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Steroids are known to play a crucial role in gonadal sex differentiation in many non-mammalian vertebrates, but also in the
gonadal sex change of hermaphroditic teleosts. We investigated the expression of two genes encoding key steroidogenic enzymes,
i.e., cytochrome P450 aromatase (P450arom) and cytochrome P45011β-hydroxylase (P45011β), during the sex change of the protogynous
rice field eel, Monopterus albus. Using RT-PCR with degenerate primers, we cloned rice field eel homologous fragments for both genes (rcP450arom and rcP45011β)
as indicated by the high level of homology with P450arom and P45011β sequences from various vertebrates. Gonadal expression
of rcP450arom and rcP45011β mRNA levels were then assessed during the sex change by semi-quantitative RT-PCR and a real-time
RT-PCR. rcP450arom was predominantly expressed in ovary, much less in ovotestis, and barely in testis. Conversely, P45011β
was markedly up-regulated at the onset of testicular development. These findings underline that regulation of steroidogenesis
is an important process in the sex change of protogynous rice field eel, and they clearly indicate that the concomitant down-regulation
of P450arom and up-regulation of P45011β are of pivotal importance to the sex change of this species. 相似文献
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Koichiro Gen Sonoko Yamaguchi Koichi Okuzawa Naoki Kumakura Hideki Tanaka Hirohiko Kagawa 《Fish physiology and biochemistry》2003,28(1-4):77-80
The duality of gonadotropins (GTHs), follicle-stimulating hormone (FSH) and luteinizing hormone (LH), has been confirmed in most teleost species, but very little is known about their biological functions. To elucidate the physiological roles of FSH and LH in fish reproduction, the expression profiles of GTH subunit genes during gonadal development were analyzed in both male and female red seabream. Furthermore, in vitro studies were carried out to examine the effects of GTHs on steroid hormone production and cytochrome P450 aromatase (P450arom) expression in red seabream gonads. In both sexes, LHβ mRNA was maintained at high levels from the early gametogenesis until spawning season, and declined with gonadal regression. Interestingly, FSHβ mRNA levels in males increased in parallel with testicular development, whereas those in female were remained low throughout oocyte development. From in vitro studies using purified red seabream FSH and LH, both GTHs had a similar potency in stimulating 11-ketotestosterone production by testicular slices, while the biological activity of FSH was much lower than that of LH in stimulating production of estradiol-17β by vitellogenic follicles. Moreover, expression of P450arom mRNA was induced by LH, but not FSH, in ovarian follicles in vitro. FSH was also ineffective in inducing maturational competence and final oocyte maturation. These results suggest that, unlike salmonids, FSH may play an important role during gametogenesis in male, but not female, red seabream, whereas LH may be involved in regulation of both early and late gametogenesis in both sexes. 相似文献
