Fat depot-specific effects of body fat distribution and adipocyte size on intramuscular fat accumulation in Wagyu cattle

Identification and Co-expression Analysis of Differentially Expressed LncRNAs and mRNAs Regulate Intramuscular Fat Deposition in Yaks at Two Developmental Stages

Intramuscular fat (IMF) content is a key indicator of yak meat quality. This study aimed to identify lncRNAs that regulate IMF deposition in yaks. Three male calf yaks (3 months) and three male adult yaks (3 years) were used in the current study. After slaughter, the tissue morphology of the longissimus dorsi (LD) muscle was assessed using a cry-sectioning technique and differentially expressed lncRNAs and mRNAs (DELs and DEMs) were identified using RNA-Seq technology. The diameter and volume of fat droplets were significantly larger and bigger, respectively, in adults than in calves (P < 0.001). A total of 37,790 genes and 16,400 lncRNAs that regulate fat deposition were identified. Among them, 2327 mRNAs and 474 lncRNAs were differentially expressed between calves and adult yaks. DEGs stearoyl-CoA desaturase (SCD), fatty acid synthase (FASN), fatty acid binding protein 4 (FABP4) and fibronectin 1 (FN1) and DELs MSTRG.15795.4 and MSTRG.35028.6 were screened. The enrichment and pathway analysis regulated by the DMEs and DELs were predicted. We found significantly enriched biological processes and pathways involved in fat deposition, including the biosynthesis of unsaturated fatty acids, fatty acid biosynthesis, fatty acid elongation, and the mTOR signaling pathway. Co-expression network of the DELs and related genes, including MSTRG.10268.1-placenta associated 8 (PLAC8), MSTRG.16223.1-galectin 3 (LGALS3), MSTRG.34732.1-glycerol-3-phosphate acyltransferase, mitochondrial (GPAM), MSTRG.11907.11-fibroblast growth factor 1 (FGF1), MSTRG.34342.1-lipase A, lysosomal acid type (LIPA), and MSTRG.1667.2-integrin subunit beta 2 (ITGB2) was constructed. RT-qPCR verified the sequence results. The molecular regulatory mechanisms of lncRNAs on intramuscular fat deposition in yak were further explored.

Fundus camera-based precision monitoring of blood vitamin A level for Wagyu cattle using deep learning

In the wagyu industry worldwide, high-quality marbling beef is produced by promoting intramuscular fat deposition during cattle fattening stage through dietary vitamin A control. Thus, however, cattle become susceptible to either vitamin A deficiency or excess state, not only influencing cattle performance and beef quality, but also causing health problems. Researchers have been exploring eye photography monitoring methods for cattle blood vitamin A levels based on the relation between vitamin A and retina colour changes. But previous endeavours cannot realise real-time monitoring and their prediction accuracy still need improvement in a practical sense. This study developed a handheld camera system capable of capturing cattle fundus images and predicting vitamin A levels in real time using deep learning. 4000 fundus images from 50 Japanese Black cattle were used to train and test the prediction algorithms, and the model achieved an average 87%, 83%, and 80% accuracy for three levels of vitamin A deficiency classification (particularly 87% for severe level), demonstrating the effectiveness of camera system in vitamin A deficiency prediction, especially for screening and early warning. More importantly, a new method was exemplified to utilise visualisation heatmap for colour-related DNNs tasks, and it was found that chromatic features extracted from LRP heatmap highlighted-ROI could account for 70% accuracy for the prediction of vitamin A deficiency. This system can assist farmers in blood vitamin A level monitoring and related disease prevention, contributing to precision livestock management and animal well-being in wagyu industry.

Diversity in Cell Morphology, Composition, and Function among Adipose Depots in River Buffaloes

Fat deposition is a significant economic trait in livestock animals. Adipose tissues (ATs) developed in subcutaneous and visceral depots are considered waste whereas those within muscle are highly valued. In river buffaloes, lipogenesis is highly active in subcutaneous (especially in the sternum subcutaneous) and visceral depots but not in muscle tissue. Revealing the features and functions of ATs in different depots is significant for the regulation of their development. Here, we characterize the cell size, composition, and function of six AT depots in river buffaloes. Our data support that the subcutaneous AT depots have a larger cell size than visceral AT depots, and the subcutaneous AT depots, especially the sternum subcutaneous AT, are mainly associated with the extracellular matrix whereas the visceral AT depots are mainly associated with immunity. We found that sternum subcutaneous AT is significantly different from ATs in other depots, due to the high unsaturated fatty acid content and the significant association with metabolic protection. The perirenal AT is more active in FA oxidation for energy supply. In addition, the expression of HOX paralogs supports the variable origins of ATs in different depots, indicating that the development of ATs in different depots is mediated by their progenitor cells. The present study enhances our understanding of the cellular and molecular features, metabolism, and origin of AT depots in buffaloes, which is significant for the regulation of fat deposition and provides new insights into the features of AT depots in multiple discrete locations.

