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This Week in PNAS: May 5, 2009

In early online publication, a collaboration between Northwestern University Feinberg School of Medicine, the University of Chicago, and Cold Spring Harbor Laboratory defined the transcriptome of human CD34+ hematopoietic stem-progenitor cells, finding that early hematopoiesis is an "orchestrated process" involving more than half the human genes distributed in various functions. In other work, a consortium performed two GWAS and a meta-analysis of bipolar disorder in people of European ancestry, finding strong associations on 1p31.1, 3p21, and 5q15. These regions have genes implicated in cell cycle, neurogenesis, neuroplasticity, and neurosignaling.

In this week's issue of PNAS, University of Michigan scientists used phylogenetic analysis to study the evolution of piRNA clusters in mammals, finding that cluster expansion is driven by positive selection. Out of 140 rodent piRNA clusters, 14 were acquired after rats and mice diverged and another 44 after rodents and primates diverged, and most clusters came about by ectopic recombination "via insertions of long sequences that were mediated by flanking chromosome-specific repetitive elements," they write.

Also in this issue, chemists looked at disulfide-rich peptides in venom using ETD mass spectrometry. "The various species of marine cone shells have alone been estimated to produce [greater than] 50,000 distinct peptide venoms," they write in the abstract. Their analysis revealed full sequences for 31 peptide toxins from the crude venom of the cone snail, Conus textile.

Johns Hopkins' Joshua Mendell led work published this week that found that contact between cells activates miRNA biogenesis. As mammalian and Drosophila cell lines grew to increasing density, miRNA biogenesis was globally activated, leading to increased levels of mature miRNA, stronger target repression, enhanced processing of miRNAs by Drosha, and more efficient formation of RNA-induced silencing complexes, they say.

The Scan

Another Resignation

According to the Wall Street Journal, a third advisory panel member has resigned following the US Food and Drug Administration's approval of an Alzheimer's disease drug.

Novavax Finds Its Vaccine Effective

Reuters reports Novavax's SARS-CoV-2 vaccine is more than 90 percent effective in preventing COVID-19.

Can't Be Used

The US Food and Drug Administration says millions of vaccine doses made at an embattled manufacturing facility cannot be used, the New York Times reports.

PLOS Papers on Frozen Shoulder GWAS, Epstein-Barr Effects on Immune Cell Epigenetics, More

In PLOS this week: genome-wide association study of frozen shoulder, epigenetic patterns of Epstein-Barr-infected B lymphocyte cells, and more.