In a paper appearing in Science Translational Medicine, scientists led by Washington University's Jeffrey Gordon created "humanized gnotobiotic mice" in order to study the effects of diet on the human gut microbial community. Feeding human feces to germ-free mice, they were able to create an animal model of the human gut microbiota, and then they tested how it reacted to certain diets. On a high-fat, high-sugar "Western" diet — as opposed to a low-fat, plant polysaccharide-rich diet — the mice developed a different microbiota within a day and showed increased adiposity. "The point of it all is to allow more precise investigation of how human gut bacteria work," says a story in The Economist.
In this week's issue of Science, an editorial from Bruce Alberts gives advice to young scientist on how to choose a mentor — "what constitutes a 'good' choice is not always obvious," he says. First, choose a lab that's led by a scientist with both high scientific and ethical standards, and who's got the time and inclination to offer support. "Often, an established leader who has no more than about a dozen people to manage can best nurture a creative, exciting, and supportive place to work. But carrying out research with an outstanding new professor with a very small group can frequently provide even better training," Alberts says.
Researchers have looked at what's behind Treg cell differentiation into specific T helper cell lineages. Scientists at Memorial Sloan-Kettering Cancer Center found that the transcription factor Stat3, which is needed to help Treg cells differentiate into TH17 cells, is also required to suppress the over-activation of the immune response by these same helper cells. They showed that mice with a deletion in Stat3 died of an intestinal inflammatory disease driven by uncontrolled T helper 17 response.
A series of papers study the model nematode, Caenorhabditis elegans. In one, scientists at the Fred Hutchinson Cancer Research Center found that starvation induces adult reproductive diapause. During periods of starvation, they saw that the entire germ line died except for a few select cells, which are saved to regenerate a new germ line that can reproduce. Importantly, the "starvation-sensing nuclear receptor NHR-49 is required for ARD entry and recovery," they write in the abstract. In work led by Ronald Ellis at the University of Medicine and Dentistry of New Jersey, scientists used RNAi to show that by lowering expression of two genes, tra-2 and swm-1, they could turn females of a related species, C. remanei, into hermaphrodites. Other research led by Piali Sengupta at Brandeis University showed that the G protein-coupled receptors SRBC-64 and SRBC-66 affect dauer larval stage formation in response to certain dauer pheromone chemicals. A perspective from Max Planck scientists Akira Ogawa and Ralf Sommer delves further.