Selker E U, Garrett P W
Institute of Molecular Biology, University of Oregon, Eugene 97403.
Proc Natl Acad Sci U S A. 1988 Sep;85(18):6870-4. doi: 10.1073/pnas.85.18.6870.
Transforming sequences are faithfully replicated in vegetative cells of Neurospora but are typically subject at high frequency to sequence alterations and methylation in the period between fertilization and nuclear fusion. Previous work showed a correlation between the occurrence of these radical changes, referred to by the acronym RIP, and the presence of sequence duplications resulting from the introduced DNA. Various possible causes for the RIP process were investigated. Introduction of a single copy of a DNA fragment containing the Neurospora am gene into a strain having a deletion of this DNA did not lead to RIP, whereas introduction of two or more copies of the same fragment did. A conventional cross of strains having single copies of am at unlinked chromosomal locations was used to build a strain duplicated for am. Both copies of the duplicated gene were subject to the RIP process in crosses of this strain. We conclude that sequence duplications, per se, trigger RIP.
转化序列在粗糙脉孢菌的营养细胞中能被忠实地复制，但在受精和核融合之间的时期通常会高频地发生序列改变和甲基化。先前的研究表明，这些被简称为RIP的剧烈变化的发生与导入DNA产生的序列重复的存在之间存在关联。研究了RIP过程的各种可能原因。将含有粗糙脉孢菌am基因的单个DNA片段导入缺失该DNA的菌株中不会导致RIP，而导入该相同片段的两个或更多个拷贝则会导致RIP。使用在不连锁的染色体位置具有am单拷贝的菌株进行常规杂交，构建了一个am基因重复的菌株。在该菌株的杂交中，重复基因的两个拷贝都经历了RIP过程。我们得出结论，序列重复本身会触发RIP。
