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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Zhang B, Qin G, Qu L, Zhang Y, Li C, Cang C, Lin Q. Wnt8a is one of the candidate genes that play essential roles in the elongation of the seahorse prehensile tail. Mar Life Sci Technol 2021; 3:416-426. [PMID: 37073259 PMCID: PMC10077196 DOI: 10.1007/s42995-021-00099-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2020] [Accepted: 01/08/2021] [Indexed: 05/03/2023]
Abstract
Seahorses are a hallmark of specialized morphological features due to their elongated prehensile tail. However, the underlying genomic grounds of seahorse tail development remain elusive. Herein, we evaluated the roles of essential genes from the Wnt gene family for the tail developmental process in the lined seahorse (Hippocampus erectus). Comparative genomic analysis revealed that the Wnt gene family is conserved in seahorses. The expression profiles and in situ hybridization suggested that Wnt5a, Wnt8a, and Wnt11 may participate in seahorse tail development. Like in other teleosts, Wnt5a and Wnt11 were found to regulate the development of the tail axial mesoderm and tail somitic mesoderm, respectively. However, a significantly extended expression period of Wnt8a during seahorse tail development was observed. Signaling pathway analysis further showed that Wnt8a up-regulated the expression of the tail axial mesoderm gene (Shh), while interaction analysis indicated that Wnt8a could promote the expression of Wnt11. In summary, our results indicate that the special extended expression period of Wnt8a might promote caudal tail axis formation, which contributes to the formation of the elongated tail of the seahorse. Supplementary Information The online version contains supplementary material available at 10.1007/s42995-021-00099-7.
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Affiliation(s)
- 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
- 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, Chinese Academy of Sciences, Guangzhou, 510275 China
- Institution of South China Sea Ecology and Environmental Engineering, Chinese Academy of Sciences, Guangzhou, 510275 China
- Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, 511458 China
| | - Lili Qu
- School of Life Sciences, University of Science and Technology of China, Hefei, 230026 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
- Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, 511458 China
| | - Chunyan Li
- 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
- Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, 511458 China
| | - Chunlei Cang
- School of Life Sciences, University of Science and Technology of China, Hefei, 230026 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
- Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, 511458 China
- University of Chinese Academy of Sciences, Beijing, 100049 China
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Suarez-Bregua P, Rosendo S, Comesaña P, Sánchez-Ruiloba L, Morán P, Planas M, Rotllant J. Dynamic changes in DNA methylation during seahorse (Hippocampus reidi) postnatal development and settlement. Front Zool 2021; 18:52. [PMID: 34627317 PMCID: PMC8502395 DOI: 10.1186/s12983-021-00436-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Accepted: 09/22/2021] [Indexed: 11/30/2022] Open
Abstract
Introduction Most living marine organisms have a biphasic life cycle dependent on metamorphosis and settlement. These critical life-history events mean that a developmentally competent larva undergoes a range of coordinated morphological and physiological changes that are in synchrony with the ecological transition from a pelagic to a benthonic lifestyle. Therefore, transition from a pelagic to a benthonic habitat requires multiple adaptations, however, the underlying mechanisms regulating this process still remains unclear. Epigenetic regulation and specifically DNA methylation, has been suggested to be particularly important for organisms to adapt to new environments. Seahorses (Family Syngnathidae, Genus Hippocampus) are a fascinating group of fish, distinguished by their unique anatomical features, reproductive strategy and behavior. They are unique among vertebrate species due to their “male pregnancy”, where males nourish developing embryos and larvae in a brood pouch until hatching and parturition occurs. After birth, free-swimming offspring are pelagic and subsequently they change into a demersal lifestyle. Therefore, to begin to address the question whether epigenetic processes could be involved in the transition from a planktonic to a benthonic lifestyle observed in seahorses, we studied global DNA methylation profiles in a tropical seahorse species (Hippocampus reidi) during postnatal development and settlement. Results We performed methylation-sensitive amplified polymorphism (MSAP) along with quantitative expression analysis for genes suggested to be involved in the methylation machinery at six age groups: 1, 5, 10, 20, 30 and 40 days after male’s pouch release (DAR). Results revealed that the H. reidi genome has a significantly different DNA methylation profile during postnatal development and settlement on demersal habitats. Moreover, gene expression analysis showed up- and down-regulation of specific DNA methyltransferases (DNMTs) encoding genes. Conclusion Our data show that the differences in the DNA methylation patterns seen among developmental stages and during the transition from a pelagic to a benthonic lifestyle suggest a potential for epigenetic regulation of gene expression (through DNA methylation) in this species. Therefore, epigenetic mechanisms could be necessary for seahorse settlement. Nevertheless, if these epigenetic mechanisms come from internal or if they are initiated via external environmental cues should be further investigated.
