Publications by authors named "Yan-Horn Lee"

27 Publications

  • Page 1 of 1

Variation in the Karyotype, Cytochrome Gene, and 5S rDNA of Four (Perciformes, Scombridae) Tunas.

Zool Stud 2018 10;57:e34. Epub 2018 Jul 10.

Department of Aquaculture, National Pingtung University of Science & Technology, Pingtung 912, Taiwan. E-mail: (Chen).

tunas in Scombridae are divided into the temperate subgenus (bluefin group) and tropical subgenus (yellowfin group) species based on anatomic traits and distributions. The main purpose of this study was to examine the systematic status of based on karyotype, cytochrome (Cyt) gene, and 5S ribosomal DNA sequences. All , , , and specimens were caught in southeastern coastal waters off the main island of Taiwan. The karyotypical formula of was 2 m + 2 st + 44 t, that of was 2 m + 2 sm + 2 st + 42 t, that of was 2 m + 2 sm + 2 st + 42 t, and that of was 2 m + 2 sm + 44 t (m: metacentric; sm: submetacentric; st: subtelocentric; t: telocentric chromosome). According to a molecular genetics analysis for these species using Cyt gene sequences (1141 bp), interspecific genetic distances ranged from 0.004 ( vs. ) to 0.038 ( vs. ). The genealogy tree exhibited these 4 species as being categorized into 4 monophyletic groups with high bootstrapping values; and are sister species. This result suggests that the species currently allocated in and might need new taxonomic characters to redefine the monophyly of the two subgenera. The sequence lengths of all cloned 5S genes from the 4 species ranged from 327-342 bp. Interspecific genetic distances ranged from 0.016 ( vs. ) to 0.111 ( vs. ). The phylogenetic tree based on 5S rDNA shows divided into 2 groups: one similar to and the other close to . These results imply that tunas have a common synapomorphic character with Scombridae fish (2n = 48) and high numbers of telocentric chromosomes (42-44). and are sister based on molecular data. may have been derived from a more-complicated speciation processes.
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http://dx.doi.org/10.6620/ZS.2018.57-34DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6517716PMC
July 2018

Oocytes express an endogenous red fluorescent protein in a stony coral, Euphyllia ancora: a potential involvement in coral oogenesis.

Sci Rep 2016 05 11;6:25868. Epub 2016 May 11.

Center of Excellence for the Oceans, National Taiwan Ocean University, Keelung, 20224, Taiwan.

To date,the molecular and cellular mechanisms underlying coral sexual reproduction remain largely unknown. We then performed a differential screen to identify genes related to oogenesis in the stony coral Euphyllia ancora. We identified a clone encoding a novel red fluorescent protein cDNA of E. ancora (named EaRFP). Microscopic observation and quantitative RT-PCR revealed that EaRFP is almost exclusively expressed in the ovary of the adult coral. The combination of the ovarian-cell separation method and the RT-PCR analysis revealed that the oocytes, but not the ovarian somatic cells, are the cells expressing EaRFP. Immunohistochemical analysis revealed that the expression of EaRFP starts in the early stage of the oocyte and continues until the maturation period. Furthermore, recombinant EaRFP was shown to possess an H2O2 degradation activity. These results raise the possibility that EaRFP plays a role in protecting the oocytes from oxidative stress from the early to late stages of oogenesis. The present study provides not only the first evidence for the potential involvement of FPs in coral oogenesis but also an insight into a cellular strategy underlying coral sexual reproduction.
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http://dx.doi.org/10.1038/srep25868DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4863156PMC
May 2016

Molecular cloning and characterization of a steroidogenic enzyme, 17β-hydroxysteroid dehydrogenase type 14, from the stony coral Euphyllia ancora (Cnidaria, Anthozoa).

Gen Comp Endocrinol 2016 Mar 8;228:95-104. Epub 2016 Feb 8.

Center of Excellence for the Oceans, National Taiwan Ocean University, Keelung, Taiwan; Department of Aquaculture, National Taiwan Ocean University, Keelung, Taiwan. Electronic address:

Sex steroids play a fundamental role not only in reproduction but also in various other biological processes in vertebrates. Although the presence of sex steroids has been confirmed in cnidarians (e.g., coral, sea anemone, jellyfish, and hydra), which are basal metazoans, only a few studies to date have characterized steroidogenesis-related genes in cnidarians. Based on a transcriptomic analysis of the stony coral Euphyllia ancora, we identified the steroidogenic enzyme 17β-hydroxysteroid dehydrogenase type 14 (17beta-hsd 14), an oxidative enzyme that catalyzes the NAD(+)-dependent inactivation of estrogen/androgen (estradiol to estrone and testosterone to androstenedione) in mammals. Phylogenetic analysis showed that E. ancora 17beta-Hsd 14 (Ea17beta-Hsd 14) clusters with other animal 17beta-HSD 14s but not with other members of the 17beta-HSD family. Subsequent quantitative RT-PCR analysis revealed a lack of correlation of Ea17beta-hsd 14 transcript levels with the coral's reproductive cycle. In addition, Ea17beta-hsd 14 transcript and protein were detected in all tissues examined, such as the tentacles, mesenterial filaments, and gonads, at similar levels in both sexes, as determined by quantitative RT-PCR analysis and Western blotting with an anti-Ea17beta-Hsd 14 antibody. Immunohistochemical analysis revealed that Ea17beta-Hsd 14 is mainly distributed in the endodermal regions of the polyps, but the protein was also observed in all tissues examined. These results suggest that Ea17beta-Hsd 14 is involved in important functions that commonly occur in endodermal cells or has multiple functions in different tissues. Our data provide information for comparison with advanced animals as well as insight into the evolution of steroidogenesis-related genes in metazoans.
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http://dx.doi.org/10.1016/j.ygcen.2016.02.006DOI Listing
March 2016

A Novel Female-Specific and Sexual Reproduction-Associated Dmrt Gene Discovered in the Stony Coral, Euphyllia ancora.

Biol Reprod 2016 Feb 6;94(2):40. Epub 2016 Jan 6.

