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Garric S, Ratin M, Marie D, Foulon V, Probert I, Rodriguez F, Six C. Impaired photoacclimation in a kleptoplastidic dinoflagellate reveals physiological limits of early stages of endosymbiosis. Curr Biol 2024; 34:3064-3076.e5. [PMID: 38936366 DOI: 10.1016/j.cub.2024.05.066] [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: 02/02/2024] [Revised: 04/02/2024] [Accepted: 05/29/2024] [Indexed: 06/29/2024]
Abstract
Dinophysis dinoflagellates are predators of Mesodinium ciliates, from which they retain only the plastids of cryptophyte origin. The absence of nuclear photosynthetic cryptophyte genes in Dinophysis raises intriguing physiological and evolutionary questions regarding the functional dynamics of these temporary kleptoplastids within a foreign cellular environment. In an experimental setup including two light conditions, the comparative analysis with Mesodinium rubrum and the cryptophyte Teleaulax amphioxeia revealed that Dinophysis acuminata possessed a smaller and less dynamic functional photosynthetic antenna for green light, a function performed by phycoerythrin. We showed that the lack of the cryptophyte nucleus prevented the synthesis of the phycoerythrin α subunit, thereby hindering the formation of a complete phycoerythrin in Dinophysis. In particular, biochemical analyses showed that Dinophysis acuminata synthesized a poorly stable, incomplete phycoerythrin composed of chromophorylated β subunits, with impaired performance. We show that, consequently, a continuous supply of new plastids is crucial for growth and effective photoacclimation in this organism. Transcriptome analyses revealed that all examined strains of Dinophysis spp. have acquired the cryptophyte pebA and pebB genes through horizontal gene transfer, suggesting a potential ability to synthesize the phycobilin pigments bound to the cryptophyte phycoerythrin. By emphasizing that a potential long-term acquisition of the cryptophyte plastid relies on establishing genetic independence for essential functions such as light harvesting, this study highlights the intricate molecular challenges inherent in the enslavement of organelles and the processes involved in the diversification of photosynthetic organisms through endosymbiosis.
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Affiliation(s)
- Sarah Garric
- Sorbonne Université, Centre National de la Recherche Scientifique, UMR 7144, Adaptation et Diversité en Milieu Marin, group Ecology of Marine Plankton, Station Biologique de Roscoff, Place Georges Teissier, Roscoff 29680, France
| | - Morgane Ratin
- Sorbonne Université, Centre National de la Recherche Scientifique, UMR 7144, Adaptation et Diversité en Milieu Marin, group Ecology of Marine Plankton, Station Biologique de Roscoff, Place Georges Teissier, Roscoff 29680, France
| | - Dominique Marie
- Sorbonne Université, Centre National de la Recherche Scientifique, UMR 7144, Adaptation et Diversité en Milieu Marin, group Ecology of Marine Plankton, Station Biologique de Roscoff, Place Georges Teissier, Roscoff 29680, France
| | - Valentin Foulon
- Centre National de la Recherche Scientifique, UMR 6285 Laboratoire des Sciences et Techniques de l'information de la Communication et de la Connaissance (Lab-STICC), Technopole Brest-Iroise, Brest 29238, France
| | - Ian Probert
- Sorbonne Université, FR 2424, Station Biologique de Roscoff, Place Georges Teissier, Roscoff 29680, France
| | - Francisco Rodriguez
- Centro oceanográfico de Vigo (IEO-CSIC), Subida a Radio Faro 50, Vigo 36390, Spain
| | - Christophe Six
- Sorbonne Université, Centre National de la Recherche Scientifique, UMR 7144, Adaptation et Diversité en Milieu Marin, group Ecology of Marine Plankton, Station Biologique de Roscoff, Place Georges Teissier, Roscoff 29680, France.
