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Laetz EMJ, Kahyaoglu C, Borgstein NM, Merkx M, van der Meij SET, Verberk WCEP. Critical thermal maxima and oxygen uptake in Elysia viridis, a sea slug that steals chloroplasts to photosynthesize. J Exp Biol 2024; 227:jeb246331. [PMID: 38629207 DOI: 10.1242/jeb.246331] [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: 06/19/2023] [Accepted: 03/31/2024] [Indexed: 05/31/2024]
Abstract
Photosynthetic animals produce oxygen, providing an ideal lens for studying how oxygen dynamics influence thermal sensitivity. The algivorous sea slug Elysia viridis can steal and retain chloroplasts from the marine alga Bryopsis sp. for months when starved, but chloroplast retention is mere weeks when they are fed another green alga, Chaetomorpha sp. To examine plasticity in thermal tolerance and changes in net oxygen exchange when fed and starving, slugs fed each alga were acclimated to 17°C (the current maximum temperature to which they are exposed in nature) and 22°C (the increase predicted for 2100) and measured at different points during starvation. We also examined increased illumination to evaluate a potential tradeoff between increased oxygen production but faster chloroplast degradation. Following acclimation, we subjected slugs to acute thermal stress to determine their thermal tolerance. We also measured net oxygen exchange before and after acute thermal stress. Thermal tolerance improved in slugs acclimated to 22°C, indicating they can acclimate to temperatures higher than they naturally experience. All slugs exhibited net oxygen uptake, and rates were highest in recently fed slugs before exposure to acute thermal stress. Oxygen uptake was suppressed following acute thermal stress. Under brighter light, slugs exhibited improved thermal tolerance, possibly because photosynthetic oxygen production alleviated oxygen limitation. Accordingly, this advantage disappeared later in starvation when photosynthesis ceased. Thus, E. viridis can cope with heatwaves by suppressing metabolism and plastically adjusting heat tolerance; however, starvation influences a slug's thermal tolerance and oxygen uptake such that continuous access to algal food for its potential nutritive and oxygenic benefits is critical when facing thermal stress.
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Affiliation(s)
- Elise M J Laetz
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands
| | - Can Kahyaoglu
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands
| | - Natascha M Borgstein
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands
| | - Michiel Merkx
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands
| | - Sancia E T van der Meij
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands
- Naturalis Biodiversity Center, Darwinweg 2, 2333 CR Leiden, The Netherlands
| | - Wilco C E P Verberk
- Department of Ecology, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
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2
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Cartaxana P, Morelli L, Cassin E, Havurinne V, Cabral M, Cruz S. Prey species and abundance affect growth and photosynthetic performance of the polyphagous sea slug Elysia crispata. ROYAL SOCIETY OPEN SCIENCE 2023; 10:230810. [PMID: 37650060 PMCID: PMC10465201 DOI: 10.1098/rsos.230810] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Accepted: 08/10/2023] [Indexed: 09/01/2023]
Abstract
Some sacoglossan sea slugs steal functional macroalgal chloroplasts (kleptoplasts). In this study, we investigated the effects of algal prey species and abundance on the growth and photosynthetic capacity of the tropical polyphagous sea slug Elysia crispata. Recently hatched sea slugs fed and acquired chloroplasts from the macroalga Bryopsis plumosa, but not from Acetabularia acetabulum. However, adult sea slugs were able to switch diet to A. acetabulum, rapidly replacing the great majority of the original kleptoplasts. When fed with B. plumosa, higher feeding frequency resulted in significantly higher growth and kleptoplast photosynthetic yield, as well as a slower relative decrease in these parameters upon starvation. Longevity of A. acetabulum-derived chloroplasts in E. crispata was over twofold that of B. plumosa. Furthermore, significantly lower relative weight loss under starvation was observed in sea slugs previously fed on A. acetabulum than on B. plumosa. This study shows that functionality and longevity of kleptoplasts in photosynthetic sea slugs depend on the origin of the plastids. Furthermore, we have identified A. acetabulum as a donor of photosynthetically efficient chloroplasts common to highly specialized monophagous and polyphagous sea slugs capable of long-term retention, which opens new experimental routes to unravel the unsolved mysteries of kleptoplasty.
