A Blog Around The Clock

Birds Can Detect Predators Using Smell:

Many animal species detect and avoid predators by smell, but this ability has largely been ignored in the study of birds, since it was traditionally thought that they did not make use of this sense. However, it has now been discovered that birds are not only capable of discerning their enemies through chemical signals, but that they also alter their behaviour depending on the perceived level of risk of predation.

Help For Insomnia Patients? Different Processes Govern Sight, Light Detection:

A Johns Hopkins University biologist, in research with implications for people suffering from seasonal affective disorder and insomnia, has determined that the eye uses light to reset the biological clock through a mechanism separate from the ability to see.

When Did Dinosaurs Go Extinct? Cretaceous-Tertiary Boundary Dating Refined:

Scientists at the University of California, Berkeley, and the Berkeley Geochronology Center have pinpointed the date of the dinosaurs’ extinction more precisely than ever thanks to refinements to a common technique for dating rocks and fossils.

Tropical Reforestation Aided By Bats:

German scientists are engaging bats to kick-start natural reforestation in the tropics by installing artificial bat roosts in deforested areas. This novel method for tropical restoration is presented in a new study published online in the science journal Conservation Biology this week. Detlev Kelm from the Leibniz Institute for Zoo and Wildlife Research in Berlin (IZW) and Kerstin Wiesner and Otto von Helversen from the University of Erlangen-Nuremberg report that the deployment of artificial bat roosts significantly increases seed dispersal of a wide range of tropical forest plants into their surroundings, providing a simple and cheap method to speed up natural forest regeneration.

Why We Sleep: The Temporal Organization of Recovery:

“If sleep does not serve an absolutely vital function, then it is the biggest mistake the evolutionary process has ever made,” Allan Rechtschaffen said. Studies of sleep and sleep deprivation suggest that the functions of sleep include recovery at the cellular, network, and endocrine system levels, energy conservation and ecological adaptations, and a role in learning and synaptic plasticity.

One Rhodopsin per Photoreceptor: Iro-C Genes Break the Rule:

A long-standing general principle in vision research holds that single photoreceptors always contain a single type of rhodopsin, although occasional examples of co-expressed rhodopsins, as the authors have now demonstrated for Drosophila, have cropped up in both vertebrates and invertebrates.

Compilation and Network Analyses of Cambrian Food Webs:

Food webs, which depict the networks of feeding interactions among co-occurring species, display many regularities in their structure. For example, the distributions of links to prey and links from predators, the percentages of omnivores and herbivores, and the mean trophic level of species change systematically with the number of taxa and feeding links in a web. Such “scale-dependent” regularities are formalized by network models based on a few simple link distribution rules that successfully predict the network structure of complex food webs from a variety of habitats. To explore how long such regularities may have persisted, we compiled and analyzed detailed food-web data for two ancient fossil assemblages from the early Paleozoic, when rapid diversification of multicellular species, body plans, and trophic roles occurred. Our analyses show that for most aspects of network structure, the Early Cambrian Chengjiang Shale and Middle Cambrian Burgess Shale food webs are very similar to modern webs. This suggests that there are strong and enduring constraints on the organization of feeding interactions in ecosystems. However, a few differences, particularly in the Chengjiang Shale web, suggest that some aspects of network structure were still in flux during early phases of de novo ecosystem construction.

Better Reporting, Better Research: Guidelines and Guidance in PLoS Medicine:

PLoS Medicine aims to publish important studies from all medical disciplines that provide a substantial advance either in clinical practice, public heath policy, or basic pathophysiology. Though this is a lofty aim it is possible to see the journal’s role as primarily a passive one; presubmission inquiries and research articles arrive unsolicited, by which time evaluation by editors and reviewers for rigor, originality, and importance can do little to improve deficiencies in study methodology (largely a fait accompli by that point). However, we would argue that medical journals such as PLoS Medicine should seek to go beyond merely reflecting current trends in medical practice and research, by actively working to establish and promote standards that aim to improve the quality of research that is done.

Standardising Outcomes in Paediatric Clinical Trials:

In a new systematic review published in this issue of PLoS Medicine, Ian Sinha and colleagues examined studies that involved the selection of outcomes for use in paediatric clinical trials [2]. As they say in their report, the choice of outcome is important because choosing inappropriate outcomes may lead to “wasted resources or misleading information which either overestimates, underestimates or completely misses the potential benefits of an intervention.”

