Fly, human mothers share a milk enzyme

Female tsetse flies produce only one egg at a time. The larva hatches in the mother’s uterus, and she feeds it with a milklike substance she produces.

Now, researchers report that tsetse milk contains an enzyme called sphingomyelinase, or sMase, that is also important in mammalian lactation.

And that means the flies can be used to help study issues in human lactation, said Joshua Benoit, an entomologist at Yale University who was involved with the research. He and his colleagues report their findings in the journal The Biology of Reproduction. Then there is sleeping sickness (and a related animal disease, nagana), which is caused by parasites transmitted by the bite of the tsetse fly. Sleeping sickness can be fatal if it is not treated early, and there is no vaccine for the disease.

The researchers believe that manipulating the production of the lactation enzyme in female flies could aid in reducing their population. This might be done by chemical spraying of the animals that the flies feed on, Benoit said. 

The neurological roots of lingering regret

Studies have suggested that older adults are better off letting go of regrets, while younger adults, with more time left to make life changes, may benefit more from holding on to them.

Now, German researchers are studying brain activity to understand the biological mechanism behind this phenomenon; they report their findings in the journal Science.

Using functional MRI scans, the researchers found that after facing a missed opportunity, young adults (average age 25) and depressed older adults (average age 65) had similar brain activity in a region called the ventral striatum, which is associated with feelings of regret. Healthy older individuals displayed a different brain pattern, suggesting that they were able to regulate their emotions more effectively. “It seems that we have a lifelong ability to use our brain to regulate our emotions, even when we are old,” said the study’s first author, Stefanie Brassen, a neuroscientist at University Medical Center Hamburg-Eppendorf.

She and her colleagues asked individuals to play a computer game designed to induce regret at a missed opportunity. Players could open boxes that contained either gold or a devil; if they reached the devil, the game ended and they lost all their loot. Players could decide at the end of each round whether they wanted to continue playing. After a missed opportunity, the young adults and depressed older adults played more aggressively in subsequent rounds, presumably because they held regrets from previous rounds. Healthy older adults, on the other hand, did not tend to take more risks in later rounds. By studying the underlying brain mechanisms connected with regret, Brassen said, it may be possible to provide exercises and training in emotion regulation.

Sindya N Bhanoo  
New York Times News Service

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