Muscle Lipid Metabolism Research Articles

Replacement of Dietary Fishmeal with Clostridium autoethanogenum Protein on Lipidomics and Lipid Metabolism in Muscle of Pearl Gentian Grouper.

Clostridium autoethanogenum protein (CAP) is an economical and alternative protein source. Here, three experimental diets were formulated with CAP replacing 0% (CAP-0), 30% (CAP-30), and 60% (CAP-60) of fishmeal to investigate the alterations of structure integrity, fatty acids profiles, and lipid metabolism in the muscle of pearl gentian grouper. With increasing levels of CAP substitution, the percentages of 16 : 0 or 18 : 0 were decreased in triglycerides (TG) and diacylglycerols (DG); 18 : 1 or 18 : 2 was increased at the sn-1 and sn-2 positions in phosphatidylethanolamines; 20 : 5n-3 was increased in TG and DG. The phosphatidylcholines (PC) (18 : 3/20 : 5), PC(22 : 6/17 : 1), and sphingomyelins (d19 : 0/24 : 4) were identified as potential lipid biomarkers between CAP treatments. The CAP-30 treatment enhanced lipolysis and lipogenesis, while the CAP-60 treatment inhibited lipogenesis. In conclusion, fishmeal replacement with CAP affected the lipid characteristics and lipid metabolism, whereas it did not affect the structural integrity and fatty acids profiles in the muscle of pearl gentian grouper.

Dietary Supplementation with Rutin Alters Meat Quality, Fatty Acid Profile, Antioxidant Capacity, and Expression Levels of Genes Associated with Lipid Metabolism in Breast Muscle of Qingyuan Partridge Chickens.

Consumer demand for tasty and quality meat has been quickly increasing. This study investigated how dietary supplemented rutin affects meat quality, muscle fatty acid profile, and antioxidant capacity in the Chinese indigenous Qingyuan partridge chicken. A cohort of 180 healthy 119-day-old chickens was subjected to a randomized assignment into three groups, identified as the control, R200, and R400 groups, with respective supplementation of 0, 200, and 400 mg/kg of rutin. The results revealed insignificance in growth performance, namely, average daily gain, average daily feed intake, and feed-to-gain ratio, across the various treatment groups (p > 0.05). Nevertheless, dietary rutin supplementation increased (p < 0.05) breast muscle yield and intramuscular fat content in breast muscle and decreased (p < 0.05) drip loss in breast muscle. Rutin supplementation increased (p < 0.05) the content of high-density lipoprotein but decreased (p < 0.05) the contents of glucose, triglyceride, and total cholesterol in serum. Rutin supplementation increased (p < 0.05) the levels of DHA (C22:6n-3), total polyunsaturated fatty acids (PUFAs), n-3 PUFAs, decanoic acid (C10:0), the activity of Δ5 + Δ6 (22:6 (n - 3)/18:3 (n - 3)), and the ratio of PUFA/SFA in breast muscle but decreased (p < 0.05) the level of palmitoleic acid (C16:1n-7), the ratio of n-6/n-3 PUFAs, and the activity of Δ9 (16:1 (n - 7)/16:0). Rutin treatment also reduced (p < 0.05) the contents of malondialdehyde in serum and breast muscle, and increased (p < 0.05) the catalase activity and total antioxidant capacity in serum and breast muscle and the activity of total superoxide dismutase in serum. Additionally, rutin supplementation downregulated the expression of AMPKα and upregulated the expression of PPARG, FADS1, FAS, ELOVL7, NRF2, and CAT in breast muscle (p < 0.05). Convincingly, the results revealed that rutin supplementation improved meat quality, fatty acid profiles, especially n-3 PUFAs, and the antioxidant capacity of Qingyuan partridge chickens.

