The proliferation and differentiation of skeletal muscle satellite cells (SMSCs) play an important role in the development of skeletal muscle. Our previous sequencing data showed that miR-21-5p is one of the most abundant miRNAs in chicken skeletal muscle. Therefore, in this study, the spatiotemporal expression of miR-21-5p and its effects on skeletal muscle development of chickens were explored using in vitro cultured SMSCs as a model. The results in this study showed that miR-21-5p was highly expressed in the skeletal muscle of chickens. The overexpression of miR-21-5p promoted the proliferation of SMSCs as evidenced by increased cell viability, increased cell number in the proliferative phase, and increased mRNA and protein expression of proliferation markers including PCNA, CDK2, and CCND1. Moreover, it was revealed that miR-21-5p promotes the formation of myotubes by modulating the expression of myogenic markers including MyoG, MyoD, and MyHC, whereas knockdown of miR-21-5p showed the opposite result. Gene prediction and dual fluorescence analysis confirmed that KLF3 was one of the direct target genes of miR-21-5p. We confirmed that, contrary to the function of miR-21-5p, KLF3 plays a negative role in the proliferation and differentiation of SMSCs. Si-KLF3 promotes cell number and proliferation activity, as well as the cell differentiation processes. Our results demonstrated that miR-21-5p promotes the proliferation and differentiation of SMSCs by targeting KLF3. Collectively, the results obtained in this study laid a foundation for exploring the mechanism through which miR-21-5p regulates SMSCs.

The yield and quality of the skeletal muscle are important economic traits in livestock and poultry production. The musculoskeletal embryonic nuclear protein 1 (MUSTN1) gene has been shown to be associated with embryonic development, postnatal growth, bone and skeletal muscle regeneration; however, its function in the skeletal muscle development of chicken remains unclear. Therefore, in this study, we observed that the expression level of MUSTN1 increased in conjunction with the proliferation of chicken skeletal muscle satellite cells (SMSCs). Knockdown of MUSTN1 in SMSCs downregulated the expression of cell proliferation genes as Pax7, CDK-2 and differentiation-relate genes including MyoD, MyoG, MyHC and MyH1B, whereas it upregulates the expression of cell apoptosis gene (Caspase-3) (P < 0.05). However, the combined analysis of CCK-8 and EdU showed that the cell vitality and EdU-positive cells of the si-MUSTN1 transfected group were significantly lower than those of the negative siRNA group (P < 0.05). In addition, the knockdown of MUSTN1 significantly increased the cell population in the G0/G1 phase and significantly decreased the cell population in the G2/M phase (P < 0.05), whereas the overexpression of MUSTN1 showed opposite effect. Taken together, our findings indicates that MUSTN1 is an important molecular factor that is responsible for regulating muscle growth and development in chickens, particularly, proliferation and differentiation of SMSCs.

Preserved duck egg yolk (PEY) can be divided into a solidified outer layer (S-PEY) and a liquid inner core (L-PEY) during the middle-later stages of alkaline pickling. The differences among PEY, S-PEY, and L-PEY were systematically investigated using property characterization, nutrient determination, and lipidomics analysis. The results demonstrated that L-PEY exhibited a more vivid red-yellow color, with higher total protein, total lipid, and phosphorus contents compared to S-PEY. Conversely, the pH, moisture, and sodium contents were higher in S-PEY than in L-PEY. Quantitative lipidomics analysis revealed that L-PEY possessed a significantly higher total lipid abundance than PEY, with 19 lipid subclasses (551 lipid molecules) being notably more abundant in L-PEY. Phospholipids exhibited the most significant differential abundance, with the abundance of phosphatidylethanolamines (PE) and phosphatidylcholines (PC) in L-PEY being 19.6 and 13.6 times greater than those in S-PEY, respectively. These findings indicated that the alkaline pickling procedure resulted in substantial nutrient migration duck egg yolk, particularly in the case of phospholipids. The results provide novel insights into the processing mechanism of preserved duck egg yolk.

