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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: 19] [Impact Index Per Article: 6.3] [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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2
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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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3
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Rycroft T, Hamilton K, Haas CN, Linkov I. A quantitative risk assessment method for synthetic biology products in the environment. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 696:133940. [PMID: 31446290 DOI: 10.1016/j.scitotenv.2019.133940] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Revised: 08/13/2019] [Accepted: 08/14/2019] [Indexed: 06/10/2023]
Abstract
The need to prevent possible adverse environmental health impacts resulting from synthetic biology (SynBio) products is widely acknowledged in both the SynBio risk literature and the global regulatory community. To-date, however, discussions of potential risks of SynBio products have been largely speculative, and the limited attempts to characterize the risks of SynBio products have been non-uniform and entirely qualitative. As the SynBio discipline continues to accelerate and bring forth novel, highly-engineered life forms, a standardized risk assessment framework will become critical for ensuring that the environmental risks of these products are characterized in a consistent, reliable, and objective manner that incorporates all SynBio-unique risk factors. In their current forms, established risk assessment frameworks - including those that address traditional genetically modified organisms - fall short of the features required of this standard framework. To address this gap, we propose the Quantitative Risk Assessment Method for Synthetic Biology Products (QRA-SynBio) - an incremental build on established risk assessment methodologies that supplements traditional paradigms with the SynBio risk factors that are currently absent, and necessitates quantitative analysis for more transparent and objective risk characterizations. We demonstrate through a hypothetical case study that the proposed framework facilitates defensible quantification of the environmental risks of SynBio products in both foreseeable and hypothetical use scenarios. Additionally, we show how the quantitative nature of the proposed method can promote increased experimental investigation into the true likelihood of hazard and exposure parameters and highlight the most sensitive parameters where uncertainty should be reduced, ultimately leading to more targeted SynBio risk research and yielding more precise characterizations of risk.
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Affiliation(s)
- Taylor Rycroft
- Environmental Laboratory, U.S. Army Engineer Research and Development Center, Concord, MA, USA.
| | - Kerry Hamilton
- School for Sustainable Engineering and the Built Environment & The Biodesign Institute Center for Environmental Health Engineering, Arizona State University, Tempe, AZ, USA
| | - Charles N Haas
- Department of Civil, Architectural and Environmental Engineering, Drexel University, Philadelphia, PA, USA
| | - Igor Linkov
- Environmental Laboratory, U.S. Army Engineer Research and Development Center, Concord, MA, USA
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4
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Van Steenkiste NWL, Stephenson I, Herranz M, Husnik F, Keeling PJ, Leander BS. A new case of kleptoplasty in animals: Marine flatworms steal functional plastids from diatoms. SCIENCE ADVANCES 2019; 5:eaaw4337. [PMID: 31328166 PMCID: PMC6636991 DOI: 10.1126/sciadv.aaw4337] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Accepted: 06/11/2019] [Indexed: 05/28/2023]
Abstract
To date, sea slugs have been considered the only animals known to sequester functional algal plastids into their own cells, via a process called "kleptoplasty." We report here, however, that endosymbionts in the marine flatworms Baicalellia solaris and Pogaina paranygulgus are isolated plastids stolen from diatoms. Ultrastructural data show that kleptoplasts are located within flatworm cells, while algal nuclei and other organelles are absent. Transcriptomic analysis and rbcL amplicons confirm the absence of algal nuclear mRNA and reveal that the plastids originate from different species of diatoms. Laboratory experiments demonstrated photosynthetic activity and short-term retention of kleptoplasts in starved worms. This lineage of flatworms represents the first known case of functional kleptoplasty involving diatoms and only the second known case of kleptoplasty across the entire tree of animals.
