在四膜虫发育过程中，包含与大核端粒同源序列的内部微核DNA区域会被删除。

Internal micronuclear DNA regions which include sequences homologous to macronuclear telomeres are deleted during development in Tetrahymena.

作者信息

Yokoyama R, Yao M C

出版信息

Nucleic Acids Res. 1984 Aug 10;12(15):6103-16. doi: 10.1093/nar/12.15.6103.

DOI:10.1093/nar/12.15.6103

PMID:6473102

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC320060/

Abstract

C4A2 repeats are present in multiple clusters in both the macronucleus and micronucleus of Tetrahymena. Although the macronucleus is generated from the micronucleus after sexual conjugation, the repeats are telomeric sequences in the macronucleus but are internally located in the micronucleus (1). This study investigates the fate of the sequences adjacent to the micronuclear C4A2 repeats. Southern blot analyses of 21 C4A2-containing micronuclear clones show that extensive elimination of the adjacent sequences occurs during the formation of the macronucleus. Comparison of one C4A2-containing micronuclear clone with its derived macronuclear segment indicates that approximately 4.5 kb of DNA, which includes the C4A2 repeats and adjacent sequences on both sides is deleted from the macronucleus. The two regions adjoining the deletion are joined together to form a contiguous segment in the macronucleus. This excision of C4A2 repeats and surrounding sequences and the rejoining of the retained segments is probably the mechanism by which all or most of the other C4A2 adjacent sequences are eliminated.

摘要

C4A2重复序列存在于四膜虫大核和小核的多个簇中。尽管大核是在有性接合后由小核产生的，但这些重复序列在大核中是端粒序列，而在小核中位于内部（1）。本研究调查了与小核C4A2重复序列相邻的序列的命运。对21个含C4A2的小核克隆进行的Southern印迹分析表明，在大核形成过程中，相邻序列被大量消除。将一个含C4A2的小核克隆与其衍生的大核片段进行比较表明，大核中大约4.5 kb的DNA被删除，其中包括C4A2重复序列及其两侧的相邻序列。与缺失区域相邻的两个区域连接在一起，在大核中形成一个连续的片段。C4A2重复序列和周围序列的切除以及保留片段的重新连接可能是所有或大多数其他C4A2相邻序列被消除的机制。