Sponge Geodia Cydonium Research Articles

Evaluating the Effects of an Organic Extract from the Mediterranean Sponge Geodia cydonium on Human Breast Cancer Cell Lines.

Marine sponges are an excellent source of bioactive secondary metabolites for pharmacological applications. In the present study, we evaluated the chemistry, cytotoxicity and metabolomics of an organic extract from the Mediterranean marine sponge Geodia cydonium, collected in coastal waters of the Gulf of Naples. We identified an active fraction able to block proliferation of breast cancer cell lines MCF-7, MDA-MB231, and MDA-MB468 and to induce cellular apoptosis, whereas it was inactive on normal breast cells (MCF-10A). Metabolomic studies showed that this active fraction was able to interfere with amino acid metabolism, as well as to modulate glycolysis and glycosphingolipid metabolic pathways. In addition, the evaluation of the cytokinome profile on the polar fractions of three treated breast cancer cell lines (compared to untreated cells) demonstrated that this fraction induced a slight anti-inflammatory effect. Finally, the chemical entities present in this fraction were analyzed by liquid chromatography high resolution mass spectrometry combined with molecular networking.

Local Ecological Knowledge Indicates Temporal Trends of Benthic Invertebrates Species of the Adriatic Sea

In the Adriatic Sea, shifts in benthic community structure have been attributed to multiple stressors, from the effects of climate change to the impacts of commercial fishing. Some fishing practices, such as bottom trawling, have caused a widespread decline in exploited fish stocks. Bottom trawling is also expected to have negative impacts on benthic habitats, usually structured by and hosting a large array of invertebrate species, which provide important ecological services to fish and commercial invertebrate stocks. However, in contrast to commercial species for which long-term time series of the abundance exist, data on these habitat-forming invertebrates are scarce, as they are usually caught as bycatch and discarded. Therefore, there is great uncertainty about their long-term trends, and if these populations are stable or declining. Here we used interview surveys conducted with bottom-trawling fishers of the central Adriatic Sea to gather local ecological knowledge on megabenthos abundance occurring in their fishing domain, as an alternative source of information to conventional fisheries data. We interviewed 44 fishers, from the most important ports of the Marche region of Italy, to understand how megabenthic species have changed in abundance within the area since the 1980s. Specifically, we asked fishers to provide qualitative abundance scores for 18 invertebrate species in five phyla (Porifera, Cnidaria, Bryozoa, Mollusca and Echinodermata) based on their recollection of these species' presence in bycatch. We stratified responses in homogeneous temporal periods and geographic sectors of the study area, and analyzed their response with mixed effect ordered logistic regression models in order to evaluate spatiotemporal changes in the perceived abundance of each species. Our analysis suggests that the abundance of the sponge Geodia cydonium, the molluscs Pecten jacobaeus, Atrina fragilis Neopycnodonte cochlear and the group of holothurians, have declined. From fishers’ perceptions, only the bryozoan Amathia semiconvoluta has increased. Local ecological knowledge can provide important information on environmental change and can highlight species and ecosystems at risk when conventional scientific data are scarce or absent. This approach can be expanded to other regions of the Adriatic and broader Mediterranean Sea to reconstruct change of this heavily exploited marine region.

Structural insight into an evolutionarily ancient programmed cell death regulator \u2013 the crystal structure of marine sponge BHP2 bound to LB-Bak-2

