Effect of crude oil on defence-relevant biomarker gene expression in early-life stage lumpfish

Abstract

This thesis investigated the response of early-life stage lumpfish (i.e., larval and juvenile) to crude oil at the mRNA level. A pilot study was conducted on juvenile lumpfish, which were exposed to five chemically-enhanced water-accommodated fraction (CEWAF) treatments for 24 h in a static system. Through multiple sequence alignment (MSA), phylogenetic and synteny analyses, five lumpfish aryl hydrocarbon receptor genes were studied and named following those in Japanese pufferfish (Takifugu rubripes). The results of real-time quantitative polymerase chain reaction (qPCR) showed significant induction for ahr1a, ahr2a and cyp1a1 in the liver of oil-exposed juvenile lumpfish. Based on these results, another exposure experiment was done on 50 days post-hatch lumpfish larvae in a similar exposure set-up, with two additional CEWAF treatments. The qPCR results indicated that the 24-h CEWAF exposure might modulate immune and redox function in larval lumpfish. Moreover, a Spearman correlation analysis and principal component analysis suggested that Ahr may affect the expression of genes involved in cardiovascular development and immune response. Collectively, these results provide new insight into the influence of acute crude oil exposure on the transcript levels of targeted genes in larval and juvenile lumpfish