| Pigeons have become the fourth largest amount poultry in China,following chickens,ducks and geese.Their meat is delicious and their pectoral muscle account for up to 30% of their body weight.Studying the growth and development rules of pigeons and finding miRNAs related to the development of the pectoral muscle of pigeons are helpful to improve the production level of the meat pigeon breeding industry.In this study,body weight,organ weight,pectoral muscle weight and body length,chest depth,chest cycle,chest width,keel width and pelvic width of 176 white king pigeon were measured at 11 time points.Von Bertallanffy,Gompertz and Logistic models were used to fit the growth and development curves of white king pigeons,and the relationship between body weight and body size index at 11 time points was analyzed by SPSS22.0.Histological characteristics of the 1d,28 d and2y pectoral muscles of the white feather king pigeon were analyzed by paraffin section.We used high-throughput sequencing,qPCR,short-time sequence expression mining(STEM)and other methods to identify and analyze the miRNAs and their expression profiles in the pectoral muscle of white king pigeons at the 1d,28 d and 2y stages,and analyzed the relationship between the cli-miR-20b-5p and the apoptosis of myocytes in white king pigeons by TUNEL assay.The main findings are as follows:(1)The cumulative growth curve of the white king pigeon is "S" shaped,and the best fitting model is Von Bertalanffy(goodness of fit = 0.998),the age of inflection is 8.75 d,and the weight of the inflection is 144.28 g.The growth and development of the white feather king pigeon is mainly completed before the age of 28 days.The body weight of the 28-dayold has reached more than 80% of the adult weight,but the weight of the pectoral muscle is only 53.88% of the adult,28-day-old and 2-year muscle fiber area is higher than 1-day-old.(2)The body weight at 28 days of age was significantly positively correlated with body length and keel length(p<0.01),and the correlation coefficients were 0.897 and 0.658,respectively.The regression coefficients between body length,keel length,body size and body weight were 0.804,0.432 and 0.876,respectively,and all of which were extremely significant.(3)The main organs of white king pigeons,such as heart,liver,lung,kidney and pancreas,have different development patterns.The heart developed vigorously from 1d to7 d,fluctuated slightly from 7d to 22 d,and became stable after 22 d.The development of liver and pancreas reached the highest level at 10 d,and then continued to decline until the end of the experiment.Kidney development was vigorous in 1-4 days,and continued to slow down after 4 days.Lung development peaked at 25 d and then continued to decline.(4)A total of 591 mature miRNAs were identified in the pectoral muscles of white king pigeons at three developmental stages,of which 304 were known miRNAs,86 were novel miRNAs,and 201 were conserved miRNAs.A total of 189 differential miRNAs were identified in the three stages,a total of 1 significantly down-regulated miRNA expression patterns were obtained,differential miRNA target genes are mainly enriched in biological processes such as biosynthesis,developmental regulation,and MAPK signaling pathways.(5)After treatment with cli-miR-20b-5p mimics,the expression level of Apaf gene was increased and the expression level of Bcl-2 gene was decreased.Conclusion: body weight is strongly positively correlated with body slant length at 28-day-old,body weight growth curve The best fitting model is Von Bertalanffy;At different developmental stages,the expression profile of miRNA in the breast muscle of the white feather king pigeon is different,the selected differentially expressed miRNA target genes are enriched in biological processes such as biosynthesis,developmental regulation,and MAPK signaling pathways;cli-miR-20b-5p regulates the apoptosis of pigeon skeletal muscle satellite cells by up-regulating the expression level of Apaf gene and reducing the expression level of Bcl-2 gene.The above results provide a scientific basis for the breeding of meat pigeon specialized strains,improving the management level and production performance of meat pigeons.and accumulating basic data for further study of the regulation mechanism of skeletal muscle development in meat pigeons.It is of great significance to reveal the role of miRNAs in the development of skeletal muscle of pigeons. |
