Intramuscular Fat Deposition Research Articles

Investigation into Critical Gut Microbes Influencing Intramuscular Fat Deposition in Min Pigs

To determine the pivotal microorganisms affecting intramuscular fat (IMF) accumulation in Min pigs and to discern the extent of the influence exerted by various intestinal segments on IMF-related traits, we sequenced 16S rRNA from the contents of six intestinal segments from a high IMF group (Group H) and a low IMF group (Group L) of Min pigs weighing 90 ± 1 kg. We then compared their diversity and disparities in bacterial genera. Group H exhibited considerably higher α diversity in the jejunum and colon than Group L (p < 0.05). When 95% confidence levels were considered, the main β diversity components for the ileum, caecum, and colon within Groups H and L exhibited absolute segregation. Accordingly, 31 differentially abundant genera across Group H were pinpointed via LEfSe and the Wilcoxon test (p < 0.05) and subsequently scrutinised based on their distribution and abundance across distinct intestinal segments and their correlation with IMF phenotypes. The abundances of Terrisporobacter, Acetitomaculum, Bacteroides, Fibrobacter, Treponema, Akkermansia, Blautia, Clostridium sensu stricto 1, Turicibacter, Subdoligranulum, the [Eubacterium] siraeum group, and dgA 11 gut groups were positively correlated with IMF content (p < 0.05), whereas those of Bacillus, the Lachnospiraceae NK4A136 group, Streptococcus, Roseburia, Solobacterium, Veillonella, Lactobacillus, the Rikenellaceae RC9 gut group, Anaerovibrio, and the Lachnospiraceae AC2044 group were negatively associated with IMF content (p < 0.05). Employing PICRUSt2 for predicting intergenic metabolic pathways that differ among intestinal microbial communities revealed that within the 95% confidence interval the colonic microbiome was enriched with the most metabolic pathways, including those related to lipid metabolism. The diversity results, bacterial genus distributions, and metabolic pathway disparities revealed the colonic segment as an influential region for IMF deposition.

Transcriptome and targeted metabolome analysis of lipid profiles, nutrients compositions and volatile compounds in longissimus dorsi of different pig breeds.

Improving meat quality is important for commercial production and breeding. The molecular mechanism of intramuscular fat (IMF) deposition and meat characteristics remain further study. This study aimed to study the mechanism of IMF deposition and meat characteristics including redox potential, nutrients compositions and volatile compounds in longissimus dorsi (LD) by comparing with different pig breeds including Shanghai white (SW), Duroc x (Landrace Yorkshire) (DLY) and Laiwu (LW) pigs. Results showed that the contents of IMF, triglyceride (TG), total cholesterol (TC), and redox potential parameters were lower, while the content of MDA and activity of lactate dehydrogenase (LDH) were higher in LD of SW pigs compared with LW pigs (p<0.05). No differences were observed about these parameters between SW and DLY pigs. Also, the contents of medium-long chain fatty acids and γ-aminobutyric acid (GABA) were higher, while Asp was lower in LD of SW pigs compared with LW pigs (p<0.05). Volatile compounds results showed that 6 ketones, 4 alkenes, 11 alkanes, 2 aldehydes, 1 alcohol were increased and cholesterol was decreased in SW pigs compared with LW pigs. Transcriptome results showed that differential expressed genes involved in lipid synthesis, metabolism and transport in LD between SW and LW pigs, which were further verified by qPCR. Spearman correlation showed that HSL and Nedd4 were positively related to contents of TG and IMF, while negatively related to volatile compounds and fatty acids (p<0.05). Plin3 and Mgll were negatively related to contents of TG, IMF and cholesterol, while positively related to MDA, LDH, and volatile compounds (p<0.05). PPARA was negatively related to contents of TC and IMF, and activity of SOD, while positively related to volatile compounds (p<0.05). Our study provided new insights into potential mechanisms of IMF deposition, nutrients composition and volatile compounds of muscular tissues of different pig breeds.

