Abstract
A multi-method approach was employed to compare the responses of Glutatione Transferases (GSTs) in the gills and hepatopancreas of Venerupis philippinarum to microcystins (MCs) toxicity. In this way, using the cytosolic fraction, the enzymatic activity of GSTs, superoxide dismutase (SOD), serine/threonine protein phosphatases (PPP2) along with the gene expression levels of four GST isoforms (pi, mu, sigma1, sigma2) were investigated in both organs of the clams exposed for 24 h to 10, 50 and 100 μg L−1 of MC-LR. Cytosolic GSTs (cGSTs) from both organs of the high dose exposed clams were purified by glutathione-agarose affinity chromatography, characterized kinetically and the changes in the expression of cGSTs of the gills identified using a proteomic approach. MC-LR caused an increase in GST enzyme activity, involved in conjugation reactions, in both gills and hepatopancreas (100 μg L−1 exposure). SOD activity, an indicator of oxidative stress, showed significantly elevated levels in the hepatopancreas only (50 and 100 μg L−1 exposure). No significant changes were found in PPP2 activity, the main target of MCs, for both organs. Transcription responses revealed an up-regulation of sigma2 in the hepatopancreas at the high dose, but no significant changes were detected in the gills. Kinetic analysis evidenced differences between gills of exposed and non-exposed extracts. Using proteomics, qualitative and quantitative differences were found between the basal and inducible cGSTs. Overall, results suggest a distinct role of GST system in counteracting MCs toxicity between the gills and the hepatopancreas of V. philippinarum, revealing different roles between GST isoforms within and among both organs.
Highlights
Cyanobacteria are a well-known source of environmental contamination and water-related concerns in the industrial sector, with worldwide occurrence records [1]
(1.5-fold for both organs) in relation to control was detected for the high dose exposed group
A significant increase in GST activity has been shown for both organs upon exposure to the high MC-LR dose group
Summary
Cyanobacteria are a well-known source of environmental contamination and water-related concerns in the industrial sector, with worldwide occurrence records [1]. Microcystis aeruginosa, a common microcystin (MC) producer, is an example of such that can form extensive blooms in freshwater and estuarine habitats [2]. There are numerous accounts of these toxins’ presence in water bodies around the world. Among the several toxin congeners, the most commonly produced cyanotoxin is microcystin-LR (MC-LR) [3,4]. This toxin is considered a public health issue mainly in freshwater, MC-LR has already been found in marine habitats. MC-LR has been identified in mussels from different regions such as the Northeastern Pacific, European and eastern
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
