近日，中国科学院水生生物研究所关于鱼类低温适应机制研究的论文“Transcriptomic characterization of cold acclimation in larval zebrafish”在BMC genomics在线发表。该论文首次报道了斑马鱼早期幼体具备建立低温耐受的机制。
低温暴露不但影响鱼类的生长和发育，严重时还可导致鱼体死亡。鱼类的低温耐受能力受遗传、热历程和发育阶段等因素的影响。近年来，鱼类低温适应机制逐渐成为研究热点，然而鱼类发育的早期阶段是否具备低温适应能力，以及低温适应过程中的转录和转录后调控机制尚不清楚。
中科院水生所崔宗斌研究员课题组以斑马鱼为模型研究鱼类的低温适应机制。研究发现斑马鱼受精后96h幼体低温（12℃）暴露前先在16℃处理24h可以显著降低死亡率，说明其具备在较低温度条件下形成低温耐受的能力。RNA-seq分析鉴定出1431个低温诱导基因和399个抑制基因。生物信息学分析结果表明，低温诱导表达的基因主要参与RNA剪接、核糖体生物发生、蛋白质分解代谢和RNA转运等生物学过程。由于RNA-seq具有全基因组范围内检测基因表达的技术优势，本研究还鉴定到大量受低温调控的可变剪接和可变启动子使用事件。该论文和本课题组前期研究（PLoS ONE， 2012， 7(5)： e37209）结果为后续深入研究鱼类低温适应过程中的信号传导机制及关键基因功能提供了重要线索。
该研究工作得到国家自然科学基金资助，由龙勇助理研究员等人完成。（生物谷Bioon.com）
生物谷推荐的英文摘要
BMC genomics doi:10.1186/1471-2164-14-612
Transcriptomic characterization of cold acclimation in larval zebrafish
Yong Long1， Guili Song1， Junjun Yan12， Xiaozhen He12， Qing Li1 and Zongbin Cui1
Background
Temperature is one of key environmental parameters that affect the whole life of fishes and an increasing number of studies have been directed towards understanding the mechanisms of cold acclimation in fish. However， the adaptation of larvae to cold stress and the cold-specific transcriptional alterations in fish larvae remain largely unknown. In this study， we characterized the development of cold-tolerance in zebrafish larvae and investigated the transcriptional profiles under cold stress using RNA-seq.
Results
Pre-exposure of 96？hpf zebrafish larvae to cold stress (16°C) for 24 h significantly increased their survival rates under severe cold stress (12°C). RNA-seq generated 272 million raw reads from six sequencing libraries and about 92% of the processed reads were mapped to the reference genome of zebrafish. Differential expression analysis identified 1，431 up- and 399 down-regulated genes. Gene ontology enrichment analysis of cold-induced genes revealed that RNA splicing， ribosome biogenesis and protein catabolic process were the most highly overrepresented biological processes. Spliceosome， proteasome， eukaryotic ribosome biogenesis and RNA transport were the most highly enriched pathways for genes up-regulated by cold stress. Moreover， alternative splicing of 197 genes and promoter switching of 64 genes were found to be regulated by cold stress. A shorter isoform of stk16 that lacks 67 amino acids at the N-terminus was specifically generated by skipping the second exon in cold-treated larvae. Alternative promoter usage was detected for per3 gene under cold stress， which leading to a highly up-regulated transcript encoding a truncated protein lacking the C-terminal domains.
Conclusions
These findings indicate that zebrafish larvae possess the ability to build cold-tolerance under mild low temperature and transcriptional and post-transcriptional regulations are extensively involved in this acclimation process.
