Nucleolar organizer-associated region proteins

To circumvent the above limitations, the morphometric method can be used (Riischoff et al., 1990). It consists of automatic or semiquantitative measurement of the area occupied by the silver-stained structures within the nuclear profile with computer-assisted image analysis (Trerb et al., 1995). This method is faster, more accurate and reproducible, and shows less interobserver variation. Moreover, in contrast to the counting technique, the morphometric method is predictive of patient survival, independent of the clinical stage of the disease (Ofner et al., 1995a,b). 

The following procedure is more suitable for routine application than other methods as many as 200 specimens can be processed at a time with this procedure. Sections (2 pm thick) of formalin-fixed and paraffin-embedded tissues are mounted on silane-coated slides. They are deparaffmized with xylene and rehydrated in a series of descending concentrations of ethanol. The sections are immersed in 0.01 M sodium citrate buffer (pH 6.0) in plastic Coplin jars and heated in an autoclave at 120°C for 20min. After the sections have cooled down to room temperature for 20 min, they are incubated in the freshly prepared following silver staining solution for 25 min at room temperature. 

2% gelatin in 1% formic acid 1 part 25% aqueous silver nitrate 2 parts 

The sections are thoroughly rinsed in deionized water to remove unwanted silver precipitates, dehydrated in a series of ascending concentrations of ethanol, cleared in xylene, and 

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As is indicated in Fig. 28-15, transcription is thought to occur from the loops of DNA that form the nucleolar organizing region. The 100-kDa nucleolin, the major protein of the nucleolus, binds to the non-transcribed spacer sequences in the DNA.529-530 It also binds to the newly formed transcripts, as do various proteins that enter the nucleus from the cytoplasm.524531 More than 270 proteins, many of which participate in synthesis of ribosomes, have been detected in the nucleolus.5313 Some of these proteins, acting together with the snoRNAs discussed in the next section, catalyze hydrolytic cleavage of the pre-rRNA molecules. For completion of pre-ribosomal particles additional protein molecules enter the nucleolus and associate with the pre-rRNA particles, then diffuse out of the nucleus. 

Ofner, D., Bankfalvi, A., Riechemann, K., Bier, B., Bocker, W., and Schmid, K. W. 1994. Wet autoclave pretreatment improves the visualization of silver stained nucleolar organizer region associated proteins (AgNORs) in routinely formalin-fixed and paraffin-embedded tissues. Mod. Pathol. 2 946-950. 

Ofner, D., Bier, B., Heinrichs, S., Berghom, M., Dtinser, M., and Hagemann, H. E. 1996. Demonstration of silver-stained nucleolar organizer regions associated proteins (AgNORs) after wet autoclave pretreatment in breast carcinoma. Breast Cancer Res. Treat. 59 165-167. 

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