Micronuclei and Nuclear Buds Induced by Cyclophosphamide in Crocodylus moreletii as Useful Biomarkers in Aquatic Environments.

Micronuclei (MN) are used to assess genotoxic exposure, whereas nuclear buds (NBs) have been linked to genotoxic events. Crocodylus moreletii was studied to identify MN and NBs. Three groups were formed: Group 1 (water) and groups 2 and 3 (7 or 10 mg/kg of cyclophosphamide). A drop of blood was obtained daily from the claw tip at 0 to 120 h. Spontaneous micronucleated erythrocytes (MNEs) and erythrocytes with nuclear buds (NBEs) were counted. The frequencies of micronucleated young erythrocytes (MNYEs) and NB young erythrocytes (NBYEs) were evaluated, including the ratio of young erythrocytes (YE)/1000 total erythrocytes. No significant differences were observed in the YE proportion on sampling days; group 1 did not show differences for any parameter, whereas group 2 showed significant differences in MNEs and NBEs, and group 3 showed differences in NBEs and NBYEs. Some mitotic activity in circulation was observed in YEs. In conclusion, NBEs could be a more sensitive biomarker to genotoxic damage than MNEs. The identification of these biomarkers leads us to propose Crocodylus moreletii as a possible environment bioindicator because these parameters could be useful to analyze the in vivo health status of these reptiles and for biomonitoring genotoxic pollutants in their habitats.

[Felines: an alternative in genetic toxicology studies?]. / Los felinos: Una alternativa en estudios de toxicología genética?

The micronuclei (MN) test carry out in peripheral blood is fast, simple, economic and it is used to detect genotoxic environmental agents. MN are fragments of chromosomes or complete chromosomes remaining in the cytoplasm after cell division, which increase when organisms are exposed to genotoxic agents. Therefore, species with the highest values of spontaneous micronucleated erythrocytes (MNE) are the most suitable to be potentials biomonitor of micronucleogenic agents, using a drop of blood. Nine species of Felines that present spontaneous MNE in peripheral blood are shown. From these species, the cat has been previously proven, with positive results and also lion (Panthera leo), yaguaroundi (Felis yagoaroundi), lynx (Lynx ruffus), jaguar (Panthera onca), puma (Puma concolor), tiger (Panthera tigris), ocelote (Felis padalis) and leopard (Panthera pardus) display spontaneous MNE, and with this characteristic this Family can be propose like a potential group to be used in toxicogenetic studies.

Nuclear abnormalities in erythrocytes of parrots (Aratinga canicularis) related to genotoxic damage.

Nuclear abnormalities in erythrocytes, as micronuclei and nuclear buds (BE), are considered potential biomarkers of genotoxic exposure. We described previously the frequency of spontaneous micronucleated erythrocytes (MNE) in the species Aratinga canicularis. Here, we have used this species to evaluate the induction of MNE and BE by mitomycin-C. Animals were given a single intracoelomic injection of 0, 2, 3 or 4 mg/kg mitomycin-C on two consecutive days. A drop of blood was obtained after 0, 24, 48 and 72 h, and stained smears were used to count micronucleated polychromatic erythrocytes (MNPCE) and polychromatic erythrocytes with buds (BPCE)/1000 polychromatic erythrocytes. The number of MNE and BE in 10 000 total erythrocytes was also counted. MNPCE and BPCE frequencies were elevated at 24, 48, and 72 h after the administration of the lower dose (P<0.03). At a 3 mg/kg dose, the frequency of MNPCE increased at 48 and 72 h (P<0.04) whereas the number of BPCE increased, but not significantly. Administration of 4 mg/kg mitomycin-C increased the number of MNE observed at 72 h (P<0.03), the number of MNPCE at 48 h (P<0.01) and 72 h (P<0.006), the BE frequency at 72 h (P<0.05), and the frequency of BPCE at 48 and 72 h (P<0.001). While mitomycin-C appears to produce a parallel increase in MNPCE and BPCE frequencies, the MNE seemed to be a more sensitive indicator of genotoxicity than the BE. This suggests that evaluating BE and MNE in routine haematological analysis should be considered to evaluate environmental genotoxic exposure.

Los felinos: ¿Una alternativa en estudios de toxicología genética?

Felines: an alternative in genetic toxicology studies? The micronuclei (MN) test carry out in peripheral blood is fast, simple, economic and it is used to detect genotoxic environmental agents. MN are fragments of chromosomes or complete chromosomes remaining in the cytoplasm after cell division, which increase when organisms are exposed to genotoxic agents. Therefore, species with the highest values of spontaneous micronucleated erythrocytes (MNE) are the most suitable to be potentials biomonitor of micronucleogenic agents, using a drop of blood. Nine species of Felines that present spontaneous MNE in peripheral blood are shown. From these species, the cat has been previously proven, with positive results and also lion (Panthera leo), yaguaroundi (Felis yagoaroundi), lynx (Lynx ruffus), jaguar (Panthera onca), puma (Puma concolor), tiger (Panthera tigris), ocelote (Felis padalis) and leopard (Panthera pardus) display spontaneous MNE, and with this characteristic this Family can be propose like a potential group to be used in toxicogenetic studies. Rev. Biol. Trop. 56 (2): 969-974. Epub 2008 June 30.

La prueba de micronúcleos (MN) en sangre periférica es rápida, sencilla, económica y sirve para detectar genotóxicos ambientales. Los MN son fragmentos de cromosomas o cromosomas completos que por alguna causa quedan fuera del núcleo en mitosis, pero que incrementan significativamente cuando los organismos que los presentan de manera espontánea se exponen a genotóxicos. Por lo tanto, el requisito para que una especie pueda ser utilizada para esta prueba es que presente eritrocitos micronucleados espontáneos (EMNe), con lo que estas especies pueden ser potenciales bioindicadores de genotóxicos micronucleogénicos, con sólo una gota de su sangre. En el presente articulo es mostramos 9 especies de felinos que como característica general presentan EMNe. Del total de especies de felinos, el gato ha sido previamente probado, con resultados positivos y ya que también el león, yaguaroundi, lince, jaguar, puma, tigre de bengala, ocelote y leopardo presentan EMNe, esta familia puede ser propuesta como un grupo potencialmente adecuado para estudios de toxicogenética. En otras palabras, cada una de estas especies puede llegar a ser un modelo potencial para determinar exposición a genotóxicos en nuestro entorno, de una manera sencilla y rápida.