Mitotic crossing-over induced by two commercial herbicides in diploid strains of the fungus Aspergillus nidulans.
Some herbicides are suspected of promoting teratogenic, carcinogenic and mutagenic events. Detection of induced mitotic crossing-over has proven to be an indirect way of testing the carcinogenic properties of suspicious substances, because mitotic crossing-over is involved in the multistep process of carcinogenesis. We examined mitotic crossing-over induced by two commercial herbicides (diuron and trifluralin) in diploid strains of Aspergillus nidulans based on the homozygotization index. Low doses (2.5 microg/mL) of diuron were sufficient to increase the mean homozygotization index in 2.1 and 11.3 times for UT448//UT196 and Dp II-I//UT196, respectively, whereas the same dose of trifluralin increased this mean only 1.2 (UT448//UT196) and 3.5 (Dp II-I//UT196) times, respectively. The lower homozygotization index value found for trifluralin could be due to its interference with mitotic crossing-over in eukaryotic cells. We concluded that the diploid Dp II-I//UT196 of A. nidulans is more sensitive to organic compounds than UT448//UT196; these compounds cause recombinational events at a greater frequency in the latter diploid. This system holds promise as an initial test for carcinogenicity of organic compounds, including herbicides.
Cardoso
R A
RA
Centro Universitário do Triângulo, Uberlândia, MG, Brasil.
Pires
L T A
LT
Zucchi
T D
TD
Zucchi
F D
FD
Zucchi
T M A D
TM
D001233:Aspergillus nidulans / Q000187:drug effects* / Q000235:genetics*; D003434:Crossing Over, Genetic / Q000187:drug effects*; D004171:Diploidy; D004237:Diuron / Q000633:toxicity; D008040:Genetic Linkage; D005838:Genotype; D006540:Herbicides / Q000633:toxicity*; D006720:Homozygote; D008938:Mitosis / Q000187:drug effects*; D014274:Trifluralin / Q000633:toxicity
D006540:Herbicides; D004237:Diuron; D014274:Trifluralin