Linsen Zan

Effects of trehalose supplementation on semen quality and oxidative stress variables in frozen-thawed bovine semen.

The antioxidant systems of superoxide dismutase (SOD), catalase (CAT), reduced glutathione (GSH), and glutathione peroxidase (GSH-Px) are important in maintaining sperm motility and viability. The purpose of this study was to determine the effects of varying doses of trehalose on in vitro semen quality variables and antioxidant activities of frozen-thawed bovine semen. The semen samples, diluted with an extender containing trehalose (0, 25, 50, 100, and 200 mM), were evaluated. The extender supplemented with 100 mM trehalose exhibited the greatest percentages of sperm motility, acrosomal membrane integrity, and plasma membrane integrity in comparison with the control group (P < 0.05). No difference was observed for sperm motility between trehalose 50 and 100 mM groups (P > 0.05). Extender supplemented with trehalose did not affect SOD levels. Compared with the other groups, CAT was greater with the supplementation of trehalose at 100 and 200 mM (P < 0.05). The extender supplemented with trehalose had enhanced GSH-Px activity compared with the control group (P < 0.05). However, increasing the doses of trehalose (100, 200 mM) decreased GSH-Px activity, compared with 50 mM trehalose (P < 0.05). Compared with the other groups, trehalose at the concentration of 25 and 50 mM increased GSH activity (P < 0.05). The application of 200 mM trehalose produced the least amount of GSH activity among all of the groups (P < 0.05). In conclusion, extender supplemented with trehalose reduced the oxidative stress induced by freeze-thaw and improved measures of bovine semen quality. The antioxidant characteristics of trehalose may be related to its effectiveness in membrane cryopreservation. Further studies are required to obtain more concrete results on the determination of lipid peroxidation and antioxidant capacities of trehalose in cryopreserved bovine semen.

Muscle transcriptomic analyses in Angus cattle with divergent tenderness

Beef tenderness contributes significantly to variation of beef palatability, and is largely influenced by various genetic and environmental factors. To identify candidate genes and pathways related to beef tenderness, we analyzed the longissimus dorsi (LD) muscle of Angus cattle that had different degrees of tenderness, measured by Warner–Bratzler shear force (WBSF). Microarray and RT-PCR analyses identified 53 genes that were differentially expressed in LD samples categorized as either tough or tender, including myosin, heavy chain 3 skeletal muscle embryonic (MYH3), myosin heavy chain 8 skeletal muscle perinatal (MYH8), guanylate binding protein 5 (GBP5), fatty acid binding protein 4 (FABP4), Stearoyl-coenzyme A desaturase (SCD), Fatty acid synthase (FASN), ubiquitin-like with PHD and ring finger domains 1 (UHRF1). Most of these genes are involved in lipid metabolism and skeletal muscle contraction. Employing Gene ontology (GO) and Ingenuity Pathway Analysis (IPA), several GO terms and pathways were found to be related to hydrolase, peptidase and GTPase activity, lipid metabolism, small molecule biochemistry, molecular transport, and tissue development. Overall, this analysis provides insight into the metabolic relationships between muscle biology and beef quality.

Melatonin regulates the development and function of bovine Sertoli cells via its receptors MT1 and MT2

Melatonin and its receptors are found in the testis of many species, where they mediate testicular functions. The present study aimed to investigate the expression of melatonin receptors (MT1 and MT2) in bovine Sertoli cells (SCs), using reverse transcription polymerase chain reaction (RT-PCR) and western blot. In addition, we assessed the mRNA levels of spermatogenesis-related genes (real-time PCR) and secretion of inhibin B after treatment with various concentrations (0, 80, 160, and 320 pg/mL) of melatonin at different time points (24, 48, or 72 h). We found that bovine SCs express MT1 and MT2 receptors, which were regulated by melatonin in time- and dose-dependent manners after treatment with melatonin. Exogenous melatonin up-regulated the expression of spermatogenesis-related genes, including Cyclin D1, Cyclin E, Pdgfa, Dhh, Occludin, and Claudin, and decreased the mRNA levels of P21 and Kit1 in a time or dose-dependent manner. Meanwhile, melatonin supplementation significantly affected Inhba, Inhbb and Inha mRNA expression. These findings were consistent with inhibin B levels detected in the culture medium. In conclusion, exogenous melatonin acts via its receptors and appears to play regulatory roles in the development and function of bovine SCs.

