Labslink Research News

Protein recognition and disorder: A debate

Fri, 11 Jan 2013 13:39:17 PDT

The extent to which three-dimensional structure is required for protein recognition and function is an
area of vigorous debate with clear implications for protein engineering. Two differing viewpoints have
been put forward in two articles published in F1000 Biology Reports today........> Full story

No evidence for 30-nm chromatin fibers in the mouse genome

Thu, 04 Oct 2012 16:51:45 PDT

Scientists in Canada and the United States have used three-dimensional imaging techniques to settle a long-standing debate about how DNA and structural proteins are packaged into chromatin fibres. The researchers, whose findings are published in EMBO reports, reveal that the mouse genome consists of 10-nm chromatin fibres but did not find evidence for the wider 30-nm fibres that were previously thought to be important components of the DNA architecture........> Full story

Computer viruses could take a lesson from showy peacocks

Wed, 29 Aug 2012 14:50:45 PDT

Computer viruses are constantly replicating throughout computer networks and wreaking havoc. But what if they had to find mates in order to reproduce?.......> Full story

Oxygen-deprived baby rats fare worse if kept warm

Mon, 13 Feb 2012 16:41:17 PDT

Premature infants’ immature lungs and frequent dips in blood pressure make them especially vulnerable to a condition called hypoxia in which their tissues don’t receive enough oxygen, sometimes leading to permanent brain damage.......> Full story

Meet the beetles: Social networks provide clues to natural selection

Mon, 30 Jan 2012 19:07:33 PDT

Think of them as a group of guys, hanging out together, but not spending much time with the ladies, nor getting much "action." Except these "guys" are forked fungus beetles......> Full story

Mysterious monkey re-discovered in Borneo

Fri, 20 Jan 2012 17:04:52 PDT

Simon Fraser University PhD student Brent Loken was hoping to capture images of the elusive Bornean clouded leopard when he set up a camera trap in the rainforest. Instead, he made the re-discovery of a lifetime.........> Full story

Fly named in honor of Beyonce

Fri, 13 Jan 2012 17:34:25 PDT

According to the Australian National Insect Collection researcher responsible for officially ‘describing’ the fly as Scaptia (Plinthina) beyonceae, CSIRO’s Bryan Lessard, the fly’s spectacular gold colour makes it the “all time diva of flies”.......> Full story

Using radiation to sterilize insect pests may protect California fruits and vegetables

Wed, 30 Nov 2011 18:08:41 PDT

A new study published in the Journal of Economic Entomology shows that radiation can be used to effectively sterilize the light brown apple moth (LBAM), an insect pest found in Australia, New Zealand, California, Hawaii, Sweden, and the British Isles.......> Full story

Body rebuilding: Researchers regenerate muscle in mice

Tue, 29 Nov 2011 17:38:08 PDT

A team of scientists from Worcester Polytechnic Institute (WPI) and CellThera, a private company located in WPI's Life Sciences and Bioengineering Center, have regenerated functional muscle tissue in mice, opening the door for a new clinical therapy to treat people who suffer major muscle trauma........> Full story

'Skin bones' helped large dinosaurs survive, new study says

Tue, 29 Nov 2011 17:36:24 PDT

Bones contained entirely within the skin of some of the largest dinosaurs on Earth might have stored vital minerals to help the massive creatures survive and bear their young in tough times, according to new research by a team including a University of Guelph scientist........> Full story

Report: Herbicide atrazine spurs reproductive problems in many creatures

Mon, 28 Nov 2011 17:19:33 PDT

An international team of researchers has reviewed the evidence linking exposure to atrazine – an herbicide widely used in the U.S. and more than 60 other nations – to reproductive problems in animals. The team found consistent patterns of reproductive dysfunction in amphibians, fish, reptiles and mammals exposed to the chemical.......> Full story

More than 50 percent decline in elephants in eastern Congo due to human conflict: UBC research

Thu, 10 Nov 2011 17:18:45 PDT

Humans play a far greater role in the fate of African elephants than habitat, and human conflict in particular has a devastating impact on these largest terrestrial animals, according to a new University of British Columbia study published online in PLoS ONE this week.......> Full story

UC research finds that a duck's boon might be a turtle's bane

Thu, 03 Nov 2011 18:48:55 PDT

That was the discovery made by University of Cincinnati Educator Associate Professor Denis Conover, of the Department of Biological Sciences in UC's McMicken College of Arts and Sciences, when he came upon a duck nest box in the wetlands of southern Ohio's Miami Whitewater Forest. The box had tipped over. Turtle corpses were strewn about the mud and mire surrounding the fallen nesting box. Several species of turtles had been trapped by the box, and not all of them made it out alive........> Full story

Bigger birds in Central California, courtesy of global climate change

Mon, 31 Oct 2011 18:09:05 PDT

Birds are getting bigger in central California, and that was a big surprise for Rae Goodman and her colleagues........> Full story

New therapy protects monkeys from Hendra virus

Wed, 19 Oct 2011 17:12:13 PDT

A new treatment for the deadly Hendra virus has proven successful in primate tests — a major step forward in combating the virus, which kills about 60 percent of those it infects and has been implicated in sporadic outbreaks in Australia ever since it was first identified in 1994. Researchers from the University of Texas Medical Branch at Galveston, Rocky Mountain Laboratories, the National Institute of Allergy and Infectious Diseases, the National Institutes of Health, the Uniformed Services University of the Health Sciences, the National Cancer Institute, and the Boston University School of Medicine teamed up to develop and test the new therapy, in a project primarily supported by a grant awarded to UTMB professor Thomas Geisbert by the NIAID. Experiments were conducted at RML in a biosafety level 4 "spacesuit" lab, because no licensed vaccine or therapy currently exists for Hendra. Researchers infected 14 African green monkeys — chosen because their response to Hendra is very similar to that of humans — with the virus. At varying time intervals after infection, 12 of the monkeys were then given doses of a human antibody designated m102.4, which had been specially selected for its affinity for Hendra. Earlier test tube and small-animal experiments by USUHS professor Christopher Broder and colleagues in Australia had strongly suggested that m102.4 antibodies would bind to proteins on the surface of Hendra virus particles and block the process by which the virus invades cells. This turned out to be the case with the monkeys as well, and all 12 of the treated animals survived — including a group not given their first dose of antibodies until three days after infection with Hendra. "I think this is a very promising therapy, especially when you consider that it was still strong three days later," said Geisbert, one of the lead authors of a paper on the work published online Oct. 19 in Science Translational Medicine. "What's also interesting is that this antibody has strong activity against Nipah virus as well, which is extremely similar to Hendra." Both Hendra and Nipah primarily reside in fruit bats, and both are extraordinarily dangerous to humans. (If the virus names sound familiar to moviegoers, it's not an accident: director Stephen Soderbergh used an imaginary combination between Hendra and Nipah to create the virus in the recent film Contagion.) But while Hendra primarily affects horses, which can spread the disease to humans, Nipah has evolved to be transmissible directly from human to human. First identified in Malaysia in 1998, Nipah is blamed for 251 deaths in outbreaks in Malaysia, India and Bangladesh. "Here at UTMB's Galveston National Laboratory we're currently looking at the efficacy of this antibody against Nipah," Geisbert said. "That would make it even more valuable." Last year m102.4 was requested for emergency use in Australia to protect a woman and her daughter from an exposure to Hendra. Both survived and showed no side effects from the treatment. Much more extensive testing would be required, though, to obtain approval for m102.4 as a therapy. According to GNL director James LeDuc, the facility is well prepared to move forward with such efforts. "Collaboration between federal and university scientists has been instrumental in producing this novel breakthrough," LeDuc said. "We're ready to help in the next steps in translating this discovery into a usable treatment."

Is chivalry the norm for insects?

Fri, 07 Oct 2011 17:42:36 PDT

The long-standing consensus of why insects stick together after mating has been turned on its head by scientists from the University of Exeter. Published today (6 October) in Current Biology, their study shows that, contrary to previous thinking, females benefit from this arrangement just as much as males. Instead of dominating their female partners through bullying and aggressive behaviour, males were revealed to be protective, even laying their lives on the line when their mates faced danger. Previously, scientists assumed that male insects stay close to females after mating to stop them from taking other partners. Female insects have multiple mates and the last mate is most likely to fertilise her eggs. Therefore, by preventing females from taking other mates a male is most likely to father her offspring. To gain insight into the lives of wild field crickets, the research team used digital video technology, tagging and DNA fingerprinting. They analysed over 200,000 hours of infra-red video footage, taken over two entire breeding seasons, to get a detailed picture of the daily dramas that occur in the insect world. The researchers found no evidence of males being aggressive towards their mates or hindering a female's movements to or from their burrow. They also discovered that a male will risk his own life to protect a female by allowing her to scamper into their burrow before him when escaping from predators such as birds. "Relationships between crickets are rather different from what we'd all assumed. Rather than being bullied by their mates, it seems that females are in fact being protected. We could even describe males as 'chivalrous'. "Males and females on their own have similar predation rates, but when they are in pairs, males are killed much more frequently and females always survive to predator attacks. "It's not completely altruistic though – males are still benefiting. Even if a male is killed, the surviving female is carrying his sperm and ensuring that his DNA lives on." The team used 96 cameras and microphones to monitor a population of Gryllus campestris crickets in Northern Spain over three entire springs. Super-glued to the back of every cricket was a tiny numbered placard, just big enough for the camera to read. Additionally, a tiny piece of leg tissue less than one millimeter across was used to create a DNA fingerprint of each individual. The visible tags allowed the researchers to analyse their lives and behaviour, including mating partners, how long particular males and females spent together, the time that each male spent singing to attract females and the fights that occur when a male approaches a burrow occupied by another male. Professor Tom Tregenza of the University of Exeter said: "Males were protective of their partners, but very aggressive with potential competitors. Males cohabiting with a female won more fights against approaching rival males than when they were on their own. "The footage we filmed and spent months analysing has given us a rare glimpse into how natural selection really happens in the wild. Although our study focused on one population, it is likely that our findings are applicable to other species across the insect world and could even have relevance for other animals. Perhaps females aren't getting pushed around quite as much as we thought they were."

