Ion transport across posterior gills of hyperosmoregulating shore crabs (Carcinus maenas): amiloride blocks the cuticular Na+ conductance and induces current-noise

2002 ◽  
Vol 205 (4) ◽  
pp. 523-531 ◽  
Author(s):  
Horst Onken ◽  
Sven Riestenpatt
Keyword(s):  
Short Circuit ◽  
Noise Analysis ◽  
Carcinus Maenas ◽  
Low Frequency ◽  
Short Circuit Current ◽  
Current Noise ◽  
Corner Frequency ◽  
Shore Crab ◽  
Shore Crabs ◽  
Gill Lamellae

SUMMARYSplit gill lamellae and gill cuticles of shore crabs (Carcinus maenas) adapted to 10 ‰ salinity were mounted in a modified Ussing-type chamber. With NaCl saline on both sides, split gill lamellae generated a short-circuit current (Isc) of –301±16 μA cm–2 at a conductance (Gte) of 40±2 mS cm–2. The net influxes of Na+ and Cl– were 8.3±2.6 and 18.2±2.7 μmol cm–2 h–1, respectively. External amiloride (100 μmol l–1) reduced Gte to approximately 50 % of the original value at unchanged Isc; Cl– fluxes remained unaffected, whereas Na+ fluxes were markedly reduced by 70–80 %. The Isc in the presence of external amiloride was almost completely inhibited by internal ouabain. At a clamp voltage of 50 mV (outside-positive), a positive current was measured at unchanged Gte. Under these conditions, amiloride reduced the current and conductance at half-maximal concentrations of 3.6 and 2.0 μmol l–1, respectively. At outside-positive voltages, but not under short-circuit conditions, external amiloride induced Lorentzian components in the power density spectra. The amiloride-dependent changes in the corner frequency (linear) and of the low-frequency plateau (‘bell-shaped’) were as expected for channel blockade by amiloride with pseudo-first-order kinetics. With an outside-positive clamp voltage of 50 mV across isolated cuticles, a positive cuticular current (Icut) of 25 188±3791 μA cm–2 and a cuticular conductance (Gcut) of 547±76 mS cm–2 were measured. External amiloride reduced Icut and Gcut at half-maximal concentrations of 0.7 and 0.6 μmol l–1, respectively. Amiloride-induced current-noise analysis gave similar results to those observed with split gill lamellae. Ion-substitution experiments with isolated cuticles further support inhibition by external amiloride of the cuticular Na+ conductance of shore crab gills and not amiloride-sensitive transporters (Na+ channels or Na+/H+ antiports) in the apical membrane.

Active absorption of Na+ and Cl- across the gill epithelium of the shore crab Carcinus maenas: voltage-clamp and ion-flux studies

1996 ◽  
Vol 199 (7) ◽  
pp. 1545-1554 ◽  
Author(s):  
S Riestenpatt ◽  
H Onken ◽  
D Siebers
Keyword(s):  
Short Circuit ◽  
Ussing Chamber ◽  
Basolateral Membrane ◽  
Carcinus Maenas ◽  
Short Circuit Current ◽  
Shore Crab ◽  
Thick Ascending Limb ◽  
Gill Epithelium ◽  
Apical Side ◽  
Shore Crabs

Mechanisms of active NaCl uptake across the posterior gills of the shore crab Carcinus maenas were examined using radiochemical and electrophysiological techniques. In order to measure short-circuit current (Isc), transepithelial conductance (Gte) and area-related unidirectional fluxes of Na+ and Cl-, single split gill lamellae (epithelium plus cuticle) of hyperregulating shore crabs were mounted in a modified Ussing chamber. The negative short-circuit current measured with haemolymph-like NaCl saline on both sides of the epithelium could be inhibited by application of basolateral ouabain (ouabain inhibitor constant KOua=56±10 µmol l-1), 5-nitro-2-(3-phenylpropylamino)-benzoic acid (NPPB; KNPPB=7.5±2.5 mmol l-1) or Cs+ (10 mmol l-1). From the apical side, Isc was nearly completely blocked by Cs+ (10 mmol l-1) or Ba2+ (15 µmol l-1), whereas apical addition of furosemide (1 mmol l-1) resulted in only a small current decrease. Cl- influxes were linearly related to negative Isc. The ratio between net influxes of Cl- and Na+ was found to be approximately 2:1. With a single membrane preparation, achieved by permeabilizing the basolateral membrane with amphotericin B, Cl- influxes which were driven by a concentration gradient were shown to depend on the presence of apical Na+ and K+. On the basis of these observations, we propose that active and electrogenic absorption of NaCl across the gill epithelium of hyperregulating shore crabs proceeds as in the thick ascending limb of Henle's loop in the mammalian nephron. Accordingly, branchial NaCl transport is mediated by apical K+ channels in cooperation with apical Na+/K+/2Cl- cotransporters and by the basolateral Na+/K+-ATPase and basolateral Cl- channels.

