Muscle mRNA Levels Research Articles

High-Intensity Interval Training Mitigates Sarcopenia and Suppresses the Myoblast Senescence Regulator EEF1E1.

The optimal exercise regimen for alleviating sarcopenia remains uncertain. This study aimed to investigate the efficacy of high-intensity interval training (HIIT) over moderate-intensity continuous training (MICT) in ameliorating sarcopenia. We conducted a randomized crossover trial to evaluate plasma proteomic reactions to acute HIIT (four 4-min high-intensity intervals at 70% maximal capacity alternating with 4 min at 30%) versus MICT (constant 50% maximal capacity) in inactive adults. We explored the relationship between a HIIT-specific protein relative to MICT, identified via comparative proteomic analysis, eukaryotic translation elongation factor 1 epsilon 1 (EEF1E1) and sarcopenia in a paired case-control study of elderly individuals (aged over 65). Young (3 months old) and aged (20 months old) mice were randomized to sedentary, HIIT and MICT groups (five sessions/week for 4 weeks; n = 8 for each group). Measurements included skeletal muscle index, hand grip strength, expression of atrophic markers Atrogin1 and MuRF1 and differentiation markers MyoD, myogenin and MyHC-II via western blotting. We examined the impact of EEF1E1 siRNA and recombinant protein on D-galactose-induced myoblast senescence, measuring senescence-associated β-galactosidase and markers like p21 and p53. The crossover trial, including 10 sedentary adults (32 years old, IQR 31-32) demonstrated significant alterations in the abundance of 21 plasma proteins after HIIT compared with MICT. In the paired case-control study of 84 older adults (84 years old, IQR 69-81; 52% female), EEF1E1 was significantly increased in those with sarcopenia compared to those without (14.68 [95%CI, 2.02-27.34] pg/mL, p = 0.03) and was associated with skeletal muscle index (R2 = 0.51, p < 0.001) and hand grip strength (R2 = 0.54, p < 0.001). In the preclinical study, aged mice exhibited higher EEF1E1 mRNA and protein levels in skeletal muscle compared to young mice, accompanied by a lower muscle mass and strength, increased cellular senescence and protein degradation markers and reduced muscle differentiation efficiency (all p < 0.05). HIIT reduced EEF1E1 expression and mitigated age-related muscle decline and atrophy in aged mice more effectively than MICT. Notably, EEF1E1 downregulation via siRNA significantly counteracted D-galactose-induced myoblast senescence as evidenced by reduced markers of muscle protein degradation and improved muscle differentiation efficiency (all p < 0.05). Conversely, treatments that increased EEF1E1 levels accelerated the senescence process (p < 0.05). Further exploration indicated that the decrease in EEF1E1 was associated with increased SIRT1 level and enhanced autophagy. This study highlights the potential of HIIT as a promising approach to prevent and treat sarcopenia while also highlighting EEF1E1 as a potential intervention target.

Effects of high-dose selenium-enriched Saccharomyces cerevisiae on growth performance, antioxidant status, tissue fat content and selenium concentration, and selenoenzyme mRNA expression in chicks

Selenium-enriched Saccharomyces cerevisiae (SSC) as organic selenium (Se) has been shown to have better advantages and is approved for use in animal feed rather than inorganic Se, however, there is little available data on the toxic effects of SSC on poultry. The present study was conducted to investigate the effects of high-dose SSC on growth performance, antioxidant status, tissue fat content and Se concentration, and selenoenzyme mRNA expression in chicks. A total of 500, 1-day-old SPF chicks were randomly divided into 5 groups with 10 replicates of 10 chicks each. Group 1 served as a control and was fed a basal diet supplemented with 0.15 mg/kg Se from sodium selenite (SS), group 2 was fed the basic diet supplemented with 1.5 mg/kg Se from SS, while groups 3, 4, and 5 were fed the basal diet supplemented with 1.5, 5 and 10 mg/kg Se from SSC, respectively. The results showed that SS and SSC supplementation significantly affected the average daily feed intake (ADFI), feed/gain ratio (FCR), glutathione peroxidase (GPx) and superoxide dismutase (SOD) activities, total antioxidant capacity (T-AOC), malondialdehyde (MDA) content, tissue fat content and Se concentration, and GPx1 and GPx4 mRNA levels compared with the control group (P < 0.05). Compared with group 2, group 3 exhibited higher GPx and SOD activities, tissue Se concentration, and lower MDA content on d 30, and higher Se concentration, GPx1 mRNA levels in liver and breast muscle and GPx4 mRNA levels in liver and thigh muscle, and lower MDA content on d 60 (P < 0.05). The results of correlation analysis showed that high-dose SSC supplementation was positively correlated with AFDI, FCR, MDA content, and tissue Se concentration, and negatively correlated with GPx and SOD activities, T-AOC, GPx1 and GPx4 mRNA levels in tissues. In conclusion, up to 1.5 mg/kg Se from SSC in diet may be a safe concentration for chicks that exhibited better biological effects than SS, the toxic effects of high-dose SSC supplementation mainly exhibited growth decrease, peroxidation and lipid metabolism disturbance, and became stronger with the increase of dietary Se levels.

