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Chen R, Zhu H, Zhang X, Li L, Xu J, Tan Z, Su J, Feng K, Chen K, Xu H. Characterization and Functional Analysis of the 17-Beta Hydroxysteroid Dehydrogenase 2 ( hsd17b2) Gene during Sex Reversal in the Ricefield Eel ( Monopterus albus). Int J Mol Sci 2024; 25:9063. [PMID: 39201749 PMCID: PMC11354438 DOI: 10.3390/ijms25169063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2024] [Revised: 08/03/2024] [Accepted: 08/05/2024] [Indexed: 09/03/2024] Open
Abstract
In mammals, 17-beta hydroxysteroid dehydrogenase 2 (Hsd17b2) enzyme specifically catalyzes the oxidation of the C17 hydroxyl group and efficiently regulates the activities of estrogens and androgens to prevent diseases induced by hormone disorders. However, the functions of the hsd17b2 gene involved in animal sex differentiation are still largely unclear. The ricefield eel (Monopterus albus), a protogynous hermaphroditic fish with a small genome size (2n = 24), is usually used as an ideal model to study the mechanism of sex differentiation in vertebrates. Therefore, in this study, hsd17b2 gene cDNA was cloned and its mRNA expression profiles were determined in the ricefield eel. The cloned cDNA fragment of hsd17b2 was 1230 bp, including an open reading frame of 1107 bp, encoding 368 amino acid residues with conserved catalytic subunits. Moreover, real-time quantitative reverse transcription polymerase chain reaction (RT-qPCR) analysis showed that hsd17b2 mRNA expressed strongly in the ovaries at early developmental stages, weakly in liver and intestine, and barely in testis and other tissues. In particular, hsd17b2 mRNA expression was found to peak in ovaries of young fish and ovotestis at the early stage, and eventually declined in gonads from the late ovotestis to testis. Likewise, chemical in situ hybridization results indicated that the hsd17b2 mRNA signals were primarily detected in the cytoplasm of oogonia and oocytes at stage I-II, subsequently concentrated in the granulosa cells around the oocytes at stage Ⅲ-Ⅳ, but undetectable in mature oocytes and male germ cells. Intriguingly, in ricefield eel ovaries, hsd17b2 mRNA expression could be significantly reduced by 17β-estradiol (E2) or tamoxifen (17β-estradiol inhibitor, E2I) induction at a low concentration (10 ng/mL) and increased by E2I induction at a high concentration (100 ng/mL). On the other hand, both the melatonin (MT) and flutamide (androgen inhibitor, AI) induction could significantly decrease hsd17b2 mRNA expression in the ovary of ricefield eel. This study provides a clue for demonstrating the mechanism of sexual differentiation in fish. The findings of our study imply that the hsd17b2 gene could be a key regulator in sexual differentiation and modulate sex reversal in the ricefield eel and other hermaphroditic fishes.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Kaili Chen
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City & College of Fisheries, Key Laboratory of Freshwater Fish Reproduction and Development Ministry of Education, Key Laboratory of Aquatic Sciences of Chongqing, Southwest University, Chongqing 402460, China; (R.C.); (H.Z.); (X.Z.); (L.L.); (J.X.); (Z.T.); (J.S.); (K.F.)
| | - Hongyan Xu
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City & College of Fisheries, Key Laboratory of Freshwater Fish Reproduction and Development Ministry of Education, Key Laboratory of Aquatic Sciences of Chongqing, Southwest University, Chongqing 402460, China; (R.C.); (H.Z.); (X.Z.); (L.L.); (J.X.); (Z.T.); (J.S.); (K.F.)
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2
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Fan M, Yang W, Zhang W, Zhang L. The ontogenic gonadal transcriptomes provide insights into sex change in the ricefield eel Monopterus albus. BMC ZOOL 2022; 7:56. [PMID: 37170354 PMCID: PMC10127409 DOI: 10.1186/s40850-022-00155-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2022] [Accepted: 10/20/2022] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND The ricefield eel is a freshwater protogynous hermaphrodite fish and has become an important aquaculture species in China. The sex change of ricefield eel is impeding its aquaculture practice, particularly the large-scale artificial breeding. Many studies including transcriptomes of mixed gonadal samples from different individuals have been aimed to elucidate mechanisms underlying the sex change. However, the key physiological factors involved in the initiation of sex change remain to be identified. RESULTS: The present study performed transcriptomic analysis on gonadal samples of different sexual stages obtained through biopsy from the same fish undergoing sex change. A total of 539,764,816 high-quality reads were generated from twelve cDNA libraries of gonadal tissues at female (F), early intersexual (EI), mid-intersexual (MI), and late intersexual (LI) stages of three individual sex-changing fish. Pairwise comparisons between EI and F, MI and EI, and LI and MI identified 886, 319, and 10,767 differentially expressed genes (DEGs), respectively. Realtime quantitative PCR analysis of 12 representative DEGs showed similar expression profiles to those inferred from transcriptome data, suggesting the reliability of RNA-seq data for gene expression analysis. The expression of apoeb, csl2, and enpp2 was dramatically increased and peaked at EI while that of cyp19a1a, wnt4a, fgf16, and foxl2a significantly downregulated from F to EI and remained at very low levels during subsequent development until LI, which suggests that apoeb, csl2, enpp2, cyp19a1a, wnt4a, fgf16, and foxl2a may be closely associated with the initiation of sex change of ricefield eels. CONCLUSIONS Collectively, results of the present study confirmed that the down-regulation of female-related genes, such as cyp19a1a, wnt4a, fgf16, and foxl2a, is important for the sex change of ricefield eels. More importantly, some novel genes, including apoeb, csl2, and enpp2, were shown to be expressed with peak values at EI, which are potentially involved in the initiation of sex change. The present transcriptomic data may provide an important research resource for further unraveling the mechanisms underlying the sex change and testicular development in ricefield eels as well as other teleosts.
