Correlative Analysis Between Vldlr Gene Polymorphism And Growth And Carcass Traits In Poultry And The Effect Of MDV On The MRNA Expression Of VLDLR

The very low density lipoprotein receptor(VLDLR)is a member of the low density lipoprotein receptor family.This receptor has an important role in cholesterol uptake,metabolism of apoprotein-E-containing triacylglycerol-rich lipoproteins the main function is to regulate the metabolism of triglycerides by binding to ApoE rich lipoproteins.In animals,VLDLR is mainly distributed in skeletal muscle,fat,heart and other tissues but liver.On the basis of previous experiments,4 SNPs loci were screened by sequencing the VLDLR gene of Gaoyou duck to study on the relationship between genetic polymorphism and growth traits and carcass traits of Gaoyou ducks.The expression of VLDLR mRNA in different tissues of ducks and chickens was studied by RT-PCR.Finally,the expression of VLDLR mRNA in different tissues of MD was detected by RT-PCR for the study of the expression of VLDLR mRNA in different tumor tissues of poultry.1 Polymorphism of VLDLR signal peptide coding region and its association with growth and carcass traits in Gaoyou ducks.The purpose of this study was to investigate the relationship between VLDLR genetic polymorphism and body weight plus abdominal fat traits of Gaoyou ducks.A primer pairs for the 5'-UTR and signal peptide coding of the duck VLDLR gene was designed based on the duck genomic sequence database.Polymorphisms were detected by polymerase chain reaction(PCR)and DNA sequencing.Four novel SNPs(g.151G>A,g.170C>T,g.206A>G and g.278-295+>-)were detected in the 374 bp.Based on the four SNPs above,8 haplotypes were identified.The H8 was the most common haplotype in Gaoyou population occurring at a frequency of more than 31%.Haplotype combinations constructed on these SNPs were associated with body weight at 6-10 weeks of age(P<0.05,P<0.01)and abdominal fat percentage(AFP)(P<0.05,P<0.01).In particular,diplotype H1H1 had positive effect on body weight from 6th to 10th weeks of age,whereas it had negative effect on abdominal fat percentage(AFP).Positive effects of the diplotype H5H8 were observed for both AFP and body weight.This suggested that the VLDLR gene was playing an important role in the regulation of body weight and fat-related traits and could be a potential marker in a marker assisted selection program during duck breeding.2 Study on VLDLR mRNA Expression of Different Tissues in poultryFor the study of VLDLR expression in tumorigenesis,this study was to investigate the expression level and distribution of VLDLR gene in different tissues of ducks and chickens at first.Lung,fat,spleen,liver and other tissues were collected quickly and stored in liquid nitrogen for RNA extraction.The expression of VLDLR gene in five tissues of ducks and chickens was analyzed by designing primers based on VLDLR gene sequence in GenBank and performing RT-PCR amplification.The relative expression level of VLDLR gene in five tissues was detected.The results showed that the expression of VLDLR gene was different among different tissues of ducks and chickens.The expression of VLDLR gene was the highest in muscle,followed by lung and adipose tissue and lowest in liver.The relative expression were skeletal muscle(57.47±0.10)>lung(11.72±0.28)>Adipose tissue(4.13±0.05)>spleen(1.76 ± 0.14)>liver(1.00±0.15)in ducks and skeletal muscle(10.95±0.14)>lung(3.87±0.23)>Adipose tissue(3.02±0.11)>spleen(2.31±0.08)>liver(1.00±0.17)in chickens.Two identical,the expression of VLDLR mRNA in spleen,lung,skeletal muscle and fat was significantly higher than that in liver(P<0.01).The expression of VLDLR mRNA in lung was higher than that in fat,the difference between the two groups was very significant(P<0.01).This study showed firstly that VLDLR gene in the lungs have a higher expression,the spleen also has a certain expression.3 The effect of MDV on the mRNA expression of VLDLRThe animals of this study was chicken suspected infected MDV,poisoned MDV RB1B and suspected PM.Liver,spleen,lung,skeletal muscle and adipose tissue were collected quickly and stored in liquid nitrogen for RNA extraction.The expression of VLDLR gene in five tissues of three kinds of chickens was analyzed by designing primers based on VLDLR gene sequence in GenBank and performing RT-PCR amplification.The results showed that the expression of VLDLR gene was different among different tissues of three kinds of chickens.The relative expression were skeletal muscle(7.88±0.095)>liver(1.00±0.041)>lung(0.649±0.027)>adipose tissue(0.168±0.053)>spleen(0.05±0,021)in chicken infected MDV,the expression of VLDLR mRNA in spleen,lung,and adipose tissue was significantly lower than that in liver(P<0.01).At the same time,the expression of VLDLR in lung was higher than that in adipose tissue,and the difference was very significant(P<0.01).The relative expression of different tissues was skeletal muscle(30.18 ± 0.074)>adipose tissue(5.13±0.061)>lung(2.991±0.178)>liver(1.00±0.390)>spleen(0.41 ±0.117)in chickens poisoned MDV RB1B,the expression of VLDLR mRNA in the spleen was lower than that in the liver,and the difference was not significant,the expression of VLDLR in lung,skeletal muscle and adipose tissue was significantly higher than that in liver(P<0.01),the expression of VLDLR mRNA in adipose tissue was higher than that in lung,the difference between the two groups was very significant(P<0.01).The relative expression of different tissues was skeletal muscle(84.83±0.183)>lung(13.17±0.307)>adipose tissue(2.72±0.050)>spleen(1.17±0.214)>liver(1.00±0.343)in PM.The expression of the spleen was slightly higher than that of liver and no significant difference between the two groups,the expression of VLDLR mRNA in lung,skeletal muscle and adipose tissue was significantly higher than that of liver(P<0.01),the VLDLR mRNA expression in lung was higher than adipose tissue,and the difference was very significant(P<0.01).The resules showed that the expression of VLDLR mRNA in liver of chicken suspccted infected MDV(Tumor liver)rised and higher than adipose tissue,spleen and other tissues,the expression of VLDLR mRNA was still low in liver no tumor or infected by other diseases.