Exposure To Glyphosate Or Roundup During Zebrafish Embryogenesis Differentially Affects Metabolism And Swimming Behaviours

Glyphosate-based herbicides (GBHs), the most recognized of which is Roundup, are the most extensively used herbicides worldwide. GBHs were initially considered safe for animals since the primary target of the active ingredient, glyphosate, is only found in plants. Recent studies show that glyphosate can affect a range of animal physiologies; however, it remains poorly characterized as to whether animal GBH effects are mediated by glyphosate itself or are in response to toxic effects of the adjuvants and surfactants found in GBH formulations. Here we expose embryonic zebrafish to environmentally relevant doses of glyphosate or Roundup and compare effects on two systems in the larvae: cellular bioenergetics, since glyphosate can affect mitochondrial function, and behaviour, as a systems-level readout of lasting developmental changes. We showed that exposure of embryonic zebrafish to low levels of glyphosate resulted in decreased mitochondrially-mediated basal respiration and hypoactive swimming behavior in larval stage, whereas exposure to Roundup in this same treatment paradigm had the opposite effect, causing increased cellular respiration and increased locomotion. In addition, we also explored generational effects of F1 embryonic glyphosate or Roundup exposure in the F2, and showed that offspring born to zebrafish exposed to low-level glyphosate or Roundup during embryogenesis both exhibited reduced mitochondrially-mediated basal respiration and altered locomotion. Combined, these data show that embryonic exposure to glyphosate or the full formulation of GBHs caused differential effects on mitochondrial function and behaviours in vertebrates, with potential lasting effects on future generations. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=84 SRC="FIGDIR/small/510731v1_fig1.gif" ALT="Figure 1"> View larger version (12K): org.highwire.dtl.DTLVardef@93431borg.highwire.dtl.DTLVardef@1aa602org.highwire.dtl.DTLVardef@1890cf5org.highwire.dtl.DTLVardef@b1c655_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOFigure 1.C_FLOATNO Graphical abstract.Zebrafish (F1 generation) were exposed to glyphosate or Roundup from zero to 48 hours, with behaviour and mitochondrial bioenergetics assessed at larval timepoints (2- and 5-dpf). Offspring of glyphosate and Roundup exposed fish (F2 generation) behaviour and mitochondrial bioenergetics were assessed to the same paradigm as F1 fish at 5-dpf. Changes to core metabolic parameters and locomotion was observed in both F1 and F2 generations. C_FIG