Discrimination between micronuclei induced by spindle poisons and clastogens by using toad bone marrow polychromatic erythrocytes

Abstract

A proposal for discrimination between aneugens and clastogens by using bone marrow polychromatic erythrocytes (PCEs) of Bufo regularis was submitted. Two common aneugens (colchicine and vinblastine sulphate) and two common clastogens (cyclophosphamide and mitomycin C) were used. The micronuclei (MN) appeared as small spherical or oval bodies present inside MN-PCEs and obviously separated from the nucleus. The used chemicals induced high percentages of micronuclei with variable sizes, which clarify the sensitivity of bone marrow cells of Bufo regularis to genotoxic action of chemicals. Twenty-five MN-PCEs induced by each chemical were randomly selected, photomicrographed and measured by the ruler for subsequent analysis. The micronucleus relative length was calculated by dividing the nucleus length over micronucleus length of the same MN-PCE. According to calculations, the proposal stated that, the aneugens induced large micronuclei with relatively large micronuclei (> 20 % of nucleus length) and conversely, the clastogens induced relatively much smaller micronuclei (< 20 % of nucleus length). The results of this work pointed out: (1) the benefit of using of bone marrow micronucleus test in Bufo regularis for detecting genotoxic action of chemicals, (2) the availability of discrimination between micronuclei produced by spindle poisoning agents and those produced by chromosome breaking agents.


KEY WORDS: bone marrow polychromatic erythrocytes, , clastogens, micronuclei.


Egyptian Journal of Biology Vol.3(2) 2001: 48-55