Basal and 3,3′,4,4′,5-pentachlorobiphenyl-induced expression of cytochrome P450 1A, 1B and 1C genes in zebrafish

Abstract

The cytochrome P4501C (CYP1C) gene subfamily was recently discovered in fish, and zebrafish (Danio rerio) CYP1C1 transcript has been cloned. Here we cloned the paralogous CYP1C2, showing that the amino acid sequence is 78% identical to CYP1C1, and examined gene structure and expression of CYP1A, CYP1B1, CYP1C1, and CYP1C2. Xenobiotic response elements were observed upstream of the coding regions in all four genes. Zebrafish adults and embryos were exposed (24 hours) to 100 nM 3,3',4,4',5-polychlorinated biphenyl (PCB126) or 20 ppm acetone and subsequently held in clean water for 24 hours (adults) or 48 hours (embryos). All adult organs examined (eye, gill, heart, liver, kidney, brain, gut, and gonads) and embryos showed basal expression of the four genes. CYP1A was most strongly expressed in liver, whereas CYP1B1, CYP1C1, and CYP1C2 were most strongly expressed in heart and eye. CYP1B1 and the CYP1C genes showed an expression pattern similar to one another and to mammalian CYP1B1. In embryos CYP1C1 and CYP1C2 tended to have a higher basal expression than CYP1A and CYP1B1. PCB126 induced CYP1A in all organs, and CYP1B1 and CYP1C1 in all organs except gonads, or gonads and brain, respectively. CYP1C2 induction was significant only in the liver. However, in embryos all four genes were induced strongly by PCB126. The results are consistent with CYP1C1 and CYP1C2, as well as CYP1A and CYP1B1, being regulated by the aryl hydrocarbon receptor. While CYP1A may have a protective role against AHR agonists in liver and gut, CYP1B1, CYP1C1, and CYP1C2 may also play endogenous roles in eye and heart and possibly other organs, as well as during development.

Basal and benzo[a]pyrene-induced expression profile of phase I and II enzymes and ABC transporter mRNA in the early life stage of Chinese rare minnows (Gobiocypris rarus)

“…In addition, the early life stages of fish are highly sensitive to environmental stress; thus, the high basal expression of gstm could result from the role of the Gsts in maintaining oxidative stress balance (Costa et al, 2012) and protecting against chemical injury (Garner and Di Giulio, 2012). Furthermore, the low basal expression of cyp1a transcript in rare minnow embryos is similar to the previously obtained results (Jonsson et al, 2007b).…”

“…3). Similar results showing higher expression for cyp1c1 relative to cyp1a and 1b1 were observed in zebrafish (Jonsson et al, 2007b) and killifish embryos (Wang et al, 2006). These results indicated that the cyp1c genes could play a role in fish embryo development (Jonsson et al, 2007b).…”

“…Previous studies have reported the elevated expression of cyp1a, 1b1 and 1c1 caused by various environmental pollutants during the early life stages of fish (Jonsson et al, 2007b;Timme-Laragy et al, 2007). In addition, cyp1a was markedly more inducible than the other two cyp1 genes during the exposure period.…”

“…The transcription level is a major factor influencing the role of xenobiotic enzymes in substrate oxidation and effects in vivo (Jonsson et al, 2007b). Therefore, the aim of this study was to evaluate the basal and BaP-induced transcription patterns of the genes involved in fish detoxification (cyp1a, cyp1b1, cyp1c1, gstm, ugt1a, abcb1, abcc1, abcc2, and abcg2) during the developmental stage of rare minnows to discern their role in embryo toxicity.…”

Mixture-specific gene expression in zebrafish ( Danio rerio ) embryos exposed to perfluorooctane sulfonic acid (PFOS), perfluorohexanoic acid (PFHxA) and 3,3′,4,4′,5-pentachlorobiphenyl (PCB126)

“…Expression of different genes known to be involved in PCB126 toxicity were studied in order to investigate whether the presence of PFASs would modify the patterns. Genes of the aryl hydrocarbon receptor (AhR) mediated pathway (ahr2, cyp1a) (Fang et al, 2012;Jonsson et al, 2007a;Jonsson et al, 2007b), the oxidative stress response (gpx1a) (Shi and Zhou, 2010), and a marker for apoptosis (tp53) (Shi et al, 2008) were studied. In order to address the possibility whether PFASs interfere with membrane integrity by altering lipid homeostasis, genes belonging to lipid metabolism (acaa2, osbpl1a) were monitored (Hu et al, 2005;Shi et al, 2009) Moreover, expression of two methyltransferases genes, dnmt1 and dnmt3ba, was measured in order to highlight underlying mechanisms of toxicity (Aluru et al, 2015 (Keiter et al, 2016): 25 mg/L (50µM) of PFOS, 15.7 mg/L (50 µM) of PFHxA and 7.5 µg/L (23 nM) of PCB126.…”