De-Shou Wang

Southwest University in Chongqing, Ch’ung-ch’ing-shih, Chongqing Shi, China

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Publications (16)41.37 Total impact

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    ABSTRACT: Feminization of animals derived from areas polluted by endocrine disrupting chemicals (EDCs) has been observed in all classes of vertebrates. However, feminization of artificially reared offspring by feeding of specific living organisms has never been reported.
    Environmental research. 06/2014;
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    ABSTRACT: Females with differentiated ovary of a gonochoristic fish, Nile tilapia, were masculinized by long term treatment with an aromatase inhibitor (Fadrozole) in the present study. The reversed gonads developed into functional testes with fertile sperm. The longer the fish experienced sex differentiation, the longer treatment time was needed for successful sex reversal. Furthermore, Fadrozole induced sex reversal, designated as secondary sex reversal (SSR), was successfully rescued by supplement of exogenous 17β-estradiol. Gonadal histology, immunohistochemistry, transcriptome and serum steroid level were analyzed during SSR. The results indicated that spermatogonia were transformed from oogonia or germline stem cell-like cells distributed in germinal epithelium; while Leydig and Sertoli cells probably came from the interstitial cells and granulosa cells of the ovarian tissue, respectively. The transdifferentiation of somatic cells, as indicated by the appearance of Dmrt1 (pre-Sertoli cells) and Cyp11b2 (pre-Leydig cells) positive cells in the ovary, provided micro-niche for the transdifferentiation of germ cells. Decrease of serum 17β-estradiol was detected earlier than increase of serum 11-ketotestosterone, indicating decrease of estrogen was the cause while increase of androgen was the consequence of SSR. The sex reversed gonad displayed more similarity in morphology and histology with a testis while the global gene expression profiles remained closer to the female control. Detailed analysis indicated that transdifferentiation was driven by suppression of female pathway genes and activation of male pathway genes. In short, SSR provides a good model for study of sex reversal in teleosts, and for understanding of sex determination and differentiation in non-mammalian vertebrates.
    Endocrinology 01/2014; · 4.72 Impact Factor
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    ABSTRACT: The Nile tilapia is a cultured teleost fish in which males grow faster and larger than females, and mono-sex culturing could avoid unwanted reproduction during grow-out. Sex control in tilapia is an important issue in aquaculture. In the present study, randomly amplified polymorphic DNA (RAPD) and amplified fragment length polymorphism (AFLP) fingerprinting were used to screen pooled and individual DNA samples from XX, XY, and YY fish for sex-linked markers. Four sex-linked markers (Marker-1 from RAPD and Markers-2, -3, and -4 from AFLP) were obtained and mapped to LG23, a small chromosome, by sequence analysis and fluorescence in situ hybridization (FISH). In addition, a total of 32 pairs of primers were designed based on the sequences of scaffolds 7, 29, and 101 on LG23, and these were used to screen genetic differences between X and Y by PCR. One of these (Marker-5) produced a detectable difference between XX, XY, and YY individuals. Eight pairs of primers based on the sequence characterized amplified region (SCAR) were designed and successfully converted to SCAR markers, which were used to sex progeny from different crosses of known genotypes for validation. Subsequently, Markers-4 and -5 were used to sex eight populations of Nile tilapia collected from different fish farms in China, which gave concordance rates that ranged from 76 to 100%. Based on the recombination rate derived from the progeny of XX (♀) × XY (♂), Markers-1, -2, -3, -4, and -5 were estimated to be around 5, 3, 5, 2 and 0 cM away from the sex-determining locus (SD), respectively. Marker-5, which mapped close to the SD reported previously (Eshel et al., 2012), was used for selective breeding of genetic male tilapia (GMT).
    Aquaculture. 01/2014; 433:19–27.