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In the present study, we implanted 2‐year‐old female red‐spotted grouper, Epinephelus akaara, with a non‐steroidal aromatase inhibitor (AI), fadrozole, in the breeding season and examined changes in gonadal histology, serum sex steroids, aromatase activities and P450 aromatase (P450arom) gene expression in gonads after AI implantation. Aromatase inhibitor at doses from 0.1 to 10.0 mg kg?1 BW induced a sex inversion and completion of spermatogenesis up to the functional male phase, but doses of 1.0 and 10.0 mg kg?1 BW AI produced more males than 0.1 mg kg?1 BW AI. Serum estradiol‐17β (E2) levels decreased, but 11‐ketotestosterone (11‐KT) levels increased significantly in all the AI‐implanted groups, whereas testosterone (T) levels increased significantly only in the 1.0 mg kg?1 BW AI‐implanted group. Aromatase activities and P450arom gene expression in gonads were inhibited significantly in the AI‐implanted groups, which was in accordance with the decrease in serum E2 levels. These results suggested the optimal dose of AI to induce sex inversion to be 1.0 mg kg?1 BW. Furthermore, the sex inversion induced by AI may be attributed to the inhibition of P450arom gene expression and aromatase activity and the resultant decrease in the biosynthesis of endogenous E2. Meanwhile, the elevated 11‐KT levels were also associated closely with the occurrence of sex inversion in protogynous red‐spotted grouper. 相似文献
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C.C. Sudhakumari B. Senthilkumaran T. Kobayashi D.S. Wang X.T. Chang Y. Nagahama 《Fish physiology and biochemistry》2003,28(1-4):177-178
Present study revealed the expression of ovarian (oP450arom) and brain (bP450arom) type cytochrome P-450 aromatases in the gonads and brains of sex reversed Nile tilapia. 相似文献
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J. K. Sundaray K. Ohta A. Yamaguchi T. Kitano M. Matsuyama 《Fish physiology and biochemistry》2005,31(2-3):137-141
Pseudolabrus sieboldi, wrasse being a diurnal spawner provides a good opportunity to study the endocrine mechanism of estrogen formation in brain
and gonads. Moreover, an extremely large amount of E2 was produced in serum and testis of wrasse. It is assumed that the presence
of E2 may play a major role in diurnal gametogenesis in male fish. In this study brain type aromatase have been isolated,
cloned and sequenced from the brain of wrasse. Further, the expression pattern of brain type aromatase in gonads and adult
tissue of male and female fish have been analyzed. In addition, the diurnal expression pattern of brain type aromatase in
both male and female fish brain during spawning season have been analyzed.
The P450arom (br) was isolated, cloned and sequenced from both male and female bamboleaf wrasse. The P450arom (br) gene (1877
sequenced nucleotide) contains an ORF of 1470 bp, a 5′-UTR of 18 bp and at least 407 bp in 3′-UTR. The amino acid sequence
homology in the coding region of wrasse P450arom (br) is high compared to that of medaka, Oryzias latipes (80%), rainbow trout type 2, Oncorhynchu mykiss (78.2%), fugu, Takifugu ribripes (78%) rainbow trout type 1, (76%), goldfish, Carassius auratus (66.8%) and zebrafish, Danio rerio (66.2%). Expression study reveals that P450arom (br) mRNA were most abundant in brains of both male and female fish throughout
the day during the spawning season. RT-PCR study revealed that P450arom (br) was expressed in skin, anal fin and tail fin
of both male and female wrasse. P450arom (br) was not detected at any time of the spawning day in either ovary or testis of
wrasse. 相似文献
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The effect of gonadotropins, forskolin and IGF-I on steroidogenic enzyme gene expression and E2 production by the rainbow trout follicle were measured. The results indicate that 3β-HSD gene expression is regulated by gonadotropins partially through the cAMP/PKA mechanism. The effect of IGF-I on P450arom mRNA levels suggests that IGF-I is a major regulator of P450arom gene expression. 相似文献
10.