Flight patterns reveal how mosquitoes find hosts to transmit deadly diseases

Fri, 30 Sep 2011 18:29:23 PDT

The carbon dioxide we exhale and the odors our skins emanate serve as crucial cues to female mosquitoes on the hunt for human hosts to bite and spread diseases such as malaria, dengue and yellow fever. Two entomologists at the University of California, Riverside have now performed experiments to study how female Aedes aegypti -- mosquitoes that transmit yellow fever and dengue -- respond to plumes of carbon dioxide and human odor. The researchers report in the October 15 issue of the Journal of Experimental Biology that puffs of exhaled carbon dioxide first attract these mosquitoes, which then proceed to follow a broad skin odor plume, eventually landing on a human host. The results from the study by Ring Cardé, a distinguished professor of entomology at the University of California, Riverside, and Teun Dekker, formerly a graduate student in Cardé's lab and now an assistant professor at the Swedish University of Agricultural Research, could clue scientists on how odors can be used in traps for intercepting and capturing host-seeking mosquitoes. Yellow fever is a viral disease that causes 30,000 deaths worldwide each year. Dengue, another viral disease, infects 50 to 100 million people worldwide a year, leading to half a million hospitalizations, and 12,500,000 deaths. In the lab, the researchers released female yellow fever mosquitoes into a wind tunnel they built, and filmed their flight paths. They found that:

Mosquitoes head upwind only briefly when they encounter just a whiff of carbon dioxide but proceed continuously upwind when the carbon dioxide plume is turbulent, fluctuating in concentration and mimicking the presence of a live host.
Mosquitoes' orientation to human skin odor, in contrast, is optimal when the plume of skin odor is broad and unvarying in its intensity, as would occur when a mosquito closes in on a potential host.

"Carbon dioxide induces a faster and more direct upwind orientation than skin odor," said Cardé, who holds the Alfred M. Boyce Chair in Entomology. "Our experiments show that the response of yellow fever mosquitoes to skin odor requires an exposure longer than that of carbon dioxide to induce upwind flight." Dekker and Cardé also report that the dynamics -- response time, duration and speed -- of carbon dioxide-induced upwind surging were very similar across a wide range of carbon dioxide concentrations, from 100 to 0.05 percent (barely above atmospheric levels). "The mosquitoes' carbon dioxide receptors allow the insects to respond almost instantly to even the slightest amount of the gas," Cardé said. "Carbon dioxide alone attracts these mosquitoes and does not require assistance from other odors. Skin odors, however, become important when the mosquito is near the host, selecting biting sites. Further, the mosquitoes' sensitivity to skin odors increases 5- to 25-fold after 'priming' with a whiff of carbon dioxide."

'Heat-proof' eggs help turtles cope with hot beaches

Mon, 26 Sep 2011 20:12:09 PDT

Sea turtles face an uncertain future as a warming climate threatens to reduce their reproductive viability. However, new research led by the University of Exeter and published this week in Proceedings of the Royal Society B shows that some turtles are naturally heat-tolerant. The study focused on green turtles nesting on Ascension Island, a UK overseas territory in the South Atlantic Ocean. Scientists from the Universities of Exeter and Groningen found that eggs laid by turtles nesting on a naturally hot beach withstand high temperatures better than eggs from turtles nesting on a cooler beach just a few kilometres away. The warmer beach has dark sand, whereas the neighbouring beach is two to three degrees Celsius cooler because it has white sand. Green turtles travel from the coast of South America to the tiny island to nest. Most female turtles nest on the beaches where they themselves hatched, so populations can become adapted to specific nesting locations. The researchers placed some of the eggs laid on each beach into incubators of either 32.5 degrees Celsius or 29 degrees Celsius and monitored their progress. They found that the eggs from the warmer beach were better able to thrive in the hot incubator than those from the cooler beach. Dr Jonathan Blount, who led the research, said: "We believe this is the first time that adaptation to local environmental conditions has been demonstrated in sea turtles, which is all the more remarkable because the beaches in question are just six kilometres apart". Heat-tolerant populations may be crucial in allowing species to adapt to a warming world, highlighting the need for conservation strategies which protect diversity in animal populations. University of Exeter PhD student Dr Sam Weber, lead author of the study, said: "Such adaptations probably evolve over many generations, so whether turtle evolution can keep pace with the rapid climate change that scientists have predicted remains to be seen. However, occasional movements of heat-adapted turtles to other nesting sites could help to spread their favourable genes."

First lizard genome sequenced

Wed, 31 Aug 2011 17:33:00 PDT

The green anole lizard is an agile and active creature, and so are elements of its genome. This genomic agility and other new clues have emerged from the full sequencing of the lizard's genome and may offer insights into how the genomes of humans, mammals, and their reptilian counterparts have evolved since mammals and reptiles parted ways 320 million years ago. The researchers who completed this sequencing project reported their findings August 31 online in the journal Nature. The green anole lizard (Anolis carolinensis) – a native of the Southeastern United States – is the first non-bird species of reptile to have its genome sequenced and assembled. Broad researchers have assembled and analyzed more than 20 mammalian genomes – including those of some of our closest relatives – but the genetic landscape of reptiles remains relatively unexplored. "Sometimes you need to be at a certain distance in order to learn about how the human genome evolved," said Jessica Alföldi, co-first author of the paper and a research scientist in the vertebrate genome biology group at the Broad Institute. "You have to look out further than you were looking previously." Lizards are more closely related to birds – which are also reptiles – than to any of the other organisms whose genomes have been sequenced in full. Like mammals, birds and lizards are amniotes, meaning that they are not restricted to laying eggs in water. "People have been sequencing animals from different parts of the vertebrate tree, but lizards had not been previously sampled," said Kerstin Lindblad-Toh, scientific director of vertebrate genome biology at the Broad and senior author of the Nature paper. "This was an important branch to look at." Four hundred species of anole lizards have fanned out across the islands of the Caribbean, North America, Central America, and South America, making them an appealing model for studying evolution. Although much is known about their biology and behavior, genomic information may be a critical missing piece for understanding how the lizards have become so diverse. "Anoles are rich in ecology and morphology and have just the right amount of diversity to make them interesting yet tractable to study," said Jonathan Losos, an author of the paper, professor at Harvard University, and author of the book Lizards in an Evolutionary Tree: Ecology and Adaptive Radiation of Anoles. "But a big stumbling block in studying them has been that they have not been great organisms for classical genetic study. The genome is going to revolutionize our ability to study that aspect of their evolutionary diversification." One of the questions this newly sequenced genome may help resolve has to do with the origin of conserved, non-coding elements in the human genome. These regions do not contain protein-coding genes but are thought to have critical roles since they have remained unchanged for millennia. Scientists wondered where these mysterious elements came from and hypothesized that they may be the relics of transposons – jumping stretches of DNA that were at one time able to copy and paste themselves throughout the genome. In humans, many of these so called "jumping genes" have lost their jumping ability, but in anole lizards, they continue to hop. "Anoles have a living library of transposable elements," said Alföldi. The researchers aligned these mobile elements to the human genome, and found that close to 100 of the human genome's non-coding elements are derived from these jumping genes. "In anoles, these transposons are still hopping around, but evolution has used them for its own purposes, turning them into something functional in humans." In addition to insights into human and mammalian genomes, the anole lizard's genome also offers up clues about how lizard species evolved to populate islands in the Greater Antilles. Much like Darwin's finches, anoles adapted to fill all of the ecological niches the islands have to offer. Some lizards have short legs and can walk along narrow twigs; others are green in color with big toe pads suited for living high up in trees; others are yellow and brown and live in the grass. But unlike the finches, lizards on different islands have independently evolved diverse communities of these twig, canopy, and grass dwelling species – almost identical lizard species have evolved in parallel on the islands of Hispaniola, Puerto Rico, Cuba, and Jamaica. "These lizards have been compared to Darwin's finches and in many respects they are similar," said Losos. "They show the workings of natural selection as species adapted to different habitats. But the difference is in the case of the lizards, this evolution has happened four times, once on each of the different islands." By sampling the genomes of more than 90 species, the researchers were able to make a preliminary map of how these species evolved to colonize the islands. "This is setting the stage for the research community to be able to look for signatures of adaptation in a very informative and well thought through way," said Lindblad-Toh. The researchers were also able to create a parts list of proteins found in green anole eggs, which they compared with those found in eggs from chickens and found that both bird and lizard egg genes are evolving rapidly. They also found many genes in the anoles genome associated with color vision, which anoles rely on to identify choice mates (males and females of some species display vividly colored flaps of skin beneath their necks called dewlaps). "Anoles have extremely good color vision – some species can even see in the ultraviolet range," said Losos. Other studies have shown that anoles can distinguish between similar colors and patterns. "It's pretty clear that one function of the dewlap is to distinguish one species from others and that they use the dewlap to determine whether another individual is in another species or not." The researchers performed the first analysis of several other unusual features in the anole genome, including microchromosomes – tiny chromosomes sometimes found in reptiles, amphibians, and fish but never in mammals. They also found a complete lack of isochores, regions of the genome with high or low concentrations of the nucleotides "G" (guanine) and "C" (cytosine) which give human chromosomes a distinct banding pattern. Additionally, the team found the sex chromosomes of the lizard – something that researchers had only been able to hypothesize about before. Like mammals, green anoles appear to have XX and XY chromosomes (unlike birds, in which males have two identical sex chromosomes called ZZ and females have two different ones known as ZW). The lizard's X chromosome turned out to be one of its many microchromosomes. Each of these insights is the fruit of collaborative efforts among scientists with expertise in the study of proteins, gene family evolution, green anole behavior and biology, computational analysis, and more. "This work represents a partnership between biologists and computational biologists," said Federica Di Palma, a co-first author of the paper and assistant director of the Broad's vertebrate genome biology group. "We were able to leverage all of these views to gain insight into genome evolution in general."

UCI-led butterfly study sheds light on convergent evolution

Thu, 21 Jul 2011 18:34:23 PDT

For 150 years scientists have been trying to explain convergent evolution. One of the best-known examples of this is how poisonous butterflies from different species evolve to mimic each other's color patterns – in effect joining forces to warn predators, "Don't eat us," while spreading the cost of this lesson. Now an international team of researchers led by Robert Reed, UC Irvine assistant professor of ecology & evolutionary biology, has solved part of the mystery by identifying a single gene called optix responsible for red wing color patterns in a wide variety of passion vine butterfly species. The result of 10 years of work, the finding is detailed in a paper that appears online today in the journal Science. "This is our first peek into how mimicry and convergent evolution happen at a genetic level," Reed said. "We discovered that the same gene controls the evolution of red color patterns across remotely related butterflies. "This is in line with emerging evidence from various animal species that evolution generally is governed by a relatively small number of genes. Out of the tens of thousands in a typical genome, it seems that only a handful tend to drive major evolutionary change over and over again." The scientists spent several years crossbreeding and raising the delicate butterflies in large netted enclosures in the tropics so they could map the genes controlling color pattern. UCI postdoctoral researcher Riccardo Papa (now an assistant professor at the University of Puerto Rico, Rio Piedras) then perfected a way to analyze the genome map by looking at gene expression in microdissected butterfly wings. Finding a strong correlation between red color patterns and gene expression in one small region of the genome was the breakthrough that led to discovery of the gene. Population genetics studies in hybrid zones, where different color types of the same species naturally interbreed, confirmed it. "Biologists have been asking themselves, 'Are there really so few genes that govern evolution?'" Reed said. "This is a beautiful example of how a single gene can control the evolution of complex patterns in nature. Now we want to understand why: What is it about this one gene in particular that makes it so good at driving rapid evolution?"

