The impact of beauvericin on rainbow trout intestinal epithelial cells at different temperatures and dosing methods.

Mycotoxins in aquatic feeds and their effects on fish are becoming more important in aquaculture, as fishmeal and fish oil in feeds are being replaced with more sustainable plant protein. Here, we investigated the potential of the mycotoxin, beauvericin (BEA), to impact the rainbow trout (RT) intestine by using cultures of the epithelial cell line, RTgutGC. BEA was dosed in different ways and exposed at temperatures ranging from 4 to 26 °C before being evaluated for cell viability by the metabolic reduction of Alamar Blue, by the accumulation of Neutral Red (lysosomal activity), cytotoxicity (CellTox Green), and for wound healing. BEA induces cell death in RTgutGC cells. The lysosomes are the main target (Neutral Red assay is the most sensitive) while cytotoxicity and plasma membrane rupture (CellTox Green) occur at considerably higher concentrations. BEA caused a dose-dependent decline in Neutral Red reading at all tested temperatures but Alamar Blue readings did not decline at 4 °C. Under these conditions, BEA appears to impair only lysosomal activity. Wound healing was reduced at 4, 10, and 26 °C compared to 18 °C. Also BEA treatment, at non-cytotoxic concentrations, reduced wound healing, but the temperature had little influence on this. Different carrier vehicles (methanol, DMSO) and exposure methods (passive or active dispersal) for BEA exposure were also studied. Here, methanol and passive dispersal gave comparable results to exposure with DMSO and active dispersal. In contrast, when DMSO was dosed with passive dispersal, immediate cytotoxicity in combination with BEA was induced.