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This Week in PNAS: Sep 25, 2018

In the early, online version of the Proceedings of the National Academy of Sciences, a team from the US and Russia reports on efforts to trace the genomic consequences of domestication in the silver fox, Vulpes vulpes, model. Using RNA sequencing and other approaches, the team profiled gene expression and SNP allele frequency patterns in prefrontal cortex and basal forebrain samples from a dozen foxes selected for tameness over more than 50 generations since the late 1950s, and from 12 foxes in a population bred for aggressiveness over the same time period. The investigators found expression shifts involving nearly 200 genes in the brain areas considered, for example, including representatives from serotonergic and glutaminergic neuron pathways.

A Max Planck Institute for the Biology of Aging-led team takes a look at mitochondrial DNA mutations and their potential ties to aging in fruit flies. The investigators assessed lifespan, dietary restriction, and starvation response in Drosophila fruit flies with mutations introduced to make them more prone to mtDNA mutations. Based on their results, they note that "fruit flies are remarkably tolerant to mtDNA mutations, as exemplified by their lack of effect on physiology and lifespan." Indeed, the current results suggest that "[o]nly an artificially induced, very drastic increase of the mtDNA mutation load will lead to reduced lifespan," they write.

Finally, researchers in Norway and Italy characterize a 15th century isolate of Borrelia recurrentis, a spirochete pathogen that causes louse-borne relapsing fever. The team saw bits of B. recurrentis sequence by metagenomic sequencing on skeletal samples at a double grave in an Oslo graveyard. It went on to sequence 13 more genomic libraries from tooth samples to put together and analyze the medieval B. recurrentis assembly, which spanned more than 95 percent of the pathogen's existing reference sequence. "[W]e offer a historical snapshot of genomic changes in an immune-evasion system of reductive evolution in a specialized vector-borne human pathogen," the authors write. GenomeWeb has more on the study, here.