Intermittent Fasting Sustainably Improves Glucose Tolerance in Normal Weight Male Mice Through Histone Hyperacetylation

Abstract To explore the mechanism by which intermittent fasting (IF) exerts prolonged effects after discontinuation, we examined mice that had been subjected to 4 cycles of fasting for 72 hours and ad libitum feeding for 96 hours per week (72hIF), followed by 4 weeks of ad libitum feeding, focusing on expression of genes for lipid metabolism in the skeletal muscle and histone acetylation in the promoter region. The 72hIF regimen resulted in metabolic remodeling, characterized by enhanced lipid utilization and mitochondrial activation in the muscle. This long-term IF (72hIF) caused stronger metabolic effects than alternate day fasting (24hIF) wherein fasting and refeeding are repeated every 24 hours. Upregulation of lipid oxidation genes and an increase in oxygen utilization were sustained even at 4 weeks after discontinuation of 72hIF, associated with histone hyperacetylation of the promoter region of uncoupling protein 3 (Ucp3) and carnitine palmitoyl transferase 1b (Cpt1b) genes. An increase in leucine owing to fasting-induced muscle degradation was suggested to lead to the histone acetylation. These findings support the previously unappreciated notion that sustainable promotion of histone acetylation in lipid oxidation genes of the muscle and adipose tissues during and after IF may contribute to sustained metabolic effects of IF.

O098 Diclofenac alters expression of genes regulating muscle lipid metabolism during resistance exercise training in humans, but does not change IMCL content

Abstract Introduction Diclofenac is an NSAID commonly used off-label to reputedly enhance athletic training adaptation. Diclofenac activates PPAR-γ and upregulates the expression of lipid metabolism genes in vitro. This study investigated the impact of diclofenac administration on IMCL content and muscle genes regulating lipid metabolism during resistance exercise training in healthy volunteers. Methods Following informed consent and screening, 17 healthy, young, exercise-trained males matched for leg strength were allocated to Diclofenac (75mg diclofenac sodium daily, n=9) or Placebo (n=8) groups. Participants performed 5×30 sets of maximal isokinetic (90°/s) knee extensions with the non-dominant leg 3× weekly over 12 weeks. Vastus lateralis biopsies were obtained in the fasted state at baseline and 1, 7, 28, and 84 days of training for histochemical determination of IMCL content and muscle mRNA expression using microfluidic gene cards. IPA identified gene networks altered from baseline. Results There were significant changes in muscle mRNA expression levels associated with the upregulation of muscle lipid metabolism at all time points compared to baseline in Diclofenac. This was not evident in Placebo, where the inhibition of lipid metabolism was predicted by day 84. Mean (±SEM) IMCL content was no different between groups at baseline (7.4±3.8% Placebo vs. 6.9±2.6% Diclofenac), and no time/treatment interactions with resistance exercise training were observed (ηp2=0.07). Conclusion Diclofenac administration had a rapid, robust impact on genes regulating muscle lipid metabolism during 12 weeks of exercise training in humans. However, these responses were not associated with changes in IMCL content and further investigation is warranted.

Filbertone, (2E)-5-methyl-2-hepten-4-one, regulates thermogenesis and lipid metabolism in skeletal muscle of a high-fat diet fed mice

Filbertone, the principal flavor compound of hazelnuts, is known to have preventive effects against hypothalamic inflammation, obesity and adipocity in vitro and in vivo. However, the effect of filbertone in skeletal muscle remains unknown. In the present study, we determined the effect of filbertone in skeletal muscle of mice fed a high-fat diet (HFD). To identify the underlying molecular and cellular processes of filbertone, we performed whole transcriptome sequencing in skeletal muscle. The muscle transcriptome analysis revealed that the upregulated differentially expressed genes (DEGs) in filbertone-fed mice were substantially associated with several pathways including thermogenesis, fatty acid degradation, oxidative phosphorylation, and branched chain amino acids (BCAAs) degradation. Furthermore, the expression level of thermogenic genes such as uncoupling protein 1 (Ucp1; p < 0.05), cell death-inducing DNA fragmentation factor alpha-like effector A (Cidea; p < 0.05), peroxisome proliferator-activated receptor alpha (Ppara; p < 0.05) and lipid droplet-associated protein genes such as Plin3 (p < 0.05), Plin4 (p < 0.05), and Plin5 (p < 0.05) were significantly upregulated in muscle tissue of HFD with filbertone fed mice compared to HFD only fed mice. Filbertone also elevated the protein level of UCP1 (p < 0.05) and PPARα (p < 0.05). In addition, filbertone reduced the accumulation of intracellular lipids in C2C12 myotubes (p < 0.05). On the basis of these results, we suggest that filbertone has a crucial effect in the regulation of muscle lipid metabolism and energy balance.

