101
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Zhao Y, Xie L, Yan Y. Microcystin-LR impairs zebrafish reproduction by affecting oogenesis and endocrine system. CHEMOSPHERE 2015; 120:115-122. [PMID: 25014902 DOI: 10.1016/j.chemosphere.2014.06.028] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2013] [Revised: 06/07/2014] [Accepted: 06/10/2014] [Indexed: 06/03/2023]
Abstract
Previous studies have shown that microcystins (MCs) are able to exert negative effects on the reproductive system of fish. However, few data are actually available on the effects of MC-LR on the reproductive system of female fish. In the present study, female zebrafish were exposed to 2, 10, and 50 μg L(-1) of MC-LR for 21 d, and its effects on oogenesis, sex hormones, transcription of genes on the hypothalamic-pituitary-gonad (HPG) axis, and reproduction were investigated for the first time. It was observed that egg production significantly declined at ⩾ 10 μg L(-1) MC-LR. MC-LR exposure to zebrafish increased the concentrations of 17β-estradiol (E2) and vitellogenin (VTG) at 10 μg L(-1) level, whereas concentrations of E2, VTG and testosterone declined at 50 μg L(-1) MC-LR. The transcriptions of steroidogenic pathway gene (cyp19a, cyp19b, 17βhsd, cyp17 and hmgra) changed as well after the exposure and corresponded well with the alterations of hormone levels. A number of intra- and extra-ovarian factors, such as gnrh3, gnrhr1, fshβ, fshr, lhr, bmp15, mrpβ, ptgs2 and vtg1 which regulate oogenesis, were significantly changed with a different dose-related effect. Moreover, MC-LR exposure to female zebrafish resulted in decreased fertilization and hatching rates, and may suggest the possibility of trans-generational effects of MC-LR exposure. The results demonstrate that MC-LR could modulate endocrine function and oogenesis, eventually leading to disruption of reproductive performance in female zebrafish. These data suggest there is a risk for aquatic population living in MC polluted areas.
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Affiliation(s)
- Yanyan Zhao
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, 73 East Beijing Road, Nanjing 210008, PR China
| | - Liqiang Xie
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, 73 East Beijing Road, Nanjing 210008, PR China.
| | - Yunjun Yan
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan 430074, PR China.
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102
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Lima D, Castro LFC, Coelho I, Lacerda R, Gesto M, Soares J, André A, Capela R, Torres T, Carvalho AP, Santos MM. Effects of Tributyltin and Other Retinoid Receptor Agonists in Reproductive-Related Endpoints in the Zebrafish (Danio rerio). JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2015; 78:747-60. [PMID: 26090559 DOI: 10.1080/15287394.2015.1028301] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Both field and experimental data examined the influence of exposure to environmental contaminant tributyltin (TBT) on marine organisms. Although most attention focused on the imposex phenomenon in gastropods, adverse effects were also observed in other taxonomic groups. It has been shown that imposex induction involves modulation of retinoid signaling in gastropods. Whether TBT influences similar pathways in fish is yet to be addressed. In this study, larvae of the model teleost Danio rerio were exposed to natural retinoids, all-trans-retinoic acid, 9-cis-retinoic acid, and all-trans-retinol, as well as to the RXR synthetic pan-agonist methoprene acid (MA) and to TBT. Larvae were exposed to TBT from 5 days post fertilization (dpf) to adulthood, and reproductive capacity was assessed and correlated with mode of action. TBT significantly decreased fecundity at environmentally relevant levels at 1 μg TBT Sn/g in diet. Interestingly, in contrast to previous reports, TBT altered zebrafish sex ratio toward females, whereas MA exposure biased sex toward males. Since fecundity was significantly altered in the TBT-exposed group with up to 62% decrease, the potentially affected pathways were investigated. Significant downregulation was observed in brain mRNA levels of aromatase b (CYP19a1b) in females and peroxisome proliferator activated receptor gamma (PPARg) in both males and females, suggesting an involvement of these pathways in reproductive impairment associated with TBT.
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Affiliation(s)
- Daniela Lima
- a Interdisciplinary Centre for Marine and Environmental Research (CIIMAR), CIMAR Associate Laboratory , University of Porto Porto , Portugal
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103
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Baumann L, Knörr S, Keiter S, Nagel T, Rehberger K, Volz S, Oberrauch S, Schiller V, Fenske M, Holbech H, Segner H, Braunbeck T. Persistence of endocrine disruption in zebrafish (Danio rerio) after discontinued exposure to the androgen 17β-trenbolone. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2014; 33:2488-2496. [PMID: 25070268 DOI: 10.1002/etc.2698] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Revised: 06/08/2014] [Accepted: 07/24/2014] [Indexed: 06/03/2023]
Abstract
The aim of the present study was to investigate the effects of the androgenic endocrine disruptor 17β-trenbolone on the sexual development of zebrafish (Danio rerio) with special emphasis on the question of whether adverse outcomes of developmental exposure are reversible or persistent. An exposure scenario including a recovery phase was chosen to assess the potential reversibility of androgenic effects. Zebrafish were exposed to environmentally relevant concentrations of 17β-trenbolone (1 ng/L-30 ng/L) from fertilization until completion of gonad sexual differentiation (60 d posthatch). Thereafter, exposure was either followed by 40 d of recovery in clean water or continued until 100 d posthatch, the age when zebrafish start being able to reproduce. Fish exposed for 100 d to 10 ng/L or 30 ng/L 17β-trenbolone were masculinized at different biological effect levels, as evidenced from a concentration-dependent shift of the sex ratio toward males as well as a significantly increased maturity of testes. Gonad morphological masculinization occurred in parallel with decreased vitellogenin concentrations in both sexes. Changes of brain aromatase (cyp19b) mRNA expression showed no consistent trend with respect to either exposure duration or concentration. Gonad morphological masculinization as well as the decrease of vitellogenin persisted after depuration over 40 d in clean water. This lack of recovery suggests that androgenic effects on sexual development of zebrafish are irreversible.
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Affiliation(s)
- Lisa Baumann
- Centre for Fish and Wildlife Health, University of Bern, Bern, Switzerland; Aquatic Ecology and Toxicology Section, Centre for Organismal Studies, University of Heidelberg, Heidelberg, Germany
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104
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Schiller V, Zhang X, Hecker M, Schäfers C, Fischer R, Fenske M. Species-specific considerations in using the fish embryo test as an alternative to identify endocrine disruption. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2014; 155:62-72. [PMID: 24992288 DOI: 10.1016/j.aquatox.2014.06.005] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Revised: 06/03/2014] [Accepted: 06/13/2014] [Indexed: 06/03/2023]
Abstract
A number of regulations have been implemented that aim to control the release of potentially adverse endocrine disrupters into the aquatic environment based on evidence from laboratory studies. Currently, such studies rely on testing approaches with adult fish because reliable alternatives have not been validated so far. Fish embryo tests have been proposed as such an alternative, and here we compared two species (medaka and zebrafish) to determine their suitability for the assessment of substances with estrogenic and anti-androgenic activity. Changes in gene expression (in here the phrase gene expression is used synonymously to gene transcription, although it is acknowledged that gene expression is additionally regulated, e.g., by translation and protein stability) patterns between the two species were compared in short term embryo exposure tests (medaka: 7-day post fertilization [dpf]; zebrafish: 48 and 96h post fertilization [hpf]) by using relative quantitative real-time RT-PCR. The tested genes were related to the hypothalamic-gonadal-axis and early steroidogenesis. Test chemicals included 17α-ethinylestradiol and flutamide as estrogenic and anti-androgenic reference compounds, respectively, as well as five additional substances with endocrine activities, namely bisphenol A, genistein, prochloraz, linuron and propanil. Estrogenic responses were comparable in 7-dpf medaka and 48/96-hpf zebrafish embryos and included transcriptional upregulation of aromatase b, vitellogenin 1 as well as steroidogenic genes, suggesting that both species reliably detected exposure to estrogenic compounds. However, anti-androgenic responses differed between the two species, with each species providing specific information concerning the mechanism of anti-androgenic disruption in fish embryos. Although small but significant changes in the expression of selected genes was observed in 48-hpf zebrafish embryos, exposure prolonged to 96hpf was necessary to obtain a response indicative of anti-androgenic activity. In contrast, for medaka clear anti-androgenic response, e.g. transcriptional downregulation of 11β-hydroxylase, 3β-hydroxysteroid-dehydrogenase, gonadotropin-releasing hormone receptor 2, was already observed at the pre-hatch stage. Together, this data suggests that medaka and zebrafish embryos would provide a beneficial alternative testing platform for endocrine disruption that involves additive information on interspecies and exposure time variability when using both species.
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Affiliation(s)
- Viktoria Schiller
- Fraunhofer Institute for Molecular Biology and Applied Ecology, 52074 Aachen, Germany.
| | - Xiaowei Zhang
- Toxicology Centre University of Saskatchewan, 44 Campus Drive Saskatoon, Saskatchewan, Canada
| | - Markus Hecker
- Toxicology Centre University of Saskatchewan, 44 Campus Drive Saskatoon, Saskatchewan, Canada
| | - Christoph Schäfers
- Fraunhofer Institute for Molecular Biology and Applied Ecology, 57392 Schmallenberg, Germany
| | - Rainer Fischer
- Fraunhofer Institute for Molecular Biology and Applied Ecology, 52074 Aachen, Germany
| | - Martina Fenske
- Fraunhofer Institute for Molecular Biology and Applied Ecology, 52074 Aachen, Germany
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105
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Qin F, Wang X, Liu S, Zheng Y, Li M, Zhang Y, Wang Z. Gene expression profiling of key genes in hypothalamus-pituitary-gonad axis of rare minnow Gobiocypris rarus in response to EE2. Gene 2014; 552:8-17. [PMID: 25194895 DOI: 10.1016/j.gene.2014.09.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Revised: 08/28/2014] [Accepted: 09/03/2014] [Indexed: 11/18/2022]
Abstract
The 17α-ethinylestradiol (EE2), which could induce estrogenic effects, is found in different aquatic systems. The current study aimed to assess in vivo effects of short-term EE2 exposure on the transcriptional activity of genes in the brain and gonad tissues in order to characterize the mode of action of EE2 on the hypothalamus-pituitary-gonad axis in rare minnow (Gobiocypris rarus). The full length cDNAs of fshβ, lhβ, fshr and lhr were first characterized in G. rarus. The homology and phylogenetic analyses of the amino acid sequences revealed that these four genes share high identity in cyprinid fish. The tissue distribution analysis by qRT-PCR showed that fshβ and lhβ were mainly expressed in the brain and fshr and lhr were mainly expressed in gonads. Adult G. rarus was exposed to EE2 at 1, 5, 25 and 125 ng/L for 3 and 6 days and the expression of brain cyp19a1b, fshβ and lhβ, estrogen receptors (esr1, esr2a, and esr2b) and gonadal fshr, lhr and cyp19a1a were assessed. Cyp19a1b was significantly up-regulated in the brains of female exposed to EE2 at 1-125 ng/L for 6 days. The brain lhβ, but not fshβ was strongly suppressed in most EE2 exposure groups of both sexes. The brain esr2b was inhibited in both sexes exposed to EE2 at all of the four concentrations for 6 days. Esr2a was up-regulated in the females by 6-day EE2 treatment at 1 and 25 ng/L. The high responsiveness of brain lhβ and esr2s to EE2 and their significant correlation in both sexes suggested that the transcriptional activity of Esr2s could play key roles in modulation of lhβ expression via direct action on gonadotropic cells in response to EE2. In gonads, fshr was strongly inhibited by EE2 in males, while lhr was significantly stimulated by EE2 in females. Cyp19a1a was inhibited by EE2 in both sexes. The positive correlations of gene expressions of both fshr and lhr with cyp19a1a in testes suggest that the suppression of 17α-estradiol (E2) synthesis in testis by exogenous estrogen could mediate via both Fsh/Fshr and Lh/Lhr signaling in male G. rarus.