Jin GX Wen HS He F Li JF Chen CF Zhang JR Chen XY Shi B Shi D Yang YP Qi BX Li N 《Fish physiology and biochemistry》2012,38(3):807-817
P450c17, a key steroidogenic enzyme, plays important roles in the production of sex steroid and cortisol. In teleost, there are two types of P450c17, P450c17-I possessing 17α-hydroxylase and 17, 20-lyase activities, and P450c17-II only possessing 17α-hydroxylase activity. This work describes the molecular cloning of the cDNA encoding the barfin flounder (Verasper moseri) P450c17-I and P450c17-II by means of RT-PCR and 5' and 3' rapid amplification of cDNA ends (RACE) analyses and mRNA expression profiles analyzing by semiquantitative RT-PCR. Respectively, P450c17-I and P450c17-II mRNA levels in the testes correlated with serum testosterone (T) level, as well as gonadosomatic index (GSI) of males during specific stages of spermatogenesis. P450c17-I and P450c17-II mRNA were expressed in the testis and ovary, suggesting that both of them participate in the production of sex steroid in barfin flounder gonads. P450c17-I mRNA was undetectable; in contrast, P450c17-II mRNA was detected at the highest level in the head kidney, meaning that only P450c17-II is involved in the production of cortisol in barfin flounder. The results demonstrated that both of P450c17-I and P450c17-II participate in the production of sex steroid in male barfin flounder gonads. 相似文献
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The effects of aromatizable 17α-methyltestosterone (MT) and non-aromatizable 17α-methyldihydrotestosterone (MDHT) on sex inversion
in red-spotted grouper, Epinephelus akaara, were investigated. Fish were implanted with MT, MDHT and MT+AI (aromatase inhibitor, AI) respectively for one month. The
results showed that the three treated groups turned into transitional stage with intersex gonads, which contained atretic
oocytes and spermatogenic germ cells at all stages of spermatogenesis. The controls did not change sex. The gonads of more
than half MT-implanted fish were in early transitional stages of sex inversion, whereas those of more than half MDHT and MT+AI-implanted
fish were in late transitional stages of sex inversion. No difference in serum estradiol-17β (E2) levels between the controls and the treated groups were observed, whereas 11-ketotestosterone (11-KT) and testosterone (T)
levels increased in all treated groups. Significantly lower gonadosomatic index (GSI) and gonadal aromatase activity were
observed in the treated groups, which were in accordance with the lower mRNA expression of P450aromA. However, P450aromB mRNA
expression increased in the MT group, while it did not change in the MDHT group. These results suggest that the sex inversion
of red-spotted grouper by MT and MDHT implantation might be due to the suppression of P450aromA gene expression, and resulting
in both the decrease of the ovarian estrogen –secretion, as well as the increase in the 11-KT levels. Furthermore, the main
reason for MT being less effective than MDHT might be due to partial aromatization of MT to estrogen. 相似文献
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Yasuhisa Kobayashi Tomoki Sunobe Tohru Kobayashi Yoshitaka Nagahama Masaru Nakamura 《Fish physiology and biochemistry》2005,31(2-3):123-127
Despite numerous endocrine studies on sex change in teleost, no general mechanism that mediates sex change has emerged. The
gobiid fish, Trimma okinawae, can change sex in both directions repeatedly. This phenomenon of sex change in goby assigns it as an excellent animal model
to elucidate the understanding mechanisms of sex change. In hermaphrodite fishes, estrogen plays a particularly important
role in natural and experimentally induced sex change. To investigate the role of estrogen in the serial-sex changing fish
T. okinawae, we cloned and analyzed the 5′-flanking regions of P450arom genes from goby genome DNA. Both regions have consensus sequences
of TATA, CRE and ERE. Ad4 binding site was restricted in the region of P450aromA. These findings indicate that different regulators
