Primary cultures from the marine sponge Xestospongia muta (Petrosiidae, Haplosclerida)

Deep-Sea Sponges and Corals off the Western Coast of Florida-Intracellular Mechanisms of Action of Bioactive Compounds and Technological Advances Supporting the Drug Discovery Pipeline

The majority of natural products utilized to treat a diverse array of human conditions and diseases are derived from terrestrial sources. In recent years, marine ecosystems have proven to be a valuable resource of diverse natural products that are generated to defend and support their growth. Such marine sources offer a large opportunity for the identification of novel compounds that may guide the future development of new drugs and therapies. Using the National Oceanic and Atmospheric Administration (NOAA) portal, we explore deep-sea coral and sponge species inhabiting a segment of the U.S. Exclusive Economic Zone, specifically off the western coast of Florida. This area spans ~100,000 km2, containing coral and sponge species at sea depths up to 3000 m. Utilizing PubMed, we uncovered current knowledge on and gaps across a subset of these sessile organisms with regards to their natural products and mechanisms of altering cytoskeleton, protein trafficking, and signaling pathways. Since the exploitation of such marine organisms could disrupt the marine ecosystem leading to supply issues that would limit the quantities of bioactive compounds, we surveyed methods and technological advances that are necessary for sustaining the drug discovery pipeline including in vitro aquaculture systems and preserving our natural ecological community in the future. Collectively, our efforts establish the foundation for supporting future research on the identification of marine-based natural products and their mechanism of action to develop novel drugs and therapies for improving treatment regimens of human conditions and diseases.

The Porifera microeukaryome: Addressing the neglected associations between sponges and protists

While bacterial and archaeal communities of sponges are intensively studied, given their importance to the animal's physiology as well as sources of several new bioactive molecules, the potential and roles of associated protists remain poorly known. Historically, culture-dependent approaches dominated the investigations of sponge-protist interactions. With the advances in omics techniques, these associations could be visualized at other equally important scales. Of the few existing studies, there is a strong tendency to focus on interactions with photosynthesizing taxa such as dinoflagellates and diatoms, with fewer works dissecting the interactions with other less common groups. In addition, there are bottlenecks and inherent biases in using primer pairs and bioinformatics approaches in the most commonly used metabarcoding studies. Thus, this review addresses the issues underlying this association, using the term "microeukaryome" to refer exclusively to protists associated with an animal host. We aim to highlight the diversity and community composition of protists associated with sponges and place them on the same level as other microorganisms already well studied in this context. Among other shortcomings, it could be observed that the biotechnological potential of the microeukaryome is still largely unexplored, possibly being a valuable source of new pharmacological compounds, enzymes and metabolic processes.

Breakthrough in Marine Invertebrate Cell Culture: Sponge Cells Divide Rapidly in Improved Nutrient Medium

Sponges (Phylum Porifera) are among the oldest Metazoa and considered critical to understanding animal evolution and development. They are also the most prolific source of marine-derived chemicals with pharmaceutical relevance. Cell lines are important tools for research in many disciplines, and have been established for many organisms, including freshwater and terrestrial invertebrates. Despite many efforts over multiple decades, there are still no cell lines for marine invertebrates. In this study, we report a breakthrough: we demonstrate that an amino acid-optimized nutrient medium stimulates rapid cell division in 9 sponge species. The fastest dividing cells doubled in less than 1 hour. Cultures of 3 species were subcultured from 3 to 5 times, with an average of 5.99 population doublings after subculturing, and a lifespan from 21 to 35 days. Our results form the basis for developing marine invertebrate cell models to better understand early animal evolution, determine the role of secondary metabolites, and predict the impact of climate change to coral reef community ecology. Furthermore, sponge cell lines can be used to scale-up production of sponge-derived chemicals for clinical trials and develop new drugs to combat cancer and other diseases.

