A study of the mode of action of chemotherapeutic substances.

Rapid progress has been made in the last decade in the study of chemotherapy, “a subject concerning the properties and various interactions of drug, parasite and host,” (Mcllwain, 1944). In particular, many bacterial diseases which have so far failed to respond to immunization are now being more effectively treated with drugs which have only recently been recognized. The chemotherapeutic drugs include those prepared synthetically and the naturally occurring antibiotics produced by living organisms. [...] Several important physical factors, such as permeability, oxygen tension and oxidation-reduction potentials have been shown to influence the overall antibacterial effect and must therefore be considered in studying the mode of drug action on bacteria. An attempt has been made in this project to investigate some of the fundamental factors which influence the action of chemotherapeutic drugs on bacteria. The results obtained in vitro would seem to indicate that a more effective chemotherapeutic action could be expected by the utilization of two inhibitory drugs simultaneously, resulting in a potentiated or synergistic action which cannot be accounted for by the arithmetic sum of the drug action per se. Accordingly, this latter aspect of synergism between antibacterial substances has also been studied

Localization of yeast glucoamylase genes by PFGE and OFAGE

Chromosomes of two closely related yeast strains, the amylolytic Saccharomyces diastaticus and the non-amylolytic Saccharomyces cerevisiae, were resolved by pulsed field gel electrophoresis (PFGE) and orthological field alteration gel electrophoresis (OFAGE). Electrophoretic karyotypes of these two strains are identical. Sixteen cloned Saccharomyces genes of known chromosomal location were used to identify individual chromosomes by Southern hybridization analyses. The Southern blots were reprobed with a cloned fragment of the STA2 glucoamylase gene of S. diastaticus. STA2 exhibits homology to STA1 and STA3 as well as the sporulation-specific glucoamylase (SGA) gene from both Saccharomyces strains. The three unlinked, homologous genes, STA1 (DEX2, MAL5), STA2 (DEX1) and STA3 (DEX3) encoding the extracellular glucoamylase isozymes GAI, GAII and GAIII in S. diastaticus were then assigned to chromosomes IV, II and XIV, respectively. The SGA gene, encoding an intracellular glucoamylase in both S. diastaticus and S. cerevisiae, was assigned to chromosome IX. Electrophoretic mapping of the STA and SGA genes is at present the only way to localize these genes, since glucoamylase repressor gene(s) (STA10, INH1 and/or IST2) are present in most laboratory strains of S. cerevisiae and the SGA phenotype is only detectable during sporulation.5 page(s