温胃阳汤对功能性消化不良大鼠肥大细胞活化及SCF/c-Kit信号通路的影响

目的:基于肥大细胞活化及干细胞因子(stem cell factor,SCF)/受体酪氨酸激酶c-Kit信号通路探讨温胃阳汤治疗大鼠功能性消化不良的作用机制。方法:将60只SD大鼠随机分为空白组,模型组,雷尼替丁组及温胃阳汤低、中、高剂量组,每组10只。空白组大鼠不予造模,其他各组采用夹尾刺激加不规则喂养复合番泻叶法建立大鼠功能性消化不良模型,模型建立后,空白组及模型组灌胃给予生理盐水,温胃阳汤低、中、高剂量组和雷尼替丁组则分别用温胃阳汤(0.743 g/mL、1.485 g/mL和2.970 g/mL)及盐酸雷尼替丁胶囊(3 g/L)灌胃。治疗结束后,以碳墨推进法测定小肠推进率;采用甲苯胺蓝染色观察大鼠十二指肠组织肥大细胞并计数;ELISA测定大鼠十二指肠中肥大细胞类胰蛋白酶(mast cell tryptase,MCT)和组胺(histamine,HA)的含量;RT-qPCR检测十二指肠中SCF和c-Kit mRNA的表达;Western blot和免疫组化检测十二指肠中SCF和c-Kit蛋白的表达水平。结果:与模型组相比,温胃阳汤治疗显著提高大鼠的小肠推进率(P<0.05);ELISA结果显示,温胃阳汤治疗可减少大鼠十二指肠黏膜组织肥大细胞数量及MCT和HA含量(P<0.05);Western blot和免疫组化结果表明,温胃阳汤治疗可上调大鼠十二指肠组织c-Kit和SCF蛋白的表达水平(P<0.05),增加SCF和c-Kit阳性细胞数(P<0.05);RT-qPCR结果显示,WWYD治疗可上调大鼠十二指肠组织c-Kit和SCF mRNA的表达(P<0.01)。而且,小肠推进率分别与MCT和HA含量呈负相关,与SCF和c-Kit的表达呈正相关。结论:温胃阳汤能促进大鼠十二指肠动力,其作用机制可能与抑制大鼠十二指肠MCT和HA的生成,及激活SCF/c-Kit信号通路有关。

基于SCF/c-kit信号通路探讨理气通便方对气滞型慢传输型便秘大鼠肠道动力的影响

目的 基于SCF/c-kit信号通路探讨理气通便方对气滞型慢传输型便秘(STC)大鼠肠道动力的影响。方法 将36只Wistar雌性大鼠按随机数字表法分为对照组6只和造模组30只。造模组采用“洛哌丁胺混悬液+夹尾刺激”复制气滞型STC大鼠模型,连续刺激14 d。当大鼠表现出激惹、易怒、烦躁等情况,正常喂养饲料时出现大便干硬、排便数量减少等表现时,说明气滞型便秘模型造模成功。将造模成功的大鼠按照随机数字表法分为模型组、西药组、低剂量组、中剂量组和高剂量组各6只,低、中、高剂量组分别按5.15、10.3、20.6 g/(kg·d)给予理气通便方药液灌胃;西药组按0.18 mg/(kg·d)给予琥珀酸普芦卡必利片混悬液灌胃;对照组和模型组按10 mL/(kg·d)给予无菌水灌胃,每日1次,连续灌胃14 d。比较6组末次给药后6 h的粪便排出量、粪便含水量和小肠推进率;HE染色观察结肠组织病理变化;免疫组化检测结肠组织c-kit蛋白表达水平;Western blot检测结肠组织c-kit、SCF蛋白表达量。结果 HE染色显示:对照组大鼠结肠黏膜完整,杯状细胞和腺体排列整齐,未见炎症细胞聚集;模型组结肠黏膜出现肠腺排列欠整齐,黏膜下层间质血管扩张;各给药组结肠黏膜肠腺排列整齐,未观察到明显上皮损伤。与对照组比较,模型组粪便排出量、粪便含水量和小肠推进率均明显降低(P<0.05),结肠组织c-kit蛋白表达水平和c-kit、SCF蛋白表达量均明显降低(P<0.05)。与模型组比较,西药组、中剂量组、高剂量组粪便排出量、粪便含水率和小肠推进率均明显提高(P<0.05),低剂量组粪便排出量和粪便含水率均明显提高(P<0.05);给药组结肠组织c-kit蛋白表达水平均明显提高(P<0.05);低、中、高剂量组结肠组织c-kit蛋白表达量均明显提高(P<0.05),高剂量组SCF蛋白表达量明显提高(P<0.05)。结论 理气通便方可提高气滞型STC模型大鼠结肠组织中ICC的表达及调控SCF/c-kit信号通路,恢复对胃肠道节律的正常调控来改善便秘的症状。