Phenol Derivatives From the Sponge-Derived Fungus Didymellaceae sp. SCSIO F46

Seven new phenol derivatives named coleophomones E and F (1, 2), diorcinols L and M (3, 4), 1-hydroxy-6-methyl-11-methoxy-8-hydroxymethylxanthone (5), porric acid E (6), and 7-(2-hydroxyphenyl) butane-7,8,9-triol (7), were isolated from the EtOAc extract of the marine sponge-derived fungus Didymellaceae sp. SCSIO F46, together with 10 known compounds. Their structures were determined by spectroscopic analyses, including NMR, MS, X-ray diffraction, and theoretical calculations. Each of 1 and 2 contains an unusual spiro [cyclohexane-1,2′-inden] moiety, which is relatively seldom in nature products. Cytotoxic and COX-2 inhibitory activities of all purified compounds were tested and evaluated. Compound 3 displayed obvious cytotoxicities against Huh-7, HeLa, DU145 and HL60 cells (IC₅₀ values 5.7–9.6 μM) and weak activities against other five cell lines, while 8 showed weak cytotoxicities against HeLa and HL7702 cells. Compound 6 displayed COX-2 inhibitory activity with IC₅₀ value of 3.3 μM.

Cytotoxic Natural Products from Marine Sponge-Derived Microorganisms

A growing body of evidence indicates that marine sponge-derived microbes possess the potential ability to make prolific natural products with therapeutic effects. This review for the first time provides a comprehensive overview of new cytotoxic agents from these marine microbes over the last 62 years from 1955 to 2016, which are assorted into seven types: terpenes, alkaloids, peptides, aromatics, lactones, steroids, and miscellaneous compounds.

Purification and partial characterization of a lectin protein complex, the clathrilectin, from the calcareous sponge Clathrina clathrus

Carbohydrate-binding proteins were purified from the marine calcareous sponge Clathrina clathrus via affinity chromatography on lactose and N-acetyl glucosamine-agarose resins. Proteomic analysis of acrylamide gel separated protein subunits obtained in reducing conditions pointed out several candidates for lectins. Based on amino-acid sequence similarity, two peptides displayed homology with the jack bean lectin Concanavalin A, including a conserved domain shared by proteins in the L-type lectin superfamily. An N-acetyl glucosamine - binding protein complex, named clathrilectin, was further purified via gel filtration chromatography, bioguided with a diagnostic rabbit erythrocyte haemagglutination assay, and its activity was found to be calcium dependent. Clathrilectin, a protein complex of 3200kDa estimated by gel filtration, is composed of monomers with apparent molecular masses of 208 and 180kDa estimated on 10% SDS-PAGE. Nine internal peptides were identified using proteomic analyses, and compared to protein libraries from the demosponge Amphimedon queenslandica and a calcareous sponge Sycon sp. from the Adriatic Sea. The clathrilectin is the first lectin isolated from a calcareous sponge and displays homologies with predicted sponge proteins potentially involved in cell aggregation and interaction with bacteria.

Antiangiogenic effects of marine sponge derived compounds on cancer

The term "angiogenic switch" refers to a time-restricted event during tumor progression where the balance between pro- and anti-angiogenic factors, resulting in the transition from dormant avascularized hyperplasia to outgrowing vascularized tumor and eventually to malignant tumor progression. Targeting angiogenesis and its mechanistic pathways are critical target for cancer therapy. Recently, marine derived compounds, plays major role in cancer research. Several sponge derived compounds such as alkaloids, terpenes, macrocylic lactone and polyketide are leading drugs in the treatment of different types of diseases including cancer. Those marine sponge compounds inhibit cancer cell proliferation and tumor angiogenesis. Hence, this review sheds light on angiogenic regulators and marine sponge derived antiangiogenic compounds for cancer.

Cultivation of sponges, sponge cells and symbionts: achievements and future prospects

Marine sponges are a rich source of bioactive compounds with pharmaceutical potential. Since biological production is one option to supply materials for early drug development, the main challenge is to establish generic techniques for small-scale production of marine organisms. We analysed the state of the art for cultivation of whole sponges, sponge cells and sponge symbionts. To date, cultivation of whole sponges has been most successful in situ; however, optimal conditions are species specific. The establishment of sponge cell lines has been limited by the inability to obtain an axenic inoculum as well as the lack of knowledge on nutritional requirements in vitro. Approaches to overcome these bottlenecks, including transformation of sponge cells and using media based on yolk, are elaborated. Although a number of bioactive metabolite-producing microorganisms have been isolated from sponges, and it has been suggested that the source of most sponge-derived bioactive compounds is microbial symbionts, cultivation of sponge-specific microorganisms has had limited success. The current genomics revolution provides novel approaches to cultivate these microorganisms.

