Will the Increasing of Anthropogenic Pressures Reduce the Biopotential Value of Sponges?

Metabolic responses of a phototrophic sponge to sedimentation supports transitions to sponge-dominated reefs

Declines in coral abundance have been linked to increased sedimentation at many locations across the world and at some of these locations there have been subsequent increases in sponge abundance. These shifts appear counterintuitive as sponges are suspension feeders and many rely on photosymbionts for carbon. At a sedimented reef in Indonesia (Wakatobi) corals have declined and the photoautotrophic sponge Lamellodysidea herbacea is now abundant. We hypothesise that this is partly due to L. herbacea's ability to clear its tissues of high levels of settled-sediment and compensate for associated metabolic demands by altering its respiration rate. Negligible detrimental effects to sponge tissue were observed after treatments up to five times the sedimentation rate of the highly sedimented reef. Rapid sediment clearance occurred that was potentially aided by mucus production. Finally, high sediment exposure caused an immediate reduction in respiration rate, likely due to reduced pumping to prevent clogging, whereas sustained high sedimentation caused an increase in respiration rate, potentially due to the energetic cost of mucus production. Our study provides evidence that some sponges can tolerate environments that appear unsuitable to many corals and with increased sedimentation this acclimation may support further transitions to sponge dominated reefs in the future.

New Cytotoxic Cembranoid from Indonesian Soft Coral Sarcophyton sp

CONTEXT

Sarcophyton is a soft coral species that contains various secondary metabolites with cytotoxic activity. The production of cytotoxic compounds in soft corals is suggested as their allelochemical to win space competition. Therefore, if a particular soft coral species dominates a reef area, it may suggest to contain interesting bioactive compounds.

AIMS

This research aimed to characterize the cytotoxic compounds in dominant soft coral species (Sarcophyton sp.) on the reef at the Western side of Mahengetang Island, Indonesia.

SUBJECTS AND METHODS

Isolation of cytotoxic compounds through ethanol extracts had been done with preparative high-performance liquid chromatography and bioassay-guided fractionation by MCF-7 (breast) cancer cell lines. The structures of each cytotoxic compounds were elucidated on the basis of mass and nuclear magnetic resonance spectroscopic studies.

RESULTS

Elucidation through all compounds found a new cembranoid, namely, 2-hydroxy-crassocolide E (1), alongside with 5 known cembranoids; sarcophytoxide (2), sarcrassin E (3), 3,7,11-cembreriene-2,15-diol (4), 11,12-epoxy-Sarcophytol A (5), and sarcophytol A (6). All of these cembranoids were showed to inhibit the growth of MCF-7 (breast) cancer, with 50% inhibition of tumor cell lines growth lower than 30 mg/L.

CONCLUSIONS

Results of this study suggest that a soft coral species which dominate a reef area is a potential source for various bioactive compounds.

SUMMARY

Elucidation of cytotoxic compounds from Sarcophyton sp. that dominate the reef at Mahengetang Island Indonesia revealed a new compound (2-hydroxy-crassocolide E) alongside with 5 known cembranoid compounds. Abbreviations Used: SCUBA: Self-contained underwater breathing apparatus; HPLC: High performance liquid chromatography; NMR: Nuclear magnetic resonance; IT-TOF: Ion trap-time of flight; MTT: 3-(4,5-dimethylthiazol-2-yl)-2; 5-diphenyltetrazolinon bromide; DEPT: Distortionless enhancement by polarisation transfer; COSY: Correlation spectroscopy; HMBC: Heteronuclear multiplebond correlation; NOE: Nuclear overhauser effect; IG50: 50% inhibition growth.

The role of sponge-bacteria interactions: the sponge Aplysilla rosea challenged by its associated bacterium Streptomyces ACT-52A in a controlled aquarium system

Sponge-associated bacteria play a critical role in sponge biology, metabolism and ecology, but how they interact with their host sponges and the role of these interactions are poorly understood. This study investigated the role of the interaction between the sponge Aplysilla rosea and its associated actinobacterium, Streptomyces ACT-52A, in modifying sponge microbial diversity, metabolite profile and bioactivity. A recently developed experimental approach that exposes sponges to bacteria of interest in a controlled aquarium system was improved by including the capture and analysis of secreted metabolites by the addition of an absorbent resin in the seawater. In a series of controlled aquaria, A. rosea was exposed to Streptomyces ACT-52A at 10⁶ cfu/ml and monitored for up to 360 h. Shifts in microbial communities associated with the sponges occurred within 24 to 48 h after bacterial exposure and continued until 360 h, as revealed by TRFLP. The metabolite profiles of sponge tissues also changed substantially as the microbial community shifted. Control sponges (without added bacteria) and Streptomyces ACT-52A-exposed sponges released different metabolites into the seawater that was captured by the resin. The antibacterial activity of compounds collected from the seawater increased at 96 and 360 h of exposure for the treated sponges compared to the control group due to new compounds being produced and released. Increased antibacterial activity of metabolites from treated sponge tissue was observed only at 360 h, whereas that of control sponge tissue remained unchanged. The results demonstrate that the interaction between sponges and their associated bacteria plays an important role in regulating secondary metabolite production.