Conjugation between unimicronuclear doublets and singlets, and several features of the clones originating from hemikarya of Euplotes woodruffi syngen 1 (ciliophora)

Abstract

Conjugation of a unimicronuclear doublet with two singlets produced three kinds of exconjugants: an exconjugant singlet cell, with a macronucleus and a micronucleus, originating from a synkaryon (diploid); an exconjugant singlet with a micronucleus and a macronucleus from a hemikaryon (haploid); and an exconjugant doublet consisting of two components, one side bearing a micronucleus and a macronucleus derived from a hemikaryon and the other side with those from a synkaryon. Of the two exconjugant singlets, one died in 64% of all cases and both singlets survived and formed clones in 20% of the cases. Using mainly the latter, the length of the immaturity period and fission rates were compared between diploid and haploid clones. Diploid clones were the same as the control clones in the morphology of their nuclear apparatus. Haploid clones showed faintly stained small micronuclei; They sometimes produced amicronucleates. Exconjugants which were considered to be diploids showed an immaturity period of over 40 fissions and fission rates of over 1.43, while those considered to be haploids often produced clones with short immaturity periods, short clonal life, and low fission rates. The F 1 singlets with short immaturity, when crossed to normal diploids, produced F 2 clones with lower viability and shorter immaturity than those produced by crosses between two normal diploids.