Early Human Populations Evolved Separately For 100,000 Years:

A team of Genographic researchers and their collaborators have published the most extensive survey to date of African mitochondrial DNA (mtDNA). Over 600 complete mtDNA genomes from indigenous populations across the continent were analyzed by the scientists, led by Doron Behar, Genographic Associate Researcher, based at Rambam Medical Center, Haifa, and Saharon Rosset of IBM T.J. Watson Research Center, NY and Tel Aviv University. Analyses of the extensive data presented in this study provide surprising insights into the early demographic history of human populations before they moved out of Africa, illustrating that these early human populations were small and isolated from each other for many tens of thousands of years.

Insects Use Plants Like A Telephone:

Dutch ecologist Roxina Soler and her colleagues have discovered that subterranean and aboveground herbivorous insects can communicate with each other by using plants as telephones. Subterranean insects issue chemical warning signals via the leaves of the plant. This way, aboveground insects are alerted that the plant is already ‘occupied’.

Rare Musk Ox May Be Threatened By Climate Change:

The Wildlife Conservation Society (WCS) recently launched a four-year study to determine if climate change is affecting populations of a quintessential Arctic denizen: the rare musk ox. Along with collaborators from the National Park Service, U. S. Geological Survey, and Alaska Fish and Game, Wildlife Conservation Society researchers have already equipped six musk ox with GPS collars to better understand how climate change may affect these relics of the Pleistocene.

Biodiversity Is Crucial To Ecosystem Productivity:

In the first experiment involving a natural environment, scientists at Brown University have shown that richer plant diversity significantly enhances an ecosystem’s productivity. The finding underscores the benefits of biodiversity, such as capturing carbon dioxide, a main contributor to global warming.

Dinosaurs Probably Lacked Tissue To Generate Heat:

A team of researchers at New York Medical College has discovered why birds, unlike mammals, lack a tissue that is specialized to generate heat. A new paper contains the surprising implication that the same lack of heat-generating tissue may have contributed to the extinction of dinosaurs.

Lizard Hunting Styles Impact Ability To Walk, Run:

The technique lizards use to grab their grub influences how they move, according to researchers at Ohio University. A research team led by doctoral student Eric McElroy tracked 18 different species of lizards as they walked or ran in order to understand how their foraging styles impact their biomechanics.

Arctic Marine Mammals On Thin Ice:

The loss of sea ice due to climate change could spell disaster for polar bears and other Arctic marine mammals. Sea ice is the common habitat feature uniting these unique and diverse Arctic inhabitants. Sea ice serves as a platform for resting and reproduction, influences the distribution of food sources, and provides a refuge from predators. The loss of sea ice poses a particularly severe threat to Arctic species, such as the hooded seal, whose natural history is closely tied to, and depends on, sea ice.

Nurture Over Nature: Certain Genes Are Turned On Or Off By Geography And Lifestyle, Study Suggests:

Score one for the nurture side of the nature vs. nurture debate, as North Carolina State University geneticists have shown that environmental factors such as lifestyle and geography play a large role in whether certain genes are turned on or off. By studying gene expression of white blood cells in 46 Moroccan Amazighs, or Berbers – including desert nomads, mountain agrarians and coastal urban dwellers – the NC State researchers and collaborators in Morocco and the United States showed that up to one-third of genes are differentially expressed due to where and how the Moroccan Amazighs live.

Human Brain Appears ‘Hard-wired’ For Hierarchy:

Human imaging studies have for the first time identified brain circuitry associated with social status, according to researchers at the National Institute of Mental Health (NIMH) of the National Institutes of Health. They found that different brain areas are activated when a person moves up or down in a pecking order — or simply views perceived social superiors or inferiors. Circuitry activated by important events responded to a potential change in hierarchical status as much as it did to winning money.

Infant Carrying Ruled Out As Reason Why Early Humans Walked Upright, According To New Research:

Scientists investigating the reasons why early humans — the so-called hominins — began walking upright say it’s unlikely that the need to carry children was a factor, as has previously been suggested.

Shell-breaking Crabs Lived 20 Million Years Earlier Than Thought:

While waiting for colleagues at a small natural history museum in the state of Chiapas, Mexico last year, Cornell paleontologist Greg Dietl chanced upon a discovery that has helped rewrite the evolutionary history of crabs and the shelled mollusks upon which they preyed.

Reputation And Money: New Insights Into How The Brain Processes Social, Economic Reward:

Researchers have mapped the brain regions that process social standing and money rewards, yielding new insights that they said will aid understanding of the basis of social behaviors.

