Karrer Kathleen M
Department of Biological Sciences, Marquette University, Milwaukee, Wisconsin, USA.
Methods Cell Biol. 2012;109:29-52. doi: 10.1016/B978-0-12-385967-9.00003-7.
Nuclear dualism is a characteristic feature of the ciliated protozoa. Tetrahymena have two different nuclei in each cell. The larger, polyploid, somatic macronucleus (MAC) is the site of transcriptional activity in the vegetatively growing cell. The smaller, diploid micronucleus (MIC) is transcriptionally inactive in vegetative cells, but is transcriptionally active in mating cells and responsible for the genetic continuity during sexual reproduction. Although the MICs and MACs develop from mitotic products of a common progenitor and reside in a common cytoplasm, they are different from one another in almost every respect.
核二元性是纤毛原生动物的一个特征。四膜虫每个细胞中有两个不同的细胞核。较大的多倍体体细胞核（MAC）是营养生长细胞中转录活性的位点。较小的二倍体微核（MIC）在营养细胞中无转录活性，但在交配细胞中有转录活性，并在有性生殖过程中负责遗传连续性。虽然微核和体细胞核由共同祖细胞的有丝分裂产物发育而来，并存在于共同的细胞质中，但它们在几乎每个方面都彼此不同。
