Yearly Archives: 2007

As always on Tuesdays late in the evening, there is a bunch of new papers published in PLoS ONE and here are my personal favourites of the week:
Oxytocin Increases Generosity in Humans:

Human beings routinely help strangers at costs to themselves. Sometimes the help offered is generous–offering more than the other expects. The proximate mechanisms supporting generosity are not well-understood, but several lines of research suggest a role for empathy. In this study, participants were infused with 40 IU oxytocin (OT) or placebo and engaged in a blinded, one-shot decision on how to split a sum of money with a stranger that could be rejected. Those on OT were 80% more generous than those given a placebo. OT had no effect on a unilateral monetary transfer task dissociating generosity from altruism. OT and altruism together predicted almost half the interpersonal variation in generosity. Notably, OT had twofold larger impact on generosity compared to altruism. This indicates that generosity is associated with both altruism as well as an emotional identification with another person.

Impaired Inhibitory Control in Recreational Cocaine Users:

Chronic use of cocaine is associated with impairment in response inhibition but it is an open question whether and to which degree findings from chronic users generalize to the upcoming type of recreational users. This study compared the ability to inhibit and execute behavioral responses in adult recreational users and in a cocaine-free-matched sample controlled for age, race, gender distribution, level of intelligence, and alcohol consumption. Response inhibition and response execution were measured by a stop-signal paradigm. Results show that users and non users are comparable in terms of response execution but users need significantly more time to inhibit responses to stop-signals than non users. Interestingly, the magnitude of the inhibitory deficit was positively correlated with the individuals lifetime cocaine exposure suggesting that the magnitude of the impairment is proportional to the degree of cocaine consumed.

Processing of Abstract Rule Violations in Audition:

The ability to encode rules and to detect rule-violating events outside the focus of attention is vital for adaptive behavior. Our brain recordings reveal that violations of abstract auditory rules are processed even when the sounds are unattended. When subjects performed a task related to the sounds but not to the rule, rule violations impaired task performance and activated a network involving supratemporal, parietal and frontal areas although none of the subjects acquired explicit knowledge of the rule or became aware of rule violations. When subjects tried to behaviorally detect rule violations, the brain’s automatic violation detection facilitated intentional detection. This shows the brain’s capacity for abstraction – an important cognitive function necessary to model the world. Our study provides the first evidence for the task-independence (i.e. automaticity) of this ability to encode abstract rules and for its immediate consequences for subsequent mental processes.

DNA Barcoding in the Cycadales: Testing the Potential of Proposed Barcoding Markers for Species Identification of Cycads:

The use of DNA barcoding to describe species that lack diagnostic features is becoming increasingly important for animal and plant conservation. In this paper, Specht and colleagues tested various genomic regions from a specific group of plants, the Cycadales, to see how effective these might be in providing unique species identifiers. The results enabled the researchers to suggest a workflow for producing and testing DNA barcoding data, which is an essential requirement to the establishment of a universal DNA barcode for plants.

A Major Ingredient of Green Tea Rescues Mice from Lethal Sepsis Partly by Inhibiting HMGB1:

The pathogenesis of sepsis is mediated in part by bacterial endotoxin, which stimulates macrophages/monocytes to sequentially release early (e.g., TNF, IL-1, and IFN-γ) and late (e.g., HMGB1) pro-inflammatory cytokines. Our recent discovery of HMGB1 as a late mediator of lethal sepsis has prompted investigation for development of new experimental therapeutics. We previously reported that green tea brewed from the leaves of the plant Camellia sinensis is effective in inhibiting endotoxin-induced HMGB1 release. Here we demonstrate that its major component, (-)-epigallocatechin-3-gallate (EGCG), but not catechin or ethyl gallate, dose-dependently abrogated HMGB1 release in macrophage/monocyte cultures, even when given 2-6 hours post LPS stimulation. Intraperitoneal administration of EGCG protected mice against lethal endotoxemia, and rescued mice from lethal sepsis even when the first dose was given 24 hours after cecal ligation and puncture. The therapeutic effects were partly attributable to: 1) attenuation of systemic accumulation of proinflammatory mediator (e.g., HMGB1) and surrogate marker (e.g., IL-6 and KC) of lethal sepsis; and 2) suppression of HMGB1-mediated inflammatory responses by preventing clustering of exogenous HMGB1 on macrophage cell surface. Taken together, these data suggest a novel mechanism by which the major green tea component, EGCG, protects against lethal endotoxemia and sepsis.

