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Gregório SF, Ruiz-Jarabo I, Carvalho EM, Fuentes J. Increased intestinal carbonate precipitate abundance in the sea bream (Sparus aurata L.) in response to ocean acidification. PLoS One 2019; 14:e0218473. [PMID: 31226164 PMCID: PMC6588277 DOI: 10.1371/journal.pone.0218473] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Accepted: 06/03/2019] [Indexed: 12/20/2022] Open
Abstract
Marine fish contribute to the carbon cycle by producing mineralized intestinal precipitates generated as by-products of their osmoregulation. Here we aimed at characterizing the control of epithelial bicarbonate secretion and intestinal precipitate presence in the gilthead sea bream in response to predicted near future increases of environmental CO2. Our results demonstrate that hypercapnia (950 and 1800 μatm CO2) elicits higher intestine epithelial HCO3- secretion ex vivo and a subsequent parallel increase of intestinal precipitate presence in vivo when compared to present values (440 μatm CO2). Intestinal gene expression analysis in response to environmental hypercapnia revealed the up-regulation of transporters involved in the intestinal bicarbonate secretion cascade such as the basolateral sodium bicarbonate co-transporter slc4a4, and the apical anion transporters slc26a3 and slc26a6 of sea bream. In addition, other genes involved in intestinal ion uptake linked to water absorption such as the apical nkcc2 and aquaporin 1b expression, indicating that hypercapnia influences different levels of intestinal physiology. Taken together the current results are consistent with an intestinal physiological response leading to higher bicarbonate secretion in the intestine of the sea bream paralleled by increased luminal carbonate precipitate abundance and the main related transporters in response to ocean acidification.
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Affiliation(s)
- Sílvia F. Gregório
- Centre of Marine Sciences (CCMar), Universidade do Algarve, Campus de Gambelas, Faro, Portugal
| | - Ignacio Ruiz-Jarabo
- Centre of Marine Sciences (CCMar), Universidade do Algarve, Campus de Gambelas, Faro, Portugal
| | - Edison M. Carvalho
- Centre of Marine Sciences (CCMar), Universidade do Algarve, Campus de Gambelas, Faro, Portugal
| | - Juan Fuentes
- Centre of Marine Sciences (CCMar), Universidade do Algarve, Campus de Gambelas, Faro, Portugal
- * E-mail:
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Alves A, Gregório SF, Egger RC, Fuentes J. Molecular and functional regionalization of bicarbonate secretion cascade in the intestine of the European sea bass (Dicentrarchus labrax). Comp Biochem Physiol A Mol Integr Physiol 2019; 233:53-64. [PMID: 30946979 DOI: 10.1016/j.cbpa.2019.03.017] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Revised: 03/20/2019] [Accepted: 03/25/2019] [Indexed: 10/27/2022]
Abstract
In marine fish the intestinal HCO3- secretion is the key mechanism to enable luminal aggregate formation and water absorption. Using the sea bass (Dicentrarchus labrax), the present study aimed at establishing the functional and molecular organization of different sections of the intestine concerning bicarbonate secretion and Cl- movements. The proximal intestinal regions presented similar HCO3- secretion rates, while differences were detected in the molecular expression of the transporters involved and on regional HCO3- concentrations. The anterior region presented significantly higher Na+/K+-ATPase activity, Cl- transepithelial transport and basolateral slc4a4, apical slc26a6 and slc26a3 expression levels. In the mid intestine, the total HCO3- content was significantly increased in the fluid as in the carbonate aggregates. In the rectum no HCO3- secretion was observed and was characterized by the diminished HCO3- total content, residual molecular expression of slc4a4, slc26a6 and slc26a3, higher H+-ATPase activity and expression, suggesting the existence of a different bicarbonate handling mechanism. The possible regulation of HCO3- secretion by extracellular HCO3- and increased intracellular cAMP levels were also investigated. cAMP did not affect HCO3- secretion, although Cl- secretion was enhanced by cftr. HCO3- secretion rise due to the HCO3- basolateral increment showed that at resting levels slc4a4 was not a limiting step for secretion. The transcellular/intracellular dependence of apical HCO3- secretion differed between the proximal regions. In conclusion, intestinal HCO3- secretion has a functional region-dependent organization that was not reflected by the anterior-posterior regionalization on HCO3- secretion and expression profiles of chloride/water absorption related genes.
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Affiliation(s)
- Alexandra Alves
- Centre of Marine Sciences (CCMAR), University of Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
| | - Sílvia F Gregório
- Centre of Marine Sciences (CCMAR), University of Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
| | - Renata C Egger
- Centre of Marine Sciences (CCMAR), University of Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
| | - Juan Fuentes
- Centre of Marine Sciences (CCMAR), University of Algarve, Campus de Gambelas, 8005-139 Faro, Portugal.