Sponges of the porifera family harbor some of the evolutionary most ancient orthologs of the B-cell lymphoma-2 (Bcl-2) family, a protein family critical to regulation of apoptosis. The genome of the sponge Geodia cydonium contains the putative pro-survival Bcl-2 homolog BHP2, which protects sponge tissue as well as mammalian Hek-293 and NIH-3T3 cells against diverse apoptotic stimuli. The Lake Baikal demosponge Lubomirskia baicalensis has been shown to encode both putative pro-survival Bcl-2 (LB-Bcl-2) and pro-apoptotic Bcl-2 members (LB-Bak-2), which have been implied in axis formation (branches) in L. baicalensis. However, the molecular mechanism of action of sponge-encoded orthologs of Bcl-2 remains to be clarified. Here, we report that the pro-survival Bcl-2 ortholog BHP2 from G. cydonium is able to bind the BH3 motif of a pro-apoptotic Bcl-2 protein, LB-Bak-2 of the sponge L. baicalensis. Furthermore, we determined the crystal structure of BHP2 bound to LB-Bak-2, which revealed that using a binding groove conserved across all pro-survival Bcl-2 proteins, BHP2 binds multi-motif Bax-like proteins through their BH3-binding regions. However, BHP2 discriminates against BH3-only bearing proteins by blocking access to a hydrophobic pocket that is critical for BH3 motif binding in pro-survival Bcl-2 proteins from higher organisms. This differential binding mode is reflected in a structure-based phylogenetic comparison of BHP2 with other Bcl-2 family members, which revealed that BHP2 does not cluster with either Bcl-2 members of higher organisms or pathogen-encoded homologs, and assumes a discrete position. Our findings suggest that the molecular machinery and mechanisms for executing Bcl-2-mediated apoptosis as observed in mammals are evolutionary ancient, with early regulation of apoptotic machineries closely resembling their modern counterparts in mammals rather than Caenorhabditis elegans or drosophila.

The first assessment of marine debris in a Site of Community Importance in the north-western Adriatic Sea (Mediterranean Sea)

At present, few studies have investigated the marine litter abundance, composition and distribution on rocky bottoms due to sampling constraints. We surveyed by means of the ROV imaging technique a system of biogenic rocky outcrops classified as a Site of Community Importance in the Adriatic Sea. A mean density of 3.3 (±1.8) items/100m2 was recorded, with a strong dominance of fishing- and aquaculture-related debris, accounting for 69.4% and 18.9% of the total, respectively. The abundance of litter over the rocky bottoms was significantly higher than that on soft substrates, and its spatial distribution proved to be related to hydrographic factors. Litter-fauna interactions were high, with most of the debris (65.7%) entangling or covering benthic organisms, in particular habitat constructors such as the endangered sea sponge Geodia cydonium. Unless appropriate measures are undertaken to address this problem, the abundance of marine litter in the area is likely to increase.

A novel interdomain interface in crystallins: structural characterization of the βγ-crystallin fromGeodia cydoniumat 0.99 Å resolution

The βγ-crystallin superfamily includes highly diverse proteins belonging to all of the kingdoms of life. Based on structural topology, these proteins are considered to be evolutionarily related to the long-lived βγ-crystallins that constitute the vertebrate eye lens. This study reports the crystallographic structure at 0.99 Å resolution of the two-domain βγ-crystallin (geodin) from the sponge Geodia cydonium. This is the most ancient member of the βγ-crystallin superfamily in metazoans. The X-ray structure shows that the geodin domains adopt the typical βγ-crystallin fold with a paired Greek-key motif, thus confirming the hypothesis that the crystallin-type scaffold used in the evolution of bacteria and moulds was recruited very early in metazoans. As a significant new structural feature, the sponge protein possesses a unique interdomain interface made up by pairing between the second motif of the first domain and the first motif of the second domain. The atomic resolution also allowed a detailed analysis of the calcium-binding site of the protein.

Arthrinins A–D: Novel diterpenoids and further constituents from the sponge derived fungus Arthrinium sp.

