Immunogenetic and Biochemical Studies of Neurospora Crassa

Abstract

In studies of antigenic diffs. between mating types a and A of strain 15300(albino-2), a brown or black pigment was observed in 15300a either in old cultures or in homogenates of whole mycelia which had been frozen and allowed to thaw. The pigment was identified as melanin by its absorption curve, which was a straight line between 470 and 600 m[mu]. A tyrosinase exhibiting both mono- and polyphenol oxidase activity and involved in melanin formation was present in 15300a and absent in 15300A. When equal volumes of 15300a supernate and 15300A supernate were mixed, the optical density of the mixture was significantly greater than that of the control mixture of 15300a supernate and buffer. Thus both mating types synthesized suitable substrate for enzyme activity, but 15300A was incapable of synthesizing an oxidizing enzyme. It is possible that the enzyme may be associated with small particles which are filtered out by the Seitz filter. The association of the enzyme diff. with mating type is in the process of genetic analysis.