雪衣藻Chlamydomonas nivalis适应温度周期性变化的生理响应和分子机制

Physiological responses of Chlamydomonas nivalis to cyclic temperature fluctuation and the adaptation mechanism

摘要:

【目的】雪衣藻（Chlamydomonas nivalis）分布于高山积雪和两极地区，可耐受低温胁迫和温度骤变，其适应温度变化的分子机制目前尚不清楚。【方法】本研究基于温度周期性变化下雪衣藻生理指标的响应规律，选择10个取样点进行转录组测序。运用加权基因共表达网络分析（weighted gene co-expression network analysis，WGCNA）划分得到17个共表达模块，从中找到5个与样品处理显著关联的模块，并对温度骤变的时间点进行基因差异表达分析。最后对筛选得到的基因集进行功能注释分析。【结果】转录组学分析显示，C. nivalis在温度周期变化下基因表达量发生了全局变化，其中果糖和甘露糖代谢通路、淀粉和蔗糖代谢通路、谷胱甘肽代谢通路以及抗坏血酸和醛酸代谢通路中关键酶的编码基因在低温下上调表达。研究还发现在温度周期变化下，C. nivalis中蛋白质质量控制系统、光合作用系统、DNA修复系统相关基因响应温度变化。【结论】本研究为揭示雪衣藻适应温度胁迫的分子机制提供了重要线索，丰富了生物抗逆基因资源库。

Abstract:

[Objective] Chlamydomonas nivalis thrives in polar regions and snowfields of high mountains. C. nivalis is characterized by tolerance to cold and drastic temperature fluctuation. However, the mechanism underlying this tolerance is unknown.[Methods] On the basis of physiological responses of C. nivalis to cyclic temperature fluctuation, we selected 10 sampling times for RNA sequencing. The weighted gene co-expression network analysis (WGCNA) yielded 17 modules, and we picked up 5 modules that were significantly associated with the sample treatment. Then we analyzed the differentially expressed genes under cyclic temperature fluctuation. The selected gene sets were analyzed by functional annotation. [Results] The gene expression on C. nivalis remarkably changed under cyclic temperature fluctuation. Genes coding key enzymes in fructose and mannose metabolism, starch and sucrose metabolism, glutathione metabolism, ascorbate and aldehyde acid metabolism pathways were up-regulated at 4℃. We also found that protein quality control system, photosynthesis system, DNA damage and repair system may play important roles in adaptation to temperature fluctuation. [Conclusion] This study provides important clues to unravel the molecular mechanism of C. nivalis in adaptation to temperature stress and enriches stress-resistant gene resources.