Effects of high-grain diet feeding on fatty acid profiles in milk, blood, muscle, and adipose tissue, and transcriptional expression of lipid-related genes in muscle and adipose tissue of dairy cows

BackgroundHigh-grain (HG) diets affect lipid metabolism in the liver and mammary tissue of dairy cows, but its effects on muscle and adipose tissue have not been wide evaluated. Thus, the aim of this study is to clarify this issue.MethodsTwelve Holstein cows were randomly divided into two groups: conventional diet group (CON, n = 6) and the HG diet group (n = 6). On day 7 of week 4, rumen fluid was sampled to measure pH, milk was sampled to measure components, and blood was sampled to measure biochemical parameters and fatty acid composition. After the experiment, cows were slaughtered to collect muscle and adipose tissue for fatty acid composition and transcriptome analysis.ResultsHG feeding decreased the ruminal pH, milk’s fat content and long-chain fatty acid proportion (P < 0.05) and increased the proportion of short- and medium-chain fatty acids in the milk (P < 0.05) as compared with CON diets. The concentrations of blood cholesterol, low-density lipoprotein, and polyunsaturated fatty acids in the HG cows were lower than those in CON cows (P < 0.05). In muscle tissue, HG feeding tended to increase the triacylglycerol (TG) concentration (P < 0.10). Transcriptome analysis revealed changes in the biosynthesis of the unsaturated fatty acids pathway, the regulation of lipolysis in the adipocytes pathway, and the PPAR signalling pathway. In adipose tissue, HG feeding increased the concentration of TG and decreased the concentration of C18:1 cis9 (P < 0.05). At the transcriptome level, the fatty acid biosynthesis pathway, linoleic acid metabolism pathway, and PPAR signalling pathway were activated.ConclusionHG feeding leads to subacute rumen acidosis and a decreased milk fat content. The fatty acid profiles in the milk and plasma of dairy cows were changed by HG feeding. In muscle and adipose tissue, HG feeding increased TG concentration and up-regulated the expression of genes related to adipogenesis, while down-regulated the expression of genes related to lipid transport. These results complement our knowledge of the fatty acid composition of muscle and adipose tissue in dairy cows and expand our understanding of the mechanisms by which HG diets affect lipid metabolism in muscle and adipose tissue.

Integrative metabolomic and transcriptomic analysis reveals difference in glucose and lipid metabolism in the longissimus muscle of Luchuan and Duroc pigs.

Luchuan pig, an obese indigenous Chinese porcine breed, has a desirable meat quality and reproductive capacity. Duroc, a traditional western breed, shows a faster growth rate, high feed efficiency and high lean meat rate. Given the unique features these two porcine breeds have, it is of interest to investigate the underlying molecular mechanisms behind their distinctive nature. In this study, the metabolic and transcriptomic profiles of longissimus dorsi muscle from Duroc and Luchuan pigs were compared. A total of 609 metabolites were identified, 77 of which were significantly decreased in Luchuan compared to Duroc, and 71 of which were significantly elevated. Most differentially accumulated metabolites (DAMs) upregulated in Luchuan were glycerophospholipids, fatty acids, oxidized lipids, alcohols, and amines, while metabolites downregulated in Luchuan were mostly amino acids, organic acids and nucleic acids, bile acids and hormones. From our RNA-sequencing (RNA-seq) data we identified a total of 3638 differentially expressed genes (DEGs), 1802 upregulated and 1836 downregulated in Luchuan skeletal muscle compared to Duroc. Combined multivariate and pathway enrichment analyses of metabolome and transcriptome results revealed that many of the DEGs and DAMs are associated with critical energy metabolic pathways, especially those related to glucose and lipid metabolism. We examined the expression of important DEGs in two pathways, AMP-activated protein kinase (AMPK) signaling pathway and fructose and mannose metabolism, using Real-Time Quantitative Reverse Transcription PCR (qRT-PCR). Genes related to glucose uptake, glycolysis, glycogen synthesis, fatty acid synthesis (PFKFB1, PFKFB4, MPI, TPI1, GYS1, SLC2A4, FASN, IRS1, ULK1) are more activated in Luchuan, while genes related to fatty acid oxidation, cholesterol synthesis (CPT1A, HMGCR, FOXO3) are more suppressed. Energy utilization can be a decisive factor to the distinctive metabolic, physiological and nutritional characteristics in skeletal muscle of the two breeds we studied. Our research may facilitate future porcine breeding projects and can be used to reveal the potential molecular basis of differences in complex traits between various breeds.

