0000000000007830
AUTHOR
Renate Steffen
Silica as a morphogenetically active inorganic polymer.
At present the scaffolds used for bioprinting of cells do not elicit morphogenetic responses in the cells. In the present study we approached a solution by studying the effect of an inorganic silica supplement added to an Na-alginate matrix. Bone- and osteoblast-like SaOS-2 cells were embedded into this organic polymeric matrix which was additionally enriched with 400 μM prehydrolyzed TEOS [tetra-ethoxy-silane], a source of ortho-silicate. In this silica-based matrix the cells synthesized hydroxyapatite crystallites after exposure to a mineralization activation cocktail composed of β-glycerophosphate, ascorbic acid and dexamethasone. The degree of hydroxyapatite synthesis, determined by sta…
Differential in vitro Anti-HIV Activity of Natural Lignans
Abstract Two naturally occurring lignanolides, isolated from the tropical climbing shrub Ipomoea cairica, (-)-arctigen in and (-)-trachelogen in , were found to inhibit strongly replication of human immunodeficiency virus type 1 (HIV-1; strain HTLV-III B) in vitro. At a concentration of 0.5 (μм , (-)-arctigenin and (-)-trachelogenin inhibited the expression of HIV-1 proteins p 17 and p24 by 80 -90 % and 60 -70 % , respectively. The reverse transcriptase activity in the culture fluids was reduced by 80 -90 % when the cells (HTLV-III B/H 9) were cultivated in the presence of 0.5 μм (-)-arctigen in or 1 μм (-)-trachelogenin . At the same concentrations, the formation of syncytia in the HTLV-I…
Possible control mechanism of cell motility in the gorgonian Eunicella cavolinii
In a previous study it was demonstrated that a lectin controls cell-cell interaction in the gorgonian Eunicella cavolinii (Koch) as a negative modulator. Now we describe the procedure to purify this lectin to homogeneity; its molecular weight is 23 400. The homologous proteoglycans were identified as positive modulators of cell-cell (and/or cell substrate) interaction. The purified single proteoglycan aggregates were 1200±700 nm long and the distance between the attachment points of the proteoglycan subunits was about 45 nm. The glycosaminoglycan residues of the gorgonian proteoglycans were identified as hyaluronic acid (35.5%), heparan sulfate (47.9%) and dermatan sulfate (14.1%). Binding …
Neuroactive compounds produced by bacteria from the marine sponge Halichondria panicea: activation of the neuronal NMDA receptor
Abstract Previous studies revealed that the marine sponge Halichondria panicea habors symbiotic- and commensalic bacteria ( Althoff et al., 1998 . Marine Biol. 130, 529–536). In the present study the hypothesis was tested whether some of those bacteria synthesize neuroactive compounds. For the first time the effect of bacterial bioactive compounds on the neuronal ionotropic glutamate receptors [iGluR], subtype N -methyl- d -aspartate (NMDA) receptor, was checked. In cortical neurons from rats as cell system the supernatant of two bacterial cultures isolated from H. panicea proved to agonize the NMDA receptor. The response of the NMDA receptor to the bioactive compounds was determined by mea…
Formation of spicules by sclerocytes from the freshwater spongeEphydatia muelleri in short-term cultures in vitro
Cells from the freshwater sponge Ephydatia muelleri were isolated by dissociating hatching gemmules. During the first 24 h the cells reaggregated, but the aggregates progressively disintegrated again to single cells, among which the spicule-forming sclerocytes were recognized. Such cultures were used to study spicule (megascleres) formation in vitro. The isolated sclerocytes formed the organic central axial filament onto which they deposited inorganic silicon. The size of the spicules (200 to 350 microns in length) as well as the rate of spicule formation (1 to 10 microns/h) under in vitro conditions were similar to the values measured in vivo. Immediately after completion of spicule format…
Evidence for a symbiosis between bacteria of the genus Rhodobacter and the marine sponge Halichondria panicea : harbor also for putatively toxic bacteria?
