Phillips R B, Zajicek K D, Utter F M
Can J Genet Cytol. 1986 Aug;28(4):502-10. doi: 10.1139/g86-074.
Chromosome banding patterns obtained by silver staining and chromomycin a3 (CMA3) staining were analyzed in six species of Oncorhynchus: O. tshawytscha, O. kisutch, O. keta, O. nerka, and O. gorbuscha from North America and O. masou from Japan. Four different chromosomal locations of the nucleolar organizer regions (NORs) were found in different species. In O. tshawytscha, O. kisutch, and O. masou the NORs comprised the entire short arms of one medium-sized acrocentric chromosome pair. In O. nerka the NORs were found in an interstitial band on the short arms of one submetacentric chromosome pair and in O. gorbuscha proximal to the centromere on one metacentric chromosome pair. In O. keta the NORs were found on the telomeres of one small submetacentric chromosome pair. As in the related genera Salmo and Salvelinus chromomycin A3 positive bands were found at the same sites as the AgNORs in all species. Salmonid fish are assumed to be ancestral tetraploids and the considerable differences in chromosome number between different species are thought to be the result of chromosomal fusions after tetraploidization. In all members of the genus Oncorhynchus the rearrangements have resulted in the consolidation of the NORs on a single chromosome pair. The possible significance of intra- and inter-species NOR polymorphisms is discussed.
对六种太平洋鲑属鱼类的染色体带型进行了分析，这些鱼类包括来自北美的大鳞大麻哈鱼、银大麻哈鱼、狗鲑、红大麻哈鱼和驼背大麻哈鱼，以及来自日本的马苏大麻哈鱼。通过银染和放线菌素A3（CMA3）染色获得染色体带型。在不同物种中发现了核仁组织区（NORs）的四个不同染色体位置。在大鳞大麻哈鱼、银大麻哈鱼和马苏大麻哈鱼中，NORs包含一对中等大小近端着丝粒染色体的整个短臂。在红大麻哈鱼中，NORs位于一对亚中着丝粒染色体短臂的中间带，在驼背大麻哈鱼中，NORs位于一对中着丝粒染色体的着丝粒近端。在狗鲑中，NORs位于一对小亚中着丝粒染色体的端粒上。与相关属的鲑鱼和红点鲑一样，在所有物种中，放线菌素A3阳性带都位于与AgNORs相同的位置。鲑科鱼类被认为是原始四倍体，不同物种之间染色体数目的显著差异被认为是四倍体化后染色体融合的结果。在太平洋鲑属的所有成员中，重排导致NORs在一对染色体上合并。讨论了种内和种间NOR多态性的可能意义。