Department of Aquaculture, National Taiwan Ocean University, Keelung, Taiwan Center of Excellence for the Oceans, National Taiwan Ocean University, Keelung, Taiwan

Transcription factors encoded by the Dmrt gene family regulate multiple aspects of animal reproduction. Most studies investigating the Dmrt gene family were conducted in model organisms from bilateral species, with a particular emphasis on gene function in male sex determination. It is still unclear whether the E. ancora Dmrt (EaDmrt) genes found in basal metazoans such as cnidarians share similar characteristics with orthologs in other metazoans. In this study, seven full Dmrt gene transcript sequences for a gonochoric coral, Euphyllia ancora (phylum: Cnidaria; class: Anthozoa), were obtained through transcriptome data mining, RT-PCR analysis, rapid amplification of cDNA ends, and sequencing. These EaDmrts were subjected to quantitative assays measuring temporal and tissue-specific expression. Results demonstrated a unique gene expression pattern for EaDmrtE, which is enriched in female germ cells during the spawning season. Based on the phylogenetic analyses performed across the homologous Dmrt genes in metazoans, we found that the female-specific EaDmrtE gene is not related to the DM1 gene of Acropora spp. coral nor to Dmrt1 of vertebrates, which are involved in sexual reproduction, especially in sex determination (vertebrate Dmrt1). Additionally, high levels of EaDmrtE transcripts detected in unfertilized mature eggs are retained in newly formed zygotes but decrease during embryonic development. We suggest that the newly discovered gene may play a role in oogenesis and early embryogenesis as a maternal factor in corals. Therefore, the sexual reproduction-associated Dmrt gene(s) should have arisen in cnidarians and might have evolved multiple times in metazoans.
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http://dx.doi.org/10.1095/biolreprod.115.133173DOI Listing
February 2016

From Somatic Cells to Oocytes: A Novel Yolk Protein Produced by Ovarian Somatic Cells in a Stony Coral, Euphyllia ancora.

Biol Reprod 2015 Sep 15;93(3):57. Epub 2015 Jul 15.

Center of Excellence for the Oceans, National Taiwan Ocean University, Keelung, Taiwan Department of Aquaculture, National Taiwan Ocean University, Keelung, Taiwan

To gain a better understanding of how corals form their eggs at both the molecular and cellular levels, we performed a differential screen (suppression subtractive hybridization) to identify genes related to oocyte development in a stony coral, Euphyllia ancora. Through the course of screening, a novel gene that contains three alternate repeats of fibronectin domain 2 and epidermal growth factor (EGF)-like domains, as well as an additional calcium-binding EGF-like domain (EGF-CA), was identified and tentatively named euphy after the scientific name of the coral, E. ancora. Quantitative RT-PCR revealed that expression levels of euphy increased in female colonies as the coral approached reproductive season. Tissue distribution analysis followed by mRNA in situ hybridization revealed that euphy is highly expressed in the ovarian (mesenterial) somatic cells in the body of E. ancora. Staining of tissue sections with an antibody against euphy protein (Euphy) revealed Euphy immunoreactivity in both ovarian somatic cells and oocytes. Subsequent Western blotting demonstrated the presence of abundant Euphy in unfertilized mature eggs. These results indicate that Euphy produced in the ovarian somatic cells is transported to and accumulates within oocytes as a yolk protein during oogenesis. We previously showed that two major yolk proteins, vitellogenin and egg protein, are similarly produced by ovarian somatic cells. Hence, the present study uncovered the third ovarian somatic-derived yolk protein in corals. Our data provide new information that contributes to a more comprehensive understanding of coral egg formation.
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http://dx.doi.org/10.1095/biolreprod.115.129643DOI Listing
September 2015

Neuroendocrine gene expression reveals a decrease in dopamine D2B receptor with no changes in GnRH system during prepubertal metamorphosis of silvering in wild Japanese eel.

Gen Comp Endocrinol 2014 Sep 12;206:8-15. Epub 2014 Aug 12.

Department of Aquaculture, National Taiwan Ocean University, Keelung 202, Taiwan; Center of Excellence for the Oceans, National Taiwan Ocean University, Keelung 202, Taiwan. Electronic address:

Silvering is a prepubertal metamorphosis preparing the eel to the oceanic reproductive migration. A moderate gonad development occurs during this metamorphosis from the sedentary yellow stage to the migratory silver stage. The aim of this study was to elucidate the molecular aspects of various endocrine parameters of BPG axis at different ovarian developmental stages in wild yellow and silver female Japanese eels. The GSI of the sampled female eels ranged between 0.18 and 2.3%, corresponding to yellow, pre-silver and silver stages. Gonad histology showed changes from previtellogenic oocytes in yellow eels to early vitellogenic oocytes in silver eels. Both serum E2 and T concentrations significantly increased with ovarian development indicating a significant activation of steroidogenesis during silvering. In agreement with previous studies, significant increases in pituitary gonadotropin beta subunits FSH-β and LH-β transcripts were also measured by qPCR, supporting that the activation of pituitary gonadotropin expression is likely responsible for the significant ovarian development observed during silvering. We investigated for the first time the possible brain neuroendocrine mechanisms involved in the activation of the pituitary gonadotropic function during silvering. By analyzing the expression of genes representative of the stimulatory GnRH control and the inhibitory dopaminergic control. The transcript levels of mGnRH and the three GnRH receptors did not change in the brain and pituitary between yellow and silver stages, suggesting that gene expression of the GnRH system is not significantly activated during silvering. The brain transcript levels of tyrosine hydroxylase, limiting enzyme of DA synthesis did not change during silvering, indicating that the DA synthesis activity was maintained. In contrast, a significant decrease in DA-D2B receptor expression in the forebrain and pituitary was observed, with no changes in DA-D2A receptor. The decrease in the pituitary expression of DA-D2BR during silvering would allow a reduced inhibitory effect of DA. We may raise the hypothesis that this regulation of D2BR gene expression is one of the neuroendocrine mechanisms involved in the slight activation of the pituitary gonadotropin and gonadal activity that occur at silvering.
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http://dx.doi.org/10.1016/j.ygcen.2014.08.001DOI Listing
September 2014

The effect of TLR9 agonist CpG oligodeoxynucleotides on the intestinal immune response of cobia (Rachycentron canadum).

J Immunol Res 2014 2;2014:273284. Epub 2014 Jun 2.

Department of Tropical Agriculture and International Cooperation, National Pingtung University of Science and Technology, Pingtung 91201, Taiwan.