Halichondria panicea (Pallas) is a marine sponge, abundantly occurring in the Adriatic sea, North sea and Baltic sea. It was the aim of the present study to investigate if this sponge species harbors bacteria. Cross sections through H. panicea were taken and inspected by electron microscopy. The micrographs showed that this sponge species is colonized by bacteria in its mesohyl compartment. To identify the bacteria, polymerase chain reaction (PCR) analysis of the 16S rRNA gene segment, typical for bacteria, was performed. DNA was isolated from sponge material that had been collected near Rovinj (Adriatic Sea), Helgoland (North Sea), and Kiel (Baltic Sea) and was amplified with bacterial pri…
A galectin links the aggregation factor to cells in the sponge (Geodia cydonium) system.
The cDNA for the full-length lectin from the marine sponge Geodia cydonium was cloned. Analysis of the deduced aa sequence revealed that this lectin belongs to the group of galectins. The full-length galectin, which was obtained also in a recombinant form, has an M(r) of 20,877; in the processed form it is a 15 kDa polypeptide. The enriched aggregation factor from G.cydonium also was determined to contain, besides minimal amounts of the galectin, a 140 kDa polypeptide which is involved in cell-cell adhesion. Monoclonal antibodies have been raised against this protein; Fab' fragments prepared from them abolished cell-cell reaggregation. Cell reaggregation experiments revealed that the aggreg…
Regulation of motility of cells from marine sponges by calcium ions
Sponges are known not to contain muscle and nerve cells. Since sponge cells are characterized by high motility we determined the effect of intracellular calcium ion concentration ([Ca2+]i) on their motility. Addition of the Ca2+ ionophore ionomycin to dissociated cells from the marine sponge Suberites domuncula caused in Ca(2+)-containing artificial seawater (ASW) an increase in motility from 0.2 micron/min (absence of the ionophore) to 3.7 microns/min (presence of ionomycin). When the experiments were performed in Ca(2+)-free medium, no effect of ionomycin could be observed. In parallel experiments the changes of [Ca2+]i using the dye Fura-2 were measured. The experiments revealed that ion…
Synthesis of the neurotoxin quinolinic acid in apoptotic tissue from Suberites domuncula: cell biological, molecular biological and chemical analyses
Sessile marine animals, such as sponges, are prone to infection by prokaryotic as well as by eukaryotic attacking organisms. In the present study we document for the first time that in tissue from sponges which underwent apoptosis, a toxic compound is produced which very likely controls the elimination of the dying tissue. The marine sponge Suberites domuncula develops in the field occasionally apoptotic tissue areas which are rapidly eliminated. In the present study apoptosis was induced in S. domuncula by exposing the specimens in aquaria to 5 µg/ml Dip or by maintaining the sponges for 3 - 5 days under non-aeration conditions. After that treatment only one eukaryotic epibiont, the mollus…
Sponges (Porifera) model systems to study the shift from immortal to senescent somatic cells: the telomerase activity in somatic cells.
