Dinotoms: a novel model system for plastidogenesis studies between kleptoplasty and endosymbiosis

Dinotoms：一种用于盗贼成形术和内共生之间质体发生研究的新型模型系统

• 批准号: 424360600
• 负责人: Dr. Norico Yamada, Ph.D.
• 金额: --
• 依托单位: Arbeitsgruppe Ökophysiologie der Pflanzen
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/424360600?language=en
• 关键词: Dinotoms; novel; model; system; plastidogenesis

It is widely accepted that all plastids were originally independent microalgae and arose by endosymbiotic events; however, many processes of plastidogenesis remain a mystery as almost all phototrophs already passed through the evolutionary developmental stages. Many model organisms are used to shed light on the developmental processes of plastids, e.g., sea slugs Elysia spp., ciliates Mesodinium spp., or the amoeba Paulinella chromatophore. The yet most unexplored question of plastidogenesis is: how do free-living microalgae transform into early-stage endosymbionts. However, none of the present model organisms can be applied to answer this question, because they are either still in the transient (“kleptoplastic”), or already in the permanent endosymbiotic stage. Dinotoms, dinoflagellates that harbour diatoms as their photosynthetic endosymbionts, are ground-breaking organisms that allow us to experimentally test these elsewise hidden processes. Their endosymbiotic diatoms exhibit three successive evolutionary stages: a kleptoplastic stage (D. capensis), in which ingested diatoms are maintained for approximately two months; a stage in which multiple endosymbiotic diatoms are permanently maintained (D. kwazulunatalensis); and a stage where a single diatom is permanently maintained (other known dinotoms). To establish D. capensis, D. kwazulunatalensis and the diatom Nitzschia cf. agnita, the plastidial source of D. capensis, as a model system that is explorable with modern molecular biology techniques, I and my collaborators are currently generating their genomic and transcriptomic information as well as genetic modification tools. During the first DFG-funded period, I focused on establishing the D. capensis strain to clarify its evolutionary stage and to investigate the bioactivity of N. cf. agnita after ingestion by D. capensis. This proposal aims to use the newly-established model system to elucidate the molecular evolutionary processes from kleptoplasty to early permanent endosymbiosis. I propose three hypotheses, based on my achievements of the first DFG period. These hypotheses are A) host dinoflagellates tightly control their endosymbiotic diatoms metabolically already at the kleptoplastic stage; B) the presence or absence of two systems, i.e., the control of diatom cell cycle gene expression and the control of nitrate supply for endosymbiotic diatoms, separates the evolutionary stages between D. capensis and D. kwazulunatalensis; and C) diatom mitochondria reduce their activity already at the kleptoplastic stage and the functions are partially replaced by dinoflagellate mitochondria. These projects will be conducted with the already-established N. cf. agnita transformation tools and the analysed dinotom transcriptomic data. My projects aim to elucidate how deeply endosymbiotic diatoms are integrated and controlled by the host at the different evolutionary stages of D. capensis and D. kwazulunatalensis.

人们普遍认为，所有质体最初都是独立的微藻，并通过内共生事件产生;然而，许多质体发生的过程仍然是一个谜，因为几乎所有的光养生物都已经经历了进化发育阶段。许多模式生物被用来阐明质体的发育过程，例如，海蛞蝓Elysia属，纤毛虫中缢虫属，或者变形虫Paulinella色素细胞。质体发生中最未被探索的问题是：自由生活的微藻如何转化为早期的内共生体。然而，没有一个目前的模式生物可以用来回答这个问题，因为它们要么仍然处于短暂的（“kleptoplastic”），或已经在永久的内共生阶段。甲藻，甲藻的港口硅藻作为其光合作用的内共生体，是突破性的生物，使我们能够实验测试这些其他隐藏的过程。它们的内共生硅藻表现出三个连续的进化阶段：一个kleptoplastic阶段（D。capensis），其中摄入的硅藻维持约两个月;多个内共生硅藻永久维持的阶段（D. kwazulunatalensis）;以及一个阶段，其中一个单一的硅藻是永久维持（其他已知的恐龙）。建立D. capensis、黑腹叶蝉D. kwazulunatalensis和硅藻Nitzschia cf. agnita，D. capensis，作为一个可以用现代分子生物学技术探索的模型系统，我和我的合作者目前正在生成他们的基因组和转录组信息以及遗传修饰工具。在DFG资助的第一个时期，我专注于建立D。capensis菌株，以明确其进化阶段，并研究其生物活性。参见ignita后摄入D. Capensis。本研究的目的是利用新建立的模型系统来阐明从kleptoplasty到早期永久性内共生的分子进化过程。本文根据第一次德意志联邦共和国时期的研究成果，提出了三个假设。这些假设是：A）宿主甲藻在纤体阶段就已经在代谢上严格控制它们的内共生硅藻; B）两个系统的存在或不存在，即，硅藻细胞周期基因表达的控制和内共生硅藻硝酸盐供应的控制，将D. capensis和D.夸祖鲁纳塔尔人;和C）硅藻线粒体在kleptoplastic阶段已经降低了它们的活性，并且其功能部分地被甲藻线粒体取代。这些项目将与已经成立的N。参见agnita转换工具和分析的dinotom转录组数据。我的项目旨在阐明内共生硅藻在不同进化阶段的宿主整合和控制的深度。capensis和D.夸祖鲁纳塔尔人