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Pappert FA, Dubin A, Torres GG, Roth O. Navigating sex and sex roles: deciphering sex-biased gene expression in a species with sex-role reversal ( Syngnathus typhle). ROYAL SOCIETY OPEN SCIENCE 2024; 11:rsos.231620. [PMID: 38577217 PMCID: PMC10987989 DOI: 10.1098/rsos.231620] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Revised: 02/02/2024] [Accepted: 03/11/2024] [Indexed: 04/06/2024]
Abstract
Sexual dimorphism, the divergence in morphological traits between males and females of the same species, is often accompanied by sex-biased gene expression. However, the majority of research has focused on species with conventional sex roles, where females have the highest energy burden with both egg production and parental care, neglecting the diversity of reproductive roles found in nature. We investigated sex-biased gene expression in Syngnathus typhle, a sex-role reversed species with male pregnancy, allowing us to separate two female traits: egg production and parental care. Using RNA sequencing, we examined gene expression across organs (brain, head kidney and gonads) at various life stages, encompassing differences in age, sex and reproductive status. While some gene groups were more strongly associated with sex roles, such as stress resistance and immune defence, others were driven by biological sex, such as energy and lipid storage regulation in an organ- and age-specific manner. By investigating how genes regulate and are regulated by changing reproductive roles and resource allocation in a model system with an unconventional life-history strategy, we aim to better understand the importance of sex and sex role in regulating gene expression patterns, broadening the scope of this discussion to encompass a wide range of organisms.
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Affiliation(s)
- Freya A. Pappert
- Marine Evolutionary Biology, Zoological Institute, Christian-Albrechts-Universität Kiel, Kiel24118, Germany
- Evolutionary Ecology of Marine Fishes, Helmholtz-Centre for Ocean Research Kiel (GEOMAR), Kiel24105, Germany
| | - Arseny Dubin
- Marine Evolutionary Biology, Zoological Institute, Christian-Albrechts-Universität Kiel, Kiel24118, Germany
| | - Guillermo G. Torres
- Institute of Clinical Molecular Biology (IKMB), University Hospital Schleswig-Holstein, Kiel University, Kiel24105, Germany
| | - Olivia Roth
- Marine Evolutionary Biology, Zoological Institute, Christian-Albrechts-Universität Kiel, Kiel24118, Germany
- Evolutionary Ecology of Marine Fishes, Helmholtz-Centre for Ocean Research Kiel (GEOMAR), Kiel24105, Germany
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2
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Li J, Lyu L, Wen H, Li Y, Wang X, Yao Y, Qi X. Estrogen regulates the transcription of guppy isotocin receptors. Comp Biochem Physiol B Biochem Mol Biol 2024; 269:110895. [PMID: 37611819 DOI: 10.1016/j.cbpb.2023.110895] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Revised: 08/19/2023] [Accepted: 08/19/2023] [Indexed: 08/25/2023]
Abstract
Estrogen can regulate oxytocin receptor expression, which is mediated through estrogen receptors (ESRs) in mammals, initiating parturition. To further study the reproductive physiological process of ovoviviparous teleosts, guppies (Poecilia reticulata) were employed as the research model in the present study to identify the transcriptional regulation of ESRs on isotocin receptors (itrs). Since guppy embryos develop inside the ovary, in the present study, the levels of itrs in the ovarian stroma of pregnant female guppies treated with estradiol (E2) in vitro were tested. E2 increased only itr2 mRNA levels 3 h post-treatment, with no variation in itr1 mRNA expression levels. In vivo, pregnant guppies were immersed in different concentrations of E2, significantly increasing the relative expression levels of itr1 and itr2 in the ovary. Moreover, based on dual-fluorescence in situ hybridization (ISH), both esrs and itrs mRNAs were localized in the same cells around the embryos in the ovary. To further investigate the regulation of itr transcription by estrogen, a luciferase reporter assay was performed, and the results demonstrated that E2 treatment could induce E2-dependent repression of luciferase activity in cells transfected with ESR1. However, overexpression of ESR2a or ESR2b caused a robust ligand-independent increase in itr2 promoter activity. Deletion analysis of the itr2 promoter indicated that there were novel potential ESR transcription factor-binding sites at -360 bp upstream of the 5' end of the itr2 promoter. Overall, our study provided novel results regarding the ESRs mediating the onset of parturition in ovoviviparous teleosts.
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Affiliation(s)
- Jianshuang Li
- College of Fishery, Ocean University of China, Qingdao 266000, PR China
| | - Likang Lyu
- College of Fishery, Ocean University of China, Qingdao 266000, PR China
| | - Haishen Wen
- College of Fishery, Ocean University of China, Qingdao 266000, PR China
| | - Yun Li
- College of Fishery, Ocean University of China, Qingdao 266000, PR China
| | - Xiaojie Wang
- College of Fishery, Ocean University of China, Qingdao 266000, PR China
| | - Yijia Yao
- College of Fishery, Ocean University of China, Qingdao 266000, PR China
| | - Xin Qi
- College of Fishery, Ocean University of China, Qingdao 266000, PR China.
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3
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Kloc M. Seahorse Male Pregnancy as a Model System to Study Pregnancy, Immune Adaptations, and Environmental Effects. Int J Mol Sci 2023; 24:9712. [PMID: 37298663 PMCID: PMC10253279 DOI: 10.3390/ijms24119712] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Revised: 05/13/2023] [Accepted: 06/02/2023] [Indexed: 06/12/2023] Open
Abstract
Seahorses, together with sea dragons and pipefishes, belong to the Syngnathidae family of teleost fishes. Seahorses and other Syngnathidae species have a very peculiar feature: male pregnancy. Among different species, there is a gradation of paternal involvement in carrying for the offspring, from a simple attachment of the eggs to the skin surface, through various degrees of egg coverage by skin flaps, to the internal pregnancy within a brood pouch, which resembles mammalian uterus with the placenta. Because of the gradation of parental involvement and similarities to mammalian pregnancy, seahorses are a great model to study the evolution of pregnancy and the immunologic, metabolic, cellular, and molecular processes of pregnancy and embryo development. Seahorses are also very useful for studying the effects of pollutants and environmental changes on pregnancy, embryo development, and offspring fitness. We describe here the characteristics of seahorse male pregnancy, its regulatory mechanisms, the development of immune tolerance of the parent toward the allogeneic embryos, and the effects of environmental pollutants on pregnancy and embryo development.
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Affiliation(s)
- Malgorzata Kloc
- The Houston Methodist Research Institute, Transplant Immunology, Houston, TX 77030, USA;
- Department of Surgery, The Houston Methodist Hospital, Houston, TX 77030, USA
- MD Anderson Cancer Center, Department of Genetics, The University of Texas, Houston, TX 77030, USA
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4
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Wilson AB, Whittington CM, Meyer A, Scobell SK, Gauthier ME. Prolactin and the evolution of male pregnancy. Gen Comp Endocrinol 2023; 334:114210. [PMID: 36646326 DOI: 10.1016/j.ygcen.2023.114210] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 11/04/2022] [Accepted: 01/11/2023] [Indexed: 01/15/2023]
Abstract
Prolactin (PRL) is a multifunctional hormone of broad physiological importance, and is involved in many aspects of fish reproduction, including the regulation of live birth (viviparity) and both male and female parental care. Previous research suggests that PRL also plays an important reproductive role in syngnathid fishes (seahorses, pipefish and seadragons), a group with a highly derived reproductive strategy, male pregnancy - how the PRL axis has come to be co-opted for male pregnancy remains unclear. We investigated the molecular evolution and expression of the genes for prolactin and its receptor (PRLR) in an evolutionarily diverse sampling of syngnathid fishes to explore how the co-option of PRL for male pregnancy has impacted its evolution, and to clarify whether the PRL axis is also involved in regulating reproductive function in species with more rudimentary forms of male pregnancy. In contrast to the majority of teleost fishes, all syngnathid fishes tested carry single copies of PRL and PRLR that cluster genetically within the PRL1 and PRLRa lineages of teleosts, respectively. PRL1 gene expression in seahorses and pipefish is restricted to the pituitary, while PRLRa is expressed in all tissues, including the brood pouch of species with both rudimentary and complex brooding structures. Pituitary PRL1 expression remains stable throughout pregnancy, but PRLRa expression is specifically upregulated in the male brood pouch during pregnancy, consistent with the higher affinity of pouch tissues for PRL hormone during embryonic incubation. Finally, immunohistochemistry of brood pouch tissues reveals that both PRL1 protein and PRLRa and Na+/K+ ATPase-positive cells line the inner pouch epithelium, suggesting that pituitary-derived PRL1 may be involved in brood pouch osmoregulation during pregnancy. Our data provide a unique molecular perspective on the evolution and expression of prolactin and its receptor during male pregnancy, and provide the foundation for further manipulative experiments exploring the role of PRL in this unique form of reproduction.
