Determination of the correlation between stallion's age and number of sex chromosome aberrations in spermatozoa

The aim of this study was a cytogenetic analysis of stallions semen to find sex chromosome aberrations and to determine if there was an association between stallion's age and aberration frequency for the sex chromosomes. Sperm samples were collected from 22 stallions of various age from 3 to 23 years. Multicolour FISH was performed on each sample, using probes for the sex chromosomes and EGFR gene, localized on 4p12 in domestic horse. A total of 26199 sperm cells were analysed (from 1 070 to 1 532 per animal). Among the analysed cells, there were 50.318% with X chromosome, 48.543% with Y chromosome and 1.139% with aberrant chromosomes. The frequency of aberrations was: sex chromosomes nullisomy (0.466%), XY aneuploidy (0.454%), XX disomy (0.146%), YY disomy (0.041%), diploidy (0.024%) and trisomy XXY (0.008%). Additionally there was a correlation between the age of an animal and the frequency of sex chromosome aberration and a significant positive correlation between age and disomy of XY, XX, YY, trisomy of XXY, autosomal disomy was seen. A Correlation between the age of a stallion and the level of nullisomy was negative. The present study demonstrated that FISH technique is a powerful method to identify sex chromosome aberrations in equine spermatozoa and might be very helpful for a breeder during a selection for the best stallion.

Usefulness of a supplementary set of microsatellite DNA markers for parentage testing in cattle

The aim of the present study was to determine a supplementary set of microsatellite DNA markers to be used in addition to the standard panel of 12 microsatellite markers recommended for parentage testing in cattle. A method has been developed for analysis of 10 loci in a single multiplex PCR reaction and using automated DNA sizing technology in a sequencer, which will enable the additional set of markers to be used for routine pedigree verification. Preliminary analysis showed that the polymorphism of 10 selected markers (PIC and H > 0.5 for 9 loci) and PEc of 99.77% suggest that the microsatellite sequences selected could be useful in cases of disputable parentage where the standard set may prove insufficient, e.g. in closely related animals or those from herds subjected to rigorous selection.

Comparative cytogenetic and molecular studies of DM domain genes in pig and cattle

Despite great differences in the biology of sex determination, the DM domain genes are thought to regulate sexual development in both invertebrates and vertebrates. Although they seem to represent the first known example of the conservation of metazoan sexual pathways, the structure-function relationships of this gene family have not yet been clearly determined. Our previous and current studies on the DMRT (Doublesex and mab-3 related transcription factor) gene cluster, DMRT1, DMRT2, DMRT3, in pig and cattle, have revealed conserved linkage to bovine (BTA8q17) and swine (SSC1q21) autosomes. However, the DMRT cluster seems to harbour the genes in different orders in both cattle (Entrez database) and pig (IMpRH map), compared to other vertebrates investigated so far. Moreover, we found that expression of DMRT1 (considered as the testicular regulator so far) is not restricted to gonads in adult animals. Beside ovary and testis, DMRT1 expression was detectable in swine kidney and bovine liver, heart, skeletal muscle, kidney, lung, spleen and showed no differences between the sexes. Swine and bovine DMRT3 expression was strongly restricted to the adult testis, while DMRT2 homologues have a wider expression pattern, as occurs in other mammals. The significance of this expression pattern of DMRT genes in adult pig and cattle remains unclear. It might shed new light on mammalian DM domain genes evolution and livestock intersexuality.

Application of 19 microsatellite DNA markers for parentage control in Borzoi dogs

The aim of this study was to analyse the polymorphism of 19 microsatellite markers and their usefulness for parentage verification in 28 Borzoi dogs in Poland. The assay involved the following 19 loci: AHTk211, CXX279, REN169018, INU055, REN54P11, INRA21, AHT137, REN169D01, AHTh260, AHTk253, INU005, INU030, FH2848, AHT121, FH2054, REN162C04, AHThl71, REN247M23 and amelogenin. These markers are included in the panel of loci recommended by the ISAG. Amplified PCR products were analysed by an automated sequencer ABI PRISM 3130xl Genetic Analyser. The number of alleles per locus varied from 3 (INU005) to 8 (REN162 and AHT171). Except the INU005 locus, which showed the lowest variation (PIC=0.396, H=0.438), the calculated PIC values exceeded 0.6 and H values ranged from 0.677 (INU055) to as much as 0.84 (REN162). Based on PE(C) it was found that incorrect pedigree in this breed can be excluded with 99.9998% accuracy using DNA analysis.