Effects of dietary disodium fumarate supplementation on muscle quality, chemical composition, oxidative stress and lipid metabolism of Hu sheep induced by high concentrate diet

Long-term feeding of high-concentrate (HC) diet causes the decrease of rumen pH, and induces subacute rumen acidosis (SARA), which results in metabolic disorders in sheep. This not only reduces animal performance, but also increases the risk of oxidative stress and inflammatory reaction. Disodium fumarate can improve the rumen buffering capacity and increase rumen pH. This experiment was conducted to investigate the effects of high concentrate diet on muscle quality, chemical composition, oxidative damage and lipid metabolism of Hu sheep, and the regulating effect of disodium fumarate. The results showed that HC diet induced SARA by reducing rumen pH value, thus causing oxidative stress and lipid metabolism disorder in longissimus lumborum (LL) muscle of Hu sheep, which also reduced meat quality by increasing shear force, drip loss, cooking loss, chewiness and hardness, and reducing the contents of crude fat and crude protein in LL muscle. However, disodium fumarate can improve meat quality of SARA Hu sheep by regulating rumen pH, inhibiting muscle oxidative stress and promoting lipid metabolism.

Antiatherosclerotic Effect and Molecular Mechanism of Salidroside.

Atherosclerotic cardiovascular disease is currently the leading cause of death worldwide. Its pathophysiological basis includes endothelial dysfunction, macrophage activation, vascular smooth muscle cell (VSMC) proliferation, lipid metabolism, platelet aggregation, and changes in the gut microbiota. Salidroside has beneficial effects on atherosclerosis through multiple pathways. In this review, we present studies on the regulatory effect of salidroside on atherosclerosis. Furthermore, we report the protective effects of salidroside against atherosclerosis by ameliorating endothelial dysfunction, suppressing macrophage activation and polarization, inhibiting VSMC proliferation, adjusting lipid metabolism, attenuating platelet aggregation, and modulating the gut microbiota. This review provides further understanding of the molecular mechanism of salidroside and new ideas for atherosclerosis management.

Low-Carbohydrate Diet Modulates Glucose–Lipid Utilization in Skeletal Muscle of Diabetic Mice

Type 2 diabetes is associated with many complications, including skeletal muscle atrophy. Ketogenic diets and low-carbohydrate diets (LCD) have recently been introduced as dietary interventions in patients with diabetes, but their effects on glucose and lipid metabolism in skeletal muscle have not been studied. In the current study, we compared the effects of LCD and ketogenic diet on glucose and lipid metabolism in skeletal muscle of diabetic mice. C57BL/6J mice with type 2 diabetes, constructed by a high-fat diet combined with streptozotocin, were fed a standard diet, a high-fat diet, an LCD, or a ketogenic diet for 14 weeks, respectively. Here, we found that the LCD, rather than the ketogenic diet, retained skeletal muscle weight and suppressed the expression of atrophy-related genes in diabetic mice. In addition, the LCD had more glycolytic/type IIb myofiber content and inhibited forkhead box O1 and pyruvate dehydrogenase kinase 4 expression, leading to improved glucose utilization. However, the ketogenic diet maintained more oxidative/type I myofibers. Moreover, compared with the ketogenic diet, the LCD decreased intramuscular triglycerides content and muscle lipolysis, suggesting improvement in lipid metabolism. Taken together, these data suggested that the LCD improved glucose utilization, and inhibited lipolysis and atrophy in skeletal muscle of diabetic mice, while the ketogenic diet showed metabolic disorders in skeletal muscle.

Improving flesh quality of grass carp (Ctenopharyngodon idellus) by completely replacing dietary soybean meal with yellow mealworm (Tenebrio molitor).

