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Maltez LC, Barbas LAL, Nitz LF, Pellegrin L, Okamoto MH, Sampaio LA, Monserrat JM, Garcia L. Oxidative stress and antioxidant responses in juvenile Brazilian flounder Paralichthys orbignyanus exposed to sublethal levels of nitrite. FISH PHYSIOLOGY AND BIOCHEMISTRY 2018; 44:1349-1362. [PMID: 29858712 DOI: 10.1007/s10695-018-0526-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2018] [Accepted: 05/23/2018] [Indexed: 06/08/2023]
Abstract
This study evaluated the effects of short-term exposure to sublethal levels of nitrite on oxidative stress parameters and histology of juvenile Brazilian flounder Paralichthys orbignyanus. An assessment of fish recovery was also performed. Fish were exposed to 0.08 (control), 5.72, 10.43, and 15.27 NO2-N mg L-1 for 10 days followed by the same recovery time. Gill, liver, and muscle samples were collected after 1, 5, and 10 days of exposure and after recovery for the measurement of antioxidant capacity against peroxyl radicals (ACAP), glutathione-S-transferase (GST) activity, content of non-protein (NPSH) and protein thiols (PSH), and lipid peroxidation levels by thiobarbituric acid-reactive substances (TBARS) content. Nitrite exposure induced alterations which compromised the overall antioxidant system (reduced ACAP and GST activity) and enhanced oxidative damage in lipids and proteins. Increases in GST activity and NPSH and PSH contents were also demonstrated. The recovery period allowed for resumption of basal levels for all (treatment 5.72 NO2-N mg L-1) or some of the evaluated parameters (other treatments). In conclusion, exposure to nitrite concentrations from 5.72 to 15.27 NO2-N mg L-1 induced oxidative stress and antioxidant responses in juvenile Brazilian flounder. The 10-day recovery period was sufficient for a complete resumption of basal physiological condition of fish exposed to concentrations of up to 5.72 NO2-N mg L-1.
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Affiliation(s)
- Lucas Campos Maltez
- Laboratório de Aquacultura Continental, Instituto de Oceanografia, Universidade Federal do Rio Grande - FURG, Rio Grande, RS, 96203-900, Brazil
| | - Luis André Luz Barbas
- Laboratório de Aquacultura de Espécies Tropicais, Instituto Federal de Educação Ciência e Tecnologia do Pará - Campus Castanhal, Castanhal, PA, Brazil
| | - Lilian Fiori Nitz
- Laboratório de Aquacultura Continental, Instituto de Oceanografia, Universidade Federal do Rio Grande - FURG, Rio Grande, RS, 96203-900, Brazil
| | - Lucas Pellegrin
- Laboratório de Aquacultura Continental, Instituto de Oceanografia, Universidade Federal do Rio Grande - FURG, Rio Grande, RS, 96203-900, Brazil
| | - Marcelo Hideo Okamoto
- Laboratório de Piscicultura Estuarina e Marinha, Instituto de Oceanografia, Universidade Federal do Rio Grande - FURG, Rio Grande, RS, Brazil
| | - Luís André Sampaio
- Laboratório de Piscicultura Estuarina e Marinha, Instituto de Oceanografia, Universidade Federal do Rio Grande - FURG, Rio Grande, RS, Brazil
| | - José Maria Monserrat
- Laboratório de Bioquímica Funcional de Organismos Aquáticos, Instituto de Oceanografia, Universidade Federal do Rio Grande - FURG, Rio Grande, RS, Brazil
| | - Luciano Garcia
- Laboratório de Aquacultura Continental, Instituto de Oceanografia, Universidade Federal do Rio Grande - FURG, Rio Grande, RS, 96203-900, Brazil.