Abstract Sponges (Porifera) represent the lowest metazoan phylum, characterized by a pronounced plasticity in the determination of cell lineages. In a first approach to elucidate the molecular mechanisms controlling the switch from the cell lineage with a putative indefinite growth capacity to senescent, somatic cells, the activity of the telomerase as an indicator for immortality has been determined. The studies were performed with the marine demosponges Suberites domuncula and Geodia cydonium . It was found that the activity for the telomerase in the tissue of both sponges is high; a quantitative analysis revealed that the extract from S. domuncula contained 10.3 TPG units per 5000 cell e…
Histocompatibility reaction in tissue and cells of the marine sponge Suberites domuncula in vitro and in vivo: central role of the allograft inflammatory factor 1
Sponges (Porifera) are the phylogenetically oldest still extant metazoan phylum. Recently elements of their immune system have been cloned and analyzed, primarily from the demosponges Suberites domuncula and Geodia cydonium. By differential display, two genes were identified in S. domuncula, whose translation products are involved in graft rejection/fusion: the allograft inflammatory factor (AIF-1) and the Tcf-like transcription factor (TCF). Since the AIF-1 and TCF genes are upregulated in vivo after tissue transplantation, especially in allografts, we investigated whether this reaction can be monitored in vitro. Therefore, the autogeneic and the allogeneic mixed sponge cell reaction (MSCR…
The multixenobiotic resistance mechanism in the marine sponge Suberites domuncula: its potential applicability for the evaluation of environmental pollution by toxic compounds
Experiments were carried out with the marine sponge Suberites domuncala to determine whether sponges may express - like mammalian tumor cells a multidrug-like transporter system. The results demonstrate that sponge cells possess such a protective system termed multixenobiotic resistance (MXR) pump or P-glycoprotein-like pump, The protein was identified by antisera for the mammalian P170 multidrug resistance protein as a 130 kDa molecule, Binding studies were performed with H-3-vincristine (H-3-VCR) and membrane vesicles ; this process is ATP-dependent and inhibited by verapamil, which is known to reverse the multidrug-resistance phenotype in mammalian systems, Accumulation experiments were …
Increased Expression of Integrin and Receptor Tyrosine Kinase Genes During Autograft Fusion in the SpongeGeodia cydonium
Recently cDNAs coding for cell surface molecules have been isolated from sponges. The molecules for alpha-integrin, galectin, and receptor tyrosine kinase (RTK), obtained from the marine sponge, Geodia cydonium, have been described earlier. In the present study also the cDNA for one putative beta-integrin has been identified from G. cydonium. The deduced aa sequence comprises the characteristic signatures, found in other metazoan beta-integrin molecules; the estimated size is 95,215 Da. To obtain first insights into the molecular events which proceed during autograft fusion, the expressions of these genes were determined on transcriptional and translational level. The cDNAs as well as antib…
Primmorphs generated from dissociated cells of the sponge Suberites domuncula: a model system for studies of cell proliferation and cell death
Sponges (Porifera) represent the lowest metazoan phylum; they have been shown to be provided with the characteristic metazoan structural and functional molecules. One autapomorphic character of sponges is the presence of high levels of telomerase activity in all cells (or almost all cells, including somatic cells). In spite of this fact previous attempts to cultivate sponge cells remained unsuccessful. It was found that dissociated sponge cells do not replicate DNA and lose their telomerase activity. In addition, no nutrients or metabolites have been detected that would stimulate sponge cells to divide. In the present study we report the culture conditions required for the formation of mult…
17β-Estradiol-dependent regulation of chaperone expression and telomerase activity in the marine sponge Geodia cydonium
It is known that species belonging to the lowest metazoan phylum, the Porifera (sponges), do not develop tumors. Sponge cells share with tumor cells of higher animals at least one characteristic; they contain high levels of telomerase activity, suggesting that they possess a high proliferation capacity. This assumption, however, has not been substantiated experimentally. In addition, sponges show a specific bauplan, leading us to postulate that they undergo apoptosis to replace a given set of cells at a given time. In the present study, 17β-estradiol (βE2) was used as a defined agent to assess its effect on both the telomerase activity and the process of apoptosis in the marine sponge Geodi…
Cultivation of primmorphs from the marine sponge Suberites domuncula: morphogenetic potential of silicon and iron.