Paternal exercise induces antioxidant defenses by α-Klotho/Keap1 pathways in the skeletal muscle of offspring exposed to a high fat-diet without changing telomere length

Although previous studies demonstrated that the ancestral lifestyle can enhance the metabolic health of offspring exposed to an obesogenic diet, the specific connections between these positive effects in redox state and telomere length are unknown. We investigated the impact of paternal resistance training (RT) on stress-responsive signaling and the pathways involved in telomere homeostasis in skeletal muscle. This investigation encompassed both the fathers and first-generation litter exposed to a long-term standard diet (24 weeks) and high fat diet (HFD). Wistar rats were randomized into sedentary or trained fathers (8 weeks of resistance training). The offspring were obtained by mating with sedentary females. Upon weaning, male offspring were divided into four groups: offspring of sedentary or trained fathers exposed to either a control diet or HFD. The gastrocnemius was prepared for reverse transcription-quantitative polymerase chain reaction, immunoblotting, ELISA, and electron paramagnetic resonance spectroscopy. RT upregulated shelterin mRNA levels and antioxidant protein, preserving muscle telomere in fathers. Conversely, HFD induced a disturbance in the redox balance, which may have contributed to the offspring telomere shortening from sedentary fathers. Preconceptional paternal RT downregulates Kelch-like ECH-associated protein 1 (Keap1) mRNA levels in the skeletal muscle of progeny exposed to HFD, driving an increase in Glutathione reductase mRNA levels, Sod1 and Catalase protein levels to mitigate ROS production. Also, paternal exercise upregulates α-Klotho protein levels, mediating antioxidative responses without altering shelterin mRNA levels and telomere length. We provide the first in-depth analysis that the offspring's redox state seems to be directly associated with the beneficial effects of paternal exercise.

Jaboticaba (Plinia jaboticaba (Vell.) Berg) polyphenols alleviate skeletal muscle insulin resistance by modulating PI3K/Akt/GLUT-4 and AMPK signaling pathways in diet-induced obese mice

Skeletal muscle responds for most of the insulin-stimulated glucose disposal at postprandial state, impacting glucose homeostasis. Polyphenols were shown to prevent obesity-associated glucose intolerance and peripheral insulin resistance in animal models, but the implication of skeletal muscle to these effects is unclear. We investigated the role of polyphenolic extracts from jaboticaba (Plinia jaboticaba (Vell.) Berg) (PEJ), a Brazilian native species, on skeletal muscle insulin resistance in diet-induced obese mice. PEJ administration was associated with an increase in skeletal muscle protein content of glucose transporter-4 (GLUT-4) and AMP-activated protein kinase (AMPK) phosphorylated at Thr172. PEJ also reduced skeletal muscle mRNA levels of inflammatory genes nuclear factor-ҡB (NF-κB), tumoral necrose factor-α (TNF-α), interleukin 1β (IL-1β), and c-Jun N-terminal kinase (JNK). This study demonstrates that polyphenols from jaboticaba may be a valuable therapeutic agent in the management and prevention of obesity-associated metabolic disorders by reducing skeletal muscle obesity-associated insulin resistance and inflammation.Graphical

The role of captopril in leukotriene deficient type 1 diabetic mice

T1D can be associated with metabolic disorders and several impaired pathways, including insulin signaling, and development of insulin resistance through the renin-angiotensin system (RAS). The main precursor of RAS is angiotensinogen (Agt) and this system is often linked to autophagy dysregulation. Dysregulated autophagy has been described in T1D and linked to impairments in both glucose metabolism, and leukotrienes (LTs) production. Here, we have investigated the role of RAS and LTs in both muscle and liver from T1D mice, and its effects on insulin and autophagy pathways. We have chemically induced T1D in 129sve and 129sve 5LO−/− mice (lacking LTs) with streptozotocin (STZ). To further inhibit ACE activity, mice were treated with captopril (Cap). In muscle of T1D mice, treatment with Cap increased the expression of RAS (angiotensinogen and angiotensin II receptor), insulin signaling, and autophagy markers, regardless of the genotype. In the liver of T1D mice, the treatment with Cap increased the expression of RAS and insulin signaling markers, mostly when LTs were absent. 5LO−/− T1D mice showed increased insulin sensitivity, and decreased NEFA, after the Cap treatment. Cap treatment impacted both insulin signaling and autophagy pathways at the mRNA levels in muscle and liver, indicating the potential role of ACE inhibition on insulin sensitivity and autophagy in T1D.

