The red tide toxin, brevetoxin, induces embryo toxicity and developmental abnormalities

Brevetoxins are lipophilic polyether toxins produced by the red tide dinofl agellate Gymnodinium breve, and their neurotoxic effects on adult animals h ave been documented. In this study, we characterized adverse developmental effects of brevetoxin-1 (PbTx-1) using an exposure: paradigm that parallels the maternal oocyte transfer of toxin. Medaka fish (Oryzias latipes) embry os mere exposed to PbTx-1 via microinjection of toxin reconstituted in a tr iolein oil droplet. Embryos microinjected with doses of 0.1-8.0 ng/egg (ppm ) of brevetoxin-l exhibited pronounced muscular activity (hyperkinesis) aft er embryonic day 4. Upon hatching, morphologic abnormalities were commonly found in embryos at the following lowest adverse effect levels: 1.0-3.0 ppm , lateral curvature of the spinal column; 3.1-3.4 ppm, herniation of brain meninges through defects in the skull; and 3.4-4.0 ppm, malpositioned eye. Hatching abnormalities were also commonly observed at brevetoxin doses of 2 .0 ppm and higher with head-first, as opposed to the normal tail-first, hat ching, and doses > 4.1 ng/egg produced embryos that developed but failed to hatch. Given the similarity of developmental professes found between highe r and lower vertebrates, teratogenic effects of brevetoxins have the potent ial to occur among different phylogenetic classes. The observation of devel opmental abnormalities after PbTx-1 exposure identifies a new spectrum of a dverse effects that may be expected to occur following exposure to G. breve red tide events.