Mating regulates growth, metabolism, and digestive efficiency in the female Drosophila midgut

Adaptive changes in organ size and function occur in most animals, but how these changes are regulated is not well understood. Previous research found that mating in Drosophila females promotes intestinal stem cell proliferation and increases the overall size of the endodermal portion of the intestine (the “midgut”). Other studies reported mating-dependent changes in feeding behavior, midgut gene expression, and whole-body lipid storage, suggesting altered metabolism. Here, we show that mating dramatically alters female midgut metabolism and digestive function. Mating increased relative levels of TCA cycle intermediates, fatty acids, and ceramides in the gut, increased total midgut lipids and protein, and reduced relative carbohydrate levels. Mating also enhanced the efficiency of protein digestion relative to carbohydrate digestion. Corroborating a previous report, we found that the expression of genes that mediate protein and carbohydrate and metabolism was similarly altered. In addition, we noted a mating-dependent downregulation of oxidative stress response and autophagy genes. Mating-dependent increases in ecdysone receptor (EcR) signaling were important for increasing TCA cycle intermediates, protein, and ceramides in the female midgut, but had minimal effects on bulk lipid accumulation. Overall, this study contributes to our understanding of the physiological changes that occur during adaptive intestinal growth, and how they are regulated. Overall design: We first compared the gene expression in mated and unmated flies whole gut (19464X1-8) and gut progenitor cells (19966X1-8) after 48 hours mating. Then, to investigate how ecdysone signaling pathway affects mating-induced changes, we compared mated and unmated flies, each expressing or not expressing EcR-RNAi. We aged the collected virgin flies for 5 days at 29°C to express EcR-RNAi under the control of ubiquitous (Actin-Gal4) (22551X1-16) or EC-specific (Myo1A-Gal4) (24047X1-2, X4-16) drivers. After 5 days of RNAi expression, we set the mating for 48 hours (25°C) by adding males. We then dissected the guts after 48 hours of mating for sample preparation. For mating experiment; mated female flies were cultured with equal number of males, whereas unmated were isolated apart from males from eclosion. For this experiment, we used 4 replicates per condition/ 15 guts, exept for RNAseq of FACS-sorted progenitor cells that we used 100-150 guts/sample. Mated and unmated flies were age- and genotype-matched. We then performed gene expression profiling analysis using data obtained from RNAseq of mated and unmated flies gut after 48 hours mating.