In Science this week, Eric Nestler and his team explore the epigenetics of cocaine addiction. They found that repeated cocaine exposure in mice is linked to decreased histone 3 lysine 9 dimethylation levels in the nucleus accumbens, a brain region involved in reward and pleasure circuitry. This decrease appears to be a consequence of reduced lysine dimethyltransferase G9a enzyme activity, they report, which may contribute to neuronal changes in this part of the brain following repeated cocaine use. A related news story is available at our sister publication GenomeWeb Daily News.
Researchers from Santaris Pharma, the Southwest Foundation for Biomedical Research, and Denmark's Aalborg University report that treatment with a locked nucleic acid or LNA-modified oligonucleotide called SPC3649, which silences the liver-expressed microRNA-122, can suppress hepatitis C infection in chimps. Our sister publication RNAi News covered the online version of the paper here.
Danisco researchers Philippe Horvath and Rodolphe Barrangou review clustered regularly interspaced short palindromic repeats, or CRISPR sequences, that help protect some bacteria and archaea from viruses and other nucleic acid interlopers. "CRISPR features may be exploited for typing purposes, epidemiological studies, host-virus ecological surveys, building specific immunity against undesirable genetic elements, and enhancing viral resistance in domesticated microbes," the pair writes.
In the advance, online edition of the journal, Pardis Sabeti and her co-workers report on their composite of multiple signals, or CMS, method for identifying signals of positive selection in the human genome. By examining nearly 200 regions implicated as being under positive selection in HapMap data, the team narrowed in on population-specific signals of selection in genes contributing to processes such as sensory perception, metabolism, skin pigmentation, and immune function. For more information, check out a news story from our sister publication GWDN.