GLUT4 translocation and dispersal operate in multiple cell types and are negatively correlated with cell size in adipocytes

The regulated translocation of the glucose transporter, GLUT4, to the surface of adipocytes and muscle is a key action of insulin. This is underpinned by the delivery and fusion of GLUT4-containing vesicles with the plasma membrane. Recent studies have revealed that a further action of insulin is to mediate the dispersal of GLUT4 molecules away from the site of GLUT4 vesicle fusion with the plasma membrane. Although shown in adipocytes, whether insulin-stimulated dispersal occurs in other cells and/or is exhibited by other proteins remains a matter of debate. Here we show that insulin stimulates GLUT4 dispersal in the plasma membrane of adipocytes, induced pluripotent stem cell-derived cardiomyocytes and HeLa cells, suggesting that this phenomenon is specific to GLUT4 expressed in all cell types. By contrast, insulin-stimulated dispersal of TfR was not observed in HeLa cells, suggesting that the mechanism may be unique to GLUT4. Consistent with dispersal being an important physiological mechanism, we observed that insulin-stimulated GLUT4 dispersal is reduced under conditions of insulin resistance. Adipocytes of different sizes have been shown to exhibit distinct metabolic properties: larger adipocytes exhibit reduced insulin-stimulated glucose transport compared to smaller cells. Here we show that both GLUT4 delivery to the plasma membrane and GLUT4 dispersal are reduced in larger adipocytes, supporting the hypothesis that larger adipocytes are refractory to insulin challenge compared to their smaller counterparts, even within a supposedly homogeneous population of cells.

The study of "muscle eye" in bulls of Ukrainian black-spotted dairy-meat breed as a factor in improving the properties of meat products

The impact of age, live weight, and growth rate of the bulls of Ukrainian breeds on the area of “muscle eye” (cross-section of m. longissimus dorsi when the carcass is divided into front and rear between the 12th and 13th ribs) was studied. The correlation between the size of the “muscle eye” and the carcass's characteristics and the meat's qualitative indicators was also determined. The research was conducted on the bulls of Ukrainian black-and-white dairy (UBWDB) and Ukrainian meat (UMB) breeds. Living animals “muscle eye” area was determined with the ultrasonic analyser Emperor 860, after slaughter. It was found that UMB bulls have the area of “muscle eye” twice as big as their UBWDB peers. The “muscle eye” area increases when growing the cattle to 400 – 450 kg. In the future, it will be practically independent of the age and weight of the animals and remains stable. An increase in the average daily gains within the breed leads to an increase in the “muscle eye” area. The area of “muscle eye” has a weak negative connection (r = -0.193) with meat tenderness and dry matter content (r = -0.345) and a positive one with slaughter weight (r = 0.614) and slaughter yield (r = 0.653). Of the three parameters (length, depth, and area) of “muscle eye”, the greatest impact on the technological properties of meat has depth. Its increase has a negative connection with meat tenderness (r = -0.810) and moisture (r = -0.474), but it has a positive impact on the moisture retention capacity (r = 0.338) and weight of weighed portion after heat treatment. The obtained results can be used to clarify the optimal growing parameters of the bulls of Ukrainian black-and-white dairy and meat breeds for meat and determine the optimal age and live weight of the cattle slaughter.

Genome-Wide Expression Profiling and Networking Reveals an Imperative Role of IMF-Associated Novel CircRNAs as ceRNA in Pigs

