Chromatin refers to the complex of DNA and proteins, primarily histones, found within the nucleus of horse cells. It plays a key role in regulating gene expression and maintaining genomic stability. Chromatin structure can influence the accessibility of DNA to transcription factors and other regulatory proteins, thereby impacting cellular function and development in horses. Modifications to chromatin, such as methylation and acetylation, can alter gene expression patterns and are a focus of research in equine genetics and epigenetics. This page compiles peer-reviewed research studies and scholarly articles that explore the structure, function, and modifications of chromatin in horses, as well as its implications for equine health and disease.
Rodriguez H, Bustos Obregon E.The fertilizing ability of stallion semen was analyzed using fresh and frozen samples, obtained before (June-July) or during (October-November) the breeding season. Thirty ejaculates obtained from 4 stallions were used. The analysis comprises routine seminogram; ATP concentration (Comhaire et al., 1983); subjective and objective motility and sperm velocity (Makler, 1980). Freezing was done following the technique of Martin et al. (1979). Sperm velocity, ATP content and objective motility in ejaculates of subjective motility >50% show values of 14.0 + or - 0.84 mu m s(-1); 4.8 + or - 2.7x10(...
Sailer BL, Jost LK, Evenson DP.Sperm from four mammalian species were analyzed by the sperm chromatin structure assay (SCSA) and the terminal deoxynucleotidyl transferase assay (TdTA) using flow cytometry. The SCSA quantitates the susceptibility of sperm nuclear DNA to in situ acid denaturation, while the TdTA quantitates the presence of endogenous DNA strand breaks in sperm nuclear chromatin. Correlations were seen between the percentage of sperm cells showing susceptibility to in situ acid denaturation and the percentage of cells showing the presence of DNA strand breaks for humans (r = 0.56, P = 0.004), rams (r = 0.84, P...
Mäkelä O, Gustavsson I, Hollmén T.Chromosomal analysis is not a routine examination in equine
practice. It is indicated, however, in infertile or subfertile
mares with small, inactive ovaries (Chandley et a/. 1975;
Power 1986).
The most commonly reported abnormalities in mares
concern sex chromosomes such as 63,XO and mosaic
63,XO/64,XX giving sterile mares and 64,XY resulting in
gonadal dysgenesis, sex reversal and testicular feminisation
(Power 1990). The phenotypic manifestations of a horse with
these karyotypic abnormalities are usually quite mild
compared with the corresponding abnormalities in man. These
mild ...
Hinrichs K, Schmidt AL, Friedman PP, Selgrath JP, Martin MG.The chromatin configuration of resting horse oocytes and the time course of in vitro oocyte maturation was characterized using a fluorescent, DNA-specific label. Oocytes were classified as having either compact (CP) or expanded (EX) cumuli at the time of collection. Centrifugation of oocytes was effective in allowing visualization of the germinal vesicle. Two main chromatin configurations were found in oocytes known to have a germinal vesicle: condensed chromatin (CC), in which the chromatin formed a dense mass surrounding the nucleolus; and fluorescing nucleus (FN), in which the entire nucleu...
Livolant F.The fine structure of chromatin in sperm heads was investigated by different microscopic techniques: in vivo examinations in the polarizing microscope, thin sections and freeze-fracture replicas observed by transmission electron microscopy. The freeze-fractured chromatin appears to be formed of superimposed lamellae, each one 330 A thick. These lamellae are parallel to the flattening plane of the sperm head. This situation was already described in other mammal spermatozoa and in particular in the bull and the rabbit. This work presents a new interpretation of this lamellated aspect. The chroma...
Brownlow MA, Hutchins DR, Johnston KG.Cells in the peritoneal fluid from 159 horses were examined in Giemsa stained preparations using light microscopy. Normal mesothelial cells showed an oval nucleus with finely reticular chromatin and pale blue cytoplasm. Activated mesothelial cells occurred in fluids derived from mesothelium under acute or subacute, non-septic stimulus and were remarkable for their pleomorphism and intense basophilia which may mimic neoplasia. Transformed mesothelial cells seen in chronic inflammatory fluids were sometimes phagocytic and showed conspicuous cytoplasmic vacuolation.
Deriusheva SE, Loginova IuA, Chiriaeva OG, Iasinetskaia NI, Efimov AM.Restriction endonuclease in situ digestion of metaphase chromosomes gives an opportunity to reveal strips with different structure within GC-rich pericentric heterochromatin of the domestic horse and the wild Przewalski horse. Blocks of heterochromatin, which are insensitive to HaeIII and brightly stained with chromomycin A3 after restriction enzyme digestion, are localized on the border with euchromatin in the majority of chromosomes of Equus caballus and E. przewalskii. In contrast to chromosome 5 of E. caballus, acrocentric chromosomes of E. prezewalskii which are homologous to this chromos...