Integrated analysis of muscle lncRNA and mRNA of Chinese indigenous breed Ningxiang pig in four developmental stages

Meat and its derivatives serve as crucial sources of protein, vitamins, minerals, and other essential nutrients for humans. Pork stands as China’s primary animal-derived food product consumed widely across diverse dietary structures; evaluating intramuscular fat content becomes pivotal in assessing its quality standards. Nonetheless, the intricate molecular mechanisms governing intramuscular fat deposition remain elusive. Our study utilized sequencing technology to scrutinize longitudinal development stages within Ningxiang pig’s longest dorsal muscles aiming to unravel these underlying mechanisms. In three distinct comparisons (30d vs. 90d, 90d vs. 150d and 150d vs. 210d) there were 578, 1,000 and 3,238 differentially expressed mRNA, along with 16, 158 and 85 lncRNAs were identified. STEM analysis unveiled six enriched model profiles for lncRNAs while seven such profiles emerged for mRNAs; notably, multiple shared model profiles existed between both RNA types. Enriched analysis highlighted numerous genes from mRNA profile8 and lncRNA profile7 significantly associated with pathways linked to fat deposition. Weight Gene Co-Expression Network Analysis (WGCNA) revealed that differential expression modules (DMEs) &amp;amp; differential expression lncRNAs primarily clustered within cyan, dark slate blue and pale turquoise modules. Furthermore, target genes PKD2 (MSTRG21592.MTRSG8859 and MTRSG18175), COL5A1 (MTRSG9969 and MTRSG180) and SOX13 (MTRSG21592 and MTRSG9088) as core components all intricately tied into processes related to fat deposition. This study lays the groundwork for deeper exploration into the molecular mechanisms underlying LDM fat deposition traits, and it also presents candidate genes for future molecular marker-assisted breeding.

Overexpression of ALDOC Promotes Porcine Intramuscular and Intermuscular Fat Deposition by Activating the AKT-mTORC1 Signaling Pathway.

Skeletal muscle fat accumulation, a common complication of obesity, has garnered increasing attention. For livestock animals, intramuscular fat content is a key determinant of meat quality and directly influences consumer preferences for different meat products. However, genes effectively regulating intramuscular and intermuscular fat (IIMF) deposition remain largely unexplored. To address this gap, we employed transcriptome sequencing of muscle from pigs with high and low IIMF contents, uncovering Aldolase C (ALDOC) as a novel key gene controlling IIMF. ALDOC overexpression significantly enhanced the IIMF content both in vivo and in vitro. Mechanistic investigations revealed that ALDOC activates the AKT-mTORC1 axis to promote lipid accumulation in myotubes and intramuscular adipocytes. Notably, the mTORC1 inhibitor rapamycin abrogated ALDOC's proadipogenic effect. Our findings establish ALDOC as a novel key gene regulating IIMF deposition and identify the ALDOC-AKT-mTORC1 signaling pathway as a promising therapeutic target for treating skeletal muscle fat infiltration and improving pork quality.

Integrating spatial transcriptomics and single-nucleus RNA-seq revealed the specific inhibitory effects of TGF-β on intramuscular fat deposition.

Intramuscular fat (IMF) is a complex adipose tissue within skeletal muscle, appearing specially tissue heterogeneous, and the factors influencing its formation remain unclear. In conditions such as diabetes, aging, and muscle wasting, IMF was deposited in abnormal locations in skeletal muscle, damaged the normal physiological functions of skeletal muscle. Here, we used Longissimus dorsi muscles from pigs with different IMF contents as samples and adopted a method combining spatial transcriptome (ST) and single-nucleus RNA-seq to identify the spatial heterogeneity of IMF. ST revealed that genes involved in TGF-β signaling pathways were specifically highly enriched in IMF. In lean pigs, IMF autocrine produces more TGF-β2, while in obese pigs, IMF received more endothelial-derived TGF-β1. In vitro experiments have proven that porcine endothelial cells in a simulated high-fat environment released more TGF-β1 than TGF-β2. Moreover, under obesity mice, the addition of TGF-β after muscle injury abolished IMF production and slowed muscle repair, whereas TGF-β inhibition accelerated muscle repair. Our findings demonstrate that the TGF-β pathway specifically regulates these processes, suggesting it as a potential therapeutic target for managing muscle atrophy in obese patients and enhancing muscle repair while reducing IMF deposition.

