Molecular characterization of a nonfibrillar collagen from the marine sponge Chondrosia reniformis Nardo 1847 and positive effects of soluble silicates on its expression

Chitosan-collagen biopolymer biofilm derived from cephalopod gladius; Evaluation of osteogenesis, angiogenesis and wound healing for tissue engineering application

Chitosan (Ch) and acid-soluble collagen (ASC) from Doryteuthis singhalensis gladius were isolated to test their osteogenic, angiogenic, and wound healing capabilities in male Wistar rats. The results of the study showed that the ASC yield was 18.58 %, the total protein content was 86.43 % ± 0.18 %, and the amino acid composition was as follows: glycine, 15.68 %; proline, 13.84 %. A, B, I, II, and III show FT-IR amide regional bands at 3392, 2959, 1652, 1471, and 1237 cm-1 respectively. The electrophoretic pattern of ASC validated its molecular weights of 105 kDa and 96 kDa. The 1H NMR spectra showed pure singles at 1.99 ppm, and the UV-Vis spectrum showed a particular absorbance between 238 and 220 nm. The DSC showed two endothermic peaks: one with an To value of 119.72 °C and TP of 126.28 °C, and the other with 147.42 °C and 148.47 °C. Initially, we fabricated Ch and ASC biofilms at an 8.5:1.5 ratio for tissue engineering applications. A cellular-level study demonstrated good biocompatibility and enhanced osteoblastic differentiation of collagen chitosan films (CChF). Additionally, the biofilm exhibited increased angiogenic potency, as observed in the chick embryo chorioallantoic membrane (CAM) assay. The experimental animal model demonstrated that in wound healing, the CChF treated rats (95.75 ± 2.28 %) had a greater decrease in the diameter of the wound than the control rats (22.25 ± 2.45 %), followed by the CF (collagen film) treated rats (63.25 ± 2.08 %) and ChF (chitosan film) (52.67 ± 1.58 %). Rats treated with CChF had 48.82 ± 1.25 mg/g of hydroxyproline in NFGT and 75.25 ± 1.56 mg/g of overall protein. The higher hydroxyproline levels in the CChF-treated groups corroborated these histopathological findings. These results imply that by promoting the development of scars, inflammation, and proliferation, CChF accelerates the healing process.

The Characterization and Cytotoxic Evaluation of Chondrosia reniformis Collagen Isolated from Different Body Parts (Ectosome and Choanosome) Envisaging the Development of Biomaterials

Chondrosia reniformis is a collagen-rich marine sponge that is considered a sustainable and viable option for producing an alternative to mammalian-origin collagens. However, there is a lack of knowledge regarding the properties of collagen isolated from different sponge parts, namely the outer region, or cortex, (ectosome) and the inner region (choanosome), and how it affects the development of biomaterials. In this study, a brief histological analysis focusing on C. reniformis collagen spatial distribution and a comprehensive comparative analysis between collagen isolated from ectosome and choanosome are presented. The isolated collagen characterization was based on isolation yield, Fourier-transformed infrared spectroscopy (FTIR), circular dichroism (CD), SDS-PAGE, dot blot, and amino acid composition, as well as their cytocompatibility envisaging the development of future biomedical applications. An isolation yield of approximately 20% was similar for both sponge parts, as well as the FTIR, CD, and SDS-PAGE profiles, which demonstrated that both isolated collagens presented a high purity degree and preserved their triple helix and fibrillar conformation. Ectosome collagen had a higher OHpro content and possessed collagen type I and IV, while the choanosome was predominately constituted by collagen type IV. In vitro cytotoxicity assays using the L929 fibroblast cell line displayed a significant cytotoxic effect of choanosome collagen at 2 mg/mL, while ectosome collagen enhanced cell metabolism and proliferation, thus indicating the latter as being more suitable for the development of biomaterials. This research represents a unique comparative study of C. reniformis body parts, serving as a support for further establishing this marine sponge as a promising alternative collagen source for the future development of biomedical applications.

Harnessing value and sustainability: Fish waste valorization and the production of valuable byproducts

The valorization of by-products, that are residual materials resulting from commercial product manufacturing, holds significant potential in various industries such as food, agrochemical, medical, and pharmaceutical sectors. This chapter explores the utilization of fish waste as a means to achieve sustainability in fish resources and enhance the production of profitable products. By developing cost-effective technologies, the abundant global supply of fish by-products can be transformed into low-cost sources of proteins and functional hydrolysates. This alternative approach in the food industry utilizes fish and seafood waste to generate valuable compounds with nutritional and functional properties, surpassing those found in traditional mammal products. Despite being commonly discarded, fish heads, viscera, skin, tails, blood, and seafood shells contain a wealth ofminerals, lipids, amino acids, polysaccharides, and proteins suitable for human health applications. This chapter presents an exploration of the various products and bioactive compounds that can be derived from seafood waste, contributing to a more sustainable and value-driven future.