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Affiliation(s)
- Fang Qin
- College of Animal Science and Technology, Northwest A&F University, Shaanxi Key Laboratory of Molecular Biology for Agriculture, Yangling, Shaanxi 712100, China
| | - Xueqin Wang
- College of Animal Science and Technology, Northwest A&F University, Shaanxi Key Laboratory of Molecular Biology for Agriculture, Yangling, Shaanxi 712100, China
| | - Shaozhen Liu
- College of Animal Science and Technology, Northwest A&F University, Shaanxi Key Laboratory of Molecular Biology for Agriculture, Yangling, Shaanxi 712100, China
| | - Yao Zheng
- College of Animal Science and Technology, Northwest A&F University, Shaanxi Key Laboratory of Molecular Biology for Agriculture, Yangling, Shaanxi 712100, China
| | - Meng Li
- College of Animal Science and Technology, Northwest A&F University, Shaanxi Key Laboratory of Molecular Biology for Agriculture, Yangling, Shaanxi 712100, China
| | - Yingying Zhang
- College of Animal Science and Technology, Northwest A&F University, Shaanxi Key Laboratory of Molecular Biology for Agriculture, Yangling, Shaanxi 712100, China
| | - Zaizhao Wang
- College of Animal Science and Technology, Northwest A&F University, Shaanxi Key Laboratory of Molecular Biology for Agriculture, Yangling, Shaanxi 712100, China.
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106
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Reyhanian Caspillo N, Volkova K, Hallgren S, Olsson PE, Porsch-Hällström I. Short-term treatment of adult male zebrafish (Danio Rerio) with 17α-ethinyl estradiol affects the transcription of genes involved in development and male sex differentiation. Comp Biochem Physiol C Toxicol Pharmacol 2014; 164:35-42. [PMID: 24747828 DOI: 10.1016/j.cbpc.2014.04.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Revised: 04/09/2014] [Accepted: 04/11/2014] [Indexed: 01/04/2023]
Abstract
The synthetic estrogen 17α-ethinyl estradiol (EE2) disturbs reproduction and causes gonadal malformation in fish. Effects on the transcription of genes involved in gonad development and function that could serve as sensitive biomarkers of reproductive effects in the field is, however, not well known. We have studied mRNA expression in testes and liver of adult zebrafish (Danio rerio) males treated with 0, 5 or 25 ng/L EE2for 14 days. qPCR analysis showed that the mRNA expression of four genes linked to zebrafish male sex determination and differentiation, Anti-Mullerian Hormone, Double sex and mab-related protein, Sry-related HMG box-9a and Nuclear receptor subfamily 5 group number 1b were significantly decreased by 25 ng/L, but not 5 ng/L EE2 compared with the levels in untreated fish. The decreased transcription was correlated with a previously shown spawning failure in these males (Reyhanian et al., 2011. Aquat Toxicol 105, 41-48), suggesting that decreased mRNA expression of genes regulating male sexual function could be involved in the functional sterility. The mRNA level of Cytochrome P-45019a, involved in female reproductive development, was unaffected by hormone treatment. The transcription of the female-specific Vitellogenin was significantly induced in testes. While testicular Androgen Receptor and the Estrogen Receptor-alpha mRNA levels were unchanged, Estrogen receptor-beta was significantly decreased by 25 ng/L EE2. Hepatic Estrogen Receptor-alpha mRNA was significantly increased by both exposure concentrations, while Estrogen Receptor-beta transcription was unaltered. The decreased transcription of male-predominant genes supports a demasculinization of testes by EE2 and might reflect reproductive disturbances in the environment.
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Affiliation(s)
- Nasim Reyhanian Caspillo
- School of Natural Sciences, Technology and Environmental Studies, Södertörn University, SE-141 89 Huddinge, Sweden; Örebro Life Science Center, School of Science and Technology, Örebro University, SE-701 82 Örebro, Sweden.
| | - Kristina Volkova
- School of Natural Sciences, Technology and Environmental Studies, Södertörn University, SE-141 89 Huddinge, Sweden; Örebro Life Science Center, School of Science and Technology, Örebro University, SE-701 82 Örebro, Sweden
| | - Stefan Hallgren
- School of Natural Sciences, Technology and Environmental Studies, Södertörn University, SE-141 89 Huddinge, Sweden
| | - Per-Erik Olsson
- Örebro Life Science Center, School of Science and Technology, Örebro University, SE-701 82 Örebro, Sweden
| | - Inger Porsch-Hällström
- School of Natural Sciences, Technology and Environmental Studies, Södertörn University, SE-141 89 Huddinge, Sweden
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107
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Shanthanagouda AH, Nugegoda D, Patil JG. Effects of bisphenol A and fadrozole exposures on cyp19a1 expression in the Murray rainbowfish, Melanotaenia fluviatilis. ARCHIVES OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2014; 67:270-280. [PMID: 24898176 DOI: 10.1007/s00244-014-0047-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2013] [Accepted: 05/09/2014] [Indexed: 06/03/2023]
Abstract
Several endocrine-disrupting chemicals (EDCs) have been attributed to the alteration of reproduction in fish through disrupting endogenous sex steroidogenic pathways including aromatisation of androgens to oestrogen by CYP19 aromatase. Here we investigate this hypothesis in adult male and female Melanotaenia fluviatilis by examining the mRNA expression of cyp19a1 isoforms after exposure for ≤96 h to two EDCs with contrasting modes of action: one a weak oestrogen mimic, bisphenol A [BPA (100 or 500 μg/L)], and the other a nonsteroidal aromatase inhibitor, fadrozole [FAD (10 or 50 µg/L)]. The results suggest that BPA did not affect cyp19a1a expression significantly at both concentrations, whereas 50 µg/L of FAD significantly upregulated its expression in ovary. In contrast, BPA exposures increased expression of cyp19a1b in brain of both males and females, whilst FAD had contrasting effects in brain: It increased in males but decreased in females. Similar contrasting responses of cyp19a1b were induced by BPA in gonads: upregulation in ovary and downregulation in testis. FAD did not have a significant effect on gonadal expression of cyp19a1b. Collectively, the results suggest that BPA and FAD can disrupt cyp19a1b activity more readily than can cyp19a1a, albeit with contrasting effects in either a tissue- or sex-specific context that is conceivably consistent with their (BPA and FAD) opposing modes of action. Enhanced spatial and temporal sensitivity of cyp19a1b compared with cyp19a1a suggests that brain sex of fish is more susceptible to disruption by environmental pollutants such as BPA and FAD. Therefore, we propose that the response of cyp19a1b in brain tissue of M. fluviatilis is a more suitable indicator of oestrogenic pollution in the aquatic environment.
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Affiliation(s)
- A H Shanthanagouda
- School of Applied Sciences, RMIT University, Bundoora West Campus, Bundoora, VIC, 3083, Australia,
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108
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Baumann L, Knörr S, Keiter S, Rehberger K, Volz S, Schiller V, Fenske M, Holbech H, Segner H, Braunbeck T. Reversibility of endocrine disruption in zebrafish (Danio rerio) after discontinued exposure to the estrogen 17α-ethinylestradiol. Toxicol Appl Pharmacol 2014; 278:230-7. [DOI: 10.1016/j.taap.2014.04.025] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2013] [Revised: 04/08/2014] [Accepted: 04/29/2014] [Indexed: 10/25/2022]
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109
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Naderi M, Wong MYL, Gholami F. Developmental exposure of zebrafish (Danio rerio) to bisphenol-S impairs subsequent reproduction potential and hormonal balance in adults. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2014; 148:195-203. [PMID: 24508763 DOI: 10.1016/j.aquatox.2014.01.009] [Citation(s) in RCA: 196] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2013] [Revised: 01/07/2014] [Accepted: 01/10/2014] [Indexed: 05/28/2023]
Abstract
In the recent years, there has been a growing concern about the production and use of bisphenol-A substitute, namely bisphenol-S (BPS). Due to its novel nature, there have been few studies addressing the ability of BPS to disrupt the endocrine system of animals. In the present study, zebrafish (Danio rerio) embryos were exposed to and reared in various concentrations of BPS (0, 0.1, 1, 10 and 100 μg/l) for 75 days. Then adult males and females were paired in spawning tanks for 7 days in clean water and the consequent effects on fish development, reproduction, plasma vitellogenin (VTG), sex steroids and thyroid hormone levels were investigated as endpoints. After 75 days of exposure, there was a skewed sex ratio in favor of females. The results also showed that body length and weight significantly decreased in males exposed to 100 μg/l of BPS. Gonadosomatic index was significantly reduced in fish at ≥ 10 μg/l. Hepatosomatic index exhibited a significant increase in both male and female fish. At ≥ 1 μg/l of BPS, plasma 17β-estradiol levels were significantly increased in both males and females. However, plasma testosterone showed a significant reduction in males exposed to 10 and 100 μg/l of BPS. A significant induction in plasma VTG level was observed in both males and females at ≥ 10 μg/l of BPS. Plasma thyroxine and triiodothyronine levels were significantly decreased at 10 and 100 μg/l of BPS in males, and at 100 μg/l in females. Egg production and sperm count were also significantly decreased in groups received 10 and 100 μg/l of BPS. Moreover, once time to hatching and hatching rates were calculated for fertilized eggs the postponed and decreased rates of hatching were observed. Taken together, these results suggest that developmental exposure to low concentrations of BPS has adverse effects on different parts of the endocrine system in zebrafish.
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Affiliation(s)
- Mohammad Naderi
- Department of Marine Biology, Faculty of Marine Science, Khorramshahr University of Marine Science and Technology, Khorramshahr, Iran.
| | - Marian Y L Wong
- School of Biological Sciences, University of Wollongong, Wollongong, NSW, Australia
| | - Fatemeh Gholami
- Department of Fundamental Science, Faculty of Biology, Yasuj Branch, Islamic Azad University, Yasuj, Iran
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110
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Overturf MD, Overturf CL, Carty DR, Hala D, Huggett DB. Levonorgestrel exposure to fathead minnows (Pimephales promelas) alters survival, growth, steroidogenic gene expression and hormone production. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2014; 148:152-161. [PMID: 24503577 DOI: 10.1016/j.aquatox.2014.01.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2013] [Revised: 01/07/2014] [Accepted: 01/10/2014] [Indexed: 06/03/2023]
Abstract
Human pharmaceuticals are commonly detected in the environment. Concern over these compounds in the environment center around the potential for pharmaceuticals to interfere with the endocrine system of aquatic organisms. The main focus of endocrine disruption research has centered on how estrogenic and androgenic compounds interact with the endocrine system to elicit reproductive effects. Other classes of compounds, such as progestins, have been overlooked. Recently, studies have investigated the potential for synthetic progestins to impair reproduction and growth in aquatic organisms. The present study utilizes the OECD 210 Early-life Stage (ELS) study to investigate the impacts levonorgestrel (LNG), a synthetic progestin, on fathead minnow (FHM) survival and growth. After 28 days post-hatch, survival of larval FHM was impacted at 462 ng/L, while growth was significantly reduced at 86.9 ng/L. Further analysis was conducted by measuring specific endocrine related mRNA transcript profiles in FHM larvae following the 28 day ELS exposure to LNG. Transcripts of 3β-HSD, 20β-HSD, CYP17, AR, ERα, and FSH were significantly down-regulated following 28d exposure to 16.3 ng/L LNG, while exposure to 86.9 ng/L significantly down-regulated 3β-HSD, 20β-HSD, CYP19A, and FSH. At 2,392 ng/L of LNG, a significant down-regulation occurred with CYP19A and ERβ transcripts, while mPRα and mPRβ profiles were significantly induced. No significant changes occurred in 11β-HSD, CYP11A, StAR, LHβ, and VTG mRNA expression following LNG exposure. An ex vivo steroidogenesis assay was conducted with sexually mature female FHM following a 7 day exposure 100 ng/L LNG with significant reductions observed in pregnenolone, 17α,20β-dihydroxy-4-pregnen-3-one (17,20-DHP), testosterone, and 11-ketotestosterone. Together these data suggest LNG can negatively impact FHM larval survival and growth, with significant alterations in endocrine related responses.
