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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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2
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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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3
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Phylogeny and evolution of functional chloroplast retention in sacoglossan sea slugs (Gastropoda: Heterobranchia). ORG DIVERS EVOL 2021. [DOI: 10.1007/s13127-021-00532-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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4
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Havurinne V, Handrich M, Antinluoma M, Khorobrykh S, Gould SB, Tyystjärvi E. Genetic autonomy and low singlet oxygen yield support kleptoplast functionality in photosynthetic sea slugs. JOURNAL OF EXPERIMENTAL BOTANY 2021; 72:5553-5568. [PMID: 33989402 PMCID: PMC8318255 DOI: 10.1093/jxb/erab216] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Accepted: 05/12/2021] [Indexed: 05/04/2023]
Abstract
The kleptoplastic sea slug Elysia chlorotica consumes Vaucheria litorea, stealing its plastids, which then photosynthesize inside the animal cells for months. We investigated the properties of V. litorea plastids to understand how they withstand the rigors of photosynthesis in isolation. Transcription of specific genes in laboratory-isolated V. litorea plastids was monitored for 7 days. The involvement of plastid-encoded FtsH, a key plastid maintenance protease, in recovery from photoinhibition in V. litorea was estimated in cycloheximide-treated cells. In vitro comparison of V. litorea and spinach thylakoids was applied to investigate reactive oxygen species formation in V. litorea. In comparison to other tested genes, the transcripts of ftsH and translation elongation factor EF-Tu (tufA) decreased slowly in isolated V. litorea plastids. Higher levels of FtsH were also evident in cycloheximide-treated cells during recovery from photoinhibition. Charge recombination in PSII of V. litorea was found to be fine-tuned to produce only small quantities of singlet oxygen, and the plastids also contained reactive oxygen species-protective compounds. Our results support the view that the genetic characteristics of the plastids are crucial in creating a photosynthetic sea slug. The plastid's autonomous repair machinery is likely enhanced by low singlet oxygen production and elevated expression of FtsH.
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Affiliation(s)
- Vesa Havurinne
- Department of Biotechnology/Molecular Plant Biology, University of Turku, Turku, Finland
| | - Maria Handrich
- Department of Biology, Heinrich-Heine-Universität, Düsseldorf, Germany
| | - Mikko Antinluoma
- Department of Biotechnology/Molecular Plant Biology, University of Turku, Turku, Finland
| | - Sergey Khorobrykh
- Department of Biotechnology/Molecular Plant Biology, University of Turku, Turku, Finland
| | - Sven B Gould
- Department of Biology, Heinrich-Heine-Universität, Düsseldorf, Germany
| | - Esa Tyystjärvi
- Department of Biotechnology/Molecular Plant Biology, University of Turku, Turku, Finland
- Correspondence:
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5
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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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Mehrotra R, A Caballer Gutiérrez M, M Scott C, Arnold S, Monchanin C, Viyakarn V, Chavanich S. An updated inventory of sea slugs from Koh Tao, Thailand, with notes on their ecology and a dramatic biodiversity increase for Thai waters. Zookeys 2021; 1042:73-188. [PMID: 34163291 PMCID: PMC8208966 DOI: 10.3897/zookeys.1042.64474] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Accepted: 05/20/2021] [Indexed: 11/12/2022] Open
Abstract
Improved access to field survey infrastructure throughout South-East Asia has allowed for a greater intensity of biodiversity surveys than ever before. The rocky bottoms and coral reef habitats across the region have been shown to support some of the highest sea slug biodiversity on the planet, with ever increasing records. During the past ten years, intensive SCUBA surveys have been carried out at Koh Tao, in the Gulf of Thailand, which have yielded remarkable findings in sea slug biology and ecology. In this work a brief history of sea slug biodiversity research from Thailand is covered and a complete inventory of sea slugs from Koh Tao, Gulf of Thailand is provided. This inventory is based on surveys from 2012 to 2020, with previously unreported findings since 2016. Habitat specificity and species-specific ecology are reported where available with a focused comparison of coral reef habitats and deeper soft-sediment habitats. The findings contribute 90 new species records for Thai waters (92 for the Gulf of Thailand) and report a remarkable consistency in the proportional diversity found to be exclusive to one habitat type or another. Additionally, taxonomic remarks are provided for species documented from Koh Tao that have not been discussed in past literature from Thailand, and a summary of previous records in the Indo-West Pacific is given.
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Affiliation(s)
- Rahul Mehrotra
- Reef Biology Research Group. Department of Marine Science, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand.,Aow Thai Marine Ecology Center, Koh Mun Nai, Kram, Klaeng District, Rayong 21110, Thailand
| | - Manuel A Caballer Gutiérrez
- American University of Paris, Department of Computer Science Math and Environmental Science, 6 rue du Colonel Combes, 75007 Paris, France.,Muséum national d'Histoire naturelle, 55 rue de Buffon, 75005 Paris, France
| | - Chad M Scott
- Conservation Diver. 7321 Timber Trail Road, Evergreen, Colorado, 80439, USA
| | - Spencer Arnold
- Conservation Diver. 7321 Timber Trail Road, Evergreen, Colorado, 80439, USA
| | - Coline Monchanin
- Aow Thai Marine Ecology Center, Koh Mun Nai, Kram, Klaeng District, Rayong 21110, Thailand.,Research Center on Animal Cognition (CRCA), Center for Integrative Biology (CBI); CNRS, University Paul Sabatier,Toulouse III, France
| | - Voranop Viyakarn
- Reef Biology Research Group. Department of Marine Science, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand
| | - Suchana Chavanich
- Reef Biology Research Group. Department of Marine Science, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand.,Center of Excellence for Marine Biotechnology, Department of Marine Science, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand
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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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8
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Melo Clavijo J, Frankenbach S, Fidalgo C, Serôdio J, Donath A, Preisfeld A, Christa G. Identification of scavenger receptors and thrombospondin-type-1 repeat proteins potentially relevant for plastid recognition in Sacoglossa. Ecol Evol 2020; 10:12348-12363. [PMID: 33209293 PMCID: PMC7663992 DOI: 10.1002/ece3.6865] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2020] [Revised: 08/20/2020] [Accepted: 08/27/2020] [Indexed: 12/24/2022] Open
Abstract
Functional kleptoplasty is a photosymbiotic relationship, in which photosynthetically active chloroplasts serve as an intracellular symbiont for a heterotrophic host. Among Metazoa, functional kleptoplasty is only found in marine sea slugs belonging to the Sacoglossa and recently described in Rhabdocoela worms. Although functional kleptoplasty has been intensively studied in Sacoglossa, the fundamentals of the specific recognition of the chloroplasts and their subsequent incorporation are unknown. The key to ensure the initiation of any symbiosis is the ability to specifically recognize the symbiont and to differentiate a symbiont from a pathogen. For instance, in photosymbiotic cnidarians, several studies have shown that the host innate immune system, in particular scavenger receptors (SRs) and thrombospondin-type-1 repeat (TSR) protein superfamily, is playing a major role in the process of recognizing and differentiating symbionts from pathogens. In the present study, SRs and TSRs of three Sacoglossa sea slugs, Elysia cornigera, Elysia timida, and Elysia chlorotica, were identified by translating available transcriptomes into potential proteins and searching for receptor specific protein and/or transmembrane domains. Both receptors classes are highly diverse in the slugs, and many new domain arrangements for each receptor class were found. The analyses of the gene expression of these three species provided a set of species-specific candidate genes, that is, SR-Bs, SR-Es, C-type lectins, and TSRs, that are potentially relevant for the recognition of kleptoplasts. The results set the base for future experimental studies to understand if and how these candidate receptors are indeed involved in chloroplast recognition.