Cytosine-guanine oligodeoxynucleotide (CpG ODN) motifs of bacterial DNA are recognized through toll-like receptor 9 (TLR9) and are potent activators of innate immunity. However, the interaction between TLR9 and CpG ODN in aquatic species has not been well characterized. Hence, cobia TLR9 isoform B (RCTLR9B) was cloned and its expression and induction in intestine were investigated. RCTLR9B cDNA consists of 3113bp encoding 1009 amino acids containing three regions, leucine rich repeats, transmembrane domain, and toll/interleukin-1 receptor (TIR) domain. Intraperitoneal injection of CpG ODN 2395 upregulated RCTLR9 A and B and MyD88 and also induced the expressions of Mx, chemokine CC, and interleukin IL-1 β . Cobia intraperitoneally injected with CpG ODN 1668 and 2395 had increased survival rates after challenge with Photobacterium damselae subsp. piscicida. In addition, formulation of CpG ODN with formalin-killed bacteria (FKB) and aluminum hydroxide gel significantly increased expressions of RCTLR9 A (50 folds) and B (30 folds) isoforms at 10 dpi (CpG ODN 1668) and MyD88 (21 folds) at 6 dpv (CpG ODN 2395). Subsequently, IL-1 β increased at 6 dpv in 1668 group. No histopathological damage and inflammatory responses were observed in the injected cobia. Altogether, these results facilitate CpG ODNs as an adjuvant to increase bacterial disease resistance and efficacy of vaccines in cobia.
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http://dx.doi.org/10.1155/2014/273284DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4060301PMC
February 2015

Identification and expression analysis of cobia (Rachycentron canadum) Toll-like receptor 9 gene.

Fish Shellfish Immunol 2014 Feb 27;36(2):417-27. Epub 2013 Dec 27.

Department of Tropical Agriculture and International Cooperation, National Pingtung University of Science and Technology, Pingtung, Taiwan. Electronic address:

Cobia culture is hindered by bacterial infection (Photobacterium damselae subsp. piscicida) and in order to study the effect of P. damselae subsp. piscicida challenge and CpG ODN stimulation on cobia Toll like receptor 9 (RCTLR9), we used PCR to clone RCTLR9 gene and qRT-PCR to quantify gene expression. The results indicated that RCTLR9 cDNA contains 3141 bp. It encodes 1047 amino acids containing 16 typical structures of leucine-rich repeats (LRRs) including an LRRTYP, LRRCT and a motif involved in PAMP binding was identified at position 240-253 amino acid. Broad expression of RCTLR9 was found in larval, juvenile and adult stages irrespective of the tissues. In larval stage, RCTLR9 mRNA expression decreased at 5 d and then increased at 10 dph. At juvenile stage cobia, the expression was significantly high (p < 0.05) in spleen and intestine compared to gill, kidney, liver and skin. However, at adult stage, the significant high expression was found in gill and intestine. Cobia challenged with P. damselae subsp. piscicida showed significant increase in RCTLR9 expression at 24 h post challenge in intestine, spleen and liver, while in kidney the expression was peak at 12 h and later it decreased at 24 h. The highest expression was 40 fold increase in spleen and the lowest expression was ∼3.6 fold increase in liver. Cobia stimulated with CpG oligonucleotides showed that the induction of these genes was CpG ODN type and time dependent. In spleen and liver, CpG ODNs 1668 and 2006 injected group showed high expression of RCTLR9, IL-1β, chemokine CC compared to other groups. Meanwhile, CpG ODN 2006 has induced high expression of IgM. The CpG ODNs 2395 have induced significant high expression of Mx in spleen and liver. These results demonstrates the potential of using CpG ODN to enhance cobia resistance to P. damselae subsp. piscicida infection and use as an adjuvant in vaccine development.
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http://dx.doi.org/10.1016/j.fsi.2013.12.017DOI Listing
February 2014

Yolk formation in a stony coral Euphyllia ancora (Cnidaria, Anthozoa): insight into the evolution of vitellogenesis in nonbilaterian animals.

Endocrinology 2013 Sep 13;154(9):3447-59. Epub 2013 Jun 13.

Department of Aquaculture, National Taiwan Ocean University, 2 Pei-Ning Road, Keelung 20224, Taiwan.

Vitellogenin (Vg) is a major yolk protein precursor in numerous oviparous animals. Numerous studies in bilateral oviparous animals have shown that Vg sequences are conserved across taxa and that Vgs are synthesized by somatic-cell lineages, transported to and accumulated in oocytes, and eventually used for supporting embryogenesis. In nonbilateral animals (Polifera, Cnidaria, and Ctenophora), which are regarded as evolutionarily primitive, although Vg cDNA has been identified in 2 coral species from Cnidaria, relatively little is known about the characteristics of yolk formation in their bodies. To address this issue, we identified and characterized 2 cDNA encoding yolk proteins, Vg and egg protein (Ep), in the stony coral Euphyllia ancora. RT-PCR analysis revealed that expression levels of both Vg and Ep increased in the female colonies as coral approached the spawning season. In addition, high levels of both Vg and Ep transcripts were detected in the putative ovarian tissue, as determined by tissue distribution analysis. Further analyses using mRNA in situ hybridization and immunohistochemistry determined that, within the putative ovarian tissue, these yolk proteins are synthesized in the mesenterial somatic cells but not in oocytes themselves. Furthermore, Vg proteins that accumulated in eggs were most likely consumed during the coral embryonic development, as assessed by immunoblotting. The characteristics of Vg that we identified in corals were somewhat similar to those of Vg in bilaterian oviparous animals, raising the hypothesis that such characteristics were likely present in the oogenesis of some common ancestor prior to divergence of the cnidarian and bilaterian lineages.
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http://dx.doi.org/10.1210/en.2013-1086DOI Listing
September 2013

Germ cell development in the scleractinian coral Euphyllia ancora (Cnidaria, Anthozoa).

PLoS One 2012 27;7(7):e41569. Epub 2012 Jul 27.

Department of Aquaculture, National Taiwan Ocean University, Keelung, Taiwan.