Wired for sound: A small fish's brain illustrates how people and other vertebrates produce sounds

Tue, 14 Jun 2011 17:54:31 PDT

Cornell researchers have identified regions of a fish brain that reveal the basic circuitry for how humans and other vertebrates generate sound used for social communication. In a study of midshipman fish, published online today (June 14) in Nature Communications, the researchers identified two distinct groups of neurons that independently control the duration and the frequency of sounds used for calling. While human speech and bird songs are far more complex than the grunts and hoots produced by some fish, the study provides a very basic wiring diagram of how the brain allows vertebrates to vocalize. "If you can understand the simplest system, it provides a road map for understanding the fundamental working units in the central nervous system for how you build a vocal system," said Andrew Bass, Cornell professor of neurobiology and behavior and senior author of the paper. In a 2008 Science paper, Bass and colleagues identified this same region of the brain in larval midshipman fish, showing how it is present in the brains of other animals, including primates. This suggests that the vocal networks in all vertebrates evolved from an ancestrally shared brain area that originated in fishes. "Studies like these allow us to trace the evolutionary history of the brain," Bass said. "All animals, including humans, share many brain circuits for complex behaviors, including the use of sounds for social communication."

Animals have personalities, too

Sun, 01 May 2011 18:47:43 PDT

An individual's personality can have a big effect on their life. Some people are outgoing and gregarious while others find novel situations stressful which can be detrimental to their health and wellbeing. Increasingly, scientists are discovering that animals are no different. A new study led by Dr Kathryn Arnold, of the Environment Department at the University of York has added important experimental evidence showing that animal personalities are reflected in their oxidative stress profiles. The research is published in the Journal of Experimental Biology. Dr Arnold teamed up with graduate student Katherine Herborn, at the Institute of Biodiversity, Animal Health and Comparative Medicine at the University of Glasgow, to classify the personalities of 22 greenfinches. They tested each bird's reactions to a novel situation by adding a brightly coloured cookie-cutter to each greenfinch's food bowl, and timing how long it took for the birds to pluck up courage to approach the food. The researchers found that the boldest birds took only a few seconds to overcome their fear while more timid birds took up to 30 minutes to approach their meal. Dr Arnold and Katherine Herborn also measured the greenfinches' motivation to explore by attaching an intriguing object to the birds' perches and timing how long it took them to land next to it. However, there was no correlation between the birds' courage and curiosity. The researchers then measured the birds' damaging reactive oxygen metabolite levels and their defences against them. Comparing the bird's blood oxidative profiles with their personalities, the team found that the most timid birds had the highest levels of damaging oxygen toxins and the weakest defences, so they suffered more oxidative stress than braver individuals. Also, the scientists found that the most curious birds (those that approached objects fastest) had better defences against oxidative damage than less curious greenfinches. Dr Arnold wants to extend the work to establish how personality traits affects birds in the wild. She says, "Neophobic birds – those that are afraid of new things -- may suffer high costs of oxidative stress and die early because they paid these physiological costs, but they might also be less likely to be eaten by a predator because they are more wary than bolder birds ."

BU researchers probe link between theta rhythm and ability of animals to track location

Thu, 28 Apr 2011 18:00:49 PDT

In a paper to be published today [April 29, 2011] in the journal Science, a team of Boston University researchers under the direction of Michael Hasselmo, professor of psychology and director of Boston University's Computational Neurophysiology Laboratory, and Mark Brandon, a recent graduate of the Graduate Program for Neuroscience at Boston University, present findings that support the hypothesis that spatial coding by grid cells requires theta rhythm oscillations, and dissociates the mechanisms underlying the generation of entorhinal grid cell periodicity and head-direction selectivity. Theta Rhythm - The hippocampal theta rhythm is an oscillation that can be observed in EEG recordings from the hippocampus and other brain structures in numerous species of mammals including rodents, rabbits, dogs, cats, bats, and marsupials. In rats, the most frequently studied species, theta rhythmicity is easily observed in the hippocampus, but can also be detected in numerous other cortical and subcortical brain structures. Hippocampal theta, with a frequency range of 6-10 Hz, appears when a rat is engaged in active motor behavior such as walking or exploratory sniffing, and also during REM sleep. Models have proposed a role for theta rhythm in spatial navigation and episodic memory function. Grid cells and Self-Localization – Early studies on navigation revealed that most animals have an exceptional ability to keep track of their location, even in complete darkness. Research now suggests that this ability may involve computations in the entorhinal cortex. Single cell recordings from the entorhinal cortex during navigation have revealed a specific type of neuron that is able to track a rat's position. These cells have been termed 'grid cells' based on the fact that they fire when the rat is at regularly spaced locations in the environment, forming a hexagonal 'grid' in the environment. These cells might allow animals to keep track of their current location. Computational neuroscientists, including Michael Hasselmo, have demonstrated how these grid cells could generate this regular spatial pattern based on theta oscillations in models. The models proposed that theta oscillations in the entorhinal cortex provide a baseline clocking mechanism. The model requires input from other cells that respond based on the current head direction of the animal or its current running speed. In the model, running speed and head direction inputs modulate the frequency of other oscillators, such that when these oscillations interact to influence the firing of a grid cell, they cause the grid cell to fire systematically dependent on the location of the animal. Brandon et al., support this theoretical model by demonstrating that grid cells in the entorhinal cortex need the theta rhythm as a clock to help keep track of the animal's location. In the article, "Reduction of Theta Rhythm Dissociates Grid Cell Spatial Periodicity from Directional Tuning," Brandon et al., report that grid cells recorded in the medial entorhinal cortex of freely moving rats exhibit firing at regular spatial locations and temporal modulation with theta rhythm oscillations (4 to 11 hertz). The researchers analyzed grid cell spatial coding during reduction of network theta rhythm oscillations caused by inactivation of the medial septum (MS) with the drug muscimol. During MS inactivation, grid cells lost their spatial periodicity, whereas head-direction cells maintained their direction signal. Conjunctive grid–by–head-direction cells lost grid cell spatial periodicity but retained head-direction specificity. All cells showed reduced rhythmicity in autocorrelations and cross-correlations. This finding provides experimental support for the role of oscillations in coding spatial location by neural circuits. Consistent with this data, other laboratories have shown that the same manipulation of MS that reduces theta rhythm can severely disrupt the behavioral ability of a rat to remember the location of prior events. The alteration of oscillatory dynamics in the entorhinal cortex could underlie impairments in the ability to remember the spatial location of events in an episode. For example, drugs that cause amnesia may do so through an influence on theta rhythm oscillations, and a change in oscillations could contribute to the influence of Alzheimer's disease on the formation of new memories.

Mutated gene found in dog disease the same in humans, MU researchers find

Mon, 18 Apr 2011 20:30:39 PDT

University of Missouri researchers believe both man and animal will benefit from their discovery that the same gene mutation found in Tibetan Terrier dogs can also be found in a fatal human neurological disorder related to Parkinson’s disease........> Full story

Nicotine does not promote lung cancer growth in mouse models

Mon, 04 Apr 2011 17:59:54 PDT

Nicotine at doses similar to those found in most nicotine replacements therapies did not increase lung cancer tumor incidence, frequency or size, according to results of a mouse study presented at the AACR 102nd Annual Meeting 2011, held here April 2-6. "If you take our data and combine it with epidemiological data from Europe, even in people who quit smoking and maintain the use of nicotine replacement therapy for months or years, there does not appear to be increased lung cancer incidence," said Phillip A. Dennis, M.D., Ph.D., senior investigator at the medical oncology branch of the National Cancer Institute. "This suggests that nicotine replacement therapy is probably safe and is certainly safer than smoking." According to Dennis, about 20 percent of all smokers are truly addicted to tobacco. In these people, the use of nicotine replacement therapy has markedly helped them to quit smoking. The current Food and Drug Administration indication for most nicotine replacement therapies, such as a nicotine patch, is limited to 10 to12 weeks. There is a subset of smokers who will need to stay on nicotine replacement therapy longer in order to appease addiction, according to Dennis. However, expanding the use of this therapy is controversial. Research to date has linked nicotine to cancer in various ways, including laboratory studies that indicate nicotine promotes the growth or spread of tumor cells or that it helps transform normal lung airway cells into cancerous cells, according to Dennis. Therefore, the researchers conducted a study in mice to determine if nicotine had any tumor-promoting effects. Three groups of mice were administered nicotine in drinking water for up to 12 weeks. In the first group, the mice were administered three weekly injections of NNK, a known tobacco carcinogen, prior to receiving nicotine. The second group of mice was genetically engineered to have activation of the KRAS oncogene, which is frequently mutated in lung cancers derived from smokers. The third group was made up of mice that were given cell lines derived from mouse lung cancers. The researchers found that all the mice had normal water consumption. Cotinine, a metabolite of nicotine, was found to be at a level that is comparable to levels found in nicotine replacement users. "We observed that there was no effect of nicotine on the mice in all three groups," said Dennis. "Nicotine did not increase tumor incidence, multiplicity or size." At the levels measured in mice, nicotine did not activate signaling pathways associated with lung cancer that had been shown to be activated by high concentrations of nicotine. "Based on our study and human epidemiological studies to date, nicotine replacement therapy is probably a safe option," he suggested.

New research suggests wild birds may play a role in the spread of bird flu

Fri, 25 Mar 2011 03:23:54 PDT

Wild migratory birds may indeed play a role in the spread of bird flu, also known as highly pathogenic avian influenza H5N1. A study by the U.S. Geological Survey, the United Nations Food and Agriculture Organization and the Chinese Academy of Sciences used satellites, outbreak data and genetics to uncover an unknown link in Tibet among wild birds, poultry and the movement of the often-deadly virus.......> Full story

MIT systems biologists use computer models to predict animal cell behavior

Thu, 24 Mar 2011 03:30:47 PDT

Biological systems, including cells, tissues and organs, can function properly only when their parts are working in harmony. These systems are often dauntingly complex: Inside a single cell, thousands of proteins interact with each other to determine how the cell will develop and respond to its environment.