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Maltez LC, Stringhetta GR, Enamorado AD, Okamoto MH, Romano LA, Monserrat JM, Sampaio LA, Garcia L. Ammonia exposure and subsequent recovery trigger oxidative stress responses in juveniles of Brazilian flounder Paralichthys orbignyanus. FISH PHYSIOLOGY AND BIOCHEMISTRY 2017; 43:1747-1759. [PMID: 28726029 DOI: 10.1007/s10695-017-0406-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Accepted: 07/05/2017] [Indexed: 06/07/2023]
Abstract
The effects of ammonia exposure and recovery on oxidative stress parameters and histology of juvenile Brazilian flounder Paralichthys orbignyanus were evaluated. The fish were exposed to 0.12, 0.28 and 0.57 mg NH3-N L-1, plus a control, for 10 days followed by the same recovery time in ammonia-free water. Gill, liver and muscle samples (n = 9) were collected after 1, 5 and 10 days of exposure and after recovery for oxidative stress analysis (antioxidant capacity against peroxyl radicals (ACAP); glutathione S-transferase (GST) activity; lipoperoxidation levels measured through thiobarbituric acid reactive substances (TBARS) content). For histological assessment, gill, liver and brain samples were collected. Exposure to all NH3-N concentrations induced different time- and dose-dependent changes in oxidative stress parameters. Reduced antioxidant capacity of the liver and muscle and enhanced TBARS levels in the gills and liver were demonstrated. Differently, a high ammonia concentration elicited lower hepatic TBARS levels. Enhanced GST activity in all organs and increased antioxidant capacity of the gills were also observed. No ammonia-induced histopathological effects were demonstrated. After recovery, most parameters (liver ACAP, GST activity in the muscle and liver and TBARS in the gills) returned to baseline levels. However, liver TBARS and gill GST activity remained altered 0.57 mg NH3-N L-1 treatment. The recovery period also led to a decrease in gill antioxidant capacity and an increase in muscle antioxidant capacity. In conclusion, a concentration of 0.12 mg NH3-N L-1 induces oxidative stress and antioxidant responses in juvenile Brazilian flounder. Moreover, a 10-day recovery period is not sufficient to restore fish homeostasis.
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Affiliation(s)
- Lucas Campos Maltez
- Laboratório de Aquacultura Continental, Instituto de Oceanografia, Universidade Federal do Rio Grande - FURG, Rio Grande, RS, 96201-900, Brazil
| | - Giovanna Rodrigues Stringhetta
- Laboratório de Aquacultura Continental, Instituto de Oceanografia, Universidade Federal do Rio Grande - FURG, Rio Grande, RS, 96201-900, Brazil
| | - Alain Danilo Enamorado
- Laboratório de Bioquímica Funcional de Organismos Aquáticos, Universidade Federal do Rio Grande - FURG, Rio Grande, RS, Brazil
| | - Marcelo Hideo Okamoto
- Laboratório de Piscicultura Estuarina e Marinha, Instituto de Oceanografia, Universidade Federal do Rio Grande - FURG, Rio Grande, RS, Brazil
| | - Luis Alberto Romano
- Laboratório de Imunologia e Patologia de Organismos Aquáticos, Instituto de Oceanografia, Universidade Federal do Rio Grande - FURG, Rio Grande, RS, Brazil
| | - José María Monserrat
- Laboratório de Bioquímica Funcional de Organismos Aquáticos, Universidade Federal do Rio Grande - FURG, Rio Grande, RS, Brazil
| | - Luís André Sampaio
- Laboratório de Piscicultura Estuarina e Marinha, Instituto de Oceanografia, Universidade Federal do Rio Grande - FURG, Rio Grande, RS, Brazil
| | - Luciano Garcia
- Laboratório de Aquacultura Continental, Instituto de Oceanografia, Universidade Federal do Rio Grande - FURG, Rio Grande, RS, 96201-900, Brazil.
