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Lobo-da-Cunha A, Alves Â, Rodrigues A. Gill histology and ultrastructure in Aplysia depilans (Mollusca, Euopisthobranchia). J Morphol 2023; 284:e21562. [PMID: 36719273 DOI: 10.1002/jmor.21562] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 01/22/2023] [Accepted: 01/28/2023] [Indexed: 02/01/2023]
Abstract
The gill of Aplysia depilans consists of several wedge-shaped pinnules with a highly folded structure, differing from the typical ctenidial gills of mollusks. Light microscopy and transmission electron microscopy were used to investigate this organ in juveniles and adults. In this species, the gill epithelium comprised ciliated, unciliated, and secretory cells. The ultrastructural analysis suggests other functions for the gill besides respiration. The deep cell membrane invaginations associated with mitochondria in the basal region of epithelium point to a role in ion regulation. Endocytosis and intracellular digestion were other activities detected in epithelial cells. In juveniles, an intranuclear crystalline structure was seen in some ciliated cells. The presence of an intranuclear crystalline structure was frequently associated with chromatin decondensation, swelling of the nuclear envelope and endoplasmic reticulum cisternae, and abundance of Golgi stacks. As these intranuclear inclusions were not found in the gill of the adult specimens, their occurrence in the two juveniles seems likely to be an anomalous condition whose cause cannot be established at the moment. Mucous cells were the most abundant secretory cells in the epithelium, but a few epithelial serous cells were also found. In addition, large protein-secreting subepithelial cells had the main cell body inserted in the connective tissue and a long thin neck crossing the epithelium. Mucous cells can be considered responsible for the production of the mucus layer that protects the epithelium, but the specific functions of the epithelial and subepithelial protein-secreting cells remain elusive. Below the epithelium, a layer of connective tissue with muscle cells lined the narrow hemolymph space. The connective tissue included cells with a large amount of rough endoplasmic reticulum cisternae. Bacteria were found on the surface of the gill, and the most abundant had a thin stalk for attachment to the epithelial cells.
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Affiliation(s)
- Alexandre Lobo-da-Cunha
- Departamento de Microscopia, Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Universidade do Porto, Porto, Portugal
- Centro Interdisciplinar de Investigação Marinha e Ambiental (CIIMAR), Matosinhos, Portugal
| | - Ângela Alves
- Departamento de Microscopia, Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Universidade do Porto, Porto, Portugal
- Unidade Multidisciplinar de Investigação Biomédica (UMIB), ICBAS, Universidade do Porto, Porto, Portugal
| | - Aurora Rodrigues
- Serviço de Anatomia Patológica/Unidade Neuropatologia, Centro Hospitalar Universitário do Porto, Porto, Portugal
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Espada-Hinojosa S, Drexel J, Kesting J, Kniha E, Pifeas I, Schuster L, Volland JM, Zambalos HC, Bright M. Host-symbiont stress response to lack-of-sulfide in the giant ciliate mutualism. PLoS One 2022; 17:e0254910. [PMID: 35213532 PMCID: PMC8880863 DOI: 10.1371/journal.pone.0254910] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Accepted: 02/05/2022] [Indexed: 11/18/2022] Open
Abstract
The mutualism between the thioautotrophic bacterial ectosymbiont Candidatus Thiobius zoothamnicola and the giant ciliate Zoothamnium niveum thrives in a variety of shallow-water marine environments with highly fluctuating sulfide emissions. To persist over time, both partners must reproduce and ensure the transmission of symbionts before the sulfide stops, which enables carbon fixation of the symbiont and nourishment of the host. We experimentally investigated the response of this mutualism to depletion of sulfide. We found that colonies released some initially present but also newly produced macrozooids until death, but in fewer numbers than when exposed to sulfide. The symbionts on the colonies proliferated less without sulfide, and became larger and more rod-shaped than symbionts from freshly collected colonies that were exposed to sulfide and oxygen. The symbiotic monolayer was severely disturbed by growth of other microbes and loss of symbionts. We conclude that the response of both partners to the termination of sulfide emission was remarkably quick. The development and the release of swarmers continued until host died and thus this behavior contributed to the continuation of the association.