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Wang H, Wu P, Xiong L, Kim HS, Kim JH, Ki JS. Nuclear genome of dinoflagellates: Size variation and insights into evolutionary mechanisms. Eur J Protistol 2024; 93:126061. [PMID: 38394997 DOI: 10.1016/j.ejop.2024.126061] [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: 10/24/2023] [Revised: 01/29/2024] [Accepted: 01/30/2024] [Indexed: 02/25/2024]
Abstract
Recent progress in high-throughput sequencing technologies has dramatically increased availability of genome data for prokaryotes and eukaryotes. Dinoflagellates have distinct chromosomes and a huge genome size, which make their genomic analysis complicated. Here, we reviewed the nuclear genomes of core dinoflagellates, focusing on the genome and cell size. Till now, the genome sizes of several dinoflagellates (more than 25) have been measured by certain methods (e.g., flow cytometry), showing a range of 3-250 pg of genomic DNA per cell. In contrast to their relatively small cell size, their genomes are huge (about 1-80 times the human haploid genome). In the present study, we collected the genome and cell size data of dinoflagellates and compared their relationships. We found that dinoflagellate genome size exhibits a positive correlation with cell size. On the other hand, we recognized that the genome size is not correlated with phylogenetic relatedness. These may be caused by genome duplication, increased gene copy number, repetitive non-coding DNA, transposon expansion, horizontal gene transfer, organelle-to-nucleus gene transfer, and/or mRNA reintegration into the genome. Ultimate verification of these factors as potential causative mechanisms would require sequencing of more dinoflagellate genomes in the future.
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Affiliation(s)
- Hui Wang
- Hunan Province Key Laboratory of Typical Environmental Pollution and Health Hazards, School of Public Health, Hengyang Medical School, University of South China, Hengyang 421001, China; Department of Life Science, Sangmyung University, Seoul 03016, Republic of Korea
| | - Peiling Wu
- Hunan Province Key Laboratory of Typical Environmental Pollution and Health Hazards, School of Public Health, Hengyang Medical School, University of South China, Hengyang 421001, China
| | - Lu Xiong
- Hunan Province Key Laboratory of Typical Environmental Pollution and Health Hazards, School of Public Health, Hengyang Medical School, University of South China, Hengyang 421001, China
| | - Han-Sol Kim
- Department of Life Science, Sangmyung University, Seoul 03016, Republic of Korea
| | - Jin Ho Kim
- Department of Earth and Marine Science, College of Ocean Sciences, Jeju National University, Jeju 63243, Republic of Korea
| | - Jang-Seu Ki
- Department of Life Science, Sangmyung University, Seoul 03016, Republic of Korea; Department of Biotechnology, Sangmyung University, Seoul 03016, Republic of Korea.
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Miyagishima SY. Taming the perils of photosynthesis by eukaryotes: constraints on endosymbiotic evolution in aquatic ecosystems. Commun Biol 2023; 6:1150. [PMID: 37952050 PMCID: PMC10640588 DOI: 10.1038/s42003-023-05544-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Accepted: 11/03/2023] [Indexed: 11/14/2023] Open
Abstract
An ancestral eukaryote acquired photosynthesis by genetically integrating a cyanobacterial endosymbiont as the chloroplast. The chloroplast was then further integrated into many other eukaryotic lineages through secondary endosymbiotic events of unicellular eukaryotic algae. While photosynthesis enables autotrophy, it also generates reactive oxygen species that can cause oxidative stress. To mitigate the stress, photosynthetic eukaryotes employ various mechanisms, including regulating chloroplast light absorption and repairing or removing damaged chloroplasts by sensing light and photosynthetic status. Recent studies have shown that, besides algae and plants with innate chloroplasts, several lineages of numerous unicellular eukaryotes engage in acquired phototrophy by hosting algal endosymbionts or by transiently utilizing chloroplasts sequestrated from algal prey in aquatic ecosystems. In addition, it has become evident that unicellular organisms engaged in acquired phototrophy, as well as those that feed on algae, have also developed mechanisms to cope with photosynthetic oxidative stress. These mechanisms are limited but similar to those employed by algae and plants. Thus, there appear to be constraints on the evolution of those mechanisms, which likely began by incorporating photosynthetic cells before the establishment of chloroplasts by extending preexisting mechanisms to cope with oxidative stress originating from mitochondrial respiration and acquiring new mechanisms.