A journey under the sea: the quest for marine anti-cancer alkaloids

The alarming increase in the global cancer death toll has fueled the quest for new effective anti-tumor drugs thorough biological screening of both terrestrial and marine organisms. Several plant-derived alkaloids are leading drugs in the treatment of different types of cancer and many are now being tested in various phases of clinical trials. Recently, marine-derived alkaloids, isolated from aquatic fungi, cyanobacteria, sponges, algae, and tunicates, have been found to also exhibit various anti-cancer activities including anti-angiogenic, anti-proliferative, inhibition of topoisomerase activities and tubulin polymerization, and induction of apoptosis and cytotoxicity. Two tunicate-derived alkaloids, aplidin and trabectedin, offer promising drug profiles, and are currently in phase II clinical trials against several solid and hematologic tumors. This review sheds light on the rich array of anti-cancer alkaloids in the marine ecosystem and introduces the most investigated compounds and their mechanisms of action.

Biosynthesis and function of polyacetylenes and allied natural products

Polyacetylenic natural products are a substantial class of often unstable compounds containing a unique carbon-carbon triple bond functionality, that are intriguing for their wide variety of biochemical and ecological functions, economic potential, and surprising mode of biosynthesis. Isotopic tracer experiments between 1960 and 1990 demonstrated that the majority of these compounds are derived from fatty acid and polyketide precursors. During the past decade, research into the metabolism of polyacetylenes has swiftly advanced, driven by the cloning of the first genes responsible for polyacetylene biosynthesis in plants, moss, fungi, and actinomycetes and the initial characterization of the gene products. The current state of knowledge of the biochemistry and molecular genetics of polyacetylenic secondary metabolic pathways will be presented together with an up-to-date survey of new terrestrial and marine natural products, their known biological activities, and a discussion of their likely metabolic origins.

Possible taxonomic trends in the success of primary aggregate formation in marine sponge cell cultures

A large number of novel compounds with significant medical potential have been isolated from sponges, motivating efforts to develop techniques for the sustainable cultivation of sponge biomass. To date, 33 sponges from nine different orders have been examined to assess their ability to be cultured in vitro. However, little consideration has been given to the relationships between these sponges; only one report has considering the phylogenetic relationships between the species. On the basis of morphological data, no taxonomic specificity was apparent as an indicator for the successful cultivation of the sponges. As the systematic classification of the Demospongiae is poorly understood, we collated available information on the success of in vitro sponge cell cultivation reports and examined the phylogenetic relationships of these sponges through the use of 18S and 28S rDNA sequence data. Based on molecular data, the ability of sponges to form primary aggregates from the dissociated cells of marine demosponges indicates that taxonomic trends may exist, emphasizing the need to better characterize sponges being investigated for biotechnological applications.

Biology of the Porifera: cell culture

The discovery that dissociated sponge cells will reaggregate to form a functional organism was the basis for the establishment of sponge cell cultures that have been used as a model for the study of fundamental processes in developmental biology and immunology. More recent is the discovery of unique bioactive compounds in marine sponges, and the feasibility of in vitro production of these chemicals is being evaluated. Techniques are well established for cell dissociation; development of several nutrient media formulations has resulted in improvements in viability and cell division; and molecular approaches to identification of genes responsible for regulation of cell cycling may provide unique perspectives in culture optimization. The use of novel substrates for immobilization of cells offers alternatives for proliferation and scale-up. All of these results support the potential for development of a model system for the study of basic metabolic processes involved in cell differentiation, as well as an in vitro production system for sponge-derived bioactive compounds. Perhaps more important, however, is the development of cell lines of these "simple" metazoans to facilitate basic cell physiology and molecular biology research that may be applied to understanding more complex metazoan systems, including humans.

