Approved Abstracts

Transcriptional effects of 4-n-Nonylphenol in the guppy Poecilia vivipara

Author(s): Piazza, CE; Mattos, JJ; Brocardo, GS; Bainy, ACD;
Presenter: Clei Endrigo Piazza

The estuarine guppy, Poecilia vivipara, has been used as an important sentinel for monitoring environmental contamination in mangrove and estuarine areas. These sites are considered hotspots of environmental contamination by several types of effluents, mainly, sanitary sewage. Among the chemical compounds present in sewage, there is a class of highly toxic nonionic surfactants: ethoxylated alkylphenols (APEOs). APEOs are widely used in the production of various chemicals. There is a growing concern about APEOs in the environment because their metabolites are less biodegradable, more lipophilic, and toxic than their precursors and mimic hormones. 4-n-Nonylphenol (NP) is identified as the most critical metabolite of APEOs. Due to its vast industrial and domestic use, Nonylphenol (NP) is globally found in the aquatic environment due to industrial effluents, raw sanitary sewage and effluents discharges from sewage treatment plants. In this context, the main goal of this study was to evaluate the transcriptional effects of genes related to phase I and II biotransformation system, antioxidant defense and endocrine disruption pathways in liver of fish injected intraperitoneally with NP. Guppies separated by sex were injected with two doses of NP (15 µg/g and 150 µg/g) or peanut oil (vehicle) as control, in triplicate glass aquaria for 24 h (n=12 for each group). After 24 h, fish were euthanized, the livers were excised and frozen in liquid nitrogen. Total RNA was extracted for cDNA synthesis and subsequent qPCR reactions. The following genes were evaluated: Aryl Hidrocarbon Receptor (AhR), Estrogen Nuclear Receptor Alpha (ER), Pregnane X Receptor (PXR), Cytochromes P450 (CYP1A, CYP2K1 and CYP3A30), Glutathione S-transferase A3 and Mu 3 (GSTa3 and GSTMu3), SRY-Box Transcription Factor 9 (SOX9), Vitellogenin-1 (VIT), Zona Pellucida Sperm-Binding Protein 4 (ZP4), ATP Binding Cassette Subfamily C Member 1 (ABCC1), Multidrug Resistance-Associated Protein 2 (MRP2), UDP Glucuronosyltransferase Family 1 Member A1 (UGT1A1). In female fishes, the transcript levels of the nuclear receptor genes AhR and PXR where 2.7-fold and 2-fold higher in the lower dose group (15 µg/g) compared to control, respectively. The genes involved in phase I biotransformation did not show changes among groups. In the females exposed to the lower dose, phase II biotransformation gene GSTa3 showed a 2.6-fold higher transcript levels than the control. No changes were observed for ABC transporter genes (ABCC1 and MRP2). The SOX9 gene involved in endocrine disruption showed a 2.1-fold higher transcription in the lower dose group compared to the control. In male fishes, no changes in transcript levels were observed for the nuclear receptors (AhR, PXR and ER) and phase I biotransformation genes (CYP1A1, CYP2K1 and CYP3A30). However, GSTa3 showed 1.8-fold and 1.4-fold less transcripts in the males injected with the lower (15 µg/g) and higher (150 µg/g) dose groups, respectively. ABCC1 transcript levels in liver of guppies injected with the lower dose was 2-fold higher than control group, while MRP2 showed 1.7-fold less transcripts than control in the same group. No changes were observed in the genes related to endocrine disruption. The exposure to NP at two environmentally relevant concentrations was sufficient to cause transcriptional changes in guppies’ livers. These short-term and low-dose changes observed can serve as early indicators of deleterious processes. Together, the results highlighted P. vivipara as a suitable organism to be used as sentinel in biomonitoring programs.
Supported by CNPq Universal 425840/2016-6

Keywords: 4-n-Nonylphenol; Poecilia vivipara; Transcription




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