Active ammonia excretion across the gills of the green shore crabCarcinus maenas: participation of Na+/K+-ATPase, V-type H+-ATPase and functional microtubules

2002 ◽  
Vol 205 (18) ◽  
pp. 2765-2775 ◽  
Author(s):  
Dirk Weihrauch ◽  
Andreas Ziegler ◽  
Dietrich Siebers ◽  
David W. Towle
Keyword(s):  
Short Circuit ◽  
Basolateral Membrane ◽  
Carcinus Maenas ◽  
Specific Inhibitor ◽  
Ammonia Excretion ◽  
Short Circuit Current ◽  
Shore Crab ◽  
Dependent Manner ◽  
Microtubule Network ◽  
Experimental Conditions

SUMMARYAlthough aquatic animals are generally believed to export nitrogenous waste by diffusion of NH3 or NH4+ across external epithelia, evidence for active ammonia excretion has been found in a number of species. In the euryhaline green shore crab Carcinus maenas, active excretion of ammonia across isolated gills is reduced by inhibitors of the Na+/K+-ATPase and vacuolar-type H+-ATPase. In addition, a functional dynamic microtubule network is necessary, since application of colchicine, taxol or thiabendazole leads to almost complete blockage of active and gradient-driven ammonia excretion. Actin filaments seem not to play a role in the excretory process. The NH4+-dependent short-circuit current and the conductance of the isolated cuticle were reduced in a dose-dependent manner by amiloride,a non-specific inhibitor of the Na+/H+ exchanger and Na+ channels. Combined with an analysis of gill morphology, the strong intracellular but weak apical abundance of V-type H+-ATPase and the fact that ammonia flux rates are equal under buffered and unbuffered experimental conditions, our observations suggest a hypothetical model of transepithelial ammonia movement that features active uptake across the basolateral membrane, sequestration in acidified vesicles, vesicle transport via microtubules and exocytosis at the apical membrane.

scholarly journals Isolation of a neuropeptide from locust corpus cardiacum which influences ileal transport.

1992 ◽  
Vol 173 (1) ◽  
pp. 261-274 ◽  
Author(s):  
N Audsley ◽  
C McIntosh ◽  
J E Phillips
Keyword(s):  
High Performance ◽  
Schistocerca Gregaria ◽  
Short Circuit ◽  
Carcinus Maenas ◽  
Short Circuit Current ◽  
Homarus Americanus ◽  
Shore Crab ◽  
Relative Molecular Mass ◽  
Corpus Cardiacum ◽  
Orconectes Limosus

1. Schistocerca gregaria ion-transport peptide (Scg-ITP) was isolated from aqueous extracts of the corpus cardiacum by a four-step procedure, utilizing reverse-phase high-performance liquid chromatography for separation and stimulation of a Cl(-)-dependent short-circuit current (Isc) across locust ilea as the bioassay. 2. Scg-ITP has an unblocked N terminus and an apparent relative molecular mass of 7700. Thirty-one residues (of an estimated 65) were identified by sequence analysis. 3. Scg-ITP is structurally related to a crustacean family of neuropeptides which includes the crustacean hyperglycaemic hormones from the shore crab Carcinus maenas and the crayfish Orconectes limosus and moult-inhibiting hormone and vitellogenesis-inhibiting hormone from the lobster Homarus americanus. 4. Scg-ITP has no sequence homology with neuroparsins (Nps). Nps are the only other neuropeptides isolated to date that might regulate reabsorption in an insect hindgut (rectum).

scholarly journals Basolateral K channels in an insect epithelium. Channel density, conductance, and block by barium.

