Liu Ting, Song Menghuan, Xia Yun, Zeng Xiaomao
Department of Herpetology, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, PR China.
Cytogenet Genome Res. 2017;151(3):161-170. doi: 10.1159/000464128. Epub 2017 Mar 24.
In an attempt to extend the knowledge of the 5S rDNA organization in anurans, the 5S rDNA sequences of Amolops mantzorum were isolated, characterized, and mapped by FISH. Two forms of 5S rDNA, type I (209 bp) and type II (about 870 bp), were found in specimens investigated from various populations. Both of them contained a 118-bp coding sequence, readily differentiated by their non-transcribed spacer (NTS) sizes and compositions. Four probes (the 5S rDNA coding sequences, the type I NTS, the type II NTS, and the entire type II 5S rDNA sequences) were respectively labeled with TAMRA or digoxigenin to hybridize with mitotic chromosomes for samples of all localities. It turned out that all probes showed the same signals that appeared in every centromeric region and in the telomeric regions of chromosome 5, without differences within or between populations. Obviously, both type I and type II of the 5S rDNA arrays arranged in tandem, which was contrasting with other frogs or fishes recorded to date. More interestingly, all the probes detected centromeric regions in all karyotypes, suggesting the presence of a satellite DNA family derived from 5S rDNA.
为了拓展对无尾两栖类5S核糖体DNA（rDNA）组织的认识，我们分离、鉴定了滇南湍蛙的5S rDNA序列，并通过荧光原位杂交（FISH）进行定位。在来自不同种群的标本中发现了两种形式的5S rDNA，即I型（209 bp）和II型（约870 bp）。它们都包含一个118 bp的编码序列，很容易通过其非转录间隔区（NTS）的大小和组成来区分。分别用四甲基罗丹明（TAMRA）或地高辛标记了四个探针（5S rDNA编码序列、I型NTS、II型NTS和整个II型5S rDNA序列），用于与所有产地样本的有丝分裂染色体杂交。结果发现，所有探针在第5号染色体的每个着丝粒区域和端粒区域都显示出相同的信号，种群内部和种群之间没有差异。显然，I型和II型5S rDNA阵列都是串联排列的，这与迄今记录的其他蛙类或鱼类形成对比。更有趣的是，所有探针在所有核型中都检测到了着丝粒区域，这表明存在一个源自5S rDNA的卫星DNA家族。