Integrative multiomics analysis identifies key genes regulating intramuscular fat deposition during development

Intramuscular fat (IMF) content is an important indicator of livestock and poultry meat quality. Enhancing IMF deposition can significantly improve meat quality. Focusing on the core process of IMF deposition, this study used the Jingxing Yellow (JXY) chickens as a model organism and employed multi-omics approaches, including RNA-sequencing (RNA-seq), Whole-genome bisulfite sequencing (WGBS), and metabolomics, to identify the key genes influencing IMF deposition in chickens during development. The results indicated that the contents of triglycerides (TG) and phospholipids (PLIP) exhibited an upward trend. The TG content did not differ significantly between day 1 (D1) and day 7 (D7), but increased significantly after 35 days (D35) of age. The WGBS results revealed that CpG methylation was the predominant methylation type in the breast muscle tissue of JXY chickens. Integrative analysis of RNA-seq and WGBS identified 50 genes, including PLA2G4F, PALMD, PLSCR5, ARHGEF26, LUM, DCN, TNRC6B, CACNA1C, ROBO1, and MBTPS2, whose methylation levels were significantly negatively correlated with their expression levels. In addition, the combined Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis of differentially-expressed metabolites (DEM) and differentially-expressed genes (DEG) converged on the glycerophospholipid metabolism pathway, which was significantly enriched in DEGs such as PLA2G4F, PLA2G15, LPIN1, MBOAT2, DGKH, AGPAT2, and CHKA, as well as DEM like glycerophosphocholine and phosphocholine. Notably, PLA2G4F was identified as a DEG by DNA methylation, suggesting that PLA2G4F could be a key candidate gene influencing IMF deposition during chicken development. These findings are expected to provide a solid theoretical foundation for improving meat quality through targeted genetic and epigenetic interventions.

Integrating lipidomics and metabolomics to reveal biomarkers of fat deposition in chicken meat

Local chicken breeds in China are highly regarded for their superior meat flavor. This study utilized lipidomics and non-targeted metabolomics to identify biomarkers influencing intramuscular fat (IMF) deposition in the breast muscle of 42- and 180-day-old Jingyuan chickens. Results revealed that IMF content was higher in the breast muscle of 180-day-old Jingyuan chickens compared to 42-day-old chickens (P < 0.01). We identified 248 differentially expressed lipids (DELs) and 1042 differentially expressed metabolites (DEMs). The breast muscle of 180-day-old chickens contained higher levels of TG, fatty acid (FA) and cholesteryl ester (CE), with C16:1 and C18:1 being particularly abundant. Integration of non-targeted metabolomic analyses emphasized glycerolipid metabolism and vitamin digestion and absorption as the main pathways distinguishing between 42- and 180-day-old chickens. Additionally, the differential metabolites LysoPS 18:1, LysoPC 20:3, LysoPC 18:2, LysoPI 20:3, and Pantothenic acid contributed to enhanced meat flavor in Jingyuan chickens.

Regulation of intramuscular fat deposition by intestinal microbes in pigs

Regulation of intramuscular fat deposition by intestinal microbes in pigs

MicroRNA Temporal-Specific Expression Profiles Reveal longissimus dorsi Muscle Development in Tianzhu White Yak.

