螅状独缩虫自然种群同工酶的研究

STUDIES ON ISOZYMES OF WILD CARCHESIUM POLYPINUM

利用聚丙烯酰氨凝胶电泳技术 ,对采自武汉沙湖螅状独缩虫自然种群的酯酶 (EST)、苹果酸脱氢酶 (MDH)、乳酸脱氢酶 (LDH)和酸性磷酸酶 (ACP)四种同工酶酶系进行了研究。实验表明 :EST同工酶酶系由六个基因座位(Est 1—Est 6 )控制 ,其中Est 1、Est 2、Est 3和Est 5为杂合基因座位 ,而Est 4和Est 6为纯合基因座位。螅状独缩虫物种中EST同工酶四级结构既有单体也有二聚体 ;MDH同工酶酶系由五个基因座位 (Mdh 1—Mdh 5 )控制 ,其中Mdh 2和Mdh 3为杂合基因座位 ,而Mdh 1、Mdh 4和Mdh 5为纯合基因座位。螅状独缩虫苹果酸脱氢酶存在明显的上清液型 (s MDH)和线粒体型 (m MDH)酶带 ;LDH同工酶酶系较其他原生动物发达 ,由 5条明显酶带组成。与高等动物研究结果比较分析认为 ,螅状独缩虫乳酸脱氢酶同工酶酶系可能为一个杂合基因座位AB控制 ;ACP同工酶酶系简单 ,为一个纯合基因座位编码。取得的结果为揭示螅状独缩虫酶学特征及其自然种群的遗传特征等问题提供了基础资料。

Carchesium polypinum, a cosmopolitan protozoa, belongs to Carchesium Ehrenberg, Peritrichida Stein, Oligohymenophorea de Puytorac et al., Ciliophora Doffein. From the 1940s, many wide and deep resesrches of its morphology and structure have been done at organism, subcellular and molecular levels. Karl described detailed characteristics of the whole organism first in 1932. After that, Lom studied the accurate fiber structure under pellicle, which is the most important criterion of speices identification and analysis of relationship between populations of ciliate. Along with the development of the molecular techniques, there are some reports about the protein and DNA structure of it, but the knowledge of isozyme——the important technique studies about species identification, relationship of intraspecific and interspecific and population genetic structure of this protozoa is very poor. In this paper, polyacrylamide gel electrophorosis was used to study four isozymes—Esterase (EST), Malate dehydrogenase (MDH), Lactate dehydrogenase (LDH) and Acid phosphatase (ACP), of three Carchesium polypinum populations from the Sand Lake of Wuhan, Hubei province. The results show that EST can be divided into 7 brown bands and 6 purple bands and are controlled by six loci (Est-1—Est-6), out of which Est-1, Est-2,Est-3 and Est-5 are heterozygotes and Est-4 and Est-6 are homozygotes. The analysis of its electrophoretic banding patterns indicates that its quaternary structure involves 2 patterns: monomer and dimmer. The bands of MDH are coded by five loci (Mdh-1—Mdh-5), in which Mdh-1, Mdh-4 and Mdh-5 are heterozygotes and Mdh-2 and Mdh-3 are homozygotes. These bands can be distinctly divided into two typical kinds—s-MDH bands and m-MDH bands. The LDH expressed in Carchesium polypinum is more than it dose in other protozoans. Five bands are coded by one heteozygotic locus—AB, compared with the conditions in higher animal. ACP has only one band and is controlled by a homozygote locus. This work can not only accumulates the information of isozymic characters of wild Carchesium polypinum, but also provide a powerful lever for the studies on the population genetics and ecology.