五株纤毛虫遗传关系的ISSR分析

GENETIC RELATIONSHIPS OF FIVE CILIATE STRAINS INFERRED FROM ISSR ANALYSIS

采用ISSR分子标记技术,尝试对四种五株纤毛虫(褶累枝虫(Epistylis plicatilis)、绿草履虫(Paramecium bursaria)、多态喇叭虫(Stentor polymorphus)、嗜热四膜虫BF1株(Tetrahymena thermophilaBF1)和嗜热四膜虫BF5株(T.ther-mophilaBF5))进行遗传关系研究。用13个ISSR引物对五株纤毛虫进行扩增,六个ISSR引物获得多态片段。根据Nei s遗传距离矩阵构建了五株纤毛虫的遗传关系树状图。UPGMA,NJ聚类图表明:两株嗜热四膜虫最先聚在一起;其次是褶累枝虫和多态喇叭虫聚在一起,然后再与嗜热四膜虫聚在一起;咽膜亚纲的绿草履虫形成独立的一枝。结果显示:①缘毛亚纲纤毛虫可能是寡膜纲中较独特的一个类群,建议提升缘毛亚纲纤毛虫的分类地位;②缘毛亚纲褶累枝虫与膜口亚纲嗜热四膜虫的亲缘关系近于咽膜亚纲绿草履虫,在寡膜纲中绿草履虫处于原始地位;③五株纤毛虫基因组中均含有微卫星DNA序列:(GTG)4(、GACA)4(、AG)8(、CAA)6和(GAA)6。

ISSR analysis was conducted to investigate the genetic relationships of five ciliate strains： Epistylis plicatilis, Paramecium bursaria, Stentor polymorphus, Tetrahymena thermophila BF1 and T. thermophila BF5. Out of 13 ISSR primers, 6 primers generated highly reproducible and polymorphic DNA fragments. The genetic trees were constructed based on ISSR amplification fingerprintings using both unweighted pair-group method fo）r arithmetic averages analysis （UPGMA） and neighbor-joining （NJ） methods. Two T. thermophila strains formed one branch first. E. plicatilis clustered with S. polymorphus, then grouped with T. thermophila. P. bursaria formed a separate branch. This shows that ① the peritrichs may be recognized as the particular ciliates within Oligohymenophorea, and they should be elevated to a higher taxonomic rank; ②the Peritrichia E. plicatilis has the closer relation with the Hymenostomatia T. thermophila than the Peniculia P. bursaria, which is the primordial group in the class Oligohymenophorea; ③ The genome of the five ciliate strains contain these microsatellite DNA sequences： （GTG）4, （GACA）4, （AG）8, （CAA）6 and （CAA）6.