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Hoang KL, Salguero-Gómez R, Pike VL, King KC. The impacts of host association and perturbation on symbiont fitness. Symbiosis 2024; 92:439-451. [PMID: 38666134 PMCID: PMC11039428 DOI: 10.1007/s13199-024-00984-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Accepted: 03/04/2024] [Indexed: 04/28/2024]
Abstract
Symbiosis can benefit hosts in numerous ways, but less is known about whether interactions with hosts benefit symbionts-the smaller species in the relationship. To determine the fitness impact of host association on symbionts in likely mutualisms, we conducted a meta-analysis across 91 unique host-symbiont pairings under a range of spatial and temporal contexts. Specifically, we assess the consequences to symbiont fitness when in and out of symbiosis, as well as when the symbiosis is under suboptimal or varying environments and biological conditions (e.g., host age). We find that some intracellular symbionts associated with protists tend to have greater fitness when the symbiosis is under stressful conditions. Symbionts of plants and animals did not exhibit this trend, suggesting that symbionts of multicellular hosts are more robust to perturbations. Symbiont fitness also generally increased with host age. Lastly, we show that symbionts able to proliferate in- and outside host cells exhibit greater fitness than those found exclusively inside or outside cells. The ability to grow in multiple locations may thus help symbionts thrive. We discuss these fitness patterns in light of host-driven factors, whereby hosts exert influence over symbionts to suit their own needs. Supplementary Information The online version contains supplementary material available at 10.1007/s13199-024-00984-6.
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Affiliation(s)
- Kim L. Hoang
- Department of Biology, University of Oxford, Oxford, UK
- Emory University School of Medicine, Atlanta, GA USA
| | | | | | - Kayla C. King
- Department of Biology, University of Oxford, Oxford, UK
- Department of Zoology, University of British Columbia, Vancouver, Canada
- Department of Microbiology & Immunology, University of British Columbia, Vancouver, Canada
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Anaerobic metabolism of Foraminifera thriving below the seafloor. ISME JOURNAL 2020; 14:2580-2594. [PMID: 32641728 PMCID: PMC7490399 DOI: 10.1038/s41396-020-0708-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 06/09/2020] [Accepted: 06/23/2020] [Indexed: 02/06/2023]
Abstract
Foraminifera are single-celled eukaryotes (protists) of large ecological importance, as well as environmental and paleoenvironmental indicators and biostratigraphic tools. In addition, they are capable of surviving in anoxic marine environments where they represent a major component of the benthic community. However, the cellular adaptations of Foraminifera to the anoxic environment remain poorly constrained. We sampled an oxic-anoxic transition zone in marine sediments from the Namibian shelf, where the genera Bolivina and Stainforthia dominated the Foraminifera community, and use metatranscriptomics to characterize Foraminifera metabolism across the different geochemical conditions. Relative Foraminifera gene expression in anoxic sediment increased an order of magnitude, which was confirmed in a 10-day incubation experiment where the development of anoxia coincided with a 20–40-fold increase in the relative abundance of Foraminifera protein encoding transcripts, attributed primarily to those involved in protein synthesis, intracellular protein trafficking, and modification of the cytoskeleton. This indicated that many Foraminifera were not only surviving but thriving, under the anoxic conditions. The anaerobic energy metabolism of these active Foraminifera was characterized by fermentation of sugars and amino acids, fumarate reduction, and potentially dissimilatory nitrate reduction. Moreover, the gene expression data indicate that under anoxia Foraminifera use the phosphogen creatine phosphate as an ATP store, allowing reserves of high-energy phosphate pool to be maintained for sudden demands of increased energy during anaerobic metabolism. This was co-expressed alongside genes involved in phagocytosis and clathrin-mediated endocytosis (CME). Foraminifera may use CME to utilize dissolved organic matter as a carbon and energy source, in addition to ingestion of prey cells via phagocytosis. These anaerobic metabolic mechanisms help to explain the ecological success of Foraminifera documented in the fossil record since the Cambrian period more than 500 million years ago.
