The length of secondary chromosomal constrictions in normal individuals and in a nucleolar mutant of Xenopus laevis.
The length of secondary chromosomal constrictions in normal individuals and in a nucleolar mutant of Xenopus laevis.
复制标题
正常个体和非洲爪蟾核仁突变体中次级染色体缢缩的长度。
DOI：
10.1159/000130054
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发表时间：
1969
期刊：
影响因子：
--
通讯作者：
R. Sherwin
中科院分区：
文献类型：
--
作者：
K. A. Rafferty;R. Sherwin
次级染色体收缩被认为是编码核糖体 RNA 合成的基因组基因座。它们的中期长度可能取决于核仁大小或间期功能活性水平或基因内容。研究人员对野生型青蛙和牛津核仁突变杂合的青蛙进行了研究，以确定哪种可能性更大。对这种突变体进行研究是因为它的单个核仁比野生型核仁大，它只有一个缢缩，核糖体基因数量只有野生型的一半，但产生相同数量的核糖体RNA。结果表明（1）缢缩长度取决于基因组的数量（而其他人已经表明核仁大小与活性水平相关）和（2）删除仅限于缢缩片段，支持缢缩是核仁组织者的观点。此外，中期缢缩比根据其 DNA 含量预期的要长。
Secondary chromosomal constrictions are thought to be the loci of the genome which code for ribosomal RNA synthesis. Their metaphase length could depend on nucleolar size or level of functional activity in interphase or on gene content. Wild-type frogs and a frog heterozygous for the Oxford nucleolar mutation were studied to determine which possibility is more probable. The mutant was studied because its single nucleolus is larger than wild-type nucleoli, it has only one constriction, half as many ribosomal genes, but produces the same amount of ribosomal RNA. The results indicate (1) that constriction length depends on the amount of genome (whereas others have shown nucleolar size to be related to level of activity) and (2) that the deletion is limited to the constricted segment, supporting the view that the constriction is the nucleolar organizer. Also, metaphase constrictions are longer than expected from their DNA content.