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Affiliation(s)
- Jenny Melo Clavijo
- Fakultät für Mathematik und Naturwissenschaften, Zoologie und BiologiedidaktikBergische Universität WuppertalWuppertalGermany
| | - Silja Frankenbach
- Department of Biology and CESAM – Center for Environmental and Marine StudiesUniversity of AveiroAveiroPortugal
| | - Cátia Fidalgo
- Department of Biology and CESAM – Center for Environmental and Marine StudiesUniversity of AveiroAveiroPortugal
| | - João Serôdio
- Department of Biology and CESAM – Center for Environmental and Marine StudiesUniversity of AveiroAveiroPortugal
| | - Alexander Donath
- Center for Molecular Biodiversity ResearchZoological Research Museum Alexander KoenigBonnGermany
| | - Angelika Preisfeld
- Fakultät für Mathematik und Naturwissenschaften, Zoologie und BiologiedidaktikBergische Universität WuppertalWuppertalGermany
| | - Gregor Christa
- Fakultät für Mathematik und Naturwissenschaften, Zoologie und BiologiedidaktikBergische Universität WuppertalWuppertalGermany
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9
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Mehrotra R, Gutiérrez MC, Scott CM, Arnold S, Monchanin C, Chavanich S. On the Plakobranchidae (Gastropoda, Sacoglossa) from soft sediment habitats of Koh Tao, Gulf of Thailand, with descriptions of two new species. Zookeys 2020; 969:85-121. [PMID: 33013168 PMCID: PMC7515966 DOI: 10.3897/zookeys.969.52941] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Accepted: 07/24/2020] [Indexed: 11/25/2022] Open
Abstract
Research in recent years have provided rapid advances in biogeographic and taxonomic documentation of sea slugs around the world. However, efforts are lacking in surveying most coastlines and habitats in South-East Asia. Recent studies from the Gulf of Thailand have indicated that a wealth of unexplored sea slug diversity and ecology may be gained from an investigation of soft sediment habitats beyond the reef slopes. Additionally, the waters of Koh Tao have been found to host regionally high levels of sea slug diversity with several species awaiting taxonomic clarification. In this work the initial findings of an expanded survey effort from the waters around Koh Tao are provided, with the identity of two soft sediment-associated sacoglossan species in the family Plakobranchidae being investigated. By integrating morphological and molecular analyses, the species Plakobranchusnoctisstellatussp. nov. and Elysiaaowthaisp. nov. are described and species complexes surrounding Plakobranchusocellatus van Hasselt, 1824 and Elysiajaponica Eliot, 1913 are discussed. The topics of morphological variability and the cryptic species problem are also discussed.
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Affiliation(s)
- Rahul Mehrotra
- Reef Biology Research Group, Department of Marine Science, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand.,Conservation Diver, 7321 Timber Trail Road, Evergreen, Colorado, 80439, USA
| | - Manuel Caballer Gutiérrez
- The American University of Paris, Department of Computer Science Math and Environmental Science, 6 rue du Colonel Combes, 75007 Paris, France.,Muséum national d'Histoire naturelle, 55 rue de Buffon, 75005 Paris, France
| | - Chad M Scott
- Conservation Diver, 7321 Timber Trail Road, Evergreen, Colorado, 80439, USA
| | - Spencer Arnold
- Conservation Diver, 7321 Timber Trail Road, Evergreen, Colorado, 80439, USA
| | - Coline Monchanin
- Conservation Diver, 7321 Timber Trail Road, Evergreen, Colorado, 80439, USA.,Research Center on Animal Cognition (CRCA), Center for Integrative Biology (CBI); CNRS, University Paul Sabatier - Toulouse III, France
| | - Suchana Chavanich
- Reef Biology Research Group, Department of Marine Science, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand.,Center of Excellence for Marine Biotechnology, Department of Marine Science, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand
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10
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Donohoo SA, Wade RM, Sherwood AR. Finding the Sweet Spot: Sub-Ambient Light Increases Fitness and Kleptoplast Survival in the Sea Slug Plakobranchus cf. ianthobaptus Gould, 1852. THE BIOLOGICAL BULLETIN 2020; 238:154-166. [PMID: 32597715 DOI: 10.1086/709371] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Sacoglossans, or "sap-sucking" sea slugs, are primarily algivorous, with many taxa exhibiting kleptoplasty, the feeding and retaining of photosynthetically active chloroplasts from algae. The Plakobranchus species complex exhibits some of the longest kleptoplast retention and survival times under starvation conditions, but the contributions of these kleptoplasts to their survival and overall fitness have been widely debated. In this study we assessed the effects of starvation and light on the fitness of Plakobranchus cf. ianthobaptus and its kleptoplasts by placing starved individuals in eight daily average light treatments, ranging from near dark (2 µmol photon m-2 s-1) to ambient light (470 µmol photon m-2 s-1). Slug weight was used as a metric of fitness, and kleptoplast photosynthetic activity was determined via maximum quantum yield (Fv/Fm) by pulse-amplitude modulated fluorometry as a proxy for kleptoplast health. Plakobranchus individuals in near-dark and high light treatments (>160 µmol photon m-2 s-1) experienced significantly greater weight loss than those in low light (65 µmol photon m-2 s-1) and moderate light treatments (95-135 µmol photon m-2 s-1). Additionally, individuals in high light treatments experienced a rapid decline in kleptoplast photosynthetic activity, while all other treatments experienced minimal decline. This relationship between kleptoplast degradation and weight loss suggests an important link between fitness and kleptoplasty. Given the significant negative effects of ambient conditions, regular refreshment and replenishment of kleptoplasts or physiological or behavioral adjustments are likely employed for the benefits of kleptoplasty to be maintained.
