New and Exciting in PLoS ONE

There are 27 brand-new articles, just uploaded on PLoS ONE. Here are a couple of titles that drew my immediate attention:

Maternal Enrichment during Pregnancy Accelerates Retinal Development of the Fetus:

Although much is known about the harmful effects parental stress has on offspring, little is understood about how enriching a mother's environment affects fetal development. In this paper, the authors experiment on developing rat embryos and find that an enriched environment speeds up the development of the nervous system. The results suggest that development of the visual system is sensitive to environmental stimulation during prenatal life.

Prior Exposure to Uninfected Mosquitoes Enhances Mortality in Naturally-Transmitted West Nile Virus Infection:

West Nile Virus has the potential to cause serious disease in humans; the virus is spread by infected mosquitoes and typically infection either results in no symptoms or in mild feverish symptoms. In this study, Higgs and colleagues found that mice that had already been exposed to the saliva from uninfected mosquitoes were subsequently more likely to die upon being infected with West Nile Virus. These findings suggest that prior exposure to mosquito saliva could potentially result in a worse outcome from West Nile Virus infection.

Gene Expression in Human Hippocampus from Cocaine Abusers Identifies Genes which Regulate Extracellular Matrix Remodeling:

People who have abused drugs in the past find it hard to avoid relapse because they remember the euphoria linked to previous drug use. In order to see if past drug abuse is associated with molecular changes in the brain, the researchers here carried out microarray analysis of samples of the hippocampus from individuals addicted to cocaine, and from control individuals. The microarray data identifies a number of genes which are up- or down-regulated in response to cocaine exposure.

Incidence and Tracking of Escherichia coli O157:H7 in a Major Produce Production Region in California:

Fresh vegetables have become associated with outbreaks caused by Escherichia coli O157:H7 (EcO157). Between 1995-2006, 22 produce outbreaks were documented in the United States, with nearly half traced to lettuce or spinach grown in California. Outbreaks between 2002 and 2006 induced investigations of possible sources of pre-harvest contamination on implicated farms in the Salinas and San Juan valleys of California, and a survey of the Salinas watershed. EcO157 was isolated at least once from 15 of 22 different watershed sites over a 19 month period. The incidence of EcO157 increased significantly when heavy rain caused an increased flow rate in the rivers. Approximately 1000 EcO157 isolates obtained from cultures of>100 individual samples were typed using Multi-Locus Variable-number-tandem-repeat Analysis (MLVA) to assist in identifying potential fate and transport of EcO157 in this region. A subset of these environmental isolates were typed by Pulse Field Gel Electrophoresis (PFGE) in order to make comparisons with human clinical isolates associated with outbreak and sporadic illness. Recurrence of identical and closely related EcO157 strains from specific locations in the Salinas and San Juan valleys suggests that transport of the pathogen is usually restricted. In a preliminary study, EcO157 was detected in water at multiple locations in a low-flow creek only within 135 meters of a point source. However, possible transport up to 32 km was detected during periods of higher water flow associated with flooding. During the 2006 baby spinach outbreak investigation, transport was also detected where water was unlikely to be involved. These results indicate that contamination of the environment is a dynamic process involving multiple sources and methods of transport. Intensive studies of the sources, incidence, fate and transport of EcO157 near produce production are required to determine the mechanisms of pre-harvest contamination and potential risks for human illness.

Different Neurophysiological Mechanisms Underlying Word and Rule Extraction from Speech:

The initial process of identifying words from spoken language and the detection of more subtle regularities underlying their structure are mandatory processes for language acquisition. Little is known about the cognitive mechanisms that allow us to extract these two types of information and their specific time-course of acquisition following initial contact with a new language. We report time-related electrophysiological changes that occurred while participants learned an artificial language. These changes strongly correlated with the discovery of the structural rules embedded in the words. These changes were clearly different from those related to word learning and occurred during the first minutes of exposition. There is a functional distinction in the nature of the electrophysiological signals during acquisition: an increase in negativity (N400) in the central electrodes is related to word-learning and development of a frontal positivity (P2) is related to rule-learning. In addition, the results of an online implicit and a post-learning test indicate that, once the rules of the language have been acquired, new words following the rule are processed as words of the language. By contrast, new words violating the rule induce syntax-related electrophysiological responses when inserted online in the stream (an early frontal negativity followed by a late posterior positivity) and clear lexical effects when presented in isolation (N400 modulation). The present study provides direct evidence suggesting that the mechanisms to extract words and structural dependencies from continuous speech are functionally segregated. When these mechanisms are engaged, the electrophysiological marker associated with rule-learning appears very quickly, during the earliest phases of exposition to a new language.

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