As a class of regulatory factors, microRNAs (miRNAs) play an important role in regulating normal muscle development and fat deposition. Muscle and adipose tissues, as major components of the animal organism, are also economically important traits in livestock production. However, the effect of miRNA expression profiles on the development of muscle and adipose tissues in yak is currently unknown. In this study, we performed RNA sequencing (RNA-Seq) on Tianzhu white yak longissimus dorsi muscle tissue obtained from calves (6 months of age, M6, n = 6) and young (30 months of age, M30, n = 6) and adult yak (54 months of age, M54, n = 6) to identify which miRNAs are differentially expressed and to investigate their temporal expression profiles, establishing a regulatory network of miRNAs associated with the development of muscle and adipose. The results showed that 1191 miRNAs and 22061 mRNAs were screened across the three stages, of which the numbers of differentially expressed miRNAs (DE miRNAs) and differentially expressed mRNAs (DE mRNAs) were 225 and 450, respectively. The expression levels of the nine DE miRNAs were confirmed using a reverse transcription quantitative PCR (RT-qPCR) assay, and the trend of the assay results was generally consistent with the trend of the transcriptome profiles. Based on the expression trend, DE miRNAs were categorized into eight different expression patterns. Regarding the expression of DE miRNAs in sub-trends Profile 1 and Profile 2 (p < 0.05), the gene expression patterns were upregulated (87 DE miRNAs). Gene ontology (GO) and Kyoto Encyclopedia of Genes Genomes (KEGG) analyses showed that the identified DE miRNAs and DE mRNAs were enriched in pathway entries associated with muscle and intramuscular fat (IMF) growth and development. On this basis, we constructed a DE miRNA-mRNA interaction network. We found that some DE mRNAs of interest overlapped with miRNA target genes, such as ACSL3, FOXO3, FBXO30, FGFBP4, TSKU, MYH10 (muscle development), ACOX1, FADS2, EIF4E2, SCD1, EL0VL5, and ACACB (intramuscular fat deposition). These results provide a valuable resource for further studies on the molecular mechanisms of muscle tissue development in yak and also lay a foundation for investigating the interactions between genes and miRNAs.

Body Composition, Sarcopenia, and Serum Myokines in Acromegaly: A Narrative Review.

Patients with active acromegaly have a higher percentage of lean body mass, a lower percentage of fat body mass, and an increase in their extracellular water compartment compared to healthy individuals. However, muscle function appears to be compromised in patients with acromegaly, with some experiencing worsened physical performance and sarcopenia. Myokine alterations, insulin resistance, dysregulation of protein metabolism, muscle oxidative stress, neuromuscular junction impairment, and increased ectopic intramuscular fat deposits may play roles in muscle dysfunction in patients with acromegaly.

MiR-196a Promotes Lipid Deposition in Goat Intramuscular Preadipocytes by Targeting MAP3K1 and Activating PI3K-Akt Pathway.

Meat quality in goats is partly determined by the intramuscular fat (IMF) content, which is associated with the proliferation and differentiation of intramuscular preadipocytes. Emerging studies have suggested that miRNA plays a crucial role in adipocyte proliferation and differentiation. In our recent study, we observed the expression variations in miR-196a in the longissimus dorsi muscle of Jianzhou goats at different ages. However, the specific function and underlying mechanism of miR-196a in IMF deposition are still unclear. This study demonstrated that miR-196a significantly enhanced adipogenesis and apoptosis and reduced the proliferation of preadipocytes. Subsequently, RNA-seq was employed to determine genes regulated by miR-196a, and 677 differentially expressed genes were detected after miR-196a overexpression. The PI3K-Akt pathway was identified as activated in miR-196a regulating intramuscular adipogenesis via Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis and further verified via Western blot and rescue assays. Lastly, using RT-qPCR, Western blot, dual-luciferase, and rescue assays, we found that miR-196a promoted adipogenesis and suppressed the proliferation of intramuscular preadipocytes by the downregulation of MAP3K1. In summary, these results suggest that miR-196a regulates IMF deposition by targeting MAP3K1 and activating the PI3K-Akt pathway and provide a theoretical foundation for improving goat meat quality through molecular breeding.

Exploration of Genes Related to Intramuscular Fat Deposition in Xinjiang Brown Cattle.