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Affiliation(s)
- Anthony B Wilson
- Department of Biology, Brooklyn College, 2900 Bedford Avenue, Brooklyn, NY 11210, United States; The Graduate Center, City University of New York, 365 Fifth Avenue, New York, NY 10016, United States; Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich 8057, Switzerland; Department of Biology, University of Konstanz, Universitätsstrasse 10, 78457, Germany.
| | - Camilla M Whittington
- Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich 8057, Switzerland; Sydney School of Veterinary Science, University of Sydney, Sydney 2006, Australia; School of Life and Environmental Sciences, University of Sydney, Sydney 2006, Australia
| | - Axel Meyer
- Department of Biology, University of Konstanz, Universitätsstrasse 10, 78457, Germany
| | - Sunny K Scobell
- Department of Biology, Brooklyn College, 2900 Bedford Avenue, Brooklyn, NY 11210, United States
| | - Marie-Emilie Gauthier
- Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich 8057, Switzerland
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Holt WV, Fazeli A, Otero-Ferrer F. Sperm transport and male pregnancy in seahorses: An unusual model for reproductive science. Anim Reprod Sci 2022; 246:106854. [PMID: 34579988 DOI: 10.1016/j.anireprosci.2021.106854] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Revised: 09/14/2021] [Accepted: 09/15/2021] [Indexed: 12/14/2022]
Abstract
The Syngnathidae (seahorses and pipefishes) are a group of teleost fishes in which, uniquely, developing embryos are hosted throughout pregnancy by males, using a specialized brood pouch situated on the abdomen or tail. Seahorses have evolved the most advanced form of brood pouch, whereby zygotes and embryos are intimately connected to the host's circulatory system and also bathed in pouch fluid. The pouch is closed to the external environment and has to perform functions such as gaseous exchange, removal of waste and maintenance of appropriate osmotic conditions, much like the mammalian placenta. Fertilization of the oocytes occurs within the brood pouch, but unlike the mammalian situation the sperm transport mechanism from the ejaculatory duct towards the pouch is unclear, and the sperm: egg ratio (about 5:1) is possibly the least of any vertebrate. In this review, there is highlighting of the difficulty of elucidating the sperm transport mechanism, based on studies of Hippocampus kuda. The similarities between seahorse pouch function and the mammalian placenta have led to suggestions that the pouch provides important nutritional support for the developing embryos, supplementing the nutritional functions of the yolk sac provided by the oocytes. In this review, there is a description of the recent evidence in support of this hypothesis, and also emphasis, as in mammals, that embryonic development depends on nutritional support from the placenta-like pouch at important stages of the gestational period ("critical windows").
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Affiliation(s)
- William V Holt
- Academic Unit of Reproductive and Developmental Medicine, Department of Oncology and Metabolism, University of Sheffield, Level 4, Jessop Wing, Tree Root Walk, Sheffield S10 2SF, UK.
| | - Alireza Fazeli
- Institute of Veterinary Medicine and Animal Sciences, Estonian University of Life Sciences, Tartu, Estonia; Department of Pathophysiology, Institute of Biomedicine and Translational Medicine, Faculty of Medicine, Tartu University, Tartu, Estonia; Academic Unit of Reproductive and Developmental Medicine, Department of Oncology and Metabolism, Medical School, University of Sheffield, Sheffield, UK
| | - Francisco Otero-Ferrer
- University Institute of Sustainable Aquaculture and Marine Ecosystems (IU ECOAQUA) Scientific and Technological Marine Park, University of Las Palmas de Gran Canaria, 35200, Spain
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6
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Dudley J, Paul J, Teh V, Mackenzie T, Butler T, Tolosa J, Smith R, Foley M, Dowland S, Thompson M, Whittington C. Seahorse brood pouch morphology and control of male parturition in Hippocampus abdominalis. Placenta 2022; 127:88-94. [DOI: 10.1016/j.placenta.2022.07.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/01/2022] [Revised: 07/07/2022] [Accepted: 07/18/2022] [Indexed: 11/30/2022]
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Zhang H, Liu Y, Qin G, Lin Q. Identification of neurohypophysial hormones and the role of VT in the parturition of pregnant seahorses ( Hippocampus erectus). Front Endocrinol (Lausanne) 2022; 13:923234. [PMID: 35966100 PMCID: PMC9372264 DOI: 10.3389/fendo.2022.923234] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Accepted: 07/06/2022] [Indexed: 11/26/2022] Open
Abstract
Neurohypophysial hormones regulate the reproductive behavior of teleosts; however, their role in the gestation and parturition of ovoviviparous fishes with male pregnancy (syngnathids) remains to be demonstrated. In the present study, the complementary DNA (cDNA) sequences of arginine vasotocin (VT) and isotocin (IT) from the lined seahorse (Hippocampus erectus) were cloned and identified. We observed that the mature core peptides of seahorse VT and IT were conserved among teleosts. In the phylogenic tree, seahorse VT and IT were clustered independently with teleost VT and IT. The tissue distribution patterns of VT and IT were similar, and both were highly expressed in the brain, gills, and gonads. Interestingly, they were also expressed to some extent in the brood pouch. In situ hybridization revealed that VT and IT messenger RNA (mRNA) signals in the brain were mainly located in the preoptic area region of the hypothalamus. Intraperitoneal administration of the VT core peptide to pregnant seahorses induced premature parturition, stimulated gonadotropin release, increased serum estrogen levels, and decreased prolactin secretion. Moreover, VT injection upregulated the mRNA expression of the membrane estrogen receptor in the brood pouch. In summary, neurohypophysial hormones promote premature parturition by regulating estrogen synthesis through the hypothalamus-pituitary-gonad axis.
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Affiliation(s)
- Huixian Zhang
- Chinese Academy of Science (CAS) Key Laboratory of Tropical Marine Bio-resources and Ecology (LMB), Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China
- Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Yali Liu
- Chinese Academy of Science (CAS) Key Laboratory of Tropical Marine Bio-resources and Ecology (LMB), Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China
- Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, China
| | - Geng Qin
- Chinese Academy of Science (CAS) Key Laboratory of Tropical Marine Bio-resources and Ecology (LMB), Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China
- Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, China
| | - Qiang Lin
- Chinese Academy of Science (CAS) Key Laboratory of Tropical Marine Bio-resources and Ecology (LMB), Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China
- Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, China
- University of Chinese Academy of Sciences, Beijing, China
- *Correspondence: Qiang Lin,
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8
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Tang L, Liu YL, Qin G, Lin Q, Zhang YH. Effects of tributyltin on gonad and brood pouch development of male pregnant lined seahorse (Hippocampus erectus) at environmentally relevant concentrations. JOURNAL OF HAZARDOUS MATERIALS 2021; 408:124854. [PMID: 33370696 DOI: 10.1016/j.jhazmat.2020.124854] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Revised: 11/26/2020] [Accepted: 12/12/2020] [Indexed: 06/12/2023]
Abstract
The male pregnancy of seahorses is unique, but their reproductive response to environmental disturbances has not yet been clarified. Tributyltin (TBT) is known to have an endocrine disrupting effect on the reproductive system of coastal marine organisms. This study evaluated the potential effects of exposure to environmentally relevant concentrations of TBT on the development of gonads and brood pouch of the lined seahorse (Hippocampus erectus). Physiological, histological, and transcriptional analyses were conducted, and results showed that high levels of TBT bioaccumulation occurred in male and female seahorses. TBT led to ovarian follicular atresia and apoptosis with the elevation of androgen levels, accompanied by the induction of genes associated with lysosomes and autophagosomes. Comparative transcriptional analyses revealed the likely inhibition of spermatogenesis via the suppression of cyclic AMP and androgen synthesis. Notably, the transcriptional profiles showed that TBT potentially affects the immune system, angiogenesis, and embryo nourishment of the brood pouch, which indicates that it has negative effects on the male reproductive system of seahorses. In summary, this study reveals that environmental levels of TBT potentially affect the reproductive efficiency of seahorses, and may ultimately lead to a reduction in their populations in coastal environments.