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Affiliation(s)
- Paula Suarez-Bregua
- Acuatic Biotechnology-ACUABIOTEC Lab, Department of Biotechnology and Aquaculture, Marine Research Institute IIM-CSIC, Vigo, Pontevedra, Spain.
| | - Sofia Rosendo
- Acuatic Biotechnology-ACUABIOTEC Lab, Department of Biotechnology and Aquaculture, Marine Research Institute IIM-CSIC, Vigo, Pontevedra, Spain
| | - Pilar Comesaña
- Acuatic Biotechnology-ACUABIOTEC Lab, Department of Biotechnology and Aquaculture, Marine Research Institute IIM-CSIC, Vigo, Pontevedra, Spain
| | - Lucia Sánchez-Ruiloba
- Acuatic Biotechnology-ACUABIOTEC Lab, Department of Biotechnology and Aquaculture, Marine Research Institute IIM-CSIC, Vigo, Pontevedra, Spain
| | - Paloma Morán
- Department of Biochemistry, Genetics and Immunology, University of Vigo, Pontevedra, Spain
| | - Miquel Planas
- Department of Ecology and Marine Resources, Marine Research Institute IIM-CSIC, Vigo, Pontevedra, Spain
| | - Josep Rotllant
- Acuatic Biotechnology-ACUABIOTEC Lab, Department of Biotechnology and Aquaculture, Marine Research Institute IIM-CSIC, Vigo, Pontevedra, Spain.
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Otero-Ferrer F, Lättekivi F, Ord J, Reimann E, Kõks S, Izquierdo M, Holt WV, Fazeli A. Time-critical influences of gestational diet in a seahorse model of male pregnancy. ACTA ACUST UNITED AC 2020; 223:jeb.210302. [PMID: 31862853 PMCID: PMC7033721 DOI: 10.1242/jeb.210302] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Accepted: 12/18/2019] [Indexed: 12/15/2022]
Abstract
Sex role reversal is not uncommon in the animal kingdom but is taken to the extreme by the Syngnathidae, in which male pregnancy is one of the most astonishing idiosyncrasies. However, critical and time-dependent environmental effects on developing embryos, such as those extensively studied in mammalian pregnancy, have not been investigated in the male pregnancy context. Here, we tested the hypothesis that seahorse pregnancy is subject to ‘critical windows’ of environmental sensitivity by feeding male long-snouted seahorses (Hippocampus reidi) a diet deficient in polyunsaturated fatty acids during specific periods before and during pregnancy. Despite embryos being nourished principally by maternally supplied yolk, we found that offspring morphology, fatty acid composition and gene expression profiles were influenced by paternal diet in a manner that depended critically on the timing of manipulation. Specifically, reception of a diet deficient in polyunsaturated fatty acids in the days preceding pregnancy resulted in smaller newborn offspring, while the same diet administered towards the end of pregnancy resulted in substantial alterations to newborn gene expression and elongation of the snout at 10 days old. Although paternal diet did not affect 10 day survival, the observed morphological alterations in some cases could have important fitness consequences in the face of natural selective pressures such as predation and food availability. Our results demonstrate that, under male pregnancy, fine-scale temporal variation in parental diet quality and subsequent critical window effects should not be overlooked as determinants of developing offspring fitness. Summary: Food quality has a time-dependent impact on the offspring of male seahorses, revealing new insights into male pregnancy and its potential adaptive importance for syngnathid offspring.
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Affiliation(s)
- Francisco Otero-Ferrer
- Grupo en Biodiversidad y Conservación, Instituto Universitario en Acuicultura Sostenible y Ecosistemas Marinos (IU-ECOAQUA), Universidad de Las Palmas de Gran Canaria, Marine Scientific and Technological Park, Carretera de Taliarte s/n, E-35214 Telde, Spain
| | - Freddy Lättekivi
- Institute of Biomedicine and Translational Medicine, Department of Pathophysiology, University of Tartu, Ravila 14b, 50411 Tartu, Estonia
| | - James Ord
- Institute of Biomedicine and Translational Medicine, Department of Pathophysiology, University of Tartu, Ravila 14b, 50411 Tartu, Estonia
| | - Ene Reimann
- Institute of Biomedicine and Translational Medicine, Department of Pathophysiology, University of Tartu, Ravila 14b, 50411 Tartu, Estonia
| | - Sulev Kõks
- Perron Institute for Neurological and Translational Science, RR Block, QE II Medical Centre, 8 Verdun Street, Nedlands, WA 6009, Australia
| | - Marisol Izquierdo
- Grupo de Investigación en Acuicultura, Instituto Universitario en Acuicultura Sostenible y Ecosistemas Marinos (IU-ECOAQUA), Universidad de Las Palmas de Gran Canaria, Marine Scientific and Technological Park, Carretera de Taliarte s/n, E-35214 Telde, Spain
| | - William Vincent 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 Biomedicine and Translational Medicine, Department of Pathophysiology, University of Tartu, Ravila 14b, 50411 Tartu, Estonia .,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
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