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This Week in PNAS: Jun 23, 2015

In the early, online edition of the Proceedings of the National Academy of Sciences, researchers from the University of Melbourne, the Wellcome Trust Sanger Centre, and elsewhere present findings from an analysis focused on the increasingly tricky-to-treat pathogen Klebsiella pneumoniae, which has been linked to hospital- and community-acquired infections. The team did whole-genome sequencing on 288 clinical or animal isolates of K. pneumoniae in an effort to understand the bug's antimicrobial resistance properties, genetic diversity, and population patterns. When they compared the genomes to one another and to 40 isolates sequenced in the past, the investigators uncovered features that fit with three distinct K. pneumoniae species: K. pneumoniae, K. quasipneumoniae, and K. variicola. GenomeWeb has more on the study, here.

By applying a genome-wide association study approach to inbred — and fully sequenced — fruit fly lines from the Drosophila Genetic Reference Panel, a team from North Carolina State University tracked down new and known genes that appear to correspond to aggressive fruit fly behavior. These included genes related to nervous system development and function, along with gustatory receptor and other genes. Researchers verified more than three-quarters of the candidate aggression-related genes using RNA interference assays aimed at knocking down genes, identifying additional genetic interactions in the process. In particular, they uncovered apparent epistatic interactions suspected of producing cryptic genetic variation in fruit fly lines from the DGRP collection.

Finally, researchers from Cornell University and the University of Rochester report on the genetic and epigenetic profiles they found when searching for the basis of sex-biased gene expression in the jewel wasp species Nasonia vitripennis and N. giraulti. Using RNA sequencing and whole-genome bisulfite sequencing, the team assessed whole body samples from male and female representatives of both jewel wasp species. Due to extensive sex-biased expression in these species, the study's author found that males from each species shared more transcriptional features than female counterparts from the same species and vice versa, though methylation patterns remained similar between male and female members of the same species.