The Biomechanics of Amnion Rupture: An X-Ray Diffraction Study:

Pre-term birth is the leading cause of perinatal and neonatal mortality, 40% of which are attributed to the pre-term premature rupture of amnion. Rupture of amnion is thought to be associated with a corresponding decrease in the extracellular collagen content and/or increase in collagenase activity. However, there is very little information concerning the detailed organisation of fibrillar collagen in amnion and how this might influence rupture. Here we identify a loss of lattice like arrangement in collagen organisation from areas near to the rupture site, and present a 9% increase in fibril spacing and a 50% decrease in fibrillar organisation using quantitative measurements gained by transmission electron microscopy and the novel application of synchrotron X-ray diffraction. These data provide an accurate insight into the biomechanical process of amnion rupture and highlight X-ray diffraction as a new and powerful tool in our understanding of this process.

Unexpected High Losses of Anopheles gambiae Larvae Due to Rainfall:

Immature stages of the malaria mosquito Anopheles gambiae experience high mortality, but its cause is poorly understood. Here we study the impact of rainfall, one of the abiotic factors to which the immatures are frequently exposed, on their mortality. We show that rainfall significantly affected larval mosquitoes by flushing them out of their aquatic habitat and killing them. Outdoor experiments under natural conditions in Kenya revealed that the additional nightly loss of larvae caused by rainfall was on average 17.5% for the youngest (L1) larvae and 4.8% for the oldest (L4) larvae; an additional 10.5% (increase from 0.9 to 11.4%) of the L1 larvae and 3.3% (from 0.1 to 3.4%) of the L4 larvae were flushed away and larval mortality increased by 6.9% (from 4.6 to 11.5%) and 1.5% (from 4.1 to 5.6%) for L1 and L4 larvae, respectively, compared to nights without rain. On rainy nights, 1.3% and 0.7% of L1 and L4 larvae, respectively, were lost due to ejection from the breeding site. This study demonstrates that immature populations of malaria mosquitoes suffer high losses during rainfall events. As these populations are likely to experience several rain showers during their lifespan, rainfall will have a profound effect on the productivity of mosquito breeding sites and, as a result, on the transmission of malaria. These findings are discussed in the light of malaria risk and changing rainfall patterns in response to climate change.

Austro-Asiatic Tribes of Northeast India Provide Hitherto Missing Genetic Link between South and Southeast Asia:

Northeast India, the only region which currently forms a land bridge between the Indian subcontinent and Southeast Asia, has been proposed as an important corridor for the initial peopling of East Asia. Given that the Austro-Asiatic linguistic family is considered to be the oldest and spoken by certain tribes in India, Northeast India and entire Southeast Asia, we expect that populations of this family from Northeast India should provide the signatures of genetic link between Indian and Southeast Asian populations. In order to test this hypothesis, we analyzed mtDNA and Y-Chromosome SNP and STR data of the eight groups of the Austro-Asiatic Khasi from Northeast India and the neighboring Garo and compared with that of other relevant Asian populations. The results suggest that the Austro-Asiatic Khasi tribes of Northeast India represent a genetic continuity between the populations of South and Southeast Asia, thereby advocating that northeast India could have been a major corridor for the movement of populations from India to East/Southeast Asia.