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Affiliation(s)
- Paulo Cartaxana
- ECOMARE – Laboratory for Innovation and Sustainability of Marine Biological Resources, CESAM – Centre for Environmental and Marine Studies, Department of Biology, University of Aveiro, Aveiro 3810-193, Portugal
| | - Luca Morelli
- ECOMARE – Laboratory for Innovation and Sustainability of Marine Biological Resources, CESAM – Centre for Environmental and Marine Studies, Department of Biology, University of Aveiro, Aveiro 3810-193, Portugal
| | - Elena Cassin
- ECOMARE – Laboratory for Innovation and Sustainability of Marine Biological Resources, CESAM – Centre for Environmental and Marine Studies, Department of Biology, University of Aveiro, Aveiro 3810-193, Portugal
| | - Vesa Havurinne
- ECOMARE – Laboratory for Innovation and Sustainability of Marine Biological Resources, CESAM – Centre for Environmental and Marine Studies, Department of Biology, University of Aveiro, Aveiro 3810-193, Portugal
| | - Miguel Cabral
- ECOMARE – Laboratory for Innovation and Sustainability of Marine Biological Resources, CESAM – Centre for Environmental and Marine Studies, Department of Biology, University of Aveiro, Aveiro 3810-193, Portugal
| | - Sónia Cruz
- ECOMARE – Laboratory for Innovation and Sustainability of Marine Biological Resources, CESAM – Centre for Environmental and Marine Studies, Department of Biology, University of Aveiro, Aveiro 3810-193, Portugal
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3
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Light modulates the lipidome of the photosynthetic sea slug Elysia timida. Biochim Biophys Acta Mol Cell Biol Lipids 2023; 1868:159249. [PMID: 36336252 DOI: 10.1016/j.bbalip.2022.159249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Revised: 10/27/2022] [Accepted: 10/28/2022] [Indexed: 11/06/2022]
Abstract
Long-term kleptoplasty, the capability to retain functional stolen chloroplasts (kleptoplasts) for several weeks to months, has been shown in a handful of Sacoglossa sea slugs. One of these sea slugs is Elysia timida, endemic to the Mediterranean, which retains functional chloroplasts of the macroalga Acetabularia acetabulum. To understand how light modulates the lipidome of E. timida, sea slug specimens were subjected to two different 4-week light treatments: regular light and quasi-dark conditions. Lipidomic analyses were performed by HILIC-HR-ESI-MS and MS/MS. Quasi-dark conditions caused a reduction in the amount of essential lipids for photosynthetic membranes, such as glycolipids, indicating high level of kleptoplast degradation under sub-optimal light conditions. However, maximum photosynthetic capacities (Fv/Fm) were identical in both light treatments (≈0.75), showing similar kleptoplast functionality and suggesting that older kleptoplasts were targeted for degradation. Although more stable, the phospholipidome showed differences between light treatments: the amount of certain lipid species of phosphatidylethanolamine (PE), phosphatidylinositol (PI), and phosphatidylglycerol (PG) decreased under quasi-dark conditions, while other lipid species of phosphatidylcholine (PC), PE and lyso-PE (LPE) increased. Quasi-dark conditions promoted a decrease in the relative abundance of polyunsaturated fatty acids. These results suggest a light-driven remodelling of the lipidome according to the functions of the different lipids and highlight the plasticity of polar lipids in the photosynthetic sea slug E. timida.
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4
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A methodological note on using next generation sequencing technology to identify the algal sources of stolen chloroplasts in a single sea slug specimen (Elysia crispata) to provide a comprehensive view of the animal’s kleptoplast population. Symbiosis 2023. [DOI: 10.1007/s13199-023-00895-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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5
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Abstract
Kleptoplasty, the process by which a host organism sequesters and retains algal chloroplasts, is relatively common in protists. The origin of the plastid varies, as do the length of time it is retained in the host and the functionality of the association. In metazoa, the capacity for long-term (several weeks to months) maintenance of photosynthetically active chloroplasts is a unique characteristic of a handful of sacoglossan sea slugs. This capability has earned these slugs the epithets "crawling leaves" and "solar-powered sea slugs." This Unsolved Mystery explores the basis of chloroplast maintenance and function and attempts to clarify contradictory results in the published literature. We address some of the mysteries of this remarkable association. Why are functional chloroplasts retained? And how is the function of stolen chloroplasts maintained without the support of the algal nucleus?
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6
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Havurinne V, Aitokari R, Mattila H, Käpylä V, Tyystjärvi E. Ultraviolet screening by slug tissue and tight packing of plastids protect photosynthetic sea slugs from photoinhibition. PHOTOSYNTHESIS RESEARCH 2022; 152:373-387. [PMID: 34826025 PMCID: PMC9458594 DOI: 10.1007/s11120-021-00883-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Accepted: 10/22/2021] [Indexed: 05/16/2023]
Abstract
One of the main mysteries regarding photosynthetic sea slugs is how the slug plastids handle photoinhibition, the constant light-induced damage to Photosystem II of photosynthesis. Recovery from photoinhibition involves proteins encoded by both the nuclear and plastid genomes, and slugs with plastids isolated from the algal nucleus are therefore expected to be incapable of constantly repairing the damage as the plastids inside the slugs grow old. We studied photoinhibition-related properties of the sea slug Elysia timida that ingests its plastids from the green alga Acetabularia acetabulum. Spectral analysis of both the slugs and the algae revealed that there are two ways the slugs use to avoid major photoinhibition of their plastids. Firstly, highly photoinhibitory UV radiation is screened by the slug tissue or mucus before it reaches the plastids. Secondly, the slugs pack the plastids tightly in their thick bodies, and therefore plastids in the outer layers protect the inner ones from photoinhibition. Both properties are expected to greatly improve the longevity of the plastids inside the slugs, as the plastids do not need to repair excessive amounts of damage.
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Affiliation(s)
- Vesa Havurinne
- Department of Life Technologies/Molecular Plant Biology, University of Turku, Turku, Finland
| | - Riina Aitokari
- Department of Life Technologies/Molecular Plant Biology, University of Turku, Turku, Finland
| | - Heta Mattila
- Department of Life Technologies/Molecular Plant Biology, University of Turku, Turku, Finland
| | - Ville Käpylä
- Department of Life Technologies/Molecular Plant Biology, University of Turku, Turku, Finland
| | - Esa Tyystjärvi
- Department of Life Technologies/Molecular Plant Biology, University of Turku, Turku, Finland.
