Starter Grant: Ecophysiology of Marine Picoeukaryotic Primary Producers

海洋微藻浮游植物是海洋生态系统的重要组成部分。这些微生物的直径只有0.2-2毫米，在海洋生态系统中非常丰富，占公海初级生产总量的50%-80%。尽管它们对全球碳循环很重要，但人们对这些生物的生态还没有很好的了解。特别是对微微浮游植物类群--微真核生物--知之甚少。为了成功地模拟它们的生态和全球碳循环，阐明它们与环境有关的生理学是至关重要的。该奖项是作为NSF微生物生物学博士后奖学金的后续活动而授予的博士后启动者。该项目的目标是探索微裸藻的光生理学和光保护机制的不同程度，为它们的相对成功做出贡献。对于光合作用的生物来说，调节光吸收和控制光损伤(包括紫外线)的能力是极其重要的。该项目的重点是一种新发现的对环境具有重要意义的生物--金黄色葡萄球菌，它是世界上已知的最小的自由生活的真核生物。基因组分析、生理生长研究和基因表达水平研究将被用来更好地了解这种生物的光合作用能力。金鱼草的基因组测序已接近完成，与光合作用和光胁迫反应相关的基因也已进行了调查。实验室实验将重点研究强光和紫外线对细胞生长的影响。已鉴定的光合作用基因在强光和/或紫外线胁迫，特别是类似于海洋表层水域的胁迫条件下的表达水平响应将通过定量聚合酶链式反应进行分析。本课程将探讨基于光生理学的生态型分化在链球菌菌株和其他常见微真核生物之间的程度。这项研究将有助于了解基本的光合作用过程以及影响这些重要初级生产者的分布和种群动态的潜在机制--使人们能够更好地了解微生物竞争、某些群体的优势以及全球碳循环。一名研究生将从一开始就参与该项目，并将接受高级研究培训。

Marine picophytoplankton are a key component of marine ecosystems. These microbes, which are only 0.2-2 mm in diameter, are highly abundant in marine ecosystems and responsible for up to 50-80% of total primary production in the open ocean. Despite their importance to global carbon cycling, the ecology of these organisms is not well understood. In particular little is known about one picophytoplankton group, the picoeukaryotes. It is critical that their physiology, as it relates to the environment, is elucidated in order to successfully model their ecology and global carbon cycles. This award is a postdoctoral starter grant as a follow-on activity to an NSF Microbial Biology Postdoctoral Fellowship. The goal of this project is to explore picoeukatyote photophysiology and the extent that photoprotective mechanisms differ, contributing to their relative success. For photosynthetic organisms the ability to regulate light absorption and control light damage (including UV) is extremely important. The project focuses on a newly discovered, environmentally important organism, Ostreococcus tauri, which is the smallest free-living eukaryote known in the world. Genome analysis, physiological growth studies and gene expression level studies will be used to better understand the photosynthetic capabilities of this organism. Genome sequencing of O. tauri is near completion and a survey of genes related to photosynthesis and light-stress responses has been conducted. Laboratory experiments will focus on the effects of high light versus UV light on cell growth. Expression level responses of the identified photosynthetic genes induced by high light and/or UV stress, especially stressful conditions akin to those of oceanic surface waters, will be analyzed by quantitative PCR. The extent of ecotypic differentiation, based on photophysiology, amongst Ostreococcus strains and other common picoeukaryotes will be explored. This research will contribute to knowledge of basic photosynthetic processes as well as the underlying mechanisms which shape the distribution and population dynamics of these important primary producers - allowing better understanding of microbial competition, dominance of certain groups, and global carbon cycling. A graduate student will be involved in the project from the outset, and will receive advanced research training.