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This Week in Genome Research: Aug 19, 2015

A team from France, Thailand, and the UK used targeted sequencing to track down resistance-related copy number changes in the dengue virus-transmitting mosquito species Aedes aegypti. By sequencing 760 candidate genes in Ae. aegypti with different insecticide susceptibility or resistance profiles from several different genetic backgrounds, the researchers narrowed in on 41 resistance-related amplifications and tens of thousands of SNPs suspected of influencing drug response. Such variants tended to turn up in conserved parts of the genome in any given geographic region, the study's authors explain, but varied by continent. "By identifying novel DNA markers of insecticide resistance," they write, "this study opens the way for tracking down metabolic changes developed by mosquitoes to resist insecticides within and among populations."

The National Human Genome Research Institute's Elaine Ostrander and colleagues used a combination of genome sequencing, genotyping, and/or comparative genomics to try to retrace the roots of a parasitic dog cancer called canine transmissible venereal tumor (CTVT). The team compared genome-wide variation patterns in 186 dog genomes with those in two available CTVT genomes, searching for mutations that allow the cancer clone to be transferred between dogs, while weeding out variants present in the founder CTVT genome. The analysis pointed to early and ongoing mutations in immune-related genes such as self-antigen presentation, for example, as well as genes related to oncogenesis.

Finally, a UK team took a look at the population patterns present in Streptococcus equi, a bacterial pathogen best known for causing a widespread horse disease called strangles. The researchers sequenced 224 S. equi isolates, including representatives from 40 outbreaks around the world, another 180 isolates from acute or persistent infections in UK horses, and isolates used in live, attenuated strangles vaccines. By comparing these sequences with one another, the study's authors found that the pathogen has a dynamic genome that tends to lose, gain, amplify, and mutated genes, while using convergent evolution to establish persistent and less virulent disease in horses over time.