Parmales: an insight into the origin and evolutionary success of diatoms

Parmales是一种未知的小型海洋浮游植物，细胞壁硅化。基于细胞壁结构的相似性，Parmales被认为是硅藻的近亲，硅藻是现代海洋中最成功的微藻类群，并可能在理解硅质细胞壁的起源和早期进化方面发挥关键作用，但这一点尚未明确。最近，我们在日本Oyashio地区首次分离到Parmales的培养物。对这种培养物的分子系统发育分析表明，Parmales属于自养裸鞭毛藻的博列藻分支和硅藻的姐妹群。本论文从生态学、生理学、基因组学和生物地球化学等方面对Parmales进行了研究，分析了它们之间的系统发育关系，包括硅藻和硅藻、叶绿体和线粒体基因组、硅质细胞壁的形成过程、Oyashio地区的种群动态、生活史和特定的生物标志物(分子化石)。

Parmales are an unknown small marine phytoplankton group with a silicified cell wall. Based on similarities in cell wall structure, Parmales has been proposed as a close relative of diatoms, the most successful microalgal group in modern oceans, and may play a key role in understanding their origin of silica cell wall and early evolution, which have not yet been clearly established. Recently, we isolated the first ever culture of Parmales in the Oyashio region of Japan. Molecular phylogenetic analysis of this culture indicated that Parmales was within the bolidophycean clade of autotrophic naked flagellates and a sister group of diatoms. We have studied on Parmales using ecological, physiological, genomic and biogeochemical approaches and analyzed their phylogenetic relationship between Bolidophycea and diatoms, chloroplast and mitochondria genomes, silica cell wall formation process, population dynamics in the Oyashio region, life cycle and specific biomarkers (molecular fossils).