Ichthyotoxins – from screening to exploring the mode of action

Ichthyotoxins within the context of this study are defined as compounds produced by microalgae that have a negative impact on fish. A general overview is provided, introducing the audience to harmful algal bloom forming species in different water bodies (fresh, brackish, and marine). Upcoming analytical challenges as well as an insight into their mode of action are presented based on our previous work. Finally, future challenges and perspectives are pointed out. The focus is placed on the haptophyte-microalga Prymnesium parvum, one of the better studied organisms. Its causative agents have previously been identified to be prymnesins, a group of over 50 different polyketide compounds. Currently, the strains are divided into A-, B-, and C-type producers based on the length of the carbon-backbone. Since no pure compounds are currently available, toxicological evaluations are based on investigating partly purified extracts. Using an in vitro test system of epithelium rainbow trout (Oncorynchus mykiss) gill cells (RTgill-W1), different end point assays were performed herein. These included assessing the metabolic activity, as well as cytotoxic and lytic properties. Potency ranked A>C>B-types with effective concentrations in the low to middle nmol/L range after just 3 h of incubation. The haemolytic potency in red blood cells from the Atlantic salmon (Salmo salar) reflected their cytotoxic potential. Further investigations showed the induction of membrane integrity changes, as well as chromatin condensation and nuclear fragmentation by P. parvum extracts. Moreover, the cellular redox status was affected. This study was funded in part by the Austrian Science Fund (grant DOI:10.55776/I5707). Hélène-Christine Prause was funded by the University of Vienna, Faculty of Chemistry, Zsuzsanna Neer received a stipend from the Eötvös Loránd University. The project on which this presentation is based was partly funded by the German Federal Ministry of Education and Research (BMBF) within the Research Initiative for the Conservation of Biodiversity (FEdA) under the funding code 16LW0561k.

• Mass Spectrometry
• VetImaging