scholarly journals Interactions between cortisol and Rhesus glycoprotein expression in ureogenic toadfish, Opsanus beta

2011 ◽  
Vol 215 (2) ◽  
pp. 314-323 ◽  
Author(s):  
T. M. Rodela ◽  
M. D. McDonald ◽  
P. J. Walsh ◽  
K. M. Gilmour
Keyword(s):  
Opsanus Beta ◽  
Rhesus Glycoprotein

Concentration of MgSO4 in the intestinal lumen of Opsanus beta limits osmoregulation in response to acute hypersalinity stress

2011 ◽  
Vol 300 (4) ◽  
pp. R895-R909 ◽  
Author(s):  
Janet Genz ◽  
M. Danielle McDonald ◽  
Martin Grosell
Keyword(s):  
Ionic Composition ◽  
Urine Osmolality ◽  
Intestinal Lumen ◽  
Natural Environments ◽  
Ambient Seawater ◽  
Opsanus Beta ◽  
Monovalent Ions ◽  
Ureteral Catheters ◽  
Tidal Pools

Marine teleosts constantly lose water to their surrounding environment, a problem exacerbated in fish exposed to salinity higher than normal seawater. Some fish undergo hypersaline exposures in their natural environments, such as short- and long-term increases in salinity occurring in small tidal pools and other isolated basins, lakes, or entire estuaries. Regardless of the degree of hypersalinity in the ambient water, intestinal absorption of monovalent ions drives water uptake to compensate for water loss, concentrating impermeable MgSO4 in the lumen. This study considers the potential of luminal [MgSO4] to limit intestinal water absorption, and therefore osmoregulation, in hypersalinity. The overall tolerance and physiological response of toadfish ( Opsanus beta) to hypersalinity exposure were examined. In vivo, fish in hypersaline waters containing artificially low [MgSO4] displayed significantly lower osmolality in both plasma and intestinal fluids, and increased survival at 85 parts per thousand, indicating improved osmoregulatory ability than in fish exposed to hypersalinity with ionic ratios similar to naturally occurring ratios. Intestinal sac preparations revealed that in addition to the osmotic pressure difference across the epithelium, the luminal ionic composition influenced the absorption of Na+, Cl−, and water. Hypersalinity exposure increased urine flow rates in fish fitted with ureteral catheters regardless of ionic composition of the ambient seawater, but it had no effect on urine osmolality or pH. Overall, concentrated MgSO4 within the intestinal lumen, rather than renal or branchial factors, is the primary limitation for osmoregulation by toadfish in hypersaline environments.

Subcellular localization and biochemical properties of the enzymes of carbamoyl phosphate and urea synthesis in the batrachoidid fishes Opsanus beta, Opsanus tau and Porichthys notatus

1995 ◽  
Vol 198 (3) ◽  
pp. 755-766 ◽  
Author(s):  
P Walsh
Keyword(s):  
Glutamine Synthetase ◽  
Subcellular Localization ◽  
Biochemical Properties ◽  
Nitrogen Excretion ◽  
Urea Synthesis ◽  
Carbamoyl Phosphate ◽  
Opsanus Beta ◽  
Opsanus Tau ◽  
Porichthys Notatus ◽  
The Family

The subcellular localization and biochemical properties of the enzymes of carbamoyl phosphate and urea synthesis were examined in three representatives of fishes of the family Batrachoididae, the gulf toadfish (Opsanus beta), the oyster toadfish (Opsanus tau) and the plainfin midshipman (Porichthys notatus). The primary objective of the study was to compare the biochemical characteristics of these fishes, which represent a range between ammoniotelism and ureotelism (O. beta being facultatively ureotelic), with previous patterns observed for an ammoniotelic teleost (Micropterus salmoides, the largemouth bass) and an obligate ureogenic elasmobranch (Squalus acanthias, the dogfish shark). The present study documents the expression of mitochondrial carbamoyl phosphate synthetase (CPSase) III and cytosolic CPSase II (and its associated enzymes of pyrimidine synthesis, dihydro-orotase and aspartate carbamoyltransferase) in the livers of all three batrachoidid species. Both mitochondrial and cytosolic activities of arginase were present in the livers of all three species, as were cytosolic glutamine synthetase and argininosuccinate synthetase and lyase. However, O. beta also showed mitochondrial glutamine synthetase activity and higher total hepatic levels of glutamine synthetase than either O. tau or P. notatus. Taken together, these observations confirm that the arrangement of these enzymes in the batrachoidid fishes has greater similarity to that of M. salmoides than to that of S. acanthias. However, differences within the family appear to coincide with the different nitrogen excretion strategies. O. tau and P. notatus are primarily ammoniotelic and most closely resemble the ammoniotelic M. salmoides, whereas ureotelism in O. beta is correlated with the presence of a mitochondrial glutamine synthetase and the ability to induce higher total glutamine synthetase activities than O. tau or P. notatus. Additionally, isolated mitochondria from O. beta were able to generate citrulline from glutamine, whereas those from O. tau were not. Also in contrast to S. acanthias, glutamine synthetase activities in the mitochondria of O. beta are consistently lower than those of CPSase III. This and other kinetic observations lend support to the hypothesis that glutamine synthetase may be an important regulatory control point in determining rates of ureogenesis in O. beta.

