Cell signalling mechanisms for insect stress tolerance

Abstract

Insects successfully occupy most environmental niches and this success depends on surviving a broad range of environmental stressors including temperature, desiccation, xenobiotic, osmotic and infection stress. Epithelial tissues play key roles as barriers between the external and internal environments and therefore maintain homeostasis and organismal tolerance to multiple stressors. As such, the crucial role of epithelia in organismal stress tolerance cannot be underestimated. At a molecular level, multiple cell-specific signalling pathways including cyclic cAMP, cyclic cGMP and calcium modulate tissue, and hence, organismal responses to stress. Thus, epithelial cell-specific signal transduction can be usefully studied to determine the molecular mechanisms of organismal stress tolerance in vivo. This review will explore cell signalling modulation of stress tolerance in insects by focusing on cell signalling in a fluid transporting epithelium -the Malpighian tubule. Manipulation of specific genes and signalling pathways in only defined tubule cell types can influence the survival outcome in response to multiple environmental stressors including desiccation, immune, salt (ionic) and oxidative stress, suggesting that studies in the genetic model Drosophila melanogaster may reveal novel pathways required for stress tolerance.

Comparative transcriptomic analysis of larval and adult Malpighian tubules from the cotton bollworm Helicoverpa armigera

“…The present study provided the first transcriptome of H. armigera MTs. Although further functional validation is required, our transcriptomic data lend support to the hypothesis that insect MTs are versatile organs (Davies et al ., ). The results highlight the importance of MTs in carbohydrate metabolism besides diuresis, detoxification and immunity.…”

How micronutrients influence the physiology of mosquitoes

“…Metal homeostasis is critical to many additional physiological and behavioral processes. Calcium signaling and regulation in the Malpighian tubules play essential roles in osmoregulation and ion homeostasis, detoxification and immunity [45,46]. Excess of calcium in the diet or defects in calcium homeostasis results in the formation of calcium oxalate crystals in the Malpighian tubules of flies; establishing insects as good models for studying human kidney diseases [47].…”

Comparative physiology of Malpighian tubules: form and function

“…76 The gene encoding Cytochrome P450-4e3 (Cyp4e3) is upregulated in the principal cells of the MT in Drosophila fed on permethrin. 77 In MT of Drosophila, studies at the molecular level indicated the overexpression of a Cytochrome P450 gene, Cyp6g1, which has been evolved to insecticide resistance.…”