Bioassay-guided fractionation of a methanolic extract of the fungus Arthrinium sp., isolated from the Mediterranean sponge Geodia cydonium, afforded 10 natural products including five new diterpenoids, arthrinins A–D ( 1– 4) and myrocin D ( 5). In addition, five known compounds were obtained, which included myrocin A ( 6), norlichexanthone ( 7), anomalin A ( 8), decarboxycitrinone ( 9) and 2,5-dimethyl-7-hydroxychromone ( 10). The structures of all isolated compounds were unambiguously elucidated based on extensive 1D and 2D NMR and HR-MS analyzes. The absolute configuration of arthrinins A–D ( 1– 4) was established by the convenient Mosher method performed in NMR tubes and by interpretation of the ROESY spectra. Antiproliferative activity of the isolated compounds was assessed in vitro against four different tumor cell lines, including mouse lymphoma (L5178Y), human chronic myelogenous leukemia (K562), human ovarian cancer (A2780) and cisplatin-resistant ovarian cancer cells (A2780CisR), using the MTT assay. Norlichexanthone ( 7) and anomalin A ( 8) exhibited the strongest activities with IC 50 values ranging from 0.40 to 74.0 μM depending on the cell line investigated. This was paralleled by the inhibitory activity of both compounds against 16 cancer related protein kinases including aurora-B, PIM1, and VEGF-R2. In vitro IC 50 values of 7 and 8 against these three protein kinases ranged from 0.3 to 11.7 μM. Further investigation of the potential antitumoral activity of compounds 5– 8 was performed in an in vitro angiogenesis assay against human umbilical vascular endothelial cells (HUVEC) sprouting induced by vascular endothelial growth factor A (VEGF-A). Anomalin A ( 8), myrocin D ( 5) and myrocin A ( 6) inhibited VEGF-A dependent endothelial cell sprouting with IC 50 values of 1.8, 2.6 and 3.7 μM, respectively, whereas norlichexanthone ( 7) was inactive.

Cloning of sponge heat shock proteins: evolutionary relationships between the major kingdoms

In the present study we have cloned from sponges (Porifera) those molecules which are involved in the protection of organisms against physiological and stress conditions; the inducible heat shock protein Mr 70,000, hsp70, from the marine sponge Geodia cydonium, its interacting hsp40, a DnaJ-like protein (from G. cydonium) and the constitutively expressed counterpart the glucose-regulated protein Mr 78,000, GRP78 from Suberites domuncula. Alignments of the sequences revealed that the deduced aa sequences of all sponge hsp's share high homology to other metazoan sequences, and are separated from related sequences from plants and fungi (hsp70, GRP78, DnaJ) as well as Bacteria (DnaK, the hsp70 homologoue and the DnaJ) and Archaea (DnaK, the hsp70 homologoue and the DnaJ). One comparison based on nt sequences (hsp70/DnaK) showed a less pronounced grouping. From these data we conclude, that for phylogenetic analyses of deep branches in the metazoan evolution, not only ‘characteristic’metazoan genes, but also ‘housekeeping genes’e.g. are suitable for evolutionary inference. The sequences reported here have been submitted to the EMBL/GenBank data base (accession no. GCDNAJ Y09037, GCHSP70 X94985, SDGR78 Y09500).

Sponge OAS has a distinct genomic structure within the 2-5A synthetase family

2',5'-Oligoadenylate synthetases (2-5A synthetases, OAS) are enzymes that play an important role in the interferon-induced antiviral defense mechanisms in mammals. Sponges, the evolutionarily lowest multicellular animals, also possess OAS; however, their function is presently unclear. Low homology between primary structures of 2-5A synthetases from vertebrates and sponges renders their evolutionary relationship obscure. The genomic structure of vertebrate OASs has been thoroughly examined, making it possible to elucidate molecular evolution and expansion of this gene family. Until now, no OAS gene structure was available from sponges to compare it with the corresponding genes from higher organisms. In the present work, we determined the exon/intron structure of the OAS gene from the marine sponge Geodia cydonium and found it to be completely different from the strictly conserved exon/intron pattern of the OAS genes from vertebrates. This finding was corroborated by the analysis of OAS genes from another sponge, Amphimedon queenslandica, whose genome was recently sequenced. Our data suggest that vertebrate and sponge OAS genes have no direct common intron-containing ancestor and two (sub)types of OAS may be discriminated. This study opens new perspectives for understanding the phylogenesis and evolution of 2-5A synthetases as well as functional aspects of this multigene family.

