期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1982
卷号：79
期号：10
页码：3255-3259
DOI：10.1073/pnas.79.10.3255
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：In the hypotrichous ciliate Oxytricha nova all of the macronuclear DNA is in the form of low molecular weight, gene-sized molecules with an average size of 2,200 base pairs. These molecules are produced during macronuclear development by excision from micronuclear chromosomes. All, or nearly all, of the small macronuclear DNA molecules possess an inverted terminal repeat sequence consisting of 5' C4A4 3' repeats. The hypothesis that this terminal sequence serves as a recognition signal for excision of gene-sized molecules from chromosomes has been tested. A sequence containing the C4A4 repeat has been isolated and used to screen clones of micronuclear DNA for the presence of the repeat sequence. The results show that the intact repeated C4A4 sequence is not present at the ends of macronuclear sequences as they exist in the micronuclear chromosomes. Therefore, the entire terminal repeat is not a recognition sequence for gene excision but must be added to the ends of gene-sized molecules during or after the excision process.
