Perimicrovillar membrane assembly: the fate of phospholipids synthesised by the midgut of Rhodnius prolixus

Paula Rego Bittencourt-Cunha,George Eduardo Gabriel Kluck,Giselle Almeida De Oliveira,Georgia Correa Atella,Carlos Peres Silva,Hatisaburo Masuda,Livia Silva-Cardoso,Mario Alberto Cardoso Da Silva Neto,Marilvia Dansa-Petretsky,Jose Roberto Da Silva,Katia Calp Gondim,Alan Barbosa Da Silveira,Michele Souza-Lima

doi:10.1590/s0074-0276108042013016

Abstract

In this study, we describe the fate of fatty acids that are incorporated from the lumen by the posterior midgut epithelium of Rhodnius prolixus and the biosynthesis of lipids. We also demonstrate that neutral lipids (NL) are transferred to the haemolymphatic lipophorin (Lp) and that phospholipids remain in the tissue in which they are organised into perimicrovillar membranes (PMMs). 3H-palmitic acid added at the luminal side of isolated midguts of R. prolixus females was readily absorbed and was used to synthesise phospholipids (80%) and NL (20%). The highest incorporation of 3H-palmitic acid was on the first day after a blood meal. The amounts of diacylglycerol (DG) and triacylglycerol synthesised by the tissue decreased in the presence of Lp in the incubation medium. The metabolic fates of 3H-lipids synthesised by the posterior midgut were followed and it was observed that DG was the major lipid released to Lp particles. However, the majority of phospholipids were not transferred to Lp, but remained in the tissue. The phospholipids that were synthesised and accumulated in the posterior midgut were found to be associated with Rhodnius luminal contents as structural components of PMMs.

Highlights

The hemipterans differ from other insects because they lack a peritrophic membrane and their midgut cells are coated with an extracellular membrane, the perimicrovillar membrane (PMM) (Terra 1988)
We observed that the capacity of the posterior midgut to absorb fatty acid (FA) from the luminal contents was higher in the first day after feeding (Fig. 2)
We have previously shown that the posterior midgut of R. prolixus is able to take up radioactive FAs from Lp preferentially on the 10th day after a blood meal (Atella et al 1995)

Summary

Introduction

The hemipterans differ from other insects because they lack a peritrophic membrane and their midgut cells are coated with an extracellular membrane, the perimicrovillar membrane (PMM) (Terra 1988). This structure was described and interpreted differently in morphological and enzymological studies performed by several authors (Marshall & Cheung 1970, Reger 1971, Burgos & Gutiérrez 1976, Lane & Harrison 1979, Baerwald & Delcarpio 1983, Billingsley & Downe 1986, Ferreira et al 1988, Silva et al 1996). We demonstrate that NL are transferred to the haemolymphatic Lp and that phospholipids remain in the tissue, where they are organised into PMMs

Methods

Results

Conclusion