Intramuscular fat (IMF) deposition is a biological process that has a strong impact on the nutritional and sensorial properties of meat, with relevant consequences on human health. Pork loins determine the effects of marbling on the sensory attributes and meat quality properties, which differ among various pig breeds. This study explores the crosstalk of non-coding RNAs with mRNAs and analyzes the potential pathogenic role of IMF-associated competing endogenous RNA (ceRNA) in IMF tissues, which offer a framework for the functional validation of key/potential genes. A high-throughput whole-genome transcriptome analysis of IMF tissues from longissimus dorsi muscles of Large White (D_JN) and Laiwu (L_JN) pigs resulted in the identification of 283 differentially expressed circRNAs (DECs), including two key circRNAs (circRNA-23437, circRNA-08840) with potential binding sites for multiple miRNAs regulating the whole network. The potential ceRNA mechanism identified the DEC target miRNAs-mRNAs involved in lipid metabolism, fat deposition, meat quality, and metabolic syndrome via the circRNA-miRNA-mRNA network, concluding that ssc-mir-370 is the most important target miRNA shared by both key circRNAs. TGM2, SLC5A6, ECI1, FASN, PER1, SLC25A34, SOD1, and COL5A3 were identified as hub genes through an intensive protein-protein interaction (PPI) network analysis of target genes acquired from the ceRNA regulatory network. Functional enrichments, pathway examinations, and qRT-PCR analyses infer their implications in fat/cholesterol metabolism, insulin secretion, and fatty acid biosynthesis. Here, circRNAs and miRNA sequencing accompanied by computational techniques were performed to analyze their expressions in IMF tissues from the longissimus dorsi muscles of two pig breeds. Their target gene evolutionary trajectories, expression profiling, functional enrichments, subcellular localizations, and structural advances with high-throughput protein modeling, following genomic organizations, will provide new insights into the underlying molecular mechanisms of adipocyte differentiation and IMF deposition and a much-needed qualitative framework for future research to improve meat quality and its role as a biomarker to treat lipid metabolic syndromes.

Weighted Gene Co-expression Network Analysis Revealed That CircMARK3 Is a Potential CircRNA Affects Fat Deposition in Buffalo

Background

Buffalo meat is increasingly widely accepted for consumption as it shares several quality attributes with cattle meat (beef). Hence, there is a huge opportunity for growth in the buffalo meat industry. However, buffalo meat has relatively low intramuscular fat (IMF) content, affecting its flavor, tenderness and juiciness. As there is a dearth of information on factors that control fat deposition, this study was undertaken to provide new candidate factor associated with buffalo fat deposition. Circular RNA (circRNA) is a novel class of non-coding RNA with a closed-loop structure, and play an important role in fat deposition.

Methods

In this study, weighted gene co-expression network analysis (WGCNA) was used to construct a circRNA co-expression network and revealed a candidate circRNA that may affect the IMF deposition of buffalo as determined by RT-qPCR, semiquantitative PCR and gain-of-function experiments.

Results

Herein, WGCNA determined that one module (turquoise module) is significantly associated with the growth and development stages of buffalo. Further analysis revealed a total of 191 overlapping circRNAs among differentially expressed (DE) circRNAs and the co-expression module. A candidate circRNA was found, 21:6969877|69753491 (circRNA_ID), with a reported involvement in lipid metabolism. This circRNA is stably expressed and originates from the MARK3 gene, hence the name circMARK3. circMARK3 is highly expressed in adipose tissue and mature adipocytes and is located in the cytoplasm. Gain-of-function experiments demonstrated that circMARK3 promoted adipogenic differentiation of buffalo adipocytes and 3T3-L1 cells by up-regulating the expression levels of adipogenic marker genes PPARG, C/EBPα and FABP4.

Conclusion

These results indicate that circMARK3 is a potential factor that promotes fat deposition by regulating adipocyte differentiation and adipogenesis in buffalo.

Manifestation of living and post-slaughter traits of productivity in inbred and outbred bull calves of Ukrainian meat cattle breed

Selection in meat cattle herds requires caution due to the manifestation of inbred depression in traits that affect the economics of this livestock industry. This paper analyses the productivity of inbred and outbred bull calves of the Ukrainian meat cattle breed and justifies methods of pair selection in purebred herds with natural pairing. In bull calves, the growth of animals and traits of their meat productivity after slaughter were considered. Inbreeding was determined based on their pedigree. Inbred animals tended to have a growth rate of 10.2% from birth to 8 months of age. Afterwards, their average daily gain in live weight decreases sharply compared to outbred peers, who grow faster over a more extended period. From 8 to 18 months of age, it is probably (p >0.95) higher by 27.3% compared to inbred animals. Inbred bull calves have higher variability (Cv,%) in average daily gains. This indicates different adaptations to the environment during the suckling period and after weaning. Outbred animals tend to gain 2.3% of body weight at 12 months, 4.7 at 15 months, and 10.3% at 18 months. Its variability with age decreases by 7.4 points in inbred bull calves and 0.4 points in outbred ones, from 8 to 18 months. The inbred animals spent 29.5% more feed per kg of gain (p >0.95) than the outbred ones. Inbred bull calves vs outbred ones at 15 and 18 months of age tend to improve the expression of meat forms by 1.3 and 2.7%. They are relatively shorter and have a more rounded barrel. As a result, they have a shorter period of rapid growth. With the small size of the Ukrainian meat cattle population, one of the most important problems is reducing genetic variation in beef productivity traits and manifesting inbred depression in them. In purebred commercial herds, the mating of close animals should be avoided. To do this, an "order" for bulls should be made, and pairs should be selected without using inbreeding at different grades. Thus, outbred bull calves will reach live weight more quickly, spending less feed per growth unit, and have better basic slaughter traits.

