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

关于从原核生物到真核生物的进化问题，内共生说和直系亲缘说一直争论不休。本课题可以从一个这样的最具生命力的藻类中为这一讨论提供材料。对日本东北地区的鸣吾温泉、五照挂温泉、北海道的二世古温泉和美国黄石国家公园的酸性温泉中的微藻进行了调查。S. A.在这些温泉中广泛分布着一种单细胞、真核、蓝绿色的前红藻，Cyanidium caldarium，Galdieria sulphuraria仅限于二世古温泉和黄石国家公园的温泉中。Cyanidioschyzonsp. YR-89是从美国黄石国家公园的酸性温泉中分离到的一种新的细菌。典型的细胞是棒状的，有一个狭窄的棒状部分，大小为1 × 3 μ m，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所包围，有时细胞形状不规则。它有一个核和一个卵形的叶绿体，叶绿体有颗粒状的叶绿体类核（含DNA区），和非堆叠的类囊体，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的可能性。

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.