title: Arrest of micronuclear DNA replication during genomic exclusion in Tetrahymena produces haploid strains.
abstract: Diploid cells of Tetrahymena thermophila were crossed to strain A*V, whose micronucleus is defective, to induce the unilateral transfer of gametic nuclei from the diploid cells to the A*V cells (round I of genomic exclusion). These haploid nuclei presumably undergo one endomitotic cycle and then become diploid with a G1 (2C) DNA content. However, further DNA replication from 2C to 4C was transiently arrested until the pairs separated. When endomitosis was blocked by treatment with cycloheximide during 6-8 hours of conjugation, the exconjugants of round I of genomic exclusion remained haploid. Competence for diploidization is apparently limited to some period of time after nuclear transfer. Blocking of diploidization during round I of genomic exclusion can be used as an efficient way to induce haploid strains in Tetrahymena.
authors.affiliation: Zoological Institute, University of Warsaw, Poland.
authors.forename: A
authors.initials: A
authors.lastname: Kaczanowski
authors.forename: I
authors.initials: I
authors.lastname: Gornicka
authors.forename: G
authors.initials: G
authors.lastname: Cleffmann
mesh_terms: D000818:Animals; D001345:Autoradiography; D002467:Cell Nucleus; D003227:Conjugation, Genetic; D003513:Cycloheximide / Q000494:pharmacology; D004261:DNA Replication; D004171:Diploidy; D005821:Genetic Techniques; D006238:Haploidy; D008957:Models, Genetic; D013768:Tetrahymena / Q000235:genetics*; D013997:Time Factors
chemical_list: D003513:Cycloheximide