The aim of this study was to investigate the differentially expressed genes associated with intramuscular fat deposition in the longissimus dorsi muscle of Xinjiang Brown Bulls. The longissimus dorsi muscles of 10 Xinjiang Brown Bulls were selected under the same feeding conditions. The intramuscular fat content of muscle samples was determined by the Soxhlet extraction method, for which 5 samples with high intramuscular fat content (HIMF group) and 5 samples with low intramuscular fat content (LIMF group) were selected. It was found that the intramuscular fat content of the HIMF group was 46.054% higher than that of the LIMF group. Muscle samples produced by paraffin sectioning were selected for morphological observation. It was found that the fat richness of the HIMF group was better than that of the LIMF group. Transcriptome sequencing technology was used to analyze the gene expression differences of longissimus dorsi muscle. Through in-depth analysis of the longissimus dorsi muscle by transcriptome sequencing technology, we screened a total of 165 differentially expressed genes. The results of Gene Ontology (GO) enrichment analysis showed that the differentially expressed genes in the two groups were mainly clustered in biological pathways related to carbohydrate metabolic processes, redox processes and oxidoreductase activities. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis showed that the differentially expressed genes were significantly clustered in 15 metabolic pathways, which mainly covered fatty acid metabolism (related to lipid metabolism and glucose metabolism), the pentose phosphate pathway, the Peroxisome Proliferator-Activated Receptor (PPAR) signaling pathway and other important metabolic processes. The three genes that were predominantly enriched in the glycolipid metabolic pathway by analysis were SCD5, CPT1C and FBP2, all of which directly or indirectly affect intramuscular fat deposition. In summary, the present study investigated the differences in gene expression between high and low intramuscular fat content in the longissimus dorsi muscle of Xinjiang Brown Bulls by transcriptome sequencing technology and revealed the related signaling pathways. Therefore, we hypothesized that SCD5, CPT1C and FBP2 were the key genes responsible for the significant differences in intramuscular fat content of the longissimus dorsi muscles in a population of Xinjiang Brown Bulls. We expect that these findings will provide fundamental support for subsequent studies exploring key genes affecting fat deposition characteristics in Xinjiang Brown Bulls.

Combined Multi-Omics Analysis Reveals the Potential Role of ACADS in Yak Intramuscular Fat Deposition.

The Yak (Bos grunniens) is a special breed of livestock predominantly distributed in the Qinghai-Tibet Plateau of China. Intramuscular fat (IMF) content in beef cattle is a vital indicator of meat quality. In this study, RNA-Seq and Protein-Seq were respectively employed to sequence the transcriptome and proteome of the longissimus dorsi (LD) tissue from 4-year-old yaks with significant differences in IMF content under the same fattening conditions. Five overlapping genes (MYL3, ACADS, L2HGDH, IGFN1, and ENSBGRG00000000-926) were screened using combined analysis. Functional verification tests demonstrated that the key gene ACADS inhibited yak intramuscular preadipocyte (YIMA) differentiation and proliferation, promoted mitochondrial biogenesis gene expression, and increased the mitochondrial membrane potential (MMP). Furthermore, co-transfection experiments further demonstrated that interfering with ACADS reversed the effect of PPARα agonists in promoting lipid differentiation. In conclusion, ACADS potentially inhibits lipid deposition in YIAMs by regulating the PPARα signalling pathway. These findings offer insights into the molecular mechanisms underlying yak meat quality.

Dynamic distribution of gut microbiota-metabolites during post-weaning longissimus dorsi muscle development in Ningxiang pigs.

