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Malaria, responsible for hundreds of thousands of deaths each year worldwide, is caused by a parasite transmitted through the salivary glands of female Anopheles mosquitoes.

Understanding the biology of these tissues is critical to developing new treatments for the disease, found mostly in tropical countries. Mosquitoes have an internal 24-hour clock that controls a variety of behaviors, including pheromone production, swarming, and mating. However, it has been unknown whether their salivary glands operate on a cyclic daily schedule.

To answer this question, researchers including Joseph Takahashi, Ph.D., Chair and Professor of Neuroscience at UT Southwestern Medical Center and an Investigator at the Peter O'Donnell Jr. Brain Institute, examined gene activity in Anopheles salivary glands.

According to their findings, reported in , about half of the mosquitoes' salivary gland genes had rhythmic expression, particularly those important for efficient feeding, such as genes that make anticlotting proteins. The researchers also found that the mosquitoes preferred to feed at night, with the blood volume they ingested varying cyclically throughout the day.

Additionally, genes of the parasites living in Anopheles salivary glands had cyclic differences in activity, especially those involved in parasite transmission. The authors suggest the internal clocks of the parasite, mosquito, and mammalian host play an important role in successful malaria infection.

Study senior author Filipa Rijo-Ferreira, Assistant Professor of Infectious Diseases and Vaccinology at the University of California, Berkeley, is a former postdoctoral researcher in the Takahashi Lab at UTSW.