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Affiliation(s)
- Lu Tang
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Innovation Academy of South China Sea Ecology and Environmental Engineering, Chinese Academy of Sciences, Guangzhou 510301, China; University of Chinese Academy of Science, Beijing 100049, China
| | - Ya-Li Liu
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Innovation Academy of South China Sea Ecology and Environmental Engineering, Chinese Academy of Sciences, Guangzhou 510301, China; Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou 511458, China
| | - Geng Qin
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Innovation Academy of South China Sea Ecology and Environmental Engineering, Chinese Academy of Sciences, Guangzhou 510301, China; Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou 511458, China
| | - Qiang Lin
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Innovation Academy of South China Sea Ecology and Environmental Engineering, Chinese Academy of Sciences, Guangzhou 510301, China; Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou 511458, China; University of Chinese Academy of Science, Beijing 100049, China.
| | - Yan-Hong Zhang
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Innovation Academy of South China Sea Ecology and Environmental Engineering, Chinese Academy of Sciences, Guangzhou 510301, China; Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou 511458, China; University of Chinese Academy of Science, Beijing 100049, China.
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9
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Li C, Li Y, Qin G, Chen Z, Qu M, Zhang B, Han X, Wang X, Qian PY, Lin Q. Regulatory Role of Retinoic Acid in Male Pregnancy of the Seahorse. ACTA ACUST UNITED AC 2020; 1:100052. [PMID: 34557717 PMCID: PMC8454549 DOI: 10.1016/j.xinn.2020.100052] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Accepted: 10/12/2020] [Indexed: 02/01/2023]
Abstract
Seahorses epitomize the exuberance of evolution. They have the unique characteristic of male pregnancy, which includes the carrying of many embryos in a brood pouch that incubates and nourishes the embryos, similar to the mammalian placenta. However, the regulatory networks underlying brood pouch formation and pregnancy remain largely unknown. In this study, comparative transcriptomic and metabolomic profiling on the lined seahorse Hippocampus erectus, with unformed, newly formed, and pregnant brood pouches identified a total of 141 and 2,533 differentially expressed genes together with 73 and 121 significantly differential metabolites related to brood pouch formation and pregnancy, respectively. Specifically, integrative omics analysis revealed that retinoic acid (RA) synthesis and signaling pathway played essential roles in the formation of the brood pouch and pregnancy. RA might function upstream of testosterone and progesterone, thereby directly influencing brood pouch formation by regulating the expression of fshr and cyp7a1. Our results also revealed that RA regulates antioxidant defenses, particularly during male pregnancy. Alternatively, pregnancy caused a consistent decrease in RA, canthaxanthin, astaxanthin, and glutathione synthetase, and an increase in susceptibility to oxidative stress, which may balance brood pouch development and reproduction in seahorses and pave the way to successful gestation.
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Affiliation(s)
- Chunyan Li
- CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, South China Sea Institute of Oceanology, Innovation of South China Sea Ecology and Environmental Engineering, Chinese Academy of Sciences, 510301 Guangzhou, China.,Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), 511458 Guangzhou, China
| | - Yongxin Li
- Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), 511458 Guangzhou, China.,Department of Chemistry, The University of Hong Kong, Pokfulam, Hong Kong, Hong Kong SAR, China
| | - Geng Qin
- CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, South China Sea Institute of Oceanology, Innovation of South China Sea Ecology and Environmental Engineering, Chinese Academy of Sciences, 510301 Guangzhou, China
| | - Zelin Chen
- CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, South China Sea Institute of Oceanology, Innovation of South China Sea Ecology and Environmental Engineering, Chinese Academy of Sciences, 510301 Guangzhou, China
| | - Meng Qu
- CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, South China Sea Institute of Oceanology, Innovation of South China Sea Ecology and Environmental Engineering, Chinese Academy of Sciences, 510301 Guangzhou, China
| | - Bo Zhang
- CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, South China Sea Institute of Oceanology, Innovation of South China Sea Ecology and Environmental Engineering, Chinese Academy of Sciences, 510301 Guangzhou, China
| | - Xue Han
- CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, South China Sea Institute of Oceanology, Innovation of South China Sea Ecology and Environmental Engineering, Chinese Academy of Sciences, 510301 Guangzhou, China
| | - Xin Wang
- CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, South China Sea Institute of Oceanology, Innovation of South China Sea Ecology and Environmental Engineering, Chinese Academy of Sciences, 510301 Guangzhou, China
| | - Pei-Yuan Qian
- Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), 511458 Guangzhou, China.,Department of Ocean Science and Hong Kong Branch of Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Hong Kong University of Science and Technology, Kowloon, Hong Kong, China
| | - Qiang Lin
- CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, South China Sea Institute of Oceanology, Innovation of South China Sea Ecology and Environmental Engineering, Chinese Academy of Sciences, 510301 Guangzhou, China.,Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), 511458 Guangzhou, China
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10
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Skalkos ZMG, Van Dyke JU, Whittington CM. Paternal nutrient provisioning during male pregnancy in the seahorse Hippocampus abdominalis. J Comp Physiol B 2020; 190:547-556. [PMID: 32617716 DOI: 10.1007/s00360-020-01289-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 04/22/2020] [Accepted: 06/18/2020] [Indexed: 02/06/2023]
Abstract
Vertebrates that incubate embryos on or within the body cavity exhibit diverse strategies to provide nutrients to developing embryos, ranging from lecithotrophy (solely yolk-provided nutrition) to substantial matrotrophy (supplemental nutrients from the mother before birth). Syngnathid fishes (seahorses, pipefishes and sea dragons) are the only vertebrates to exhibit male pregnancy. Therefore, they provide a unique opportunity for comparative evolutionary research, in examining pregnancy independent of the female reproductive tract. Here, we tested the hypothesis that the most complex form of syngnathid pregnancy involves nutrient transport from father to offspring. We compared the dry masses of newly fertilised Hippocampus abdominalis eggs with those of fully developed neonates to derive a patrotrophy index. The patrotrophy index of H. abdominalis was 1, indicating paternal nutrient supplementation to embryos during gestation. We also measured the lipid content of newly fertilised eggs and neonates and found that there was no significant decrease in lipid mass during embryonic development. Since lipids are likely to be the main source of energy during embryonic development, our results suggest that lipid yolk reserves being depleted by embryonic metabolism are replaced by the brooding father. The results of our study support the hypothesis that nutrient transport occurs in the most advanced form of male pregnancy in vertebrates.
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Affiliation(s)
- Zoe M G Skalkos
- School of Life and Environmental Sciences, The University of Sydney, Heydon-Laurence A08, Camperdown, NSW, 2006, Australia
| | - James U Van Dyke
- School of Molecular Sciences, College of Science, Health and Engineering, La Trobe University, Wodonga, VIC, Australia
| | - Camilla M Whittington
- School of Life and Environmental Sciences, The University of Sydney, Heydon-Laurence A08, Camperdown, NSW, 2006, Australia.