scholarly journals Opsanus brasiliensis Rotundo, Spinelli & Zavalla-Camin, 2005 (Teleostei: Batrachoidiformes: Batrachoididae), sinônimo- júnior de Opsanus beta (Goode & Bean, 1880), com notas sobre a ocorrência da espécie na costa brasileira

2007 ◽  
Vol 7 (2) ◽  
pp. 135-139 ◽  
Author(s):  
Rodrigo Antunes Caires ◽  
Helen Audrey Pichler ◽  
Henry Louis Spach ◽  
Juliana Martinhão Ignácio
Keyword(s):  
Sao Paulo ◽  
São Paulo ◽  
Opsanus Beta

Neste trabalho, dois exemplares de Opsanus coletados na costa do Paraná, e que representam os primeiros registros do gênero no sul do Brasil, foram identifcados como Opsanus beta (Goode & Bean, 1880). Uma comparação mais detalhada entre estes exemplares e a série-tipo de Opsanus brasiliensis Rotundo, Spinelli & Zavalla-Camin, 2005 (descrita originalmente do litoral de Santos, São Paulo), além de informações da literatura, indicou que Opsanus brasiliensis é sinônimo-júnior de Opsanus beta e que os representantes de Opsanus aqui encontrados são exóticos. É aqui levantada a possibilidade de que O. beta invadiu a costa brasileira através de água de lastro de navios que teriam zarpado das áreas naturais de ocorrência desta espécie.

Intestinal base excretion in the seawater-adapted rainbow trout: a role in acid-base balance?

1996 ◽  
Vol 199 (10) ◽  
pp. 2331-2343 ◽  
Author(s):  
R Wilson ◽  
K Gilmour ◽  
R Henry ◽  
C Wood
Keyword(s):  
Rainbow Trout ◽  
Potential Role ◽  
Excretion Rate ◽  
Anterior Region ◽  
Acid Base Balance ◽  
Acid Base ◽  
Opsanus Beta ◽  
Base Balance ◽  
High Fluid

A potential role for the intestine of seawater-adapted teleosts in acid­base regulation was investigated following earlier reports of highly alkaline rectal fluids in the gulf toadfish Opsanus beta. Rectal samples taken from starved seawater-adapted rainbow trout had a high fluid pH (8.90±0.03; mean ± s.e.m., N=13) and base (HCO3-+2CO32-) content of 157±26 mequiv kg-1 (N=11). In trout fitted with rectal catheters, rectal fluid was voided at a rate of 0.47±0.11 ml kg-1 h-1 (N=8), giving a net base excretion rate of 114±15 µequiv kg-1 h-1 (N=7). Drinking rates averaged 3.12±0.48 ml kg-1 h-1 (N=8), and accounted for only 6 % of the base excreted via the intestine, indicating substantial net transport of endogenously derived base into the intestine. Rectally excreted base was approximately balanced by an equivalent efflux of net acid from non-rectal sources (possibly as NH4+ excretion via the gills). Samples taken from four sites along the intestine revealed that the most anterior region (the pyloric intestine) was responsible for the majority of HCO3-+2CO32- accumulation. The pyloric intestine was subsequently perfused in situ to investigate possible mechanisms of base secretion. Net base fluxes were found to be dependent on luminal Cl-, 76 % stimulated by amiloride, 20 % inhibited by 10(-4) mol l-1 acetazolamide, but unaffected by either 10(-4) mol l-1 SITS or 2x10(-5) mol l-1 DIDS. This suggests that the mechanism of base secretion within the pyloric intestine may involve a Cl-/HCO3--ATPase. It is speculated that intestinal base secretion may play a role in facilitating osmoregulation of seawater-adapted teleosts.