Abstract Marine demosponges (phylum Porifera) are rich sources for potent bioactive compounds. With the establishment of the primmorph system from sponges, especially from Suberites domuncula , the technology to cultivate sponge cells in vitro improved considerably. This progress was possible after the elucidation that sponges are provided with characteristic metazoan cell adhesion receptors and extracellular matrix molecules which allow their cells a positioning in a complex organization pattern. This review summarizes recent data on the cultivation of sponges in aquaria and—with main emphasis—of primmorphs in vitro. It is outlined that silicon and Fe(+++) contribute substantially to the f…
Molecular response of the sponge Suberites domuncula to bacterial infection
The aim of this study was the documentation of the molecular immune response of Suberites domuncula upon bacterial infection. Additionally, the bacteria that are naturally present in the sponge after prolonged aquarium maintenance were characterized. After 6 months of maintenance of S. domuncula in seawater aquaria, only one bacterial 16S rDNA sequence could be recovered, which belongs to the genus Pseudomonas. Concomitantly, morphologically uniform bacteria were found encapsulated in bacteriocytes. These findings indicate that certain bacteria, possibly of the genus Pseudomonas, are able to persist for long periods in host bacteriocytes. Subsequent to performing a previously established in…
Rebalancing β-Amyloid-Induced Decrease of ATP Level by Amorphous Nano/Micro Polyphosphate: Suppression of the Neurotoxic Effect of Amyloid β-Protein Fragment 25-35
Morbus Alzheimer neuropathology is characterized by an impaired energy homeostasis of brain tissue. We present an approach towards a potential therapy of Alzheimer disease based on the high-energy polymer inorganic polyphosphate (polyP), which physiologically occurs both in the extracellular and in the intracellular space. Rat pheochromocytoma (PC) 12 cells, as well as rat primary cortical neurons were exposed to the Alzheimer peptide Aβ25-35. They were incubated in vitro with polyphosphate (polyP); ortho-phosphate was used as a control. The polymer remained as Na+ salt; or complexed in a stoichiometric ratio to Ca2+ (Na-polyP[Ca2+]); or was processed as amorphous Ca-polyP microparticles (C…
Sarcophytolide: a new neuroprotective compound from the soft coral Sarcophyton glaucum
Abstract Bioactivity-guided fractionation of an alcohol extract of the soft coral Sarcophyton glaucum collected from the intertidal areas and the fringing coral reefs near Hurghada, Red Sea, Egypt resulted in the isolation of a new lactone cembrane diterpene, sarcophytolide. The structure of this compound was deduced from its spectroscopic data and by comparison of the spectral data with those of known closely related cembrane-type compounds. In antimicrobial assays, the isolated compound exhibited a good activity towards Staphylococcus aureus, Pseudomonas aeruginosa , and Saccharomyces cerevisiae. Sarcophytolide was found to display a strong cytoprotective effect against glutamate-induced …
Engineering a morphogenetically active hydrogel for bioprinting of bioartificial tissue derived from human osteoblast-like SaOS-2 cells.
Abstract Sodium alginate hydrogel, stabilized with gelatin, is a suitable, biologically inert matrix that can be used for encapsulating and 3D bioprinting of bone-related SaOS-2 cells. However, the cells, embedded in this matrix, remain in a non-proliferating state. Here we show that addition of an overlay onto the bioprinted alginate/gelatine/SaOS-2 cell scaffold, consisting of agarose and the calcium salt of polyphosphate [polyP·Ca 2+ -complex], resulted in a marked increase in cell proliferation . In the presence of 100 μ m polyP·Ca2+ -complex, the cells proliferate with a generation time of approximately 47–55 h. In addition, the hardness of the alginate/gelatin hydrogel substantially i…
Cloning and expression of new receptors belonging to the immunoglobulin superfamily from the marine sponge Geodia cydonium
A cDNA encoding a receptor tyrosine kinase (RTK) was previously cloned and expressed from the marine sponge (Porifera) Geodia cydonium. In addition to the two intracellular regions characteristic for RTKs, two immunoglobulin (Ig)-like domains are found in the extracellular part of the sponge RTK. In the present study it is shown that no further Ig-like domain is present in the upstream region of the cDNA as well as of the gene hitherto known from the sponge RTK. Two different full-length cDNAs have been isolated and characterized in the present study, which possess two Ig-like domains, one transmembrane segment, and only a short intracellular part, without a TK domain. The two deduced polyp…
Osteogenic potential of a biosilica-coated P(UDMA-co-MPS) copolymer
A P(UDMA-co-MPS) copolymer was surface-functionalized through the polycondensation activity of the enzyme silicatein. The resulting biosilica coating significantly enhanced mineralization of osteoblastic cells, thereby revealing its osteogenic potential. Consequently, the functionalized copolymer may be explored as an alternative to conventionally used acrylics in applications where stable bone-material interfaces are required.