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Gregório SF, Fuentes J. Regulation of Bicarbonate Secretion in Marine Fish Intestine by the Calcium-Sensing Receptor. Int J Mol Sci 2018; 19:E1072. [PMID: 29617283 PMCID: PMC5979614 DOI: 10.3390/ijms19041072] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Revised: 03/26/2018] [Accepted: 04/01/2018] [Indexed: 12/29/2022] Open
Abstract
In marine fish, high epithelial intestinal HCO₃− secretion generates luminal carbonate precipitates of divalent cations that play a key role in water and ion homeostasis. The present study was designed to expose the putative role for calcium and the calcium-sensing receptor (CaSR) in the regulation of HCO₃− secretion in the intestine of the sea bream (Sparus aurata L.). Effects on the expression of the CaSR in the intestine were evaluated by qPCR and an increase was observed in the anterior intestine in fed fish compared with unfed fish and with different regions of intestine. CaSR expression reflected intestinal fluid calcium concentration. In addition, anterior intestine tissue was mounted in Ussing chambers to test the putative regulation of HCO₃− secretion in vitro using the anterior intestine. HCO₃− secretion was sensitive to varying calcium levels in luminal saline and to calcimimetic compounds known to activate/block the CaSR i.e., R 568 and NPS-2143. Subsequent experiments were performed in intestinal sacs to measure water absorption and the sensitivity of water absorption to varying luminal levels of calcium and calcimimetics were exposed as well. It appears, that CaSR mediates HCO₃− secretion and water absorption in marine fish as shown by responsiveness to calcium levels and calcimimetic compounds.
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Affiliation(s)
- Sílvia F Gregório
- Centre of Marine Sciences (CCMar), Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal.
| | - Juan Fuentes
- Centre of Marine Sciences (CCMar), Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal.
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Lu W, Jin Y, Xu J, Greenwood MP, Balment RJ. Molecular characterisation and expression of parathyroid hormone-related protein in the caudal neurosecretory system of the euryhaline flounder, Platichthys flesus. Gen Comp Endocrinol 2017; 249:24-31. [PMID: 28242308 DOI: 10.1016/j.ygcen.2017.02.015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Revised: 02/21/2017] [Accepted: 02/23/2017] [Indexed: 02/05/2023]
Abstract
Parathyroid hormone-related protein (PTHrP) is a hypercalcemic factor in fish, but the source of circulating PTHrP remains unclear. In this study investigation of the caudal neurosecretory system (CNSS), considered one of major sources of PTHrP in fish, provided valuable insights into this regulatory system. We report pthrpa and pthrpb gene cloning, characterization, expression, and responses to low salinity and hypocalcemia challenge in flounder. The pthrpa and pthrpb precursors, isolated from a European flounder CNSS library, consist of 166 and 192 amino acid residues, respectively, with an overall homology of approximately 59.2%. Both precursors contain a signal peptide and a mature peptide with cleavage and amidation sites. The flounder PTHrPA and PTHrPB peptides share only 41% sequence identity with human PTHrPA. Quantitative PCR analysis demonstrated that the bone and bladder, are respectively major sites of pthrpa and pthrpb expression in flounder. Urophysectomy confirmed the CNSS as a likely contributor to circulating PTHrP peptides. There were no significant differences in CNSS pthrpa and pthrpb mRNA expression or plasma PTHrP levels between seawater (SW) and freshwater (FW)-adapted fish, though plasma total calcium concentrations were higher in FW animals. The intraperitonial administration of EGTA rapidly induced hypocalcemia and concomitant elevation in plasma PTHrP accompanied by increases in both pthrpa and pthrpb expression in the CNSS. Together, these findings support an evolutionary conserved role for PTHrP in the endocrine regulation of calcium.
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Affiliation(s)
- Weiqun Lu
- Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Ministry of Education, Shanghai 201306, China; College of Fisheries and Life Science, Shanghai Ocean University, Shanghai 201306, China.
| | - Yingying Jin
- College of Fisheries and Life Science, Shanghai Ocean University, Shanghai 201306, China
| | - Jinling Xu
- College of Fisheries and Life Science, Shanghai Ocean University, Shanghai 201306, China
| | - Michael P Greenwood
- Faculty of Life Sciences, University of Manchester, Oxford Road, M13 9PT, United Kingdom
| | - Richard J Balment
- Faculty of Life Sciences, University of Manchester, Oxford Road, M13 9PT, United Kingdom
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Acute salinity and temperature challenges during early development of zebrafish: Differential gene expression of PTHs, PTHrPs and their receptors. AQUACULTURE AND FISHERIES 2017. [DOI: 10.1016/j.aaf.2017.04.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Ruiz-Jarabo I, Gregório SF, Gaetano P, Trischitta F, Fuentes J. High rates of intestinal bicarbonate secretion in seawater tilapia (Oreochromis mossambicus). Comp Biochem Physiol A Mol Integr Physiol 2017; 207:57-64. [PMID: 28238831 DOI: 10.1016/j.cbpa.2017.02.022] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Revised: 02/13/2017] [Accepted: 02/20/2017] [Indexed: 01/07/2023]
Abstract
Osmoregulation in fish is a complex process that requires the orchestrated cooperation of many tissues. In fish facing hyperosmotic environments, the intestinal absorption of some monovalent ions and the secretion of bicarbonate are key processes to favor water absorption. In the present study, we showed that bicarbonate levels in the intestinal fluid are several fold higher in seawater than in freshwater acclimated tilapia (Oreochromis mossambicus). In addition, we analyzed gene expression of the main molecular mechanisms involved in HCO3- movements i.e. slc26a6, slc26a3, slc4a4 and v-type H-ATPase sub C in the intestine of tilapia acclimated to both seawater and freshwater. Our results show an anterior/posterior functional regionalization of the intestine in tilapia in terms of expression patterns, which is affected by environmental salinity mostly in the anterior and mid intestine. Analysis of bicarbonate secretion using pH-Stat in tissues mounted in Ussing chambers reveals high rates of bicarbonate secretion in tilapia acclimated to seawater from anterior intestine to rectum ranging between ~900 and ~1700nmolHCO3-cm-2h-1. However, a relationship between the expression of slc26a6, slc26a3, slc4a4 and the rate of bicarbonate secretion seems to be compromised in the rectum. In this region, the low expression of the bicarbonate transporters could not explain the high bicarbonate secretion rates here described. However, we postulate that the elevated v-type H-ATPase mRNA expression in the rectum could be involved in this process.
