Efficacy of HUMN criteria for scoring the micronucleus assay in human lymphocytes exposed to a low concentration of p,p'-DDT

Abstract

The cytokinesis-block micronucleus (CBMN) assay is one of the standard cytogenetic tools employed to assess chromosomal damage subsequent to exposure to genotoxic/cytotoxic agents, and is widely applicable to plant, animal and human cells. In the present study, the CBMN assay was used to assess the baseline damage in binuclear human peripheral blood lymphocytes exposed to 25 µg/L p,p'-DDT for 1, 2, 24, and 48 h by measuring the frequency of micronuclei, nucleoplasmic bridges and nuclear buds. These new scoring criteria facilitated the detection of different types of clastogenic and aneugenic effects induced by this type of pollutant. With these criteria, CBMN can also be used to measure nucleoplasmic bridges which are considered to be consequences of chromosome rearrangements and nuclear buds which are biomarkers of altered gene amplification and gene dosage. The total number of micronuclei observed in binuclear human peripheral blood lymphocytes of the exposed samples (ranging from 32 to 47) was significantly greater (P < 0.05) than that detected in the unexposed (0 time) control sample, where the total number of micronuclei was 7. The number of nucleoplasmic bridges and nuclear buds obtained after 24 and 48 h was also significantly (P < 0.05) greater in the samples treated with p,p'-DDT than in the unexposed control samples. Thus, our results confirmed the usefulness of the new criteria applicable for the CBMN assay employed in measuring the DNA damage and its role of a sensitive cytogenetic biomarker.

Evaluation of the Cytogenetic Status of Human Lymphocytes After Exposure to a High Concentration of Bee Venom In Vitro

“…Current evidence suggests that nucleoplasmic bridges derive from dicentric chromosomes in which the centromeres have been pulled to the opposite poles of the cell during the anaphase stage, and are therefore indicative of the DNA mis-repair, chromosome rearrangement, or telomere end-fusion. Nuclear buds arise from the elimination of amplifi ed DNA and possibly from the elimination of DNA repair complexes, and can therefore serve as markers of gene amplifi cation and altered gene dosage (29,(38)(39)(40). Our alkaline comet assay showed that bee venom had a great impact on DNA stability, which was indicated by a statistically signifi cant, time-dependent increase in all comet parameters.…”

In Utero Pesticides Exposure and Generation of Acute Myeloid Leukemia Associated Translocation (8; 21)

“…Malathion and DDT are well known genotoxic substances both on acute and chronic exposure in different cell lineages including cells of hematological origin as human T-lymphocytes. 22,23 The genotoxic effects, including chromatid breakdown and increased the frequency of breakpoint formation, are noted at low concentration that did not even confer cytotoxicity; [22][23][24][25][26][27] this explains the apparent healthy mothers and babies in our cohort. The absence of variation between t (8; 21) carriers and non-carriers regarding maternal and fetal variables (rather than being a rural resident) indicated direct association between exposure to theses pesticides and generation of the translocation.…”

Presence of Dichlorodiphenyltrichloroethane (DDT) in Croatia and Evaluation of Its Genotoxicity

“…It is a reliable method for measuring chromosomal instability and altered cellular viability (Fenech, 2009;Fenech et al, 2003). It includes micronuclei, which are biomarkers of chromosome breakage and whole chromosome loss, nucleoplasmic bridges, which are biomarkers of DNA misrepair and telomere end-fusions, and nuclear buds, which are biomarkers of elimination of amplified DNA and DNA repair complexes (Fenech, 2007;Garaj-Vrhovac et al, 2008). Considering the lack of data on the effect of DDT on the cellular genome, and taking into account its usage in some countries of the Third World and its environmental persistence, the aim of this study was to evaluate the genotoxic potential of a low concentration of aqueous p,p'-DDT upon in vitro exposure of HPBLs of different duration, by using alkaline comet assay and CBMN assay.…”

“…Current evidence suggests that NPBs derive from dicentric chromosomes which the centromeres have been pulled to the opposite poles of the cell during the anaphase stage, and are therefore indicative of the DNA mis-repair, chromosome rearrangement or telomere end-fusion. According to the new criteria applicable to the CBMN assay, NBUDs arise from the elimination of the amplified DNA and possibly from the elimination of the DNA-repair complexes, which therefore, may be considered a marker of gene amplification and altered gene dosage (Fenech, 2006;Fenech & Crott, 2002;Fenech et al, 2011;Garaj-Vrhovac et al, 2008;Lindberg et al, 2006;Thomas et al, 2003). The significance of the CBMN assay lies in the fact that every cell in the system studied is scored cytologically for its viability status (necrosis, apoptosis), its mitotic status (mononucleated, metaphase, anaphase, binucleated, multinucleated) and its chromosomal instability or damage status (presence of MNi, NPBs, NBUDs and number of centromere probe signals amongst nuclei of binucleated cell if such molecular tools are used in combination with the assay).…”

“…The significance of the CBMN assay lies in the fact that every cell in the system studied is scored cytologically for its viability status (necrosis, apoptosis), its mitotic status (mononucleated, metaphase, anaphase, binucleated, multinucleated) and its chromosomal instability or damage status (presence of MNi, NPBs, NBUDs and number of centromere probe signals amongst nuclei of binucleated cell if such molecular tools are used in combination with the assay). In this respect, the micronucleus assay has evolved into a comprehensive method employed in measuring chromosomal instability of the phenotype and altered cell viability and represents an effective tool to be used in research of cellular www.intechopen.com and nuclear dysfunctions caused by in vitro or in vivo exposure to toxic substances (Fenech, 2006;Garaj-Vrhovac et al, 2008;. …”