Analysis of chromatin instability of somatic cells in sheep

Abstract

Cytogenetic tests are highly reliable, sensitive indicators of the early effects of genomic instability. Their results provide information on the organism’s susceptibility to exogenous and endogenous factors and are measures of the degree of repair of DNA damage. Our study assessed spontaneously occurring damage in following four breeds of sheep: Polish Heath, Polish Lowland (Zelazna variety), Polish Blackhead, and Berrichon du Cher. Instability was identified using the following three different tests: a sister chromatid exchange (SCE) assay, identification of fragile sites, and the comet assay. The distribution of instabilities varied depending on the breed. The mean frequency of SCEs was 5.13 ± 1.58, whereas that of fragile sites was 3.30 ± 1.24. The mean level of DNA damage (% head DNA) was 96.52 ± 6.59. The most damage to genetic material was observed in the Berrichon du Cher sheep, and the least in the Polish Heath sheep. The tests used are reliable biomarkers of genome stability in animal breeds, as well as in individuals within breeds.

Evaluation of chromosomal instability in somatic cells of farmed foxes

“…Frequency of spontaneous sister chromatid exchange was analysed in various species of animals and amounted to 3.40 in chinchillas (Kuchta-Gładysz et al, 2015), 2.69 in rabbits and 1.41 in coypu (Kuchta-Gładysz et al, 2016), 3.38 in domestic cats (Szeleszczuk et al, 2014), 0.65 in blue fox and 2.33 in silver fox (Grzesiakowska et al, 2017). Cytogenetic instability identified as fragile site was observed in farm animals such as sheep (Wójcik et al, 2018) and in fur animals such as coypu (Kuchta-Gładysz et al, unpublished). The analyses performed on farmed fox lymphocytes were aimed to evaluate chromosomal instability using the MN test.…”

“…Çavaş and Ergene-Gözükara (2005) analysed 1500 cells. In a study with mammals, birds and reptiles, Zúñiga-González et al (2000) counted 10 000 cells per animal.…”

“…The MN assay was performed to assess chromosomal instability in animals, hybrids of two polymorphic species: the blue fox and the silver fox. Zúñiga-González et al (2000) studied the number of spontaneous nuclei in different species of mammals, birds and reptiles. The animals with the highest frequency of micronuclei were ocelot -13.5 MN per 10 000 cells; lynx -10.8; owl -10.6; gray squirrel -9.1; hedgehog -9.2; lion -4.1; orange-fronted parakeet -5.1; and common barn owl -3.5.…”

“…Chromosomal instabilities (CIN) are evaluated using cytogenetic tests for chromosome instability such as the micronucleus (MN) test, the sister chromatid exchange test, the bleomycin test, and the comet assay. The main chromosomal instabilities subjected to most analysis are isochromosomes, dicentric chromosomes, micronuclei, sister chromatid exchanges, and fragile sites (Świtoński et al, 2006;Geigl et al, 2008;Kozłowska and Łaczmańska, 2010;Czubaszek et al, 2014;Wójcik et al, 2018).…”

Assessment of chromosome stability in boars

“…It identifies chemical or enzymatic DNA modifications that transform into DNA breaks, as well as the kinetics of repair of this type of DNA damage. Using all these methods it is possible to assess and compare the chromosome stability of individual animal breeds [15,16].…”