Effects of Slaughter Age on Myosin Heavy Chain Isoforms, Muscle Fibers, Fatty Acids, and Meat Quality in Longissimus Thoracis Muscle of Tibetan Sheep

Integration analysis of transcriptome and metabolome revealed the potential mechanism of spermatogenesis in Tibetan sheep (Ovis aries) at extreme high altitude

Testis has an indispensable function in male reproduction of domestic animals. Numerous genes and metabolites were related to testicular development and spermatogenesis. However, little is known about the biological regulation pathways associated with fecundity in male Tibetan sheep. In this study, Testes were collected from Huoba Tibetan sheep (HB, 4614 m) and Gangba Tibetan sheep (GB, 4401 m) at extreme high altitude, and Alpine Merino sheep (AM, 2500 m, control group) at medium-high altitude, investigating the genes and metabolites levels of them. The histological analysis of testicular tissue using hematoxylin-eosin (HE) staining was performed for Tibetan sheep and Alpine Merino sheep, and the testes of them were analyzed by transcriptomics and metabolomics to explore the potential mechanism of testicular development and spermatogenesis. The statistical results showed that the cross-sectional area of testicular seminiferous tubules, diameter of seminiferous tubules, and spermatogenic epithelium thickness were significantly smaller in HB and GB than in AM (P < 0.05). Overall, 5648 differentially expressed genes (DEGs) and 336 differential metabolites (DMs) were identified in three sheep breeds, which were significantly enriched in spermatogenesis and other related pathways. According to integrated metabolomic and transcriptomic analysis, glycolysis/gluconeogenesis, AMPK signaling pathway, and TCA cycle, were predicted to have dramatic effects on the spermatogenesis of Tibetan sheep. Several genes (including Wnt2, Rab3a, Sox9, Hspa8, and Slc38a2) and metabolites (including L-histidinol, Glucose, Fumaric acid, Malic acid, and Galactose) were significantly enriched in pathways related to testicular development and spermatogenesis, and might affect the reproduction of Tibetan sheep by regulating the acrosome reaction, meiotic gene expression, and the production of sex hormones. Our results provide further understanding of the key genes and metabolites involved in testicular development and spermatogenesis in Tibetan sheep.

A comprehensive study of CYP2E1 and its role in carcass characteristics and chemical lamb meat quality in different Indonesian sheep breeds

The role of CYP2E1 in oxidation is essential for its effects on meat quality. This study used 200 Indonesian sheep (Ovis aries) to determine the SNP g allele frequencies. g. 50658168 T>C of CYP2E1 gene located in 3´-UTR region and their genetic association with lamb quality traits, including carcass characteristics, retail cut carcass, physicochemical lamb, fatty acid, cholesterol, flavor and odor, and mineral content. Further, the level of CYP2E1 mRNA and CYP2E1 protein expression in muscle were determined and correlated with lamb quality traits. CYP2E1 gene polymorphisms were identified using Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) analysis. The CYP2E1 mRNA expression levels in phenotypically divergent sheep populations were analyzed using Quantitative Real Time-PCR (qRT-PCR). Immunohistochemistry (IHC) and hematoxylin-eosin (HE) staining analysis used three samples each in the high and low lamb quality groups based on pH value and tenderness. An association study of CYP2E1 gene polymorphisms was performed using General Linear Model (GLM) analysis. The genetic association between the CC, CT, and TT genotypes at the SNP g. 50658168 T>C CYP2E1 gene and lamb quality traits were significant (P<0.05), including carcass characteristics, retail cut carcass, fatty acid, cholesterol, flavor, and odor. Lambs with the CT genotype had a higher mRNA and protein expression in high lamb quality traits. The highest CYP2E1 protein expression was localized in the longissimus dorsi. The group sample with high lamb quality had a higher area and perimeter of muscle cells. CYP2E1 can be used as a genetic marker for selecting sheep with high meat quality.

Comprehensive analysis of the expression patterns and function of the FTO-LINE1 axis in yak tissues and muscle satellite cells

Background

The long interspersed nuclear element 1 (LINE1) retrotransposon has been identified as a specific substrate for fat mass and obesity-related gene (FTO), which facilitates the removal of N6-methyladenosine modifications from its targeted RNAs.

Methods

This study examined the dynamic interaction between FTO and LINE1 in yak tissues and muscle satellite cells, utilizing RT-qPCR, RNA immunoprecipitation (RIP), immunofluorescence staining, and techniques involving overexpression and interference of FTO and LINE1 to elucidate the relationship between FTO and LINE1 in yak tissues and muscle satellite cells.

