Tetrahymena micronuclear genome mapping: A high-resolution meiotic map of chromosome 1L

The ciliate Tetrahymena thermophila is a useful model organism that combine s diverse experimental advantages with powerful capabilities for genetic ma nipulation. The genetics of Tetrahymena are especially rich among eukaryoti c cells, because it possesses two distiller but related nuclear genomes wit hin one cytoplasm, contained separately in the micronucleus (MIC) and the m acronucleus (MAC). In an effort to advance fulfillment of Tetrahymena's pot ential as a genetic system, we are mapping both genomes and investigating t he correspondence between them. With the latter goal especially in mind, we report here a high-resolution meiotic linkage map of the It ft ar-m of chr omosome 1, one of Tetrahymena's five chromosomes. The map consists of 40 ma rkers, with all average spacing of 2.3 cM in the Haldane function and a tot al length of 88.6 cM. This study represents the first mapping of any large region of the Tetrahymena genome that has been done at this level of detail . Results of a parallel mapping effort in the macronucleus, and the corresp ondence between the two genomes, can be found in this issue as a companion to this article.