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Alexander V. Ereskovsky - One of the best experts on this subject based on the ideXlab platform.
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Kinetid structure in larval and adult stages of the demosponges Haliclona aquaeductus (Haplosclerida) and Halichondria panicea (Suberitida)
Zoomorphology, 2019Co-Authors: Agniya M. Sokolova, Igor R. Pozdnyakov, Alexander V. Ereskovsky, Sergey A. KarpovAbstract:At larval and adult stage of life cycle, sponges (Porifera) have different flagellated cells that play different roles in their body. The larval epithelium cells serve as locomotion organs, while adult collar cells (Choanocytes) have a feeding function. Here, for the first time, we describe detailed structure of the flagellar apparatus (kinetid) in larval cells and Choanocytes of Haliclona aquaeductus and Halichondria panicea demosponges, and attach schemes of its organization, based on longitudinal and transversal ultrathin serial sections. The kinetid of larvae has proved to be more complicated than the Choanocytes ones. It includes well-developed transverse and longitudinal cytoskeletons that strengthen the larval flagellum. The longitudinal skeleton in H. aquaeductus is represented by unusual structures, which were previously understudied: large tubular rootlets made of oblique-crossed fibers, which connect the kinetosome with mitochondria. We also found out that the kinetid composition varies between different cell types of a highly structured parenchymella of H. aquaeductus . In simply organized parenchymella of H. panicea , flagellated cells are identical and its kinetid includes a permanent additional centriole absent in Choanocytes of adult sponges. We tried to evaluate the diversity of sponge larval kinetid organization based on literature data and found it variable within Haplosclerida and quite conservative within other sponge lineages.
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Oscarella pearsei sp. nov. TEM of cells and symbiotic bacteria.
2017Co-Authors: Alexander V. Ereskovsky, Daniel J. Richte, Dennis V. Lavrov, Klaske J. Schippers, Sco A. NicholsAbstract:(A) exopinacocyte; (B) endopinacocyte; (C) Choanocytes; (D) apopylar cell; (E) apical part of Choanocyte with glycocalyx layer; (F) basal parts of Choanocyte and endopinacocyte with basement membrane. (Abbreviations: AG–Golgi apparatus, ap–apopylar cell, B–symbiotic bacteria, bb–basal body of flagellum, bm–basement membrane, ch–Choanocytes, en–endopinacocyte, ex–exopinacocyte, f–flagellum, mv–microvilli, n–nucleus, ph–phagosome. Arrowheads–white: basal surface has pseudopodia that extend into the extracellular matrix. black: glycocalyx).
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Oscarella pearsei sp. nov. reproduction.
2017Co-Authors: Alexander V. Ereskovsky, Dennis V. Lavrov, Klaske J. Schippers, Daniel J. Richter, Scott A. NicholsAbstract:(A) semi-thin section of the spermatocyst; (B) TEM of young oocyte before vitellogenesis; (C) semi-thin section of the egg with flat monolayer follicle and the thick layer of maternal cells; (D) TEM of flat monolayer follicle of the egg and the thick layer of maternal cells; (E) semi-thin section of the embryo with bilayer follicle composed of cubical cells; (F) histological section of embryos with cubical follicle; (G) semi-thin section of the cinctoblastula larva; (H) TEM of the embryo with bilayer follicle with flat external layer and cubical internal ones. (Abbreviations: cc—Choanocyte chamber, cf–cubic follicle, ch–Choanocyte, eg–egg, em–embryo, en–endopinacocyte, ex–exhalant canal, ff–flat follicle, gc–granular cells; l–larva, lc–larval cavity, le–larval ciliated epithelium, mc–maternal cells; n–nucleus, oo- oocyte, sc–spherulous cells with paracrystalline inclusions, sp–spermatocyst).
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Three hours after operation.