EFFECTS OF AMMONIA ON SURVIVAL, SWIMMING AND ACTIVITIES OF ENZYMES OF NITROGEN METABOLISM IN THE LAKE MAGADI TILAPIA OREOCHROMIS ALCALICUS GRAHAMI

1993 ◽  
Vol 180 (1) ◽  
pp. 323-327 ◽  
Author(s):  
P. J. Walsh ◽  
H. L. Bergman ◽  
A. Narahara ◽  
C. M. Wood ◽  
P. A. Wright ◽  
...  
Keyword(s):  
Nitrogen Metabolism ◽  
Swimming Performance ◽  
Ammonia Excretion ◽  
Ammonia Toxicity ◽  
Short Term ◽  
Opsanus Beta ◽  
Lake Magadi ◽  
High Ammonia ◽  
Unionized Ammonia ◽  
Ammonia Exposure

The Lake Magadi tilapia, Oreochromis alcalicus grahami, is remarkable among teleosts in that it flourishes under extremely well-buffered alkaline water conditions (pH 10, CCO2 180 mmol l-1) at temperatures of 30–40 °C (Wood et al. 1989). As expected from current models in teleosts, ammonia excretion into such water would be difficult at best (Wood, 1993). Part of the survival strategy of the Lake Magadi tilapia is that it has a complete ornithine-urea cycle (O-UC) in the liver and excretes virtually all of its waste nitrogen as urea (Randall et al. 1989). Ammonia toxicity in ammoniotelic teleosts has been studied extensively, and typical values for unionized ammonia (NH3) 96 h LC50 (the concentration at which half of test subjects die after 96 h) are well below 100 micromolar (Haywood, 1983; Thurston et al. 1983a,b; Campbell, 1991). Surprisingly, no ammonia LC50 values are available for ureogenic teleost fish, and one would predict that fish synthesizing and excreting urea for whatever purpose would have higher LC50 values than their ammoniotelic counterparts. Additionally, since ammonia exposure has been implicated in the functional response of urea excretion in the Lake Magadi tilapia (Wood et al. 1989) and another ureogenic teleost (the gulf toadfish Opsanus beta) (Walsh et al. 1990), we reasoned that ammonia exposure in the Lake Magadi tilapia might reveal insights into the biochemical regulation of the O-UC in this species; in particular that it might induce enzyme activity. We report here that the Lake Magadi tilapia has a rather high ammonia LC50 compared to values for other teleosts, but that short-term ammonia exposure has very limited effects on the activities of the enzymes of nitrogen metabolism and on swimming performance.

Localization and analysis of natriuretic peptide receptors in the gills of the toadfish, Opsanus beta (teleostei)

1994 ◽  
Vol 267 (6) ◽  
pp. R1437-R1444 ◽  
Author(s):  
J. A. Donald ◽  
T. Toop ◽  
D. H. Evans
Keyword(s):  
Natriuretic Peptide ◽  
Binding Sites ◽  
Peptide Receptors ◽  
Natriuretic Peptide Receptors ◽  
Major Band ◽  
Opsanus Beta ◽  
Secondary Lamellae ◽  
Membrane Bound ◽  
Type C ◽  
Specific Ligand

The distribution and nature of natriuretic peptide binding sites was determined in the gills of the toadfish, Opsanus beta. Specific 125I-labeled rat atrial natriuretic peptide (rANP) and 125I-labeled porcine C-type natriuretic peptide (pCNP) binding sites were observed on the afferent and efferent filamental arteries and lamellar arterioles, and on the marginal channels of the secondary lamellae. In both section autoradiography and competition assays, the binding of both ligands was completely displaced by 1 microM rANP and 1 microM pCNP, but residual binding was observed with 1 microM of the type C natriuretic peptide receptor (NPR-C)-specific ligand C-ANF. Electrophoresis of gill membranes cross-linked with 125I-rANP showed a major band at 75 kDa and a fainter band at 140 kDa. Both rANP and pCNP significantly stimulated the production of cGMP above basal levels; C-ANF had no stimulatory effect. These data show that the intrafilamental gill vasculature of toadfish contains a major population of natriuretic peptide receptors very similar to mammalian clearance receptors and a smaller population of receptors that are linked to a membrane-bound guanylate cyclase.

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