On The High Horse: Why Dominant Individuals Climb The Proverbial Ladder:

Psychological findings imply that a person’s level of dominance could be measured based on their biases favoring vertical representations of power, as is the case in a hierarchy. In an attempt to grasp complex concepts, humans have tried to represent abstractions like power and dominance through visually-stimulated metaphors such as pyramids and steeples. And dominance especially has been measured socially, linguistically and artistically on a vertical dimension, as with upper and lower class divisions in hierarchical structures.

What’s Not To Like? Why Fondness Makes Us Poor Judges, But Dislike Is Spot-on:

How good are we at guessing other people’s likes and dislikes? Ever bring a favorite dish to a potluck — only to watch it go uneaten? Or receive an unwelcome shock when a cherished product is discontinued for lack of sales? People have the tendency to assume the whole world likes what we like, reveals new research from the June 2008 issue of the Journal of Consumer Research. However, we don’t generalize the same way when it comes to things we hate.

Coke Or Pepsi? Being Distracted Can Make You More Susceptible To Ads:

A can of Coke next to the word “awesome”; a can of Pepsi next to a picture of a happy couple. Seem too basic to be effective advertising? Prior research has shown that reported attitudes towards brands are not affected by such simple juxtapositions. However, a new paper in the June 2008 issue of the Journal of Consumer Research examines our implicit opinions — and finds that we may actually be more susceptible than we think.

Molecular Analysis Confirms Tyrannosaurus Rex’s Evolutionary Link To Birds:

Putting more meat on the theory that dinosaurs’ closest living relatives are modern-day birds, molecular analysis of a shred of 68-million-year-old Tyrannosaurus rex protein — along with that of 21 modern species — confirms that dinosaurs share common ancestry with chickens, ostriches, and to a lesser extent, alligators.

There are 41 new articles published this week in PLoS ONE. A always, make comments and ratings while browsing and reading the articles. Here are just a few picks – titles I found interesting – but you should go and check all the others as well:
Nutrition or Detoxification: Why Bats Visit Mineral Licks of the Amazonian Rainforest:

Many animals in the tropics of Africa, Asia and South America regularly visit so-called salt or mineral licks to consume clay or drink clay-saturated water. Whether this behavior is used to supplement diets with locally limited nutrients or to buffer the effects of toxic secondary plant compounds remains unclear. In the Amazonian rainforest, pregnant and lactating bats are frequently observed and captured at mineral licks. We measured the nitrogen isotope ratio in wing tissue of omnivorous short-tailed fruit bats, Carollia perspicillata, and in an obligate fruit-eating bat, Artibeus obscurus, captured at mineral licks and at control sites in the rainforest. Carollia perspicillata with a plant-dominated diet were more often captured at mineral licks than individuals with an insect-dominated diet, although insects were more mineral depleted than fruits. In contrast, nitrogen isotope ratios of A. obscurus did not differ between individuals captured at mineral lick versus control sites. We conclude that pregnant and lactating fruit-eating bats do not visit mineral licks principally for minerals, but instead to buffer the effects of secondary plant compounds that they ingest in large quantities during periods of high energy demand. These findings have potential implications for the role of mineral licks for mammals in general, including humans.

Interactive ‘Video Doctor’ Counseling Reduces Drug and Sexual Risk Behaviors among HIV-Positive Patients in Diverse Outpatient Settings:

Reducing substance use and unprotected sex by HIV-positive persons improves individual health status while decreasing the risk of HIV transmission. Despite recommendations that health care providers screen and counsel their HIV-positive patients for ongoing behavioral risks, it is unknown how to best provide “prevention with positives” in clinical settings. Positive Choice, an interactive, patient-tailored computer program, was developed in the United States to improve clinic-based assessment and counseling for risky behaviors. We conducted a parallel groups randomized controlled trial (December 2003-September 2006) at 5 San Francisco area outpatient HIV clinics. Eligible patients (HIV-positive English-speaking adults) completed an in-depth computerized risk assessment. Participants reporting substance use or sexual risks (n = 476) were randomized in stratified blocks. The intervention group received tailored risk-reduction counseling from a “Video Doctor” via laptop computer and a printed Educational Worksheet; providers received a Cueing Sheet on reported risks. Compared with control, fewer intervention participants reported continuing illicit drug use (RR 0.81, 95% CI: 0.689, 0.957, p = 0.014 at 3 months; and RR 0.65, 95% CI: 0.540, 0.785, p<0.001 at 6 months) and unprotected sex (RR 0.88, 95% CI: 0.773, 0.993, p = 0.039 at 3 months; and RR 0.80, 95% CI: 0.686, 0.941, p = 0.007 at 6 months). Intervention participants reported fewer mean days of ongoing illicit drug use (-4.0 days vs. -1.3 days, p = 0.346, at 3 months; and -4.7 days vs. -0.7 days, p = 0.130, at 6 months) than did controls, and had fewer casual sex partners at (−2.3 vs. −1.4, p = 0.461, at 3 months; and −2.7 vs. −0.6, p = 0.042, at 6 months). The Positive Choice intervention achieved significant cessation of illicit drug use and unprotected sex at the group-level, and modest individual-level reductions in days of ongoing drug use and number of casual sex partners compared with the control group. Positive Choice, including Video Doctor counseling, is an efficacious and appropriate adjunct to risk-reduction efforts in outpatient settings, and holds promise as a public health HIV intervention.

