Chromosomal localization and heterochromatin association of ribosomal RNA gene loci and silver-stained nucleolar organizer regions in salmonid fishes
Chromosomal localization and heterochromatin association of ribosomal RNA gene loci and silver-stained nucleolar organizer regions in salmonid fishes
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DOI：
10.1023/a:1009200428369
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发表时间：
1998-09-01
影响因子：
2.6
通讯作者：
Yoshida, MC
中科院分区：
文献类型：
--
作者：
Fujiwara, A;Abe, S;Yoshida, MC
利用荧光原位杂交技术（FISH）对虹鳟（Oncorhynchus mykiss）、大麻哈鱼（O. masou）、溪鳟（Salvelinus fontinalis）和日本哲罗鱼（Hucho perryi）。在这些物种中，次要的rDNA位点基本上位于2 - 4对染色体上，而主要的rDNA位点基本上被发现在一个染色体对上，除了溪鳟。其主要的rDNA位点分布在约一半的染色体上，在数量和位置上表现出相当大的个体间变异。主要和次要的rDNA位点被分离到不同的染色体上的研究物种，除了虹鳟鱼，其中一个染色体对串联排列的次要和主要的rDNA位点。在每个物种的染色体区域，发现含有这两种rDNA位点的染色与C-显带，显示这些位点与异染色质的协会。分配的主要rDNA位点和顺序检测的银（Ag）染色核仁组成区（AgNORs）在所有物种的比较显示了相当大的多态性的数量和大小的AgNORs之间或在这些位点内，这表明可能的主要rDNA之间或intralocus失活。
Ribosomal RNA gene (rDNA) loci, including those of nucleolus-forming 18S, 5.8S and 28S (major) and non-nucleolus-forming 5S (minor) rDNA, were assigned using fluorescence in situ hybridization (FISH) to the embryonic chromosomes of rainbow trout (Oncorhynchus mykiss), masu salmon (O. masou), brook trout (Salvelinus fontinalis) and Japanese huchen (Hucho perryi). In these species, the minor rDNA loci were located basically on 2-4 chromosome pairs, whereas the major rDNA loci were found essentially on one chromosome pair, except for the brook trout. Its major rDNA loci were dispersed on about half of the chromosome complement, showing a considerable interindividual variation in the number and location. The major and minor rDNA loci were separated onto different chromosomes in the examined species, except for the rainbow trout, in which one chromosome pair had tandemly aligned minor and major rDNA loci. Chromosome regions containing both kinds of rDNA loci in each species were found to be stained with C-banding, showing an association of these loci with heterochromatin. Comparison of the assigned major rDNA loci and sequentially detected silver (Ag)-stained nucleolar organizer regions (AgNORs) in all the species revealed a considerable polymorphism in the number and size of AgNORs among or within those loci, suggesting a possible inter- or intralocus inactivation of the major rDNAs.