Inheritance of T Serotypes in Tetrahymena

PREVIOUS work on serotypes of Tetrahymena pyriformis, syngen 1, has shown that a single strain manifests different serotypes at different temperatures.Specifically, all strains have a different serotype at 15°C (the L type) from that at 25°C (the H type) (LOEFER, OWEN and CHRISTENSEN 1958).This paper is concerned with a third serotype, expressed at 40"C, which will be called the T serotype.Studies of the H serotype system have revealed four different H types distributed among the 11 different inbred families of T. pyriformis, syngen 1.These represent different alleles at a single genetic locus.Heterozygotes in this system are unstable in expression and during vegetative multiplication sublines differentiate so that some express one H allele, and others express the other H allele ( NANNEY and DUBERT 1960).Three different T phenotypes among the 11 inbred families can be distinguished with T specific antisera.This paper will examine the genetic basis of these traits and possible linkage relationships with the other known loci in Tetrahymena.Differentiation in T serotype heterozygotes during vegetative multiplication will be considered in the following paper. MATERIALS A N D METHODSThe strains used in this study were representatives of 11 inbred families of T .pyrformis, syngen 1.The allelic constitution of these families is given in Table 1.