Marine invertebrate cell cultures: new millennium trends

This review analyzes activities in the field of marine invertebrate cell culture during the years 1999 to 2004 and compares the outcomes with those of the preceding decade (1988 to 1998). During the last 5 years, 90 reports of primary cell culture studies of marine organisms belonging to only 6 taxa (Porifera, Cnidaria, Crustacea, Mollusca, Echinodermata, and Urochordata) have been published. This figure represents a 2-fold increase in the annual number of publications over the decade 1988 to 1998. Three other trends distinguish the two reviewed periods. First, in recent years studies attempting to improve cell culture methodologies have decreased, while interest in applications of already existing methodologies has increased. This reflects the effects of short-term cultures in attracting new researchers and scientific disciplines to the field. Second, only 17.8% of the recent publications used long-term cultures, compared with 30.0% of the publications in the previous decade. Third, during recent years research in cell cultures has studied fewer model species more extensively (mainly, Botryllus schlosseri, Crassostrea, Mytilus, Penaeus, and Suberites domuncula), signifying a shift from previous investigations that had studied a more diverse range of organisms. From 1988 to 1998 the phylum Mollusca was the most studied taxon (34.4%), but recent years have seen more studies of Porifera and Crustacea (30.0% and 32.2% of publications) than of Mollusca (21.1%). Still, not even a single established cell line from any marine invertebrate has yet been made available. However, the use of new cellular, genomic, and proteomic tools may fundamentally change our strategy for the development of cell cultures from marine invertebrates.

Traditional and Modern Biomedical Prospecting: Part II-the Benefits: Approaches for a Sustainable Exploitation of Biodiversity (Secondary Metabolites and Biomaterials from Sponges)

The progress in molecular and cell biology has enabled a rational exploitation of the natural resources of the secondary metabolites and biomaterials from sponges (phylum Porifera). It could be established that these natural substances are superior for biomedical application to those obtained by the traditional combinatorial chemical approach. It is now established that the basic structural and functional elements are highly conserved from sponges to the crown taxa within the Protostomia (Drosophila melanogaster and Caenorhabditis elegans) and Deuterostomia (human); therefore, it is obvious that the molecular etiology of diseases within the metazoan animals have a common basis. Hence, the major challenge for scientists studying natural product chemistry is to elucidate the target(s) of a given secondary metabolite, which is per se highly active and selective. After this step, the potential clinical application can be approached. The potential value of some selected secondary metabolites, all obtained from sponges and their associated microorganisms, is highlighted. Examples of compounds that are already in medical use (inhibition of tumor/virus growth [arabinofuranosyl cytosine and arabinofuranosyl adenine]), or are being considered as lead structures (acting as cytostatic and anti-inflammatory secondary metabolites [avarol/avarone], causing induction of apoptosis [sorbicillactone]) or as prototypes for the interference with metabolic pathways common in organisms ranging from sponges to humans (modulation of pathways activated by fungal components [aeroplysinin], inhibition of angiogenesis [2-methylthio-1,4-napthoquinone], immune modulating activity [FK506]) are discussed in this study. In addition, bioactive proteins from sponges are listed (antibacterial activity [pore-forming protein and tachylectin]). Finally, it is outlined that the skeletal elements-the spicules-serve as blueprints for new biomaterials, especially those based on biosilica, which might be applied in biomedicine. These compounds and biomaterials have been isolated/studied by members of the German Center of Excellence BIOTECmarin. The goal for the future is to successfully introduce some of these compounds in the treatment of human diseases in order to raise the public awareness on the richness and diversity of natural products, which should be sustainably exploited for human benefit.

The life and death of sponge cells

Cell viability is an essential touchstone in the study of the effect of medium components on cell physiology. We developed a flow-cytometric assay to determine sponge-cell viability, based on the combined use of fluorescein diacetate (FDA) and propidium iodide (PI). Cell fluorescence measurements based on incubation of cells with FDA or PI resulted in a useful and reproducible estimate of the viability of primary sponge-cell cultures. We studied the effects of temperature, ammonium, and the fungicide amphotericin B on the viability of a primary-cell culture from the marine sponge Suberites domuncula using the aforementioned flow-cytometric assay. S. domuncula cells die rapidly at a temperature of >or=22 degrees C, but they are insensitive to ammonium concentrations of up to 25 mM. Amphotericin B, which is frequently used in sponge-cell culture media, was found to be toxic to S. domuncula cells.