In a paper published online in advance in Science this week, investigators at the Salk Institute for Biological Studies in La Jolla, Calif., and elsewhere report on their examination of "spontaneously occurring variation in DNA methylation in Arabidopsis thaliana plants propagated by single-seed descent for 30 generations." The Salk-led team observed 114,287 CG single-methylation polymorphisms as well as 2,485 CG differentially methylated regions, "both of which show patterns of divergence compared to the ancestral state." Overall, the team suggests that "transgenerational epigenetic variation in DNA methylation may generate new allelic states that alter transcription, providing a mechanism for phenotypic diversity in the absence of genetic mutation."
MIT's David Bartel and his colleagues this week show that reconstituting RNAi in Saccharomyces cerevisiae "causes loss of a beneficial double-stranded RNA virus known as killer virus." Bartel et al. say that an incompatibility exists between RNAi and killer viruses in yeast, and that such incompatibility "extends to other fungal species in that RNAi is absent in all species known to possess double-stranded RNA killer viruses, whereas killer viruses are absent in closely related species that retained RNAi."
The Fred Hutchinson Cancer Research Center's Bruce Knutson and Steven Hahn report in this week's Science that initiation mechanisms of among multi-subunit polymerases are conserved, and that this is a "key function of yeast core factor/human SL1 in Pol I transcription."
Samir Damani at the Scripps Translational Science Institute comments in Science Translational Medicine on Karsten Suhre et al.'s recent Nature paper, in which the authors coupled metabolomic analysis to a genome-wide association study. This work, Damani says, "underscores how the coupling of intermediate phenotypes with GWASs can illuminate disease-related biological pathways, validate previous genotype-phenotype correlations, and identify novel targets for therapeutic manipulation."