OLFML3 Expression is Decreased during Prenatal Muscle Development and Regulated by MicroRNA-155 in Pigs

The Olfactomedin-like 3 (OLFML3) gene has matrix-related function involved in embryonic development. MicroRNA-155 (miR-155), 21- to 23-nucleotides (nt) noncoding RNA, regulated myogenesis by target mRNA. Our LongSAGE analysis suggested that OLFML3 gene was differently expressed during muscle development in pig. In this study, we cloned the porcine OLFML3 gene and detected its tissues distribution in adult Tongcheng pigs and dynamical expression in developmental skeletal muscle (12 prenatal and 10 postnatal stages) from Landrace (lean-type) and Tongcheng (obese-type) pigs. Subsequently, we analyzed the interaction between OLFML3 and miR-155. The OLFML3 was abundantly expressed in liver and pancreas, moderately in lung, small intestine and placenta, and weakly in other tissues and postnatal muscle. There were different dynamical expression patterns between Landrace and Tongcheng pigs during prenatal skeletal muscle development. The OLFML3 was down-regulated (33-50 days post coitus, dpc), subsequently up-regulated (50-70 dpc), and then down-regulated (70-100 dpc) in Landrace pigs, while in Tongcheng pigs, it was down-regulated (33-50 dpc), subsequently up-regulated (50-55 dpc) and then down-regulated (55-100 dpc). There was higher expression in Tongcheng than Landrace in prenatal muscle from 33 to 60 dpc, and opposite situation from 65 to 100 dpc. Dual luciferase assay and real time PCR documented that OLFML3 expression was regulated by miR-155 at mRNA level. Our research indicated that OLFML3 gene may affect prenatal skeletal muscle development and was regulated by miR-155. These finding will help understanding biological function and expression regulation of OLFML3 gene in mammal animals.

Novel polymorphisms of SIX4 gene and their association with body measurement traits in Qinchuan cattle.

Sine oculis homeobox homolog 4 (SIX4) gene belongs to the sine oculis/SIX gene family, which includes six members in vertebrates. SIX4 gene plays a crucial role in skeletal myogenesis, and its genetic variations or deficiency may cause hypopituitarism, suggesting that SIX4 gene is a potential candidate gene affecting body measurement traits (BMTs) in animals. Herein, the objectives of this study were to identify genetic polymorphisms of bovine SIX4 gene and to analyze potential association between single nucleotide polymorphisms (SNPs) and body measurement traits in Qinchuan cattle. In the present study, we investigated polymorphisms of SIX4 gene in 426 Qinchuan cattle using DNA sequencing and polymerase chain reaction-restriction fragment length polymorphisms. Three novel SNPs were identified within bovine SIX4 gene. Associations between body measurement traits and SIX4 gene polymorphisms were investigated, and significant statistical associations were found between polymorphisms of these three SNPs and body measurement traits (P<0.05). Hence, based on results obtained from this study, we conjectured that SIX4 gene may have potential effects on body measurement traits in Qinchuan cattle population and could be used for marker-assisted selection.

Functional Genomic Analysis of Variation on Beef Tenderness Induced by Acute Stress in Angus Cattle

Beef is one of the leading sources of protein, B vitamins, iron, and zinc in human food. Beef palatability is based on three general criteria: tenderness, juiciness, and flavor, of which tenderness is thought to be the most important factor. In this study, we found that beef tenderness, measured by the Warner-Bratzler shear force (WBSF), was dramatically increased by acute stress. Microarray analysis and qPCR identified a variety of genes that were differentially expressed. Pathway analysis showed that these genes were involved in immune response and regulation of metabolism process as activators or repressors. Further analysis identified that these changes may be related with CpG methylation of several genes. Therefore, the results from this study provide an enhanced understanding of the mechanisms that genetic and epigenetic regulations control meat quality and beef tenderness.