To understand this great complexity, a growing number of biologists and bioengineers are turning to computational models. This approach, known as systems biology, has been used successfully to model the behavior of cells grown in laboratory dishes. However, until now, no one has used it to model the behavior of cells inside a living animal.......> Full story

Study shows how chickens keep their cool

Wed, 16 Mar 2011 07:10:21 PDT

Its head looks like a turkey's, its body resembles a chicken's – now scientists can explain why one of the poultry world's most curious specimens has developed such a distinctive look. The Transylvanian naked neck chicken – once dubbed a Churkey or a Turken because of its hybrid appearance – has developed its defining feature because of a complex genetic mutation. Researchers at The Roslin Institute at The University of Edinburgh found that a vitamin A-derived substance produced around the bird's neck enhanced the effects of the genetic mutation. This causes a protein – BMP12 – to be produced, suppressing feather growth and causing the bird to have an outstanding bald neck. The findings could help poultry production in hot countries, including in the developing world, because chickens with naked necks are much better equipped to withstand the heat. The discovery also has implications for understanding how birds – including vultures – evolved to have featherless necks due to their metabolism of vitamin A selectively in neck skin. Transylvanian naked necks, which are thought to have originated from the north of Romania, have been around for hundreds of years and were introduced to Britain in the 1920s. The research, published in the journal PLoS Biology, was funded by the Biotechnology and Biological Sciences Research Council. Dr Denis Headon, who led the research at The Roslin Institute, said: "Not only does this help our understanding of developmental biology and give insight into how different breeds have evolved but it could have practical implications for helping poultry production in hot countries including those in the developing world." Researchers analysed DNA samples from naked neck chickens in Mexico, France and Hungary to find the genetic mutation. Skin samples from embryonic chickens were also analysed using complex mathematical modelling to identify the genetic trigger.

UF study traces global red imported fire ant invasions to southern US

Fri, 25 Feb 2011 03:29:40 PDT

Red imported fire ant invasions around the globe in recent years can now be traced to the southern U.S., where the nuisance insect gained a foothold in the 1930s, new University of Florida research has found. Native to South America, the ant had been contained there and in the southeastern U.S. before turning up in faraway places in the last 20 years — including California, China, Taiwan, Australia and New Zealand. The study in Friday's edition of Science was co-authored by Marina Ascunce, a postdoctoral associate with the Florida Museum of Natural History on the UF campus and Chin-Cheng Yang of National Taiwan University. The team's findings could prove helpful in finding new ways to control the invasive species, Solenopsis invicta, Ascunce said. Americans spend more than $6 billion a year to control the ants and offset damage they cause, including medical expenses and $750 million in agricultural losses. "Fire ants are very annoying pests, and they cause people to suffer," Ascunce said. "People who are allergic can die (from ant stings)." Red imported fire ants are highly aggressive. They have a painful sting, often discovered by humans only after stepping on a mound. The research team used several types of molecular genetic markers to trace the origins of ants in nine locations where recent invasions occurred. They traced all but one of the invasions to the southern U.S. The exception was an instance where the ants moved from the southeastern U.S. to California, then to Taiwan. Ascunce said the scientists were surprised by the findings. "I thought that at least one of the populations in the newly invaded areas would have come from South America, but all of the genetic data suggest the most likely source in virtually every case was the southern U.S.," she said. The study results show the problematic side of a robust global trade and travel network. DeWayne Shoemaker, a U.S. Department of Agriculture scientist affiliated with UF's Institute of Food and Agricultural Sciences who was senior author and lead investigator on the grant that funded the study, said pinning down precise origins for the ants is a huge win because it helps scientists know where to look to find the most effective biological control agents, such as phorid flies. Since the late 1990s, scientists have been releasing phorid flies to help control the ants while reducing use of pesticides. The flies hover over mounds before injecting an egg into an ant. When the egg hatches, the maggot develops in the ant's head, eventually decapitating it. The maggot turns into a fly and the cycle repeats. Shoemaker, a key member of the research team that sequenced the complete genome of the red imported fire ant earlier this year, said the team collected ants from 2,144 colonies at 75 geographic sites. From there, they used multiple genetic tests—including some similar to human paternity tests — to determine the ants' origin with high confidence levels. "I really think our power to distinguish … hinged on us having such a large data set," he said. "I don't think we'd have had the statistical power to come up with these kinds of conclusions otherwise. All of these conclusions are highly supported by data." It is widely believed the red imported fire ant first entered the U.S. in the 1930s through the port of Mobile, Ala., on cargo ships, possibly in dirt used as ballast.

What a rat can tell us about touch

Sat, 19 Feb 2011 14:42:50 PDT

In her search to understand one of the most basic human senses – touch – Mitra Hartmann turns to what is becoming one of the best studied model systems in neuroscience: the whiskers of a rat. In her research, Hartmann, associate professor of biomedical engineering and mechanical engineering in the McCormick School of Engineering and Applied Science at Northwestern University, uses the rat whisker system as a model to understand how the brain seamlessly integrates the sense of touch with movement. Hartmann will discuss her research in a daylong seminar "Body and Machine" at the American Association for the Advancement of Science (AAAS) annual meeting in Washington, D.C. Her presentation is part of the session, "Linking Mechanics, Robotics, and Neuroscience: Novel Insights from Novel Systems," to be held from 8:30 to 11:30 a.m. Friday, Feb. 18. Rats are nocturnal, burrowing animals that move their whiskers rhythmically to explore the environment by touch. Using only tactile information from its whiskers, a rat can determine all of an object's spatial properties, including size, shape, orientation and texture. Hartmann's research group is particularly interested in characterizing the mechanics of sensory behaviors, and how mechanics influences perception. "The big question our laboratory is interested in is how do animals, including humans, actively move their sensors through the environment, and somehow turn that sensory data into a stable perception of the world," Hartmann says. Hundreds of papers are published each year that use the rat whisker system as a model to understand neural processing. But there is a big missing piece that prevents a full understanding the neural signals recorded in these studies: no one knows how to represent the "touch" of a whisker in terms of mechanical variables. "We don't understand touch nearly as well as other senses," Hartmann says. "We know that visual and auditory stimuli can be quantified by the intensity and frequency of light and sound, but we don't fully understand the mechanics that generate our sense of touch." In order to gain a better understanding of how the rat uses its whiskers to sense its world, Hartmann's group works to both better understand the rat's behavior and to create models of the system that enable the creation of artificial whisker arrays. To determine how a rat can sense the shape of an object, Hartmann's team developed a light sheet to monitor the precise locations of the whiskers as they came in contact with the object. Using high-speed video, the team can also analyze how the rat moves its head to explore different shapes. More recently, Hartmann's team has created a model that establishes the full structure of the rat head and whisker array. This means that the team can now simulate the rat "whisking " into different objects, and predict the full range of inputs into the whisker system as a rat encounters an object. The simulations can then be compared against real behavior, as monitored with the light sheet. These advances will provide insight into the sense of touch, but may also enable new technologies that could make use of the whisker system. For example, Hartmann's lab created arrays of robotic whiskers that can, in several respects, mimic the capabilities of mammalian whiskers. The researchers demonstrated that these arrays can sense information about both object shape and fluid flow. "We show that the bending moment, or torque, at the whisker base can be used to generate three-dimensional spatial representations of the environment," Hartmann says. "We used this principle to make arrays of robotic whiskers that in replicate much of the basic mechanics of rat whiskers." The technology, she said, could be used to extract the three-dimensional features of almost any solid object. Hartmann envisions that a better understanding of the whisker system may be useful for engineering applications in which vision is limited. But most importantly, a better understanding of the rat whisker system could translate into a better understanding of ourselves. "Although whiskers and hands are very different, the basic neural pathways that process tactile information are in many respects similar across mammals," Hartmann says. "A better understanding of neural processing in the whisker system may provide insights into how our own brains process information."

Scientists uncover surprising features of bear hibernation

Fri, 18 Feb 2011 03:26:13 PDT

Black bears show surprisingly large and previously unobserved decreases in their metabolism during and after hibernation according to a paper by scientists at the Institute of Arctic Biology at the University of Alaska Fairbanks and published in the 18 February issue of the journal Science. "In general, an animal's metabolism slows to about half for each 10 degree (Celsius) drop in body temperature. Black bears' metabolism slowed by 75 percent, but their core body temperature decreased by only five to six degrees," said Øivind Tøien, IAB research scientist and lead author. The amount of metabolic suppression was a surprise since the decrease in body temperatures of hibernating bears was moderate. Tøien and colleagues were also surprised when the bears' metabolism remained suppressed for several weeks after the animals emerged from their dens. Interest in the physiology of human-sized hibernators like black bears extends beyond comparative biology, since application of the mechanisms of metabolic suppression to people in emergency situations could save lives. "Quickly reducing metabolic demand in victims of stroke, heart attack or trauma would put them in a stabilized, protected state to provide more time to arrange advanced, medical care. It could extend the golden hour to a golden day or longer." said Brian Barnes, IAB director and senior author of the paper. This is the first study to continuously measure the metabolic rates and body temperatures of black bears as they hibernated during the winter under natural conditions and after they emerged from their dens in spring. Technical limitations have previously prevented continuous long-term monitoring of such large animals. The study included five American black bears, which were nuisance bears captured in south-central and Interior Alaska by the Alaska Department of Fish and Game. Tøien and colleagues implanted radio transmitters into each bear to record its body temperature, heart beats and muscle activity. The bears were kept in structures mimicking dens, away from human disturbance, and monitored via infrared cameras. "We measured the bears' metabolism by continuously measuring the oxygen and carbon dioxide concentrations of the air entering and leaving the den," Tøien said The transmitters inside each bear told us that the bear's body temperature was not stable, but varied over the winter in slow cycles each lasting several days." "Such large, multi-day fluctuations in core body temperature are unlike those observed in any other mammal before. This detail was missed by past studies, and may have caused overestimation of metabolic rate because bears periodically shiver when they increase their body temperature," Tøien said. Hibernating bears only breathe one to two times per minute and their heart slows between breaths; sometimes there is 20 seconds between beats. "Each time the bear takes a breath, the heart accelerates for a short time to almost that of a resting bear in summer," said Tøien. "When the bear breathes out, the heart slows down again and there will be another 30 to 60 seconds until the next breath." Tøien and colleagues had expected to find the animals' metabolism returning to normal levels right away when the bears resumed activity and emerged from their dens in spring just like a small hibernator such as the arctic ground squirrel would do. "We were surprised to find that the bears' metabolic rates were still only about half of their normal, summer levels even though body temperature had returned to near normal of 37°C," Tøien said. They continued to monitor the bears' metabolism for another month after emergence and observed that it took the bears two to three full weeks to stabilize at their summer metabolic levels. "Free-ranging bears one may encounter out in the woods in early spring may be in a transition state," Tøien said. Toien, Barnes and collaborators will continue studies to determine the changes in gene expression that accompany transitions in hibernating state in black bears and whether protection of tissues can be activated during the summer.

