ULTRASTRUCTURAL-LOCALIZATION OF EPIDERMAL GROWTH-FACTOR (EGF)-RECEPTOR TRANSCRIPTS IN THE CELL-NUCLEUS USING PREEMBEDDING IN-SITU HYBRIDIZATION IN COMBINATION WITH ULTRA-SMALL GOLD PROBES AND SILVER ENHANCEMENT

A high-resolution in situ hybridization method is described for locali zing epidermal growth factor (EGF)-receptor transcripts in nuclei of A 431 epidermoid carcinoma cells. The method is based upon the use of ul tra-small gold particles in combination with silver enhancement. The R NA of the EGF-receptor was detected mainly around the nucleoli. After removal of the DNA using nucleases and high salt extraction, the RNA o f the EGF-receptor appears to be associated with the nuclear matrix. T he RNA of the EGF-receptor was observed in close contact with the SC-3 5 splicing protein, but no exact colocalization was observed. These re sults demonstrate that high resolution pre-embedding in situ hybridiza tion in combination with immunocytochemistry, both using ultra-small g old as a detection method, provides a powerful tool to unravel the org anization of nuclear processes.