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This Week in PNAS: Jan 29, 2013

In the early, online edition of the Proceedings of the National Academy of Sciences, researchers with the Georgia Institute of Technology and the National Aeronautics and Space Administration report on findings from a microbiome study centered on atmospheric samples collected between one and 10 kilometers above the ocean and land as part of NASA's Genesis and Rapid Intensification Processes campaign. Using quantitative PCR, microscopy, and small subunit ribosomal RNA sequence data, the team profiled and quantified microbial community members in these samples, comparing communities found at the high altitude (10 km samples) with those at the low altitude (1 to 4 km), and exploring their relationships with atmospheric features and tropical storm systems.

Our sister publication GenomeWeb Daily News has more on the study, here.

A team from the US and Italy track down recurrent gene mutations and copy number alterations in an aggressive form of endometrial cancer called uterine serous carcinoma. The researchers sequenced the whole exomes of 57 uterine serous carcinoma tumors, along with matched normal exome sequencing of nearly three dozen of the samples. Though most of the tumors harbored relatively few mutations apiece, they report, a handful of uterine serous carcinomas contained thousands of mutations — a pattern that the researchers attributed to apparent defects in DNA repair. Across the broader tumor set, meanwhile, frequently mutated or copy number altered genes appeared in pathways involved processes such as DNA damage response, chromatin remodeling, and cell cycle/proliferation control.

The growth advantage of maize hybrid plants appears to be at least partly due to gene dosage effects and is not simply caused by complementation that covers up mildly deleterious mutations in the parental lines, according to another PNAS study. The University of Missouri, Columbia's James Birchler and his colleagues focused on nine maize traits in their study of hybrid vigor, also called heterosis, comparing eight well genotyped diploid or triploid maize lines over two summers. The group unearthed differences in the triploid and diploid lines that smacked of gene dosage effects, prompting them to conclude that "a major component of heterosis is a mechanism that is modulated by dosage-sensitive factors that involves allelic diversity across the genome."