Cytochrome P4501A mRNA and protein induction in striped bass (Morone saxatilis)

Abstract

The striped bass (Morone saxatilis) supports a valuable recreational fishery and is among the most important piscivorous fish of the San Francisco Estuary. This species has suffered a significant decline in numbers over the past decades, and there is indication that contaminants are important contributors. Polycyclic aromatic hydrocarbons (PAHs) and polyhalogenated aromatic hydrocarbons (PHAHs) including PCBs and dioxins are widespread in the estuary, they typically bioaccumulate through trophic levels, reaching highest levels in top predators and are known to affect the fish health and development. The aim of this study was to investigate the dynamics of cytochrome P4501A (Cyp1a) induction simultaneously at different levels of biological organization (RNA transcription and protein synthesis) as a biomarker of exposure to PAHs and PHAHs. We utilized β-naphthoflavone (BNF) as a model PAH to induce Cyp1a responses in juvenile striped bass in both dose-response and time-response assessments and determined Cyp1a mRNA and protein levels. Significant responses were measured in both systems at 10 mg ΒΝF kg⁻¹, a concentration used for time-response studies. Messenger RNA levels peaked at 6 h post-injection, while protein levels increased progressively with time, significantly peaking at 96 h post-injection; both remaining elevated throughout the duration of the test (8 days). Our data suggest that rapid induction of gene transcription following exposure and subsequent cumulative protein synthesis could provide a useful means of identifying temporal variants in exposure to Cyp1a inducers in Morone saxatilis. The potential application of this combined Cyp1a gene and protein biomarker in this species for field studies is discussed.

Effects of water accommodated fractions of crude oils and diesel on a suite of biomarkers in Atlantic cod (Gadus morhua)

“…Such a lag between CYP1A mRNA transcription and protein expression was expected and has also been observed in other fish species (e.g. Durieux et al, 2012;Nahrgang et al, 2009). The large variability within groups in CYP1A protein expression could be due to individual differences in response times and sensitivity to potential agonists or inhibitors.…”

“…Whether this was a result of a continued DNA transcription, high mRNA stability, low rate of mRNA degradation or other species-specific factors is not known, but a rapid CYP1A mRNA turnover (days) has been indicated in other fish species following intraperitoneal injections of CYP1A inducers (Durieux et al, 2012;Kloepper-Sams and Stegeman, 1989;Nahrgang et al, 2009). An extended period (four weeks) of CYP1A mRNA induction was however also observed in polar cod (Boreogadus saida) following exposure to WAF from a NSC oil (Nahrgang et al,…”

Cytochrome P450 system expression and DNA adduct formation in the liver of Zacco platypus following waterborne Benzo(a)pyrene exposure: implications for biomarker determination

“…The time required to reach the maximum level was longer than for mRNA. This result has been shown in several studies (Hahn et al, ; Levine and Oris, ; Durieus et al, ). One possible interpretation for the prolonged increase in protein levels may involve the accumulation of mRNA and the stability of proteins (Levine and Oris, ).…”

“…However, previous studies indicated that mRNA and protein induction levels usually show a lack of correlation and mRNA is not the end product of a gene‐for‐gene function. Therefore, we studied protein induction levels as well as mRNA induction levels (Greenbaum et al, ; Durieus et al, ).…”