Chromosomal aberrations and their mechanisms have been studied for many years in livestock. In cattle, chromosomal abnormalities are often associated with serious reproduction-related problems, such as infertility of carriers and early mortality of embryos. In the present work, we review the mechanisms and consequences of the most important bovine chromosomal aberrations: Robertsonian translocations and reciprocal translocations. We also discuss the application of bovine cell cultures in genotoxicity studies.

The detection of chromosomal damage serves as a tool for the verification of the genotoxic effects of chemical substances in vitro. We used conventional cytogenetic analysis in order to test for the potential genotoxic action of the insecticide thiacloprid (the active ingredient in commercial preparation CALYPSO 480 SC). The test cultures of bovine lymphocytes obtained from the peripheral blood were incubated with the insecticide in concentrations of: 30, 120, 240 and 480 μg.ml⁻¹ for 24 and 48 hours. After 24 hours of incubation, we observed that the increasing concentrations resulted in a significant (P < 0.05; P < 0.01) increase in the frequency of DNA damage. Our experiments showed the presence of aberrations of a non-stable type (chromatid and chromosome breakage). The conventional chromosome analysis was supplemented with fluorescence in situ hybridization for the detection of numeric and stable structural aberrations. Whole chromosome probes for bovine chromosomes 1, 5 and 7 (BTA 1, BTA 5 and BTA 7) were used in the experiments.

Background: Two hereditary eye disorders that are frequently observed in Collies and related breeds are Collie Eye Anomaly (CEA) and Progressive Retinal Atrophy (PRA). The main symptom of CEA is choroidal hypoplasia. It is associated with a 7.8 kb deletion in intron 4 of the NHEJ1 gene located on chromosome CFA7. Rod–cone dysplasia 3 (RCD3), an early-onset form of PRA, is associated with mutations in the PDE6A gene. Methods: Molecular diagnostic techniques were used in this study to identify genetic mutations linked to CEA and RCD3-type PRA in a subset of dog breeds. Australian Shepherds (n = 29), Border Collies (n = 9), Longhaired Collies (n = 27), and Shetland Sheepdogs (n = 10) provided a total of 75 DNA samples. Samples were collected by buccal swab or blood draw, and PCR and real-time PCR methods were used for processing. Results: Of the dogs in the studied breeds, 31 had the NHEJ1 gene mutation linked to CEA. Among these, 15 were homozygous recessive (affected), while 16 were heterozygous (carriers). None of the samples had any mutations in the PDE6A gene associated with RCD3-type PRA. Conclusions: Effective identification of carriers and affected individuals for CEA was made possible by PCR-based genetic testing, confirming its value in early diagnosis and breed control. Although the RCD3 form of PRA has not been previously reported in Collies or Australian Shepherds, it was included in our analysis due to the genetic relatedness among herding breeds and the potential presence of undetected carriers resulting from historical crossbreeding.

5-methylcytosine (5mC) is one of the most important epigenetic modifications. Its increased occurrence in regulatory sequences of genes, such as promoters and enhancers, is associated with the inhibition of their expression. Methylation patterns are not stable but are sensitive to factors such as the environment, diet, and age. In the present study, we investigated the effects of fungicide miconazole, both alone and in combination with the insecticide Mospilan 20SP, on the methylation status of bovine GSTP1, GSTA4, and AChE genes in bovine lymphocytes cultured in vitro. The methylation-specific PCR technique was used for the objectives of this study. We found that miconazole alone at concentrations of 1.25, 2.5, 5, 10, 25, and 50 µg/mL after 24 h exposure probably did not induce changes in methylation for all three genes analysed. The same results were found for the combination of pesticides at 24 h exposure and the following concentrations for each of them: 0.625, 1.25, 2.5, 5, and 12.5 µg/mL. Thus, we can conclude that the fungicide miconazole alone, as well as in combination with the insecticide Mospilan 20SP, was unlikely to cause changes to the methylation of bovine GSTP1, GSTA4, and AChE genes.

Thiacloprid, a neonicotinoid insecticide, is widely used to control various species of pests in the current agriculture of today. The potential genotoxic effects of thiacloprid on human peripheral blood lymphocytes were investigated in vitro by chromosome aberrations (CA), and double-strand breaks (DSB), which were detected by the phosphorylation of γH2AX histone. Human peripheral blood lymphocytes were exposed to 30, 60, 120, 240, 480 µg.ml⁻¹ doses for the last 24 and 48 hours of culture. Thiacloprid increased CA at the concentrations of 240, 480 μg.ml⁻¹ (P < 0.05), but these results did not confirm genotoxicity. The mitotic index (MI) was important to us; it served as a basis for the confirmation of the cytotoxicity of this insecticide. During 48 hours of culture, at the concentration of 480 µg.ml⁻¹, its value rapidly decreased (0.42) (P < 0.001), which did not allow us to analyse the results because of the high cytotoxic response.