Yi M, Asgenbaatar N, Wang X, Ulaangerel T, Shen Y, Wen X, Du M, Dong X, Dugarjav M, Bou G.DNA methyltransferases (DNMTs) are important epigenetic modification during spermatogenesis. To further evaluate the pattern of DNMTs in horse testes during development, we investigated the expression and localization of DNMT1, DNMT3a and DNMT3b at different time points. The qRT-PCR results showed that DNMT1 expression was maintained in testes tissue from 6-month-old (0.5y) to 2-year-old (2y) of age and decreased after 3-year-old (3y) (P < 0.01). The expression levels of DNMT3a and DNMT3b peaked in testes tissue at 3y (P < 0.01). At 4-year-old (4y), the expression of DNMT3a and DNMT3b was ...
Frontiers in geneticsFebruary 27, 2025
Volume 16 1534461 doi: 10.3389/fgene.2025.1534461
Barber AM, Kingsley NB, Peng S, Giulotto E, Bellone RR, Finno CJ, Kalbfleisch T, Petersen JL.The Functional Annotation of Animal Genomes (FAANG) consortium aims to annotate animal genomes across species, and work in the horse has substantially contributed to that goal. As part of this initiative, chromatin immunoprecipitation with sequencing (ChIP-seq) was performed to identify histone modifications corresponding to enhancers (H3K4me1), promoters (H3K4me3), activators (H3K27ac), and repressors (H3K27me3) in eight tissues from two Thoroughbred stallions: adipose, parietal cortex, heart, lamina, liver, lung, skeletal muscle, and testis. The average genome coverage of peaks identified by...
Baatar T, Song D, Weng Y, Wang G, Jin L, Guo R, Li B, Dugarjaviin M.The epigenetic regulation of gene expression through the covalent modification of histones is crucial for developing germline cells. To study the regulatory role of alternative splicing (AS) of euchromatic histone lysine methyltransferase 2 (EHMT2/G9A) in spermatogenesis in Mongolian horses, this study first examines the localization of the EHMT2 gene in testicular support cells and then predicts the higher-order structures of sequences with and without AS. Two types of lentiviral vectors for overexpression were subsequently constructed for the EHMT2 gene, one with AS and one without, to infec...
Ząbek T, Witarski W, Szmatoła T, Semik-Gurgul E, Sawicki S, Ropka-Molik K.We have explored the impact of DNA methylation changes on gene transcription in expanded equine chondrocytes treated with the histone deacetylase inhibitor (HDACi), Trichostatin A (TSA). The subjects were DNA and RNA samples prepared from articular cartilage cells derived from four animals in our previous study. Using Reduced Representation Bisulfite Sequencing (RRBS), we determined differentially methylated sites (DMS) and regions (DMRs) in the genomes of TSA-treated cells. We linked them to gene differential expression, as obtained from 3' mRNA sequencing data and the single-locus quantifica...
Ramírez-Agámez L, Hernández-Avilés C, Samper JC, Love CC.Intracytoplasmic sperm injection (ICSI) using frozen/thawed (F/T) stallion sperm is a common procedure in the equine breeding industry. Historically, sex-sorted (SS) F/T stallion sperm has yielded lower cleavage (<30 %) and blastocyst rates (<5 %) after ICSI when compared to non-sorted (NS) F/T sperm. Recently, a new technology for sperm sex-sorting (Genesis III) has been validated by a commercial company. In Experiment 1, the post-thaw quality between NS-F/T and SS-F/T stallion sperm produced with this technology was compared. The post-thaw sperm motility was higher in NS-F/T (41 %) than i...
Brito LFC, Linardi RL, Rosales LAS, Balamurugan NS, Hernández-Avilés C, Ramírez-Agámez L.Efficient use of stallion semen in liquid state is limited by its relatively short shelf-life. A chemically defined extender (Beyond) is now available for long-term liquid semen preservation. The objectives of the present study were to compare Beyond with milk extenders for the preservation of semen at two temperatures, and to evaluate fertility of semen cooled for 4-8 days before artificial insemination. Semen was processed using different extenders: milk, cholesterol (BotuSemen Special); milk-based (INRA 96); and Beyond. Sperm motility, membrane and acrosome integrity, and chromatin struct...
Rychtarova J, Fulka H, Loi P, Fulka J.In the mouse, spermatozoa are highly resistant to DNA damage, even when frozen without cryoprotectants, and can produce offspring when subsequently used for ICSI (intracytoplasmic sperm injection). It is not known whether the same applies to other mammals as well. For example, in the horse, even conventional sperm freezing is still very problematic and frequently leads to sperm immobility. It has, however, never been tested whether sperm immobility also mirrors sperm head DNA damage, and if so, to what extent. In our study, we evaluated the damage to DNA in horse frozen and thawed motile and i...
Liu L, Cao H, Ma H, Chen B, Liu W.H3K4me3, a well-established histone modification associated with active promoters, plays a critical role in orchestrating gene expression programs that govern mammary gland development and lactation. In this study, we present the first comprehensive epigenomic profiling of H3K4me3 modifications during mammary gland development in Yili horses using Cleavage Under Targets and Tagmentation (CUT&Tag) and RNA sequencing. Mammary gland tissues were collected from two developmental stages-early lactation and peak lactation. A total of 393 differentially expressed genes (DEGs) were identified betw...