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Affiliation(s)
- Matthew D Overturf
- Department of Biology, University of North Texas, Denton, TX 76203, USA.
| | - Carmen L Overturf
- Department of Biology, University of North Texas, Denton, TX 76203, USA
| | - Dennis R Carty
- Department of Biology, University of North Texas, Denton, TX 76203, USA
| | - David Hala
- Department of Biology, University of North Texas, Denton, TX 76203, USA
| | - Duane B Huggett
- Department of Biology, University of North Texas, Denton, TX 76203, USA
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111
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Liu SY, Jin Q, Huang XH, Zhu GN. Disruption of zebrafish (Danio rerio) sexual development after full life-cycle exposure to environmental levels of triadimefon. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2014; 37:468-475. [PMID: 24531054 DOI: 10.1016/j.etap.2013.11.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2013] [Revised: 10/31/2013] [Accepted: 11/07/2013] [Indexed: 06/03/2023]
Abstract
In this study, zebrafish was exposed to environmental levels of triadimefon (0.125, 0.25, 0.5 μg/mL) from 24 h post fertilization to 120 days post fertilization. Several endpoints that related to reproductive function were evaluated. It was found that the body length, body weight and vitellogenin transcription were significantly reduced for fish exposed to triadimefon. Histological examination showed that the sex ratio of fish skewed to male and female exposed to 0.5 μg/mL triadimefon had immature ovary. The breeding success, as determined from data on egg production and spawning, was reduced in fish exposed to 0.25 μg/mL triadimefon. In the offspring, the reduced egg fertility, hatching rate and survival were observed in eggs exposed to 0.5 μg/mL triadimefon. These findings indicated that triadimefon had the potential to adversely affect the sexual development and breeding success through the multiple endocrine actions.
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Affiliation(s)
- Shao-ying Liu
- Laboratory of Chemistry and Physics, Hangzhou Center for Disease Control and Prevention, Hangzhou 310021, PR China
| | - Quan Jin
- Laboratory of Chemistry and Physics, Hangzhou Center for Disease Control and Prevention, Hangzhou 310021, PR China
| | - Xi-hui Huang
- Laboratory of Chemistry and Physics, Hangzhou Center for Disease Control and Prevention, Hangzhou 310021, PR China
| | - Guo-nian Zhu
- Institute of Pesticide and Environmental Toxicology, Zhejiang University, Hangzhou 310029, PR China.
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112
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Takatsu K, Miyaoku K, Roy SR, Murono Y, Sago T, Itagaki H, Nakamura M, Tokumoto T. Induction of female-to-male sex change in adult zebrafish by aromatase inhibitor treatment. Sci Rep 2013; 3:3400. [PMID: 24292399 PMCID: PMC3844967 DOI: 10.1038/srep03400] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Accepted: 11/15/2013] [Indexed: 11/09/2022] Open
Abstract
This study investigated whether undifferentiated germ and/or somatic stem cells remain in the differentiated ovary of a species that does not undergo sex changes under natural conditions and retain their sexual plasticity. The effect of aromatase inhibitor (AI)-treatment on sexually mature female zebrafish was examined. A 5-month AI treatment caused retraction of the ovaries after which testes-like organs appeared, and cyst structures filled with spermatozoa-like cells were observed in sections of these tissues. Electron microscopic observations revealed that these cells appeared as large sperm heads without tails. Sperm formation was re-examined after changing the diet to an AI-free food. A large number of normal sperm were obtained after eight weeks, and no formation of ovarian tissue was observed. Artificial fertilization using sperm from the sex-changed females was successful. These results demonstrated that sex plasticity remains in the mature ovaries of this species.
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Affiliation(s)
- Kanae Takatsu
- Department of Biology, Faculty of Science, National University Corporation Shizuoka University, Oya 836, Suruga-ku, Shizuoka 422-8529, Japan
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113
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Chambers JE, Greim H, Kendall RJ, Segner H, Sharpe RM, Van Der Kraak G. Human and ecological risk assessment of a crop protection chemical: a case study with the azole fungicide epoxiconazole. Crit Rev Toxicol 2013; 44:176-210. [DOI: 10.3109/10408444.2013.855163] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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114
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Segner H, Casanova-Nakayama A, Kase R, Tyler CR. Impact of environmental estrogens on Yfish considering the diversity of estrogen signaling. Gen Comp Endocrinol 2013; 191:190-201. [PMID: 23763869 DOI: 10.1016/j.ygcen.2013.05.015] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/11/2012] [Revised: 05/16/2013] [Accepted: 05/29/2013] [Indexed: 12/31/2022]
Abstract
Research on endocrine disruption in fish has been dominated by studies on estrogen-active compounds which act as mimics of the natural estrogen, 17β-estradiol (E2), and generally exert their biological actions by binding to and activation of estrogen receptors (ERs). Estrogens play central roles in reproductive physiology and regulate (female) sexual differentiation. In line with this, most adverse effects reported for fish exposed to environmental estrogens relate to sexual differentiation and reproduction. E2, however, utilizes a variety of signaling mechanisms, has multifaceted functions and targets, and therefore the toxicological and ecological effects of environmental estrogens in fish will extend beyond those associated with the reproduction. This review first describes the diversity of estrogen receptor signaling in fish, including both genomic and non-genomic mechanisms, and receptor crosstalk. It then considers the range of non-reproductive physiological processes in fish that are known to be responsive to estrogens, including sensory systems, the brain, the immune system, growth, specifically through the growth hormone/insulin-like growth factor system, and osmoregulation. The diversity in estrogen responses between fish species is then addressed, framed within evolutionary and ecological contexts, and we make assessments on their relevance for toxicological sensitivity as well as ecological vulnerability. The diversity of estrogen actions raises questions whether current risk assessment strategies, which focus on reproductive endpoints, and a few model fish species only, are protective of the wider potential health effects of estrogens. Available - although limited - evidence nevertheless suggests that quantitative environmental threshold concentrations for environmental protection derived from reproductive tests with model fish species are protective for non-reproductive effects as well. The diversity of actions of estrogens across divergent physiological systems, however, may lead to and underestimation of impacts on fish populations as their effects are generally considered on one functional process only and this may underrepresent the impact on the different physiological processes collectively.
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Affiliation(s)
- Helmut Segner
- Centre for Fish and Wildlife Health, University of Bern, Bern, Switzerland.
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115
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Ji K, Liu X, Lee S, Kang S, Kho Y, Giesy JP, Choi K. Effects of non-steroidal anti-inflammatory drugs on hormones and genes of the hypothalamic-pituitary-gonad axis, and reproduction of zebrafish. JOURNAL OF HAZARDOUS MATERIALS 2013; 254-255:242-251. [PMID: 23611805 DOI: 10.1016/j.jhazmat.2013.03.036] [Citation(s) in RCA: 123] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2012] [Revised: 03/13/2013] [Accepted: 03/16/2013] [Indexed: 06/02/2023]
Abstract
This study was conducted in two experiments, to identify non-steroidal anti-inflammatory drugs (NSAIDs) with high endocrine disruption potentials, and to understand consequences of exposure to such NSAIDs in fish. In the first experiment, the effects of five NSAIDs on hormones and gene transcriptions of the hypothalamic-pituitary-gonad (HPG) axis were evaluated after 14 d exposure of adult zebrafish. Ibuprofen and mefenamic acids were identified to increase the concentrations of 17β-estradiol and testosterone in females significantly, while decreased those of testosterone among male fish. Significant up-regulation of fshβ, lhβ, fshr and lhr were observed in females, whereas down-regulation was observed in males exposed to each NSAID. In the second experiment, ibuprofen was chosen as a model chemical. Adult zebrafish pairs were exposed to ibuprofen for 21 d, and the effects on reproduction and development of offspring were examined. The egg production was significantly decreased at ≥1 μg/L ibuprofen, and parental exposure resulted in delayed hatching even when they were transferred to clean water for hatching. The results demonstrated that ibuprofen could modulate hormone production and related gene transcription of the HPG axis in a sex-dependent way, which could cause adverse effects on reproduction and the development of offspring.
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Affiliation(s)
- Kyunghee Ji
- School of Public Health, Seoul National University, Seoul 151-742, Republic of Korea; Department of Biomedical Veterinary Sciences and Toxicology Centre, University of Saskatchewan, Saskatoon, SK S7N 5B3, Canada; Department of Occupational and Environmental Health, Yongin University, Yongin 449-714, Republic of Korea
| | - Xiaoshan Liu
- School of Public Health, Seoul National University, Seoul 151-742, Republic of Korea
| | - Saeram Lee
- School of Public Health, Seoul National University, Seoul 151-742, Republic of Korea
| | - Sungeun Kang
- School of Public Health, Seoul National University, Seoul 151-742, Republic of Korea
| | - Younglim Kho
- School of Human & Environmental Sciences, Eulji University, Seongnam 461-713, Republic of Korea
| | - John P Giesy
- Department of Biomedical Veterinary Sciences and Toxicology Centre, University of Saskatchewan, Saskatoon, SK S7N 5B3, Canada
| | - Kyungho Choi
- School of Public Health, Seoul National University, Seoul 151-742, Republic of Korea.
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116
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Yan Z, Lu G, Wu D, Ye Q, Xie Z. Interaction of 17β-estradiol and ketoconazole on endocrine function in goldfish (Carassius auratus). AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2013; 132-133:19-25. [PMID: 23434491 DOI: 10.1016/j.aquatox.2013.01.015] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2012] [Revised: 01/29/2013] [Accepted: 01/29/2013] [Indexed: 06/01/2023]
Abstract
An understanding of the effects of toxic mixtures of endocrine disrupting chemicals (EDCs) on aquatic organisms is challenging as these organisms are exposed to multiple classes of contaminants in their natural habitat. The aim of the present study was to evaluate the interactions of two classes of EDCs, 17β-estradiol (E2) and ketoconazole (KTC), on endocrine function in male goldfish (Carassius auratus), including vitellogenesis, metabolic capability and serum steroid synthesis. Changes in vitellogenin (VTG) concentration, liver 7-ethoxyresorufin-O-deethylase (EROD) activity and circulating serum E2 level were examined. The expression of related genes was also determined using quantitative real-time polymerase chain reaction. Exposure to E2 caused a significant increase in VTG concentrations which corresponded with the gene expression of VTG and estrogen receptor (ER) in males, which were further elevated after combined exposure to E2 and KTC, indicative of a synergetic relationship. Exposure to E2 also resulted in a distinct increase in serum steroid biosynthesis and associated cytochrome P450 (CYP) aromatase expression after 10 days. However, these changes were inhibited by the presence of KTC, which acted as a steroidogenic inhibitor in fish. Moreover, KTC significantly decreased liver EROD activity and increased the related gene expression of CYP1A. However, these KTC-mediated metabolic reactions in goldfish were up-regulated following exposure to KTC in combination with E2. These findings reveal complex interactions on endocrine functions in male goldfish when exposed to multiple contaminations and may provide a better understanding of the effects of toxic mixtures.