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11
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Abstract
Synopsis
Females of some species are considered sex-role reversed, meaning that they face stronger competition for mates compared to males. While much attention has been paid to behavioral and morphological patterns associated with sex-role reversal, less is known about its physiological regulation. Here, we evaluate hypotheses relating to the neuroendocrine basis of sex-role reversal. We refute the most widely tested activational hypothesis for sex differences in androgen secretion; sex-role reversed females do not have higher levels of androgens in circulation than males. However, we find some evidence that the effects of androgens may be sex-specific; circulating androgen levels correlate with some competitive phenotypes in sex-role reversed females. We also review evidence that sex-role reversed females have higher tissue-specific sensitivity to androgens than males, at least in some species and tissues. Organizational effects may explain these relationships, considering that early exposure to sex steroids can shape later sensitivity to hormones, often in sex-specific ways. Moving forward, experimental and correlative studies on the ontogeny and expression of sex-role reversal will further clarify the mechanisms that generate sex-specific behaviors and sex roles.
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Affiliation(s)
- Sara E Lipshutz
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - Kimberly A Rosvall
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
- Center for the Integrated Study of Animal Behavior, Indiana University, Bloomington, IN 47405, USA
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12
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Anderson AP, Rose E, Flanagan SP, Jones AG. The Estrogen-Responsive Transcriptome of Female Secondary Sexual Traits in the Gulf Pipefish. J Hered 2020; 111:294-306. [PMID: 32124926 DOI: 10.1093/jhered/esaa008] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Accepted: 02/24/2020] [Indexed: 01/01/2023] Open
Abstract
Sexual dimorphism often results from hormonally regulated trait differences between the sexes. In sex-role-reversed vertebrates, females often have ornaments used in mating competition that are expected to be under hormonal control. Males of the sex-role-reversed Gulf pipefish (Syngnathus scovelli) develop female-typical traits when they are exposed to estrogens. We aimed to identify genes whose expression levels changed during the development and maintenance of female-specific ornaments. We performed RNA-sequencing on skin and muscle tissue in male Gulf pipefish with and without exposure to estrogen to investigate the transcriptome of the sexually dimorphic ornament of vertical iridescent bands found in females and estrogen-exposed males. We further compared differential gene expression patterns between males and females to generate a list of genes putatively involved in the female secondary sex traits of bands and body depth. A detailed analysis of estrogen-receptor binding sites demonstrates that estrogen-regulated genes tend to have nearby cis-regulatory elements. Our results identified a number of genes that differed between the sexes and confirmed that many of these were estrogen-responsive. These estrogen-regulated genes may be involved in the arrangement of chromatophores for color patterning, as well as in the growth of muscles to achieve the greater body depth typical of females in this species. In addition, anaerobic respiration and adipose tissue could be involved in the rigors of female courtship and mating competition. Overall, this study generates a number of interesting hypotheses regarding the genetic basis of a female ornament in a sex-role-reversed pipefish.
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Affiliation(s)
| | - Emily Rose
- Department of Biology, University of Tampa, Tampa, FL
| | - Sarah P Flanagan
- School of Biological Sciences, University of Canterbury, Christchurch, New Zealand
| | - Adam G Jones
- Department of Biological Sciences, University of Idaho, Moscow, ID
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13
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Whittington CM, Friesen CR. The evolution and physiology of male pregnancy in syngnathid fishes. Biol Rev Camb Philos Soc 2020; 95:1252-1272. [PMID: 32372478 DOI: 10.1111/brv.12607] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2019] [Revised: 04/09/2020] [Accepted: 04/09/2020] [Indexed: 12/24/2022]
Abstract
The seahorses, pipefishes and seadragons (Syngnathidae) are among the few vertebrates in which pregnant males incubate developing embryos. Syngnathids are popular in studies of sexual selection, sex-role reversal, and reproductive trade-offs, and are now emerging as valuable comparative models for the study of the biology and evolution of reproductive complexity. These fish offer the opportunity to examine the physiology, behavioural implications, and evolutionary origins of embryo incubation, independent of the female reproductive tract and female hormonal milieu. Such studies allow us to examine flexibility in regulatory systems, by determining whether the pathways underpinning female pregnancy are also co-opted in incubating males, or whether novel pathways have evolved in response to the common challenges imposed by incubating developing embryos and releasing live young. The Syngnathidae are also ideal for studies of the evolution of reproductive complexity, because they exhibit multiple parallel origins of complex reproductive phenotypes. Here we assay the taxonomic distribution of syngnathid parity mode, examine the selective pressures that may have led to the emergence of male pregnancy, describe the biology of syngnathid reproduction, and highlight pressing areas for future research. Experimental tests of a range of hypotheses, including many generated with genomic tools, are required to inform overarching theories about the fitness implications of pregnancy and the evolution of male pregnancy. Such information will be widely applicable to our understanding of fundamental reproductive and evolutionary processes in animals.
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Affiliation(s)
- Camilla M Whittington
- The University of Sydney, School of Life and Environmental Sciences, Sydney, New South Wales, 2006, Australia.,The University of Sydney, Sydney School of Veterinary Science, Sydney, New South Wales, 2006, Australia
| | - Christopher R Friesen
- The University of Wollongong, School of Earth, Atmospheric and Life Sciences, Faculty of Science, Medicine and Health, Wollongong, New South Wales, 2522, Australia.,Illawarra Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, New South Wales, 2522, Australia
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14
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Qin G, Zhang Y, Zhang B, Zhang Y, Liu Y, Lin Q. Environmental estrogens and progestins disturb testis and brood pouch development with modifying transcriptomes in male-pregnancy lined seahorse Hippocampus erectus. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 715:136840. [PMID: 32032986 DOI: 10.1016/j.scitotenv.2020.136840] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2019] [Revised: 01/08/2020] [Accepted: 01/19/2020] [Indexed: 06/10/2023]
Abstract
Exposure to environmental estrogens and progestins has contributed to adverse effects on the reproduction of many aquatic wildlife species. However, few reports have paid attention to fish species with specialized reproductive strategies, such as male-pregnancy seahorses. In this study, the potential effects on the behavior, gonad and brood pouch development, and transcriptomic profiles of lined seahorse Hippocampus erectus exposed to environmentally relevant concentrations of 17α-ethynyl estradiol (EE2, 5 ng/L, 50 ng/L, 10 ng/L, 100 ng/L) or progesterone (P4) for 60 days were examined. Both EE2 and P4 significantly inhibited male brood pouch development by disrupting the extracellular matrix and basement membrane pathways. In addition, both EE2 and P4 impaired the expression of genes associated with spermatogenesis in the testis, and even caused male feminization. We suggest that seahorses be regarded as a sensitive indicator for evaluating the potential effects of endocrine disrupting chemical (EDC) pollution on aquatic biotic communities.
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Affiliation(s)
- Geng Qin
- CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510275, China; Institution of South China Sea Ecology and Environmental Engineering, Chinese Academy of Sciences, Guangzhou 510275, China
| | - Yuan Zhang
- CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510275, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Bo Zhang
- CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510275, China; Institution of South China Sea Ecology and Environmental Engineering, Chinese Academy of Sciences, Guangzhou 510275, China
| | - Yanhong Zhang
- CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510275, China; Institution of South China Sea Ecology and Environmental Engineering, Chinese Academy of Sciences, Guangzhou 510275, China
| | - Yali Liu
- CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510275, China; Institution of South China Sea Ecology and Environmental Engineering, Chinese Academy of Sciences, Guangzhou 510275, China
| | - Qiang Lin
- CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510275, China; Institution of South China Sea Ecology and Environmental Engineering, Chinese Academy of Sciences, Guangzhou 510275, China; University of Chinese Academy of Sciences, Beijing 100049, China.
