title: A cytogenetic study of development in mechanically disrupted pairs of Tetrahymena thermophila.
abstract: We examined the nuclear behavior of mating Tetrahymena cells that had been mechanically disrupted at various times throughout conjugation. Disruption was achieved by agitating conjugating Tetrahymena in the presence of 0.1-3 mm glass beads. Two minutes of agitation with 1 mm beads yielded optimal pair disruption (70%) with high viability (92%). Disrupting pairs between 0-4.7 h after the initiation of mating produced mostly disrupted conjugants in which development was aborted. However, as many as 20% of these early disrupted conjugants completed development even without their mating partners. After 5 h the percentage of disrupted conjugants completing development increased dramatically, reaching 80% by 6.7 h. These results support a model suggesting that events associated with nuclear exchange and fusion 5 h into conjugation trigger a commitment to completion of the postzygotic developmental program. The early conjugants that completed development following disruption suggest that development can be sustained even in the absence of a mating partner. This represents a novel method of bringing the micronuclear genome into macronuclear expression with minimal cytoplasmic exchange between partners. We discuss these results in light of a model relating cortical and nuclear signaling events that reciprocally drive conjugal development.
authors.affiliation: Biology Department, St. Olaf College, Northfield, Minnesota 55057, USA.
authors.forename: M A
authors.initials: MA
authors.lastname: Virtue
authors.forename: E S
authors.initials: ES
authors.lastname: Cole
mesh_terms: D000818:Animals; D018503:Genome, Protozoan; D016808:Tetrahymena thermophila / Q000235:genetics* / Q000254:growth & development; D013997:Time Factors