Too much of a good thing: how insects cope with excess ions or toxins in the diet

Abstract

SummaryMuch of our understanding of the ionoregulatory and excretory physiology of blood-feeding insects can be traced to a series of papers by Simon Maddrell and colleagues in the 1970s and 1980s. These studies of the Malpighian (renal) tubules of Rhodnius prolixus revealed a number of physiological adaptations to the short-term and long-term stresses associated with blood feeding. More recent electrophysiological studies using voltage-and ion-selective microelectrodes have extended our understanding of the mechanisms and control of ion transport by the secretory and reabsorptive segments of the Rhodnius Malpighian tubule. The discovery that the rates of transport of organic anions, urates and Ca 2+ are synchronized to coincide with the appearance of the products of blood meal digestion in the haemolymph of Rhodnius has stimulated parallel studies in Drosophila. This recent research has examined how excretory mechanisms for organic cations and organic anions are altered by exposure to such compounds in the diet. These studies also show that the Drosophila Malpighian tubule provides a useful model for analysis of the roles of transporters such as P-glycoproteins and multidrug resistance-associated proteins in the excretion of toxins.

Discovery and Characterization of a Potent and Selective Inhibitor of Aedes aegypti Inward Rectifier Potassium Channels

“…Overall, these findings highlight efficient xenobiotic transport mechanisms in mosquitoes that render a nanomolar inhibitor of Ae Kir1 (VU625) ineffective in vivo, even when introduced directly to the hemolymph. The tissues that contribute to the excretion of VU625 remain to be determined, but presumably involve the Malpighian tubules and/or gut [32], [33].…”

Reestablishment of ion homeostasis during chill-coma recovery in the cricketGryllus pennsylvanicus

“…If the hindgut of G. pennsylvanicus has similar capacity, most of the water moved back to the hemolymph during chill-coma recovery could be transported through the hindgut. There is, however, variation in the mechanisms regulating ion and water homeostasis among insect species, especially related to the rich variety of diets (34), which may affect the exact nature of ionoregulation during CCR across the insect phylogeny.…”

AedesCAPA-PVK-1 displays diuretic and dose dependent antidiuretic potential in the larval mosquito Aedes aegypti (Liverpool)

“…Malpighian tubules and the hind-gut, together have the physiological functionality analogous to vertebrate renal systems (Beyenbach, 2003;Maddrell, 1971;Ramsay, 1951); however, this is achieved without glomerular filtration Beyenbach, 1983, 1984;. As would be expected, MTs along with the rectum are involved in tasks similar to most renal systems: osmoregulation, excretion of nitrogenous wastes as well as xenobiotics and immunity (Beyenbach et al, 2010;Dow and Davies, 2006;O'Donnell, 2009). The MTs are regulated by a number of endocrine factors that are either diuretic or anti-diuretic (see Coast, 2007 for review).…”