Toxicity of the Extracellular Phase of Prymnesium parvum Cultures

Abstract

SUMMARYCytotoxic material ('prymnesin') excreted into the growth medium by the phytoflagellate Pymnesium parvum was partially purified and crudely characterized. It proved to be a highly potent haemolysin; its solubility properties and some other characteristics are those of a lipid, perhaps a saponin. The high haemolytic activity which characterized the toxin was often also accompanied by a high ichthyotoxic activity. A method of locating haemolytic activity in a paper chromatogram is described. Fish were killed not by prymnesin alone, but were rendered highly susceptible to prymnesin poisoning by a range of cofactors: streptomycin sulphate, calcium chloride, magnesium chloride. Ichthyotoxicity in cofactor + prymnesin systems conformed within a wide concentration range to the relationship: a x b = Q, where a is a prymnesin concentration, b a minimum concentration of cofactor which elicits a lethal effect in presence of a, and Q is a cofactor-specific constant. The recognition of this relationship has enabled a sensitive assay to be developed. Practical implications are discussed and the hypothesis proposed that prymnesin acts on fish by inducing a state of abnormal permeability of the gill. A 2-week-old culture was used in the proportion of 1 : l O for inoculum. Largescale preparations were made from samples of pond water (batch size about 50 1.) which had been transferred during prymnesium bloom to a tank which was maintained a t ambient temperature (10-2S0) under fluorescent lighting for 1 to 2 weeks, in which time the toxic activity reached its peak.Detection and meamremend of hamolytic activity Rkfmmce 8tadurd. Digitonin (Merck, C. P.) served as a standard for reference; the stock solution was at a concentration of 0-026 % (w/v) in water. At a dilution of 1/200 in isotonic sodium chloride, this effected 50 % lysis of bovine erythrocytes within $5 min. in conditions of a standard assay described below.

Effects of Harmful Algal Blooms on Fish: Insights from Prymnesium parvum

“…These studies included the raphidophyte Chattonella marina [10][11][12], and reports on other relevant algal groups are lacking, even though natural blooms of several other HAB species often lead to fish kills. The existing knowledge on the mechanistic effects of P. parvum exposure indicates that an increase in gill permeability is causing sensitivity to subsequent secondary toxicity as the primary mode of action [6][7][8], but other mechanisms of action, such as hemolysis and anti-coagulant properties, have been proposed [13][14][15][16][17]. However, none of these hypotheses have been confirmed by a physiological study of P. parvum on the whole fish.…”

“…At the time of the experiment, the proposed toxins (the prymnesins [38]), were unquantifiable [39,40]. Whether prymnesins are the sole toxins in a P. parvum bloom is debatable, so controlling for prymnesin content might confound the effects of other unknown toxins [7,8,[40][41][42][43]. Significant variations in toxicity have been reported when exposing fish externally to P. parvum culture [8,40].…”

“…Whether prymnesins are the sole toxins in a P. parvum bloom is debatable, so controlling for prymnesin content might confound the effects of other unknown toxins [7,8,[40][41][42][43]. Significant variations in toxicity have been reported when exposing fish externally to P. parvum culture [8,40]. The P. parvum toxicity has been reported to vary with pH [7,43], temperature, adsorbents, oxidizing agents [43], and mechanical disturbance [44].…”

“…One of the main fish killers is the haptophyte Prymnesium parvum. This species is currently a major problem in Texas (USA) [4,5], but it has caused fish killing blooms worldwide since the first recorded bloom in Danish waters in the 1930s [1,[6][7][8]. The specific physiological mechanisms behind the effects of HABs on fish are often lacking [9].…”

Effects of the toxic haptophyte Prymnesium parvum on the survival and feeding of a ciliate: the influence of different nutrient conditions

“…The toxins have mainly been considered a problem for gill-breathing animals as they destroy the selective permeability of the gill tissue (Yariv & Hestrin 1961). However, there is also evidence for toxic effects on potential grazers.…”