Cell adhesion molecule in the hexactinellid Aphrocallistes vastus
Abstract The Hexactinellida sponge Aphrocallistes vastus contains a soluble aggregation factor (AF) whose purification has been described in this communication. It is characterized by a S° 20.w value of 37 and a buoyant density of 1.45 g/cm 3 . The AF is a glycoporteinaceous particle composed of three major protein species; no core structure could be visualized. In the presence of Ca 2+ , the AF causes secondary aggregation of single cells. The aggregation process is temperature, pH, and ionic strength independent within a broad range. Evidence is presented indicating that two (or more) AF molecules are required for the establishment of a stable cell: cell interaction. In contrast to the AF…
Genome size and chromosomes in marine sponges [Suberites domuncula, Geodia cydonium]
The genome size of the marine sponges Suberites domuncula and Geodia cydonium has been determined by flow cytofluorometric analysis using diamidino-phenylindole [DAPI]. Using human lymphocytes as reference the amount of DNA in cells from S. domuncula has been determined to be 3.7 pg and that of G. cydonium 3.3 pg. While no chromosomes could be identified in G. cydonium, the karyotype of the Suberites domuncula is 32 chromosomes in the diploid state. The size of the chromosomes was between 0.25 and 1.0 micron. No pronounced banding pattern was visible.
Apoptosis in marine sponges: a biomarker for environmental stress (cadmium and bacteria)
The marine demosponge Suberites domuncula is abundantly present on muddy sand bottoms, both in the open sea and in harbors. In the present study it is shown that exposure of S. domuncula to cadmium (CdCl2) in concentrations ranging from 0.01 to 5.0 g ml−1 for up to 5 d results in apoptotic fragmentation of DNA. Kinetics experiments revealed that after 24 h a significant increase of DNA fragmentation already occurred. Besides cadmium a second stimulus was identified to also cause apoptosis in this species, namely exposure to heat-treated Escherichia coli. In order to support the finding that both cadmium and E. coli induce apoptosis in the sponge, expression of the apoptotic gene MA-3 was st…
Okadaic Acid, an Apoptogenic Toxin for Symbiotic/Parasitic Annelids in the Demosponge Suberites domuncula
ABSTRACT The role of okadaic acid (OA) in the defense system of the marine demosponge Suberites domuncula against symbiotic/parasitic annelids was examined. Bacteria within the mesohyl produced okadaic acid at concentrations between 32 ng/g and 58 ng/g of tissue (wet weight). By immunocytochemical methods and by use of antibodies against OA, we showed that the toxin was intracellularly stored in vesicles. Western blotting experiments demonstrated that OA also existed bound to a protein with a molecular weight of 35,000 which was tentatively identified as a galectin (by application of antigalectin antibodies). Annelids that are found in S. domuncula undergo apoptotic cell death. OA is one ca…
Suppression of allograft rejection in the sponge Suberites domuncula by FK506 and expression of genes encoding FK506-binding proteins in allografts.
SUMMARY Porifera (sponges) are, evolutionarily, the oldest metazoan phylum. Recent molecular data suggest that these animals possess molecules similar to and homologous with those of the innate and adaptive immune systems of higher Metazoa. Applying the biological system of parabiosis and the technique of differential display of mRNA, two cDNAs encoding putative FK506-binding proteins were isolated. FK506 is successfully used in clinics as a drug to prevent allograft rejection and is toxic to Suberites domuncula cells in vitro at doses above 100ng ml−1. Autograft fusion of transplants from S. domuncula was not affected by FK506. Allograft non-fusion was not affected by FK506 at toxic doses;…
3D printing of hybrid biomaterials for bone tissue engineering: Calcium-polyphosphate microparticles encapsulated by polycaprolactone.