2D Collagen Membranes from Marine Demosponge Chondrosia reniformis (Nardo, 1847) for Skin-Regenerative Medicine Applications: An In Vitro Evaluation

Research in tissue engineering and regenerative medicine has an ever-increasing need for innovative biomaterials suitable for the production of wound-dressing devices and artificial skin-like substitutes. Marine collagen is one of the most promising biomaterials for the production of such devices. In this study, for the first time, 2D collagen membranes (2D-CMs) created from the extracellular matrix extract of the marine demosponge Chondrosia reniformis have been evaluated in vitro as possible tools for wound healing. Fibrillar collagen was extracted from a pool of fresh animals and used for the creation of 2D-CMs, in which permeability to water, proteins, and bacteria, and cellular response in the L929 fibroblast cell line were evaluated. The biodegradability of the 2D-CMs was also assessed by following their degradation in PBS and collagenase solutions for up to 21 days. Results showed that C. reniformis-derived membranes avoided liquid and protein loss in the regeneration region and also functioned as a strong barrier against bacteria infiltration into a wound. Gene expression analyses on fibroblasts stated that their interaction with 2D-CMs is able to improve fibronectin production without interfering with the regular extracellular matrix remodeling processes. These findings, combined with the high extraction yield of fibrillar collagen obtained from C. reniformis with a solvent-free approach, underline how important further studies on the aquaculture of this sponge could be for the sustainable production and biotechnological exploitation of this potentially promising and peculiar biopolymer of marine origin.

The prokaryotic community of Chondrosia reniformis Nardo, 1847: from diversity to mercury detection

Microbial communities inhabiting sponges are known to take part in many metabolic pathways, including nutrient cycles, and possibly also in the bioaccumulation of trace elements (TEs). Here, we used high-throughput, Illumina sequencing of 16S rRNA genes to characterize the prokaryotic communities present in the cortex and choanosome, respectively the external and internal body region of Chondrosia reniformis, and in the surrounding seawater. Furthermore, we estimated the total mercury content (THg) in these body regions of the sponge and in the corresponding microbial cell pellets. Fifteen prokaryotic phyla were detected in association with C. reniformis, 13 belonging to the domain Bacteria and two to the Archaea. No significant differences between the prokaryotic community composition of the two regions were found. Three lineages of ammonium-oxidizing organisms (Cenarchaeum symbiosum, Nitrosopumilus maritimus, and Nitrosococcus sp.) co-dominated the prokaryotic community, suggesting ammonium oxidation/nitrification as a key metabolic pathway within the microbiome of C. reniformis. In the sponge fractions, higher THg levels were found in the choanosome compared to the cortex. In contrast, comparable THg levels found in the microbial pellets obtained from both regions were significantly lower than those observed in the corresponding sponge fractions. Our work provides new insights into the prokaryotic communities and TEs distribution in different body parts of a model organism relevant for marine conservation and biotechnology. In this sense, this study paves the way for scientists to deepen the possible application of sponges not only as bioindicators, but also as bioremediation tools of metal polluted environments.

Collagenic architecture and morphotraits in a marine basal metazoan as a model for bioinspired applied research

In some Porifera (Demospongiae: Keratosa), prototypes of the connective system are almost exclusively based on collagenic networks. We studied the topographic distribution, spatial layout, microtraits, and/or morphogenesis of these collagenic structures in Ircinia retidermata (Dictyoceratida: Irciniidae). Analyses were carried out on a clonal strain from sustainable experimental mariculture by using light and scanning electron microscopy. Histology revealed new insights on the widely diversified and complex hierarchical assemblage of collagenic structures. Key evolutionary novelties in the organization of sponge connective system were found out. The aquiferous canals are shaped as corrugate‐like pipelines conferring plasticity to the water circulation system. Compact clusters of elongated cells are putatively involved in a nutrient transferring system. Knob‐ended filaments are characterized by a banding pattern and micro‐components. Ectosome and outer endosome districts are the active fibrogenetic areas, where exogenous material constitutes an axial condensation nucleus for the ensuing morphogenesis. The new data can be useful to understand not only the evolutionary novelties occurring in the target taxon but also the morpho‐functional significance of its adaptive collagenic anatomical traits. In addition, data may give insights on both marine collagen sustainable applied researches along with evolutionary and phylogenetic analyses, thus highlighting sponges as a key renewable source for inspired biomaterials. Therefore, we also promote bioresources sustainable exploitation with the aim to provide new donors of marine collagen, thereby supporting conservation of wild populations/species.