1986 ◽  
Vol 87 (3) ◽  
pp. 443-466 ◽  
Author(s):  
J W Hanrahan ◽  
N K Wills ◽  
J E Phillips ◽  
S A Lewis
Keyword(s):  
Single Channel ◽  
Short Circuit ◽  
Noise Analysis ◽  
Basolateral Membrane ◽  
Membrane Conductance ◽  
Short Circuit Current ◽  
Corner Frequency ◽  
Fluctuation Analysis ◽  
K Channels ◽  
K Current

K channels in the basolateral membrane of insect hindgut were studied using current fluctuation analysis and microelectrodes. Locust recta were mounted in Ussing-type chambers containing Cl-free saline and cyclic AMP (cAMP). A transepithelial K current was induced by raising serosal [K] under short-circuit conditions. Adding Ba to the mucosal (luminal) side under these conditions had no effect; however, serosal Ba reversibly inhibited the short-circuit current (Isc), increased transepithelial resistance (Rt), and added a Lorentzian component to power density spectra of the Isc. A nonlinear relationship between corner frequency and serosal [Ba] was observed, which suggests that the rate constant for Ba association with basolateral channels increased as [Ba] was elevated. Microelectrode experiments revealed that the basolateral membrane hyperpolarized when Ba was added: this change in membrane potential could explain the nonlinearity of the 2 pi fc vs. [Ba] relationship if external Ba sensed about three-quarters of the basolateral membrane field. Conventional microelectrodes were used to determine the correspondence between transepithelially measured current noise and basolateral membrane conductance fluctuations, and ion-sensitive microelectrodes were used to measure intracellular K activity (acK). From the relationship between the net electrochemical potential for K across the basolateral membrane and the single channel current calculated from noise analysis, we estimate that the conductance of basolateral K channels is approximately 60 pS, and that there are approximately 180 million channels per square centimeter of tissue area.

Waterborne copper causes gill damage and hemolymph hypoxia in the shore crab Carcinus maenas

1993 ◽  
Vol 71 (8) ◽  
pp. 1569-1576 ◽  
Author(s):  
L. Nonnotte ◽  
F. Boitel ◽  
J. P. Truchot
Keyword(s):  
Carcinus Maenas ◽  
Lactate Concentration ◽  
Gill Tissue ◽  
Major Effect ◽  
Blood Oxygenation ◽  
Shore Crab ◽  
Structural Alterations ◽  
Arterial Blood ◽  
Shore Crabs ◽  
Gill Lamellae

The ultrastructure of gill lamellae was studied in shore crabs, Carcinus maenas, exposed to sublethal (0.5 mg∙L−1) and lethal (2 mg∙L−1) concentrations of waterborne copper for various durations. Oxygen tension, pH, and lactate concentration in arterial blood were determined in parallel studies. Extensive structural alterations involving cellular hyperplasia, vacuolization, and necrosis were found after 5–6 days of exposure to both sublethal and lethal copper levels. This led to considerable thickening of the gill epithelium and reduction of haemolymph spaces, resulting in restriction of respiratory gas exchange as shown by a marked hypoxemia. Ensuing lactacidemia suggests that tissue hypoxia was probably the major effect of the toxicant at lethal levels. In sublethal conditions, partial repair of gill tissue and recovery of normal blood oxygenation and pH were observed after 18 days of exposure.

scholarly journals Influence of temperature on intraspecific, unbalanced dyadic contests between crabs

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e7845
Author(s):  
Allan T. Souza ◽  
Felipe O. Ribas ◽  
João F. Moura ◽  
Claudia Moreira ◽  
Joana Campos ◽  
...  
Keyword(s):  
Carapace Width ◽  
Carcinus Maenas ◽  
Individual Characteristics ◽  
The Body ◽  
Shore Crab ◽  
Temperature Conditions ◽  
Red Color ◽  
Shore Crabs ◽  
Influence Of Temperature On ◽  
Globally Distributed

