Donald J. Gerhart

Learn More
The gorgonian octocoralLeptogorgia virgulata (Phylum Coelenterata, Class Anthozoa) is rarely overgrown by fouling organisms and is avoided by most predators. Laboratory experiments suggest that secondary metabolites and calcium carbonate spicules interact synergistically to provideL. virgulata with an effective defense against predatory fish. In spite of(More)
Tissue and extractable metabolites from the subtropical gorgonianLeptogorgia virgulata (Coelenterata: Anthozoa: Octocorallia: Gorgonacea) induce vomiting in a variety of fish species. To elucidate the chemical bases of this phenomenon, experiments were undertaken with purified pukalide, a cembranoid diterpene that comprises as much as 0.1–0.5% of the wet(More)
The vertebrate hormone deoxycorticosterone is the most commonly occurring component of defensive secretions from aquatic beetles in the family Dytiscidae. Deoxycorticosterone and the structurally related steroids pregn-4-en-20α:-ol-3-one and pregn-4-en-20β-ol-3-one were tested for their ability to inhibit feeding by bluegill sunfish,Lepomis macrochirus, in(More)
The spongeLissodendoryx isodictyalis is an odorous, encrusting, blue-gray sponge found on subtidal flats in North Carolina waters. The strong odor ofL. isodictyalis, coupled with the observation that it is rarely overgrown by fouling organisms, suggested that this sponge may produce metabolites with potent antifouling activity. Ethyl acetate extracts ofL.(More)
Prostaglandin A2 and its ester derivatives comprise as much as 8% of the wet tissue weight of some octocoral species such as Plexaura homomalla (phylum Cnidaria, class Anthozoa, subclass Octocorallia). These high levels of prostaglandins, although initially palatable to fish, may function as defensive toxins by inducing emesis and learned aversions in(More)
Prevoius studies have determined that the octocorals Renilla reniformis and Leptogorgia virgulata contain diterpenes that are potent inhibitors of barnacle settlement. These antifoulants—the renillafoulins and pukalide—are, however, comparatively complex and thus are not amenable to commercial exploitation. The present study examined 19 analogues, based on(More)
The Caribbean gorgonian Plexaura hornomalla contains levels of prostaglandin A2 (PGA,) which are 1 million times higher than those of most other organisms. In many sections of the Caribbean, P. homomalla produces 15(S)-PGA,, which has the same configuration at carbon 15 as mammalian prostaglandins. 15(S)-PGA, possesses potent biological activity. In Florida(More)
  • 1