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Fernández Míguez M, Presa P, Puvanendran V, Tveiten H, Hansen ØJ, Pérez M. Gene Expression and Phenotypic Assessment of Egg Quality across Developmental Stages of Atlantic Cod throughout the Spawning Season. Int J Mol Sci 2024; 25:7488. [PMID: 39000593 PMCID: PMC11242223 DOI: 10.3390/ijms25137488] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2024] [Revised: 06/27/2024] [Accepted: 06/29/2024] [Indexed: 07/16/2024] Open
Abstract
Egg quality in fishes is commonly determined by fertilisation success and cleavage patterns as a phenotypic outcome of underlying regulatory mechanisms. Although these phenotypic estimators of egg quality are useful in farming conditions, these "good quality" egg batches do not always translate to good larval growth and survival. The identification of genes involved in embryonic development may help find links between genetic factors of maternal origin and egg quality. Herein, the relative expression of seven stage-specific developmental genes of Atlantic cod was analysed using quantitative PCR to understand the function during embryogenesis and its relationship with egg quality. Genes ccnb2 and pvalb1 showed significant differential expression between developmental stages and significant upregulation from blastula and somite stages, respectively. The comparison of spawning batches showed that the relative gene expression of genes ccnb2, acta, tnnt3 and pvalb1 was significantly higher from the middle of the spawning season where phenotypic quality estimators establish the best egg quality. Moreover, a positive significant correlation was observed between quality estimators based on egg morphology and the genetic expression of genes acta and acta1 during somitogenesis. This study suggests that the combination of quality estimators, genetics and batch timing could help optimise reproductive protocols for commercial stocks of Atlantic cod.
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Affiliation(s)
- María Fernández Míguez
- Department of Biological Sciences, University of Bergen, 5006 Bergen, Norway
- Laboratory of Marine Genetic Resources, ReXenMar, CIM, Universidade de Vigo, 36310 Vigo, Spain;
- AQUACOV, Centro Oceanográfico de Vigo, Instituto Español de Oceanografía (IEO, CSIC), 36202 Vigo, Spain;
| | - Pablo Presa
- Laboratory of Marine Genetic Resources, ReXenMar, CIM, Universidade de Vigo, 36310 Vigo, Spain;
| | - Velmurugu Puvanendran
- Department of Production Biology, Centre for Marine Aquaculture, Nofima AS, 9291 Tromsø, Norway; (V.P.); (Ø.J.H.)
| | - Helge Tveiten
- Faculty of Biosciences, Fisheries and Economics, Norwegian College of Fishery Science, The Arctic University of Norway (UiT), 9019 Tromsø, Norway;
| | - Øyvind J. Hansen
- Department of Production Biology, Centre for Marine Aquaculture, Nofima AS, 9291 Tromsø, Norway; (V.P.); (Ø.J.H.)
| | - Montse Pérez
- AQUACOV, Centro Oceanográfico de Vigo, Instituto Español de Oceanografía (IEO, CSIC), 36202 Vigo, Spain;
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A Potential Role of the Translation Elongation Factor eef1a1 in Gonadal High-Temperature Perception in Chinese Tongue Sole (Cynoglossus semilaevis). Animals (Basel) 2022; 12:ani12131603. [PMID: 35804501 PMCID: PMC9265046 DOI: 10.3390/ani12131603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Revised: 06/09/2022] [Accepted: 06/10/2022] [Indexed: 11/16/2022] Open
Abstract
Simple Summary The eukaryotic elongation factor 1 alpha (eef1a) gene is vital for protein translation by delivering aminoacylated tRNAs to the A/P site of the ribosome via the GTP-dependent reaction. Here, the Chinese tongue sole (Cynoglossus semilaevis) eef1a1 gene was identified, and its potential role in gonadal high-temperature perception was assessed. The full-length sequence of eef1a1 cDNA was 1809 base pair (bp) encoding a putative protein of 461 amino acids. The expression levels of eef1a1 in the ovary were significantly higher than that in the testis from 6 mpf to 3 ypf. Under high-temperature induction during sex differentiation, eef1a1 was significantly down-regulated