Austerberry C F, Snyder R O, Yao M C
Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98104.
Nucleic Acids Res. 1989 Sep 25;17(18):7263-72. doi: 10.1093/nar/17.18.7263.
Regulated DNA deletions are known to occur to thousands of specific DNA segments in Tetrahymena during macronuclear development. In this study we determined the precision of this event by examining the junction sequences produced by three different deletions in many independent caryonidal lines. 0.9 kb deletions in region M produce at least 3 types of junction sequences, of which two have been determined and found to be different by 4 bp. The alternative 0.6 kb deletions in this region are much less variable. 1.1 kb deletions in region R, known from a previous study to be slightly variable, produce two types of junction sequences which are different from each other by 3 bp. Thus, developmentally regulated deletions in Tetrahymena can produce sequence microheterogeneity at their junctions. This process contributes significantly to the diversification of Tetrahymena's somatic genome.
已知在大核发育过程中，四膜虫体内数千个特定DNA片段会发生受调控的DNA缺失。在本研究中，我们通过检查许多独立细胞核系中三种不同缺失产生的连接序列，确定了这一事件的精确性。区域M中的0.9 kb缺失至少产生3种连接序列类型，其中两种已确定，发现相差4个碱基对。该区域另一种0.6 kb缺失的变异性要小得多。区域R中的1.1 kb缺失，根据先前研究已知其变异性较小，产生两种连接序列，彼此相差3个碱基对。因此，四膜虫发育过程中受调控的缺失在其连接处可产生序列微异质性。这一过程对四膜虫体细胞基因组的多样化有显著贡献。
