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Schoen AN, Weinrauch AM, Bouyoucos IA, Treberg JR, Gary Anderson W. Hormonal effects on glucose and ketone metabolism in a perfused liver of an elasmobranch, the North Pacific spiny dogfish, Squalus suckleyi. Gen Comp Endocrinol 2024; 352:114514. [PMID: 38582175 DOI: 10.1016/j.ygcen.2024.114514] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/25/2023] [Revised: 02/26/2024] [Accepted: 04/03/2024] [Indexed: 04/08/2024]
Abstract
Hormonal influence on hepatic function is a critical aspect of whole-body energy balance in vertebrates. Catecholamines and corticosteroids both influence hepatic energy balance via metabolite mobilization through glycogenolysis and gluconeogenesis. Elasmobranchs have a metabolic organization that appears to prioritize the mobilization of hepatic lipid as ketone bodies (e.g. 3-hydroxybutyrate [3-HB]), which adds complexity in determining the hormonal impact on hepatic energy balance in this taxon. Here, a liver perfusion was used to investigate catecholamine (epinephrine [E]) and corticosteroid (corticosterone [B] and 11-deoxycorticosterone [DOC]) effects on the regulation of hepatic glucose and 3-HB balance in the North Pacific Spiny dogfish, Squalus suckleyi. Further, hepatic enzyme activity involved in ketogenesis (3-hydroxybutyrate dehydrogenase), glycogenolysis (glycogen phosphorylase), and gluconeogenesis (phosphoenolpyruvate carboxykinase) were assessed in perfused liver tissue following hormonal application to discern effects on hepatic energy flux. mRNA transcript abundance key transporters of glucose (glut1 and glut4) and ketones (mct1 and mct2) and glucocorticoid function (gr, pepck, fkbp5, and 11βhsd2) were also measured to investigate putative cellular components involved in hepatic responses. There were no changes in the arterial-venous difference of either metabolite in all hormone perfusions. However, perfusion with DOC increased gr transcript abundance and decreased flow rate of perfusions, suggesting a regulatory role for this corticosteroid. Phosphoenolpyruvate carboxykinase activity increased following all hormone treatments, which may suggest gluconeogenic function; E also increased 3-hydroxybutyrate dehydrogenase activity, suggesting a function in ketogenesis, and decreased pepck and fkbp5 transcript abundance, potentially showing some metabolic regulation. Overall, we demonstrate hormonal control of hepatic energy balance using liver perfusions at various levels of biological organization in an elasmobranch.
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Affiliation(s)
- Alexandra N Schoen
- Department of Biological Sciences, University of Manitoba, Winnipeg, MB R3T 2N2, Canada; Bamfield Marine Sciences Centre, Bamfield, BC V0R 1B0, Canada.
| | - Alyssa M Weinrauch
- Department of Biological Sciences, University of Manitoba, Winnipeg, MB R3T 2N2, Canada; Bamfield Marine Sciences Centre, Bamfield, BC V0R 1B0, Canada
| | - Ian A Bouyoucos
- Department of Biological Sciences, University of Manitoba, Winnipeg, MB R3T 2N2, Canada; Bamfield Marine Sciences Centre, Bamfield, BC V0R 1B0, Canada
| | - Jason R Treberg
- Department of Biological Sciences, University of Manitoba, Winnipeg, MB R3T 2N2, Canada
| | - W Gary Anderson
- Department of Biological Sciences, University of Manitoba, Winnipeg, MB R3T 2N2, Canada; Bamfield Marine Sciences Centre, Bamfield, BC V0R 1B0, Canada
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Weinrauch AM, Bouyoucos IA, Conlon JM, Anderson WG. The chondrichthyan glucagon-like peptide 3 regulates hepatic ketone metabolism in the Pacific spiny dogfish Squalus suckleyi. Gen Comp Endocrinol 2024; 350:114470. [PMID: 38346454 DOI: 10.1016/j.ygcen.2024.114470] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Revised: 12/07/2023] [Accepted: 02/03/2024] [Indexed: 02/17/2024]
Abstract
Chondrichthyans have a novel proglucagon-derived peptide, glucagon-like peptide (GLP)-3, in addition to GLP-1 and GLP-2 that occur in other vertebrates. Given that the GLPs are important regulators of metabolic homeostasis across vertebrates, we sought to investigate whether GLP-3 displays functional actions on metabolism within a representative chondrichthyan, the Pacific spiny dogfish Squalus suckleyi. There were no observed effects of GLP-3 perfusion (10 nM for 15 min) on the rate of glucose or oleic acid acquisition at the level of the spiral valve nor were there any measured effects on intermediary metabolism within this tissue. Despite no effects on apparent glucose transport or glycolysis in the liver, a significant alteration to ketone metabolism occurred. Firstly, ketone flux through the perfused liver switched from a net endogenous production to consumption following hormone application. Accompanying this change, significant increases in mRNA transcript abundance of putative ketone transporters and in the activity of β-hydroxybutyrate dehydrogenase (a key enzyme regulating ketone flux in the liver) were observed. Overall, while these results show effects on hepatic metabolism, the physiological actions of GLP are distinct between this chondrichthyan and those of GLP-1 on teleost fishes. Whether this is the result of the particular metabolic dependency on ketone bodies in chondrichthyans or a differential function of a novel GLP remains to be fully elucidated.