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11
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Middlebrooks ML, Curtis NE, Pierce SK. Algal Sources of Sequestered Chloroplasts in the Sacoglossan Sea Slug Elysia crispata Vary by Location and Ecotype. THE BIOLOGICAL BULLETIN 2019; 236:88-96. [PMID: 30933641 DOI: 10.1086/701732] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Sacoglossan sea slugs feed by suctorially consuming siphonaceous green algae. Most sacoglossan species are feeding specialists, but the Caribbean coral reef-dwelling Elysia crispata is polyphagous and sequesters chloroplasts from multiple algal species into cells lining its digestive diverticulum for use in photosynthesis. We have used sequences of the chloroplast-encoded rbcL gene to compare the chloroplast donor algae in five populations of E. crispata from various Caribbean locations. We found that E. crispata utilizes more algal species than was previously known, including some algae previously not reported as present in the region. In addition, slugs from each location had unique chloroplast arrays with little overlap, except that all locations had slugs feeding on algae within the genus Bryopsis. This variation in diet between locations suggests that the slugs may be exhibiting local adaptation in their dietary choices, and it highlights ecological differences between the Caribbean-wide reef-dwelling ecotypes and the mangrove lagoon ecotypes found in the Florida Keys.
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12
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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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13
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Updating Plakobranchus cf. ianthobapsus (Gastropoda, Sacoglossa) host use: Diverse algal-animal interactions revealed by NGS with implications for invasive species management. Mol Phylogenet Evol 2018; 128:172-181. [PMID: 30031771 DOI: 10.1016/j.ympev.2018.07.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Revised: 07/02/2018] [Accepted: 07/11/2018] [Indexed: 11/21/2022]
Abstract
Sacoglossa, the "sap sucking" sea slugs, are highly specialized herbivores and the only metazoans that exhibit kleptoplasty, the sequestration and retention of chloroplasts from algae. Plakobranchus is one of the most generalistic herbivores within this order, with as many as 12 reported "algal host" (i.e. kleptoplast source) species. However, kleptoplast diversity studies conducted on Plakobranchus to date most likely underestimated the full diversity of kleptoplast sources within the studied populations due to limitations of the molecular techniques employed. Here, we apply a high throughput sequencing technique to assess kleptoplast diversity of Plakobranchus cf. ianthobapsus' from 10 sites across the Main Hawaiian Islands during winter and summer seasons. In so doing, we effectively used P. cf. ianthobapsus as a novel sampling tool to explore diminutive algal communities, including the current distribution of the invasive alga "Avrainvillea amadelpha." Our results show that P. cf. ianthobapsus sequesters chloroplasts from 23 algal species from across the siphonous green algal order Bryopsidales. We identified "Avrainvillea amadelpha" and Codium edule as new host species for P. cf. ianthobapusus, but their rarity among the data suggests they were most likely less preferential as hosts and were possibly utilized due to low abundance or unavailability of more preferable species, and therefore a response to starvation risk. Additionally, the identification of the highly invasive siphonous green alga "A. amadelpha" as a kleptoplast source provides new fine-scale range and distribution data for this problematic species. Overall kleptoplast diversity does not differ among sites, except in a coral-dominated, (i.e. not algal dominated) environment, suggesting that siphonous algal assemblages are common in algal-dominated ecosystems in the Hawaiian Islands. Diversity dissimilarity among seasons was recovered from the majority of sites sampled, supporting the need for seasonal data collection in algal diversity assessments. This case study using metabarcoding of sacoglossan kleptoplasts provides deeper insights into these plant-animal interactions with a better understanding of host use than previous studies using traditional molecular methods and illustrates how algal diversity studies on the scale of plastids can have implications for understanding algal community structure and invasive species dynamics.
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14
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Laetz EMJ, Wägele H. How does temperature affect functional kleptoplasty? Comparing populations of the solar-powered sister-species Elysia timida Risso, 1818 and Elysia cornigera Nuttall, 1989 (Gastropoda: Sacoglossa). Front Zool 2018; 15:17. [PMID: 29760759 PMCID: PMC5937827 DOI: 10.1186/s12983-018-0264-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Accepted: 04/06/2018] [Indexed: 01/03/2023] Open
Abstract
Background Despite widespread interest in solar-powered sea slugs (Sacoglossa: Gastropoda), relatively little is know about how they actually perform functional kleptoplasty. Sister-taxa Elysia timida and E. cornigera provide an ideal model system for investigating this phenomenon, since they feed on the same algal genus and only E. timida is capable of long-term kleptoplasty. Recent research has explored factors regarding functional kleptoplasty in E. timida, including their starvation longevity, digestive activity, autophagal response and photosynthetic efficiency under two different temperature conditions (18 °C and 21 °C). These studies revealed the trends E. timida displays regarding each factor during starvation as well as influences temperature has on some aspects of functional kleptoplasty. This study examines E. cornigera regarding each of these factors in an attempt to elucidate differences between each species that could explain their differing kleptoplastic abilities. Since both species naturally occur in 25 °C seawater (E. timida peak summer temperature, E. cornigera low winter temperature), each species was acclimatized to 25 °C to facilitate comparison and determine if these species exhibit physiological differences to starvation when under the same environmental conditions. Results When comparing the different E. timida temperature treatments, it becomes clear that increased temperatures compromise E. timida’s kleptoplastic abilities. Specimens acclimatized to 25 °C revealed shorter starvation longevities surviving an average 42.4 days compared to the 95.9 day average observed in specimens exposed to 18 °C. Each temperature treatment displayed a significantly different decrease throughout the starvation period in both, the rate of photosynthetic efficiency and in the decreasing functional kleptoplast abundance. Lysosomal abundances are assessed here as indicators of different aspects of metabolic activity, which could be correlated to temperature. E. cornigera, also acclimatized to 25 °C did not display significantly similar patterns as any of the E. timida temperature treatments, having fewer incorporated kleptoplasts, a higher lysosomal response to starvation, a faster decrease in photosynthetic efficiency and a lower starvation longevity. Conclusions These results confirm that each species has different physiological reactions to starvation and kleptoplast retention, even under the same conditions. While temperature affects aspects of functional kleptoplasty, it is likely not responsible for the differences in kleptoplastic abilities seen in these species. Electronic supplementary material The online version of this article (10.1186/s12983-018-0264-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Elise Marie Jerschabek Laetz
- 1Zoological Research Museum Alexander Koenig, 160 Adenauerallee, 53113 Bonn, Germany.,2Institute for Evolutionary Biology and Ecology, University of Bonn, An der Immenburg 1, 53121 Bonn, Germany
| | - Heike Wägele
- 1Zoological Research Museum Alexander Koenig, 160 Adenauerallee, 53113 Bonn, Germany
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15
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Rauch C, Jahns P, Tielens AGM, Gould SB, Martin WF. On Being the Right Size as an Animal with Plastids. FRONTIERS IN PLANT SCIENCE 2017; 8:1402. [PMID: 28861094 PMCID: PMC5562673 DOI: 10.3389/fpls.2017.01402] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Accepted: 07/27/2017] [Indexed: 06/07/2023]
Abstract
Plastids typically reside in plant or algal cells-with one notable exception. There is one group of multicellular animals, sea slugs in the order Sacoglossa, members of which feed on siphonaceous algae. The slugs sequester the ingested plastids in the cytosol of cells in their digestive gland, giving the animals the color of leaves. In a few species of slugs, including members of the genus Elysia, the stolen plastids (kleptoplasts) can remain morphologically intact for weeks and months, surrounded by the animal cytosol, which is separated from the plastid stroma by only the inner and outer plastid membranes. The kleptoplasts of the Sacoglossa are the only case described so far in nature where plastids interface directly with the metazoan cytosol. That makes them interesting in their own right, but it has also led to the idea that it might someday be possible to engineer photosynthetic animals. Is that really possible? And if so, how big would the photosynthetic organs of such animals need to be? Here we provide two sets of calculations: one based on a best case scenario assuming that animals with kleptoplasts can be, on a per cm2 basis, as efficient at CO2 fixation as maize leaves, and one based on 14CO2 fixation rates measured in plastid-bearing sea slugs. We also tabulate an overview of the literature going back to 1970 reporting direct measurements or indirect estimates of the CO2 fixing capabilities of Sacoglossan slugs with plastids.