A case of an intersex horse with 63,X/64,XX/65,XX,del(Y)(q?) karyotype

Cytogenetic and molecular genetic studies of an intersex horse have been carried out. The investigated animal had overall male body conformation; however, its external genitalia consisted of incompletely developed vulva and penis. The X and Y chromosome painting probes detected three cell lines in the examined horse: 63,X, 64,XX and 65,XX with a fragment of a Y chromosome (del Y). The DNA analysis with the PCR and PCR/RFLP methods showed absence of SRY,AMELY and ZFY genes as well as of six Y microsatellite markers (YM2, YP9, YJ10, YE1, YH12, and YA16). These results suggest that the Y chromosome fragment detected in the investigated animal was the result of a deletion of a euchromatic fragment comprising the above-mentioned markers.

Karyotype evaluation among young horse populations in Poland

Five hundred young horses of the following breeds: Thoroughbred, Silesian, Malopolska, Wielkopolska, Polish Konik, Hutsul, Shetland Pony, Half-bred Anglo-Arabian, Noble Half-bred, Fjord and crosses were cytogenetically investigated. Chromosome preparations obtained after lymphocyte culture were analysed using conventional Giemsa staining and CBG-banding methods. In the case of abnormalities GTG-banding as well as FISH technique were applied. In ten mares different karyotypic abnormalities were diagnosed. One mare showed chromosome chimerism (64,XX/64,XY), eight had sex chromosomal aneuploidy (one in pure line 63,X and seven in mosaic form 63,X/64,XX) and one presented autosomal aneuploidy with mosaicism (64,XX/65,XX,+31). The influence of sex chromosome abnormalities on fertility and the possible utilisation of karyotypic control in any selection programme are discussed.

Fluorescent in situ hybridization mapping of the epidermal growth factor receptor gene in donkey

The physical localization of the epidermal growth factor receptor (EGFR) gene was performed on donkey chromosomes. Bacterial artificial chromosome DNA containing the equine EGFR gene was used to map this gene by fluorescent in situ hybridization on donkey metaphase chromosomes. The gene was mapped on donkey 1q21.1 region.

Comparison between the G-banded karyotype of the aoudad (Ammotragus lervia) and sheep (Ovis aries)

Karyotypes of the aoudad and sheep were compared on the basis of G-banded chromosomes at the 450 band level. The common G-banded karyotype showed the homology of all aoudad chromosomes (2n=58) with sheep chromosomes (2n=54) or sheep chromosome arms. The results of cytogenetic investigations suggest that in this case karyotype evolution has led to reduction in chromosome number as a result of centric fusions. The formation of the first metacentric chromosome occurred in the aoudad. The homology of the G-banding pattern in sheep and aoudad suggests the conservation in linear arrangement of genetic material. Thus comparative cytogenetics can be a useful tool in gene mapping.

60,XY/60,XX chimerism in the germ cell line of mature bulls born in heterosexual twinning

According to present knowledge there is a germ cell chimerism (XY/XX) in young bulls born in heterosexual twinning due to exchange of primordial germ cells in embryonic life. These germ cells were believed to have been eliminated in the young bull. Two-color fluorescence in situ hybridization (FISH) identification of the sex chromosomes by biotinylated and digoxygenin labeled probes have been used. The material consisted of three bulls born in heterosexual twinning. The results obtained indicated that even mature bulls (more than two years old) demonstrate spermatogonial chimerism. Several authors state that the bulls with blood cell chimerism, originating from dizygous twinning, are characterized by decreased fertility. Changes of the sex ratio of offspring due to proliferation of the female cells have also been proposed. The present observations should give a renewed interest in checking the possibility of survival and differentiation of germ cells from the female partner in the germ cell lines.