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Garcia LDO, Okamoto MH, Riffel APK, Saccol EM, Pavanato MA, Sampaio LAN. Oxidative stress parameters in juvenile Brazilian flounder Paralichthys orbignyanus (Valenciennes, 1839) (Pleuronectiformes: Paralichthyidae) exposed to cold and heat shocks. NEOTROPICAL ICHTHYOLOGY 2015. [DOI: 10.1590/1982-0224-20140148] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The aim of this study was to determine oxidative stress parameters in the liver and gill of Brazilian flounder juveniles (307.0 ± 16.0 g and 30.0 ± 4.0 cm) submitted to different water temperature (17.1, 23.0 and 28.8ºC) for 72 h and maintained at salinity 25‰. After the acclimation of 7 days, in 23ºC, fish were transferred to 200 L tanks containing seawater (salinity 25‰) at 28.8ºC (heat shock), 17.1ºC (cold shock) or 23.0ºC (control), five replicates (five fish tank-1). The sampled collection occurred in 0 (pre-challenge), 3, 24, 48 and 72 h after temperature shock. Flounder exposed to 17.1ºC and 28.8ºC showed significantly higher TBARS levels and GST activity in the liver post-exposition (PE) in relation to the control (23ºC). CAT activity in liver present a significantly increase at 17.1ºC, in first 48 h, and subsequently decrease in 72 h PE in relation to 28.8ºC. The gills of flounder showed significantly higher TBARS levels, GST and CAT activity when submitted at 17.1 and 28.8ºC in relation to 23.0ºC. There were observed changes in lipid peroxidation levels (LPO), CAT and GST activities in the liver and gill of Brazilian flounder in response to reactive oxygen species (ROS) produced by thermal shocks.
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Sinha AK, AbdElgawad H, Zinta G, Dasan AF, Rasoloniriana R, Asard H, Blust R, De Boeck G. Nutritional Status as the Key Modulator of Antioxidant Responses Induced by High Environmental Ammonia and Salinity Stress in European Sea Bass (Dicentrarchus labrax). PLoS One 2015; 10:e0135091. [PMID: 26241315 PMCID: PMC4524602 DOI: 10.1371/journal.pone.0135091] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2015] [Accepted: 07/17/2015] [Indexed: 01/18/2023] Open
Abstract
Salinity fluctuation is one of the main factors affecting the overall fitness of marine fish. In addition, water borne ammonia may occur simultaneously with salinity stress. Additionally, under such stressful circumstances, fish may encounter food deprivation. The physiological and ion-osmo regulatory adaptive capacities to cope with all these stressors alone or in combination are extensively addressed in fish. To date, studies revealing the modulation of antioxidant potential as compensatory response to multiple stressors are rather lacking. Therefore, the present work evaluated the individual and combined effects of salinity challenge, ammonia toxicity and nutritional status on oxidative stress and antioxidant status in a marine teleost, European sea bass (Dicentrarchus labrax). Fish were acclimated to normal seawater (32 ppt), to brackish water (20 ppt and 10 ppt) and to hypo-saline water (2.5 ppt). Following acclimation to different salinities for two weeks, fish were exposed to high environmental ammonia (HEA, 20 mg/L representing 50% of 96h LC50 value for ammonia) for 12 h, 48 h, 84 h and 180 h, and were either fed (2% body weight) or fasted (unfed for 7 days prior to HEA exposure). Results show that in response to decreasing salinities, oxidative stress indices such as xanthine oxidase activity, levels of hydrogen peroxide (H2O2) and lipid peroxidation (malondialdehyde, MDA) increased in the hepatic tissue of fasted fish but remained unaffected in fed fish. HEA exposure at normal salinity (32 ppt) and at reduced salinities (20 ppt and 10 ppt) increased ammonia accumulation significantly (84 h–180 h) in both feeding regimes which was associated with an increment of H2O2 and MDA contents. Unlike in fasted fish, H2O2 and MDA levels in fed fish were restored to control levels (84 h–180 h); with a concomitant increase in superoxide dismutase (SOD), catalase (CAT), components of the glutathione redox cycle (reduced glutathione, glutathione peroxidase and glutathione reductase), ascorbate peroxidase (APX) activity and reduced ascorbate (ASC) content. On the contrary, fasted fish could not activate many of these protective systems and rely mainly on CAT and ASC dependent pathways as antioxidative sentinels. The present findings exemplify that in fed fish single factors and a combination of HEA exposure and reduced seawater salinities (upto 10 ppt) were insufficient to cause oxidative damage due to the highly competent antioxidant system compared to fasted fish. However, the impact of HEA exposure at a hypo-saline environment (2.5 ppt) also defied antioxidant defence system in fed fish, suggesting this combined factor is beyond the tolerance range for both feeding groups. Overall, our results indicate that the oxidative stress mediated by the experimental conditions were exacerbated during starvation, and also suggest that feed deprivation particularly at reduced seawater salinities can instigate fish more susceptible to ammonia toxicity.