On the Path to Thermo-Stable Collagen: Culturing the Versatile Sponge Chondrosia reniformis

The collagen proteins family is sought-after in the pharmaceuticals, cosmetics, and food industries for various biotechnological applications. The most abundant sources of collagen are pigs and cows, but due to religious restrictions and possible disease transmission, they became less attractive. An alternative source can be found in marine invertebrates, specifically in sponges. Alas, two problems arise: (1). Growing sponges is complicated. (2). Sponge collagen has low heat tolerance, which can impose a problem for human biotechnological usage. To fill these gaps, we studied the collagen-abundant sponge Chondrosia reniformis. Two culture experiments were conducted: (1). A sea-based system examined the difference in growth rates of C. reniformis from different habitats, growing under natural seasonal conditions; (2). A land-based controlled system, which assessed the growth-rate of C. reniformis at different temperatures. The results reveal that C. reniformis from shallow habitats are growing larger and faster than individuals from colder, deeper habitats, and that the optimal temperature for C. reniformis growth is 25 °C. The results demonstrate that C. reniformis is highly fit for culture and can produce thermally stable collagen. Further research is needed to determine the best conditions for C. reniformis culture for collagen extract and other exciting materials for bioprospecting.

Potential Biomedical Applications of Collagen Filaments derived from the Marine Demosponges Ircinia oros (Schmidt, 1864) and Sarcotragus foetidus (Schmidt, 1862)

Collagen filaments derived from the two marine demosponges Ircinia oros and Sarcotragus foetidus were for the first time isolated, biochemically characterised and tested for their potential use in regenerative medicine. SDS-PAGE of isolated filaments revealed a main collagen subunit band of 130 kDa in both of the samples under study. DSC analysis on 2D membranes produced with collagenous sponge filaments showed higher thermal stability than commercial mammalian-derived collagen membranes. Dynamic mechanical and thermal analysis attested that the membranes obtained from filaments of S. foetidus were more resistant and stable at the rising temperature, compared to the ones derived from filaments of I. oros. Moreover, the former has higher stability in saline and in collagenase solutions and evident antioxidant activity. Conversely, their water binding capacity results were lower than that of membranes obtained from I. oros. Adhesion and proliferation tests using L929 fibroblasts and HaCaT keratinocytes resulted in a remarkable biocompatibility of both developed membrane models, and gene expression analysis showed an evident up-regulation of ECM-related genes. Finally, membranes from I. oros significantly increased type I collagen gene expression and its release in the culture medium. The findings here reported strongly suggest the biotechnological potential of these collagenous structures of poriferan origin as scaffolds for wound healing.

Diverse and Productive Source of Biopolymer Inspiration: Marine Collagens

Marine biodiversity is expressed through the huge variety of vertebrate and invertebrate species inhabiting intertidal to deep-sea environments. The extraordinary variety of "forms and functions" exhibited by marine animals suggests they are a promising source of bioactive molecules and provides potential inspiration for different biomimetic approaches. This diversity is familiar to biologists and has led to intensive investigation of metabolites, polysaccharides, and other compounds. However, marine collagens are less well-known. This review will provide detailed insight into the diversity of collagens present in marine species in terms of their genetics, structure, properties, and physiology. In the last part of the review the focus will be on the most common marine collagen sources and on the latest advances in the development of innovative materials exploiting, or inspired by, marine collagens.

Applications of marine collagens in bone tissue engineering

For decades, collagen has been among the most widely used biomaterials with several biomedical applications. Recently, researchers have shown a keen interest in collagen obtained from marine sources because of its biocompatibility, biodegradability, ease of extractability, safety, low immunogenicity, and low production costs. A wide variety of marine collagen-based scaffolds have been developed for bone tissue engineering, and these scaffolds display excellent biological effects. This review aims to provide an overview of the biological effects of marine collagen in bone engineering, such as promoting osteogenesis and collagen synthesis, inhibiting inflammation, inducing the differentiation of cartilage, and improving bone mineral density. Marine collagen holds great promise as a biomaterial in bone tissue engineering.

