Endo Hisashi, Yamagishi Yuki, Nguyen Thi Tuyen, Ogata Hiroyuki
Bioinformatics Center, Institute for Chemical Research, Kyoto University, Kyoto, Japan.
Shimadzu Techno-Research Inc, Kyoto, Japan.
Environ Microbiol. 2025 Aug;27(8):e70164. doi: 10.1111/1462-2920.70164.
Marine plankton communities consist of numerous species, and their composition and physiological states are closely linked to ecosystem functions. Understanding biogeochemical cycles requires measuring taxon-specific mortality due to viral lysis, sloppy feeding, and other mechanical stresses as the dissolved organic matter released contributes to rapid nutrient recycling and long-term carbon sequestration following microbial transformation. To examine the lytic cell death of marine microeukaryotes, we applied a quantitative and comprehensive analysis of the dissolved constituents of seawater using the Mortality by Ribosomal Sequencing (MoRS) method. Our experimental pipeline successfully recovered 83% of cell-free rRNA. A higher number of protist phylotypes was significantly lysed in the mesopelagic zone than in the surface ecosystems, indicating that the mesopelagic zone is a potential hotspot for eukaryotic cell lysis. Many protist lineages, including phytoplankton such as haptophytes, were less susceptible to cell lysis in the epipelagic layer yet were actively lysed in the mesopelagic zone. Notably, over 86% of the significantly lysed species in the mesopelagic layer had a habitat preference for the epipelagic layer. These findings suggest that sinking from the surface and lysis in the mesopelagic may represent prevalent dynamics for various eukaryotes.
海洋浮游生物群落由众多物种组成，其组成和生理状态与生态系统功能密切相关。理解生物地球化学循环需要测量因病毒裂解、粗放摄食和其他机械应力导致的特定分类群死亡率，因为释放的溶解有机物在微生物转化后有助于快速的养分循环和长期的碳固存。为了研究海洋微真核生物的裂解性细胞死亡，我们使用核糖体测序死亡率（MoRS）方法对海水的溶解成分进行了定量和全面的分析。我们的实验流程成功回收了83%的无细胞rRNA。中层带中被显著裂解的原生生物分类型数量比表层生态系统中的要多，这表明中层带是真核细胞裂解的一个潜在热点。许多原生生物谱系，包括诸如定鞭藻等浮游植物，在上层带对细胞裂解不太敏感，但在中层带却被积极裂解。值得注意的是，中层带中超过86%的被显著裂解物种在栖息地偏好上是上层带。这些发现表明，从表层下沉并在中层带裂解可能是各种真核生物普遍存在的动态过程。