Abstract Here we describe the formulation of a morphogenetically active bio-ink consisting of amorphous microparticles (MP) prepared from Ca 2+ and the physiological inorganic polymer, polyphosphate (polyP). Those MP had been fortified by mixing with poly-e-caprolactone (PCL) to allow 3D-bioprinting. The resulting granular PCL/Ca-polyP-MP hybrid material, liquefied by short-time heating to 100 °C, was used for the 3D-printing of tissue-like scaffolds formed by strands with a thickness of 400 µm and a stacked architecture leaving ≈0.5 mm 2 -sized open holes enabling cell migration. The printed composite scaffold turned out to combine suitable biomechanical properties (Young’s modulus of 1.60…
Molecular Mechanism of Spicule Formation in the Demosponge Suberites domuncula: Silicatein-Collagen-Myotrophin
In living organisms four major groups of biominerals exist: (1) iron compounds, which are restricted primarily to Prokaryota; (2) calcium phosphates, found in Metazoa; (3) calcium carbonates, used by Prokaryota, Protozoa, Plantae, Fungi and Metazoa and (4) silica (opal) present in sponges and diatoms (reviewed in: Bengtson 1994; Baeuerlein 2000). It is surprising that the occurrence of silica as a major skeletal element is restricted to some Protozoa and to sponges (Porifera). The element silicon (Si) contributes to 28% of the earth crust and is - after oxygen - the second most abundant element on earth (Windholz 1983).
Alterations of Activities of Ribonucleases and Polyadenylate Polymerase in Synchronized Mouse L Cells
The activities of the three known catabolic and the one anabolic polyadenylate enzymes have been determined in synchronized L5178y cells: endoribonuclease, exoribonuclease, 5'-nucleotidase and poly(A) polymerase (Mg2+-dependent). These four enzymes were found primarily in the nuclear fraction. The activity of poly(A) polymerase remains essentially constant during the transition from G1 to S phase. However, the poly(A) catabolic enzyme activities increase parallel with DNA synthesis; the endoribonuclease activity increases 4-fold during G1 to S phase, the exoribonuclease and the nucleotidase activities increasing 30-fold and 16-fold. During the S phase the poly(A)-degrading enzymes are far m…
The Marine Sponge-Derived Inorganic Polymers, Biosilica and Polyphosphate, as Morphogenetically Active Matrices/Scaffolds for the Differentiation of Human Multipotent Stromal Cells: Potential Application in 3D Printing and Distraction Osteogenesis
The two marine inorganic polymers, biosilica (BS), enzymatically synthesized from ortho-silicate, and polyphosphate (polyP), a likewise enzymatically synthesized polymer consisting of 10 to >100 phosphate residues linked by high-energy phosphoanhydride bonds, have previously been shown to display a morphogenetic effect on osteoblasts. In the present study, the effect of these polymers on the differential differentiation of human multipotent stromal cells (hMSC), mesenchymal stem cells, that had been encapsulated into beads of the biocompatible plant polymer alginate, was studied. The differentiation of the hMSCs in the alginate beads was directed either to the osteogenic cell lineage by …
Sponges (Porifera) Molecular Model Systems to Study Cellular Differentiation in Metazoa
Evolution is a gradual process whereby primarily new genes are formed either by gene duplication (Ohno 1970) or exon shuffling (Gilbert 1978). New proteins can also be produced by overlapping genes, alternative splicing or gene sharing (Li and Graur 1991). These facts imply that (1) proteins found in a given phylum contain elements or modules which are present already in ancestral protein(s) of members of phylogenetically older phyla and (2) that new combinations of such modules create proteins that possess new functions.
Ethylene modulates gene expression in cells of the marine sponge Suberites domuncula and reduces the degree of apoptosis.
