Heat stress affects swimming performance and induces biochemical, structural, and transcriptional changes in the heart of Gymnocypris eckloni

Abstract

Global warming has heightened the severity and frequency of extreme high-temperature events, presenting challenges to fish survival and negatively affecting the production of fishery. Gymnocypris eckloni, native to the Tibetan Plateau, is widely cultured in southwest China. Its sensitivity to heat makes it a suitable model for studying the impact of high temperatures on fish. The heart is a vital organ for survival, while is relatively understudied concerning the impact of high temperatures on fish hearts. In this study, G. eckloni was subjected to a seven-day exposure to 27 °C followed by a transfer to 18 °C for a seven-day recovery period. Behavioral tests revealed a significant increase in locomotor speed, distance, and respiratory rate of G. eckloni at 27 °C. Serum indices exhibited significantly elevated stress indicators (cortisol) and kinases associated with heart damage (lactate dehydrogenase, lactate dehydrogenase isoenzyme 1, creatine kinase, creatine kinase isoenzyme, and aspartate transaminase) at 27 °C, and histological analyses have confirmed the occurrence of heart damage subjected to high temperatures. After 7 days of recovery, most of these indicators showed a significant decrease compared to the heat stress group, with no significant differences observed compared to the control group. Transcriptomic analyses have revealed the widespread involvement of ferroptosis, P53 signaling pathway, oxidative phosphorylation, myocardial contraction, and DNA repair pathway in the response of G. eckloni to high temperatures. Our study offers a systematic exploration of the effects of heat stress on G. eckloni, providing valuable insights for the cultivation of high-altitude fish.

Keywords

• High temperature
• Locomotor behavior
• Heart damage
• Transcriptomic response