BIOLOGICAL CHEMISTRY: DNA Copier Component Found to Be Real Drag
A new study sheds light on a longstanding puzzle in DNA replication: how do the enzymes that copy the two strands of DNA manage to coordinate their separate movements while still remaining in sync? The answer, detailed in the Feb. 2 Nature by (left to right) Samir Hamdan, Antoine van Oijen, Jong-Bong Lee, and colleagues, is that replication on the leading strand, which can progress much more quickly, pauses to wait for replication on the lagging strand to catch up. The enzyme that constructs short primers on the lagging strand acts as a brake to slow the leading strand’s progress.

NEUROSCIENCE: Protein Underlies Brain’s Response to Activity
Two independent teams of HMS researchers have identified a protein that plays key roles in one of neurobiology’s biggest mysteries—how individual experience shapes the brain. The researchers report in the Feb. 17 Science that the protein, MEF2, either pares down or promotes a neuron’s synapses, depending on whether or not the neuron is being activated. The uncovering of MEF2 could lead to a new understanding of psychiatric and neurodegenerative diseases, said Azad Bonni who, with Aryaman Shalizi, Brice Gaudillière, and colleagues, authored one of the papers. Steven Flavell, Tae-Kyung Kim, and Michael Greenberg, who led the other team, believe that the MEF2 pathway could play a role in autism and other neurodevelopmental diseases. Flavell (left) and Kim appear in the top photo, Shalizi (left) and Gaudillière in the bottom photo.

HEALTH CARE POLICY: Social Network Study Predicts Health Risks from Spouse Falling Ill
Researchers are just beginning to explore how the health of people is connected in ways that have nothing to do with the biological spread of disease. In the largest study of its kind, Nicholas Christakis found that the hospitalization of a husband or wife can increase the risk of illness and death for the partner. A partner faced the highest risk in the first month of a sick spouse’s hospitalization, and more disabling diseases were more dangerous to the partner in the long term, according to the study of a half million married couples older than 65. The findings appear in the Feb. 16 New England Journal of Medicine.