Nullisomic tetrahymena: eliminating germinal chromosomes.

Germinal and somatic functions in Tetrahymena are performed separately by the micro- and macronuclei, respectively. Cells with haploid micronuclei were mated with diploids to yield monosomic progeny. These were induced to undergo a form of self-fertilization, generating cells lacking both copies of one or more of the five chromosomes in the micronucleus while still possessing a complete macronuclear genome.