Reducing abdominal fat (AF) accumulation and increasing the level of intramuscular fat (IMF) simultaneously is a major breeding goal in the poultry industry. To explore the different molecular mechanisms underlying AF and IMF, gene expression profiles in the breast muscle (BM) and AF from three chicken breeds were analyzed. A total of 4737 shared DEGs were identified between BM and AF, of which 2602 DEGs were upregulated and 2135 DEGs were downregulated in the BM groups compared with the AF groups. DEGs involved in glycerophospholipid metabolism and glycerolipid metabolism were potential regulators, resulting in the difference in lipid metabolite accumulation between IMF and AF. The PPAR signaling pathway was the most important pathway involved in tissue-specific lipid deposition. Correlation analysis showed that most representative DEGs enriched in the PPAR signaling pathway, such as FABP5, PPARG, ACOX1, and GK2, were negatively correlated with PUFA-enriched glycerophospholipid molecules. Most DEGs related to glycerophospholipid metabolism, such as GPD2, GPD1, PEMT, CRLS1, and GBGT1, were positively correlated with glycerophospholipid molecules, especially DHA- and arachidonic acid (ARA)-containing glycerophospholipid molecules. This study elucidated the molecular mechanism underlying tissue-specific lipid deposition and poultry meat quality.

Ferritin heavy chain 1 (FTH1) is pivotal in the storage, release, and utilization of iron, plays a crucial role in the ferroptosis pathway, and exerts significant impacts on various diseases. Iron influences skeletal muscle development and health by promoting cell growth, ensuring energy metabolism and ATP synthesis, maintaining oxygen supply, and facilitating protein synthesis. However, the precise molecular mechanisms underlying iron’s regulation of skeletal muscle growth and development remain elusive. In this study, we demonstrated that the conditional knockout (cKO) of FTH1 in skeletal muscle results in muscle atrophy and impaired exercise endurance. In vitro studies using FTH1 cKO myoblasts revealed notable decreases in GSH concentrations, elevated levels of lipid peroxidation, and the substantial accumulation of Fe²⁺, collectively implying the induction of ferroptosis. Mechanistically, E3 ubiquitin-protein ligase SMURF1 (SMURF1) acts as an E3 ubiquitin ligase for FTH1, thereby facilitating the ubiquitination and subsequent degradation of FTH1. Consequently, this activation of the ferroptosis pathway by SMURF1 impedes myoblast differentiation into myotubes. This study identifies FTH1 as a novel regulator of muscle cell differentiation and skeletal muscle development, implicating its potential significance in maintaining skeletal muscle health through the regulation of iron homeostasis.

Indoor environmental control is usually applied in poultry farming to ensure optimum growth conditions for birds. However, these control methods represent a considerable share of total energy consumption, and the trend of applying new equipment in the future for precision livestock farming would further increase energy demand, resulting in an increase in greenhouse gas emissions and management costs. Therefore, to ensure optimum efficiency of both energy use and livestock productivity, a customized hourly model was developed in the present study to interpret and analyze the electronically collected data. The modules for estimating indoor gas concentrations were incorporated into the present model, as this has not been properly considered in previous studies. A validation test was performed in a manure-belt layer house using sensors and meters to measure the indoor environmental parameters and energy consumption. The predicted results, including indoor temperature, relative humidity, carbon dioxide and ammonia concentrations, showed good agreement with the measured data, indicating a similar overall trend with acceptable discrepancies. Moreover, the corresponding differences between the measured and simulated energy consumption for heating, tunnel ventilation and base ventilation were 13.7, 7.5, and 0.1%, respectively. The total energy demand estimated by the model showed a limited discrepancy of approximately 10.6% compared with that measured in reality. Although human factors, including inspection, cleaning, vaccination, etc., were not included in the model, the validation results still suggested that the customized model was able to accurately predict the indoor environment and overall energy consumption during poultry farming. The validated model provides a tool for poultry producers to optimize production planning and management strategies, increase the production rate of unit energy consumption and achieve precision livestock farming from an energy consumption standpoint.