Altered Transcript Levels of MMP13 and VIT Genes in the Muscle and Connective Tissue of Pigs with Umbilical Hernia.

Umbilical hernia (UH) and inguinal hernia (IH) are among the most common defects in pigs, affecting their welfare and resulting in economic losses. In this study, we aimed to verify the association of previously reported differences in transcript levels of the ACAN, COL6A5, MMP13, and VIT genes with the occurrence of UH and IH. We examined mRNA levels in muscle and connective tissue from 68 animals-34 affected by UH and 34 controls. In a second cohort, we examined inguinal channel samples from 46 pigs (in four groups). We determined DNA methylation levels in muscle tissue for the UH and control animals. The transcript level of MMP13 changed in the UH cases, being upregulated and downregulated in muscle and connective tissue, respectively, and the VIT gene also showed an increased muscular mRNA level. The transcript of the ACAN gene significantly decreased in old pigs with IH. We further observed an increased DNA methylation level for one CpG site within the MMP13 gene in UH individuals. We conclude that these alterations in gene mRNA levels in the UH animals depend on the tissue and can sometimes be a consequence of, not a cause of, the affected phenotype.

Effects of Dietary Chlorogenic Acid Supplementation on Growth Performance, Meat Quality, and Muscle Flavor Substances in Finishing Pigs.

With the prohibition of antibiotics in feed, certain phytocompounds have been widely studied as feed additives. Chlorogenic acid (CGA), a natural polyphenol found in plants, possesses anti-inflammatory, antioxidant, and metabolic regulatory features. The objective of this study was to investigate the effects of dietary chlorogenic acid supplementation on growth performance and carcass traits, as well as meat quality, nutrient value and flavor substances of Duroc × Landrace × Yorkshire (DLY) pigs. Forty healthy DLY pigs (initial body weight (BW): 26.69 ± 0.37) were allotted to four treatment groups and were fed with the control diet, which was supplemented with 25 mg kg-1, 50 mg kg-1, and 100 mg kg-1 CGA, respectively. The trial lasted 100 days. The results suggested that dietary CGA supplementation had no effect (p < 0.05) on the average daily gain (ADG) and feed conversion ratio (FC). Herein, it was found that 50 mg kg-1 CGA-containing diet not only increased the dressing percentage and perirenal fat, but also reduced the rate of muscular pH decline (p < 0.05). In the longissimus thoracis (LT) muscle, the myofiber-type-related genes such as the MyHC IIa and MyHC IIX mRNA levels were increased by 100 mg kg-1 CGA. The results also indicated that the 100 mg kg-1 CGA-containing diet increased the content of crude fat, glycogen, total amino acids, and flavor amino acids, but decreased the inosine and hypoxanthine concentration in LT (p < 0.05). Meanwhile, the lipogenic gene ACC1 mRNA level was elevated by 50 mg kg-1 CGA. Instead, 100 mg kg-1 CGA downregulated the expression level of NT5C2, an enzyme responsible for inosine-5'-monophosphate (IMP) degradation. Additionally, 100 mg kg-1 CGA decreased the malondialdehyde (MDA) content, but increased the glutathione peroxidase (GSH-Px) content as well as antioxidant gene (HO-1, NQO-1, NRF2) mRNA levels in LT muscle. These findings showed that dietary CGA could partly improve carcass traits and muscle flavor without negatively affecting growth performance, and the underlying mechanism may be due to the antioxidant properties induced by CGA.

Irisin ameliorates age-associated sarcopenia and metabolic dysfunction.