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7
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Cartaxana P, Rey F, LeKieffre C, Lopes D, Hubas C, Spangenberg JE, Escrig S, Jesus B, Calado G, Domingues R, Kühl M, Calado R, Meibom A, Cruz S. Photosynthesis from stolen chloroplasts can support sea slug reproductive fitness. Proc Biol Sci 2021; 288:20211779. [PMID: 34583582 PMCID: PMC8479339 DOI: 10.1098/rspb.2021.1779] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Accepted: 09/07/2021] [Indexed: 12/13/2022] Open
Abstract
Some sea slugs are able to steal functional chloroplasts (kleptoplasts) from their algal food sources, but the role and relevance of photosynthesis to the animal host remain controversial. While some researchers claim that kleptoplasts are slowly digestible 'snacks', others advocate that they enhance the overall fitness of sea slugs much more profoundly. Our analysis shows light-dependent incorporation of 13C and 15N in the albumen gland and gonadal follicles of the sea slug Elysia timida, representing translocation of photosynthates to kleptoplast-free reproductive organs. Long-chain polyunsaturated fatty acids with reported roles in reproduction were produced in the sea slug cells using labelled precursors translocated from the kleptoplasts. Finally, we report reduced fecundity of E. timida by limiting kleptoplast photosynthesis. The present study indicates that photosynthesis enhances the reproductive fitness of kleptoplast-bearing sea slugs, confirming the biological relevance of this remarkable association between a metazoan and an algal-derived organelle.
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Affiliation(s)
- Paulo Cartaxana
- CESAM—Centre for Environmental and Marine Studies, University of Aveiro, Aveiro 3810-193, Portugal
- Department of Biology, University of Aveiro, Aveiro 3810-193, Portugal
| | - Felisa Rey
- CESAM—Centre for Environmental and Marine Studies, University of Aveiro, Aveiro 3810-193, Portugal
- Mass Spectrometry Centre, LAQV-REQUIMTE, Department of Chemistry, University of Aveiro, Aveiro 3810-193, Portugal
| | - Charlotte LeKieffre
- Cell and Plant Physiology Laboratory, University of Grenoble Alpes, CNRS, CEA, INRAE, Grenoble Cedex, France
| | - Diana Lopes
- CESAM—Centre for Environmental and Marine Studies, University of Aveiro, Aveiro 3810-193, Portugal
| | - Cédric Hubas
- Biologie des Organismes et Écosystèmes Aquatiques (UMR BOREA 8067), Muséum National d'Histoire Naturelle, Sorbonne Université, Université de Caen Normandie, Université des Antilles, CNRS, IRD, Station Marine de Concarneau, Place de la croix, Concarneau 29900, France
| | - Jorge E. Spangenberg
- Institute of Earth Surface Dynamics (IDYST), University of Lausanne, Lausanne, CH-1015, Switzerland
| | - Stéphane Escrig
- Laboratory for Biological Geochemistry, École Polytechnique Fédérale de Lausanne, Lausanne, CH-1015, Switzerland
| | - Bruno Jesus
- Laboratoire Mer Molécules Santé, Faculté des Sciences et des Techniques, Université de Nantes, Nantes 44322, France
| | - Gonçalo Calado
- Department of Life Sciences, Lusófona University, Campo Grande 376, Lisbon 1749-024, Portugal
- NOVA School of Science and Technology, MARE—Marine and Environmental Sciences Centre, Campus de Caparica, Caparica 2829-516, Portugal
| | - Rosário Domingues
- Department of Biology, University of Aveiro, Aveiro 3810-193, Portugal
- Mass Spectrometry Centre, LAQV-REQUIMTE, Department of Chemistry, University of Aveiro, Aveiro 3810-193, Portugal
| | - Michael Kühl
- Marine Biological Section, Department of Biology, University of Copenhagen, Strandpromenaden 5, Helsingør 3000, Denmark
| | - Ricardo Calado
- CESAM—Centre for Environmental and Marine Studies, University of Aveiro, Aveiro 3810-193, Portugal
| | - Anders Meibom
- Laboratory for Biological Geochemistry, École Polytechnique Fédérale de Lausanne, Lausanne, CH-1015, Switzerland
- Center for Advanced Surface Analysis, Institute of Earth Sciences, University of Lausanne, Lausanne, CH-1015, Switzerland
| | - Sónia Cruz
- CESAM—Centre for Environmental and Marine Studies, University of Aveiro, Aveiro 3810-193, Portugal
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8
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Aoki R, Matsunaga S. A Photosynthetic Animal: A Sacoglossan Sea Slug that Steals Chloroplasts. CYTOLOGIA 2021. [DOI: 10.1508/cytologia.86.103] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Ryota Aoki
- Department of Applied Biological Science, Faculty of Science and Technology, Tokyo University of Science
| | - Sachihiro Matsunaga
- Laboratory of Integrated Biology, Department of Integrated Biosciences, Graduate School of Frontier Sciences
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9
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Seasonality and Longevity of the Functional Chloroplasts Retained by the Sacoglossan Sea Slug Plakobranchus ocellatus van Hasselt, 1824 Inhabiting A Subtropical Back Reef Off Okinawa-jima Island, Japan. Zool Stud 2021; 59:e65. [PMID: 34140982 DOI: 10.6620/zs.2020.59-65] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2020] [Accepted: 10/12/2020] [Indexed: 01/19/2023]
Abstract
