Murine transfer factor. I. Description of the model and evidence for specificity

A model for studying transfer of delayed-type sensitivity to mice with cellfree materials is described. The results with a particulate antigen (Candida) and 4 soluble protein antigens (PPD, ferritin, cytochrome c, and horseradish peroxidase) suggest that the phenomenon is antigen specific. Identical preparations from the spleens of insensitive donors were not active. This murine model should facilitate characterization of the immunologic and chemical properties of transfer factor.     

Serological study of yeast killer toxins by monoclonal antibodies

Yeast killer toxins coded by determined and undetermined killer plasmids or presumptive nuclear gene(s) in various genera (Saccharomyces, Kluyveromyces, Pichia and Candida) have been serologically investigated by a monoclonal antibody (KT4), produced against the yeast killer toxin of Pichia (Hansenula) anomala UCSC 25F. Double immunodiffusion with the killer toxins as antigens and indirect immunofluorescence on whole cells of the corresponding killer yeast have been used. In both the serological procedures, monoclonal antibody KT4 proved to be reacting only with the killer toxins and the whole cells of yeasts belonging to the genus Pichia.     

Crown gall transformation of tobacco callus cells by cocultivation with Agrobacterium tumefaciens

Incubation of cells from squashed tobacco callus tissue with virulent Agrobacterium tumefaciens leads to the production of cells displaying a crown gall phenotype.     

Genomic studies on killer yeasts belonging to the genusPichia

Twenty-four species belonging to the genusPichia were investigated using restriction fragment length polymorphism (RFLP) and Southern blot hybridization of their genomic DNA.Saccharomyces cerevisiae, Kluyveromyces lactis, Williopsis mrakii andCandida albicans were also included in this study. The RFLP patterns were obtained from digestion of yeast DNA with several restriction endonuclease enzymes, and showed various bands with different mobility; in most isolates, the more deeply stained bands were species-specific. This observation was confirmed by the results obtained from Southern blot hybridization of theEcoRI andXhoI RFLP patterns withP. anomala UCSC 25F DNA, digested with the same enzymes, used as probes. These bands are likely to be ribosomal DNA as shown by hybridization of digested DNA from unrelated yeast species (S. cerevisiae, K. lactis andC. albicans). However, one hybridized band, located at 3.9–4.1 Kb, seems to be peculiar to thePichia species. Our study confirms the usefulness of molecular tools in studying genetic relatedness among yeasts.