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1.D.207.  The Freeze Tolerance System in Aquatic Ectothermic Vertebrates (FTS-AEV) Family 

Freeze tolerance, the ability of an organism to survive internal ice formation, is a survival strategy employed by some ectotherms living in cold environments. The Amur sleeper (Perccottus glenii), the only known freeze-tolerant fish species, can overwinter with its entire body frozen in ice. Jiang et al. 2023 sequenced the chromosome-level genome of the Amur sleeper and performed comparative genomic, transcriptomic, and metabolomic analyses to investigate its strategies for surviving freezing. Evolutionary analysis suggested that the Amur sleeper diverged from its closest non-cold-hardy relative about 15 million years ago and has experienced a high rate of protein evolution. Transcriptomic and metabolomic data identified a coordinated and tissue-specific regulation of genes and metabolites involved in hypometabolism, cellular stress response, and cryoprotectant accumulation involved in freezing and thawing. Several genes showing evidence of accelerated protein sequence evolution or family size expansion were found as adaptive responses to freezing induced stresses. Specifically, genetic changes associated with cytoskeleton stability, cryoprotectant synthesis, transmembrane transport and neuroprotective adaptations were identified as potentially key innovations that aid in freezing survival. These observations unveil molecular adaptations supporting freeze tolerance in ectothermic vertebrates (Jiang et al. 2023).

References associated with 1.D.207 family:

Jiang, H., W. Lv, Y. Wang, Y. Qian, C. Wang, N. Sun, C. Fang, D.M. Irwin, X. Gan, S. He, and L. Yang. (2023). Multi-omics investigation of freeze tolerance in the Amur sleeper, an aquatic ectothermic vertebrate. Mol Biol Evol. [Epub: Ahead of Print] 36805964