SCF泛素连接酶的体外泛素化体系构建与检测

为研究蛋白质的体外泛素化过程,利用大肠杆菌表达系统异源表达和纯化APPBP1/UBA3(E1)、UBC12(E2)、Cullin1-Rbx1(E3)和Nedd8(neural precursor cell expressed developmentally down-regulated protein 8)蛋白,制备FITC-Cysteine绿色荧光素标记的泛素Ub(Ubiquitin),构建了SCF泛素连接酶的体外泛素化体系,同时实现快速检测SCF泛素连接酶中Cullin1蛋白的自泛素化修饰。结果表明,建立的体外SCF E3自泛素化活性反应体系具有较高的可操作性和便利性。

基于SCF/C-kit通路探讨三焦针法对腹泻型肠易激综合征大鼠的影响

目的 观察三焦针法对腹泻型肠易激综合征(irritable bowel syndrome with diarrhea, IBS-D)大鼠胃肠动力异常及结肠组织干细胞因子(stem cell factor, SCF)、酪氨酸激酶受体(tyrosine kinase receptor, C-kit) mRNA和蛋白表达的影响,探讨三焦针法治疗IBS-D的作用机制。方法 wistar雄性大鼠随机分为空白组、模型组、西药组和三焦组,每组6只。除空白组外,其余各组采用“冰醋酸灌肠+束缚应激”建立IBS-D大鼠模型。西药组予匹维溴胺灌胃(15 mg/kg),三焦组针刺膻中、中脘、气海、血海(双侧)及足三里(双侧),诸穴行捻转补法30秒,1次/d,均治疗14天。观察大鼠一般状态;测定体质量、旷场实验(大鼠横向运动和纵向运动)、稀便率、腹壁撤退反射(abdominal retraction reflex, AWR)3分阈值时注水量;RT-PCR法、Western blot法检测结肠组织SCF、C-kit mRNA及蛋白表达。结果 与空白组相比,IBS-D模型大鼠一般状态较差,体质量显著降低(P<0.01),旷场实验检测横向运动距离与纵向运动次数显著降低(P<0.01),稀便率显著增高(P<0.01),AWR3分时注水量显著降低(P<0.01),结肠组织中SCF、C-kit mRNA及蛋白表达水平均显著升高(P<0.01)。与模型组比较,西药组、三焦组大鼠体质量显著升高(P<0.01,P<0.05),横向运动距离与纵向运动次数均显著升高(P<0.05,P<0.01),稀便率显著下调(P<0.01),AWR3分时注水量显著提升(P<0.01),三焦组大鼠结肠组织中SCF、C-kit mRNA及蛋白水平表达均显著降低(P<0.01),而西药组SCF、C-kit mRNA及蛋白表达无统计学意义(P>0.05)。结论 三焦针法可改善IBS-D大鼠症状,可能是与调节结肠组织中SCF、C-kit mRNA及蛋白表达水平有关。

