Reed K M, Phillips R B
Department of Biological Sciences, University of Wisconsin-Milwaukee 53201, USA.
Chromosome Res. 1997 Jun;5(4):221-7. doi: 10.1023/a:1018411417816.
Polymorphism of the nucleolus organizer region (NOR) on the putative sex chromosomes of Arctic char (Salvelinus alpinus) was examined using conventional cytogenetic and molecular techniques. Variation was observed in the number, size and position of rDNA loci on the sex pair. Fluorescence in situ hybridization (FISH) analyses showed that the sex chromosomes of Arctic char lack the repetitive DNA sequences (Mbol/BglII family) that are a prominent feature of the sex chromosomes of lake trout (S. namaycush). Southern analyses of genomic DNAs using an rDNA fragment as probe revealed extensive restriction fragment length polymorphism (RFLP) variation among individuals. Despite the presence of variation in all aspects of this rDNA locus, no sex-specific differences were detected. Repetitive DNAs (multicopy rDNA as in Arctic char or tandem repetitive DNA as in lake trout) appear to play important but different roles in the evolution of the sex chromosomes in these species.
利用传统细胞遗传学和分子技术，对北极红点鲑（Salvelinus alpinus）假定性染色体上的核仁组织区（NOR）多态性进行了研究。在性染色体对的rDNA位点数量、大小和位置上观察到了变异。荧光原位杂交（FISH）分析表明，北极红点鲑的性染色体缺乏重复DNA序列（Mbol/BglII家族），而这是湖红点鲑（S. namaycush）性染色体的一个显著特征。使用rDNA片段作为探针对基因组DNA进行Southern分析，揭示了个体间广泛的限制性片段长度多态性（RFLP）变异。尽管该rDNA位点的各个方面都存在变异，但未检测到性别特异性差异。重复DNA（如北极红点鲑中的多拷贝rDNA或湖红点鲑中的串联重复DNA）似乎在这些物种性染色体的进化中发挥着重要但不同的作用。
