Mapping Of Erhualian Pig’s Growth Curve And Its Association With ACSL1 Gene Variability In Promoter Region

As the two most important fat traits of pigs,the backfat thickness(BFT)and intramuscular fat(IMF)content have a great influence on the meat quality of pigs.It is an effective way to improve meat quality by reducing BFT and increasing IMF content.The ACSL1 gene has an important influence on fat deposition in animals.Therefore,the establishment of the fat trait high and low group,screening for the SNP of the promoter region in ACSL1 gene,and selection of different genotypes for the SNP to reduce the BFT of Erhualian pigs is very important to increase the IMF content.Design the following scheme according to the relevant test specifications.The main test contents are as follows:Trial 1:Growth Curve of Fat Traits of Erhualian Pigs.In this study,we selected 14 pigs in the same litter of Erhualian pig,and then weighted them per-month,and measured the BFT and IMF content by using ultrasound from 3 month old.Based on the weight data of Erhualian pigs,we use three models of Logistic,Gompertz,Bertalanffy body which was used to simulate the body weight growth curves of Erhualian pigs.In addition,the Nlmixed BFT model was used to fitting the BFT of the living body of Erhualian pigs,and at the same time,a better growth model of BFT and IMF content was found.The results showed that:1)The fitting degrees of the four body weight growth models were 0.956,0.965,0.968,and 0.965.Based on the data of the inflection point and body inflection point of growth age,we regard the Bertalanffy model as the best body weight growth curve of Erhualian pigs.2)The R2 of Gaussian and Nlmixed are 0.849 and 0.719.According to value of R2,the Gaussian model is better than Nlmixed models to fit BFT of Erhualian pigs.3)Based on age,the Exponential model was fitted on the IMF content.The formula of Exponential model is y=4.852*exp(-0.0269*x).Trial 2:Saliva collection and DNA extraction methods.In this study,we investigated the method of non-invasive extraction of animal DNA.First,we look for tools and methods of collecting saliva from Erhualian pigs,and then we collected saliva samples.We set the three comparisons in the DNA extraction experiment,those are lysate method and potassium iodide method,adult boar and piglet,saliva and muscle,to comparing the concentration and purity of extracted DNA.Then we PCR those genes samples and sequencing the PCR－production.The results showed that:l)According to the size of the pig’s body,we founded two saliva collection methods,which were self-made sponge collection tools and cotton swabs.To collect the larger adult pigs,we use self-made sponge collection tools,and smaller one,we use cotton swabs.2)The effect of tissue lysate treatment on the DNA obtained is better than that of potassium iodide method.3)The difference of saliva DNA results between adult boars and piglets is not significant.It is suggesting that the adult boar’s saliva is more impurity,but it do none effect to saliva extracts.It is not significantly different between muscle-extraction results and saliva extracts result by sequencing and agarose gel assay.The results of sequencing and agarose gel assay were consistent.It is indicating that the saliva DNA-extraction method is feasible and effective.Trial 3:Association analysis between ACSLI gene and body fat traits in Erhualian pigs.To investigate that whether the ACSL1 gene had an effect on the body fat traits of Erhualian pigs,we collected data of the BFT and IMF content from the Erhualian boars,those are about the age of 6 months.And we collected saliva samples to extract DNA from Erhualian boars.According to the data of fat traits,we collected 184 Erhualian pigs’ saliva in total.We established three high and low groups of Erhualian pigs,those are BFT,IMF content,BFT/IMF content.Then we screened the SNPs of ACSL1 gene from promoter region.In the entire Erhualian pig group,we sequenced the 184 Erhualian pig’s ACSL1 gene and compared the allele frequencies of SNP loci in populations.Combining the genetic pedigree records and other data we used a mixed linear model to correlate the fat traits with the ACSL1 gene.The results showed that:1)There were three mutation sites in the promoter region of ACSL1 gene.In the BFT,the difference of c.-33A>G site between high and low groups were more than 0.2.2)Association-analysis showed that there is a significant difference in the BFT between AA genotype and GG genotype(P<0.05),but there was no significant difference in other fat traits.In summary,the conclusions are as follows:1.Based on the data of the inflection point and body inflection point of growth age,we think that the Bertalanffy model is the optimal body weight growth curve of Erhualian pigs.The Gaussian model is better than the Nlmixed model in fitting the BFT of the Erhualian pigs.We fund that Exponential model do better in fitting the IMF content of Erhualian pigs2.We established two protocols of saliva collection and a method of collecting saliva-extracted animal DNA.3.The c.-33A>G mutation site was found by sequencing the ACSL1 gene’s promoter region.We found that this site was significantly associated with the BFT traits of Erhualian pigs.