Ningxiang pigs (NXPs) have a strong ability to deposit fat and intramuscular fat (IMF). However, microbiota-metabolite development and the role in IMF deposition have been rarely reported. Here, we compared the gut microbiota and metabolite profiles and IMF content at 30, 70, 150, 200, and 250 days of age of NXPs. The results revealed that the IMF content in NXPs increased significantly (P < 0.05) as the pigs' age extended. Additionally, the C14:0 content in the longissimus dorsi muscle at 30 and 70 days of age was significantly lower (P < 0.05) than that at 150 and 200 days of age. The Shannon index and ACE index showed a pattern of initially increasing and then decreasing. LEfSe analysis revealed that 41 differential bacteria at the genus level were specific to different growth stages, indicating the dominant bacteria's dynamic changes in the NXPs during different stages of age. Furthermore, we found that there were significant differences in cecal metabolism, the classification of differential metabolites revealed that 15.61% of compounds were fatty acyls, 13.98% were prenol lipids, and 10.57% were steroids and steroid derivatives. Next, the network analysis showed that Lachnospiraceae-XPB1014-group was positively related to 4-2-Aminophenyl-2-4-dioxobutanoic-acid, (Z)-3-Octene, 5-Methyl-furaldehyde, Propyl-2-4-decadienoate, which were also positively correlated with the IMF content. Our findings illustrated the dynamic distribution of cecal microbiota and metabolite composition at different growth stages in NXPs and their correlation with IMF deposition. These results provide a valuable insight into optimizing meat quality and overall health in post-weaning NXPs, providing a foundation for enhancement in pork product.IMPORTANCEUnderstanding the dynamic interplay between gut microbiota, metabolites, and intramuscular fat (IMF) deposition in pigs at various growth stages holds significant importance for the pork industry. This research sheds light on how the composition of gut microbiota and metabolites changes throughout the developmental stages of pigs, impacting IMF content in meat. By identifying specific bacterial genera and metabolites associated with IMF deposition, this study offers valuable insights for optimizing meat quality and health in post-weaning pigs. Such knowledge could lead to targeted interventions or management strategies aimed at enhancing pork product quality and overall profitability for producers. Ultimately, this research contributes to advancing our understanding of the complex relationship between gut microbiota, metabolites, and meat quality, offering practical implications for the swine industry.

Dynamic alternations of three-dimensional chromatin architecture contribute to phenotypic characteristics of breast muscle in chicken

Breast muscle growth rate and intramuscular fat (IMF) content show apparent differences between fast-growing broilers and slow-growing indigenous chickens. However, the underlying genetic basis of these phenotypic characteristics remains elusive. In this study, we investigate the dynamic alterations of three-dimensional genome architecture and chromatin accessibility in breast muscle across four key developmental stages from embryo to starter chick in Arbor Acres (AA) broilers and Yufen (YF) indigenous chickens. The limited breed-specifically up-regulated genes (Bup-DEGs) are embedded in breed-specific A compartment, while a majority of the Bup-DEGs involving myogenesis and adipogenesis are regulated by the breed-specific TAD reprogramming. Chromatin loops allow distal accessible regions to interact with myogenic genes, and those loops share an extremely low similarity between chicken with different growth rate. Moreover, AA-specific loop interactions promote the expression of 40 Bup-DEGs, such as IGF1, which contributes to myofiber hypertrophy. YF-specific loop interactions or distal accessible regions lead to increased expression of 5 Bup-DEGs, including PIGO, PEMT, DHCR7, TMEM38B, and DHDH, which contribute to IMF deposition. These results help elucidate the regulation of breast muscle growth and IMF deposition in chickens.

Meat quality of Santa Inês sheep fed forage palm (Opuntia ficus-indica, Mill) and water restriction

The aim of this study was to evaluate the physicochemical composition, fatty acids, and sensory properties of meat from Santa Inês sheep fed forage palm in the diet and with water restriction. They used 42 non-castrated male Santa Inês lambs, with about 180 days of age and an average weight of 21.6 ± 2.2 kg, distributed in a completely randomized design with seven treatments and six repetitions, and the data were submitted to regression analysis, factorial (level × water), and contrast between the control treatment and others. The treatments consisted of the inclusion of spineless cactus (0, 30, 50, and 70%). In treatments containing cactus pear (36 animals), half of the animals were placed under voluntary water consumption restriction. According to the physicochemical characteristics analyzed, lipids suffered an increasing linear effect (p&lt;0.05) as they included spineless cactus in the diet of sheep. The control diet had the lowest percentage of lipids (2.44%). The inclusion of 50% cactus pear promoted a higher content of lipids (3.41), and restricting water intake resulted in higher lipid content (3.09). The inclusion of cactus pear and water restriction did not affect the profile of fatty acids in meat. In the studied sensory attributes (hardness, juiciness, flavor, color, aroma, and overall acceptability), only meat color suffered an increasing linear effect (p &lt; 0.05). With the inclusion of spineless cactus in the diet, the meat from the lambs received good grades from the panelists, showing good acceptability. This demonstrates that the cactus pear provides sufficient water and nutrients for animals, resulting in the deposition of intramuscular fat, thus becoming a good-quality meat.