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Affiliation(s)
- Amit Kumar Sinha
- Systemic Physiological and Ecotoxicological Research, Department of Biology, University of Antwerp, Antwerp, Belgium
| | - Hamada AbdElgawad
- Molecular Plant Physiology and Biotechnology group, Department of Biology, University of Antwerp, Antwerp, Belgium; Department of Botany, Faculty of Science, University of Beni-Sueif, Beni-Sueif, Egypt
| | - Gaurav Zinta
- Molecular Plant Physiology and Biotechnology group, Department of Biology, University of Antwerp, Antwerp, Belgium
| | - Antony Franklin Dasan
- Systemic Physiological and Ecotoxicological Research, Department of Biology, University of Antwerp, Antwerp, Belgium
| | - Rindra Rasoloniriana
- Systemic Physiological and Ecotoxicological Research, Department of Biology, University of Antwerp, Antwerp, Belgium
| | - Han Asard
- Molecular Plant Physiology and Biotechnology group, Department of Biology, University of Antwerp, Antwerp, Belgium
| | - Ronny Blust
- Systemic Physiological and Ecotoxicological Research, Department of Biology, University of Antwerp, Antwerp, Belgium
| | - Gudrun De Boeck
- Systemic Physiological and Ecotoxicological Research, Department of Biology, University of Antwerp, Antwerp, Belgium
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Sinha AK, Rasoloniriana R, Dasan AF, Pipralia N, Blust R, De Boeck G. Interactive effect of high environmental ammonia and nutritional status on ecophysiological performance of European sea bass (Dicentrarchus labrax) acclimated to reduced seawater salinities. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2015; 160:39-56. [PMID: 25625520 DOI: 10.1016/j.aquatox.2015.01.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Revised: 01/04/2015] [Accepted: 01/07/2015] [Indexed: 06/04/2023]
Abstract
We investigated the interactive effect of ammonia toxicity, salinity challenge and nutritional status on the ecophysiological performance of European sea bass (Dicentrarchus labrax). Fish were progressively acclimated to normal seawater (32ppt), to brackish water (20ppt and 10ppt) and to hyposaline water (2.5ppt). Following acclimation to different salinities for two weeks, fish were exposed to high environmental ammonia (HEA, 20mg/L ∼1.18mM representing 50% of 96h LC50 value for ammonia) for 12h, 48h, 84h and 180h, and were either fed (2% body weight) or fasted (unfed for 7 days prior to HEA exposure). Biochemical responses such as ammonia (Jamm) and urea excretion rate, plasma ammonia, urea and lactate, plasma ions (Na(+), Cl(-) and K(+)) and osmolality, muscle water content (MWC) and liver and muscle energy budget (glycogen, lipid and protein), as well as branchial Na(+)/K(+)-ATPase (NKA) and H(+)-ATPase activity, and branchial mRNA expression of NKA and Na(+)/K(+)/2Cl(-) co-transporter (NKCC1) were investigated in order to understand metabolic and ion- osmoregulatory consequences of the experimental conditions. During HEA, Jamm was inhibited in fasted fish at 10ppt, while fed fish were still able to excrete efficiently. At 2.5ppt, both feeding groups subjected to HEA experienced severe reductions and eventually a reversion in Jamm. Overall, the build-up of plasma ammonia in HEA exposed fed fish was much lower than fasted ones. Unlike fasted fish, fed fish acclimated to lower salinities (10ppt-2.5ppt) could maintain plasma osmolality, [Na(+)], [Cl(-)] and MWC during HEA exposure. Thus fed fish were able to sustain ion-osmotic homeostasis which was associated with a more pronounced up-regulation in NKA expression and activity. At 2.5ppt both feeding groups activated H(+)-ATPase. The expression of NKCC1 was down-regulated at lower salinities in both fed and fasted fish, but was upregulated within each salinity after a few days of HEA exposure. Though an increment in plasma lactate content and a decline in energy stores were noted for both feeding regimes, the effect was more severe in feed deprived fish. Overall, several different physiological processes were disturbed in fasted sea bass during HEA exposure while feeding alleviated adverse effects of high ammonia and salinity challenge. This suggests that low food availability can render fish more vulnerable to external ammonia, especially at reduced seawater salinities.
