Maluszynska J, Schweizer D
Department of Cytology & Genetics, University of Vienna, Austria.
Heredity (Edinb). 1989 Feb;62 ( Pt 1):59-65. doi: 10.1038/hdy.1989.8.
A non-radioactive in situ hybridization method using biotin-labelled rDNA has made it possible to localize rRNA genes not only at the secondary constriction in both homologous chromosomes No. 3 of Crepis capillaris but also in the B chromosomes occurring in the plants employed. Very clear dot-like rDNA signals at the telomeres of both arms were observed in all B chromosomes. Histochemical silver staining, which is indicative of transcriptional activity of rRNA gene clusters, resulted in both darkly-staining nucleolar constrictions of chromosomes No. 3 and silver deposits at the telomeres of Bs. We conclude that the B chromosomes of C. capillaris are isochromosomes with active rRNA genes located near both telomeres.
一种使用生物素标记的rDNA的非放射性原位杂交方法，不仅能够将rRNA基因定位在毛茛（Crepis capillaris）同源3号染色体的次缢痕处，还能定位在所使用植物中出现的B染色体上。在所有B染色体的双臂端粒处均观察到非常清晰的点状rDNA信号。指示rRNA基因簇转录活性的组织化学银染，导致3号染色体的核仁缢痕深染以及B染色体端粒处有银沉积。我们得出结论，毛茛的B染色体是等臂染色体，其活性rRNA基因位于两个端粒附近。
