生物如何适应环境的改变是进化生物学的基本问题。陈良标课题组通过对适应极端寒冷环境的南极鱼与温带亲缘鱼之间转录组和基因组的比较揭示了鱼类为适应极端寒冷环境进行的系统性的变化，发现近200个基因所参与的15个生物学过程在寒冷环境下显著高表达，尤以蛋白质折叠和降解、抗过氧化引起的细胞凋亡、卵壳形成、先天免疫、抗冻蛋白和转录系统的增强最为明显。

    以基因芯片为基础的比较基因组杂交表明上述很多基因的高表达是通过大规模的基因扩增实现的，而这可能是鱼类适应永恒低温环境的一个重要和普遍的进化机制。有趣的是，南极稳定的低温环境所导致的低代谢并没有使鱼类基因组中基因的含量降低，相反的是普遍扩增，特别是逆转录系统扩增了近300倍，提示在极端环境下繁衍了千万年的南极鱼类还保持着适应性进化的能力。本研究揭示了低温下鱼类适应性进化的一些基本规律，并有望对不耐寒物种的遗传改良提供基因和借鉴。该成果发表在2008年9月的美国《国家科学院院刊》（PNAS）上。

原始出处：

PNAS，doi: 10.1073/pnas.0802432105，Zuozhou Chen，Liangbiao Chen

Transcriptomic and genomic evolution under constant cold in Antarctic notothenioid fish

Zuozhou Chen*,?, C.-H. Christina Cheng?,?, Junfang Zhang*,?,§, Lixue Cao*,§, Lei Chen*, Longhai Zhou*, Yudong Jin*, Hua Ye*,§, Cheng Deng*,§, Zhonghua Dai*,§, Qianghua Xu*, Peng Hu*,§, Shouhong Sun*, Yu Shen*, and Liangbiao Chen*,?

The antifreeze glycoprotein-fortified Antarctic notothenioid fishes comprise the predominant fish suborder in the isolated frigid Southern Ocean. Their ecological success undoubtedly entailed evolutionary acquisition of a full suite of cold-stable functions besides antifreeze protection. Prior studies of adaptive changes in these teleost fishes generally examined a single genotype or phenotype. We report here the genome-wide investigations of transcriptional and genomic changes associated with Antarctic notothenioid cold adaptation. We sequenced and characterized 33,560 ESTs from four tissues of the Antarctic notothenioid Dissostichus mawsoni and derived 3,114 nonredundant protein gene families and their expression profiles. Through comparative analyses of same-tissue transcriptome profiles of D. mawsoni and temperate/tropical teleost fishes, we identified 177 notothenioid protein families that were expressed many fold over the latter, indicating cold-related up-regulation. These up-regulated gene families operate in protein biosynthesis, protein folding and degradation, lipid metabolism, antioxidation, antiapoptosis, innate immunity, choriongenesis, and others, all of recognizable functional importance in mitigating stresses in freezing temperatures during notothenioid life histories. We further examined the genomic and evolutionary bases for this expressional up-regulation by comparative genomic hybridization of DNA from four pairs of Antarctic and basal non-Antarctic notothenioids to 10,700 D. mawsoni cDNA probes and discovered significant to astounding (3- to >300-fold, P < 0.05) Antarctic-specific duplications of 118 protein-coding genes, many of which correspond to the up-regulated gene families. Results of our integrative tripartite study strongly suggest that evolution under constant cold has resulted in dramatic genomic expansions of specific protein gene families, augmenting gene expression and gene functions contributing to physiological fitness of Antarctic notothenioids in freezing polar conditions.