The Effect of Environmental Factors on Sister Chromatid Exchange Incidence in Domestic Horse (Equus caballus) Chromosomes

Effect of Selected Micro- and Macroelements and Vitamins on the Genome Stability of Bovine Embryo Transfer Recipients following In Vitro Fertilization

Genome instability can lead to a wide variety of diseases. Many endogenous and exogenous factors influence the level of damage to genetic material. Genome integrity depends on factors such as the fidelity of DNA replication, normal DNA organization in the chromosomes, and repair mechanisms. Genome stability influences fertility, embryonic development, and the maintenance of pregnancy. In the case of in vitro fertilization, it can be an important factor determining the success of the procedure. The aim of the study was to assess the stability of the genomes of recipient cows following in vitro fertilization using cytogenetic tests and to analyze the effects of selected vitamins and micro- and macroelements on genome integrity. Genome stability was analyzed using the sister chromatid exchange, fragile site, and comet assays. The material for analysis was peripheral blood from 20 Holstein-Friesian heifers that were embryo transfer recipients. The effect of selected micro- and macroelements and vitamins on the genome stability of the cows was analyzed. Folic acid was shown to significantly influence the level of damage identified using the SCE, FS, and SCGE assays, while iron affected SCE and SCGE results, and zinc affected FS.

Chromosome Instability in Pony of Esperia Breed Naturally Infected by Intestinal Strongylidae

The Pony of Esperia is an Italian autochthonous horse breed reared in the wild on the Aurunci and Ausoni Mountains. Currently, it is considered an endangered breed, as its population consists of 1623 animals. It is therefore essential to identify all aspects that can improve the management and economy of its breeding, favoring its diffusion. In this paper, the effects of intestinal strongyle infection on the chromosome stability of peripheral blood lymphocytes (PBLs) was evaluated through aneuploidy and chromosome aberration (gap, chromatid and chromosome breaks, and the number of abnormal cells) test. Statistical difference in the mean values of aneuploidy, cells with chromosome abnormalities, and chromosome and chromatid breaks were observed between ponies with high fecal egg counts (eggs per gram > 930) and those with undetectable intestinal strongylosis. The causes of this phenomenon and possible repercussions on the management of Pony of Esperia are discussed in the paper.

Assessment of chromosome stability in boars

Chromosome instability adversely affects animal fertility and reproduction. Analysis of instability can be a valuable diagnostic tool. Helpful tests for assessment of instabilities include the sister chromatid exchange assay, identification of fragile sites, the bleomycin assay and the comet assay. These techniques can be used to assess and compare the chromosome stability of individual breeds of animals. The aim of the study was to assess chromosome stability in boars: Duroc, Duroc x Pietrain and Pietrain x Duroc crossbreds, Polish Large White, and the Neckar, P76 and PIC lines. The study assessed the chromosome stability of boars. The distribution of instabilities in individual breeds was varied. The average frequency of chromatid exchange was 4.8 ± 1.5, while that of fragile sites was 3.9 ± 1.4. The mean level of DNA damage (% tail DNA) was 9.4 ± 8.3, while in the bleomycin assay b/c and %AM were 0.6 ± 0.7 and 44.4 ± 4.1. A higher rate of instability was found in older individuals than in younger ones. The cytogenetic assays used to identify various forms of chromosome instability can be used to evaluate boars intended for breeding.

Assessment of genome stability in various breeds of cattle

Chromosomal instability is a type of genome instability involving changes in genetic information at the chromosomal level. The basic tests used to identify this form of instability are sister chromatid exchange (SCE) tests and identification of fragile sites (FS). SCE is the process by which sister chromatids become fragmented as a result of DNA strand breakage and reassembly, followed by exchange of these fragments. FS can be observed in the form of breaks, gaps or constrictions on chromosomes, which often result from multiple nucleotide repeats in DNA that are difficult to replicate. The research material was the peripheral blood of ten breeds of cattle raised in Poland, including four native breeds covered by a genetic resources conservation programme, i.e. Polish Red, Polish Red-and-White, White-Backed, and Polish Black-and-White, as well as Polish Holstein-Friesian, Simmental, Montbéliarde, Jersey, Limousine and Danish Red. Two tests were performed on chromosomes obtained from in vitro cultures: SCE and FS. The average frequency of SCE was 5.08 ± 1.31, while the incidence of FS was 3.45 ± 0.94. Differences in the incidence of SCE and FS were observed between breeds. The least damage was observed in the Polish Red and White-Backed breeds, and the most in Polish Holstein-Friesians. The most damage was observed in the interstitial part of the chromosomes. Age was shown to significantly affect the incidence of SCE and FS. Younger cows showed less damage than older ones (SCE: 4.84 ± 1.25; 5.34 ± 1.24; FS: 3.10 ± 0.88, 3.80 ± 0.92).

Immunophenotypic characterisation and cytogenetic analysis of mesenchymal stem cells from equine bone marrow and foal umbilical cords during in vitro culture

Introduction: The objective of the study was immunophenotypic and cytogenetic analysis of mesenchymal stem cells from equine bone marrow and foal umbilical cords during in vitro culture.

