A light in the darkness: new biotransformation genes, antioxidant parameters and tissue-specific responses in oysters exposed to phenanthrene

Phenanthrene (PHE), a major component of crude oil, is one of the most abundant polycyclic aromatic hydrocarbons (PAHs) in aquatic ecosystems, and is readily bioavailable to marine organisms. Understanding the toxicity of PAHs in animals requires knowledge of the systems for xenobiotic biotransformation and antioxidant defence and these are poorly understood in bivalves. We report, for the first time, new transcripts and tissue-specific transcription in gill and digestive gland from the oyster Crassostrea brasiliana following 24 h exposure to 100 and 1000 μg L−1 PHE, a model PAH. Six new cytochrome P450 (CYP) and four new glutathione S-transferase (GST) genes were analysed by means of quantitative reverse transcription PCR (qRT-PCR). Different antioxidant endpoints, including both enzymatic and non-enzymatic parameters, were assessed as potential biomarkers of oxidative stress. GST activity was measured as an indicator of phase II biotransformation. Rapid clearance of PHE was associated with upregulation of both phase I and II genes, with more pronounced effects in the gill at 1000 μg L−1 PHE. After 24 h of exposure, PHE also caused impairment of the antioxidant system, decreasing non-protein thiols and glutathione levels. On the other hand, no change in antioxidant enzymes was observed. PHE treatment (100 μg L−1) significantly decreased GST activity in the gill of exposed oysters. Both CYP and GST were transcribed in a tissue-specific manner, reflecting the importance of the gill in the detoxification of PAHs. Likewise, the antioxidant parameters followed a similar pattern. The data provide strong evidence that these genes play key roles in C. brasiliana biotransformation of PHE and highlight the importance of gill in xenobiotic metabolism

Twenty years of the ‘Preparation for Oxidative Stress’ (POS) theory: Ecophysiological advantages and molecular strategies

Freezing, dehydration, salinity variations, hypoxia or anoxia are some of the environmental constraints that many organisms must frequently endure. Organisms adapted to these stressors often reduce their metabolic rates to maximize their chances of survival. However, upon recovery of environmental conditions and basal metabolic rates, cells are affected by an oxidative burst that, if uncontrolled, leads to (oxidative) cell damage and eventually death. Thus, a number of adapted organisms are able to increase their antioxidant defenses during an environmental/functional hypoxic transgression; a strategy that was interpreted in the 1990s as a “preparation for oxidative stress” (POS). Since that time, POS mechanisms have been identified in at least 83 animal species representing different phyla including Cnidaria, Nematoda, Annelida, Tardigrada, Echinodermata, Arthropoda, Mollusca and Chordata. Coinciding with the 20th anniversary of the postulation of the POS hypothesis, we compiled this review where we analyze a selection of examples of species showing POS-mechanisms and review the most recent advances in understanding the underlying molecular mechanisms behind those strategies that allow animals to survive in harsh environments

RA Differentiation Enhances Dopaminergic Features, Changes Redox Parameters, and Increases Dopamine Transporter Dependency in 6-Hydroxydopamine-Induced Neurotoxicity in SH-SY5Y Cells

Experimental investigations were performed to characterize the mechanical properties of bamboo fiber-polyester composites. The composite laminates were fabricated by infusing different forms of untreated bamboo fibers (randomly oriented, bamboo textiles and bamboo foam cores) with polyester resin. The results showed that the engineered bamboo fiber composites have strength and stiffness properties suitable for structural applications. Among the tested composites, the laminates with randomly oriented bamboo fibers exhibited the highest strength properties. Its strength in flexure, tension, compression, and shear are 58, 35, 48, and 32 MPa, respectively and its Modulus of Elasticity (MOE) is 3.2GPa. However, only the tensile strength and MOE showed better properties to that of neat polyester resin which are 15% and 4% higher, re-spectively possibly due to relatively poor load transfer between the fibers and the matrix. Importantly, the flexural strength of the bamboo fiber-polyester composites is 200% and 30% higher than the standard particleboard and medium density fiberboard, respectively used in the construction industry. It is expected that the results of this preliminary study will provide information to support the development and application of this new generation composites in housing and construction