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Affiliation(s)
- Zhenhua Yan
- Key Laboratory of Integrated Regulation and Resources Development of Shallow Lakes of Ministry of Education, College of Environment, Hohai University, 1 Xikang Road, Nanjing 210098, China
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117
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Sharma P, Patiño R. Regulation of gonadal sex ratios and pubertal development by the thyroid endocrine system in zebrafish (Danio rerio). Gen Comp Endocrinol 2013; 184:111-9. [PMID: 23337033 DOI: 10.1016/j.ygcen.2012.12.018] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/05/2012] [Revised: 11/12/2012] [Accepted: 12/25/2012] [Indexed: 11/27/2022]
Abstract
We examined associations between thyroid condition, gonadal sex and pubertal development in zebrafish. Seventy-two-hour postfertilization larvae were reared in untreated medium or in the presence of goitrogens (sodium perchlorate, 0.82 mM; methimazole, 0.15 and 0.3 mM) or thyroxine (1 and 10 nM) for 30 days. Thyrocyte height, gonadal sex and gonadal development were histologically determined at 45 and 60 days postfertilization (dpf). Thyrocyte hypertrophy, an index of hypothyroidism, was observed at 45 and 60 dpf in perchlorate-treated but only at 45 dpf in methimazole-treated fish. Similarly, gonadal sex ratios were biased toward ovaries relative to control animals at 45 and 60 dpf in perchlorate-treated fish but only at 45 dpf in methimazole-treated fish. Gonadal sex ratios were biased toward testes at 45 and 60 dpf in thyroxine-treated fish. Spermatogenesis was delayed in testes from goitrogen-treated fish at 60 dpf relative to control values, but was unaffected in testes from thyroxine-treated individuals. Oogenesis seemed to be nonspecifically delayed in all treatments relative to control at 60 dpf. This study confirmed the previously reported association between hypothyroid condition and ovarian-skewed ratios, and hyperthyroid condition and testicular-skewed ratios, and also showed that male pubertal development is specifically delayed by experimental hypothyroidism. The simultaneous recovery from the hypothyroid and ovary-inducing effects of methimazole by 60 dpf (27 days post-treatment) suggests that the ovary-skewing effect of goitrogens is reversible when thyroid conditions return to basal levels before developmental commitment of gonadal sex. Conversely, the masculinizing effect of hyperthyroidism seems to be stable and perhaps permanent.
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Affiliation(s)
- Prakash Sharma
- Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409-2120, USA
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118
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In vivo response of melatonin, gonadal activity and biochemical changes during CYP19 inhibited sex reversal in common carp Cyprinus carpio (L). Anim Reprod Sci 2013; 136:317-25. [DOI: 10.1016/j.anireprosci.2012.11.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2012] [Revised: 11/05/2012] [Accepted: 11/06/2012] [Indexed: 11/20/2022]
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119
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Schiller V, Wichmann A, Kriehuber R, Muth-Köhne E, Giesy JP, Hecker M, Fenske M. Studying the effects of genistein on gene expression of fish embryos as an alternative testing approach for endocrine disruption. Comp Biochem Physiol C Toxicol Pharmacol 2013; 157:41-53. [PMID: 23017276 DOI: 10.1016/j.cbpc.2012.09.005] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2012] [Revised: 09/17/2012] [Accepted: 09/18/2012] [Indexed: 12/11/2022]
Abstract
Assessment of endocrine disruption currently relies on testing strategies involving adult vertebrates. In order to minimize the use of animal tests according to the 3Rs principle of replacement, reduction and refinement, we propose a transcriptomics and fish embryo based approach as an alternative to identify and analyze an estrogenic activity of environmental chemicals. For this purpose, the suitability of 48 h and 7 days post-fertilization zebrafish and medaka embryos to test for estrogenic disruption was evaluated. The embryos were exposed to the phytoestrogen genistein and subsequently analyzed by microarrays and quantitative real-time PCR. The functional analysis showed that the genes affected related to multiple metabolic and signaling pathways in the early fish embryo, which reflect the known components of genistein's mode of actions, like apoptosis, estrogenic response, hox gene expression and steroid hormone synthesis. Moreover, the transcriptomic data also suggested a thyroidal mode of action and disruption of the nervous system development. The parallel testing of two fish species provided complementary data on the effects of genistein at gene expression level and facilitated the separation of common from species-dependent effects. Overall, the study demonstrated that combining fish embryo testing with transcriptomics can deliver abundant information about the mechanistic effects of endocrine disrupting chemicals, rendering this strategy a promising alternative approach to test for endocrine disruption in a whole organism in-vitro scale system.
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Affiliation(s)
- Viktoria Schiller
- Fraunhofer Institute for Molecular Biology and Applied Ecology, Aachen, Germany.
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120
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Li J, Sun L, Zuo Z, Chen M, Geng H, Wang C. Exposure to paclobutrazol disrupts spermatogenesis in male Sebastiscus marmoratus. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2012; 122-123:120-124. [PMID: 22789407 DOI: 10.1016/j.aquatox.2012.06.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2012] [Revised: 06/09/2012] [Accepted: 06/19/2012] [Indexed: 06/01/2023]
Abstract
Paclobutrazol (PBZ) is triazole-containing fungicides and widely used in agriculture as an efficient plant growth retardant. However, far fewer studies addressing the reproductive toxicity of PBZ on fishes are available. The present study was conducted to investigate the effects of PBZ at environmentally relevant concentrations on testicular development in male rockfish Sebastiscus marmoratus and to gain insight into its mechanism of action. After exposure to 10, 100 and 1000 ng/L PBZ for 50 d, although the gonadosomatic index did not show a significant alteration, there was a reduced number of mature sperm and an abundance of the late stages of spermatocysts in the testes. The activity of γ-glutamyl transpeptidase (which is used as a Sertoli cell marker) was decreased in a dose-dependent manner after PBZ exposure, which might be a result of the reduction in FSHβ expression in the brain. The toxicity induced by accumulation of PBZ in the brain might be primary cause impacting the spermatogenesis via brain-pituitary-gonad pathway.
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Affiliation(s)
- Jinshou Li
- Department of Biological Engineering, Ningde Normal University, Ningde City, Fujian, China
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121
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Blüthgen N, Zucchi S, Fent K. Effects of the UV filter benzophenone-3 (oxybenzone) at low concentrations in zebrafish (Danio rerio). Toxicol Appl Pharmacol 2012; 263:184-94. [DOI: 10.1016/j.taap.2012.06.008] [Citation(s) in RCA: 182] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2012] [Revised: 06/10/2012] [Accepted: 06/11/2012] [Indexed: 01/16/2023]
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122
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Uno T, Ishizuka M, Itakura T. Cytochrome P450 (CYP) in fish. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2012; 34:1-13. [PMID: 22418068 DOI: 10.1016/j.etap.2012.02.004] [Citation(s) in RCA: 216] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2011] [Revised: 01/31/2012] [Accepted: 02/05/2012] [Indexed: 05/31/2023]
Abstract
Cytochrome P450 (CYP) enzymes are members of the hemoprotein superfamily, and are involved in the mono-oxygenation reactions of a wide range of endogenous and exogenous compounds in mammals and plants. Characterization of CYP genes in fish has been carried out intensively over the last 20 years. In Japanese pufferfish (Takifugu rubripes), 54 genes encoding P450s have been identified. Across all species of fish, 137 genes encoding P450s have been identified. These genes are classified into 18 CYP families: namely, CYP1, CYP2, CYP3, CYP4, CYP5, CYP7, CYP8, CYP11, CYP17, CYP19, CYP20, CYP21, CYP24, CYP26, CYP27, CYP39, CYP46 and CYP51.We pinpointed eight CYP families: namely, CYP1, CYP2, CYP3, CYP4, CYP11, CYP17, CYP19 and CYP26 in this review because these CYP families are studied in detail. Studies of fish P450s have provided insights into the regulation of P450 genes by environmental stresses including water pollution. In this review, we present an overview of the CYP families in fish.
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Affiliation(s)
- Tomohide Uno
- Laboratory of Biological Chemistry, Department of Biofunctional Chemistry, Faculty of Agriculture, Kobe University, Nada-ku Hyogo, Japan.
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123
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Wang H, Wu T, Qin F, Wang L, Wang Z. Molecular cloning of Foxl2 gene and the effects of endocrine-disrupting chemicals on its mRNA level in rare minnow, Gobiocypris rarus. FISH PHYSIOLOGY AND BIOCHEMISTRY 2012; 38:653-664. [PMID: 21850400 DOI: 10.1007/s10695-011-9548-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2011] [Accepted: 08/03/2011] [Indexed: 05/31/2023]
Abstract
Endocrine-disrupting chemicals (EDCs) can affect normal sexual differentiation in fish. Foxl2, one forkhead transcription factor, plays an important role in ovarian differentiation in the early development of the female gonad in mammals and fish. How EDCs affect Foxl2 expression is little known. In this study, we isolated a Foxl2 cDNA from the ovary of rare minnow Gobiocypris rarus and examined its expression during early development stages and in different adult tissues. Then, we analyzed Foxl2 expression in G. rarus juvenile following 3-day exposure to 17α- ethinylestradiol (EE2), 4-n-nonylphenol (NP), and bisphenol A (BPA). Alignment of known Foxl2 sequences among vertebrates showed high identity in forkhead domain and C-terminal region with other vertebrate proteins. Quantitative RT-PCR analysis showed that Foxl2 expression was linear decrease and cyp19a1a, the downstream target gene of Foxl2, had no correlation with Foxl2 from 18 to 50 days post fertilization (dpf). Among different adult tissues, Foxl2 is mainly expressed in ovary, brain, gill, eye, and male spleen. In the 3-day exposure, the juvenile fish to EDCs, 0.1 nM EE2, and 1 nM BPA significantly up-regulated the expression of Foxl2 gene, while NP had no effect on Foxl2 expression. Altogether, these results provide basic data for further study on how Foxl2 mediates EDCs impact on the sexual differentiation in G. rarus.
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Affiliation(s)
- Houpeng Wang
- Shaanxi Key Laboratory of Molecular Biology for Agriculture, College of Animal Science and Technology, Northwest A&F University, 22 Xinong Road, Yangling, Shaanxi, China
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124
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Duarte-Guterman P, Ryan MJ, Trudeau VL. Developmental expression of sex steroid- and thyroid hormone-related genes and their regulation by triiodothyronine in the gonad-mesonephros of a Neotropical frog, Physalaemus pustulosus. Gen Comp Endocrinol 2012; 177:195-204. [PMID: 22487252 DOI: 10.1016/j.ygcen.2012.03.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2011] [Revised: 02/27/2012] [Accepted: 03/22/2012] [Indexed: 12/29/2022]
Abstract
Gonadal differentiation in frogs is affected by sex steroids and thyroid hormones (THs); however, the genes controlling differentiation and the molecular effects of THs in the gonad are not clear and have only been investigated in a few anuran species. In this study, we established developmental profiles and TH regulation of sex steroid- and TH-related genes in the gonad-mesonephros complex (GMC) of the túngara frog (Physalaemus pustulosus), and compared the results to our previous research in another tropical frog, Silurana tropicalis. The developmental profiles allowed us to identify three genes as markers of ovarian development. During metamorphosis, aromatase (cyp19), estrogen receptor α, and steroid 5α-reductase 1 (srd5alpha1) were higher in the GMC of putative and morphological females. Acute exposure to triiodothyronine (T3) decreased GMC expression of srd5alpha1 and cyp19, while increasing TH-related genes in premetamorphic tadpoles. The regulation of sex steroid-related genes differed significantly from our previous study in S. tropicalis. P. pustulosus and S. tropicalis share ecological, developmental, and reproductive characteristics; however, they are not closely related. These results along with our previous research in the tadpole brain support the hypothesis that evolutionary convergence is not important in understanding differences in the effects of TH on sex steroid-related genes in frogs. Finally, we propose that T3 induces male gonadal development but this can be achieved through different mechanisms depending on the species.