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    ABSTRACT: Transcription activator-like effector nucleases (TALENs) are a powerful approach for targeted genome editing and have been proved to be effective in several organisms. In this study, we reported that TALENs can induce somatic mutations in Nile tilapia, an important species for worldwide aquaculture, with reliably high efficiency. Six pairs of TALENs were constructed to target genes related to sex differentiation, including dmrt1, foxl2, cyp19a1a, gsdf, igf3 and nrob1b, and all resulted in indel mutations with maximum efficiencies of up to 81% at the targeted loci. Effects of dmrt1 and foxl2 mutation on gonadal phenotype, sex differentiation and related gene expression were analyzed by histology, immunohistochemistry and real-time PCR. In Dmrt1 deficiency testes, phenotypes of significant testicular regression, including deformed efferent duct, degenerated spermatogonia or even a complete loss of germ cells, and proliferated steroidogenic cells, were observed. In addition, disruption of Dmrt1 in XY fish resulted in increased foxl2, cyp19a1a expression, serum estradiol-17β and 11-ketotestosterone levels. On the contrary, deficiency of Foxl2 in XX fish exhibited varying degrees of oocyte degeneration, significantly decreased aromatase gene expression and serum estradiol-17β levels. Some Foxl2 deficiency fish even exhibited complete sex reversal with high expression level of Dmrt1 and Cyp11b2. Furthermore, disruption of Cyp19a1a in XX fish led to partial sex reversal with Dmrt1 and Cyp11b2 expression. Taken together, our data demonstrated that TALENs are an effective tool for targeted gene editing in tilapia genome. Foxl2 and Dmrt1 play antagonistic roles in sex differentiation in Nile tilapia via regulating cyp19a1a expression and estrogen production.
    Endocrinology 10/2013; · 4.72 Impact Factor
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    ABSTRACT: Fibroblast growth factors (FGFs) have been proved to participate in a wide variety of processes, including growth, differentiation, cell proliferation, migration, sex determination and sex differentiation. The roles of FGF9/16/20 subfamily members in the gonadal development of teleost fish have not yet been reported. Three FGFs (16, 20a and 20b) of the FGF9/16/20 subfamily were cloned from the Nile tilapia by RT-PCR and RACE. Phylogenetic, bioinformatic and syntenic analyses demonstrated that these cloned FGFs are genuine FGF16, 20a and 20b. Our analyses further supported the non-existence of FGF9 ortholog and the existence of two FGF20 paralogs in teleost genomes. Tissue distribution analysis by RT-PCR demonstrated that FGF16 was expressed in a wide range of tissues including the testis and ovary, FGF20b in the brain, pituitary, intestine and ovary, but not in the testis, while FGF20a in the brain, pituitary and spleen, but not in the gonad. These results were consistent with the Northern blot analysis. The expression profiles of FGF16 and FGF20b during normal and sex reversed gonadal development were investigated by real-time PCR. Both showed much higher expression in the XX ovary and 17 beta-estradiol induced XY ovary compared with the XY testis and fadrozole and tamoxifen induced XX testis, with the highest in both sexes at 120 dah. Strong signals of FGF16 and FGF20b were detected in phase II oocytes by in situ hybridization. These data suggest that FGF9/16/20 subfamily is involved in the early oocyte development of the female.