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Affiliation(s)
- Miao Fan
- Institute of Aquatic Economic Animals and Guangdong Province Key Laboratory for Aquatic Economic Animals, School of Life Sciences, Sun Yat-Sen University, Guangzhou, People's Republic of China
| | - Wei Yang
- Institute of Aquatic Economic Animals and Guangdong Province Key Laboratory for Aquatic Economic Animals, School of Life Sciences, Sun Yat-Sen University, Guangzhou, People's Republic of China
- Present address: Institute of Biomedical Engineering, Shenzhen People's Hospital (The Second Clinical Medical College, Jinan University; The First Affiliated Hospital, Southern University of Science and Technology), Shenzhen, 518020, Guangdong, People's Republic of China
| | - Weimin Zhang
- Institute of Aquatic Economic Animals and Guangdong Province Key Laboratory for Aquatic Economic Animals, School of Life Sciences, Sun Yat-Sen University, Guangzhou, People's Republic of China.
- Biology Department, School of Life Sciences, Sun Yat-Sen University, Guangzhou, People's Republic of China.
| | - Lihong Zhang
- Institute of Aquatic Economic Animals and Guangdong Province Key Laboratory for Aquatic Economic Animals, School of Life Sciences, Sun Yat-Sen University, Guangzhou, People's Republic of China.
- Biology Department, School of Life Sciences, Sun Yat-Sen University, Guangzhou, People's Republic of China.
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3
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Dunleavy JEM, Dinh DT, Filby CE, Green E, Hofstee P, Pini T, Rivers N, Skerrett-Byrne DA, Wijayarathna R, Winstanley YE, Zhou W, Richani D. Reproductive biology research down under: highlights from the Australian and New Zealand Annual Meeting of the Society for Reproductive Biology, 2021. Reprod Fertil Dev 2022; 34:855-866. [PMID: 35836362 DOI: 10.1071/rd22115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Accepted: 06/17/2022] [Indexed: 11/23/2022] Open
Abstract
Against the backdrop of a global pandemic, the Society for Reproductive Biology (SRB) 2021 meeting reunited the Australian and New Zealand reproductive research community for the first time since 2019 and was the first virtual SRB meeting. Despite the recent global research disruptions, the conference revealed significant advancements in reproductive research, the importance of which span human health, agriculture, and conservation. A core theme was novel technologies, including the use of medical microrobots for therapeutic and sperm delivery, diagnostic hyperspectral imaging, and hydrogel condoms with potential beyond contraception. The importance of challenging the contraceptive status quo was further highlighted with innovations in gene therapies, non-hormonal female contraceptives, epigenetic semen analysis, and in applying evolutionary theory to suppress pest population reproduction. How best to support pregnancies, particularly in the context of global trends of increasing maternal age, was also discussed, with several promising therapies for improved outcomes in assisted reproductive technology, pre-eclampsia, and pre-term birth prevention. The unique insights gained via non-model species was another key focus and presented research emphasised the importance of studying diverse systems to understand fundamental aspects of reproductive biology and evolution. Finally, the meeting highlighted how to effectively translate reproductive research into policy and industry practice.
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Affiliation(s)
- Jessica E M Dunleavy
- School of BioSciences, Faculty of Science, The University of Melbourne, Parkville, Vic. 3010, Australia
| | - Doan Thao Dinh
- Robinson Research Institute, School of Biomedicine, Faculty of Health Sciences, The University of Adelaide, Adelaide, SA 5006, Australia
| | - Caitlin E Filby
- The Ritchie Centre, Hudson Institute of Medical Research, Clayton, Vic. 3168, Australia; and Department of Obstetrics and Gynaecology, School of Clinical Sciences, Monash University, Clayton, Vic. 3168, Australia
| | - Ella Green
- Robinson Research Institute and Adelaide Medical School, The University of Adelaide, Adelaide, SA 5006, Australia
| | - Pierre Hofstee
- Faculty of Science, Medicine and Health, University of Wollongong, Wollongong, NSW 2522, Australia
| | - Taylor Pini
- School of Veterinary Science, The University of Queensland, Gatton, Qld 4343, Australia
| | - Nicola Rivers
- Department of Obstetrics and Gynaecology, School of Clinical Sciences, Monash University, Clayton, Vic. 3168, Australia
| | - David A Skerrett-Byrne
- School of Environmental and Life Sciences, College of Engineering, Science and Environment, The University of Newcastle, Callaghan, NSW 2308, Australia; and Infertility and Reproduction Research Program, Hunter Medical Research Institute, New Lambton, NSW 2305, Australia
| | - Rukmali Wijayarathna
- Centre for Reproductive Health, Hudson Institute of Medical Research, Clayton, Vic. 3168, Australia; and Department of Molecular and Translational Sciences, School of Clinical Sciences, Monash University, Clayton, Vic. 3800, Australia
| | - Yasmyn E Winstanley
- Robinson Research Institute, School of Biomedicine, Faculty of Health Sciences, The University of Adelaide, Adelaide, SA 5006, Australia
| | - Wei Zhou
- Department of Obstetrics and Gynaecology, The University of Melbourne, Parkville, Vic. 3010, Australia; and Gynaecology Research Centre, Royal Women's Hospital, Parkville, Vic. 3052, Australia
| | - Dulama Richani
- Fertility & Research Centre, School of Women's and Children's Health, University of New South Wales, Sydney, NSW 2031, Australia
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Tian HF, Hu Q, Lu HY, Li Z. Chromosome-Scale, Haplotype-Resolved Genome Assembly of Non-Sex-Reversal Females of Swamp Eel Using High-Fidelity Long Reads and Hi-C Data. Front Genet 2022; 13:903185. [PMID: 35669182 PMCID: PMC9165713 DOI: 10.3389/fgene.2022.903185] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Accepted: 04/04/2022] [Indexed: 11/13/2022] Open
Abstract
The Asian swamp eel (Monopterus albus) is an excellent model species for studying sex change and chromosome evolution. M. albus is also widely reared in East Asia and South-East Asia because of its great nutritional value. The low fecundity of this species (about 300 eggs per fish) greatly hinders fries production and breeding programs. Interestingly, about 3–5% of the eels could remain as females for 3 years and lay more than 3,000 eggs per fish, which are referred to as non-sex-reversal (NSR) females. Here, we presented a new chromosome-level genome assembly of such NSR females using Illumina, HiFi, and Hi-C sequencing technologies. The new assembly (Mal.V2_NSR) is 838.39 Mb in length, and the N50 of the contigs is 49.8 Mb. Compared with the previous assembly obtained using the continuous long-read sequencing technology (Mal.V1_CLR), we found a remarkable increase of continuity in the new assembly Mal.V2_NSR with a 20-times longer contig N50. Chromosomes 2 and 12 were assembled into a single contig, respectively. Meanwhile, two highly contiguous haplotype assemblies were also obtained, with contig N50 being 14.54 and 12.13 Mb, respectively. BUSCO and Merqury analyses indicate completeness and high accuracy of these three assemblies. A comparative genomic analysis revealed substantial structural variations (SVs) between Mal.V2_NSR and Mal.V1_CLR and two phased haplotype assemblies, as well as whole chromosome fusion events when compared with the zig-zag eel. Additionally, our newly obtained assembly provides a genomic view of sex-related genes and a complete landscape of the MHC genes. Therefore, these high-quality genome assemblies would provide great help for future breeding works of the swamp eel, and it is a valuable new reference for genetic and genomic studies of this species.
