科研动态 Research Highlight

通过转录组学与小RNA组学分析揭示甲藻应对磷酸盐胁迫的多层次调控机制
Transcriptomic and microRNAomic profiling reveals multi-faceted mechanisms to cope with phosphate stress in a dinoflagellate
发布日期:2017-6-9      浏览次数:1413

通过转录组学与小RNA组学分析揭示甲藻应对磷酸盐胁迫的多层次调控机制

Transcriptomic and microRNAomic profiling reveals multi-faceted mechanisms to cope with phosphate stress in a dinoflagellate

原甲藻是广分布的典型甲藻代表,而东海原甲藻在我国近海海域广泛存在,是赤潮主导物种,每年都爆发大规模赤潮,对我国海洋生态系统影响大,且易于室内培养、同步化效率高(室内培养和现场分别可达75%60%以上),非常适合研究赤潮甲藻对环境因子的分子响应机制。

 

 显微镜下的东海原甲藻

多年的海洋生态调查结果显示,东海原甲藻往往在磷胁迫条件下获取生态位优势从而形成赤潮。我实验室林森杰教授团队以东海原甲藻为例,首次综合利用生理学、转录组学、转录后调控、蛋白质印迹杂交、荧光定量PCR、以及高效液相质谱(HPLC-MS)等研究方法,探讨该甲藻在磷胁迫条件下转录水平、转录后水平以及代谢水平上的应答机制,有效地推进了东海原甲藻成为甲藻研究模式种的进程。

在低磷条件下,东海原甲藻对磷胁迫产生一系列的生理学响应,细胞快速进入平台期、细胞增大、光合效率降低、单细胞RNA含量降低、细胞周期停滞在G1期。研究团队通过转录组数据分析发现,在磷限制条件下1657 个基因 (0.86%) 表达量出现显著差异,其中包括596个基因上调,1061个基因下调。被调控的基因通路包括无机氮的吸收代谢、有机磷的同化、糖酵解途径以及ATP分解及合成等。控制细胞分裂的重要基因G1/S细胞周期蛋白在磷胁迫条件下显著下调。鉴于甲藻的基因表达存在大量转录后调控的情况,研究人员又对磷限制条件下东海原甲藻的microRNA进行了测序,来探讨磷胁迫条件下转录后调控的响应。共发现17microRNA,它们的靶蛋白标定109个和磷应用相关的基因,其功能主要是利用有机磷以及磷酸基团的转运等。这17miRNA中有12个表达差异显著,这些miRNA靶向3,268个蛋白。对这些蛋白进行富集分析发现富集度最高的通路是硫脂水解酶基因,这最终导致硫脂(sulfatide)在单细胞中的积累。为了验证转录后调控分析所获得的这一结果,团队对磷限制条件下的单细胞硫脂进行了高效液相质谱(HPLC-MS)分析,发现单细胞硫脂显著增加。结合以往的研究结果,研究人员认为在磷限制条件下东海原甲藻可以用硫脂(sulfatide)代替磷脂以节约利用磷,从而在海区磷限制的条件下获取竞争优势并爆发形成赤潮。

 

磷酸盐胁迫条件下东海原甲藻代谢通路图

该研究成果于20175月发表于环境生态学领域顶级期刊 ISME Journal 上(2015年影响因子9.328)。论文第一作者是MEL杰出博士后基金获得者石新国,通讯作者为 “千人计划特聘教授林森杰。

Abstract: Although gene regulation can occur at both transcriptional and epigenetic (microRNA) levels, combined transcriptomic and microRNAomic responses to environmental stress are still largely unexplored for marine plankton. Here, we conducted transcriptome and microRNAome sequencing for Prorocentrum donghaiense to understand the molecular mechanisms by which this dinoflagellate copes with phosphorus (P) deficiency. Under P-depleted conditions, G1/S specific cyclin gene was markedly downregulated, consistent with growth inhibition, and genes related to dissolved organic phosphorus (DOP) hydrolysis, carbon fixation, nitrate assimilation, glycolysis, and cellular motility were upregulated. The elevated expression of ATP-generating genes (for example, rhodopsin) and ATP-consuming genes suggests some metabolic reconfiguration towards accelerated ATP recycling under P deficiency. MicroRNAome sequencing revealed 17 microRNAs, potentially regulating 3268 protein-coding genes. Functional enrichment analysis of these microRNA-targeted genes predicted decreases in sulfatide (sulfolipid) catabolism under P deficiency. Strikingly, we detected a significant increase in sulfolipid sulfatide content (but not in sulphoquinovosyldiacylglycerol content) and its biosynthesis gene expression, indicating a different sulfolipid-substituting-phospholipid mechanism in this dinoflagellate than other phytoplankters studied previously. Taken together, our integrative transcriptomic and microRNAomic analyses show that enhanced DOP utilization, accelerated ATP cycling and repressed sulfolipid degradation constitute a comprehensive strategy to cope with P deficiency in a model dinoflagellate.

Citation: Shi X, Lin X, Li L, Li M, Palenik B, Lin S (2017). Transcriptomic and microRNAomic profiling reveals multi-faceted mechanisms to cope with phosphate stress in a dinoflagellate. The ISME Journal. doi:10.1038/ismej.2017.81

论文链接:http://www.nature.com/ismej/journal/vaop/ncurrent/full/ismej201781a.html