    Fish Physiology and Biochemistry 03/2012; 38(5):1427-39. · 1.55 Impact Factor
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    ABSTRACT: P450 11beta-hydroxylase, encoded by P450(11beta) gene, is a key mitochondrial enzyme to produce 11beta-hydroxy testosterone, substrate for the production of 11-ketotestosterone (11-KT), which has been shown to be potent androgen in several fish species. In the present work, two alternative splicing isoforms i.e. P450(11beta)-1 and P450(11beta)-2 cDNAs were cloned from the Nile tilapia, Oreochromis niloticus. They were 1614 and 1227bp in length with open reading frames encoding proteins of 537 and 408 amino acids, respectively. In contrast to P450(11beta)-1, which derived from 9 exons of the P450(11beta) gene, the 7th and 8th exons were absent in P450(11beta)-2. Tilapia P450(11beta)-1 shares the highest homology with that of medaka, Oryzias latipes. Expressions of P450(11beta)-1 and -2 were detected in the kidney and head kidney of both sexes, and in the testis but not in the ovary, with P450(11beta)-2 lower than P450(11beta)-1. Ontogenic expressions of both isoforms were detected in testis from 50dah onwards. P450(11beta)-1 and -2 were strongly expressed in sex reversed XX testis after fadrozole and tamoxifen treatment, but completely inhibited in 17beta-estradiol induced XY ovary. The existence of two alternatively spliced isoforms and the sexual dimorphic expression of P450(11beta)s were further confirmed by Northern blot. Strong expression signals in Leydig cells and weak signals in spermatogonia were detected by in situ hybridization and immunohistochemistry. Taken together, our data suggest a role for P450(11beta) in the spermatogenesis of tilapia through the production of 11-KT in testis, in addition to cortisol production in head kidney.
    General and Comparative Endocrinology 07/2009; 165(1):34-41. · 2.82 Impact Factor
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    ABSTRACT: Two types of thrombospondin-1 (named TSP-1a and TSP-1b) were cloned from two species of teleosts, the Nile tilapia and medaka. Phylogenetic analysis of these TSP-1 sequences, together with those available from other vertebrates further demonstrated that two types of TSP-1 exist only in teleosts, extending the finding in fugu and tetraodon to two additional fish species. The expression of both genes was examined using tilapia at various developmental stages. Tilapia TSP-1a and TSP-1b were each expressed in a wide range of tissues examined. The early expression of TSP-1b in both XX and XY gonads from 5dah (day after hatching) onwards suggested an important role in the formation of gonads, while the expression of TSP-1a only in ovaries during later stages of development (from 120dah onwards) may suggest that TSP-1a is involved in oogenesis. During the 14-day spawning cycle, the expression of both types of TSP-1 exhibited distinct peaks at day 5 (peak of vitellogenesis) and day 12 (oocyte maturation). In situ hybridization analyses revealed differential expression, with TSP-1a occurring in granulosa cells and TSP-1b in theca cells. Furthermore, both TSP-1a and -1b were expressed in skeletal tissues but with clear temporal and spatial differences. In contrast, only TSP-1b was found in the myosepta. The positive signals of both TSP-1a and TSP-1b were also detected in the heart and spleen, and TSP-1a in brain and intestine by both RT-PCR and in situ hybridization.
    Gene Expression Patterns 07/2009; 9(6):436-43. · 1.64 Impact Factor
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    ABSTRACT: Distinct from the conventional IGFs (IGF-1 and IGF-2), here we report the identification of a novel IGF (herein called IGF-3) encoded by a separate gene from teleost species. The IGF-3 cDNA sequences were cloned from tilapia and zebrafish, and predicted from the medaka genome and EST databases. Similar to IGF-1 and IGF-2, IGF-3 is also comprised of five domains (B, C, A, D, E) with a similar tertiary protein structure, despite a low sequence homology among them. Phylogenetic analysis reveals that the IGF-3 sequences from different teleosts cluster to form a distinctive clade separate from IGF-1 and IGF-2. The expression of this novel IGF-3 is gonad-specific and starts early in fish development. In situ hybridization revealed that IGF-3 is expressed in the somatic cells and later in granulosa cells of the ovary, and in the interstitial cells of the testis. These findings highlight the importance of this novel IGF in teleost gonadal development and reproduction.
