Gene expression identifies metabolic and functional differences between intramuscular and subcutaneous adipocytes in cattle

Transcriptome and co-expression network analysis reveals the molecular mechanism of inosine monophosphate-specific deposition in chicken muscle

The inosine monophosphate (IMP) content in chicken meat is closely related to muscle quality and is an important factor affecting meat flavor. However, the molecular regulatory mechanisms underlying the IMP-specific deposition in muscle remain unclear. This study performed transcriptome analysis of muscle tissues from different parts, feeding methods, sexes, and breeds of 180-day-old Jingyuan chickens, combined with differential expression and weighted gene co-expression network analysis (WGCNA), to identify the functional genes that regulate IMP deposition. Out of the four comparison groups, 1,775, 409, 102, and 60 differentially expressed genes (DEGs) were identified, of which PDHA2, ACSS2, PGAM1, GAPDH, PGM1, GPI, and TPI1 may be involved in the anabolic process of muscle IMP in the form of energy metabolism or amino acid metabolism. WGCNA identified 11 biofunctional modules associated with IMP deposition. The brown, midnight blue, red, and yellow modules were strongly correlated with IMP and cooking loss (p < 0.05). Functional enrichment analysis showed that glycolysis/gluconeogenesis, arginine and proline metabolism, and pyruvate metabolism, regulated by PYCR1, SMOX, and ACSS2, were necessary for muscle IMP-specific deposition. In addition, combined analyses of DEGs and four WGCNA modules identified TGIF1 and THBS1 as potential candidate genes affecting IMP deposition in muscle. This study explored the functional genes that regulate muscle development and IMP synthesis from multiple perspectives, providing an important theoretical basis for improving the meat quality and molecular breeding of Jingyuan chickens.

Transcriptomics and Lipid Metabolomics Analysis of Subcutaneous, Visceral, and Abdominal Adipose Tissues of Beef Cattle

Fat deposition traits are influenced by genetics and environment, which affect meat quality, growth rate, and energy metabolism of domestic animals. However, at present, the molecular mechanism of fat deposition is not entirely understood in beef cattle. Therefore, the current study conducted transcriptomics and lipid metabolomics analysis of subcutaneous, visceral, and abdominal adipose tissue (SAT, VAT, and AAT) of Huaxi cattle to investigate the differences among these adipose tissues and systematically explore how candidate genes interact with metabolites to affect fat deposition. These results demonstrated that compared with SAT, the gene expression patterns and metabolite contents of VAT and AAT were more consistent. Particularly, SCD expression, monounsaturated fatty acid (MUFA) and triglyceride (TG) content were higher in SAT, whereas PCK1 expression and the contents of saturated fatty acid (SFA), diacylglycerol (DG), and lysoglycerophosphocholine (LPC) were higher in VAT. Notably, in contrast to PCK1, 10 candidates including SCD, ELOVL6, ACACA, and FABP7 were identified to affect fat deposition through positively regulating MUFA and TG, and negatively regulating SFA, DG, and LPC. These findings uncovered novel gene resources and offered a theoretical basis for future investigation of fat deposition in beef cattle.

Analyzing the interactions of mRNAs, miRNAs and lncRNAs to predict ceRNA networks in bovine cystic follicular granulosa cells

Cross-talk between competitive endogenous RNAs (ceRNAs) may play a critical role in revealing potential mechanism of bovine follicular cysts. Ovarian cyst has always been an intractable scientific problem and has led to considerable economic losses to bovine breeding industry. However, its pathogenesis and molecular mechanisms are still not well understood. Here, this study aimed to investigate the role of non-coding RNAs (ncRNAs) and the ceRNA networks in bovine follicular cyst. Whole transcriptome sequencing of bovine follicular granulosa cells (GCs) was conducted to obtain the expression profiles of mRNAs, lncRNAs and miRNAs. The results for the identified expressions of 8,003 mRNAs, 579 lncRNAs and 205 miRNAs were often altered between cystic and normal follicular GCs. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses were performed on these differentially expressed mRNAs. Furthermore, the ceRNA network combining mRNAs, miRNAs, and lncRNAs using several bioinformatics methods based on co-expression analysis between the differentially expressed RNAs was conducted. Finally, the lncRNA NONBTAT027373.1-miR-664b-HSD17B7 pathway was verified by dual-luciferase reporting assay and RNA binding protein immunoprecipitation (RIP) assay. LncRNA NONBTAT027373.1 sponged miR-664b in GCs and prevented miR-664b from binding to the HSD17B7 3′-UTR. These results indicated that genes and lncRNAs related to steroid hormone synthesis and energy metabolism could play important roles in the formation of bovine cystic follicles through the ceRNA mechanism and represent candidate targets for further research. This can be used as a practical guideline for promoting healthy and highly efficient development in the bovine industry.