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Affiliation(s)
- Paula Duarte-Guterman
- Centre for Advanced Research in Environmental Genomics, Department of Biology, University of Ottawa, Ottawa, Ontario, Canada K1N 6N5
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125
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Urbatzka R, Rocha E, Reis B, Cruzeiro C, Monteiro RAF, Rocha MJ. Effects of ethinylestradiol and of an environmentally relevant mixture of xenoestrogens on steroidogenic gene expression and specific transcription factors in zebrafish. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2012; 164:28-35. [PMID: 22318008 DOI: 10.1016/j.envpol.2012.01.018] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2011] [Revised: 01/10/2012] [Accepted: 01/15/2012] [Indexed: 05/31/2023]
Abstract
In natural environments fish are exposed to endocrine disrupting compounds (EDCs) present at low concentrations and with different modes of actions. Here, adult zebrafish of both sexes were exposed for 21 days to an estrogenic mixture (Mix) of eleven EDCs previously quantified in Douro River estuary (Portugal) and to 100 ng/L 17α-ethinylestradiol (EE2) as positive control. Vitellogenin mRNA and HSI in males confirmed both exposure regimes as physiologically active. Potential candidates for estrogenic disturbance of steroidogenesis were identified (StAR, 17β-HSD1, cyp19a1), but Mix only affected cyp19a1 in females. Significant differences in the response of FSHβ, cypa19a2, 20β-HSD were observed between EE2 and Mix. Mtf-1 and tfap2c transcription factor binding sites were discovered in the putative promoter regions and corresponding transcription factors were found to be differentially expressed in response to Mix and EE2. The results suggest that "non-classical effects" of estrogenic EDC in fish are mediated via transcription factors.
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Affiliation(s)
- R Urbatzka
- Laboratory of Cellular, Molecular and Analytical Studies (LECEMA), Interdisciplinary Centre of Marine and Environmental Research (CIIMAR), CIMAR Associated Laboratory (CIMAR LA), University of Porto (U.Porto), Rua dos Bragas 289, 4050-123 Porto, Portugal.
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126
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Chang J, Gui W, Wang M, Zhu G. Effects of butachlor on estrogen receptor, vitellogenin and P450 aromatase gene expression in the early life stage of zebrafish. JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH. PART A, TOXIC/HAZARDOUS SUBSTANCES & ENVIRONMENTAL ENGINEERING 2012; 47:1672-1677. [PMID: 22702828 DOI: 10.1080/10934529.2012.687256] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Butachlor has adverse effects on fecundity and disrupts sex hormone homeostasis in adult zebrafish, but the underlying molecular mechanisms are still unclear. In the present study, zebrafish (Danio rerio) embryos were exposed to various concentrations of butachlor from 2 h post-fertilization (hpf) to 30 days post-fertilization (dpf). The transcription of genes involved estrogen receptors (ERα, ERβ1 and ERβ2), vitellogenins (VTG I and II), and cytochrome P450 aromatase (CYP19a) was analyzed by real-time quantitative PCR. The results showed that there was no significant alteration in the expression of VTGI, ERα, ERβ1, ERβ2 and CYP19a after 30 days of butachlor exposure, whereas the transcription of VTG II gene was significantly up-regulated in zebrafish exposed to 100 μg/L butachlor. It is suggested that butachlor may be a weak estrogen, and more endpoints need to be investigated to assess the effects of butachlor on the hypothalamus-pituitary-gonadal axis of zebrafish.
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Affiliation(s)
- Juhua Chang
- a Department of Pesticide Science, College of Plant Protection, Nanjing Agricultural University, Jiangsu Key Laboratory of Pesticide Science, Nanjing, P. R. China
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127
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Sridevi P, Senthilkumaran B. Cloning and differential expression of FOXL2 during ovarian development and recrudescence of the catfish, Clarias gariepinus. Gen Comp Endocrinol 2011; 174:259-68. [PMID: 21906596 DOI: 10.1016/j.ygcen.2011.08.015] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2011] [Revised: 08/12/2011] [Accepted: 08/23/2011] [Indexed: 10/17/2022]
Abstract
FOXL2 is a member of the forkhead/HNF-3-related family of transcription factors which provides tissue-specific gene regulation. It is known to regulate ovarian aromatase, (cyp19a1a) which plays a crucial role in ovarian differentiation. To understand the role of FOXL2 in gonads and brain during ovarian development and recrudescence, we cloned the full-length cDNA of FOXL2 and analyzed its spatio-temporal expression both at transcript and protein levels in the air-breathing catfish, Clarias gariepinus. Based on its deduced amino acid sequence, an antigenic peptide conjugated with a carrier protein was synthesized which was then used for raising antibody that reacted specifically with FOXL2. Tissue distribution pattern of FOXL2 revealed its presence prominently in ovary and female brain with sexual dimorphism. Highest expression of FOXL2 was observed in ovary and brain during prespawning phase indicating an important role for this correlate in ovarian recrudescence. Human chorionic gonadotropin (hCG) treatment, in vitro and in vivo, induced FOXL2 expression in the ovary during preparatory and prespawning phases. Similar type of enhanced expression was evident in brain after hCG-induction during the prespawning phase. The ontogeny of FOXL2 showed sexual dimorphic expression pattern both in gonads and brain. Based on our previous studies, the expression pattern of FOXL2 was found to be synchronous not only with that of ovarian cyp19a1a but also with brain cyp19a1b. Present study substantiates the role of FOXL2 in the regulation of aromatase in teleosts and also designates FOXL2 as a potential ovary and brain marker during female sex development in catfish.
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Affiliation(s)
- P Sridevi
- Department of Animal Sciences, School of Life Sciences, University of Hyderabad, P.O. Central University, Hyderabad 500 046, Andhra Pradesh, India
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128
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Thresher R, Gurney R, Canning M. Effects of lifetime chemical inhibition of aromatase on the sexual differentiation, sperm characteristics and fertility of medaka (Oryzias latipes) and zebrafish (Danio rerio). AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2011; 105:355-360. [PMID: 21819815 DOI: 10.1016/j.aquatox.2011.07.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2011] [Revised: 07/06/2011] [Accepted: 07/07/2011] [Indexed: 05/31/2023]
Abstract
The deleterious effects of tributyltin (TBT) on spermiation in fish have been attributed to its role in inhibiting aromatisation of androgens to estrogens, and the critical role of the latter in sperm development. We test this hypothesis by examining sperm parameters, fertilisation and hatching success in males of two fish species exposed throughout life to doses of Fadrozole, a non-steroidal aromatase inhibitor (AI), provided in their diets. AI-treatment caused 100% male development in zebrafish, but only partial masculinisation in medaka, in both cases supporting previous studies and suggesting different roles of estrogen in sexual differentiation in the two species. Milt volume, initial sperm motility, maximum sperm swimming duration and sperm morphology did not differ significantly between Control and AI-dosed fish in either species, after excluding low milt volumes in sex-changed females in medaka. Fertilisation rates were also unaffected by the aromatase inhibition, but hatching success in medaka was 31% lower than in Control males, suggesting a previously unreported effect of aromatase on sperm quality. The slight effect of aromatase inhibition on sperm parameters in general contrasts with the marked effect of TBT on fish sperm, and suggests that a mechanism other than depressed estrogen levels is involved.
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Affiliation(s)
- Ronald Thresher
- CSIRO Marine and Atmospheric Research, GPO Box 1538, Hobart, Tasmania 7001, Australia.
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129
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Reyhanian N, Volkova K, Hallgren S, Bollner T, Olsson PE, Olsén H, Hällström IP. 17α-Ethinyl estradiol affects anxiety and shoaling behavior in adult male zebra fish (Danio rerio). AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2011; 105:41-48. [PMID: 21684240 DOI: 10.1016/j.aquatox.2011.05.009] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2011] [Revised: 05/04/2011] [Accepted: 05/10/2011] [Indexed: 05/30/2023]
Abstract
Ethinyl estradiol is a potent endocrine disrupting compound in fish and ubiquitously present in the aquatic environment. In this study, we exposed adult zebra fish (Danio rerio) males to 0, 5 or 25 ng Ethinyl estradiol/L for 14 days and analyzed the effects on non-reproductive behavior. Effects of treatment of the exposed males was shown by vitellogenin induction, while brain aromatase (CYP 19B) activity was not significantly altered. Both concentrations of Ethinyl estradiol significantly altered the behavior in the Novel tank test, where anxiety is determined as the tendency to stay at the bottom when introduced into an unfamiliar environment. The effects were, however, opposite for the two concentrations. Fish that were exposed to 5 ng/L had longer latency before upswim, fewer transitions to the upper half and shorter total time spent in the upper half compared with control fish, while 25 ng Ethinyl estradiol treatment resulted in shorter latency and more and longer visits to the upper half. The swimming activity of 25, but not 5 ng-exposed fish were slightly but significantly reduced, and these fish tended to spend a lot of time at the surface. We also studied the shoaling behavior as the tendency to leave a shoal of littermates trapped behind a Plexiglas barrier at one end of the test tank. The fish treated with Ethinyl estradiol had significantly longer latency before leaving shoal mates and left the shoal fewer times. Further, the fish exposed to 5 ng/L also spent significantly less time away from shoal than control fish. Fertilization frequency was higher in males exposed to 5 ng/L Ethinyl estradiol when compared with control males, while no spawning was observed after treatment with 25 ng/L. The testes from both treatment groups contained a normal distribution of spermatogenesis stages, and no abnormality in testis morphology could be observed. In conclusion, we have observed effects on two behaviors not related to reproduction in zebra fish males after treatment with Ethinyl estradiol, adding to the ecological consequences of contamination of aquatic environments with estrogenic substances.
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Affiliation(s)
- Nasim Reyhanian
- School of Life Sciences, Södertörn University, SE-141 86 Huddinge, Sweden
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130
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Katsu Y, Lange A, Miyagawa S, Urushitani H, Tatarazako N, Kawashima Y, Tyler CR, Iguchi T. Cloning, expression and functional characterization of carp,Cyprinus carpio, estrogen receptors and their differential activations by estrogens. J Appl Toxicol 2011; 33:41-9. [DOI: 10.1002/jat.1707] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2011] [Revised: 05/07/2011] [Accepted: 05/07/2011] [Indexed: 12/23/2022]
Affiliation(s)
| | - Anke Lange
- School of Biosciences, College of Life and Environmental Sciences; University of Exeter; Exeter; EX4 4PS; UK
| | | | | | - Norishisa Tatarazako
- National Institute for Environmental Studies; 16-2 Onogawa; Tsukuba; Ibaraki; 305-8506; Japan
| | - Yukio Kawashima
- Japan NUS Co. Ltd, 7-5-25 Nishi-Shinjyuku; Shinjyuku-ku; Tokyo; 160-0023; Japan
| | - Charles R. Tyler
- School of Biosciences, College of Life and Environmental Sciences; University of Exeter; Exeter; EX4 4PS; UK
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131
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An SNP-Based Linkage Map for Zebrafish Reveals Sex Determination Loci. G3-GENES GENOMES GENETICS 2011; 1:3-9. [PMID: 21949597 PMCID: PMC3178105 DOI: 10.1534/g3.111.000190] [Citation(s) in RCA: 106] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
A surprising diversity of mechanisms controls sex determination of vertebrate organisms, even among closely related species. Both genetic and temperature-dependent systems of sex determination have been described in teleost fish. In the common zebrafish model organism, heteromorphic sex chromosomes are not observed, and the potential role of a genetic component of sex determination remains largely unknown. Here we report a genome-wide linkage study of sex determination in zebrafish using a novel SNP genetic map. We identified loci on zebrafish chromosomes 5 (LOD score 7.9) and 16 (LOD score 9.3) governing sex determination as a complex trait, rather than as an XY or ZW genetic system. Each of these loci contains a prominent candidate gene with a conserved role in sex determination across additional species that suggest potential mechanisms of sex determination in zebrafish. The chromosome 5 locus harbors dmrt1, a key gene in sex determination from fruit flies to humans; mutation of the human DMRT1 ortholog is a cause of complete sex reversal of XY individuals. The chromosome 16 locus harbors cyp21a2; mutation of the human CYP21A2 ortholog is one of the more common causes of pseudohermaphroditism. Mutation detection at each of these candidate genes within the zebrafish cross identified hypomorphic variants on the female-associated allele of each locus. The two loci together accounted for 16% of variance of the trait. Interacting environmental cues are likely to be an additional important component of sex determination in zebrafish.
