عنوان مقاله [English]
نویسندگان [English]چکیده [English]
Oil spills can result in the deposition of large quantities of petroleum hydrocarbons intointertidal and shallow waters seriously impacting bivalve populations. Petroleum hydrocarbonsare enriched in polycyclic aromatic hydrocarbons (PAHs) and PAH analogs many ofwhich may have potential chromosomal aberration. The micronuclei (MN) test is useful for assessing chromosomal aberration and DNA damage and has been used to a limited degree with aquatic organisms, but mostly with studies in vitro. This study carried out with the MN test to assess the DNA damaging potential of crude oil the complex mixtures of petroleum hydrocarbons for bivalves.Micronucleus test, one of the most popular and promisingtest ofenvironmental genotoxicity, has served as an index ofcytogenetic damagefor over 30 years. Micronuclei (MN) are produced from chromosome fragmentsor whole chromosomes that lag at cell division due to lack ofcentromere, damage in centromere or defect in cytokinesis. Intissues with actively dividing cells, micronuclei records reflectaction of clastogenic or aneugenic compoundsThis study presents the data on rate of MN numbers with use of micronuclei (MN) test in gill cells offreshwater bivalve molluscs (Anodonta cygnea) exposed to crude oil. Bivalves were exposed for ten days to 0.25, 0.5 and 1.0 ppm of crude oil. For the micronuclei (MN) test Two branches of mussel gills were placed in a big drop of 3:1 ethanol acetic acid (or methanol acetic acid) solution separately on two clean microscopic slides and gently nipped with tweezers for 2andndash;3 minutes (until cells spread within a drop). Then the cell suspension was softly smeared on the whole surface (except label place) of both slides. Dried slides were fixed in methanol for 10 min. and stained with 5% Giemsa solution in phosphate buffer pH = 6.8. The stained slides were analyzed under the light microscope at a final magnification of 1000andtimes;. a statically significant increase in level of micronuclei (MN) was found with 0.25, 0.5 and 1.0 ppm of crude oil. The rate of MN frequency was measured 1.6 , 2.6 and 2 MN/1000 gill cells, respectively. The frequency of micronuclei was varied from 0 to 2.6 andpermil; (MN/1000 cells).This study has demonstrated a potential for DNA damage in bivalvesexposedto crude oil as well as potential for interspecies sensitivity.