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Affiliation(s)
- Cessa Rauch
- Molecular Evolution, Heinrich-Heine-UniversityDüsseldorf, Germany
| | - Peter Jahns
- Plant Biochemistry, Heinrich-Heine-UniversityDüsseldorf, Germany
| | - Aloysius G. M. Tielens
- Department of Biochemistry and Cell Biology, Faculty of Veterinary Medicine, Utrecht UniversityUtrecht, Netherlands
- Department of Medical Microbiology and Infectious Diseases, Erasmus University Medical CenterRotterdam, Netherlands
| | - Sven B. Gould
- Molecular Evolution, Heinrich-Heine-UniversityDüsseldorf, Germany
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16
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Wade RM, Sherwood AR. Molecular determination of kleptoplast origins from the sea slug Plakobranchus ocellatus (Sacoglossa, Gastropoda) reveals cryptic bryopsidalean (Chlorophyta) diversity in the Hawaiian Islands. JOURNAL OF PHYCOLOGY 2017; 53:467-475. [PMID: 27992652 DOI: 10.1111/jpy.12503] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Accepted: 09/30/2016] [Indexed: 06/06/2023]
Abstract
The sacoglossan sea slug species complex Plakobranchus ocellatus is a common algivore throughout the tropical Pacific, including the Hawaiian Islands. Plakobranchus ocellatus is kleptoplastic-it sequesters and retains algal chloroplasts-a characteristic that can be exploited to molecularly characterize diminutive bryopsidalean algae that are typically difficult to locate, collect, and identify. Previous DNA barcode analyses of both P. ocellatus and its kleptoplasts have been conducted primarily in the western Pacific and have only minimally sampled the most eastern populations in the Hawaiian Islands. Using two chloroplast markers, rbcL and tufA, kleptoplast samples from an Oahu population of P. ocellatus were amplified and cloned to identify their algal sources. Plakobranchus ocellatus sequester chloroplasts from up to 11 bryopsidalean algal species, all but one being diminutive in thallus size. Notably, eight of the detected algal species were new records to the Hawaiian Islands. A sequestration preference study demonstrated that the O'ahu population of P. ocellatus preferentially sequesters chloroplasts from diminutive, epilithic taxa. Using coxI barcoding of P. ocellatus, we showed the O'ahu population to be part of a clade that includes sequences from the neighboring island Maui, Australia, and the Philippines. The use of P. ocellatus as a novel sampling tool allows the exploration of the green algal community diversity and composition at a fine scale.
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Affiliation(s)
- Rachael M Wade
- Department of Botany, University of Hawaii at Mānoa, 3190 Maile Way, Honolulu, Hawaii, 96822, USA
| | - Alison R Sherwood
- Department of Botany, University of Hawaii at Mānoa, 3190 Maile Way, Honolulu, Hawaii, 96822, USA
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17
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Greve C, Ruiz-Tagle Lui M, Sivalingam S, Ludwig KU, Wägele H, Donath A. The complete mitochondrial genome of the 'solar-powered' sea slug Plakobranchus cf. ocellatus (Heterobranchia: Panpulmonata: Sacoglossa). MITOCHONDRIAL DNA PART B-RESOURCES 2017; 2:130-131. [PMID: 33473741 PMCID: PMC7799614 DOI: 10.1080/23802359.2016.1247667] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
We present the complete mitochondrial genome sequence of Plakobranchus cf. ocellatus (Heterobranchia: Sacoglossa), a so-called ‘solar-powered’ sea slug with long-term retention of chloroplasts. The mitochondrial genome was 14,177 bp in length containing the standard set of 13 protein-coding genes, 2 rRNAs, and 22 tRNAs. The base composition of 27.3% A, 15.6% C, 18.6% G, and 38.5% T showed a strong A + T bias. The genome organization of P. cf. ocellatus is identical to the other sacoglossan mitogenomes sequenced so far, except for Ascobulla fragilis.
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Affiliation(s)
- Carola Greve
- Zoological Research Museum Alexander Koenig (ZFMK), Centre for Molecular Biodiversity Research (zmb), Bonn, Germany
| | - Maximiliano Ruiz-Tagle Lui
- Zoological Research Museum Alexander Koenig (ZFMK), Centre for Molecular Biodiversity Research (zmb), Bonn, Germany
| | - Sugirthan Sivalingam
- Life & Brain Center, Department of Genomics, University of Bonn, Bonn, Germany.,Institute of Human Genetics, University of Bonn, Bonn, Germany
| | - Kerstin U Ludwig
- Life & Brain Center, Department of Genomics, University of Bonn, Bonn, Germany.,Institute of Human Genetics, University of Bonn, Bonn, Germany
| | - Heike Wägele
- Zoological Research Museum Alexander Koenig (ZFMK), Centre for Molecular Biodiversity Research (zmb), Bonn, Germany
| | - Alexander Donath
- Zoological Research Museum Alexander Koenig (ZFMK), Centre for Molecular Biodiversity Research (zmb), Bonn, Germany
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18
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Laetz EMJ, Rühr PT, Bartolomaeus T, Preisfeld A, Wägele H. Examining the retention of functional kleptoplasts and digestive activity in sacoglossan sea slugs. ORG DIVERS EVOL 2016. [DOI: 10.1007/s13127-016-0308-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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19
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Population Dynamics of the Sea Slug Plakobranchus ocellatus (Opisthobranch: Sacoglossa: Elysioidea) on a Subtropical Coral Reef off Okinawa-jima Island, Ryukyu Archipelago, Japan. Zool Stud 2016; 55:e42. [PMID: 31966187 DOI: 10.6620/zs.2016.55-42] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2016] [Accepted: 07/14/2016] [Indexed: 11/18/2022]
Abstract
Daisuke Tanamura and Euichi Hirose (2016) Plakobranchus ocellatus is a sacoglossan sea slug that can retain functional chloroplast from its algal food. This species feed on multiple species of siphonous green algae and can survive several months without food by utilizing retained chloroplasts in its digestive gland (kleptoplasty). While the population dynamics of opisthobranchs are often influenced by the seasonal fluctuation of the abundance of food resources, the fluctuation of food availability would not be a crucial factor to restrict the occurrence of P. ocellatus. We monitored the population density of P. ocellatus for 20 months on a subtropical coral reef where the water temperature fluctuated from 17°C to 32°C, in order to examine whether the population density, distribution pattern of individuals, and size distribution of P. ocellatus are stable or seasonally change. The present results showed that P. ocellatus appeared all year round in the study site, while the population density changed seasonally. The population density decreased in cold (≤ 21°C) and hot (≥ 27°C) periods, and densities in the months of intermediate temperature range (< 21°C, > 25°C) were significantly higher than the densities in other months (Student's t-test, P < 0.0001). Accordingly, population density is probably influenced by water temperature. Morisita's Iδ indicated that the sea slugs were distributed in random patterns (13 months) or clumped patterns (7 months). Our field observations indicated that the sea slugs do not feed in daytime, and probably feed at night. Whereas P. ocellatus individuals of less than 10 mm were rarely recorded in the monitoring area, a decrease of the average body length and increase in population density in April - May suggest active recruitment of small individuals in this period.
