Age-associated methylation changes in genomic DNA have been recently reported in spermatozoa, and these changes can contribute to decline in fertility. In a previous study, we analyzed the genome-wide DNA methylation profiles of bull spermatozoa using a human DNA methylation microarray and identified one CpG site (CpG-1) that potentially reflects age-related methylation changes. In the present study, cryopreserved semen samples from a Japanese Black bull were collected at five different ages, which were referred to as JD1-5: 14, 19, 28, 54, and 162 months, respectively, and were used for genome-wide DNA methylation analysis and in vitro fertilization (IVF). Distinct age-related changes in methylation profiles were observed, and 77 CpG sites were found to be differently methylated between young and adult samples (JD1-2 vs. JD4-5). Using combined bisulfite restriction analysis (COBRA), nine CpG sites (including CpG-1) were confirmed to exhibit significant differences in their age-dependent methylation levels. Eight CpG sites showed an age-dependent increase in their methylation levels, whereas only one site showed age-dependent hypomethylation; in particular, these changes in methylation levels occurred rapidly at a young age. COBRA revealed low methylation levels in some CpG regions in the majority of the IVF blastocyst-stage embryos derived from spermatozoa at JD2-5. Interestingly, bulls with different ages did not show differences in their methylation levels. In conclusion, our findings indicated that methylation levels at nine CpG sites in spermatozoa changed with increasing age and that some CpG regions were demethylated after fertilization. Further studies are required to determine whether age-dependent different methylation levels in bull spermatozoa can affect fertility.
Keywords: glycogen, moisture content, Japanese wagyu beef, FT-NIR, PLSR (MSC) yielded optimum results with R p 2 of 0.795, RMSEP of 2.669%, and RPD of 2.008. The results of this study demonstrated that NIR spectroscopy offers great potential for the prediction of glycogen and moisture contents in Japanese wagyu beef samples. effect on Japanese consumers' preference owing to the improvement in beef quality such as tenderness. (2)(3)(4)(5)(6)(7) This is consistent with the conclusion that tenderness is the most important factor affecting beef palatability. (8)(9)(10)(11) However, additional studies have shown that when tenderness is at an acceptable level, flavor becomes the next most important factor affecting the beef preference of consumers. (10)(11)(12)(13)(14)(15) Flavor is a complex concept, which is composed of taste, odor, and the interaction of these factors. In our previous work, a sensory panel test was used to determine the relationship between sensory attributes (e.g., sweetness, fattiness, aroma, tenderness, flavor, and overall evaluation) and chemical composition characteristics (e.g., moisture, protein, free amino acid, glycogen, and fatty acid contents) of Japanese wagyu beef by the simmering method. (16) We demonstrated that the 'flavor' of sensory attributes was associated with glycogen and moisture contents. It has been widely reported that pre rigor muscle glycogen content has a negative curvilinear relationship with ultimate pH, (17) which is an indicator of the final palatability of meat. (18,19) In addition, the glycogen content in the muscle is related to the amounts of monosaccharides such as glucose and fructose after slaughter, which affect the development of meat flavor via the Maillard reaction; therefore, glycogen contributes to beef palatability. (20) Moisture content is often used to assess meat quality. (21) It also has a strong relationship with the contents of lipids that affect sensory attributes such as flavor, juiciness, texture, and appearance. (22) Therefore, to satisfy an increasing demand for evaluating meat quality by either the meat processing industry or consumers, fast, accurate, and nondestructive methods are urgently required.In recent years, near-infrared (NIR) spectroscopy, which is based on optical measurements of reflectance, transmittance, and interactance, has been considered as a nondestructive, fast, convenient, inexpensive, and precise technique. NIR spectroscopy combined with various multivariable data processing techniques has been effectively employed. Applications of the NIR technique to the evaluation of meat quality have been reviewed. (23) The NIR technique has the potential of detecting meat adulteration, (24,25) assessing meat microbial spoilage, (26,27) and estimating meat quality. (28,29) Nowadays, several research studies on Japanese wagyu beef have shown that NIR spectroscopy can be applied to predict the fat content and quantify the fatty acid composition. Kobayashi et al. have demonstrated the correlation between fat content and spectral infor...
Intensive use of a few elite sires has increased the risk of the manifestation of deleterious recessive traits in cattle. Substantial genotyping data gathered using single-nucleotide polymorphism (SNP) arrays have identified the haplotypes with homozygous deficiency, which may compromise survival. We developed Japanese Black cattle haplotypes (JBHs) using SNP array data (4843 individuals) and identified deleterious recessive haplotypes using exome sequencing of 517 sires. We identified seven JBHs with homozygous deficiency. JBH_10 and JBH_17 were associated with the resuming of estrus after artificial insemination, indicating that these haplotypes carried deleterious mutations affecting embryonic survival. The exome data of 517 Japanese Black sires revealed that AC_000165.1:g.85341291C>G of IARS in JBH_8_2, AC_000174.1:g.74743512G>T of CDC45 in JBH_17, and a copy variation region (CNVR_27) of CLDN16 in JBH_1_1 and JBH_1_2 were the candidate mutations. A novel variant AC_000174.1:g.74743512G>T of CDC45 in JBH_17 was located in a splicing donor site at a distance of 5 bp, affecting pre-mRNA splicing. Mating between heterozygotes of JBH_17 indicated that homozygotes carrying the risk allele died around the blastocyst stage. Analysis of frequency of the CDC45 risk allele revealed that its carriers were widespread throughout the tested Japanese Black cattle population. Our approach can effectively manage the inheritance of recessive risk alleles in a breeding population.
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