| Inosine monophosphate acid (IMP) is one of the key components for meat flavor. And the process of synthesis and metabolism for IMP is very complicated, with ten-step reactions involved. Adenylosuccinate lyase (ADSL; also called "adenylosuccinase") catalyzes two steps in the synthesis of purine nucleotides: (1) the conversion of succinylaminoimidazolecarboxamide ribotide into aminoimidazolecarboxamide ribotide and (2) the conversion of adenylosuccinate into adenosine monophosphate. And the trifunctional protein with glycinamide ribonucleotide synthetase (GARS), aminoimidazole ribonucleotide synthetase (AIRS) and glycinamide ribonucleotide formyltransferase (GART) enzymatic activities, catalyzes the second, third and fifth steps of de novo purine biosynthesis. In the first part of this study, we took these two genes, ADSL and GARS-AIRS-GART, as candidate genes for IMP contents in chicken. To explore the relationships between these two genes with IMP contents in chicken, single strand conformation (SSCP) analysis and sequencing reactions were performed to screen single nucleotide polymorphism (SNP) in four Chinese indigenous chicken breeds, Taihe Silkies (TS), Xiaoshan chickens (XS), Baier chickens (BE), Tibetan chickens (TC), and an exotic breed, Recessive White broilers (RW). And in second part, genetic structure and genetic differentiation of the former four indigenous chicken breeds, TS, XS, BE and TC, were analyzed based on 29 microsatellite markers and 15SNPs loci, which were detected in the first part. The main results were as follows,1. IMP content of breast muscle of 30 individuals (female) at the age of 12 weeks were mensurated for each breed (TS, XS, BE, TC, and RW), which were raised in the same condition of management, and were compared among different breeds. Significant differences of IMP content were found between breeds, which confirms the fact that genetic elements may play a key role on IMP content of chicken. And this may settle a foundation for exploring the mechanism of flavor of Chinese indigenous chicken breeds from the molecular level, and be of significance for our breeding practice of chickens.2. All 13 exons with flanking intronic sequences of ADSL gene, were screened in the five chicken breeds mentioned above, by the method of PCR-SSCP analysis, combined with sequencing reactions. We detected 5 SNPs , C3484T from exon 2, T7426C from intron 5, G7942C from intron 6, C9839A from exon 9, and T12546C from intron 11. These five polymorphic sites were nominated as ADSLl, ADSL2, ADSL3, ADSL4 and ADSL5 respectively. The mutation of CD A at ADSL4 was a non-synonymous mutation, which leads an amino acid substitution, Pro DThr, at site of 273 of amino acid sequence of adenylosuccinate lyase. The result from analysis of variation, failed to prove a relationship between this site and IMP content of breast muscle, though significant differences of genotypes distribution existed among different chicken breeds. The distribution of genotypes for the rest four loci was also different significantly among breeds. Only the ADSLl loci show a significant relationship with IMP content of breast muscle. Across the breeds, IMP content of individuals with TT genotype, was higher than that of individuals with CT and CC genotype, in an extremely significant level (P<0.01). This locus may be a candidate assistant marker for selection for IMP contents.3. All 21 exons with flanking intronic sequences, as well as a 263 bp fragment of the 5' flanking region, of GARS-AIRS-GART gene, were screened in the same five populations, by the method of PCR-SSCP analysis, combined with sequencing reactions. We detected 10 SNPs, C-179T from 5' flanking region, A5669G form exon 3, C6545Afrom exon 4, A7777G from intron 4, G10854T, C10867T, G10898T from intron 6, A16197G from intron 11, C21228T from intron 14, and C29686T from exon 21. These ten polymorphic sites were nominated as GARS1, GARS2, GARS3, GARS4, GARS5, GARS6, GARS7, GARS8, GARS9, and GARS 10, respectively. The mutation of C D A at GARS3 was a non-synonymous mutation, wh...
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