Peroxisome Proliferation in the Digestive Epithelium of Mussels Exposed to the Water Accommodated Fraction of Three Oils

The Mediterranean limpet Patella caerulea (Gastropoda, Mollusca) to assess marine ecotoxicological risk: a case study of Tunisian coasts contaminated by metals

Participants in the coastal socio-economy of the Mediterranean Sea, such as industries, aquaculture, urban populations, conglomerates, and tourists, create intense anthropogenic pressures on marine ecosystems (such as the release of trace metals). This raises concerns about their impact on the surrounding environment and on marine organisms, including those collected for human consumption. This study introduces the possibility of using Patella caerulea (Linnaeus 1758), indigenous to the Mediterranean Sea, as a biosentinel of marine pollution. This study proposes coupling environmental (bioaccumulation) and toxicological (redox homeostasis) measures of bioavailability with genetic variability (COI mtDNA) assessments. Concentrations of six trace metals (cadmium, copper, iron, lead, nickel, and zinc) were measured in surface seawater and in P. caerulea individuals collected from four coastal stations on the Tunisian coast where different levels of metal contamination have occurred. The quantified biomarkers involved the determination of antioxidant defense enzymes, catalase (CAT), glutathione peroxidase (GPX), superoxide dismutase (SOD), and the measurement of lipid peroxidation indicated by malondialdehyde (MDA) levels. Our study identified critical levels of metal contamination among locations in the Gulf of Gabes. Concomitantly, the induction of antioxidant biomarkers (especially SOD and GPX) was observed, highlighting the potential of P. caerulea to acclimate to stressful pollution conditions. Molecular analysis of COI (mtDNA) revealed low discrimination between the four P. caerulea populations, highlighting the role of marine currents in the Mediterranean Sea in the dispersal and passive transportation of limpet larvae, allowing an exchange of individuals among physically separated, P. caerulea populations.

Adverse Effects, Expression of the Bk-CYP3045C1 Gene, and Activation of the ERK Signaling Pathway in the Water Accommodated Fraction-Exposed Rotifer

To examine the deleterious effects of the water accommodated fraction (WAF) of crude oil, the growth curve, fecundity, and lifespan of the monogonont rotifer (Brachionus koreanus) were measured for 24 h in response to three different doses (0.2×, 0.4×, and 0.8×) of WAFs. A higher dose of WAFs significantly reduced the fecundity and lifespan. A rotifer 32K microarray chip showed that the Bk-CYP3045C1 gene had the highest expression. Of the 25 entire CYP genes, the Bk-CYP3045C1 gene showed a significant expression for different doses and times in response to WAFs and chemical components of WAFs (naphthalene and phenanthrene); also, glutathione S-transferase genes, ABC transporter, and other genes showed dose responses upon exposure to 80% WAF over time. Different doses of WAFs increased the oxidative stress with an induction of reactive oxygen species (ROS) and a depletion of glutathione (GSH). Exposure to WAFs did not show toxic effects on survivability in B. koreanus; however, toxicity to WAFs was shown when piperonyl butoxide, a potent inhibitor of cytochrome P450 (CYP) enzymes, was added. This toxicity was dose-dependent. After WAFs exposure, p-ERK was activated over time in response to WAFs, which suggests that WAFs can be activated by the p-ERK signaling pathway.

Effects of chronic exposure to dispersed oil on selected reproductive processes in adult blue mussels (Mytilus edulis) and the consequences for the early life stages of their larvae

Mussels (Mytilus edulis) were continuously exposed to dispersed crude oil (0.015-0.25mg/l) for 7 months covering the whole gamete development cycle. After 1 month exposure to 0.25 mg oil/l, the level of alkali-labile phosphates (ALP) and the volume density of atretic oocytes in female gonads were higher than those in the gonads of control females, indicating that oil affected the level of vitellogenin-like proteins and gamete development. Spawning of mussels was induced after 7 months oil exposure. Parental oil exposure did not affect subsequent fertilization success in clean seawater but this was reduced in 0.25 mg oil/l. Parental exposure to 0.25 mg oil/l caused both slow development and a higher percentage of abnormalities in D-shell larvae 2 days post-fertilization; reduced growth 7 days post-fertilization. These effects were greatly enhanced when larval stages were maintained at 0.25 mg oil/l. Similar studies are warranted for risk assessment prognosis.

Biomarker induction in tropical fish species on the Northwest Shelf of Australia by produced formation water

Normal operation of oil well platforms results in the discharge of produced formation water (PFW). The expression of CYP1A, CYP2M1- and 2K1-like proteins was examined for use as possible biomarkers of PFW exposure. A pilot study on the Northwest Shelf of Australia had indicated that PFW contamination possibly contributes to induction of CYP1A-like proteins in Gold-Spotted Trevally (Carangoides fulvoguttatus). The pilot study samples were re-examined for CYP1A, and, in addition, CYP2K1/2M1-like proteins. In a subsequent caged fish study in the same location a second species, Stripey seaperch (Lutjanus carponotatus), caught at a clean site, were distributed to three caging sites in a PFW gradient from the Harriet A production platform: A (near-field), B (far-field) and C (a non-impacted reference site). Fish were sampled at time (T) T = 0, T = 3 and T = 10 days. Significant increases of CYP1A, one CYP2K1- and two CYP2M1-like proteins were noted at Site A at T = 10d. For another CYP2K1-like protein, a significant increase was observed at Site A only at T = 3d. These results support a previous study indicating that CYP1A protein is sensitive to PFW exposure. Importantly, statistically significant environmental induction of both CYP2M1- and CYP2K1-like proteins in tropical fish due to PFW exposure had not previously been described and induction of enzymes in the CYP2 family suggest new biomarkers for PFW. In addition, the novel response of one CYP2K-like protein requires further verification, but offers promise for improved monitoring of sub-lethal responses in marine organisms.