Mechanism Of Muscle Developmental Regulation In Jingning Chicken

Jingning chicken is a special local breed for combination of meat and eggs in Gansu province. Now they are already in endanger. Jingning chicken and broiler chicken, with the same origin, have the same genetic background, but there are also differences that related to their specific properties such as muscle growth and development. This study was carried out on protein expression of different periods of Jingning chicken embryos, being investigted such as the cat’s eye syndrome candidate gene2(CECR2), insulin-like growth factor1(IGF-1), extracellular fatty acid binding protein (Ex-FABP), lipoprotein lipase (LPL), calpastatin(CAST) and calpainl(CAPN1) by using immunohistochemistry method. The expression level of above protein were detected by Western blotting, compared with the expression in embryos of Baiyu broilers, Huangyu broilers and hy-line brown layers. The results are as follows:1Behavioral and histological observationCharacteristics of different periods in stereo microscope were according to Mr. Hamburger’s, therefor the chicken embryo could be get on schedule. Different strains of chicken embryo had motion difference in five minutes from HH19to HH31period. Huangyu broilers and Baiyu broilers had all higher movements than Jingning chicken and hy-line brown layers. The weight of embryos increased with the incubation days. Adult Jingning chicken had better meat properties than the other breeds. The results indicated that species selection may lead to cells proliferation and differentiation at early stages. The different growth rate among breeds were already show in embryonic stages.2Expression of factors related to muscle growth in Jingning chicken embryos2.1Immunohistochemistry results showed that CECR2protein was expressed in limb bud and somite of different chicken embryos. At HH19period, CECR2protein was expressed near the beak to the somite and fringes of limb bud. From HH21to27period,CECR2protein expression was extend to the rear somite and fringes of limb bud. From HH29to31period, CECR2expression was also seen in the somite and limb bud. Western blotting results showed that Huangyu broilers and Baiyu broilers had higher CECR2expression throughout the entire period, Jingning chicken hardly express CECR2protein from HH19to HH24, but there was a sudden increase in HH27, and to E13days beyond Huangyu broilers and Baiyu broilers. Hy-line brown layers didn’t show much. The results suggested that CECR2protein was involved in early muscle cells growth of Jingning chicken. In each developmental period, different chicken breeds had differ expression, this may be related to different muscle cell development.2.2Immunohistochemistry results showed IGF-1protein were expressed in different strains of chicken embryos. At HH19period, IGF-1protein was expressed at the non-AER section, AER, and cartilage formation area. At HH31period, IGF-1protein was expressed at the cartilage prototype area, perichondrium and cell necrosis area. Western blotting results showed that IGF-1expression level in Jingning chicken continued to increase and have the highest expression level during HH27to HH31. From HH31to E18, IGF-1expression level in Jingning chicken is lower than in Huangyu broilers and Baiyu broilers. The results showed that IGF-1protein expression have strain differences in muscle, programmed cell activation and muscle specific gene expression in chicken embryos were affected by IGF-1.Therefor, IGF-1may participate in muscle cell proliferation and myotube fusion during Jingning chicken embryo stages.3Expression of factors involved in fatty acid metabolism in Jingning chicken embryos3.1Immunohistochemistry results showed that in the early development of embryos, the Ex-FABP was distributed in the entire limb bud. At early stage, mesenchymal cells showed Ex-FABPprotein expression. Ex-FABP protein were observed also in the large blood vessels. At HH31, the protein became prominent in myofibers and also found in mesenchymal cells. Western blotting results showed in the whole process, that the Ex-FABP protein expression levels of Jingning chicken were higher than broilers and laying hens at the same period. Results showed that during the early embryonic development, the Ex-FABP protein expression in Jingning chicken may promote muscle development as well as muscle fat deposition, even as a source of fat decomposition to supply energy for Jingning chicken during cold environment.3.2Immunohistochemistry results showed that LPL protein were expressed in developing limb bud and segment. Western blotting results were that Jingning chicken had higher LPL protein expression during the period, especially at HH27, HH31and E18. Jingning chicken had the highest LPL protein expression. The results showed that higher LPL expression in Jingning chicken may be according to the quicker organ formation and differentiation stage, it may do more to relate with energy demand and intramuscular fat deposition. Time differences during expression may be due to earlier LPL gene expression in Jingning chickens than in other chickens.Therefor, supply more energy for Jingning chickens during early embryonic development.4Expression of factors involved in protein degradation in Jingning chicken embryos 4.1Immunohistochemistry results showed that from HH19to HH31, CAST were widely distributed in the limb bud and segment. Western blotting results showd that, from HH19to HH24, CAST protein expression of Jingning chicken were higher than the other three strains and then declined. From E13to E18, the expression of Jingning chicken rose again, and had significant difference with the other three breeds (p<0.05). The results showed that calpastatin was ubiquitous in chicken cells, this may be due to the liver to be an advantage organ for CAST expression.And then, the protein expression in early Jingning chicken limb muscle development is not the main regulatory factors.4.2Immunohistochemistry results showed that CAPN1protein were expressed in chicken embryo limb bud during development periods, but relatively weak. Western blotting results showed that CAPN1protein expression of JingNing chicken has been relatively stable. From HH19to E13, CAPN1JingNing chicken expression level was slightly lower than Huangyu broilers and Baiyu broilers, but higher than layers. Upto E18, CAPN1expression level in Jingning chicken embryo was slightly lower than Baiyu broilers and higher than Huangyu broilers. The results showed that CAPN1was involved in the early embryo development. Changes of CAPN1protein expression in Jingning chicken development level may be meet to demand for protein metabolism in muscle cell growth and meat tenderness.In conclusion, cat’s eye syndrome candidate gene2, insulin-like growth factor1, extracellular fatty acid binding protein, lipoprotein lipase, calpastatin and calpain1were involved in muscle development during different stages of Jingning chicken embryos. Jingning chicken had difference with Baiyu broilers, Huangyu broilers and hy-line brown layers in the muscle characteristic, this may be due to different regulation ability by above protein on muscle development.