Population Response to Habitat Fragmentation in a Stream-Dwelling Brook Trout Population:

Fragmentation can strongly influence population persistence and expression of life-history strategies in spatially-structured populations. In this study, we directly estimated size-specific dispersal, growth, and survival of stream-dwelling brook trout in a stream network with connected and naturally-isolated tributaries. We used multiple-generation, individual-based data to develop and parameterize a size-class and location-based population projection model, allowing us to test effects of fragmentation on population dynamics at local (i.e., subpopulation) and system-wide (i.e., metapopulation) scales, and to identify demographic rates which influence the persistence of isolated and fragmented populations. In the naturally-isolated tributary, persistence was associated with higher early juvenile survival (~45% greater), shorter generation time (one-half) and strong selection against large body size compared to the open system, resulting in a stage-distribution skewed towards younger, smaller fish. Simulating barriers to upstream migration into two currently-connected tributary populations caused rapid (2-6 generations) local extinction. These local extinctions in turn increased the likelihood of system-wide extinction, as tributaries could no longer function as population sources. Extinction could be prevented in the open system if sufficient immigrants from downstream areas were available, but the influx of individuals necessary to counteract fragmentation effects was high (7-46% of the total population annually). In the absence of sufficient immigration, a demographic change (higher early survival characteristic of the isolated tributary) was also sufficient to rescue the population from fragmentation, suggesting that the observed differences in size distributions between the naturally-isolated and open system may reflect an evolutionary response to isolation. Combined with strong genetic divergence between the isolated tributary and open system, these results suggest that local adaptation can ‘rescue’ isolated populations, particularly in one-dimensional stream networks where both natural and anthropogenically-mediated isolation is common. However, whether rescue will occur before extinction depends critically on the race between adaptation and reduced survival in response to fragmentation.

Randomised, Controlled, Assessor Blind Trial Comparing 4% Dimeticone Lotion with 0.5% Malathion Liquid for Head Louse Infestation:

Malathion 0.5% has been the most prescribed pediculicide in the United Kingdom for around 10 years, and is widely used in Europe and North America. Anecdotal reports suggest malathion treatments are less effective than formerly, but this has not been confirmed clinically. This study was designed to determine whether malathion is still effective and if 4% dimeticone lotion is a more effective treatment for head louse infestation. We designed this study as an assessor blinded, randomised, controlled, parallel group trial involving 58 children and 15 adults with active head louse infestation. Each participant received two applications 7 days apart of either 4% dimeticone lotion, applied for 8 hours or overnight, or 0.5% malathion liquid applied for 12 hours or overnight. All treatment and check-up visits were conducted in participants’ homes. Cure of infestation was defined as no evidence of head lice after the second treatment. Some people were found free from lice but later reinfested. Worst case, intention to treat, analysis found dimeticone was significantly more effective than malathion, with 30/43 (69.8%) participants cured using dimeticone compared with 10/30 (33.3%) using malathion (p<0.01, difference 36.4%, 95% confidence interval 14.7% to 58.2%). Per protocol analysis showed cure rates of 30/39 (76.9%) and 10/29 (34.5%) respectively. Irritant reactions were observed in only two participants, both treated with malathion. We concluded that, although malathion liquid is still effective for some people, dimeticone lotion offers a significantly more effective alternative treatment for most people.

Thermal Disruption of Mushroom Body Development and Odor Learning in Drosophila:

Environmental stress (nutritive, chemical, electromagnetic and thermal) has been shown to disrupt central nervous system (CNS) development in every model system studied to date. However, empirical linkages between stress, specific targets in the brain, and consequences for behavior have rarely been established. The present study experimentally demonstrates one such linkage by examining the effects of ecologically-relevant thermal stress on development of the Drosophila melanogaster mushroom body (MB), a conserved sensory integration and associative center in the insect brain. We show that a daily hyperthermic episode throughout larval and pupal development (1) severely disrupts MB anatomy by reducing intrinsic Kenyon cell (KC) neuron numbers but has little effect on other brain structures or general anatomy, and (2) greatly impairs associative odor learning in adults, despite having little effect on memory or sensory acuity. Hence, heat stress of ecologically relevant duration and intensity can impair brain development and learning potential.