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Affiliation(s)
- Hai-Feng Tian
- Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan, China
| | - Qiaomu Hu
- Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan, China
| | - Hong-Yi Lu
- Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan, China
- College of Fisheries, Huazhong Agricultural University, Wuhan, China
| | - Zhong Li
- Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan, China
- *Correspondence: Zhong Li,
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5
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Whiteley SL, Georges A, Weisbecker V, Schwanz LE, Holleley CE. Ovotestes suggest cryptic genetic influence in a reptile model for temperature-dependent sex determination. Proc Biol Sci 2021; 288:20202819. [PMID: 33467998 DOI: 10.1098/rspb.2020.2819] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Sex determination and differentiation in reptiles is complex. Temperature-dependent sex determination (TSD), genetic sex determination (GSD) and the interaction of both environmental and genetic cues (sex reversal) can drive the development of sexual phenotypes. The jacky dragon (Amphibolurus muricatus) is an attractive model species for the study of gene-environment interactions because it displays a form of Type II TSD, where female-biased sex ratios are observed at extreme incubation temperatures and approximately 50 : 50 sex ratios occur at intermediate temperatures. This response to temperature has been proposed to occur due to underlying sex determining loci, the influence of which is overridden at extreme temperatures. Thus, sex reversal at extreme temperatures is predicted to produce the female-biased sex ratios observed in A. muricatus. The occurrence of ovotestes during development is a cellular marker of temperature sex reversal in a closely related species Pogona vitticeps. Here, we present the first developmental data for A. muricatus, and show that ovotestes occur at frequencies consistent with a mode of sex determination that is intermediate between GSD and TSD. This is the first evidence suggestive of underlying unidentified sex determining loci in a species that has long been used as a model for TSD.
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Affiliation(s)
- Sarah L Whiteley
- Institute for Applied Ecology, University of Canberra, Canberra, Australia.,Australian National Wildlife Collection, CSIRO, Canberra, Australia
| | - Arthur Georges
- Institute for Applied Ecology, University of Canberra, Canberra, Australia
| | - Vera Weisbecker
- College of Science and Engineering, Flinders University, Adelaide, Australia
| | - Lisa E Schwanz
- Evolution and Ecology Research Centre, School of Biological, Earth and Environmental Sciences, UNSW, Sydney, Australia
| | - Clare E Holleley
- Australian National Wildlife Collection, CSIRO, Canberra, Australia
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6
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Li S, Lin G, Fang W, Huang P, Gao D, Huang J, Xie J, Lu J. Gonadal Transcriptome Analysis of Sex-Related Genes in the Protandrous Yellowfin Seabream ( Acanthopagrus latus). Front Genet 2020; 11:709. [PMID: 32765585 PMCID: PMC7378800 DOI: 10.3389/fgene.2020.00709] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Accepted: 06/11/2020] [Indexed: 12/13/2022] Open
Abstract
Yellowfin seabream (Acanthopagrus latus), a protandrous hermaphroditic fish, is a good model for studying the mechanism of sex reversal. However, limited knowledge is known about the genetic information related to reproduction and sex differentiation in this species. Here, we performed de novo transcriptome sequencing analysis of the testis, ovotestis, and ovary to identify sex-related genes in yellowfin seabream. The results assembled 71,765 unigenes in which 16,126 and 17,560 unigenes were differentially expressed in the ovotestis and ovary compared to the testis, respectively. The most differentially expressed gene (DEG)-enriched Kyoto Encyclopedia of Genes and Genomes and GO pathways were closely associated with the synthesis of sex steroid hormones. Functional analyses identified 55 important sex-related DEGs, including 32 testis-biased DEGs (dmrt1, amh, and sox9, etc.), 20 ovary-biased DEGs (cyp19a, foxl2, and wnt4, etc.), and 3 ovotestis-biased DEGs (lhb, dmrt2, and foxh1). Furthermore, the testis-specific expression of dmrt1 and the brain-pituitary-ovary axis expression of foxl2 were characterized, suggesting that they might play important roles in sex differentiation in yellowfin seabream. Our present work provided an important molecular basis for elucidating the mechanisms underlying sexual transition and reproductional regulation in yellowfin seabream.
