Hutchison N, Pardue M L
Chromosoma. 1975 Nov 20;53(1):51-69. doi: 10.1007/BF00329390.
The metaphase chromosomes of Notophthalmus (Triturus) viridescens have been studied by C-banding and in situ hybridization. The chromosomes show the pericentric C-banding seen in many organisms and in addition have interstitial C-bands located a short distance from the pericentric C-bands on each chromosome arm. A few C-bands are seen in telomeric regions. Regions which hybridize in situ with 18S and 28S ribosomal RNA were found on three chromosome pairs. The animals studied fell into three groups with respect to which of the six possible sites showed detectable hybridization with 18S and 28S RNA. Individual animals differed not only in the pattern of in situ hybridization of ribosomal RNA but also in the number of ribosomal RNA cistrons in the genome as measured by saturation hybridization on purified DNA. In situ hybridization showed five pairs of chromosomes which contained DNA complementary to 5S RNA. The four pairs of subtelocentric chromosomes in the N. viridescens karyotype all have 5S DNA in the pericentric regions. The fifth cluster of 5S DNA is in the middle of one arm of the chromosomes in one of the two smallest submetacentric pairs in the genome. The five sites of 5S DNA differ markedly in the level of in situ hybridization with 5S cRNA.
利用C带和原位杂交技术对绿眼北美螈（Triturus）的中期染色体进行了研究。这些染色体呈现出许多生物中可见的着丝粒周围C带，此外，在每条染色体臂上距离着丝粒周围C带较短距离处还有居间C带。在端粒区域可见少数C带。在三对染色体上发现了与18S和28S核糖体RNA原位杂交的区域。就六个可能的位点中哪些显示出与18S和28S RNA的可检测杂交而言，所研究的动物分为三组。个体动物不仅在核糖体RNA的原位杂交模式上存在差异，而且通过对纯化DNA的饱和杂交测量，其基因组中核糖体RNA顺反子的数量也有所不同。原位杂交显示有五对染色体含有与5S RNA互补的DNA。绿眼北美螈核型中的四对亚端着丝粒染色体在着丝粒区域均含有5S DNA。5S DNA的第五个簇位于基因组中两个最小的亚中着丝粒对之一的一条染色体臂的中部。5S DNA的五个位点在与5S cRNA的原位杂交水平上有显著差异。
