Effect of temperature stress on the growth, ovary development, antioxidant capacity, sex hormone content, and reproductive-related gene expression of female red swamp crayfish (Procambarus clarkii)

Red swamp crayfish (Procambarus clarkii) is the most extensively farmed freshwater shrimp species in China. However, the underdeveloped factory breeding technology of P. clarkii has significantly constrained the development of this industry. Temperature changes directly affect the metabolism of P. clarkii, thereby influencing its growth and reproduction. The study aimed to investigate the effects of temperature on growth, ovarian development, antioxidant capacity, sex hormone levels, and reproductive gene expression of female P. clarkii, and to investigate the molecular mechanism through which temperature regulation promotes ovarian development. A total of 250 female P. clarkii (average weight of 13.30 ± 0.31 g) were randomly selected and divided into five groups, with five replicates in each group. Temperature stress experiments were conducted at natural temperature (control group), 17℃, 19℃, 21℃, 25℃, and 29℃. Compared with the control group, the maturity and vitellogenin content of female crayfish at 25℃ were significantly improved, and their growth rate was the highest. Compared with the natural temperature group, levels of glutathione peroxidase, superoxide dismutase, and total antioxidant capacity in the hepatopancreas and hemolymph of the 17℃, 21℃, and 29℃ groups were significantly reduced, while the content of malondialdehyde was significantly increased (P < 0.05), while there was no significant difference in the 25℃ group. At 25℃, the levels of estrogen and progesterone in the hemolymph of female P. clarkii were significantly increased, and the expression levels of vitellogenin receptor (vgr), forkheadboxL2 (foxL2), vitellogenin (vg), proliferating cell nuclear antigen (pcna), and cyclin B in hepatopancreas were significantly upregulated (P < 0.05). At 25°C, estrogen simultaneously activated the expression of vg and vgr genes in the hepatopancreas and ovaries, promoting the efficient synthesis and transport of vitellogenin. Additionally, estradiol enhanced the transcription of foxL2 by binding to the binding protein, maintained ovarian differentiation, induced pcna-mediated proliferation of reproductive cells, and activated cyclin B and cell division cycle 2 (cdc2) genes to promote the meiotic division process of oocytes. These findings demonstrate a core mechanism of reproductive enhancement involving gene activation, cell cycle synergy, and oxidative balance, thereby significantly improving the efficiency of ovarian maturation. In conclusion, the 25℃ is the most effective temperature for promoting the growth and ovarian development of female P. clarkii, and its antioxidant capacity remains at a relatively high level at this temperature, which is conducive to reproductive activities. This study provides a theoretical basis for optimizing the temperature control strategy for the reproduction of P. clarkii and cultivating stress-resistant varieties.