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15
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Metcalf CJE, Roth O, Graham AL. Why leveraging sex differences in immune trade-offs may illuminate the evolution of senescence. Funct Ecol 2020; 34:129-140. [PMID: 32063662 PMCID: PMC7006808 DOI: 10.1111/1365-2435.13458] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Accepted: 09/10/2019] [Indexed: 12/15/2022]
Abstract
The immune system affects senescence (declines in probabilities of survival or reproduction with age), by shaping late age vulnerability to chronic inflammatory diseases and infections. It is also a dynamic interactive system that must balance competing demands across the life course. Thus, immune system function remains an important frontier in understanding the evolution of senescence.Here, we review our expanding mechanistic understanding of immune function over the life course, in the context of theoretical predictions from life-history evolution. We are especially interested in stage- and sex-dependent costs and benefits of investment in the immune system, given differential life-history priorities of the life stages and sexes.We introduce the costs likely to govern immune allocation across the life course. We then discuss theoretical expectations for differences between the sexes and their likely consequences in terms of how the immune system is both modulated by and may modulate senescence, building on information from life-history theory, experimental immunology and demography.We argue that sex differences in immune function provide a potentially powerful probe of selection pressures on the immune system across the life course. In particular, differences in 'competing' and 'caring' between the sexes have evolved across the tree of life, providing repeated instances of divergent selection pressures on immune function occurring within the same overall bauplan.We conclude by detailing an agenda for future research, including development of theoretical predictions of the differences between the sexes under an array of existing models for sex differences in immunity, and empirical tests of such predictions across the tree of life. A free http://onlinelibrary.wiley.com/doi/10.1111/1365-2435.13458/suppinfo can be found within the Supporting Information of this article.
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Affiliation(s)
| | - Olivia Roth
- GEOMAR, Marine Evolutionary EcologyHelmholtz Centre for Ocean ResearchKielGermany
| | - Andrea L. Graham
- Department of Ecology and Evolutionary BiologyPrinceton UniversityPrincetonNJUSA
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16
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Wang W, Chen J, Fang Y, Wang B, Zou Q, Wang L, Zhang W, Huang X, Lv H, Zhang C, Wang K. Identification of gnrh2 and gnrh3 and their expression during brood pouch growth and short-term benzo(a)pyrene exposure in lined seahorse (Hippocampus erectus). Comp Biochem Physiol C Toxicol Pharmacol 2019; 225:108579. [PMID: 31386905 DOI: 10.1016/j.cbpc.2019.108579] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Revised: 07/25/2019] [Accepted: 07/26/2019] [Indexed: 11/16/2022]
Abstract
Gonadotropin-releasing hormones (GnRH) regulate gonadal growth of teleosts. Benzo(a)pyrene (BaP) functions as a reproductive endocrine disruptor. Furthermore, endocrine regulation on brood pouch growth of Syngnathidaes is elusive. To better understand the role of GnRH in brood pouch growth and effects of BaP on reproductive endocrine in lined seahorse (Hippocampus erectus), gnrh2 and gnrh3 genes were identified. Results showed that lined seahorse GnRH2 and GnRH3 precursors included the conservative tripartite structure and their transcripts highly expressed in brain as other teleosts. Expression profiles of gnrh2 and gnrh3 transcripts were detected during brood pouch growth. Results indicated that brain gnrh2 transcripts remarkably increased at the middle-stage and late-stage of brood pouch growth, while brain gnrh3 transcripts significantly raised at the early-stage and middle-stage. These suggested that GnRH2 and GnRH3 regulated brood pouch growth at different stages. Short-term BaP exposure in lined seahorse was performed. Transcripts of gnrh2 and gnrh3 remarkably increased in females and males exposed to BaP. Besides, plasma 17-beta estradiol (E2) levels presented a reduced trend during female fish exposed to BaP. This revealed that BaP functioned as anti-estrogenic effects and it may result in high expression of gnrh mRNA. However, plasma 11-ketone testosterone (11-KT) levels showed an increased trend during male fish exposed to BaP. Taken together, these indicated interesting results of BaP on reproduction in each sex of seahorse. These observations contribute to provide novel information of regulation on brood pouch growth and effects of BaP on reproductive endocrine in Syngnathidaes.
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Affiliation(s)
- Wenqiang Wang
- School of Agriculture, Ludong University, Yantai 264025, China
| | - Jun Chen
- School of Agriculture, Ludong University, Yantai 264025, China.
| | - Yan Fang
- School of Agriculture, Ludong University, Yantai 264025, China
| | - Bin Wang
- Key Laboratory of Sustainable Development of Marine Fisheries, Ministry of Agriculture and Rural Affairs, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao 266071, China
| | - Qiang Zou
- Yantai Branch of Shandong Technology Transfer Center, Chinese Academy of Sciences, Yantai 264003, China
| | - Lei Wang
- College of life sciences, Ludong University, Yantai 264025, China
| | - Wenwen Zhang
- School of Agriculture, Ludong University, Yantai 264025, China
| | - Xueying Huang
- School of Agriculture, Ludong University, Yantai 264025, China
| | - Haoyue Lv
- School of Agriculture, Ludong University, Yantai 264025, China
| | - Chenxiao Zhang
- School of Agriculture, Ludong University, Yantai 264025, China
| | - Kai Wang
- School of Agriculture, Ludong University, Yantai 264025, China.
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17
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Gao Y, Jing Q, Huang B, Jia Y. Molecular cloning, characterization, and mRNA expression of gonadotropins during larval development in turbot (Scophthalmus maximus). FISH PHYSIOLOGY AND BIOCHEMISTRY 2019; 45:1697-1707. [PMID: 31098916 DOI: 10.1007/s10695-019-00656-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2018] [Accepted: 05/06/2019] [Indexed: 06/09/2023]
Abstract
Gonadotropins (GtHs) play a pivotal role in regulating the reproductive axis and puberty. In this study, full-length sequences coding for common glycoprotein α subunit (CGα) and luteinizing hormone β (LHβ) were isolated from female turbot (Scophthalmus maximus) pituitary by homology cloning and a strategy based on rapid amplification of cDNA end-polymerase chain reaction. Results showed that the two cDNAs consisted of 669 and 660 nucleotides encoding 129 and 139 amino acids, respectively. CGα and LHβ manifested typical characteristics of glycoprotein hormones, high homologies with the corresponding sequences of available teleosts, and high homology with that of Hippoglossus hippoglossus. CGα, FSHβ, and LHβ mRNAs were abundant in the pituitary, but less expressed in extra-pituitary tissues. The cgα, fshβ, and lhβ were detected at 1-day post-hatching (dph) and peaked simultaneously at early-metamorphosis (22 dph). cgα and fshβ mRNA levels were significantly increased at pre-metamorphosis, peaked in early metamorphosis, and then gradually decreased until metamorphosis was completed. Conversely, lhβ mRNA levels gradually decreased at pre-metamorphosis, dramatically peaked at early metamorphosis, and then decreased during metamorphosis. In addition, the mRNA levels of cgα were significantly higher than those of fshβ and lhβ during turbot larval metamorphic development, whereas no significant difference was found between fshβ and lhβ. These results suggested (i) an early activation of the GtHs system after hatching, which was the highest expression at early metamorphosis, and (ii) FSHβ and LHβ were together involved in the establishment of the reproductive axis during larval development in turbot. These findings contribute to further understanding the potential roles of GtHs during fish larval development.
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Affiliation(s)
- Yunhong Gao
- Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, No. 106 Nanjing Road, Qingdao, 266071, People's Republic of China
- Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266237, China
- College of Fisheries and Life Science, Shanghai Ocean University, Shanghai, 201306, China
| | - Qiqi Jing
- Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, No. 106 Nanjing Road, Qingdao, 266071, People's Republic of China
- College of Fisheries and Life Science, Shanghai Ocean University, Shanghai, 201306, China
| | - Bin Huang
- Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, No. 106 Nanjing Road, Qingdao, 266071, People's Republic of China
- Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266237, China
- College of Fisheries and Life Science, Shanghai Ocean University, Shanghai, 201306, China
| | - Yudong Jia
- Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, No. 106 Nanjing Road, Qingdao, 266071, People's Republic of China.
- Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266237, China.
- College of Fisheries and Life Science, Shanghai Ocean University, Shanghai, 201306, China.
