Arctic Sponge Research Articles

Somalactams A-D: Anti-inflammatory Macrolide Lactams with Unique Ring Systems from an Arctic Actinomycete Strain.

Four new PKS-NRPS-derived macrolide lactams with three unique ring fusion types were discovered from the Arctic sponge associated actinomycete Streptomyces somaliensis 1107 using a genome mining strategy. Their structures were elucidated by a combination of MS, NMR spectroscopic analysis, and single-crystal X-ray diffraction. Biosynthetically, a novel gene cluster sml consisting of three polyketide synthases and one hybrid polyketide synthase-nonribosomal peptide synthetase together with cytochrome P450s and flavin-containing monooxygenases and oxidoreductases was demonstrated to assemble the unique skeleton. Pharmacological studies revealed that compound 1 displayed a potent anti-inflammatory effect without cytotoxicity. It inhibited IL-6 and TNF-α release in the serum of LPS-stimulated RAW264.7 macrophage cells with IC50 values of 5.76 and 0.18 μM, respectively, and modulated the MAPK pathway. Moreover, compound 1 alleviated LPS-induced systemic inflammation in our transgenic fluorescent zebrafish model.

Somalactams A–D: Anti‐inflammatory Macrolide Lactams with Unique Ring Systems from an Arctic Actinomycete Strain

AbstractFour new PKS‐NRPS‐derived macrolide lactams with three unique ring fusion types were discovered from the Arctic sponge associated actinomycete Streptomyces somaliensis 1107 using a genome mining strategy. Their structures were elucidated by a combination of MS, NMR spectroscopic analysis, and single‐crystal X‐ray diffraction. Biosynthetically, a novel gene cluster sml consisting of three polyketide synthases and one hybrid polyketide synthase‐nonribosomal peptide synthetase together with cytochrome P450s and flavin‐containing monooxygenases and oxidoreductases was demonstrated to assemble the unique skeleton. Pharmacological studies revealed that compound 1 displayed a potent anti‐inflammatory effect without cytotoxicity. It inhibited IL‐6 and TNF‐α release in the serum of LPS‐stimulated RAW264.7 macrophage cells with IC50 values of 5.76 and 0.18 μM, respectively, and modulated the MAPK pathway. Moreover, compound 1 alleviated LPS‐induced systemic inflammation in our transgenic fluorescent zebrafish model.

Beyond the tip of the seamount: Distinct megabenthic communities found beyond the charismatic summit sponge ground on an arctic seamount (Schulz Bank, Arctic Mid-Ocean Ridge)

Our understanding of the benthic communities on arctic seamounts and descriptions of such communities in habitat classification systems are limited. In recent years, Schulz Bank (73°52′N 7°30′E), a seamount on the Arctic Mid-Ocean Ridge (AMOR), has become well studied but the work has primarily focused on an arctic sponge ground at the summit. This has compounded a general assumption that the most biologically interesting community is on the summit alone. With the potential threat of deep-sea mining on nearby sites on AMOR, it is crucial to form a baseline understanding of the benthic megafaunal communities not only on the summit, but on the slopes and base of the seamount as well. Using video footage collected by a remotely operated vehicle in 2017 and 2018 to survey the seamount from 2700 to 580 m depth, several distinct megafauna communities on Schulz Bank were identified. Specifically, five biotopes, two of which were dominated by large structure-forming sponges, appeared to follow a depth gradient and change with the type of substrata present. The sponge-dominated communities on the summit and lower slope had the highest average community densities and number of morphotaxa per image compared to the upper slope and seamount base communities. Most notably, sponge-dominated bedrock walls on the lower slopes challenge the assumption that the summit is the most dense and diverse community on Schulz Bank. The results from this study lay the foundation for future research and conservation efforts of arctic sponge grounds by looking beyond the seamount summit to bring a full view of enigmatic sponge dominated ecosystems.

An Efficient Synthesis of 3-Alkylpyridine Alkaloids Enables Their Biological Evaluation.

3-Alkylpyridine alkaloids (3-APAs) isolated from the arctic sponge Haliclona viscosa are a promising group of bioactive marine alkaloids. However, due to limited bioavailability, investigations of their bioactivity have been hampered. Additionally, synthesis of a common intermediate requires the use of protecting groups and harsh conditions. In this work, we developed a simple and concise two-step route to nine different natural and synthetic haliclocyclins. These compounds displayed modest antibiotic activity against several Gram-positive bacterial strains.