in males, while the difference was not detected in females. Furthermore, the rapid response of eef1a1 to environmental high temperature was assessed in vitro. Our findings suggest that C. semilaevis eef1a1 might be essential for the molecular response regulatory network of external temperature affecting internal sex differentiation. Abstract The eukaryotic translation elongation factor 1 alpha (eef1a) gene has a well-defined role in protein synthesis. However, its role in external temperature perception and internal sex differentiation and development is still unclear. In this study, eef1a1 was identified and functionally analyzed in Chinese tongue sole (Cynoglossus semilaevis). The eef1a1 cDNA, 1809 bp in length, had a 1386 bp open reading frame (ORF) that encoded a 461 amino acid polypeptide containing one EF-1_alpha domain. eef1a1 expression levels were investigated across different tissues and during gonadal development. In the gonad, eef1a1 showed a sexually dimorphic expression pattern with a statistically higher expression level in the ovary than in the testis from 6 months postfertilization to 3 years postfertilization. Under high temperature (28 °C) treatment during C. semilaevis sex differentiation (from 30 days postfertilization to 3 months postfertilization), eef1a1 was statistically down-regulated in males, while the difference was not detected in females. In addition, the dual-luciferase assay exhibited that eef1a1 can respond to high temperature rapidly. Based on these results, C. semilaevis eef1a1 might have a dual role in the perception of external temperature changes and sex differentiation regulation.
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Breton TS, Sampson WGB, Clifford B, Phaneuf AM, Smidt I, True T, Wilcox AR, Lipscomb T, Murray C, DiMaggio MA. Characterization of the G protein-coupled receptor family SREB across fish evolution. Sci Rep 2021; 11:12066. [PMID: 34103644 PMCID: PMC8187511 DOI: 10.1038/s41598-021-91590-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Accepted: 05/28/2021] [Indexed: 12/20/2022] Open
Abstract
The SREB (Super-conserved Receptors Expressed in Brain) family of G protein-coupled receptors is highly conserved across vertebrates and consists of three members: SREB1 (orphan receptor GPR27), SREB2 (GPR85), and SREB3 (GPR173). Ligands for these receptors are largely unknown or only recently identified, and functions for all three are still beginning to be understood, including roles in glucose homeostasis, neurogenesis, and hypothalamic control of reproduction. In addition to the brain, all three are expressed in gonads, but relatively few studies have focused on this, especially in non-mammalian models or in an integrated approach across the entire receptor family. The purpose of this study was to more fully characterize sreb genes in fish, using comparative genomics and gonadal expression analyses in five diverse ray-finned (Actinopterygii) species across evolution. Several unique characteristics were identified in fish, including: (1) a novel, fourth euteleost-specific gene (sreb3b or gpr173b) that likely emerged from a copy of sreb3 in a separate event after the teleost whole genome duplication, (2) sreb3a gene loss in Order Cyprinodontiformes, and (3) expression differences between a gar species and teleosts. Overall, gonadal patterns suggested an important role for all sreb genes in teleost testicular development, while gar were characterized by greater ovarian expression that may reflect similar roles to mammals. The novel sreb3b gene was also characterized by several unique features, including divergent but highly conserved amino acid positions, and elevated brain expression in puffer (Dichotomyctere nigroviridis) that more closely matched sreb2, not sreb3a. These results demonstrate that SREBs may differ among vertebrates in genomic structure and function, and more research is needed to better understand these roles in fish.
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Affiliation(s)
- Timothy S Breton
- Division of Natural Sciences, University of Maine at Farmington, Farmington, ME, USA.