Plakobranchus ocellatus is a sacoglossan sea slug that feeds on multiple algal species and retains chloroplasts as kleptoplasts for several months. The seasonal differences in the photosynthetic properties of kleptoplasts were examined in sacoglossans collected from a subtropical back reef off of Okinawa-jima (26°21'55"N 127°44'10"E) in 2017-2018. The effective quantum yield of photosystem II in kleptoplasts indicated that stronger ambient light causes more stress in kleptoplasts. The maximum quantum yields (QY) at 20°C, 30°C, and 40°C indicated that kleptoplasts were more functional in photosynthesis in winter than in spring or summer, whereas kleptoplasts may have the highest tolerance to high temperatures in summer. In the long-starvation experiment (LSE), the relative ratio of body weight (relW) linearly decreased and the sacoglossans died within 2 months in the total dark condition, whereas in the LSE with illumination, the animals survived up to 5 months. The time course for the decrease in the relative ratio of the QY (relQY) in the LSE indicated that the photosynthetic function was almost normal for 2 months, regardless of the presence or absence of illumination, after which time relQY gradually decreased to zero. In the field, P. ocellatus continuously took up new kleptoplasts that have suitable properties of photosynthetic ability for each season. In a subtropical environment, in which water temperatures vary from below 20°C to above 30°C, seasonal changes could cause a temporary shortage of algal food and affect the photosynthetic activity of P. ocellatus kleptoplast. Our results, however, indicated the kleptoplasts of P. ocellatus functioned normally for several months and maintained the presence of this sacoglossan in a subtropical environment throughout the year.
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Maeda T, Takahashi S, Yoshida T, Shimamura S, Takaki Y, Nagai Y, Toyoda A, Suzuki Y, Arimoto A, Ishii H, Satoh N, Nishiyama T, Hasebe M, Maruyama T, Minagawa J, Obokata J, Shigenobu S. Chloroplast acquisition without the gene transfer in kleptoplastic sea slugs, Plakobranchus ocellatus. eLife 2021; 10:60176. [PMID: 33902812 PMCID: PMC8079154 DOI: 10.7554/elife.60176] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Accepted: 04/01/2021] [Indexed: 12/14/2022] Open
Abstract
Some sea slugs sequester chloroplasts from algal food in their intestinal cells and photosynthesize for months. This phenomenon, kleptoplasty, poses a question of how the chloroplast retains its activity without the algal nucleus. There have been debates on the horizontal transfer of algal genes to the animal nucleus. To settle the arguments, this study reported the genome of a kleptoplastic sea slug, Plakobranchus ocellatus, and found no evidence of photosynthetic genes encoded on the nucleus. Nevertheless, it was confirmed that light illumination prolongs the life of mollusk under starvation. These data presented a paradigm that a complex adaptive trait, as typified by photosynthesis, can be transferred between eukaryotic kingdoms by a unique organelle transmission without nuclear gene transfer. Our phylogenomic analysis showed that genes for proteolysis and immunity undergo gene expansion and are up-regulated in chloroplast-enriched tissue, suggesting that these molluskan genes are involved in the phenotype acquisition without horizontal gene transfer.
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Affiliation(s)
- Taro Maeda
- National Institute for Basic Biology, Okazaki, Japan
| | - Shunichi Takahashi
- Sesoko Station, Tropical Biosphere Research Center, University of the Ryukyu, Okinawa, Japan
| | - Takao Yoshida
- Japan Agency for Marine-Earth Science and Technology, Yokosuka, Japan
| | - Shigeru Shimamura
- Japan Agency for Marine-Earth Science and Technology, Yokosuka, Japan
| | - Yoshihiro Takaki
- Japan Agency for Marine-Earth Science and Technology, Yokosuka, Japan
| | - Yukiko Nagai
- Japan Agency for Marine-Earth Science and Technology, Yokosuka, Japan
| | | | | | - Asuka Arimoto
- Marine Biological Laboratory, Hiroshima University, Hiroshima, Japan
| | | | - Nori Satoh
- Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
| | - Tomoaki Nishiyama
- Research Center for Experimental Modeling of Human Disease, Kanazawa University, Kanazawa, Japan
| | - Mitsuyasu Hasebe
- National Institute for Basic Biology, Okazaki, Japan.,SOKENDAI, the Graduate University for Advanced Studies, Okazaki, Japan
| | | | - Jun Minagawa
- National Institute for Basic Biology, Okazaki, Japan.,SOKENDAI, the Graduate University for Advanced Studies, Okazaki, Japan
| | - Junichi Obokata
- Kyoto Prefectural University, Kyoto, Japan.,Setsunan Universiy, Hirakata, Japan
| | - Shuji Shigenobu
- National Institute for Basic Biology, Okazaki, Japan.,SOKENDAI, the Graduate University for Advanced Studies, Okazaki, Japan
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11
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Cartaxana P, Cruz S. On the art of stealing chloroplasts. eLife 2020; 9:64057. [PMID: 33215989 PMCID: PMC7679131 DOI: 10.7554/elife.64057] [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: 11/18/2020] [Accepted: 11/18/2020] [Indexed: 11/16/2022] Open
Abstract
Sea slugs increase the longevity of the chloroplasts they steal from algae by limiting the harmful side-effects of photosynthesis.