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Affiliation(s)
- Amit Kumar Sinha
- Systemic Physiological and Ecotoxicological Research, Department of Biology, University of Antwerp, Groenenborgerlaan 171, BE-2020 Antwerp, Belgium.
| | - Rindra Rasoloniriana
- Systemic Physiological and Ecotoxicological Research, Department of Biology, University of Antwerp, Groenenborgerlaan 171, BE-2020 Antwerp, Belgium
| | - Antony Franklin Dasan
- Systemic Physiological and Ecotoxicological Research, Department of Biology, University of Antwerp, Groenenborgerlaan 171, BE-2020 Antwerp, Belgium
| | - Nitin Pipralia
- Systemic Physiological and Ecotoxicological Research, Department of Biology, University of Antwerp, Groenenborgerlaan 171, BE-2020 Antwerp, Belgium
| | - Ronny Blust
- Systemic Physiological and Ecotoxicological Research, Department of Biology, University of Antwerp, Groenenborgerlaan 171, BE-2020 Antwerp, Belgium
| | - Gudrun De Boeck
- Systemic Physiological and Ecotoxicological Research, Department of Biology, University of Antwerp, Groenenborgerlaan 171, BE-2020 Antwerp, Belgium
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Martins SE, Bianchini A. Toxicity tests aiming to protect Brazilian aquatic systems: current status and implications for management. ACTA ACUST UNITED AC 2011; 13:1866-75. [PMID: 21643562 DOI: 10.1039/c0em00787k] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The current status of toxicological tests performed with Brazilian native species was evaluated through a survey of the scientific data available in the literature. The information gathered was processed and an electronic toxicology database (http://www.inct-ta.furg.br/bd_toxicologico.php) was generated. This database provides valuable information for researchers to select sensitive and tolerant aquatic species to a large variety of aquatic pollutants. Furthermore, the toxicology database allows researchers to select species representative of an ecosystem of interest. Analysis of the toxicology database showed that ecotoxicological assays have significantly improved in Brazil over the last decade, in spite of the still relatively low number of tests performed and the restricted number of native species tested. This is because most of the research is developed in a few laboratories concentrated in certain regions of Brazil, especially in Southern and Southeast regions. Considering the extremely rich biodiversity and the large variety of aquatic ecosystems in Brazil, this finding points to the urgent need for the development of ecotoxicological studies with other groups of aquatic animals, such as insects, foraminifera, cnidarians, worms, amphibians, among others. This would help to derive more realistic water quality criteria (WQC) values, which would better protect the different aquatic ecosystems in Brazil. Finally, the toxicology database generated presents solid and science based information, which can encourage and drive the Environmental Regulatory Agencies in Brazil to derive WQC based on native species. In this context, the present paper discusses the historical evolution of ecotoxicological studies in Brazil, and how they have contributed to the improvement of the Brazilian Federal and Regional regulations for environment.