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Affiliation(s)
- Shizhu Li
- School of Marine Sciences, Sun Yat-sen University, Zhuhai, China
| | - Genmei Lin
- School of Marine Sciences, Sun Yat-sen University, Zhuhai, China
| | - Wenyu Fang
- School of Marine Sciences, Sun Yat-sen University, Zhuhai, China
| | - Peilin Huang
- School of Marine Sciences, Sun Yat-sen University, Zhuhai, China
| | - Dong Gao
- School of Marine Sciences, Sun Yat-sen University, Zhuhai, China
| | - Jing Huang
- School of Marine Sciences, Sun Yat-sen University, Zhuhai, China
| | - Jingui Xie
- School of Marine Sciences, Sun Yat-sen University, Zhuhai, China
| | - Jianguo Lu
- School of Marine Sciences, Sun Yat-sen University, Zhuhai, China
- Southern Marine Science and Engineering Guangdong Laboratory, Zhuhai, China
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7
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Ozaki Y, Damsteegt EL, Setiawan AN, Miura T, Lokman PM. Expressional regulation of gonadotropin receptor genes and androgen receptor genes in the eel testis. Gen Comp Endocrinol 2019; 280:123-133. [PMID: 31009604 DOI: 10.1016/j.ygcen.2019.04.020] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Revised: 04/17/2019] [Accepted: 04/17/2019] [Indexed: 11/17/2022]
Abstract
Receptors for follicle-stimulating hormone (Fshr), luteinizing hormone (Lhcgr1 and Lhcgr2) and androgens (Ara and Arb) transduce the hormonal signals that coordinate spermatogenesis, but the factors that regulate the abundance of these transducers in fish testes remain little-understood. To mend this paucity of information, we first determined changes in transcript abundance for these receptors (fshr, lhcgr1, ara and arb) during spermatogenesis induced by human chorionic gonadotropin (hCG) injection in the eel, Anguilla australis. We related our findings to testicular production of the fish androgen, 11-ketotestosterone (11-KT), and to the levels of the transcripts encoding steroidogenic acute regulatory protein (star) and 11β-hydroxylase (cyp11b), and subsequently evaluated the effects of hCG or 11-KT on mRNA levels of these target genes in vitro. Testicular 11-KT production was greatly increased by hCG treatment, both in vivo and in vitro, and associated with up-regulation of star and cyp11b transcripts. In situ hybridization indicated that testicular fshr mRNA levels were higher in the early stages of hCG-induced spermatogenesis, while lhcgr1 transcripts were most abundant later, once spermatids were observed. In vitro experiments further showed that hCG and its steroidal mediator 11-KT significantly increased fshr transcript abundance. These data provide new angles on the interactions between gonadotropin and androgen signaling during early spermatogenesis. Increases in levels of 11-KT following hCG injection elevated testicular fshr mRNA levels augmenting Fsh sensitivity in the testis. This evidence is suggestive of a positive feedback loop between gonadotropins and 11-KT that may be key to regulating early spermatogenesis in fish.
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MESH Headings
- Androgens/metabolism
- Anguilla/blood
- Anguilla/genetics
- Animals
- Chorionic Gonadotropin/administration & dosage
- Chorionic Gonadotropin/pharmacology
- Gene Expression Regulation/drug effects
- Humans
- Male
- Phosphoproteins/genetics
- Phosphoproteins/metabolism
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Receptors, Androgen/genetics
- Receptors, Androgen/metabolism
- Receptors, FSH/genetics
- Receptors, FSH/metabolism
- Receptors, Gonadotropin/genetics
- Receptors, Gonadotropin/metabolism
- Receptors, LH/genetics
- Receptors, LH/metabolism
- Spermatogenesis/drug effects
- Spermatogenesis/genetics
- Steroid 11-beta-Hydroxylase/genetics
- Steroid 11-beta-Hydroxylase/metabolism
- Testis/drug effects
- Testis/metabolism
- Testosterone/analogs & derivatives
- Testosterone/blood
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Affiliation(s)
- Yuichi Ozaki
- Department of Zoology, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand
| | - Erin L Damsteegt
- Department of Zoology, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand.
| | - Alvin N Setiawan
- Department of Zoology, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand
| | - Takeshi Miura
- Graduate School of Agriculture, Ehime University, 3-5-7 Tarumi, Matsuyama, Ehime 790 8566, Japan
| | - P Mark Lokman
- Department of Zoology, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand
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8
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Thomas JT, Todd EV, Muncaster S, Lokman PM, Damsteegt EL, Liu H, Soyano K, Gléonnec F, Lamm MS, Godwin JR, Gemmell NJ. Conservation and diversity in expression of candidate genes regulating socially-induced female-male sex change in wrasses. PeerJ 2019; 7:e7032. [PMID: 31218121 PMCID: PMC6568253 DOI: 10.7717/peerj.7032] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2018] [Accepted: 04/27/2019] [Indexed: 01/06/2023] Open
Abstract
Fishes exhibit remarkably diverse, and plastic, patterns of sexual development, most striking of which is sequential hermaphroditism, where individuals readily reverse sex in adulthood. How this stunning example of phenotypic plasticity is controlled at a genetic level remains poorly understood. Several genes have been implicated in regulating sex change, yet the degree to which a conserved genetic machinery orchestrates this process has not yet been addressed. Using captive and in-the-field social manipulations to initiate sex change, combined with a comparative qPCR approach, we compared expression patterns of four candidate regulatory genes among three species of wrasses (Labridae)-a large and diverse teleost family where female-to-male sex change is pervasive, socially-cued, and likely ancestral. Expression in brain and gonadal tissues were compared among the iconic tropical bluehead wrasse (Thalassoma bifasciatum) and the temperate spotty (Notolabrus celidotus) and kyusen (Parajulus poecilepterus) wrasses. In all three species, gonadal sex change was preceded by downregulation of cyp19a1a (encoding gonadal aromatase that converts androgens to oestrogens) and accompanied by upregulation of amh (encoding anti-müllerian hormone that primarily regulates male germ cell development), and these genes may act concurrently to orchestrate ovary-testis transformation. In the brain, our data argue against a role for brain aromatase (cyp19a1b) in initiating behavioural sex change, as its expression trailed behavioural changes. However, we find that isotocin (it, that regulates teleost socio-sexual behaviours) expression correlated with dominant male-specific behaviours in the bluehead wrasse, suggesting it upregulation mediates the rapid behavioural sex change characteristic of blueheads and other tropical wrasses. However, it expression was not sex-biased in temperate spotty and kyusen wrasses, where sex change is more protracted and social groups may be less tightly-structured. Together, these findings suggest that while key components of the molecular machinery controlling gonadal sex change are phylogenetically conserved among wrasses, neural pathways governing behavioural sex change may be more variable.
