Changes in Transcript Abundance in Chlamydomonas reinhardtii following Nitrogen Deprivation Predict Diversion of Metabolism
Changes in Transcript Abundance in Chlamydomonas reinhardtii following Nitrogen Deprivation Predict Diversion of Metabolism
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DOI：
10.1104/pp.110.165159
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发表时间：
2010-12-01
期刊：
影响因子：
7.4
通讯作者：
Benning, Christoph
中科院分区：
文献类型：
--
作者：
Miller, Rachel;Wu, Guangxi;Benning, Christoph
与许多微藻一样，莱茵衣藻在营养缺乏时会形成富含三酰甘油的脂滴。为了开始研究这一过程的机制，我们利用氮 (N) 剥夺来诱导三酰甘油积累和配子发生等发育程序的变化。在诱导和非诱导条件下对转录本进行比较全局分析被用作研究在遇到新营养环境的细胞中促进或伴随三酰甘油积累的分子变化的第一种方法。为了实现这一目标，采用高通量测序技术生成八个生物学独立文库的大量表达序列标签，每个条件四个，N 充足和 N 缺乏，从而可以对两种测试条件下的表达水平进行统计学上的合理比较。正如预期的那样，氮剥夺激活了参与配子发生的控制基因的子集，同时下调了蛋白质生物合成。除 PSBS 基因外，光合作用成分的基因也下调。氮缺乏导致代谢明显改变方向：主要碳源乙酸盐不再通过乙醛酸循环和糖异生转化为细胞构建块，而是直接进入脂肪酸生物合成。膜重塑可能会产生额外的脂肪酸，通过观察到的推定脂肪酶基因转录本丰度的变化表明了这一过程。基于转录分析的代谢推论是间接的，但生化实验支持其中一些推论。这里提供的数据为探索微藻中石油积累的机制提供了丰富的资源。
Like many microalgae, Chlamydomonas reinhardtii forms lipid droplets rich in triacylglycerols when nutrient deprived. To begin studying the mechanisms underlying this process, nitrogen (N) deprivation was used to induce triacylglycerol accumulation and changes in developmental programs such as gametogenesis. Comparative global analysis of transcripts under induced and noninduced conditions was applied as a first approach to studying molecular changes that promote or accompany triacylglycerol accumulation in cells encountering a new nutrient environment. Towards this goal, high-throughput sequencing technology was employed to generate large numbers of expressed sequence tags of eight biologically independent libraries, four for each condition, N replete and N deprived, allowing a statistically sound comparison of expression levels under the two tested conditions. As expected, N deprivation activated a subset of control genes involved in gametogenesis while down-regulating protein biosynthesis. Genes for components of photosynthesis were also down-regulated, with the exception of the PSBS gene. N deprivation led to a marked redirection of metabolism: the primary carbon source, acetate, was no longer converted to cell building blocks by the glyoxylate cycle and gluconeogenesis but funneled directly into fatty acid biosynthesis. Additional fatty acids may be produced by membrane remodeling, a process that is suggested by the changes observed in transcript abundance of putative lipase genes. Inferences on metabolism based on transcriptional analysis are indirect, but biochemical experiments supported some of these deductions. The data provided here represent a rich source for the exploration of the mechanism of oil accumulation in microalgae.