Microbial Genome Sequencing: An EST Approach to Understanding Endosymbiotic Gene Transfer

爱荷华大学的Debashish Bhattacharya获得了一项赠款，用于创建来自有毒甲藻Alexandrium Tamarense和甲藻Emily huxleyi的表达基因(EST)的基因组资源。EST数据将被用来理解内共生在推动核基因组进化中的作用。内生共生作用解释了大多数藻类的起源，即单细胞原生生物吞噬并“奴役”另一个细胞的光合器官(叶绿体)。由于外源基因从捕获的内共生体到宿主核的大规模移动，叶绿体内共生必然会改变“宿主”谱系。这一过程被称为内生共生基因转移，是叶绿体功能所必需的。尽管它对细胞进化很重要，但对内共生基因转移的了解还处于初级阶段。为了获得对这一过程的基本认识，本研究使用基因组学方法，对亚历山大和埃米利亚尼亚的30,000个EST进行了测序。高质量的表达基因库被用于有效的“基因发现”策略，以产生一个全面的藻类EST集合。使用这些技术，将从每个藻类物种中产生约10,000个独特的EST。这些数据将是理解内共生基因转移的基础，并将为对藻类进化、有害藻华中的毒素产生(HAB)、碳循环和遗传学等主题感兴趣的科学家提供一个宝贵的资源，用于研究具有高度经济和生态重要性的两个类群的生物学。亚历山大藻在沿海地区引起赤潮，导致麻痹性贝类中毒，而埃米利亚氏菌在海洋开放水域占主导地位，在那里，其球石生物体阶段是地球上的主要碳汇。这是一个微生物基因组测序奖，由美国国家科学基金会和农业部合作资助。

Debashish Bhattacharya of the University of Iowa has been awarded a grant to create a genomic resource of expressed genes (ESTs) from the toxic dinoflagellate alga Alexandrium tamarense and the haptophyte alga Emiliana huxleyi. The EST data will be used to understand the role of endosymbiosis in driving nuclear genome evolution. Endosymbiosis, in which a single-celled protist engulfs and "enslaves" the photosynthetic organelle (plastid) of another cell, explains the origin of most algae. Plastid endosymbiosis necessarily changes the "host" lineage because of the large scale movement of foreign genes from the captured endosymbiont to the host nucleus. This process, known as endosymbiotic gene transfer, is required for plastid function. Despite its importance to cellular evolution, the understanding of endosymbiotic gene transfer is in its infancy. To gain fundamental insights into this process, a genomics approach is used in this research through the sequencing of 30,000 ESTs from Alexandrium and Emiliania. High-quality libraries of expressed genes are used in an efficient "gene discovery" strategy to generate a comprehensive collection of algal ESTs. Using these techniques, about 10,000 unique ESTs from each algal species will be produced. These data will be the basis for understanding endosymbiotic gene transfer and will provide a broad community of scientists interested in topics such as algal evolution, toxin production in harmful algal blooms (HABs), carbon cycling, and genetics with an invaluable resource for studying the biology of two taxa that are of high economic and ecological importance. Alexandrium causes HABs in coastal areas resulting in paralytic shellfish poisoning, whereas Emiliania is dominant in oceanic open waters where its coccolithophore phase acts as a major carbon sink on the planet. This is a Microbial Genome Sequencing Award funded through a collaborative program between the National Science Foundation and the Department of Agriculture.