GSK3 regulation Wnt/β-catenin signaling affects adipogenesis in bovine skeletal muscle fibro/adipogenic progenitors

Clarifying the cellular origin and regulatory mechanisms of intramuscular fat (IMF) deposition is crucial for improving beef quality. Here, we used single-nucleus RNA sequencing to analyze the structure and heterogeneity of skeletal muscle cell populations in different developmental stages of Yanbian cattle and identified eight cell types in two developmental stages of calves and adults. Among them, fibro/adipogenic progenitors (FAPs) expressing CD29 (ITGA7)pos and CD56 (NCAM1)neg surface markers were committed to IMF deposition in beef cattle and expressed major Wnt ligands and receptors. LY2090314/XAV-939 was used to activate/inhibit Wnt/β-catenin signal. The results showed that the blockade of Glycogen Synthase Kinase 3 (GSK3) by LY2090314 promoted the stabilization of β-catenin and reduced the expression of genes related adipogenic differentiation (e.g., PPARγ and C/EBPα) in bovine FAPs, confirming the anti-adipogenic effect of GSK3. XAV-939 inhibition of the Wnt/β-catenin pathway promoted the lipid accumulation capacity of FAPs. Furthermore, we found that blocking GSK3 enhanced the paracrine effects of FAPs-MuSCs and increased myotube formation in muscle satellite cells (MuSCs). Overall, our results outline a single-cell atlas of skeletal muscle development in Yanbian cattle, revealed the role of Wnt/GSK3/β-catenin signaling in FAPs adipogenesis, and provide a theoretical basis for further regulation of bovine IMF deposition.

Transcriptome analysis reveals the effects of Schizochytrium sp. on the meat quality attributes of Tan lambs

Schizochytrium sp., a feed additive, positively affects the quality of animal meat. In this study, the molecular mechanisms through which dietary Schizochytrium sp. affects the meat quality characteristics of Tan lambs were investigated using transcriptomic techniques. The findings demonstrate that the lambs supplemented with Schizochytrium sp. had a larger loin eye area and a higher average daily gain and intramuscular fat content (P < 0.05). They also had lower drip loss (at 24 and 48 h) and shear force (P < 0.05). Further, 745 genes were differentially expressed between lambs supplemented with Schizochytrium and the control group. Moreover, KEGG pathway analysis showed that the ECM-receptor interaction pathway, which is related to muscle generation and intramuscular fat deposition, was significantly enriched in the lambs administered a diet containing Schizochytrium sp. Herein, we identified some pivotal genes linked to muscular system development and lipid metabolism. Thus, using Schizochytrium sp. may boost the meat quality of Tan lambs by modifying the expression of genes related to hub pathways. The results supply a new basis to determine the molecular mechanisms through which Schizochytrium sp. supplementation regulates the meat quality characteristics of sheep.

Single-nucleus RNA sequencing and lipidomics reveal characteristics of transcriptional and lipid composition in porcine longissimus dorsi muscle