Sexual reproduction of scleractinian coral is among the most important means of establishing coral populations. However, thus far, little is known about the mechanisms underlying coral gametogenesis. To better understand coral germ cell development, we performed a histological analysis of gametogenesis in Euphyllia ancora and characterized the coral homolog of the Drosophila germline marker gene vasa. The histological analysis revealed that E. ancora gametogenesis occurs in the mesenterial mesoglea between the mesenterial filaments and the retractor muscle bands. The development of germ cells takes approximately one year in females and half a year in males. Staining of tissue sections with an antibody against E. ancora Vasa (Eavas) revealed anti-Eavas immunoreactivity in the oogonia, early oocyte, and developing oocyte, but only faint or undetectable reactivity in developing oocytes that were >150 µm in diameters. In males, Eavas could be detected in the spermatogonia and primary spermatocytes but was only faintly detectable in the secondary spermatocytes, spermatids, and sperms. Furthermore, a reverse transcription-polymerase chain reaction analysis and Western blotting analysis of unfertilized mature eggs proved the presence of Eavas transcripts and proteins, suggesting that Eavas may be a maternal factor. Vasa may represent a germ cell marker for corals, and would allow us to distinguish germ cells from somatic cells in coral bodies that have no distinct organs.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0041569PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3407244PMC
March 2013

Screening of new microsatellite DNA markers from the genome of Platyeriocheir formosa.

Int J Mol Sci 2012 9;13(5):5598-606. Epub 2012 May 9.

Department of Environmental Resources Management, Chia Nan University of Pharmacy and Science, Tainan 717, Taiwan; E-Mail:

The catadromous Platyeriocheir formosa is a crab endemic in Taiwan. To conserve P. formosa population diversity and ensure the sustainable use of this natural resource, we have developed new genetic markers, 17 polymorphic microsatellite loci, to promote the study of its population genetics in the future. In this study, more than 70 microsatellite sequences were found. Among these, 18 loci were selected to analyze the genetic diversity of P. formosa. With the exception of the Pfo15 locus, all of the remaining loci were polymorphic with allelic numbers ranging from 3-14. Heterozygosity within all 17 polymorphic loci ranged from 0.2-0.95 with an average of 0.55, which suggested that these loci are proper markers for studying population genetics. After we tested cross-specific amplification, eight and six primer sets could be successfully used for the amplification of microsatellite loci in morphologically similar Eriocheir sinensis and E. japonica, respectively; this suggests that they are useful markers for closely related species.
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http://dx.doi.org/10.3390/ijms13055598DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3382756PMC
August 2015

17,20β,21-Trihydroxy-4-pregnen-3-one biosynthesis and 20β-hydroxysteroid dehydrogenase expression during final oocyte maturation in the protandrous yellowfin porgy, Acanthopagrus latus.

Gen Comp Endocrinol 2012 Apr 2;176(2):192-200. Epub 2012 Feb 2.

Department of Aquaculture, National Kaohsiung Marine University, Kaohsiung 811, Taiwan.

The purpose of this study was to investigate the physiological maturation-inducing steroid (MIS) in the marine protandrous yellowfin porgy (Acanthopagrus latus). Female fish were injected with 2 doses of LHRH analog (10 and 40 μg per kg). Ovarian tissue was obtained at 6 h intervals for in vitro analysis of oocyte maturation. The most effective steroids for inducing in vitro maturation (germinal vesicle breakdown and GVBD) in cultured oocytes were 17,20β-dihydroxy-4-pregnen-3-one (17,20βP) and 17,20β,21-trihydroxy-4-pregnen-3-one (20β-S). 17,20βP was less potent than 20βS in inducing oocyte maturation. At higher concentrations, 11-deoxycortisol, 17α-hydroxy-progesterone, and 20β-21-dihydroxy-4-pregnen-3-one also significantly induced oocyte maturation. A tritiated precursor [(3)H]-pregnenolone, was cultured in vitro together with the maturing ovarian tissue. The tritiated metabolites were purified and identified by solvent extraction, HPLC, TLC, acetylation reaction and recrystallization. HPLC, TLC and recrystallization analysis showed that significant levels of tritiated 11-deoxycortisol (a precursor of 20β-S) and 20β-S, but not 17,20βP, were biosynthesized from [(3)H]-pregnenolone. Similar TLC profiles were obtained from the tritiated products that were isolated from the HPLC/TLC 20β-S fraction and standard 20β-S after the acetylation reaction. Constant specific radioactivity of tritiated 11-deoxycortisol and 20β-S but not 17,20βP by recrystallization was obtained in the tritiated metabolites isolated from HPLC and TLC fractions. The expression of 20β-hydroxysteroid dehydrogenase (20β-HSD) mRNA (a key enzyme that converts 11-deoxycortisol to 20β-S) was significantly increased in maturing ovarian tissue. This study provides the first evidence that 20β-S is converted from 11-deoxycortisol and is the possible MIS in yellowfin porgy.
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http://dx.doi.org/10.1016/j.ygcen.2012.01.010DOI Listing
April 2012

Differential regulation of the expression of cytochrome P450 aromatase, estrogen and androgen receptor subtypes in the brain-pituitary-ovarian axis of the Japanese eel (Anguilla japonica) reveals steroid dependent and independent mechanisms.

Gen Comp Endocrinol 2012 Jan 15;175(1):163-72. Epub 2011 Nov 15.

Department of Aquaculture, National Kaohsiung Marine University, Kaohsiung 811, Taiwan.

This study aimed at investigating the role of sexual steroids in the regulation of the expression of the single aromatase gene and steroid receptor subtypes in the brain-pituitary-ovarian axis of the Japanese eel. Unlike other teleosts, which possess duplicated genes for aromatase, cyp19a1a and cyp19a1b, expressed in the gonads and in the brain, respectively, eel species possess a single cyp19a1. Phylogenetic analysis indicated that eel brain/gonadal cyp19a1 branches at the basis of both teleost gonadal cyp19a1a and brain cyp19a1b clades. Female eels treated with catfish pituitary homogenate (CPH) to induce sexual maturation showed an increase in the expression of cyp19a1 and aromatase enzymatic activity in the brain and in the ovaries. Treatments with sex steroids (estradiol-17β, E(2) or testosterone, T) revealed that the increase in cyp19a1 expression in the brain may result from E(2)-specific induction. In contrast, the increase in cyp19a1 expression in the ovaries of CPH-treated eels is a result of steroid-independent control, probably from a direct effect of gonadotropins contained in the pituitary extract. Analysis of the expression of estrogen and androgen receptor subtypes, esr-α, esr-β, ar-α and ar-β, in eels treated with CPH or sex steroids revealed differential regulations. In CPH-treated eels, the expression of esr-α and ar-α was significantly increased in the brain, while the expression of ar-α and ar-β was increased in the ovaries. No change was observed in esr-β in any organ. Steroid treatments induced an upregulation by E(2) of esr-α, but not esr-β expression, in the brain, pituitary and ovaries, while no autoregulation by T of its own receptors could be observed. These results reveal both steroid-dependent and -independent mechanisms in the regulation of cyp19a1 and steroid receptor subtype expression in the eel.
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http://dx.doi.org/10.1016/j.ygcen.2011.11.005DOI Listing
January 2012

Testosterone improves the transition of primary oocytes in artificial maturation eels (Anguilla japonica) by altering ovarian PTEN expression.