High-Power Raman Soliton Generation at 1.7 μm in All-Fiber Polarization-Maintaining Erbium-Doped Amplifier

An all-fiber polarization maintaining high-power laser system operating at 1.7 μm based on the Ramaninduced soliton self-frequency shifting effect is demonstrated. The entirely fiberized system is built by erbiumdoped oscillator and two-stage amplifiers with polarization maintaining commercial silica fibers and devices, which can provide robust and stable soliton generation. High-power soliton laser with the average power of 0.28 W,the repetition rate of 42.7 MHz, and pulse duration of 515 fs is generated directly from the main amplifier.Our experiment provides a feasible method for high-power all-fiber polarization maintaining femtosecond laser generation working at 1.7 μm.

Optical Nonlinearity of Violet Phosphorus and Applications in Fiber Lasers

A D-shaped fiber is coated with a new two-dimensional nanomaterial,violet phosphorus(VP),to create a saturable absorber(SA)with a modulation depth of 3.68%.Subsequently,the SA is inserted into a fiber laser,enabling successful generation of dark solitons and bright–dark soliton pairs through adjustment of the polarization state within the cavity.Through further study,mode-locked pulses are achieved,proving the existence of polarization-locked vector solitons.The results indicate that VP can be used as a polarization-independent SA.

Time Transfer in a 1839-km Telecommunication Fiber Link Demonstrating a Picosecond-Scale Stability

An implementation of high-precision time transfer over a 1839-km field fiber loop back link between two provincial capitals of China,Xi’an and Taiyuan,is reported.Time transfer stabilities of 6.5 ps at averaging time of 1 s and 4.6 ps at 40000 s were achieved.The uncertainty for the time transfer system was evaluated,showing a budget of 56.2 ps.These results stand for a significant milestone in achieving high-precision time transfer over a field fiber link spanning thousands of kilometers,signifying a record-breaking achievement for the real-field time transfer in both stability and distance,which paves the way for constructing the nationwide high-precision time service via fiber network.

On the generation of high-quality Nyquist pulses in mode-locked fiber lasers

Nyquist pulses have wide applications in many areas,from electronics to optics.Mode-locked lasers are ideal platforms to generate such pulses.However,how to generate high-quality Nyquist pulses in mode-locked lasers remains elusive.We address this problem by managing different physical effects in mode-locked fiber lasers through extensive numerical simulations.We find that net dispersion,linear loss,gain and filter shaping can affect the quality of Nyquist pulses significantly.We also demonstrate that Nyquist pulses experience similariton shaping due to the nonlinear attractor effect in the gain medium.Our work may contribute to the design of Nyquist pulse sources and enrich the understanding of pulse shaping dynamics in mode-locked lasers.

Giving Food a Fiber Boost: Adding High Beta-Glucan Ingredient from Barley to Everyday Foods

Lack of dietary fiber contributes to many health issues, particularly chronic vascular diseases. Mixed linkage β-1.3 - 1.4 beta-glucan (beta-glucan, in this paper) is a confirmed beneficial ingredient for the human diet through reduction of cholesterol and the glycemic index. Barley contains the highest beta-glucan content of all the grains, and in this study, a percentage of flour from two high beta glucan lines was, each, added to an array of wheat-based food products to measure how it impacted total dietary fiber. Results showed that beta-glucan content was higher in all the products containing the added high beta-glucan flour, along with increased total dietary fiber content. Protein content in the food products is also increased with the higher protein in the barley flours added. Beta-glucan content in the barley-added products increased to 1.2% - 4.0% versus 0.2% - 0.5% in the pure wheat products, while the dietary fibers increased to 3.5% - 24.4% versus 2.1% - 9.1% in pure wheat product controls. This research provided experimental evidence that using a high beta-glucan barley ingredient in food can increase dietary fiber to benefit health.