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Affiliation(s)
- Jodi T. Thomas
- ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, Queensland, Australia
- Department of Anatomy, University of Otago, Dunedin, Otago, New Zealand
| | - Erica V. Todd
- Department of Anatomy, University of Otago, Dunedin, Otago, New Zealand
| | - Simon Muncaster
- Faculty of Primary Industries, Environment and Science, Toi Ohomai Institute of Technology, Tauranga, Bay of Plenty, New Zealand
| | - P Mark Lokman
- Department of Zoology, University of Otago, Dunedin, Otago, New Zealand
| | - Erin L. Damsteegt
- Department of Zoology, University of Otago, Dunedin, Otago, New Zealand
| | - Hui Liu
- Department of Anatomy, University of Otago, Dunedin, Otago, New Zealand
| | - Kiyoshi Soyano
- Institute for East China Sea Research, Organization for Marine Science and Technology, Nagasaki University, Taira-machi, Nagasaki, Japan
| | - Florence Gléonnec
- Department of Anatomy, University of Otago, Dunedin, Otago, New Zealand
- BIOSIT - Structure Fédérative de Recherche en Biologie-Santé de Rennes, Université Rennes I, Rennes, France
| | - Melissa S. Lamm
- Department of Biological Sciences and WM Keck Center for Behavioral Biology, North Carolina State University, Raleigh, NC, United States of America
| | - John R. Godwin
- Department of Biological Sciences and WM Keck Center for Behavioral Biology, North Carolina State University, Raleigh, NC, United States of America
| | - Neil J. Gemmell
- Department of Anatomy, University of Otago, Dunedin, Otago, New Zealand
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9
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Abstract
Sexual fate can no longer be considered an irreversible deterministic process that once established during early embryonic development, plays out unchanged across an organism's life. Rather, it appears to be a dynamic process, with sexual phenotype determined through an ongoing battle for supremacy between antagonistic male and female developmental pathways. That sexual fate is not final and is actively regulated via the suppression or activation of opposing genetic networks creates the potential for flexibility in sexual phenotype in adulthood. Such flexibility is seen in many fish, where sex change is a usual and adaptive part of the life cycle. Many fish are sequential hermaphrodites, beginning life as one sex and changing sometime later to the other. Sequential hermaphrodites include species capable of female-to-male (protogynous), male-to-female (protandrous), or bidirectional (serial) sex change. These natural forms of sex change involve coordinated transformations across multiple biological systems, including behavioral, anatomical, neuroendocrine and molecular axes. Here we review the biological processes underlying this amazing transformation, focusing particularly on the molecular aspects, where new genomic technologies are beginning to help us understand how sex change is initiated and regulated at the molecular level.
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Affiliation(s)
- Neil J Gemmell
- Department of Anatomy, University of Otago, Dunedin, New Zealand.
| | - Erica V Todd
- Department of Anatomy, University of Otago, Dunedin, New Zealand
| | | | | | - Timothy A Hore
- Department of Anatomy, University of Otago, Dunedin, New Zealand
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10
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Genome-wide analysis of brain and gonad transcripts reveals changes of key sex reversal-related genes expression and signaling pathways in three stages of Monopterus albus. PLoS One 2017; 12:e0173974. [PMID: 28319194 PMCID: PMC5358790 DOI: 10.1371/journal.pone.0173974] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Accepted: 03/01/2017] [Indexed: 12/21/2022] Open
Abstract
Background The natural sex reversal severely affects the sex ratio and thus decreases the productivity of the rice field eel (Monopterus albus). How to understand and manipulate this process is one of the major issues for the rice field eel stocking. So far the genomics and transcriptomics data available for this species are still scarce. Here we provide a comprehensive study of transcriptomes of brain and gonad tissue in three sex stages (female, intersex and male) from the rice field eel to investigate changes in transcriptional level during the sex reversal process. Results Approximately 195 thousand unigenes were generated and over 44.4 thousand were functionally annotated. Comparative study between stages provided multiple differentially expressed genes in brain and gonad tissue. Overall 4668 genes were found to be of unequal abundance between gonad tissues, far more than that of the brain tissues (59 genes). These genes were enriched in several different signaling pathways. A number of 231 genes were found with different levels in gonad in each stage, with several reproduction-related genes included. A total of 19 candidate genes that could be most related to sex reversal were screened out, part of these genes’ expression patterns were validated by RT-qPCR. The expression of spef2, maats1, spag6 and dmc1 were abundant in testis, but was barely detected in females, while the 17β-hsd12, zpsbp3, gal3 and foxn5 were only expressed in ovary. Conclusion This study investigated the complexity of brain and gonad transcriptomes in three sex stages of the rice field eel. Integrated analysis of different gene expression and changes in signaling pathways, such as PI3K-Akt pathway, provided crucial data for further study of sex transformation mechanisms.
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Gao HT, Xu R, Cao WX, Qian LL, Wang M, Lu L, Xu Q, Yu SQ. Effects of six priority controlled phthalate esters with long-term low-dose integrated exposure on male reproductive toxicity in rats. Food Chem Toxicol 2017; 101:94-104. [PMID: 28089693 DOI: 10.1016/j.fct.2017.01.011] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2016] [Revised: 01/10/2017] [Accepted: 01/12/2017] [Indexed: 01/16/2023]
Abstract
Human beings are inevitably exposed to ubiquitous phthalate esters (PEs) surroundings. The purposes of this study were to investigate the effects of long-term low-dose exposure to the mixture of six priority controlled phthalate esters (MIXPs): dimethyl phthalate (DMP), diethyl phthalate (DEP), di(n-butyl) phthalate (DBP), butyl benzyl phthalate (BBP), di(2-ethyhexyl) phthalate (DEHP) and di-n-octyl phthalate (DNOP), on male rat reproductive system and further to explore the underlying mechanisms of the reproductive toxicity. The male rats were orally exposed to either sodium carboxymethyl cellulose as controls or MIXPs at three different low-doses by gavage for 15 weeks. Testosterone and luteinizing hormone (LH) in serum were analyzed, and pathological examinations were performed for toxicity evaluation. Steroidogenic proteins (StAR, P450scc, CYP17A1 and 17β-HSD), cell cycle and apoptosis-related proteins (p53, Chk1, Cdc2, CDK6, Bcl-2 and Bax) were measured for mechanisms exploration. MIXPs with long-term low-dose exposure could cause male reproductive toxicity to the rats, including the decrease of both serum and testicular testosterone, and the constructional damage of testis. These effects were related to down-regulated steroidogenic proteins, arresting cell cycle progression and promoting apoptosis in rat testicular cells. The results indicate that MIXPs with long-term low-dose exposure may pose male reproductive toxicity in human.