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20
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Meyers-Muñoz MA, van der Velde G, van der Meij SET, Stoffels BEMW, van Alen T, Tuti Y, Hoeksema BW. The phylogenetic position of a new species of Plakobranchus from West Papua, Indonesia (Mollusca, Opisthobranchia, Sacoglossa). Zookeys 2016:73-98. [PMID: 27408559 PMCID: PMC4926700 DOI: 10.3897/zookeys.594.5954] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Accepted: 05/09/2016] [Indexed: 11/12/2022] Open
Abstract
Plakobranchus papua Meyers-Muñoz & van der Velde, sp. n. from West Papua (Papua Barat province, Indonesia), is described based on its external morphology, colour pattern, internal anatomy, radula and reproductive system. In a molecular phylogenetic study specimens of this new species were compared with those of ten candidate taxa under the name Plakobranchus ocellatus van Hasselt, 1824. DNA analyses of COI mtDNA showed a clear distinction between Plakobranchus papua sp. n. and "Plakobranchus ocellatus". Plakobranchus papua, sp. n. also differed from all taxa that have been synonymised with Plakobranchus ocellatus. The genus is in dire need of taxonomic revision, preferably based on an integrative analysis involving morphology and DNA of all known Plakobranchus varieties.
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Affiliation(s)
- María Angélica Meyers-Muñoz
- Radboud University Nijmegen, Institute for Water and Wetland Research, Department of Animal Ecology and Physiology, P.O. Box 9010, 6500 GL Nijmegen, The Netherlands
| | - Gerard van der Velde
- Radboud University Nijmegen, Institute for Water and Wetland Research, Department of Animal Ecology and Physiology, P.O. Box 9010, 6500 GL Nijmegen, The Netherlands; Naturalis Biodiversity Center, Darwinweg 2, 2333 CR Leiden, The Netherlands
| | - Sancia E T van der Meij
- Naturalis Biodiversity Center, Darwinweg 2, 2333 CR Leiden, The Netherlands; Oxford University Museum of Natural History, Parks Road, Oxford OX1 3PW, United Kingdom
| | - Bart E M W Stoffels
- Radboud University Nijmegen, Institute for Water and Wetland Research, Department of Animal Ecology and Physiology, P.O. Box 9010, 6500 GL Nijmegen, The Netherlands
| | - Theo van Alen
- Radboud University Nijmegen, Institute for Water and Wetland Research, Department of Microbiology, P.O. Box 9010, 6500 GL Nijmegen, The Netherlands
| | - Yosephine Tuti
- Research Centre for Oceanography (RCO), Indonesian Institute of Sciences (LIPI), Jl. Pasir Putih I, Ancol Timur, Jakarta 14430, Indonesia
| | - Bert W Hoeksema
- Naturalis Biodiversity Center, Darwinweg 2, 2333 CR Leiden, The Netherlands
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21
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Leal MC, Ferrier-Pagès C. Molecular trophic markers in marine food webs and their potential use for coral ecology. Mar Genomics 2016; 29:1-7. [PMID: 26896098 DOI: 10.1016/j.margen.2016.02.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Revised: 02/01/2016] [Accepted: 02/05/2016] [Indexed: 12/25/2022]
Abstract
Notable advances in ecological genomics have been driven by high-throughput sequencing technology and taxonomically broad sequence repositories that allow us to accurately assess species interactions with great taxonomic resolution. The use of DNA as a marker for ingested food is particularly relevant to address predator-prey interactions and disentangle complex marine food webs. DNA-based methods benefit from reductionist molecular approaches to address ecosystem scale processes, such as community structure and energy flow across trophic levels, among others. Here we review how molecular trophic markers have been used to better understand trophic interactions in the marine environment and their advantages and limitations. We focus on animal groups where research has been focused, such as marine mammals, seabirds, fishes, pelagic invertebrates and benthic invertebrates, and use case studies to illustrate how DNA-based methods unraveled food-web interactions. The potential of molecular trophic markers for disentangling the complex trophic ecology of corals is also discussed.
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Affiliation(s)
- Miguel Costa Leal
- Dept. of Fish Ecology Evolution, Eawag: Swiss Federal Institute of Aquatic Science and Technology, Center for Ecology, Evolution and Biogeochemistry; Seestrasse 79, 6047 Kastanienbaum, Switzerland.
| | - Christine Ferrier-Pagès
- Centre Scientifique du Monaco, Ecophysiology team, 8 Quai Antoine ler, MC-98000 Monaco, Monaco.
