Stress, immune and growth responses of bluegill sunfish (Lepomis macrochirus) to different environmental temperatures as referred by related gene expression

Abstract

Hiam Elabd, Vikas Kumar, Nour Eissa, Zhi-Gang Shen, Hong Yao, Adel Shaheen, Amany Abbass, Han-Ping Wang

Global temperature climate changes affect stress, immune function and growth of aquatic animals. The aim of this study was to investigate the effect of different temperatures on oxidative stress, thermal stress, immune response and growth in bluegill sunfish (Lepomis macrochirus). The experiment included four groups that were exposed to different water temperatures: 10ºC (10.2 ± 0.05), 20ºC (20 ± 0.06), 30ºC (29.7 ± 0.09), and 35ºC (34.7 ± 0.05) for six weeks. Fish were sampled at day 0, 3 weeks, and 6 weeks. Significantly higher (P < 0.05) erythrocyte lysate superoxide dismutase (SOD) wasobserved in the 10ºC, 30ºC and 35ºC groups at day 0 and 3 week, but more pronounced at the 6th week. Heat Shock protein90 (HSP-90) was significantly up-regulated at higher temperatures (20, 30, and 35ºC), while downregulated at 10ºC. Similarly, immune response biomarker α-2-macroglobulin (A2M) was also upregulated in 20 and 30ºC groups whereas down-regulated in 10ºC group. All groups exhibited 100% survival except the 35ºC group (86% survival). The highest growth performance was observed for the 30ºC group and the lowest for the 10ºC group. Conclusively, findings support that SOD, HSP-90 and A2M could be considered as biomarkers for climate change and environmental monitoring as referred in fish species.