Genes & Cells

Walking, thinking crawdad
Researchers have identified a “get ready to walk” signal that lights up in a crayfish’s brain cells as the animal decides to start moving. Katsushi Kagaya and Masakazu Takahata of Hokkaido University in Japan tethered crayfish to the tops of balls. Electrodes picked up the activity of single brain cells as the animals — unprompted — started to walk. Just before the crayfish got moving, certain cells in the brain received a sequence of messages: First, the cells got activity-enhancing input from partner cells, and then the same cells received activity-curbing input. The signals, described in a paper appearing April 15 in Science, may prepare bodies for many different kinds of voluntary movements. —Laura Sanders

Restoring nerve cell insulation
A protein that controls cell growth may also determine when and where raw electrical wiring in the nervous system gets repaired. The protein, called Cdk2, helps control production of myelin, a type of insulation that coats nerve cells and speeds electrical messages. Cdk2 isn’t important during normal mouse development, but if the insulation breaks down the protein can halt repair, an international team of researchers reports in the April 18 Journal of Cell Biology. Mice lacking Cdk2 repaired more neurons with thicker insulation than normal mice did. The findings could help explain why people with multiple sclerosis have difficulty repairing damaged myelin. —Tina Hesman Saey

Timing birth
Genes that are evolving faster in humans than in other primates may also shorten pregnancies, sometimes resulting in premature birth, a new study finds.
Big brains and narrow pelvises have necessitated that humans give birth relatively earlier than other mammals, researchers led by Louis Muglia of Vanderbilt University in Nashville propose online April 14 in PLoS Genetics. The team examined 150 human genes that are quickly evolving and may be involved in advancing human delivery times to increase the odds that moms and babies will survive delivery.  One of those genes — the follicle-stimulating hormone receptor gene — contains genetic variants associated with premature birth in Finnish and African-American women. —Tina Hesman Saey