Intraspecific agonistic interactions are widespread across the animal kingdom, with many individual morphological and physiological characteristics playing important roles in the fate of disputes. Additionally, changes to environmental conditions can influence the outcomes of animal contests. The shore crab (Carcinus maenas) is a globally distributed species, present in numerous coastal and estuarine temperate systems around the world. Although shore crabs are highly tolerant to changes in temperature, this parameter has important physiological effects on the species’ ecology, while its effects on behavior are not fully understood. Our study aims to investigate how different individual characteristics (such as sex, color morphotype, carapace and chela morphology) and temperature conditions affect the dyadic interactions between shore crabs when disputing food resources. In general, the differences in carapace width between opponents, their sexes, color morphotypes and the temperature conditions interacted and were important predictors of the contest fate. We found that the body size and color morphotype of C. maenas determined the fate of dyadic disputes. However, the higher temperatures disrupted the well-established dominance of the larger red color morphotype individuals. Overall, the agonistic contest results suggest higher plasticity than previously acknowledged.

The Distribution of P O2 and Hydrostatic Pressure Changes Within the Branchial Chambers in Relation to GILL VENTILATION OF THE SHORE CRAB CARCINUS MAENAS L

1969 ◽  
Vol 51 (1) ◽  
pp. 203-220
Author(s):  
G. M. HUGHES ◽  
B. KNIGHTS ◽  
C. A. SCAMMELL
Keyword(s):  
Hydrostatic Pressure ◽  
Ventilation System ◽  
Carcinus Maenas ◽  
Pressure Change ◽  
Shore Crab ◽  
Positive Pressure ◽  
Transparent Plastic ◽  
Gill Lamellae ◽  
Minimum Disturbance ◽  
Pressure Changes

1. A technique is described for replacing part of the branchiostegite of Carcinus maenas by a transparent plastic ‘window’ for direct observation of the gills in situ with minimum disturbance. 2. Observation of dye streams shows that most water enters the hypobranchial space through the Milne-Edwards openings above the chelae, flowing anteriorly and/or posteriorly to ventilate most of gills 3-8. Water also enters above the pereiopods to ventilate the rest of the gills. Water passes from the hypobranchial to the epibranchial space, confirming that there is a counterflow with respect to the circulation of blood through the gill lamellae. 3. By sampling water at different points in the branchial system, patterns of oxygen removal were studied. The gradients confirmed the direction of water flow observed by the use of dyes. 4. Rhythmic changes in hydrostatic pressure in normal forward-pumping of 3-12 mm. H2O were recorded from the branchial cavities, superimposed on a maintained negative pressure relative to that outside the crab of 0-10 mm. H2O. Reversals produced a brief positive pressure change of 0-22 mm. H2O. 5. The possible relationships of the rhythmic pressure changes to scaphognathite movements are discussed. 6. The role of reversals is discussed and it is concluded that their primary function during ventilation is in helping to clean the ventrally facing gill surfaces. But they are also important in respiration under certain special conditions which arise during the normal life of the animal. 7. The utilization of O2 during its passage over the gills is low (7-23%) in spite of the counterflow. Possible explanations of this are discussed in relation to a model of the whole ventilation system.

Effect of amiloride on the poorly selective cation channel of larval bullfrog skin

1989 ◽  
Vol 256 (1) ◽  
pp. C168-C174 ◽  
Author(s):  
S. D. Hillyard ◽  
W. Van Driessche
Keyword(s):  
Single Channel ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Inhibitory Effect ◽  
Ringer Solution ◽  
Cation Channel ◽  
Power Density Spectrum ◽  
Corner Frequency ◽  
Open Probability ◽  
Density Spectrum

A small, inward-directed, short-circuit current (SCC) was measured across the isolated skin of larval bullfrogs (Rana catesbeiana) when either NaCl or KCl Ringer solution bathed the mucosal surface. The addition of amiloride, in concentrations of 1-100 microM, produced a stepwise increase in SCC. As SCC values became maximally elevated by amiloride, the plateau value (So) of the Lorentzian component in the power-density spectrum increased, whereas the corner frequency (fc) decreased. This agonist effect of amiloride can be explained by an increase in the open probability and possibly the single-channel current of the larval channel. When the amiloride concentration was increased above 100 microM, the SCC values declined progressively but usually remained above pretreatment values. This suggests an antagonist effect of amiloride that is concurrent with the agonist effect. The removal of Ca2+ from the mucosal Ringers increased SCC in conjunction with an increase in So and a decrease in fc. Under these conditions, the maximal agonist effect of amiloride was observed at concentrations of 10-20 microM. Ca2+ thus exerts an inhibitory effect on the larval cation channel that interferes with the agonist effect of amiloride. The addition of Ba2+ to Ca2+-free preparations lowered SCC and reduced the agonist effect of amiloride.