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Affiliation(s)
- Shin-Ya Miyagishima
- Department of Gene Function and Phenomics, National Institute of Genetics, 1111 Yata, Mishima, Shizuoka, 411-8540, Japan.
- The Graduate University for Advanced Studies, SOKENDAI, 1111 Yata, Mishima, Shizuoka, 411-8540, Japan.
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Hongo Y, Kimura K, Takaki Y, Yoshida Y, Baba S, Kobayashi G, Nagasaki K, Hano T, Tomaru Y. The genome of the diatom Chaetoceros tenuissimus carries an ancient integrated fragment of an extant virus. Sci Rep 2021; 11:22877. [PMID: 34819553 PMCID: PMC8613185 DOI: 10.1038/s41598-021-00565-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Accepted: 10/11/2021] [Indexed: 11/09/2022] Open
Abstract
Diatoms are one of the most prominent oceanic primary producers and are now recognized to be distributed throughout the world. They maintain their population despite predators, infections, and unfavourable environmental conditions. One of the smallest diatoms, Chaetoceros tenuissimus, can coexist with infectious viruses during blooms. To further understand this relationship, we sequenced the C. tenuissimus strain NIES-3715 genome. A gene fragment of a replication-associated gene from the infectious ssDNA virus (designated endogenous virus-like fragment, EVLF) was found to be integrated into each 41 Mb of haploid assembly. In addition, the EVLF was transcriptionally active and conserved in nine other C. tenuissimus strains from different geographical areas, although the primary structures of their proteins varied. The phylogenetic tree further suggested that the EVLF was acquired by the ancestor of C. tenuissimus. Additionally, retrotransposon genes possessing a reverse transcriptase function were more abundant in C. tenuissimus than in Thalassiosira pseudonana and Phaeodactylum tricornutum. Moreover, a target site duplication, a hallmark for long interspersed nuclear element retrotransposons, flanked the EVLF. Therefore, the EVLF was likely integrated by a retrotransposon during viral infection. The present study provides further insights into the diatom-virus evolutionary relationship.
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Affiliation(s)
- Yuki Hongo
- Fisheries Resources Institute, Japan Fisheries Research and Education Agency, 2-12-4 Fukuura, Kanazawa, Yokohama, Kanagawa, 236-8648, Japan.
| | - Kei Kimura
- Faculty of Agriculture, Saga University, 1 Honjo-machi, Saga, 840-8502, Japan
| | - Yoshihiro Takaki
- Super-Cutting-Edge Grand and Advanced Research Program, Japan Agency for Marine-Earth Science and Technology, 2-15 Natsushima-cho, Yokosuka, Kanagawa, 237-0061, Japan
| | - Yukari Yoshida
- Super-Cutting-Edge Grand and Advanced Research Program, Japan Agency for Marine-Earth Science and Technology, 2-15 Natsushima-cho, Yokosuka, Kanagawa, 237-0061, Japan
| | - Shuichiro Baba
- United Graduate School of Agricultural Sciences, Kagoshima University, 1-21-24 Korimoto, Kagoshima, 890-0065, Japan
| | - Genta Kobayashi
- Faculty of Agriculture, Saga University, 1 Honjo-machi, Saga, 840-8502, Japan
| | - Keizo Nagasaki
- Faculty of Science and Technology, Kochi University, 200 Otsu, Monobe, Nankoku, Kochi, 783-8502, Japan
| | - Takeshi Hano
- Fisheries Technology Institute, Japan Fisheries Research and Education Agency, 2-17-5 Maruishi, Hatsukaichi, Hiroshima, 739-0452, Japan
| | - Yuji Tomaru
- Fisheries Technology Institute, Japan Fisheries Research and Education Agency, 2-17-5 Maruishi, Hatsukaichi, Hiroshima, 739-0452, Japan.
