Assay systems for the study of gene function. 2 assay systems, the syntheses of RNA and protein, are described; their virtues and drawbacks are discussed.

The study of genetic regulatory mechanisms operating in plants and animals is of paramount importance in contemporary biology. A precise understanding of the mechanisms that underlie normal cellular differentiation is a prerequisite for understanding neoplastic transformation and genetic disease. At present, we are not aware of a single assay system that can give answers to all questions we are already able to pose. Studies of RNA synthesis are valuable because they provide a direct measurement of transcriptional activity. But these studies remain incomplete until we succeed in unraveling the metabolic roles of the molecules whose synthesis we study. In this respect, the study of enzyme synthesis represents a better defined assay system, although the interpretation of observed fluctuations in synthetic rates is made difficult by the many steps that intervene between the genes and their finished protein products. We propose that a combination of protein biosynthetic and cytogenetic analysis is a promising assay system for further investigation.