50 BIOCHEMICAL SYSTEMATICS 



ing with the antibodies to normal tryptophan synthetase, and it was 

 discovered that certain td mutants did contain serologically active 

 though enzymatically inactive material. This presumably represented 

 an altered protein, formed in the presence of the mutant. It was 

 sufficiently close to the normal enzyme to behave as a similar antigen, 

 but the protein had not retained its catalytic property. Furthermore, 

 the td mutant could elicit antitryptophan synthetase when injected 

 into rabbits. If the inferences drawn from these studies are correct, 

 classical genetics will be served at least to the extent of an elegant ex- 

 periment suggesting indirectly the idea of mutation as a change, not 

 a loss. Suskind and other workers are primarily interested in the 

 study of an allelic series as applied to questions of intragenic structure. 

 Adams (1942) and Markert and Owens (1954) have prepared antisera 

 against a tyrosinase preparation from the fungi, Psalliota campestris 

 and Glomerella, respectively. Antiserum for the tyrosinase of Psalliota 

 was inactive against tyrosinase from a related genus, Lactarius pi- 

 paratus, and antiserum for the tyrosinase of Glomerella was inactive 

 against tyrosinase preparations from Neurospora, Psalliota, Tenebrio, 

 and the vascular plant genus, Solanum. Therefore, the same enzyme 

 from different species, by serological criteria, may be somewhat differ- 

 ent. Novel applications of such serological methods are theoretically 

 possible, though perhaps impractical at this time. For example. Bird- 

 song, Alston, and Turner (1960), noting the absence of canavanine in 

 seeds of certain species in a genus in which canavanine occurs, suggest 

 that interspecific crosses of canavanine-less forms might yield a 

 canavanine-producing hybrid, disclosing latent pathways in much the 

 same way that complementary mutants in Neurospora are indicative 

 of metabolic blocks affecting different steps. But what if the species 

 are incompatible or even compatible but yield a canavanine-less 

 hybrid? Serological tests of the type described above might be applied 

 to disclose an enzymatically inert, but related protein. This result 

 would imply that canavanine synthesis was a lost property, and such 

 information would have definite taxonomic value. 



Even now, it is apparent that the disclosure of homologous 

 genes by serological tests is becoming feasible (Nisselbaum, et al., 

 1961). Stimpfling and Irwin (1960a) have recently reported a study 

 of gene homologies in species of the Columbidae (including doves and 

 pigeons). Through extensive previous genetic and serological inves- 

 tigations, it has been possible to demonstrate in these species a series 

 of species-specific antigens which segregate in backcross generations 

 as simple Mendelian characters. If one thus produces an antiserum 

 and adsorbs with appropriate mixtures of test sera, it is possible to 

 produce a single-antibody-containing antiserum which can then be 