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Maselli M, Anestis K, Klemm K, Hansen PJ, John U. Retention of Prey Genetic Material by the Kleptoplastidic Ciliate Strombidium cf. basimorphum. Front Microbiol 2021; 12:694508. [PMID: 34394035 PMCID: PMC8355899 DOI: 10.3389/fmicb.2021.694508] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 06/30/2021] [Indexed: 11/13/2022] Open
Abstract
Many marine ciliate species retain functional chloroplasts from their photosynthetic prey. In some species, the functionality of the acquired plastids is connected to the simultaneous retention of prey nuclei. To date, this has never been documented in plastidic Strombidium species. The functionality of the sequestered chloroplasts in Strombidium species is thought to be independent from any nuclear control and only maintained via frequent replacement of chloroplasts from newly ingested prey. Chloroplasts sequestered from the cryptophyte prey Teleaulax amphioxeia have been shown to keep their functionality for several days in the ciliate Strombidium cf. basimorphum. To investigate the potential retention of prey genetic material in this ciliate, we applied a molecular marker specific for this cryptophyte prey. Here, we demonstrate that the genetic material from prey nuclei, nucleomorphs, and ribosomes is detectable inside the ciliate for at least 5 days after prey ingestion. Moreover, single-cell transcriptomics revealed the presence of transcripts of prey nuclear origin in the ciliate after 4 days of prey starvation. These new findings might lead to the reconsideration of the mechanisms regulating chloroplasts retention in Strombidium ciliates. The development and application of molecular tools appear promising to improve our understanding on chloroplasts retention in planktonic protists.
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Affiliation(s)
- Maira Maselli
- Marine Biological Section, Department of Biology, University of Copenhagen, Helsingør, Denmark
| | - Konstantinos Anestis
- Alfred-Wegener-Institute, Helmholtz Center for Polar and Marine Research, Bremerhaven, Germany
| | - Kerstin Klemm
- Alfred-Wegener-Institute, Helmholtz Center for Polar and Marine Research, Bremerhaven, Germany
| | - Per Juel Hansen
- Marine Biological Section, Department of Biology, University of Copenhagen, Helsingør, Denmark
| | - Uwe John
- Alfred-Wegener-Institute, Helmholtz Center for Polar and Marine Research, Bremerhaven, Germany.,Helmholtz Institute for Functional Marine Biodiversity, Oldenburg, Germany
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Abstract
The origin of plastids (chloroplasts) by endosymbiosis stands as one of the most important events in the history of eukaryotic life. The genetic, biochemical, and cell biological integration of a cyanobacterial endosymbiont into a heterotrophic host eukaryote approximately a billion years ago paved the way for the evolution of diverse algal groups in a wide range of aquatic and, eventually, terrestrial environments. Plastids have on multiple occasions also moved horizontally from eukaryote to eukaryote by secondary and tertiary endosymbiotic events. The overall picture of extant photosynthetic diversity can best be described as “patchy”: Plastid-bearing lineages are spread far and wide across the eukaryotic tree of life, nested within heterotrophic groups. The algae do not constitute a monophyletic entity, and understanding how, and how often, plastids have moved from branch to branch on the eukaryotic tree remains one of the most fundamental unsolved problems in the field of cell evolution. In this review, we provide an overview of recent advances in our understanding of the origin and spread of plastids from the perspective of comparative genomics. Recent years have seen significant improvements in genomic sampling from photosynthetic and nonphotosynthetic lineages, both of which have added important pieces to the puzzle of plastid evolution. Comparative genomics has also allowed us to better understand how endosymbionts become organelles.