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Inorganic carbon and nitrogen assimilation in cellular compartments of a benthic kleptoplastic foraminifer. Sci Rep 2018; 8:10140. [PMID: 29973634 PMCID: PMC6031614 DOI: 10.1038/s41598-018-28455-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Accepted: 06/20/2018] [Indexed: 11/08/2022] Open
Abstract
Haynesina germanica, an ubiquitous benthic foraminifer in intertidal mudflats, has the remarkable ability to isolate, sequester, and use chloroplasts from microalgae. The photosynthetic functionality of these kleptoplasts has been demonstrated by measuring photosystem II quantum efficiency and O2 production rates, but the precise role of the kleptoplasts in foraminiferal metabolism is poorly understood. Thus, the mechanism and dynamics of C and N assimilation and translocation from the kleptoplasts to the foraminiferal host requires study. The objective of this study was to investigate, using correlated TEM and NanoSIMS imaging, the assimilation of inorganic C and N (here ammonium, NH4+) in individuals of a kleptoplastic benthic foraminiferal species. H. germanica specimens were incubated for 20 h in artificial seawater enriched with H13CO3- and 15NH4+ during a light/dark cycle. All specimens (n = 12) incorporated 13C into their endoplasm stored primarily in the form of lipid droplets. A control incubation in darkness resulted in no 13C-uptake, strongly suggesting that photosynthesis is the process dominating inorganic C assimilation. Ammonium assimilation was observed both with and without light, with diffuse 15N-enrichment throughout the cytoplasm and distinct 15N-hotspots in fibrillar vesicles, electron-opaque bodies, tubulin paracrystals, bacterial associates, and, rarely and at moderate levels, in kleptoplasts. The latter observation might indicate that the kleptoplasts are involved in N assimilation. However, the higher N assimilation observed in the foraminiferal endoplasm incubated without light suggests that another cytoplasmic pathway is dominant, at least in darkness. This study clearly shows the advantage provided by the kleptoplasts as an additional source of carbon and provides observations of ammonium uptake by the foraminiferal cell.
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Melo Clavijo J, Donath A, Serôdio J, Christa G. Polymorphic adaptations in metazoans to establish and maintain photosymbioses. Biol Rev Camb Philos Soc 2018; 93:2006-2020. [PMID: 29808579 DOI: 10.1111/brv.12430] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Revised: 04/30/2018] [Accepted: 05/02/2018] [Indexed: 12/21/2022]
Abstract
Mutualistic symbioses are common throughout the animal kingdom. Rather unusual is a form of symbiosis, photosymbiosis, where animals are symbiotic with photoautotrophic organisms. Photosymbiosis is found among sponges, cnidarians, flatworms, molluscs, ascidians and even some amphibians. Generally the animal host harbours a phototrophic partner, usually a cyanobacteria or a unicellular alga. An exception to this rule is found in some sea slugs, which only retain the chloroplasts of the algal food source and maintain them photosynthetically active in their own cytosol - a phenomenon called 'functional kleptoplasty'. Research has focused largely on the biodiversity of photosymbiotic species across a range of taxa. However, many questions with regard to the evolution of the ability to establish and maintain a photosymbiosis are still unanswered. To date, attempts to understand genome adaptations which could potentially lead to the evolution of photosymbioses have only been performed in cnidarians. This knowledge gap for other systems is mainly due to a lack of genetic information, both for non-symbiotic and symbiotic species. Considering non-photosymbiotic species is, however, important to understand the factors that make symbiotic species so unique. Herein we provide an overview of the diversity of photosymbioses across the animal kingdom and discuss potential scenarios for the evolution of this association in different lineages. We stress that the evolution of photosymbiosis is probably based on genome adaptations, which (i) lead to recognition of the symbiont to establish the symbiosis, and (ii) are needed to maintain the symbiosis. We hope to stimulate research involving sequencing the genomes of various key taxa to increase the genomic resources needed to understand the most fundamental question: how have animals evolved the ability to establish and maintain a photosymbiosis?
