This week in Nature, a Japanese and American research team found the first evidence that mammalian genomes contain sequences from non-retroviral RNA viruses. The endogenous Borna-like N or EBLN elements, named for their similarity to sequences from a group bornaviruses, showed up in the genomes of humans, non-human primates, rodents, and other mammals. "Our results … give novel insights not only into generation of endogenous elements, but also into a role of bornavirus as a source of genetic novelty in its host," they write. For more information, check out a related news story in our sister publication GenomeWeb Daily News.
Researchers from the University of British Columbia and the BC Cancer Agency came up with a way to distinguish between sister chromatids in mouse metaphase chromosomes. Using a method called chromosome orientation fluorescence in situ hybridization or CO-FISH, they were able to tell the Watson from Crick DNA strands in sister chromatids. They then followed repetitive DNA orientation to track the sister chromatids as they segregated during mitosis.
In an advance, online paper, Andy Futreal and his colleagues sequenced 3,544 protein-coding genes in 101 clear cell renal cell carcinoma cases. The kidney cancer usually involves mutations in a gene called VHL. But sequencing revealed additional mutations in two histone modifying enzymes and a histone H3 27 demethylase enzyme, suggesting chromatin modifications are also involved. The findings highlight the genetic heterogeneity in cancers, the team notes, even those thought to involve single genes. "[S]ystematic screens will be key to fully determining the somatic genetic architecture of cancer," they write.
Robert Blelloch and his co-workers examined the role that microRNAs play in mouse embryonic stem cell self-renewal. They found that one family of miRNAs, including let-7, inhibits a group of self-renewal genes while another indirectly activates them. "Together, these findings show how the [embryonic stem cell cycle regulating] and let-7 miRNAs act through common pathways to alternatively stabilize the self-renewing versus differentiated cell fates," the researchers write.