Age-associated sarcopenia is characterized of progressed loss of skeletal muscle power, mass, and function, which affects human physical activity and life quality. Besides, accompanied with sarcopenia, aged population also faces a series of metabolic dysfunctions. Irisin, the cleaved form of fibronectin type III domain-containing protein 5 (FNDC5), is a myokine induced by exercise and has been shown to exert multiple beneficial effects on health. The goal of the study is to investigate the alterations of Fndc5/irisin in skeletal muscles during ageing and whether irisin administration could ameliorate age-associated sarcopenia and metabolic dysfunction. The mRNA and protein levels of FNDC5/irisin in skeletal muscle and serum from 2- and 24-month-old mice or human subjects were analysed using qRT-PCR and western blot. FNDC5/irisin knockout mice were generated to investigate the consequences of FNDC5/irisin deletion on skeletal muscle mass, as well as morphological and molecular changes in muscle during ageing via histological and molecular analysis. To identify the therapeutic effects of chronic irisin treatment in mice during ageing, in vivo intraperitoneal administration of 2mg/kg recombinant irisin was performed three times per week in ageing mice (14-month-old) for 4months or in aged mice (22-month-old) for 1month to systematically investigate irisin's effects on age-associated sarcopenia and metabolic performances, including grip strength, body weights, body composition, insulin sensitivity, energy expenditure, serum parameters and phenotypical and molecular changes in fat and liver. We showed that the expression levels of irisin, as well as its precursor Fndc5, were reduced at mRNA and protein expression levels in muscle during ageing. In addition, via phenotypic analysis of FNDC5/irisin knockout mice, we found that FNDC5/irisin deficiency in aged mice exhibited aggravated muscle atrophy including smaller grip strength (-3.23%, P<0.05), muscle weights (quadriceps femoris [QU]: -20.05%; gastrocnemius [GAS]: -17.91%; tibialis anterior [TA]: -19.51%, all P<0.05), fibre size (QU: P<0.01) and worse molecular phenotypes compared with wild-type mice. We then delivered recombinant irisin protein intraperitoneally into ageing or aged mice and found that it could improve sarcopenia with grip strength (+18.42%, P<0.01 or +13.88%, P<0.01), muscle weights (QU: +9.02%, P<0.01 or +16.39%, P<0.05), fibre size (QU: both P<0.05) and molecular phenotypes and alleviated age-associated fat tissues expansion, insulin resistance and hepatic steatosis (all P<0.05), accompanied with altered gene signatures. Together, this study revealed the importance of irisin in the maintenance of muscle physiology and systematic energy homeostasis during ageing and suggested a potent therapeutic strategy against age-associated metabolic diseases via irisin administration.

Endurance exercise under short-duration intermittent hypoxia promotes endurance performance via improving muscle metabolic properties in mice.

This study was designed to (1) investigate the effects of acute exercise under intermittent hypoxia on muscle mRNA and protein levels, and (2) clarify the mechanisms by which exercise under intermittent hypoxia improves endurance capacity. Experiment-1: Male mice were subjected to either acute endurance exercise, exercise under hypoxia (14% O2 ), exercise under intermittent hypoxia (Int, three cycles of room air [10min] and 14% O2 [15 min]). At 3h after exercise under intermittent hypoxia, sirtuin-6 mRNA levels and nuclear prolyl hydroxylases-2 protein levels were significantly upregulated in white gastrocnemius muscle in the Int group. Experiment-2: Mice were assigned to sedentary control (Sed), normoxic exercise-trained (ET), hypoxic exercise-trained (HYP) or exercise-trained under intermittent hypoxia (INT) groups. Exercise capacity was significantly greater in the INT group than in the ET and HYP group. Activity levels of citrate synthase were significantly greater in the INT group than in the HYP group in soleus (SOL) and red gastrocnemius muscles. In SOL, nuclear N-terminal PGC1α levels were considerably increased by the INT training (95% confidence interval [CI]: 1.09-1.79). The INT significantly increased pyruvate dehydrogenase complex activity levels in left ventricle (LV). Monocarboxylate transporter-4 protein levels were significantly increased after the INT training in LV. Capillary-to-fiber ratio values were significantly increased in SOL and were substantially increased in LV (CI: 1.10-1.22) after the INT training. These results suggest that exercise training under intermittent hypoxia represents a beneficial strategy for increasing endurance performance via improving metabolic properties and capillary profiles in several hind-leg muscles and the heart.

Growth differentiation factor-15 as a modulator of bone and muscle metabolism.