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Affiliation(s)
- Shannon J Sibbald
- Department of Biochemistry & Molecular Biology, Dalhousie University, Halifax, Nova Scotia, Canada.,Centre for Comparative Genomics and Evolutionary Bioinformatics, Dalhousie University, Halifax, Nova Scotia, Canada
| | - John M Archibald
- Department of Biochemistry & Molecular Biology, Dalhousie University, Halifax, Nova Scotia, Canada.,Centre for Comparative Genomics and Evolutionary Bioinformatics, Dalhousie University, Halifax, Nova Scotia, Canada
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Gomaa F, Utter DR, Powers C, Beaudoin DJ, Edgcomb VP, Filipsson HL, Hansel CM, Wankel SD, Zhang Y, Bernhard JM. Multiple integrated metabolic strategies allow foraminiferan protists to thrive in anoxic marine sediments. SCIENCE ADVANCES 2021; 7:7/22/eabf1586. [PMID: 34039603 PMCID: PMC8153729 DOI: 10.1126/sciadv.abf1586] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Accepted: 04/05/2021] [Indexed: 05/14/2023]
Abstract
Oceanic deoxygenation is increasingly affecting marine ecosystems; many taxa will be severely challenged, yet certain nominally aerobic foraminifera (rhizarian protists) thrive in oxygen-depleted to anoxic, sometimes sulfidic, sediments uninhabitable to most eukaryotes. Gene expression analyses of foraminifera common to severely hypoxic or anoxic sediments identified metabolic strategies used by this abundant taxon. In field-collected and laboratory-incubated samples, foraminifera expressed denitrification genes regardless of oxygen regime with a putative nitric oxide dismutase, a characteristic enzyme of oxygenic denitrification. A pyruvate:ferredoxin oxidoreductase was highly expressed, indicating the capability for anaerobic energy generation during exposure to hypoxia and anoxia. Near-complete expression of a diatom's plastid genome in one foraminiferal species suggests kleptoplasty or sequestration of functional plastids, conferring a metabolic advantage despite the host living far below the euphotic zone. Through a unique integration of functions largely unrecognized among "typical" eukaryotes, benthic foraminifera represent winning microeukaryotes in the face of ongoing oceanic deoxygenation.
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Affiliation(s)
- Fatma Gomaa
- Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA.
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
| | - Daniel R Utter
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
| | - Christopher Powers
- Department of Cell and Molecular Biology, College of the Environment and Life Sciences, University of Rhode Island, Kingston, RI 02881, USA
| | - David J Beaudoin
- Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
| | - Virginia P Edgcomb
- Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
| | | | - Colleen M Hansel
- Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
| | - Scott D Wankel
- Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
| | - Ying Zhang
- Department of Cell and Molecular Biology, College of the Environment and Life Sciences, University of Rhode Island, Kingston, RI 02881, USA
| | - Joan M Bernhard
- Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA.
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Raven JA, Suggett DJ, Giordano M. Inorganic carbon concentrating mechanisms in free-living and symbiotic dinoflagellates and chromerids. JOURNAL OF PHYCOLOGY 2020; 56:1377-1397. [PMID: 32654150 DOI: 10.1111/jpy.13050] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Accepted: 06/23/2020] [Indexed: 06/11/2023]
Abstract
Photosynthetic dinoflagellates are ecologically and biogeochemically important in marine and freshwater environments. However, surprisingly little is known of how this group acquires inorganic carbon or how these diverse processes evolved. Consequently, how CO2 availability ultimately influences the success of dinoflagellates over space and time remains poorly resolved compared to other microalgal groups. Here we review the evidence. Photosynthetic core dinoflagellates have a Form II RuBisCO (replaced by Form IB or Form ID in derived dinoflagellates). The in vitro kinetics of the Form II RuBisCO from dinoflagellates are largely unknown, but dinoflagellates with Form II (and other) RuBisCOs have inorganic carbon concentrating mechanisms (CCMs), as indicated by in vivo internal inorganic C accumulation and affinity for external inorganic C. However, the location of the membrane(s) at which the essential active transport component(s) of the CCM occur(s) is (are) unresolved; isolation and characterization of functionally competent chloroplasts would help in this respect. Endosymbiotic Symbiodiniaceae (in Foraminifera, Acantharia, Radiolaria, Ciliata, Porifera, Acoela, Cnidaria, and Mollusca) obtain inorganic C by transport from seawater through host tissue. In corals this transport apparently provides an inorganic C concentration around the photobiont that obviates the need for photobiont CCM. This is not the case for tridacnid bivalves, medusae, or, possibly, Foraminifera. Overcoming these long-standing knowledge gaps relies on technical advances (e.g., the in vitro kinetics of Form II RuBisCO) that can functionally track the fate of inorganic C forms.