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18
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Zhang H, Chen L, Zhang B, Lin Q. Molecular identification of GnIH and its potential role in reproductive physiology and male pregnancy of the lined seahorse (Hippocampus erectus). Gen Comp Endocrinol 2019; 279:196-202. [PMID: 31002825 DOI: 10.1016/j.ygcen.2019.04.018] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Revised: 04/12/2019] [Accepted: 04/16/2019] [Indexed: 01/29/2023]
Abstract
The gonadotropin-inhibitory hormone (GnIH) plays a negative role in the hypothalamic-pituitary-gonadal (HPG) axis by inhibiting gonadotropin secretion in vertebrates. Male pregnancy and ovoviviparous behavior are unique phenomena among vertebrates. To better understand the neuroendocrine regulatory mechanisms in ovoviviparous fish with male pregnancy, we identified the orthologous GnIH gene in the lined seahorse (Hippocampus erectus). The full-length cDNA of the GnIH precursor was 658 base pairs with an open reading frame of 528 base pairs that encoded a 175-amino acid prepro-GnIH peptide. The seahorse GnIH precursor contained two putative LPXRFamide peptides. Both seahorse LPXRFa-1 and LPXRFa-2 were found to be unique among vertebrates. The synteny blocks of GnIH gene loci were conserved in mammals and teleosts. Tissue distribution analysis revealed that seahorse GnIH mRNA was mainly expressed in the hypothalamus, with relatively high levels observed in the brood pouch. The expression patterns of seahorse GnIH during different reproductive stages and pregnancy stages were also detected, and GnIH mRNA expression was significantly reduced during the early puberty stage. In addition, GnIH mRNA expression was significantly increased during the pregnancy stage compared to non-pregnancy stages. In summary, our results reveal the existence of GnIH in ovoviviparous fish and suggest its involvement in regulation of reproductive behavior and male pregnancy in the male seahorse.
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Affiliation(s)
- Huixian Zhang
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology (LMB), Guangdong Provincial Key Laboratory of Applied Marine Biology (LAMB), South China Sea Institute of Oceanology, Institute of South China Sea Ecology and Environmental Engineering, Chinese Academy of Sciences, Guangzhou, China
| | - Lingzhen Chen
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology (LMB), Guangdong Provincial Key Laboratory of Applied Marine Biology (LAMB), South China Sea Institute of Oceanology, Institute of South China Sea Ecology and Environmental Engineering, Chinese Academy of Sciences, Guangzhou, China; University of Chinese Academy of Sciences, Beijing, China
| | - Bo Zhang
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology (LMB), Guangdong Provincial Key Laboratory of Applied Marine Biology (LAMB), South China Sea Institute of Oceanology, Institute of South China Sea Ecology and Environmental Engineering, Chinese Academy of Sciences, Guangzhou, China; University of Chinese Academy of Sciences, Beijing, China
| | - Qiang Lin
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology (LMB), Guangdong Provincial Key Laboratory of Applied Marine Biology (LAMB), South China Sea Institute of Oceanology, Institute of South China Sea Ecology and Environmental Engineering, Chinese Academy of Sciences, Guangzhou, China; University of Chinese Academy of Sciences, Beijing, China.
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19
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Zhang H, Zhang B, Qin G, Li S, Lin Q. The Roles of the Kisspeptin System in the Reproductive Physiology of the Lined Seahorse ( Hippocampus erectus), an Ovoviviparous Fish With Male Pregnancy. Front Neurosci 2018; 12:940. [PMID: 30618569 PMCID: PMC6298243 DOI: 10.3389/fnins.2018.00940] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Accepted: 11/29/2018] [Indexed: 11/13/2022] Open
Abstract
The kisspeptin/GPR54 system plays a crucial role in the regulation of the reproductive axis in vertebrates. Male pregnancy and ovoviviparity are special reproductive phenomena among vertebrates. To better understand the neuroendocrine mechanisms of male pregnancy, cDNAs encoding kiss2 and GPR54 were cloned and functionally characterized from the lined seahorse, Hippocampus erectus, an ovoviviparous teleost with male pregnancy. The core mature peptide of seahorse Kiss2 is high conserved among seahorses, but unique among vertebrate Kiss orthologs. In the phylogenic analysis, the seahorse Kiss clustered with the teleost Kiss2 clade. The kiss2 transcripts were shown to be widely expressed in various tissues, notably in the brain and gonad of the seahorse, while GPR54-2 mRNA was expressed exclusively in the brain. In addition, kiss2 mRNA found in male seahorse brain tissue increased significantly at the early pubertal stage, and decreased significantly during pregnancy. Intraperitoneal administration of seahorse Kiss2-10 to sexual mature male seahorses demonstrated to stimulate lutropin β (LHβ) and follitropin β (FSHβ) release and increased serum testosterone levels. In summary, we first identified the kisspeptin/GPR54 system in an ovoviviparous fish with male pregnancy, which might be involved in the regulation of the reproductive functions of pubertal onset, gonadal development, and male pregnancy via regulating the synthesis of both gonadotropic hormone (GTH) and testosterone.
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Affiliation(s)
- Huixian Zhang
- CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology (LMB), Guangdong Provincial Key Laboratory of Applied Marine Biology (LAMB), South China Sea Institute of Oceanology, Institution of South China Sea Ecology and Environmental Engineering, Chinese Academy of Sciences, Guangzhou, China
| | - Bo Zhang
- CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology (LMB), Guangdong Provincial Key Laboratory of Applied Marine Biology (LAMB), South China Sea Institute of Oceanology, Institution of South China Sea Ecology and Environmental Engineering, Chinese Academy of Sciences, Guangzhou, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Geng Qin
- CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology (LMB), Guangdong Provincial Key Laboratory of Applied Marine Biology (LAMB), South China Sea Institute of Oceanology, Institution of South China Sea Ecology and Environmental Engineering, Chinese Academy of Sciences, Guangzhou, China
| | - Shuisheng Li
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Qiang Lin
- CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology (LMB), Guangdong Provincial Key Laboratory of Applied Marine Biology (LAMB), South China Sea Institute of Oceanology, Institution of South China Sea Ecology and Environmental Engineering, Chinese Academy of Sciences, Guangzhou, China.,University of Chinese Academy of Sciences, Beijing, China
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20
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Qin G, Luo W, Tan S, Zhang B, Ma S, Lin Q. Dimorphism of sex and gonad-development-related genes in male and female lined seahorse, Hippocampus erectus, based on transcriptome analyses. Genomics 2018; 111:260-266. [PMID: 30445213 DOI: 10.1016/j.ygeno.2018.11.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2018] [Revised: 10/28/2018] [Accepted: 11/09/2018] [Indexed: 02/06/2023]
Abstract
Seahorse is characterized by its male pregnancy and sex-role reversal. To better understand the sexual dimorphism of male and female seahorses based on essential genes, we performed systematic transcriptome studies for both genders. A total of 157,834,590 cleaned reads were obtained and assembled into 129,268 transcripts and 31,764 could be annotated. Results showed that 176 up-regulated and 391 down-regulated transcripts were identified in the male seahorses compared with those in females. Genes involved in sex differentiation, such as dmrt1, sox9, fem1 and vasa, were identified and characterized. Moreover, the essential genes involved in reproductive molecular pathway were identified and analyzed in seahorses. In conclusion, the present study provides an archive for the future systematic research on seahorse sex differentiation.
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Affiliation(s)
- Geng Qin
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Institution of South China Sea Ecology and Environmental Engineering, Chinese Academy of Sciences, Guangzhou 510301, PR China
| | - Wei Luo
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Institution of South China Sea Ecology and Environmental Engineering, Chinese Academy of Sciences, Guangzhou 510301, PR China
| | - Shuwen Tan
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Institution of South China Sea Ecology and Environmental Engineering, Chinese Academy of Sciences, Guangzhou 510301, PR China
| | - Bo Zhang
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Institution of South China Sea Ecology and Environmental Engineering, Chinese Academy of Sciences, Guangzhou 510301, PR China; University of Chinese Academy of Sciences, 19 A Yuquan Rd, Shijingshan District, Beijing 100049, PR China
| | - Shaobo Ma
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Institution of South China Sea Ecology and Environmental Engineering, Chinese Academy of Sciences, Guangzhou 510301, PR China; University of Chinese Academy of Sciences, 19 A Yuquan Rd, Shijingshan District, Beijing 100049, PR China
| | - Qiang Lin
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Institution of South China Sea Ecology and Environmental Engineering, Chinese Academy of Sciences, Guangzhou 510301, PR China.