In order to find viable alternative protein sources for aquaculture, we evaluated the effect of partial or complete replacement of dietary soybean meal with yellow mealworm (TM) on the flesh quality of grass carp. In this study, 180 grass carp (511.85±0.25g) were fed 3 experimental diets in which 0% (CN), 30% (YM30) and 100% (YM100) dietary soybean meal was replaced by TM for 90d. The results showed that growth performance, biological parameters and serum antioxidant capacity of grass carp were not affected by dietary TM (P>0.05). Both muscle and whole body crude protein were obviously promoted with the increase of dietary TM (P<0.05), and the concentration of heavy metal in muscle was not influenced (P>0.05), indicating that food safety was not influenced by TM. Dietary TM improved muscle textural characteristics by elevating adhesiveness, springiness and chewiness in YM100 (P<0.05). In addition, the muscle tenderness was significantly increased by declining the shear force (P<0.05). The muscle fiber density in YM30 &YM100 and length of dark bands and sarcomeres in YM100 were obviously increased (P<0.05). The expression of myf5, myog and myhc exhibited a significant upward trend with the increase of dietary TM (P<0.05), which promoted fiber density, length of sarcomere and texture of grass carp muscle. According to the results of metabolomics, the arachidonate (ARA) and eicosapentaenoic acid (EPA) were notably elevated in YM30 and YM100, which indicated that the improvement of flesh quality of grass carp may contribute to the dietary TM influence on muscle lipid metabolism, especially the polyunsaturated fatty acids. In conclusion, TM can completely replace dietary soybean meal and improve the nutritional value of grass carp.

Muscular lipidomics and transcriptomics reveal the effects of bile acids on lipid metabolism in high-fat diet-fed grouper.

Little information is available on how exogenous bile acids alter lipid metabolism in muscle of fish. In the present study, an 8-week feeding trial were used to investigate the impacts of bile acids on lipid deposition, lipid metabolism, lipidomics, and transcriptomics in muscle of pearl gentian grouper (Epinephelus fuscoguttatus♀ × E. lanceolatus♂) fed a high-fat diet (HD). The HD treatment significantly increased the crude lipid content, while bile acids diet (BD) treatment decreased it (p = 0.057). BD treatment significantly decreased triglycerides level and significantly increased phosphatidylcholines, phosphatidylethanolamines, and phosphatidylglycerol levels. The contents of TG (17:0/18:2/18:2), TG (17:1/18:2/22:6), PC (6:0/22:1), PC (9:0/26:1), PC (26:1/6:0), PC (17:2/18:2), PE (16:0/18:1), PE (18:0/17:1), PG (18:0/20:5), PG (18:3/20:5), PG (19:0/16:1), and PG (18:0/18:1) in muscle were well response to dietary lipid level and bile acids supplementation. HD and BD groups induced a variety of adaptive metabolic responses in transcriptomics. HD treatment increased the lipogenesis and decreased lipolysis, whereas BD treatment decreased the lipogenesis and increased lipolysis. Present study revealed the improvement of muscular lipid metabolism and lipid composition in response to bile acids administration in pearl gentian grouper.

Accumulation of polyunsaturated fatty acid-derived metabolites in the sarcopenic muscle of aging mice.

Although it is known that advanced age alters skeletal muscle lipid metabolism, the role(s) of polyunsaturated fatty acid-derived metabolites (mostly eicosanoids and docosanoids) in sarcopenia are not clear. We therefore examined the changes in the metabolites of arachidonic acid, eicosapentaenoic acid and docosahexaenoic acid in the sarcopenic muscle of aged mice. We used 6- and 24-month-old male C57BL/6J mice as healthy and sarcopenic muscle models, respectively. Skeletal muscles were removed from the lower limb and subjected to a liquid chromatography-tandem mass spectrometry analysis. The liquid chromatography-tandem mass spectrometry analysis detected distinct changes of metabolites in the muscles of the aged mice. Of the 63 metabolites identified, nine were significantly higher in the sarcopenic muscle of aged mice compared with the healthy muscle of young mice. In particular, prostaglandin E2 , prostaglandin F2a , thromboxane B2 , 5-hydroxyeicosatetraenoic acid, and 15-oxo-eicosatetraenoic acid (arachidonic acid-derived metabolites), 12-hydroxy-eicosapentaenoic acid and 14,15-epoxy-eicosatetraenoic acid (eicosapentaenoic acid-derived metabolites) and 10-hydroxydocosa-hexaenoic acid and 14-hydroxyoctadeca-pentaenoic acid (docosahexaenoic acid-derived metabolites) were significantly higher in aged tissue compared with young tissue (all P< 0.05). We observed the accumulation of metabolites in the sarcopenic muscle of aged mice. Our results may provide new insights into the pathogenesis and progression of aging- or disease-related sarcopenia. Geriatr Gerontol Int 2023; 23: 297-303.

