Scientists have known that females of many species eat more to meet the demands of reproduction, and that females undergo widespread physiological and behavioral changes after mating. The mechanisms of these changes, however, are not well understood.
A new study of the common fruit fly (Drosophila melanogaster) has identified a protein in the male鈥檚 seminal fluid that triggers the female鈥檚 midgut to expand after mating. This widening and lengthening of the gut likely prepares the female for eating more to meet the increased energy and nutrient demands required for reproduction.
The study, 鈥,鈥 was published Dec. 21 in Proceedings of the National Academy of 麻豆视频.
鈥淲e show that this male protein is what causes the female鈥檚 gut to grow,鈥 said , professor of molecular biology and genetics and a Stephen H. Weiss Presidential Fellow in the 麻豆视频 and 麻豆视频. Melissa White, a graduate student in Wolfner鈥檚 lab, is the paper鈥檚 first author.
By identifying this seminal protein 鈥 called the sex peptide 鈥 in Drosophila and learning how it works, the researchers opened the door for identifying similar proteins and possibly manipulating them to decrease populations of harmful insects, such as disease-carrying mosquitoes, or to enhance reproduction in bees and other beneficial insects. The findings may also provide insights into studying the roles of seminal proteins and analogous systems in mammals, including humans.
In the study, White led a variety of experiments. She mated normal females and males, and mated normal females with mutant males that were engineered to not produce the sex peptide. By measuring the midguts of the females from these experiments, White discovered that the female鈥檚 gut only grew if she received the sex peptide from her mate. White then confirmed the necessity of the sex peptide for gut growth by showing that female flies that lacked a receptor known to bind the sex peptide failed to grow their guts after mating, and that females engineered to make the sex peptide themselves grew large guts without the need to mate.
鈥淢elissa鈥檚 work showed that the growth in length and width of the gut was dependent on the receipt and retention of this seminal protein,鈥 Wolfner said.
Study co-author Alessandro Bonfini, a postdoctoral researcher in the lab of co-senior author , associate professor of entomology in the College of Agriculture and Life 麻豆视频, identified a change in the gene expression in the female鈥檚 gut after mating; the gut increased expression of enzymes needed to digest protein and decreased expression of enzymes required to digest carbohydrate.
The researchers showed that if the female doesn鈥檛 get the sex peptide, those changes in gene expression don鈥檛 occur.
鈥淭hat鈥檚 consistent with females needing and using more protein after they鈥檝e mated,鈥 Wolfner said, a finding previously reported by researchers at other universities, but not previously shown to be dependent on receipt of a protein from males.
鈥淯pon mating, females of many species undergo a number of physiological transformations that allow them to adjust to an increased demand in specific nutrients,鈥 Buchon said. 鈥淥ur work demonstrates that some of these changes involves increasing the size of the digestive tract and altering its digestive function.鈥
The study was funded by the National Institutes of Health and the National Science Foundation.
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