Effect of Gender to Fat Deposition in Yaks Based on Transcriptomic and Metabolomics Analysis

Fat deposition in yaks plays an important part in survival, multiplication, and meat quality. In this work, the characteristic of fat deposition in male yaks (MYs) and female yaks (FYs) and the regulations of gender to yak fat deposition were explored by mRNA-Seq and non-targeted metabolomics analyses. FYs possessed a higher body fat rate (BFR) of visceral fat, fat content in longissimus dorsi (LD) and liver, and subcutaneous fat thickness (p < 0.05). The fat and cholesterol synthesis in liver and the fat transport in FY blood increased. The fat metabolism in yaks is the combined effect of carbohydrate, fatty acid, and amino acid metabolism by tricarboxylic acid (TCA) cycle, and an increase of triglyceride (TG) synthesis was accompanied by an increase of steroid synthesis. The high levels of myo-inositol and cortisol (COR) (p < 0.01) activated the calcium signaling in FY subcutaneous fat, followed by the increase of adipocyte secretion, and resulted in more leptin (LEP) secretion (p < 0.01). Then peroxisome proliferator-activated receptor (PPAR) signaling was activated by the focal adhesions and ECM-receptor interaction. Finally, the TG and steroid synthesis increased by the expression regulation of ME1, SCD, ELOVL6, DGAT2, DBI, LPL, CPT1, PLIN1, LIPA, DHCR24, and SQLE gene. The above genes can be considered as the candidate genes for yak with higher fat amount in molecular breeding in the future. This study can provide a theoretical basis for improving the meat quality and breeding of yaks.

Gene Expression Analysis Provides New Insights into the Mechanism of Intramuscular Fat Formation in Japanese Black Cattle

Japanese Black cattle (Japanese Wagyu) have a unique phenotype in which ectopic intramuscular fat accumulates in skeletal muscle, producing finely marbled beef. However, the mechanism of intramuscular fat formation in Japanese Black cattle remains unclear. To investigate the key genes involved in intramuscular fat accumulation, we comprehensively analyzed mRNA levels in subcutaneous and intramuscular fat tissues using RNA sequence (RNA-seq) analysis, which detected 27,606 genes. We identified eight key genes, namely carboxypeptidase E, tenascin C, transgelin, collagen type IV alpha 5 (COL4A5), cysteine and glycine-rich protein 2, PDZ, and LIM domain 3, phosphatase 1 regulatory inhibitor subunit 14A, and regulator of calcineurin 2. These genes were highly and specifically expressed in intramuscular fat tissue. Immunohistochemical analysis revealed a collagen network, including COL4A5, in the basement membrane around the intramuscular fat tissue. Moreover, pathway analysis revealed that, in intramuscular fat tissue, differentially expressed genes are related to cell adhesion, proliferation, and cancer pathways. Furthermore, pathway analysis showed that the transforming growth factor-β (TGF-β) and small GTPases regulators RASGRP3, ARHGEF26, ARHGAP10, ARHGAP24, and DLC were upregulated in intramuscular fat. Our study suggests that these genes are involved in intramuscular fat formation in Japanese Black cattle.

Review: An overview of beef production from pasture and feedlot globally, as demand for beef and the need for sustainable practices increase

Beef is a high-quality source of protein that also can provide highly desirable eating experiences, and demand is increasing globally. Sustainability of beef industries requires high on-farm efficiency and productivity, and efficient value-chains that reward achievement of target-market specifications. These factors also contribute to reduced environmental and animal welfare impacts necessary for provenance and social licence to operate. This review provides an overview of beef industries, beef production, and beef production systems globally, including more productive and efficient industries, systems and practices. Extensive beef production systems typically include pasture-based cow-calf and stocker-backgrounding or grow-out systems, and pasture or feedlot finishing. Cattle in pasture-based systems are subject to high levels of environmental variation to which specific genotypes are better suited. Strategic nutritional supplementation can be provided within these systems to overcome deficiencies in the amount and quality of pasture- or forage-based feed for the breeding herd and for younger offspring prior to a finishing period. More intensive systems can maintain more control over nutrition and the environment and are more typically used for beef and veal from dairy breeds, crosses between beef and dairy breeds, and during finishing of beef cattle to assure product quality and specifications. Cull cows and heifers from beef seedstock and cow-calf operations and dairy enterprises that are mostly sent directly to abattoirs are also important in beef production. Beef production systems that use beef breeds should target appropriate genotypes and high productivity relative to maintenance for the breeding herd and for growing and finishing cattle. This maximizes income and limits input costs particularly feed costs which may be 60% or more of production costs. Digital and other technologies that enable rapid capture and use of environmental and cattle performance data, even within extensive systems, should enhance beef industry productivity, efficiency, animal welfare and sustainability.

