Abstract: A cell-free system has been developed based on Xenopus egg extracts that induced the morphological transformations characteristic of apoptosis in isolated nuclei. Purified nuclei from mouse liverceels are induced into apoptosis in this apoptotic cell-free system. Two best characterized hallmarks of apoptosis:formation of apoptotic bodies and DNA fragmentation into nucleosomal fragments were observed. In attempts to characterize and identify the nuclease associated with apoptosis, that a Mg²⁺-dependent, Ca²⁺-independent, Zn²⁺-inhibitable nuclease was examined in induced apoptotic extract and a 27 kD protein was found to be a possible candidate by SDS-PAGE-DNA assay.

Key words: Xenopus laevis, cell-free system, dATP, apoptosis, nuclease, SDS-PAGE-DNA

摘要： 通过向正常爪蟾卵提取物S-150中加入dATP和细胞色素c，得到能有效诱导外源细胞核凋亡的非细胞体系。温育在上述非细胞体系中的小鼠肝细胞核表现出明显的凋亡特征。细胞核的绝大部分染色质DNA凝集并排出，只在核膜边缘残留一些DNA成分，而温育体系中充满高度凝集的凋亡小体。这种凋亡小体产生的过程以往工作未见描述。同时,小鼠肝细胞核在卵提取物中发生的形态变化伴随着染色质DNA被降解成DNA ladder。进一步研究发现，卵提取物经dATP与细胞色素c诱导后，表现出凋亡相关的核酸酶活性，并确认该核酸酶为一27kD的蛋白。研究表明，利用爪蟾卵提取物研究细胞核凋亡是一个很好的实验模式。

关键词: 非洲爪蟾, 卵非细胞体系, dATP, 细胞凋亡, 核酸酶, SDS-PAGE-DNA