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Affiliation(s)
- Hai-Tao Gao
- Key Laboratory of Environmental Medicine Engineering, Ministry of Education, School of Public Health, Southeast University, Nanjing 210009, China
| | - Run Xu
- Key Laboratory of Environmental Medicine Engineering, Ministry of Education, School of Public Health, Southeast University, Nanjing 210009, China
| | - Wei-Xin Cao
- Key Laboratory of Environmental Medicine Engineering, Ministry of Education, School of Public Health, Southeast University, Nanjing 210009, China
| | - Liang-Liang Qian
- Key Laboratory of Environmental Medicine Engineering, Ministry of Education, School of Public Health, Southeast University, Nanjing 210009, China
| | - Min Wang
- Zibo Municipal Center for Disease Control and Prevention, Zibo 255026, China
| | - Lingeng Lu
- Department of Chronic Disease Epidemiology, Yale School of Public Health, School of Medicine, Yale University, New Haven, CT 06520-8034, USA
| | - Qian Xu
- Key Laboratory of Environmental Medicine Engineering, Ministry of Education, School of Public Health, Southeast University, Nanjing 210009, China; Department of Chronic Disease Epidemiology, Yale School of Public Health, School of Medicine, Yale University, New Haven, CT 06520-8034, USA.
| | - Shu-Qin Yu
- Jiangsu Key Laboratory for Supramolecular Medicinal Material and Applications, College of Life Sciences, Nanjing Normal University, Nanjing 210046, China; Jiangsu Province Key Laboratory for Molecular and Medicinal Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing 210046, China.
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12
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Todd EV, Liu H, Muncaster S, Gemmell NJ. Bending Genders: The Biology of Natural Sex Change in Fish. Sex Dev 2016; 10:223-241. [PMID: 27820936 DOI: 10.1159/000449297] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Indexed: 11/19/2022] Open
Abstract
Sexual fate is no longer seen as an irreversible deterministic switch set during early embryonic development but as an ongoing battle for primacy between male and female developmental trajectories. That sexual fate is not final and must be actively maintained via continuous suppression of the opposing sexual network creates the potential for flexibility into adulthood. In many fishes, sexuality is not only extremely plastic, but sex change is a usual and adaptive part of the life cycle. Sequential hermaphrodites begin life as one sex, changing sometime later to the other, and include species capable of protandrous (male-to-female), protogynous (female-to-male), or serial (bidirectional) sex change. Natural sex change involves coordinated transformations across multiple biological systems, including behavioural, anatomical, neuroendocrine, and molecular axes. We here review the biological processes underlying this amazing transformation, focussing particularly on its molecular basis, which remains poorly understood, but where new genomic technologies are significantly advancing our understanding of how sex change is initiated and progressed at the molecular level. Knowledge of how a usually committed developmental process remains plastic in sequentially hermaphroditic fishes is relevant to understanding the evolution and functioning of sexual developmental systems in vertebrates generally, as well as pathologies of sexual development in humans.
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Affiliation(s)
- Erica V Todd
- Department of Anatomy, University of Otago, Dunedin, New Zealand
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13
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Qu XC, Jiang JY, Cheng C, Feng L, Liu QG. Cloning and transcriptional expression of a novel gene during sex inversion of the rice field eel (Monopterus albus). SPRINGERPLUS 2015; 4:745. [PMID: 26693104 PMCID: PMC4666882 DOI: 10.1186/s40064-015-1544-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Accepted: 11/18/2015] [Indexed: 01/08/2023]
Abstract
We performed annealing control primer (ACP)-based differential-display reverse transcription-polymerase chain reaction (DDRT-PCR) to isolate differentially expressed genes (DEGs) from the stage IV ovary and ovotestis of the rice field eel, Monopterus albus. Using 20
arbitrary ACP primers, 14 DEG expressed-sequence tags were identified and sequenced. The transcriptional expression of one DEG, G2, was significantly greater in the ovotestis than the stage IV ovary. To understand the role of G2 in sex inversion, G2 cDNA was cloned and semi-RT-PCR, real time PCR were performed during gonad development. The full-length G2 cDNA was 650 base pairs (bp) and it comprised a 5′-untranslated region (UTR) of 82 bp, a 3′-UTR of 121 bp and an open reading frame of 444 bp that encoded a 148-amino acid protein. The expression of G2 was weak during early ovarian development
until the stage IV ovary, but expression increased significantly with gonad development. We speculate that G2 may play an important function during sex inversion and testis development in the rice field eel, but the full details of the function of this gene requires further research.
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Affiliation(s)
- X C Qu
- College of Fisheries and Life Sciences, Shanghai Ocean University, Shanghai, 201306 China
| | - J Y Jiang
- College of Life Sciences, Guangxi Normal University, Guilin, 541004 China.,Key Laboratory of Ecology of Rare and Endangered Species and Environmental Protection, Ministry of Education, Guangxi Normal University, Guilin, 541004 China
| | - C Cheng
- College of Fisheries and Life Sciences, Shanghai Ocean University, Shanghai, 201306 China
| | - L Feng
- College of Fisheries and Life Sciences, Shanghai Ocean University, Shanghai, 201306 China
| | - Q G Liu
- College of Fisheries and Life Sciences, Shanghai Ocean University, Shanghai, 201306 China
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14
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Schiffer L, Anderko S, Hannemann F, Eiden-Plach A, Bernhardt R. The CYP11B subfamily. J Steroid Biochem Mol Biol 2015; 151:38-51. [PMID: 25465475 DOI: 10.1016/j.jsbmb.2014.10.011] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/14/2014] [Revised: 10/10/2014] [Accepted: 10/14/2014] [Indexed: 01/11/2023]
Abstract
The biosynthesis of steroid hormones is dependent on P450-catalyzed reactions. In mammals, cholesterol is the common precursor of all steroid hormones, and its conversion to pregnenolone is the initial and rate-limiting step in hormone biosynthesis in steroidogenic tissues such as gonads and adrenal glands. The production of glucocorticoids and mineralocorticoids takes place in the adrenal gland and the final steps are catalyzed by 2 mitochondrial cytochromes P450, CYP11B1 (11β-hydroxylase or P45011β) and CYP11B2 (aldosterone synthase or P450aldo). The occurrence and development of these 2 enzymes in different species, their contribution to the biosynthesis of steroid hormones as well as their regulation at different levels (gene expression, cellular regulation, regulation on the level of proteins) is the topic of this chapter.