A conserved haplotype in Wagyu cattle contains RAB4A whose encoded protein regulates glucose trafficking in muscle and fat cells

The Wagyu breed of taurine cattle possess favourable genetics for intramuscular fat (IMF) but genomic loci associated with the trait remain under characterised. Here, we report the identification of a previously unidentified genomic region possessing a particular haplotype structure in Wagyu. Through deployment of a genome-wide haplotype detection analysis that captures regions conserved in a target population but not other populations we screened 100 individual Wagyu and contrasted them with 100 individuals from two independent comparison breeds, Charolais and Angus, using high-density SNPs. An extreme level of Wagyu conservation was assigned to a single genomic window (spanning genomic coordinates BTA28:41 088-300 265 bp). In fact, a five-SNP region spanning 27 096 bp is almost perfectly conserved among the 100 Wagyu individuals assayed and partially overlaps RAB4A. Focussing in, two consecutive SNPs (genomic coordinates 236 949 and 239 950) are apparently fixed within the Wagyu (BB and AA respectively), but at mixed frequencies in the other two breeds. These SNPs are located in the two introns straddling exon 7. In a separate analysis using the 1000 Bulls database, we found that, coincident with exon 7 of RAB4A first allele frequencies were highest in the high IMF Japanese Native (Wagyu) breeds (0.78) and lowest in the low IMF indicine breeds (Nelore and Brahman), with intermediate marbling breeds (Angus and Charolais) assigned intermediate rankings (0.42). RAB4A is known to encode a protein that regulates intracellular trafficking of the insulin-regulated glucose transporter GLUT4. RAB4A can be considered an attractive new positional candidate for IMF development.

Characterization of Breed Specific Differences in Spermatozoal Transcriptomes of Sheep in Australia

Reduced reproductive efficiency results in economic losses to the Australian sheep industry. Reproductive success, particularly after artificial insemination, is dependent on a number of contributing factors on both ewe and ram sides. Despite considerable emphasis placed on characterising ewe side contributions, little emphasis has been placed on characterising ram side contributions to conception success. Over 14,000 transcripts are in spermatozoa of other species, which are transferred to the ova on fertilisation. These transcripts conceivably influence early embryonic development and whether conception is successful. Semen was collected (n = 45) across three breeds; Merino, Dohne, and Poll Dorset. Following collection, each ejaculate was split in two; an aliquot was assessed utilising Computer Assisted Semen Analysis (CASA) and the remaining was utilised for RNA extraction and subsequent next-generation sequencing. Overall, 754 differentially expressed genes were identified in breed contrasts and contrast between ejaculates of different quality. Downstream analysis indicated that these genes could play significant roles in a broad range of physiological functions, including maintenance of spermatogenesis, fertilisation, conception, embryonic development, and offspring production performance. Overall results provide evidence that the spermatozoal transcriptome could be a crucial contributing factor in improving reproductive performance as well as in the overall productivity and profitability of sheep industries.

Genome-wide association study and pathway analysis for fat deposition traits in nellore cattle raised in pasture-based systems

