The Application of Zoo-Fish Technique for Analysis of Chromosomal Rearrangements in the Equidae Family
Genome analysis is necessary to trace evolutionary rearrangements and relationships between species. Initially, to this end, the tools of classical cytogenetics were used but along with the development of molecular cytogenetics methods it became possible to analyse the genome more thoroughly. One of the widely used methods is fluorescence in situ hybridization (FISH) and its different types. Zoo-FISH, or cross-species chromosome painting, which uses painting probes specific for whole chromosomes, enables detecting homologous synteny blocks, the occurrence of which is evidence that species share a common ancestry and are related. Zoo-FISH technique is complemented by FISH with probes specific to chromosome arms or repetitive sequences (telomeres, centromeres), which provide additional information about karyotype organization, as well as karyotype polymorphism and conservation. Another method used is FISH with gene-specific probes, which enable the localization of single loci, thus making it possible to determine linkages between genes and verify data obtained after using painting probes in Zoo-FISH technique. Because of its diverse karyotype and rapid karyotypic evolution, the Equidae family is an ideal object of study using a number of methods based on in situ hybridization, which, in turn, enables information to be obtained at many levels of DNA organization.
Sarcoid is the most common skin cancer in horses. The etiology of the tumor is associated with BPV infection (BPV-1, -2, -13), which is an inducer of malignant transformation. The comparative genomic hybridization (CGH) technique identifying the unbalanced chromosome aberrations was used to analyze the genome of equine sarcoid cells and to diagnose the chromosome rearrangements involving large deletions or amplification. The results were based on the analysis of 100 metaphases and their karyograms as well as the diagram showing the average ratio of the intensity of the green to red fluorescence, using MetaSystems software (Isis). Based on a comparison of the fluorescence intensity ratios we found duplication in the subtelomeric regions of chromosome pairs 1, 4, 7, 8 and 23. Duplicated region of chromosome pair 1 also included the coding region of the rDNA. In the chromosome 23 next to the duplication occurring in the centromeric region of q arm (23q11) we also found the presence of deletions involving 23q18-23q19 region. For the chromosome pairs 25 to 31 and the X chromosome the software failed to generate CGH diagram, but on the individual karyograms we were able to observe fluorescence signals characteristic of duplication (red), in rDNA regions of chromosome pairs 28 and 31. The study showed that duplications of DNA present in the sarcoid cells are found mainly in the telomeric and rDNA regions. The presence of the duplication of telomeric regions is associated with increased activity of the telomerase enzyme, which is a hallmark of cancer cells, affecting the immortality of these cells. Accordingly, duplications of rDNA coding regions increase activity of nucleolar organizer region which is a tumor marker.
Mitochondrial DNA (mtDNA) is a molecular tool that is very effective in genetic research, including phylogenetic analysis. The non-coding region is the most variable fragment of mtDNA, showing variability in length and nucleobase composition and containing three domains: two hypervariable peripheral regions and the conserved domain (D-loop) in the middle. The Anseriformes are amongst the best studied avian groups, including approximately 150 species and containing geese, swans, ducks (Anatidae), the Magpie goose (Anseranatidae) and screamers (Anhimidae). The most numerous family is the Anatidae, appearing in close relationships within the phylogenetic branches of the species. There are differences between the non-coding region of the Anatidae in comparison to other avian control regions. In the article presented below the control region sequences and the phylogeny of the Anatidae were reviewed.
The aim of the study was to analyse the genetic basis of piebald coat colour in Hucul horses and to verify their coat colour in breeding records. Tests were performed with DNA purified from the whole blood samples of 242 Hucul horses with different coat colour patterns. DNA was analysed to identify an inversion in ECA3 (PCR). The results confirmed that the inversion on ECA3 is a direct factor determining piebald (tobiano) colour in the analysed Hucul horses. No inversion was observed in any of the solid coloured horses, but it was present in all the piebald ones. It was also identified in 18% (11 of 61) of the horses from the group of horses qualified in the passport as solid coloured with white markings. In fact, these horses had the tobiano gene that is phenotypically identifiable as crypto-tobiano, which may give the false impression of having white markings and lead to error when describing a horse. This is an important issue, in particular with regard to the breed standard, which eliminates Hucul horses with white markings from breeding.