    Biochemical and Biophysical Research Communications 04/2008; 367(2):336-41. · 2.41 Impact Factor
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    ABSTRACT: The Nile tilapia, a gonochoristic teleost fish with an XX/XY sex-determining system, provides an excellent model for studying gonadal sex differentiation because genetic all-females and all-males are available. In this study, we used quantitative real-time RT-PCR to determine the precise timing of the gonadal expression of 17 genes thought to be associated with gonadal sex differentiation in vertebrates. Gonads were isolated from all-female and all-male tilapia before (5-15 days after hatching [dah]) and after (25-70 dah) morphological sex differentiation. The transcript of aromatase (cyp19a1a), an enzyme responsible for producing estradiol-17beta, was expressed only in XX gonads at 5 dah, with a marked elevation in expression thereafter. In contrast, mRNA expression of steroid 11beta-hydroxylase (cyp11b2), an enzyme responsible for the synthesis of 11-ketotestosterone (11-KT, a potent androgen in fish), was found in XY gonads from 35 dah only. These results, combined with the presence of transcripts for other steroidogenic enzymes and estrogen receptors in XX gonads at 5-7 dah, are consistent with our earlier suggestion that estradiol-17beta plays a critical role in ovarian differentiation in tilapia, whereas a role for 11-KT in testicular differentiation is questionable. A close relationship between the expression of foxl2, but not nr5a1 (Ad4BP/SF-1), and that of cyp19a1a in XX gonads suggests an important role for Foxl2 in the transcriptional regulation of cyp19a1a. Dmrt1 exhibited a male-specific expression in XY gonads from 6 dah onward, suggesting an important role for Dmrt1 in testicular differentiation. Sox9 and amh (anti-Mullerian hormone) showed a testis-specific expression, being evident only in the later stages of testicular differentiation. It is concluded that the sex-specific expression of foxl2 and cyp19a1a in XX gonads and dmrt1 in XY gonads during early gonadal differentiation (5-6 dah) is critical for undifferentiated gonads to differentiate into either the ovary or testis in the Nile tilapia.
    Biology of Reproduction 03/2008; 78(2):333-41. · 4.03 Impact Factor
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    ABSTRACT: Two isoforms of Vasa cDNA, derived from the 5′alternative splicing of the same gene, were isolated and characterized in Southern catfish, Silurus meridionalis, by reverse transcription polymerase chain reaction (RT-PCR) and rapid amplification of cDNA ends (RACE) methods. Analysis of the nucleotide sequences revealed that the full length cDNA of Southern catfish Vasa (scVasa) comprises 2525 base pairs (bp) with an open reading frame (ORF) of 1989 bp, encoding 662 amino acids, while that of Vasa short form (scVasa-s) comprises 2438 bp with an ORF of 1926 bp, encoding 641 amino acids. Except the difference in 5′-untranslated region, scVasa-s also lacks a part of the 5′-ORF region found in the scVasa. Both of the two deduced amino acid sequences contain all the eight conserved motifs characteristic to the DEAD-box protein family and four arginine-glycine-glycine motifs unique to Vasa proteins. scVasa showed the highest similarity to Vasa homolog of giebel carp (73.3%). Tissue distribution analysis by RT-PCR revealed that these two isoforms were exclusively expressed in the gonads of both sexes. In adult fish, scVasa was found to be mainly expressed in the primary oocytes at phase Ⅰ and Ⅱ in the ovary while in the spermatogonia and primary spermatocytes in the testis by in situ hybridization. Semi-quantitative RT-PCR analysis showed that the expressions of both scVasa isoforms were much higher in ovarian recrudescent stage (mainly with phase Ⅱ oocytes) than in vitellogenic stage (mainly with phase Ⅲ and Ⅳ oocytes) [Acta Zoologica Sinica 54(6):1051–1060, 2008].
