Characteristics Of Type Ⅰ,Ⅲ Collagens In Intramuscular Connective Tissue From Wuzhumuqin Sheep Of Different Ages

Type Ⅰ and type Ⅲ collagen are the major fibrous collagens in connective tissue of skeletal muscle.Their distribution and characteristics change at different stages of animal growth,affecting the tenderness of the muscle.In this study,Wuzhumuqin sheep at 6,9,12,and 18 months of age under natural grazing conditions were used to extract the semitendinosus and the longissimus dorsi muscle,and total RNA was extracted.The type I collagen gene was detected by real-time fluorescent quantitative PCR.Analysis of Relative Expression of COL1A1,COL1A2 and Type Ⅲ Collagen Gene COL3A1 in muscle.The distribution of typeⅠ and Ⅲ collagen in the connective tissue of skeletal muscle was analyzed by indirect immunofluorescence staining.Type Ⅰ and Ⅲ collagen were extracted from muscle tissue,and qualitative and quantitative analysis was performed by SDS-PAGE method and hydroxyproline method.Established a two-dimensional electrophoresis method for isolating type Ⅰ collagen.The results showed that the relative expression levels of typeⅠ collagen al gene COL1A1,COL1A2 and type Ⅲcollagen were relatively high in 9 and 12 at different ages.The content of type 1 and typeⅢ collagen increased significantly with the increase of age(p<0.05),and the content of type Ⅰ collagen in the connective tissue of semitendinosus muscle was significantly higher than the longissimus dorsi muscle(p<0.05).Type Ⅰ collagen are mainly distributed in the endomysium and perimysium,type Ⅲ collagen is mainly distributed in the endomysium,and a small amount is distributed in the perimysium.The condition for separation of type I collagen by two-dimensional electrophoresis was as follows:the first isoelectric point focusing time was 50000 V·h and the sample loading was 640 μg/mL.