This study aims to clarify the potential role of growth differentiation factor-15 (GDF-15) as a myokine in bone metabolism and muscle function in females with osteoporosis. In total, 45 female participants (71.0 ± 8.5 years) with distal radius fractures were recruited. Participants were classified as healthy/osteopenic (n=28) (CON) or osteoporotic (n=17) (OP) according to their T-score from the areal bone mineral density (aBMD) of the femoral neck. Body mass index, upper arm and calf circumferences, and handgrip strength were assessed. Total hip, femoral neck, and lumbar spine aBMD was measured via dual-energy x-ray absorptiometry. The focal bone quality of the distal radius was evaluated via 3D reconstructed computed tomographic images. Serum levels of GDF-15, insulin-like growth factor-1, and inflammatory markers such as tumor necrosis factor-α (TNF-α), interleukin-6, and interleukin-1β (IL-1β), as well as the corresponding mRNA levels in the pronator quadratus muscle were determined. Participants in the OP group had higher serum GDF-15 levels than those in the CON group. The mRNA levels of GDF-15, IL-1β, and TNF-α in the pronator quadratus muscle were significantly higher in the OP group than in the CON one. Levels of both serum GDF-15 and GDF-15 mRNA in muscle were positively correlated with age and negatively associated with the aBMD of the total hip and focal bone quality of the distal radius. Handgrip power was not correlated with circulating GDF-15 levels but was correlated with circumferences of the upper arm and calf, and levels of GDF-15 mRNA in muscle specimens. The mRNA levels of GDF-15 were correlated with those of inflammatory cytokines such as TNF-α and IL-1β. The mRNA levels of TNF-α were associated with circumferences of the upper arm and calf and with the aBMD of the total hip. The mRNA levels of GDF-15 in muscle were correlated with serum levels of GDF-15 and TNF-α. GDF-15 may have associations with bone metabolism in humans via paracrinological and endocrinological mechanisms. Maintenance of muscle mass and function would be influenced more by GDF-15 in muscle than by circulating GDF-15. The role of GDF-15 in bone metabolism and muscle homeostasis could be related to inflammatory responses.

Effects of high-intensity interval training with hyperbaric oxygen.

Hyperbaric Oxygen (HBO2) has been proposed as a pre-conditioning method to enhance exercise performance. Most prior studies testing this effect have been limited by inadequate methodologies. Its potential efficacy and mechanism of action remain unknown. We hypothesized that HBO2 could enhance aerobic capacity by inducing mitochondrial biogenesis via redox signaling in skeletal muscle. HBO2 was administered in combination with high-intensity interval training (HIIT), a potent redox stimulus known to induce mitochondrial biogenesis. Aerobic capacity was tested during acute hypobaric hypoxia seeking to shift the limiting site of whole body V̇O2 from convection to diffusion, more closely isolating any effect of improved oxidative capacity. Healthy volunteers were screened with sea-level (SL) V̇O2peak testing. Seventeen subjects were enrolled (10 men, 7 women, ages 26.5±1.3 years, BMI 24.6±0.6 kg m−2, V̇O2peak SL = 43.4±2.1). Each completed 6 HIIT sessions over 2 weeks randomized to breathing normobaric air, “HIIT+Air” (PiO2 = 0.21 ATM) or HBO2 (PiO2 = 1.4 ATM) during training, “HIIT+HBO2” group. Training workloads were individualized based on V̇O2peak SL test. Vastus Lateralis (VL) muscle biopsies were performed before and after HIIT in both groups. Baseline and post-training V̇O2peak tests were conducted in a hypobaric chamber at PiO2 = 0.12 ATM. HIIT significantly increased V̇O2peak in both groups: HIIT+HBO2 31.4±1.5 to 35.2±1.2 ml kg−1·min−1 and HIIT+Air 29.0±3.1 to 33.2±2.5 ml kg−1·min−1 (p = 0.005) without an additional effect of HBO2 (p = 0.9 for interaction of HIIT x HBO2). Subjects randomized to HIIT+HBO2 displayed higher skeletal muscle mRNA levels of PPARGC1A, a regulator of mitochondrial biogenesis, and HK2 and SLC2A4, regulators of glucose utilization and storage. All other tested markers of mitochondrial biogenesis showed no additional effect of HBO2 to HIIT. When combined with HIIT, short-term modest HBO2 (1.4 ATA) has does not increase whole-body V̇O2peak during acute hypobaric hypoxia. (ClinicalTrials.gov Identifier: NCT02356900; https://clinicaltrials.gov/ct2/show/NCT02356900).