Results

Cloning and analysis of the FTO coding sequence in Jiulong yak revealed a conserved protein structure across various Bos breeds, with notable homology observed with domestic yak, domestic cattle, and Java bison. Comprehensive examination of FTO and LINE1 gene expression patterns in Jiulong yaks revealed consistent trends across tissues in both sexes. FTO mRNA levels were markedly elevated in the heart and kidney, while LINE1 RNA was predominantly expressed in the heart. Immunoprecipitation confirmed the direct interaction between the FTO protein and LINE1 RNA in yak tissues and muscle satellite cells. The FTO-LINE1 axis was confirmed by a significant decrease in LINE1 RNA enrichment following its expression interference in yak muscle satellite cells. Overexpression of FTO substantially reduced the expression of recombinant myogenic factor 5 (MYF5). However, FTO interference had no discernible effect on MYF5 and myoblast determination protein 1 (MYOD1) mRNA levels. Immunofluorescence analysis revealed no alterations in Ki-67 protein expression following FTO interference or overexpression. However, phalloidin staining demonstrated enhancement in the myotube fusion rate of yak muscle satellite cells upon LINE1 interference.

Conclusion

This comprehensive mapping of the FTO and LINE1 mRNA expression patterns establishes a direct interaction between the FTO protein and LINE1 RNA in yak. The findings suggest that FTO overexpression promotes muscle satellite cells differentiation, whereas LINE1 negatively regulates myotube fusion. The study provides fundamental insights into the role of the FTO-LINE1 axis in determining the fate of muscle satellite cells in yak, laying a solid theoretical foundation for future investigations.

Characterisation of Dry-Salted Violino and Bresaola from Grass-Fed Bergamasca Sheep

This study focuses on characterising two seasoned products, violino and bresaola, derived from grass-fed Bergamasca sheep monitored with a GPS system. The evaluation includes both nutritional and sensory aspects. Results reveal that both products boast a high protein content (approximately 40%) and a beneficial fatty acid profile, endorsing a healthy n-6/n-3 ratio (2.2), along with rumenic acid (92-184 mg/100 g) and branched-chain fatty acids (BCFAs) (237-621 mg/100 g). The sensory evaluation highlights distinctive ovine characteristics in aroma and flavour. Violino and bresaola from grass-fed Bergamasca sheep showcase positive attributes for human consumption. The study emphasises the potential for added value to seasoned products from Bergamasca sheep through a traceable, sustainable, and health-conscious supply chain.

Expression profile and bioinformatics analysis of circRNA and its associated ceRNA networks in longissimus dorsi from Lufeng cattle and Leiqiong cattle

This paper aims to explore the role of circRNA expression profiles and circRNA-associated ceRNA networks in the regulation of myogenesis in the longissimus dorsi of cattle breeds surviving under subtropical conditions in southern China by RNA sequencing and bioinformatics analysis. It also aims to provide comprehensive understanding of the differences in muscle fibers in subtropical cattle breeds and to expand the knowledge of the molecular networks that regulate myogenesis. With regard to meat quality indicators, results showed that the longissimus dorsi of LQC had lower pH (P < 0.0001), lower redness (P < 0.01), lower shear force (P < 0.05), and higher brightness (P < 0.05) than the longissimus dorsi of LFC. With regard to muscle fiber characteristics, the longissimus dorsi of LQC had a smaller diameter (P < 0.0001) and higher density of muscle fibers (P < 0.05). The analysis results show that the function of many circRNA-targeted mRNAs was related to myogenesis and metabolic regulation. Furthermore, in the analysis of the function of circRNA source genes, we hypothesized that btacirc_00497 and btacirc_034497 may regulate the function and type of myofibrils by affecting the expression of MYH6, MYH7, and NEB through competitive linear splicing.

Expression of MSTN/Smad signaling pathway genes and its association with meat quality in Tibetan sheep (Ovis aries)