Material and Methods: The mesenchymal stem cells were obtained from equine bone marrow of three horses and from foal umbilical cords of six foals. The cells were cultured in CO2 incubators by standard procedure. Quantitative abnormalities of chromosomes, i.e. aneuploidy and polyploidy, and structural aberrations, i.e. breaks in chromosomes and chromatid, were taken into account during the study.

Results: The results of cytogenetic analysis of equine bone marrow mesenchymal stem cells at the third and fourth passages indicated that the level of karyotype variability of these cells corresponded to the spontaneous level of karyotype variability typical of the peripheral blood lymphocytes of this species. Equine bone marrow contained several clones of stem cells that differed in the expression of specific nuclear markers characteristic of proliferating cells.

Conclusion: Mesenchymal stem cells from foal umbilical cords during in vitro cultivation are characterised by quantitative abnormalities of the chromosomal apparatus.

Similar Sister Chromatid Arrangement in Mono- and Holocentric Plant Chromosomes

Due to the X-shape formation at somatic metaphase, the arrangement of the sister chromatids is obvious in monocentric chromosomes. In contrast, the sister chromatids of holocentric chromosomes cannot be distinguished even at mitotic metaphase. To clarify their organization, we differentially labelled the sister chromatids of holocentric Luzula and monocentric rye chromosomes by incorporating the base analogue EdU during replication. Using super-resolution structured illumination microscopy (SIM) and 3D rendering, we found that holocentric sister chromatids attach to each other at their contact surfaces similar to those of monocentrics in prometaphase. We found that sister chromatid exchanges (SCEs) are distributed homogeneously along the whole holocentric chromosomes of Luzula, and that their occurrence is increased compared to monocentric rye chromosomes. The SCE frequency of supernumerary B chromosomes, present additionally to the essential A chromosome complement of rye, does not differ from that of A chromosomes. Based on these results, models of the sister chromatid arrangement in mono- and holocentric plant chromosomes are presented.

Spontaneous sister chromatid exchange in mitotic chromosomes of the chinchilla (Chinchilla lanigera)

Kuchta-Gładysz, M., Wójcik, E., Szeleszczuk, O., Niedbała, P. and Tyblewska, K. 2015. Spontaneous sister chromatid exchange in mitotic chromosomes of the chinchilla (Chinchilla lanigera). Can. J. Anim. Sci. 95: 543–550. The sister chromatid exchange (SCE) test is a cytogenetic tool with applications as a short-term screen. It is used to assess the influence of physical and chemical factors with potential mutagenic and genotoxic properties on the animal organism. The test results make it possible to eliminate mutagens, as well as helping to predict possible genetic consequences in animal cells and assess animal resistance. The mitotic chromosomes were obtained from an in vitro culture of peripheral blood lymphocytes with added bromodeoxyuridine (BrdU), at five different concentrations: 0.25, 0.5, 1.0, 2.5, and 5.0 µg mL−1. The chromosomes were stained according to the FPG method. Our analyses revealed the spontaneous SCE level in the chinchilla at the concentration of 0.5 µg mL−1. Higher concentrations of this substance have a genotoxic effect and cause damage to the DNA structure of the chromosomes by inducing additional SCEs in the chromosomes of this species. The mean SCE/cell incidence in the chinchilla population was 4.34±1.28. We investigated the effects of age on the incidence of SCE and found it significantly affected this phenomenon in both sexes.

Analysis of chromosome damage by sister chromatid exchange (SCE) and redox homeostasis characterization on sheep flocks from Sardinian pasturelands

Over the last decades, an increase of pollutants of diverse origin (industrial, military, mining, etc.) was recorded in several areas of Sardinia Island. We report the results of a multidisciplinary and complementary study based on cytogenetic and physiological analyses. The data obtained show the effects of the environmental impact on six sheep flocks (Sardinian breed) grazing on natural pasturelands next to possible polluted areas and compared to three herds grazing in different areas far from those potentially contaminated and used as control. Sister chromatid exchange (SCE) test was used as cytogenetic test to analyze chromosomal damages and it was performed on peripheral blood samples collected from 129 adult sheep (age > 4 years) randomly selected from polluted (92 animals) and control (37 animals) areas. Two types of cell cultures were performed: without (normal cultures) and with the addition of 5-BrdU. SCE-mean values estimated over 35 cells counted for each animal were 8.65 ± 3.40, 8.10 ± 3.50, 8.05 ± 3.08, 7.42 ± 3.34, 9.28 ± 3.56 and 8.38 ± 3.29 in the exposed areas, whereas the average values were 7.86 ± 3.31 in the control group. Significant increases (P < 0.01) of SCEs were found in three investigated areas of Southern Sardinia. Furthermore, sheep of the same flocks were characterized for blood redox homeostasis in order to define the potential targets of oxidative damage and to identify biomarkers of the extent of animal exposure to environmental contaminants. The plasma levels of Asc, Toc and Ret were found to be significantly lower (P < 0.001) in exposed sheep (I, II, IV and V) than in the control group. TAC as well as GPx and SOD activities were higher in control than in the exposed groups (P < 0.001). Finally, plasma levels of N-Tyr, PC, and LPO were significantly lower (P < 0.001) in the control group than in the exposed groups.