Research On Relationship Between CTSD And VLDLR Gene And Yolk Deposition In Chicken

The yolk not only has a high nutritional value, in the pharmaceutical care has animportant role, therefore, in recent years, high content of egg yolk is favor for more andmore people of all ages, how to improve the content of egg yolk gradually becomes ahot topic and focus.By increasing the deposition weight of the egg yolk during the formation of yolkdeposition can increase the amount of egg yolk. Yolk formation is the endocytosistransport process mediated by very low density lipoprotein receptor on folliclemembrane. VLDLR plays a very important role in the transport and deposition processof vitellogenesis and very low density lipoprotein which are the main components ofegg yolk. The Cathepsin D is a key enzyme in the transport process of the endocytosisprocess in VLDL transport the main component of egg yolk. Therefore, VLDLR andCTSD gene is most likely the main effect genes influencing egg yolk weight and eggweight.In this study, the SNPs of VLDLR gene and CTSD gene in Shandong local chickenbreeds of Wenshang Luhua chicken, Jining Bairi chicken and Laiwu Black chickenwere detected by PCR-SSCP and PCR-RFLP methods, and the polymorphic loci ofdifferent genotypes and four egg yolk traits correlation were analysised. The resultswere as follows:(1) VLDLR gene SNPs detection and the egg yolk traits correlation analysis:In the three test chicken groups2biological significance of SNP sites weredetected, namely the sixth exon8467of NT G→A mutation (V8467) and theseventeenth introns at13876NT A→G mutation (V13876). Least square analysisresults showed that, the V8467was extremely significant effect on yolk weight (P<0.01)and had significant influence on the yolk height (P<0.05); the V13876was significantlyassociated with yolk weight (P<0.01), yolk rate (P<0.05) and yolk height (P<0.05). TheBB genotype of the site V8467and the AA genotype of the site V13876were of largeadvantages in egg yolk deposition, whereas the other genotypes was not conducive toraising egg yolk proportion. The diplotype was significantly associated with yolkweight (P<0.01), yolk rate (P<0.01) and yolk height (P<0.05).(2) CTSD gene SNPs detection and the egg yolk traits correlation analysis:In the three test chicken groupa2SNPs loci were detected, respectively, in the third exon of2614nt C→T mutation (CTSD3) and fourth introns5274nt G→Tmutation (CTSD5274). Least square analysis results showed that, the exon3wassignificantly associated with yolk weight (P<0.01) and yolk height (P<0.05); the intron4was significantly associated with yolk weight (P<0.01), yolk rate (P<0.05) and yolkheight (P<0.05). The AB genotype of the both sites were of greater advantages in yolkdeposition.The diplotype was significantly associated with yolk weight (P<0.01), yolkrate (P<0.01) and yolk height (P<0.01).In short, SNPS from coding site8467and the non-coding site13876of theVLDLR gene and coding site2614and the non-coding site5274of the CTSD genecontributes a significant effect at the deposition of the egg yolk...