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Affiliation(s)
- Paulo Cartaxana
- Department of Biology, University of Aveiro, Aveiro, Portugal.,Centre for Environmental and Marine Studies, Aveiro, Portugal
| | - Sónia Cruz
- Department of Biology, University of Aveiro, Aveiro, Portugal.,Centre for Environmental and Marine Studies, Aveiro, Portugal
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12
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Havurinne V, Tyystjärvi E. Photosynthetic sea slugs induce protective changes to the light reactions of the chloroplasts they steal from algae. eLife 2020; 9:57389. [PMID: 33077025 PMCID: PMC7679141 DOI: 10.7554/elife.57389] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Accepted: 10/07/2020] [Indexed: 12/13/2022] Open
Abstract
Sacoglossan sea slugs are able to maintain functional chloroplasts inside their own cells, and mechanisms that allow preservation of the chloroplasts are unknown. We found that the slug Elysia timida induces changes to the photosynthetic light reactions of the chloroplasts it steals from the alga Acetabularia acetabulum. Working with a large continuous laboratory culture of both the slugs (>500 individuals) and their prey algae, we show that the plastoquinone pool of slug chloroplasts remains oxidized, which can suppress reactive oxygen species formation. Slug chloroplasts also rapidly build up a strong proton-motive force upon a dark-to-light transition, which helps them to rapidly switch on photoprotective non-photochemical quenching of excitation energy. Finally, our results suggest that chloroplasts inside E. timida rely on oxygen-dependent electron sinks during rapid changes in light intensity. These photoprotective mechanisms are expected to contribute to the long-term functionality of the chloroplasts inside the slugs. Plants, algae and a few other organisms rely on a process known as photosynthesis to fuel themselves, as they can harness cellular structures called chloroplasts to convert light into usable energy. Animals typically lack chloroplasts, making them unable to use photosynthesis to power themselves. The sea slug Elysia timida, however, can steal whole chloroplasts from the cells of the algae it consumes: the stolen structures then become part of the cells in the gut of the slug, allowing the animal to gain energy from sunlight. Once they are in the digestive system of the slug, the chloroplasts survive and keep working for longer than expected. Indeed, these structures are often harmed as a side effect of photosynthesis, but the sea slug does not have the right genes to help repair this damage. In addition, conditions inside animal cells are widely different to the ones found inside algae and plants. It is not clear then how the sea slug extends the lifespan of its chloroplasts by preventing damage caused by sunlight. To investigate this question, Havurinne and Tyystjärvi compared photosynthesis in sea slugs and the algae they eat. A range of methods, including measuring fluorescence from the chloroplasts, was used: this revealed that the slug changes the inside of the stolen chloroplasts, making them more resistant to damage. First, when exposed to light the stolen chloroplasts can quickly switch on a mechanism that dissipates light energy to heat, which is less damaging. Second, a molecule that serves as an intermediate during photosynthesis is kept in a ‘safe’ state which prevents it from creating harmful compounds. And finally, additional safeguard molecules ‘deactivate’ compounds that could otherwise mediate damaging reactions. Overall, these measures may reduce the efficiency of the chloroplasts but allow them to keep working for much longer. Early chloroplasts were probably independent bacteria that were captured and ‘domesticated’ by other cells for their ability to extract energy from the sun. Photosynthesizing sea slugs therefore provide an interesting way to understand some of the challenges of early life. The work by Havurinne and Tyystjärvi may also reveal new ways to harness biological processes such as photosynthesis for energy production in other contexts.
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Affiliation(s)
- Vesa Havurinne
- University of Turku, Department of Biochemistry / Molecular Plant Biology, Turku, Finland
| | - Esa Tyystjärvi
- University of Turku, Department of Biochemistry / Molecular Plant Biology, Turku, Finland
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13
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Shiroyama H, Mitoh S, Ida TY, Yusa Y. Adaptive significance of light and food for a kleptoplastic sea slug: implications for photosynthesis. Oecologia 2020; 194:455-463. [DOI: 10.1007/s00442-020-04779-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2019] [Accepted: 10/08/2020] [Indexed: 01/23/2023]
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14
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Rey F, Melo T, Cartaxana P, Calado R, Domingues P, Cruz S, Domingues MRM. Coping with Starvation: Contrasting Lipidomic Dynamics in the Cells of Two Sacoglossan Sea Slugs Incorporating Stolen Plastids from the Same Macroalga. Integr Comp Biol 2020; 60:43-56. [PMID: 32294176 DOI: 10.1093/icb/icaa019] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Several species of sacoglossan sea slugs are able to sequester chloroplasts from algae and incorporate them into their cells. However, the ability to maintain functional "stolen" plastids (kleptoplasts) can vary significantly within the Sacoglossa, giving species different capacities to withstand periods of food shortage. The present study provides an insight on the comparative shifts experienced by the lipidome of two sacoglossan sea slug species, Elysia viridis (long-term retention of functional chloroplasts) and Placida dendritica (retention of non-functional chloroplasts). A hydrophilic interaction liquid chromatography-mass spectrometry approach was employed to screen the lipidome of specimens from both species feeding on the macroalga Codium tomentosum and after 1-week of starvation. The lipidome of E. viridis was generally unaffected by the absence of food, while that of P. dendritica varied significantly. The retention of functional chloroplasts by E. viridis cells allows this species to endure periods of food shortage, while in P. dendritica a significant reduction in the amount of main lipids was the consequence of the consumption of its own mass to endure starvation. The large proportion of ether phospholipids (plasmalogens) in both sea slug species suggests that these compounds may play a key role in chloroplast incorporation in sea slug cells and/or be involved in the reduction of the oxidative stress resulting from the presence of kleptoplasts.
