1985 Volume 26 Issue 6 Pages 638-642_1
A practical determination of diarrhetic shellfish poison (DSP) was established by measuring the 50% acid phosphatase activity inhibitory concentration (APIC50) with Tetrahymena pyriformis, in place of the mouse lethal assay. That is, DSP was extracted with acetone and ether from the toxic hepatopancreas of scallops, and applied to a silicic acid column. The column was washed with ether-methanol (40:1), and DSP was eluted with ether-methanol (1:1). A suitable concentration of DSP was added to 20ml of the medium for growth of T. pyriformis in an Erlenmeyer flask. This flask was inoculated with 0.2ml (approximately 4, 000 cells) of preculture of T. pyriformis and incubated at 28°C for 24 hours. The cultured cells were washed twice with 0.5% saline, and destroyed by sonication for 5min. Then the acid phosphatase activity in T. pyriformis was determined.
The APIC50 and the 50% growth inhibitory concentration (GIC50) of T. pyriformis were equivalent to 1 Mouse Unit (0.05MU/g of sample). The presence of DSP in samples can be judged qualitatively by using the naked eye when the toxin content is above the GIC50 of T. pyriformis. For the analysis of a few samples, it is convenient to apply GIC50 for quantitation of DSP, but the application of APIC50 is preferable for the treatment of many samples.
