Untangling mechanisms of crude oil toxicity: Linking gene expression, morphology and PAHs at two developmental stages in a cold-water fish

Cardiac dysfunction affects eye development and vision by reducing supply of lipids in fish

“…Cyp1a is believed to be one of the most important factors disrupting retinoid signaling following toxicant exposure 26,60 , and is the main gene induced in crude oil exposed animals 5 . Another Cyp1 paralog, Cyp1b, is also involved in eye development (regulating ocular fissure closure) through both retinoic aciddependent and -independent pathways 25,61 and were thought to partly induce the stage dependent eye abnormalities found in Sørhus et al 2021 5 . Cyp1b induction could also explain the increased levels of retinoic acid observed in conjunction with eye deformities in our previous study 7 . Phe is known to be a poor inducer of Cyp1a 62 , and Phe eyes did not show any effect on any cyps except cyp51.…”

“…In addition to its role in the heart, calcium is also a crucial second messenger that is involved in numerous biological functions, like transcription of genes 17 . Accordingly, the calcium regulated genes were induced by crude oil exposure prior to effects on cardiac function, suggesting that crude oil has a direct effect on calcium homeostasis 5 . Although this direct effect on cardiac function is reversible 18 , a transient effect on ion homeostasis may disrupt cardiac development and cause irreversible changes in a developing animal 6 .…”

“…It is well known that crude oil exposure causes severe functional and morphometric symptoms in fish embryo and larval stages [1][2][3] . In particular, functional and developmental heart abnormalities, jaw and abnormally shaped eyes and/or reduced eye size have been documented [1][2][3][4][5][6][7] . Later in life (juveniles and adult stages), these impairments may lead to increased injuries, developmental delays, changes in swimming capacity and mortality [8][9][10] .…”

“…Exposure to crude oil and oil components have resulted in reduced eye size (anapthalmia) and reduced size with abnormalities (microthalmia) in fish larvae 5,7,23 . Eye development may be affected through several pathways.…”

“…exposures. Disruption of cardiac function after completion of main organogenesis may also affect circulatory dependent proliferation and formation events 5 , which we tested with Phe exposures. We suspected that circulatory disorders may impact lipid distribution in the organism.…”