title: The biological importance of glutathione peroxidase and peroxiredoxin backup systems in bivalves during peroxide exposure.
abstract: Organic peroxide elimination in eukaryotes essentially depends on glutathione peroxidase (GPx) and peroxiredoxin (Prx) enzymes, which are supported by their respective electron donors, glutathione (GSH) and thioredoxin (Trx). This system depends on the ancillary enzymes glutathione reductase (GR) and thioredoxin reductase (TrxR) to maintain GSH and Trx in their reduced state. This study discusses the biological importance of GR and TrxR in supporting GPx and Prx during cumene hydroperoxide (CHP) exposure in brown mussel Perna perna. ZnCl2 or 1-chloro-2,4-dinitrobenze (CDNB) was used to decrease GR and TrxR activities in gills, as already reported with mammals and bivalves. ZnCl2 exposure lowered GR activity (28%), impaired the in vivo CHP decomposition and decreased the survival rates under CHP exposure. CDNB decreased GR (54%) and TrxR (73%) activities and induced glutathione depletion (99%), promoting diminished peroxide elimination and survival rates at a greater extent than ZnCl2. CDNB also increased the susceptibility of hemocytes to CHP toxicity. Despite being toxic and causing mortality at longer exposures, short (2 h) exposure to CHP promoted an up regulation of GSH (50 and 100 μM CHP) and protein-thiol (100 μM CHP) levels, which was blocked by ZnCl2 or CDNB pre-exposure. Results highlight the biological importance of GSH, GR and TrxR in supporting GPx and Prx activities, contributing to organic peroxides elimination and mussel survival under oxidative challenges. To our knowledge, this is the first work that demonstrates, albeit indirectly, the biological importance of GPx/GR/GSH and Prx/TrxR/Trx systems on in vivo organic peroxide elimination in bivalves.
authors.affiliation: Biochemistry Department, Federal University of Santa Catarina, Florianópolis 88040-900, Brazil. Electronic address: rafael.trevisan@gmail.com.
authors.forename: Rafael
authors.initials: R
authors.lastname: Trevisan
authors.affiliation: Biochemistry Department, Federal University of Santa Catarina, Florianópolis 88040-900, Brazil.
authors.forename: Danielle Ferraz
authors.initials: DF
authors.lastname: Mello
authors.affiliation: Biochemistry Department, Federal University of Santa Catarina, Florianópolis 88040-900, Brazil.
authors.forename: Marcela
authors.initials: M
authors.lastname: Uliano-Silva
authors.affiliation: Biochemistry Department, Federal University of Santa Catarina, Florianópolis 88040-900, Brazil.
authors.forename: Gabriel
authors.initials: G
authors.lastname: Delapedra
authors.affiliation: Biochemistry Department, Federal University of Santa Catarina, Florianópolis 88040-900, Brazil.
authors.forename: Miriam
authors.initials: M
authors.lastname: Arl
authors.affiliation: Biochemistry Department, Federal University of Santa Catarina, Florianópolis 88040-900, Brazil.
authors.forename: Alcir Luiz
authors.initials: AL
authors.lastname: Dafre
mesh_terms: D000818:Animals; D001555:Benzene Derivatives / Q000378:metabolism / Q000633:toxicity*; D002712:Chlorides / Q000494:pharmacology; D004137:Dinitrochlorobenzene / Q000494:pharmacology; D004781:Environmental Exposure; D005979:Glutathione Peroxidase / Q000378:metabolism / Q000502:physiology*; D006706:Homeostasis; D049883:Perna / Q000187:drug effects / Q000201:enzymology*; D054464:Peroxiredoxins / Q000378:metabolism*; D013438:Sulfhydryl Compounds / Q000378:metabolism; D018675:Toxicity Tests; D017967:Zinc Compounds / Q000494:pharmacology
chemical_list: D001555:Benzene Derivatives; D002712:Chlorides; D004137:Dinitrochlorobenzene; D013438:Sulfhydryl Compounds; D017967:Zinc Compounds; C016837:zinc chloride; D054464:Peroxiredoxins; D005979:Glutathione Peroxidase; C007164:cumene hydroperoxide
keywords: Antioxidants; Cumene hydroperoxide; Gills; Glutathione reductase; Mussels; Oxidative stress; Perna perna; Thioredoxin reductase