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Affiliation(s)
- Niels W. L. Van Steenkiste
- Department of Zoology, University of British Columbia, 4200-6270 University Blvd., Vancouver, BC V6T 1Z4, Canada
- Department of Botany, University of British Columbia, 3200-6270 University Blvd., Vancouver, BC V6T 1Z4, Canada
| | - India Stephenson
- Department of Zoology, University of British Columbia, 4200-6270 University Blvd., Vancouver, BC V6T 1Z4, Canada
| | - María Herranz
- Department of Zoology, University of British Columbia, 4200-6270 University Blvd., Vancouver, BC V6T 1Z4, Canada
- Department of Botany, University of British Columbia, 3200-6270 University Blvd., Vancouver, BC V6T 1Z4, Canada
| | - Filip Husnik
- Department of Botany, University of British Columbia, 3200-6270 University Blvd., Vancouver, BC V6T 1Z4, Canada
| | - Patrick J. Keeling
- Department of Botany, University of British Columbia, 3200-6270 University Blvd., Vancouver, BC V6T 1Z4, Canada
| | - Brian S. Leander
- Department of Zoology, University of British Columbia, 4200-6270 University Blvd., Vancouver, BC V6T 1Z4, Canada
- Department of Botany, University of British Columbia, 3200-6270 University Blvd., Vancouver, BC V6T 1Z4, Canada
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5
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Cai H, Li Q, Fang X, Li J, Curtis NE, Altenburger A, Shibata T, Feng M, Maeda T, Schwartz JA, Shigenobu S, Lundholm N, Nishiyama T, Yang H, Hasebe M, Li S, Pierce SK, Wang J. A draft genome assembly of the solar-powered sea slug Elysia chlorotica. Sci Data 2019; 6:190022. [PMID: 30778257 PMCID: PMC6380222 DOI: 10.1038/sdata.2019.22] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Accepted: 01/10/2019] [Indexed: 11/09/2022] Open
Abstract
Elysia chlorotica, a sacoglossan sea slug found off the East Coast of the United States, is well-known for its ability to sequester chloroplasts from its algal prey and survive by photosynthesis for up to 12 months in the absence of food supply. Here we present a draft genome assembly of E. chlorotica that was generated using a hybrid assembly strategy with Illumina short reads and PacBio long reads. The genome assembly comprised 9,989 scaffolds, with a total length of 557 Mb and a scaffold N50 of 442 kb. BUSCO assessment indicated that 93.3% of the expected metazoan genes were completely present in the genome assembly. Annotation of the E. chlorotica genome assembly identified 176 Mb (32.6%) of repetitive sequences and a total of 24,980 protein-coding genes. We anticipate that the annotated draft genome assembly of the E. chlorotica sea slug will promote the investigation of sacoglossan genetics, evolution, and particularly, the genetic signatures accounting for the long-term functioning of algal chloroplasts in an animal.
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Affiliation(s)
- Huimin Cai
- Department of Computer Science, City University of Hong Kong, Hong Kong 999077, China
| | - Qiye Li
- BGI-Shenzhen, Shenzhen 518083, China.,State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223, China.,Center for Excellence in Animal Evolution and Genetics, Chinese Academy of Sciences, 650223, Kunming, China
| | | | - Ji Li
- BGI-Shenzhen, Shenzhen 518083, China.,State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223, China.,Center for Excellence in Animal Evolution and Genetics, Chinese Academy of Sciences, 650223, Kunming, China
| | - Nicholas E Curtis
- Department of Biology, Ave Maria University, Ave Maria, Florida 34142, USA
| | - Andreas Altenburger
- Section for Evolutionary Genomics, Natural History Museum of Denmark, University of Copenhagen, Copenhagen 1350, Denmark
| | - Tomoko Shibata
- National Institute for Basic Biology, Okazaki 444-8585, Japan
| | - Mingji Feng
- BGI Genomics, BGI-Shenzhen, Shenzhen 518083, China
| | - Taro Maeda
- National Institute for Basic Biology, Okazaki 444-8585, Japan
| | - Julie A Schwartz
- Department of Integrative Biology, University of South Florida, Tampa, Florida 33620, USA
| | - Shuji Shigenobu
- National Institute for Basic Biology, Okazaki 444-8585, Japan.,Graduate University for Advanced Studies (SOKENDAI), Okazaki 444-8585, Japan
| | - Nina Lundholm
- Section for Evolutionary Genomics, Natural History Museum of Denmark, University of Copenhagen, Copenhagen 1350, Denmark
| | - Tomoaki Nishiyama
- Advanced Science Research Center, Kanazawa University, Kanazawa 920-0934, Japan
| | - Huanming Yang
- BGI-Shenzhen, Shenzhen 518083, China.,James D. Watson Institute of Genome Sciences, Hangzhou 310058, China