2015Co-Authors: Alexander V. Ereskovsky, Ilya E. Orisenko, Eve Gazave, Daria . Tokina, Pascal Lapebie, Carole OrchielliniAbstract:A. Semithin section of injured sponge. Box shows the magnified area displayed in panel C. B. SEM of the wound surface. C. Semithin section of a wound. D. SEM of the marginal zone of a wound and intact exopinacoderm. E. Semithin section showing the condensation of the extracellular matrix of mesohyl, collagen fibers and concentration of symbiotic bacteria in the wound, and Choanocytes having migrated inside chamber cavities (arrowhead). F. SEM of intact exopinacocytes of marginal zones that have begun preparation for migration in the direction of the wound surfaces. This preparation is expressed in changes in the form of cells: from flat to oval and pseudopodia formation, directed toward the wound surface. cc—Choanocyte chamber, d—debris; da—damaged area, exp—exopinacocyte, iz—intact zone, ps—pseudopodia. Scale bars: A— 200 μm, B—250 μm; C—100 μm; D—25 μm, E—50 μm; F—2 μm.
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The morphology of intact Oscarella lobularis.
2015Co-Authors: Alexander V. Ereskovsky, Ilya E. Orisenko, Eve Gazave, Daria . Tokina, Pascal Lapebie, Carole OrchielliniAbstract:A. Semithin section of upper part of sponge. B. SEM of an exopinacocytes. C. SEM of an endopinacocytes. D. TEM of a Choanocytes. E. SEM of an apopyle with apopylar cells. F. TEM of type 1 and type 2 vacuolar cells. b—symbiotic bacteria, bm—basal membrane, ca—canal cavity, cc—Choanocyte chamber, ec—exhalant canal, enp—endopinacocytes, exp—exopinacocytes, f—flagellum, ic—inhalant canal, m—mesohyl, mv—microvilli, n—nucleus, o—ostium, ph—phagosome, ps—pseudopodia, v—vacuole, v1—vacuolar cell type 1, v2—vacuolar cell type 2. Scale bars: A—50 μm, B—10 μm; C—5 μm; D—2 μm; E—5 μm; F—3 μm.
Noriko Funayama - One of the best experts on this subject based on the ideXlab platform.
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Conserved expression of vertebrate microvillar gene homologs in Choanocytes of freshwater sponges
EvoDevo, 2016Co-Authors: Jesús F. Peña, Noriko Funayama, Alexandre Alié, Daniel J. Richter, Lingyu Wang, Scott A. NicholsAbstract:Background The microvillus is a versatile organelle that serves important functions in disparate animal cell types. However, from a molecular perspective, the microvillus has been well studied in only a few, predominantly vertebrate, contexts. Little is known about how differences in microvillar structure contribute to differences in function, and how these differences evolved. We sequenced the transcriptome of the freshwater sponge, Ephydatia muelleri , and examined the expression of vertebrate microvillar gene homologs in Choanocytes—the only microvilli-bearing cell type present in sponges. Sponges offer a distant phylogenetic comparison with vertebrates, and Choanocytes are central to discussions about early animal evolution due to their similarity with choanoflagellates, the single-celled sister lineage of modern animals. Results We found that, from a genomic perspective, sponges have conserved homologs of most vertebrate microvillar genes, most of which are expressed in Choanocytes, and many of which exhibit Choanocyte-specific or Choanocyte-enriched expression. Possible exceptions include the cadherins that form intermicrovillar links in the enterocyte brush border and hair cell stereocilia of vertebrates and cnidarians. No obvious orthologs of these proteins were detected in sponges, but at least four candidate cadherins were identified as Choanocyte-enriched and might serve this function. In contrast to the evidence for conserved microvillar structure in sponges and vertebrates, we found that choanoflagellates and ctenophores lack homologs of many fundamental microvillar genes, suggesting that microvillar structure may diverge significantly in these lineages, warranting further study. Conclusions The available evidence suggests that microvilli evolved early in the prehistory of modern animals and have been repurposed to serve myriad functions in different cellular contexts. Detailed understanding of the sequence by which different microvilli-bearing cell/tissue types diversified will require further study of microvillar composition and development in disparate cell types and lineages. Of particular interest are the microvilli of choanoflagellates, ctenophores, and sponges, which collectively bracket the earliest events in animal evolution.