Firefly glow: Berkeley Lab scientists develop a hydrogen peroxide probe based on firefly luciferin

Mon, 14 Feb 2011 03:22:37 PDT

A unique new probe based on luciferase, the enzyme that gives fireflies their glow, enables researchers to monitor hydrogen peroxide levels in mice and thereby track the progression of infectious diseases or cancerous tumors without harming the animals or even having to shave their fur. Developed by researchers with the Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California (UC) Berkeley, this new bioluminescent probe has already provided the first direct experimental evidence that hydrogen peroxide is continuously made even in a healthy animal.......> Full story

The most genes in an animal? Tiny crustacean holds the record

Wed, 09 Feb 2011 03:20:30 PDT

Scientists have discovered that the animal with the most genes--about 31,000--is the near-microscopic freshwater crustacean Daphnia pulex, or water flea. By comparison, humans have about 23,000 genes. Daphnia is the first crustacean to have its genome sequenced. The water flea's genome is described in a Science paper published this week by members of the Daphnia Genomics Consortium, an international network of scientists led by the Center for Genomics and Bioinformatics (CGB) at Indiana University (IU) Bloomington and the U.S. Department of Energy's Joint Genome Institute........> Full story

Death in the bat caves: UC Davis experts call for action against fast-moving disease

Thu, 03 Feb 2011 03:25:03 PDT

A team of wildlife experts led by UC Davis called today for a national fight against a new fungus that has killed more than 1 million bats in the eastern United States and is spreading fast throughout North America. "If we lose bats, we lose keystone species in some communities, predators that consume enormous numbers of insects, and beautiful wildlife species that are important parts of North America's biodiversity," said Janet Foley, a UC Davis professor of veterinary medicine at the Center for Vectorborne Diseases. Foley and her co-authors' call to action appears today online in the Early View section of the journal Conservation Biology. Bats are essential members of natural ecosystems, hunting insects, pollinating plants and scattering seeds, Foley said. "Bats do the jobs at night that birds do during the day. But because they are most active in darkness, few people are aware of how many bats live around us and how valuable they are." The new fungal disease has been named "white-nose syndrome." Scientists think the fungus, which normally lives in soil, somehow traveled to cave walls where bats hibernate in winter and began infecting the animals' facial skin and wing membranes. Sick bats appear to be coated with frost. They fly more than normal, which uses up fat reserves, and also lose water at a faster rate than normal. Disoriented, they move to exposed places, such as cave entrances. Eventually, they starve, freeze or die of dehydration. The first infected bats were found by a cave explorer near Albany, N.Y., in February 2006. Since then, infected bats have been found northward to Ontario and Quebec in Canada, south to Tennessee and west to Oklahoma. The authors write that they expect white-nose syndrome to cross the Rocky Mountains and enter California in the next several years. There are 23 species of bats in California that hibernate in caves, and so are vulnerable to white-nose syndrome. Foley said the fungus does not appear to be a threat to people or animals other than bats. The National Wildlife Health Center, a program of the U.S. Geological Survey, identified the white-nose fungus, Geomyces destructans, in 2007. "In the three years since its discovery, white-nose syndrome has changed the focus of bat conservation in North America," said Foley. "A national response is required, and our epidemiological roadmap is designed to help emerging state and national plans to combat white-nose syndrome across the United States." Foley and her collaborators developed their recommendations at a workshop in Colorado in August funded by the National Park Service. The authors' recommendations include: an outbreak investigation network that would establish a standard diagnosis and case definitions; bat population monitoring; and improved public awareness of the problem. "Scientists, policy makers and members of the public will all have a voice in the coming debate over the best course of action," Foley said. They also call for further studies of chemical and biological agents known to kill the fungus but not yet proven safe for bats, as well as study of treatments for similar diseases.

Newly decoded ant genomes provide clues on ant social life, pest control

Tue, 01 Feb 2011 03:27:06 PDT

Scientists have deciphered the genome of a persistent household pest -- the Argentine ant, an invasive species that is threatening native insects across the world. The newly sequenced genomes of the Argentine ant (Linepithema humile) and the red harvester ant (Pogonomyrmex barbatus) could provide new insights on how embryos with the same genetic code develop into either queens or worker ants and may advance our understanding of invasion biology and pest control. An international collaboration of scientists reported the results today as part of a series of three decoded ant genomes, including the Argentine ant, the red harvester ant and the fire ant published in the Proceedings of the National Academy of Sciences. In addition, the genome of the leaf‑cutter ant is scheduled for publication in the Feb. 24 issue of the Public Library of Science Genetics. See below for high-res images and how to obtain copies of the papers. "We now know that ants have the genes and genome signature of DNA methylation -- the same molecular mechanism that published honeybee studies have shown is responsible for switching whether the genome is read to be a worker or queen," said Christopher D. Smith, assistant professor of biology at San Francisco State University, an author on three of the four genome studies. Similar to bees, ants have sophisticated social structures. Queen ants typically have larger bodies, wings and fertile ovaries, and are responsible for reproduction in the colony. Worker ants are smaller, wingless and infertile, and are tasked with foraging for food and caring for the queen's offspring. Analysis of these new ant genomes suggests that chemical modification of certain sections of DNA could be responsible for the differential development of queens and workers. As an ant larva develops, DNA methylation, which involves methyl chemical groups attaching onto the DNA, may switch off the genes that control reproductive capacity and wing growth. "Our analysis suggests that ants may utilize the same genetic system as honeybees to create their social structures, although we have yet to understand whether the process works in exactly the same way across species," Smith said. Smith co-led the Argentine ant research with Neil Tsutsui of University of California, Berkeley; was a lead author on the red harvester ant genome along with Chris R. Smith of Earlham College and Jürgen Gadau of Arizona State University; and was a co-author on the leaf-cutter ant genome. Argentine ants The mapping of the Argentine ant genome may enable the development of novel pest control solutions. A better understanding of how larvae develop into queens or workers could support the development of new control methods that use more benign chemicals to limit the number of queens born in a colony, effectively sterilizing the population. Tiny, brown Argentine ants have spread to nearly every Mediterranean-type climate in the world in the last century, where they are threatening and eradicating native species and disrupting agriculture by protecting aphids that attack crops. In their native South America, aggression between Argentine ants from different nests keeps their population in check, but beyond their native range, they do not attack ants from other nests, which has allowed them to form massive "supercolonies". "The Argentine ant genome provides a reference map that may help us understand the geography and timing of their global invasion, and perhaps how they've evolved to increase insecticide resistance," Smith said. Red harvester ants Analysis of the red harvester ant genome suggests these ants have evolved "detox" genes over the course of history, developing a greater number of genes that produce the enzymes needed to digest toxic substances. The researchers explain that this evolution may have taken place 10-30 million years ago in response to the elevation of the Sierra Nevada and Andes mountain ranges, which created deserts on their eastern sides and changed the habitat of ants in the harvester ant genus. New genes related to detoxification may have been an adaptation to new habitats with a changed diet consisting of different seeds and plants. Red harvester ants are native to the Southwest United States. Their three-tier social structure consists of queen ants, "soldier" ants that work outside the nest and minor workers that stay inside the nest. Red harvester ants were found to have the largest number of odor detection genes of any known insect, with at least 344 genes related to smell compared to 166 for the honeybee and 225 in the parasitic wasp. Using their antennae to swab surfaces and creatures, ants use their sense of smell for social communication and to detect if nearby insects are friend or foe.

Brain 'GPS' illuminated in migratory monarch butterflies

Thu, 27 Jan 2011 03:26:11 PDT

A new study takes a close look at the brain of the migratory monarch butterfly to better understand how these remarkable insects use an internal compass and skylight cues to navigate from eastern North America to Mexico each fall. The research, published by Cell Press in the January 27 issue of the journal Neuron, provides key insights into how ambiguous sensory signals can be integrated in the brain to guide complex navigation. Previous research has shown that migrants use a time-compensated "sun compass" to maintain a southerly direction during flight. "In general, this sun compass mechanism proposes that skylight cues providing directional information are sensed by the eyes and that this sensory information is then transmitted to a sun compass system in the brain," explains senior study author, Dr. Steven Reppert from the University of Massachusetts Medical School. "There, information from both eyes is integrated and time compensated for the sun's movement by a circadian clock so that flight direction is constantly adjusted to maintain a southerly bearing over the day." Dr. Reppert and coauthor Dr. Stanley Heinze were interested in studying exactly how skylight cues are processed by migrating monarchs and how the skylight pattern of polarized light may provide directional information on cloudy days. "The pattern of linearly polarized skylight is arranged as concentric circles of electric field vectors (E-vectors) around the sun, and they can indicate the sun's position, even when the sun itself is covered with clouds," says Dr. Reppert. "However, the symmetrical nature of the polarized skylight pattern leads to directional uncertainty unless the pattern is integrated with the horizontal position of the sun, called the solar azimuth." Dr. Heinze compared the neuronal organization of the monarch brain sun compass network to that of the well-characterized desert locust and found it to be remarkably similar. He went on to show that individual neurons in the sun compass were tuned to specific E-vector angles of polarized light, as well as azimuth-dependent responses to unpolarized light. Interestingly, the responses of individual neurons to these two different stimuli were mediated through different parts of the monarch eye. The responses were then integrated in the sun compass part of the monarch brain to form an accurate representation of skylight cues throughout the day. "Our results reveal the general layout of the neuronal machinery for sun compass navigation in the monarch brain and provide insights into a possible mechanism of integrating polarized skylight information and solar azimuth," conclude the authors. "More generally, our results address a fundamental problem of sensory processing by showing how seemingly contradictory skylight signals are integrated into a consistent, neural representation of the environment."

Hormonal therapy for older, pregnant horses?

