Antioxidant responses of microalgal species to pyrene

Abstract

The antioxidant response of four freshwater microalgal species, Chlorella vulgaris Beij., Scenedesmus platydiscus (G. M. Smith) Chod., Scenedesmus quadricauda(Turp.) Bréb., and Selenastrum capricornutum Printz without pyrene addition (control) and at two pyrene concentrations (0.1 and 1.0 mgL −1 ) were investigated. Under the control condition, the values of the antioxidant parameters differed significantly among species and the difference was seemed not to be related to their susceptibility to pyrene. The antioxidant response to pyrene treatments also varied from species to species. Pyrene led to a significant increase in total glutathione (GSH) content in all species except C. vulgaris, a species did not exhibit any ability to metabolize pyrene. The glutathione-S-transferase (GST) activities also remained unchanged in pyrene treated C. vulgaris, increased greatly in S. platydiscus and Se. capricornutum (the two species with higher pyrene metabolism ability), but inhibited remarkably in S. quadricauda (the only species sensitive to pyrene toxicity). On the other hand, the glutathione reductase (GR) activities increased in C. vulgaris but remained at a similar level as the control in the other three species. The malondialdehyde (MDA) content, an indicator of lipid peroxidation, declined in S. quadricauda but showed no significant change in the other three species. The activities of glutathione peroxidase (GPX), superoxide dismutase (SOD) and catalase (CAT) in pyrene treated cells remained almost the same as the controls for all microalgal species. Results suggested that the alterations of antioxidant systems in microalgae might not be useful indicators of pyrene exposure but pyrene-enhanced GSH metabolism might be important in pyrene biotransformation.

Combined toxicity of polycyclic aromatic hydrocarbons and heavy metals to biochemical and antioxidant responses of free and immobilized Selenastrum capricornutum

“…The present study revealed that mixed PAHs alone did not have any significant effect on the growth of free S. capricornutum cells but induced the production of reduced GSH and POD activities. Similarly, these two antioxidant responses of S. capricornutum were stimulated by nonylphenol [41], while PYR enhanced the GSH content of four freshwater microalgae, C. vulgaris, Scenedesmus platydiscus, Scenedesmus quadricauda, and Selenastrum capricornutum, but had no effect on their SOD activities [11]. The combined effects of PAHs and heavy metals on free S. capricornutum cells in the present study were more significant than those of a single group of contaminants.…”

“…The major watersoluble antioxidant in plant and algae is GSH, which directly reduces most of the ROS [9] or acts as a cofactor or a substrate in the enzymatic reactions involved in controlling cellular ROS levels [10]. An increase in GSH content indicates a protective response to various environmental stresses [9,11]. The GSH content and SOD activity in microalgal cells were also found to increase with the increasing stress posed by single types of contaminants, such as metals or PAHs [11,12].…”

“…An increase in GSH content indicates a protective response to various environmental stresses [9,11]. The GSH content and SOD activity in microalgal cells were also found to increase with the increasing stress posed by single types of contaminants, such as metals or PAHs [11,12]. However, most of these studies were mainly on the toxicity of single contaminants; research on the combined toxic effects of more than one group of contaminants in microalgae is limited [13,14].…”

Responses of Synechocystis sp. PCC 6803 (cyanobacterium) photosystem II to pyrene stress

“…Pyrene is a four-ring containing PAH, and it is also one of most common PAHs in various environments. The toxicities of pyrene toward a wide range of organisms, including mussels (Okay et al, 2006), fish (Roling et al, 2004;Zapata-Pérez et al, 2002), copepods (Jensen et al, 2008), macrophytes (Yin et al, 2008) and eukaryotic algae (Djomo et al, 2004;Lei et al, 2006) have been studied. However, there is little information about the effects of pyrene on cyanobacteria which is one of most important prokaryotic organisms in aquatic ecosystem.…”

Assessment of cellular reduced glutathione content in Pseudokirchneriella subcapitata using monochlorobimane

“…Usually these techniques involve a cell lysis step followed by glutathione quantification using enzymatic or chromatographic methods (ion-exchange chromatography or high-performance liquid chromatography; Anderson 1985;Le Faucheur et al 2005; Lei et al 2006;Yang et al 2011). These procedures are labour-intensive and expensive.…”