关键词: 鲫鱼, Ca-VtgAo1基因, Ca-VtgC基因, 系统进化分析, 组织表达

Abstract: In order to study the biological functions and molecular mechanisms of different Vitellogenin (Vtg) subtype genes in Carassius auratus, two subtypes of Vtg homologous genes were cloned and identified,named Ca-VtgAo1 and Ca-VtgC,respectively.The full-length cDNA sequences of Ca-VtgAo1 and Ca-VtgC were 4 241 bp and 4 207 bp,the open reading frames(ORF) were 3 873 bp and 3 612 bp,and the 5′untranslated regions (UTR) were 192 bp and 150 bp,3′UTR were 176 bp and 445 bp,encoding 1 290 and 1 203 amino acid residues,and the predicted protein molecular weight were about 140.6 ku and 134.8 ku,respectively. The domain analysis results showed that both Ca-VtgAo1 and Ca-VtgC had the conserved domains of LPD_N (lipoprotein N-terminal domain),DUF1943 and DUF1944,but neither had β′-component yolk protein(β′-C) and the carboxy-terminal component yolk protein(CT)domain,and Ca-VtgAo1 had the phosvitin(Pv) domain,Ca-VtgC did not have this domain.The results of evolutionary analysis showed that VtgC first clustered with VtgABCD in Ichthyomyzon unicuspis,and then clustered with VtgAa,VtgAb,VtgAe and VtgAo.Ca-VtgAo1,due to the Pv domain,evolved faster than Ca-VtgC.Quantitative real-time PCR analysis results showed that Ca-VtgAo1 mRNA was expressed in the tested tissues,of which the relative expression level in liver tissue reached the highest,and the relative expression level of Ca-VtgAo1 mRNA in female liver was fifty times of that in male liver.The relative expression level suggests that the source of Vtg is mainly exogenous synthesis in the liver,but the old way of endogenous synthesis of Vtg in the ovary is still retained.The Ca-VtgAo1 gene can be used as a molecular marker for sex identification in C.auratus.

Key words: Carassius auratus, Ca-VtgAo1 gene, Ca-VtgC gene, Phylogenetic analysis, Tissue expression