Increasing dietary fiber intake for type 2 diabetes mellitus management: A systematic review

BACKGROUND Type 2 diabetes is a chronic,non-communicable disease with a substantial global impact,affecting a significant number of individuals.Its etiology is closely tied to imbalanced dietary practices and sedentary lifestyles.Conversely,increasing die-tary fiber(DF)intake has consistently demonstrated health benefits in numerous studies,including improvements in glycemic control and weight management.AIM To investigate the efficacy of DF interventions in the management of type 2 diabetes mellitus(T2DM).METHODS A systematic literature review was conducted to explore the association between DF intake and the management of T2DM.Following the inclusion and exclusion criteria,a total of 26 studies were included in this review.RESULTS The main strategies implied to increased DF intake were:High DF diet plus acarbose(2 studies);DF supplements(14 studies);and high DF diets(10 studies).Overall,most studies indicated that increased DF intake resulted in im-provements in glycemic control and weight management in T2DM patients.CONCLUSION DF represents a valuable strategy in the treatment of type 2 diabetes,improving health outcomes.DF intake offers the potential to improve quality of life and reduce complications and mortality associated with diabetes.Likewise,through supplements or enriched foods,DF contributes significantly to the control of several markers such as HbA1c,blood glucose,triglycerides,low-density lipoprotein,and body weight.

Estimation of cancer cell migration in biomimetic random/oriented collagen fiber microenvironments

Increasing data indicate that cancer cell migration is regulated by extracellular matrixes and their surrounding biochemical microenvironment,playing a crucial role in pathological processes such as tumor invasion and metastasis.However,conventional two-dimensional cell culture and animal models have limitations in studying the influence of tumor microenvironment on cancer cell migration.Fortunately,the further development of microfluidic technology has provided solutions for the study of such questions.We utilize microfluidic chip to build a random collagen fiber microenvironment(RFM)model and an oriented collagen fiber microenvironment(OFM)model that resemble early stage and late stage breast cancer microenvironments,respectively.By combining cell culture,biochemical concentration gradient construction,and microscopic imaging techniques,we investigate the impact of different collagen fiber biochemical microenvironments on the migration of breast cancer MDA-MB-231-RFP cells.The results show that MDA-MB-231-RFP cells migrate further in the OFM model compared to the RFM model,with significant differences observed.Furthermore,we establish concentration gradients of the anticancer drug paclitaxel in both the RFM and OFM models and find that paclitaxel significantly inhibits the migration of MDA-MB-231-RFP cells in the RFM model,with stronger inhibition on the high concentration side compared to the low concentration side.However,the inhibitory effect of paclitaxel on the migration of MDA-MB-231-RFP cells in the OFM model is weak.These findings suggest that the oriented collagen fiber microenvironment resembling the late-stage tumor microenvironment is more favorable for cancer cell migration and that the effectiveness of anticancer drugs is diminished.The RFM and OFM models constructed in this study not only provide a platform for studying the mechanism of cancer development,but also serve as a tool for the initial measurement of drug screening.

Development of a scintillating-fiber-based beam monitor for the coherent muon-to-electron transition experiment

The coherent muon-to-electron transition(COMET)experiment is a leading experiment for the coherent conversion of μ^(-)N→e^(-)N using a high-intensity pulsed muon beamline,produced using innovative slow-extraction techniques.Therefore,it is critical to measure the muon beam characteristics.We set up a muon beam monitor(MBM),where scintillating fibers woven in a cross shape were coupled to silicon photomultipliers to measure the spatial profile and timing structure of the extracted muon beam for the COMET.The MBM detector was tested successfully with a proton beamline at the China Spallation Neutron Source and took data with good performance in the commissioning run.The development of the MBM,including its mechanical structure,electronic readout,and beam measurement results,are discussed.

