Acclimation during Embryogenesis Remodulates Telomerase Activity and Gene Expression in Baikal Whitefish Larvae, Mitigating the Effects of Acute Temperature Stress.

Simple Summary: Temperature acclimation enables animals, especially aquatic ones, to safely survive climate fluctuations in the natural environment. The aim of our work was to study how temperature acclimation in aquaculture affects cold-water Baikal whitefish at the embryonic stage and their well-being during a heat shock (24 °C). Selected molecular markers (telomere length, telomerase activity, and expression of target genes) showed that acclimation at the early developmental stages has a positive effect on the Baikal whitefish larvae and allows them to tolerate acute temperature stress without the harmful consequences. The data obtained will improve the survival of fish and increase their plasticity under aquaculture conditions. Acclimation through the hormesis effect increases the plasticity of organisms, which has been shown for many ectothermic animals, including fish. We investigated the effect of temperature acclimation in Baikal whitefish Coregonus baicalensis (Dybowski, 1874). Telomere length, telomerase activity, and the expression of genes, whose products are involved in the regulation of telomere length and defense against reactive oxygen species, were selected to assess the state of the larvae. Acclimation and acute temperature stress (+12 °C) had no effect on telomere length, but altered telomerase activity (acclimation decreased it; stress increased it) and the levels of genes expression. Under stress, the expression of superoxide dismutase genes was increased in acclimated larvae and that of glutathione peroxidases in non-acclimated larvae, which may indicate lower reactive oxygen species formation and slower antioxidant responses in acclimated fish. The expression of some telomere-related genes was reduced under temperature stress, but the expression of the tzap and smg genes, whose products improve the control of telomere length by preventing them from lengthening or shortening, was increased in acclimated individuals. The data obtained indicate a positive effect of acclimation on the state of the Baikal whitefish larvae by remodulation of their telomerase activity and the transcriptional profile. [ABSTRACT FROM AUTHOR]