scholarly journals Mycosis Is a Disease State Encountered Rarely in Shore Crabs, Carcinus maenas

Pathogens ◽  
2020 ◽  
Vol 9 (6) ◽  
pp. 462
Author(s):  
Charlotte E. Davies ◽  
Sophie H. Malkin ◽  
Jessica E. Thomas ◽  
Frederico M. Batista ◽  
Andrew F. Rowley ◽  
...  
Keyword(s):  
Immune Cell ◽  
Fungal Infections ◽  
Novel Species ◽  
Carcinus Maenas ◽  
Shore Crab ◽  
Marine Animals ◽  
Cell Reactivity ◽  
Shore Crabs ◽  
Swansea Bay ◽  
Disease Signatures

There is a paucity of knowledge regarding the diversity and impact(s) of disease-causing fungi in marine animals, especially shellfish. In efforts to address this knowledge gap for the shore crab Carcinus maenas, a year-long disease screen was carried out across two sites in Swansea Bay (Wales, UK) with a view to characterising putative fungal infections. Crabs were sampled between November 2017 and October 2018, and screened systematically for disease signatures using haemolymph (blood) preparations, targeted PCR and tissue histopathology. Strikingly, mycosis was confirmed in ~0.4% of total crabs tested (n = 1191) and restricted to one location only (Mumbles Pier). Clinical infections were observed in four out of four infected crabs. In these animals, the gills and hepatopancreas were congested with fungal morphotypes. In addition, some evidence indicates haemocyte (immune cell) reactivity toward the fungi. Phylogenetic placement of the partial internal transcribed spacer (ITS1) gene regions amplified from three mycotic crabs revealed the causative agent to be related to hypocrealean fungi, thereby representing a novel species.

Na+-K+-ATPase and Na+/Ca2+exchange activities in gills of hyperregulatingCarcinus maenas

1999 ◽  
Vol 276 (2) ◽  
pp. R490-R499 ◽  
Author(s):  
Čedomil Lucu ◽  
Gert Flik
Keyword(s):  
Atpase Activity ◽  
Specific Activity ◽  
Short Circuit ◽  
Carcinus Maenas ◽  
High Capacity ◽  
Short Circuit Current ◽  
Total Activity ◽  
Camp Content ◽  
Dependent Protein ◽  
Leaky Epithelium

Na+-K+-ATPase and Na+/Ca2+exchange activities were studied in gills of Carcinus maenas in seawater (SW) and after transfer to dilute seawater (DSW). Carcinushyperregulates its hemolymph osmolarity through active uptake of Na+, Cl−, and Ca2+. In DSW total Na+-K+-ATPase activity in posterior gills quadrupled; Na+/Ca2+exchange specific activity was unaffected, and total activity increased 1.67-fold. Short-circuit current ( Isc) in voltage-clamped posterior gill hemilamellae was −181 μA/cm2in SW and −290 μA/cm2in DSW and up to 90% ouabain sensitive; conductivity was similar in SW or DSW (42 and 46 mS/cm2, respectively) and representative of a leaky epithelium. The new steady state of hemolymph osmolarity 24 h after DSW transfer was preceded, already 3 h after transfer, by increased Na+-K+-ATPase but not Na+/Ca2+exchange activity. Western blot analysis indicated that the amount of Na+-K+-ATPase protein had increased 2.1-fold in crabs acclimated 3 wk to DSW; however, 4 h after DSW transfer no difference in the amount of Na+-K+-ATPase protein was observed. After DSW transfer branchial cAMP content decreased. A negative correlation between branchial Na+-K+-ATPase activity and cAMP content points to rapid regulation of Na+-K+-ATPase through cAMP-dependent protein kinase A activity. Ca2+transport may depend on the high-capacity Na+/Ca2+exchanger coupled to the versatile sodium pump.

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