control the expression of the two P450arom genes. 相似文献
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在水温分别为20(常温对照组)、25、30℃条件下,采用RT-PCR方法,研究性腺成熟期雄性黄颡鱼组织中P450芳香化酶(P450aromA和P450aromB)的mRNA表达水平,同时测定性腺成熟系数(GSI)、肝重指数(HSI)、肥满度(CF)和血浆睾酮(T),雌二醇(E2)含量。结果表明,P450aromA在性腺发育成熟期雄性黄颡鱼心脏、肝、脾、胃、肾脏、精巢、鳃、脑、头肾、肠管组织中均无表达,P450aromB只在脑和肠中有表达,在脑中表达量高于肠,表达量随着水温升高而显著下降;各组实验鱼血浆T和E2含量与芳香化酶基因表达量存在相关关系。该实验结果表明,P450aromA可能与精子发生相关,可能不参与黄颡鱼精子排放过程;P450aromB在雄鱼脑中高度表达,可能参与性腺成熟期精子活力保持与排放过程,且应激温度越高,对性腺成熟期精子活力保持与排放过程影响越大。 相似文献
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黄鳝脑芳香化酶基因cDNA的克隆及组织表达特异性分析 总被引：1，自引：0，他引：1
根据NCBI数据库报道的黄鳝芳香化酶基因的gDNA序列,设计了一对特异性引物.用Trizol试剂盒提取黄鳝脑总RNA,反转录获得cDNA第一条链,进行PCR扩增.扩增产物经过回收、连接、测序后得到了一条长1514 bp的芳香化酶基因cDNA序列.同源性比较表明该基因属于脑型P450aromB,与其他鱼类脑型P450aromB的同源性较高(>70%),与性腺型P450aromA的同源性较低(<60%),与自身性腺型芳香化酶同源性为59.5%.采用RT-PCR的方法对该基因在雄性黄鳝的各组织表达情况进行了分析,结果表明,该基因的转录本较高的表达于脑和精巢中,较低的在皮肤中表达,而在肝脏、心脏、小肠、肌肉等组织中没有检测到该基因的表达. 相似文献
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Shigeho Ijiri Norio Takei Shinji Andachi Kohei Yamauchi 《Fish physiology and biochemistry》2003,28(1-4):209-210
Antibodies against P450scc, P450c17 and P450arom were generated using recombinant proteins. In eel testis, P450scc and P450c17 were immunolocalized as clusters in Leydig cells. In vitellogenic eel ovary, P450scc and P450c17 immunoreactive cells were localized as clusters in the outer layer of the ovarian follicle. In contrast, P450arom seemed to be immunolocalized in the innermost follicle layer. 相似文献
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J.K. Sundaray K. Ohta A. Yamaguchi K. Suzuki M. Matsuyama 《Fish physiology and biochemistry》2003,28(1-4):193-195
The wrasse, Pseudolabrus sieboldi, is a diandric protogynous labrid fish. Spawning is performed by a terminal phase (TP) male and an initial phase (IP) female between 6:00 and 9:00 h daily during two-month-long spawning season. In the present study, to investigate the roles of steroid hormones in the diurnal spermatogenesis of the P. sieboldi TP male, all steroid hormones produced in the testis were identified and the synthetic pathways of these steroids were determined. Furthermore, the circulating levels of the major steroids produced were analyzed throughout a day at 3-hour intervals during spawning season. In the testis, 11-ketotestosterone (11-KT), estradiol-17β (E2), 17,20β-dihydoxy-4-pregnane-3-one (17,20β-P) and 17,20β,21-trihydroxy-4-pregnen-3-one (20β-S) were synthesized as the major metabolites. In vitro steroid biosynthesis experiments showed similar results to the circulation profiles of the major steroids. This study is the first to clarify the complete steroidogenic pathways in the gonads of a diandric protogynous species throughout its life, when combined with the results of the steroidogenesis in the ovarian follicles. This is also the first report of a clear diurnal rhythm of the steroid production corresponding to the spermatogenic process in the testis of a male teleost. 相似文献
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Martín Blasco Gustavo Manuel Somoza Denise Vizziano-Cantonnet 《Fish physiology and biochemistry》2013,39(1):71-74
The involvement of androgens during sex differentiation period was investigated in the pejerrey Odontesthes bonariensis, by classic biochemical studies and gonadal histology. We studied in particular whether the enzyme activities involved in 11-oxygenated androgen production were active in a gonadal/peritoneum complex (GPC) of very small larvae exposed to masculinizing temperatures previous to morphological sex differentiation (5 weeks post-hatching). The GPC was incubated with 17-hydroxyprogesterone (3H-17P), and the presence of 11-KT as major metabolite in early gonads undergoing masculine pathway after temperature treatment exposure is reported. 11-KT was identified by thin-layer chromatography and high-pressure liquid chromatography. The present results show that 11-KT is produced at very early stages of testis development in pejerrey, being this androgen one of the main mediators of the masculinization induced by temperature treatment at the gonad level. 相似文献