Genome-wide association study (GWAS) is a powerful tool to identify candidate genes and genomic regions underlying key biological mechanisms associated with economically important traits. In this context, the aim of this study was to identify genomic regions and metabolic pathways associated with backfat thickness (BFT) and rump fat thickness (RFT) in Nellore cattle, raised in pasture-based systems. Ultrasound-based measurements of BFT and RFT (adjusted to 18 months of age) were collected in 11,750 animals, with 39,903 animals in the pedigree file. Additionally, 1,440 animals were genotyped using the GGP-indicus 35K SNP chip, containing 33,623 SNPs after the quality control. The single-step GWAS analyses were performed using the BLUPF90 family programs. Candidate genes were identified through the Ensembl database incorporated in the BioMart tool, while PANTHER and REVIGO were used to identify the key metabolic pathways and gene networks. A total of 18 genomic regions located on 10 different chromosomes and harbouring 23 candidate genes were identified for BFT. For RFT, 22 genomic regions were found on 14 chromosomes, with a total of 29 candidate genes identified. The results of the pathway analyses showed important genes for BFT, including TBL1XR1, AHCYL2, SLC4A7, AADAT, VPS53, IDH2 and ETS1, which are involved in lipid metabolism, synthesis of cellular amino acids, transport of solutes, transport between Golgi Complex membranes, cell differentiation and cellular development. The main genes identified for RFT were GSK3β, LRP1B, EXT1, GRB2, SORCS1 and SLMAP, which are involved in metabolic pathways such as glycogen synthesis, lipid transport and homeostasis, polysaccharide and carbohydrate metabolism. Polymorphisms located in these candidate genes can be incorporated in commercial genotyping platforms to improve the accuracy of imputation and genomic evaluations for carcass fatness. In addition to uncovering biological mechanisms associated with carcass quality, the key gene pathways identified can also be incorporated in biology-driven genomic prediction methods.

Integrative analysis of circRNAs, miRNAs, and mRNAs profiles to reveal ceRNAs networks in chicken intramuscular and abdominal adipogenesis

BACKGROUND

Tissue-specific fat deposition is regulated by a series of complex regulatory mechanisms. Reports indicate that epigenetic regulators, such as circular RNAs (circRNAs), are crucial in diseases progression, animal development, metabolism, and adipogenesis. In this study, to assess the functional roles of circRNAs in adipogenesis and tissue-specific fat deposition, we comprehensively analyzed the Ribo-Zero RNA-Seq and miRNAs data during chicken intramuscular and abdominal adipogenic differentiation.

RESULTS

circRNAs and miRNAs profiles during chicken adipogenic differentiation were found in adipocytes derived from various adipose tissues. It was also discovered that high levels of downregulated miRNAs potentially promote adipogenesis by activating their target genes which are associated with fatty acid metabolism and adipogenic differentiation. Through analysis of the correlation between the expression levels of circRNAs and adipogenic genes, as well as the dynamic expression patterns of circRNAs during adipogenic differentiation, several candidate circRNAs were identified. Moreover, competing endogenous RNA (ceRNAs) networks were constructed during chicken intramuscular and abdominal adipogenesis by combining miRNAs with mRNAs data. Several candidate circRNAs potentially influence adipogenesis by regulating miRNAs via PPAR and fatty acid metabolism-related pathways were identified, such as circLCLAT1, circFNDC3AL, circCLEC19A and circARMH1.

CONCLUSION

In conclusion, our findings reveal that circRNAs and the circRNA-miRNAs-mRNAs-ceRNAs network may play important roles in chicken adipocytes differentiation and tissue-specific fat deposition.

Use of gene expression profile to identify potentially relevant transcripts to myofibrillar fragmentation index trait

The myofibrillar fragmentation index (MFI) is an indicative trait for meat tenderness. Longissimus thoracis muscle samples from the 20 most extreme bulls (out of 80 bulls set) for MFI (high (n = 10) and low (n = 10) groups) trait were used to perform transcriptomic analysis, using RNA Sequencing (RNA-Seq). An average of 24.616 genes was expressed in the Nellore muscle transcriptome analysis. A total of 96 genes were differentially expressed (p value ≤ 0.001) between the two groups of divergent bulls for MFI. The HEBP2 and BDH1 genes were overexpressed in animals with high MFI. The MYBPH and MYL6, myosin encoders, were identified. The differentially expressed genes were related to increase mitochondria efficiency, especially in cells under oxidative stress conditions, and these also were related to zinc and calcium binding, membrane transport, and muscle constituent proteins, such as actin and myosin. Most of those genes were involved in metabolic pathways of oxidation-reduction, transport of lactate in the plasma membrane, and muscle contraction. This is the first study applying MFI phenotypes in transcriptomic studies to identify and understand differentially expressed genes for beef tenderness. These results suggest that differences detected in gene expression between high and low MFI animals are related to reactive mechanisms and structural components of oxidative fibers under the condition of cellular stress. Some genes may be selected as positional candidate genes to beef tenderness, MYL6, MYBPH, TRIM63, TRIM55, TRIOBP, and CHRNG genes. The use of MFI phenotypes could enhance results of meat tenderness studies.