Identification, Purification and Molecular Characterization of Chondrosin, a New Protein with Anti-tumoral Activity from the Marine Sponge Chondrosia Reniformis Nardo 1847

: Chondrosia reniformis is a common marine demosponge showing many peculiarities, lacking silica spicules and with a body entirely formed by a dense collagenous matrix. In this paper, we have described the identification of a new cytotoxic protein (chondrosin) with selective activity against specific tumor cell lines, from C. reniformis, collected from the Liguria Sea. Chondrosin was extracted and purified using a salting out approach and molecular weight size exclusion chromatography. The cytotoxic fractions were then characterized by two-dimensional gel electrophoresis and mass spectrometry analysis and matched the results with C. reniformis transcriptome database. The procedure allowed for identifying a full-length cDNA encoding for a 199-amino acids (aa) polypeptide, with a signal peptide of 21 amino acids. The mature protein has a theoretical molecular weight of 19611.12 and an IP of 5.11. Cell toxicity assays showed a selective action against some tumor cell lines (RAW 264.7 murine leukemia cells in particular). Cell death was determined by extracellular calcium intake, followed by cytoplasmic reactive oxygen species overproduction. The in silico modelling of chondrosin showed a high structural homology with the N-terminal region of the ryanodine receptor/channel and a short identity with defensin. The results are discussed suggesting a possible specific interaction of chondrosin with the Cav 1.3 ion voltage calcium channel expressed on the target cell membranes.

First identification of a fatal fungal infection of the marine sponge Chondrosia reniformis by Aspergillus tubingensis

Sponges are considered promising sources of biomolecules for both pharmaceutical and cosmetic interests as well as for the production of biomaterials suitable for tissue engineering and regenerative medicine. Accordingly, the ability to grow sponges in captivity and in healthy conditions to increase their biomass is a required goal for the development of sponge aquaculture systems. To date, little information is available about the pathogenicity of fungi associated with sponges. In our study, we identified an infection in freshly collected specimens of Chondrosia reniformis (Porifera, Demospongiae) and determined that the fungus Aspergillus tubingensis was the pathogen responsible. This is the first description of a natural infection of C. reniformis by A. tubingensis. Despite raising an inflammatory response by means of an increase in tumour necrosis factor (TNF) mRNA, the infected C. reniformis specimens were not able to control the fungal infection, leading to rotting in 15 d. Characterization of this infection shows that a widely distributed fungus can represent a potential hazard to sponge aquaculture industries and how, especially in stressed or compromised marine environments, this fungus could represent a fatal opportunistic pathogen.

Insights into the evolution of metazoan regenerative mechanisms: roles of TGF superfamily members in tissue regeneration of the marine sponge Chondrosia reniformis

Tissue repair is an adaptive and widespread metazoan response. It is characterised by different cellular mechanisms and complex signalling networks that involve numerous growth factors and cytokines. In higher animals, transforming growth factor-β (TGF-β) signalling plays a fundamental role in wound healing. In order to evaluate the involvement of TGF superfamily members in lower invertebrate tissue regeneration, sequences for putative TGF ligands and receptors were isolated from the transcriptome of the marine sponge Chondrosia reniformis We identified seven transcripts that coded for TGF superfamily ligands and three for TGF superfamily receptors. Phylogenetically, C. reniformis TGF ligands were not grouped into any TGF superfamily clades and thus presumably evolved independently, whereas the TGF receptors clustered in the Type I receptor group. We performed gene expression profiling of these transcripts in sponge regenerating tissue explants. Data showed that three ligands (TGF1, TGF3 and TGF6) were mainly expressed during early regeneration and seemed to be involved in stem cell maintenance, whereas two others (TGF4 and TGF5) were strongly upregulated during late regeneration and thus were considered pro-differentiating factors. The presence of a strong TGF inhibitor, SB431542, blocked the restoration of the exopinacoderm layer in the sponge explants, confirming the functional involvement of the TGF pathway in tissue regeneration in these early evolved animals.

Modelling the early evolution of extracellular matrix from modern Ctenophores and Sponges

Animals (metazoans) include some of the most complex living organisms on Earth, with regard to their multicellularity, numbers of differentiated cell types, and lifecycles. The metazoan extracellular matrix (ECM) is well-known to have major roles in the development of tissues during embryogenesis and in maintaining homoeostasis throughout life, yet insight into the ECM proteins which may have contributed to the transition from unicellular eukaryotes to multicellular animals remains sparse. Recent phylogenetic studies place either ctenophores or poriferans as the closest modern relatives of the earliest emerging metazoans. Here, we review the literature and representative genomic and transcriptomic databases for evidence of ECM and ECM-affiliated components known to be conserved in bilaterians, that are also present in ctenophores and/or poriferans. Whereas an extensive set of related proteins are identifiable in poriferans, there is a strikingly lack of conservation in ctenophores. From this perspective, much remains to be learnt about the composition of ctenophore mesoglea. The principal ECM-related proteins conserved between ctenophores, poriferans, and bilaterians include collagen IV, laminin-like proteins, thrombospondin superfamily members, integrins, membrane-associated proteoglycans, and tissue transglutaminase. These are candidates for a putative ancestral ECM that may have contributed to the emergence of the metazoans.

