Department of Biological Sciences and Center for Comparative Genomics, University of Iowa, Iowa City, Iowa 52242 USA;
Am J Bot. 2004 Oct;91(10):1523-34. doi: 10.3732/ajb.91.10.1523.
In this paper, we focus on dinoflagellate ecology, toxin production, fossil record, and a molecular phylogenetic analysis of hosts and plastids. Of ecological interest are the swimming and feeding behavior, bioluminescence, and symbioses of dinoflagellates with corals. The many varieties of dinoflagellate toxins, their biological effects, and current knowledge of their origin are discussed. Knowledge of dinoflagellate evolution is aided by a rich fossil record that can be used to document their emergence and diversification. However, recent biogeochemical studies indicate that dinoflagellates may be much older than previously believed. A remarkable feature of dinoflagellates is their unique genome structure and gene regulation. The nuclear genomes of these algae are of enormous size, lack nucleosomes, and have permanently condensed chromosomes. This chapter reviews the current knowledge of gene regulation and transcription in dinoflagellates with regard to the unique aspects of the nuclear genome. Previous work shows the plastid genome of typical dinoflagellates to have been reduced to single-gene minicircles that encode only a small number of proteins. Recent studies have demonstrated that the majority of the plastid genome has been transferred to the nucleus, which makes the dinoflagellates the only eukaryotes to encode the majority of typical plastid genes in the nucleus. The evolution of the dinoflagellate plastid and the implications of these results for understanding organellar genome evolution are discussed.
本文重点研究了甲藻生态学、毒素产生、化石记录以及宿主和质体的分子系统发育分析。游泳和摄食行为、生物发光以及甲藻与珊瑚的共生关系具有生态意义。本文讨论了多种甲藻毒素的生物效应及其起源的现有知识。甲藻进化的知识得益于丰富的化石记录，这些记录可用于记录它们的出现和多样化。然而，最近的生物地球化学研究表明，甲藻的历史可能比以前认为的要久远。甲藻的一个显著特征是其独特的基因组结构和基因调控。这些藻类的核基因组非常庞大，缺乏核小体，并且染色体始终处于浓缩状态。本章综述了有关核基因组独特方面的甲藻基因调控和转录的现有知识。先前的研究表明，典型甲藻的质体基因组已简化为仅编码少数蛋白质的单基因迷你环。最近的研究表明，质体基因组的大部分已转移到细胞核中，这使得甲藻成为唯一在核中编码大多数典型质体基因的真核生物。讨论了甲藻质体的进化以及这些结果对理解细胞器基因组进化的意义。
