Yearly Archives: 2007

New articles in PLoS Pathogens, PLoS Computational Biology and PLoS Genetics were published on Friday. My picks for this week are:
Influenza Virus Transmission Is Dependent on Relative Humidity and Temperature:

In temperate regions influenza epidemics recur with marked seasonality: in the northern hemisphere the influenza season spans November to March, while in the southern hemisphere epidemics last from May until September. Although seasonality is one of the most familiar features of influenza, it is also one of the least understood. Indoor crowding during cold weather, seasonal fluctuations in host immune responses, and environmental factors, including relative humidity, temperature, and UV radiation have all been suggested to account for this phenomenon, but none of these hypotheses has been tested directly. Using the guinea pig model, we have evaluated the effects of temperature and relative humidity on influenza virus spread. By housing infected and naïve guinea pigs together in an environmental chamber, we carried out transmission experiments under conditions of controlled temperature and humidity. We found that low relative humidities of 20%-35% were most favorable, while transmission was completely blocked at a high relative humidity of 80%. Furthermore, when guinea pigs were kept at 5 °C, transmission occurred with greater frequency than at 20 °C, while at 30 °C, no transmission was detected. Our data implicate low relative humidities produced by indoor heating and cold temperatures as features of winter that favor influenza virus spread.

Brightness and Darkness as Perceptual Dimensions:

Vision scientists have long adhered to the classic opponent-coding theory of vision, which states that bright-dark, red-green, and blue-yellow form mutually exclusive color pairs. According to this theory, it is not possible to see both brightness and darkness at a single spatial location, or an extended set of locations, such as a uniform surface. One corollary of this statement is that all perceivable grey shades vary along a continuum from bright to dark. At first glance, the notion that brightness and darkness cannot coexist on a single surface accords with our common-sense notion that a given grey shade cannot be simultaneously both brighter and darker than any other grey shade. The results presented here suggest that this common-sense notion is not supported by experimental data. Our results imply that a given grey shade can indeed be simultaneously brighter and darker than another grey shade. This seemingly paradoxical conclusion arises naturally if one assumes that brightness and darkness constitute the dimensions of a two-dimensional perceptual space in which points represent grey shades. Our results may encourage scientists working in related fields to question the assumption that perceptual variables, rather than sensory variables, are encoded in opponent pairs.

Copy Number Variants and Common Disorders: Filling the Gaps and Exploring Complexity in Genome-Wide Association Studies:

Genome-wide association scans (GWASs) using single nucleotide polymorphisms (SNPs) have been completed successfully for several common disorders and have detected over 30 new associations. Considering the large sample sizes and genome-wide SNP coverage of the scans, one might have expected many of the common variants underpinning the genetic component of various disorders to have been identified by now. However, these studies have not evaluated the contribution of other forms of genetic variation, such as structural variation, mainly in the form of copy number variants (CNVs). Known CNVs account for over 15% of the assembled human genome sequence. Since CNVs are not easily tagged by SNPs, might have a wide range of copy number variability, and often fall in genomic regions not well covered by whole-genome arrays or not genotyped by the HapMap project, current GWASs have largely missed the contribution of CNVs to complex disorders. In fact, some CNVs have already been reported to show association with several complex disorders using candidate gene/region approaches, underpinning the importance of regions not investigated in current GWASs. This reveals the need for new generation arrays (some already in the market) and the use of tailored approaches to explore the full dimension of genome variability beyond the single nucleotide scale.

Power Of Altruism Confirmed In Wikipedia Contributions:

The beauty of open-source applications is that they are continually improved and updated by those who use them and care about them. Dartmouth researchers looked at the online encyclopedia Wikipedia to determine if the anonymous, infrequent contributors, the Good Samaritans, are as reliable as the people who update constantly and have a reputation to maintain.

X-effect: Female Chromosome Confirmed A Prime Driver Of Speciation:

Researchers at the University of Rochester believe they have just confirmed a controversial theory of evolution. The X chromosome is a strikingly powerful force in the origin of new species.

Accessory Protein Determines Whether Pheromones Are Detected:

Pheromones are like the molecules you taste as you chomp on a greasy french fry: big and fatty. In research to be published in Nature*, Rockefeller University researchers reveal an unanticipated role for a new CD36-like protein to help cells detect these invisible communication signals that drive a wide range of behaviors, from recognizing a sibling to courting a mate, a finding that may explain what pheromone communication, pathogen recognition and fat taste perception all have in common.