Physicochemical and functional characterization of the polymerization process of the Geodia cydonium lectin.

The extracellularly localized, galactose-specific lectin from the sponge Geodia cydonium binds at one class of sites, 40 mol Ca2+/mol lectin with an association constant (Ka) of 0.3 X 10(6)M-1. Stoichiometric calculations reveal that in the extracellular milieu 22 mol Ca2+ (maximum) are complexed per mol lectin. Binding of Ca2+ to the lectin increases its apparent Mr from 44000 to 56000 (electrophoretic determination) or from 36500 to 53500 (high-pressure liquid gel chromatographical determination); the s20, w increases from 4.3 S to 4.5 S if Ca2+ is added to the lectin. In the presence of Ca2+ the lectin undergoes a conformational change perhaps by expanding the carbohydrate side chains which are terminated by galactose. Subsequently the lectin molecules polymerize to large three-dimensional clumps (diameter up to 8 micron). Turbidimetric studies reveal an inhibition of the lectin polymerization by lactose. The Ka of the lectin-lectin polymerization rises from 0.9 X 10(6)M-1 to 14.0 X 10(6)M-1 after increasing the Ca2+ concentration (from 1 microM to 100 microM). Parallel with this increase in affinity, the Ka value of the lectin-aggregation factor binding drops from 41.2 X 10(6)M-1 (1 microM Ca2+) to 1.3 X 10(6)M-1 (100 microM Ca2+). In the absence of Ca2+, the Geodia lectin forms 1-10-micron two-dimensional sheets in the presence of homologous glycoconjugates. Cell binding experiments with polyacrylamide gels, containing covalently bound galactose, show that both homologous (Geodia cydonium) and heterologous cells (L5178y) bind with a higher affinity to the lectin-polymer matrix than to the lectin-monomer one. These data suggest that lectin-polymer structures, together with lectin-glycoconjugate associates, are components of the cell-substrate adhesion system(s) of sponges in vivo.

Isolation, purification, characterization and glycan-binding profile of a d-galactoside specific lectin from the marine sponge, Halichondria okadai

A lectin recognizing both Galβ1-3GlcNAc and Galβ1-4GlcNAc was purified from the demosponge Halichondria okadai by lactosyl-agarose affinity chromatography. The molecular mass of the lectin was determined to be 30 kDa by SDS-PAGE under reducing and non-reducing conditions and 60 kDa by gel permeation chromatography. The p I value of the lectin was 6.7. It was found to agglutinate trypsinized and glutaraldehyde-fixed rabbit and human erythrocytes in the presence and absence of divalent cations. The hemagglutinating activity by the lectin was inhibited by d-galactose, methyl- d-galactopyranoside, N-acetyl- d-galactosamine, methyl- N-acetyl- d-galactosaminide, lactose, melibiose, and asialofetuin. The K d of the lectin against p-nitrophenyl-β-lactoside was determined to be 2.76 × 10 − 5 M and its glycan-binding profile given by frontal affinity chromatography was shown to be similar to many other known galectins. Partial primary structure analysis of 7 peptides by cleavage with lysyl endopeptidase indicated that one of the peptides showed significant similarity with galectin purified from the sponge Geodia cydonium.

A Combined Strategy for Glycan Profiling: a Model Study with Pyridylaminated Oligosaccharides

Structural glycomics plays a fundamental role in glycoscience and glycotechnology. In this paper, a novel strategy for the structural characterization of glycans is described, in which MS2 analysis involving a LIFT-TOF/TOF procedure is combined with frontal affinity chromatography (FAC). As model compounds, 20 neutral pyridylaminated (PA) oligosaccharides were chosen, which included four groups of structural isomers differing in sequence, linkage, position, or branching features. By depicting significant diagnostic ions on MS2, most of the analyzed oligosaccharides were successfully differentiated, while two pairs of linkage isomers, i.e., LNT/LNnT, and LNH/LNnH were not. For subsequent analysis by FAC, 14 lectins showing significant affinity to either LNT (type 1) or LNnT (type 2) were screened, and a galectin from the marine sponge Geodia cydonium (GC1) and a plant seed lectin from Ricinus communis (RCA-I) were used for determination of type 1 and 2 chains, respectively. With these specific probes, both of the isomeric pairs were unambiguously differentiated. Furthermore, a pair of triantennary, asparagine-linked oligosaccharide isomers could also be successfully differentiated. Thus, the combination of MS2 and FAC is a practical alternative for the structural characterization of complex glycans.