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Affiliation(s)
- Felisa Rey
- CESAM, Department of Chemistry, University of Aveiro, Campus Universitário de Santiago, Aveiro 3810-193, Portugal.,Mass Spectrometry Centre & QOPNA & LAQV-REQUIMTE, Department of Chemistry, University of Aveiro, Campus Universitário de Santiago, Aveiro 3810-193, Portugal
| | - Tânia Melo
- CESAM, Department of Chemistry, University of Aveiro, Campus Universitário de Santiago, Aveiro 3810-193, Portugal.,Mass Spectrometry Centre & QOPNA & LAQV-REQUIMTE, Department of Chemistry, University of Aveiro, Campus Universitário de Santiago, Aveiro 3810-193, Portugal
| | - Paulo Cartaxana
- ECOMARE, CESAM, Department of Biology, University of Aveiro, Campus Universitário de Santiago, Aveiro 3810-193, Portugal
| | - Ricardo Calado
- ECOMARE, CESAM, Department of Biology, University of Aveiro, Campus Universitário de Santiago, Aveiro 3810-193, Portugal
| | - Pedro Domingues
- Mass Spectrometry Centre & QOPNA & LAQV-REQUIMTE, Department of Chemistry, University of Aveiro, Campus Universitário de Santiago, Aveiro 3810-193, Portugal
| | - Sónia Cruz
- ECOMARE, CESAM, Department of Biology, University of Aveiro, Campus Universitário de Santiago, Aveiro 3810-193, Portugal
| | - M Rosário M Domingues
- CESAM, Department of Chemistry, University of Aveiro, Campus Universitário de Santiago, Aveiro 3810-193, Portugal.,Mass Spectrometry Centre & QOPNA & LAQV-REQUIMTE, Department of Chemistry, University of Aveiro, Campus Universitário de Santiago, Aveiro 3810-193, Portugal
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15
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Cruz S, LeKieffre C, Cartaxana P, Hubas C, Thiney N, Jakobsen S, Escrig S, Jesus B, Kühl M, Calado R, Meibom A. Functional kleptoplasts intermediate incorporation of carbon and nitrogen in cells of the Sacoglossa sea slug Elysia viridis. Sci Rep 2020; 10:10548. [PMID: 32601288 PMCID: PMC7324368 DOI: 10.1038/s41598-020-66909-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Accepted: 05/26/2020] [Indexed: 01/16/2023] Open
Abstract
Some sacoglossan sea slugs incorporate intracellular functional algal chloroplasts, a process termed kleptoplasty. “Stolen” chloroplasts (kleptoplasts) can remain photosynthetically active up to several months, contributing to animal nutrition. Whether this contribution occurs by means of translocation of photosynthesis-derived metabolites from functional kleptoplasts to the animal host or by simple digestion of such organelles remains controversial. Imaging of 13C and 15N assimilation over a 12-h incubation period of Elysia viridis sea slugs showed a light-dependent incorporation of carbon and nitrogen, observed first in digestive tubules and followed by a rapid accumulation into chloroplast-free organs. Furthermore, this work revealed the presence of 13C-labeled long-chain fatty acids (FA) typical of marine invertebrates, such as arachidonic (20:4n-6) and adrenic (22:4n-6) acids. The time frame and level of 13C- and 15N-labeling in chloroplast-free organs indicate that photosynthesis-derived primary metabolites were made available to the host through functional kleptoplasts. The presence of specific 13C-labeled long-chain FA, absent from E. viridis algal food, indicates animal based-elongation using kleptoplast-derived FA precursors. Finally, carbon and nitrogen were incorporated in organs and tissues involved in reproductive functions (albumin gland and gonadal follicles), implying a putative role of kleptoplast photosynthesis in the reproductive fitness of the animal host.
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Affiliation(s)
- Sónia Cruz
- ECOMARE, CESAM - Centre for Environmental and Marine Studies, Department of Biology, University of Aveiro, Campus Universitário de Santiago, 3810-193, Aveiro, Portugal.
