Coenzyme-dependent alcohol dehydrogenases in Candida guilliermondii Y4

Candida guilliermondii Y4 is capable of synthesizing two different alcohol dehydrogenases. ADH1 is constitutive on different carbon sources under shaking or settling conditions and its activity is prominent on gel electrophoresis. ADH2 is only synthesized under shaking condition. Two types of mutants were isolated using an allyl alcohol selection technique. ADH1-deficient mutants had 2.7% ADH activity of the wild type, while ADH2-deficient mutants had an ADH activity as high as that of the wild-type ADH activity. The alcohol dehydrogenases of the mutants differ from those of the wild type in their relative oxidation rates of alcohols. ADH1 appears to possess a functional role mainly in the production of ethanol from acetaldehyde, while ADH2 functions mainly in the oxidation of ethanol to acetaldehyde. However, both enzymes seem to be capable of carrying out the reverse reactions, since mutants lacking either of them still grew satisfactorily on different carbon sources. Key words: Candida guilliermondii, alcohol dehydrogenase, ADH1-deficient mutant, ADH2-deficient mutant.

Radiation-induced alcohol dehydrogenase mutants in maize following allyl alcohol selection of pollen

SUMMARYThe alcohol dehydrogenase-1 gene in maize presents advantages for mutational analysis. Foremost among these is the ability to chemically select ADH-negative and ADH-low gametophytes owing to their resistance to allyl alcohol vapour. Immature tassels were irradiated with either 220 kV X-rays or 400 MeV/amu accelerated neon-ions; spontaneous mutants were also selected and recovered. RBE for neon-20 was about 5. A total of 70 presumptive mutants were placed into one of four classes on the basis of allozyme profiles following electrophoresis and ADH staining: (A) dysfunction, (B) underproducer, (C) overproducer, and (D) up-Adh2 gene. Mutants have been recovered and confirmed in the first three classes. These include two male-transmissible deletion-type lesions induced by X-rays, five underproducer transpositions and one overproducer transposition induced by neon-20. Certain of the neoninduced alleles are unstable in their expression. All 70 mutants are chromosomal aberrations; no intragenic lesions were recovered although our experimental design would have preferentially recovered them if they had occurred.The Discussion considers the mutagenic action of ionizing radiation, and especially the well-documented differences between maize and Drosophila data. In particular, the effect of these chromosome derangements on the ‘programmable’ component(s) of the Adhl cistron is discussed.