Spontaneous and radiation-induced micronuclei in erythrocytes from four species of wild rodents: a comparison with CBA mice.
Almost 100 animals of 4 different species of small wild rodents (bank vole, Clethrionomys glareolus; field vole, Microtus agrestis; yellow-necked mouse, Apodemus flavicollis; and wood mouse, Apodemus sylvaticus) were trapped in central Sweden and used in experiments to determine the spontaneous and radiation-induced frequencies of polychromatic (fMPCE) and normochromatic erythrocytes (fMNCE) from bone marrow (bm) and peripheral blood (pb) using flow cytometric analysis. The results were compared with those from similar experiments with CBA mice. The saving of time and labour by the use of the flow cytometer-based analysis was a prerequisite for this study in which about 135 million PCE were analysed. The two species of voles had a mean background fMPCE (bm) of about the same value as CBA mice, while the yellow-necked mice had about five times higher fMPCE (bm). Wood mice had more than twice the fMPCE (bm) compared to CBA mice. Between individual animals in each of the 4 species, the background fMPCE (bm) varied more than between individual CBA mice, and the elimination of micronucleated erythrocytes was considerable. When exposed to ionizing radiation, the voles did not show a significant response. The response of the two Apodemus species was similar to that of the CBA mice, although it varied between individual animals and was not correlated to their background fMPCE. This study indicates that bank voles and field voles are unsuitable testing objects in the in vivo micronucleus assay. On the other hand, yellow-necked mice and wood mice seem to be useful in this test. Since the variation between individuals is considerable in wild Apodemus mice, large groups will be needed for obtaining statistically significant results when exposure to a genotoxic agent is low. Alternatively, repeated samples can be taken from individual wild mice to study the effect of a decreased exposure after keeping the animals for a period of time in an uncontaminated environment.
Abramsson-Zetterberg
L
L
Department of Genetics, Uppsala University, Sweden. GENLAZ@STRIX.ITS.UU.SE
Grawé
J
J
Zetterberg
G
G
D000818:Animals; D000835:Animals, Wild / Q000097:blood / Q000235:genetics*; D003411:Arvicolinae / Q000097:blood / Q000235:genetics*; D001853:Bone Marrow / Q000528:radiation effects / Q000648:ultrastructure; D004784:Environmental Monitoring; D004912:Erythrocytes / Q000528:radiation effects* / Q000648:ultrastructure*; D005434:Flow Cytometry; D005720:Gamma Rays; D051379:Mice; D008808:Mice, Inbred CBA; D048629:Micronuclei, Chromosome-Defective / Q000528:radiation effects*; D015162:Micronucleus Tests / Q000379:methods*; D009115:Muridae / Q000097:blood / Q000235:genetics*; D013045:Species Specificity; D014965:X-Rays