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Piwi expression in archeocytes and Choanocytes in demosponges: insights into the stem cell system in demosponges.
Evolution & development, 2010Co-Authors: Noriko Funayama, Mikiko Nakatsukasa, Kurato Mohri, Yoshiki Masuda, Kiyokazu AgataAbstract:Little is known about the stem cells of organisms early in metazoan evolution. To characterize the stem cell system in demosponges, we identified Piwi homologs of a freshwater sponge, Ephydatia fluviatilis, as candidate stem cell (archeocyte) markers. EfPiwiA mRNA was expressed in cells with archeocyte cell morphological features. We demonstrated that these EfPiwiA-expressing cells were indeed stem cells by showing their ability to proliferate, as indicated by BrdU-incorporation, and to differentiate, as indicated by the coexpression of EfPiwiA with cell-lineage-specific genes in presumptive committed archeocytes. EfPiwiA mRNA expression was maintained in mature Choanocytes forming chambers, in contrast to the transition of gene expression from EfPiwiA to cell-lineage-specific markers during archeocyte differentiation into other cell types. Choanocytes are food-entrapping cells with morphological features similar to those of choanoflagellates (microvillus collar and a flagellum). Their known abilities to transform into archeocytes under specific circumstances and to give rise to gametes (mostly sperm) indicate that even when they are fully differentiated, Choanocytes maintain pluripotent stem cell-like potential. Based on the specific expression of EfPiwiA in archeocytes and Choanocytes, combined with previous studies, we propose that both archeocytes and Choanocytes are components of the demosponge stem cell system. We discuss the possibility that Choanocytes might represent the ancestral stem cells, whereas archeocytes might represent stem cells that further evolved in ancestral multicellular organisms.
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Isolation of the Choanocyte in the fresh water sponge, Ephydatia fluviatilis and its lineage marker, Ef annexin
Development growth & differentiation, 2005Co-Authors: Noriko Funayama, Mikiko Nakatsukasa, Tetsutaro Hayashi, Kiyokazu AgataAbstract:In order to investigate the cellular system of the freshwater sponge, Ephydatia fluviatilis, we isolated a molecular marker for the most prominent cell type, the Choanocyte. After feeding sponge with fluorescent beads, fluorescent-labeled Choanocytes were collected by fluorescence activated cell sorting (FACS). By protein profiling Choanocyte and archeocyte (stem cell)-rich fractions, proteins characteristic of Choanocyte were identified. The partial amino-acid sequence of one of the proteins characteristic of Choanocyte matches the deduced amino-acid sequence of sponge expression tag (EST) clones and mouse annexin VII. These EST clones overlap and encode a protein, designated Ef annexin, which includes four annexin domains. Whole mount in situ hybridization shows Ef annexin expression in chamber-forming Choanocytes in 7-day-old sponge, leading us to conclude that Ef annexin can be used as a Choanocyte marker. In the early development stage, Ef annexin expression can be detected in both large single cells, characteristic of archeocytes, and cells forming 2-, 4- and multiple-cell clusters. These results indicate that Ef annexin is initially expressed in the Choanocyte-committed archeocyte which then undergoes several mitotic cell divisions to form a Choanocyte chamber. This suggests that the single Choanocyte chamber essentially originates from a single archeocyte.
Shunsuke Sogabe - One of the best experts on this subject based on the ideXlab platform.