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Affiliation(s)
- Lina Schiffer
- Institute of Biochemistry, Saarland University, Campus B2.2, 66123 Saarbrücken, Germany
| | - Simone Anderko
- Institute of Biochemistry, Saarland University, Campus B2.2, 66123 Saarbrücken, Germany
| | - Frank Hannemann
- Institute of Biochemistry, Saarland University, Campus B2.2, 66123 Saarbrücken, Germany
| | - Antje Eiden-Plach
- Institute of Biochemistry, Saarland University, Campus B2.2, 66123 Saarbrücken, Germany
| | - Rita Bernhardt
- Institute of Biochemistry, Saarland University, Campus B2.2, 66123 Saarbrücken, Germany.
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15
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Hu Q, Guo W, Gao Y, Tang R, Li D. Reference gene selection for real-time RT-PCR normalization in rice field eel (Monopterus albus) during gonad development. FISH PHYSIOLOGY AND BIOCHEMISTRY 2014; 40:1721-1730. [PMID: 25079246 DOI: 10.1007/s10695-014-9962-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2014] [Accepted: 07/14/2014] [Indexed: 06/03/2023]
Abstract
Real-time reverse transcriptase (RT) polymerase chain reaction (PCR) requires data normalization using an appropriate reference gene in order to obtain more reliable results with biological significance. We cloned a partial sequence of elongation factor-1-α (EF1α) and ribosomal protein L17 (RPL17) from Monopterus albus. We investigated the suitability of five commonly used reference genes [18S ribosomal RNA (18S), cytoskeletal protein (β-actin), glyceraldehyde phosphate dehydrogenase (GAPDH), EF1α and RPL17] as potential quantitative reference genes for normalizing real-time RT-PCR data generated in gonads of different developmental stages and in other tissues of M. albus. Analysis of the data indicated that 18S, β-actin and GAPDH are not suitable as reference genes because of their levels of variations of expression. EF1α and RPL17 might be suitable as reference genes in the gonads of different developmental stages as well as in other tissues of M. albus.
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Affiliation(s)
- Qing Hu
- College of Fisheries, Huazhong Agricultural University, Wuhan, 430070, China
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16
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Gao Y, Guo W, Hu Q, Zou M, Tang R, Chi W, Li D. Characterization and differential expression patterns of conserved microRNAs and mRNAs in three genders of the rice field eel (Monopterus albus). Sex Dev 2014; 8:387-98. [PMID: 25427634 DOI: 10.1159/000369181] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/15/2014] [Indexed: 11/19/2022] Open
Abstract
MicroRNAs (miRNAs) are endogenous small RNAs that can regulate target mRNAs by binding to their sequences in the 3' untranslated region. The expression of miRNAs and their biogenetic pathway are involved in sexual differentiation and in the regulation of the development of germ cells and gonadal somatic cells. The rice field eel (Monopterus albus) undergoes a natural sexual transformation from female to male via an intersex stage during its life cycle. To investigate the molecular mechanisms of this sexual transformation, miRNAs present in the different sexual stages of the rice field eel were identified by high-throughput sequencing technology. A significantly differential expression among the 3 genders (p < 0.001) was observed for 48 unique miRNAs and 3 miRNAs*. Only 9 unique miRNAs showed a more than 8-fold change in their expression among the 3 genders, including mal-miR-430a and mal-miR-430c which were higher in females than in males. However, mal-miR-430b was only detected in males. Several potential miRNA target genes (cyp19a, cyp19b, nr5a1b, foxl2 amh, and vasa) were also investigated. Real-time RT-PCR demonstrated highly specific expression patterns of these genes in the 3 genders of the rice field eel. Many of these genes are targets of mal-miR-430b according to the TargetScan and miRTarBase. These results suggest that the miR-430 family may be involved in the sexual transformation of the rice field eel.
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Affiliation(s)
- Yu Gao
- College of Fisheries, Huazhong Agricultural University, and Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture, Wuhan, PR China
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17
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Hu Q, Guo W, Gao Y, Tang R, Li D. Molecular cloning and analysis of gonadal expression of Foxl2 in the rice-field eel Monopterus albus. Sci Rep 2014; 4:6884. [PMID: 25363394 PMCID: PMC4217102 DOI: 10.1038/srep06884] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2014] [Accepted: 10/13/2014] [Indexed: 12/16/2022] Open
Abstract
We isolated the complete Foxl2 (Foxl2a) cDNA from the Monopterus albus ovary. An alignment of known Foxl2 amino-acid sequences confirmed the conservation of the Foxl2 open reading frame, especially the forkhead domain and C-terminal region. The expression of Foxl2 was detected in the brain, eyes, and gonads. A high level of Foxl2 expression in the ovary before sex reversal, but its transcripts decreased sharply when the gonad developed into the ovotestis and testis. The correlation between the Foxl2 expression and the process of sex development revealed the important function of Foxl2 during the sex reversal of M. albus. Immunohistochemical analysis showed that Foxl2 was expressed abundantly in granulosa cells and in the interstitial cells of the ovotestis and testis. These results suggest that Foxl2 plays a pivotal role in the development and maintenance of ovarian function. Foxl2 may be also involved in the early development of testis and the development of ocular structures of M. albus.