Novel extraction method of genomic DNA suitable for long-fragment amplification from small amounts of milk

Isolation of genomic DNA is a prerequisite for assessment of milk quality. As a source of genomic DNA, milk somatic cells from milking ruminants are practical, animal friendly, and cost-effective sources. Extracting DNA from milk can avoid the stress response caused by blood and tissue sampling of cows. In this study, we optimized a novel DNA extraction method for amplifying long (>1,000 bp) DNA fragments and used it to evaluate the isolation of DNA from small amounts of milk. The techniques used for the separation of milk somatic cell were explored and combined with a sodium dodecyl sulfate (SDS)-phenol method for optimizing DNA extraction from milk. Spectrophotometry was used to determine the concentration and purity of the extracted DNA. Gel electrophoresis and DNA amplification technologies were used for to determine DNA size and quality. The DNA of 112 cows was obtained from milk (samples of 13 ± 1 mL) and the corresponding optical density ratios at 260:280 nm were between 1.65 and 1.75. Concentrations were between 12 and 45 μg/μL and DNA size and quality were acceptable. The specific PCR amplification of 1,019- and 729-bp bovine DNA fragments was successfully carried out. This novel method can be used as a practical, fast, and economical mean for long genomic DNA extraction from a small amount of milk.

miRNA-dysregulation associated with tenderness variation induced by acute stress in Angus cattle

AbstractmiRNAs are a class of small, single-stranded, non-coding RNAs that perform post-transcriptional repression of target genes by binding to 3’ untranslated regions. Research has found that miRNAs involved in the regulation of many metabolic processes. Here we uncovered that the beef quality of Angus cattle sharply diversified after acute stress. By performing miRNA microarray analysis, 13 miRNAs were significantly differentially expressed in stressed group compared to control group. Using a bioinformatics method, 135 protein-coding genes were predicted as the targets of significant differentially expressed miRNAs. Gene Ontology (GO) term and Ingenuity Pathway Analysis (IPA) mined that these target genes involved in some important pathways, which may have impact on meat quality and beef tenderness.

A novel polymorphism of the MYPN gene and its association with meat quality traits in Bos taurus.

Myopalladin (MYPN) is a multifunctional protein that maintains sarcomeric integrity and regulates Z-line structure. It is an important candidate gene for meat quality selection through marker-assisted selection. Using PCR-RFLP technology, we discovered a single-nucleotide polymorphism (SNP) (A1795G in exon 9) of the MYPN gene. Allele frequencies of this SNP were investigated and evaluated by the chi(2) test in 660 cattle populations in China; only the Nanyang population was not in Hardy-Weinberg equilibrium. Gene heterozygosity, effective allele number and polymorphism information content of the bovine MYPN locus in seven populations varied from 0.3888 to 0.4998, 1.6360 to 1.9992, and 0.3132 to 0.3749, respectively. We also looked for a potential association of this SNP with ultrasound traits in 399 individuals and found a significant effect on the ultrasound loin-muscle area. Meat quality traits were analyzed in another 61 Qinchuan individuals to analyze associations with genotype. Animals with the genotype GG had higher mean values for loin-eye area (P < 0.05) and water-holding capacity (P < 0.01) than those with AA or AG genotypes. We conclude that this SNP of the MYPN gene has potential as a genetic marker for meat quality traits in cattle reproduction and breeding.

An Optimized Trichloroacetic Acid/Acetone Precipitation Method for Two-Dimensional Gel Electrophoresis Analysis of Qinchuan Cattle Longissimus Dorsi Muscle Containing High Proportion of Marbling

Longissimus dorsi muscle (LD) proteomics provides a novel opportunity to reveal the molecular mechanism behind intramuscular fat deposition. Unfortunately, the vast amounts of lipids and nucleic acids in this tissue hampered LD proteomics analysis. Trichloroacetic acid (TCA)/acetone precipitation is a widely used method to remove contaminants from protein samples. However, the high speed centrifugation employed in this method produces hard precipitates, which restrict contaminant elimination and protein re-dissolution. To address the problem, the centrifugation precipitates were first grinded with a glass tissue grinder and then washed with 90% acetone (TCA/acetone-G-W) in the present study. According to our result, the treatment for solid precipitate facilitated non-protein contaminant removal and protein re-dissolution, ultimately improving two-dimensional gel electrophoresis (2-DE) analysis. Additionally, we also evaluated the effect of sample drying on 2-DE profile as well as protein yield. It was found that 30 min air-drying did not result in significant protein loss, but reduced horizontal streaking and smearing on 2-DE gel compared to 10 min. In summary, we developed an optimized TCA/acetone precipitation method for protein extraction of LD, in which the modifications improved the effectiveness of TCA/acetone method.