Tue, 25 Jan 2011 03:32:02 PDT

Most miscarriages in horses results at very early stages of pregnancy (within about three weeks) and it is generally believed that the primary cause is that the foetus grows or develops too slowly: smaller than normal embryos have a higher chance of being lost then normally sized ones. It is not clear whether low concentrations of progesterone lead to slower embryonic development but nevertheless the progestin altrenogest is routinely used to treat mares that frequently suffer miscarriages. Aurich’s group has now found that altrenogest treatment has no effect on the levels of luteinizing hormone (LH) or progesterone, hormones that are known to be important in maintaining pregnancy.......> Full story

Choosing organic milk could offset effects of climate change

Mon, 17 Jan 2011 19:46:45 PDT

Wetter, cooler summers can have a detrimental effect on the milk we drink, according to new research published by Newcastle University. Researchers found milk collected during a particularly poor UK summer and the following winter had significantly higher saturated fat content and far less beneficial fatty acids than in a more 'normal' year. But they also discovered that switching to organic milk could help overcome these problems. Organic supermarket milk showed higher levels of nutritionally beneficial fatty acids compared with 'ordinary' milk regardless of the time of year or weather conditions. The study, which is published in this month's Journal of Dairy Science (January 2011), leads on from previous research undertaken nearly three years ago which looked at the difference between organic and conventional milk at its source – on the farms. "We wanted to check if what we found on farms also applies to milk available in the shops," said Gillian Butler, who led the study. "Surprisingly, the differences between organic and conventional milk were even more marked. Whereas on the farms the benefits of organic milk were proven in the summer but not the winter, in the supermarkets it is significantly better quality year round." There was also greater consistency between organic suppliers, where the conventional milk brands were of variable quality. "We were surprised to see obvious differences between the conventional brands, with the more expensive ones not necessarily better," said Mrs Butler. "Some brands - which promote their suppliers as wholesome and grazing on fresh pastures - actually sold milk that appeared to be from very intensive farms." Low levels of omega-3 and polyunsaturated fatty acids were discovered in some of these brands, which are indicative of a diet low in fresh grass. These samples also showed evidence of the cows being supplemented with a saturated fat product derived from palm oil. Mrs Butler puts the differences down to a lower reliance on grazing and fertiliser suppressing clover on conventional farms. "The results suggest greater uniformity of feeding practice on farms supplying organic milk since there were no brands which differed consistently in fat composition," she said. "This implies a fairly uniform approach to feeding practised across these suppliers." Organic dairying standards prescribe a reliance on forage, especially grazing, and, in the absence of nitrogen fertiliser, tend to encourage swards of red and white clover, which have been shown to alter the fatty acid intake and composition of milk. While protein, antioxidants, vitamins, minerals and some mono and polyunsaturated fatty acids in milk are considered beneficial, saturated fatty acids are believed to have a negative effect on human health. "We're always being told to cut down on the saturated fat we consume and switching to organic milk and dairy products provides a natural way to increase our intake of nutritionally desirable fatty acids, vitamins and antioxidants without increasing our intake of less desirable fatty acids," said Mrs Butler. "By choosing organic milk you can cut saturated fats by 30-50 percent and still get the same intake of beneficial fatty acids, as the omega-3 levels are higher but omega-6 is not, which helps to improve the crucial ratio between the two." While undertaking their research into the differences between organic and conventional milk, the researchers discovered the surprising link between milk quality and our changing climate. Their results suggest that if we continue to have wetter, cooler summers then farmers may have to rethink their current dairy practices. There was a considerable difference between the milk bought in the first sampling period (July 2006 and January 2007) and corresponding times a year later. The second set of samples, following a particularly wet summer in 2007, was higher in saturated fat and lower in beneficial fatty acids. "We didn't expect to find differences between the sampling periods," said Mrs Butler. "But this is likely to be down to the impact of the weather on availability and quality of forage." In North East England, for example, the summer of 2007 was particularly wet, with approximately 30 per cent higher recorded rainfall and 12 per cent lower temperatures compared with 2006. "These conditions may affect the cows' behaviour, reducing grazing intake and milk output," said Mrs Butler. "Farmers also often increase supplementation with concentrated feeds or conserved forage to maintain milk yields in these conditions." During the region's main silage making period (late May until the end of July) rainfall in 2007 was three times higher than the previous year, which also made for poorer quality silage and therefore the need for greater supplementation to compensate in winter diets. "If these weather patterns continue, both forage and dairy management will have to adapt to maintain current milk quality," said Mrs Butler. "The higher levels of beneficial fats in organic milk would more than compensate for the depression brought about by relatively poor weather conditions in the wet year." The researchers, who are part of the University's Nafferton Ecological Farming Group and its Human Nutrition Centre, looked at the quality of milk in supermarkets across North East England at varying times of year over a two-year period. They concluded that organic brands of milk available in supermarkets are higher in beneficial fatty acids such as CLA and omega-3 fatty acids in summer (as in their previous research) and winter (where previous research showed that the difference in the winter was not as noticeable). Emma Hockridge, head of policy at the Soil Association, said: "This groundbreaking research proves for the first time that people buying organic milk will be benefitting from the higher levels of beneficial fatty acids in organic milk through the whole year."

GM chickens that don't transmit bird flu developed

Fri, 14 Jan 2011 03:31:32 PDT

Chickens genetically modified to prevent them spreading bird flu have been produced by researchers at the Universities of Cambridge and Edinburgh. The scientists have successfully developed genetically modified (transgenic) chickens that do not transmit avian influenza virus to other chickens with which they are in contact. This genetic modification has the potential to stop bird flu outbreaks spreading within poultry flocks. This would not only protect the health of domestic poultry but could also reduce the risk of bird flu epidemics leading to new flu virus epidemics in the human population. The study, funded by the Biotechnology and Biological Sciences Research Council (BBSRC), is to be published in the Friday, 14 January issue of the journal Science. Dr Laurence Tiley, Senior Lecturer in Molecular Virology from the University of Cambridge, Department of Veterinary Medicine, said: "Chickens are potential bridging hosts that can enable new strains of flu to be transmitted to humans. Preventing virus transmission in chickens should reduce the economic impact of the disease and reduce the risk posed to people exposed to the infected birds. The genetic modification we describe is a significant first step along the path to developing chickens that are completely resistant to avian flu. These particular birds are only intended for research purposes, not for consumption." Professor Helen Sang, from The Roslin Institute at the University of Edinburgh, said, "The results achieved in this study are very encouraging. Using genetic modification to introduce genetic changes that cannot be achieved by animal breeding demonstrates the potential of GM to improve animal welfare in the poultry industry. This work could also form the basis for improving economic and food security in many regions of the world where bird flu is a significant problem." To produce these chickens, the Cambridge and Edinburgh scientists introduced a new gene that manufactures a small "decoy" molecule that mimics an important control element of the bird flu virus. The replication machinery of the virus is tricked into recognising the decoy molecule instead of the viral genome and this interferes with the replication cycle of the virus. When the transgenic chickens were infected with avian flu, they became sick but did not transmit the infection on to other chickens kept in the same pen with them. This was the case even if the other chickens were normal (non-transgenic) birds. Dr Tiley continued, "The decoy mimics an essential part of the flu virus genome that is identical for all strains of influenza A. We expect the decoy to work against all strains of avian influenza and that the virus will find it difficult to evolve to escape the effects of the decoy. This is quite different from conventional flu vaccines, which need to be updated in the face of virus evolution as they tend only to protect against closely matching strains of virus and do not always prevent spread within a flock." Professor Douglas Kell, BBSRC Chief Executive, said: "Infectious diseases of livestock represent a significant threat to global food security and the potential of pathogens, such as bird flu, to jump to humans and become pandemic has been identified by the Government as a top level national security risk. The BBSRC funds world-class research to help to protect the UK from such eventualities and the present approach provides a very exciting example of novel approaches to producing disease-resistant poultry."

Ginger is key ingredient in recipe for conserving stag beetles

Mon, 10 Jan 2011 03:23:38 PDT

The humble ginger root could be the key to conserving the UK's largest and most spectacular terrestrial beetle – the stag beetle. Ecologists from Royal Holloway, University of London and the University of York have developed a series of new methods to monitor stag beetle numbers – including ginger lures to trap adult beetles and tiny microphones to detect sounds made by the larvae in their underground nests. Conservation efforts have been hampered until now because ecologists lacked a reliable way of monitoring stag beetle numbers. The new research, published in the Royal Entomological Society's journal Insect Conservation and Diversity, found that a combination of ginger-baited aerial traps to catch adult stag beetles, plus tiny microphones to record the underground larvae's sounds and samplers to detect the chemicals they emit, give an accurate picture of the species' abundance. According to Dr Deborah Harvey, one of the study's authors: "Our new methods offer genuine promise for monitoring the population of this elusive and rare insect, one that we think is declining across much of its European range. We need to know where the stag beetle lives – and in what numbers – to be able to conserve it effectively." Harvey and her colleagues discovered ginger was irresistible to adult stag beetles only after testing the attractiveness of many other fruit and vegetables – including banana, strawberry, tomato and cherry – as well as wine and beer. Ginger works because it contains large amounts of alpha copaene, a chemical known to attract other insects that live in dead and decaying wood. By using ginger, and designing the trap using heavy duty plastic, Harvey was able to produce a very cost-effective trap, which is vital because most insect monitoring in the UK is done by a small army of dedicated but unfunded amateur recorders. Using other methods of trapping insects, such as light traps or traps baited with food, do not work with adult stag beetles because they are not reliably attracted to light and the species does not eat during the adult phase of its life cycle. As well as finding a method of monitoring adult numbers, Harvey also needed a way to detect larvae, which live underground. Hand searching is likely to destroy their habitats, so instead the team used tiny microphones to pick up the sounds – known as stridulation – the larvae make, together with so-called diffusive samplers to detect a chemical (longifolene) they emit. Harvey says: "Sampling subterranean insects without destroying the larval habitat is notoriously difficult. These diffusive samplers are widely used to monitor environmental pollution, but this is the first time they have been used for insect detection. Because longifolene can be produced by plants, we used it together with sound recording to come up with a more accurate method of finding stag beetle larvae." The team found that stridulation patterns produced by stag beetle larvae are very different from other species likely to live nearby, such as the rose chafer (Cetonia aurata) and the lesser stag beetle (Dorcus parallelipipedus). "Stridulation is likely to be a form of communication between larvae; it increases if larvae are handled or placed in solitary confinement," Harvey says. These are the first ever sound recordings of lesser stag beetle and rose chafer larvae. The latter sound like squeaky shoes. The new methods could help conserve other rare species. According to Harvey: "Acoustic detection of insects as a sampling method is very underused, but we believe it could have great potential in detecting larvae in the field."