| | - William G B Sampson
- Division of Natural Sciences, University of Maine at Farmington, Farmington, ME, USA
| | - Benjamin Clifford
- Science Department, Southern Maine Community College, South Portland, ME, USA
| | - Anyssa M Phaneuf
- Division of Natural Sciences, University of Maine at Farmington, Farmington, ME, USA
| | - Ilze Smidt
- Department of Biology, Bates College, Lewiston, ME, USA
| | - Tamera True
- Division of Natural Sciences, University of Maine at Farmington, Farmington, ME, USA
| | - Andrew R Wilcox
- Division of Natural Sciences, University of Maine at Farmington, Farmington, ME, USA
| | - Taylor Lipscomb
- Tropical Aquaculture Laboratory, Program in Fisheries and Aquatic Sciences, School of Forest Resources and Conservation, Institute of Food and Agricultural Sciences, University of Florida, Ruskin, FL, USA.,Livingston Stone National Fish Hatchery, US Fish and Wildlife Service, Shasta Lake, CA, USA
| | - Casey Murray
- Tropical Aquaculture Laboratory, Program in Fisheries and Aquatic Sciences, School of Forest Resources and Conservation, Institute of Food and Agricultural Sciences, University of Florida, Ruskin, FL, USA
| | - Matthew A DiMaggio
- Tropical Aquaculture Laboratory, Program in Fisheries and Aquatic Sciences, School of Forest Resources and Conservation, Institute of Food and Agricultural Sciences, University of Florida, Ruskin, FL, USA
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Ribas L, Crespo B, Sánchez-Baizán N, Xavier D, Kuhl H, Rodríguez JM, Díaz N, Boltañá S, MacKenzie S, Morán F, Zanuy S, Gómez A, Piferrer F. Characterization of the European Sea Bass (Dicentrarchus labrax) Gonadal Transcriptome During Sexual Development. MARINE BIOTECHNOLOGY (NEW YORK, N.Y.) 2019; 21:359-373. [PMID: 30919121 DOI: 10.1007/s10126-019-09886-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Accepted: 02/18/2019] [Indexed: 06/09/2023]
Abstract
The European sea bass is one of the most important cultured fish in Europe and has a marked sexual growth dimorphism in favor of females. It is a gonochoristic species with polygenic sex determination, where a combination between still undifferentiated genetic factors and environmental temperature determines sex ratios. The molecular mechanisms responsible for gonadal sex differentiation are still unknown. Here, we sampled fish during the gonadal developmental period (110 to 350 days post fertilization, dpf), and performed a comprehensive transcriptomic study by using a species-specific microarray. This analysis uncovered sex-specific gonadal transcriptomic profiles at each stage of development, identifying larger number of differentially expressed genes in ovaries when compared to testis. The expression patterns of 54 reproduction-related genes were analyzed. We found that hsd17β10 is a reliable marker of early ovarian differentiation. Further, three genes, pdgfb, snx1, and nfy, not previously related to fish sex differentiation, were tightly associated with testis development in the sea bass. Regarding signaling pathways, lysine degradation, bladder cancer, and NOD-like receptor signaling were enriched for ovarian development while eight pathways including basal transcription factors and steroid biosynthesis were enriched for testis development. Analysis of the transcription factor abundance showed an earlier increase in females than in males. Our results show that, although many players in the sex differentiation pathways are conserved among species, there are peculiarities in gene expression worth exploring. The genes identified in this study illustrate the diversity of players involved in fish sex differentiation and can become potential biomarkers for the management of sex ratios in the European sea bass and perhaps other cultured species.
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Affiliation(s)
- L Ribas
- Institute of Marine Sciences (ICM), Spanish National Research Council (CSIC), Barcelona, Catalonia, Spain
| | - B Crespo
- Institute of Aquaculture of Torre de la Sal (IATS-CSIC), Ribera de Cabanes s/n. Torre la Sal, 12595, Castellón, Spain
- UCL GOS Institute of Child Health, University College London, London, UK
| | - N Sánchez-Baizán
- Institute of Marine Sciences (ICM), Spanish National Research Council (CSIC), Barcelona, Catalonia, Spain
| | - D Xavier
- Department of Biochemistry and Molecular Biology I, Complutense University, Madrid, Spain
| | - H Kuhl
- Max Planck Institute for Molecular Genetics, Berlin, Germany
- Department of Ecophysiology and Aquaculture, Leibniz Institute for Freshwater Ecology and Inland Fisheries, Berlin, Germany
| | - J M Rodríguez
- Spanish National Bioinformatics Institute, Madrid, Spain
- Cardiovascular Proteomics Laboratory, Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid, Spain
| | - N Díaz
- Institute of Marine Sciences (ICM), Spanish National Research Council (CSIC), Barcelona, Catalonia, Spain
- Max Planck Institute for Molecular Biomedicine, Muenster, Germany
| | - S Boltañá
- Autonomous University of Barcelona, Barcelona, Spain
- Interdisciplinary Center for Aquaculture Research (INCAR), Department of Oceanography, Biotechnology Center, University of Concepción, Concepción, Chile
| | - S MacKenzie
- Autonomous University of Barcelona, Barcelona, Spain
- Institute of Aquaculture, University of Stirling, Stirling, Scotland, UK
| | - F Morán
- Department of Biochemistry and Molecular Biology I, Complutense University, Madrid, Spain
| | - S Zanuy
- Institute of Aquaculture of Torre de la Sal (IATS-CSIC), Ribera de Cabanes s/n. Torre la Sal, 12595, Castellón, Spain
| | - A Gómez
- Institute of Aquaculture of Torre de la Sal (IATS-CSIC), Ribera de Cabanes s/n. Torre la Sal, 12595, Castellón, Spain.