The Geodia cydonium galectin exhibits prototype and chimera-type characteristics and a unique sequence polymorphism within its carbohydrate recognition domain

The ancestral galectin from the sponge Geodia cydonium (GCG) is classified on a structural basis to the prototype subfamily, whereas its carbohydrate-binding specificity is related to that of the mammalian chimera-type galectin-3. This dual coordination reveals GCG as a potential precursor of the later evolved galectin subfamilies, which is reflected in the primary structure of the protein. This study provides evidence that GCG is the LECT1 gene product, while neither a previously described LECT2 gene nor a functional LECT2 gene product was found in the specimen under investigation. The electrophoretically separated protein isomers with apparent molecular masses of 13, 15, and 16 kDa correspond to variants of the LECT1 protein-exhibiting peptide sequence polymorphisms that concern critical positions of the carbohydrate recognition domain (13 kDa: Leu51, Asn55, His130, Gly137; 15 kDa: Ser51, Asn55, Asn130, Gly137; 16 kDa: Ser51, Tyr55, Asn130, Glu137). Four residues, highly conserved in the galectin family, are substituted. None of the residues claimed to be involved in interactions with GalNAcalpha1-3 moieties at an extended binding subsite of galectin-3 was identified in the corresponding positions of GCG. Apparently, the substitutions do not confer distinct binding characteristics to the GCG variants as evidenced by binding studies with a recombinantly expressed 15-kDa isoform. The natural isoforms as well as the recombinant 15-kDa isoform oligomerize by the formation of non-covalent heteromeric or homomeric complexes. A phosphorylation of the galectin was confirmed neither by mass spectrometry nor by alkaline phosphatase treatment combined with isoelectric focusing.

Sequence similarities of protein kinase substrates and inhibitors with immunoglobulins and model immunoglobulin homologue: cell adhesion molecule from the living fossil sponge Geodia cydonium. Mapping of coherent database similarities and implications for evolution of CDR1 and hypermutation.

Sequences of immunoglobulin (Ig) domains of adhesive molecule GSAMS from the living fossil sponge Geodia cydonium were compared with the important motif of peptide protein kinase substrates and inhibitors (PKSI), detail PKSI sequences, and a common template sequence, derived from structures determined previously. We found the site-restricted sequence similarities to these peptide sequences predominantly in the GSAM Ig1 domain of GSAMS in the domain region related to corresponding Ig similarities detected earlier. Additional sequence block-related analysis revealed the presence of CDR1-like segments within PKSI-related regions and resulted in the detection of increased numbers of hypermutation motifs just in the CDR1-like segment of GSAM Ig1 (GSAM(cdrl.1)). In the following database searches with PKSI-related regions and GSAM(cdr1.1) we looked for: (i) peptide similarities present in the context of Ig domains or related structures in a large range of species from Archaea to Vertebrata, and (ii) some special nucleotide similarities.