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Affiliation(s)
- Alyssa M Weinrauch
- Department of Biological Sciences, University of Manitoba, Winnipeg, MB R3T 2N2, Canada; Bamfield Marine Sciences Centre, Bamfield, BC V0R 1B0, Canada.
| | - Ian A Bouyoucos
- Department of Biological Sciences, University of Manitoba, Winnipeg, MB R3T 2N2, Canada; Bamfield Marine Sciences Centre, Bamfield, BC V0R 1B0, Canada
| | - J Michael Conlon
- Diabetes Research Centre, School of Biomedical Sciences, Ulster University, Coleraine BT52 1SA, Northern Ireland, UK
| | - W Gary Anderson
- Department of Biological Sciences, University of Manitoba, Winnipeg, MB R3T 2N2, Canada; Bamfield Marine Sciences Centre, Bamfield, BC V0R 1B0, Canada
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Schoen AN, Treberg JR, Wheaton CJ, Mylniczenko N, Gary Anderson W. Energy and corticosteroid mobilization following an induced stress response in an elasmobranch fish, the North Pacific spiny dogfish (Squalus acanthias suckleyi). Gen Comp Endocrinol 2021; 310:113799. [PMID: 33961877 DOI: 10.1016/j.ygcen.2021.113799] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Revised: 04/23/2021] [Accepted: 04/30/2021] [Indexed: 12/22/2022]
Abstract
The dominant corticosteroid in elasmobranchs, 1α-hydroxycorticosterone (1α-OHB), has a described role in mineral regulation but a presumptive role in energy balance. Energy demand in vertebrates following exposure to a stressor typically involves an immediate but transient release of glucocorticoids as a means of mobilizing available energy stores, usually in the form of glucose. Although a glucocorticoid role for 1α-OHB would be expected, direct glucocorticoid function of this steroid has yet to be reported in any elasmobranch. In addition, elasmobranchs also utilize the metabolite β-hydroxybutyrate (β-HB), which is thought to replace the role fatty acids play in most vertebrates as a predominant fuel source in extrahepatic tissues. To determine the mobilization of metabolites and corticosteroids during a stress event, North Pacific spiny dogfish, Squalus acanthias suckleyi, were cannulated and held in a darkened isolation box to recover (24-48 h) before being subjected to an acute air exposure or corticosterone injection. Dogfish were then serially blood sampled at nine timepoints over 48 h. Glucose, β-HB, 1α-OHB, corticosterone, as well as lactate, pH, and osmolality were quantified in plasma samples. All measured variables increased in control and treatment groups within 48 h from the start of experimentation, and β-HB and 1α-OHB remained elevated for the duration of the experiment. There was no linear correlation between glucose and 1α-OHB, but there was a weak (R2 = 0.230) although significant (p = 0.001), positive correlation between β-HB and 1α-OHB. Interestingly, there were also significant correlations between increasing circulating glucose and corticosterone (R2 = 0.349; p < 0.001), and decreasing β-HB and corticosterone concentrations (R2 = 0.180; p = 0.008). Our data suggest that following successive stressors of capture, surgery, and confinement, 1α-OHB was not correlated with circulating glucose, only weakly correlated with circulating β-HB concentrations (R2 = 0.230; p = 0.001), and that corticosterone may also serve a role in energy mobilization in this species.