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Affiliation(s)
- Jenny Melo Clavijo
- Center for Molecular Biodiversity Research (zmb), Zoological Research Museum Alexander Koenig, Adenauerallee 160, Bonn, 53113, Germany
| | - Alexander Donath
- Center for Molecular Biodiversity Research (zmb), Zoological Research Museum Alexander Koenig, Adenauerallee 160, Bonn, 53113, Germany
| | - João Serôdio
- Department of Biology and Center for Environmental and Marine Studies, University of Aveiro, Campus Santiago, Aveiro, 3810-192, Portugal
| | - Gregor Christa
- Center for Molecular Biodiversity Research (zmb), Zoological Research Museum Alexander Koenig, Adenauerallee 160, Bonn, 53113, Germany.,Department of Biology and Center for Environmental and Marine Studies, University of Aveiro, Campus Santiago, Aveiro, 3810-192, Portugal
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Caron DA, Alexander H, Allen AE, Archibald JM, Armbrust EV, Bachy C, Bell CJ, Bharti A, Dyhrman ST, Guida SM, Heidelberg KB, Kaye JZ, Metzner J, Smith SR, Worden AZ. Probing the evolution, ecology and physiology of marine protists using transcriptomics. Nat Rev Microbiol 2016; 15:6-20. [DOI: 10.1038/nrmicro.2016.160] [Citation(s) in RCA: 128] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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de Vries J, Stanton A, Archibald JM, Gould SB. Streptophyte Terrestrialization in Light of Plastid Evolution. TRENDS IN PLANT SCIENCE 2016; 21:467-476. [PMID: 26895731 DOI: 10.1016/j.tplants.2016.01.021] [Citation(s) in RCA: 77] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Revised: 01/19/2016] [Accepted: 01/28/2016] [Indexed: 05/21/2023]
Abstract
Key steps in evolution are often singularities. The emergence of land plants is one such case and it is not immediately apparent why. A recent analysis found that the zygnematophycean algae represent the closest relative to embryophytes. Intriguingly, many exaptations thought essential to conquer land are common among various streptophytes, but zygnematophycean algae share with land plants the transfer of a few plastid genes to the nucleus. Considering the contribution of the chloroplast to terrestrialization highlights potentially novel exaptations that currently remain unexplored. We discuss how the streptophyte chloroplast evolved into what we refer to as the embryoplast, and argue this was as important for terrestrialization by freshwater algae as the host cell-associated exaptations that are usually focused upon.
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Affiliation(s)
- Jan de Vries
- Institute for Molecular Evolution, Heinrich-Heine-University (HHU) Düsseldorf, 40225 Düsseldorf, Germany
| | - Amanda Stanton
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia B3H 4R2, Canada
| | - John M Archibald
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia B3H 4R2, Canada
| | - Sven B Gould
- Institute for Molecular Evolution, Heinrich-Heine-University (HHU) Düsseldorf, 40225 Düsseldorf, Germany.
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Gavelis GS, White RA, Suttle CA, Keeling PJ, Leander BS. Single-cell transcriptomics using spliced leader PCR: Evidence for multiple losses of photosynthesis in polykrikoid dinoflagellates. BMC Genomics 2015; 16:528. [PMID: 26183220 PMCID: PMC4504456 DOI: 10.1186/s12864-015-1636-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Accepted: 05/18/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Most microbial eukaryotes are uncultivated and thus poorly suited to standard genomic techniques. This is the case for Polykrikos lebouriae, a dinoflagellate with ultrastructurally aberrant plastids. It has been suggested that these plastids stem from a novel symbiosis with either a diatom or haptophyte, but this hypothesis has been difficult to test as P. lebouriae dwells in marine sand rife with potential genetic contaminants. RESULTS We applied spliced-leader targeted PCR (SLPCR) to obtain dinoflagellate-specific transcriptomes on single-cell isolates of P. lebouriae from marine sediments. Polykrikos lebouriae expressed nuclear-encoded photosynthetic genes that were characteristic of the peridinin-plastids of dinoflagellates, rather than those from a diatom of haptophyte. We confirmed these findings at the genomic level using multiple displacement amplification (MDA) to obtain a partial plastome of P. lebouriae. CONCLUSION From these data, we infer that P. lebouriae has retained the peridinin plastids ancestral for dinoflagellates as a whole, while its closest relatives have lost photosynthesis multiple times independently. We discuss these losses with reference to mixotrophy in polykrikoid dinoflagellates. Our findings demonstrate new levels of variation associated with the peridinin plastids of dinoflagellates and the usefulness of SLPCR approaches on single cell isolates. Unlike other transcriptomic methods, SLPCR has taxonomic specificity, and can in principle be adapted to different splice-leader bearing groups.
