Department of Integrative Biology, University of Guelph, 50 Stone Road East, Guelph, ON N1G 2W1, Canada.
J Exp Biol. 2023 Aug 15;226(16). doi: 10.1242/jeb.245583. Epub 2023 Aug 21.
Predicted climate change-induced increases in heat waves and hypoxic events will have profound effects on fishes, yet the capacity of parents to alter offspring phenotype via non-genetic inheritance and buffer against these combined stressors is not clear. This study tested how prolonged adult zebrafish exposure to combined diel cycles of thermal stress and hypoxia affect offspring early survival and development, parental investment of cortisol and heat shock proteins (HSPs), larval offspring stress responses, and both parental and offspring heat and hypoxia tolerance. Parental exposure to the combined stressor did not affect fecundity, but increased mortality, produced smaller embryos and delayed hatching. The combined treatment also reduced maternal deposition of cortisol and increased embryo hsf1, hsp70a, HSP70, hsp90aa and HSP90 levels. In larvae, basal cortisol levels did not differ between treatments, but acute exposure to combined heat stress and hypoxia increased cortisol levels in control larvae with no effect on larvae from exposed parents. In contrast, whereas larval basal hsf1, hsp70a and hsp90aa levels differed between parental treatments, the combined acute stressor elicited similar transcriptional responses across treatments. Moreover, the combined acute stressor only induced a marked increase in HSP47 levels in the larvae derived from exposed parents. Finally, combined hypoxia and elevated temperatures increased both thermal and hypoxia tolerance in adults and conferred an increase in offspring thermal but not hypoxia tolerance. These results demonstrate that intergenerational acclimation to combined thermal stress and hypoxia elicit complex carryover effects on stress responsiveness and offspring tolerance with potential consequences for resilience.
预测气候变化引起的热浪和缺氧事件增加将对鱼类产生深远影响，但父母通过非遗传继承改变后代表型并缓冲这些综合胁迫的能力尚不清楚。本研究测试了延长成年斑马鱼暴露于昼夜热应激和缺氧的综合循环中如何影响后代的早期存活和发育、父母对皮质醇和热休克蛋白 (HSPs) 的投资、幼虫后代的应激反应以及父母和后代的耐热性和耐缺氧性。父母暴露于综合胁迫源不会影响繁殖力，但会增加死亡率，产生更小的胚胎并延迟孵化。联合处理还降低了母体皮质醇的沉积，并增加了胚胎 hsf1、hsp70a、HSP70、hsp90aa 和 HSP90 的水平。在幼虫中，基础皮质醇水平在处理之间没有差异，但急性暴露于综合热应激和缺氧会增加对照幼虫中的皮质醇水平，而对暴露于父母的幼虫没有影响。相比之下，虽然幼虫的基础 hsf1、hsp70a 和 hsp90aa 水平在父母处理之间存在差异，但联合急性胁迫源在处理之间引起了相似的转录反应。此外，联合急性胁迫源仅在暴露于父母的幼虫中诱导 HSP47 水平的显著增加。最后，缺氧和升高的温度联合增加了成年鱼的耐热性和耐缺氧性，并赋予了后代耐热性但不是耐缺氧性的增加。这些结果表明，对综合热应激和缺氧的代际适应会对应激反应和后代耐受性产生复杂的遗传效应，从而对恢复力产生潜在影响。
