The Proteomic Study Of Muscle Development And Intramuscular Fat Deposition Of Chickens At Embryonic And Early Growth Stages

Breast muscle is the most valuable part of the skeletal muscle in chicken. Its development and composition are closely associated with the poultry meat-production performance and meat quality. Intramuscular fat(IMF) content can improve tenderness of meat and plays an important role in the flavor of meat. Its deposition depends not only on adipocyte development inside the muscletissue, but also on muscle tissue development and other factors. The variation of muscle development and IMF content of cell hyperplasia during embryonic period to early growth period is a key determinant of the final meat quality. However, up to now, molecular regulatory mechanisms for muscle development and IMF deposition from incubation to early growth stage remain still poorly characterized.In the current study, slow-growing Beijing-you chicken and fast-growing Cobb chicken were used as experimental animals. The body weight and breast muscle weight were determined at embryonic day 12(E12), embryonic day 17(E17), day 1(D1) and day 14(D14) after hatching. Histological section analysis was carried out correspondingly to measure the changing patterns of breast muscle growth and IMF accumulation at early developmental stage.The proteomes of breast muscle of two breeds at four time points were analysed by isobaric tags for relative and absolute quantitation(iTRAQ) and verified by Western blot. The main results were as follows:1. The changing patterns of breast muscle growth and IMF accumulation at early developmental stage. The body weight, breast muscle weight and the diameter and size of breast muscle fibers were increased significantly(P<0.01). The density of breast muscle fibers were decreased significantly(P<0.01) during D1 to D14. E12 to E17 and D1 to D14 were main muscle growth periods, where the weight increased 1.8 and 14.5 folds respectively in Beijing-you chicken and 5.5 and 35.9 folds respectively in Cobb chicken. The diameters of breast muscle fiber were increased dramatically 3 folds in Beijing-you chicken and 5.7 folds in Cobb chicken during D1 to D14. The major accumulation time for IMF was E17 to D1 and the amount of IMF was decreased dramatically from D1 to D14, which indicated the maximum amount of IMF accumulation at D1.2. The proteomic study on breast muscle of chickens at embryonic and early growth stages. A total of 263 significantly different proteins were detected in Beijing-you chicken among 2585 proteins and 248 significantly different proteins were detected in Cobb chicken among 2353 proteins by iTRAQ.The total number of the differential proteins was approximate between two breeds, while about 40% proteins were different. GO and KEGG analysis showed: different proteins at stage of E12 to E17 mainly enriched in terms and pathways related to cell differentiation; E17 to D1 mainly enriched in terms and pathways related to energy metabolism and nucleotide metabolism; D1 to D14 mainly enriched in terms and pathways related to energy metabolism.3. The study on molecular mechanism of muscle development and intramuscular fat deposition of chickens at embryonic and early growth stages. ECM-receptor interaction, focal adhesion, dilated cardiomyopathy and hypertrophic cardiomyopathy may play an important role in muscle development during embryonic period, where ACTN2, COL3A1, COL6A1, LAMA4, DES, TPM1, DMD and MYL10 were established to be the key proteins. Pentose phosphate pathway, biosynthesis of amino acids, cysteine and methionine metabolism and glycolysis/gluconeogenesis may play an important role in muscle development during early growth period, where AHCY, FBP, GAPDH, GPI, LDHA, PFKM, PGAM1, PGK1, PGM1 and TPI1 were established to be the key proteins. Fatty acid degradation, fatty acid metabolism, fatty acid elongation and PPAR signaling pathway may play an important role in IMF deposition at early developmental stage, where ACADL, APOA1, HADHA and HADHB were established to be the key proteins. The number of pathways of energy metabolism in Cobb chicken was more than that in Beijing-you chicken.Pyruvate metabolism may play an important role for muscle development at early developmental stage in Cobb chicken.