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132
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Leet JK, Gall HE, Sepúlveda MS. A review of studies on androgen and estrogen exposure in fish early life stages: effects on gene and hormonal control of sexual differentiation. J Appl Toxicol 2011; 31:379-98. [PMID: 21557264 DOI: 10.1002/jat.1682] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2011] [Revised: 02/23/2011] [Accepted: 02/24/2011] [Indexed: 11/09/2022]
Abstract
Teleost fish are unique among vertebrates in that phenotypic sex or onset of sex inversion can be easily manipulated by hormonal treatments. In recent years, researchers have begun reporting concentrations of synthetic and natural hormones in the environment. Although concentrations are very low (in the parts per trillion to low parts per billion), they are still of concern because of the high potency of synthetic hormones and the enhanced susceptibility of teleost fishes, especially early life stages, to hormonal exposures. In this review, we will focus on sex differentiation in teleost fishes and how these processes in fish early life stages may be impacted by environmental hormones which are known to contaminate aquatic environments. We will start by reviewing information on sources and concentrations of hormones in the environment and continue by summarizing the state of knowledge of sex differentiation in teleost gonochoristic fishes, including information on genes involved (e.g. cyp19, dmrt1, sox9 and foxl2). We will end our review with a summary of studies that have examined the effects of androgens and estrogens on fish sex differentiation after exposure of fish embryos and larvae and with ideas for future research.
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Affiliation(s)
- Jessica K Leet
- Department of Forestry and Natural Resources, Purdue University, West Lafayette, IN 47907, USA
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133
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Han XB, Lei ENY, Lam MHW, Wu RSS. A whole life cycle assessment on effects of waterborne PBDEs on gene expression profile along the brain-pituitary-gonad axis and in the liver of zebrafish. MARINE POLLUTION BULLETIN 2011; 63:160-165. [PMID: 21549400 DOI: 10.1016/j.marpolbul.2011.04.001] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2010] [Revised: 04/01/2011] [Accepted: 04/04/2011] [Indexed: 05/30/2023]
Abstract
Polybrominated diphenyl ethers (PBDEs) are now found ubiquitously in the aquatic environment and biota, and there is a growing concern that PBDEs may disrupt endocrine systems, leading to reproductive impairments of aquatic animals. In our study, zebrafish (Danio rerio) were exposed to the 5 ng/L, 1 μg/L and 50 μg/L of DE-71 for the duration of the whole life cycle (120 days, from eggs to adults). The expression of selected genes along the brain-pituitary-gonadal (BPG) axis and liver, and the levels of plasma sex hormones were examined. In male fish, up-regulation of GnRH in brain, FSHβ and LHβ in pituitary, FSH-receptor, LH-receptor, and CYP19a in testis was clearly evident, while down-regulation of CYP11a and 3β-HSD was found in testis. In female fish, a 2.4-fold up-regulation of 3β-HSD was found in ovary upon exposure to 50 μg/L of DE-71. GnRH in brain, FSHβ and LHβ in pituitary were also up-regulated, while ERβ, TH and TPH in brain and GnRH-receptor in pituitary were significantly down-regulated. Hepatic ERα, AR and VTG in males were all down-regulated, while hepatic ERα and AR in female were up-regulated. Serum estradiol (E2) was reduced in both male and female upon exposure to DE-71, while significant increases in serum testosterone (T) and 11-keto-testosterone (11-KT) were only found in male but not female fish. The ratio of T/E2 as well as the ratio of 11-KT/E2 in male fish increased in a dose-dependent manner upon exposure to DE-71. Our overall results showed that whole life exposure of DE-71 altered the expression of regulatory genes and receptors at all three levels of the BPG axis in zebrafish, and the responses are sex dependent. The observed disruption of GnRH and GtHs can be further related to the subsequent disruption in both levels and balance sex steroid hormones.
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Affiliation(s)
- X B Han
- Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong SAR, Hong Kong.
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134
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Margiotta-Casaluci L, Sumpter JP. 5α-Dihydrotestosterone is a potent androgen in the fathead minnow (Pimephales promelas). Gen Comp Endocrinol 2011; 171:309-18. [PMID: 21354156 DOI: 10.1016/j.ygcen.2011.02.012] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2010] [Revised: 02/09/2011] [Accepted: 02/18/2011] [Indexed: 12/30/2022]
Abstract
Dihydrotestosterone (DHT) is one of the most physiologically important androgens in many male vertebrates, with the exception of teleost fish, in which 11-ketotestosterone (KT) is generally considered the major circulating male androgen. In the present study, we investigated the effects of KT and DHT on fathead minnow juveniles (Pimephales promelas), with the aim to compare the effects of the two androgens on critical physiological processes, such as somatic growth, male secondary sexual characteristics expression, and gonad maturation. Juvenile fish (60 days post-hatch) were exposed to 20 and 200 ng/L of KT and DHT for 45 days. Exposure to both androgens significantly stimulated somatic growth in both males (20 and 200 ng/L) and females (200 ng/L). Nuptial tubercle formation was induced by both KT and DHT, but only the latter, at 200 ng/L, caused the appearance of dorsal fin spot in 92% of males and 75% of females. Circulating plasma T concentrations showed a sex-specific response; a significant increase was recorded in exposed males and a decrease in females. Both androgens induced a significant advancement of the spermatogenic processes in males at 200 ng/L. In contrast, only DHT caused a severe disruption of ovarian physiology and morphology in females, inducing the development of spermatogenic tissue (intersex). These results show that in fathead minnow juveniles, DHT had in vivo androgenic potency comparable to KT in males, and higher than KT in females, suggesting a potential involvement of DHT in the mediation of fathead minnow androgenic responses.
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135
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Sun L, Shao X, Chi J, Hu X, Jin Y, Fu Z. Transcriptional responses in the brain, liver and gonad of Japanese ricefish (Oryzias latipes) exposed to two anti-estrogens. Comp Biochem Physiol C Toxicol Pharmacol 2011; 153:392-401. [PMID: 21281741 DOI: 10.1016/j.cbpc.2011.01.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/09/2010] [Revised: 01/23/2011] [Accepted: 01/24/2011] [Indexed: 11/23/2022]
Abstract
The study of endocrine disruption is being increasingly conducted at the mRNA level of genes, as this approach might yield insight into the modes of action and mechanisms of toxicity. In this study, the transcriptional responses of a set of functionally relevant genes associated with the pathways of the hypothalamic-pituitary-gonadal (HPG; or HPG[L]-liver) axis of Japanese ricefish were examined after treatment with two model anti-estrogens, letrozole (LET) and tamoxifen (TAM), at three concentrations (30, 100 and 300μg/L) for 72h. The results showed that LET and TAM produced distinct expression profiles in a complex tissue- and gender-specific manner, confirming that they exert their anti-estrogenic effects via different molecular mechanisms. For example, the transcriptional levels of hepatic vitellogenin were significantly downregulated in females exposed to either LET or TAM, while they were significantly upregulated in TAM-exposed males and did not exhibit any change in LET-treated males. The expression of genes involved in steroidogenesis was also modulated by these two anti-estrogens in a way that corresponded with their anticipated mode of action. Overall, the data not only provide mechanistic information of anti-estrogenic chemicals but also demonstrate the potential of investigation of gene expression in the HPG(L) axis of model fish for diagnostic and predictive assessments of the risks associated with chemical exposure.
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Affiliation(s)
- Liwei Sun
- College of Biological and Environmental Engineering, Zhejiang University of Technology, Hangzhou, 310032, PR China
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136
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Mortensen AS, Letcher RJ, Cangialosi MV, Chu S, Arukwe A. Tissue bioaccumulation patterns, xenobiotic biotransformation and steroid hormone levels in Atlantic salmon (Salmo salar) fed a diet containing perfluoroactane sulfonic or perfluorooctane carboxylic acids. CHEMOSPHERE 2011; 83:1035-44. [PMID: 21354591 DOI: 10.1016/j.chemosphere.2011.01.067] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2010] [Revised: 01/18/2011] [Accepted: 01/29/2011] [Indexed: 05/05/2023]
Abstract
In the present study, groups of juvenile Atlantic salmon (Salmo salar) were fed gelatine capsules containing fish-food spiked with PFOA or PFOS (0.2 mg kg(-1) fish) and solvent (methanol). The capsules were given at days 0, 3 and 6. Blood, liver and whole kidney samples were collected prior to exposure (no solvent control), and at days 2, 5, 8 and 14 after exposure (Note: that day 14 after exposure is equal to 7d recovery period). We report on the differences in the tissue bioaccumulation patterns of PFOS and PFOA, in addition to tissue and compound differences in modulation pattern of biotransformation enzyme genes. We observed that the level of PFOS and PFOA increased in the blood, liver and kidney during the exposure period. Different PFOS and PFOA bioaccumulation patterns were observed in the kidney and liver during exposure- and after the recovery periods. Particularly, after the recovery period, PFOA levels in the kidney and liver tissues were almost at the control level. On the contrary, PFOS maintained an increase with tissue-specific differences, showing a higher bioaccumulation potential (also in the blood), compared with PFOA. While PFOS and PFOA produced an apparent time-dependent increase in kidney CYP3A, CYP1A1 and GST expression, similar effects were only temporary in the liver, significantly increasing at sampling day 2. PFOA and PFOS exposure resulted in significant decreases in plasma estrone, testosterone and cortisol levels at sampling day 2, and their effects differed with 17α-methyltestostrerone showing significant decrease by PFOA (also for cholesterol) and increase by PFOS. PFOA significantly increased estrone and testosterone, and no effects were observed for cortisol, 17α-methyltestosterone and cholesterol at sampling day 5. Overall, the changes in plasma steroid hormone levels parallel changes in CYP3A mRNA levels. Given that there are no known studies that have demonstrated such tissue differences in bioaccumulation patterns with associated differences in toxicological responses in any fish species or lower vertebrate, the present findings provide some potential insights and basis for a better understanding of the possible mechanisms of PFCs toxicity that need to be studied in more detail.