Effects of Long-Term Physical Activity and BCAA Availability on the Subcellular Associations between Intramyocellular Lipids, Perilipins and PGC-1α.

Cellular skeletal muscle lipid metabolism is of paramount importance for metabolic health, specifically through its connection to branched-chain amino acids (BCAA) metabolism and through its modulation by exercise. In this study, we aimed at better understanding intramyocellular lipids (IMCL) and their related key proteins in response to physical activity and BCAA deprivation. By means of confocal microscopy, we examined IMCL and the lipid droplet coating proteins PLIN2 and PLIN5 in human twin pairs discordant for physical activity. Additionally, in order to study IMCLs, PLINs and their association to peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) in cytosolic and nuclear pools, we mimicked exercise-induced contractions in C2C12 myotubes by electrical pulse stimulation (EPS), with or without BCAA deprivation. The life-long physically active twins displayed an increased IMCL signal in type I fibers when compared to their inactive twin pair. Moreover, the inactive twins showed a decreased association between PLIN2 and IMCL. Similarly, in the C2C12 cell line, PLIN2 dissociated from IMCL when myotubes were deprived of BCAA, especially when contracting. In addition, in myotubes, EPS led to an increase in nuclear PLIN5 signal and its associations with IMCL and PGC-1α. This study demonstrates how physical activity and BCAA availability affects IMCL and their associated proteins, providing further and novel evidence for the link between the BCAA, energy and lipid metabolisms.

Exposure to waterborne cadmium induce disorder of lipid metabolism, antioxidant system and autophagy in the muscle of crayfish Procambarus clarkii

Cadmium (Cd) is a non-essential toxic metal in the body, which can cause harmful effects on the aquatic environment and aquatic organisms. In this study, the effects of acute Cd exposure on lipid metabolism disorder, oxidative stress and autophagy in abdominal muscles of Procambarus clarkii were investigated, as well the underlying molecular mechanisms were explored. P. clarkii were exposed to 0 (control), 1 and 5 mg Cd/l, respectively, for 5 days. We found that TG content, fas, hsl, and cpt1 gene expression levels, as well as the Srebp1 protein content in abdominal muscle decreased with the Cd concentrations increased, indicating that acute Cd exposure induced disorder of lipid metabolism in the abdominal muscle of P. clarkii. Further studies showed that acute Cd exposure provoked oxidative stress in the abdominal muscle of P. clarkii by increasing the accumulation of malondialdehyde (MDA) in the abdominal muscle. The oxidative stress of abdominal muscle induced by acute Cd exposure may be due to the reduction of catalases (CAT) and glutathione peroxidase (GPX) enzyme activities and Nrf2 protein content in the nucleus. The expression levels of autophagy-related genes (beclin1, atg101, atg13, atg3, atg4b, atg5, atg7, lc3a, lc3c atg9a) were also affected by acute Cd exposure, suggesting that acute Cd exposure also affected autophagy activity in abdominal muscle of P. clarkii. Our research indicates that waterborne acute Cd exposure can induce lipid metabolism disorder, and oxidative stress, and inhibit the expression of genes that trigger autophagy in the abdominal muscle of P. clarkii. These results may be useful for understanding the mechanism of Cd muscular toxicity in crustaceans.

Utilizing Variants Identified with Multiple Genome-Wide Association Study Methods Optimizes Genomic Selection for Growth Traits in Pigs

Improving the prediction accuracies of economically important traits in genomic selection (GS) is a main objective for researchers and breeders in the livestock industry. This study aims at utilizing potentially functional SNPs and QTLs identified with various genome-wide association study (GWAS) models in GS of pig growth traits. We used three well-established GWAS methods, including the mixed linear model, Bayesian model and meta-analysis, as well as 60K SNP-chip and whole genome sequence (WGS) data from 1734 Yorkshire and 1123 Landrace pigs to detect SNPs related to four growth traits: average daily gain, backfat thickness, body weight and birth weight. A total of 1485 significant loci and 24 candidate genes which are involved in skeletal muscle development, fatty deposition, lipid metabolism and insulin resistance were identified. Compared with using all SNP-chip data, GS with the pre-selected functional SNPs in the standard genomic best linear unbiased prediction (GBLUP), and a two-kernel based GBLUP model yielded average gains in accuracy by 4 to 46% (from 0.19 ± 0.07 to 0.56 ± 0.07) and 5 to 27% (from 0.16 ± 0.06 to 0.57 ± 0.05) for the four traits, respectively, suggesting that the prioritization of preselected functional markers in GS models had the potential to improve prediction accuracies for certain traits in livestock breeding.