NLRP3 is a promising target for regulating high glucose-induced inflammatory response in Megalobrama amblycephala

The nucleotide-binding domain, leucine-rich repeat and pyrin domain containing protein 3 (NLRP3) has emerged as a key regulator of glucose homeostasis in mammals, while relevant information are still poorly interpreted in aquatic animals. Herein, we cloned and characterized NLRP3 gene from Megalobrama amblycephala, and analyzed its function in high glucose (HG)-induced inflammation. Full-length cDNA of NLRP3 measured 4380 bp with 3570 bp open reading frame encoding 1189 amino acids, compared with Pimephales promelas, it displayed 90.3% homology. Structural analysis revealed that M. amblycephala NLRP3 processed characteristic domains of pyrin, FISNA, NACHT, CARD and LRRs. Spatial expression analysis displayed NLRP3 was ubiquitously expressed in eight organs/tissues (gill, liver, spleen, intestine, head kidney, white muscle, heart and brain) with largest magnitude in head kidney. After a 13-week nutritional experiment, carbohydrate-enriched (45%) diets significantly upregulated NLRP3 mRNA levels in the liver and white muscle than that of the control (30%) diets. Glucose loading caused a significantly increased NLRP3 mRNA levels in the white muscle and liver, with maximum values got at 1 and 2 h, respectively. Subsequently, the mRNA levels rapidly returned to the basal level at 12 h. As for the in-vitro experiments, both ATP and high-glucose treatments remarkably increased the expression of NLRP3 and pro-inflammatory cytokines (IL1β and IL6) in hepatocytes. Additionally, high-leucine (30 mM) levels remarkably increased NLRP3 protein content and transcriptions of NLRP3, NF-κB, IL1β and IL6 than those of the HG and HG + low leucine (10 mM) treatment groups, while the opposite was true for IL8 and IL10. Overall, our findings indicated that M. amblycephala NLRP3 is highly conserved compared with other vertebrates. NLRP3 participated in the control of HG-induced inflammation, and high-leucine levels could aggravate HG-induced inflammation in hepatocytes of M. amblycephala via NLRP3 activation.

Removal of p16 INK4 Expressing Cells in Late Life has Moderate Beneficial Effects on Skeletal Muscle Function in Male Mice.

Aging results in the progressive accumulation of senescent cells in tissues that display loss of proliferative capacity and acquire a senescence-associated secretory phenotype (SASP). The tumor suppressor, p16 INK4A , which slows the progression of the cell cycle, is highly expressed in most senescent cells and the removal of p16-expressing cells has been shown to be beneficial to tissue health. Although much work has been done to assess the effects of cellular senescence on a variety of different organs, little is known about the effects on skeletal muscle and whether reducing cellular senescent load would provide a therapeutic benefit against age-related muscle functional decline. We hypothesized that whole-body ablation of p16-expressing cells in the advanced stages of life in mice would provide a therapeutic benefit to skeletal muscle structure and function. Treatment of transgenic p16-3MR mice with ganciclovir (GCV) from 20 to 26 months of age resulted in reduced p16 mRNA levels in muscle. At 26 months of age, the masses of tibialis anterior, extensor digitorum longus, gastrocnemius and quadriceps muscles were significantly larger in GCV-treated compared with vehicle-treated mice, but this effect was limited to male mice. Maximum isometric force for gastrocnemius muscles was also greater in GCV-treated male mice compared to controls. Further examination of muscles of GCV- and vehicle-treated mice showed fewer CD68-positive macrophages present in the tissue following GCV treatment. Plasma cytokine levels were also measured with only one, granulocyte colony stimulating factor (G-CSF), out of 22 chemokines analyzed was reduced in GCV-treated mice. These findings show that genetic ablation of p16+ senescent cells provides moderate and sex specific therapeutic benefits to muscle mass and function.

Metabolism of Imidazole Dipeptides, Taurine, Branched-Chain Amino Acids, and Polyamines of the Breast Muscle Are Affected by Post-Hatch Development in Chickens.

To explore metabolic characteristics during the post-hatch developmental period, metabolomic analyses of breast muscle and plasma were performed in chickens. The most significant growth-related changes in metabolite levels were observed between seven and 28 days of age. Some of these metabolites are essential nutrients or reported as growth-promoting metabolites. In the muscle, two imidazole dipeptides—carnosine and its methylated metabolite, anserine—increased with the development. These dipeptide levels may be, in part, regulated transcriptionally because in the muscle mRNA levels of carnosine synthase and carnosine methylation enzyme increased. In contrast, taurine levels in the muscle decreased. This would be substrate availability-dependent because some upstream metabolites decreased in the muscle or plasma. In branched-chain amino acid metabolism, valine, leucine, and isoleucine decreased in the muscle, while some of their downstream metabolites decreased in the plasma. The polyamines, putrescine and spermidine, decreased in the muscle. Furthermore, mRNA levels associated with insulin/insulin-like growth factor 1 signaling, which play important roles in muscle growth, increased in the muscle. These results indicate that some metabolic pathways would be important to clarify metabolic characteristics and/or growth of breast muscle during the post-hatch developmental period in chickens.

