Studies on systematic relationship of diatoms based on their sexual reproduction in culture.

本研究的目的是：1)在实验室培养条件下诱导硅藻的配子发生；2)分析硅藻的系统关系；3)根据硅藻的生活史，特别是它们的有性繁殖过程，分析硅藻的系统关系。八角藻、放线藻、湖泊海链藻和热带海藻，分析硅藻的系统发育关系。文中简要报道了它们的有性繁殖过程。八角体：雌雄同株，四个精子完全由母细胞产生(新发现)，辅助孢子由精子和鞭毛进入卵原细胞形成，鳞片状周壁覆盖着产生大的初始营养细胞的辅助孢子。放线菌：雌雄同株，四个精子由母细胞(30-50微米)无性生殖形成，辅助孢子的形成方式与串珠分枝杆菌相同。海链藻：雌雄同株，8个精子由母细胞无性生殖形成，辅助孢子(约30um)的形成方式与串珠藻相同。热带Eunotia tropica：雌雄异株(原藻亚科第一例)，配对细胞各产生一个配子，配子融合，成为覆盖有带状附着体的辅助孢子，该附着体的一部分具有与鳞状附着体相似的凹槽图案。

Objectives of this research project are the followings; 1)Inducing the gametogenesis of diatoms under laboratory culture conditions, 2)Analysis of the systematic relationship of diatoms based on their structures of auxospore coverings, 3) and based on their life cycle patterns, in particular to their sexual reproduction processes.We could accumulate the significant results of four taxa; Melosila moniliformis var. octagona, Actinocyclus sp., Thalassiosira lacustris and Eunotia tropica, for analizing the systematic and phylogenetic relationship of diatoms. These are briefly reported, focusing on their sexual reproduction processes.M. moniliformis var. octagona: monoecious, four sperms hologeneusly born from the mother cell(new finding), auxospore formed by a sperm with a flagellum penetrating into an oogonium, scally perizonia covering with the auxospore in which a large initial vegetative cell is produced.Actinocyclus sp.: monoecious, four sperms merogenously formed from the mother cell(30-50um), auxospore formed by the same manner as M. moniliformis var. octagona, and covered with scally perizonia(new finding), bearing an initial of the vegetative cell(90-130um).Thalassiosira lacustris: monoecious, eight sperms merogenously formed from the mother cell, auxospore(ca.30um) formed by the same manner as M. moniliformis var. octagona, and covered with scally perizonia(new finding), bearing an initial vegetative cell(ca.80um).Eunotia tropica: dioecious(first case in the Protoraphidioideae), pairing cells producing a gamete in each, gametes fusing and becoming a auxospore covered with band-shaped perizonia which possess similar pattern of notches to those of scally ones in a part.