Wildflower colors tell butterflies how to do their jobs

Mon, 10 Jan 2011 03:20:23 PDT

The recipe for making one species into two requires time and some kind of separation, like being on different islands or something else that discourages gene flow between the two budding species. In the case of common Texas wildflowers that share meadows and roadside ditches, color-coding apparently does the trick. Duke University graduate student Robin Hopkins has found the first evidence of a specific genetic change that helps two closely related wildflowers avoid creating costly hybrids. It results in one of the normally light blue flowers being tagged with a reddish color to appear less appetizing to the pollinating butterflies which prefer blue. "There are big questions about evolution that are addressed by flower color," said Hopkins, who successfully defended her doctoral dissertation just weeks before seeing the same work appear in the prestigious journal Nature. What Hopkins found, with her thesis adviser, Duke biology professor Mark Rausher, is the first clear genetic evidence for something called reinforcement in plants. Reinforcement keeps two similar proto-species moving apart by discouraging hybrid matings. Flower color had been expected to aid reinforcement, but the genes had not been found. In animals or insects, reinforcement might be accomplished by a small difference in scent, plumage or mating rituals. But plants don't dance or choose their mates. So they apparently exert some choice by using color to discourage the butterflies from mingling their pollen, Hopkins said. Where Phlox drummondii lives by itself, it has a periwinkle blue blossom. But where its range overlaps with Phlox cuspidata, which is also light blue, drummondii flowers appear darker and more red. Some individual butterflies prefer light blue blossoms and will go from blue to blue, avoiding the dark reds. Other individual butterflies prefer the reds and will stick with those. This "constancy" prevents hybrid crosses. Hybrid offspring between drummondii and cuspidata turn out to be nearly sterile, making the next generation a genetic dead-end. The persistent force of natural selection tends to push the plants toward avoiding those less fruitful crosses, and encourages breeding true to type. In this case, selection apparently worked upon floral color. Hopkins was able to find the genes involved in the color change by crossing a light blue drummondii with the red in greenhouse experiments. She found the offspring occurred in four different colors in the exact 9-to-3-to-3-to-1 ratios of classical Mendelian inheritance. "It was 2 in the morning when I figured this out," she said. "I almost woke up my adviser." From there, she did standard genetics to find the exact genes. The change to red is caused by a recessive gene that knocks out the production of the plant's one blue pigment while allowing for the continued production of two red pigments. Even where the red flowers are present, about 11 percent of each generation will be the nearly-sterile hybrids. But without color-coding, that figure would be more like 28 percent, Hopkins said. Why and how the butterflies make the distinction has yet to be discovered. Hopkins will be continuing her research as a visiting scientist at the University of Texas, and the clear message from all of her advisers is "follow the butterflies. Everyone wants to know more about the butterflies!"

Catfish study reveals multiplicity of species

Thu, 06 Jan 2011 03:25:31 PDT

Peer into any stream in a South American rainforest and you may well see a small shoal of similar-looking miniature catfish. But don't be fooled into thinking that they are all the same species. An extensive investigation of South American Corydoras catfish, (reported in Nature 6.1.11), reveals that catfish communities- although containing almost identically coloured and patterned fish, could actually contain three or more different species. Establishing for the first time that many species are mimetic; that is, they evolve to share the same colour patterns for mutual benefit- the research also established that each individual community of similar looking fish comprised species belonging to different genetic lineages, but still adopting similar colour patterns. This discovery suggests that in many cases the number of Corydoras catfish species may be higher than previously recognised. This has consequent implications for environmentalists charged with protecting environmental diversity and safeguarding the species. This increases the challenge of conserving these species at a time when many South American rivers are experiencing large scale development involving damn building, and destruction or contamination of habitats. Markos Alexandrou, PhD student at Bangor University and one of the paper's authors said: "Although appearing identical in terms of colour pattern, our in-depth assessments of genetic relationships, diet, body shape and colour patterns of the fish revealed that 92% of the communities we sampled comprised species that do not compete for resources. Dr Martin Taylor, project leader at the University's School of Biological Sciences said: "This research highlights the hidden diversity and complexity found within neotropical freshwater ecosystems. Unfortunately, these habitats are also under extreme pressure from human activities." Claudio Oliveira of project partners, (UNESP, Botucatu, Brazil) said: "Besides the unknown biodiversity and interesting evolutionary system revealed by this study, it reinforces the urgent need to preserve and manage South American environments to avoid the loss of many species yet to be discovered and described."

Even healthy cats act sick when their routine is disrupted

Tue, 04 Jan 2011 03:22:49 PDT

A cat regularly vomiting hairballs or refusing to eat probably isn’t being finicky or otherwise “cat-like,” despite what conventional wisdom might say. There is a good chance that the cat is acting sick because of the stress caused by changes in its environment, new research suggests. Healthy cats were just as likely as chronically ill cats to refuse food, vomit frequently and leave waste outside their litter box in response to changes in their routine, according to the Ohio State University study. Veterinary clinicians refer to these acts as sickness behaviors. The researchers documented sickness behaviors in healthy cats and in cats with feline interstitial cystitis, a chronic illness characterized by recurring discomfort or pain in the bladder and often both an urgent and frequent need to urinate.......> Full story

Without intervention, Mariana crow to become extinct in 75 years

Tue, 21 Dec 2010 03:32:07 PDT

Researchers from the University of Washington say the Mariana crow, a forest crow living on Rota Island in the western Pacific Ocean, will go extinct in 75 years. The extinction could happen almost twice as soon as previously believed. The crow's extinction can be prevented with a bird management program that focuses on helping fledgling birds reach their first birthday, said James Ha, UW research associate professor in psychology. Ha examined survival rates in 97 Mariana crows – Corvus kubaryi – that had been tracked between 1990 and 2010 by researchers. He found that 40 percent of fledgling crows made it to their first birthday. The rapid decline of young birds is twice what researchers previously estimated. "It's the first year of survival that's the most crucial," said Ha, lead author of a report on the research. "If only 40 percent of fledglings survive their first year, then we predict the species will go extinct in 75 years." Ha and his co-authors published the report in the current issue of Bird Conservation International. The 75-year extinction estimate is according to a population model that factors in the estimated number of existing Mariana crows – 330 – with the 40 percent first-year survival rate, average number of fledglings per nest and fertility of female birds. Using this model, Ha found that 91 birds would exist in 20 years and that in 75 years the species would be extinct. Previously, biologists believed that the first-year survival rate of Mariana crows was higher, around 60 to 80 percent. When Ha used those estimates in his population model, the outlook was not as grim for the birds. At 60 percent first-year survival rate, Mariana crows would dwindle to 218 birds in 20 years and become extinct in 133 years. And an 80 percent first-year survival rate projects that in 20 years there would be 453 birds, a growing population that would avoid extinction. "According to the population model, if we can boost fledgling survival from 40 percent to 70 percent, the Mariana crows will be fine," Ha said. Of the about 35 crow species, Mariana crows are considered rare and classified as critically endangered. Weighing about a half of a pound, Mariana crows are 40 percent smaller than other crows, such as the Northwest crow. Monogamously-mating, Mariana crows live exclusively on Rota Island, populated by about 1,200 people and located 56 miles northeast of Guam. Rota is a U.S. territory and is up for consideration as a U.S. national park. Ha and Renee Ha, co-author of the report and UW research scientist in psychology, fear that Rota faces the same avian demise as Guam, which has no forest birds. Brown tree snakes introduced to the island after World War II wiped out native birds, such as the Guam flycatcher and the Rufous fantail. The Has suspect that the uncontrolled increase of feral cats on Rota is leading to the decrease of Mariana crows, much like brown tree snakes led to the disappearance of forest birds on Guam. The researchers say that a captive rearing program could save the Mariana crows. They hope to set up a rearing facility where they could incubate eggs from the wild, raise the fledglings until their first birthday and then release the grown birds into nesting sites on the island.

Marsupial embryo jumps ahead in development

Tue, 30 Nov 2010 03:17:51 PDT

Long a staple of nature documentaries, the somewhat bizarre development of a grub-like pink marsupial embryo outside the mother's womb is curious in another way. Duke University researchers have found that the developmental program executed by the marsupial embryo runs in a different order than the program executed by virtually every other vertebrate animal. "The limbs are at a different place in the entire timeline," said Anna Keyte, a postdoctoral biology researcher at Duke who did this work as part of her doctoral dissertation. "They begin development before almost any other structure in the body." Biologists have been pursuing the notion that limb development is triggered by other organ systems coming on line first, but this study shows the marsupial's limbs begin development without such triggers. "Development is probably more flexible than we might have known otherwise," said biology professor Kathleen Smith. Their study animals were gray short-tailed opossums (Monodelphis domestica) native to Brazil and Bolivia, but the same should hold true for any marsupial, Smith said. For the undeveloped embryo to be able to drag itself across the mother's belly from the birth canal to the teat, it needs a formidable pair of forelimbs. To get them, its developmental program has been rearranged to start building the forelimbs much sooner. "A lot of these genes were turned on earlier than you'd see in a mouse or a chick," Keyte said. The researchers were also able to show that the forelimbs received cells from a much larger part of the developing embryo than is normally seen in other vertebrates. What surprised the researchers was that the genetic program to establish the hind limbs also appeared to be turned on early. Gene expression sets up the pattern of where each of the four limbs will be, but the marsupial's forelimbs grow much faster than the hind limbs because the embryo devotes more of its scarce number of early cells to building those structures, Smith said. The plans are in place for the hind limbs, but not the bricks to build them. The embryo emerges from the mother with burly forearms that include bones and well developed muscles, while the hind limbs are small and rubbery. Blind, hairless and with an incomplete brain, a marsupial embryo is shockingly underdeveloped to be living outside the womb. But the system obviously works for marsupials. "There are probably 50 explanations for why marsupials develop outside the womb, and none of them are very good," Smith said. It's pretty clear however that the external development gives the female a lot more control over her reproduction. If conditions change or she runs out of food, the marsupial mother can easily terminate an external pregnancy.

