The Genetic Significance of Viruses in the Marine Environment

病毒现在被认为是世界海洋中数量最多的生命形式。这一发现引发了无数关于病毒在海洋中的生态作用的问题。本研究将探讨海洋环境中病毒的遗传意义。病毒可能是海洋溶解（0.2 um）核酸池的重要组成部分，它们也有可能通过转导和病毒介导的转化影响基因转移来改变细菌基因库。为了研究病毒在海洋环境中的遗传意义，本研究将追求以下三个研究目标：1)确定河口、沿海和近海环境中表层和地下水中的病毒丰度，并开发沉积物中直接病毒计数的方法。将评估病毒丰度与总（自养和异养）宿主池大小之间的关系，以及与颗粒和溶解DNA含量的关系。2)测定河口、沿海和近海水体中病毒颗粒中所含颗粒核酸和溶解核酸的比例。将开发直接定量病毒DNA的方法，并将其与海洋样品中的细菌和“游离”（即可溶的，而不是被病毒包裹的）联系起来。3)通过研究温带噬菌体和溶原宿主细菌的存在，确定海洋环境中基因转导的可能性。利用分离的噬菌体-宿主系统和天然的病毒和细菌组合，该研究将通过化学和物理诱导裂解来确定温带噬菌体/溶原宿主的存在。一旦溶原被确定，它们将被用于研究染色体DNA和广泛宿主质粒的转导转移。这项研究将开始回答病毒在海洋基因库中的作用问题。

Viruses are now known to be the most numerically dominant form of life in the world's oceans. This revelation has raised a myriad of questions concerning the ecological role of viruses in the oceans. This study will investigate the genetic significance of viruses in the marine environment. Viruses could be a significant component of the oceanic dissolved (0.2 um) nucleic acid pools and they also have the potential to alter bacterial gene pools by effecting gene transfer by transduction and viral mediated transformation. To investigate the gentic significance of viruses in the marine environment this study wil pursue the following three research objectives: 1) To determine viral abundance in estuarine, coastal, and offshore environments in surface and subsurface waters, and to develop methods for direct viral enumeration in sediments. The relationship between viral abundance and total (autotrophic and heterotrophic) host pool size will be assessed, as well as the relationship with particulate and dissolved DNA content. 2) To determine the proportion of particulate and dissolved nucleic acids that are contained in virus particles in estuarine, coastal, and offshore waters. Methods will be developed to quantitate viral DNA directly and relate it to bacterial and "free" (i.e. soluble as opposed to that encapsulated in virons) in oceanic samples. 3) To determine the potential for gene transfer by transduction in the marine environment by investigating the presence of temperate phage and lysogenic host bacteria. Using both isolated phage-host systems and natural viral and bacterial assemblages, the study will determine the presence of temperate phage/lysogenic hosts by chemical and physical induction of lysis. Once lysogens have been identified, these will be used in studies on the transfer of chromosomal DNA and broad host range plasmids by transduction. This research will begin to answer the questions of the role of viruses in the oceanic gene pool.