https://phaidra.vetmeduni.ac.at/o:4273 Cytotoxicity of Prymnesium parvum extracts and prymnesin analogs on epithelial fish gill cells RTgill-W1 and the human colon cell line HCEC-1CT Varga, Elisabeth Elisabeth Varga 0000-0001-6046-3259 University of Veterinary Medicine Vienna Prause, Hélène-Christine Hélène-Christine Prause Riepl, Matthias Matthias Riepl Hochmayr, Nadine Nadine Hochmayr Berk, Deniz Deniz Berk Attakpah, Eva Eva Attakpah Kiss, Endre Endre Kiss Medić, Nikola Nikola Medić Del Favero, Giorgia Giorgia Del Favero Thomas Ostenfeld, Larsen Larsen Thomas Ostenfeld Hansen, Per Juel Per Juel Hansen Marko, Doris Doris Marko Springer journal article open access eng Harmful algal blooms kill fish populations worldwide, as exemplified by the haptophyte microalga Prymnesium parvum. The suspected causative agents are prymnesins, categorized as A-, B-, and C-types based on backbone carbon atoms. Impacts of P. parvum extracts and purified prymnesins were tested on the epithelial rainbow trout fish gill cell line RTgill-W1 and on the human colon epithelial cells HCEC-1CT. Cytotoxic potencies ranked A > C > B-type with concentrations spanning from low (A- and C-type) to middle (B-type) nM ranges. Although RTgill-W1 cells were about twofold more sensitive than HCEC-1CT, the cytotoxicity of prymnesins is not limited to fish gills. Both cell lines responded rapidly to prymnesins; with EC50 values for B-types in RTgill-W1 cells of 110 ± 11 nM and 41.5 ± 0.6 nM after incubations times of 3 and 24 h. Results of fluorescence imaging and measured lytic effects suggest plasma membrane interactions. Postulating an osmotic imbalance as mechanisms of toxicity, incubations with prymnesins in media lacking either Cl-, Na+, or Ca2+ were performed. Cl- removal reduced morphometric rearrangements observed in RTgill-W1 and cytotoxicity in HCEC-1CT cells. Ca2+-free medium in RTgill-W1 cells exacerbated effects on the cell nuclei. Prymnesin composition of different P. parvum strains showed that analog composition within one type scarcely influenced the cytotoxic potential, while analog type potentially dictate potency. Overall, A-type prymnesins were the most potent ones in both cell lines followed by the C-types, and lastly B-types. Disturbance of Ca2+ and Cl- ionoregulation may be integral to prymnesin toxicity. A Correction to this article was published on 09 April 2024: https://doi.org/10.1007/s00204-024-03716-3 Harmful Algal Bloom Transport Processes Primary Cultures Ion Regulation Rainbow-Trout Toxicity Ichthyotoxicity Allelopathy Healthy Mode http://creativecommons.org/licenses/by/4.0/ https://phaidra.vetmeduni.ac.at/api/object/o:4273/download 10.1007/s00204-023-03663-5 https://phaidra.vetmeduni.ac.at/o:605 application/pdf Archives of Toxicology issn:0340-5761 VoR Archives of Toxicology 98 3 1.47 MB 2024