Showing papers by "William Fenical published in 1981"

Antibiotics in microbial ecology : Isolation and structure assignment of several new antibacterial compounds from the insect-symbiotic bacteriaXenorhabdus spp.

Abstract: Nine strains of the terrestrial bacterial genusXenorhabdus, all isolated as symbionts of nematodes, were examined for their abilities to produce substances with antibiotic activites when grown in pure culture. All nine produced measurable antibiotic activities against one or more of the test strains utilized. The inhibition patterns indicated that different compounds were being produced by the various bacteria. Two of the species that showed particularly strong inhibition patterns were studied in detail. The inhibitory compounds were purified and identified. Strain R produced a mixture of active substances, the major components of which were hydroxyl- and acetoxyl-bearing indole derivatives, presumably produced via tryptophan. Strain Hb, on the other hand, produced only two antibiotics, 4-ethyl- and 4-isopropyl-3,5-dihydroxy-trans-stilbenes, which are presumed to arise via polyketide pathways.

Lophotoxin: a novel neuromuscular toxin from Pacific sea whips of the genus Lophogorgia

Abstract: A new neuromuscular toxin, lophotoxin, has been isolated from several pacific gorgonians of the genus Lophogorgia. The structure of lophotoxin was deduced by combined spectrochemical methods, and belongs to the well-known cembrene class of diterpenoid molecules. Lophotoxin contains furanoaldehyde and alpha, beta-epoxy-gamma-lactone functional groups, in sharp contrast to the cationic ammonium functional groups of the established neurotoxins.

Sterol synthesis by cultured zooxanthellae; implications concerning sterol metabolism in the host-symbiont association in caribbean gorgonians

Abstract: 1. 1. The sterol composition of three taxonomically diverse Caribbean gorgonians, Briareum asbestinum (Pallas), Muriceopsis flavida (Deichmann and Bayer), and Gorgonia mariae (Bayer) is reported. As noted earlier, gorgosterol and 23-demethylgorgosterol are major components. 2. 2. The sterol composition of cultured, single colony-derived zooxanthellae isolated from these gorgonians reflects a preponderant synthesis of 4α-methyl sterols, with gorgosterol and 23-demethylgorgosterol being absent. 3. 3. Sterol analyses of three zooxanthellae-free Pacific gorgonians, Pacifigorgia adamsii (Verrill), Lophogorgia alba (Duchaissang and Michelotti) and Lophogorgia cuspidata (Verrill) point towards the existence of dietary-sterols, thus demonstrating a contrast with the composition of zooxanthellae-bearing Caribbean gorgonians. 4. 4. Our results lead to the conclusion that either some unprecedented steps in sterol biosynthesis are occurring or that sterol synthesis by zooxanthellae proceeds in different directions depending whether the algae live symbiotically or alone.