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Mizobata H, Tomita K, Yonezawa R, Hayashi K, Kinoshita S, Yoshitake K, Asakawa S. The highly developed symbiotic system between the solar-powered nudibranch Pteraeolidia semperi and Symbiodiniacean algae. iScience 2023; 26:108464. [PMID: 38125017 PMCID: PMC10730344 DOI: 10.1016/j.isci.2023.108464] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 10/09/2023] [Accepted: 11/13/2023] [Indexed: 12/23/2023] Open
Abstract
The intricate coexistence of Symbiodiniacean algae with a diverse range of marine invertebrates underpins the flourishing biodiversity observed within coral reef ecosystems. However, the breakdown of Symbiodiniaceae-host symbiosis endangers these ecosystems, necessitating urgent study of the symbiotic mechanisms. The symbiosis between nudibranchs and Symbiodiniaceae has been identified as an efficacious model for examining these mechanisms, yet a comprehensive understanding of their histological structures and cellular processes remains elusive. A meticulous histological exploration of the nudibranch Pteraeolidia semperi, employing optical, fluorescence, and electron microscopy, has revealed fine tubules extending to the body surface, with associated epithelial cells having been shown to adeptly encapsulate Symbiodiniaceae intracellularly. By tracing the stages of the "bleaching" in nudibranchs, it was inferred that algal cells, translocated via the digestive gland, are directly phagocytosed and expelled by these epithelial cells. Collectively, these insights contribute substantially to the scholarly discourse on critical marine symbiotic associations.
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Affiliation(s)
- Hideaki Mizobata
- Department of Aquatic Bioscience, Graduate School of Agricultural and Life Sciences, the University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Kenji Tomita
- Technology Advancement Center, Graduate School of Agricultural and Life Sciences, the University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Ryo Yonezawa
- Department of Aquatic Bioscience, Graduate School of Agricultural and Life Sciences, the University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Kentaro Hayashi
- Department of Aquatic Bioscience, Graduate School of Agricultural and Life Sciences, the University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Shigeharu Kinoshita
- Department of Aquatic Bioscience, Graduate School of Agricultural and Life Sciences, the University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Kazutoshi Yoshitake
- Department of Aquatic Bioscience, Graduate School of Agricultural and Life Sciences, the University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Shuichi Asakawa
- Department of Aquatic Bioscience, Graduate School of Agricultural and Life Sciences, the University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan
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Assessing the Trophic Impact of Bleaching: The Model Pair Berghia stephanieae/ Exaiptasia diaphana. Animals (Basel) 2023; 13:ani13020291. [PMID: 36670832 PMCID: PMC9854479 DOI: 10.3390/ani13020291] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2022] [Revised: 01/09/2023] [Accepted: 01/10/2023] [Indexed: 01/18/2023] Open
Abstract
Bleaching events associated with climate change are increasing worldwide, being a major threat to tropical coral reefs. Nonetheless, the indirect impacts promoted by the bleaching of organisms hosting photosynthetic endosymbionts, such as those impacting trophic interactions, have received considerably less attention by the scientific community. Bleaching significantly affects the nutritional quality of bleached organisms. The consequences promoted by such shifts remain largely overlooked, namely on specialized predators that have evolved to prey upon organisms hosting photosynthetic endosymbionts and benefit nutritionally, either directly or indirectly, from the available pool of photosynthates. In the present study, we advocate the use of the model predator-prey pair featuring the stenophagous nudibranch sea slug Berghia stephanieae that preys upon the photosymbiotic glass anemone Exaiptasia diaphana to study the impacts of bleaching on trophic interactions. These model organisms are already used in other research fields, and one may benefit from knowledge available on their physiology, omics, and culture protocols under controlled laboratory conditions. Moreover, B. stephanieae can thrive on either photosymbiotic or aposymbiotic (bleached) glass anemones, which can be easily maintained over long periods in the laboratory (unlike photosymbiotic corals). As such, one can investigate if and how nutritional shifts induced by bleaching impact highly specialized predators (stenophagous species), as well as if and how such effects cascade over consecutive generations. Overall, by using this model predator-prey pair one can start to truly unravel the trophic effects of bleaching events impacting coral reef communities, as well as their prevalence over time.
