Transporters associated with intestinal physiology in Tenebrio molitor, Rhodnius prolixus and Dysdercus peruvianus

Abstract

Although there is much work on sugar transporters (Bifano et al., 2010; Price and Gatehouse, 2014), amino acids (Evans et al., 2009; Boudko, 2012), peptides (Roman et al., 1998), lipids (Dourlen et al., 2015), as well as ions (Chintapalli et al., 2015; Xiang et al., 2012) in insects, a comprehensive molecular analysis of intestinal physiology using transporters is at an early stage. A working model has been proposed to explain the counterflux of ectoperitrophic fluid in Tenebrio molitor, based on a transcriptomic approach (Moreira et al., 2017). A more detailed approach was used to describe the mechanism of starch digestion and glucose uptake by Musca domestica larva (Pimentel et al., 2018). More recently, a combination midgut transcriptomics from M. domestica larvae with proteomic analysis of microvillar membranes and in vivo experimentation with inhibitors and dyes led to a physiological model. According to this model, simporters are involved in water fluxes, causing countercurrent fluxes responsible for digestive trypsin recycling, which prevents its excretion (Barroso et al., 2019, submitted for publication). The aim now is to use the technical experience acquired with M. domestica to study in detail the intestinal physiology of T. molitor, including the purification of not only of intestinal microvilli but also of basolateral membranes (with cell fractionation techniques)for proteomic analysis. This will take the understanding of T. molitor intestinal processes to another level.The hematophagous Rhodnius prolixus and the cottonseed sucker Dysdercus peruvianus have intestinal microvillar membranes lined with perimicrovillar membranes like glove fingers. It is speculated that this system arose in the ancestor of these insects for the absorption of amino acids from plant sap poor in these compounds. Perimicrovillar membrane would capture amino acids together with potassium favored by the gradient established between the sap that has high concentration and the space between the perimicrovillar and microvillar membranes that has low concentration of this ion, maintained by the action of a microvillar ion pump (Terra and Ferreira, 2012). The aim is to isolate the perimicrovillar and microvillar membranes with techniques that we already have (Ferreira et al., 1988; Silva et al., 1996) and obtain their proteomes. With these data and our transcriptomes, models of intestinal molecular physiology of these insects can be proposed. (AU)