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22
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Martin R, Walther P, Tomaschko KH. Variable retention of kleptoplast membranes in cells of sacoglossan sea slugs: plastids with extended, shortened and non-retained durations. ZOOMORPHOLOGY 2015. [DOI: 10.1007/s00435-015-0278-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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23
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Baumgartner FA, Pavia H, Toth GB. Acquired phototrophy through retention of functional chloroplasts increases growth efficiency of the sea slug Elysia viridis. PLoS One 2015; 10:e0120874. [PMID: 25830355 PMCID: PMC4382131 DOI: 10.1371/journal.pone.0120874] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Accepted: 01/27/2015] [Indexed: 11/29/2022] Open
Abstract
Photosynthesis is a fundamental process sustaining heterotrophic organisms at all trophic levels. Some mixotrophs can retain functional chloroplasts from food (kleptoplasty), and it is hypothesized that carbon acquired through kleptoplasty may enhance trophic energy transfer through increased host growth efficiency. Sacoglossan sea slugs are the only known metazoans capable of kleptoplasty, but the relative fitness contributions of heterotrophy through grazing, and phototrophy via kleptoplasts, are not well understood. Fitness benefits (i.e. increased survival or growth) of kleptoplasty in sacoglossans are commonly studied in ecologically unrealistic conditions under extended periods of complete darkness and/or starvation. We compared the growth efficiency of the sacoglossan Elysia viridis with access to algal diets providing kleptoplasts of differing functionality under ecologically relevant light conditions. Individuals fed Codium fragile, which provide highly functional kleptoplasts, nearly doubled their growth efficiency under high compared to low light. In contrast, individuals fed Cladophora rupestris, which provided kleptoplasts of limited functionality, showed no difference in growth efficiency between light treatments. Slugs feeding on Codium, but not on Cladophora, showed higher relative electron transport rates (rETR) in high compared to low light. Furthermore, there were no differences in the consumption rates of the slugs between different light treatments, and only small differences in nutritional traits of algal diets, indicating that the increased growth efficiency of E. viridis feeding on Codium was due to retention of functional kleptoplasts. Our results show that functional kleptoplasts from Codium can provide sacoglossan sea slugs with fitness advantages through photosynthesis.
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Affiliation(s)
- Finn A. Baumgartner
- University of Gothenburg, Department of Biological and Environmental Sciences-Tjärnö, Strömstad, Sweden
| | - Henrik Pavia
- University of Gothenburg, Department of Biological and Environmental Sciences-Tjärnö, Strömstad, Sweden
| | - Gunilla B. Toth
- University of Gothenburg, Department of Biological and Environmental Sciences-Tjärnö, Strömstad, Sweden
- * E-mail:
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24
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Cruz S, Cartaxana P, Newcomer R, Dionísio G, Calado R, Serôdio J, Pelletreau KN, Rumpho ME. Photoprotection in sequestered plastids of sea slugs and respective algal sources. Sci Rep 2015; 5:7904. [PMID: 25601025 PMCID: PMC4298725 DOI: 10.1038/srep07904] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2014] [Accepted: 12/18/2014] [Indexed: 01/07/2023] Open
Abstract
Some sea slugs are capable of retaining functional sequestered chloroplasts (kleptoplasts) for variable periods of time. The mechanisms supporting the maintenance of these organelles in animal hosts are still largely unknown. Non-photochemical quenching (NPQ) and the occurrence of a xanthophyll cycle were investigated in the sea slugs Elysia viridis and E. chlorotica using chlorophyll fluorescence measurements and pigment analysis. The photoprotective capacity of kleptoplasts was compared to that observed in their respective algal source, Codium tomentosum and Vaucheria litorea. A functional xanthophyll cycle and a rapidly reversible NPQ component were found in V. litorea and E. chlorotica but not in C. tomentosum and E. viridis. To our knowledge, this is the first report of the absence of a functional xanthophyll cycle in a green macroalgae. The absence of a functional xanthophyll cycle in C. tomentosum could contribute to the premature loss of photosynthetic activity and relatively short-term retention of kleptoplasts in E. viridis. On the contrary, E. chlorotica displays one of the longest functional examples of kleptoplasty known so far. We speculate that different efficiencies of photoprotection and repair mechanisms of algal food sources play a role in the longevity of photosynthetic activity in kleptoplasts retained by sea slugs.
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Affiliation(s)
- Sónia Cruz
- Departamento de Biologia &CESAM - Centro de Estudos do Ambiente e do Mar, Universidade de Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal
| | - Paulo Cartaxana
- MARE - Centro de Ciências do Mar e do Ambiente, Faculdade de Ciências da Universidade de Lisboa, 1749-016 Lisboa, Portugal
| | - Rebecca Newcomer
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT, USA
| | - Gisela Dionísio
- 1] Departamento de Biologia &CESAM - Centro de Estudos do Ambiente e do Mar, Universidade de Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal [2] MARE - Centro de Ciências do Mar e do Ambiente, Faculdade de Ciências da Universidade de Lisboa, 1749-016 Lisboa, Portugal
| | - Ricardo Calado
- Departamento de Biologia &CESAM - Centro de Estudos do Ambiente e do Mar, Universidade de Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal
| | - João Serôdio
- Departamento de Biologia &CESAM - Centro de Estudos do Ambiente e do Mar, Universidade de Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal
| | - Karen N Pelletreau
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT, USA
| | - Mary E Rumpho
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT, USA
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Christa G, Händeler K, Kück P, Vleugels M, Franken J, Karmeinski D, Wägele H. Phylogenetic evidence for multiple independent origins of functional kleptoplasty in Sacoglossa (Heterobranchia, Gastropoda). ORG DIVERS EVOL 2014. [DOI: 10.1007/s13127-014-0189-z] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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26
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de Vries J, Habicht J, Woehle C, Huang C, Christa G, Wägele H, Nickelsen J, Martin WF, Gould SB. Is ftsH the key to plastid longevity in sacoglossan slugs? Genome Biol Evol 2014; 5:2540-8. [PMID: 24336424 PMCID: PMC3879987 DOI: 10.1093/gbe/evt205] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Plastids sequestered by sacoglossan sea slugs have long been a puzzle. Some sacoglossans feed on siphonaceous algae and can retain the plastids in the cytosol of their digestive gland cells. There, the stolen plastids (kleptoplasts) can remain photosynthetically active in some cases for months. Kleptoplast longevity itself challenges current paradigms concerning photosystem turnover, because kleptoplast photosystems remain active in the absence of nuclear algal genes. In higher plants, nuclear genes are essential for plastid maintenance, in particular, for the constant repair of the D1 protein of photosystem II. Lateral gene transfer was long suspected to underpin slug kleptoplast longevity, but recent transcriptomic and genomic analyses show that no algal nuclear genes are expressed from the slug nucleus. Kleptoplast genomes themselves, however, appear expressed in the sequestered state. Here we present sequence data for the chloroplast genome of Acetabularia acetabulum, the food source of the sacoglossan Elysia timida, which can maintain Acetabularia kleptoplasts in an active state for months. The data reveal what might be the key to sacoglossan kleptoplast longevity: plastids that remain photosynthetically active within slugs for periods of months share the property of encoding ftsH, a D1 quality control protease that is essential for photosystem II repair. In land plants, ftsH is always nuclear encoded, it was transferred to the nucleus from the plastid genome when Charophyta and Embryophyta split. A replenishable supply of ftsH could, in principle, rescue kleptoplasts from D1 photodamage, thereby influencing plastid longevity in sacoglossan slugs.
