Cloning Of Quail FMO3Gene And Association Of Gene Polymorphisms With Trimethylamine Concentration In Egg Yolk

Egg yolk trimethylamine is an important factor influencing the egg quality and egg consuming. Egg yolk trimethylamine concentration levels up while particular hens were fed with choline-precursor-enriched diets. It showed that excessive trimethylamine deposition in egg yolk resulted by disfunction of FMO3enzyme is due to an adenine to thymine mutation in FMO3gene. Quail was one of the important special commercial birds among abundant domestic bird in China. Quail egg had become a common consuming production in Chinese daily life. However reports about genetics of quail egg quality were rare, meanwhile no reports about whether the quail FMO3gene correlated to egg trimethylamine still conducted.This thesis systematically studied the genetic pattern of egg yolk in egg quail in China using Shendan automatic sexing commercial line as study material. Total194quails of dam line and sire line were tested to identify FMO3gene polymorphisms. The FMO3gene polymorphisms association analysis with egg yolk trimethylamine was carried out to find out the relationship between FMO3gene and quail egg yolk trimethylamine concentration. A1888bp quail FMO3gene cDNA sequence which obtained by using5’RACE and3’RACE contains an1596bp long open reading frame, a37bp long5’UTR region and a255bp long3’UTR region. The quail FMO3gene cDNA sequence encodes the quail FM03contained532amino acid residuals. The FMO3protein primary structure analysis showed that protein identities and positives between quail and chicken were93%and98%respectively, which were higher than that between quail and any of other mammals or Xenopus laevis. In addition, the hydrophobisity of quail and chicken FM03protein sequences was extremely similar. There existed a strong hydrophobic region in the C-terminal in either protein sequences. Real-time fluorescence quantitative PCR results showed that quail FMO3gene expression has tissue specificity. The expression relative amount of quail FM03gene is the highest in liver, secondly in kidney, thirdly in lung among all14kinds of tissues. A cytimidine to thymine mutation was found being associated with trimethylamine in quail eggs, which led to a codon coding glutamine to stop codon change in the319th amino acid residual in quail FM03protein. The egg yolk trimethylamine of TT genotype individuals increased distinctly after choline-enrich feed intake, which was very significantly higher than before treatment (P<0.01). Moreover, their egg yolk trimethylamine was very significantly higher than that of the CC and CT genotype individuals in same treatment group as well (P<0.01). The trimethylamine content of the other2groups showed no differences after choline-rich feed intake treatment (P>0.05).This study probed the preliminary genetic mechanism that quail FMO3gene mediating egg yolk trimethylamine, and provided preliminary theoretic basis for the quail egg quality and flavor breeding.