A Survey for Microalgae Situated in the Evolution from Prokaryote to Eukaryote.

关于原核生物向真核生物的进化问题，从内共生理论到直接亲缘关系理论一直争论不休。本课题可以从一种最原始的藻类中为这一讨论提供材料。本文调查了日本东北地区的Narugo、Goshokake温泉、北海道的Niseko温泉和美国黄石国家公园的酸性温泉中微藻的分布情况。这些温泉中广泛分布着单细胞真核蓝绿色前藻Cyanidium caldarium，而Galdieria suluraria仅局限于Niseko温泉和黄石国家公园的温泉中。用显微操作仪从美国黄石国家公园酸性温泉中分离到一株新菌株YR-89。典型的细胞是棒状的，有一个狭窄的葫芦状的部分，1 × 3妈妈大小，不像Cyanidioschyzon merolae，它的细胞是棒状的，没有狭窄的部分。细胞被薄而不稳定的膜包围，细胞形状有时不规则。它有一个细胞核和卵形叶绿体，卵形叶绿体有颗粒状的叶绿体类核（含有DNA的区域），以及不堆叠的类囊体，如Cyanidioschyzon melorae和Cyanidium caldarium。讨论了最原始的真核藻类（两种Cyanidioschyzon）可能是通过内共生过程进化而来的。

The problem on the evolution from prokaryote to eukaryote has been discussed from a long time between endosymbiotic theory and direct filiation theory. The present task could offered a material for this discussion from a such of the most primitivealgae. We surveyed microalgae occured in acid-hot springs such as Narugo, Goshokake spas in Tohoku district, and Niseko spa in Hokkaido in Japan, and those in Yellostone National Park, U. S. A. An Unicellular, eukaryotic, blue-green Prerhodophyta, Cyanidium caldarium is widely distributed in these hot-springs, and Galdieria sulphuraria is confined in Niseko spa and in hot springs in Yellowstone National Park. Cyanidioschyzon sp. YR-89, was newly isolated from acid-hot springs in Yellowstone National Park, using a micromanipulator. Typically the cell is clubshaped with a narrow gourd-like section, 1 x 3 mum in size, unlike Cyanidioschyzon merolae whose cell is club-shaped without a narrow section. The cell is surrounded by thin and labile membrane, and the cell shape is sometimes irregular. It has a nucleus and an ovoid chloroplast which has granular chloroplast nucleoid (DNA containing area), and unstacked thylakoids like Cyanidioschyzon melorae and Cyanidium caldarium. The probability is discussed, that those most primitive eukaryotic algae (two Cyanidioschyzon species) might be evolved by endosymbiotic process.