Lipophorin receptor 1 (LpR1) in Drosophila muscle influences life span by regulating mitochondrial aging

Lipophorin receptor knockdown reduces hatchability of kissing bug Rhodnius prolixus eggs

Lipophorin is the primary lipoprotein present in the hemolymph of insects, responsible for the lipids' transport between organs. It interacts with specific sites on cell membranes in an essential process for transferring lipids. The lipophorin receptor is the protein responsible for the interaction between lipophorin and cell membranes. In the kissing bug Rhodnius prolixus, much information on the interaction of lipophorin with organs is available. However, molecular data on the lipophorin receptor and its functions is still needed. Here, we explored lipophorin receptor gene expression and functions using a functional genomics approach. The R. prolixus genome encodes seven genes from the low-density lipoprotein receptor family, including a single ortholog of the lipophorin receptor. All organs analyzed (anterior and posterior midguts, fat body, ovaries, and flight muscle) expressed this gene. In the fat body, blood-feeding strongly reduced lipophorin receptor gene expression. Lipophorin receptor knockdown by RNA interference delayed egg laying and reduced the triacylglycerol in laid eggs without altering lipid stores in the fat body or lipid levels in the hemolymph. In the ovaries, lipophorin receptor knockdown reduces the expression of acetyl-CoA carboxylase and a fatty acid synthase while altered the gene expression profile in the fat body, causing an increase in the expression of carnitine palmitoyltransferase 1 and a reduction in Brummer lipase and vitellogenin 2. RNA interference treatment reduced the hatching of the eggs, causing the collapse and darkening of the laid eggs, in addition to the hatching of deformed first-stage nymphs. Furthermore, the structure of the chorion showed distortions in patterns and cracks and reduced hydrocarbon levels. These results show that the lipophorin receptor alone is not essential for lipid physiology in R. prolixus. However, this protein plays a fundamental role in the viability of eggs and, consequently, in insect reproduction.

The metabolism and role of free fatty acids in key physiological processes in insects of medical, veterinary and forensic importance

Insects are the most widespread group of organisms and more than one million species have been described. These animals have significant ecological functions, for example they are pollinators of many types of plants. However, they also have direct influence on human life in different manners. They have high medical and veterinary significance, stemming from their role as vectors of disease and infection of wounds and necrotic tissue; they are also plant pests, parasitoids and predators whose activities can influence agriculture. In addition, their use in medical treatments, such as maggot therapy of gangrene and wounds, has grown considerably. They also have many uses in forensic science to determine the minimum post-mortem interval and provide valuable information about the movement of the body, cause of the death, drug use, or poisoning. It has also been proposed that they may be used as model organisms to replace mammal systems in research. The present review describes the role of free fatty acids (FFAs) in key physiological processes in insects. By focusing on insects of medical, veterinary significance, we have limited our description of the physiological processes to those most important from the point of view of insect control; the study examines their effects on insect reproduction and resistance to the adverse effects of abiotic (low temperature) and biotic (pathogens) factors.