Cold tolerance is linked to osmoregulatory function of the hindgut in Locusta migratoria
Cold tolerance is linked to osmoregulatory function of the hindgut in Locusta migratoria
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DOI：
10.1242/jeb.173930
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发表时间：
2018-03-01
影响因子：
2.8
通讯作者：
Overgaard, Johannes
中科院分区：
文献类型：
--
作者：
Gerber, Lucie;Overgaard, Johannes
越来越多的证据表明，维持离子和水分平衡决定了许多昆虫的耐寒性。陆生昆虫的后肠是维持机体内环境稳定的关键，因为它调节血淋巴的溶质和水平衡。在这里，我们使用离体外翻肠囊的飞蝗检查温度（0-30摄氏度），热适应，缺氧，离子和渗透力对散装水和离子（Na+，K+和Cl-）运动的直肠上皮细胞的影响。这些研究结果与同时在体内测量水和离子平衡蝗虫暴露在类似的温度。正如预测的那样，我们观察到在低温下净水和离子重吸收的临界抑制与体内水和离子稳态的损失成比例。此外，冷驯化蝗虫，这是众所周知的捍卫离子和水分平衡在低温下，其特点是在低温下提高重吸收能力。这些发现有力地支持了低温下后肠的运输机制对耐寒性至关重要的假设。在低温条件下，直肠对异硫氰酸荧光素葡聚糖的调节能力的丧失主要是由于主动转运减少所致，而直肠对异硫氰酸荧光素葡聚糖的细胞旁渗透性在0 ℃和30 ℃下没有变化。在冷暴露，水的重吸收是独立的主要阳离子梯度跨上皮细胞，而减少粘膜Cl-的可用性和粘膜渗透压的增加显着抑制水的重吸收。这些研究结果进行了讨论的背景下，现有的知识和建议，为未来的生理研究昆虫冷驯化和适应。
There is growing evidence that maintenance of ion and water balance determines cold tolerance in many insects. The hindgut of terrestrial insects is critical for maintaining organismal homeostasis as it regulates solute and water balance of the haemolymph. Here, we used ex vivo everted gut sacs of Locusta migratoria to examine the effects of temperature (0-30 degrees C), thermal acclimation, hypoxia, and ionic and osmotic forces on bulk water and ion (Na+, K+ and Cl-) movement across the rectal epithelium. These findings were related to simultaneous in vivo measurements of water and ion balance in locusts exposed to similar temperatures. As predicted, we observed a critical inhibition of net water and ion reabsorption at low temperature that was proportional to the in vivo loss of water and ion homeostasis. Further, cold-acclimated locusts, which are known to defend ion and water balance at low temperature, were characterised by improved reabsorptive capacity at low temperature. These findings strongly support the hypothesis that transport mechanisms in the hindgut at low temperature are essential for cold tolerance. The loss of osmoregulatory capacity at low temperature was primarily caused by reduced active transport, while rectal paracellular permeability to fluorescein isothiocyanate dextran was unchanged at 0 and 30 degrees C. During cold exposure, water reabsorption was independent of major cation gradients across the epithelia, while a reduction in mucosal Cl- availability and an increase in mucosal osmolality markedly depressed water reabsorption. These findings are discussed in the context of existing knowledge and with suggestions for future physiological studies on cold acclimation and adaptation in insects.