Showing papers by "William Fenical published in 1995"

Defenses of Caribbean sponges against predatory reef fish. I. Chemical deterrency

Abstract: Laboratory feeding assays employing the common Canbbean wrasse Thalassoma bifasciatum were undertaken to determine the palatability of food pellets containing natural concentrations of crude organic extracts of 71 species of Caribbean demosponges from reef, mangrove, and grassbed habitats. The majority of sponge species (69%) yielded deterrent extracts, but there was considerable interand intraspecific vanability in deterrency. Most of the sponges of the aspiculate orders Verongida and Dictyoceratida yielded highly deterrent extracts, as did all the species in the orders Homosclerophorida and Axinellida. Palatable extracts were common among species in the orders Hadromerida, Poecilosclerida and Haplosclerida. Intraspecific variability was evident, suggesting that, for some species, some individuals (or portions thereof) may be chemically undefended. Reef sponges generally yielded more deterrent extracts than sponges from mangrove or grassbed habitats, but 4 of the 10 most common sponges on reefs yielded palatable extracts (Callyspongia vaginalis, Mycale laevis, Niphates erecta, Iotrochota birotulata), including those most commonly eaten by sponge-eating reef fish. The presence of symbiotic zoanthid cnidarians of the genus Parazoanthus in the tissues of otherwise palatable sponges had little effect on the deterrency of tissue extracts, indicating that these commensal polyps do not confer a chemical defense by association There was no relationship between sponge color and deterrency, suggesting that sponges are not aposematic and that color variation is the result of other factors. There was also no relationship between the toxicity of sponge extracts (as determined in previous studies) and deterrency, confirming the invalidity of previous assessments of chemical defense based on toxicity. Although chemical antipredatory defenses are important strategies for most Caribbean sponges, some common species appear to rely on other tactics.

Effects of storage and extraction procedures on yields of lipophilic metabolites from the brown seaweeds Dictyota ciliolata and D. menstrualis

Abstract: Investigations focused on the ecological roles of manne secondary metabolltes have become common, but manne ecologists have rarely assessed how methodologies used in sample preparation affect the extractability and stablhty of secondary metabolites and, thus measurements of intraspeclflc and interspeclflc compound vanance We assessed vanous procedures for storing, drylng, and extracting samples of 2 chenllcally defended brown seaweeds Dictyota cillolata and D menstrualis These plants contain the diterpenoid alcohols pachydictyol A dictyol B acetate and dlctyol E that are relatively stable under all test conditions In contrast, the related diterpenoid dlaldehyde dictyodlal decomposed when plant tissues or crude extracts were stored at -25'C for 13 to 27 wk or when tissues or extracts were freeze-dned or subjected to high vacuum ( C O 01 torr) methods that are commonly used in studies of marine chemical ecology The stabihty of dictyodial was specles-specdlc, degrading more in D cillolata than in D menstrual~s Dunng a few extractions, dictyodial reacted with methanol (MeOH) to yleld an artdact resulting from the addition of 2 molecules of MeOH per molecule of dlctyodial A mlxture of 2 1 dlchloromethane (DCM) and MeOH tended to extract the lipophlhc secondary metabolites better than MeOH or DCM alone Metabolltes were also afforded some protection agalnst degradation when fresh tissue was submerged In 2 1 DCM MeOH dunng storage at -25'C Results of thls inveshgation lndlcate that storage, extraction, and quantlflcation methods need to be o p t m z e d for analyses of individual compounds and that even ldentlcal compounds can behave differently when they occur in different specles

The relative abundance and seawater requirements of gram-positive bacteria in near-shore tropical marine samples.

Abstract: The relative abundance of gram-positive bacteria in a variety of near-shore marine samples was determined using the KOH method. Gram-positive bacteria accounted for 14%, 25%, 31 %, and 12%, respectively, of the colony-forming bacteria obtained from seawater, sediments, and the surfaces of algae and invertebrates. A total of 481 gram-positive strains were isolated representing a wide range of morphological groups including regular and irregular rods, cocci, and actinomycetes. Seventy-seven percent of the strains characterized did not form spores and were aerobic, catalase-positive rods with regular to irregular cell morphologies. Eighty-two percent of the strains tested showed an obligate requirement of seawater for growth. None of the cocci tested required seawater or sodium for growth. This is the first report documenting that gram-positive bacteria can compose a large percentage of the culturable, heterotrophic bacteria associated with the surfaces of tropical marine algae.