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Affiliation(s)
- Qing Hu
- 1] College of Fisheries, Huazhong Agricultural University, Wuhan 430070, China [2] Freshwater Aquaculture Collaborative Innovation Center of Hubei Province, Wuhan 430070, China [3] Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture, Wuhan 430070, China
| | - Wei Guo
- 1] College of Fisheries, Huazhong Agricultural University, Wuhan 430070, China [2] Freshwater Aquaculture Collaborative Innovation Center of Hubei Province, Wuhan 430070, China [3] Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture, Wuhan 430070, China
| | - Yu Gao
- 1] College of Fisheries, Huazhong Agricultural University, Wuhan 430070, China [2] Freshwater Aquaculture Collaborative Innovation Center of Hubei Province, Wuhan 430070, China [3] Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture, Wuhan 430070, China
| | - Rong Tang
- 1] College of Fisheries, Huazhong Agricultural University, Wuhan 430070, China [2] Freshwater Aquaculture Collaborative Innovation Center of Hubei Province, Wuhan 430070, China [3] Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture, Wuhan 430070, China
| | - Dapeng Li
- 1] College of Fisheries, Huazhong Agricultural University, Wuhan 430070, China [2] Life Science College, Hunan University of Arts and Science, Changde 415000, China [3] Freshwater Aquaculture Collaborative Innovation Center of Hubei Province, Wuhan 430070, China [4] Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture, Wuhan 430070, China
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18
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Mei J, Yan W, Fang J, Yuan G, Chen N, He Y. Identification of a gonad-expression differential gene insulin-like growth factor-1 receptor (Igf1r) in the swamp eel (Monopterus albus). FISH PHYSIOLOGY AND BIOCHEMISTRY 2014; 40:1181-1190. [PMID: 24488410 DOI: 10.1007/s10695-014-9914-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Accepted: 01/22/2014] [Indexed: 06/03/2023]
Abstract
In vertebrate species, the biopotential embryonic gonad differentiation is affected by many key genes and key steroidogenic enzymes. Insulin-like growth factor-1 receptor (Igf1r) has been considered as an important sex-differentiation gene in mammals and could mediate the biological action of Igf1, an important regulator of key steroidogenic enzymes. However, Igf1r gene is still unknown in the swamp eel, an economically important fish. In our study, we identified Igf1r gene in the swamp eel, which was a 2,148-bp open-reading frame encoding a protein of 716 amino acids. The alignment and the phylogenetic tree showed that Igf1r of the swamp eel had a conservative sequence with other vertebrates, especial fishes. Western blotting of Igf1r showed that Igf1r expressed much more in ovotestis and testis than in ovary, indicating an important role of Igf1r during gonad differentiation. We analyzed ubiquitination of Igf1r by co-immunoprecipitation and found the amount of ubiquitinated Igf1r was increased from ovary, ovotestis to testis, which was reversely to the trend of Hsp10 expression during gonadal transformation. It was possible that Hsp10 could suppress Igf1r ubiquitination during gonadal development of the swamp eel.
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Affiliation(s)
- Jie Mei
- College of Fisheries, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China
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Geffroy B, Guiguen Y, Fostier A, Bardonnet A. New insights regarding gonad development in European eel: evidence for a direct ovarian differentiation. FISH PHYSIOLOGY AND BIOCHEMISTRY 2013; 39:1129-1140. [PMID: 23334566 DOI: 10.1007/s10695-013-9769-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2012] [Accepted: 01/09/2013] [Indexed: 06/01/2023]
Abstract
In European eel, it has been proposed that the undifferentiated gonad would develop into either an intersexual stage (Syrski organ) or directly into an ovary. The Syrski organ could then develop into either an ovary or a testis. In the present study, glass eels were raised until they reached a minimum size of 29 cm for histological sex assessment. In addition, some undifferentiated individuals with size encompassing 15-28 cm were sampled in a female-biased population (Oir River). We also investigated aromatase gene expression, which is known to be involved in the process of fish sex differentiation. Gonad histology revealed that intersexual eels were characterized by a small number of oocytes within a predominant testis-like structure. Males were significantly smaller than intersexual eels, which suggests that all males do not necessarily pass through an intermediate intersexual stage. Aromatase transcript levels in intersexual eels gonads and testes were similar but significantly lower than in ovaries and were comparable between ovaries and undifferentiated gonads from the females-biased population. In addition, condition factor was lower in female than in intersexual individuals. Together, these results provide evidence that ovaries would not develop from the Syrski organ.
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Affiliation(s)
- Benjamin Geffroy
- INRA, UMR 1224 Ecobiop, Pôle d'Hydrobiologie, Quartier Ibarron, 64310, Saint Pée sur Nivelle, France
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20
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Böhne A, Heule C, Boileau N, Salzburger W. Expression and sequence evolution of aromatase cyp19a1 and other sexual development genes in East African cichlid fishes. Mol Biol Evol 2013; 30:2268-85. [PMID: 23883521 PMCID: PMC3773371 DOI: 10.1093/molbev/mst124] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Sex determination mechanisms are highly variable across teleost fishes and sexual development is often plastic. Nevertheless, downstream factors establishing the two sexes are presumably conserved. Here, we study sequence evolution and gene expression of core genes of sexual development in a prime model system in evolutionary biology, the East African cichlid fishes. Using the available five cichlid genomes, we test for signs of positive selection in 28 genes including duplicates from the teleost whole-genome duplication, and examine the expression of these candidate genes in three cichlid species. We then focus on a particularly striking case, the A- and B-copies of the aromatase cyp19a1, and detect different evolutionary trajectories: cyp19a1A evolved under strong positive selection, whereas cyp19a1B remained conserved at the protein level, yet is subject to regulatory changes at its transcription start sites. Importantly, we find shifts in gene expression in both copies. Cyp19a1 is considered the most conserved ovary-factor in vertebrates, and in all teleosts investigated so far, cyp19a1A and cyp19a1B are expressed in ovaries and the brain, respectively. This is not the case in cichlids, where we find new expression patterns in two derived lineages: the A-copy gained a novel testis-function in the Ectodine lineage, whereas the B-copy is overexpressed in the testis of the speciest-richest cichlid group, the Haplochromini. This suggests that even key factors of sexual development, including the sex steroid pathway, are not conserved in fish, supporting the idea that flexibility in sexual determination and differentiation may be a driving force of speciation.
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Affiliation(s)
- Astrid Böhne
- Zoological Institute, University of Basel, Basel, Switzerland
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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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