Marine Collagen as A Promising Biomaterial for Biomedical Applications

This review focuses on the expanding role of marine collagen (MC)-based scaffolds for biomedical applications. A scaffold-a three-dimensional (3D) structure fabricated from biomaterials-is a key supporting element for cell attachment, growth, and maintenance in 3D cell culture and tissue engineering. The mechanical and biological properties of the scaffolds influence cell morphology, behavior, and function. MC, collagen derived from marine organisms, offers advantages over mammalian collagen due to its biocompatibility, biodegradability, easy extractability, water solubility, safety, low immunogenicity, and low production costs. In recent years, the use of MC as an increasingly valuable scaffold biomaterial has drawn considerable attention from biomedical researchers. The characteristics, isolation, physical, and biochemical properties of MC are discussed as an understanding of MC in optimizing the subsequent modification and the chemistries behind important tissue engineering applications. The latest technologies behind scaffold processing are assessed and the biomedical applications of MC and MC-based scaffolds, including tissue engineering and regeneration, wound dressing, drug delivery, and therapeutic approach for diseases, especially those associated with metabolic disturbances such as obesity and diabetes, are discussed. Despite all the challenges, MC holds great promise as a biomaterial for developing medical products and therapeutics.

Physicochemical and Biocompatibility Properties of Type I Collagen from the Skin of Nile Tilapia (Oreochromis niloticus) for Biomedical Applications

The aim of this study is to investigate the physicochemical properties, biosafety, and biocompatibility of the collagen extract from the skin of Nile tilapia, and evaluate its use as a potential material for biomedical applications. Two extraction methods were used to obtain acid-soluble collagen (ASC) and pepsin-soluble collagen (PSC) from tilapia skin. Amino acid composition, FTIR, and SDS-PAGE results showed that ASC and PSC were type I collagen. The molecular form of ASC and PSC is (α₁)₂α₂. The FTIR spectra of ASC and PSC were similar, and the characteristic peaks corresponding to amide A, amide B, amide I, amide II, and amide III were 3323 cm-1, 2931 cm-1, 1677 cm-1, 1546 cm-1, and 1242 cm-1, respectively. Denaturation temperatures (Td) were 36.1 °C and 34.4 °C, respectively. SEM images showed the loose and porous structure of collagen, indicting its physical foundation for use in applications of biomedical materials. Negative results were obtained in an endotoxin test. Proliferation rates of osteoblastic (MC3T3E1) cells and fibroblast (L929) cells from mouse and human umbilical vein endothelial cells (HUVEC) were increased in the collagen-treated group compared with the controls. Furthermore, the acute systemic toxicity test showed no acute systemic toxicity of the ASC and PSC collagen sponges. These findings indicated that the collagen from Nile tilapia skin is highly biocompatible in nature and could be used as a suitable biomedical material.

Evaluation of the Potential of Collagen from Codfish Skin as a Biomaterial for Biomedical Applications

Collagen is one of the most widely used biomaterials, not only due its biocompatibility, biodegradability and weak antigenic potential, but also due to its role in the structure and function of tissues. Searching for alternative collagen sources, the aim of this study was to extract collagen from the skin of codfish, previously obtained as a by-product of fish industrial plants, and characterize it regarding its use as a biomaterial for biomedical application, according to American Society for Testing and Materials (ASTM) Guidelines. Collagen type I with a high degree of purity was obtained through acid-extraction, as confirmed by colorimetric assays, SDS-PAGE and amino acid composition. Thermal analysis revealed a denaturing temperature around 16 °C. Moreover, collagen showed a concentration-dependent effect in metabolism and on cell adhesion of lung fibroblast MRC-5 cells. In conclusion, this study shows that collagen can be obtained from marine-origin sources, while preserving its bioactivity, supporting its use in biomedical applications.

Elicited ROS Scavenging Activity, Photoprotective, and Wound-Healing Properties of Collagen-Derived Peptides from the Marine Sponge Chondrosia reniformis

Recently, the bioactive properties of marine collagen and marine collagen hydrolysates have been demonstrated. Although there is some literature assessing the general chemical features and biocompatibility of collagen extracts from marine sponges, no data are available on the biological effects of sponge collagen hydrolysates for biomedical and/or cosmetic purposes. Here, we studied the in vitro toxicity, antioxidant, wound-healing, and photoprotective properties of four HPLC-purified fractions of trypsin-digested collagen extracts-marine collagen hydrolysates (MCHs)-from the marine sponge C. reniformis. The results showed that the four MCHs have no degree of toxicity on the cell lines analyzed; conversely, they were able to stimulate cell growth. They showed a significant antioxidant activity both in cell-free assays as well as in H₂O₂ or quartz-stimulated macrophages, going from 23% to 60% of reactive oxygen species (ROS) scavenging activity for the four MCHs. Finally, an in vitro wound-healing test was performed with fibroblasts and keratinocytes, and the survival of both cells was evaluated after UV radiation. In both experiments, MCHs showed significant results, increasing the proliferation speed and protecting from UV-induced cell death. Overall, these data open the way to the use of C. reniformis MCHs in drug and cosmetic formulations for damaged or photoaged skin repair.