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21
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Beal AP, Martin FD, Hale MC. Using RNA-seq to determine patterns of sex-bias in gene expression in the brain of the sex-role reversed Gulf Pipefish (Syngnathus scovelli). Mar Genomics 2018; 37:120-127. [DOI: 10.1016/j.margen.2017.09.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2017] [Revised: 09/15/2017] [Accepted: 09/15/2017] [Indexed: 10/18/2022]
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22
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Lin T, Liu X, Xiao D, Zhang D. Plasma levels of immune factors and sex steroids in the male seahorse Hippocampus erectus during a breeding cycle. FISH PHYSIOLOGY AND BIOCHEMISTRY 2017; 43:889-899. [PMID: 28197868 DOI: 10.1007/s10695-017-0343-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Accepted: 01/09/2017] [Indexed: 06/06/2023]
Abstract
To better understand the endocrine- and immune-response pattern during reproduction in a fish species having parental care behaviors and also to accumulate the endocrine- and immune-related data for future explanations of the low reproductive efficiency in seahorse species, the variations of immune factors and sex steroids in the plasma of the male lined seahorse Hippocampus erectus at different breeding stages, i.e., pre-pregnancy, pregnancy (early, middle, and late periods), and post-pregnancy, were investigated in the present study. The immune factors included monocytes/leucocytes (M/L), leucocyte phagocytic rate (LPR), immunoglobulin M (Ig M), interleukin-2 (IL-2), interferon-α (IFN-α), and lysozyme (LZM). The sex steroids included testosterone (T), 11-ketotestosterone (11-KT), 11β-hydroxytestosterone (11β-OHT), 17α-methyltestosterone (17α-MT), 17β-estradiol (E2), and 17α-hydroxy-20β-dihydroprogesterone (17α-20β-P). Moreover, the immune metabolic activity of epithelium cells in the brood pouch at different breeding stages was also analyzed through ultrastructural observations of the abundance of cytoplasmic granules, mitochondria, endoplasmic reticulum, lysosomes, and exocytosis. The results show that a higher immune level was observed during pregnancy, particularly in the early and middle periods, and a lower immune level was noted during pre-pregnancy. Correspondingly, the epithelium cells in the brood pouch also showed a stronger immune metabolic activity during pregnancy and weaker activity during pre-pregnancy. Four sex steroids of T, 11β-OHT, 17α-MT, and E2 were higher during pre-pregnancy and lower during post-pregnancy, whereas 11-KT and 17α-20β-P, which were positively correlated with part immune factors, were higher during pregnancy. No negative correlations between sex steroids and immune factors were observed. In conclusion, the higher immune competence during pregnancy may indicate that parental care could improve immunity, which may be the major factor for no immunosuppressive effect of sex steroids during reproduction in the seahorse H. erectus, unlike noncaregiving fishes in which inhibitions of sex steroids on immunity are frequently observed. Moreover, higher 11-KT and 17α-20β-P during pregnancy than during pre-pregnancy and post-pregnancy may suggest that these two steroids are also involved in parental care regulation.
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Affiliation(s)
- Tingting Lin
- Key Laboratory of East China Sea and Oceanic Fishery Resources Exploitation and Utilization, Ministry of Agriculture, East China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Shanghai, 200090, People's Republic of China
| | - Xin Liu
- Key Laboratory of East China Sea and Oceanic Fishery Resources Exploitation and Utilization, Ministry of Agriculture, East China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Shanghai, 200090, People's Republic of China
| | - Dongxue Xiao
- Key Laboratory of East China Sea and Oceanic Fishery Resources Exploitation and Utilization, Ministry of Agriculture, East China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Shanghai, 200090, People's Republic of China
| | - Dong Zhang
- Key Laboratory of East China Sea and Oceanic Fishery Resources Exploitation and Utilization, Ministry of Agriculture, East China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Shanghai, 200090, People's Republic of China.
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23
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Sokołowska E, Kleszczyńska A, Nietrzeba M, Kulczykowska E. Annual changes in brain concentration of arginine vasotocin and isotocin correspond with phases of reproductive cycle in round goby, Neogobius melanostomus. Chronobiol Int 2016; 32:917-24. [PMID: 26172224 DOI: 10.3109/07420528.2015.1052142] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Reproductive cycle of seasonally breeding fish is synchronized with changes of photoperiod and temperature in environment. We hypothesize that arginine vasotocin (AVT) and isotocin (IT) are involved in timing and synchronization of seasonal reproductive activity in the round goby (Neogobius melanostomus). To verify this hypothesis, we examined the annual profiles of brain AVT and IT in round goby males and females in relation to their reproductive cycle. Wild round gobies were exposed to annual environmental changes in their natural habitats from where they were sampled monthly over a year. AVT and IT were measured using HPLC with fluorescence detection preceded by solid-phase extraction. This study shows seasonal variations in brain AVT and IT levels. Profiles of changes were similar in males and females: the peak of AVT was observed before spawning in March-April, whereas that of IT during spawning in May-June. Furthermore, the lowest AVT level was noted out of breeding season from November to January, while the level of IT decreased immediately at the end of the spawning. The results show that high AVT levels correlate with pre-spawning period whereas the highest IT levels correspond to spawning. A significant decline in AVT and IT in non-spawning season coincided with the quiescent phase of gametogenesis in both sexes.
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Affiliation(s)
- E Sokołowska
- a Department of Genetics and Marine Biotechnology , Institute of Oceanology, Polish Academy of Sciences , Sopot , Poland
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24
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Abstract
Cannibalism provides energetic benefits but is also potentially costly, especially when directed towards kin. Since fitness costs increase with time and energy invested in offspring, cannibalism should be infrequent when parental investment is high. Thus, filial cannibalism in male syngnathids, a group known for the occurrence of male pregnancy, should be rare. Using the pipefish (Syngnathus abaster) we aimed to investigate whether cannibalism does occur in both sexes and how it is affected by reproductive and nutritional states. Although rare, we witnessed cannibalism both in the wild and in the laboratory. Unlike non-pregnant males and females, pregnant and post-partum males largely refrained from cannibalising juveniles. Reproducing males decreased their feeding activity, thus rendering cannibalism, towards kin or non-kin, less likely to occur. However, if not continuously fed, all pipefish adopted a cannibal strategy, revealing that sex and life history stages influenced the ratio between the benefits and costs of cannibalism.
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Affiliation(s)
- M. Cunha
- CIBIO/InBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, Rua Padre Armando Quintas, 4485-661 Vairão, Portugal
- Faculdade de Ciências da Universidade do Porto, rua do Campo Alegre, 4169-007 Porto, Portugal
| | - A. Berglund
- Department of Animal Ecology, Evolutionary Biology Centre (EBC), Uppsala University, Norbyvägen 14, 752 36, Uppsala, Sweden
| | - T. Alves
- CIBIO/InBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, Rua Padre Armando Quintas, 4485-661 Vairão, Portugal
| | - N.M. Monteiro
- CIBIO/InBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, Rua Padre Armando Quintas, 4485-661 Vairão, Portugal
- Faculdade de Ciências da Universidade do Porto, rua do Campo Alegre, 4169-007 Porto, Portugal
- CEBIMED, Faculdade de Ciências da Saúde, Universidade Fernando Pessoa, Rua Carlos da Maia 296, 4200-150 Porto, Portugal
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25
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Rose E, Flanagan SP, Jones AG. The Effects of Synthetic Estrogen Exposure on the Sexually Dimorphic Liver Transcriptome of the Sex-Role-Reversed Gulf Pipefish. PLoS One 2015; 10:e0139401. [PMID: 26448558 PMCID: PMC4598134 DOI: 10.1371/journal.pone.0139401] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Accepted: 09/12/2015] [Indexed: 01/22/2023] Open
Abstract
Species exhibiting sex-role reversal provide an unusual perspective on the evolution of sex roles and sex differences. However, the proximate effects of sex-role reversal are largely unknown. Endocrine disruptors provide an experimental mechanism to address hormonal regulation of sexually dimorphic gene expression in sex-role-reversed taxa. Here, we investigate gene expression patterns in the liver of the sex-role-reversed Gulf pipefish, because the liver is known to be sexually dimorphic and estrogen-regulated in species with conventional sex roles. Using next-generation RNA-sequencing technology (RNA-seq), we detected sexually dimorphic hepatic gene expression patterns, with a total of 482 differentially expressed genes between the sexes in Gulf pipefish. Two-thirds of these genes were over-expressed in females, and the sex-specific transcriptomes of this sex-role-reversed pipefish’s liver were superficially similar to those of fishes with conventional sex-roles. We exposed females, pregnant males, and non-pregnant males to 17α-ethinylestradiol (EE2) at ecologically relevant concentrations of 5ng/L and compared gene expression patterns in the livers of exposed fish to control fish. Several genes that were up-regulated in EE2-exposed males relative to control males were also found to be female-biased in control animals. These genes included several of the classic estrogen biomarkers, such as vitellogenin, choriogenin, and zona pellucida. Thus, estrogen exposure induced feminization of the male liver transcriptome in a sex-role-reversed pipefish. These results suggest that the ancestral state of estrogen-regulated female reproductive physiology has been retained in all sex-role-reversed vertebrates thus far studied, despite substantial evolution of the hormonal regulation of ornamentation and mating behavior in these interesting taxa.