Fish Physiol Biochem 2012 Jun 7;38(3):777-87. Epub 2011 Oct 7.

Department of Life Science, National University of Kaohsiung, No. 700 Kaohsiung University Road, Nan Tzu Dist., Kaohsiung, Taiwan.

In mammals, androgens appear to enhance the development of primary ovarian follicles, but PI3K (phosphoinositide 3-kinases) pathway is well recognized as one of the critical pathways in early follicular development. Roles of the PI3K were revealed by deletion of PTEN (phosphatase and tensin homolog on chromosome 10). PTEN is demonstrated to play an important role in the early stage of follicle development. In the Japanese eel, two forms of PTEN have been cloned, but what their functions on the development of early ovarian follicles are still not clear. The natural blockage and inducible of ovarian development was a benefit to address this question in the eel. Testosterone (T) shows to ameliorate the early ovarian development in the eel. The aims of this study were to elucidate the two forms of PTEN by cellular and physiological criteria and to study the effects of T on the ovarian PTEN production in the exogenous pituitary extracts-stimulated eel. Our results suggested that two forms of PTEN are existing in the Japanese eel, and eel ovarian development corresponded to the decrease in ovarian PTEN expression, vice versa. In addition, the supplement of T on eel early ovarian development can be attributed to its PTEN inhibitor role.
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http://dx.doi.org/10.1007/s10695-011-9560-6DOI Listing
June 2012

Investigating expression profiles of VEGF-Flk, and Angpt1 during development of gas glands in Japanese eel (Anguilla japonica).

Comp Biochem Physiol A Mol Integr Physiol 2010 Mar 3;155(3):350-60. Epub 2009 Dec 3.

Department of Life Science, National University of Kaohsiung No.700, Kaohsiung University Road, Nan Tzu Dist., 811 Kaohsiung, Taiwan.

Angiogenesis is a highly regulated physiological process in animals. Angiopoietin-1 (Angpt1) induces the signaling pathways related to vessel maturation in late phase of angiogenesis, which recruits pericyte supplements to make compact interaction with vessel tubes. There are only few data showing Angpt1 functions in fish. By using degenerate primers, partial sequence (812 bp) of Angpt1 was cloned from Anguilla japonica, and deduced amino acids showed 80% similarity to those of zebrafish. Physiological functions of cloned eel Angpt1 were studied by in vitro and in vivo manipulations with gas glands (rete mirabile) taken as the tested target tissues. RT-PCR and immunofluorescent staining techniques were performed to examine the expression patterns of Angpt1 as well as VEGF-Flk. Experimental data showed that, in vitro, bFGF, PPAR beta agonist, and estradiol affected Angpt1 expression; while cobalt ions, a VEGF expression-inducer, did not affect Angpt1 expression. In vivo, expression levels of Angpt1 increased with body growth. Furthermore, Angpt1 expressions increased significantly in the late stage of gas glands in the stimulated eel. Successive expression patterns on VEGF-Flk, and Angpt1 on different development stages of gas glands were observed. Our results suggest that the original function of angiopoietin-1 on angiogenesis is conserved during evolution.
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http://dx.doi.org/10.1016/j.cbpa.2009.11.021DOI Listing
March 2010

Sex differentiation and sex change in the protandrous black porgy, Acanthopagrus schlegeli.

Gen Comp Endocrinol 2010 Jul 14;167(3):417-21. Epub 2009 Nov 14.

Department of Aquaculture, National Taiwan Ocean University, Keelung 202, Taiwan.

Protandrous black porgy fish, Acanthopagrus schlegeli, have a striking life cycle with a male sex differentiation at the juvenile stage and male-to-female sex change at 3 years of age. We had characterized the sex differentiation and sex change in this species by the integrative approaches of histology, endocrine and molecular genetics. The fish differentiated in gonad at the age around 4-months and the gonad further developed with a bisexual gonad for almost for 3 years and sex change at 3 year of age. An antagonistic relationship in the testicular and ovarian tissues was found during the development of the gonadal tissue. Male- (such as sf-1, dmrt1, dax-1 and amh) and female- (such as wnt4, foxl2 and cyp19a1a) promoting genes were associated with testicular and ovarian development, respectively. During gonadal sex differentiation, steroidogenic pathway and estrogen signaling were also highly expressed in the brain. The increased expression of sf-1 and wnt4, cyp19a1a in ovarian tissue and decreased expression of dax-1 in the ovarian tissue may play important roles in sex change from a male-to-female. Endocrine factors such as estradiol and luteinizing hormone may also involve in the natural sex change. Estradiol induced the expression of female-promoting genes and resulted in the precocious sex change in black porgy. Our series of studies shed light on the sex differentiation and sex change in protandrous black porgy and other animals.
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http://dx.doi.org/10.1016/j.ygcen.2009.11.003DOI Listing
July 2010

Differential expression and regulation of gonadotropins and their receptors in the Japanese eel, Anguilla japonica.

Gen Comp Endocrinol 2007 Oct-Dec;154(1-3):161-73. Epub 2007 May 25.

Department of Aquaculture, National Kaohsiung Marine University, Kaohsiung 811, Taiwan.