| | - Charlotte LeKieffre
- ECOMARE, CESAM - Centre for Environmental and Marine Studies, Department of Biology, University of Aveiro, Campus Universitário de Santiago, 3810-193, Aveiro, Portugal.,UMR CNRS 6112 LPG-BIAF, Université d'Angers, 2 Boulevard Lavoisier, 49045, Angers, Cedex 1, France.,Cell & Plant Physiology Laboratory, University of Grenoble Alpes, CNRS, CEA, INRA, Grenoble, France
| | - Paulo Cartaxana
- ECOMARE, CESAM - Centre for Environmental and Marine Studies, Department of Biology, University of Aveiro, Campus Universitário de Santiago, 3810-193, Aveiro, Portugal
| | - Cédric Hubas
- Biologie des Organismes et Ecosystèmes Aquatiques (BOREA), Muséum National d'Histoire Naturelle, Sorbonne Université, Université de Caen Normandie, Université des Antilles, CNRS, IRD, Station Marine de Concarneau, Place de la croix, 29900, Concarneau, France
| | - Najet Thiney
- Biologie des Organismes et Ecosystèmes Aquatiques (BOREA), Muséum National d'Histoire Naturelle, Sorbonne Université, Université de Caen Normandie, Université des Antilles, CNRS, IRD, Station Marine de Concarneau, Place de la croix, 29900, Concarneau, France
| | - Sofie Jakobsen
- Marine Biological Section, Department of Biology, University of Copenhagen, 3000, Helsingør, Denmark
| | - Stéphane Escrig
- Laboratory for Biological Geochemistry, École Polytechnique Fédérale de Lausanne, 1015, Lausanne, Switzerland
| | - Bruno Jesus
- Laboratoire Mer Molécules Santé, Faculté des Sciences et des Techniques, Université de Nantes, 44322, Nantes, France
| | - Michael Kühl
- Marine Biological Section, Department of Biology, University of Copenhagen, 3000, Helsingør, Denmark
| | - Ricardo Calado
- ECOMARE, CESAM - Centre for Environmental and Marine Studies, Department of Biology, University of Aveiro, Campus Universitário de Santiago, 3810-193, Aveiro, Portugal
| | - Anders Meibom
- Laboratory for Biological Geochemistry, École Polytechnique Fédérale de Lausanne, 1015, Lausanne, Switzerland.,Center for Advanced Surface Analysis, Institute of Earth Sciences, University of Lausanne, 1015, Lausanne, Switzerland
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16
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Bessho-Uehara M, Yamamoto N, Shigenobu S, Mori H, Kuwata K, Oba Y. Kleptoprotein bioluminescence: Parapriacanthus fish obtain luciferase from ostracod prey. SCIENCE ADVANCES 2020; 6:eaax4942. [PMID: 31934625 PMCID: PMC6949039 DOI: 10.1126/sciadv.aax4942] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Accepted: 11/11/2019] [Indexed: 06/10/2023]
Abstract
Through their diet, animals can obtain substances essential for imparting special characteristics, such as toxins in monarch butterflies and luminescent substances in jellyfishes. These substances are typically small molecules because they are less likely to be digested and may be hard for the consumer to biosynthesize. Here, we report that Parapriacanthus ransonneti, a bioluminescent fish, obtains not only its luciferin but also its luciferase enzyme from bioluminescent ostracod prey. The enzyme purified from the fish's light organs was identical to the luciferase of Cypridina noctiluca, a bioluminescent ostracod that they feed upon. Experiments where fish were fed with a related ostracod, Vargula hilgendorfii, demonstrated the specific uptake of the luciferase to the fish's light organs. This "kleptoprotein" system allows an organism to use novel functional proteins that are not encoded in its genome and provides an evolutionary alternative to DNA-based molecular evolution.
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Affiliation(s)
- Manabu Bessho-Uehara
- Monterey Bay Aquarium Research Institute, 7700 Sandholdt Road, Moss Landing, CA 95039, USA
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi 464-8601, Japan
- Department of Environmental Biology, Chubu University, Kasugai, Aichi 487-8501, Japan
| | - Naoyuki Yamamoto
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi 464-8601, Japan
| | - Shuji Shigenobu
- NIBB Core Research Facilities, National Institute for Basic Biology, Okazaki 444-8585, Japan
| | - Hitoshi Mori
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi 464-8601, Japan
| | - Keiko Kuwata
- Graduate School of Sciences, Nagoya University, Nagoya, Aichi 464-8601, Japan
| | - Yuichi Oba
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi 464-8601, Japan
- Department of Environmental Biology, Chubu University, Kasugai, Aichi 487-8501, Japan
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17
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18
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Cartaxana P, Morelli L, Jesus B, Calado G, Calado R, Cruz S. The photon menace: kleptoplast protection in the photosynthetic sea slug Elysia timida. ACTA ACUST UNITED AC 2019; 222:jeb.202580. [PMID: 31171599 DOI: 10.1242/jeb.202580] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Accepted: 06/02/2019] [Indexed: 11/20/2022]
Abstract
Absorption of excessive light by photosymbiotic organisms leads to the production of reactive oxygen species that can damage both symbiont and host. This is highly relevant in sacoglossan sea slugs that host functional chloroplasts 'stolen' from their algal foods (kleptoplasts), because of limited repair capacities resulting from the absence of algal nuclear genes. Here, we experimentally demonstrate (i) a host-mediated photoprotection mechanism in the photosynthetic sea slug Elysia timida, characterized by the closure of the parapodia under high irradiance and the reduction of kleptoplast light exposure; and (ii) the activation of a reversible xanthophyll cycle in kleptoplasts, which allows excessive energy to be dissipated. The described mechanisms reduce photoinactivation under high irradiance. We conclude that both host-mediated behavioural and plastid-based physiological photoprotective mechanisms can mitigate oxidative stress induced by high light in E. timida These mechanisms may play an important role in the establishment of long-term photosynthetically active kleptoplasts.