Silica-induced fibrosis: an ancient response from the early metazoans

Exposure to crystalline silica particles causes silicosis, an occupational disease leading to an overproduction of collagen in the lung. The first step of this pathology is characterized by the release of inflammatory mediators. Tumour necrosis factor (TNF) is a pro-inflammatory cytokine directly involved in silica-induced pulmonary fibrosis. The marine demosponge Chondrosia reniformis is able to incorporate silica grains and partially dissolve the crystalline forms apparently without toxic effects. In the present work, C. reniformis tissue explants were treated with fine quartz dust and the expression level of fibrogenic genes was assayed by qPCR, demonstrating an overexpression of a fibrillar and a non-fibrillar collagen and of prolyl-4-hydroxylase enzyme. The deposition of new collagen could also be documented in quartz-treated sponge explants. Furthermore, TNF pro-inflammatory cytokine overexpression and involvement in silica-induced sponge collagen biosynthesis was demonstrated in quartz-treated explants as compared with controls by means of specific TNF inhibitors affecting the fibrogenic gene response. As no documentable detrimental effect was observed in treated explants, we conclude that the C. reniformis unique quartz engulfment and erosion is physiological and beneficial to the animal, leading to new collagen synthesis and strengthening of the body stiffness. Thus, we put forward the hypothesis that an ancient physiological behaviour from the lowest of the Metazoa, persisting through evolution via the same molecular mediators such as TNF, may have become the cause of disease in the specialized tissues of higher animals such as mammals.

Production, Characterization and Biocompatibility Evaluation of Collagen Membranes Derived from Marine Sponge Chondrosia reniformis Nardo, 1847

Collagen is involved in the formation of complex fibrillar networks, providing the structural integrity of tissues. Its low immunogenicity and mechanical properties make this molecule a biomaterial that is extremely suitable for tissue engineering and regenerative medicine (TERM) strategies in human health issues. Here, for the first time, we performed a thorough screening of four different methods to obtain sponge collagenous fibrillar suspensions (FSs) from C. reniformis demosponge, which were then chemically, physically, and biologically characterized, in terms of protein, collagen, and glycosaminoglycans content, viscous properties, biocompatibility, and antioxidant activity. These four FSs were then tested for their capability to generate crosslinked or not thin sponge collagenous membranes (SCMs) that are suitable for TERM purposes. Two types of FSs, of the four tested, were able to generate SCMs, either from crosslinking or not, and showed good mechanical properties, enzymatic degradation resistance, water binding capacity, antioxidant activity, and biocompatibility on both fibroblast and keratinocyte cell cultures. Finally, our results demonstrate that it is possible to adapt the extraction procedure in order to alternatively improve the mechanical properties or the antioxidant performances of the derived biomaterial, depending on the application requirements, thanks to the versatility of C. reniformis extracellular matrix extracts.

Structural studies on Demospongiae sponges from Gökçeada Island in the Northern Aegean Sea

The Demospongiae is the largest Class in the phylum Porifera (sponges). Most sponge species in the Class Demospongiae have a skeleton of siliceous spicules and/or protein spongin or both. The first aim of this study was to perform the morphological and structural characterization of the siliceous spicules of four species belonging to Class Demospongiae (Suberites domuncula, Axinella polypoides, Axinella damicornis and Agelas oroides) collected around Gökçeada Island-Turkey (Northern Aegean Sea). The characterizations were carried out using a combination of Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy (SEM/EDX), Attenuated Total Reflection-Fourier Transform Infrared Spectroscopy (ATR-FTIR) and Small Angle X-ray Scattering (SAXS) techniques. The sponge Chondrosia reniformis (Porifera, Demospongiae) lacks a structural skeleton of spicules or the spongin. It consists mainly of a collagenous tissue. The collagen with sponge origin is an important source in biomedical and pharmaceutical applications. The second aim of this study was to provide more information on the molecular structure of collagen of outer (ectosome) and inner (choanosome) regions of the Chondrosia reniformis using ATR-FTIR spectroscopy. Hierarchical clustering analysis (HCA) was also used for the discrimination of ATR-FTIR spectra of species.