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Affiliation(s)
- Samantha Eslava Martins
- Universidade Federal do Rio Grande-FURG, Instituto de Ciências Biológicas, Av. Itália km 8-CEP, 96201-900, Rio Grande, RS, Brazil
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Lima RLD, Braun N, Kochhann D, Lazzari R, Radünz Neto J, Moraes BS, Loro VL, Baldisserotto B. Survival, growth and metabolic parameters of silver catfish, Rhamdia quelen, juveniles exposed to different waterborne nitrite levels. NEOTROPICAL ICHTHYOLOGY 2011. [DOI: 10.1590/s1679-62252011005000004] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
High nitrite (NO2-) levels may develop in aquaculture systems due to high fish density, but studies of lethal concentration values and the effect of NO2- on metabolic parameters and growth are scarce. Consequently, in this study was verified the lethal concentration at 96 h (LC50-96h) for (NO2-) in juvenile silver catfish, Rhamdia quelen and the effect of four waterborne NO2- concentrations (0.06, 0.46, 1.19, and 1.52 mg.L-1) on growth, and hepatic and muscular lactate, glucose, glycogen and protein. Nitrite LC50-96h was 20.46 (confidence interval: 16.10-23.68) mg.L-1. In the growth experiment, exposure to NO2- did not affect weight, length or specific growth rate, but due to mortality (66.7% and 100% after 20 and 40 days, respectively), biomass of juveniles exposed to 1.52 mg.L-1 NO2- was significantly lower than the biomass of juveniles exposed to other treatments. Therefore, the safe level of nitrite for growth of silver catfish juveniles is below 1.19 mg.L-1 (2% of LC50-96h). Exposure of silver catfish to NO2- for 40 days reduced lactate levels in muscle, but lactate levels increased in liver tissue of fish maintained at 1.19 mg.L-1 NO2-. In addition, glucose levels in muscle and liver tissues were significantly lower in silver catfish exposed to the highest NO2- level. These results indicate that chronic NO2- exposure causes anaerobic substrate oxidation to meet energy demand.
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Affiliation(s)
| | - Neiva Braun
- Universidade Federal de Santa Catarina, Brazil
| | | | - Rafael Lazzari
- Centro de Educação Superior Norte do Rio Grande do Sul, Brazil
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Campos VF, Collares T, Deschamps JC, Seixas FK, Dellagostin OA, Lanes CFC, Sandrini J, Marins LF, Okamoto M, Sampaio LA, Robaldo RB. Identification, tissue distribution and evaluation of brain neuropeptide Y gene expression in the Brazilian flounder Paralichthys orbignyanus. J Biosci 2010; 35:405-13. [DOI: 10.1007/s12038-010-0046-y] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Meier KM, Figueiredo MA, Kamimura MT, Laurino J, Maggioni R, Pinto LS, Dellagostin OA, Tesser MB, Sampaio LA, Marins LF. Increased growth hormone (GH), growth hormone receptor (GHR), and insulin-like growth factor I (IGF-I) gene transcription after hyperosmotic stress in the Brazilian flounder Paralichthys orbignyanus. FISH PHYSIOLOGY AND BIOCHEMISTRY 2009; 35:501-509. [PMID: 19082753 DOI: 10.1007/s10695-008-9287-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2008] [Accepted: 10/26/2008] [Indexed: 05/27/2023]
Abstract
Growth hormone (GH) action is the result of an intracellular cascade initiated just after its interaction with the growth hormone receptor (GHR) located on the surface of target cells. This cascade culminates with the transcription of target genes, such as the insulin-like growth factors (IGFs), which are responsible for most GH biological effects. In addition to its central role in growth, fish GH is also involved with osmoregulatory control. Within this context, the objective of the present work was to isolate GH, GHR, and IGF-I cDNAs from the Brazilian flounder Paralichthys orbignyanus and evaluate whether these genes are induced by hyperosmotic stress. The obtained results indicated that GH mRNA had a significant peak only 24 h after hyperosmotic stress. In gills, GHR mRNA was significantly increased after 7 days. In liver, GHR and IGF-I mRNAs were significantly increased in 72 h and both reached even higher levels after 7 days. These results indicate that hyperosmotic stress can increase GH sensitivity in the gills and liver of P. orbignyanus and, consequently, improve IGF-I production. The management of this parameter could be useful in achieving better growth performance for this and other commercially important species in which GH has a direct correlation with osmoregulatory mechanisms.
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Affiliation(s)
- Karina M Meier
- Instituto de Ciências Biológicas, Universidade Federal do Rio Grande-FURG, Rio Grande, RS, Brazil
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