Caspase-mediated apoptosis in sponges: cloning and function of the phylogenetic oldest apoptotic proteases from Metazoa

Sponges (phylum Porifera) represent the phylogenetically oldest metazoan phylum. These animals have complex cell adhesion and powerful immune systems which allow the formation of a distinct body plan. Consequently, an apoptotic machinery has to be predicted that allows sponges to eliminate unwanted cells accumulating during development. With the marine sponge Geodia cydonium, it is shown that allografts of these animals undergo apoptosis as demonstrated by apoptotic DNA fragmentation. Extracts from allografts contain an enzymic activity characteristic for caspases; as substrate to determine the cleavage activity, Ac-DEVD-AMC was applied. cDNAs encoding predicted caspase-3-related proteins were isolated; they comprise the characteristic structure known from caspases of other metazoan phyla. The two cDNAs are assumed to originate from one gene by alternative splicing; the longer form comprises a caspase recruitment domain (CARD), whereas the shorter one is missing CARD. The expression of sponge caspase genes is up-regulated during allograft rejection. In vivo incubation experiments with Ac-DEVD-CHO (a caspase-3 inhibitor) showed a reduction of apoptotic DNA fragmentation, whereas Ac-LEHD-CHO (an inhibitor of caspase-9) caused no effect. It is concluded, that for the establishment of the metazoan body plan, both the adhesion molecules and the apoptotic molecules (described here) were essential prerequisites.

Sponge (2′,5′)oligoadenylate synthetase activity in the whole sponge organism and in a primary cell culture

A high (2′,5′)oligoadenylate (2-5A) synthetase activity was found in the marine sponge Geodia cydonium. Here we demonstrate that the 2-5A synthetase activity is present also in other sponge species although the level of the 2-5A synthetase activity varies in several magnitudes in different sponges. The 2-5A synthesizing activity was maintained in the primary culture produced from a sponge.

2′,5′-oligoadenylate synthetase from a lower invertebrate, the marine sponge Geodia cydonium, does not need dsRNA for its enzymatic activity

Recently, the presence of 2′,5′-linked oligoadenylates and a high 2′,5′-oligoadenylate synthetase activity were discovered in a lower invertebrate, the marine sponge Geodia cydonium. It has been demonstrated that mammalian 2–5A synthetase isozymes require a dsRNA cofactor for their enzymatic activity. Our results show that, unlike mammalian 2–5A synthetases, the 2–5A synthetase from the sponge acts in a dsRNA-independent manner in vitro. A prolonged incubation of the G. cydonium extract with a high concentration of a micrococcal nuclease had no effect on the activity of the 2–5A synthetase. At the same time, the micrococcal nuclease was effective within 30 min in degrading dsRNA needed for the enzymatic activity in IFN-induced PC12 cells. These results indicate that the 2–5A synthetase from G. cydonium may be active per se or is activated by some other mechanism. The sponge enzyme is capable of synthesizing a series of 2–5A oligomers ranging from dimers to octamers. The accumulation of a dimer in the predominant proportion during the first stage of the reaction was observed, followed by a gradual increase in longer oligoadenylates. By its product profile and kinetics of formation, the sponge 2–5A synthetase behaves like a specific isoform of enzymes of the 2–5A synthetase family.

Cloning and expression of the putative aggregation factor from the marine sponge Geodia cydonium.

Sponges (phylum Porifera) have extensively been used as a model system to study cell-cell interaction on molecular level. Recently, we identified and cloned the putative aggregation receptor (AR) of the sponge Geodia cydonium, which interacts in a heterophilic way with the aggregation factor (AF) complex. In the present study, antibodies against this complex have been raised that abolish the adhesion function of the enriched sponge AF, the AF-Fraction 6B. Using this antibody as a tool, a complete 1.7 kb long cDNA, GEOCYAF, could be isolated from a cDNA library that encodes the putative AF. Its deduced aa sequence in the N-terminal section comprises high similarity to amphiphysin/BIN1 sequences found in Protostomia and Deuterostomia. However, the C-terminal portion of the sponge sequence lacks the SH3 domain characteristic for amphiphysin/BIN1. The polypeptide with a calculated size of 47 kDa was expressed in Escherichia coli. The recombinant, soluble 36 kDa putative AF was prepared and found to compete with the AF complex-associated adhesion protein of the AF-Fraction 6B for the binding sites at the cell surface. Furthermore, the recombinant putative AF was recognized by the antibody used to screen the cDNA library by western blotting. In addition, there is evidence that the recombinant putative AF binds to the G. cydonium galectin. It is concluded that the putative G. cydonium AF--a further autapomorphic molecule characteristic for Metazoa--binds to the AR present on the cell surface in association with the homologous galectin.

