Characterization of fish activin

我们克隆了虹鳟鱼激活βA和βB、抑制素A、水母激活βA和βB、鲤鱼激活βA和βB的cdna。这些cDNA的成熟蛋白编码区与人类激活素和抑制素的编码区具有高度的同源性。同时克隆了虹鳟激活素βA和抑制素A基因。基因βA和抑制素A的结构都有两个外显子和一个内含子。采用RT-PCR检测虹鳟激活基因的表达。在mRNA水平上，虹鳟激活素的主要表达组织为卵巢和脑，其主要表达亚基为βB亚基。利用互补RNA探针原位杂交技术研究了虹鳟鱼卵巢和睾丸不同腔室中抑制素α、激活素βA和βB的分布。在睾丸中，抑制素α、激活素βA和βB仅在分布有Sertori细胞和Leydig细胞的精小叶之间的睾丸间质中表达。在每个月取样的所有卵巢中，卵泡的卵泡膜细胞层对抑制素α和激活素βA和βB杂交的cRNA探针有强烈的反应。在7月取样的卵巢中发现退行性卵母细胞，出现阳性反应。利用重组人激活素A的异源抗体，免疫组织化学方法研究了激活素A在虹鳟鱼性腺中的分布及其季节性变化。在睾丸中，在产卵季节结束时精子退化期间检测到激活素A-ir。在卵巢中，激活素A-ir从性腺复发到排卵增加，但在排卵后完全消失。

We cloned cDNAs of rainbow trout activin βA and βB, inhibin A, medaka activinβA and βB, and carp activinβA and βB. The mature protein coding regions of these cDNA have high homologies to those of human activin and inhibin. The genes of rainbow trout activinβA and inhibin A were also cloned. The structure of both genes βA and inhibin A have two exons mad one intron. The expression of rainbow trout activin genes was examined by RT-PCR. The major expression tissue of rainbow trout activin was ovary and brain at the mRNA level, and the major expression subunit of rainbow trout was βB subunit.Distribution of inhibin α and activin βA and βB in different ovarian and testis compartments were studied in rainbow trout by in situ hybridization with complementary RNA probes. In testes, inhibin α-and activin βA and βB were only expressed in the testicular interstitia between the seminal lobules, where Sertori cells and Leydig cells are distributed. In all the ovaries sampled every month period, theca cell layers of follicles had the strong reactions of cRNA probes hybridizing against inhibin α and activin βA and βB. In the regressive oocyte found in the July-sampled ovary, the positive reaction appeared.Distribution of activin A and its seasonal changes in the gonads of rainbow trout were immunohistochemically investigated using an heterologous antibody against recombinant human activin A. There were clear seasonal changes in activin A-ir in the gonads. In the testis, activin A-ir was detected during the degeneration of spermatozoa at the end of the spawning season. In the ovary, activin A-ir increased from gonadal recrudescence to ovulation, but disappeared completely after ovulation.