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Affiliation(s)
- Alexandra N Schoen
- Department of Biological Sciences, 50 Sifton Road, University of Manitoba, Winnipeg R3T 2N2, Manitoba, Canada; Bamfield Marine Sciences Centre, 100 Pachena Road, Bamfield R3T 0A8, British Columbia, Canada.
| | - Jason R Treberg
- Department of Biological Sciences, 50 Sifton Road, University of Manitoba, Winnipeg R3T 2N2, Manitoba, Canada
| | - Catharine J Wheaton
- Disney Animals, Science and Environment, Disney's Animal Kingdom® and the Seas with Nemo and Friends®, Lake Buena Vista 32830, FL, USA
| | - Natalie Mylniczenko
- Disney Animals, Science and Environment, Disney's Animal Kingdom® and the Seas with Nemo and Friends®, Lake Buena Vista 32830, FL, USA
| | - W Gary Anderson
- Department of Biological Sciences, 50 Sifton Road, University of Manitoba, Winnipeg R3T 2N2, Manitoba, Canada; Bamfield Marine Sciences Centre, 100 Pachena Road, Bamfield R3T 0A8, British Columbia, Canada
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Hauser-Davis RA, Pereira CF, Pinto F, Torres JPM, Malm O, Vianna M. Mercury contamination in the recently described Brazilian white-tail dogfish Squalus albicaudus (Squalidae, Chondrichthyes). Chemosphere 2020; 250:126228. [PMID: 32114339 DOI: 10.1016/j.chemosphere.2020.126228] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2019] [Revised: 02/11/2020] [Accepted: 02/13/2020] [Indexed: 06/10/2023]
Abstract
The recently described Squalus albicaudus is a mesopredator shark and, as such, exposed to mercury biomagnification processes. Therefore, this study aimed to assess total Hg (THg) concentrations in S. albicaudus, a deep-water species, sampled off Southeastern Brazil and discuss ecological, reproductive, human consumption and conservation implications. Thirty-two individuals were sampled off the coast of Rio de Janeiro, including 13 gravid females carrying 34 embryos. Muscle THg concentrations were higher in all sex classes compared to liver, gonads and brain. The last three, in turn, presented THg concentrations above toxic biota thresholds. Significant correlations were observed between muscle and brain and liver, indicating systemic Hg contamination and inter-organ transport and distribution. In addition, correlations observed between organs strongly support efficient Hg blood-brain barrier crossing and maternal transfer. Maternal THg transfer was observed, with embryo THg also above toxic thresholds for fish. THg levels in muscle and liver, as well as embryos, were higher compared to other Squalus species worldwide. Hg contamination off the coast of Rio de Janeiro is of significant concern and should be further assessed. Potential human consumption risks are noted, as muscle THg concentrations were above maximum permissible levels set by regulatory agencies.
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Affiliation(s)
- Rachel Ann Hauser-Davis
- Laboratório de Avaliação e Promoção da Saúde Ambiental, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Av. Brasil, 4.365, Manguinhos, Rio de Janeiro, 21040-360, Brazil.
| | - Camila Ferreira Pereira
- Laboratório de Biologia e Tecnologia Pesqueira, Departamento de Biologia Marinha, Instituto de Biologia, Centro de Ciências da Saúde, UFRJ, Av. Carlos Chagas Filho, 373, Cidade Universitária, 21941-902, Rio de Janeiro, Brazil
| | - Fernando Pinto
- Laboratório de Radioisótopos Eduardo Penna Franca, Instituto de Biofísica Carlos Chagas Filho, Centro de Ciências da Saúde, UFRJ, Av. Carlos Chagas Filho, 373, Cidade Universitária, 21941-902, Rio de Janeiro, RJ, Brazil
| | - João Paulo M Torres
- Laboratório de Radioisótopos Eduardo Penna Franca, Instituto de Biofísica Carlos Chagas Filho, Centro de Ciências da Saúde, UFRJ, Av. Carlos Chagas Filho, 373, Cidade Universitária, 21941-902, Rio de Janeiro, RJ, Brazil
| | - Olaf Malm
- Laboratório de Radioisótopos Eduardo Penna Franca, Instituto de Biofísica Carlos Chagas Filho, Centro de Ciências da Saúde, UFRJ, Av. Carlos Chagas Filho, 373, Cidade Universitária, 21941-902, Rio de Janeiro, RJ, Brazil
| | - Marcelo Vianna
- Laboratório de Biologia e Tecnologia Pesqueira, Departamento de Biologia Marinha, Instituto de Biologia, Centro de Ciências da Saúde, UFRJ, Av. Carlos Chagas Filho, 373, Cidade Universitária, 21941-902, Rio de Janeiro, Brazil; IMAM-AquaRio, Rio de Janeiro Aquarium Research Center, Rio de Janeiro, Brazil.