| | - F Piferrer
- Institute of Marine Sciences (ICM), Spanish National Research Council (CSIC), Barcelona, Catalonia, Spain.
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Breton TS, Kenter LW, Greenlaw K, Montgomery J, Goetz GW, Berlinsky DL, Luckenbach JA. Initiation of sex change and gonadal gene expression in black sea bass (Centropristis striata) exposed to exemestane, an aromatase inhibitor. Comp Biochem Physiol A Mol Integr Physiol 2018; 228:51-61. [PMID: 30414915 DOI: 10.1016/j.cbpa.2018.10.024] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Revised: 10/24/2018] [Accepted: 10/30/2018] [Indexed: 12/25/2022]
Abstract
Many teleost fishes exhibit sequential hermaphroditism, where male or female gonads develop first and later undergo sex change. Model sex change species are characterized by social hierarchies and coloration changes, which enable experimental manipulations to better understand these processes. However, other species such as the protogynous black sea bass (Centropristis striata) do not exhibit these characteristics and instead receive research attention due to their importance in fisheries or aquaculture. Black sea bass social structure is unknown, which makes sex change sampling difficult, and few molecular resources are available. The purpose of the present study was to induce sex change using exemestane, an aromatase inhibitor, and assess gonadal gene expression using sex markers (amh, zpc2) and genes involved in steroidogenesis (cyp19a1a, cyp11b), estrogen signaling (esr1, esr2b), and apoptosis or atresia (aen, casp9, fabp11, parg, pdcd4, rif1). Overall, dietary exemestane treatment was effective, and most exposed females exhibited early histological signs of sex change and significantly higher rates of ovarian atresia relative to control females. Genes associated with atresia did not reflect this, however, as expression patterns in sex changing gonads were overall similar to those of ovaries, likely due to a whole ovary dilution effect of the RNA. Still, small but insignificant expression decreases during early sex change were detected for ovary-related genes (aen, casp9, fabp11, zpc2) and anti-apoptotic factors (parg, rif1). Exemestane treatment did not impact spermatogenesis or testicular gene expression, but testes were generally characterized by elevated steroidogenic enzyme and estrogen receptor mRNAs. Further research will be needed to understand these processes in black sea bass, using isolated ovarian follicles and multiple stages of sex change.
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Affiliation(s)
- Timothy S Breton
- Division of Natural Sciences, University of Maine at Farmington, 173 High Street, Farmington, ME 04938, USA.