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Affiliation(s)
- Jan de Vries
- Institute of Molecular Evolution, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
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27
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Abundance and size distribution of the sacoglossan Elysia viridis on co-occurring algal hosts on the Swedish west coast. PLoS One 2014; 9:e92472. [PMID: 24647524 PMCID: PMC3960251 DOI: 10.1371/journal.pone.0092472] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2013] [Accepted: 02/22/2014] [Indexed: 11/25/2022] Open
Abstract
Sacoglossans are specialized marine herbivores that tend to have a close evolutionary relationship with their macroalgal hosts, but the widely distributed species Elysia viridis can associate with several algal species. However, most previous investigations on the field abundance and size distribution of E. viridis have focussed on Codium spp. in the British Isles, and algae from this genus are considered superior hosts for E. viridis. In the present study, we investigated the abundance and size distribution of E. viridis on 6 potential host algae with differing morphologies (the septate species Cladophora sericea, Cladophora rupestris, Chaetomorpha melagonium, and Ceramium virgatum, as well as the siphonaceous species Codium fragile and Bryopsis sp.) at 2 sites on the Swedish west coast over the course of a year. In spring, slugs were almost absent from all algal hosts. In summer and autumn, E. viridis consistently occurred on several of the algal species at both sites. The highest number of small E. viridis were found on C. sericea, intermediate numbers of significantly larger E. viridis were found on C. rupestris, while fewer, intermediate sized animals were found on C. fragile. Throughout the study period, only a few E. viridis individuals were found on C. melagonium, Bryopsis sp., and C. virgatum. Our results indicate that E. viridis is an annual species in Sweden, capable of exploiting co-occurring congeneric and intergeneric algal hosts with differing morphologies. These results corroborate previous findings that E. viridis can exploit several different algal species, but does not indicate that C. fragile is a superior host.
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28
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Identification of sequestered chloroplasts in photosynthetic and non-photosynthetic sacoglossan sea slugs (Mollusca, Gastropoda). Front Zool 2014; 11:15. [PMID: 24555467 PMCID: PMC3941943 DOI: 10.1186/1742-9994-11-15] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2013] [Accepted: 02/06/2014] [Indexed: 11/24/2022] Open
Abstract
Background Sacoglossan sea slugs are well known for their unique ability among metazoans to incorporate functional chloroplasts (kleptoplasty) in digestive glandular cells, enabling the slugs to use these as energy source when starved for weeks and months. However, members assigned to the shelled Oxynoacea and Limapontioidea (often with dorsal processes) are in general not able to keep the incorporated chloroplasts functional. Since obviously no algal genes are present within three (out of six known) species with chloroplast retention of several months, other factors enabling functional kleptoplasty have to be considered. Certainly, the origin of the chloroplasts is important, however, food source of most of the about 300 described species is not known so far. Therefore, a deduction of specific algal food source as a factor to perform functional kleptoplasty was still missing. Results We investigated the food sources of 26 sacoglossan species, freshly collected from the field, by applying the chloroplast marker genes tufA and rbcL and compared our results with literature data of species known for their retention capability. For the majority of the investigated species, especially for the genus Thuridilla, we were able to identify food sources for the first time. Furthermore, published data based on feeding observations were confirmed and enlarged by the molecular methods. We also found that certain chloroplasts are most likely essential for establishing functional kleptoplasty. Conclusions Applying DNA-Barcoding appeared to be very efficient and allowed a detailed insight into sacoglossan food sources. We favor rbcL for future analyses, but tufA might be used additionally in ambiguous cases. We narrowed down the algal species that seem to be essential for long-term-functional photosynthesis: Halimeda, Caulerpa, Penicillus, Avrainvillea, Acetabularia and Vaucheria. None of these were found in Thuridilla, the only plakobranchoidean genus without long-term retention forms. The chloroplast type, however, does not solely determine functional kleptoplasty; members of no-retention genera, such as Cylindrobulla or Volvatella, feed on the same algae as e.g., the long-term-retention forms Plakobranchus ocellatus or Elysia crispata, respectively. Evolutionary benefits of functional kleptoplasty are still questionable, since a polyphagous life style would render slugs more independent of specific food sources and their abundance.
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Christa G, de Vries J, Jahns P, Gould SB. Switching off photosynthesis: The dark side of sacoglossan slugs. Commun Integr Biol 2014; 7:e28029. [PMID: 24778762 PMCID: PMC3995730 DOI: 10.4161/cib.28029] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Revised: 01/28/2014] [Accepted: 01/28/2014] [Indexed: 11/19/2022] Open
Abstract
Sometimes the elementary experiment can lead to the most surprising result. This was recently the case when we had to learn that so-called “photosynthetic slugs“ survive just fine in the dark and with chemically inhibited photosynthesis. Sacoglossan sea slugs feed on large siphonaceous, often single-celled algae by ingesting their cytosolic content including the organelles. A few species of the sacoglossan clade fascinate researcher from many disciplines, as they can survive starvation periods of many months through the plastids they sequestered, but not immediately digested – a process known as kleptoplasty. Ever since the term “leaves that crawl“ was coined in the 1970s, the course was set in regard to how the subject was studied, but the topics of how slugs survive starvation and what for instance mediates kleptoplast longevity have often been conflated. It was generally assumed that slugs become photoautotrophic upon plastid sequestration, but most recent results challenge that view and the predominant role of the kleptoplasts in sacoglossan sea slugs.
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Affiliation(s)
- Gregor Christa
- Zoologisches Forschungsmuseum Alexander Koenig; Centre for Molecular Biodiversity Research (ZMB); Bonn, Germany ; Institute for Molecular Evolution; Heinrich-Heine-University; Düsseldorf, Germany
| | - Jan de Vries
- Institute for Molecular Evolution; Heinrich-Heine-University; Düsseldorf, Germany
| | - Peter Jahns
- Plant Biochemistry and Stress Physiology; Heinrich-Heine-University; Düsseldorf, Germany
| | - Sven B Gould
- Institute for Molecular Evolution; Heinrich-Heine-University; Düsseldorf, Germany
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Schmitt V, Händeler K, Gunkel S, Escande ML, Menzel D, Gould SB, Martin WF, Wägele H. Chloroplast incorporation and long-term photosynthetic performance through the life cycle in laboratory cultures of Elysia timida (Sacoglossa, Heterobranchia). Front Zool 2014; 11:5. [PMID: 24428892 PMCID: PMC3898781 DOI: 10.1186/1742-9994-11-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2013] [Accepted: 01/10/2014] [Indexed: 11/30/2022] Open
Abstract
Introduction The Mediterranean sacoglossan Elysia timida is one of the few sea slug species with the ability to sequester chloroplasts from its food algae and to subsequently store them in a functional state in the digestive gland cells for more than a month, during which time the plastids retain high photosynthetic activity (= long-term retention). Adult E. timida have been described to feed on the unicellular alga Acetabularia acetabulum in their natural environment. The suitability of E. timida as a laboratory model culture system including its food source was studied. Results In contrast to the literature reporting that juvenile E. timida feed on Cladophora dalmatica first, and later on switch to the adult diet A. acetabulum, the juveniles in this study fed directly on A. acetabulum (young, non-calcified stalks); they did not feed on the various Cladophora spp. (collected from the sea or laboratory culture) offered. This could possibly hint to cryptic speciation with no clear morphological differences, but incipient ecological differentiation. Transmission electron microscopy of chloroplasts from A. acetabulum after initial intake by juvenile E. timida showed different states of degradation — in conglomerations or singularly — and fragments of phagosome membranes, but differed from kleptoplast images of C. dalmatica in juvenile E. timida from the literature. Based on the finding that the whole life cycle of E. timida can be completed with A. acetabulum as the sole food source, a laboratory culture system was established. An experiment with PAM-fluorometry showed that cultured E. timida are also able to store chloroplasts in long-term retention from Acetabularia peniculus, which stems from the Indo-Pacific and is not abundant in the natural environment of E. timida. Variations between three experiment groups indicated potential influences of temperature on photosynthetic capacities. Conclusions E. timida is a viable laboratory model system to study photosynthesis in incorporated chloroplasts (kleptoplasts). Capacities of chloroplast incorporation in E. timida were investigated in a closed laboratory culture system with two different chloroplast donors and over extended time periods about threefold longer than previously reported.