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Affiliation(s)
- Salvador Espada-Hinojosa
- Department of Functional and Evolutionary Ecology, University of Vienna, Vienna, Austria
- * E-mail:
| | - Judith Drexel
- Department of Functional and Evolutionary Ecology, University of Vienna, Vienna, Austria
| | - Julia Kesting
- Department of Functional and Evolutionary Ecology, University of Vienna, Vienna, Austria
| | - Edwin Kniha
- Department of Functional and Evolutionary Ecology, University of Vienna, Vienna, Austria
| | - Iason Pifeas
- Department of Functional and Evolutionary Ecology, University of Vienna, Vienna, Austria
| | - Lukas Schuster
- Department of Functional and Evolutionary Ecology, University of Vienna, Vienna, Austria
| | - Jean-Marie Volland
- Department of Functional and Evolutionary Ecology, University of Vienna, Vienna, Austria
| | - Helena C. Zambalos
- Department of Functional and Evolutionary Ecology, University of Vienna, Vienna, Austria
| | - Monika Bright
- Department of Functional and Evolutionary Ecology, University of Vienna, Vienna, Austria
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Lim SJ, Davis B, Gill D, Swetenburg J, Anderson LC, Engel AS, Campbell BJ. Gill microbiome structure and function in the chemosymbiotic coastal lucinid Stewartia floridana. FEMS Microbiol Ecol 2021; 97:6168404. [PMID: 33705534 DOI: 10.1093/femsec/fiab042] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Accepted: 03/09/2021] [Indexed: 11/14/2022] Open
Abstract
Lucinid bivalves harbor environmentally acquired, chemosynthetic, gammaproteobacterial gill endosymbionts. Lucinid gill microbiomes, which may contain other gammaproteobacterial and/or spirochete taxa, remain under-sampled. To understand inter-host variability of the lucinid gill microbiome, specifically in the bacterial communities, we analyzed the microbiome content of Stewartia floridana collected from Florida. Sampled gills contained a monospecific gammaproteobacterial endosymbiont expressing lithoautotrophic, mixotrophic, diazotrophic and C1 compound oxidation-related functions previously characterized in similar lucinid species. Another low-abundance Spirochaeta-like species in ∼72% of the sampled gills was most closely related to Spirochaeta-like species in another lucinid Phacoides pectinatus and formed a clade with known marine Spirochaeta symbionts. The spirochete expressed genes were involved in heterotrophy and the transport of sugars, amino acids, peptides and other substrates. Few muscular and neurofilament genes from the host and none from the gammaproteobacterial and spirochete symbionts were differentially expressed among quadrats predominantly covered with seagrass species or 80% bare sand. Our results suggest that spirochetes are facultatively associated with S. floridana, with potential scavenging and nutrient cycling roles. Expressed stress- and defense-related functions in the host and symbionts also suggest species-species communications, which highlight the need for further study of the interactions among lucinid hosts, their microbiomes and their environment.
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Affiliation(s)
- Shen Jean Lim
- Department of Biological Sciences, Clemson University, Clemson, SC 29634, USA
| | - Brenton Davis
- Department of Biological Sciences, Clemson University, Clemson, SC 29634, USA
| | - Danielle Gill
- Department of Biological Sciences, Clemson University, Clemson, SC 29634, USA
| | - John Swetenburg
- Department of Biological Sciences, Clemson University, Clemson, SC 29634, USA
| | - Laurie C Anderson
- Department of Geology and Geological Engineering, South Dakota School of Mines & Technology, Rapid City, SD 57701, USA
| | - Annette Summers Engel
- Department of Earth and Planetary Sciences, University of Tennessee Knoxville, Knoxville, TN 37920, USA
| | - Barbara J Campbell
- Department of Biological Sciences, Clemson University, Clemson, SC 29634, USA
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Regionalized cell proliferation in the symbiont-bearing gill of the hydrothermal vent mussel Bathymodiolus azoricus. Symbiosis 2020. [DOI: 10.1007/s13199-020-00720-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Yuen B, Polzin J, Petersen JM. Organ transcriptomes of the lucinid clam Loripes orbiculatus (Poli, 1791) provide insights into their specialised roles in the biology of a chemosymbiotic bivalve. BMC Genomics 2019; 20:820. [PMID: 31699041 PMCID: PMC6836662 DOI: 10.1186/s12864-019-6177-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Accepted: 10/03/2019] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND The lucinid clam Loripes orbiculatus lives in a nutritional symbiosis with sulphur-oxidizing bacteria housed in its gills. Although our understanding of the lucinid endosymbiont physiology and metabolism has made significant progress, relatively little is known about how the host regulates the symbiosis at the genetic and molecular levels. We generated transcriptomes from four L. orbiculatus organs (gills, foot, visceral mass, and mantle) for differential expression analyses, to better understand this clam's