𝔖 Bobbio Scriptorium
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Program 2000 Environmental Mutagen Society Annual Meeting April 8–April 13, 2000 New Orleans, LA. Jim Tucker, Program Chair

Publisher
John Wiley and Sons
Year
2000
Tongue
English
Weight
246 KB
Volume
35
Category
Article
ISSN
0893-6692

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✦ Synopsis

The phytoestrogen coumestrol (COUM) has been shown to induce DNA strand breaks, micronuclei and chromosomal aberrations in vitro but was negative in the Salmonella Ames assay. To further investigate the mechanism of COUM-induced chromosomal aberrations and micronuclei (MN), we treated cultured human lymphocytes with COUM using various treatment protocols. Following a 4, 6, or 24 hr treatment and a 24 hr recovery period in the presence of cytochalasin B without the test compound, a highly significant increase of micronuclei was seen between 50 and 100 µM COUM. The highest induction frequency with 200 MN per 1000 binucleated cells was found at 100 µM following a 6 hr treatment. Using the CREST-staining it was shown that the induced micronuclei were solely caused by chromosomal breakage. However, following a continuous 48 hr treatment, no induction of micronuclei could be detected, with COUM-concentrations between 50 and 100 µM being to toxic for evaluation. Using multicolor fluorescence in situ hybridization with tandem DNA probes, no induction of chromosomal breakage affecting the pericentric heterochromatin regions of chromosomes 1, 9, and 16 or hyperdiploidy was seen with the continuous treatment protocol. These results indicate that COUM is a potent inducer of chromosomal aberrations only at concentrations of 50 µM or higher and indicates the importance of treatment protocols for the evaluation of clastogenic agents.

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