Table 1. Toxic activity of purified PfTx extract from filtrate of Pfiesteria isolates in FMAs with larval C. variegatus, and cytotoxicity to mammalian cells.
| Culture
|
|||||
|---|---|---|---|---|---|
| Culture and year tested | Volume, liters | Cells per ml | Toxic activity,* pg of toxin extract per cell | 50 μl of PfTx extract yields time to fish death (cell equivalents)† | Cytotoxicity (GH4C1 rat pituitary cells) |
| Cultures from positive SFBs | |||||
| P. shumwayae CAAE1024C | |||||
| Trial 1 (algae-fed, then SFBs, 2003) | 1 | 1.5 ± 0.3 × 103 | 58–202 | <30 min (41 ce) | + |
| Trial 2 (fish-fed, SFBs, 2003) | 1 | 0.8 ± 0.2 × 102 | 43–251 | NA | + |
| Trial 3 (fish-fed, SFBs, 2004) | 6.4 | 11.63×104 | 47 | <28 min (817 ce) | + |
| Trial 4 (fish cell-fed – bacteria, 2004) | 0.7 | 3.5×105 | — | NA | + |
| P. shumwayae CCCMP2089 | |||||
| Trial 1 (algae-fed, then SFBs, 2003) | 1 | 1.2 ± 0.2 × 103 | 67–142 | <28 min (64 ce) | + |
| Trial 2 (fish-fed, SFBs, 2003) | 1 | 1.4 ± 1.1 × 103 | 150–284 | NA | + |
| Trial 3 (fish-fed, SFBs, 2004) | 6.4 | 1.1×104 | 0.5 | <24 h (555 ce) | + |
| Trial 4 (algae-fed, 2002) | 90 | 3.00×104 | 5 | <40 min (1,500 ce) | + |
| Controls (no fish death, SFBs) | |||||
| P. piscicida (fish-fed, SFBs, CCMP1832, NON-IND, 2003) | 300 | 2.50×104 | 6 | <90 min (1,250 ce) | + |
| P. piscicida (fish-fed, SFBs, CAAE2200, NON-IND, 2003) | 1 | 1.3×103 | ND | No mortality | — |
| Cryptoperidiniopsoid (fish-fed, SFBs, CAAE543-AC1, 2003) | 1 | 3×102 | — | No mortality | — |
| Fish – dinoflagellates (2003) | 7 | — | No mortality | — | |
All control fish remained active with no signs of stress. NA, not available; ND, not detectable.
*
Toxicity activity, based on mass of PfTx fraction purified from HW40F size-exclusion chromatography
†
Cell equivalents (ce) = μl of purified PfTx extract (derived from size-exclusion chromatography) × the cell density used to produce that purified extract