Macgregor H, Sherwood S
Chromosoma. 1979 May 10;72(3):271-80. doi: 10.1007/BF00331089.
The main clusters of ribosomal genes, or nucleolus organizers, have been located by in situ nucleic acid hybridization of Xenopus laevis 3H labelled ribosomal RNA to mitotic chromosomes in squash preparations of intestinal epithelium from 7 species of Plethodon and 3 species of Aneides. The species used were chosen on account of having well known karyotypes and genome sizes. The Plethodon species covered a range of genome size of 20--69.4 pg. The locations of those nucleolus organizers that could be detected by autoradiography after in situ hybridization varied from species to species, and in Aneides there were differences between two populations of the same species. On the other hand, some distantly related species of Plethodon, with widely different genome sizes, had nucleolus organizers at corresponding positions. The results are discussed in relation to ideas on karyotype stability, homosequentiality and chromosome repatterning.
通过将非洲爪蟾3H标记的核糖体RNA与7种东美螈属和3种拟髭蟾属物种的肠上皮压片制备中的有丝分裂染色体进行原位核酸杂交，确定了核糖体基因的主要簇，即核仁组织区。所使用的物种是因其具有已知的核型和基因组大小而被挑选出来的。东美螈属物种的基因组大小范围为20 - 69.4皮克。原位杂交后通过放射自显影可检测到的那些核仁组织区的位置因物种而异，并且在拟髭蟾属中，同一物种的两个种群之间也存在差异。另一方面，一些亲缘关系较远、基因组大小差异很大的东美螈属物种，其核仁组织区位于相应位置。结合核型稳定性、同序列性和染色体重新模式化的观点对结果进行了讨论。