Eel species have a striking life cycle with a blockade of puberty until the oceanic migration. We report the first molecular data on eel gonadotropin receptors. The partial sequences cloned covered two-third of the open reading frame and included most of the extracellular and transmembrane domains. Phylogenetic analysis partitioned the two eel gonadotropin receptors into the two teleost FSHR and LHR clusters, respectively. Real-time quantitative RT-PCR was used to quantify the expression of eel gonadotropins and their receptors. Similar levels of pituitary FSH-beta and LH-beta transcripts were found in the immature previtellogenic female eels. In contrast, ovarian FSHR mRNA level was at 100- to 185-fold higher than that of LHR. This revealed that FSHR rather LHR would mediate gonadotropin stimulation of the early stages of ovarian growth. Chronic treatment with fish pituitary homogenates, applied to induce eel sexual maturation, stimulated pituitary LH-beta but suppressed FSH-beta transcripts. In the ovaries, both FSHR and LHR mRNA were significantly increased in experimentally matured eels. Treatments with sexual steroids showed a stimulatory effect of estradiol-17beta (E(2)) on pituitary LH-beta mRNA levels, while FSH-beta transcripts were suppressed by E(2) or testosterone (T). In contrast, neither E(2) nor T-treatment had any significant effect on ovarian FSHR nor LHR transcripts. This suggests that steroid feedbacks may be responsible for the opposite regulation of pituitary gonadotropins in experimentally matured eels, but are not involved in the regulation of gonadotropin receptors. In conclusion, these are the first data on the sequence, expression and regulation of gonadotropin receptors in the eel. They provide new foundation for basic and applied research on eel reproduction.
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http://dx.doi.org/10.1016/j.ygcen.2007.05.026DOI Listing
December 2007

Hormones and reproduction in scleractinian corals.

Comp Biochem Physiol A Mol Integr Physiol 2006 Jul 20;144(3):247-53. Epub 2006 Feb 20.

National Museum of Marine Biology and Aquarium, Pingtung 944, Taiwan, ROC.

Most broadcast spawning scleractinian corals synchronously release gametes during a brief annual spawning period. In southern Taiwan, the mass spawning of scleractinians occurs in lunar mid-March. The exact cues triggering this annual phenomenon remain unclear. A scleractinian coral, Euphyllia ancora has been selected as a model for the hormones and reproduction studies. Testosterone (T) and estradiol (E2) in free and glucuronided forms were identified and consistently detected in coral polyps throughout the year. Peak levels of free E2, glucuronided E2 and T were obtained in the coral tissue just prior to spawning. The presence of specific aromatase activity was demonstrated in coral tissue. Higher concentrations of free E2 than glucuronided E2 were detected in the coral tissue throughout the year. In contrast, higher levels of glucuronided E2 than free E2 and glucuronided T were found in seawater during mass coral spawning. Furthermore, immunoreactivity and biological activity of immunoreactive gonadotropin-releasing hormone (irGnRH) was detected and quantified in coral tissue. Coral extracts (irGnRH) and mammalian (m)GnRH agonist had a similar dose-dependent effect on luteinizing hormone (LH) release in black porgy fish pituitary cells (in vitro). Peak levels of irGnRH were detected during the spawning period. In in vivo experiments, mGnRH agonist time- and dose-dependently stimulated aromatase activity, as well as the levels of T and E2 in free and glucuronided forms in coral. In conclusion, our data suggest that irGnRH and glucuronided E2 may play important roles in the control of reproduction and mass spawning in corals.
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http://dx.doi.org/10.1016/j.cbpa.2006.01.011DOI Listing
July 2006

The presence and ancestral role of gonadotropin-releasing hormone in the reproduction of scleractinian coral, Euphyllia ancora.

Endocrinology 2006 Jan 29;147(1):397-406. Epub 2005 Sep 29.

Institute of Marine Biology, Department of Aquaculture, National Taiwan Ocean University, Keelung 202, Taiwan.

The objectives of this study were to investigate the presence of immunoreactive GnRH (irGnRH) in scleractinian coral, Euphyllia ancora, study its seasonal variation, and evaluate its biological activity. irGnRH was detected and quantified in coral polyps. The biological activity of coral irGnRH was tested on pituitary cells from black porgy by evaluating its ability to stimulate LH release. Coral extracts (10(-9)-10(-5) M irGnRH) as well as mammalian (m) GnRH agonist (10(-10)-10(-6) M) had a similar dose-dependent effect on LH release. Furthermore, GnRH receptor antagonist dose-dependently inhibited the stimulation of LH release in response to coral extracts (10(-5) M irGnRH) and mGnRH agonist (10(-6) M). Peak levels of irGnRH (10-fold increase) were observed during the spawning period in a 3-yr investigation. Significantly higher aromatase activity and estradiol (E2) levels were also detected during the period of spawning compared with the nonreproductive season. In in vivo experiments, mGnRH agonist time- and dose-dependently stimulated aromatase activity as well as the concentrations of testosterone and E2 in free and glucuronided forms in coral. In conclusion, our data indicate that irGnRH does exist in coral, with its ability to stimulate LH release in fish. Seasonal variations of coral irGnRH, with a dramatic increase during the spawning period, concomitant to that in aromatase and E2, as well as the ability of mGnRH agonist to stimulate coral aromatase, steroidogenesis, and steroid glucuronization suggest that irGnRH plays an important role in the control of oocyte growth and mass spawning in corals.
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http://dx.doi.org/10.1210/en.2005-0584DOI Listing
January 2006

Current status of genetic and endocrine factors in the sex change of protandrous black porgy, Acanthopagrus schlegeli (Teleostean).

Ann N Y Acad Sci 2005 Apr;1040:206-14

Department of Aquaculture, National Taiwan Ocean University, Keelung, Taiwan.

Black porgy, Acanthopagrus schlegeli Bleeker, a marine protandrous hermaphrodite fish, is functionally male for the first 2 years of life, but begins to sexually change to female after the third year. Testicular tissue and ovarian tissue are separated by connective tissue in the bisexual gonad. This sex pattern provides a unique model to study the mechanism of sex change in fish. The annual profiles of plasma estradiol, vitellogenin, and 11-ketotestosterone concentrations in males were significantly different from those in the 3-year-old females. Oral administration of estradiol stimulated high levels of gonadal aromatase activity, plasma luteinizing hormone (LH) levels, and sex change in the 2-year-old fish. Oral administration with aromatase inhibitors for 1 year further blocked the natural sex change in 3-year-old black porgy and all fish became functional males. Transcripts of estrogen receptor (ER), androgen receptor, and gonadotropin receptors in the ovarian tissue of bisexual gonad were significantly less expressed than those in the bisexual testicular tissue. ER and aromatase transcripts were much higher in the vitellogenic ovary than those in the bisexual ovarian tissue. Plasma LH levels were higher in male fish than sex-changing fish during postspawning and nonspawning season in 2(+)-year-old black porgy. We are also conducting investigations on the role of the genetic factors (Dmrt 1, Sox 9, Sf-1, and Dax-1) in sex development and sex change. An endocrine mechanism of sex change in black porgy is proposed.
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http://dx.doi.org/10.1196/annals.1327.026DOI Listing
April 2005

Corals have already evolved the vertebrate-type hormone system in the sexual reproduction.

