1-Nitropyrene efficiently induces mitotic recombination in Saccharomyces cerevisiae.
Nitropyrene, a mutagenic and carcinogenic component of diesel exhaust, has been shown to be a potent bacterial and mammalian mutagen. There is, however, some controversy regarding the genotoxic effects of 1-nitropyrene towards yeast. To obtain insights into the mechanisms of 1-nitropyrene-induced mutations in Saccharomyces cerevisiae, we have attempted to characterize the genetic alterations that inactivate the endogenous CAN1 gene either in haploid cells or in heterozygous diploid cells. 1-Nitropyrene, without any activation treatment, showed a substantial toxic effect until 500 microM. The mutation frequency in haploid cells treated with 500 microM of 1-nitropyrene was 1.59 x 10(-5), which is 15-fold higher than the control value. Sequencing of mutants indicated that both frameshifts and base substitutions were increased. In diploid cells treated with 500 microM of 1-nitropyrene, the frequency with which can1Delta::LEU2/can1Delta::LEU2 was converted from CAN1/can1Delta::LEU2, a phenotypic change from a canavanine-sensitive to canavanine-resistant form, was 8.59 x 10(-4), which is 9.15-fold higher than the spontaneous level. More than 99% of the 1-nitropyrene-induced mutations in canavanine-resistant diploid cells constituted a gene conversion or crossover. Chromosome loss was not increased after treatment with 1-nitropyrene. These results suggest that 1-nitropyrene is an agent that efficiently induces point mutations, gene conversion, and crossover, but not chromosome loss, in S. cerevisiae.
Rhenimi
Lalla Rajaa
LR
Graduate School of Life Sciences, Tohoku University, Sendai, Japan.
Abu-Nasr
Naglaa Fathi
NF
Yamamoto
Kazuo
K
D050256:Antimitotic Agents / Q000008:administration & dosage*; D004305:Dose-Response Relationship, Drug; D008938:Mitosis / Q000187:drug effects / Q000235:genetics*; D009153:Mutagens / Q000008:administration & dosage*; D011721:Pyrenes / Q000008:administration & dosage*; D011995:Recombination, Genetic / Q000235:genetics* / Q000528:radiation effects; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000235:genetics*
D050256:Antimitotic Agents; D009153:Mutagens; D011721:Pyrenes; C032668:1-nitropyrene