| | - Mitsuyasu Hasebe
- National Institute for Basic Biology, Okazaki 444-8585, Japan.,Graduate University for Advanced Studies (SOKENDAI), Okazaki 444-8585, Japan
| | - Shuaicheng Li
- Department of Computer Science, City University of Hong Kong, Hong Kong 999077, China
| | - Sidney K Pierce
- Department of Integrative Biology, University of South Florida, Tampa, Florida 33620, USA.,Department of Biology, University of Maryland, College Park, Maryland 20742, USA
| | - Jian Wang
- BGI-Shenzhen, Shenzhen 518083, China.,James D. Watson Institute of Genome Sciences, Hangzhou 310058, China
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6
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Chaijarasphong T, Savage DF. Sequestered: Design and Construction of Synthetic Organelles. Synth Biol (Oxf) 2018. [DOI: 10.1002/9783527688104.ch14] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Affiliation(s)
- Thawatchai Chaijarasphong
- Mahidol University; Faculty of Science, Department of Biotechnology; Rama VI Rd. Bangkok 10400 Thailand
| | - David F. Savage
- University of California; Department of Molecular and Cell Biology; 2151 Berkeley Way, Berkeley CA 94720 USA
- University of California; Department of Chemistry; 2151 Berkeley Way, Berkeley CA 94720 USA
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7
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Pierce SK, Mahadevan P, Massey SE, Middlebrooks ML. A Preliminary Molecular and Phylogenetic Analysis of the Genome of a Novel Endogenous Retrovirus in the Sea Slug Elysia chlorotica. THE BIOLOGICAL BULLETIN 2016; 231:236-244. [PMID: 28048954 DOI: 10.1086/691071] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
An endogenous retrovirus that is present in the sea slug Elysia chlorotica is expressed in all individuals at the end of the annual life cycle. But the precise role of the virus, if any, in slug senescence or death is unknown. We have determined the genomic sequence of the virus and performed a phylogenetic analysis of the data. The 6060-base pair genome of the virus possesses a reverse transcriptase-domain-containing protein that shows similarity to retrotransposon sequences found in Aplysia californica and Strongylocentrotus purpuratus. However, nucleotide BLAST analysis of the whole genome resulted in hits to only a few portions of the genome, indicating that the Elysia chlorotica retrovirus is novel, has not been previously sequenced, and does not have great genetic similarity to other known viral species. When more invertebrate retroviral genomes are examined, a more precise phylogenetic placement of the Elysia chlorotica retrovirus can be determined.
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9
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Rauch C, Vries JD, Rommel S, Rose LE, Woehle C, Christa G, Laetz EM, Wägele H, Tielens AGM, Nickelsen J, Schumann T, Jahns P, Gould SB. Why It Is Time to Look Beyond Algal Genes in Photosynthetic Slugs. Genome Biol Evol 2015; 7:2602-7. [PMID: 26319575 PMCID: PMC4607529 DOI: 10.1093/gbe/evv173] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Eukaryotic organelles depend on nuclear genes to perpetuate their biochemical integrity. This is true for mitochondria in all eukaryotes and plastids in plants and algae. Then how do kleptoplasts, plastids that are sequestered by some sacoglossan sea slugs, survive in the animals’ digestive gland cells in the absence of the algal nucleus encoding the vast majority of organellar proteins? For almost two decades, lateral gene transfer (LGT) from algae to slugs appeared to offer a solution, but RNA-seq analysis, later supported by genome sequencing of slug DNA, failed to find any evidence for such LGT events. Yet, isolated reports continue to be published and are readily discussed by the popular press and social media, making the data on LGT and its support for kleptoplast longevity appear controversial. However, when we take a sober look at the methods used, we realize that caution is warranted in how the results are interpreted. There is no evidence that the evolution of kleptoplasty in sea slugs involves LGT events. Based on what we know about photosystem maintenance in embryophyte plastids, we assume kleptoplasts depend on nuclear genes. However, studies have shown that some isolated algal plastids are, by nature, more robust than those of land plants. The evolution of kleptoplasty in green sea slugs involves many promising and unexplored phenomena, but there is no evidence that any of these require the expression of slug genes of algal origin.