Tibetan sheep is a unique breed living in Qinghai-Tibet Plateau. Since MSTN/Smad signaling pathway plays a critical role in the regulation of muscle development, we aimed to study the mutton quality, mRNA expression of main transduction genes in the MSTN/Smad signaling pathway, and the effects of those genes on the mutton quality of Tibetan sheep in this study. Six-month-old Qinghai-Tibetan sheep were selected, slaughtered, and their Longissimus lumborum, semitendinosus muscle, arm triceps, and quadriceps femoris muscle were collected. The mutton quality was evaluated, and gene expression and their association with the mutton quality were analyzed using RT-qPCR. The results showed that the indexes of mutton quality were not significantly different between ewes and rams (p > .05) except for Warner-Bratzler shear force (WBSF) (p < .05). A total of 21 different fatty acids were detected in the muscles of Tibetan sheep, including nine types of SFA, four types of MUFA, and eight types of PUFA. The main transduction genes of the MSTN/Smad signaling pathway were found to be widely expressed in muscle tissues, but no significant differences were observed (p > .05). The correlation analysis of the main genes and mutton quality showed that MSTN was significantly correlated with redness and cooking time; Smad2, Smad3, Smad4, and TGFβRI had significant positive correlations with marbling in arm triceps; Smad3 and TGFβRII had strong negative correlations with pH24 h in Longissimus lumborum; Smad2 was negatively correlated with drip loss in Longissimus lumborum. In short, the expression level of MSTN in muscles was positively correlated with Smad2, Smad3, and Smad4 genes and negatively correlated with TGFβRII genes. Thus, the results of this study provide a theoretical basis for the regulation mechanism of the MSTN/Smad pathway on mutton quality.

Applications of lipidomics in goat meat products: Biomarkers, structure, nutrition interface and future perspectives

Goat meat, as a superior product including low lipids, low cholesterol contents and high-quality proteins, becomes the superior food for the national market. With the increasing demand for goat meat, the production, sensory quality and physicochemical properties of goat meat are also widely observed. Following significant discoveries on the mechanism determining goat meat quality, further research on complex and interactive factors leading to changes of goat meat quality is increasingly based on data-driven "omics" methods, such as lipidomics, which can rapidly identify and quantify >1000 lipid species at same time facilitating comprehensive analyses of lipids in tissues. Molecular mechanism and biomarkers indicating the changes of goat meat quality, authentication, meat analogue, nutrition and health by lipidomics are feasible. According to the analysis results of the classes and of different biomarkers lipids of goat meat quality, the main processes involved the biosynthesis of unsaturated fatty acids, associations with lipids and proteins, lipid oxidation, lipid hydrolysis, lipid degradation, lipid deposition and lipid denaturation, which have been translated into advanced technologies for identifying the goat meat adulteration and faux meat rapidly and accurately. SIGNIFICANCE: In this review, the research of lipidomics technology, past applications, recent findings and common on the recent advances of lipidomics in the quality assessment of mutton products by lipidomics with MS approaches have been summarized. The information reported in review can serve as a reference to characterize the lipids found in mutton, clarify the application of lipidomics to the field of mutton products and provide new perspectives in producing superior quality mutton products.

Transcriptomic Study of Spermatogenesis in the Testis of Hu Sheep and Tibetan Sheep

Numerous genes involved in male reproduction regulate testis development and spermatogenesis. In this study, the testis tissue transcriptome was used to identify candidate genes and key pathways associated with fecundity in sheep. Histological analysis of testis tissue using hematoxylin-eosin (HE) routine staining was performed for two sheep breeds. Overall, 466 differentially expressed genes (DEGs) were identified between Hu sheep (HS) and Tibetan sheep (TS) through RNA sequencing technology (RNA-Seq), including 226 upregulated and 240 downregulated genes. Functional analysis showed that several terms and pathways, such as "protein digestion and absorption", "cAMP signaling pathway", "focal adhesion", and "p53 signaling pathway" were closely related to testis development and spermatogenesis. Several genes (including COL1A1, COL1A2, COL3A1, SOX9, BCL2, HDC, and GGT5) were significantly enriched in these terms and pathways and might affect the reproduction of sheep by regulating the migration of spermatogenic cells, apoptosis of spermatogenic cells, and secretion of sterol hormones via testicular interstitial cells. Our results provide a theoretical basis for better understanding the molecular mechanisms of reproduction in sheep.