Coherent optical frequency transfer via 972-km fiber link

We demonstrate coherent optical frequency dissemination over a distance of 972 km by cascading two spans where the phase noise is passively compensated for.Instead of employing a phase discriminator and a phase locking loop in the conventional active phase control scheme,the passive phase noise cancellation is realized by feeding double-trip beat-note frequency to the driver of the acoustic optical modulator at the local site.This passive scheme exhibits fine robustness and reliability,making it suitable for long-distance and noisy fiber links.An optical regeneration station is used in the link for signal amplification and cascaded transmission.The phase noise cancellation and transfer instability of the 972-km link is investigated,and transfer instability of 1.1×10^(-19)at 10^(4)s is achieved.This work provides a promising method for realizing optical frequency distribution over thousands of kilometers by using fiber links.

Anti-abrasion collagen fiber-based membrane functionalized by UiO-66-NH_(2)with ultra-high efficiency and stability for oil-in-water emulsions separation

Membrane separation strategies offer promising platform for the emulsion separation.However,the low mechanical strength of membrane separation layers and the trade-off between separation flux and efficiency present significant challenges.In this study,we report a CFM@UiO-66-NH_(2)membrane with high separation flux,efficiency and stability,through utilizing a robust anti-abrasion collagen fiber membrane(CFM)as the multifunctional support and UiO-66-NH_(2)by an in-situ growth as the separation layer.The high mechanical strength of the CFM compensated for the weakness of the separation layer,while the charge-breaking effect of UiO-66-NH_(2),along with the size sieving of its constituent separating layers and the capillary effect of the collagen fibers,contributed to the potential for efficient separation.Additionally,the CFM@UiO-66-NH_(2)membrane exhibited superhydrophilic properties,making it suitable for separating oil-in-water microemulsions and nanoemulsions stabilized by anionic surfactants.The membrane demonstrated remarkable separation efficiencies of up to 99.960%and a separation flux of370.05 L·m^(-2)·h^(-1).Moreover,it exhibits stability,durability,and abrasion resistance,maintaining excellent separation performance even when exposed to strong acids and alkalis without any damage to its structure and performance.After six cycles of reuse,it achieved a separation flux of 417.97 L·m^(-2)·h^(-1)and a separation efficiency of 99.747%.Furthermore,after undergoing 500 cycles of strong abrasion,the separation flux remained at 124.39 L·m^(-2)·h^(-1),with a separation efficiency of 99.992%.These properties make it suitable for the long-term use in harsh operating environments.We attribute these properties to the electrostatic effect resulting from the amino group on UiO-66-NH_(2)and its in-situ growth on the CFM,which forms a size-screening separation layer.Our work highlights the potential of the CFM@UiO-66-NH_(2)membrane as an environmentally friendly size-screening material for the efficient emulsion wastewater separation.

Relationship of Retinal Nerve Fiber Layer Thickness and Retinal Vessel Calibers with Cognitive Impairment in the Asymptomatic Polyvascular Abnormalities Population

Objective Cognitive impairment(CI)in older individuals has a high morbidity rate worldwide,with poor diagnostic methods and susceptible population identification.This study aimed to investigate the relationship between different retinal metrics and CI in a particular population,emphasizing polyvascular status.Methods We collected information from the Asymptomatic Polyvascular Abnormalities Community Study on retinal vessel calibers,retinal nerve fiber layer(RNFL)thickness,and cognitive function of 3,785participants,aged 40 years or older.Logistic regression was used to analyze the relationship between retinal metrics and cognitive function.Subgroups stratified by different vascular statuses were also analyzed.Results RNFL thickness was significantly thinner in the CI group(odds ratio:0.973,95%confidence interval:0.953–0.994).In the subgroup analysis,the difference still existed in the non-intracranial arterial stenosis,non-extracranial carotid arterial stenosis,and peripheral arterial disease subgroups(P<0.05).Conclusion A thin RNFL is associated with CI,especially in people with non-large vessel stenosis.The underlying small vessel change in RNFL and CI should be investigated in the future.