Cold exposure alters lipid metabolism of skeletal muscle through HIF-1α-induced mitophagy

BackgroundIn addition to its contractile properties and role in movement, skeletal muscle plays an important function in regulating whole-body glucose and lipid metabolism. A central component of such regulation is mitochondria, whose quality and function are essential in maintaining proper metabolic homeostasis, with defects in processes such as autophagy and mitophagy involved in mitochondria quality control impairing skeletal muscle mass and function, and potentially leading to a number of associated diseases. Cold exposure has been reported to markedly induce metabolic remodeling and enhance insulin sensitivity in the whole body by regulating mitochondrial biogenesis. However, changes in lipid metabolism and lipidomic profiles in skeletal muscle in response to cold exposure are unclear. Here, we generated lipidomic or transcriptome profiles of mouse skeletal muscle following cold induction, to dissect the molecular mechanisms regulating lipid metabolism upon acute cold treatment.ResultsOur results indicated that short-term cold exposure (3 days) can lead to a significant increase in intramuscular fat deposition. Lipidomic analyses revealed that a cold challenge altered the overall lipid composition by increasing the content of triglyceride (TG), lysophosphatidylcholine (LPC), and lysophosphatidylethanolamine (LPE), while decreasing sphingomyelin (SM), validating lipid remodeling during the cold environment. In addition, RNA-seq and qPCR analysis showed that cold exposure promoted the expression of genes related to lipolysis and fatty acid biosynthesis. These marked changes in metabolic effects were associated with mitophagy and muscle signaling pathways, which were accompanied by increased TG deposition and impaired fatty acid oxidation. Mechanistically, HIF-1α signaling was highly activated in response to the cold challenge, which may contribute to intramuscular fat deposition and enhanced mitophagy in a cold environment.ConclusionsOverall, our data revealed the adaptive changes of skeletal muscle associated with lipidomic and transcriptomic profiles upon cold exposure. We described the significant alterations in the composition of specific lipid species and expression of genes involved in glucose and fatty acid metabolism. Cold-mediated mitophagy may play a critical role in modulating lipid metabolism in skeletal muscle, which is precisely regulated by HIF-1α signaling.

Enriched functional milk fat ameliorates glucose intolerance and triacylglycerol accumulation in skeletal muscle of rats fed high-fat diets.

We examined the effect of a functional milk fat (FMF) on the glucose metabolism and its association with the intramuscular triacylglycerol (TAG) content in rats fed high-fat diets. Male Wistar rats were fed for 60days with S7 (soybean oil 7%), S30 (soybean oil 30%), MF30 (soybean oil 3% + milk fat 27%), or FMF30 (soybean oil 3% + FMF 27%) diets. An oral glucose tolerance test was performed. The levels of key metabolites in gastrocnemius muscle and mRNA levels of genes involved in glucose and lipid metabolism in muscle, epididymal white adipose tissue (EWAT), and serum were assessed. The S30 diet induced glucose intolerance and led to TAG, citrate, and glucose accumulation in muscle. Moreover, we observed a downregulation of uncoupling proteins (Ucp2 and Ucp3) and insulin receptor substrate-1 (Irs1) genes, lower carnitine palmitoyl transferase-1b (CPT-1b), and phosphofructokinase-1 (PFK1) activities in muscle and lower expression of adiponectin (Adipoq) in EWAT. The FMF30 diet ameliorated the glucose intolerance and normalized the glucose and TAG levels in muscle, preventing the accumulation of citrate and enhancing glucose utilization by the PFK1. The beneficial effects might also be related to the higher expression of Adipoq in EWAT, its receptor in muscle (Adipor1), and the expression of Ucp2, Ucp3, and Irs1 in muscle, restoring the alterations observed with the S30 diet. FMF30 modulated key genes involved in glucose and lipid metabolism in skeletal muscle, improving the glucose utilization and preventing TAG, glucose, and citrate accumulation.

