(redirected from micronuclear)
Also found in: Dictionary, Medical.


(invertebrate zoology)
The smaller, reproductive nucleus in multinucleate protozoans.



in infusorians, the smaller (generative) nucleus. The micronucleus is usually diploid and divides by mitosis; however, during the sexual process in infusorians (conjugation), it divides meiotically and gives rise to sexual nuclei or pronuclei. During the vegetative period, the genetic apparatus of the micronucleus remains inactive, does not synthesize ribonucleic acid, and has no influence on the phenotype of the organism.

References in periodicals archive ?
nova, the micronuclear copy of the genes for Actin I, [Alpha]-telomere binding protein, and DNA polymerase a must be reordered, and the intervening DNA sequences removed, to construct functional macronuclear genes.
Then, when the cell is synthesizing new DNA in preparation for division, the double minute chromosomes replicate and may be enveloped by micronuclear membranes that bud out of the nuclear membrane.
JPL even has an "inside out" micronuclear magnetic resonance instrument, one that inserts itself in the ground and performs NMR analysis on soil samples.