Plastid-Associated Genes in Dinoflagellates Identified by cDNA Screening and Expression Analysis

摘要该项目将探索甲藻的遗传和基因组特性，目的是利用基因组技术研究外膜型质体整合到宿主细胞中的情况。该项目的具体目标是：1)确定最适合于分子遗传学研究的甲藻物种；2)检测甲藻的核、叶绿体和线粒体基因组的基本性质，并探索其对基因组研究的适宜性；3)建立一个丰富的稀有转录本的cDNA文库，对该文库中的数百个克隆进行测序，并筛选这些序列中与叶绿体相关的基因。一个关键的问题是，为什么这些生物拥有如此巨大的基因组；目前尚不清楚基因组的复杂程度是否与其庞大的规模相匹配。为了了解甲藻基因组的组织结构，还必须确定该基因组是否为多倍体，以及甲藻基因编码为多基因的程度。这与鉴定与叶绿体相关的基因相一致，将导致对甲藻基因组组织的了解，以及叶绿体与宿主细胞的遗传整合。甲藻是一组独特的鞭毛原生动物，与大多数模式生物有较远的亲缘关系，并具有许多在真核生物中不寻常的特征。它们是海洋和淡水浮游生物群落的重要成员，并可能对有害的藻华和毒素产生负责。虽然在甲藻中发现了几种类型的质体(叶绿体)，但大多数光合作用的甲藻依赖于包括色素周胶在内的质体，以及叶绿素a和c。这些周胶类型的质体由三层膜结合。该项目将探索甲藻的遗传和基因组特性，目的是利用基因组技术研究周围型质体与其宿主细胞的整合。对甲藻的遗传研究相对较少，因此该项目将重点研究基本的遗传特性，如核基因组的大小和基因含量，基因转录本上多聚A尾巴的存在程度，以及核和叶绿体之间相互作用的基础。

Abstract The project will explore the genetic and genomic properties of dinoflagellates, with the aim of using genomic techniques to study the integration of the peridinin-type plastid into its host cell. The specific goals of the project are 1) to identify the most suitable dinoflagellate species for molecular genetic studies 2) to examine the fundamental properties of the nuclear, chloroplast, and mitochondrial genomes in this dinoflagellate, and explore its suitability for genomic studies, and 3) to generate a cDNA library that has been enriched for rare transcripts, sequence several hundred clones from this library, and screen these sequences for plastid-associated genes. One key question is why these organisms have such remarkably large genomes; it is not clear that the complexity of the genomes matches its large size. To understand the organization of the dinoflagellate genome, it will also be important to determine whether the genome is polyploid, and the extent to which dinoflagellate genes are encoded as polygenes. This, in concert with the identification of plastid-associated genes, will lead to an understanding of dinoflagellate genome organization, and the genetic integration of the plastid into the host cell. Dinoflagellates are a distinctive group of flagellate protists that are distantly related to most model organisms, and have many features that are unusual among eukaryotes. They are important members of both marine and freshwater plankton communities, and can be responsible for harmful algal blooms and toxin production. While there are several types of plastids (chloroplasts) found in dinoflagellates, the majority of photosynthetic dinoflagellates rely on plastids that include the pigment peridinin, along with chlorophylls a and c. These peridinin-type plastids are bound by three membranes. The project will explore the genetic and genomic properties of dinoflagellates, with the aim of using genomic techniques to study the integration of the peridinin-type plastid into its host cell. Relatively little genetic work has been performed with dinoflagellates, so the project will emphasize investigations into fundamental genetic properties such as the size and gene content of the nuclear genome, the degree to which poly-A tails are present on gene transcripts, and the basis for interaction between the nucleus and plastid.