Fish Physiol Biochem 2005 Apr;31(2-3):111-5

National Museum of Marine Biology and Aquarium, Pingtung, 944, Taiwan.

Most broadcast spawning scleractinian corals synchronously release gametes during a brief annual spawning period. In southern Taiwan, the mass spawning of scleractinians occurs in lunar mid-March. Endocrine system has been proposed to play important roles in this annual phenomenon. A scleractinian coral, Euphyllia ancora has been selected as a model for the hormones and reproduction studies. We detected the presence of estradiol (E2), testosterone (T), glucuronided E2, glucuronided T, aromatase, immunoreactive (ir)GnRH in coral polyps E. ancora. Annual profiles of sex steroids, aromatase, and irGnRH have also been characterized. We found the parallel increases in irGnRH concentrations, aromatase activity and free E2 and glucuronided E2 concentrations at the time of coral mass spawning. The stimulation of mammalian (m)GnRH agonist in the increased aromatase activity and sex steroid concentrations was also observed in corals. Coral extracts (irGnRH) and mGnRH agonist had a similar dose-dependent effect on luteinizing hormone release in black porgy fish pituitary cells (in vitro). In conclusion, our data suggest that irGnRH and glucuronided E2 may play important roles in the control of reproduction and mass spawning in corals. Corals already evolved the vertebrate-type hormone system in the sexual reproduction.
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http://dx.doi.org/10.1007/s10695-006-7591-1DOI Listing
April 2005

Seasonal profiles of brain and pituitary gonadotropin-releasing hormone and plasma luteinizing hormone in relation to sex change of protandrous black porgy, Acanthopagrus schlegeli.

Biol Reprod 2005 Apr 15;72(4):922-31. Epub 2004 Dec 15.

Department of Aquaculture, National Taiwan Ocean University, Keelung 202, Taiwan.

Three molecular variants of GnRH in the brain (sbGnRH, sGnRH, and cGnRH-II) and two forms in the pituitary (sbGnRH and sGnRH) were detected in protandrous black porgy, Acanthopagrus schlegeli using chromatographic and immunological methods. In juvenile fish, brain sbGnRH, sGnRH, and cGnRH-II levels increased in May and reached their highest levels in July and August (the nonspawning season) and in January through March (the spawning season). In fish aged 1 yr and older, high levels of brain sbGnRH and sGnRH were detected in September, November, and February-March, but the levels of brain cGnRH-II remained constant. A gradual increase in pituitary sbGnRH was detected in juvenile fish from July to March. In fish aged 1+ yr, pituitary sbGnRH levels were high in September and March-May, but low in January-February. A close correlation between pituitary sbGnRH and plasma LH levels was found in juvenile fish and in those aged 1+ yr. In fish aged 2+ yr, significantly lower levels of plasma LH was detected during the nonspawning period in fish that changed sex compared with the fish that remained as males. Higher plasma LH levels were detected in the sex-changing fish from artificially sex-reversed female to male. FSH receptor and LH receptor transcripts were higher in bisexual testicular tissue than in ovarian tissue in 2+-yr-old fish. Direct effects of hCG on sex change were studied and the results show that exogenous hCG did not stimulate gonadal aromatase activity in 2+-yr-old fish. Therefore, it is suggested that high and basal levels of plasma LH during the nonspawning season correlate with the development of male and female gonad, respectively, in black porgy. This important role of the neuroendocrine system in sex change (for male direction) is proposed in hermaphroditic fish.
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http://dx.doi.org/10.1095/biolreprod.104.033159DOI Listing
April 2005

In vivo and in vitro sex steroids stimulate seabream gonadotropin-releasing hormone content and release in the protandrous black porgy, Acanthopagrus schlegeli.

Gen Comp Endocrinol 2004 Oct;139(1):12-9

National Museum of Marine Biology and Aquarium, Pintung 944, Taiwan, ROC.

The objective of the present study was to investigate the regulation of seabream gonadotropin-releasing hormone (sbGnRH) release using in vivo and in vitro approaches in the protandrous black porgy, Acanthopagrus schlegeli. Estradiol-17beta (E2), testosterone (T), and 11-ketotestosterone (11-KT) were found to significantly stimulate the increase of sbGnRH levels in pituitary of black porgy after 5-96 h of injection. An in vitro culture system using dispersed brain neurons was also developed to investigate the effects of various steroids on sbGnRH release. Different doses (10(-6) - 10(-12) M) of E2, T, 11-KT, and cortisol were applied during 6 h experiment. KCl stimulated sbGnRH release at a dose- and time-dependent manner. The concentration of sbGnRH increased 2-fold in the highest dose of KCl treatment compared to the control. Treatments with E2, T, 11-KT and cortisol significantly stimulated the release of sbGnRH from the cultured brain neurons. The concentration of sbGnRH in medium was increased by 2-, 1.9-, 2.1-, and 4.9-fold when treated with E2, T, 11-KT, and cortisol, respectively, as compared to the respective control. Cholesterol did not have any stimulatory effects in the release of sbGnRH. The results showed that sex steroids and cortisol had direct effect on brain neuronal cells stimulating the release of sbGnRH.
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http://dx.doi.org/10.1016/j.ygcen.2004.07.010DOI Listing
October 2004

Estradiol-17beta induced a reversible sex change in the fingerlings of protandrous black porgy, Acanthopagrus schlegeli Bleeker: the possible roles of luteinizing hormone in sex change.

Biol Reprod 2004 Oct 9;71(4):1270-8. Epub 2004 Jun 9.

National Museum of Marine Biology and Aquarium, Pintung 944, Taiwan.

