In work out of Dave Bartel's MIT lab, researchers found that even though RNAi has not been conserved in the model budding yeast, Saccharomyces cerevisiae, it is present in other species, including S. castellii and Candida albicans. These two species use "noncanonical" Dicer proteins to make small interfering RNAs that mostly correspond to transposable elements and Y' subtelomeric repeats, they say, and when they introduced Dicer and Argonaute of S. castellii into S. cerevisiae, it restored RNAi. The work was published in this week's early online edition of Science.
In the current issue, Science editor Bruce Alberts has penned an editorial on the need to redefine cancer research. He says that more funding should be put into studying the therapeutic benefit of PARP inhibitors, with geneticists and molecular biologists, chemists, and experts in genomics and proteomics all weighing in with their expertise to better elucidate DNA repair pathways and the at least 150 different proteins that catalyze DNA repair, he says. "Often the discoveries that have the most profound impact on cancer treatments emanate from basic research on model organisms, rather than from studies of highly complex human tumors," he writes.
Susan Wessler at the University of Georgia, Athens, led research that used a genome-wide functional interaction screen to study how miniature inverted repeat transposable elements, which are widespread in eukaryotic genomes, originate and accumulate. The scientists' screen in the rice genome found that MITEs move by tapping into the functionality of the transposases of other mobile elements, called Osmars. The process, known known as cross-mobilization, is explained in more detail in a story in our sister publication, GenomeWeb Daily News, while a related perspective in Science delves deep.
In other work, scientists led by senior author Yumiko Saga at the National Institute of Genetics in Japan looked for regulators of sperm stem cells in mice. Using loss- and gain-of-function studies for the NANOS2 gene, they found that cells need this RNA-binding protein to maintain an undifferentiated state. "Thus, NANOS2 is a key stem cell regulator that is expressed in self-renewing spermatogonial stem cells and maintains the stem cell state during murine spermatogenesis," they write in the abstract.