Jankun M, Martinez P, Pardo B G, Kirtiklis L, Rab P, Rabova M, Sanchez L
University WM in Olsztyn, Department of Evolutionary Ecology, 10-718 Olsztyn-Kortowo, Poland.
Heredity (Edinb). 2001 Dec;87(Pt 6):672-9. doi: 10.1046/j.1365-2540.2001.00964.x.
Major rDNA loci, i.e. nucleolus-organizing regions (NORs), were assigned using chromomycin-A3 (CMA3) staining followed by sequential silver (Ag) staining and in situ hybridization (ISH) with a rDNA probe to the chromosomes of the European whitefish (Coregonus lavaretus), the peled (Coregonus peled) and the vendace (Coregonus albula), three closely related coregonine salmonid fishes. One pair of NOR-bearing chromosomes was found in the peled karyotype. Multichromosomal, but stable, locations of rDNA sites on three pairs of chromosomes were observed in the European whitefish karyotype. Multichromosomal polymorphic locations, both in site and number, were observed in the karyotype of the vendace. Several Ag-, CMA3- and ISH-positive regions were found which defined up to seven cytotypes of five NOR-bearing chromosomes. All positive Ag-NORs detected corresponded both to rDNA-ISH- and CMA3-positive signals, which suggests extensive structural polymorphism in the locations of rDNA sites. Stable NOR sites were found at the same location on both homologous elements of the chromosome no. 9 in all individuals, while the remaining NORs were quite variable between individuals, and often present in heterozygous condition. The apparently similar and parallel evolutionary rDNA differentiation patterns in the subfamilies Coregoninae and Salmoninae (family Salmonidae) are observed and discussed.
利用嗜铬霉素A3（CMA3）染色，随后进行连续银（Ag）染色，并使用rDNA探针进行原位杂交（ISH），对欧洲白鲑（Coregonus lavaretus）、高白鲑（Coregonus peled）和湖拟鲤（Coregonus albula）这三种亲缘关系密切的白鲑亚科鲑科鱼类的染色体进行主要rDNA位点（即核仁组织区，NORs）定位。在高白鲑核型中发现了一对带有NOR的染色体。在欧洲白鲑核型中观察到rDNA位点在三对染色体上呈多染色体但稳定的定位。在湖拟鲤核型中观察到rDNA位点在位置和数量上均存在多染色体多态性定位。发现了几个Ag、CMA3和ISH阳性区域，它们定义了多达七种由五条带有NOR的染色体组成的细胞型。检测到的所有阳性Ag-NORs均与rDNA-ISH和CMA3阳性信号相对应，这表明rDNA位点的位置存在广泛的结构多态性。在所有个体的9号染色体的两条同源染色体上，稳定的NOR位点都位于相同位置，而其余的NORs在个体之间差异很大，并且常常以杂合状态存在。文中观察并讨论了白鲑亚科和鲑亚科（鲑科）中明显相似且平行的rDNA进化分化模式。