How Global Is the Global Biodiversity Information Facility?:

There is a concerted global effort to digitize biodiversity occurrence data from herbarium and museum collections that together offer an unparalleled archive of life on Earth over the past few centuries. The Global Biodiversity Information Facility provides the largest single gateway to these data. Since 2004 it has provided a single point of access to specimen data from databases of biological surveys and collections. Biologists now have rapid access to more than 120 million observations, for use in many biological analyses. We investigate the quality and coverage of data digitally available, from the perspective of a biologist seeking distribution data for spatial analysis on a global scale. We present an example of automatic verification of geographic data using distributions from the International Legume Database and Information Service to test empirically, issues of geographic coverage and accuracy. There are over 1/2 million records covering 31% of all Legume species, and 84% of these records pass geographic validation. These data are not yet a global biodiversity resource for all species, or all countries. A user will encounter many biases and gaps in these data which should be understood before data are used or analyzed. The data are notably deficient in many of the world’s biodiversity hotspots. The deficiencies in data coverage can be resolved by an increased application of resources to digitize and publish data throughout these most diverse regions. But in the push to provide ever more data online, we should not forget that consistent data quality is of paramount importance if the data are to be useful in capturing a meaningful picture of life on Earth.

As always, go and read, rate, comment, annotate and trackback your blog posts….

Circadian Disorders And Adjusting To The Night Shift: Guide For Professionals:

Practice parameters are a guide to the appropriate assessment and treatment of circadian rhythm sleep disorders (CRSDs). The standards will have a positive impact on professional behavior, patient outcomes and possibly health care costs.

Sleep-related Breathing Disorder Linked To Increased Heart Rate Variability:

A sleep-related breathing disorder, common in heart failure, increases one’s heart rate variability. Further, central sleep apnea (CSA) and obstructive sleep apnea (OSA) produce different patterns of heart rate variability, which are likely to reflect the different pathophysiological mechanisms involved, according to a new study.

For Migrating Sparrows, Kids Have A Compass, But Adults Have The Map:

Even bird brains can get to know an entire continent — but it takes them a year of migration to do so, suggests a Princeton research team.

Smell You Later: Scientists Reveal How Mice Recognize Each Other:

Scientists at the University of Liverpool have discovered that mice rely on a special set of proteins to recognise each other. Previous study assumed that another set of genes that influence smell in vertebrates might be used by animals that identify each other through scent. The team found, however, that mice use a highly specialised set of proteins in their urine to recognise different individuals, suggesting that this may also be true of other animals.

New Species Of Peccary –pig-like Animal — Discovered In Amazon Region:

Dutch biologist Marc van Roosmalen has discovered a new species of peccary, a member of the pig family, in the basin of the Rio Aripuanã in the south-eastern Amazon region. The divergence time from the already known peccary species (the time which has passed since the evolutionary division) has been set at one to 1.2 million years.

Mice Influenced By Traumatic ‘Childhood’ Experiences:

How does the experience of traumatic stress in childhood affect one’s life in subsequent years? Leo Enthoven, a PhD student at the Leiden / Amsterdam Center for Drug Research (LACDR) and Leiden University Medical Center (LUMC) studied this subject in a laboratory animal model. He has achieved some remarkable results with mice, but cannot yet say anything about humans.

Tiger Numbers Could Be Doubled In South Asia:

Researchers at the Wildlife Conservation Society and other institutions declare that improvements in management of existing protected areas in South Asia could double the number of tigers currently existing in the region.

All Male or All Female Litter? Sex-ratio Meiotic Drive System Identified In Fruit Flies:

If you met a person who had 10 children, all of whom were girls, you would probably find this surprising. Yet this kind of distorted sex ratio does occur in groups as diverse as mammals, insects, and plants, where some parents consistently produce litters in which the sex ratio is dramatically skewed.

Rest For The Racehorse After Exercise:

Equine muscle glycogen stores require sufficient time for post-exercise repletion. Repletion cannot be hastened in any way other than rest.

Earliest Birds Acted More Like Turkeys Than Common Cuckoos:

The earliest birds acted more like turkeys than common cuckoos, according to a new report. By comparing the claw curvatures of ancient and modern birds, the researchers provide new evidence that the evolutionary ancestors of birds primarily made their livings on the ground rather than in trees.