| | - Linas W Kenter
- Department of Biological Sciences, University of New Hampshire, 38 College Road, Durham, NH 03824, USA
| | - Katherine Greenlaw
- Division of Natural Sciences, University of Maine at Farmington, 173 High Street, Farmington, ME 04938, USA
| | - Jacob Montgomery
- Division of Natural Sciences, University of Maine at Farmington, 173 High Street, Farmington, ME 04938, USA
| | - Giles W Goetz
- School of Aquatic and Fishery Sciences, University of Washington, Seattle, WA 98195, USA
| | - David L Berlinsky
- Department of Agriculture, Nutrition, and Food Systems, University of New Hampshire, 46 College Road, Durham, NH 03824, USA
| | - J Adam Luckenbach
- Environmental and Fisheries Sciences Division, Northwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Seattle, WA 98112, USA; Center for Reproductive Biology, Washington State University, Pullman, WA 99164, USA
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Schaefer FJ, Hermelink B, Husmann P, Meeus W, Adriaen J, Wuertz S. Induction of gonadal maturation at different temperatures in burbot Lota lota. JOURNAL OF FISH BIOLOGY 2016; 89:2268-2281. [PMID: 27650588 DOI: 10.1111/jfb.13107] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Accepted: 07/06/2016] [Indexed: 06/06/2023]
Abstract
A rearing experiment was conducted to test whether temperature protocols that differed from a simulation of natural conditions might induce maturation after isothermal grow-out in burbot Lota lota. Lota lota were acclimated to two different temperature regimes: low temperature (LT), close to natural temperature at 4·0° C and elevated, high temperature (HT) at 8·5° C over 40 and 27 days respectively, with all fish then wintered for 47 days. Every second fish was treated with a gonadotropin-releasing hormone analogue. Maturational competence of oocytes was assessed with a germinal vesicle breakdown assay using a novel staining strategy. In both treatments, puberty and maturational progress occurred, characterised by an elevated gonado-somatic index and advanced gonadal stages (histological analysis). Progress of gonadal maturation was reflected by elevated plasma concentrations of testosterone and 11-ketosterone in males and 17β-oestradiol in females. Ovulation was not observed. Sperm could be activated equally across treatments. In general, LT was more effective than HT treatment, indicated by advanced gonadal stages, higher numbers of oocytes undergoing germinal vesicle breakdown in vitro and elevated sex steroid levels. Hormone treatment could improve effectiveness at HT. In conclusion, less drastic temperature regimes as previously reported in combination with hormone treatments seem sufficient to induce maturation in L. lota after isothermal grow-out.
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Affiliation(s)
- F J Schaefer
- Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Dept. Ecophysiology and Aquaculture, Müggelseedamm 310, 12587, Berlin, Germany
- Humboldt-Universität zu Berlin, Faculty of Life Sciences, Thaer Institute of Agricultural and Horticultural Sciences, Invalidenstraße 42, 10099, Berlin, Germany
| | - B Hermelink
- Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Dept. Ecophysiology and Aquaculture, Müggelseedamm 310, 12587, Berlin, Germany
| | - P Husmann
- Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Dept. Ecophysiology and Aquaculture, Müggelseedamm 310, 12587, Berlin, Germany
- Freie Universität Berlin, Department of Biology, Chemistry and Pharmacy, Takustraße 3, 14195, Berlin, Germany
| | - W Meeus
- Aqua-ERF, Odisee University College, Hospitaalstraat 23, 9100, Sint-Niklaas, Belgium
| | - J Adriaen
- Aqua-ERF, Odisee University College, Hospitaalstraat 23, 9100, Sint-Niklaas, Belgium
| | - S Wuertz
- Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Dept. Ecophysiology and Aquaculture, Müggelseedamm 310, 12587, Berlin, Germany.
- Humboldt-Universität zu Berlin, Faculty of Life Sciences, Thaer Institute of Agricultural and Horticultural Sciences, Invalidenstraße 42, 10099, Berlin, Germany.
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Tokarz J, Möller G, Hrabě de Angelis M, Adamski J. Steroids in teleost fishes: A functional point of view. Steroids 2015; 103:123-44. [PMID: 26102270 DOI: 10.1016/j.steroids.2015.06.011] [Citation(s) in RCA: 127] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Revised: 06/11/2015] [Accepted: 06/15/2015] [Indexed: 01/23/2023]
Abstract
Steroid hormones are involved in the regulation of a variety of processes like embryonic development, sex differentiation, metabolism, immune responses, circadian rhythms, stress response, and reproduction in vertebrates. Teleost fishes and humans show a remarkable conservation in many developmental and physiological aspects, including the endocrine system in general and the steroid hormone related processes in particular. This review provides an overview of the current knowledge about steroid hormone biosynthesis and the steroid hormone receptors in teleost fishes and compares the findings to the human system. The impact of the duplicated genome in teleost fishes on steroid hormone biosynthesis and perception is addressed. Additionally, important processes in fish physiology regulated by steroid hormones, which are most dissimilar to humans, are described. We also give a short overview on the influence of anthropogenic endocrine disrupting compounds on steroid hormone signaling and the resulting adverse physiological effects for teleost fishes. By this approach, we show that the steroidogenesis, hormone receptors, and function of the steroid hormones are reasonably well understood when summarizing the available data of all teleost species analyzed to date. However, on the level of a single species or a certain fish-specific aspect of physiology, further research is needed.
