| Thyroid hormone responsive spot 14 (THRSP or Spot 14) is a small acidic protein that is predominately expressed in lipogenic tissues (i.e., liver, abdominal fat and the mammary gland) in mammals. This gene has been identified to play a role in lipogenesis and regulating the transcription of enzymes related with de novo lipogenesis in liver, i.e., ATP-citrate lyase (ACLY), fatty acid synthase (FAS) and malic enzyme (ME). THRSP gene family including THRSPαand a paralog of THRSPβby the duplication, located in the position of chr1:184523552-184524974 and chr1:184524508-184524957 respectively for chicken. In this study, genomic variation of THRSPαwas screened by the means of DNA pool and Sequencing protocol, and the correlation between the polymorphism of mutation and the economic traits of growth, carcass and fat were statistically analyzed. The results are presented as follow:1. Nineteen SNPS (single nucleotide polymorphism) were detected from the 2130 bp of THRSPαgenome with 800 bp 5'flanking region. One new transcription factor of AP-1(activator protein 1)binding site resulted from G-637A SNP mutation. Results showed that the polymorphisms of G/A significantly were related with the carcass and fat traits, GG genotype with higher carcass weight, eviscerated yield with giblet, eviscerated yield, fat cingula width and crude fat content in leg musle than AG genotype (P < 0.05), AG and GG genotypes with higher crude fat content in leg musle than AA genotypes (P < 0.05).2. A reported 9bp insertion/deletion mutation in 267bp of THRSPα, 5'-CATAGATGG- 3', was also detected during the sequencing for SNP scanning. The correlation between polymorphisms of chicken THRSPαgene were examined by the electrophoresis of 4% agarose gel and 8% PAGE gel in total 1525 chickens of F2 from full-sib (439) and half-sib (886) resource population of White Recessive Rocks×Chinese Native Xinghua and random population of broilers (200). It was showed that the results were in same trends in 3 different populations. The relationships between the polymorphisms of Chicken THRSPαand traits of growth,carcass and meat quality were analyzed by using the SAS software. No significant difference between THRSPαand traits of growth and garcass, however, THRSP BB (deletion) and AB (insertion /deletion) present a higher abdominal fat weight and fat cingula width than AA (insertion) (P<0.05). Checking the relative expression in liver and abdominal fat tissue by SYBR real-time PCR, the expression of THRSPαmRNA in BB, AB was higher than that in AA.3. The genotypic distribution of 9bp insertion/deletion mutation of THRSPαvaried among the 16 imported and domestic breeds. The frequencies of AB, BB higher than that of AA,which was even zero in Hailan, Tibet and White Leghorn population. Only Chahua, Hanlan, Beijing Youji, Tibet Chicken and Xinghua are under Hardy-Weinberg Equilibrium.4. The polymorphisms of a reported 6-12bp insertion/deletion mutation of THRSPβwere examined by the electrophoresis of 4% agarose gel and 8% PAGE gel, and the relationships between the polymorphisms of chicken THRSPβand traits of growth, carcass and meat quality were first analyzed by using the SAS software in F2 full-sib resource population of White Recessive Rocks×Chinese Native Xinghua. The results showed that THRSPβvariation was associated with the growth and carcass traits, in which the BB(deletion) had the higher body weight of birth, weekly weight of lasting 12 weeks and carcass weight than AA (insertion), and also had higher weight of eviscerated yield with giblet and eviscerated yield than AA.5. The expression of the chicken THRSPαgenes was examined by SYBR Quantitative real-time PCR in different age of Yangshan chicken. Among 15 tissues of 63 d old chicken, abdominal fat and subcutaneous fat had the highest expression level of THRSPαmRNA, 4 and 3 folds to which in liver respectively, with heart, liver, spleen, kidney and oviduct expressing lower amounts, and with lung, breast muscle, leg muscle, brain, stomach and uterus expressing much lower amounts. Among 17 tissues of 137 d old chicken, abdominal fat had the highest expression level of THRSPαmRNA, 4 folds to which in liver, lung, subcutaneous fat, ovary ,oviduct and pituitary,and 3 folds to which in heart and hypothalamus, with spleen, breast muscle, leg muscle, brain, stomach and small intestine expressing much lower amounts. The expression of the chicken THRSPαgene was different as reported before just in liver and fat.6. Adding T3 (Thyroid hormone) in adipocyte culture media did not affect much the growth of cells and the expression of THRSPα.All the results suggested that the significant association of the THRSPαgene with fat traits, and also suggested that the mutation of insertion/deletion of THRSPαcould be used as a molecular marker linkage with fat traits in high quality broiler assistant selection breeding program.
|
PDF Full Text Request