A high-throughput, microtiter plate assay for paralytic shellfish poisons using the saxitoxin-specific receptor, saxiphilin.
An isoform of the paralytic shellfish poison (PSP)-specific receptor saxiphilin, from the tropical centipede Ethmostigmus rubripes, was used as the basis for a radiometric, high-throughput, microtiter plate assay for this group of toxins. Characterization of the assay revealed that it was able to detect several representatives from the various structural PSP subgroups and yet was insensitive toward tetrodotoxin. To test the utility of the assay as a seafood toxin-monitoring tool, the assay was subjected to a variety of marine organism extracts, some of which were known to contain PSPs, and whole extract toxicity expressed as STX equivalents (STXeq) was measured by two methods: First, by comparison of values from a screening assay with a standard STX inhibition curve and, second, for highly active extracts, by calculation using the IC50 from a full inhibition curve of the extract. For extracts which could be quantified by both methods, there was almost 100% correlation between the derived values. STXeq derived by both methods from the bioassay highly correlated with absolute toxin quantities from HPLC analysis.
Australian Institute of Marine Science, Townsville 4810, Australia.
L E
LE
Llewellyn
J
J
Doyle
A P
AP
Negri
D029845:Amphibian Proteins; D000818:Animals; D001181:Arthropods / Q000737:chemistry; D001681:Biological Assay / Q000379:methods; D002352:Carrier Proteins / Q000378:metabolism*; D002623:Chemistry Techniques, Analytical / Q000379:methods*; D002851:Chromatography, High Pressure Liquid; D005506:Food Contamination / Q000032:analysis; D012530:Saxitoxin / Q000031:analogs & derivatives / Q000032:analysis* / Q000378:metabolism / Q000633:toxicity; D012758:Shellfish / Q000032:analysis* / Q000633:toxicity
D029845:Amphibian Proteins; D002352:Carrier Proteins; C027525:saxitoxin-binding protein, Rana catesbeiana; D012530:Saxitoxin