Malpighamoebainfection compromises fluid secretion and P-glycoprotein detoxification in Malpighian tubules

Abstract

12Malpighian tubules, analogous to vertebrate nephrons, play a key role in insect 13 osmoregulation and detoxification. Tubules can become infected with a protozoan, 14Malpighamoeba, which damages their epithelial cells, potentially compromising their function. 15Here we quantify the impact of Malpighamoeba infection on fluid secretion and P-glycoprotein-16 dependent detoxification by Malpighian tubules of the desert locust using a modified Ramsay 17 assay. Infected tubules have a greater surface area and a higher fluid secretion rate than 18 uninfected tubules. Infection also impairs P-glycoprotein-dependent detoxification reducing 19 the net extrusion of rhodamine B per unit of surface area. However, infected tubules' increased 20 surface area and fluid secretion rate means they have similar total net extrusion per tubule to 21 uninfected tubules. Increased fluid secretion rate of infected tubules likely subjects locusts to 22 greater water stress and imposes increased energy costs. Coupled with reduced efficiency of 23 P-glycoprotein detoxification, Malpighamoeba infection is likely to reduce insect survival within 24 natural environments. 25