MicroRNA and circular RNA profiling in the deposited fat tissue of Sunite sheep

As the most typical deposited fat, tail fat is an important energy reservoir for sheep adapted to harsh environments and plays an important role as a raw material in daily life. However, the regulatory mechanisms of microRNA (miRNA) and circular RNA (circRNA) in tail fat development remain unclear. In this study, we characterized the miRNA and circRNA expression profiles in the tail fat of sheep at the ages of 6, 18, and 30 months. We identified 219 differentially expressed (DE) miRNAs (including 12 novel miRNAs), which exhibited a major tendency to be downregulated, and 198 DE circRNAs, which exhibited a tendency to be upregulated. Target gene prediction analysis was performed for the DE miRNAs. Functional analysis revealed that their target genes were mainly involved in cellular interactions, while the host genes of DE circRNAs were implicated in lipid and fatty acid metabolism. Subsequently, we established a competing endogenous RNA (ceRNA) network based on the negative regulatory relationship between miRNAs and target genes. The network revealed that upregulated miRNAs play a leading role in the development of tail fat. Finally, the ceRNA relationship network with oar-miR-27a_R-1 and oar-miR-29a as the core was validated, suggesting possible involvement of these interactions in tail fat development. In summary, DE miRNAs were negatively correlated with DE circRNAs during sheep tail fat development. The multiple ceRNA regulatory network dominated by upregulated DE miRNAs may play a key role in this developmental process.

Lactobacillus improves meat quality in Sunit sheep by affecting mitochondrial biogenesis through the AMPK pathway

Sunit sheep are famous for their high meat quality, but the meat quality of them has declined due to the change in feeding methods. Lactobacillus has a variety of probiotic effects and is widely used in animal diets to optimize meat quality. This study aimed to investigate the effect of dietary supplementation with different levels of Lactobacillus on meat quality. A total of 24 3-month-old Sunit sheep with an average body weight of 19.03 ± 3.67 kg were randomly divided into control (C), 1% (L1), 2% (L2), and 3% Lactobacillus groups (L3), with 6 sheep in each group. Myofiber characteristics, meat quality, and metabolic enzyme activity were detected. Moreover, the regulatory mechanism of Lactobacillus on meat quality was explored by using Western blotting and real-time Quantitative polymerase chain reaction (RT-qPCR). The results showed that dietary addition of Lactobacillus decreased LDH activity in the Biceps femoris of Sunit sheep (P < 0.05). Compared to the other groups, the 1% Lactobacillus group showed the conversion of myofibers from the glycolytic to the oxidative type, and the increasing b* values (P < 0.05), decreasing shear force and cooking loss of meat (P < 0.05) and the relative gene and protein expression levels of AMPK, PGC-1α, NRF1, TFAM, and COX IV (P < 0.05) in the Biceps femoris were also increased in the 1% Lactobacillus group. Therefore, the addition of Lactobacillus to the diet of Sunit sheep could regulate the AMPK signaling pathway to promote myofiber type conversion, which improves meat quality. This study provided a theoretical and data basis for improving the meat quality of sheep and supplied a novel way of applying Lactobacillus.

Fortification of diets with omega-3 long-chain polyunsaturated fatty acids enhances feedlot performance, intramuscular fat content, fat melting point, and carcass characteristics of Tattykeel Australian White MARGRA lambs

Meat eating quality indices such as intramuscular fat content (IMF) and fat melting point (FMP) of the Longissimus thoracis et lumborum muscle and the feedlot performance, carcass traits, and commercial wholesale cuts of lot-fed Tattykeel Australian White (TAW) MARGRA lambs as a result of dietary fortification of the diet with omega-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFA) were evaluated. A total of 75 TAW MARGRA lambs at 6 months of age with an average liveweight of 30 ± 1.2 kg were used. The lambs were randomly allocated to the following three dietary treatments of 25 lambs each in a 47-day feeding trial using a completely randomized experimental design: (1) control diet of hay plus pellets without omega-3 oil, (2) hay plus commercial whole grain pellets (MSM) without omega-3 oil, and (3) hay plus pellets fortified with omega-3 oil. It was hypothesized that dietary supplementation with omega-3 fortified pellets will improve feedlot performance, meat-eating quality indices of IMF, FMP, and carcass characteristics. Lot-fed lambs on the MSM whole grain had the highest feed intake of 1.69 kg/day, followed by the control at 1.57 kg/day and the lowest in the omega-3 diet at 1.01 kg/day (p = 0.0001). However, the omega-3 diet had the highest average daily gain of 230 g/head/day (p = 0.0001), indicating the greatest feed efficiency since it had the best growth response with minimal feed intake. Post-slaughter evaluation of the Longissimus thoracis et lumborum muscle revealed significant treatment variations in IMF (p = 0.0001), FMP (p = 0.0001), pH (p = 0.0380), and wholesale French rack primal cut (p = 0.0001). Strong correlations (p < 0.05) between liveweight, temperature, pH, FMP, and IMF were observed. Similarly, significant correlations between carcass characteristics of total saleable meat yield, lean trim, fat trims, bones, and leg shank were evident (p < 0.05). However, there were no treatment differences in the final liveweight, GR fat depth, hot standard carcass weight, or dressing percentage. The findings indicate that feedlot performance, meat-eating quality traits such as IMF and FMP, and commercial wholesale French rack cuts can be further improved during feedlot finishing of TAW MARGRA lambs through dietary supplementation with omega-3 oils, and hence the tested hypothesis of improved meat quality attributes is partially confirmed.