Characterization, expression pattern and antiviral activities of oligoadenylate synthetase in Chinese Giant Salamander, Andrias davidianus

The enzyme 2′-5′-oligoadenylate synthetase (OAS) is an antiviral protein induced by interferons (IFNs), which plays an important role in IFN-mediated antiviral signaling pathway. In this study, the OAS of Chinese Giant Salamander, Andrias davidianus (AdOAS) was identified for the first time, and the expression profiles in vivo and the antiviral activities in vitro were investigated. The open reading frame (ORF) of AdOAS gene is 1185 bp in length, encoding a putative protein of 394 amino acids, in which a Nucleotidyltransferase (NTase) domain (40–143 aa) and a conserved OAS1 C superfamily domain (165–341 aa) are included. qRT-PCR analysis revealed a broad expression of AdOAS in vivo, with the highest expression level in intestine and heart. After infection with Chinese giant salamander iridovirus (GSIV), the mRNA level of AdOAS in liver increased significantly at 24 h and 48 h post infection and reached the peak at 72 h compared with the control group. The AdOAS mRNA level in kidney increased slightly at 6 h and 12 h post infection, declined to the initial level at 24 h and peaked at 48 h post infection, while in spleen it was slightly up-regulated at 6 h, inhibited at 12 h, 24 h and 48 h, and then significantly increased to the peak at 72 h post infection. In vitro, AdOAS mRNA level in Chinese giant salamander muscle (GSM) cells was not noticeably up-regulated until 24 h and then peaked at 48 h post GSIV infection. In antiviral activity test, the mRNA transcription and protein level of virus major capsid protein (MCP) in AdOAS over-expressed cells was significantly reduced compared with that in control cells by qRT-PCR and western blot analysis. In addition, ddPCR results showed that lower MCP gene copy was found in AdOAS over-expressed cells compared with the control group. These results collectively suggest that AdOAS plays a crucial role against GSIV infection in Chinese giant salamander, and provide a solid base for the further studies on the mechanism of immune defense and the control of the disease in this animal.

Characterization of MRF genes and their tissue distributions and analysis of the effects of starvation and refeeding on the expression of these genes in Acipenser dabryanus muscle.

The purpose of the study was to clone the sequences of myogenic regulatory factors in Acipenser dabryanus and explore the changes in their expression during starvation and refeeding in A. dabryanus muscle. One hundred twenty fish (60.532±0.284g) were randomly assigned to four groups (fasted for 0, 3, 7 or 14 d and then refed for 14 d). Our predictions showed that the coding sequences of myod1, myf5, myog and myf6 in A. dabryanus encoded 275, 248, 248 and 243 amino acids, respectively, and the expression of the four genes was the highest in muscle. During fasting, the expression of myod1 in muscle was significantly decreased in the 14 d group. The expressions of myf5 and myf6 were increased significantly at first and then decreased with prolonged starvation time. The expression of myog in the 14 d group was significantly decreased compared with other groups (P<0.05). During refeeding, the highest values of myod1 and myf6 expression were found in the 3 d group (P<0.05).The expressions of myf5 and myog in 0 d and 3 d group were significantly higher than those in 7 d and 14 d group (P<0.05). These results indicate that myogenic regulatory factors (MRFs) play important roles in muscle growth and development in A. dabryanus. The inhibition of long-term starvation (14 d) on the expression of myogenic regulatory factors is probably one of the reasons why it can not achieve full compensation for growth.

Paternal Resistance Exercise Modulates Skeletal Muscle Remodeling Pathways in Fathers and Male Offspring Submitted to a High-Fat Diet.

Although some studies have shown that a high-fat diet (HFD) adversely affects muscle extracellular matrix remodeling, the mechanisms involved in muscle trophism, inflammation, and adipogenesis have not been fully investigated. Thus, we investigated the effects of 8 weeks of paternal resistance training (RT) on gene and protein expression/activity of critical factors involved in muscle inflammation and remodeling of fathers and offspring (offspring exposed to standard chow or HFD). Animals were randomly distributed to constitute sedentary fathers (SF; n = 7; did not perform RT) or trained fathers (TF n = 7; performed RT), with offspring from mating with sedentary females. After birth, 28 male pups were divided into four groups (n = 7 per group): offspring from sedentary father submitted either to control diet (SFO-C) or high-fat diet (SFO-HF) and offspring from trained father submitted to control diet (TFO-C) or high-fat diet (TFO-HF). Our results show that an HFD downregulated collagen mRNA levels and upregulated inflammatory and atrophy pathways and adipogenic transcription factor mRNA levels in offspring gastrocnemius muscle. In contrast, paternal RT increased MMP-2 activity and decreased IL-6 levels in offspring exposed to a control diet. Paternal RT upregulated P70s6k and Ppara mRNA levels and downregulated Atrogin1 mRNA levels, while decreasing NFκ-B, IL-1β, and IL-8 protein levels in offspring exposed to an HFD. Paternal physical training influences key skeletal muscle remodeling pathways and inflammatory profiles relevant for muscle homeostasis maintenance in offspring submitted to different diets.