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Affiliation(s)
- I Ruiz-Jarabo
- Comparative Endocrinology and Integrative Biology, Centre of Marine Sciences (CCMar), Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
| | - S F Gregório
- Comparative Endocrinology and Integrative Biology, Centre of Marine Sciences (CCMar), Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
| | - P Gaetano
- Comparative Endocrinology and Integrative Biology, Centre of Marine Sciences (CCMar), Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal; Dipartimento di Scienze Chimiche, Biologiche, Farmaceutiche ed Ambientali, Università degli Studi di Messina, Messina, Italy
| | - F Trischitta
- Dipartimento di Scienze Chimiche, Biologiche, Farmaceutiche ed Ambientali, Università degli Studi di Messina, Messina, Italy
| | - J Fuentes
- Comparative Endocrinology and Integrative Biology, Centre of Marine Sciences (CCMar), Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal.
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Ruiz-Jarabo I, Barany A, Jerez-Cepa I, Mancera JM, Fuentes J. Intestinal response to salinity challenge in the Senegalese sole (Solea senegalensis). Comp Biochem Physiol A Mol Integr Physiol 2016; 204:57-64. [PMID: 27865855 DOI: 10.1016/j.cbpa.2016.11.009] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Revised: 09/08/2016] [Accepted: 11/14/2016] [Indexed: 12/27/2022]
Abstract
Fish are continuously forced to actively absorb or expel water and ions through epithelia. Most studies have focused on the gill due to its role in Na+ and Cl- trafficking. However, comparatively few studies have focused on the changing function of the intestine in response to external salinity. Therefore, the present study investigated the main intestinal changes of long-term acclimation of the Senegalese sole (Solea senegalensis) to 5, 15, 38 and 55ppt. Through the measurement of short-circuit current (Isc) in Ussing chambers and biochemical approaches, we described a clear anterior/posterior functional regionalization of the intestine in response to salinity. The use of specific inhibitors in Ussing chamber experiments, revealed that the bumetanide-sensitive Na+/K+/Cl- co-transporters are the main effectors of Cl- uptake in both anterior intestine and rectum. Additionally, the use of the anion exchanger specific inhibitor, DIDS, showed a salinity/region dependency of anion exchanger function. Moreover, we also described ouabain-sensitive Na+/K+-ATPase (NKA) and Bafilomycin A1-sensitive H+-ATPase activities (HA), which displayed changes related to salinity and intestinal region. However, the most striking result of the present study is the description of an omeprazole-sensitive H+/K+-ATPase (HKA) in the rectum of Senegalese sole. Its activity was consistently measurable and increased at lower salinities, reaching rates even higher than those of the NKA. Together our results provide new insights into the changing role of the intestine in response to external salinity in teleost fish. The rectal activity of HKA offers an alternative/cooperative mechanism with the HA in the final processing of intestinal water absorption by apical titration of secreted bicarbonate.
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Affiliation(s)
- I Ruiz-Jarabo
- Comparative Endocrinology and Integrative Biology, Centre of Marine Sciences (CCMar), Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal; Departamento de Biología, Facultad de Ciencias del Mar y Ambientales, Universidad de Cádiz, 11510, Puerto Real, Cádiz, Spain
| | - A Barany
- Comparative Endocrinology and Integrative Biology, Centre of Marine Sciences (CCMar), Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal; Departamento de Biología, Facultad de Ciencias del Mar y Ambientales, Universidad de Cádiz, 11510, Puerto Real, Cádiz, Spain
| | - I Jerez-Cepa
- Departamento de Biología, Facultad de Ciencias del Mar y Ambientales, Universidad de Cádiz, 11510, Puerto Real, Cádiz, Spain
| | - J M Mancera
- Departamento de Biología, Facultad de Ciencias del Mar y Ambientales, Universidad de Cádiz, 11510, Puerto Real, Cádiz, Spain
| | - J Fuentes
- Comparative Endocrinology and Integrative Biology, Centre of Marine Sciences (CCMar), Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal.
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