Advances in application of ultrasound in meat tenderization: A review

Tenderness could measure the eating quality of meat. The mechanism of muscle tenderization is becoming more and more critical in the past decade. Since the transforming of muscle into edible meat requires a complex physiological and biochemical process, the related tenderization of meat can be beneficial to improving the meat quality. As a non-thermal processing technology with energy-saving, environmental protection, and intense penetration, ultrasonic treatment has been widely used in the tenderizing process of meat products. In this paper, the principle of meat tenderization, the ultrasonic technology, and the application of ultrasonic technology in meat tenderization is summarized. The effect of ultrasonic technology on the tenderization of meat products is discussed from different perspectives (muscle fibers and connective tissue properties).

Comparative Transcriptome Analysis Reveals the Mechanism Associated With Dynamic Changes in Meat Quality of the Longissimus Thoracis Muscle in Tibetan Sheep at Different Growth Stages

Tibetan sheep are mainly distributed in the Qinghai–Tibet Plateau. Its meat is not only essential for the local people but also preferred by the non-inhabitant of this plateau also. To investigate the salient development features and molecular mechanism of the meat difference of LT muscle caused by different growth stages in Tibetan sheep, the carcass performance, meat quality, and comparative transcriptome analysis were performed for investigating the potential molecular mechanism of the meat quality difference of the LT muscle caused by four growth stages [4-months old (4 months), 1.5-years old (1.5 years), 3.5-years old (3.5 years), and 6-years old (6 years)] in the Tibetan sheep. The shear force increased with the increase of age (p < 0.05) while the intramuscular fat (IMF) was the highest at 1.5 y. The AMPK signaling pathway was significantly enriched in the four comparative groups. The weighted gene co-expression network analysis (WGCNA) results showed that the hub genes P4HA2, FBXL4, and PPARA were identified to regulate the meat quality. In summary, 1.5 years was found to be the most suitable slaughter age of the Tibetan sheep which ensured better meat tenderness and higher IMF content. Moreover, the genes LIPE, LEP, ADIPOQ, SCD, and FASN may regulate the transformation of the muscle fiber types through the AMPK signaling pathway, further affecting the meat quality.

Characterization of the circRNA–miRNA–mRNA Network to Reveal the Potential Functional ceRNAs Associated With Dynamic Changes in the Meat Quality of the Longissimus Thoracis Muscle in Tibetan Sheep at Different Growth Stages

Circular RNAs (circRNAs) have a regulatory role in animal skeletal muscle development. In this study, RNA sequencing was performed to reveal the temporal regularity of circRNA expression and the effect of the circRNA–miRNA–mRNA ceRNA regulatory network on the meat quality of longissimus thoracis (LT) muscle in Tibetan sheep at different growth stages (4 months old, 4 m; 1.5 years old, 1.5 y; 3.5 years old, 3.5 y; 6 years old, 6 y). There were differences in the carcass performance and meat quality of Tibetan sheep at different ages. Especially, the meat tenderness significantly decreased (p &lt; 0.05) with the increase of age. GO functional enrichment indicated that the source genes of the DE circRNAs were mainly involved in the protein binding, and myofibril and organelle assembly. Moreover, there was a significant KEGG enrichment in the adenosine 5′-monophosphate (AMP)-activated protein kinase (AMPK) signaling pathway, as well as the calcium signaling pathway, regulating the pluripotency of the stem cells. The circRNA–miRNA–mRNA ceRNA interaction network analysis indicated that circRNAs such as circ_000631, circ_000281, and circ_003400 combined with miR-29-3p and miR-185-5p regulate the expression of LEP, SCD, and FASN related to the transformation of muscle fiber types in the AMPK signaling pathway. The oxidized muscle fibers were transformed into the glycolytic muscle fibers with the increase of age, the content of intramuscular fat (IMF) was lowered, and the diameter of the muscle fiber was larger in the glycolytic muscle fibers, ultimately increasing the meat tenderness. The study revealed the role of the circRNAs in the transformation of skeletal muscle fiber types in Tibetan sheep and its influence on meat quality. It improves our understanding of the role of circRNAs in Tibetan sheep muscle development.