Marine Incursion: The Freshwater Herring of Lake Tanganyika Are the Product of a Marine Invasion into West Africa:

The spectacular marine-like diversity of the endemic fauna of Lake Tanganyika, the oldest of the African Great Lakes, led early researchers to suggest that the lake must have once been connected to the ocean. Recent geophysical reconstructions clearly indicate that Lake Tanganyika formed by rifting in the African subcontinent and was never directly linked to the sea. Although the Lake has a high proportion of specialized endemics, the absence of close relatives outside Tanganyika has complicated phylogeographic reconstructions of the timing of lake colonization and intralacustrine diversification. The freshwater herring of Lake Tanganyika are members of a large group of pellonuline herring found in western and southern Africa, offering one of the best opportunities to trace the evolutionary history of members of Tanganyika’s biota. Molecular phylogenetic reconstructions indicate that herring colonized West Africa 25-50MYA, at the end of a major marine incursion in the region. Pellonuline herring subsequently experienced an evolutionary radiation in West Africa, spreading across the continent and reaching East Africa’s Lake Tanganyika during its early formation. While Lake Tanganyika has never been directly connected with the sea, the endemic freshwater herring of the lake are the descendents of an ancient marine incursion, a scenario which may also explain the origin of other Tanganyikan endemics.

Truncated Power Laws Reveal a Link between Low-Level Behavioral Processes and Grouping Patterns in a Colonial Bird:

Departures from power law group size frequency distributions have been proposed as a useful tool to link individual behavior with population patterns and dynamics, although examples are scarce for wild animal populations. We studied a population of Lesser kestrels (Falco naumanni) breeding in groups (colonies) from one to ca. 40 breeding pairs in 10,000 km2 in NE Spain. A 3.5 fold steady population increase occurred during the eight-year study period, accompanied by a geographical expansion from an initial subpopulation which in turn remained stable in numbers. This population instability was mainly driven by first-breeders, which are less competitive at breeding sites, being relegated to breed solitarily or in small colony sizes, and disperse farther than adults. Colony size frequency distributions shifted from an initial power law to a truncated power law mirroring population increase. Thus, we hypothesized that population instability was behind the truncation of the power law. Accordingly, we found a power law distribution through years in the initial subpopulation, and a match between the power law breakpoint (at ca. ten pairs) and those colony sizes from which the despotic behavior of colony owners started to impair the settlement of newcomers. Moreover, the instability hypothesis was further supported by snapshot data from another population of Lesser kestrels in SW Spain suffering a population decline. Appropriate analysis of the scaling properties of grouping patterns has unraveled the link between local agonistic processes and large-scale (population) grouping patterns in a wild bird population.

Floral Temperature and Optimal Foraging: Is Heat a Feasible Floral Reward for Pollinators?:

As well as nutritional rewards, some plants also reward ectothermic pollinators with warmth. Bumble bees have some control over their temperature, but have been shown to forage at warmer flowers when given a choice, suggesting that there is some advantage to them of foraging at warm flowers (such as reducing the energy required to raise their body to flight temperature before leaving the flower). We describe a model that considers how a heat reward affects the foraging behaviour in a thermogenic central-place forager (such as a bumble bee). We show that although the pollinator should spend a longer time on individual flowers if they are warm, the increase in total visit time is likely to be small. The pollinator’s net rate of energy gain will be increased by landing on warmer flowers. Therefore, if a plant provides a heat reward, it could reduce the amount of nectar it produces, whilst still providing its pollinator with the same net rate of gain. We suggest how heat rewards may link with plant life history strategies.