Collagens of Poriferan Origin

The biosynthesis, structural diversity, and functionality of collagens of sponge origin are still paradigms and causes of scientific controversy. This review has the ambitious goal of providing thorough and comprehensive coverage of poriferan collagens as a multifaceted topic with intriguing hypotheses and numerous challenging open questions. The structural diversity, chemistry, and biochemistry of collagens in sponges are analyzed and discussed here. Special attention is paid to spongins, collagen IV-related proteins, fibrillar collagens from demosponges, and collagens from glass sponge skeletal structures. The review also focuses on prospects and trends in applications of sponge collagens for technology, materials science and biomedicine.

A new collagenase enzyme of the marine sponge pathogen Pseudoalteromonas agarivorans NW4327 is uniquely linked with a TonB dependent receptor

The primary pathogen of the Great Barrier Reef sponge Rhopaloeides odorabile, recently identified as a novel strain (NW4327) of Pseudoalteromonas agarivorans, produced collagenase which degraded R. odorabile skeletal fibers. We now report the collagenase of P. agarivorans as a metalloprotease which required Ca²⁺ and Zn²⁺ as cofactors. The collagenase was a TonB dependent receptor (TBDR) having a carboxypeptidase regulatory like domain (CRLD) in the N-terminal along with an outer membrane (OM) channel superfamily domain. The genes for TBDR sub-components and collagenase formed one unified entity in the genome of P. agarivorans NW4327. This association of a collagenase with a TBDR distinguished it from all known functional collagenases till date and for the first time, established the enzymatic capability of TBDRs. Predicted TBDR model demonstrated only 15% identity with ferripyoverdin receptor and the CRLD displayed merely 24% identity with carboxypeptidase catalytic chain. Presence of signal peptide, lack of transmembrane helices, absence of N-terminal in the cytoplasmic side, extracellular localization and recovery from the culture supernatant implicated that the TBDR was secreted. Stronger binding of the collagenase with marine sponge type IV collagen than type I collagen, revealed through molecular docking, indicated higher specificity of the enzyme towards type IV collagen.

Cellular migration, transition and interaction during regeneration of the sponge Hymeniacidon heliophila

Sponges have a high capacity for regeneration and this process improves biomass production in some species, thus contributing to a solution for the biomass supply problem for biotechnological applications. The aim of this work is to characterize the dynamics of cell behavior during the initial stages of sponge regeneration, using bright-field microscopy, confocal microscopy and SEM. We focused on the first 20 h of regeneration, during which blastema formation and epithelium initialization occur. An innovative sponge organotypic culture of the regenerating internal region is described and investigated by confocal microscopy, cell transplantation and vital staining. Cell-cell interaction and cell density are shown to affect events in morphogenesis such as epithelial/mesenchymal and mesenchymal/epithelial transitions as well as distinct cell movements required for regeneration. Extracellular matrix was organized according to the morphogenetic process observed, with evidence for cell-signaling instructions and remodeling. These data and the method of organotypic culture described here provide support for the development of viable sponge biomass production.

Aquaporin in Chondrosia reniformis Nardo, 1847 and Its Possible Role in the Interaction Between Cells and Engulfed Siliceous Particles

The sponge Chondrosia reniformis selectively engulfs siliceous particles that, when in crystalline form, become quickly dissolved in its ectosome. The molecular mechanism, identity, and physiological significance of the cells involved in this process are not completely understood. In the present study, we applied light and electronic microscopic techniques to show how the quartz particles in C. reniformis are enveloped through collagen fibers and host cells near the surface of these organisms. As various aquaporins from bacteria, animals, and plants bidirectionally conduct metalloids-including silicon ions--through the cell membrane, the presence and potential involvement of aquaporins in quartz dissolution in C. reniformis have been investigated. An aquaporin-like transcript (CrAQP) was isolated according to the transcriptome sequencing results in C. reniformis The full-length CrAQP cDNA is 907 nucleotides long, with a 795-base pair (bp), open reading frame encoding a protein of 265 amino acids, a 29-bp, 5'-non-coding region, and a 83-bp, 3'-untranslated region. The Bayesian phylogenetic inference suggests that CrAqp is closely related to the Aqp8L grade, which is also implicated in H2O2 transport. Quantification of CrAQP mRNA through qPCR indicated that the transcript level was higher in the ectosome than in the choanosome. Immunofluorescence of a mammalian AQP8 in C. reniformis showed positivity in some cells near the quartz particles, a finding that may support the initial hypothesis of the potential involvement of CrAQP in quartz erosion. However, the features of the primary structure of this protein offer a new viewpoint about the functional role of these molecules in this process: that CrAQP may be involved in the permeation of H2O2 released during silica erosion.