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Pluripotency and the origin of animal multicellularity
Nature, 2019Co-Authors: Shunsuke Sogabe, William L. Hatleberg, Kevin M. Kocot, Tahsha E. Say, Daniel Stoupin, Kathrein E. Roper, Selene L. Fernandez-valverde, Sandie M. Degnan, Bernard M. DegnanAbstract:Comparison of transcriptomes, cell fates and behaviour of three primary cell types from the sponge Amphimedon queenslandica with choanoflagellates and other unicellular holozoans suggests that the first animal cells transitioned between multiple states. A widely held—but rarely tested—hypothesis for the origin of animals is that they evolved from a unicellular ancestor, with an apical cilium surrounded by a microvillar collar, that structurally resembled modern sponge Choanocytes and choanoflagellates^ 1 – 4 . Here we test this view of animal origins by comparing the transcriptomes, fates and behaviours of the three primary sponge cell types—Choanocytes, pluripotent mesenchymal archaeocytes and epithelial pinacocytes—with choanoflagellates and other unicellular holozoans. Unexpectedly, we find that the transcriptome of sponge Choanocytes is the least similar to the transcriptomes of choanoflagellates and is significantly enriched in genes unique to either animals or sponges alone. By contrast, pluripotent archaeocytes upregulate genes that control cell proliferation and gene expression, as in other metazoan stem cells and in the proliferating stages of two unicellular holozoans, including a colonial choanoflagellate. Choanocytes in the sponge Amphimedon queenslandica exist in a transient metastable state and readily transdifferentiate into archaeocytes, which can differentiate into a range of other cell types. These sponge cell-type conversions are similar to the temporal cell-state changes that occur in unicellular holozoans^ 5 . Together, these analyses argue against homology of sponge Choanocytes and choanoflagellates, and the view that the first multicellular animals were simple balls of cells with limited capacity to differentiate. Instead, our results are consistent with the first animal cell being able to transition between multiple states in a manner similar to modern transdifferentiating and stem cells.
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Pluripotency and the origin of animal multicellularity
2019Co-Authors: Shunsuke Sogabe, William L. Hatleberg, Kevin M. Kocot, Tahsha E. Say, Daniel Stoupin, Kathrein E. Roper, Selene L. Fernandez-valverde, Sandie M. Degnan, Bernard M. DegnanAbstract:The most widely held, but rarely tested, hypothesis for the origin of animals is that they evolved from a unicellular ancestor with an apical cilium surrounded by a microvillar collar that structurally resembled present-day sponge Choanocytes and choanoflagellates1,2,3,4. Here we test this traditional view of the origin of the animal kingdom by comparing the transcriptomes, fates and behaviours of the three primary sponge cell types, Choanocytes, pluripotent mesenchymal archeocytes and epithelial pinacocytes, with choanoflagellates and other unicellular holozoans. Unexpectedly, we find the transcriptome of sponge Choanocytes is the least similar to the transcriptomes of choanoflagellates and is significantly enriched in genes unique to either animals or to sponges alone. In contrast, pluripotent archeocytes upregulate genes controlling cell proliferation and gene expression, as in other metazoan stem cells and in the proliferating stages of two closely-related unicellular holozoans, including a colonial choanoflagellate. In the context of the body plan of the sponge, Amphimedon queenslandica, we show that Choanocytes appear late in development and are the result of a transdifferentiation event. They exist in a metastable state and readily transdifferentiate into archeocytes, which can differentiate into a range of other cell types. These sponge cell type conversions are similar to the temporal cell state changes that occur in many unicellular holozoans5. Together, these analyses offer no support for the homology of sponge Choanocytes and choanoflagellates, nor for the view that the first multicellular animals were simple balls of cells with limited capacity to differentiate. Instead, our results are consistent with the first animal cell being able to transition between multiple states in a manner similar to modern transdifferentiating and stem cells.
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the ontogeny of Choanocyte chambers during metamorphosis in the demosponge amphimedon queenslandica
Evodevo, 2016Co-Authors: Shunsuke Sogabe, Nagayasu Nakanishi, Bernhard M DegnanAbstract:Background The aquiferous body plan of poriferans revolves around internal chambers comprised of Choanocytes, a cell type structurally similar to choanoflagellates. These Choanocyte chambers perform a range of physiological and developmental functions, including the capture of food and the generation of stem cells. Despite the increasing interest for Choanocytes as sponge stem cells, there is limited knowledge on the development of Choanocyte chambers. Using a combination of cell lineage tracing, antibody staining and EdU labeling, here we examine the development of Choanocytes and the chambers they comprise during metamorphosis in the marine demosponge Amphimedon queenslandica.