Distribution, density, and sequestration of host chemical defenses by the specialist nudibranch Tritonia hamnerorum found at high densities on the sea fan Gorgonia ventalina

Abstract: The dendronotid nudibranch Tritonia hamnerorurn was observed on some reefs In the Flonda Keys, USA, at very high densities dunng the summer of 1992 T hamnerorum specializes on the sea fan Gorgonia vental~na and sequesters the furano-germacrene lulieannafuran from its host, this compound effectively protects the nudibranch from consumption by the common predatoiy reef f ~ s h Thalassoma bifasciatum T hamnerorum densit~es were extremely hlgh at some locations, with as Inany as 1700 nudibranchs found on a single G ventalina colony At high densities, nudibranch feeding killed large areas on some sea fan colonies by stnpping all tissue from portions of the sea fan and allowing fllamentous algae and other epibionts to colonize The density of T hamnerorum on G ventahna vaned greatly on scales of centimeters meters and k~lometers High density patches of nudlbranchs on individual sea fans were usually composed of equivalent-sized nudtbranchs These observations suggest that pelagic vellgers have an incredible capabil~ty to find and settle synchronously on one portion of a sea fan or that the larvae or luveniles hatch from egg masses and develop without leaving the sea fan This study adds to a growlng number of manne examples suggesting that feeding specialization occurs pnmardy among small sedentary consumers that deter or escape predators by associating w t h defended hosts

Nonsteroidal human progesterone receptor modulators from the marine alga Cymopolia barbata.

Abstract: The co-transfection assay is a novel functional assay using cells transiently transfected with plasmids encoding intracellular receptors and corresponding reporter genes. Using this assay, natural product extracts were tested to identify compounds that modulate intracellular receptor activity, measured as changes in reporter gene activity. A crude extract of the marine alga Cymopolia barbata was found to inhibit progesterone-stimulated reporter gene expression in cells transfected with the human progesterone receptor (hPR) and an appropriate reporter construct. Purification of the active constituents of the extract, guided by the co-transfection assay, yielded two diastereomers of cyclocymopol monomethyl ether, possessing opposing pharmacological activities with the hPR. The antagonist (3R)-cyclocymopol monomethyl ether (LG100127) blocked 1 nM progesterone-stimulated reporter gene expression with an IC50 value of 549 +/- 55 nM in the co-transfection assay. The agonist (3S)-cyclocymopol monomethyl ether (LG100128) had efficacy similar to that of progesterone and an EC50 value of 35 +/- 2 nM. Stimulation by progesterone of the hPR in the human breast cancer cell line T-47D results in enhanced expression of alkaline phosphatase; LG100127 blocked alkaline phosphatase expression stimulated either by progesterone or by LG100128, and LG100128 mimicked progesterone in this assay. Both diastereomers displaced [3H]progesterone from baculovirus-expressed hPR. LG100127 and LG100128 each interacted with the human androgen receptor but did not interact with the human glucocorticoid receptor, estrogen receptor, vitamin D receptor, or retinoid receptors. In summary, these in vitro studies describe the first nonsteroidal pharmacophores for the hPR and demonstrate the use of the co-transfection assay in their discovery.

Antibacterial Diterpenoids from an Undescribed Soft-Coral of the genus Xenia

Abstract: Two new xenicane diterpenoids, 9-deoxyxeniolide-A (1) and 9-deoxyxeniolide-B (2), were isolated from a new species of the alcyonacean soft-coral Xenia, collected in the Philippines. The structures of the new compounds were elucidated by interpretation of spectral data. The metabolites show weak antibacterial activities, with the conjugated lactone 9-deoxyxeniolide-A (1) showing the greatest potency.

Elijopyrones A-D: New α-pyrones from a Marine Actinomycete

Abstract: Elijopyrones A-D (1–4) were isolated from a cultured marine actinomycete (isolate CNB-880). The producing strain was obtained from a sediment collected from the San Elijo Lagoon, Cardiff, California. The structures of the new compounds were determined by comprehensive spectral analyses.

Eleutherobin and analogs thereof

Abstract: Eleutherobin is a glycosylated diterpene which has structural formula (I). Eleutherobin is a cytotoxic agent which is toxic to carcinoma cancer cells. Analogs of eleutherobin are also disclosed.

Cyclic heptapeptide anti-inflammatory agent

Abstract: A cyclic heptapeptide anti-inflammatory agent, named cyclomarin-A is disclosed as in the figure. Cyclomarin-A is produced by a specific marine actinomycete. The cyclomarin-A producing bacterium is isolated from sediment located in marine estuaries in and around San Diego, California. Fermentation of the isolated bacterium in saltwater-based media produces cyclomarin-A as a secondary by-product. The cyclomarin-A is useful as an anti-inflammatory agent.

Ether derivatives of pseudopterosin

Abstract: Methods for treating mammals to reduce pain and/or reduce inflammation are described based on administering to the mammals synthetic ether derivatives of pseudopterosin having the formula: ##STR1## wherein A is an alkyl, aryl or amide group having from 2 to 20 carbon atoms, R1, R2 and R3 are hydrogen or an acyl residue (--COR) having from 1 to 6 carbon atoms, R4 is hydrogen or --CH2 OH and R5 is a hydrocarbon having from 1 to 10 carbon atoms. Also disclosed are synthetic compositions having the above general formula which are useful in the described method.