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Affiliation(s)
| | | | | | | | | | | | | | - Heike Wägele
- Zoologisches Forschungsmuseum Alexander Koenig, Adenauerallee 160, 53113 Bonn, Germany.
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Christa G, Zimorski V, Woehle C, Tielens AGM, Wägele H, Martin WF, Gould SB. Plastid-bearing sea slugs fix CO2 in the light but do not require photosynthesis to survive. Proc Biol Sci 2013; 281:20132493. [PMID: 24258718 DOI: 10.1098/rspb.2013.2493] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Several sacoglossan sea slugs (Plakobranchoidea) feed upon plastids of large unicellular algae. Four species--called long-term retention (LtR) species--are known to sequester ingested plastids within specialized cells of the digestive gland. There, the stolen plastids (kleptoplasts) remain photosynthetically active for several months, during which time LtR species can survive without additional food uptake. Kleptoplast longevity has long been puzzling, because the slugs do not sequester algal nuclei that could support photosystem maintenance. It is widely assumed that the slugs survive starvation by means of kleptoplast photosynthesis, yet direct evidence to support that view is lacking. We show that two LtR plakobranchids, Elysia timida and Plakobranchus ocellatus, incorporate (14)CO2 into acid-stable products 60- and 64-fold more rapidly in the light than in the dark, respectively. Despite this light-dependent CO2 fixation ability, light is, surprisingly, not essential for the slugs to survive starvation. LtR animals survived several months of starvation (i) in complete darkness and (ii) in the light in the presence of the photosynthesis inhibitor monolinuron, all while not losing weight faster than the control animals. Contrary to current views, sacoglossan kleptoplasts seem to be slowly digested food reserves, not a source of solar power.
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Affiliation(s)
- Gregor Christa
- Zoologisches Forschungsmuseum Alexander Koenig, Centre for Molecular Biodiversity Research (zmb), , Bonn 53113, Germany, Institute for Molecular Evolution, Heinrich Heine-University Düsseldorf, , Düsseldorf 40225, Germany, Department of Biochemistry and Cell Biology, Faculty of Veterinary Medicine, Utrecht University, , Utrecht, The Netherlands, Department of Medical Microbiology and Infectious Diseases, Erasmus University Medical Center, , Rotterdam, The Netherlands
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Cruz S, Calado R, Serôdio J, Cartaxana P. Crawling leaves: photosynthesis in sacoglossan sea slugs. JOURNAL OF EXPERIMENTAL BOTANY 2013; 64:3999-4009. [PMID: 23846876 DOI: 10.1093/jxb/ert197] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Some species of sacoglossan sea slugs can maintain functional chloroplasts from specific algal food sources in the cells of their digestive diverticula. These 'stolen' chloroplasts (kleptoplasts) can survive in the absence of the plant cell and continue to photosynthesize, in some cases for as long as one year. Within the Metazoa, this phenomenon (kleptoplasty) seems to have only evolved among sacoglossan sea slugs. Known for over a century, the mechanisms of interaction between the foreign organelle and its host animal cell are just now starting to be unravelled. In the study of sacoglossan sea slugs as photosynthetic systems, it is important to understand their relationship with light. This work reviews the state of knowledge on autotrophy as a nutritional source for sacoglossans and the strategies they have developed to avoid excessive light, with emphasis to the behavioural and physiological mechanisms suggested to be involved in the photoprotection of kleptoplasts. A special focus is given to the advantages and drawbacks of using pulse amplitude modulated fluorometry in photobiological studies addressing sacoglossan sea slugs. Finally, the classification of photosynthetic sacoglossan sea slugs according to their ability to retain functional kleptoplasts and the importance of laboratory culturing of these organisms are briefly discussed.
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Affiliation(s)
- Sónia Cruz
- Departamento de Biologia and CESAM, Universidade de Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal
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Krug PJ, Vendetti JE, Rodriguez AK, Retana JN, Hirano YM, Trowbridge CD. Integrative species delimitation in photosynthetic sea slugs reveals twenty candidate species in three nominal taxa studied for drug discovery, plastid symbiosis or biological control. Mol Phylogenet Evol 2013; 69:1101-19. [PMID: 23876292 DOI: 10.1016/j.ympev.2013.07.009] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2012] [Revised: 07/10/2013] [Accepted: 07/11/2013] [Indexed: 11/30/2022]
Abstract
DNA barcoding can highlight taxa in which conventional taxonomy underestimates species richness, identifying mitochondrial lineages that may correspond to unrecognized species. However, key assumptions of barcoding remain untested for many groups of soft-bodied marine invertebrates with poorly resolved taxonomy. Here, we applied an integrative approach for species delimitation to herbivorous sea slugs in clade Sacoglossa, in which unrecognized diversity may complicate studies of drug discovery, plastid endosymbiosis, and biological control. Using the mitochondrial barcoding COI gene and the nuclear histone 3 gene, we tested the hypothesis that three widely distributed "species" each comprised a complex of independently evolving lineages. Morphological and reproductive characters were then used to evaluate whether each lineage was distinguishable as a candidate species. The "circumtropical" Elysia ornata comprised a Caribbean species and four Indo-Pacific candidate species that are potential sources of kahalalides, anti-cancer compounds. The "monotypic" and highly photosynthetic Plakobranchus ocellatus, used for over 60 years to study chloroplast symbiosis, comprised 10 candidate species. Finally, six candidate species were distinguished in the Elysia tomentosa complex, including potential biological control agents for invasive green algae (Caulerpa spp.). We show that a candidate species approach developed for vertebrates effectively categorizes cryptic diversity in marine invertebrates, and that integrating threshold COI distances with non-molecular character data can delimit species even when common assumptions of DNA barcoding are violated.
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Affiliation(s)
- Patrick J Krug
- Department of Biological Sciences, California State University, Los Angeles, CA 90032-8201, USA.
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