Abstract

Chlamydomonas reinhardtii P.A. Dangeard is a unicellular green alga capable to assimilate acetate. C. reinhardtii growth and metabolism distinctly depend on trophic conditions. Its influence on batch culture interferes with changes in the medium composition and metabolism of microalgae occurring during culture growth. The aim of this work was to estimate the effect of acetate on changes in the expression of 32 genes encoding enzymes of central metabolism and plastid transporters during growth of batch cultures of C. reinhardtii cc-124. In autotrophic conditions, transcription profiles considerably differed from the profiles in the presence of acetate. The strongest influence of trophic conditions was observed in the log phase of growth. In the presence of acetate, a more intense expression of gene ACS2 encoding plastid acetyl-CoA synthase and of the genes encoding subunits of enzymes directing acetyl groups to the synthesis of fatty acids was recorded. Elevated expression of genes PCK1 and PPT1 under mixotrophic conditions may be corresponded to the entry of acetate carbon to gluconeogenesis. In the presence of acetate, a high expression level of the starch metabolism genes was observed. Autotrophic conditions were notable for an elevated accumulation of transcripts of the genes encoding subunits of citrate lyase, which may be responsible for an outflow of acetyl groups from the Krebs cycle. Moreover, a higher level of expression was shown for genes of plastid transporters participating in the export of sugars from plastids, which is associated with the redistribution of reducing power in the cell. It was concluded that, on the level of transcription, similarity between mixotrophic and autotrophic cultures becomes more pronounced in the course of development.

中文翻译：

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不同营养条​​件下莱茵衣藻主要代谢和叶绿体转运蛋白基因表达的变化

摘要

莱茵衣藻PA Dangeard是一种能够吸收乙酸盐的单细胞绿藻。莱茵衣藻的生长和代谢明显取决于营养条件。它对分批培养的影响会干扰培养生长过程中微藻的培养基组成和代谢变化。这项工作的目的是估计醋酸盐对莱茵衣藻分批培养生长过程中32种编码中央代谢酶和质体转运蛋白的基因表达的影响。CC-124。在自养条件下，转录谱与乙酸盐存在下的谱显着不同。在生长的对数期观察到营养条件的最强影响。在乙酸盐存在下，记录了编码质体乙酰辅酶A合酶的ACS2基因和编码将乙酰基引导至脂肪酸合成的酶的亚基的基因的更强烈表达。基因PCK1和PPT1的表达升高在混合营养条件下，可能对应于乙酸碳进入糖异生。在乙酸盐的存在下，观察到淀粉代谢基因的高表达水平。自养条件是引起柠檬酸裂解酶亚基编码基因转录物积累增加的原因，这可能是乙酰基从克雷布斯循环中流出的原因。此外，显示了参与质体糖输出的质体转运蛋白基因的更高水平的表达，这与细胞中还原能力的重新分布有关。结论是，在转录水平上，混合营养和自养培养物之间的相似性在发育过程中变得更加明显。