Genetic Variation And Expression Of ADSL And GARS-AIRS-GART Genes And Their Associations With Meat Quality In Chicken

Inosine monophosphate acid (IMP) is one of the key components for meat flavor. In this study. PCR-SSCP and DNA sequencing were used for studying genetic variation of ADSL and GARS-AIRS-GART genes and their relationship with meat quality in four populations, Wenchang chicken, Rugao chicken, Anka chiken and the Recessive White Rock chicken, respectively. Paraffin sections were made for investigating the development character of muscle fibres and its association with meat quality and fat cells were analyzed. Real time fluorescent quantitative PCR was conducted to detect spatial and temporal expression patterns of ADSL and GARS-AIRS-GART genes in10tissues (heart, liver, chest muscle, small intestine, large intestine, cerebellum, brain, kidney, leg muscle and proventriculus) of Rugao chicken and Recessive White Rock chicken, aiming to provide reasonable scientific base for chicken breeding or genetic improvement. The main results were showed as following.1. Paraffin section resultsThe diameter of Recessive White Rock chickens muscle fibers was higher than that of the Rugao chicken, and reached significant differences (P<0.05) in every weeks; some of them even reached extraordinary significant level (P<0.01), which were consistent with faster growth and high feed utilization of Recessive White Rock chicken. The subcutaneous fat cell size of Recessive White Rock chickens was higher than that of Rugao chicken in6weeks and8weeks old, and lower than in Rugao chicken in10weeks and12weeks of age. The subcutaneous fat cell size in two breeds showed the same "up-down" trends, but Recessive White Rock Chickens showed downward trend at8weeks of age, while Rugao chicken appeared decline in the10weeks of age.2. Associations of SNPs of ADSL gene with IMP in chickenThere were g.3713G> A, g.3793C> T and g.10191C>T nonsense mutations found in ADSL exons2and9, respectively. Correlation analysis suggested that the IMP content of BB genetype individuals was significantly lower than AA and AB genotype individuals (P<0.01), but the IMP content of AB genetype slightly higher than and BB genotype.3. Associations of SNPs of GARS-AIRS-GART gene with IMP in chickenFour SNPs were discovered in exon21of GARS-AIRS-GART gene, g.29968C> T was nonsense mutation, g.29943G> A、g.30011T> C、g.30017C> T were missense mutations, resulting in amino acid sequence altered from Asp to Asn in site29943,30011of Trp into Arg, and30017of Arg into Cys. Association results showed that the IMP content of AE genotype was significantly lower than that of other genotype individuals (P<0.01), while the IMP content of among the other genotypes had no significant difference (P>0.05)4. ADSL and GARS-AIRS-GART gene candidate haplotypes in chickenWe detected in128candidate haplotypes in ADSL and GARS-AIRS-GART genes. The frequency of number1,21and37candidate haplotypes were more than10%. respectively,0.5021,0.1316and0.3159; the frequencies of number2,3,5,6,13,31,33.38,39,53,65,85, and101candidate haplotype were between1%～10%; and the others were less than1%. The difference of haplotype frequencies could be caused by linkage disequilibrium. In the four chicken breeds of this study, Anka chicken had up to80kinds of the candidate haplotypes detected which was the most; Recessive White Rock chickens had the least, that is8; Rugao chicken and Wenchang Chicken were in center, that are32and62respectively; and the candidate haplotype and frequency varied.5. Spatial and temporal expression pattern analysis of ADSL gene in Rugao chicken and Recessive White Rock ChickenBy real-time fluorescent quantitative PCR, the results revealed that ADSL gene in Rugao chicken presented high-level expression in chest muscle and leg muscle tissues, moderate-level expression in liver, kidney and heart, and low-level expression in cerebellum, brain, proventriculus, small intestine and large intestine. Temporal expression pattern of ADSL gene in brain of Rugao chicken was consistent with Recessive White broilers, performing up trend from0-day-old to4weeks and then gradually decline. In heart, the expression pattern of2weeks in Rugao chiken was highest, then gradually decline till10～12weeks. Recessive White Rock chicken was relatively high in0day old, then gradually reduced, and reached the highest at8weeks. The expression in liver of Rugao chicken increased after birth, reached the maximum in 2weeks, then gradually declined till12weeks; In Recessive White Rock chicken the ADSL gene expressed high at birth, then gradually reduced. In chest muscle, ADSL gene of Rugao chicken reached the highest expression in2weeks and the expression of Rugao cock was significantly higher than that of the hen; and Recessive White Rock chicken reached the highest expression in6weeks. In leg muscle, the expressions of the two breed cocks increased at first and then decreased, while the hens decreased firstly and then slowly rise.6. Tissue expression pattern analysis of GART gene in Rugao chicken and the Recessive White broilersBy real-time fluorescent quantitative PCR, the results revealed that GART gene in Rugao chicken presented high-level expression in liver and leg muscle, moderate expression in cerebellum, glandular stomach, chest, heart, kidney, and low expression in lager intestine, small intestine and brain. Developmental expression pattern of GART gene in leg muscle of Rugao cock were consistent with the Recessive White broilers, performing up trend from0-day-old up to2weeks, and then gradually decline. But the expression of Rugao cock was higher than the Recessive White cock. Developmental expression pattern of Rugao hen were consistent with the Recessive White hen. The expression of Rugao chickens was increased in12weeks of age, but the expression of Recessive White broilers were a downward trend; chest muscle tissue test results that GART gene expression levels of Rugao chickens and the Recessive White broilers was opposited in every weeks; the expression of Rugao chicken higher than the Recessive White Rock chickens in0～4weeks old and were lower than Recessive White Rock chickens in4～8weeks; then the expression was higher than the Recessive White Rock Chickens; heart tissue test results that the expression of hen rapid decline in0～2weeks, and the expression of cock rise in the0～2weeks of age;4～12weeks old in the mother remained at a relatively stable level; liver test results that Rugao cock higher than that of hen in the0～2weeks of age, was lower than that of hens in4～12expression; and the Recessive White cock of0～12weeks old were higher than that of the hen.