title: Extruded micronuclei induced by colchicine or acrylamide contain mostly lagging chromosomes identified in paintbrush smears by minor and major mouse DNA probes.
abstract: In the mouse bone marrow micronucleus assay, it was studied whether micronuclei (MN) could be expelled from polychromatic erythrocytes (PCE) in a similar way to the main nucleus. To avoid the disrupting centrifugation step of the conventional bone marrow preparation procedure, the paintbrush technique was used in the present experiments. With May-Grunwald-Giemsa staining of paintbrush slides, 5 % of the colchicine (COL)-induced MN were found attached to the outside membranes of PCE and were regarded as extruded. Of the acrylamide (AA)-induced MN, 22% were extruded. After fluorescence in situ hybridization (FISH) of a total of 300 MN per chemical treatment with the mouse minor and major satellite DNA probes, 9.7% MN were extruded in the COL group and 8.3% MN were extruded in the AA group. FISH showed that 76% of the retained COL-induced MN were signal-positive, indicating that they contained entire chromosomes. With AA, 29% minor-positive and 28.3 % major-positive retained MN were found, confirming its known clastogenicity. However, the observed frequency of signal-positive MN (1.7 MNPCE(pos)/ 1000 PCE) in the AA group was about three times higher than in the control (0.5 MNPCE(pos)/1000 PCE) which indicates that AA has aneugenic potential. FISH analysis of the extruded MN showed 72-100% major as well as minor signals. It is concluded that expelled MN contain mostly entire chromosomes.
authors.affiliation: Ludwigs-Maximillians-Universität München, Tierärzliche Fakultät, Lehrstuhl für Allgemeine Pathologie und Neuropathologie, Germany.
authors.forename: G
authors.initials: G
authors.lastname: Schriever-Schwemmer
authors.forename: U
authors.initials: U
authors.lastname: Kliesch
authors.forename: I D
authors.initials: ID
authors.lastname: Adler
mesh_terms: D020106:Acrylamide; D000178:Acrylamides / Q000633:toxicity*; D000818:Animals; D003078:Colchicine / Q000633:toxicity*; D015342:DNA Probes; D004912:Erythrocytes / Q000187:drug effects; D005821:Genetic Techniques; D017404:In Situ Hybridization, Fluorescence / Q000379:methods; D008297:Male; D051379:Mice; D008809:Mice, Inbred C3H; D008815:Mice, Inbred Strains; D048629:Micronuclei, Chromosome-Defective / Q000187:drug effects*; D015162:Micronucleus Tests / Q000379:methods*; D013194:Staining and Labeling / Q000379:methods
chemical_list: D000178:Acrylamides; D015342:DNA Probes; D020106:Acrylamide; D003078:Colchicine