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Affiliation(s)
- Janina Tokarz
- Helmholtz Zentrum München, German Research Center for Environmental Health, Institute of Experimental Genetics, Genome Analysis Center, Ingolstaedter Landstrasse 1, 85764 Neuherberg, Germany
| | - Gabriele Möller
- Helmholtz Zentrum München, German Research Center for Environmental Health, Institute of Experimental Genetics, Genome Analysis Center, Ingolstaedter Landstrasse 1, 85764 Neuherberg, Germany
| | - Martin Hrabě de Angelis
- Helmholtz Zentrum München, German Research Center for Environmental Health, Institute of Experimental Genetics, Genome Analysis Center, Ingolstaedter Landstrasse 1, 85764 Neuherberg, Germany; Lehrstuhl für Experimentelle Genetik, Technische Universität München, 85350 Freising-Weihenstephan, Germany; Member of German Center for Diabetes Research (DZD), Ingolstaedter Landstrasse 1, 85764 Neuherberg, Germany
| | - Jerzy Adamski
- Helmholtz Zentrum München, German Research Center for Environmental Health, Institute of Experimental Genetics, Genome Analysis Center, Ingolstaedter Landstrasse 1, 85764 Neuherberg, Germany; Lehrstuhl für Experimentelle Genetik, Technische Universität München, 85350 Freising-Weihenstephan, Germany; Member of German Center for Diabetes Research (DZD), Ingolstaedter Landstrasse 1, 85764 Neuherberg, Germany.
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Kleppe L, Edvardsen RB, Furmanek T, Taranger GL, Wargelius A. Global transcriptome analysis identifies regulated transcripts and pathways activated during oogenesis and early embryogenesis in Atlantic cod. Mol Reprod Dev 2014; 81:619-35. [PMID: 24687555 PMCID: PMC4265210 DOI: 10.1002/mrd.22328] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2013] [Accepted: 03/25/2014] [Indexed: 12/28/2022]
Abstract
The molecular mechanisms underlying oogenesis and maternally controlled embryogenesis in fish are not fully understood, especially in marine species. Our aim was to study the egg and embryo transcriptome during oogenesis and early embryogenesis in Atlantic cod. Follicles from oogenesis stages (pre-, early-, and late-vitellogenic), ovulated eggs, and two embryonic stages (blastula, gastrula) were collected from broodstock fish and fertilized eggs. Gene expression profiles were measured in a 44 K oligo microarray consisting of 23,000 cod genes. Hundreds of differentially expressed genes (DEGs) were identified in the follicle stages investigated, implicating a continuous accumulation and degradation of polyadenylated transcripts throughout oogenesis. Very few DEGs were identified from ovulated egg to blastula, showing a more stable maternal RNA pool in early embryonic stages. The highest induction of expression was observed between blastula and gastrula, signifying the onset of zygotic transcription. During early vitellogenesis, several of the most upregulated genes are linked to nervous system signaling, suggesting increasing requirements for ovarian synaptic signaling to stimulate the rapid growth of oocytes. Highly upregulated genes during late vitellogenesis are linked to protein processing, fat metabolism, osmoregulation, and arrested meiosis. One of the genes with the highest upregulation in the ovulated egg is involved in oxidative phosphorylation, reflecting increased energy requirements during fertilization and the first rapid cell divisions of early embryogenesis. In conclusion, this study provides a large-scale presentation of the Atlantic cod's maternally controlled transcriptome in ovarian follicles through oogenesis, ovulated eggs, and early embryos. Mol. Reprod. Dev. 81: 619–635, 2014. © 2014 Wiley Periodicals, Inc.
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Affiliation(s)
- Lene Kleppe
- Institute of Marine Research, Bergen, Norway
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