physiological adaptations to a chemosymbiotic lifestyle, and how it regulates nutritional and immune interactions with its symbionts. RESULTS The transcriptome profile of the symbiont-housing gill suggests the regulation of apoptosis and innate immunity are important processes in this organ. We also identified many transcripts encoding ion transporters from the solute carrier family that possibly allow metabolite exchange between host and symbiont. Despite the clam holobiont's clear reliance on chemosynthesis, the clam's visceral mass, which contains the digestive tract, is characterised by enzymes involved in digestion, carbohydrate recognition and metabolism, suggesting that L. orbiculatus has a mixotrophic diet. The foot transcriptome is dominated by the biosynthesis of glycoproteins for the construction of mucus tubes, and receptors that mediate the detection of chemical cues in the environment. CONCLUSIONS The transcriptome profiles of gills, mantle, foot and visceral mass provide insights into the molecular basis underlying the functional specialisation of bivalve organs adapted to a chemosymbiotic lifestyle.
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Affiliation(s)
- Benedict Yuen
- Centre for Microbiology and Environmental Systems Science, Division of Microbial Ecology, University of Vienna, Althanstrasse 14, 1090, Vienna, Austria.
| | - Julia Polzin
- Centre for Microbiology and Environmental Systems Science, Division of Microbial Ecology, University of Vienna, Althanstrasse 14, 1090, Vienna, Austria
| | - Jillian M Petersen
- Centre for Microbiology and Environmental Systems Science, Division of Microbial Ecology, University of Vienna, Althanstrasse 14, 1090, Vienna, Austria
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Extensive Thioautotrophic Gill Endosymbiont Diversity within a Single Ctena orbiculata (Bivalvia: Lucinidae) Population and Implications for Defining Host-Symbiont Specificity and Species Recognition. mSystems 2019; 4:4/4/e00280-19. [PMID: 31455638 PMCID: PMC6712303 DOI: 10.1128/msystems.00280-19] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Seagrass-dwelling members of the bivalve family Lucinidae harbor environmentally acquired gill endosymbionts. According to previous studies, lucinid symbionts potentially represent multiple strains from a single thioautotrophic gammaproteobacterium species. This study utilized genomic- and transcriptomic-level data to resolve symbiont taxonomic, genetic, and functional diversity from Ctena orbiculata endosymbiont populations inhabiting carbonate-rich sediment at Sugarloaf Key, FL (USA). The sediment had mixed seagrass and calcareous green alga coverage and also was colonized by at least five other lucinid species. Four coexisting, thioautotrophic endosymbiont operational taxonomic units (OTUs), likely representing four strains from two different bacterial species, were identified from C. orbiculata Three of these OTUs also occurred at high relative abundances in the other sympatric lucinid species. Interspecies genetic differences averaged about 5% lower at both pairwise average nucleotide identity and amino acid identity than interstrain differences. Despite these genetic differences, C. orbiculata endosymbionts shared a high number of metabolic functions, including highly expressed thioautotrophy-related genes and a moderately to weakly expressed conserved one-carbon (C1) oxidation gene cluster previously undescribed in lucinid symbionts. Few symbiont- and host-related genes, including those encoding symbiotic sulfurtransferase, host respiratory functions, and host sulfide oxidation functions, were differentially expressed between seagrass- and alga-covered sediment locations. In contrast to previous studies, the identification of multiple endosymbiont taxa within and across C. orbiculata individuals, which were also shared with other sympatric lucinid species, suggests that neither host nor endosymbiont displays strict taxonomic specificity. This necessitates further investigations into the nature and extent of specificity of lucinid hosts and their symbionts.IMPORTANCE Symbiont diversity and host/symbiont functions have been comprehensively profiled for only a few lucinid species. In this work, unprecedented thioautotrophic gill endosymbiont taxonomic diversity was characterized within a Ctena orbiculata population associated with both seagrass- and alga-covered sediments. Endosymbiont metabolisms included known chemosynthetic functions and an additional conserved, previously uncharacterized C1 oxidation pathway. Lucinid-symbiont associations were not species specific because this C. orbiculata population hosted multiple endosymbiont strains and species, and other sympatric lucinid species shared overlapping symbiont 16S rRNA gene diversity profiles with C. orbiculata Our results suggest that lucinid-symbiont association patterns within some host species could be more taxonomically diverse than previously thought. As such, this study highlights the importance of holistic analyses, at the population, community, and even ecosystem levels, in understanding host-microbe association patterns.