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Multiple bacterial partners in symbiosis with the nudibranch mollusk Rostanga alisae. Sci Rep 2022; 12:169. [PMID: 34997021 PMCID: PMC8742107 DOI: 10.1038/s41598-021-03973-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Accepted: 12/13/2021] [Indexed: 01/23/2023] Open
Abstract
The discovery of symbiotic associations extends our understanding of the biological diversity in the aquatic environment and their impact on the host’s ecology. Of particular interest are nudibranchs that unprotected by a shell and feed mainly on sponges. The symbiotic association of the nudibranch Rostanga alisae with bacteria was supported by ample evidence, including an analysis of cloned bacterial 16S rRNA genes and a fluorescent in situ hybridization analysis, and microscopic observations. A total of 74 clones belonging to the phyla α-, β-, γ-Proteobacteria, Actinobacteria, and Cyanobacteria were identified. FISH confirmed that bacteriocytes were packed with Bradyrhizobium, Maritalea, Labrenzia, Bulkholderia, Achromobacter, and Stenotrophomonas mainly in the foot and notum epidermis, and also an abundance of Synechococcus cyanobacteria in the intestinal epithelium. An ultrastructural analysis showed several bacterial morphotypes of bacteria in epidermal cells, intestine epithelium, and in mucus layer covering the mollusk body. The high proportion of typical bacterial fatty acids in R. alisae indicated that symbiotic bacteria make a substantial contribution to its nutrition. Thus, the nudibranch harbors a high diversity of specific endo- and extracellular bacteria, which previously unknown as symbionts of marine invertebrates that provide the mollusk with essential nutrients. They can provide chemical defense against predators.
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Melo Clavijo J, Drews F, Pirritano M, Simon M, Salhab A, Donath A, Frankenbach S, Serôdio J, Bleidißel S, Preisfeld A, Christa G. The complete mitochondrial genome of the photosymbiotic sea slug Berghia stephanieae (Valdés, 2005) (Gastropoda, Nudibranchia). Mitochondrial DNA B Resour 2021; 6:2281-2284. [PMID: 34291161 PMCID: PMC8279152 DOI: 10.1080/23802359.2021.1914211] [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] [Indexed: 11/01/2022] Open
Abstract
Berghia stephanieae (Nudibranchia, Cladobranchia) is a photosymbiotic sea slug that feeds exclusively on sea anemones from the genus Exaiptasia. It then specifically incorporates dinoflagellates belonging to the Symbiodiniaceae obtained from their prey. Here, we present the complete mitochondrial genome sequence of B. stephanieae combining Oxford Nanopore long read and Illumina short-read sequencing data. The mitochondrial genome has a total length of 14,786 bp, it contains the 13 protein-encoding genes, 23 tRNAs, and two rRNAs and is similar to other nudibranchs except for the presence of a duplicated tRNA-Ser 1.
