Molecular effects of Microcystin-LA in tilapia (Oreochromis niloticus). (August 2019)

• Record Type: Journal Article
• Authors: Moreira, Daniel A.; Soares, Raquel M.; Valente, Richard H.; Bebianno, Maria J.; Rebelo, Mauro F.
• Is Part Of: Toxicon. Volume 166(2019)
• Page Start: 76
• Page End: 82
• Publication Date: 2019-08
• Subjects: Cyanotoxins -- Protein phosphatase -- Glutathione peroxidase -- Gene expression; Toxins -- Periodicals; Venom -- Periodicals; 615.9
• DOI: 10.1016/j.toxicon.2019.05.002
• Languages: English
• ISSNs: 0041-0101

Abstract

Abstract: Nile tilapia ( Oreochromis niloticus ) is a freshwater phytoplanktivorous fish species reported to accumulate and tolerate large amounts of cyanotoxins such as microcystins (MCs). The present study aimed to investigate molecular responses to the acute exposure of Nile tilapia to the Microcystin-LA analogue (MC-LA). Thus, the specimens were sublethally exposed to 1000 μg kg −1 of MC-LA for 12, 24, 48, and 96 h. Gene expression of PP1, PP2A, GST, GPX and actin was analyzed by quantitative PCR. The protein abundance profile of PP2A was determined by immunoblotting, while the integrity of its biological function was assessed by a phosphatase enzymatic assay. PP2A activity was significantly and strongly reduced by MC-LA. A resulting feedback mechanism significantly increased PP2A gene expression and protein abundance in all assessed times. However, a recovery of that phosphatase activity was not observed. In this study, the observed increase in GPX gene expression was the only response that could be directly related to the unknown factors associated to the fish survival to such high dose exposure. Highlights: Tilapia survived to MC-LA high dose, even presenting a strong inhibition of PP2A. PP2A inhibition leads to an increase in the transcription and translation of this protein. GPX mRNA increasing could be related to the fish survival to such high dose exposure.