In PLOS One, an international team led by investigators at Rutgers New Jersey Medical School describe a strategy to help find drug resistance in the tuberculosis (TB) pathogen Mycobacterium tuberculosis. The sequencing-based assay involves extracting DNA from Acid Fast Bacilli smears, followed by PCR amplification and sequencing of several M. tuberculosis gene segments, the team says. When the authors applied the approach to more than 1,200 clinical smear samples collected in Ghana, Kenya, Uganda, and Zambia, they uncovered resistance to one or more drugs in some 10 percent of the samples overall, and in far more samples collected from tuberculosis cases treated in the past. "Our assay demonstrated well-established associations of drug resistance with geographical region and TB treatment status," they report.
Researchers from Japan and the Philippines explore population structure in the dengue virus mosquito vector Aedes aegypti in an urban region in Manila for a paper in PLOS Neglected Tropical Diseases. Using microsatellite genotyping, the team assessed genetic diversity, population patterns, and more in more than 500 samples collected from 21 locations in the metropolitan Manila area, uncovering signs of significant gene flow and mosquito dispersal involving active mosquito movement and passive travel in conjunction with humans. "Our findings indicated the dual dispersal nature of Ae. aegypti," they write. "The use of microsatellites as genetic markers also allowed us to describe the potential long distance dispersal patterns, possible through human-aided land transportation via the existing road networks of Metropolitan Manila."
Finally, a pair of investigators from the University of Zurich and the University of Sheffield report on gene expression-based adaptations to variable heat and drought conditions in the red flour beetle model organism, Tribolium castaneum. As they report in PLOS Genetics, the researchers analyzed offspring numbers and transcriptome sequence data to get a look at the relationship between fitness and gene expression under different environmental conditions. "We found that variation in fitness can be attributed to gene expression variation and that selection pressures were environment dependent and opposite between control and stress conditions," the authors write, adding that "plastic responses of expression were largely adaptive."