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This Week in Science: Apr 12, 2019

In this week's Science, a multi-institute team publishes the results of a study examining the impact of long-term spaceflight on human biology. The study compared NASA astronaut Scott Kelly — who spent nearly a year in orbit — with his twin brother Mark — a former astronaut who remained on Earth as a genetically matched control. Among the spaceflight-associated changes identified were telomere elongation, genome instability, transcriptional and metabolic changes, and DNA methylation changes in immune and oxidative stress–related pathways. Notably, while changes in average telomere length, global gene expression, and the microbiome returned to near preflight levels within six months after Kelly's return to Earth, increased numbers of short telomeres were observed and expression of some genes was still disrupted. Although limited by its small size, the study provides "a valuable roadmap of the putative health risks for future human spaceflight," the authors write. GenomeWeb has more on this study, here.

And in Science Translational Medicine, a team led by scientists from Harvard Medical School report on the use of functional genomics to investigate an early bacterial outbreak caused by multidrug-resistant Enterococcus faecalis in patients in a Wisconsin hospital between 1984 and 1988. Genome sequence analysis revealed a progression of increasingly fixed mutations and repeated independent occurrences of mutations in a relatively small set of genes. The repeated independent mutations occurred within a small number of loci and suggest selection within the host during the course of infection in response to pressures such as host immunity and antibiotic treatment. Functional studies reveal that the mutations in these loci enable the bacteria to better withstand antibiotic pressure and innate immune defenses in the human bloodstream. Importantly, the researchers also identify a shift in mutation pattern that corresponded to the introduction of carbapenem antibiotics in 1987. The findings, they write, "highlight pathways that could be further leveraged in the future for control and management of nosocomial enterococcal infections."