The NAC transcription factor LuNAC61 negatively regulates fiber development in flax (Linum usitatissimum L.)

Flax is a crucial fiber crop that exhibits excellent textile properties and serves as a model plant for investigating phloem fiber development. The regulation of multiple genes significantly influences fiber development, notably involving NAC(NAM, ATAF1/2, CUC2) transcription factors in forming the fiber secondary cell wall(SCW).Overexpression of LuNAC61 in flax resulted in sparse top meristematic zone leaves and significantly reduced stem cellulose content. Scanning electron microscopy and staining observations revealed a significant reduction in fiber bundles. β-Glucuronidase(GUS) staining analysis demonstrated high activity of the LuNAC61 promoter in the bast fibers of the flax stem. Additionally, several members of the LuPLATZ and LuCesA families exhibited significant coexpression with LuNAC61. Subcellular localization indicated the presence of LuPLATZ24 protein in the nucleus and cytoplasm, LuNAC61 protein exclusively in the nucleus, and LuCesA10 in the nucleus and endoplasmic reticulum. LuPLATZ24 positively regulates LuNAC61, whereas LuNAC61 negatively affects LuCesA10, suggesting the involvement of a metabolic network in regulating flax fiber development. In conclusion, this study provides a critical opportunity for a comprehensive and in-depth analysis of the mechanisms governing flax fiber development and the potential use of biotechnology to enhance flax fiber yield.

Optimization of the Pretreatment of the Mixture of Cassava Peelings and Pineapple Fibers Using Response Surface Methodology and a Process Simulator for the Bioethanol Production

The increase in oil prices and greenhouse gas emissions has led to the search for substitutes for fossil fuels. In Cameroon, the abundance of lignocellulosic resources is inherent to agricultural activity. Production of bioethanol remains a challenge given the crystallinity of cellulose and the presence of the complex. The pretreatment aimed to solubilize the lignin fraction and to make cellulose more accessible to the hydrolytic enzymes, was done using the organosolv process. A mathematical modeling was performed to point out the effect of the temperature on the kinetics of the release of the reducing sugars during the pretreatment. Two mathematical model was used, SAEMAN’s model and Response surface methodology. The first show that the kinetic parameters of the hydrolysis of the cellulose and reducing sugar are: 0.05089 min-1, 5358.1461 J·mol-1, 1383.03691 min-1, 51577.6100 J·mol-1 respectively. The second model was used. Temperature is the factor having the most positive influence whereas, ethanol concentration is not an essential factor. To release the maximum, an organosolv pre-treatment of this sub-strate should be carried out at 209.08°C for 47.60 min with an ethanol-water ratio of 24.02%. Organosolv pre-treatment is an effective process for delignification of the lignocellulosic structure.

Demineralized Bone Matrix Fibers plus Allograft Bone for Multilevel Posterolateral Spine Fusion: A Game Changer?

Introduction: While autograft bone is the gold standard for multilevel posterolateral lumbar fusion, bone substitutes and graft extenders such as allograft bone, ceramics and demineralized bone matrix (DBM) have been used to avoid the morbidity and insufficient quantity associated with harvesting autologous bone. The primary objective of this retrospective study was to determine whether, in patients with increased risk of operative nonunion related to multilevel fusion, adding DBM fibers to mineralized bone allograft resulted in better fusion than using allograft alone. The secondary objectives were to evaluate how adding DBM fibers affects functional disability, low back pain, intraoperative blood loss and the nonunion rate. Methods: This retrospective study involved a chart review of consecutive patients who underwent multilevel lumbar spinal fusion and were operated on by a single surgeon. The patients were divided into two groups: 14 patients received mineralized bone allograft (control group) and 14 patients received a combination of mineralized bone allograft and DBM (experimental group). Patients were reviewed at a mean of 16.4 ± 2.2 months after surgery at which point CT scans were analyzed to determine whether fusion had occurred;Oswestry disability index (ODI) and pain were also evaluated. Results: A mean of 5 levels [min 2, max 13] were fused in these patients. Posterolateral fusion as defined by the Lenke classification was not significantly different between groups. The experimental DBM group had a significantly better composite fusion score than the control group (P Discussion: Adding DBM fibers to allograft bone during multilevel posterolateral spinal fusion was safe and produced better composite fusion than using allograft only as an autograft extender.