The aging process is a variable, stochastic and pleiotropic phenomenon which is regulated by different environmental and genetic factors. The age-associated changes, which occur at the molecular and cellular levels and disturb biological homeostasis, may directly or indirectly contribute to aging, causing apoptosis or cellular senescence and consequently leading to the death of the organism. In this context, it is particularly interesting to observe changes in somatic cell chromatin. In the present paper, we summarized the knowledge on the biological aspects of aging with special consideration of age-related changes in chromatin like DNA damage, shortening telomeres or age-related changes in methylation of DNA.
Blood cell chimerism is a common phenomenon occurring in cattle coming from double or multiple parturitions and can be observed as two DNA profiles present in blood of each of twin born animals. In the era of genomics, a large number of animals is being genotyped with high throughput genotyping methods, which are giving limited insight into the performance of single markers and rather only statistical description of the results is available for a common user. This hampers the detailed analysis of the results obtained and direct identification of the causes of poorer performance of some samples. In this study we describe the influence of analysis of DNA obtained from blood samples of cattle with genetic chimerism on basic parameters of Infinium technology-based Illumina’s genotyping arrays. The results obtained may help to identify such samples, especially when no precise information about the animals’ origin is available
Allelic and haplotypic variations at 27 SNP sites identified in four CpG islands of OAS1 were described in a group of Anglo-Arabian and Hucul horses. Variation in the type of less frequent alleles was the source of variability among breeds. A number of putative LD blocks were identified which could be used to study changes in the genetic structure between generations of both breeds concerning susceptibility to flaviviral infections. Some of the identified SNPs may have an impact on the transcriptional activity of OAS1 or could lead to amino acid substitution influencing proper function of OAS1 enzyme. In the light of recent studies, the described genetic variability of investigated CpG islands might be important in view of the effectiveness of viral incorporation into the host genome.
One of epigenetic features of mammalian genomes is methylation of DNA. This nucleotide modification might exert suppressive effect on gene transcription. We have described putative relevance of methylation of one of immune cells related gene (ITGAL) observed in the set of 11 equine tissues. Comparison between qualitative RT-PCR results and DNA bisulfite sequencing of investigated set of tissues pointed to potential correlations between tissue specific methylation and tissue specific transcription in ITGAL locus. These findings might be important for studies on genetic and epigenetic background of autoimmune disorders in the horse.
This study was designed to determine the degree of genetic distinctiveness between farmed and wild foxes (Vulpes vulpes). Analysis of polymorphism in 16 microsatellite sequences led to the conclusion that red foxes raised on Polish farms and wild foxes living in Poland are two groups of genetically distinct animals. Farmed Polish foxes are genetically more similar to the population of wild animals from North America than they are to the free-living population in Poland, as confirmed by the fact that the farmed animals are descended from animals raised in Canada.
The small genetic distance between wild Canadian foxes (indicated as the progenitor of farmed Polish foxes) and farmed Polish foxes possibly suggests that the differences between the farmed and wild Polish populations may result from the fact that Canadian and Polish foxes took separate evolutionary paths.
The raccoon dog (Nyctereutes procyonoides) is a mammalian species that belongs to Canidae family, order Carnivora. This species represents both animals living in the wild and farm animals used in the fur industry. Raccoon dogs have the most ‘primitive’ karyotype among Canidae family. The Chinese raccoon dog (Nyctereutes procyonoides procyonoides) is characterised by a variable number of chromosomes (2n = 54 + 0-4 B). B chromosomes are supernumerary chromosomes occurring in addition to the basic set of A chromosomes in the cells of many organisms. The function and origin of these additional chromosomes is not clear. The aim of this work was to determine possible karyotypic differences between wild-living and farm populations, using methods of classical and molecular cytogenetics. The most useful cytogenetic markers to analyse karyotype polymorphism of canine are the number of B chromosomes and nucleolar organizer regions. A variation was identified in the number of B chromosomes and nucleolar organizer regions (NORs) in cells between wild-living and breeding populations.