Ma Mingyang, Yang Wentao, Chen Hong, Ke Wanwan, Gong Yingchun, Hu Qiang
Institute for Advanced Study, Shenzhen University, Shenzhen, China.
Department of Biochemistry and Molecular Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States.
Front Microbiol. 2023 Oct 4;14:1173541. doi: 10.3389/fmicb.2023.1173541. eCollection 2023.
Mixotrophic flagellates, which have diverse nutritional modes and play important roles in connecting the microbial loop with the classical food chain, are ideal models to study the mechanisms of adaptation between different nutritional modes in protists. In their natural ecosystems, mixotrophic flagellates may encounter microalgal prey of different digestibility, which may affect the carbon flow. To date, a molecular biological view of the metabolic processes in the mixotrophic flagellate during nutritional adaptation and feeding on microalgal prey of different digestibility is still lacking. Accordingly, this study focused on the gene expression differences in under autotrophy, being fed by the digestible microalga GT-1, and being fed by the indigestible microalga CMBB-146. Results showed that the growth rate of under autotrophy was much lower than that when fed by digestible microalgae. Addition of CMBB-146 could only increase the growth rate of in the first 3 days, but the cell concentration of started to decrease gradually after 4 days. Compared to autotrophic , total 6,583 and 3,510 genes were significantly and differentially expressed in fed by digestible microalgae and indigestible microalgae, respectively. Compared to autotrophic cells, genes related to the ribosome, lysosome, glycolysis, gluconeogenesis, TCA cycle, β-oxidation, duplication, and β-1,3-glucan in grazing on digestible prey were up-regulated, while genes related to light harvesting and key enzymes referring to chlorophyll were down-regulated. Genes related to apoptosis and necrosis in were up-regulated after grazing on indigestible microalgae compared to the autotrophic group, which we suggest is associated with the up-regulation of genes related to lysosome enzymes. This study provides abundant information on the potential intracellular physiological responses of during the process of nutritional adaptation.
兼养鞭毛虫具有多种营养模式，在连接微生物环与经典食物链方面发挥着重要作用，是研究原生生物不同营养模式之间适应机制的理想模型。在其自然生态系统中，兼养鞭毛虫可能会遇到不同消化率的微藻猎物，这可能会影响碳流。迄今为止，对于兼养鞭毛虫在营养适应过程中以及摄食不同消化率的微藻猎物时的代谢过程，仍缺乏分子生物学视角的认识。因此，本研究聚焦于兼养鞭毛虫在自养、以可消化微藻GT-1为食以及以难消化微藻CMBB-146为食这三种情况下的基因表达差异。结果表明，兼养鞭毛虫自养时的生长速率远低于以可消化微藻为食时的生长速率。添加CMBB-146仅在前3天能提高兼养鞭毛虫的生长速率，但4天后其细胞浓度开始逐渐下降。与自养的兼养鞭毛虫相比，以可消化微藻为食和以难消化微藻为食的兼养鞭毛虫分别有6583个和3510个基因显著差异表达。与自养细胞相比，兼养鞭毛虫摄食可消化猎物时，与核糖体、溶酶体、糖酵解、糖异生、三羧酸循环、β-氧化、复制以及β-1,3-葡聚糖相关的基因上调，而与光捕获和叶绿素相关关键酶的基因下调。与自养组相比，兼养鞭毛虫摄食难消化微藻后，与凋亡和坏死相关的基因上调，我们认为这与溶酶体酶相关基因的上调有关。本研究为兼养鞭毛虫营养适应过程中潜在的细胞内生理反应提供了丰富信息。