The objectives of the present study were to investigate the effects of oral administration of estradiol-17beta (E(2)) on luteinizing hormone (LH) in plasma, aromatase activity in gonad, and sex change in the fingerlings of protandrous black porgy, Acanthopagus schlegeli Bleeker. The expression of estrogen receptor (ER) and androgen receptor (AR) transcripts in gonad was also analyzed. Undifferentiated (2-mo-old) black porgy were divided into two groups, one fed a control diet and the other a diet mixed with E(2) (6.0 mg/kg feed) for 5 mo. Fish treated with E(2) for 3 mo showed complete suppression of spermatogenesis and spermiation and induced sex change with primary oocytes. Aromatase activity in forebrain and midbrain was increased in the control in December-March (during the spawning season). E(2) stimulated aromatase activity in the brain. Higher gonadal aromatase activity in concordance with elevated levels of plasma LH was observed in the E(2) group compared with the control. After 2-mo of E(2) termination, regressed testicular tissue recovered and controlled females gradually reversed back to functional males in January and March. Plasma LH levels were higher in the E(2)-terminated group during the period of reversible sex change (from a controlled female to male) compared with the control. The expression of ER and AR transcripts was closely related to the development of testis and ovary. The data showed that E(2) induced a reversible sex change with high plasma LH. Increase of gonadal aromatase and decrease of ER/AR were associated with controlled sex change. Plasma LH levels were correlated with the conversion from a controlled female to male in black porgy.
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http://dx.doi.org/10.1095/biolreprod.104.030221DOI Listing
October 2004

Differential messenger RNA transcription of androgen receptor and estrogen receptor in gonad in relation to the sex change in protandrous black porgy, Acanthopagrus schlegeli.

Biol Reprod 2003 Aug 2;69(2):455-61. Epub 2003 Apr 2.

Department of Aquaculture, National Taiwan Ocean University, Keelung 202, Taiwan, Republic of China.

Black porgy, Acanthopagrus schlegeli Bleeker, is a marine protandrous hermaphrodite fish. All are functional males at 1-2 yr of age and then become either males or females at 3 yr of age. To study the process of sex change in this species, mRNA transcripts of two estrogen receptors (ERalpha and ERbeta) and an androgen receptor (AR) were monitored. An AR cDNA was cloned and characterized. ERalpha, ERbeta, and AR were differentially transcribed in bisexual testicular and ovarian tissue according to reverse transcription polymerase chain reaction (RT-PCR) and Southern analysis. A real-time quantification PCR analysis was further developed for the measurement of AR, ERalpha, and ERbeta transcripts. ERalpha and AR transcripts were significantly more plentiful in bisexual testis than in bisexual ovary in 1(+)- and 2(+)-yr-old fish. ERalpha, ERbeta, and AR transcripts decreased in the functional testis of 3-yr-old fish. Similar levels of ERbeta and AR were detected in the ovary of sex-changed females and in functional testis of 3-yr-old males. Significantly decreased AR transcripts were found in testicular tissue of bisexual and functional male and female gonads in 3-yr-old fish as compared with 1- and 2-yr-old fish. In contrast, increased ERalpha transcripts were detected in the bisexual ovary and sex-changed ovary of 3-yr-old fish as compared with the bisexual ovary of 1- and 2-yr-old fish. The data suggest a differential sensitivity in the bisexual testicular and ovarian tissue of black porgy.
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http://dx.doi.org/10.1095/biolreprod.102.015040DOI Listing
August 2003

Aromatase inhibitors block natural sex change and induce male function in the protandrous black porgy, Acanthopagrus schlegeli Bleeker: possible mechanism of natural sex change.

Biol Reprod 2002 Jun;66(6):1749-54

National Museum of Marine Biology and Aquarium, Taiwan, Republic of China.

The objectives of the present study were to investigate the effects of oral administration of aromatase inhibitors on sex change, milt volume, 11-ketotestosterone (11-KT), and LH in plasma; aromatase activity in gonad, pituitary, and brain in the protandrous fish, black porgy (Acanthopagus schlegeli Bleeker). Two-year-old functional male black porgy were divided into two groups; one was fed a control diet and the other was fed a diet mixed with aromatase inhibitors (AIs; fadrozole and 1,4,6-androstatriene-3,17-dione, each 10 mg/kg feed) for 8.5 mo. A significantly higher gonadosomatic index was observed in the AI group. Fish treated with AIs showed complete suppression of natural sex change. Significantly higher levels of plasma 11-KT, LH, and milt volume were shown in the AI group than the controls. Lower aromatase activity in the gonad, pituitary, forebrain, midbrain, and hindbrain in concordance with the suppression of sex change was observed in the AI group. The data show that aromatase is directly involved in the mechanism of natural sex change of protandrous black porgy. AIs also enhanced male function in concordance with the elevated plasma levels of 11-KT and spermiation in milt volume.
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http://dx.doi.org/10.1095/biolreprod66.6.1749DOI Listing
June 2002

Estradiol-17beta triggers luteinizing hormone release in the protandrous black porgy (Acanthopagrus schlegeli Bleeker) through multiple interactions with gonadotropin-releasing hormone control.

Biol Reprod 2002 Jan;66(1):251-7

Department of Aquaculture, National Taiwan Ocean University, Keelung 202, Taiwan, Republic of China.

We investigated the mechanism of estradiol-17beta (E2) action on stimulation of LH (=gonadotropin II) release in the black porgy fish (Acanthopagrus schlegeli Bleeker) using an in vivo approach and primary cultures of dispersed pituitary cells in vitro. In vivo, E2 but not androgens (testosterone [T] and 11-ketotestosterone [11-KT]) significantly stimulated plasma LH in a dose-dependent manner. Estradiol-17beta also increased brain content of seabream GnRH. GnRH antagonist prevented E2 stimulation of LH release in vivo, indicating that the effect of E2 on LH was mediated by GnRH. In vitro, sex steroids (E2, T, 11-KT) alone had no effect on basal LH release in the cultured pituitary cells, but GnRH significantly stimulated LH release. Estradiol-17beta potentiated GnRH stimulation of LH release, an effect that was inhibited by GnRH antagonist, and 11-KT, but not T, also potentiated GnRH stimulation of LH release. The potentiating effect of 11-KT on GnRH-induced LH release in vitro was stronger than that of E2. These data suggest that E2 triggers LH release in vivo by acting both on GnRH production at the hypothalamus and on GnRH action at the pituitary. In contrast, 11-KT may only stimulate GnRH action at the pituitary. The E2) induction of LH release, through multiple interactions with GnRH control, supports a possible central role of E2in the sex change observed in the protandrous black porgy.
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http://dx.doi.org/10.1095/biolreprod66.1.251DOI Listing
January 2002
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