Bacterial precursors and unsaturated long-chain fatty acids are biomarkers of North-Atlantic deep-sea demosponges.

Sponges produce distinct fatty acids (FAs) that (potentially) can be used as chemotaxonomic and ecological biomarkers to study endosymbiont-host interactions and the functional ecology of sponges. Here, we present FA profiles of five common habitat-building deep-sea sponges (class Demospongiae, order Tetractinellida), which are classified as high microbial abundance (HMA) species. Geodia hentscheli, G. parva, G. atlantica, G. barretti, and Stelletta rhaphidiophora were collected from boreal and Arctic sponge grounds in the North-Atlantic Ocean. Bacterial FAs dominated in all five species and particularly isomeric mixtures of mid-chain branched FAs (MBFAs, 8- and 9-Me-C16:0 and 10- and 11-Me-C18:0) were found in high abundance (together ≥ 20% of total FAs) aside more common bacterial markers. In addition, the sponges produced long-chain linear, mid- and a(i)-branched unsaturated FAs (LCFAs) with a chain length of 24‒28 C atoms and had predominantly the typical Δ5,9 unsaturation, although the Δ9,19 and (yet undescribed) Δ11,21 unsaturations were also identified. G. parva and S. rhaphidiophora each produced distinct LCFAs, while G. atlantica, G. barretti, and G. hentscheli produced similar LCFAs, but in different ratios. The different bacterial precursors varied in carbon isotopic composition (δ13C), with MBFAs being more enriched compared to other bacterial (linear and a(i)-branched) FAs. We propose biosynthetic pathways for different LCFAs from their bacterial precursors, that are consistent with small isotopic differences found in LCFAs. Indeed, FA profiles of deep-sea sponges can serve as chemotaxonomic markers and support the concept that sponges acquire building blocks from their endosymbiotic bacteria.

Spatial patterns of arctic sponge ground fauna and demersal fish are detectable in autonomous underwater vehicle (AUV) imagery

Deep-sea sponge grounds are important habitats that provide several ecosystem services, yet relatively little is known about their distribution and ecology. While most surveys have focused on the broad-scale distribution patterns of sponge grounds (100s–1000s m), only rarely have the finer-scale (<10 m) spatial distribution patterns of the primary organisms been studied. In this study, the autonomous underwater vehicle (AUV) Hugin 1000 was used to map an area of an arctic sponge ground located on the summit of the Schulz Bank (Arctic Mid-Ocean Ridge), with the aim of detecting small-scale spatial patterns produced by the dominant megafauna. Using low-light cameras to construct a photomosaic comprising of 9,953 images and a virtual quadrat spatial sampling approach, density hotspots of the most prominent megafauna were visualized. The primary megafauna detected were demosponges, hexactinellids, ascidians, cnidarians, echinoderms, and demersal fish species. Most megafauna, like the primary structure-forming sponge species Geodia parva and Stelletta rhaphidiophora, were distributed evenly throughout the sample area, though species like Lissodendoryx (Lissodendoryx) complicata and Gersemia rubiformis displayed clear fine-scale spatial preferences. The three demersal fish species, Macrourus berglax, Reinhardtius hippoglossoides, and Amblyraja hyperborea, were uniformly distributed throughout the sample area. Based on the presence of skate egg cases and juveniles within many images, it is likely that the site is being used as a nursery ground for A. hyperborea. This study demonstrates the potential of using AUVs to detect fine-scale spatial patterns of the structure-forming sponges and demersal fish species. The use of AUVs for deep-water benthic surveys can help visualize how fauna (e.g. fish) utilise deep-sea habitats, and act as a tool for quantifying individuals through relatively unbiased means (e.g. pre-programmed track, no sampling). Such information is crucial for future conservation and management efforts.

