By sequencing Y chromosomes from several archaic humans, a team led by Max Planck Institute scientists provides new evidence that archaic Neanderthal Y chromosomes were replaced by introgressed Homo sapiens Y chromosomes. Data on the Y chromosomes of Denisovans and Neanderthals has been lacking because the majority that have been sequenced to sufficient coverage are female. To address this knowledge gap, the investigators used a targeted capture-based DNA sequencing method to enrich and extract Y chromosome DNA from two Denisovans and three Neanderthals. Their analysis revealed that the Y chromosomes of Denisovans split around 700,000 years ago from a lineage shared by Neanderthals and modern human Y chromosomes, which themselves diverged around 370,000 years ago. Further, the researchers found that human and Neanderthal Y chromosomes were more related to each other than to the Denisovan Y chromosome, indicating that interbreeding between early humans and Neanderthals and subsequent selection led to the replacement of more ancient Denisovan-like genetic material in late Neanderthals. GenomeWeb has more on this study, here.
New potential therapeutic targets for the neglected tropical disease Schistosomiasis, which is caused by parasitic flatworms called schistosomes, are reported in a pair of papers in Science this week. In the first, scientists from UT Southwestern Medical Center and the University of California, San Diego, used single-cell RNA sequencing to characterize thousands of cells from the adult schistosome. They identified 68 distinct cell populations, including specialized stem cells that are required to maintain the parasite's gut and ability to feed on host blood. In the second study, the UT Southwestern and Wellcome Sanger Institute scientists performed a large-scale RNAi screen in adult schistosomes and identified 261 genes associated with the neuromuscular function, tissue integrity, stem cell maintenance, and parasite survival. From these, the investigators uncovered a pair of protein kinases that, when lost, results in paralysis and worm death in a mammalian host.