Recent advances in molecular histochemical techniques: in situ hybridization and southwestern histochemistry.

Over the past decade, considerable efforts to understand the states of specific gene expression at cellular and/or subcellular levels have been made. For this particular purpose, nonradioactive in situ hybridization to localize mRNAs has been developed and improved substantially, and it is now recognized as a powerful, established light-microscopical technique. In this review, we focus on the recent advances in the technological aspects of nonradioactive in situ hybridization including the use of synthetic oligodeoxynucleotide probes, the progress in analysis of signals, and the application to electron microscopy. Also, southwestern histochemistry, a relatively new method of localizing transcription regulatory proteins by utilizing haptenized DNA with responsive element sequences is described. Then we discuss what we can see by combining these molecular histochemical methods which were brought about by the merger of molecular biology and structural biology.