Anopheles coluzzii stearoyl-CoA desaturase is essential for adult female survival and reproduction upon blood feeding

Abstract

Vitellogenesis and oocyte maturation require anautogenous female Anopheles mosquitoes to obtain a bloodmeal from a vertebrate host. The bloodmeal is rich in proteins that are readily broken down into amino acids in the midgut lumen and absorbed by the midgut epithelial cells where they are converted into lipids and then transported to other tissues including ovaries. The stearoyl-CoA desaturase (SCD) plays a pivotal role in this process by converting saturated (SFAs) to unsaturated (UFAs) fatty acids; the latter being essential for maintaining cell membrane fluidity amongst other housekeeping functions. Here, we report the functional and phenotypic characterization of SCD1 in the malaria vector mosquito Anopheles coluzzii. We show that RNA interference (RNAi) silencing of SCD1 and administration of sterculic acid (SA), a small molecule inhibitor of SCD1, significantly impact on the survival and reproduction of female mosquitoes following blood feeding. Microscopic observations reveal that the mosquito thorax is quickly filled with blood, a phenomenon likely caused by the collapse of midgut epithelial cell membranes, and that epithelial cells are depleted of lipid droplets and oocytes fail to mature. Transcriptional profiling shows that genes involved in protein, lipid and carbohydrate metabolism and immunity-related genes are the most affected by SCD1 knock down (KD) in blood-fed mosquitoes. Metabolic profiling reveals that these mosquitoes exhibit increased amounts of saturated fatty acids and TCA cycle intermediates, highlighting the biochemical framework by which the SCD1 KD phenotype manifests as a result of a detrimental metabolic syndrome. Accumulation of SFAs is also the likely cause of the potent immune response observed in the absence of infection, which resembles an auto-inflammatory condition. These data provide insights into mosquito bloodmeal metabolism and lipid homeostasis and could inform efforts to develop novel interventions against mosquito-borne diseases.

Unveil the sugar diet and associated environmental compounds in the crop of the mosquito Culex pipiens

“…Two amino acids l -tyrosine and l -glutamine have been detected in the crops of mosquitoes fed with Chamelaucium uncinatum , Delphinium elatum and collected from field sample (FS). These amino acids are necessary and critical for the production and maturation of egg chorion in mosquitoes [ 36 ]. l -tyrosine and l -glutamine are also crucial for the synthesis of protein, and l -tyrosine is an intermediary compound for melanin synthesis which is essential for egg melanization and increase the hatching rate [ 37 ].…”

Current Status of Omics Studies Elucidating the Features of Reproductive Biology in Blood-Feeding Insects

“…Stearoyl-CoA desaturase (SCD) plays a critical role in the digestion of the blood meal in female Anopheles mosquitoes [146] (Figure 1; Table 1). It is crucial in the conversion of saturated fatty acids to unsaturated fatty acids, which play an important role in maintaining cell membrane fluidity.…”

“…It is crucial in the conversion of saturated fatty acids to unsaturated fatty acids, which play an important role in maintaining cell membrane fluidity. Metabolic profiling in SCD1 knockdown Anopheles coluzzii mosquitos revealed a depletion of lipid droplets that led to a detrimental effect on oocyte maturation, affecting their reproductivity [146].…”