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Piquet B, Shillito B, Lallier FH, Duperron S, Andersen AC. High rates of apoptosis visualized in the symbiont-bearing gills of deep-sea Bathymodiolus mussels. PLoS One 2019; 14:e0211499. [PMID: 30716127 PMCID: PMC6361440 DOI: 10.1371/journal.pone.0211499] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Accepted: 01/15/2019] [Indexed: 12/03/2022] Open
Abstract
Symbiosis between Bathymodiolus and Gammaproteobacteria allows these deep-sea mussels to live in toxic environments such as hydrothermal vents and cold seeps. The quantity of endosymbionts within the gill-bacteriocytes appears to vary according to the hosts environment; however, the mechanisms of endosymbiont population size regulation remain obscure. We investigated the possibility of a control of endosymbiont density by apoptosis, a programmed cell death, in three mussel species. Fluorometric TUNEL and active Caspase-3-targeting antibodies were used to visualize and quantify apoptotic cells in mussel gills. To control for potential artefacts due to depressurization upon specimen recovery from the deep-sea, the apoptotic rates between mussels recovered unpressurised, versus mussels recovered in a pressure-maintaining device, were compared in two species from hydrothermal vents on the Mid-Atlantic Ridge: Bathymodiolus azoricus and B. puteoserpentis. Results show that pressurized recovery had no significant effect on the apoptotic rate in the gill filaments. Apoptotic levels were highest in the ciliated zone and in the circulating hemocytes, compared to the bacteriocyte zone. Apoptotic gill-cells in B. aff. boomerang from cold seeps off the Gulf of Guinea show similar distribution patterns. Deep-sea symbiotic mussels have much higher rates of apoptosis in their gills than the coastal mussel Mytilus edulis, which lacks chemolithoautotrophic symbionts. We discuss how apoptosis might be one of the mechanisms that contribute to the adaptation of deep-sea mussels to toxic environments and/or to symbiosis.
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Affiliation(s)
- Bérénice Piquet
- Sorbonne Université, CNRS, Lab. Adaptation et Diversité en Milieu Marin, AD2M, Team: Adaptation et Biologie des Invertébrés marins en Conditions Extrêmes (UMR 7144), ABICE, Station Biologique de Roscoff, SBR, Roscoff, France
- Sorbonne Université, MNHN, CNRS, IRD, UCN, UA, Lab. Biologie des Organismes et Ecosystèmes Aquatiques BOREA (UMR 7208), Team: Adaptation aux Milieux Extrêmes, AMEX, 7 Quai Saint-Bernard, Paris, France
| | - Bruce Shillito
- Sorbonne Université, MNHN, CNRS, IRD, UCN, UA, Lab. Biologie des Organismes et Ecosystèmes Aquatiques BOREA (UMR 7208), Team: Adaptation aux Milieux Extrêmes, AMEX, 7 Quai Saint-Bernard, Paris, France
| | - François H. Lallier
- Sorbonne Université, CNRS, Lab. Adaptation et Diversité en Milieu Marin, AD2M, Team: Adaptation et Biologie des Invertébrés marins en Conditions Extrêmes (UMR 7144), ABICE, Station Biologique de Roscoff, SBR, Roscoff, France
| | - Sébastien Duperron
- Sorbonne Université, MNHN, CNRS, IRD, UCN, UA, Lab. Biologie des Organismes et Ecosystèmes Aquatiques BOREA (UMR 7208), Team: Adaptation aux Milieux Extrêmes, AMEX, 7 Quai Saint-Bernard, Paris, France
- Muséum National d’Histoire Naturelle, CNRS, Lab. Mécanismes de Communication et Adaptation des Micro-organismes (UMR 7245), Team: Cyanobactéries, Cyanotoxines et Environnement, CCE, 12 rue Buffon, Paris, France
- Institut Universitaire de France, Paris, France
- * E-mail: (ACA); (SD)
| | - Ann C. Andersen
- Sorbonne Université, CNRS, Lab. Adaptation et Diversité en Milieu Marin, AD2M, Team: Adaptation et Biologie des Invertébrés marins en Conditions Extrêmes (UMR 7144), ABICE, Station Biologique de Roscoff, SBR, Roscoff, France
