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With the advent of next-generation sequencing technology, genome-wide maps of DNA methylation are now available. The Thoroughbred horse is bred for racing, while the Jeju horse is a traditional Korean horse bred for racing or food. The methylation profiles of equine organs may provide genomic clues underlying their athletic traits. We have developed a database to elucidate genome-wide DNA methylation patterns of the cerebrum, lung, heart, and skeletal muscle from Thoroughbred and Jeju horses. Using MeDIP-Seq, our database provides information regarding significantly enriched methylated regions beyond a threshold, methylation density of a specific region, and differentially methylated regions (DMRs) for tissues from two equine breeds. It provided methylation patterns at 784 gene regions in the equine genome. This database can potentially help researchers identify DMRs in the tissues of these horse species and investigate the differences between the Thoroughbred and Jeju horse breeds.

The Przewalski׳s horse is a rare and endangered species and the last existing wild horses. Therefore, its genetic characterization is important to facilitate the systematic preservation and promotion of its gene pool. Karyotypes of chromosomes confirmed that the two tested horses were indeed Przewalski׳s horses (2n=66). Their genome was characterized using whole-genome re-sequencing and a comprehensive list of genetic variants including SNPs and INDELs was developed. We found a total number of 5,879,868 SNPs in the male and 6,040,778 SNPs in the female. Homozygous variations were more abundant than heterozygous variations, probably caused by inbreeding during the restoration process of species from only 13 horses. In conclusion, our results provide valuable information such as additional sequence information for equine researchers and can help to figure out how the horse genome was changed by domestication in recent years.

Physical exercise induces gene expression changes that trigger glucose metabolism pathways in organisms. In the present study, we monitored the expression levels of LDHA (lactate dehydrogenase) and GYS1 (glycogen synthase 1) in the blood, to confirm the roles of these genes in exercise physiology. LDHA and GYS1 are related to glucose metabolism and fatigue recovery, and these processes could elicit economically important traits in racehorses. We collected blood samples from three retired thoroughbred racehorses, pre-exercise and immediately after 30 min of exercise. We extracted total RNA and small RNA (≤ 200 nucleotide-long) from the blood, and assessed the expression levels of LDHA, GYS1, and microRNAs (miRNAs), by using qRT-PCR. We showed that LDHA and GYS1 were down-regulated, whereas eca-miR-33a and miR-17 were up-regulated, after exercise. We used sequences from the 3′ UTR of LDHA and GYS1, containing eca-miR-33a and miR-17 binding sites, to observe the down-regulation activity of each gene expression. We observed that the two miRNAs, namely, eca-miR-33a and miR-17, inhibited LDHA and GYS1 expression via binding to the 3′ UTR sequences of each gene. Our results indicate that eca-miR-33a and miR-17 play important roles in the glucose metabolism pathway. In addition, our findings provide a basis for further investigation of the exercise metabolism of racehorses.

This study investigated the effects of two different activation regimens on the developmental potential of somatic cell nuclear transfer (SCNT) embryos and postnatal survivability of the cloned piglets. In vitro matured oocytes were enucleated and reconstructed with porcine fetal fibroblasts. On the basis of the activation regimen used, the reconstructed porcine embryos were allocated into two groups: Group 1-simultaneous electrical pulses and activation group (SFA group); and Group 2-electrical fusion without calcium followed by electrical pulses with calcium after colcemid and cytochalasin B treatment for 5h (DA group). Embryonic development in both SFA and DA groups was determined at day 6 of culture in NSCU-23 medium. To investigate the post-implantation development after the two activation methods, embryos were cultured for 1 day and then transferred into the oviducts of estrus-synchronized recipients. DA group had significantly (p0.05) higher cleavage rates than SFA group. However, the developmental rate to the blastocyst stage and the mean cell number of blastocysts did not differ (p0.05) between SFA and DA groups. Moreover, the pregnancy rate of SFA group was not significantly different compared to DA group. A total of 20 cloned piglets (SFA group-8 live piglets, DA group-11 live piglets and one stillborn) were obtained in the present study. The birth weight of the cloned piglets (live births) did not differ (p0.05) between the two groups. Furthermore, no difference was observed in the postnatal survival rates of the cloned piglets obtained using two different activation regimens. These results suggest that the timing of artificial activation and additional chemical treatments do not affect the developmental rate of porcine SCNT embryos. Remarkably, the pregnancy rate and postnatal survivability of the cloned piglets did not vary between SFA and DA groups.

Thoroughbred is the main horse breed in the horse racing industry. The horses which record excellent performance are valuable in the aspects of economics and industry. Because of the limitation of the conventional breeding methods, it is needed to develop a reliable system for the selection of stallion stud based on molecular breeding. Therefore we conducted high throughput analysis to discover exercise-related single nucleotide variations (SNVs) and differentially expressed genes (DEGs). We sequenced the whole mRNA from the blood and muscle tissues of six thoroughbred horses before and after exercise. By comparing current horse genome annotation, we identified 32,361 unigene clusters and 189,973 SNVs from the sequence aligned against the horse reference genome. We also identified genes regulated by exercise: 62 up-regulated and 80 down-regulated genes in the blood, and 878 up-regulated and 285 down-regulated genes in the muscle, respectively. In addition to DEGs, we also found differentially expressed alternative splicing forms of AXL, DYNC1, PLEKHG1, and COBLL1 before and after exercise. Overall, our results indicated that exercise stress induces massive gene expression change. Further studies should be focused on the mechanism of exercise-induced change and their relation in excellent performance in racing horses. Our data would be valuable information to develop exercise-related markers in horses and ultimately applied to establish a reliable selection system for producing a better stallion.

To date, immunoglobulin (Ig) genes have only been fully characterized in a small number of aves, which pose a major obstacle to understanding Ig evolution. Thus, we cloned the cDNAs of three immunoglobulin classes, IgA, IgM, and IgY, from Phasianus colchicus, Coturnix japonica, and Meleagris gallopavo. Multiple sequence alignments revealed that the highest degree of sequence homology in all Ig classes was observed between pheasant and turkey whereas the degree of homology between the galliforms and non-galliforms was relatively low compared to that among the galliforms. When the constant region domains of the four human Ig classes were compared with the corresponding regions in aves, the average percent homology between human CH2 and avian CH3, and between human CH3 and avian CH4, was greater than between identical domains in IgA and IgY, which are in partial agreement with the hypothesis that the avian CH2 domain evolved to form the mammalian hinge via domain condensation. Phylogenetic analysis showed that the galliform Ig heavy chain constant regions were divided into quail and the common ancestor of chicken, turkey, and pheasant, and that chicken was separated from turkey and pheasant, which were grouped together. These results add to our knowledge of galliform Igs and the diversification of these genes.

This study was conducted to investigate the amount of CLA synthesized endogenously by rat mammary tissues in response to TVA (a precursor for cis-9, trans-11 CLA endogenous synthesis) treatment as well as the differences in the protein expression of genes encoding the biosynthesis of CLA in rat mammary tissue and mouse mammary gland epithelia cells (HC11). Treatment with TVA resulted in improved CLA productivity. Furthermore, 2-DE revealed two spots in samples of mammary tissues and one spot in samples of mammary gland epithelia cells (HC11) that were consistently altered in the TVA treatment groups when compared with the control group (non-fatty acid). The mRNA expression patterns of three of the proteins (PDI, PRDX2, LAMR1), as measured by real-time PCR, were similar to the pattern of protein abundance. In addition, the expression of SCD mRNA in the mammary tissue of rats and HC11 cell treated with TVA was higher than in the control group. Our results suggest that the identified proteins may be related to CLA biosynthesis in mammary tissue.