University of Guilan Caspian Journal of Environmental Sciences 1735-3033 21 5 2023 12 01 Antioxidant defenses during early developmental stages in tetraploid rainbow trout, Oncorhynchus mykiss 1005 1016 7255 10.22124/cjes.2023.7255 EN Hajar Sadat Tabatabaei Pozveh Department of Natural Resources, Isfahan University of Technology, Isfahan, 84156-83111, Iran Salar Dorafshan Department of Natural Resources, Isfahan University of Technology, Isfahan, 84156-83111, Iran Fatemeh Paykan Heyrati Department of Natural Resources, Isfahan University of Technology, Isfahan, 84156-83111, Iran Majid Talebi Department of Biotechnology, College of Agriculture, Isfahan University of Technology, Isfahan, 84156-83111, Iran Tillmann J. Benfey Department of Biology, University of New Brunswick, Fredericton, New Brunswick, E3B 6E1, Canada Journal Article 2023 11 18 Antioxidant defense status was examined during early developmental stages of rainbow trout, <em>Oncorhynchus mykiss</em>, as affected by heat shock (HS) treatment to induce tetraploidy. Samples were collected at 3850 degree-min post-fertilization at 10 °C and at eyed, hatch, swim-up, in addition to fry stages to determine the activity of catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), and levels of vitamin C, A and E as well as malondialdehyde (MDA). HS treatment caused a significant reduction in survival, but not affected growth compared to the control. CAT and SOD activities peaked at hatch, whereas GPx activity reached a maximum at the swim-up stage, showing similar patterns, however, significantly higher activities in the HS group. Vitamin levels were at their minimum at the hatch in both groups, while significantly lower in the HS groups. Vitamin levels were at their highest at the fry stage, with the exception of low vitamin E in the HS group. The levels of MDA showed a steady increase during development, with consistently higher levels in the HS group. These results suggest that HS treatment and/or tetraploidy status cause high oxidative stress, as evidenced by higher activity of antioxidant enzymes and MDA levels, and lower levels of vitamins. https://cjes.guilan.ac.ir/article_7255_f759e4afc5b7b6056321155aa05194c8.pdf