期刊
COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY A-MOLECULAR & INTEGRATIVE PHYSIOLOGY
卷 216, 期 -, 页码 28-33出版社
ELSEVIER SCIENCE INC
DOI: 10.1016/j.cbpa.2017.11.005
关键词
Insect; Gryllus; Malpighian tubules; Rectum; Sodium pump; Proton pump; Ion homeostasis; Phenotypic plasticity
资金
- Natural Sciences and Engineering Research Council of Canada (NSERC) via Canada Graduate Scholarships
- NSERC Discovery Grants
- York University through a Vernon Stong Scholarship
Cold-acclimated insects defend ion and water transport function during cold exposure. We hypothesized that this is achieved via enhanced active transport. The Malpighian tubules and rectum are likely targets for such transport modifications, and recent transcriptomic studies indicate shifts in Na+-K+ ATPase (NKA) and V-ATPase expression in these tissues following cold acclimation. Here we quantify the effect of cold acclimation (one week at 12 degrees C) on active transport in the ionoregulatory organs of adult Gryllus pennsylvanicus field crickets. We compared primary urine production of warm- and cold-acclimated crickets in excised Malpighian tubules via Ramsay assay at a range of temperatures between 4 and 25 degrees C. We then compared NKA and V-ATPase activities in Malpighian tubule and rectal homogenates from warm- and cold-acclimated crickets via NADH-linked photometric assays. Malpighian tubules of cold-acclimated crickets excreted fluid at lower rates at all temperatures compared to warm-acclimated crickets. This reduction in Malpighian tubule excretion rates may be attributed to increased NKA activity that we observed for cold-acclimated crickets, but V-ATPase activity was unchanged. Cold acclimation had no effect on rectal NKA activity at either 21 degrees C or 6 degrees C, and did not modify rectal V-ATPase activity. Our results suggest that an overall reduction, rather than enhancement of active transport in the Malpighian tubules allows crickets to maintain hemolymph water balance during cold exposure, and increased Malpighian tubule NKA activity may help to defend and/or re-establish ion homeostasis.
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