Codon usage in the siliceous sponge Geodia cydonium: highly expressed genes in the simplest multicellular animals prefer C- and G-ending codons

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Receptor protein-tyrosine phosphatases: origin of domains (catalytic domain, Ig-related domain, fibronectin type III module) based on the sequence of the sponge Geodia cydonium

Reversible tyrosine phosphorylation of proteins is one of the major regulatory physiological events in response to cell-cell- and cell-matrix contact in Metazoa. Previously it was documented that the tyrosine phosphorylating enzymes, the tyrosine kinases (TKs), are autapomorphic characters of Metazoa, including sponges. In this paper the tyrosine dephosphorylating enzymes, the protein-tyrosine phosphatases (PTPs), are studied which can be grouped into two subfamilies, the soluble PTPs and the receptor PTPs (RPTPs). PTPs are characterized by one PTPase domain which interestingly comprises sequence similarity to yeast PTPs. In contrast to the PTPs, the RPTPs – which have been found only in Metazoa – are provided with two PTPase domains. To study the evolution of the RPTPs the full-length size RPTP was cloned from the marine demosponge Geodia cydonium, the phylogenetic oldest metazoan taxon. The 3253 bp long sequence has a putative open reading frame coding for a 999 aa long RPTP which is characterized by two fibronectin (type III; FN-III) domains in the extracellular portion, one intracellular immunoglobulin (Ig)-related domain, and two PTPase domains. Phylogenetic analysis revealed that the sponge FN-III domains form the basis of the metazoan FN-III domain with the common metazoan ancestor. The Ig-related, typical metazoan, module is classified to the disulphide lacking Ig members and represents the phylogenetic earliest member of this group. The β-sheet propensity was calculated and the characteristic amino acids are present in the seven β-sheets. The analysis of the two PTPase domains of the sponge RPTP demonstrates that the first domain is closely related to the PTPase domains present in the soluble PTPs, while the second PTPase domain is only distantly related to them. By constructing a rooted phylogenetic cladogram it became overt that the duplication of the PTPase domains must have occurred already in yeast. This interesting finding indicates that two conserved PTPase domains originated from a common ancestor in yeast while the evolutionary novelties, the FN-III domains and the Ig-related module, were added during the transition to the Metazoa. Hence, the tyrosine dephosphorylating enzyme, RPTP, is an example for a modular protein which is composed of ancient modules (PTPase domain[s]) and two metazoan novelties, while the tyrosine phosphorylating enzymes, the TKs, evolved only in Metazoa.

Epibiontic and endobiontic polychaetes of Geodia cydonium (Porifera, Demospongiae) from the Mediterranean Sea

Polychaete assemblages associated to the sponge Geodia cydonium were investigated at two sampling sites in the Mediterranean Sea: Porto Cesareo Basin (Apulia) and Marsala Lagoon (Sicily), both characterized by sheltered hydrodynamic conditions. Samples were seasonally performed during 1997, in order to compare the assemblages coming from the two localities studied, considering separately the internal and external tissues of the sponge, and with the aim of evaluating the influence of sponge size on polychaete colonization. The examined sponge is characterized by a peculiar stratification of its tissues: an external thick and hard layer, the cortex, and an internal softer one, the choanosome. Statistical analysis showed that this was the main factor controlling polychaete assemblage, with the internal tissue, less rich and diversified, appearing impoverished with respect to the external layer. A similarity in species composition was observed between sites, even though some differences were evidenced in the abundance of some species, mainly reflecting differences in local environmental conditions. Species richness and density increased with the increasing sponge size. Such a situation is particularly evident at Porto Cesareo, where sponges are covered by an algal layer which is particularly rich on the largest specimens, thus suggesting that most of the species of polychaetes were linked more to the neighbouring environment than to the sponge itself.