Dietary potassium and cold acclimation additively increase cold tolerance in Drosophila melanogaster

IF 2.3 2区 农林科学 Q1 ENTOMOLOGY
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Abstract

In the cold, chill susceptible insects lose the ability to regulate ionic and osmotic gradients. This leads to hemolymph hyperkalemia that drives a debilitating loss of cell membrane polarization, triggering cell death pathways and causing organismal injury. Biotic and abiotic factors can modulate insect cold tolerance by impacting the ability to mitigate or prevent this cascade of events. In the present study, we test the combined and isolated effects of dietary manipulations and thermal acclimation on cold tolerance in fruit flies. Specifically, we acclimated adult Drosophila melanogaster to 15 or 25 °C and fed them either a K+-loaded diet or a control diet. We then tested the ability of these flies to recover from and survive a cold exposure, as well as their capacity to protect transmembrane K+ gradients, and intracellular Na+ concentration. As predicted, cold-exposed flies experienced hemolymph hyperkalemia and cold-acclimated flies had improved cold tolerance due to an improved maintenance of the hemolymph K+ concentration at low temperature. Feeding on a high-K+ diet improved cold tolerance additively, but paradoxically reduced the ability to maintain extracellular K+ concentrations. Cold-acclimation and K+-feeding additively increased the intracellular K+ concentration, aiding in maintenance of the transmembrane K+ gradient during cold exposure despite cold-induced hemolymph hyperkalemia. There was no effect of acclimation or diet on intracellular Na+ concentration. These findings suggest intracellular K+ loading and reduced muscle membrane K+ sensitivity as mechanisms through which cold-acclimated and K+-fed flies are able to tolerate hemolymph hyperkalemia.

Abstract Image

膳食钾和低温驯化可增加黑腹果蝇的耐寒能力
在寒冷环境中,易受寒冷影响的昆虫会失去调节离子和渗透梯度的能力。这导致血淋巴高钾血症,使细胞膜极化丧失,引发细胞死亡途径,造成生物体损伤。生物和非生物因素可通过影响减轻或防止这一系列事件的能力来调节昆虫的耐寒性。在本研究中,我们测试了饮食控制和热驯化对果蝇耐寒性的综合和单独影响。具体来说,我们将黑腹果蝇成虫驯化至 15 或 25 °C,并喂食含有 K+ 的食物或对照食物。然后,我们测试了这些果蝇从寒冷暴露中恢复和存活的能力,以及它们保护跨膜K+梯度和细胞内Na+浓度的能力。正如预测的那样,暴露于低温的蝇类会出现血淋巴高钾血症,而适应低温的蝇类由于在低温下能更好地维持血淋巴中的K+浓度,因此耐寒能力有所提高。饲喂高K+食物可额外提高耐寒性,但却降低了维持细胞外K+浓度的能力。尽管低温会引起血淋巴高钾血症,但低温适应和饲喂高K+食物会增加细胞内的K+浓度,有助于在低温暴露期间维持跨膜K+梯度。适应或饮食对细胞内 Na+ 浓度没有影响。这些发现表明,细胞内K+负荷和肌膜K+敏感性降低是冷驯化和K+喂养的苍蝇能够耐受血淋巴高钾血症的机制。
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来源期刊
Journal of insect physiology
Journal of insect physiology 生物-昆虫学
CiteScore
4.50
自引率
4.50%
发文量
77
审稿时长
57 days
期刊介绍: All aspects of insect physiology are published in this journal which will also accept papers on the physiology of other arthropods, if the referees consider the work to be of general interest. The coverage includes endocrinology (in relation to moulting, reproduction and metabolism), pheromones, neurobiology (cellular, integrative and developmental), physiological pharmacology, nutrition (food selection, digestion and absorption), homeostasis, excretion, reproduction and behaviour. Papers covering functional genomics and molecular approaches to physiological problems will also be included. Communications on structure and applied entomology can be published if the subject matter has an explicit bearing on the physiology of arthropods. Review articles and novel method papers are also welcomed.
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