生物如何適應環(huán)境的改變是進化生物學的基本問題,。陳良標課題組通過對適應極端寒冷環(huán)境的南極魚與溫帶親緣魚之間轉(zhuǎn)錄組和基因組的比較揭示了魚類為適應極端寒冷環(huán)境進行的系統(tǒng)性的變化,，發(fā)現(xiàn)近200個基因所參與的15個生物學過程在寒冷環(huán)境下顯著高表達,，尤以蛋白質(zhì)折疊和降解,、抗過氧化引起的細胞凋亡、卵殼形成,、先天免疫,、抗凍蛋白和轉(zhuǎn)錄系統(tǒng)的增強最為明顯。
以基因芯片為基礎的比較基因組雜交表明上述很多基因的高表達是通過大規(guī)模的基因擴增實現(xiàn)的,，而這可能是魚類適應永恒低溫環(huán)境的一個重要和普遍的進化機制,。有趣的是，南極穩(wěn)定的低溫環(huán)境所導致的低代謝并沒有使魚類基因組中基因的含量降低,，相反的是普遍擴增,，特別是逆轉(zhuǎn)錄系統(tǒng)擴增了近300倍，提示在極端環(huán)境下繁衍了千萬年的南極魚類還保持著適應性進化的能力,。本研究揭示了低溫下魚類適應性進化的一些基本規(guī)律,，并有望對不耐寒物種的遺傳改良提供基因和借鑒。該成果發(fā)表在2008年9月的美國《國家科學院院刊》（PNAS）上,。（生物谷Bioon.com）
生物谷推薦原始出處：
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.
