TSUKII Yuuji Institute of Biology, Hosei University, Professor, 第一教養部, 教授 (20163777)
MIKAMI Kazuyuki Environmental Education Center, Miyagi College of Education, Professor, 環境教育実践研究センター, 教授 (90009177)
|Budget Amount *help
¥6,800,000 (Direct Cost : ¥6,800,000)
Fiscal Year 1999 : ¥3,600,000 (Direct Cost : ¥3,600,000)
Fiscal Year 1998 : ¥3,200,000 (Direct Cost : ¥3,200,000)
To study the species evolution in Paramecium caudatum, many natural strains at different geographic places are necessary, and establishment by recovery of the lost syngen (genetical species) is essential. Therefore, I carried out collection of natural strains in USA, Canada and Uruguay Republic.
1. The collections were carried out at 197 points around the Five lakes and the eastern part of USA, and at 78 points in Uruguay Republic. P. caudatum was obtained from 34 sampling points, and 222 isolation lines were established.
2. Three groups consisting in complementary mating types, that is "syngen", were discovered. These three syngens are independent from known syngens. They are tentatively called as syngen a, syngen b and syngen d. New strains belonging to syngen 1, syngen 3, syngen 5 and syngen 12 were also obtained.
3. Surprisingly, a problem in identification of species revealed from the analyses of some strains, for example UC131 or UC151. They look like P. caudatum very much in size of cells and external morphology, but their RAPD patterns are quite different from many strains of P. caudatum. They have 2-5 vesicular type micronuclei, two contractile vacuoles and living in fresh water. These characteristics are not identical to the known biological species. Further studies are necessary whether they are really new biological species or not.
4. Some strains show inter-syngen mating reactions. This evidence emphasizes an importance of establishment of the syngen standard strains.