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This Week in PNAS: May 22, 2018

A University of Oxford-led team takes a look at the relationship between genotype and insecticide resistance phenotypes in the Anopheles gambiae mosquito as part of a broader study quantifying insecticide resistance patterns in the African malaria vector. The researchers sampled An. gambiae from nearly 1,200 sites in Africa, profiling insecticide resistance and using a geostatistical modeling approach to consider co-variation in resistance to multiple insecticides. Along with these phenotypic variation and co-variation resistance patterns, they incorporated genotyping information to search for potential insecticide resistance markers in the An. gambiae species complex. "Given an appropriate sampling procedure," the authors note, "use of DNA diagnostics to predict resistance phenotypes could provide a means of increasing resistance data resources to support monitoring programs."

Researchers from the US and Denmark track transcriptome patterns in Pseudomonas aeruginosa during human infection, comparing the gene expression dynamics in this context with those found in laboratory models of the opportunistic bacterial pathogen. Among other transcriptome differences in detected in P. aeruginosa in vitro and in vivo, the team saw enhanced expression of suspected antibiotic resistance genes in the human infection context, but declining expression of bacterial quorum sensing genes that tended to be more active in the lab setting. "Determining what differentiates our current models from clinical infections is important to better understand bacterial infections and will be necessary to create model systems that more accurately capture the biology of infection."

A team from Korea, Spain, the US, and China describe chromatin epigenetic changes that accompany cold stress response and cold tolerance in the model plant Arabidopsis. Using yeast two-hybrid screens, co-immunoprecipitation assays, stress response assays, and other experimental approaches, the researchers uncovered interactions between the WD40 repeat protein HOS15, a histone deacetylase enzyme known as HD2C, and the promoter regions of COR genes implicated in cold response in the plant. From these and other results, the authors suggest that "cold induces HOS15-mediated chromatin modifications by degrading HD2C. This switches the chromatin structure status and facilitates recruitment of [CBF transcription factors] to the COR gene promoters."