Bidle Kay D
Department of Marine and Coastal Sciences, Rutgers University, New Brunswick, NJ 08901, USA.
Curr Biol. 2016 Jul 11;26(13):R594-R607. doi: 10.1016/j.cub.2016.05.056.
Unicellular, planktonic, prokaryotic and eukaryotic photoautotrophs (phytoplankton) have an ancient evolutionary history on Earth during which time they have played key roles in the regulation of marine food webs, biogeochemical cycles, and Earth's climate. Since they represent the basis of aquatic ecosystems, the manner in which phytoplankton die critically determines the flow and fate of photosynthetically fixed organic matter (and associated elements), ultimately constraining nutrient flow. Programmed cell death (PCD) and associated pathway genes, which are triggered by a variety of abiotic (nutrient, light, osmotic) and biotic (virus infection, allelopathy) environmental stresses, have an integral grip on cell fate, and have shaped the ecological success and evolutionary trajectory of diverse phytoplankton lineages. A combination of physiological, biochemical, and genetic techniques in model algal systems has demonstrated a conserved molecular and mechanistic framework of stress surveillance, signaling, and death activation pathways, involving collective and coordinated participation of organelles, redox enzymes, metabolites, and caspase-like proteases. This mechanistic understanding has provided insight into the integration of sensing and transduction of stress signals into cellular responses, and the mechanistic interfaces between PCD, cell stress and virus infection pathways. It has also provided insight into the evolution of PCD in unicellular photoautotrophs, the impact of PCD on the fate of natural phytoplankton assemblages and its role in aquatic biogeochemical cycles.
单细胞、浮游、原核和真核光合自养生物（浮游植物）在地球上有着古老的进化历史，在此期间它们在海洋食物网、生物地球化学循环和地球气候的调节中发挥了关键作用。由于它们是水生生态系统的基础，浮游植物死亡的方式至关重要地决定了光合固定有机物（及相关元素）的流动和归宿，最终限制了营养物质的流动。程序性细胞死亡（PCD）及相关途径基因，由各种非生物（营养、光照、渗透压）和生物（病毒感染、化感作用）环境胁迫触发，对细胞命运有着不可或缺的控制，并塑造了不同浮游植物谱系的生态成功和进化轨迹。在模式藻类系统中结合生理、生化和遗传技术，已证明了应激监测、信号传导和死亡激活途径的保守分子和机制框架，涉及细胞器、氧化还原酶、代谢物和半胱天冬酶样蛋白酶的集体和协调参与。这种机制上的理解为洞察应激信号的感知和转导如何整合到细胞反应中，以及PCD、细胞应激和病毒感染途径之间的机制界面提供了依据。它还为单细胞光合自养生物中PCD的进化、PCD对天然浮游植物群落命运的影响及其在水生生物地球化学循环中的作用提供了见解。
