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In this study, the mutagenic and recombinogenic effects of indole-3-acetic acid (IAA), a plant growth regulator naturally synthesized in plants but produced synthetically, and β-naphthoxyacetic acid (BNOA), a synthetic plant growth regulator widely used in agricultural regions, were investigated using the somatic mutation and recombination test (SMART) in Drosophila wings. The effect of the same plant growth regulators against the proliferation and viability of a human immortalized embryonic kidney HEK293 cells which is at the early stage of carcinogenesis were also examined with MTT and trypan-blue exclusion assays. For the SMART assay, two different crosses were used: a standard and a high-bioactivation (HB) cross, involving the flare-3 and the multiple wing hairs markers. The HB cross involved flies characterized by an increased cytochrome P-450-dependent bioactivation capacity, which permits the more efficient biotransformation of promutagens and procarcinogens. In both crosses, the wings of the two types of progeny, inversion-free marker heterozygotes and balancer heterozygotes, were analyzed. The results show that IAA and BNOA are not mutagenic or recombinogenic in the wing cells of Drosophila. Furthermore, neither plant growth regulator affected the proliferation rate of HEK293 cells; however, both of them induced cell death at high concentrations. [ABSTRACT FROM PUBLISHER]

Purpose: The aim of this study was to assess the adaptive response induced by low doses of ultraviolet-B (UVB, 290-320 nm) radiation in the Drosophila wing spot test. Materials and methods: The adaptive response of Drosophila larvae to UVB light was studied by using a somatic mutation and recombination test (SMART). The SMART system used was the wing spot test, which uses morphological markers of the wing blade. This in vivo test has shown to be very useful to study the induction of genetic damage in somatic cells, measuring loss of heterozygosity (LOH) resulting from gene mutation, mitotic recombination, chromosomal rearrangements or chromosome loss. Results: To determine the induction of adaptive response, two-day-old Drosophila larvae were first irritated with an adaptive dose (58.3 J/m2), followed by different challenge doses (178, 224, 288, 338, and 386 J/m2). When the results obtained in the different challenge doses were compared with those obtained following the application of adaptive plus challenge doses, significant decreases (74.7-80.8%) in a first experiment, and (65.6-78.4%) in a second experiment, were observed in the frequency of mutant spots on the wing blades. Conclusions: Our results show that in Drosophila the adaptive response can be stimulated in vivo by UVB exposure. [ABSTRACT FROM AUTHOR]

In the present study, the herbicides bentazone, molinate, thiobencarb and trifluralin were evaluated for mutagenic and recombinagenic effects using the wing spot test of Drosophila melanogaster (somatic mutation and recombination test, SMART). Both standard (ST) and high-bioactivation (HB) fly crosses were used, the latter cross is characterised by a high sensitivity to promutagens and procarcinogens. Three-day-old larvae, transheterozygous for the multiple wing hairs (mwh, 3–0.3) and flare-3 (flr3, 3–38.8) genes, were chronically fed with six different concentrations of each herbicide. Feeding ended with pupation of the surviving larvae and the genetic changes induced in somatic cells of the wing’s imaginal discs lead to the formation of mutant clones on the wing blade. Point mutation, chromosome breakage and mitotic recombination produce single spots; while twin spots are produced only by mitotic recombination. Bentazone, usually considered as a non-mutagen, gave positive results in the wing spot test with the high-bioactivation cross. Molinate, about which information on mutagenic effects is inconclusive, gave positive responses in both the standard and the high-bioactivation crosses, while the other thiocarbamate, thiobencarb, gave positive results only in the standard cross and at the highest concentration tested (10 mM). Finally, trifluralin, one of the most widely studied herbicides for genotoxic effects, gave positive results in the wing spot test with both crosses. Apart from the interest of the results found in the genotoxic evaluation of the four selected herbicides, our results also contribute to extend the existing database on the Drosophila wing spot test, and corroborate the utility of the use of high-bioactivation strains for the genotoxic evaluation of xenobiotics. [Copyright &y& Elsevier]