The yield of adipose tissue and by-products in the course of the slaughter of inbred and outbred bulls of the Ukrainian beef breed

The research focuses on analysing and generalising the distribution of internal adipose tissue and organs that are not part of the carcasses of inbred and outbred bulls of the Ukrainian beef breed. Animal stock inbreeding was determined based on five breeding records according to Wright’s method modified by Kyslovskyi. Two experimental groups of 5 bulls were formed. The average inbreeding coefficient for inbred bulls was 3.43%. Animals were bred up to 18 months of age. Following slaughter, the mass and the yield of the head, liver, lungs, heart, kidneys, and brain were determined, and 4 types of fat were separated and weighed: perirenal, from the stomach, intestines, and pericardial. Inbred animals are more prone to the accretion of internal adipose tissue. Inbred bulls have 1.8 points more of it. Fat is more intensely accumulated around inbred bulls' multichambered stomachs and kidneys. Intensive fat accumulation was observed around the hearts and intestines of outbred bulls. Adipose tissue around the heart and intestines is more variable in inbred and outbred animals – from the forestomach and kidneys. The weight of inbred bulls’ liver is less by 22.4%, kidneys – by 62.5%, heart – by 11.1%, and head – by 23.8% compared to outbred ones. The weight of their lungs is more by 10.5%. At the same time, inbred bulls tend to have brain weight gain of 12.5% and testicles – by 8.3%. Thus, inbreeding application in Ukrainian beef breeds with a small population size affects the growth of internal organs and the intensity of accumulation and distribution of interior fat. Due to more intensive accumulation of internal adipose tissue, inbred bulls have increased expenditure of forage energy for its formation. They are characterized by an increased yield of low-value raw fat, making them less efficient than outbred bulls for beef production.     

Weighted Gene Co-Expression Network Analysis Identifies Key Modules and Central Genes Associated With Bovine Subcutaneous Adipose Tissue

Background

Fat deposition is an important economic trait in livestock and poultry production. However, the relationship between various genes and signal pathways of fat deposition is still unclear to a large extent. The purpose of this study is to analyze the potential molecular targets and related molecular pathways in bovine subcutaneous adipose tissue.

Results

We downloaded the GSE116775 microarray dataset from Gene Expression Omnibus (GEO). The weighted gene co-expression network (WGCNA) was used to analyze the gene expression profile, and the key gene modules with the highest correlation with subcutaneous adipose tissue were identified, and the functional enrichment of the key modules was analyzed. Then, the “real” Hub gene was screened by in-module analysis and protein–protein interaction network (PPI), and its expression level in tissue samples and adipocytes was verified. The study showed that a total of nine co-expression modules were identified, and the number of genes in these modules ranged from 101 to 1,509. Among them, the blue module is most closely related to subcutaneous adipose tissue, containing 1,387 genes. These genes were significantly enriched in 10 gene ontologies including extracellular matrix organization, biological adhesion, and collagen metabolic process, and were mainly involved in pathways including ECM-receptor interaction, focal adhesion, cAMP signaling pathway, PI3K-AKT signaling pathway, and regulation of lipolysis in adipocytes. In the PPI network and coexpression network, five genes (CAV1, ITGA5, COL5A1, ABL1, and HSPG2) were identified as “real” Hub genes. Analysis of Hub gene expression by dataset revealed that the expression of these Hub genes was significantly higher in subcutaneous adipose tissue than in other tissues. In addition, real-time fluorescence quantitative PCR (qRT-PCR) analysis based on tissue samples and adipocytes also confirmed the above results.

Conclusion

In this study, five key genes related to subcutaneous adipose tissue were discovered, which laid a foundation for further study of the molecular regulation mechanism of subcutaneous adipose tissue development and adipose deposition.

