HE fact that a posttreatment can abolish the mutations induced by a mutaTgenic agent can furnish a tool for the study of the metabolic conditions that are necessary for the completion of processes that begin with the mutagenic treatment and lead finally to mutation (WITKIN 1956; DOUDNEY and HAAS 1958, 1960). Different agents can produce a decrease in the mutation frequency after UV treatment: v...

We have studied the role of the pga1 gene of Penicillium chrysogenum, encoding the alpha subunit of a heterotrimeric G protein, in secondary metabolite production. The dominant activating pga1(G42R) mutation caused an increase in the production of the three secondary metabolites penicillin, the yellow pigment chrysogenin and the mycotoxin roquefortine, whereas the dominant inactivating pga1(G20...

The possibility of releasing gold nanoparticles (GNP) into the environment has been 9 rapidly increasing with the wide spread and flourishing application of gold nanoparticles (GNPs) 10 in a wide range of areas. Consequently, environmental effects of GNP, especially toxicities to 11 living organisms have drawn great attention. However, their toxicological characteristics still 12 remain unclear...

LEDERBERG, J. 1950 Isolation and characterization of biochemical mutants of bacteria. Methods in Med. Research, 3, 5-22. NEWCOMBE, H. B. 1953 The delayed appearance of radiationinduced genetic change in bacteria. Genetics, 38, 134151. NEWCOMBE, H. B. 1955 Mechanisms of mutation production in microorganisms. In BACQ, Z. M., AND ALEXANDER, P. Radiobiol. Symposium, Proc. Li6ge, 1954. PONTECORVO, G...