Long-Term Dietary Supplementation with Betaine Improves Growth Performance, Meat Quality and Intramuscular Fat Deposition in Growing-Finishing Pigs.

This study was designed to investigate the effects of dietary betaine supplementation on growth performance, meat quality and muscle lipid metabolism of growing-finishing pigs. Thirty-six crossbred pigs weighing 24.68 ± 0.97 kg were randomly allotted into two treatments consisting of a basal diet supplemented with 0 or 1200 mg/kg betaine. Each treatment included six replications of three pigs per pen. Following 119 days of feeding trial, dietary betaine supplementation significantly enhanced average daily gain (ADG) (p < 0.05) and tended to improve average daily feed intake (ADFI) (p = 0.08) and decreased the feed intake to gain ratio (F/G) (p = 0.09) in pigs during 100~125 kg. Furthermore, a tendency to increase ADG (p = 0.09) and finial body weight (p = 0.09) of pigs over the whole period was observed in the betaine diet group. Betaine supplementation significantly increased a*45 min and marbling and decreased b*24 h and cooking loss in longissimus lumborum (p < 0.05), tended to increase intramuscular fat (IMF) content (p = 0.08), however had no significant influence on carcass characteristics (p > 0.05). Betaine supplementation influenced the lipid metabolism of pigs, evidenced by a lower serum concentration of low-density lipoprotein cholesterol (p < 0.05), an up-regulation of mRNA abundance of fatty acid synthase and acetyl-CoA carboxylase (p < 0.05), and a down-regulation of mRNA abundance of lipolysis-related genes, including the silent information regulators of transcription 1 (p = 0.08), peroxisome proliferator-activated receptorα (p < 0.05), peroxisome proliferator-activated receptor gamma coactivator-1α (p = 0.07) and carnitine palmitoyl transferase 1 (p < 0.05) in longissimus lumborum. Moreover, betaine markedly improved the expression of microRNA-181a (miR-181a) (p < 0.05) and tended to enhance miR-370 (p = 0.08). Overall, betaine supplementation at 1200 mg/kg could increase the growth performance of growing-finishing pigs. Furthermore, betaine had a trend to improve meat quality and IMF content via increasing lipogenesis and down-regulating the abundance of genes associated with lipolysis, respectively, which was associated with the regulation of miR-181a and miR-370 expression by betaine.

Desorption electrospray ionization-mass spectrometry imaging of carnitine and imidazole dipeptides in pork chop tissues

Carnitine is essential for energy production and lipid metabolism in skeletal muscle. Carnosine and its methylated analogs anserine and balenine are histidine-containing imidazole dipeptides, which are antioxidative compounds. They are major health-related components in meat; however, analytical technique to investigate their distribution among tissues have not fully established. Here, we performed desorption electrospray ionization (DESI)-mass spectrometry imaging (MSI) of pork chop sections containing longissimus thoracis et lumborum muscle (loin), intermuscular fat tissue, transparent tissue, and spinalis muscle to investigate the distributions of carnitine and imidazole dipeptides. Liquid chromatography-MS revealed that the concentrations of carnitine, carnosine, anserine, and balenine were 11.0 ± 0.9, 330.1 ± 15.5, 21.2 ± 1.5, and 9.6 ± 0.5 mg/100 g, respectively. In the mass spectrum obtained by DESI-MSI, peaks corresponding to the chemical formulae of carnitine and imidazole dipeptides were detected. DESI-MSI provided definite identification of carnitine, while DESI-tandem MSI (MS/MSI) was necessary to accurately visualize carnosine, anserine, and balenine. Carnitine and these imidazole dipeptides were mainly distributed in the loin and spinalis muscle, while their distribution was not uniform in both muscle tissues. In addition, the balance between both tissues were different. The concentration of carnitine was higher in the spinalis muscle than that in the loin, while those of imidazole dipeptides were higher in the loin than those in the spinalis muscle. These results were consistent with those obtained by liquid chromatography-MS quantification, suggest that DESI-MSI analysis is useful for the distribution analysis of carnitine and imidazole dipeptides in meat.