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Affiliation(s)
- Cessa Rauch
- Molecular Evolution, Heinrich-Heine-University Düsseldorf, Germany
| | - Jan de Vries
- Molecular Evolution, Heinrich-Heine-University Düsseldorf, Germany
| | - Sophie Rommel
- Population Genetics, Heinrich-Heine-University Düsseldorf, Germany
| | - Laura E Rose
- Population Genetics, Heinrich-Heine-University Düsseldorf, Germany
| | - Christian Woehle
- Institut für Allgemeine Mikrobiologie, Christian-Albrechts-Universität ZMB, Am Botanischen Garten, Kiel, Germany
| | - Gregor Christa
- Molecular Evolution, Heinrich-Heine-University Düsseldorf, Germany
| | - Elise M Laetz
- Zoologisches Forschungsmuseum Alexander Koenig, Bonn, Germany
| | - Heike Wägele
- Zoologisches Forschungsmuseum Alexander Koenig, Bonn, Germany
| | - Aloysius G M Tielens
- Department of Biochemistry and Cell Biology, Faculty of Veterinary Medicine, Utrecht University, The Netherlands Department of Medical Microbiology and Infectious Diseases, Erasmus University Medical Center, Rotterdam, The Netherlands
| | | | - Tobias Schumann
- Plant Biochemistry and Stress Physiology, Heinrich-Heine-University Düsseldorf, Germany
| | - Peter Jahns
- Plant Biochemistry and Stress Physiology, Heinrich-Heine-University Düsseldorf, Germany
| | - Sven B Gould
- Molecular Evolution, Heinrich-Heine-University Düsseldorf, Germany
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11
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Nissen M, Shcherbakov D, Heyer A, Brümmer F, Schill RO. Behaviour of the plathelminth Symsagittifera roscoffensis under different light conditions and the consequences for the symbiotic algae Tetraselmis convolutae. ACTA ACUST UNITED AC 2015; 218:1693-8. [PMID: 25852067 DOI: 10.1242/jeb.110429] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Accepted: 03/31/2015] [Indexed: 02/03/2023]
Abstract
Symsagittifera roscoffensis is a plathelminth living in symbiosis with the green algae Tetraselmis convolutae. Host and symbiont are a model system for the study of endosymbiosis, which has so far mainly focused on their biochemical interactions. Symsagittifera roscoffensis is well known for its positive phototaxis that is hypothesized to optimize the symbiont's light perception for photosynthesis. In this study, we conducted a detailed analysis of phototaxis using light sources of different wavelength and brightness by videotracking. Furthermore, we compared the behavioural data with the electron transfer rate of the photosystem from cultured symbiotic cells. The symbiotic algae is adapted to low light conditions, showing a positive electron transfer rate at a photosynthetically active radiation of 0.112 µmol photons m(-2) s(-1), and S. roscoffensis showed a positive phototactic behaviour for light intensities up to 459.17 µmol photons m(-2) s(-1), which is not optimal regarding the needs of the symbiotic cells and may even harm host and symbiont. Red light cannot be detected by the animals and therefore their eyes seem not to be suitable for measuring the exact photosynthetically active radiation to the benefit of the photosymbionts.
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Affiliation(s)
- Matthias Nissen
- Department of Biophysics, Biological Institute, University of Rostock, Gertrudenstr. 11 A, Rostock 18057, Germany Department of Zoology, Institute of Biomaterials and Biomolecular Systems, University of Stuttgart, Pfaffenwaldring 57, Stuttgart 70569, Germany
| | - Denis Shcherbakov
- Institute of Zoology, University of Hohenheim, Garbenstr. 30, Stuttgart 70593, Germany
| | - Arnd Heyer
- Department of Plant Biotechnology, Institute of Biomaterials and Biomolecular Systems, University of Stuttgart, Pfaffenwaldring 57, Stuttgart 70569, Germany
| | - Franz Brümmer
- Department of Zoology, Institute of Biomaterials and Biomolecular Systems, University of Stuttgart, Pfaffenwaldring 57, Stuttgart 70569, Germany
| | - Ralph O Schill
- Department of Zoology, Institute of Biomaterials and Biomolecular Systems, University of Stuttgart, Pfaffenwaldring 57, Stuttgart 70569, Germany
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