Du Feichao, Li Yuhang, Bilcke Gust, Sato Shinya, Xu Kuidong
Laboratory of Marine Organism Taxonomy and Phylogeny, Qingdao Key Laboratory of Marine Biodiversity and Conservation, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China; University of Chinese Academy of Sciences, Beijing, 100049, China.
Laboratory of Marine Organism Taxonomy and Phylogeny, Qingdao Key Laboratory of Marine Biodiversity and Conservation, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China.
Mar Environ Res. 2025 Feb;204:106859. doi: 10.1016/j.marenvres.2024.106859. Epub 2024 Nov 28.
Extreme climate events, such as marine heatwaves (MHWs), are expected to occur more frequently and intensely in the future, resulting in a substantial impact on marine life. The way that diatoms respond to MHWs may have crucial effects on global primary production and biogeochemical cycles. Euplanktonic diatoms appear to benefit from MHWs directly, but this phenomenon needs an explanation. As concerns tychoplanktonic and benthic diatoms, no studies have been addressed on their thermal response strategies. To address this, we investigated the responses and underlying mechanisms of three typical growth forms of diatoms, Pseudo-nitzschia multiseries (euplanktonic), Paralia guyana (tychoplanktonic) and Navicula avium (benthic), under heat stress by combining a growth experiment with transcriptomic analysis. Our results showed that the physiological responses of diatoms to MHWs and underlying molecular mechanisms are largely related to their growth forms. The euplanktonic diatom was first depressed, but then had a distinct increase in the growth rate accompanied by inducing zeatin and unsaturated fatty acid biosynthesis and repressing substance assimilation and energy metabolism. Contrarily, the benthic diatom showed elevated substance and energy demands for macromolecules accumulation by reducing cell division and increasing photosynthesis and nitrogen assimilation. The tychoplanktonic diatom exhibited higher physiological plasticity to maintain growth and cellular homeostasis. Our results indicate the increased rate of cell division in euplanktonic diatoms under heat stress is likely an emergency response strategy promoting diatom dispersal for survival, but at the cost of disturbances of metabolic balance.
极端气候事件，如海洋热浪（MHWs），预计在未来会更频繁、更强烈地发生，从而对海洋生物产生重大影响。硅藻对海洋热浪的响应方式可能会对全球初级生产和生物地球化学循环产生关键影响。真浮游硅藻似乎直接受益于海洋热浪，但这种现象需要解释。关于 tychoplanktonic 和底栖硅藻，尚未有关于它们热响应策略的研究。为了解决这个问题，我们通过结合生长实验和转录组分析，研究了三种典型生长形式的硅藻，即多列拟菱形藻（真浮游）、圭亚那圆筛藻（tychoplanktonic）和鸟舟形藻（底栖）在热胁迫下的响应及其潜在机制。我们的结果表明，硅藻对海洋热浪的生理响应和潜在分子机制在很大程度上与其生长形式有关。真浮游硅藻首先受到抑制，但随后生长速率明显增加，同时诱导玉米素和不饱和脂肪酸生物合成，并抑制物质同化和能量代谢。相反，底栖硅藻通过减少细胞分裂并增加光合作用和氮同化，对大分子积累表现出更高的物质和能量需求。tychoplanktonic 硅藻表现出更高的生理可塑性以维持生长和细胞内稳态。我们的结果表明，热胁迫下真浮游硅藻细胞分裂速率的增加可能是一种促进硅藻扩散以生存的应急响应策略，但代价是代谢平衡受到干扰。