Molecular characterization and expression analysis of the first Porifera tumor necrosis factor superfamily member and of its putative receptor in the marine sponge Chondrosia reniformis

Here we report the molecular cloning and characterization of the first Tumor Necrosis Factor homologous and of its putative receptor in the marine sponge Chondrosia reniformis: chTNF and chTNFR, respectively. The deduced chTNF amino acid sequence is a type II transmembrane protein containing the typical TNFSF domain. Phylogenetic analysis reveals that chTNF is more related to Chordata TNFs rather than to other invertebrates. chTNF and chTNFR are constitutively expressed both in the ectosome and in the choanosome of the sponge, with higher levels in the ectosome. chTNF and chTNFR mRNAs were monitored in sponge fragmorphs treated with Gram(+) or Gram(-) bacteria. chTNF was significantly upregulated in Gram(+)-treated fragmorphs as compared to controls, while chTNFR was upregulated by both treatments. Finally, the possible chTNF fibrogenic role in sponge fragmorphs was studied by TNF inhibitor treatment measuring fibrillar and non fibrillar collagen gene expression; results indicate that the cytokine is involved in sponge collagen deposition and homeostasis.

Molecular Cloning, Characterization, and Expression Analysis of a Prolyl 4-Hydroxylase from the Marine Sponge Chondrosia reniformis

Prolyl 4-hydroxylase (P4H) catalyzes the hydroxylation of proline residues in collagen. P4H has two functional subunits, α and β. Here, we report the cDNA cloning, characterization, and expression analysis of the α and β subunits of the P4H derived from the marine sponge Chondrosia reniformis. The amino acid sequence of the α subunit is 533 residues long with an M r of 59.14 kDa, while the β subunit counts 526 residues with an M r of 58.75 kDa. Phylogenetic analyses showed that αP4H and βP4H are more related to the mammalian sequences than to known invertebrate P4Hs. Western blot analysis of sponge lysate protein cross-linking revealed a band of 240 kDa corresponding to an α2β2 tetramer structure. This result suggests that P4H from marine sponges shares the same quaternary structure with vertebrate homologous enzymes. Gene expression analyses showed that αP4H transcript is higher in the choanosome than in the ectosome, while the study of factors affecting its expression in sponge fragmorphs revealed that soluble silicates had no effect on the αP4H levels, whereas ascorbic acid strongly upregulated the αP4H mRNA. Finally, treatment with two different tumor necrosis factor (TNF)-alpha inhibitors determined a significant downregulation of αP4H gene expression in fragmorphs demonstrating, for the first time in Porifera, a positive involvement of TNF in sponge matrix biosynthesis. The molecular characterization of P4H genes involved in collagen hydroxylation, including the mechanisms that regulate their expression, is a key step for future recombinant sponge collagen production and may be pivotal to understand pathological mechanisms related to extracellular matrix deposition in higher organisms.

Comparing dynamic connective tissue in echinoderms and sponges: morphological and mechanical aspects and environmental sensitivity

Echinoderms and sponges share a unique feature that helps them face predators and other environmental pressures. They both possess collagenous tissues with adaptable viscoelastic properties. In terms of morphology these structures are typical connective tissues containing collagen fibrils, fibroblast- and fibroclast-like cells, as well as unusual components such as, in echinoderms, neurosecretory-like cells that receive motor innervation. The mechanisms underpinning the adaptability of these tissues are not completely understood. Biomechanical changes can lead to an abrupt increase in stiffness (increasing protection against predation) or to the detachment of body parts (in response to a predator or to adverse environmental conditions) that are regenerated. Apart from these advantages, the responsiveness of echinoderm and sponge collagenous tissues to ionic composition and temperature makes them potentially vulnerable to global environmental changes.

Cell reactivity to different silica

The interaction between mineral structures and living beings is increasingly attracting the interest of research. The formation of skeletons, geomicrobiology, the study of the origin of life, soil biology, benthos biology, human and mammalian diseases generated by the inhalation of dust and biomaterials are some examples of scientific areas where the topic has a relevance. In this chapter we focus on cell reactivity to siliceous rocks and to the various forms of silicon dioxide, in particular. The examples here reported carefully review how such minerals may strongly affect different living beings, from simple ones to humans. The biomineralogy concept is explained, focusing on the effects of rocks on cell growth and development. The toxic action of silicon dioxide in mammalian lungs is the oldest evidence of crystalline silica bioactivity. More recently, we could demonstrate that crystalline silica has a deep impact on cell biology throughout the whole animal kingdom. One of the most illustrative case studies is the marine sponge Chondrosia reniformis, which has the amazing ability to incorporate and etch crystalline silica releasing dissolved silicates in the medium. This specific and selective action is due to the chemical reaction of ascorbic acid with quartz surfaces. One consequence of this is an increased production of collagen. The discovery of this mechanism opened the door to a new understanding of silica toxicity for animal cells and mammalian cells in particular. The presence of silica in sea water and substrates also affects processes like the settlement of larvae and the growth of diatoms. The following sections review all such aspects.