ANALYSIS OF TRANSCRIPTIONAL REGULATORY REGIONS IN-VIVO

Understanding the transcriptional regulation of development and tissue -specific gene expression is a central goal of modern biology. Althoug h the analysis of gene transcription in transfected cultured cells has been essential in establishing many key aspects of this gene control, only analysis in animals can determine developmental timing and cell- specificity of expression within a complex organ and in all the tissue s of an animal. The advent of transgenesis made in vivo studies possib le. A summary of the in vivo regulatory properties of the pancreas-spe cific transcriptional enhancer of the rat elastase 1 gene (ELA1) and t he role individual elements in this enhancer play in directing high le vel, cell-specific transcription illustrates the nature, revelations a nd limitations of transgenic analysis.