    Acta Zoologica Sinica. 01/2008;
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    ABSTRACT: Recently we reported the isolation of two types of cytochrome P450c17s (steroid 17alpha-hydroxylase/C17, 20 lyase) encoded by two different genes, from genomes of teleost fish. In this study, we characterized the expression profile, enzymatic activity and transcriptional regulation of P450c17-I and -II in the medaka ovary. Similar to tilapia, medaka P450c17-I possessed both hydroxylase and lyase activities, while P450c17-II possessed only the hydroxylase activity. In situ hybridization and gene expression profiles during 48h prior to spawning indicated that P450c17-I is responsible for the production of estradiol-17beta during oocyte growth, while P450c17-II for the production of 17alpha, 20beta-dihydroxy-4-pregnen-3-one during oocyte maturation and cortisol production in the head kidney. Luciferase assays and expression profiles of transcription factors as revealed by real time PCR suggested that P450c17-I and -II expression are tightly controlled by Ad4BP/SF-1, Lrh-1, Foxl2, and Dax1 during the 48 h prior to spawning.
    Biochemical and Biophysical Research Communications 11/2007; 362(3):619-25. · 2.41 Impact Factor
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    ABSTRACT: Dax1 is a member of an unusual orphan nuclear receptor family, and is known to regulate P450arom in mammals and is involved in sex differentiation in some vertebrates. To investigate whether Dax1 is involved in the regulation of the steroidogenic pathway for estrogen biosynthesis in medaka ovarian follicles, we isolated Dax1 cDNA from adult medaka ovaries and analyzed its expression pattern in medaka gonads. In adult ovaries, Dax1 mRNA was detected only in postvitellogenic follicles and was not detected in previtellogenic and vitellogenic follicles. In adult testis, Dax1 mRNA was not detected. We compared the expression pattern of Dax1 with that of Foxl2, Ad4BP/Sf-1, P450c17, and P450arom by in situ hybridization using adjacent sections. In contrast to Dax1 expression, these genes were co-expressed in vitellogenic follicles but were not detected in postvitellogenic follicles. Thus, in medaka ovarian follicles, Dax1 did not show any overlapping expression patterns against Foxl2, Ad4BP/Sf-1, P450c17, and P450arom. Moreover, co-transfection experiments demonstrated that Dax1 inhibits Ad4BP/Sf-1- and Foxl2-mediated P450arom expression. On the other hand, during early sex differentiation, Dax1 mRNA was not detected in both males and females. Our results suggest that Dax1 down-regulates Ad4BP/Sf-1- and Foxl2-mediated P450arom expression in medaka ovarian follicles.
    Molecular Reproduction and Development 11/2007; 74(10):1239-46. · 2.81 Impact Factor
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    ABSTRACT: Cytochrome P450c17 is the single enzyme that mediates the 17 alpha-hydroxylase and 17, 20 lyase activities during the biosynthesis of steroid hormones in the gonads and adrenal gland. However, the mechanism underlying its dual action continues to be a controversy in the field of steroidogenesis in fish. In an attempt to resolve this issue, we identified a novel type of P450c17 (P450c17-II) by an in silico analysis from the genomes of six fish species. We cloned P450c17-II from tilapia and medaka, and comparison with the conventional P450c17-I revealed that they differ in gene structure and enzymatic activity. Enzymatic assays by thin-layer chromatography revealed that P450c17-II possesses only the 17 alpha-hydroxylase activity without any 17, 20 lyase activity, unlike P450c17-I, which has both these activities. In testis, both P450c17-I and -II express in the interstitial cells. Remarkable differences, revealed by in situ hybridization, in the expression patterns of the P450c17-I and -II in the ovary and head kidney of tilapia during various stages of development strongly suggest that P450c17-I is responsible for the synthesis of estradiol-17beta in the ovary, whereas P450c17-II is required for the production of C21 steroids such as cortisol in the head kidney. More interestingly, a temporally controlled switching is observable in the expression of these two genes during the steroidogenic shift from estradiol-17beta to the C21 steroid, 17 alpha, 20 beta-dihydroxy-4-pregnen-3-one (maturation-inducing hormone of fish oocytes) in the fish ovary, revealing a role for P450c17-II in the production of hormones that induce oocyte maturation in fish.