Single nucleotide polymorphism scanning and expression analysis of ACSL1 from different duck breeds

Accumulating studies have indicated that the long-chain fatty acyl-CoA1 (ACSL1) gene is related to fat deposition and meat quality in mammals. However, few studies have investigated the relationship between ACSL1 and lipid deposition in ducks. To examine this, we assessed the physicochemical property, homologous alignment, and phylogenetic analyses of the ACSL1 amino acid sequence using bioinformatics tools. The analysis indicated that the ACSL1 amino acid sequence varies in animals, and the duck ACSL1 protein is most closely related to that of chicken. Two single nucleotide polymorphism (SNP) sites were identified at 1749 and 1905 bp of the coding region of ACSL1 by sequencing. Quantitative real-time PCR and western blotting were used to measure mRNA and protein levels in abdominal fat, breast muscle, and liver tissue of Pekin duck (BD) and Cherry Valley duck (CD). mRNA and protein expression were significantly higher in BD than in CD in abdominal fat and liver tissue (P &lt; 0.05). In breast muscle, the mRNA level of ACSL1 was also significantly higher in BD than in CD (P &lt; 0.05), and protein expression in BD tended to be higher than that of CD. These results suggest that ACSL1 may contribute to lipid deposition and meat quality in ducks.

Molecular identification of glucose transporter 4: The responsiveness to starvation, glucose, insulin and glucagon on glucose transporter 4 in common carp (Cyprinus carpio L.).

Glucose transporter 4 (GLUT4) is comprehensively investigated in mammals, while the comparative research of GLUT4 in common carp is deficient. To investigate the function of GLUT4, carp glut4 was first isolated. The open reading frame of carp glut4 was 1518 bp in length, encoding 505 amino acids. A high-sequence homology was identified in carp and teleost, and the phylogenetic tree displayed that the carp GLUT4 was clustered with the teleost. A high level of glut4 mRNA was analysed in fat, red muscle and white muscle. After fasting treatment, glut4 mRNA expression was increased significantly in muscle. In the oral glucose tolerance test experiment, glut4 mRNA was also significantly elevated in muscle, gut and fat. Furthermore, intraperitoneal injection of insulin resulted in the upregulation of glut4 gene expression significantly in white muscle, gut and fat. On the contrary, the glut4 mRNA level in the white muscle, gut and fat was markedly downregulated after glucagon injection. These results suggest that GLUT4 might play important roles in food intake and could be regulated by nutrient condition, insulin and glucagon in common carp. Our study is the first to report on GLUT4 in common carp. These data provide a basis for further study on fish GLUT4.

Evaluation of yeast hydrolysate as a substitute to dietary fish meal of| juvenile Jian carp ( Cyprinus carpio var. Jian): Protein synthesis via TOR pathway

This study was performed to evaluate effects of fish meal replacement by yeast hydrolysate (YH) on crude protein via TOR pathway of Jian carp, Cyprinus carpio var. Jian (initial average weight 19.44 ± 0.06 g). Six hundred fish were assigned into five groups and fed with five isonitrogenous and isocaloric diets replacing fish meal by 0g/kg (G1), 10g/kg (G2), 30g/kg (G3), 50g/kg (G4) and 70g/kg YH (G5). The results showed crude protein of fish in G2 and G3 were significantly higher (p < .05) than in G1. YH significantly increased AST and ALT activities of hepatocytes (p < .05) compared with the control group, but had no effects (p > .05) on AST and ALT contents in conditioned medium of hepatocytes. Furthermore, MyoD, TOR and S6K1 mRNA levels in muscle of G2 and G3 were significantly higher than of G1 (p < .05). Meanwhile, YH significantly increased MyoD, TOR and S6K1 mRNA levels in hepatocytes compared with the control group. In conclusion, 10g/kg and 30g/kg YH increased crude protein content of muscle in fish and increased TOR pathway genes expression levels in muscle and hepatocytes.