Estrogen hydroxylases (EHs) are cytochrome P450 Family 1 (Cyp1, Clan 2) proteins involved in estrogen hydroxylations at 2-, 4- or 16- carbon positions to form catecholestrogens. EHs are encoded by CYP1A1, CYP1A2 and CYP1B1 in mammals. In the catfish Heteropneustes fossilis, cyp1a1 and cyp1b1 cDNAs were cloned and characterized from liver and ovary. The cyp1a1 cDNA is 2071 bp long and codes for a 518 amino acids (aa) long protein. The cloned cyp1b1 cDNA is 1927 bp long and codes for a 509 residue protein. The deduced proteins clustered distinctly into teleost Cyp1a1 and Cyp1b1 clades, distinct from the tetrapod clusters and featured common function domains and homology with other teleost proteins. In the qPCR assay, the transcripts were the most abundant in the liver, followed by brain and ovary, and moderate in gill, kidney and muscle. Evidence was presented to show the involvement of the genes in reproduction. Expression of brain and ovarian transcripts showed significant seasonal variations with the highest abundance in the spawning phase. In situ hybridization showed the transcripts in the follicular layer (theca and granulosa) of the ovarian follicles. Periovulatory changes in the expression cyp1a1 and cyp1b1 were obtained during final oocyte maturation (FOM) and ovulation induced by human chorionic gonadotropin (hCG), both in vivo and in vitro, and by 2-hydroxyestradiol-17β (catecholestrogen) in vitro. In the brain, the transcript levels increased with time but in the ovary, the increase was maximal at 16 h and decreased at 24 h. The periovulatory activation of the cyp1 genes was reported in this study and discussed on the basis of complex regulation of FOM and ovulation.

雌激素羟化酶 (EH) 是细胞色素 P450 家族 1（Cyp1，Clan 2）蛋白，参与雌激素在 2、4 或 16 位碳位的羟化以形成儿茶酚雌激素。EHs 在哺乳动物中由 CYP1A1、CYP1A2 和 CYP1B1 编码。在鲶鱼Heteropneustes 化石中，从肝脏和卵巢中克隆和表征了cyp1a1和cyp1b1 cDNA。与c yp1a1的cDNA是2071个碱基长，并编码一种518个氨基酸（aa）长的蛋白质。克隆的cyp1b1cDNA 长 1927 bp，编码 509 个残基蛋白质。推导出的蛋白质明显地聚集成硬骨鱼 Cyp1a1 和 Cyp1b1 进化枝，与四足类集群不同，并具有共同的功能域和与其他硬骨鱼蛋白质的同源性。在 qPCR 测定中，转录物在肝脏中含量最高，其次是脑和卵巢，在鳃、肾脏和肌肉中含量适中。有证据表明基因参与繁殖。大脑和卵巢转录本的表达显示出显着的季节性变化，在产卵期丰度最高。原位杂交显示了卵巢卵泡的卵泡层（卵泡膜和颗粒层）中的转录物。cyp1a1和cyp1b1表达的排卵期变化在体内和体外由人绒毛膜促性腺激素 (hCG) 和体外 2-羟基雌二醇-17β（儿茶酚雌激素）诱导的最终卵母细胞成熟 (FOM) 和排卵期间获得。在大脑中，转录水平随时间增加，但在卵巢中，增加在 16 小时达到最大，并在 24 小时下降。本研究报道了cyp1基因的排卵期激活，并在 FOM 和排卵的复杂调节的基础上进行了讨论。