Madireddi M T, Coyne R S, Smothers J F, Mickey K M, Yao M C, Allis C D
Department of Biology, University of Rochester, New York 14627, USA.
Cell. 1996 Oct 4;87(1):75-84. doi: 10.1016/s0092-8674(00)81324-0.
During Tetrahymena conjugation, programmed DNA degradation occurs in two separate nuclei. Thousands of germline-specific deletion elements are removed from the genome of the developing somatic macronucleus, and the old parental macronucleus is degraded by an apoptotic mechanism. An abundant polypeptide, Pdd1p (formerly p65), localizes to both of these nuclei at the time of DNA degradation. Here we report that, in developing macronuclei, Pdd1p localizes to electron-dense, heterochromatic structures that contain germline-specific deletion elements. Pdd1p also associates with parental macronuclei during terminal stages of apoptosis. Sequencing of the PDD1 gene reveals it to be a member of the chromodomain family, suggesting a molecular link between heterochromatin assembly and programmed DNA degradation.
在四膜虫接合过程中，程序性DNA降解发生在两个独立的细胞核中。数千个生殖系特异性缺失元件从发育中的体大核基因组中被去除，而旧的亲代大核则通过凋亡机制被降解。一种丰富的多肽Pdd1p（以前称为p65）在DNA降解时定位于这两个细胞核。我们在此报告，在发育中的大核中，Pdd1p定位于富含电子的异染色质结构，这些结构包含生殖系特异性缺失元件。在凋亡末期，Pdd1p也与亲代大核相关联。PDD1基因测序显示它是色域家族的成员，这表明异染色质组装与程序性DNA降解之间存在分子联系。