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Affiliation(s)
- Anne S Mortensen
- Department of Biology, Norwegian University of Science and Technology (NTNU), 7491 Trondheim, Norway
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137
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Löhr H, Hammerschmidt M. Zebrafish in Endocrine Systems: Recent Advances and Implications for Human Disease. Annu Rev Physiol 2011; 73:183-211. [DOI: 10.1146/annurev-physiol-012110-142320] [Citation(s) in RCA: 137] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Heiko Löhr
- Institute for Developmental Biology, University of Cologne, D-50923 Cologne, Germany
| | - Matthias Hammerschmidt
- Institute for Developmental Biology, University of Cologne, D-50923 Cologne, Germany
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CEDAD), University of Cologne, D-50923 Cologne, Germany
- Center for Molecular Medicine Cologne (CMMC), University of Cologne, D-50923 Cologne, Germany;
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138
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a Marca Pereira ML, Wheeler JR, Thorpe KL, Burkhardt-Holm P. Development of an ex vivo brown trout (Salmo trutta fario) gonad culture for assessing chemical effects on steroidogenesis. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2011; 101:500-511. [PMID: 21276476 DOI: 10.1016/j.aquatox.2010.12.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2010] [Revised: 12/08/2010] [Accepted: 12/13/2010] [Indexed: 05/30/2023]
Abstract
A variety of natural and synthetic environmental substances have been shown to disrupt vertebrate reproduction through mimicking or modifying the regulation of the endocrine system. Tests to screen for any such chemicals that directly interact with the steroid hormone receptors are widely available; however, few tests have been developed to identify chemicals that affect endocrine function through non-receptor mediated mechanisms. The aim of this study was, therefore, to develop an assay for the identification of substances that disrupt the activity of enzymes involved in the sex steroid biosynthesis cascade, in particular the aromatase enzyme, CYP19, that catalyses the final conversion of androgens to estrogens. A gonad ex vivo assay was developed using gonad explants harvested from juvenile brown trout and cultured in a modified Leibovitz medium. Effects on sex steroid biosynthesis were quantified through measurement of 17β-estradiol (E2) and testosterone (T) concentrations in the medium after 2 days incubation. Exposure of ovary explants to 100 ng/mL 1,4,6-androstatriene-3,17-dione (ATD), a potent pharmaceutical aromatase inhibitor, reduced E2 concentrations and elevated T concentrations confirming that CYP19 activity could be inhibited in the assay. Exposure of ovary explants to 250 ng/mL prochloraz, an imidazole fungicide, also reduced E2 concentrations but did not affect T levels, consistent with reports that in addition to inhibiting CYP19 activity, prochloraz also inhibits enzymes in the steroidogenic pathway upstream of the CYP19 enzyme. Exposure to a third chemical, tributyltin (TBT), did not affect T or E2 concentrations, further supporting previous evidence that the CYP19 modulating effects of this chemical are not mediated through direct inhibition of CYP19 activity. These results demonstrate that the gonad ex vivo assay developed here can be successfully used to identify substances that disrupt sex steroid biosynthesis and further that it has the potential to inform on their specific mode of action.
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Affiliation(s)
- M L a Marca Pereira
- Programm MGU Mensch-Gesellschaft-Umwelt, Department of Environmental Sciences, University of Basel, Vesalgasse 1, Basel, Switzerland.
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139
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Zucchi S, Blüthgen N, Ieronimo A, Fent K. The UV-absorber benzophenone-4 alters transcripts of genes involved in hormonal pathways in zebrafish (Danio rerio) eleuthero-embryos and adult males. Toxicol Appl Pharmacol 2011; 250:137-46. [DOI: 10.1016/j.taap.2010.10.001] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2010] [Revised: 09/30/2010] [Accepted: 10/02/2010] [Indexed: 12/27/2022]
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140
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Larsen MG, Baatrup E. Functional behavior and reproduction in androgenic sex reversed zebrafish (Danio rerio). ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2010; 29:1828-1833. [PMID: 20821638 DOI: 10.1002/etc.214] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Endocrine-disrupting chemicals released into natural watercourses may cause biased sex ratios by sex reversal in fish populations. The present study investigated the androgenic sex reversal of zebrafish (Danio rerio) exposed to the androgenic compound 17beta-trenbolone (TB) and whether sex-changed females would revert to the female phenotype after cessation of TB exposure. 17beta-Trenbolone is a metabolite of trenbolone acetate, an anabolic steroid used as a growth promoter in beef cattle. 17beta-Trenbolone in runoff from cattle feedlots may reach concentrations that affect fish sexual development. Zebrafish were exposed to a concentration of 20 ng/L TB in a flow-through system for five months from egg until sexual maturity. This resulted in an all-male population. It was further found that all these phenotypic males displayed normal male courtship behavior and were able to reproduce successfully, implying that the sex reversal was complete and functional. None of the phenotypic males developed into females after six months in clean water, demonstrating that androgenic sex reversal of zebrafish is irreversible.
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Affiliation(s)
- Mia G Larsen
- Department of Biological Sciences, Zoophysiology, University of Aarhus, C.F. Moellers Allé 3, Building 1131, DK-8000 Aarhus C, Denmark
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141
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Zhang D, Duarte-Guterman P, Langlois VS, Trudeau VL. Temporal expression and steroidal regulation of piRNA pathway genes (mael, piwi, vasa) during Silurana (Xenopus) tropicalis embryogenesis and early larval development. Comp Biochem Physiol C Toxicol Pharmacol 2010; 152:202-6. [PMID: 20388553 DOI: 10.1016/j.cbpc.2010.04.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/06/2009] [Revised: 03/21/2010] [Accepted: 04/07/2010] [Indexed: 12/24/2022]
Abstract
It has been extensively documented that exposure of amphibians and teleost fish to exogenous steroid hormones like estrogen, androgen, xenoestrogen or steroid biosynthesis inhibitors can impair their gonadal development or induce sex reversal against genotypic sex. However, the molecular pathways underlying sexual development and the effects of sex steroids or other exogenous hormones in these aquatic vertebrates remain elusive. Recently, a germ plasm-associated piRNA (piwi-interacting RNA) pathway has been shown to be a determinant in the development of animal gonadal germline cells. In the current study, we examined whether this piRNA pathway is involved in the regulation of sex steroid hormones in gonadal development. We firstly established developmental expression patterns of three key piRNA pathway genes (mael, piwi and vasa), during Silurana (Xenopus) tropicalis embryogenesis and early larval development. All three genes exhibit high expression at early developmental stages and have significantly decreased expression thereafter, indicating a very active involvement of piRNA pathway at the beginning of embryogenesis. We further examined gene expression changes of those genes in frog larvae exposed to two sex steroid biosynthesis inhibitors, fadrozole and finasteride, both of which are known to result in male-biased or female-biased phenotypes, respectively. We found that fadrozole and finasteride exposures increased the expression of piRNA pathway genes such as mael and vasa at the larval stage when the expression of piRNA pathway genes is programmed to be very low. Therefore, our results indicate that the piRNA pathway is likely a common pathway by which different sex steroid hormones regulate gonadal sex differentiation.
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Affiliation(s)
- Dapeng Zhang
- Centre for Advanced Research in Environmental Genomics, Department of Biology, University of Ottawa, Ottawa, Ontario, Canada K1N6N5
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142
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Rodríguez-Marí A, Cañestro C, BreMiller RA, Nguyen-Johnson A, Asakawa K, Kawakami K, Postlethwait JH. Sex reversal in zebrafish fancl mutants is caused by Tp53-mediated germ cell apoptosis. PLoS Genet 2010; 6:e1001034. [PMID: 20661450 PMCID: PMC2908690 DOI: 10.1371/journal.pgen.1001034] [Citation(s) in RCA: 149] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2010] [Accepted: 06/17/2010] [Indexed: 11/19/2022] Open
Abstract
The molecular genetic mechanisms of sex determination are not known for most vertebrates, including zebrafish. We identified a mutation in the zebrafish fancl gene that causes homozygous mutants to develop as fertile males due to female-to-male sex reversal. Fancl is a member of the Fanconi Anemia/BRCA DNA repair pathway. Experiments showed that zebrafish fancl was expressed in developing germ cells in bipotential gonads at the critical time of sexual fate determination. Caspase-3 immunoassays revealed increased germ cell apoptosis in fancl mutants that compromised oocyte survival. In the absence of oocytes surviving through meiosis, somatic cells of mutant gonads did not maintain expression of the ovary gene cyp19a1a and did not down-regulate expression of the early testis gene amh; consequently, gonads masculinized and became testes. Remarkably, results showed that the introduction of a tp53 (p53) mutation into fancl mutants rescued the sex-reversal phenotype by reducing germ cell apoptosis and, thus, allowed fancl mutants to become fertile females. Our results show that Fancl function is not essential for spermatogonia and oogonia to become sperm or mature oocytes, but instead suggest that Fancl function is involved in the survival of developing oocytes through meiosis. This work reveals that Tp53-mediated germ cell apoptosis induces sex reversal after the mutation of a DNA-repair pathway gene by compromising the survival of oocytes and suggests the existence of an oocyte-derived signal that biases gonad fate towards the female developmental pathway and thereby controls zebrafish sex determination.
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Affiliation(s)
- Adriana Rodríguez-Marí
- Institute of Neuroscience, University of Oregon, Eugene, Oregon, United States of America
| | - Cristian Cañestro
- Institute of Neuroscience, University of Oregon, Eugene, Oregon, United States of America
| | - Ruth A. BreMiller
- Institute of Neuroscience, University of Oregon, Eugene, Oregon, United States of America
| | | | - Kazuhide Asakawa
- Division of Molecular and Developmental Biology, National Institute of Genetics, Mishima, Shizuoka, Japan
- Department of Genetics, The Graduate University for Advanced Studies (Sokendai), Mishima, Shizuoka, Japan
| | - Koichi Kawakami
- Division of Molecular and Developmental Biology, National Institute of Genetics, Mishima, Shizuoka, Japan
- Department of Genetics, The Graduate University for Advanced Studies (Sokendai), Mishima, Shizuoka, Japan
| | - John H. Postlethwait
- Institute of Neuroscience, University of Oregon, Eugene, Oregon, United States of America
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143
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Morthorst JE, Holbech H, Bjerregaard P. Trenbolone causes irreversible masculinization of zebrafish at environmentally relevant concentrations. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2010; 98:336-43. [PMID: 20363039 DOI: 10.1016/j.aquatox.2010.03.008] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2010] [Revised: 03/05/2010] [Accepted: 03/08/2010] [Indexed: 05/16/2023]
Abstract
Feminization of fish caused by certain estrogenic compounds e.g. 17 alpha-ethinylestradiol (EE2) has been shown to be partly reversible. So far it has not been studied if this applies for androgenic compounds too. The androgenic steroid trenbolone acetate (TbA) is used as growth promoter in beef cattle in the United States, South America, and Australia. TbA metabolites are stable in animal waste and have been detected in surface waters associated with feedlot areas and studies on both fish and mammals have demonstrated a strong androgenic effect of those metabolites. Zebrafish (Danio rerio) were exposed to environmentally relevant concentrations of the TbA metabolite 17beta-trenbolone from 0 to 60 days post-hatch (dph) and either sacrificed at 60 dph, transferred to clean water for 170 days or kept in exposure for 170 days. At 60 dph gonadal histology and vitellogenin analyses revealed all-male populations in groups exposed to 15.5 and 26.2 ng/L, and at 9.2 ng/L a skewed sex ratio towards males was observed. After the depuration period no sign of reversibility was observed. Environmentally relevant concentrations of 17beta-trenbolone cause a strong and irreversible masculinization of zebrafish and that raises concern about the effects of androgenic discharges in the aquatic environment. In addition this study also aids in understanding of the so far unknown sex determination process in zebrafish.
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Affiliation(s)
- Jane E Morthorst
- Institute of Biology, University of Southern Denmark, Campusvej 55, Odense M, Denmark.
