In this week's Science, investigators from the Hebrew University of Jerusalem and elsewhere reconstructed full DNA methylation maps of Neanderthals and Denisovans — humans' closest extinct relatives — by examining the natural degradation processes of methylated and unmethylated cytosines. By comparing these maps with methylation maps of modern-day humans, the scientists identified about 2,000 differentially methylated regions, among them the HoxD gene cluster that influences body structure and limb placement and is less methylated in modern humans. They also found that the regions with the greatest differences in methylation in modern-day humans were about twice as likely to be associated with disease-related genes, many linked to psychiatric and neurological disorders.
Also in Science, a University of Colorado, Denver-led team reports the X-ray crystal structure of RNA from the flavivirus Murray Valley Encephalitis virus, giving insights into how it and related viruses like Ebola resist degradation by host cell endonucleases. They show that the virus produces small strands of RNA, dubbed sfRNA, that feature a knot-like arrangement that the team suspects that exonucleases cannot untangle.