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Affiliation(s)
- Paulo Cartaxana
- Departamento de Biologia & CESAM & ECOMARE, Universidade de Aveiro, 3810-193 Aveiro, Portugal
| | - Luca Morelli
- Departamento de Biologia & CESAM & ECOMARE, Universidade de Aveiro, 3810-193 Aveiro, Portugal
| | - Bruno Jesus
- Laboratoire Mer Molécules Santé, Faculté des Sciences et des Techniques, Université de Nantes, 44322 Nantes, France
| | - Gonçalo Calado
- Departamento de Ciências da Vida, Universidade Lusófona, 1749-024 Lisboa, Portugal
| | - Ricardo Calado
- Departamento de Biologia & CESAM & ECOMARE, Universidade de Aveiro, 3810-193 Aveiro, Portugal
| | - Sónia Cruz
- Departamento de Biologia & CESAM & ECOMARE, Universidade de Aveiro, 3810-193 Aveiro, Portugal
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19
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Chan CX, Vaysberg P, Price DC, Pelletreau KN, Rumpho ME, Bhattacharya D. Active Host Response to Algal Symbionts in the Sea Slug Elysia chlorotica. Mol Biol Evol 2019; 35:1706-1711. [PMID: 29659974 DOI: 10.1093/molbev/msy061] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Sacoglossan sea slugs offer fascinating systems to study the onset and persistence of algal-plastid symbioses. Elysia chlorotica is particularly noteworthy because it can survive for months, relying solely on energy produced by ingested plastids of the stramenopile alga Vaucheria litorea that are sequestered in cells lining its digestive diverticula. How this animal can maintain the actively photosynthesizing organelles without replenishment of proteins from the lost algal nucleus remains unknown. Here, we used RNA-Seq analysis to test the idea that plastid sequestration leaves a significant signature on host gene expression during E. chlorotica development. Our results support this hypothesis and show that upon exposure to and ingestion of V. litorea plastids, genes involved in microbe-associated molecular patterns and oxidative stress-response mechanisms are significantly up-regulated. Interestingly, our results with E. chlorotica mirror those found with corals that maintain dinoflagellates as intact cells in symbiosomes, suggesting parallels between these animal-algal symbiotic interactions.
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Affiliation(s)
- Cheong Xin Chan
- Institute for Molecular Bioscience and School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Australia
| | - Pavel Vaysberg
- Department of Biochemistry and Microbiology, Rutgers University, New Brunswick, NJ
| | - Dana C Price
- Department of Plant Biology, Rutgers University, New Brunswick, NJ
| | - Karen N Pelletreau
- Center for Innovation in Teaching and Learning, University of Maine, Orono, ME
| | - Mary E Rumpho
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT
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20
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Christa G, Pütz L, Sickinger C, Melo Clavijo J, Laetz EMJ, Greve C, Serôdio J. Photoprotective Non-photochemical Quenching Does Not Prevent Kleptoplasts From Net Photoinactivation. Front Ecol Evol 2018. [DOI: 10.3389/fevo.2018.00121] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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21
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Cartaxana P, Morelli L, Quintaneiro C, Calado G, Calado R, Cruz S. Kleptoplast photoacclimation state modulates the photobehaviour of the solar-powered sea slug Elysia viridis. ACTA ACUST UNITED AC 2018; 221:jeb.180463. [PMID: 29712748 DOI: 10.1242/jeb.180463] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Accepted: 04/26/2018] [Indexed: 12/12/2022]
Abstract
Some sacoglossan sea slugs incorporate intracellular functional algal chloroplasts (kleptoplasty) for periods ranging from a few days to several months. Whether this association modulates the photobehaviour of solar-powered sea slugs is unknown. In this study, the long-term kleptoplast retention species Elysia viridis showed avoidance of dark independently of light acclimation state. In contrast, Placida dendritica, which shows non-functional retention of kleptoplasts, showed no preference over dark, low or high light. High light-acclimated (HLac) E. viridis showed a higher preference for high light than low light-acclimated (LLac) conspecifics. The position of the lateral folds (parapodia) was modulated by irradiance, with increasing light levels leading to a closure of parapodia and protection of kleptoplasts from high light exposure. Furthermore, closure of parapodia occurred at higher irradiance in HLacE. viridis Our results strongly indicate that kleptoplast photoacclimation state modulates the photobehaviour of the solar-powered sea slug E. viridis.
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Affiliation(s)
- Paulo Cartaxana
- Departamento de Biologia & CESAM & ECOMARE, Universidade de Aveiro, 3810-193 Aveiro, Portugal
| | - Luca Morelli
- Departamento de Biologia & CESAM & ECOMARE, Universidade de Aveiro, 3810-193 Aveiro, Portugal.,Dipartimento di Scienze Agrarie, Alimentari e Agro-ambientali, Università di Pisa, 56124 Pisa, Italy
| | - Carla Quintaneiro
- Departamento de Biologia & CESAM & ECOMARE, Universidade de Aveiro, 3810-193 Aveiro, Portugal
| | - Gonçalo Calado
- Departamento de Ciências da Vida, Universidade Lusófona, 1749-024 Lisboa, Portugal
| | - Ricardo Calado
- Departamento de Biologia & CESAM & ECOMARE, Universidade de Aveiro, 3810-193 Aveiro, Portugal
| | - Sónia Cruz
- Departamento de Biologia & CESAM & ECOMARE, Universidade de Aveiro, 3810-193 Aveiro, Portugal
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