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Affiliation(s)
- Gregory S Gavelis
- Department of Zoology, University of British Columbia, Vancouver, BC, V6T1Z4, Canada.
| | - Richard A White
- Department of Microbiology & Immunology, University of British Columbia, Vancouver, BC, V6T1Z4, Canada.
| | - Curtis A Suttle
- Department of Microbiology & Immunology, University of British Columbia, Vancouver, BC, V6T1Z4, Canada.
- Department of Botany, University of British Columbia, Vancouver, BC, V6T1Z4, Canada.
- Department of Earth, Ocean and Atmospheric Sciences, Vancouver, BC, V6T1Z4, Canada.
| | - Patrick J Keeling
- Department of Botany, University of British Columbia, Vancouver, BC, V6T1Z4, Canada.
| | - Brian S Leander
- Department of Zoology, University of British Columbia, Vancouver, BC, V6T1Z4, Canada.
- Department of Botany, University of British Columbia, Vancouver, BC, V6T1Z4, Canada.
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Balzano S, Corre E, Decelle J, Sierra R, Wincker P, Da Silva C, Poulain J, Pawlowski J, Not F. Transcriptome analyses to investigate symbiotic relationships between marine protists. Front Microbiol 2015; 6:98. [PMID: 25852650 PMCID: PMC4362344 DOI: 10.3389/fmicb.2015.00098] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2014] [Accepted: 01/26/2015] [Indexed: 11/13/2022] Open
Abstract
Rhizaria are an important component of oceanic plankton communities worldwide. A number of species harbor eukaryotic microalgal symbionts, which are horizontally acquired in the environment at each generation. Although these photosymbioses are determinant for Rhizaria ability to thrive in oceanic ecosystems, the mechanisms for symbiotic interactions are unclear. Using high-throughput sequencing technology (i.e., 454), we generated large Expressed Sequence Tag (EST) datasets from four uncultured Rhizaria, an acantharian (Amphilonche elongata), two polycystines (Collozoum sp. and Spongosphaera streptacantha), and one phaeodarian (Aulacantha scolymantha). We assessed the main genetic features of the host/symbionts consortium (i.e., the holobiont) transcriptomes and found rRNA sequences affiliated to a wide range of bacteria and protists in all samples, suggesting that diverse microbial communities are associated with the holobionts. A particular focus was then carried out to search for genes potentially involved in symbiotic processes such as the presence of c-type lectins-coding genes, which are proteins that play a role in cell recognition among eukaryotes. Unigenes coding putative c-type lectin domains (CTLD) were found in the species bearing photosynthetic symbionts (A. elongata, Collozoum sp., and S. streptacantha) but not in the non-symbiotic one (A. scolymantha). More particularly, phylogenetic analyses group CTLDs from A. elongata and Collozoum sp. on a distinct branch from S. streptacantha CTLDs, which contained carbohydrate-binding motifs typically observed in other marine photosymbiosis. Our data suggest that similarly to other well-known marine photosymbiosis involving metazoans, the interactions of glycans with c-type lectins is likely involved in modulation of the host/symbiont specific recognition in Radiolaria.
