| Navodon septentrionalisis considered as one of the most economic marinefishes in China. This paper takes Navodon septentrionalis which cultured in Baijiafishery company (Yantai, Shandong province) as an experimental fish. The period ofthe whole experiment is one year. In this study, the gonadal tissue, sexual steroidhormone of serum and expression patterns of sexual steroid hormone receptores inNavodon septentrionalis are study by immunohistochemical and radioimmunoassayand biochemical methods in details. The results are as follows:1. Immunohistochemical study on the gonads of NavodonseptentrionalisThe samples were collected every two month for a year. Then gonad sampledand used to study the immunohistochemical to locate the estrogen receptor α (ERα)and androgen receptor (AR). The results showed that the gonads at different stagesexhibit immunopositive reaction in varying degrees to the two receptors. In ovary, inthe early period of oocytes, it shows strong immunopositive reaction to ERαantibodies. With the oocyte mature, the immunopositive reaction to AR antibodiesincreased gradually. These results demonstated that estrogen and its receptor play acrucial role in the early development of ovarian, while we know little about themechanism of androgen and its receptor to ovary development. In testis, interstitialcell shows strong immunopositive reaction to the two receptors, whereas reproductivecells show stronger immunopositive reaction to ERα than AR which indicate thatestrogen and its receptor make a critical difference in testis development. This alsomay indicate that androgen and its receptor stimulate germ cell development, matureand maintain.2. Molecular cloning and expression analysis of estrogen receptor (ERs) in Navodon septentrionalisIn this experiment, three estrogen receptors are isolated from ovary of Navodonseptentrionalis. The length of ERα partial cDNA sequence is1410base pairs [bp],and encodes470amino acids; the full-length cDNA of ERβ1and ERβ2consist of2192bp and2363bp, respectively, including an open reading frame encoding deducedprotein of565and662amino acid residues. Biological softwares are used to comparethe three cloned ERs sequences with that of other ERs and some structure identitiesare found in these sequences. In this paper, the tissue distribution of ERs mRNA inNavodon septentrionalis is examined using RT-PCR. The results show that the threeERs mRNA are present in most tissue of adult female fishes including somenon-reproductive tissue like gill, kidney and spleen, while they have a restricteddistribution in males. Particularly, except for the testis, it is undetectable in other forERβ1in males. In addition, we analyzed the relative expression level of ERs inreproductive cycle in ovary and testis by quantitative RT-PCR together with GSI andserum E2and T, and ERs mRNA expression pattern appear to be gonad developmentstage-dependent and related to the serum E2throughout the annual reproductive cycle.These results indicate that E2and its receptor can stimulate gonads development andmature.3. Molecular cloning and expression analysis of androgen receptor(AR) in Navodon septentrionalisThe androgen receptoris isolated from ovary of Navodon septentrionalis for thefirst time. The length of AR partial cDNA sequence is769bp, and encodes256aminoacids. Biological softwares are used to compare the AR sequence with that of otherAR and some structure identities are found in these sequences. In this paper, the tissuedistribution of AR mRNA in Navodon septentrionalis is examined using RT-PCR. Theresults show that the AR mRNA is present in all tissues of adult male fishes, whereasit has a restricted distribution in females, being more abundant in males. The AR isconsidered more closely to ARβ than ARα. In addition, we analyzed the relativeexpression level of AR in reproductive cycle in ovary and testis by qRT-PCR together with serum T, and AR mRNA expression pattern appear to be gonad developmentstage and serum T-dependent throughout the annual reproductive cycle. |
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