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144
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Ruksana S, Pandit NP, Nakamura M. Efficacy of exemestane, a new generation of aromatase inhibitor, on sex differentiation in a gonochoristic fish. Comp Biochem Physiol C Toxicol Pharmacol 2010; 152:69-74. [PMID: 20193775 DOI: 10.1016/j.cbpc.2010.02.014] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/18/2009] [Revised: 02/23/2010] [Accepted: 02/24/2010] [Indexed: 11/19/2022]
Abstract
We report the first use of exemestane (EM), a steroidal aromatase inhibitor (AI) commercially known as aromasin, in studies of sex differentiation in fish. The effectiveness of EM was examined in two different age groups of the gonochoristic fish, Nile tilapia (Oreochromis niloticus). Untreated control fish (all female) showed normal ovarian differentiation through 120 days after hatching (dah), whereas fish treated with EM at 1000 and 2000 microg/g of feed from 9 dah through 35 dah, the critical period for sex differentiation, exhibited complete testicular differentiation; all stages of spermatogenic germ cells were evident and well developed efferent ducts were present. Fish treated with EM at 1000 microg/g of feed from 70 dah through 100 dah significantly suppressed plasma estradiol-17beta level and increased level of 11-ketotestosterone. Furthermore, untreated control fish showed strong gonadal expression of the steroidogenic enzymes P450 cholesterol-side chain-cleavage enzyme (P450scc), 3beta-hydroxysteroid dehydrogenase (3beta-HSD), and cytochrome P450 aromatase (P450arom). In contrast, EM-treated fish showed immunopositive reactions against P450scc and 3beta-HSD but not against P450arom in interstitial Leydig cells. These results indicate that treatment of tilapia juveniles with EM during sex differentiation leads to the development of testes, apparently by a complete suppression of aromatase activity.
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Affiliation(s)
- Sabina Ruksana
- Sesoko Station, Tropical Biosphere Research Center, University of the Ryukyus, Sesoko 3422, Motobu, Okinawa 905-0227, Japan
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145
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Siegfried KR. In search of determinants: gene expression during gonadal sex differentiation. JOURNAL OF FISH BIOLOGY 2010; 76:1879-1902. [PMID: 20557645 DOI: 10.1111/j.1095-8649.2010.02594.x] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The diversity of inputs that guide sexual fate during development is both intriguing and daunting. In the field of fish biology, the study of sex determination is of great importance. For example, in aquaculture, sexually dimorphic growth rates and overall size leads to one sex being more marketable than the other. Moreover, for breeding purposes it is important to maintain balanced sex ratios. Furthermore, sex determination is sensitive to environmental factors, such as temperature and contaminants, which can lead to skewed sex ratios, intersexes and sterility in wild or farmed fish. The gonad is typically the first organ to exhibit morphological signs of sexual dimorphism and therefore is likely to be the primary organ system whose fate is controlled by the sex determination cues in many fish species. Additionally, the sexual fate of the gonad has been shown to fully or partially control organismal sex differentiation. Thus, understanding the genetic regulation of gonadal sex differentiation is critical in studies of fish sex determination. This review summarizes recent knowledge of genes expressed during gonadal sex differentiation in gonochoristic teleost fish. Three species are discussed, which serve as excellent model systems for probing teleost sex differentiation: the Oreochromis niloticus, Oryzias latipes and Danio rerio. The similarities and differences between gonadal gene expression in these three species and in comparison to mammals suggest conserved roles during vertebrate gonadal sex differentiation. In the future, it will be essential to develop tools to assay the function of genes expressed during gonadal sex differentiation in fish.
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Affiliation(s)
- K R Siegfried
- Max Planck Institute for Developmental Biology, Department of Genetics, Spemannstrasse 35, 72076 Tuebingen, Germany.
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146
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Neumann JC, Dovey JS, Chandler GL, Carbajal L, Amatruda JF. Identification of a heritable model of testicular germ cell tumor in the zebrafish. Zebrafish 2010; 6:319-27. [PMID: 20047465 DOI: 10.1089/zeb.2009.0613] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Germ cell tumors (GCTs) affect infants, children, and adults and are the most common cancer type in young men. Progress in understanding the molecular basis of GCTs has been hampered by a lack of suitable animal models. Here we report the identification of a zebrafish model of highly penetrant, heritable testicular GCT isolated as part of a forward genetic screen for cancer susceptibility genes. The mutant line develops spontaneous testicular tumors at a median age of 7 months, and pedigree analysis indicates dominant inheritance of the GCT susceptibility trait. The zebrafish model exhibits disruption of testicular tissue architecture and the accumulation of primitive, spermatogonial-like cells with loss of spermatocytic differentiation. Radiation treatment leads to apoptosis of the tumor cells and tumor regression. The GCT-susceptible line can serve as a model for understanding the mechanisms regulating germ cells in normal development and disease and as a platform investigating new therapeutic approaches for GCTs.
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Affiliation(s)
- Joanie C Neumann
- Department of Pediatrics, UT Southwestern Medical Center, Dallas, Texas, USA
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147
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Gust M, Garric J, Giamberini L, Mons R, Abbaci K, Garnier F, Buronfosse T. Sensitivity of New Zealand mudsnail Potamopyrgus antipodarum (Gray) to a specific aromatase inhibitor. CHEMOSPHERE 2010; 79:47-53. [PMID: 20153502 DOI: 10.1016/j.chemosphere.2010.01.030] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2009] [Revised: 01/15/2010] [Accepted: 01/15/2010] [Indexed: 05/28/2023]
Abstract
The freshwater prosobranch Potamopyrgus antipodarum (Molluska, Hydrobiidea, Smith 1889) has been proposed as a suitable species to assess the impact of endocrine disrupting compounds (EDC) in aquatic ecosystems. Steroid hormone biosynthesis pathway is potentially an important target for EDC, and vertebrate-like sex steroids seem to play a functional role in the control of mollusk reproduction. To assess the response and the sensitivity of P. antipodarum to disrupters of the steroid hormone biosynthesis pathway, we have experienced the action of a specific vertebrate aromatase inhibitor, fadrozole, acting on 17beta-estradiol synthesis in two separate 28 and 42d exposures. Fadrozole had effects consistent with the expected mechanism of action. A decrease of the reproduction parameters (such as on the number of neonates and number of embryos in the brood pouch) in a dose-dependant manner was observed. The steroids levels were also impaired with the ratio 17beta-estradiol/testosterone decreased by half in exposed snails. This shift of the steroids balance was accompanied by some alteration in the gonads histology and immunohistochemistry in fadrozole-exposed snails. This study highlights the value role of P. antipodarum as a test species for assessing EDC effects in aquatic wildlife.
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Affiliation(s)
- M Gust
- Cemagref, UR MALY, Laboratoire d'écotoxicologie, 3b quai Chauveau 69009 Lyon, France; AgroPariTech ENGREF, 19 Avenue du Maine, F 75732 Paris, France.
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148
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Guiguen Y, Fostier A, Piferrer F, Chang CF. Ovarian aromatase and estrogens: a pivotal role for gonadal sex differentiation and sex change in fish. Gen Comp Endocrinol 2010; 165:352-66. [PMID: 19289125 DOI: 10.1016/j.ygcen.2009.03.002] [Citation(s) in RCA: 411] [Impact Index Per Article: 29.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/11/2008] [Revised: 02/23/2009] [Accepted: 03/03/2009] [Indexed: 10/21/2022]
Abstract
The present review focuses on the roles of estrogens and aromatase (Cyp19a1a), the enzyme needed for their synthesis, in fish gonadal sex differentiation. Based on the recent literature, we extend the already well accepted hypothesis of an implication of estrogens and Cyp19a1a in ovarian differentiation to a broader hypothesis that would place estrogens and Cyp19a1a in a pivotal position to control not only ovarian, but also testicular differentiation, in both gonochoristic and hermaphrodite fish species. This working hypothesis states that cyp19a1a up-regulation is needed not only for triggering but also for maintaining ovarian differentiation and that cyp19a1a down-regulation is the only necessary step for inducing a testicular differentiation pathway. When considering arguments for and against, most of the information available for fish supports this hypothesis since either suppression of cyp19a1a gene expression, inhibition of Cyp19a1a enzymatic activity, or blockage of estrogen receptivity are invariably associated with masculinization. This is also consistent with reports on normal gonadal differentiation, and steroid-modulated masculinization with either androgens, aromatase inhibitors or estrogen receptor antagonists, temperature-induced masculinization and protogynous sex change in hermaphrodite species. Concerning the regulation of fish cyp19a1a during gonadal differentiation, the transcription factor foxl2 has been characterized as an ovarian specific upstream regulator of a cyp19a1a promoter that would co-activate cyp19a1a expression, along with some additional partners such as nr5a1 (sf1) or cAMP. In contrast, upstream factors potentially down-regulating cyp19a1a during testicular differentiation are still hypothetical, such as the dmrt1 gene, but their definitive characterization as testicular repressors of cyp19a1a would strongly strengthen the hypothesis that early testicular differentiation would need active repression of cyp19a1a expression.
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Affiliation(s)
- Yann Guiguen
- INRA, UR1037 SCRIBE, IFR140, Ouest-Genopole, F-35000 Rennes, France.
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149
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Clelland E, Peng C. Endocrine/paracrine control of zebrafish ovarian development. Mol Cell Endocrinol 2009; 312:42-52. [PMID: 19406202 DOI: 10.1016/j.mce.2009.04.009] [Citation(s) in RCA: 186] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2008] [Revised: 04/16/2009] [Accepted: 04/17/2009] [Indexed: 12/11/2022]
Abstract
Ovarian differentiation and the processes of follicle development, oocyte maturation and ovulation are complex events, requiring the coordinated action of regulatory molecules. In zebrafish, ovarian development is initiated at 10 days after hatching and fish become sexually mature at 3 months. Adult zebrafish have asynchronous ovaries, which contain follicles of all stages of development. Eggs are spawned daily under proper environmental conditions in a population of zebrafish, with individual females spawning irregularly every 4-7 days in mixed sex conditions. Maximal embryo viability is achieved when sexually isolated females are bred in 10-day intervals [Niimi, A.J., LaHam, Q.N., 1974. Influence of breeding time interval on egg number, mortality, and hatching of the zebra fish Brachydanio verio. Can. J. Zool. 52, 515-517]. Similar to other vertebrates, hormones from the hypothalamus-pituitary-gonadal axis play important roles in regulating follicle development. Follicle stimulating hormone (FSH) stimulates estradiol production, which in turn, promotes viteollogenesis. Luteinizing hormone (LH) stimulates the production of 17,20beta-dihydroxy-4-pregnen-3-one (17,20betaP) or maturation inducing hormone (MIH) which acts through membrane progestin receptors to activate maturation promoting factor, leading to oocyte maturation. Recent studies in zebrafish have also provided novel insights into the functions of ovary-derived growth factors in follicle development and oocyte maturation. The present review summarizes the current knowledge on how endocrine and paracrine factors regulate ovarian development in zebrafish. Special emphasis is placed on how follicle development and oocyte maturation in adult females is regulated by gonadotropins, ovarian steroids and growth factors produced by the ovary.
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Affiliation(s)
- Eric Clelland
- Department of Biology, York University, 4700 Keele Street, Toronto, Ontario M3J 1P3, Canada
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150
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Orban L, Sreenivasan R, Olsson PE. Long and winding roads: testis differentiation in zebrafish. Mol Cell Endocrinol 2009; 312:35-41. [PMID: 19422878 DOI: 10.1016/j.mce.2009.04.014] [Citation(s) in RCA: 114] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/24/2008] [Revised: 03/31/2009] [Accepted: 04/25/2009] [Indexed: 02/02/2023]
Abstract
Zebrafish sex determination, gonad differentiation and reproduction are far from being fully understood. Although the mode of sex determination is still being disputed, most experimental data point towards the lack of sex chromosomes and a multigenic sex determination system. Secondary effects from the environment and/or (xeno)hormones may influence the process, resulting in biased sex ratios. The exact time point of sex determination is unknown. Gonad differentiation involves a compulsory 'juvenile ovary' stage with subsequent transformation of the gonad into a testis in males. As the latter is a late event, there is a delay between sex determination and testis differentiation in zebrafish, in contrast to mammals. Information on the expression of several candidate genes thought to be involved in these processes has been supplemented with data from large-scale gonadal transcriptomic studies. New approaches and methodologies provide hope that answers to a number of important questions will be deciphered in the future.
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Affiliation(s)
- Laszlo Orban
- Reproductive Genomics Group, Strategic Research Program, Temasek Life Sciences Laboratory, Singapore.
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