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Affiliation(s)
- Jenny Melo Clavijo
- Bergische Universität Wuppertal, Fakultät für Mathematik und Naturwissenschaften, Zoologie und Biologiedidaktik, Wuppertal, Germany
| | - Franziska Drews
- Bergische Universität Wuppertal, Fakultät für Mathematik und Naturwissenschaften, Chemie und Biologie, Molekulare Zellbiologie und Mikrobiologie, Wuppertal, Germany
| | - Marcello Pirritano
- Bergische Universität Wuppertal, Fakultät für Mathematik und Naturwissenschaften, Chemie und Biologie, Molekulare Zellbiologie und Mikrobiologie, Wuppertal, Germany
| | - Martin Simon
- Bergische Universität Wuppertal, Fakultät für Mathematik und Naturwissenschaften, Chemie und Biologie, Molekulare Zellbiologie und Mikrobiologie, Wuppertal, Germany
| | | | - Alexander Donath
- Zoologisches Forschungsinstitut und Museum Alexander Koenig, Bonn, Germany
| | - Silja Frankenbach
- Department of Biology and CESAM, Centre for Environmental and Marine Studies, University of Aveiro, Aveiro, Portugal
| | - João Serôdio
- Department of Biology and CESAM, Centre for Environmental and Marine Studies, University of Aveiro, Aveiro, Portugal
| | - Sabrina Bleidißel
- Bergische Universität Wuppertal, Fakultät für Mathematik und Naturwissenschaften, Zoologie und Biologiedidaktik, Wuppertal, Germany
| | - Angelika Preisfeld
- Bergische Universität Wuppertal, Fakultät für Mathematik und Naturwissenschaften, Zoologie und Biologiedidaktik, Wuppertal, Germany
| | - Gregor Christa
- Bergische Universität Wuppertal, Fakultät für Mathematik und Naturwissenschaften, Zoologie und Biologiedidaktik, Wuppertal, Germany
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Prevalence and Photobiology of Photosynthetic Dinoflagellate Endosymbionts in the Nudibranch Berghia stephanieae. Animals (Basel) 2021; 11:ani11082200. [PMID: 34438657 PMCID: PMC8388370 DOI: 10.3390/ani11082200] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Revised: 07/21/2021] [Accepted: 07/21/2021] [Indexed: 11/17/2022] Open
Abstract
Simple Summary Some sea slugs have evolved highly specialized feeding habits and solely prey upon a reduced number of species. This is the case of Berghia stephanieae, a sea slug that feeds exclusively on glass anemones, such as Exaiptasia diaphana. Glass anemones host photosynthetic microalgae that B. stephanieae ingest when preying upon E. diaphana. The association between these photosynthetic microalgae and sea slugs appears to be limited in time, particularly if B. stephanieae is deprived of prey hosting these microalgae. In the present study, we validate the use of a non-invasive and non-destructive approach that allows monitoring the persistence of this association in live sea slugs by measuring chlorophyll fluorescence. A complete loss of photosynthetic microalgae was observed within 8 days when animals were deprived of food or fed glass anemones with no microalgae (bleached anemones). As such, the association between B. stephanieae and photosynthetic microalgae acquired when preying glass anemones is not a true symbiosis. Future studies may use the technique here described to monitor the prevalence of the association between sea slugs and photosynthetic microalgae, particularly under bleaching events that will impair sea slugs to acquire microalgae by preying upon their invertebrate hosts. Abstract Berghia stephanieae is a stenophagous sea slug that preys upon glass anemones, such as Exaiptasia diaphana. Glass anemones host photosynthetic dinoflagellate endosymbionts that sea slugs ingest when consuming E. diaphana. However, the prevalence of these photosynthetic dinoflagellate endosymbionts in sea slugs appears to be short-lived, particularly if B.stephanieae is deprived of prey that host these microalgae (e.g., during bleaching events impacting glass anemones). In the present study, we investigated this scenario, along with food deprivation, and validated the use of a non-invasive and non-destructive approach employing chlorophyll fluorescence as a proxy to monitor the persistence of the association between sea slugs and endosymbiotic photosynthetic dinoflagellates acquired through the consumption of glass anemones. Berghia stephanieae deprived of a trophic source hosting photosynthetic dinoflagellate endosymbionts (e.g., through food deprivation or by feeding on bleached E. diaphana) showed a rapid decrease in minimum fluorescence (Fo) and photosynthetic efficiency (Fv/Fm) when compared to sea slugs fed with symbiotic anemones. A complete loss of endosymbionts was observed within 8 days, confirming that no true symbiotic association was established. The present work opens a new window of opportunity to rapidly monitor in vivo and over time the prevalence of associations between sea slugs and photosynthetic dinoflagellate endosymbionts, particularly during bleaching events that prevent sea slugs from incorporating new microalgae through trophic interactions.