Identification and Functional Verification Reveals that miR-195 Inhibiting THRSP to Affect Fat Deposition in Xinyang Buffalo

The buffalo population is extensive in China, but its meat quality is relatively inferior. Therefore, improving meat quality should be one of the breeding goals. microRNAs (miRNAs) play an essential regulatory role in the post-transcriptional expression of genes. Some studies have reported their function regulating genes related to fat deposition and adipocyte differentiation in cattle, but there is limited reports in buffalo. We performed small RNA transcriptome sequencing of Xinyang buffalo adipose tissue between calves and adults in this study. As a result, 282 mature miRNAs were significantly differentially expressed, and co-expression analysis showed that 454 miRNAs were significantly associated with developmental stages. Target gene identification, GO (gene ontology) annotation, and KEGG analysis of miRNAs showed that miR-195, miR-192, and miR-24-3p could target key genes for lipogenesis and thus regulate adipose deposition and differentiation. Among them, miR-195 was significantly upregulated in adipose tissue and induced adipocytes of adult buffaloes, and its overexpression significantly inhibited lipid accumulation in primary adipocytes. Dual-luciferase reporter gene analysis showed that miR-195 reduced the expression of thyroid hormone response protein (THRSP) by targeting its 3′ untranslated terminal region, suggesting that miR-195 may inhibit lipid accumulation in adipocytes by regulating THRSP. The results confirmed the reliability of predictive screening of miRNAs and provided theoretical support for buffalo fattening.

Intramuscular adipogenesis in cattle: Effects of body fat distribution and macrophage infiltration

Ectopic fat is defined by the deposition of adipose tissue within non-adipose tissue such as skeletal muscle. Japanese Black cattle (Wagyu) are characterized by the ability to accumulate high amounts of intramuscular adipose tissue. Obese conditions enhance the accumulation of ectopic fat. This review shows the effects of subcutaneous and visceral fat distribution on Wagyu intramuscular adipogenesis. Obese conditions also stimulate the macrophage infiltration into adipose tissues. Adipose tissue macrophages have reported to regulate adipose tissue growth and ectopic fat accumulation in humans and rodents. Wagyu is characterized by the higher capacity for intramuscular adipogenesis than Holsteins. This review discusses the depot-specific effects of macrophage infiltration among subcutaneous, visceral, and intramuscular adipose tissue on intramuscular adipogenesis in Wagyu and Holstein cattle. Recently, metabolome analysis has been used to identify obesity-related biomarkers by comparing the biological samples between lean and obese patients. This review introduces the metabolomic profiles of plasma and intramuscular adipose tissue between Wagyu and Holsteins.

Main regulatory factors of marbling level in beef cattle

The content of intramuscular fat (IMF), that determines marbling levels is considered as one of the vital factors influencing beef sensory quality including tenderness, juiciness, flavour and colour. The IMF formation in cattle commences around six months after conception, and continuously grows throughout the life of the animal. The accumulation of marbling is remarkably affected by genetic, sexual, nutritional and management factors. In this review, the adipogenesis and lipogenesis process regulated by various factors and genes during fetal and growing stages is briefly presented. We also discuss the findings of recent studies on the effects of breed, gene, heritability and gender on the marbling accumulation. Various research reported that feeding during pregnancy, concentrate to roughage ratios and the supplementation or restriction of vitamin A, C, and D are crucial nutritional factors affecting the formation and development of IMF. Castration and early weaning combined with high energy feeding are effective management strategies for improving the accumulation of IMF. Furthermore, age and weight at slaughter are also reviewed because they have significant effects on marbling levels. The combination of several factors could positively affect the improvement of the IMF deposition. Therefore, advanced strategies that simultaneously apply genetic, sexual, nutritional and management factors to achieve desired IMF content without detrimental impacts on feed efficiency in high-marbling beef production are essential.

miR-10a-5p Inhibits the Differentiation of Goat Intramuscular Preadipocytes by Targeting KLF8 in Goats

Intramuscular fat contributes to the improvement of meat quality of goats. MicroRNAs (miRNAs) have been reported to regulate adipocyte differentiation and maturation. The aim of our study was to clarify whether miR-10a-5p regulates goat intramuscular preadipocyte (GIPC) differentiation and its direct downstream signaling pathway. GIPCs were isolated from longissimus dorsi, whose miR-10a-5p level was measured at different time point of differentiation induction. Adipogenic differentiation of the GIPCs was evaluated by Oil Red O and BODIPY staining, and the expression changes of adipogenic genes like ACC, ATGL, CEBPβ, PPARγ, etc. Related mechanisms were verified by qPCR, a bioinformatic analysis, a dual-luciferase reporter assay, overexpression, and siRNA transfection. Oil Red O and BODIPY staining both with adipogenic gene detection showed that miR-10a-5p suppressed the accumulation of lipid droplets in GIPCs and inhibited its differentiation. The dual-luciferase reporter assay experiment revealed that miR-10a-5p regulates GIPC differentiation by directly binding to KLF8 3’UTR to regulate its expression. Thus, the results indicated that miR-10a-5p inhibits GIPC differentiation by targeting KLF8 and supply a new target for fat deposition and meat quality improvement.