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McMillan OJL, Dichiera AM, Harter TS, Wilson JM, Esbaugh AJ, Brauner CJ. Blood and Gill Carbonic Anhydrase in the Context of a Chondrichthyan Model of CO 2 Excretion. Physiol Biochem Zool 2020; 92:554-566. [PMID: 31567050 DOI: 10.1086/705402] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Pacific spiny dogfish (Squalus suckleyi) have been widely used as a representative species for chondrichthyan CO2 excretion. Pacific spiny dogfish have a slower red blood cell (RBC) carbonic anhydrase (CA) isoform than teleost fishes, extracellular CA activity, no endogenous plasma CA inhibitor, and plasma-accessible CA IV at the gills. Thus, both the RBC and plasma compartments contribute to bicarbonate ion (HCO3-) dehydration at the gills for CO2 excretion in contrast to teleost fishes, in which HCO3- dehydration is restricted to RBCs. We compared CA activity levels, subcellular localization, and presence of plasma CA inhibitors in the blood and gills of 13 chondrichthyans to examine the hypothesis that the dogfish model of CO2 excretion applies broadly to chondrichthyans. In general, blood samples from the 12 other chondrichthyans examined had lower RBC CA activity than teleosts, some extracellular CA activity, and no endogenous plasma CA inhibitor. While type IV-like membrane-associated CA was found in the gills in all four of the chondrichthyans examined, S. suckleyi had three times more CA activity (183±13.2 μmol CO2 min-1 mg protein-1) in the microsomal (membrane) fraction of gills than the other three. In addition, unexpected variation in CA characteristics was observed between chondrichthyan species. Thus, in general, it appears that the pattern of CA distribution in fishes can be generally categorized as either chondrichthyan or teleost models. However, further studies should examine the functional significance of the within-chondrichthyan differences we observed and investigate whether CO2 excretion patterns exist along a continuum or in discrete groups.
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Deck CA, Gary Anderson W, Walsh PJ. Effects of glucose and insulin administration on glucose transporter expression in the North Pacific spiny dogfish (Squalus suckleyi). Gen Comp Endocrinol 2017; 247:46-52. [PMID: 28093310 DOI: 10.1016/j.ygcen.2017.01.016] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Revised: 01/05/2017] [Accepted: 01/12/2017] [Indexed: 10/20/2022]
Abstract
Elasmobranchs (sharks, skates, and rays) are a primarily carnivorous group of fish, consuming few carbohydrates. Further, they tend to exhibit delayed responses to glucose and insulin administration in vivo relative to mammals, leading to a presumption of glucose-intolerance. To investigate the glucoregulatory capabilities of the spiny dogfish (Squalus suckleyi), plasma glucose concentration, muscle and liver glycogen content, and glucose transporter (glut1 and 4) mRNA levels were measured following intra-arterial administration of bovine insulin (10ngkg-1) or an approximate doubling of fasting plasma glucose concentration. Within 6h, following glucose administration, approximately half of the introduced glucose load had been cleared, with control levels being restored by 24h post-injection. It was determined that plasma clearance was due in part to increased uptake by the tissues as muscle and liver glycogen content increased significantly, correlating with an upregulation of glut mRNA levels. Following administration of bovine insulin, plasma glucose steadily decreased through 18h before returning toward control levels. Observed decreases in plasma glucose following insulin injection were, however, relatively minor, and no increases in tissue glycogen content were observed. glut4 and glycogen synthase mRNA levels did significantly increase in the muscle in response to insulin, but no changes occurred in the liver. The responses observed mimic what occurs in mammals and teleosts, thus suggesting a conserved mechanism for glucose homeostasis in vertebrates and a high degree of glucose tolerance in these predominantly carnivorous fish.
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Affiliation(s)
- Courtney A Deck
- Department of Biology, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada; Bamfield Marine Sciences Centre, Bamfield, British Columbia V0R 1B0, Canada.