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Watson WH, Bourque KMF, Sullivan JR, Miller M, Buell A, Kallins MG, Curtis NE, Pierce SK, Blackman E, Urato S, Newcomb JM. The Digestive Diverticula in the Carnivorous Nudibranch, Melibe leonina, Do Not Contain Photosynthetic Symbionts. Integr Org Biol 2021; 3:obab015. [PMID: 34337322 PMCID: PMC8319451 DOI: 10.1093/iob/obab015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
A number of nudibranchs, including Melibe engeli and Melibe pilosa, harbor symbiotic photosynthetic zooxanthellae. Melibe leonina spends most of its adult life on seagrass or kelp, capturing planktonic organisms in the water column with a large, tentacle-lined oral hood that brings food to its mouth. M. leonina also has an extensive network of digestive diverticula, located just beneath its translucent integument, that are typically filled with pigmented material likely derived from ingested food. Therefore, the focus of this project was to test the hypothesis that M. leonina accumulates symbiotic photosynthetic dinoflagellates in these diverticula. First, we conducted experiments to determine if M. leonina exhibits a preference for light, which would allow chloroplasts that it might be harboring to carry out photosynthesis. We found that most M. leonina preferred shaded areas and spent less time in direct sunlight. Second, we examined the small green circular structures in cells lining the digestive diverticula. Like chlorophyll, they exhibited autofluorescence when illuminated at 480 nm, and they were also about the same size as chloroplasts and symbiotic zooxanthellae. However, subsequent electron microscopy found no evidence of chloroplasts in the digestive diverticula of M. leonina; the structures exhibiting autofluorescence at 480 nm were most likely heterolysosomes, consistent with normal molluscan digestion. Third, we did not find evidence of altered oxygen consumption or production in M. leonina housed in different light conditions, suggesting the lack of any significant photosynthetic activity in sunlight. Fourth, we examined the contents of the diverticula, using HPLC, thin layer chromatography, and spectroscopy. The results of these studies indicate that the diverticula did not contain any chlorophyll, but rather harbored other pigments, such as astaxanthin, which likely came from crustaceans in their diet. Together, all of these data suggest that M. leonina does sequester pigments from its diet, but not for the purpose of symbiosis with photosynthetic zooxanthellae. Considering the translucent skin of M. leonina, the pigmented diverticula may instead provide camouflage.
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Affiliation(s)
- W H Watson
- Department of Biological Sciences, University of New Hampshire, Durham, NH 03824, USA
| | - K M F Bourque
- Department of Biological Sciences, University of New Hampshire, Durham, NH 03824, USA
- Department of Pediatrics, Johns Hopkins Hospital, Baltimore, MD 21287, USA
| | - J R Sullivan
- Department of Biological Sciences, University of New Hampshire, Durham, NH 03824, USA
- Department of Human Development and Family Studies, University of New Hampshire, Durham, NH 03824, USA
| | - M Miller
- Department of Biological Sciences, University of New Hampshire, Durham, NH 03824, USA
| | - A Buell
- Department of Biological Sciences, University of New Hampshire, Durham, NH 03824, USA
- Department of Psychiatry, Dartmouth College Geisel School of Medicine, Hanover, NH 03755, USA
| | - M G Kallins
- Department of Biology, Rollins College, Winter Park, FL 32789, USA
| | - N E Curtis
- Department of Biology, Rollins College, Winter Park, FL 32789, USA
- Department of Biology, Ave Maria University, Ave Maria, FL 34142, USA
| | - S K Pierce
- Department of Integrative Biology, University of South Florida, Tampa, FL 33620, USA
- Department of Biology, University of Maryland, College Park, MD 20742, USA
| | - E Blackman
- Department of Biology and Health Science, New England College, Henniker, NH 03242, USA
- College of Osteopathic Medicine, Lake Erie College of Osteopathic Medicine, Bradenton, FL 34211, USA
| | - S Urato
- Department of Biology and Health Science, New England College, Henniker, NH 03242, USA
| | - J M Newcomb
- Department of Biology and Health Science, New England College, Henniker, NH 03242, USA
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