    Endocrinology 10/2007; 148(9):4282-91. · 4.72 Impact Factor
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    ABSTRACT: Increasing evidence suggests the crucial role of estrogen in ovarian differentiation of nonmammalian vertebrates including fish. The present study has investigated the plausible role of Foxl2 in ovarian differentiation through transcriptional regulation of aromatase gene, using monosex fry of tilapia. Foxl2 expression is sexually dimorphic, like Cyp19a1, colocalizing with Cyp19a1 and Ad4BP/SF-1 in the stromal cells and interstitial cells in gonads of normal XX and sex-reversed XY fish, before the occurrence of morphological sex differentiation. Under in vitro conditions, Foxl2 binds to the sequence ACAAATA in the promoter region of the Cyp19a1 gene directly through its forkhead domain and activates the transcription of Cyp19a1 with its C terminus. Foxl2 can also interact through the forkhead domain with the ligand-binding domain of Ad4BP/SF-1 to form a heterodimer and enhance the Ad4BP/SF-1 mediated Cyp19a1 transcription. Disruption of endogenous Foxl2 in XX tilapia by overexpression of its dominant negative mutant (M3) induces varying degrees of testicular development with occasional sex reversal from ovary to testis. Such fish display reduced expression of Cyp19a1 as well as a drop in the serum levels of 17beta-estradiol and 11-ketotestosterone. Although the XY fish with wild-type tilapia Foxl2 (tFoxl2) overexpression never exhibited a complete sex reversal, there were significant structural changes, such as tissue degeneration, somatic cell proliferation, and induction of aromatase, with increased serum levels of 17beta-estradiol and 11-ketotestosterone. Altogether, these results suggest that Foxl2 plays a decisive role in the ovarian differentiation of the Nile tilapia by regulating aromatase expression and possibly the entire steroidogenic pathway.
    Molecular Endocrinology 04/2007; 21(3):712-25. · 4.75 Impact Factor
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    ABSTRACT: Foxl2 is a member of the winged helix/forkhead family of transcription factors and is known to be involved in ovarian development in some vertebrates. To address the role of Foxl2 in ovarian differentiation in medaka, we isolated Foxl2 cDNA and analyzed its expression patterns during sex differentiation. Expression of Foxl2 started in somatic cells surrounding germ cells in XX gonads, just after initiation of ovarian differentiation, and was maintained in granulosa cells throughout ovarian development. In the adult ovary, Foxl2 was expressed in previtellogenic and vitellogenic follicles, but expression ceased in postvitellogenic follicles. In contrast, Foxl2 mRNA could not be detected in testes. In addition, Foxl2 and aromatase mRNAs were co-localized in some somatic cells located on the ventral side of developing XX gonads. Our results suggested that Foxl2 was not involved in ovarian determination, but was involved in differentiation of granulosa cells in medaka.
    Biochemical and Biophysical Research Communications 06/2006; 344(1):353-61. · 2.41 Impact Factor
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    ABSTRACT: Piscine DAX1 and SHP cDNAs with an open reading frame encoding 296 and 258 amino acid residues, respectively, as well as SHP partial gene fragment, were cloned from Nile tilapia. Phylogenetic analyses of DAX1s, SHPs, and homologous EST fragments indicate that DAX1 and SHP are conserved in gene structure and are present throughout vertebrates. A single band of approximately 1.4kb for DAX1 and of approximately 1.2kb for SHP was detected in the Northern blot analysis. Tissue distribution analysis by RT-PCR showed that fish DAX1 and SHP mRNAs are widely expressed in adult tissues, with the most abundant expression in gonads and liver, respectively. DAX1 and SHP were also detected in gonads of both sexes at 5-90 days after hatching (dah). However, the expression of DAX1 is weak at 5 and 10dah and then significantly up-regulated between 10 and 15dah, whereas the expression of SHP is moderate and consistent during the ontogeny.
    Biochemical and Biophysical Research Communications 10/2002; 297(3):632-40. · 2.41 Impact Factor