GENETIC STUDIES WITH TETRAHYMENA

我们在纤毛虫遗传学计划的目的是发展物种 四膜虫属的研究， 研究真核生物的基本机制。 我们特别 对繁殖系统和生活方式的异质性感兴趣 它们都是在一个共同的身体设计的基础上进化而来的。 四膜虫纤毛虫包括几十种， 从无性无微核到自配子再到接合 具有复杂多样的调节系统的物种 交配 它们的范围也从表面上的自由生活 从食肉动物到寄生虫， 无脊椎动物宿主的数量。 要了解这些原生动物的多样性， 探索他们的关系。 在这方面，我们建议 继续我们对核糖体RNA序列的分析。 我们 测试基于“共享双类型”的“噪声过滤器”的有效性， 这些“位点”有望制造出即使是很短的RNA序列 关于远古时期进化事件的信息。 这 我们用来自5S、5.8S、17 S和23 S的序列举例说明这种方法 rRNA。 我们建议将这种进化分析扩展到几个 近年来收集的十几种菌株， 任何一个被命名的物种。 我们才刚刚开始 寄生/寄生和食肉形式的工作。 除此之外，我们计划将四膜虫安全地放置在 通过继续研究纤毛虫的进化历史， 纤毛虫生殖 我们希望能确定 纤毛虫原生动物从真核生物的根部出现，我们希望 去发现这种辐射的本质 我们的育种研究将集中在T。pigmentosa和T. 马六甲，这是进化不同的更多 一般研究T.嗜热菌，我们有一个 大量未发表的评论。 这些物种显示 一些截然不同的交配类型的表达， 血清型 我们怀疑， 四膜虫掩盖了一些有趣的差异， 体细胞大核中的核酸序列的管理。

Our intent in the program in ciliate genetics is to develop species of the genus Tetrahymena into more effective instruments in the study of basic eukaryotic mechanisms. We are particularly interested in the heterogeneity of breeding systems and life styles that have evolved on the basis of a common body design. Tetrahymenine ciliates consist of dozens of species that range from asexual amicronucleates through autogamates to conjugating species with sophisticated and diverse systems for regulating mating. They also range from apparently free-living bacteriophagous forms through carnivores to parasites on a number of invertebrate hosts. An understanding of the diversity of these protozoa requires an exploration of their relationships. In this connection we propose to continue our analyses of ribosomal RNA sequences. We are testing the validity of a "noise filter" based on "shared ditypic sites" that promises to make even short RNA sequences informative about evolutionary events at remote times. This approach we illustrate with sequences from 5S, 5.8S, 17S and 23S rRNAs. We propose the extension of this evolutionary analysis to several dozen strains collected in recent years that have not been assigned to any of the named species. We have only begun to work with the parasitic/commensal and carnivorous forms. Beyond that we plan to place the tetrahymenines securely in ciliate evolutionary history by continuing our study of general ciliate phylogeny. We expect to identify where and when the ciliated protozoa emerged from the eukaryotic roots, and we hope to discover something of the nature of that radiation. Our breeding studies will concentrate on T. pigmentosa and T. malaccensis, which are evolutionary distinct from the more commonly studied T. thermophila, and for which we have a substantial body of unpublished observations. These species show some strikingly different expressions of mating types and serotypes. We suspect that the superficial similarities among the tetrahymenines obscure some interesting differences in the management of nucleic sequences in the somatic macronucleus.