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This Week in Science: Mar 23, 2013

In Science this week, researchers from Stanford University reported on the discovery that the Wnt family of proteins can affect the division of embryonic stem cells based on their positions outside of the dividing cells, rather than the concentration of their signals as previously thought. The team attached Wnt3a molecules, known to maintain stem cell pluripotency, to beads that were then introduced to dividing stem cells and observed the effects using time-lapse microscopy. They found that daughter cells closest to the beads maintained pluripotency while those farther away differentiated. The findings suggest a “mechanism for external control of asymmetric stem cell division and differentiation.”

Also in Science, a team of French investigators revealed the genetic basis for the appearance of black spots of the wings of certain species of Drosophila melanogaster, offering insights into the emergence and diversification of novel traits among related species. The scientists pinpointed where a gene required for black pigmentation patterns is expressed on the fly wing, which allowed them to uncover other genes expressed in other such regions and map the genes’ interactions. “These results suggest that the genetic changes underlying the emergence and diversification of wing pigmentation patterns are partitioned within genetic networks.”

The Scan

Rise of B.1.617.2 in the UK

According to the Guardian, UK officials expect the B.1.617.2 variant to soon be the dominant version of SARS-CoV-2 there.

Anne Schuchat to Retire

Anne Schuchat is retiring after more than 30 years at the US Centers for Disease Control and Prevention, Politico reports.

US to Share More Vaccines

CNN reports that the US will share 20 million doses of the Moderna, Pfizer, and Johnson & Johnson SARS-CoV-2 vaccines with other countries.

PNAS Papers on Gene Therapy Platform, Aspergillus Metabolome, Undernutrition Model Microbiome

In PNAS this week: approach to deliver protein-based treatments to cells, pan-secondary metabolome of Aspergillus, and more.