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The ontogeny of Choanocyte chambers during metamorphosis in the demosponge Amphimedon queenslandica
EvoDevo, 2016Co-Authors: Shunsuke Sogabe, Nagayasu Nakanishi, Bernhard M DegnanAbstract:Background The aquiferous body plan of poriferans revolves around internal chambers comprised of Choanocytes, a cell type structurally similar to choanoflagellates. These Choanocyte chambers perform a range of physiological and developmental functions, including the capture of food and the generation of stem cells. Despite the increasing interest for Choanocytes as sponge stem cells, there is limited knowledge on the development of Choanocyte chambers. Using a combination of cell lineage tracing, antibody staining and EdU labeling, here we examine the development of Choanocytes and the chambers they comprise during metamorphosis in the marine demosponge Amphimedon queenslandica . Results Lineage-tracing experiments show that larval epithelial cells transform into mesenchymal pluripotent stem cells, resembling archeocytes, within 24 h of initiating metamorphosis. By 36 h, some of these labeled archeocyte-like cells have differentiated into Choanocytes that will form the first postlarval Choanocyte chambers. Non-labeled cells also contribute to these primary Choanocyte chambers, consistent with these chambers being a chimera of multiple transdifferentiated larval cell types and not the proliferation of a single Choanocyte precursor. Moreover, cell proliferation assays demonstrate that, following the initial formation of Choanocyte chambers, chambers grow at least partially by the proliferation of Choanocytes within the chamber, although recruitment of individual cells into established chambers also appears to occur. EdU labeling of postlarvae and juveniles reveals that Choanocyte chambers are the primary location of cell proliferation during metamorphosis. Conclusion Our results show that multiple larval cell lineages typically contribute to formation of individual Choanocyte chambers at metamorphosis, contrary to previous reports in other species that show sponge Choanocyte chambers form clonally. Choanocytes in postlarval and juvenile A. queenslandica chambers can also divide, with Choanocyte chambers being the primary location of cell proliferation. Interestingly, the level of cell proliferation varies greatly between chambers and appears to be contingent on the size, location and developmental state of the chamber. Small chambers on the periphery of the body tend to possess more dividing cells. As Choanocytes can also dedifferentiate into archeocyte-like cells, cell proliferation in chambers may not only contribute to chamber growth and self-renewal but also increase the number of pluripotent archeocytes.
Hans Ulrik Riisgård - One of the best experts on this subject based on the ideXlab platform.
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Hydrodynamic characteristics of aquiferous modules in the demosponge Halichondria panicea
Marine Biology Research, 2019Co-Authors: Rachael A. Kealy, Thomas Busk, Josephine Goldstein, Poul Scheel Larsen, Hans Ulrik RiisgårdAbstract:ABSTRACTMulti-oscula sponges are organisms composed of aquiferous modules, each of which draws water through its canal system by means of pumping units (Choanocytes, Cs, in Choanocyte chambers, CCs...
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Hydrodynamics of the leucon sponge pump.
Journal of the Royal Society Interface, 2019Co-Authors: Seyed Saeed Asadzadeh, Poul Scheel Larsen, Hans Ulrik Riisgård, Jens Honore WaltherAbstract:Leuconoid sponges are filter-feeders with a complex system of branching inhalant and exhalant canals leading to and from the close-packed Choanocyte chambers. Each of these Choanocyte chambers hold...