BackgroundGlobal per capita meat consumption continues to rise, especially pork. Meat quality is influenced by the content of intramuscular fat (IMF) as a key factor. The longissimus dorsi muscle of Dahe pigs (DHM, IMF: 7.98% ± 1.96%) and Dahe black pigs (DHBM, IMF: 3.30% ± 0.64%) was studied to explore cellular heterogeneity and differentially expressed genes (DEGs) associated with IMF deposition using single-nucleus RNA sequencing (snRNA-seq). The lipid composition was then analyzed using non-targeted lipidomics.ResultsA total of seven cell subpopulations were identified, including myocytes, fibroblast/fibro/adipogenic progenitors (FAPs), satellite cells, endothelial cells, macrophages, pericytes, and adipocytes. Among them, FAPs and adipocytes were more focused because they could be associated with lipid deposition. 1623 DEGs in the FAPs subpopulation of DHBM were up-regulated compared with DHM, while 1535 were down-regulated. These DEGs enriched in the glycolysis/gluconeogenesis pathway. 109 DEGs were up-regulated and 806 were down-regulated in the adipocyte subpopulation of DHBM compared with DHM, which were mainly enriched in the PPAR signaling pathway and fatty acid (FA) biosynthesis. The expression level of PPARG, ABP4, LEP, and ACSL1 genes in DHM was higher than that in DHBM. Lipidomics reveals porcine lipid composition characteristics of muscle tissue. A total of 41 lipid classes and 2699 lipid species were identified in DHM and DHBM groups. The top ten relative peak areas of lipid classes in DHM and DHBM were triglyceride (TG), phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylserine (PS), diglyceride (DG), cardiolipin (CL), ceramides (Cer), Simple Glc series (Hex1Cer), sphingomyelin (phSM), and phosphatidylinositol (PI). The relative peak areas of 35 lipid species in DHM were lower than DHBM, and 28 lipid species that were higher. There was a significant increase in the TG fatty acyl chains C6:0, C17:0, and C11:4, and a significant decrease in C16:0, C18:1, C18:2, and C22:4 in DHBM (p < 0.05).ConclusionsC16:0 FA may downregulate the expression level of PPARG gene, which leads to the downregulation of fat metabolism-related genes such as ACSL, PLIN2, and FABP4 in DHBM compared with DHM. This may be the reason that the lipid deposition ability of Dahe pigs is stronger than that of Dahe black pigs, which need further investigation.

Temporal Transcriptome Dynamics of Longissimus dorsi Reveals the Mechanism of the Differences in Muscle Development and IMF Deposition between Fuqing Goats and Nubian Goats.

In this study, we measured the growth performance and intramuscular fat (IMF) content of the Longissimus dorsi (LD) of Fuqing goats (FQs) and Nubian goats (NBYs), which exhibit extreme phenotypic differences in terms of their production and meat quality traits. RNA-Seq analysis was performed, and transcriptome data were obtained from the LD tissue of 3-month fetuses (E3), 0-month lambs (0M), 3-month lambs (3M), and 12-month lambs (12M) to reveal the differences in the molecular mechanisms regulating the muscle development and IMF deposition between FQs and NBYs. The results showed that a higher body weight and average daily gain were observed in the NBYs at three developmental stages after birth, whereas a higher IMF content was registered in the FQs at 12M. Additionally, transcriptome profiles during the embryonic period and after birth were completely different for both FQs and NBYs. Moreover, DEGs (KIF23, CCDC69, CCNA2, MKI67, KIF11, RACGAP1, NUSAP1, SKP2, ZBTB18, NES, LOC102180034, CAPN6, TUBA1A, LOC102178700, and PEG10) significantly enriched in the cell cycle (ko04110) at E3 (FQs vs. NBYs), and DEGs (MRPS7, RPS8, RPL6, RPL4, RPS11, RPS10, RPL5, RPS6, RPL8, RPS13, RPS24, RPS15, RPL23) significantly enriched in ribosomes (ko03010) at 0M (FQs vs. NBYs) related to myogenic differentiation and fusion were identified. Meanwhile, the differences in glucose and lipid metabolism began at the E3 timepoint and continued to strengthen as growth proceeded in FQs vs. NBYs. DEGs (CD36, ADIROQR2, ACACA, ACACB, CPT1A, IGF1R, IRS2, LDH-A, PKM, HK2, PFKP, PCK1, GPI, FASN, FADS1, ELOVL6, HADHB, ACOK1, ACAA2, and ACSL4) at 3M (FQs vs. NBYs) and 12M (FQs vs. NBYs) significantly enriched in the AMPK signaling pathway (ko04152), insulin resistance (ko04931), the insulin signaling pathway (ko04910), fatty acid metabolism (ko01212), and glycolysis/gluconeogenesis (ko00010) related to IMF deposition were identified. Further, the results from this study provide the basis for future studies on the mechanisms regulating muscle development and IMF deposition in different breeds of goats, and the candidate genes identified could be used in the selection process.