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Simplified ag-staining technique for nucleolar organizing regions and nucleoli

Hermione Elly Melara de Campos Bicudo; Lilian Madi-Ravazzi; Satiko Nanya

Departamento de Biologia, Instituto de Biociências, Letras e Ciências Exatas - UNESP, 15055 São José do Rio Preto, SP, Brasil

ABSTRACT

The Ag-staining technique now used for nucleolar organizing regions (NORs) and nucleoli was first described by Goodpasture and Bloom (1975) and Howell et al. (1975). NOR specificity to this type of staining was shown in nine mammal species previously submitted to in situ hybridization with ribosomic RNA (Goodpasture and Bloom, 1975). The use of Ag-staining rapidly became widespread, leading to a great accumulation of data on the morphological and physiological patterns presented by these structures in many organisms.
Several modifications of the Ag-staining technique have been developed since that time. Today the most commonly used is that of Howell and Black (1980). In this technique two solutions are used. One is prepared by completely dissolving one g of gelatin in 50 ml of deionized hot water and adding 0.5 ml of formic acid (solution A). The other is prepared by dissolving one g of silver nitrate in two ml of deionized water and filtering through filter paper (solution B). Both solutions are kept in dark bottles, wrapped in aluminum paper. For staining, two drops of solution B and one of solution A are dropped onto the prepared slides, covered with a coverslip and placed in an incubator or on a hot plate at 70°C for about eight minutes, after which the mixture turns a golden brown color.

Keywords: Staining technique; NOR; Nucleoli.

REFERENCES

Boquist, L.L.V. (1990). Nucleolar organizer regions in normal, hyperplastic and neoplastic parathyroid glands. Virchows Archiv A. Pathol. Anat. 417: 273-241.

Goodpasture, C. and Bloom, S.E. (1975). Visualization of nucleolar organizer regions in mammalian chromosomes using silver staining. Chromosoma 53: 37-50.

Howell, W.M., Denton, T. and Diamond, J.R. (1975). Differential staining of the sattelite regions of human acrocentric chromosomes. Experientia 31: 260-262.

Howell, W.M. and Black, D.A. (1980). Controlled silver-staining of nucleolus organizer regions with a protective colloidal developer: 1-step method. Experientia 36: 1014-15.