The overall objective of our research program is the systematic biochemical and pathophysiological characterization of novel toxins and bioactive compounds from venomous marine invertebrates of regional importance.
Advances in the field of natural toxin and bioactive compound identification from venomous animals by researchers worldwide typically involve a combined iterative strategy of biochemical separation and bioactivity assay. Over the past 7 years, we have utilized an array of biochemical, physiological, morphological, and molecular biological approaches to elucidate the biochemical properties and the mechanisms of action of venom constituents, which initiate the pathophysiological responses observed in human envenomation by the Hawaiian box jellyfish, Carybdea alata. This systems-based research effort involves a classic array of conventional and sophisticated research tools including density-gradient separations, high pressure liquid chromatography using normal-phase, reverse-phase and specialized resins, Fourier transform infrared spectrometry, enzyme assays, tissue culture assays (96-well plate chemotaxis and calcium flux) cardiac doppler recording, and scanning and transmission electron microscopy. Successful isolation and characterization of a profoundly hemolytic protein from Carybdea alata by our laboratory demonstrates the success of such a strategy. The target of the current research program is the identification and characterization of neuroactive compounds from this potent paralytic venom such as identifying the constituent(s) eliciting crayfish nerve cord block and heart-rate effects in crude venom and hydrophobic extracts. Further bioassays to continue to characterize these bioactive lipids are now being developed. After successful purification of bioactive fractions, various bioassay and electrophysiological techniques (in collaboration) will be used to carefully elucidate the mechanism of action. Parallel mass spectrometry (MS) studies have led to the molecular identification of several bioactive lipid compounds.
The systematic biochemical characterization of this cnidarian venom has resulted in unanticipated discoveries as well. For instance, initial work to optimize the recovery of nematocyst venom for biochemical characterization led to the discovery of a novel and unprecedented structure, the lancet, which underscores the highly specialized nature of cubozoans as compared to other cnidarian species. Similarly, while characterizing phospholipase proteins, a family of novel fluorophores was identified (which prompt questions about the absorbance properties of visual pigments of invertebrate and/or fish prey) and may potentially indicate a new photic lure predation strategy.