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This Week in PNAS: Mar 10, 2015

In the early, online edition of the Proceedings of the National Academy of Sciences, researchers from Denmark, the Netherlands, and the US report on their DNA sequencing of ancient samples from a 17th century burial ground on Saint Martin in their effort to understand the geographic origins of individuals involved in the transatlantic slave trade. After doing ancient DNA enrichment and sequencing on the samples, the team used comparisons with present-day individuals around the world to not only verify the African ancestry of the individuals, but also to trace their origins to specific regions and populations in Africa. GenomeWeb has more on the study here.

A team from Brazil, the US, and Italy describes changes in microRNA expression that appear to presage the development of retinopathy in mice. Using a mouse model, the researchers examined miR-17 family miRNA expression patterns and targets in relation to a form of retinal angiogenesis associated with prematurity. In that murine retinopathy of prematurity model, they saw a unanimous decline in miR-17 family miRNA expression during an early stage of the disease involving vascularization of the retina. The reduced expression of the miRNAs appears to enhance levels of proteins involved in angiogenesis, they note, including hypoxia-inducible factor 1-alpha and VEGFA.

Finally, Baylor College of Medicine researchers explore the mutational effects of environmental stressors such as heat, cold, low oxygen, or oxidative stress. The team focused on microsatellite repeats called long trinucleotide repeats, specifically repeats involving cytosine, adenine, and guanine. With the help of a green fluorescence protein-based assay, the investigators tracked the consequences of stress exposure in human cells. Their results suggest that stress-related trinucleotide repeat mutagenesis does not stem from processes such as mismatch repair or transcription, but rather from DNA re-replication instigated by stress response factors.