Cooperation and Deception Recruit Different Subsets of the Theory-of-Mind Network:

The term “theory of mind” (ToM) describes an evolved psychological mechanism that is necessary to represent intentions and expectations in social interaction. It is thus involved in determining the proclivity of others to cooperate or defect. While in cooperative settings between two parties the intentions and expectations of the protagonists match, they diverge in deceptive scenarios, in which one protagonist is intentionally manipulated to hold a false belief about the intention of the other. In a functional magnetic resonance imaging paradigm using cartoons showing social interactions (including the outcome of the interaction) between two or three story characters, respectively, we sought to determine those brain areas of the ToM network involved in reasoning about cooperative versus deceptive interactions. Healthy volunteers were asked to reflect upon the protagonists’ intentions and expectations in cartoons depicting cooperation, deception or a combination of both, where two characters cooperated to deceive a third. Reasoning about the mental states of the story characters yielded substantial differences in activation patterns: both deception and cooperation activated bilateral temporoparietal junction, parietal and cingulate regions, while deception alone additionally recruited orbitofrontal and medial prefrontal regions. These results indicate an important role for prefrontal cortex in processing a mismatch between a character’s intention and another’s expectations as required in complex social interactions.

Orexigenic Hormone Ghrelin Attenuates Local and Remote Organ Injury after Intestinal Ischemia-Reperfusion:

Gut ischemia/reperfusion (I/R) injury is a serious condition in intensive care patients. Activation of immune cells adjacent to the huge endothelial cell surface area of the intestinal microvasculature produces initially local and then systemic inflammatory responses. Stimulation of the vagus nerve can rapidly attenuate systemic inflammatory responses through inhibiting the activation of macrophages and endothelial cells. Ghrelin, a novel orexigenic hormone, is produced predominately in the gastrointestinal system. Ghrelin receptors are expressed at a high density in the dorsal vagal complex of the brain stem. In this study, we investigated the regulation of the cholinergic anti-inflammatory pathway by the novel gastrointestinal hormone, ghrelin, after gut I/R. Gut ischemia was induced by placing a microvascular clip across the superior mesenteric artery for 90 min in male adult rats. Our results showed that ghrelin levels were significantly reduced after gut I/R and that ghrelin administration inhibited pro-inflammatory cytokine release, reduced neutrophil infiltration, ameliorated intestinal barrier dysfunction, attenuated organ injury, and improved survival after gut I/R. Administration of a specific ghrelin receptor antagonist worsened gut I/R-induced organ injury and mortality. To determine whether ghrelin’s beneficial effects after gut I/R require the intact vagus nerve, vagotomy was performed in sham and gut I/R animals immediately prior to the induction of gut ischemia. Our result showed that vagotomy completely eliminated ghrelin’s beneficial effect after gut I/R. To further confirm that ghrelin’s beneficial effects after gut I/R are mediated through the central nervous system, intracerebroventricular administration of ghrelin was performed at the beginning of reperfusion after 90-min gut ischemia. Our result showed that intracerebroventricular injection of ghrelin also protected the rats from gut I/R injury. These findings suggest that ghrelin attenuates excessive inflammation and reduces organ injury after gut I/R through activation of the cholinergic anti-inflammatory pathway.

Life Expectancy Worsening Or Stagnating For Large Segment Of U.S. Population:

One of the major aims of the U.S. health system is improving the health of all people, particularly those segments of the population at greater risk of health disparities. In fact, overall life expectancy in the U.S. increased more than seven years for men and more than six years for women between 1960 and 2000. Now, a new, long-term study of mortality trends in U.S. counties over the same four decades reports a troubling finding: These gains are not reaching many parts of the country; rather, the life expectancy of a significant segment of the population is declining or at best stagnating.

Shell-breaking Crabs Lived 20 Million Years Earlier Than Thought:

While waiting for colleagues at a small natural history museum in the state of Chiapas, Mexico last year, Cornell paleontologist Greg Dietl chanced upon a discovery that has helped rewrite the evolutionary history of crabs and the shelled mollusks upon which they preyed.

Birds Announce Their Sentry Duty To Help Comrades Get A Good Meal:

Soldiers on sentry duty in hostile territory keep in regular radio contact with their colleagues to assure them that all is well and that they are safe to carry on their manoeuvres. New research reveals that this is also a feature of the bird world and is very likely to be a rare example of truly cooperative behaviour.

Variety Is The Spice Of Life: Too Many Males, Too Little Time…:

Female Australian painted dragon lizards are polyandrous, that is, they mate with as many males as they can safely get access to. This promiscuous behaviour is often found in species where male quality is dubious and there are high levels of infertility in the male population.

Building A Global Reference Library Of DNA Barcodes Of Marine Life:

Most of us are familiar with bar codes, those small black stripes with numbers below, known as the Universal Product Code or UPC label, that appear on commercial products. We scan them at the grocery store or to check a price, or have to cut them out and send them in for a rebate.