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The Sponge Pump
Journal of Theoretical Biology, 1994Co-Authors: Poul Scheel Larsen, Hans Ulrik RiisgårdAbstract:Abstract The sponge pump was analysed and compared with the choanoflagellate pump in order to identify prerequisite properties of the basic pump units which have enabled the development of large sponges. The comparative pump analysis was based on experimentally measured back-pressure pumping-rate characteristics of the demosponge Haliclona urceolus and on mathematical-hydraulic modelling. A curved characteristic was found for H. urceolus , and the maximal pressure rise (at zero flow) which could be delivered by the sponge was about 2·4 mm H 2 O. First, to unveil the pumping principle and to propose a pump model for sponges a free living choanoflagellate ( Monosiga ) was considered as representative of a sponge-Choanocyte because the two cell types are structurally and functionally identical: a flagellum pumps water through a collar of microvilli acting as a filter. Knowing the flagellum length, beat frequency, wavelength and amplitude the pump head of the choanoflagellate was estimated to be 0·076 mm H 2 O. Because this pump head is insufficient to handle the pressure drop in a sponge is was instead suggested that the closely spaced flagella in the Choanocyte chambers of sponges, possibly confined as a bundle by the apopyle, might all together act as a peristaltic pump being able to create the necessary pump pressure to overcome the resistance in the extensive canal system. It is argued that the basic pump units in a "standard" demosponge are the Choanocyte chambers, constituting 30-50% of the wall structure separating inhalant and exhalant canals, and further, that all pump units operate in parallel and at essentially the same flow and pressure rise. Finally, a comparison between choanoflagellates and Choanocytes is made in order to draw attention to evolutionary aspects of the sponge pump.
Brittany E. Alexander - One of the best experts on this subject based on the ideXlab platform.
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Difference in the percentage proliferation in Choanocytes and mesohyl cells
2016Co-Authors: Brittany E. Alexander, Ronald Osinga, Harm G. Van Der Geest, Jack P.m. Cleutjens, Bert Schutte, Kevin Liebrand, Wim Admiraal, Fons Verheyen, Marta Ribes, Emiel Van LoonAbstract:Percentage of proliferating Choanocyte and mesohyl cells per individual and per specie
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Cell kinetics during regeneration in the sponge Halisarca caerulea: how local is the response to tissue damage?
PeerJ, 2015Co-Authors: Brittany E. Alexander, Michelle Achlatis, Ronald Osinga, Harm G. Van Der Geest, Jack P.m. Cleutjens, Bert Schutte, Jasper M. De GoeijAbstract:Sponges have a remarkable capacity to rapidly regenerate in response to wound infliction. In addition, sponges rapidly renew their filter systems (Choanocytes) to maintain a healthy population of cells. This study describes the cell kinetics of Choanocytes in the encrusting reef sponge Halisarca caerulea during early regeneration (0-8 h) following experimental wound infliction. Subsequently, we investigated the spatial relationship between regeneration and cell proliferation over a six-day period directly adjacent to the wound, 1 cm, and 3 cm from the wound. Cell proliferation was determined by the incorporation of 5-bromo-2'-deoxyuridine (BrdU). We demonstrate that during early regeneration, the growth fraction of the Choanocytes (i.e., the percentage of proliferative cells) adjacent to the wound is reduced (7.0 ± 2.5%) compared to steady-state, undamaged tissue (46.6 ± 2.6%), while the length of the cell cycle remained short (5.6 ± 3.4 h). The percentage of proliferative Choanocytes increased over time in all areas and after six days of regeneration Choanocyte proliferation rates were comparable to steady-state tissue. Tissue areas farther from the wound had higher rates of Choanocyte proliferation than areas closer to the wound, indicating that more resources are demanded from tissue in the immediate vicinity of the wound. There was no difference in the number of proliferative mesohyl cells in regenerative sponges compared to steady-state sponges. Our data suggest that the production of collagen-rich wound tissue is a key process in tissue regeneration for H. caerulea, and helps to rapidly occupy the bare substratum exposed by the wound. Regeneration and Choanocyte renewal are competing and negatively correlated life-history traits, both essential to the survival of sponges. The efficient allocation of limited resources to these life-history traits has enabled the ecological success and diversification of sponges.
