Gastric bypass surgery in mice alters the microbial makeup of their gut, and these changes may contribute to the rapid weight loss experienced after the surgery, according to a new study appearing in the 27 March issue of the journal Science Translational Medicine.

Researchers found that transplanting microbes harvested from mice that underwent surgery, into mice with no gut bacteria, led to weight loss (up to 5% of body weight) and decreased fat tissue in the mice who received the transplants.

Toxicologists have long held that the dose makes the poison: A substance can cause harm only in amounts high enough to overwhelm the body’s defenses. But a major conceptual shift is underway, a leading expert said recently at AAAS, with much more attention being paid to low-dose chemical exposures and the impact they can have even many years later.

The language and cognitive difficulties often seen in autism may be caused in part by an overly connected frontal lobe within the brain, says a new study of children published in Science Translational Medicine.

The research points to a gene called CNTNAP2 as responsible for wiring neurons in the front of the brain. If carrying different versions of CNTNAP2 is found to be a consistent predictor of language difficulties, the findings may help researchers design targeted therapies to assist the brain toward a path of more normative development early on.