| | - W Gary Anderson
- Department of Biological Sciences, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada; Bamfield Marine Sciences Centre, Bamfield, British Columbia V0R 1B0, Canada
| | - Patrick J Walsh
- Department of Biology, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada; Bamfield Marine Sciences Centre, Bamfield, British Columbia V0R 1B0, Canada
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Deck CA, Bockus AB, Seibel BA, Walsh PJ. Effects of short-term hyper- and hypo-osmotic exposure on the osmoregulatory strategy of unfed North Pacific spiny dogfish (Squalus suckleyi). Comp Biochem Physiol A Mol Integr Physiol 2015; 193:29-35. [PMID: 26686463 DOI: 10.1016/j.cbpa.2015.12.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2015] [Revised: 12/08/2015] [Accepted: 12/09/2015] [Indexed: 11/19/2022]
Abstract
The North Pacific spiny dogfish (Squalus suckleyi) is a partially euryhaline species of elasmobranch that often enter estuaries where they experience relatively large fluctuations in environmental salinity that can affect plasma osmolality. Previous studies have investigated the effects of altered salinity on elasmobranchs over the long term, but fewer studies have conducted time courses to investigate how rapidly they can adapt to such changes. In this study, we exposed unfed (no exogenous source of nitrogen or TMAO) spiny dogfish to hyper- and hypo-osmotic conditions and measured plasma and tissue osmolytes, nitrogen excretion, and changes in enzyme activity and mRNA levels in the rectal gland over 24h. It was shown that plasma osmolality changes to approximately match the ambient seawater within 18-24h. In the hypersaline environment, significant increases in urea, sodium, and chloride were observed, whereas in the hyposaline environment, only significant decreases in TMAO and sodium were observed. Both urea and ammonia excretion increased at low salinities suggesting a reduction in urea retention and possibly urea production. qPCR and enzyme activity data for Na(+)/K(+)-ATPase did not support the idea of rectal gland activation following exposure to increased salinities. Therefore, we suggest that the rectal gland may not be a quantitatively important aspect of the dogfish osmoregulatory strategy during changes in environmental salinity, or it may be active only in the very early stages (i.e., less than 6h) of responses to altered salinity.
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Affiliation(s)
- Courtney A Deck
- Department of Biology, University of Ottawa, Ottawa, ON K1N 6N5, Canada; Bamfield Marine Sciences Centre, Bamfield, BC V0R 1B0, Canada.
| | - Abigail B Bockus
- Department of Biological Sciences, University of Rhode Island, Kingston, RI 02881, USA; Bamfield Marine Sciences Centre, Bamfield, BC V0R 1B0, Canada
| | - Brad A Seibel
- Department of Biological Sciences, University of Rhode Island, Kingston, RI 02881, USA
| | - Patrick J Walsh
- Department of Biology, University of Ottawa, Ottawa, ON K1N 6N5, Canada; Bamfield Marine Sciences Centre, Bamfield, BC V0R 1B0, Canada
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Gilmour KM, Bayaa M, Kenney L, McNeill B, Perry SF. Type IV carbonic anhydrase is present in the gills of spiny dogfish (Squalus acanthias). Am J Physiol Regul Integr Comp Physiol 2006; 292:R556-67. [PMID: 16973930 DOI: 10.1152/ajpregu.00477.2006] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Physiological and biochemical studies have provided indirect evidence for a membrane-associated carbonic anhydrase (CA) isoform, similar to mammalian type IV CA, in the gills of dogfish (Squalus acanthias). This CA isoform is linked to the plasma membrane of gill epithelial cells by a glycosylphosphatidylinositol anchor and oriented toward the plasma, such that it can catalyze the dehydration of plasma HCO(3)(-) ions. The present study directly tested the hypothesis that CA IV is present in dogfish gills in a location amenable to catalyzing plasma HCO(3)(-) dehydration. Homology cloning techniques were used to assemble a 1,127 base pair cDNA that coded for a deduced protein of 306 amino acids. Phylogenetic analysis suggested that this protein was a type IV CA. For purposes of comparison, a second cDNA (1,107 base pairs) was cloned from dogfish blood; it encoded a deduced protein of 260 amino acids that was identified as a cytosolic CA through phylogenetic analysis. Using real-time PCR and in situ hybridization, mRNA expression for the dogfish type IV CA was detected in gill tissue and specifically localized to pillar cells and branchial epithelial cells that flanked the pillar cells. Immunohistochemistry using a polyclonal antibody raised against rainbow trout type IV CA revealed a similar pattern of CA IV immunoreactivity and demonstrated a limited degree of colocalization with Na(+)-K(+)-ATPase immunoreactivity. The presence and localization of a type IV CA isoform in the gills of dogfish is consistent with the hypothesis that branchial membrane-bound CA with an extracellular orientation contributes to CO(2) excretion in dogfish by catalyzing the dehydration of plasma HCO(3)(-) ions.
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Affiliation(s)
- K M Gilmour
- Department of Biology, University of Ottawa, 30 Marie Curie, Ottawa, ON, Canada K1N 6N5.
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