Oceanographic setting and short-timescale environmental variability at an Arctic seamount sponge ground

Mass occurrences of large sponges, or ‘sponge grounds’, are found globally in a range of oceanographic settings. Interest in these grounds is growing because of their ecological importance as hotspots of biodiversity, their role in biogeochemical cycling and bentho-pelagic coupling, the biotechnological potential of their constituent sponges, and their perceived vulnerability to physical disturbance and environmental change. Little is known about the environmental conditions required for sponges to persist and for grounds to form, and very few studies have explicitly characterised and interpreted the importance of oceanographic conditions. Here, results are presented of the first observational oceanographic campaign at a known sponge ground on the Schultz Massif Seamount (SMS; Arctic Mid-Ocean Ridge, Greenland / Norwegian Seas). The campaign consisted of water column profiling and short-term deployment of a benthic lander. It was supported by multibeam echosounder bathymetry and remotely operated vehicle video surveys. The seamount summit hosted several environmental factors potentially beneficial to sponges. It occurred within relatively nutrient-rich waters and was regularly flushed from above with slightly warmer, oxygen-enriched Norwegian Arctic Intermediate Water. It was exposed to elevated suspended particulate matter levels and oscillating currents (with diurnal tidal frequency) likely to enhance food supply and prevent smothering of the sponges by sedimentation. Elevated chlorophyll a concentration was observed in lenses above the summit, which may indicate particle retention by seamount-scale circulation patterns. High sponge density and diversity observed on the summit is likely explained by the combination of several beneficial factors, the coincidence of which at the summit arises from interaction between seamount geomorphology, hydrodynamic regime, and water column structure. Neighbouring seamounts along the mid-ocean ridge are likely to present similarly complex oceanographic settings and, as with the SMS, associated sponge ground ecosystems may therefore be sensitive to changes over a particularly broad range of abiotic factors.

The bromotyrosine derivative ianthelline isolated from the arctic marine sponge Stryphnus fortis inhibits marine micro- and macrobiofouling.

The inhibition of marine biofouling by the bromotyrosine derivative ianthelline, isolated from the Arctic marine sponge Stryphnus fortis, is described. All major stages of the fouling process are investigated. The effect of ianthelline on adhesion and growth of marine bacteria and microalgae is tested to investigate its influence on the initial microfouling process comparing with the known marine antifoulant barettin as a reference. Macrofouling is studied via barnacle (Balanus improvisus) settlement assays and blue mussel (Mytilus edulis) phenoloxidase inhibition. Ianthelline is shown to inhibit both marine micro- and macrofoulers with a pronounced effect on marine bacteria (minimum inhibitory concentration (MIC) values 0.1-10μg/mL) and barnacle larval settlement (IC50 = 3.0μg/mL). Moderate effects are recorded on M. edulis (IC50 = 45.2μg/mL) and microalgae, where growth is more affected than surface adhesion. The effect of ianthelline is also investigated against human pathogenic bacteria. Ianthelline displayed low micromolar MIC values against several bacterial strains, both Gram positive and Gram negative, down to 2.5μg/mL. In summary, the effect of ianthelline on 20 different representative marine antifouling organisms and seven human pathogenic bacterial strains is presented.

The Arctic sponge Haliclona viscosa as a source of a wide array of 3-alkyl pyridine alkaloids

The Arctic sponge Haliclona viscosa has proven to be a promising source for 3-alkyl pyridinium and 3-alkyl tetrahydropyridine alkaloids (3-APAs). H. viscosa was the origin of the first cyclic monomeric 3-APA (haliclocyclin F), the first cyclic trimeric 3-APA (viscosamine C), the first dimeric 3-APA amino acid adduct (viscosaline C), and the first 3‐alkyl tetrahydropyridine alkaloids with saturated alkyl chains (haliclamines C and D). This review focuses on the challenging structure elucidations of 3-APAs isolated from H. viscosa using a combination of NMR spectroscopy and mass spectrometry.

ChemInform Abstract: Structure Elucidation of Submilligram Quantities of Natural Products — Application to Haliclamines G and H from the Arctic Marine Sponge Haliclona viscosa.

AbstractTwo new haliclamines (I) are identified directly from the crude extract of an arctic sponge using improved chromatographic conditions and detailed knowledge about the fragmentation pattern of haliclamines.

