ALLELIC STRAINS OF Neurospora LACKING TRYPTOPHAN SYNTHETASE: A PRELIMINARY IMMUNOCHEMICAL CHARACTERIZATION

The action of genetic material and its relation to enzyme biosynthesis has only in recent years received attention from an experimental standpoint. A variety of enzyme changes has been found to be associated with genetic alterations, including the formation of altered enzymes, the modifications in various quantitative aspects of enzyme formation, and the complete loss of ability to form specific enzymes (see review' ). The first two categories have received some attention in previous investigations. The last category, which might be the most informative, has received scant attention in the past, largely because the lack of enzyme activity severely limits a direct experimental approach. However, the absence of detectable enzyme activity need not abolish all hope of examining such a condition. Even if the ability to form a specific enzyme were lost, there might remain the synthesis of proteins antigenically similar to that enzyme, and the presence of these could be investigated by immunochemical methods. This approach has recently been employed in studies of the f-galactosidase system of Escherichia coli2 and of the tyrosinase of Glomerella.3 The present paper is a preliminary report on the application of immunochemical techniques to problems of gene action and of the control of tryptophan synthetase formation in Neurospora crassa. This enzyme was selected for study because a series of well-characterized alleles affecting its formation was available,4' 5 as well as detailed information about the enzyme itself.6' 7, 8 Materials and Methods.-The various tryptophan independent (T+) and tryptophan requiring (T-) strains of N. crassa used in this work are listed in Table 1.