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Affiliation(s)
- Emily Rose
- Department of Biology, Texas A&M University, 3258 TAMU, College Station, Texas, 77845, United States of America
- * E-mail:
| | - Sarah P. Flanagan
- Department of Biology, Texas A&M University, 3258 TAMU, College Station, Texas, 77845, United States of America
| | - Adam G. Jones
- Department of Biology, Texas A&M University, 3258 TAMU, College Station, Texas, 77845, United States of America
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26
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Whittington CM, Griffith OW, Qi W, Thompson MB, Wilson AB. Seahorse Brood Pouch Transcriptome Reveals Common Genes Associated with Vertebrate Pregnancy. Mol Biol Evol 2015; 32:3114-31. [PMID: 26330546 DOI: 10.1093/molbev/msv177] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Viviparity (live birth) has evolved more than 150 times in vertebrates, and represents an excellent model system for studying the evolution of complex traits. There are at least 23 independent origins of viviparity in fishes, with syngnathid fishes (seahorses and pipefish) unique in exhibiting male pregnancy. Male seahorses and pipefish have evolved specialized brooding pouches that provide protection, gas exchange, osmoregulation, and limited nutrient provisioning to developing embryos. Pouch structures differ widely across the Syngnathidae, offering an ideal opportunity to study the evolution of reproductive complexity. However, the physiological and genetic changes facilitating male pregnancy are largely unknown. We used transcriptome profiling to examine pouch gene expression at successive gestational stages in a syngnathid with the most complex brood pouch morphology, the seahorse Hippocampus abdominalis. Using a unique time-calibrated RNA-seq data set including brood pouch at key stages of embryonic development, we identified transcriptional changes associated with brood pouch remodeling, nutrient and waste transport, gas exchange, osmoregulation, and immunological protection of developing embryos at conception, development and parturition. Key seahorse transcripts share homology with genes of reproductive function in pregnant mammals, reptiles, and other live-bearing fish, suggesting a common toolkit of genes regulating pregnancy in divergent evolutionary lineages.
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Affiliation(s)
- Camilla M Whittington
- Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland School of Biological Sciences, The University of Sydney, Sydney, NSW, Australia
| | - Oliver W Griffith
- Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland
| | - Weihong Qi
- Functional Genomics Centre, University of Zurich, Zurich, Switzerland
| | - Michael B Thompson
- Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland
| | - Anthony B Wilson
- School of Biological Sciences, The University of Sydney, Sydney, NSW, Australia Department of Biology, Brooklyn College The Graduate Center, City University of New York
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27
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Piccinno M, Zupa R, Corriero A, Centoducati G, Passantino L, Rizzo A, Sciorsci RL. In vitro effect of isotocin on ovarian tunica albuginea contractility of gilthead seabream (Sparus aurata L.) in different reproductive conditions. FISH PHYSIOLOGY AND BIOCHEMISTRY 2014; 40:1191-9. [PMID: 24482096 DOI: 10.1007/s10695-014-9915-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Accepted: 01/22/2014] [Indexed: 05/21/2023]
Abstract
Contractions of ovarian tunica albuginea, the teleostean cystovary wall layer containing smooth muscle fibres, facilitate oocytes and fluids movements within the ovary, oocytes ovulation and spawning. Fish isotocin, the homologue hormone of mammalian oxytocin, plays a significant role in ovulation, oviduct contraction and spawning. In the present study, ovarian wall spontaneous contraction, as well as isotocin in vitro effect on tunica albuginea contractility, was analysed in female seabream in different reproductive conditions: vitellogenesis, regressing (post-spawning) and extensive atresia. Tunica albuginea spontaneous contractility was recorded using ovary wall strips mounted in an organ bath containing modified Ringer's solution. The strips were then exposed to cumulative doses of isotocin (6, 30, 60 μg/ml). Female seabream in regressing condition exhibited the highest level of tunica albuginea spontaneous contraction amplitude compared with the other two groups. Only fish in vitellogenesis state showed a significant increase in contraction amplitude after isotocin administration at the dose of 30 μg/ml. The same group exhibited also a significant isotocin dose-dependent decrease in the contractile frequency. These results confirm the involvement of isotocin in stimulating tunica albuginea contractile activity during the oestrogen-regulated phase of vitellogenesis, whereas the absence of significant effects of isotocin on ovarian contractility in fish at the regressing state might be ascribed to the occurrence of a contractile activity autonomously regulated by the internal pacemaker system. The absence of exposed isotocin receptors could explain the lack of effects of the isotocin administration in seabream showed extensive atresia of the follicular cells.
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Affiliation(s)
- M Piccinno
- Department of Emergency and Organ Transplantation, Section of Veterinary Medicine and Animal Production, University of Bari Aldo Moro, S.P. Per Casamassima Km. 3, 70010, Valenzano, BA, Italy
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28
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Sommer S, Whittington CM, Wilson AB. Standardised classification of pre-release development in male-brooding pipefish, seahorses, and seadragons (Family Syngnathidae). BMC DEVELOPMENTAL BIOLOGY 2012; 12:39. [PMID: 23273265 PMCID: PMC3541971 DOI: 10.1186/1471-213x-12-39] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/05/2012] [Accepted: 12/14/2012] [Indexed: 11/10/2022]
Abstract
BACKGROUND Members of the family Syngnathidae share a unique reproductive mode termed male pregnancy. Males carry eggs in specialised brooding structures for several weeks and release free-swimming offspring. Here we describe a systematic investigation of pre-release development in syngnathid fishes, reviewing available data for 17 species distributed across the family. This work is complemented by in-depth examinations of the straight-nosed pipefish Nerophis ophidion, the black-striped pipefish Syngnathus abaster, and the potbellied seahorse Hippocampus abdominalis. RESULTS We propose a standardised classification of early syngnathid development that extends from the activation of the egg to the release of newborn. The classification consists of four developmental periods - early embryogenesis, eye development, snout formation, and juvenile - which are further divided into 11 stages. Stages are characterised by morphological traits that are easily visible in live and preserved specimens using incident-light microscopy. CONCLUSIONS Our classification is derived from examinations of species representing the full range of brooding-structure complexity found in the Syngnathidae, including tail-brooding as well as trunk-brooding species, which represent independent evolutionary lineages. We chose conspicuous common traits as diagnostic features of stages to allow for rapid and consistent staging of embryos and larvae across the entire family. In view of the growing interest in the biology of the Syngnathidae, we believe that the classification proposed here will prove useful for a wide range of studies on the unique reproductive biology of these male-brooding fish.
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Affiliation(s)
- Stefan Sommer
- Institute of Evolutionary Biology and Environmental Studies, University of Zürich, Winterthurerstrasse 190, Zürich, CH-8057, Switzerland.
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29
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Ahnesjö I, Craig JF. The biology of Syngnathidae: pipefishes, seadragons and seahorses. JOURNAL OF FISH BIOLOGY 2011; 78:1597-1602. [PMID: 21651518 DOI: 10.1111/j.1095-8649.2011.03008.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
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