Transcribed and nontranscribed parts of the human ribosomal gene repeat show a similar pattern of distribution in nucleoli

Abstract

The distribution pattern of the transcribed and nontranscribed parts of human ribosomal RNA genes were visualized simultaneously in the same cells by nonautoradiographic in situ hybridization. DNA probes labeled with either digoxigenin or biotin were detected in the same cells by different fluorescence systems. The signals from both the transcribed and nontranscribed parts showed a similar distribution pattern. This finding is not compatible with the conclusion, suggested by earlier studies, that the transcribed and nontranscribed parts of the rRNA genes are located at different sites within the nucleoli or in different nucleolar components.

Arrangement of ribosomal genes in nucleolar domains revealed by detection of "Christmas tree" components

“…8a, b), our data suggest that transcript elongation is associated with the hypotony-sensitive parts of the DF. This view is further corroborated when comparing the rDNA sequence distribution in isotonically embedded cells as published earlier (PuvionDutilleul et al 1991;Schöfer et al 1996;Wachtler et al 1991) and the current data on hypotonically pretreated nucleoli. Some authors described 3′ rDNA signal also within the FCs (Puvion-Dutilleul et al 1991;Thiry and Goessens 1992).…”

“…The 3′ part sequences and hence the elongation of the transcript occurs in a different region. The data obtained in this study together with previously published data on rDNA location in normal (isotonic) cells Wachtler et al 1991) let us conclude that a major part of the actively transcribed rDNA gene is located in the hypotonically dispersable part of the DF. Our finding that some part of the 5′ probe associates with the surface of FCs (i.e.…”

Ribosomal transcription units integrated via T‐DNA transformation associate with the nucleolus and do not require upstream repeat sequences for activity in Arabidopsis thaliana

“…The probes were labelled with biotin or digoxigenin by nick translation. For detection of HPT II DNA, the slides were treated as described by Wachtler et al (1991). Briefly, preparation involves incubation with RNase A and subsequent digestion of the sections with proteinase K for 20 min and dehydration through a graded series of ethanol.…”

Where no RNA polymerase has gone before

“…Early work posited that this region either played a structural role within the nucleolus allowing for the formation of tightly packed nucleolar organizing regions 18 or provided some form of genomic stabilization through the attachment of specific sequences to the nuclear matrix. 19 Evolutionarily, the IGS appears to have increased in size over time, measuring only 2.5 kb in yeasts, 5.1 kb in Drosophilia melanogaster, 5.7 kb in Xenopus laevis, while the chickens, mouse and primate sequences are all Figure 1. Synthesis of rrNA from the ribosomal cassette.…”