Body & Brain

The taste of fat
Fat may be ready to join the ranks of sweet, bitter, sour, salty and savory as the sixth basic kind of taste. Fat molecules trigger responses from taste cells in mice by hitting a particular molecular sensor, scientists report in the June 8 Journal of Neuroscience. The results argue against the predominant view that fat is tasteless, loveable for its texture. Mice engineered to lack the newly identified fat sensor, a protein called TRPM5, on their taste cells no longer preferred fat-laced liquid, researchers from Utah State University in Logan show. Figuring out how cells sense and respond to fat may help scientists understand why it’s so hard to resist fatty foods. —Laura Sanders  

Crossword-puzzle vision
Taste preferences aside, the brain may prefer the chocolate cookies in an Oreo better over the cream filling. People pick out black shapes from a noisy background quicker and more accurately than white shapes, say researchers from the College of Optometry at the State University of New York in New York City. When presented with a crossword puzzle–like black-and-white mosaic, study subjects recognized large, hidden black squares correctly 92 percent of the time versus 83 percent for similar white squares. This disparity may indicate that in the first steps of image processing, more resources are dedicated to seeing dark rather than light colors, the group reports in the June 8 Journal of Neuroscience. —Daniel Strain

Epilepsy drugs risk birth defects
Drugs taken by pregnant women for epileptic seizures increase the risk of birth defects. A four-drug comparison published online June 6 in Lancet Neurology suggests that lamotrigine poses the least risk and valproic acid the most. A global team of more than 700 collaborators collected data on the use of these two drugs, plus carbamazepine and phenobarbital by 4,540 pregnant women who needed medication to control seizures that can harm a fetus.  The lowest rate of birth defects occurred in women on low-dose lamotrigine (2 percent) during pregnancy and the highest in women using high-dose valproic acid (24 percent). The other drugs fell between these levels, and high doses increased risk with all four drugs. —Nathan Seppa

Clue to metastasis
White blood cells called macrophages, which normally play a protective role in immunity, also show up in breast cancers prone to spread. Reporting June 8 in Nature, researchers at the Albert Einstein College of Medicine in New York City and Ortho Biotech in King of Prussia, Penn., reveal that macrophage precursor cells called inflammatory monocytes — which produce a signaling protein called CCL2 — show up more often in breast tumors that metastasize than in stay-at-home tumors. Tests in mice show that inhibiting CCL2 from binding to a partner protein bogs down tumor metastasis and prolongs the animals’ survival, suggesting that CCL2 and the monocytes that make them could be drug targets. —Nathan Seppa

Timing of IUD insertion
Immediate insertion of an intrauterine device for birth control after an induced abortion or miscarriage may pose risks. Researchers report that 13 of 258 women (5 percent) randomly assigned to get an IUD inserted immediately after an abortion or miscarriage experienced IUD expulsion, in which the device gets dislodged, over the subsequent six months. Of 317 women undergoing IUD insertion two to six weeks after abortion or miscarriage, 91 failed to show up for the procedure. Five of those women got pregnant over the next six months, illustrating the downside of such a delay. But of women who did get the IUD, only 6 of 226 experienced expulsion (2.7 percent). No IUD recipient in either group became pregnant, researchers from the Oregon Health and Science University and colleagues report in the June 9 New England Journal of Medicine. —Nathan Seppa

Screening for ovarian cancer
Women who get screened for ovarian cancer risk don’t survive any longer on average than those not screened, a study of nearly 80,000 women finds. Between 1993 and 2001, a U.S.-Canadian study team randomly assigned women to get standard care or to also receive an annual ovarian cancer screening, which included a vaginal ultrasound exam or a blood test for levels of a protein called CA-125. Since this protein is more common in tumor cells, especially ovarian cancers, it is a biomarker of risk. After an average follow-up of 13 years, the number of deaths due to ovarian cancer or other causes were roughly equal in the two groups, the researchers report in the June 8 Journal of the American Medical Association. —Nathan Seppa

Why smokers are skinny
Nicotine triggers a “not hungry” response in a select group of nerve cells in the brain, a study in mice shows. The results help explain how cigarettes curb appetite in some people. In the study, Marina Picciotto of Yale University School of Medicine and colleagues traced the effects of nicotine as it kicked off a series of molecular changes in the mouse brain. Particular nerve cells in the hypothalamus, a brain region known to control feeding behavior, can sense nicotine and tell the animal to reduce food intake, the team reports in the June 10 Science. —Laura Sanders