Women More Likely Than Men To Be Affected By Acne As Adults:

While acne is oftentimes as much a part of being a teenager as dating and Friday night football games, a new study examining the prevalence of acne in adults age 20 and older confirms that a significant proportion of adults continue to be plagued by acne well beyond the teenage years. In particular, women experience acne at higher rates than their male counterparts across all age groups 20 years and older.

Sex Hormone Signature Indicates Gender Rather Than Just Chromosomes:

Help with assigning gender could one day be at hand for intersex individuals whose genital phenotypes and sex chromosomes don’t match, thanks to the discovery of a stable sex hormone signature in our cells.

How Singing Bats Communicate:

Bats are the most vocal mammals other than humans, and understanding how they communicate during their nocturnal outings could lead to better treatments for human speech disorders, say researchers at Texas A&M University.

Anne-Marie has more on this story.

Feeling Sleepy Is All In Your Genes:

Genes responsible for our 24 hour body clock influence not only the timing of sleep, but also appear to be central to the actual restorative process of sleep, according to research published in BMC Neuroscience. The study identified changes in the brain that lead to the increased desire and need for sleep during time spent awake.

Cringe at the title. Someone please send me the paper itself…
Level Of Oxytocin In Pregnant Women Predicts Mother-child Bond:

Humans are hard-wired to form enduring bonds with others. One of the primary bonds across the mammalian species is the mother-infant bond. Evolutionarily speaking, it is in a mother’s best interest to foster the well-being of her child; however, some mothers just seem a bit more maternal than others do. Now, new research points to a hormone that predicts the level of bonding between mother and child.

Kate already covered this study expertly.
Modafinil Is Effective In Treating Excessive Sleepiness, Study Suggests:

A study published in the October 15 issue of the Journal of Clinical Sleep Medicine finds that modafinil is well-tolerated in the treatment of excessive sleepiness associated with disorders of sleep and wakefulness such as shift work sleep disorder, obstructive sleep apnea (OSA) and narcolepsy, and does not affect cardiovascular or sleep parameters.

Feminism And Romance Go Hand In Hand:

Contrary to popular opinion, feminism and romance are not incompatible and feminism may actually improve the quality of heterosexual relationships, according to Laurie Rudman and Julie Phelan, from Rutgers University in the US. Their study* also shows that unflattering feminist stereotypes, that tend to stigmatize feminists as unattractive and sexually unappealing, are unsupported.

Pathway Required For Normal Reproductive Development Identified:

Massachusetts General Hospital (MGH) clinical researchers, in collaboration with basic scientists from the University of California, Irvine (UC Irvine) have identified a new molecular pathway required for normal development of the reproductive, olfactory and circadian systems in both humans and mice. In their report to appear in the Proceedings of the National Academy of Sciences, the team describes defects in a gene called PROK2 (prokineticin 2) in human siblings with two different forms of infertility. The UC Irvine team had previously reported that mice lacking PROK2 had abnormal olfactory structures and disrupted circadian rhythm.

I’d like to read this paper as well, please….

Dawn Of Animal Vision Discovered:

By peering deep into evolutionary history, scientists at the University of California, Santa Barbara have discovered the origins of photosensitivity in animals. The scientists studied the aquatic animal Hydra, a member of Cnidaria, which are animals that have existed for hundreds of millions of years. The authors are the first scientists to look at light-receptive genes in cnidarians, an ancient class of animals that includes corals, jellyfish, and sea anemones.

Ecologists Discover City Is ‘Uber-forest’ For Big Owls:

Charlotte has a spooky secret: the North Carolina city is home to a robust population of very large barred owls — a species long-believed by ornithologists to require old growth forest for survival. According to ecologists doing the most extensive field study ever done on the species, the owls see urban life as an upgrade on the old woods, and Charlotteans are not at all creeped out by the big birds that share their yards.

Endangered Wild Ox Given Lifeline:

Twenty years after its discovery in the forested mountains of Vietnam, local authorities here have agreed to establish new nature reserves to protect a critically endangered wild ox.