In this week's Nature Biotechnology, a team from Massachusetts General Hospital reports on the development of a next-generation CRISPR-based gene-editing platform. Monomeric Cas9 nucleases are commonly used to induce the genomic alterations in CRISPR systems, but the researchers note that these often result in unwanted off-target mutations. To address this, the researchers developed dimeric RNA-guided FokI nucleases (RFNs) that can edit endogenous genes with high efficiencies in human cells. Because RFN-mediated cleavage depends on the binding of two specific types of RNA to a particular stretch of DNA, the likelihood that a target will occur more than once is substantially reduced. The team also describes a method to broaden the targeting range of RFNs.
Meanwhile, in Nature Communications, a multi-institute team led by researchers from The Gambia and London School of Hygiene and Tropical Medicine published a study showing that variations in a mother's diet at the time of conception can affect DNA methylation at specific genes in her offspring. They studied women in rural Gambia, who experience dramatic shifts in diet each year between the rainy and dry seasons. The scientists found that infants conceived during the rainy season have higher methylation levels in all six genes studied versus children born in the dry season. The findings suggest that maternal diet can trigger persistent changes in her children that could affect their development.