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细胞色素P450芳香化酶(P450arom)作为P450细胞色素酶超家族中的一员,是性类固醇生成途径中的末端酶,能够将雄激素转化为雌激素。在大多数脊椎动物中,P450arom由CYP19单基因编码。但是在鱼类中存在两种P450芳香化酶,分为性腺型芳香化酶(P450aromA)和脑型芳香化酶(P450aromB),它们由不同的基因(CYP19a和CYP19b)编码,分布在不同的组织。通过简并引物扩增及RACE cDNA扩增克隆,在国内外首次获得全长为2167bp的条斑星鲽CYP19a cDNA序列,并将推测的氨基酸序列与其它物种P450arom氨基酸序列进行多重比较,发现存在跨膜螺旋区、I-螺旋区、Ozol肽区、芳香化酶特异保守区以及血红素结合区。通过RT-PCR分析了P450aromA mRNA在条斑星鲽不同组织中的表达情况,结果表明,CYP19a基因主要在脑、卵巢和精巢中表达,其次在肠、肝脏、肾脏也有少量表达。同时也分析了P450aromA mRNA在处于不同发育期的精巢中的表达情况,发现在Ⅱ期精巢中表达量最高,在Ⅴ期精巢中表达量最低。
As a P450 cytochrome superfamily, cytochrome P450 aromatase (P450arom) is the terminal enzyme in the sex steroidogenic pathway that converts androgens to estrogen. P450arom is encoded by the CYP19 single gene in most vertebrates. However, there are two P450 aromatases in fish, which are divided into the glandular aromatase (P450aromA) and the brain aromatase (P450aromB), which are encoded by different genes (CYP19a and CYP19b) and distributed in different tissues . Through the degenerate primer amplification and RACE cDNA amplification cloning, the 2167bp full length cDNA of CYP19a was obtained at home and abroad, and the deduced amino acid sequence was compared with the P450arom amino acid sequence of other species for multiple comparison. Membrane helix region, I-helix region, Ozol peptide region, aromatase-specific conserved region, and heme-binding region. The expression of P450aromA mRNA was detected by RT-PCR. The results showed that the CYP19a gene was mainly expressed in the brain, ovary and testes, followed by a small amount of expression in the intestine, liver and kidney. The expression of P450aromA mRNA in the testis at different developmental stages was also analyzed. The results showed that the expression level of P450aromA mRNA was the highest in stage Ⅱ and the lowest in stage Ⅴ.