Flying Lemurs Are The Closest Relatives Of Primates:

While the human species is unquestionably a member of the Primate group, the identity of the next closest group to primates within the entire class of living mammals has been hotly debated. Now, new molecular and genomic data gathered by a team including Webb Miller, a professor of biology and computer science and engineering at the Penn State University, has shown that the colugos — nicknamed the flying lemurs — is the closest group to the primates.

Anne-Marie has more.
Fossil Record Reveals Elusive Jellyfish More Than 500 Million Years Old:

Using recently discovered “fossil snapshots” found in rocks more than 500 million years old, three University of Kansas researchers have described the oldest definitive jellyfish ever found.

How Old Tree Rings And Ancient Wood Are Helping Rewrite History:

Cornell archaeologists are rewriting history with the help of tree rings from 900-year-old trees, wood found on ancient buildings and through analysis of the isotopes (especially radiocarbon dating) and chemistry they can find in that wood.

Burrowing Mammals Dig For A Living, But How Do They Do That?:

Next time you see a mole digging in tree-root-filled soil in search of supper, take a moment to ponder the mammal’s humerus bones. When seen in the lab, they are nothing like the long upper arm bones of any other mammal, says Samantha Hopkins, a paleontologist at the University of Oregon.

Hanging Around With Lemurs, The Planet’s Most Primitive Primates:

Nayuta Yamashita’s office is in the Alan Hancock Foundation Building, right in the heart of USC’s campus. But her lab, in the truest sense, is halfway around the world.

Tangled Web Of The Insect, Plant And Parasite Arms Race:

New insights into the evolutionary relationship between plant-dwelling insects and their parasites are revealed in the online open access journal BMC Biology. Researchers shed light on how sawflies evolved to escape their parasites and gain themselves an ‘enemy-free space’ for millions of years.

Fossilized Spider, 50 Million Years Old, Clear As Life:

A 50-million-year-old fossilised spider has been brought back to life in stunning 3D by a scientist at The University of Manchester.

Fossilized Body Imprints Of Amphibians Found In 330 Million-year-old Rocks:

Unprecedented fossilized body imprints of amphibians have been discovered in 330 million-year-old rocks from Pennsylvania. The imprints show the unmistakably webbed feet and bodies of three previously unknown, foot-long salamander-like critters that lived 100 million years before the first dinosaurs.

Volcanic Eruptions, Not Meteor, May Have Killed The Dinosaurs:

A series of monumental volcanic eruptions in India may have killed the dinosaurs 65 million years ago, not a meteor impact in the Gulf of Mexico. The eruptions, which created the gigantic Deccan Traps lava beds of India, are now the prime suspect in the most famous and persistent paleontological murder mystery, say scientists who have conducted a slew of new investigations honing down eruption timing.

Genetics Of Coat Color In Dogs May Help Explain Human Stress And Weight:

A discovery about the genetics of coat color in dogs could help explain why humans come in different weights and vary in our abilities to cope with stress, a team led by researchers from the Stanford University School of Medicine reports.

Drug Commonly Used To Treat Bipolar Disorder Dramatically Increases Lifespan In Worms:

Nematode worms treated with lithium show a 46 percent increase in lifespan, raising the tantalizing question of whether humans taking the mood affecting drug are also taking an anti-aging medication.

Whales For The Saving: Research Demonstrates Need For Speed Restrictions:

Dal research demonstrates need for speed restrictions to protect North Atlantic Right Whales in Canadian waters. There are less than 400 of them left in the world, and many of them travel to Canadian waters each year to feed. The North Atlantic Right Whale is one of the most endangered whales in the world.

Efficient Crowd Control In Bacterial Colonies:

Bacterial cells form colonies with complex organization (aka biofilms), particularly in response to hostile environmental conditions. Recent studies have shown that biofilm development occurs when bacterial cells seek out small cavities and populate them at high densities.

Rosemary Chicken Protects Your Brain From Free Radicals:

Rosemary not only tastes good in culinary dishes such as Rosemary chicken and lamb, but scientists have now found it is also good for your brain. A collaborative group from the Burnham Institute for Medical Research (Burnham Institute) in La Jolla, CA and in Japan, report that the herb rosemary contains an ingredient that fights off free radical damage in the brain.