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Affiliation(s)
- Sergio Balzano
- UMR 7144, Université Pierre et Marie Curie Université Paris 06, Sorbonne Universités, Station Biologique de Roscoff Roscoff, France ; Centre National de la Recherche Scientifique, UMR 7144, Station Biologique de Roscoff Roscoff, France
| | - Erwan Corre
- Centre National de la Recherche Scientifique and Université Pierre et Marie Curie, FR2424, ABiMS, Station Biologique Roscoff, France
| | - Johan Decelle
- UMR 7144, Université Pierre et Marie Curie Université Paris 06, Sorbonne Universités, Station Biologique de Roscoff Roscoff, France ; Centre National de la Recherche Scientifique, UMR 7144, Station Biologique de Roscoff Roscoff, France
| | - Roberto Sierra
- Department of Genetics and Evolution, University of Geneva Geneva, Switzerland
| | - Patrick Wincker
- Commissariat à l'Energie Atomique et aux Energies Alternatives Genoscope, France
| | - Corinne Da Silva
- Commissariat à l'Energie Atomique et aux Energies Alternatives Genoscope, France
| | - Julie Poulain
- Commissariat à l'Energie Atomique et aux Energies Alternatives Genoscope, France
| | - Jan Pawlowski
- Department of Genetics and Evolution, University of Geneva Geneva, Switzerland
| | - Fabrice Not
- UMR 7144, Université Pierre et Marie Curie Université Paris 06, Sorbonne Universités, Station Biologique de Roscoff Roscoff, France ; Centre National de la Recherche Scientifique, UMR 7144, Station Biologique de Roscoff Roscoff, France
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Pillet L. The role of horizontal gene transfer in kleptoplastidy and the establishment of photosynthesis in the eukaryotes. Mob Genet Elements 2014; 3:e24773. [PMID: 23914312 DOI: 10.4161/mge.24773] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2013] [Accepted: 04/22/2013] [Indexed: 11/19/2022] Open
Abstract
Found in different eukaryotic lineages, kleptoplastidy is the ability to sequester chloroplasts from algal preys that are ingested and partially digested. While most of the genetic information required for the activity and maintenance of the kleptoplastids disappeared with the digestion of the algal nuclei, the photosynthetic organelles remain active during extended period of time. Many different hypotheses have been proposed to explain the longevity of the kleptoplastids within their host. The most popular one involves Horizontal Gene Transfer (HGT) from the algal genome to the host nucleus. In order to test this hypothesis, transcriptome-based analyses have been performed on different kleptoplastidic organisms during the past few years. However, the variability of the results obtained does not allow drawing a convincing conclusion regarding the precise role of HGT in kleptoplastidy. Understanding the mechanism that allow persistence of the plastids is crucial, not only for the characterization of kleptoplastidy, but also for important evolutionary questions surrounding endosymbiotic events and the emergence and spread of photosynthesis in the eukaryotes. Here, I discuss alternative theories that could explain the longevity of sequestered plastids in their host, with special focus on the simplest chloroplast stability hypothesis.
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Affiliation(s)
- Loïc Pillet
- Department of Genetics and Evolution; University of Geneva; Geneva, Switzerland
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Santoferrara LF, Guida S, Zhang H, McManus GB. De novo transcriptomes of a mixotrophic and a heterotrophic ciliate from marine plankton. PLoS One 2014; 9:e101418. [PMID: 24983246 PMCID: PMC4077812 DOI: 10.1371/journal.pone.0101418] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2014] [Accepted: 06/06/2014] [Indexed: 11/19/2022] Open
Abstract
Studying non-model organisms is crucial in the context of the current development of genomics and transcriptomics for both physiological experimentation and environmental characterization. We investigated the transcriptomes of two marine planktonic ciliates, the mixotrophic oligotrich Strombidium rassoulzadegani and the heterotrophic choreotrich Strombidinopsis sp., and their respective algal food using Illumina RNAseq. Our aim was to characterize the transcriptomes of these contrasting ciliates and to identify genes potentially involved in mixotrophy. We detected approximately 10,000 and 7,600 amino acid sequences for S. rassoulzadegani and Strombidinopsis sp., respectively. About half of these transcripts had significant BLASTP hits (E-value <10−6) against previously-characterized sequences, mostly from the model ciliate Oxytricha trifallax. Transcriptomes from both the mixotroph and the heterotroph species provided similar annotations for GO terms and KEGG pathways. Most of the identified genes were related to housekeeping activity and pathways such as the metabolism of carbohydrates, lipids, amino acids, nucleotides, and vitamins. Although S. rassoulzadegani can keep and use chloroplasts from its prey, we did not find genes clearly linked to chloroplast maintenance and functioning in the transcriptome of this ciliate. While chloroplasts are known sources of reactive oxygen species (ROS), we found the same complement of antioxidant pathways in both ciliates, except for one enzyme possibly linked to ascorbic acid recycling found exclusively in the mixotroph. Contrary to our expectations, we did not find qualitative differences in genes potentially related to mixotrophy. However, these transcriptomes will help to establish a basis for the evaluation of differential gene expression in oligotrichs and choreotrichs and experimental investigation of the costs and benefits of mixotrophy.
