Induction of micronuclei in cultured mammalian cells by fume condensates of roofing asphalt.
Qian-W; Ong-T; Whong-Z
Am J Ind Med 1996 May; 29(5):554-559
Induction of micronuclei by fume condensates of roofing asphalt was studied in vitro. Chinese-hamster lung fibroblasts (V79 cells) were incubated with up to 250 micrograms per milliliter (microg/ml) of fume condensates of type-I or type-III roofing asphalt for 24 hours (hr). The condensates were generated at 316 degrees-C. Some cells were treated with 1microg/ml N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) as a positive control. After 24hr exposure, the cells were scored for micronuclei. Both types of condensates caused dose related increases in the frequency of micronucleated cells. The increase in micronuclei frequency appeared to plateau at 187.5microg/ml after either treatment. MNNG also induced a high frequency of micronucleated. Additional V79 cells were treated with 185microg/ml of the type-I or type-III fume condensates for 24hr. Changes in the expression of immunofluorescent staining of kinetochore were determined to investigate a possible mechanism for micronuclei formation using human antikinetochore primary antibodies and fluoresceinated goat antihuman immunoglobulin-G. Vincristine- sulfate at 0.01microg/ml and mitomycin-C (MMC) at 0.04microg/ml were used as positive controls. kinetochore positive (KC+) micronuclei were carried by 67.5% of the cells exposed to the type-I condensate and 69.7% of those exposed to type-III condensate. The frequency of KC+ micronucleated cells was similar to that (68.2%) induced by vincristine-sulfate. The frequency of KC+ micronuclei induced by MMC was 18.2%. The authors conclude that type-I and type-III roofing asphalt fume condensates showed aneuploidic and clastogenic activity. Since both condensates induced KC+ micronuclei to the same extent as vincristine-sulfate, a compound known to interfere with microtubule assembly by binding to free tubulin, the aneuploidic activity of the two condensates may involve blockage of spindle assembly through an interaction with tubulin.
NIOSH-Author; Genotoxic-effects; Asphalt-fumes; Dose-response; In-vitro-studies; Mammalian-cells; Immunochemistry; Cell-cultures
American Journal of Industrial Medicine