- * E-mail: (ACA); (SD)
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König S, Le Guyader H, Gros O. Thioautotrophic bacterial endosymbionts are degraded by enzymatic digestion during starvation: Case study of two lucinidsCodakia orbicularisandC. orbiculata. Microsc Res Tech 2014; 78:173-9. [DOI: 10.1002/jemt.22458] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Accepted: 11/10/2014] [Indexed: 11/11/2022]
Affiliation(s)
- Sten König
- Institut de Biologie Paris-Seine, UMR 7138 - Evolution Paris-Seine, Equipe Biologie de la Mangrove, Université des Antilles et de la Guyane, UFR des Sciences Exactes et Naturelles; Département de Biologie; BP 592. 97159 Pointe-à-Pitre Cedex Guadeloupe France
| | - Hervé Le Guyader
- Sorbonne Universités Paris VI, Institut de Biologie Paris-Seine, UMR 7138 - Evolution Paris-Seine, Equipe Phylogénie, Anatomie, Evolution, C.N.R.S, Institut de Biologie Paris-Seine, UMR 7138 - Evolution Paris-Seine, Equipe Biologie de la Mangrove
| | - Olivier Gros
- Institut de Biologie Paris-Seine, UMR 7138 - Evolution Paris-Seine, Equipe Biologie de la Mangrove, Université des Antilles et de la Guyane, UFR des Sciences Exactes et Naturelles; Département de Biologie; BP 592. 97159 Pointe-à-Pitre Cedex Guadeloupe France
- C3MAG, UFR des Sciences Exactes et Naturelles; Université des Antilles et de la Guyane; BP 592 - 97159 Pointe-à-Pitre Guadeloupe French West Indies
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Elisabeth NH, Caro A, Césaire T, Mansot JL, Escalas A, Sylvestre MN, Jean-Louis P, Gros O. Comparative modifications in bacterial gill-endosymbiotic populations of the two bivalves Codakia orbiculata and Lucina pensylvanica during bacterial loss and reacquisition. FEMS Microbiol Ecol 2014; 89:646-58. [PMID: 24939560 DOI: 10.1111/1574-6941.12366] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2014] [Revised: 05/21/2014] [Accepted: 06/05/2014] [Indexed: 11/27/2022] Open
Abstract
Until now, the culture of sulphur-oxidizing bacterial symbionts associated with marine invertebrates remains impossible. Therefore, few studies focused on symbiont's physiology under stress conditions. In this study, we carried out a comparative experiment based on two different species of lucinid bivalves (Codakia orbiculata and Lucina pensylvanica) under comparable stress factors. The bivalves were starved for 6 months in sulphide-free filtered seawater. For C. orbiculata only, starved individuals were then put back to the field, in natural sediment. We used in situ hybridization, flow cytometry and X-ray fluorescence to characterize the symbiont population hosted in the gills of both species. In L. pensylvanica, no decrease in symbiont abundance was observed throughout the starvation experiment, whereas elemental sulphur slowly decreased to zero after 3 months of starvation. Conversely, in C. orbiculata, symbiont abundance within bacteriocytes decreased rapidly and sulphur from symbionts disappeared during the first weeks of the experiment. The modifications of the cellular characteristics (SSC--relative cell size and FL1--genomic content) of the symbiotic populations along starvation were not comparable between species. Return to the sediment of starved C. orbiculata individuals led to a rapid (2-4 weeks) recovery of symbiotic cellular characteristics, comparable with unstressed symbionts. These results suggest that endosymbiotic population regulation is host-species-dependent in lucinids.
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Affiliation(s)
- Nathalie H Elisabeth
- UMR 7138 UPMC-CNRS, Equipe "Biologie de la Mangrove", Département de Biologie, UFR des Sciences Exactes et Naturelles, Université des Antilles et de la Guyane, Pointe-à-Pitre Cedex, Guadeloupe, France
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