Dawson D, Buckley B, Cartinhour S, Myers R, Herrick G
Chromosoma. 1984;90(4):289-94. doi: 10.1007/BF00287037.
The ciliated protozoa exhibit nuclear dimorphism. The genome of the somatic macronucleus arises from the germ-line genome of the micronucleus following conjugation. We have studied the fates of highly repetitious sequences in this process. Two cloned, tandemly repeated sequences from the micronucleus of Oxytricha fallax were used as probes in hybridizations to micronuclear and macronuclear DNA. The results of these experiments show: (1) the cloned repeats are members of two apparently unrelated repetitious sequence families, which each appear to comprise a few percent of the micronuclear genome, and (2) the amount of either family in the macronuclei from which our DNA was prepared is about 1/15 that found in an equal number of diploid micronuclei. Most, if not all, of the apparent macronuclear copies of these repeats can be accounted for by micronuclear contamination, which strongly suggests that these sequences are eliminated from the macronuclei and have no vegetative function.
纤毛原生动物表现出核二态性。在接合后，体细胞大核的基因组来源于小核的种系基因组。我们研究了这一过程中高度重复序列的命运。来自草履虫的两个克隆的串联重复序列用作与小核和大核DNA杂交的探针。这些实验结果表明：（1）克隆的重复序列是两个明显不相关的重复序列家族的成员，每个家族似乎占小核基因组的百分之几；（2）我们制备DNA的大核中任何一个家族的数量约为相同数量的二倍体小核中发现数量的1/15。这些重复序列的大多数（如果不是全部）明显的大核拷贝可以由小核污染来解释，这强烈表明这些序列从小核中被消除且没有营养功能。