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Cell Turnover and Detritus Production in Marine Sponges from Tropical and Temperate Benthic Ecosystems
PLOS ONE, 2014Co-Authors: Brittany E. Alexander, Ronald Osinga, Jack P.m. Cleutjens, Bert Schutte, Kevin Liebrand, Wim Admiraal, Fons Verheyen, Marta Ribes, Harm G. Van Der Geest, E. Emiel Van LoonAbstract:This study describes in vivo cell turnover (the balance between cell proliferation and cell loss) in eight marine sponge species from tropical coral reef, mangrove and temperate Mediterranean reef ecosystems. Cell proliferation was determined through the incorporation of 5-bromo-2′-deoxyuridine (BrdU) and measuring the percentage of BrdU-positive cells after 6 h of continuous labeling (10 h for Chondrosia reniformis). Apoptosis was identified using an antibody against active caspase-3. Cell loss through shedding was studied quantitatively by collecting and weighing sponge-expelled detritus and qualitatively by light microscopy of sponge tissue and detritus. All species investigated displayed substantial cell proliferation, predominantly in the choanoderm, but also in the mesohyl. The majority of coral reef species (five) showed between 16.1±15.9% and 19.0±2.0% Choanocyte proliferation (mean±SD) after 6 h and the Mediterranean species, C. reniformis, showed 16.6±3.2% after 10 h BrdU-labeling. Monanchora arbuscula showed lower Choanocyte proliferation (8.1±3.7%), whereas the mangrove species Mycale microsigmatosa showed relatively higher levels of Choanocyte proliferation (70.5±6.6%). Choanocyte proliferation in Haliclona vansoesti was variable (2.8–73.1%). Apoptosis was negligible and not the primary mechanism of cell loss involved in cell turnover. All species investigated produced significant amounts of detritus (2.5–18% detritus bodyweight−1·d−1) and cell shedding was observed in seven out of eight species. The amount of shed cells observed in histological sections may be related to differences in residence time of detritus within canals. Detritus production could not be directly linked to cell shedding due to the degraded nature of expelled cellular debris. We have demonstrated that under steady-state conditions, cell turnover through cell proliferation and cell shedding are common processes to maintain tissue homeostasis in a variety of sponge species from different ecosystems. Cell turnover is hypothesized to be the main underlying mechanism producing sponge-derived detritus, a major trophic resource transferred through sponges in benthic ecosystems, such as coral reefs.
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Cell proliferation and cell loss in a selection of four sponge species.
2014Co-Authors: Brittany E. Alexander, Ronald Osinga, Harm G. Van Der Geest, Jack P.m. Cleutjens, Bert Schutte, Kevin Liebrand, Wim Admiraal, Fons Verheyen, Marta Ribes, Emiel Van LoonAbstract:Sponge species from three benthic ecosystems; tropical coral reef, temperate Mediterranean reef, and mangroves. (A) In situ (H. caerulea, C. reniformis and M. microsigmatosa) and ex situ (C. caribensis) photographs of test species. (B) BrdU-positive Choanocytes (arrows) and mesohyl cells (arrowheads) of sponges BrdU-labeled for 6 h (10 h for C. reniformis) in vivo as a measure for proliferation. Areas of non-specific BrdU-labeling are occasionally seen in the cytoplasm of cells or extracellularly. (C) High amounts of cell shedding (Sh) in the lumen of excurrent canals (Ca) in specimens of H. caerulea, C. caribensis and C. reniformis sampled in situ. Choanocyte chambers (Ch), oscula (Os), the mesohyl (Me) and pinacoderm (Pi) are shown. Minor amounts of cell shedding (arrows) in the tropical mangrove sponge M. microsigmatosa sampled in situ. (D) Active caspase-3 activity of in vivo tissue was found in cells located in the mesohyl (arrows) resembling spherulous cells and, occasionally, archeocytes.