Structure Elucidation of Submilligram Quantities of Natural Products - Application to Haliclamines G and H from the Arctic Marine Sponge Haliclona viscosa

Two new haliclamines were identified directly from the crude extract of the Arctic sponge Haliclona viscosa using improved chromatographic conditions and a detailed knowledge about the fragmentation pattern of haliclamines. These are haliclamine G (1) with two alkyl chains of equal length (10 methylene groups) and haliclamine H (2) with alkyl chains of 10 and 12 methylene groups. Due to the limited amount of sponge material available, the haliclamines were not isolated, and the structure elucidation relied on the chromatographic and mass spectrometric comparison with synthetic compounds

Viscosalines B1,2 and E1,2: Challenging New 3-Alkyl Pyridinium Alkaloids from the Marine Sponge Haliclona viscosa

Four new 3-alkyl pyridinium alkaloids, the viscosalines B(1) (1 a), B(2) (1 b), E(1) (2 a), and E(2) (2 b), were isolated from the Arctic sponge Haliclona viscosa. The structure elucidation of these isomeric compounds was challenging due to ambiguous fragments that derive during "standard" mass spectrometric fragmentation experiments. The final structure elucidation relied on the use of a combination of synthesis, liquid chromatography, and mass spectrometry. Three different mass spectrometers were used to differentiate between the synthetic structural isomers: a time-of-flight (TOF) mass spectrometer and two ion-trap mass spectrometers with different ion-transfer technologies (i.e., skimmer versus funnel optics). Although at first none of the spectrometers returned spectra that permitted structure elucidation, all three mass spectrometers provided analysis that successfully differentiated between the isomers after thorough method optimization. The use of in-source collision-induced dissociation (CID) with the ion trap and TOF instrument returned the most interesting results. The mode of fragmentation of the viscosalines under different experimental conditions is described herein. After successful optimization of the mass spectrometric method applied, the chromatographic method was improved to distinguish the previously inseparable isomers. Finally, both the liquid chromatography and mass spectrometric methods were applied to the natural products and the results compared to those from the synthetic compounds.

Haliclocyclin C, a New Monomeric 3-Alkyl Pyridinium Alkaloid from the Arctic Marine Sponge Haliclona viscosa

For the first time, the macrocyclic monomeric 3-alkyl pyridinium alkaloid with an alkyl chain of 13 methylene groups, haliclocyclin C (1), could be identified from a natural source in the crude extract of the Arctic sponge Haliclona viscosa. Structure elucidation was carried out by comparison of the natural product with the corresponding synthetic compound.

Abstract A49: Verification of two novel phytochemical inducers of phase II metabolic enzyme NQO1 in human lung cells

Abstract One strategy for lung cancer chemoprevention focuses on the use of agents to modulate the metabolism and disposition of tobacco, environmental and endogenous carcinogens through up-regulation of detoxifying phase II enzymes. However, in studies to date, most candidate agents are not active in human lung cells. Therefore we previously applied a gene expression-based high-throughput screening approach to investigate n=800 plant-derived polyphenolic- and flavenoid- predominant compounds in the MicroSource Natural Products Library as to their effect on inducing the phase II metabolic enzymes glutathione S-transferases (GSTP1) and NAD(P)H:quinone oxidoreductase 1 (NQO1) in primary normal human bronchial epithelial (NHBE) cells and immortalized human bronchial epithelial cells (HBEC). We had identified 2, 3-dihydroxy-4-methoxy-4’-ethoxybenzophenone (DMEBP, putative source arctic sponge) and triacetylresveratrol (TRES, putative source plant myrtle) as new inducers for NQO1 mRNA expression. In the current study, in order to confirm our results, NHBE and HBEC cells in culture were exposed to diet-achievable levels of TRES and DMEBP (0.5, 1.0, 2.0 µM), as well as a panel of conventionally-recognized phytopreventive agents [epigallocatechin gallate (EGCG), resveratrol (RES) and sulforaphane (SFN)] for 24 h, 48 h, and 6 d, respectively. Quantitative RNA-specific RT-PCR showed an up-regulation of NQO1 mRNA expression of up to 10.8 fold in DMEBP-treated NHBE cells and an up-regulation of up to 4.6 fold in TRES-treated NHBE cells. NQO1 protein expression increased up to 3.4 fold in DMEBP-treated and up to 1.8 fold in TRES-treated NHBE cells. HBEC cells showed similar results for mRNA expression — an up-regulation of NQO1 mRNA expression of up to 9.7 fold in DMEBP-treated HBEC cells and an up-regulation of up to 3.1 fold in TRES-treated HBEC cells — whereas none of the tested compounds had an effect on protein expression in HBEC cells. DMEBP had a narrow therapeutic window, and was notably toxic to lung cells at 1-2 µM. We then measured accumulation of reactive oxygen species (ROS) in NHBE cell using DFA, and total GSH assays. Our ROS data so far show a slight anti-oxidant effect for DMEBP, but no effect yet found for TRES. Our data show two new agents have some effect on the up-regulation of the detoxifying enzyme NQO1 at mRNA and protein levels, but the effect was modest, and none was observed for GSTP1. Among the newly discovered agents, TRES is the most plausible candidate resulting from this search, and compares favorably, to conventional plant-derived polyphenolics/flavenoids tested. Citation Information: Cancer Prev Res 2010;3(12 Suppl):A49.

