A novel, polyoxygenated, pyranose ring containing 16-membered macrolide peloruside A (1) exhibiting cytotoxic activity in the nanomolar range was isolated from the New Zealand marine sponge Mycale sp. The structure of 1 and relative stereochemistry of the 10 stereogenic centers were determined on a 3 mg sample using a variety of spectroscopic methods. Compound 1 was isolated along with the previously reported cytotoxins mycalamide A (2) and pateamine (3) from a single specimen of this sponge.
Intraspecific variation in the composition of three cytotoxic secondary metabolites from the New Zealand marine sponge Mycale hentscheli collected at two sites in central New Zealand was quantified by 1H NMR techniques. A total of 275 sponges were analyzed bimonthly over 15 mo to compare intersite (approximately 100 km) and intrasite (approximately 100 m) spatial and temporal variations in the metabolites. Biological and physical characteristics of sponge size, morphology, depth, and temperature were recorded at each site. Metabolite concentrations were found to vary in space and time. Metabolite composition was site-specific; mycalamide A, pateamine, and peloruside A were present at Pelorus Sound, whereas pateamine was absent from sponges at Kapiti Island. Pateamine and peloruside A concentrations in sponges at Pelorus Sound varied seasonally; no such patterns were observed at Kapiti Island. Relationships of compound concentration with volume and depth were complex. High levels of peloruside A in Pelorus Sound sponges from between 8 and 10 m depth coincided with a density boundary layer and chlorophyll a maximum.
The marine sponge metabolites mycalamide A (mycalamide) and pateamine are extremely cytotoxic. While mycalamide has been shown to inhibit protein synthesis, the mechanism by which these compounds induce cell death is unknown. Using DNA laddering, Annexin-V staining, and morphological analysis, we demonstrate that both metabolites induce apoptosis in several different cell lines. Furthermore, both mycalamide and pateamine were more potent inducers of apoptosis in the 32D myeloid cell line after transformation with either the ras or bcr-abl oncogenes. This increased sensitivity was also observed in response to the protein synthesis inhibitors cycloheximide and puromycin, and cytosine-beta-D-arabinofuranoside (Ara-C), an inducer of DNA damage. We propose, therefore, that in 32D cells where Ras signalling has been altered either by constitutive expression of oncogenic ras or by Bcr/abl-mediated perturbation of upstream signalling events, increased susceptibility to apoptosis by a range of stimuli is conferred.
Warmer, more acidic water resulting from increased emissions of greenhouse gases will impact coral reef organisms, but the effects remain unknown for many dominant groups such as sponges. To test for possible effects, adult sponges of 6 common Caribbean coral reef speciesAiolochroia crassa, Aplysina cauliformis, Aplysina fistularis, Ectyoplasia ferox, Iotrochota birotulata and Smenospongia conulosa -were grown for 24 d in seawater ranging from values experienced at present-day summer-maxima (temperature = 28°C; pH = 8.1) to those predicted for the year 2100 (temperature = 31°C; pH = 7.8). For each species, growth and survival were similar among temperature and pH levels. Sponge attachment rates, which are important for reef consolidation, were similar between pH values for all species, and highest at 31°C for E. ferox, I. birotulata and A. cauliformis. Secondary metabolites, responsible for deterring predation and fouling, were examined for A. crassa, A. cauliformis, E. ferox and I. birotulata, with 1 to 3 major metabolites quantified from each species. Final metabolite concentrations varied significantly among treatments only for zooanemonin from E. ferox and N-tele-methylhistamine from I. birotulata, but these concentrations were similar to those found in wild conspecifics. Considering adult sponges only, these findings suggest that the ecological roles and physiological processes of the 6 coral reef species will be little affected by the mean values of water temperature and pH predicted for the end of the century. KEY WORDS: Sponges · Water temperature · pH · Climate change · Growth · Metabolite biosynthesis Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 462: [67][68][69][70][71][72][73][74][75][76][77] 2012 els negatively affect coral reef sponges, these ecological processes and community interactions could be impacted.The combined effects of warmer and more acidic waters on marine sponges are largely unknown. Millions of years ago, mass extinctions of calcifying sponges occurred during periods of ocean acidification and global warming (Kiessling & Simpson 2011). However, most coral reef sponges today are not calcifying species; instead they have a skeleton composed of silica spicules and/or spongin fibers (i.e. demosponges), so the effects today may differ from those of archaic times. Numerous studies have also found a relationship between water temperature and sponge growth and survival. Seasonal patterns of water temperature, for example, are positively correlated with sponge growth for some tropical species (e.g. McMurray et al. 2008, Leong & Pawlik 2010, Duckworth & Wolff 2011. In contrast, high water temperatures can exclude coral reef sponges from neighboring habitats (Pawlik et al. 2007), disrupt their symbiotic relationship with microbes, causing death (Webster et al. 2008), and promote disease outbreaks that decimate sponge populations (Smith 1941). The pH level can also influence sponge abundances, with low pH seawater caused by sulphur...
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