Ja. Ferreiro et al., IS THE WHITE-IVORY ASSAY OF DROSOPHILA-MELANOGASTER A USEFUL TOOL IN GENETIC TOXICOLOGY, Environmental and molecular mutagenesis, 29(4), 1997, pp. 406-417
The white-ivory assay of Drosophila is based on the detection of rever
sions to wild-type phenotype of ommatidia with the white-ivory mutatio
n. A tandem quadruplication of this gene is used in order to increase
the reversion probability. Although the exact mechanism implicated in
reversion is not known, revertant spots are believed to arise as a con
sequence of intrachromosomal recombination or related phenomena. Since
the white-ivory assay has not been broadly used, the number of chemic
als tested until now is still limited. In this work, we have essayed 2
5 chemicals belonging to several chemical groups, i.e., crosslinking a
gents, DNA-topoisomerase inhibitors, ant; metabolites/nucleotide pool
inhibitors, cyclic-adduct inducers, halogenated hydrocarbons, bulky-ad
duct inducers, intercalating agents, oxidative damage inducers, and a
multiple damage inducer, to validate this test. Cross-linking agents,
halogenated hydrocarbons, and the multiple damage inducer, daunomycin,
were positive. On the contrary, the three antimetabolites/nucleotide
pool inhibitors tested were negative. The other chemical groups showed
disparate results, since some chemicals were positive, whereas others
were negative in each group. A comparison with the results obtained i
n the w/w(+) and mwh/flr(3) assays shows that the w(i) assay detects a
more restricted spectrum of damages than those, although, with respec
t to carcinogenicity, its sensitivity (0.76, with the 62 chemicals tes
ted until now) is similar to that estimated for the mentioned somatic
assays. The conclusion of this work, then, is that the w(i) assay is n
ot recommended as a general screening test, because the background rev
ersion frequencies show a high variability among solvents, the range o
f lesion-recognition is lower than in the w/w(+) and mwh/flr(3) SMARTs
, and the mechanism implicated in the white-ivory reversion is poorly
understood. (C) 1997 Wiley-Liss, Inc.