Synthesis of 3-Alkyl Pyridinium Alkaloids from the Arctic Sponge Haliclona viscosa

3-Alkyl pyridinium alkaloids (3-APAs) are common secondary metabolites in marine sponges of the order Haplosclerida. In recent years, our laboratory has isolated and synthesized several new members of this family such as haliclamines C–F, viscosamine, viscosaline and a cyclic monomer. All of them were isolated from the Arctic sponge Haliclona viscosa collected in Spitsbergen, Norway. In this article we report the syntheses of these secondary metabolites from Haliclona viscosa and related compounds and give a short overview of the bioactivity.

New haliclamines E and F from the Arctic sponge Haliclona viscosa

The Arctic sponge Haliclona viscosa is a rich source of 3-alkyl pyridinium alkaloids. Herein, we report the identification of two new haliclamines from the crude extract of this sponge. Due to the lack of sponge material, identification relied on HR-LCMS measurements and comparison with synthetic compounds.

Synthesis of the Arctic sponge alkaloid viscosaline and the marine sponge alkaloid theonelladin C

The synthesis of Arctic sponge alkaloid viscosaline ( 1) is achieved by using the Zincke reaction as the penultimate step. A key synthetic intermediate theonelladin C ( 6), itself a marine sponge natural product, is synthesised efficiently using a four-step sequence.

First Total Synthesis of the Marine Natural Product Viscosamine

Pyridinium alkaloids are widely distributed in marine sponges of the order Haplosclerida. The cyclic trimeric 3-alkylpyridinium alkaloid viscosamine, from the Arctic sponge Haliclona viscosa, was synthesised through a ten-step synthesis starting from pyridylalcohol in 8% overall yield. Key steps involved the simultaneous activation and deprotection of an open chain precursor, followed by cyclisation under highly dilution conditions. Viscosamine is the first cyclotrimeric 3-alkylpyridinium natural product obtained by total synthesis.

Dense populations of Archaea associated with the demosponge Tentorium semisuberites Schmidt, 1870 from Arctic deep-waters

The associated microbial community in the mesohyl of the Arctic deep-water sponge Tentorium semisuberites Schmidt, 1870 (Hadromerida, Demospongiae) is dominated by Archaea. This is the result of an integral approach applying analyses of microbial lipid biomarkers as well as microscopic investigations using differential fluorescence in situ hybridisation with universal probes and counterstaining with 4′,6′-diamidino-2-phenylindole (DAPI) on sponge sections based on samples collected in the Greenland Sea in 2001, 2002 and 2005. The distribution of isoprenoidal C40 hydrocarbons of the biphytane series suggests that affiliates of both major archaeal kingdoms, the Crenarchaeota and the Euryarchaeota, are present in the choanosome of T. semisuberites. Positive signals using the oligonucleotide probe ARCH915 indicate high numbers of Archaea in the mesohyl of this sponge. Based on optical estimations 70–90% of all microbial DAPI signals accounted for archaeal cells. Archaea in these high proportions have never been described in an Arctic deep-sea hadromerid sponge, nor in any other demosponge species. Similar observations in specimens collected over a time scale of 4 years suggest permanent sponge-Archaea associations.

Two New Haliclamines from the Arctic Sponge Haliclona viscosa

AbstractThere are a large number of studies on sponges from warm or tropical waters, whereas little is known about the chemistry of sponges from Arctic waters. Here, we describe the isolation and structure elucidation of two new 3‐alkyltetrahydropyridine alkaloids (haliclamines C and D) from the Arctic sponge Haliclona viscosa. MS and 2D NMR spectroscopy were used to analyse the structure of the two new compounds. Since the haliclamines consist of long alkyl chains, MS/MS methods were necessary for the unambiguous assignment of the constitution of the new alkaloids. (© Wiley‐VCH Verlag GmbH &amp; Co. KGaA, 69451 Weinheim, Germany, 2004)