基于转录组的假微型海链藻硫代谢相关途径分析

Transcriptome-Based Analysis of Sulfur Metabolism-Related Pathways in Thalassiosira pseudonana

为分析近海广布藻华原因种应对广盐环境的细胞关键生命代谢活动过程的调控策略,本研究对不同盐度以及不同处理时间的假微型海链藻(Thalassiosira pseudonana)进行转录组测序,获得T.pseudonana硫代谢途径酶编码基因的差异表达结果。研究结果显示:在不同盐度下,共发现13个硫代谢途径的差异表达基因;随培养时间延长,低盐度培养的实验组相较于对照组有更多的硫代谢编码基因发生显著差异表达,如在硫酸盐同化过程中,在培养的第二天ATP硫酸化酶的基因表达量相对于第一天显著降低,其原因可能是因为藻细胞对硫酸盐同化需求的减少,从而可能会限制亚硫酸盐的形成;在低盐胁迫下,与半胱氨酸合成相关的酶(如丝氨酸乙酰转移酶)基因表达量显著降低,说明藻细胞减少了含硫氨基酸(如半胱氨酸)的合成,这些都会影响其正常的生命代谢活动。本研究表明,沿海河口区的盐度波动可能会对T.pseudonana的硫代谢产生重要影响,这一发现有助于深入理解近海广布藻华原因种应对盐度压力时的分子响应机制。

In order to provide an in-depth analysis of the regulating strategies for cellular processes of key life metabolic activities in the offshore widespread algal bloom species,when they are facing extensive salt variations,the transcriptomic sequencing for Thalassiosira pseudonana under different salinities and different cultivation time was executed in this study,and expression of sulfur metabolism related genes was analyzed.A total of 13 differentially expressed genes that related to sulfur metabolic pathways were identified with different salinity.The number of differentially expressed functional genes gradually increased in the reducing-salinity experimental group compared to the control group over culturing time.For example,during sulfur assimilation,the gene expression of ATP-sulfurylase was significantly lower on the second day of incubation compared to the first day,probably due to reducing demand for sulfate assimilation in the cells,which would further limit sulfite formation.Besides,the gene expression related to cysteine synthesis(e.g.serine acetyltransferase)significantly decreased in low salt stress.These results showed that the synthesis of sulfur-containing amino acids(such as cysteine biosynthesis)in T.pseudonana was reduced,and thus influencing the metabolic activity of microalgae.This study demonstrates that salinity fluctuation in the coastal estuarine areas will potentially affect the sulfur metabolism of T.pseudonana,which is helpful to understand the molecular mechanism of offshore widespread algal bloom species in response to salinity stress.