Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China.
Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266071, China.
BMC Biotechnol. 2019 Jul 26;19(1):53. doi: 10.1186/s12896-019-0544-4.
Increasing CO emissions have resulted in ocean acidification, affecting marine plant photosynthesis and changing the nutrient composition of marine ecosystems. The physiological and biochemical processes of marine phytoplankton in response to ocean acidification have been reported, but have been mainly focused on growth and photosynthetic physiology. To acquire a thorough knowledge of the molecular regulation mechanisms, model species with clear genetic background should be selected for systematic study. Phaeodactylum tricornutum is a pennate diatom with the characteristics of small genome size, short generation cycle, and easy to transform. Furthermore, the genome of P. tricornutum has been completely sequenced.
In this study, P. tricornutum was cultured at high and normal CO concentrations. Cell composition changes during culture time were investigated. The C isotope tracing technique was used to determine fractional labeling enrichments for the main cellular components. The results suggested that when lipid content increased significantly under high CO conditions, total protein and soluble sugar contents decreased. The C labeling experiment indicated that the C skeleton needed for fatty acid C chain elongation in lipid synthesis under high CO conditions is not mainly derived from NaHCO (carbon fixed by photosynthesis).
This study indicated that breakdown of intracellular protein and soluble sugar provide C skeleton for lipid synthesis under high CO concentration.
不断增加的 CO 排放导致海洋酸化，影响海洋植物的光合作用，并改变海洋生态系统的营养成分组成。海洋浮游植物对海洋酸化的生理生化响应已有报道，但主要集中在生长和光合作用生理方面。为了全面了解分子调控机制，应选择具有明确遗传背景的模式物种进行系统研究。三角褐指藻是一种有翼的硅藻，具有基因组小、世代周期短、易于转化等特点。此外，三角褐指藻的基因组已经完全测序。
本研究在高 CO 和正常 CO 浓度下培养三角褐指藻，研究了培养过程中细胞组成的变化。利用 C 同位素示踪技术测定了主要细胞成分的分数标记丰度。结果表明，在高 CO 条件下，当脂质含量显著增加时，总蛋白和可溶性糖含量下降。C 标记实验表明，在高 CO 条件下，脂质合成中脂肪酸 C 链延长所需的 C 骨架不是主要来源于 NaHCO（光合作用固定的碳）。
本研究表明，在高 CO 浓度下，细胞内蛋白质和可溶性糖的分解为脂质合成提供了 C 骨架。