Coaxial Wet Spinning of Boron Nitride Nanosheet‑Based Composite Fibers with Enhanced Thermal Conductivity and Mechanical Strength

Hexagonal boron nitride nanosheets(BNNSs)exhibit remarkable thermal and dielectric properties.However,their self-assembly and alignment in macroscopic forms remain challenging due to the chemical inertness of boron nitride,thereby limiting their performance in applications such as thermal management.In this study,we present a coaxial wet spinning approach for the fabrication of BNNSs/polymer composite fibers with high nanosheet orientation.The composite fibers were prepared using a superacid-based solvent system and showed a layered structure comprising an aramid core and an aramid/BNNSs sheath.Notably,the coaxial fibers exhibited significantly higher BNNSs alignment compared to uniaxial aramid/BNNSs fibers,primarily due to the additional compressive forces exerted at the core-sheath interface during the hot drawing process.With a BNNSs loading of 60 wt%,the resulting coaxial fibers showed exceptional properties,including an ultrahigh Herman orientation parameter of 0.81,thermal conductivity of 17.2 W m^(-1)K^(-1),and tensile strength of 192.5 MPa.These results surpassed those of uniaxial fibers and previously reported BNNSs composite fibers,making them highly suitable for applications such as wearable thermal management textiles.Our findings present a promising strategy for fabricating high-performance composite fibers based on BNNSs.

Vitamin A regulates mitochondrial biogenesis and function through p38 MAPK‑PGC‑1α signaling pathway and alters the muscle fiber composition of sheep

Background Vitamin A(VA)and its metabolite,retinoic acid(RA),are of great interest for their wide range of physiological functions.However,the regulatory contribution of VA to mitochondrial and muscle fiber composition in sheep has not been reported.Method Lambs were injected with 0(control)or 7,500 IU VA palmitate into the biceps femoris muscle on d 2 after birth.At the age of 3 and 32 weeks,longissimus dorsi(LD)muscle samples were obtained to explore the effect of VA on myofiber type composition.In vitro,we investigated the effects of RA on myofiber type composition and intrinsic mechanisms.Results The proportion of type I myofiber was greatly increased in VA-treated sheep in LD muscle at harvest.VA greatly promoted mitochondrial biogenesis and function in LD muscle of sheep.Further exploration revealed that VA elevated PGC-1αmRNA and protein contents,and enhanced the level of p38 MAPK phosphorylation in LD muscle of sheep.In addition,the number of type I myofibers with RA treatment was significantly increased,and type IIx myofibers was significantly decreased in primary myoblasts.Consistent with in vivo experiment,RA significantly improved mitochondrial biogenesis and function in primary myoblasts of sheep.We then used si-PGC-1αto inhibit PGC-1αexpression and found that si-PGC-1αsignificantly abrogated RA-induced the formation of type I myofibers,mitochondrial biogenesis,MitoTracker staining intensity,UQCRC1 and ATP5A1 expression,SDH activity,and enhanced the level of type IIx muscle fibers.These data suggested that RA improved mitochondrial biogenesis and function by promoting PGC-1αexpression,and increased type I myofibers.In order to prove that the effect of RA on the level of PGC-1αis caused by p38 MAPK signaling,we inhibited the p38 MAPK signaling using a p38 MAPK inhibitor,which significantly reduced RA-induced PGC-1αand MyHC I levels.Conclusion VA promoted PGC-1αexpression through the p38 MAPK signaling pathway,improved mitochondrial biogenesis,and altered the composition of muscle fiber type.