Battle of the sexes, fruit-fly style

Wed, 24 Nov 2010 03:31:02 PDT

Pity the female fruit fly. Being a looker is simply not enough. To get a date, much less a proposal, you have to act like a girl, even smell like one. Otherwise, you might just have a fight on your hands. Like most animals, fruit flies must distinguish between a potential mate and a potential competitor. When a male fruit fly suspects he's encountered a female, he'll court; when he senses the other is a male, he'll fight. What triggers these sex-specific responses? According to new research by scientists at Harvard Medical School, the answer lies with both pheromonal profiles and behavioral patterns. The researchers investigated the effects of taste and action by manipulating a gene that governs both the sex specificity of a fruit fly's body-surface hydrocarbons, or pheromones, and the sex-linked behavioral cues that issue through the dense nerve-cell network that constitutes the fly's brain. "These findings underscore the importance of behavioral feedback in the manifestation of aggression," says Edward Kravitz, the George Packer Berry Professor of Neurobiology at Harvard Medical School. The research is published in the November 23 issue of PLoS Biology. María de la Paz Fernández and Yick-Bun Chan, post-doctoral researchers in the Kravitz lab, discovered these links to aggression when investigating whether a male fruit fly would ever attack a female. They focused on a particular gene called transformer, which is active in females but not in males. Through blocking transformer expression in a variety of different tissues in females, the researchers could specifically alter the "femaleness" or "maleness" of the pheromones, which in turn altered the patterns of aggressive behavior encoded in the fly's brain. When they changed pheromone profiles so that females "tasted" like males, the researchers found that males would attack them. This indicated that pheromonal cues alone could label another fly as a competitor. But the researchers were surprised to discover that males also attacked "aggressive females"—flies that still looked, smelled and tasted female but had been genetically altered to display male-like patterns of behavior. When the researchers turned the tables by triggering the expression of transformer in males so as to feminize both the pheromonal and behavioral profiles, control males showed no aggression toward the transformed males. Instead, they began to court them. These results show that it is possible to completely reverse normal behavioral responses by presenting males with unanticipated and conflicting sensory cues. "Future studies will aim at unraveling the neuronal circuitry that governs this type of decision-making behavior, as such decisions are essential for survival," says Kravitz. "With the powerful genetic methods available in fly neurobiology, it should be possible to dissect the decision-making circuitry at far greater levels of detail than have heretofore been possible in other species." "This study addresses a classic question in animal behavior: What motivates an individual to do X rather than Y, or vice versa," said Laurie Tompkins, Ph.D., who manages Kravitz's and other behavioral genetics grants at the National Institutes of Health. "Because the general principles of how behaviors are controlled are conserved among species, Kravitz's conclusions about how flies make simple choices may illuminate how humans and other animals make more complex decisions."

DNA uncovers 1 of the world's rarest birds

Wed, 24 Nov 2010 03:26:43 PDT

A team of Australian researchers involving DNA experts from the University of Adelaide has identified a new, critically endangered species of ground parrot in Western Australia. The team, led by Australian Wildlife Conservancy's Dr Stephen Murphy, used DNA from museum specimens up to 160 years old to reveal that populations of ground parrots in eastern and western Australia are highly distinct from each other and that the western populations should be recognized as a new species, Pezoporus flaviventris. "The discovery has major conservation implications," said Dr Murphy. "The Western Ground parrot has declined rapidly in the last 20 years, there are now only about 110 birds surviving in the wild and most of these are confined to a single national park. It is now one of the world's rarest birds." WA Department of Environment and Conservation's Dr Allan Burbidge said: "A single wildfire through the national park or an influx of introduced predators, such as cats, could rapidly push the species to extinction. There is now an urgent need to prevent further population declines and to establish insurance populations into parts of the former range." "Our findings demonstrate that museum collections, some going back more than 150 years, continue to be relevant and can provide critical information for understanding and conserving the world's biodiversity into the future," said team member Dr Jeremy Austin, Deputy Director of the Australian Centre for Ancient DNA at the University of Adelaide. Director of CSIRO's Australian National Wildlife Collection, Dr Leo Joseph, said: "Even after 200 years of study, we are still recognizing new species of birds in Australia. This finding highlights the need for further research on Australia's unique, and sometimes cryptic, biodiversity."

Bat brains offer clues as to how we focus on some sounds and not others

Mon, 15 Nov 2010 03:21:03 PDT

How do you know what to listen to? In the middle of a noisy party, how does a mother suddenly focus on a child's cry, even if it isn't her own? Bridget Queenan, a doctoral candidate in neuroscience at Georgetown University Medical Center is turning to mustached bats to help her solve this puzzle. At the annual meeting of the Society for Neuroscience in San Diego, Queenan will report that she has found neurons in the brains of bats that seem to "shush" other neurons when relevant communications sounds come in – a process she suggests may be working in humans as well. In her investigations, she has also found that "some neurons seemed to know to yell louder to report communication sounds over the presence of background noise." "So we can now start to piece together how the cells in your brain are able to deal with the complex sensory environment we live in," Queenan added. To understand auditory brain function, bats are especially interesting animals to study because they process sound through echolocation, which is a kind of biological sonar. Bats call out and then listen to their own echoes produced when those calls bounce off nearby objects. Bats use these echoes to navigate and to hunt. Not only do the brains of bats have to process a constant stream of pulses and echoes, they have to simultaneously process the bats' social communication, Queenan says. "What we are trying to figure out is how a bat can fly around echolocating - screeching and listening to its own individual sounds bouncing back - amidst a whole colony of hundreds of other echolocating bats – and possibly hear another bat saying 'watch out! Bats actually do make these cautious calls quite a bit," she says. "In fact, bats have a whole host of communication sounds: angry sounds, warning sounds, and sounds that says 'please don't hurt me." The auditory processing area in bats' brains is larger than other centers, just like the visual processing center in humans is large. "Humans operate predominantly by sight so a huge portion of our brain is devoted to vision processing. Bats, however, operate by sound," Queenan says. In this study, Queenan and her colleagues presented different combinations of echolocation sounds with various communication sounds to awake bats to see how neurons in the bat brains were dealing with this incredible cacophony. The researchers found that some bats' neurons control the activity of other neurons when important sounds are perceived. These GUMC scientists also found other neurons that amp up perception of bat communication in the face of background noise. Working together, these clumps of neurons allow the bats to hear what is needed. "All organisms are constantly assaulted by incoming stimuli such as sounds, light, vibrations, and so on, and our sensory systems have to triage the most relevant stimuli to help us survive," Queenan says. "As humans we are not only sensitive to a child's cry, but we notice flashing ambulance lights even though we are engrossed in something else. We want to know how that happens." Queenan says her next task is to record brain neurons in bats that are not only awake, but flying.

New strain of 'high-runner' rats uniquely resistant to disease -- all disease!

Tue, 02 Nov 2010 03:20:06 PDT

Everybody knows that if you're physically fit, you're less likely to get a wide range of diseases. What most people don't know is that some people are "naturally" in better shape than others, and this variation in conditioning makes it difficult to test for disease risk and drug effectiveness in animal models. A new research paper published in the November 2010 print issue of The FASEB Journal (http://www.faseb.org) started out as a study to explain the strong statistical link between low aerobic exercise capacity and common diseases, but ultimately led to an animal model that breaks through the limitations of current systems that target single disease pathways. Because common disease risks arise from complex interactions of many genetic pathways, future animal model systems, like this one, must account for multiple pathways. The animal model developed in this study can be used to evaluate mechanisms by which positive and negative environmental effects influence disease risks and explore a wide variety of pathways, rather than focusing on a single target. "We hope that our approach of using a more realistic animal model system of disease risks will lead to information that is explanatory and ultimately predictive of mechanisms underlying disease," said Heikki Kainulainen, Ph.D., co-author of the study from the Neuromuscular Research Center at the University of Jyväskylä in Finland. "This seems to be the only path for developing diagnostics and therapeutics that have high efficacy." To create this animal model, researchers bred high-runners with high-runners and low¬-runners with low-runners to divide and concentrate the genes for these traits in two groups of rats. After 11 generations of selection, "high-runner" rats could run three times as far as the "low-runner" rats. The low-runner rats appeared to be at a higher risk for disease than the high-runner rats. Genetic analysis of the two groups of rats revealed that the expression levels of seven functionally related groups of genes correlated with differences in aerobic running traits and disease risks between the low- and high- runner rats. This makes the low-runner and high-runner rat model system a valuable tool to explore mechanisms underlying disease risks at all levels of biological organization. "Genes that increase resistance to common diseases in high-runner rats are also present across species," said Gerald Weissmann, M.D., Editor-in-Chief of The FASEB Journal. "As our understanding of disease grows in complexity, so does our need for animal models that can mimic disease susceptibility in humans."

Mosquito monitoring saves lives and money, analysis finds

Wed, 27 Oct 2010 03:24:44 PDT

Cutting surveillance for mosquito-borne diseases would likely translate into an exponential increase in both the number of human cases and the health costs when a disease outbreak occurs, according to an analysis by Emory University. The Public Library of Science (PLoS) publishes the research, led by Emory disease ecologist Gonzalo Vazquez-Prokopec, Oct. 26. "Our analysis shows that halting mosquito surveillance can increase the management costs of epidemics by more than 300 times, in comparison with sustained surveillance and early case detection," Vazquez-Prokopec says. The research was prompted by a U.S. government proposal last spring to slash funding for the vector-borne disease program of the Centers for Disease Control and Prevention. Congress ultimately voted to retain the program's budget at the same levels for 2011. "This analysis provides scientific-based evidence of the need for more funding of mosquito surveillance, not less," says Uriel Kitron, a co-author of the study and the chair of Emory's Department of Environmental Studies. Diseases spread by mosquitoes and other blood-sucking vectors are a major public health risk worldwide. They include a wide variety of bacterial, parasitic and viral infections, such as malaria, West Nile Virus, dengue fever and Lyme disease. The Emory analysis used data from two outbreaks of dengue fever in Cairns, Australia, that occurred in 2003 and 2009. (Dengue fever, an extremely debilitating viral disease spread by mosquitoes, can be fatal.) A mathematical model was applied to the Cairns data to evaluate the economic impact of hypothetical epidemic curves, plotted against different response times. A response within two weeks of the introduction of the pathogen was assumed to occur with active disease surveillance in place, and delays of six-to-eight weeks were assumed when active disease and vector surveillance were eliminated. In Cairns, where mosquito surveillance is active, the reactions to the dengue fever outbreaks were rapid. The costs of the epidemics – including vector control, case diagnosis, blood screening and work days lost to disease – totaled U.S.$150,000 for the 2003 outbreak and $1.1 million for the 2009 outbreak. The analysis showed that a delayed response of four-to-six weeks to both Cairns dengue outbreaks would have resulted in drastically escalated costs of up to U.S.$382 million. A slight increase in the virulence of the strain could have multiplied the cost by another 10 times. Cairns has a tropical climate similar to South Florida, where a dengue fever outbreak occurred in 2009, Vazquez-Prokopec notes. "Predictions based on our analysis show that, if the Miami area had not had a surveillance system in place, the costs to control the Florida outbreak could have been higher than the entire U.S. budget for mosquito surveillance," he says. While the modern-day United States has been relatively unscathed by vector-borne disease, it is not immune to a host of new and emerging pathogens, the researchers warn. The emergence of West Nile Virus (WNV) in New York City in 1999 spurred better mosquito surveillance, and serves as an example of the consequences of a delayed response. By the time a correct diagnosis was made and proper controls were initiated, the pathogen had spread throughout the country. By the end of 2008, WNV had generated 28,961 known cases and 1,130 fatalities.