| In this research, we carried out different feed-style tests to a new line which breeds Erlang mountainous chickens, by recording and testing the production and the traits of meat quality, we explored the effect of different feed-styles. Meanwhile, we cloned the entire coding sequence of two members for SREBFs, which were SREBF1 and SREBF2 and the correlations of the bioinformatics analysis were done. For different feed-styles, we also tested and analyzed the expression pattern of SREBF1 and SREBF2 in different growth points and in different tissues using SYBR Green I qRT-PCR. We also detected the SNPs of SREBF2 genes using PCR-SSCP and sequence screening methods in six stains of Daheng high-quality chicken in Sichuan province and Erlang mountainous chickens, and related analysis was conducted, the results are as follows:Determination of properties found that at 8,10 and 13 weeks, the part of the fat traits,blood biochemical parameters and chest fatty acids, respectively, in caged feed chickens,indoor floor chickens and outdoor access chickens were significantly or extremely significantly (P<0.05 or P<0.01) different, suggested that these traits or indicators may be due to the different feed-styles.We successfully obtained the full coding sequence of SREBF1 and SREBF2. Based on these two cDNA sequences, their amino acid sequences were increased (1115aa and 952aa). By bioinformatics, we found SREBP-1 and SREBP-2 were not transmembrane protein but contain membrane region, and conservative structural functional domain of bHLH transcription factor family. It implied that they all belonged to the bHLH family.We used the real-time PCR (SYBR green I) method to test the expression level of SREBF1 and SREBF2 gene in different tissue including liver, abdomen fat, sebumcutaneum fat, breast muscle, leg muscle, and uropygial gland in at certain growth point of chicken with different feed-styles. The results indicated that SREBF1 and SREBF2 genes had expressed in all tissues at all growth points and there were growth points and tissues with higher expression level. We also found the expression in different feeding conditions was different. Liver, breast and uropygial gland are advantageous expressed tissues for SREBFl and SREBF2. In different feeding-styles, the expression level of SREBF1 in liver had significant differences (P<0.05), and free-range chicken had lower expression level. For SREBF2, there were significantly different expressions in abdomen fat and breast muscles (P<0.01), and the expression level in abdomen fat with outdoor access was lower, while in breast muscle the outdoor access had higher expression level.In this study, we screened part sequences of extrons and intron of SREBF2 gene by sequencing and PCR-SSCP method. Ten SNPs were identified, including rl: 51382660, r1:51382391, r1:51381392, r1:51376638, r1:51376226, r1:51375686, r1:51374255, r1:51373368, r1:51372941 and r1:51370350, respectively. And the superiority alleles were A, C, A, A, C, C, G, G, G and C, respectively. Because SNP6, SNP8 and SNP9 had the extremely significant superiority alleles and genotypes, and the PIC＜O.1, so we deleted their haplotypes. Then 30 haplotypes were constructed to form by the other seven SNPs, and there were 117 composite haplotypes. H4 (A-C-G-A-T-A-G) H10 (A-C-A-A-C-G-C), H13 (A-C-A-A-T-G-C), and H16 (A-C-A-G-C-G-C) were advantageous haplotypes. By mark-associated analysis, we found SNP1 had extremely significant genetic effect on eviscerated weight (Type III SS, F=5.605, P=0.004), SNP2 had significant genetic effect on eviscerated weight (Type III SS, F=3.418, P=0.034). SNP4 had significant genetic effect on live-weight (Type III SS, F=3.881, P=0.022), and had extremely significant effect on carcass weight, semi-eviscerated weight, breast muscle weight and leg muscle weight (Type III SS, F=5.805, P=0.03; Type III SS, F=6.303, P=0.0002; Type III SS, F=6.841, P=0.001; Type III SS, F=4.987, P=0.007; Type III SS, F=6.576, P=0.002). SNP3, SNP5, SNP7 and SNP10 all had no significant genetic effect on carcass traits (P>0.05). Based on haplotype analysis, we found that haplotype had extremely significant genetic effect on breast muscle weight (Type III SS, F=1.966, P=0.006), but had no significant genetic effect on other carcass traits (P>0.05). H21H21 was superior haplotype of live-weight, carcass weight, semi-eviscerated weight, eviscerated weight, and leg muscle weight, H13H21 was for breast muscle weight, while H4H21 was inferior haplotype for skinfold thickness. So it can be concluded that H21 (A-T-G-A-C-G-C) may have positive effect on promoting the production performance for boiler chicken. |
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