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Affiliation(s)
- John A Raven
- Division of Plant Sciences, University of Dundee at the James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK
- Faculty of Science, University of Technology, Sydney, Climate Change Cluster, Ultimo, Sydney, New South Wales, 2007, Australia
- School of Biological Science, University of Western Australia, 35 Stirling Highway, Crawley, Western Australia, 6009, Australia
| | - David J Suggett
- Faculty of Science, University of Technology, Sydney, Climate Change Cluster, Ultimo, Sydney, New South Wales, 2007, Australia
| | - Mario Giordano
- Dipartimento di Scienze della Vita e dell'Ambiente, Università Politecnica delle Marche, Via Brecce Bianche, 60131, Ancona, Italy
- Institute of Microbiology, Academy of Sciences of the Czech Republic, Algatech, Trebon, Czech Republic
- National Research Council, Institute of Marine Science ISMAR, Venezia, Italy
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Yamada N, Sakai H, Onuma R, Kroth PG, Horiguchi T. Five Non-motile Dinotom Dinoflagellates of the Genus Dinothrix. FRONTIERS IN PLANT SCIENCE 2020; 11:591050. [PMID: 33329655 PMCID: PMC7710806 DOI: 10.3389/fpls.2020.591050] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Accepted: 10/21/2020] [Indexed: 06/12/2023]
Abstract
Dinothrix paradoxa and Gymnodinium quadrilobatum are benthic dinoflagellates possessing diatom-derived tertiary plastids, so-called dinotoms. Due to the lack of available genetic information, their phylogenetic relationship remains unknown. In this study, sequencing of 18S ribosomal DNA (rDNA) and the rbcL gene from temporary cultures isolated from natural samples revealed that they are close relatives of another dinotom, Galeidinium rugatum. The morphologies of these three dinotoms differ significantly from each other; however, they share a distinctive life cycle, in which the non-motile cells without flagella are their dominant phase. Cell division occurs in this non-motile phase, while swimming cells only appear for several hours after being released from each daughter cell. Furthermore, we succeeded in isolating and establishing two novel dinotom strains, HG180 and HG204, which show a similar life cycle and are phylogenetically closely related to the aforementioned three species. The non-motile cells of strain HG180 are characterized by the possession of a hemispheroidal cell covered with numerous nodes, while those of the strain HG204 form aggregations consisting of spherical smooth-surface cells. Based on the similarity in life cycles and phylogenetic closeness, we conclude that all five species should belong to a single genus, Dinothrix, the oldest genus within this clade. We transferred Ga. rugatum and Gy. quadrilobatum to Dinothrix, and described strains HG180 and HG204 as Dinothrix phymatodea sp. nov. and Dinothrix pseudoparadoxa sp. nov.
