Variation of micronucleated erythrocytes in peripheral blood of Sciurus aureogaster in relation to age: an increment of micronucleated polychromatic erythrocytes after the administration of colchicine.

In some species, in which the human is included, the influence of age in the variation in the number of micronucleated erythrocytes (MNE) is known. In the present work we show how the process of aging influences the number of spontaneous MNE in the gray squirrel (Sciurus aureogaster). Because of the difficulty of knowing the age of each animal, 69 animals were weighed at their arrival to the laboratory and at the start of sample taking, with the supposition that the heaviest animals were the oldest and those with the lightest weight were the youngest. The major number of MNE was found in the younger animals, whereas the adults displayed less MNE (P < 0.0001). A group of 11 animals were sampled every 15 days over a period of 6 months, and the number of MNE were found to decrease with an increment in the weight in conformity with the time elapsed. These results showed that in the gray squirrel, the number of spontaneous MNE in peripheral blood depend on age. An additional interesting datum about the increment of MNE after the administration of colchicine is shown.

Evaluation of genotoxic activity of maleic hydrazide, ethyl methane sulfonate, and N-nitroso diethylamine in Tradescantia.

OBJECTIVE: To assess the genotoxic activity of N-nitroso diethylamine (NDEA), maleic hydrazide (MH), and ethyl methane sulfonate (EMS) using two systems: the comet assay on nuclei from Tradescantia, and the pink mutation test on Tradescantia staminal hairs (clone 4430). MATERIAL AND METHODS: Tradescantia cups was obtained from Laboratorio de Citogenética y Mutagénesis del Centro de Ciencias de la Atmósfera de la Universidad Nacional Autónoma de México and treated with: N-nitroso diethylamine (NDEA) at 1, 5, 10 mM, maleic hydrazide (MH) at 1, 5, 10 mM and ethyl methane sulfonate (EMS) at 15, 30 and 45 mM; and used in both pink mutation assay and comet assay using cellular nuclei from Tradescantia staminal hairs. The observation of staminal hair was realized along eight days (6-14) after treatment), flowers produced day 14 after treatment were utilized done according to Underbrink. In previous reports on plants, were comet assay was used, breaking cellular wall and separating by centrifugation gradient are necessary. Here, nuclei from staminal hairs were obtained by squashing the cells (is not necessary to utilize to break special procedure cellular wall), collected using a nylon mesh of 80 Mm and next the comet assay was applied. Student's T test was the statistical test used for analyzing the comet assay data. RESULTS: Both assays showed a great sensitivity to the studied mutagens. A relationship between the dose-pink event and the dose-tail length was evident. Even though the Tradescantia mutation assay is a sensitive test with MH and EMS, low doses of NDEA were not able to induce a significant increase in the pink event frequencies; however, the comet assay was able to detect the mutagenic effect of NDEA at the same dose. Thus, it is clear that the comet assay is highly sensitive to the lowest dose of chemical mutagens. CONCLUSIONS: The comet assay on nuclei from Tradescantia staminal hairs is a useful tool to monitor genotoxic agents; it is simple, highly sensitive, and faster than the pink mutation test.

[Karyotype-phenotype correlation in a child with an idic (Yp)]. / Correlación cariotipo-fenotipo en un niño con un idic (Yp).

An 8-year-old boy with hypospadias and a 45,X/46,X,idic(Yp) karyotype is described. This chromosome abnormality possibly originated in an early zygote. It is concluded that: a) phenotypic variability in patients with an idic(Yp) probably results from an unequal tissular distribution of the different clones, and (b) deletion of Yq in the present case was distal to the stature determinants.