The genomic basis for colonizing the freezing Southern Ocean revealed by Antarctic toothfish and Patagonian robalo genomes

作者：Liangbiao Chen, Ying Lü, Wenhao Li, Yandong Ren, Mengchao Yu, Shouwen Jiang, Yanxia Fu, Jian Wang, Sihua Peng, Kevin T. Bilyk, Katherine R. Murphy, Xuan Zhuang, Mathias Hüne, Wanying Zhai, Wen Wang, Qianghua Xu, Chi-Hing C. Cheng · 发表于：GigaScience · 年份：2019 · DOI：10.1093/gigascience/giz016 · 被引用次数：64 · 研究领域：Physiological and biochemical adaptations、Marine Invertebrate Physiology and Ecology、Ichthyology and Marine Biology

BACKGROUND: The Southern Ocean is the coldest ocean on Earth but a hot spot of evolution. The bottom-dwelling Eocene ancestor of Antarctic notothenioid fishes survived polar marine glaciation and underwent adaptive radiation, forming >120 species that fill all water column niches today. Genome-wide changes enabling physiological adaptations and the rapid expansion of the Antarctic notothenioids remain poorly understood. RESULTS: We sequenced and compared 2 notothenioid genomes-the cold-adapted and neutrally buoyant Antarctic toothfish Dissostichus mawsoni and the basal Patagonian robalo Eleginops maclovinus, representing the temperate ancestor. We detected >200 protein gene families that had expanded and thousands of genes that had evolved faster in the toothfish, with diverse cold-relevant functions including stress response, lipid metabolism, protein homeostasis, and freeze resistance. Besides antifreeze glycoprotein, an eggshell protein had functionally diversified to aid in cellular freezing resistance. Genomic and transcriptomic comparisons revealed proliferation of selcys-transfer RNA genes and broad transcriptional upregulation across anti-oxidative selenoproteins, signifying their prominent role in mitigating oxidative stress in the oxygen-rich Southern Ocean. We found expansion of transposable elements, temporally correlated to Antarctic notothenioid diversification. Additionally, the toothfish exhibited remarkable shifts in genetic programs towards enhanced fat cell...