Sponges (phylum Porifera) live in an aqueous milieu that contains dissolved organic carbon. This is degraded photochemically by ultraviolet radiation to alkenes, particularly to ethylene. This study demonstrates that sponge cells (here the demosponge Suberites domuncula has been used), which have assembled to primmorphs, react to 5 microM ethylene with a significant up-regulation of intracellular Ca(2+) concentration and with a reduction of starvation-induced apoptosis. In primmorphs from S. domuncula the expression of two genes is up-regulated after exposure to ethylene. The cDNA of the first gene (SDERR) isolated from S. domuncula encodes a potential ethylene-responsive protein, termed ER…
Polymorphism in the immunoglobulin-like domains of the receptor tyrosine kinase from the sponge Geodia cydonium.
Sponges [Porifera] are the phylogenetically oldest phylum of the Metazoa. They are provided with both cellular and humoral allorecognition systems. The underlying molecules are not yet known. To study allorecognition in sponges we first determined the frequency of graft rejection in a natural population of the marine sponge Geodia cydonium. We then determined, for the first time at the molecular level, the degree of sequence polymorphism in segments of one molecule which may be related to sponge allorecognition and host defense: the Ig-like domains from the receptor tyrosine kinase [RTK]. Thirty six pairs of auto- and allografts were assayed, either by parabiotic attachment or insertion of …
Application of a MTT Assay for Screening Nutritional Factors in Growth Media of Primary Sponge Cell Culture
Marine sponges (Porifera) are producers of the largest variety of bioactive compounds among benthic marine organisms. In vitro culture of marine sponge cells has been proposed for the sustainable production of these pharmacologically interesting compounds from marine sponges but with limited success. The development of a suitable growth medium is an essential prerequisite for sponge cells grown in vitro. The MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay was adapted to screen for potential nutritional factors in formulating a growth medium for primary cell culture of Suberites domuncula. In 96-well plates, the effects of nutritional factors including glutamine, pyr…
The putative sponge aggregation receptor. Isolation and characterization of a molecule composed of scavenger receptor cysteine-rich domains and short consensus repeats.
Porifera (sponges) are the oldest extant metazoan phylum. Dissociated sponge cells serve as a classic system to study processes of cell reaggregation. The reaggregation of dissociated cells is mediated by an extracellularly localized aggregation factor (AF), based on heterophilic interactions of the third order; the AF bridges two cells by ligating a cell-surface-bound aggregation receptor (AR). In the present study we report cloning, expression and immunohistochemical localization of a polypeptide from the marine sponge Geodia cydonium, which very likely represents the AR. The presumed AR gene gives rise to at least three forms of alternatively spliced transcripts of 6.5, 4.9 and 3.9 kb, a…
Iron Induces Proliferation and Morphogenesis in Primmorphs from the Marine SpongeSuberites domuncula
Dissociated cells from marine demosponges retain their proliferation capacity if they are allowed to form special aggregates, the primmorphs. On the basis of incorporation studies and septin gene expression, we show that Fe3+ ions are required for the proliferation of cells in primmorphs from Suberites domuncula. In parallel, Fe3+ induced the expression of ferritin and strongly stimulated the synthesis of spicules. This result is supported by the finding that the enzymatic activity of silicatein, converting organosilicon to silicic acid, depends on Fe3+. Moreover, the expression of a scavenger receptor molecule, possibly involved in the morphology of spicules, depends on the presence of Fe3…
Cryptochrome in Sponges: A Key Molecule Linking Photoreception with Phototransduction
Sponges (phylum: Porifera) react to external light or mechanical signals with contractile or metabolic reactions and are devoid of any nervous or muscular system. Furthermore, elements of a photoreception/phototransduction system exist in those animals. Recently, a cryptochrome-based photoreceptor system has been discovered in the demosponge. The assumption that in sponges the siliceous skeleton acts as a substitution for the lack of a nervous system and allows light signals to be transmitted through its glass fiber network is supported by the findings that the first spicules are efficient light waveguides and the second sponges have the enzymatic machinery for the generation of light. Now…