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Affiliation(s)
- Luciana F. Santoferrara
- Department of Marine Sciences, University of Connecticut, Groton, Connecticut, United States of America
- * E-mail:
| | - Stephanie Guida
- The National Center for Genome Resources, Santa Fe, New Mexico, United States of America
| | - Huan Zhang
- Department of Marine Sciences, University of Connecticut, Groton, Connecticut, United States of America
| | - George B. McManus
- Department of Marine Sciences, University of Connecticut, Groton, Connecticut, United States of America
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Yamaguchi H, Nakayama T, Hongoh Y, Kawachi M, Inouye I. Molecular diversity of endosymbiotic Nephroselmis (Nephroselmidophyceae) in Hatena arenicola (Katablepharidophycota). JOURNAL OF PLANT RESEARCH 2014; 127:241-247. [PMID: 23979010 DOI: 10.1007/s10265-013-0591-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2013] [Accepted: 06/30/2013] [Indexed: 06/02/2023]
Abstract
Hatena arenicola (Katablepharidophycota) is a single-celled eukaryote that temporarily possesses a chlorophyte alga of the genus Nephroselmis as an intracellular symbiont. In the present study, we investigated the molecular diversity of the endosymbiont Nephroselmis in a natural population of the host H. arenicola. We sequenced the host's 18S rRNA gene and the endosymbiont's plastid-encoded 16S rRNA gene. The results indicated that almost identical strains of the host harbored at least three distinct strains of the algal endosymbiont affiliated to the clade Nephroselmis rotunda. This finding supports our previous hypothesis that H. arenicola and its symbiotic alga are in an early stage of secondary endosymbiosis.
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MESH Headings
- Base Sequence
- Chlorophyta/genetics
- Chlorophyta/physiology
- DNA, Plant/chemistry
- DNA, Plant/genetics
- DNA, Ribosomal/chemistry
- DNA, Ribosomal/genetics
- Eukaryota/genetics
- Eukaryota/physiology
- Genetic Variation
- Molecular Sequence Data
- Phylogeny
- Plastids/genetics
- RNA, Plant/genetics
- RNA, Ribosomal, 16S/genetics
- RNA, Ribosomal, 18S/genetics
- Sequence Analysis, DNA
- Symbiosis
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Affiliation(s)
- Haruyo Yamaguchi
- National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki, 305-8506, Japan,
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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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The genome of the foraminiferan Reticulomyxa filosa. Curr Biol 2013; 24:11-18. [PMID: 24332546 DOI: 10.1016/j.cub.2013.11.027] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2013] [Revised: 10/09/2013] [Accepted: 11/12/2013] [Indexed: 02/08/2023]
Abstract
BACKGROUND Rhizaria are a major branch of eukaryote evolution with an extensive microfossil record, but only scarce molecular data are available. The rhizarian species Reticulomyxa filosa, belonging to the Foraminifera, is free-living in freshwater environments. In culture, it thrives only as a plasmodium with thousands of haploid nuclei in one cell. The R. filosa genome is the first foraminiferal genome to be deciphered. RESULTS The genome is extremely repetitive, and the large amounts of identical sequences hint at frequent amplifications and homologous recombination events. Presumably, these mechanisms are employed to provide more gene copies for higher transcriptional activity and to build up a reservoir of gene diversification in certain gene families, such as the kinesin family. The gene repertoire indicates that it is able to switch to a single-celled, flagellated sexual state never observed in culture. Comparison to another rhizarian, the chlorarachniophyte alga Bigelowiella natans, reveals that proteins involved in signaling were likely drivers in establishing the Rhizaria lineage. Compared to some other protists, horizontal gene transfer is limited, but we found evidence of bacterial-to-eukaryote and eukaryote-to-eukaryote transfer events. CONCLUSIONS The R. filosa genome exhibits a unique architecture with extensive repeat homogenization and gene amplification, which highlights its potential for diverse life-cycle stages. The ability of R. filosa to rapidly transport matter from the pseudopodia to the cell body may be supported by the high diversification of actin and kinesin gene family members.