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Affiliation(s)
- Norico Yamada
- Department of Natural History Sciences, Graduate School of Science, Hokkaido University, Sapporo, Japan
- Department of Biology, University of Konstanz, Konstanz, Germany
| | - Hiroto Sakai
- Department of Natural History Sciences, Graduate School of Science, Hokkaido University, Sapporo, Japan
| | - Ryo Onuma
- Department of Natural History Sciences, Graduate School of Science, Hokkaido University, Sapporo, Japan
| | - Peter G. Kroth
- Department of Biology, University of Konstanz, Konstanz, Germany
| | - Takeo Horiguchi
- Department of Biological Sciences, Faculty of Science, Hokkaido University, Sapporo, Japan
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Nyuji M, Hongo Y, Yoneda M, Nakamura M. Transcriptome characterization of BPG axis and expression profiles of ovarian steroidogenesis-related genes in the Japanese sardine. BMC Genomics 2020; 21:668. [PMID: 32993516 PMCID: PMC7526130 DOI: 10.1186/s12864-020-07080-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Accepted: 09/18/2020] [Indexed: 11/10/2022] Open
Abstract
Background The clupeoid fishes are ecologically and commercially important fish species worldwide that exhibit a high level of population fluctuation, accompanied by alteration of reproductive traits. However, knowledge about their reproductive physiology in order to understand mechanisms underlying such population dynamics is limited. The endocrine system along with the brain–pituitary–gonadal (BPG) axis is critical for regulating reproduction. The aims of this study were to provide transcript data and genes related to the BPG axis, and to characterize the expression profiles of ovarian steroidogenesis-related genes in the Japanese sardine (Sardinops melanostictus, Clupeidae). Results RNA sequencing was performed using the sardine brain, pituitary, and gonad in both sexes. A total of 290,119 contigs were obtained and 115,173 non-redundant ORFs were annotated. The genes differentially expressed between ovary and testis were strongly associated with GO terms related to gamete production. The tissue-specific profile of the abundance of transcripts was characterized for the major regulators in the BPG axis, such as gonadotropin-releasing hormone, gonadotropin, and steroidogenic enzyme. By comparing between ovary and testis, out of eight different 17β-hydroxysteroid dehydrogenase (Hsd17b) genes identified, higher hsd17b7 expression was found in testis, whereas higher expression of hsd17b8, hsd17b10, hsd17b12a, and hsd17b12b was found in ovary. The cDNAs encoding key endocrine factors in the ovarian steroidogenic pathway were cloned, sequenced, and quantitatively assayed. In the pituitary, follicle-stimulating hormone beta peaked during vitellogenesis, while luteinizing hormone beta peaked at the completion of vitellogenesis. In the ovary, follicle-stimulating hormone receptor and luteinizing hormone receptor were upregulated from mid- to late phase of vitellogenesis. Furthermore, three steroidogenic enzyme genes (cyp11a1, cyp17a1, and cyp19a1a) gradually increased their expression during ovarian development, accompanying a rise in serum estradiol-17β, while 3β-hydroxysteroid dehydrogenase and steroidogenic acute regulatory protein did not change significantly. Conclusions This is the first report of deep RNA sequencing analysis of Japanese sardine, in which many key genes involved in the BPG axis were identified. Expression profiles of ovarian steroidogenesis-related genes provide a molecular basis of the physiological processes underlying ovarian development in the sardine. Our study will be a valuable resource for clarifying the molecular biology of clupeoid fishes.
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Affiliation(s)
- Mitsuo Nyuji
- Fisheries Resources Institute, Japan Fisheries Research and Education Agency, Yokohama, 236-8648, Japan.
| | - Yuki Hongo
- Fisheries Resources Institute, Japan Fisheries Research and Education Agency, Yokohama, 236-8648, Japan
| | - Michio Yoneda
- Hakatajima Field Station, Fisheries Technology Institute, Japan Fisheries Research and Education Agency, Kinoura, Imabari, Ehime, 794-2305, Japan
| | - Masahiro Nakamura
- Hakatajima Field Station, Fisheries Technology Institute, Japan Fisheries Research and Education Agency, Kinoura, Imabari, Ehime, 794-2305, Japan
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