EAGER: Cell to cell communication in marine phytoplankton: population density dependent control of cellular processes

EAGER：海洋浮游植物中的细胞间通讯：细胞过程的种群密度依赖性控制

• 批准号: 1140042
• 负责人: Maria Vernet
• 金额: $ 28.61万
• 依托单位: University of California-San Diego Scripps Inst of Oceanography
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-07-15 至 2013-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1140042&HistoricalAwards=false
• 关键词: EAGER; Cell; cell; communication; marine

Recent discoveries have shown that cell-cell communication extends from the intra-species to the inter-kingdom level and play pivotal roles in population-wide biological events such as changes in morphology, metabolic state and population structure. Quorum sensing (QS) is a communication process that allows single cells to cooperatively function as a decentralized network. Studies in prokaryotes and, more recently, fungi have demonstrated that QS regulates the timing of key biological processes such as colony formation, sporulation, morphological changes, pathogenicity and sexual reproduction. In the marine environment, QS has been demonstrated in bacteria however, this level of mutual cooperation has not been considered for phytoplankton populations. In view of the emerging literature on the critical role of cell-cell communication, it is timely to reconsider how we regard marine phytoplankton.Thus far marine phytoplankton cell-cell interaction studies have primarily focused on chemical signals for competition against other species (e.g. allelopathy), predation deterrence and warning systems for environmental stress. There are several lines of circumstantial evidence to support QS in phytoplankton such as the timing of cell division, density dependent allelopathy and programmed cell death. However, to our knowledge there has been no direct experimentation to determine if phytoplankton can function in a cooperative consortium. Do they have a quorum sensing- type of communication to regulate intra-species processes as well as modulates inter-species interactions? Are recurrent phytoplankton communities established because these species are able to communicate with each member serving a specific role to maintain the population? These are difficult questions to address but have far reaching implications in our understanding of phytoplankton ecology.This project will test whether phytoplankton have a QS system by examining the process of autoinduction (a basic tenant for QS) for specific biological events. The PIs will test this by examining two specific areas using phytoplankton ecological and physiological measurements coupled with state of the art bio-informatic and genomic tools:I. Perform an extensive search for candidate phytoplankton QS-related genes in existing genomic and gene expression databases, based on homology with QS-related genes from other organisms. The PIs will conduct a detailed analysis to definitively map homologs of these QS regulatory pathways in their entirety as well as the few known biosynthetic pathways of QS compounds and transcriptional/translational regulators onto phytoplankton genomes. The results will be included as part of a comparative genomics study on cell-to-cell communication in phytoplankton, and the possible role of any candidate genes in QS will be tested by the experiments detailed below (2).II. Establish autoinduction of cellular processes in a diatom species using an experimental approach. The PIs will focus on the autoinduction of growth, cell morphology, allelopathy and biofilm formation using axenic cultures using two model diatom species, Phaeodactylum tricornutum Bohlin and Thalassiosira pseudonana.Intellectual Merit: The establishment of a QS-like communication system will bring in a new perspective to our views on phytoplankton ecology beyond our current paradigm of bottom-up and top-down controls or competitive interactions. Results from this study will also influence our views on the factors controlling phytoplankton population diversity, as we will now have to consider the role of inter-species communication. Funding through an EAGER proposal will provide support for exploratory, high-risk research to obtain a minimum set of data as proof of concept of QS in phytoplankton.Broader Impacts: The PIs will establish a collaboration with a local high school. They seek to remedy the mismatch in the way biology is taught and practiced by teaching high-school students to examine biological phenomena from a systems perspective. This will better prepare them for potential science careers in the information era while fostering their curiosity about their local marine ecosystem.

最近的研究表明，细胞间的交流从种内扩展到界间水平，并在种群范围内的生物事件中发挥关键作用，如形态、代谢状态和种群结构的变化。群体感应（Quorum sensing， QS）是一种允许单个细胞作为分散网络协同工作的通信过程。对原核生物的研究以及最近对真菌的研究表明，QS调节了关键生物过程的时间，如菌落形成、产孢、形态变化、致病性和有性生殖。在海洋环境中，QS已在细菌中得到证实，但这种水平的相互合作尚未被考虑到浮游植物群体。鉴于关于细胞间通讯的关键作用的新兴文献，是时候重新考虑我们如何看待海洋浮游植物了。迄今为止，海洋浮游植物细胞-细胞相互作用的研究主要集中在与其他物种竞争的化学信号（如化感作用）、捕食威慑和环境压力警告系统。有几条间接证据支持浮游植物中的QS，如细胞分裂的时间、密度依赖性化感作用和程序性细胞死亡。然而，据我们所知，目前还没有直接的实验来确定浮游植物是否能在合作联盟中发挥作用。它们是否具有群体感应类型的通信来调节种内过程以及调节种间相互作用？周期性浮游植物群落的建立是否因为这些物种能够与每个成员进行交流，以维持种群的特定角色？这些都是很难解决的问题，但对我们对浮游植物生态学的理解有着深远的影响。该项目将通过研究浮游植物对特定生物事件的自诱导过程（QS的基本租户）来测试浮游植物是否具有QS系统。pi将通过使用浮游植物生态和生理测量以及最先进的生物信息学和基因组工具来检查两个特定区域来验证这一点：根据与其他生物的qs相关基因的同源性，在现有的基因组和基因表达数据库中广泛搜索候选浮游植物qs相关基因。pi将进行详细的分析，以确定这些QS调控途径的同源物，以及少数已知的QS化合物和转录/翻译调控因子的生物合成途径到浮游植物基因组上。这些结果将作为浮游植物细胞间通讯的比较基因组学研究的一部分，任何候选基因在QS中的可能作用将通过下面(2)详细的实验进行测试。利用实验方法在硅藻物种中建立细胞过程的自诱导。该项目将重点研究两种模式硅藻——三角褐藻（Phaeodactylum tricornutum Bohlin）和假海硅藻（thalassisira pseudonana）——在无菌培养条件下的自诱导生长、细胞形态、化感作用和生物膜形成。智力价值：建立一个类似qs的交流系统将为我们对浮游植物生态学的看法带来一个新的视角，超越我们目前自下而上和自上而下的控制或竞争相互作用的范式。这项研究的结果也将影响我们对控制浮游植物种群多样性的因素的看法，因为我们现在必须考虑物种间交流的作用。通过EAGER提案提供的资金将为探索性、高风险的研究提供支持，以获得最少的数据集，作为浮游植物QS概念的证明。更广泛的影响：pi将与当地一所高中建立合作关系。他们试图通过教高中生从系统的角度审视生物现象来弥补生物学教学和实践方式的不匹配。这将更好地为他们在信息时代的科学事业做好准备，同时培养他们对当地海洋生态系统的好奇心。