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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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Bhattacharya D, Pelletreau KN, Price DC, Sarver KE, Rumpho ME. Genome analysis of Elysia chlorotica Egg DNA provides no evidence for horizontal gene transfer into the germ line of this Kleptoplastic Mollusc. Mol Biol Evol 2013; 30:1843-52. [PMID: 23645554 PMCID: PMC3708498 DOI: 10.1093/molbev/mst084] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The sea slug Elysia chlorotica offers a unique opportunity to study the evolution of a novel function (photosynthesis) in a complex multicellular host. Elysia chlorotica harvests plastids (absent of nuclei) from its heterokont algal prey, Vaucheria litorea. The “stolen” plastids are maintained for several months in cells of the digestive tract and are essential for animal development. The basis of long-term maintenance of photosynthesis in this sea slug was thought to be explained by extensive horizontal gene transfer (HGT) from the nucleus of the alga to the animal nucleus, followed by expression of algal genes in the gut to provide essential plastid-destined proteins. Early studies of target genes and proteins supported the HGT hypothesis, but more recent genome-wide data provide conflicting results. Here, we generated significant genome data from the E. chlorotica germ line (egg DNA) and from V. litorea to test the HGT hypothesis. Our comprehensive analyses fail to provide evidence for alga-derived HGT into the germ line of the sea slug. Polymerase chain reaction analyses of genomic DNA and cDNA from different individual E. chlorotica suggest, however, that algal nuclear genes (or gene fragments) are present in the adult slug. We suggest that these nucleic acids may derive from and/or reside in extrachromosomal DNAs that are made available to the animal through contact with the alga. These data resolve a long-standing issue and suggest that HGT is not the primary reason underlying long-term maintenance of photosynthesis in E. chlorotica. Therefore, sea slug photosynthesis is sustained in as yet unexplained ways that do not appear to endanger the animal germ line through the introduction of dozens of foreign genes.
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Affiliation(s)
- Debashish Bhattacharya
- Department of Ecology, Evolution and Natural Resources and Institute of Marine and Coastal Science, Rutgers University
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Schmidt S, Raven JA, Paungfoo-Lonhienne C. The mixotrophic nature of photosynthetic plants. FUNCTIONAL PLANT BIOLOGY : FPB 2013; 40:425-438. [PMID: 32481119 DOI: 10.1071/fp13061] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2013] [Accepted: 03/22/2013] [Indexed: 06/11/2023]
Abstract
Plants typically have photosynthetically competent green shoots. To complement resources derived from the atmospheric environment, plants also acquire essential elements from soil. Inorganic ions and molecules are generally considered to be the sources of soil-derived nutrients, and plants tested in this respect can grow with only inorganic nutrients and so can live as autotrophs. However, mycorrhizal symbionts are known to access nutrients from organic matter. Furthermore, specialist lineages of terrestrial photosynthetically competent plants are mixotrophic, including species that obtain organic nutrition from animal prey (carnivores), fungal partners (mycoheterotrophs) or plant hosts (hemi-parasites). Although mixotrophy is deemed the exception in terrestrial plants, it is a common mode of nutrition in aquatic algae. There is mounting evidence that non-specialist plants acquire organic compounds as sources of nutrients, taking up and metabolising a range of organic monomers, oligomers, polymers and even microbes as sources of nitrogen and phosphorus. Plasma-membrane located transporter proteins facilitate the uptake of low-molecular mass organic compounds, endo- and phagocytosis may enable the acquisition of larger compounds, although this has not been confirmed. Identifying the mechanisms involved in the acquisition of organic nutrients will provide understanding of the ecological significance of mixotrophy. Here, we discuss mixotrophy in the context of nitrogen and phosphorus nutrition drawing parallels between algae and plants.
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Affiliation(s)
- Susanne Schmidt
- School of Agriculture and Food Sciences, The University of Queensland, St Lucia, Qld 4072, Australia
| | - John A Raven
- Division of Plant Sciences, University of Dundee at the James Hutton Institute, Invergowrie, Dundee DD2 5DA, UK
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