Why do hagfish have gill "chloride cells" when they need not regulate plasma NaCl concentration?

1987 ◽  
Vol 65 (8) ◽  
pp. 1956-1965 ◽  
Author(s):  
Jon Mallatt ◽  
David M. Conley ◽  
Richard L. Ridgway
Keyword(s):  
Carbonic Anhydrase ◽  
Ion Transport ◽  
Specific Activity ◽  
Carbonic Anhydrase Activity ◽  
Chloride Cells ◽  
Gillichthys Mirabilis ◽  
The Pacific ◽  
Nacl Concentration ◽  
Tubular System ◽  
Freshwater Teleosts

Two enzymes implicated in branchial ion transport, Na+-K+-ATPase and carbonic anhydrase, were localized in gill ionocytes ("chloride cells") of the Pacific hagfish, Eptatretus stouti, by light microscopic histochemical techniques. In hagfish, ouabain-sensitive Na+-K+-ATPase activity was confined to apical halves of ionocytes, where most of the cytoplasmic tubular system is located. In marine teleosts, Na+-K+-ATPase was noted in chloride cells and erythrocytes. Acetazolamide and potassium cyanate sensitive carbonic anhydrase activity occurred throughout the cytoplasm and nucleus of hagfish ionocytes. Biochemical assay of hagfish gill homogenates for Na+-K+-ATPase yielded a specific activity of 3.1 μmol Pi∙mg protein−1∙h−1 at 37 °C. This resembles values we obtained for freshwater fish (Carassius auratus: 3.3 μmol Pi∙mg protein−1∙h−1; Tilapia shirana: 3.7 μmol Pi∙mg protein−1∙h−1), and is less than values we obtained for marine teleosts (Pomacentrus spp.: 13 μmol Pi∙mg protein−1∙h−1; Gillichthys mirabilis: 6.7 μmol Pi∙mg protein−1∙h−1). Hagfish resemble freshwater teleosts in many other gill features related to ion transport. The presence of carbonic anhydrase in gill ionocytes of hagfish supports the proposal that these cells function in acid–base regulation, i.e., that they exchange H+ for Na+ and [Formula: see text] for Cl−.

Localization of carbonic anhydrase in the cytoplasmic membrane of Neisseria sicca (strain 19)

1981 ◽  
Vol 27 (1) ◽  
pp. 87-92 ◽  
Author(s):  
M. N. MacLeod ◽  
I. W. DeVoe
Keyword(s):  
Carbonic Anhydrase ◽  
Density Gradient ◽  
Specific Activity ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sucrose Density Gradient ◽  
Carbonic Anhydrase Activity ◽  
Protein Patterns ◽  
Inner Membrane ◽  
Outer Membranes ◽  
Neisseria Sicca

The carbonic anhydrase activity and the growth of Neisseria sicca 19 were inhibited by the sulfonamide acetazolamide (10−5 M). Such inhibition was completely overcome by the addition of exogenous bicarbonate. Some carbonic anhydrase activity associated with the membranous envelope fraction of the cell was released when cells were broken by sonic treatment but not during cell breakage by high-pressure extrusion. After the selective solubilization (4 °C) of the inner membrane of envelopes by treatment with 1% sodium lauroyl sarcosinate, all detectable carbonic anhydrase activity was found in the soluble (inner membrane) fraction. After fractionation of the cell envelope into inner and outer membranes by treatment with ethylenediaminetetraacetate (EDTA) followed by sucrose density gradient centrifugation, the total and specific activity of carbonic anhydrase paralleled that of succinate dehydrogenase, an inner membrane enzyme marker. The Coomassie blue stained protein patterns after polyacrylamide gel electrophoresis of the bands from the sucrose density gradient provided confirmation that the inner and outer membranes had indeed been separated.

Histochemical localization of Na+–K+ ATPase and carbonic anhydrase activity in gills of 17 fish species

1988 ◽  
Vol 66 (11) ◽  
pp. 2398-2405 ◽  
Author(s):  
David M. Conley ◽  
Jon Mallatt
Keyword(s):  
Carbonic Anhydrase ◽  
Atpase Activity ◽  
Carbonic Anhydrase Activity ◽  
Chloride Cells ◽  
Shark Species ◽  
Acid Base ◽  
Pavement Cells ◽  
Leopard Shark ◽  
Biochemical Assays ◽  
Definite Correlation

Activities of two enzymes considered to be involved in NaCl regulation, Na+–K+ ATPase and carbonic anhydrase, were localized in gill epithelia of 14 teleost, 2 agnathan, and 1 shark species through light microscopic histochemistry. Findings were confirmed by use of appropriate inhibitors (ouabain, acetazolamide). Na+–K+ ATPase activity was detected in chloride cells of most marine teleost species (six of eight) and of marine leopard shark and hagfish, but never in freshwater fish gills. In general, this finding agrees with past biochemical assays showing gill Na+–K+ ATPase activity to be highest in marine teleosts. Staining for carbonic anhydrase took one of three patterns among species: gill pavement cells or chloride cells, or both, were stained. Interspecific distribution of these patterns bore little relation to taxonomy or to habitat salinity, although chloride cells of euryhaline teleosts seemed more likely to stain than chloride cells of stenohaline teleosts, freshwater or marine. Given the lack of a definite correlation with salinity, it is concluded that fish gill carbonic anhydrase may not function in NaCl regulation as much as in acid–base regulation; the enzyme's role in preventing systemic pH imbalance is discussed.

Temperature-Related Changes in the Erythrocytic Carbonic Anhydrase (Acetazolamide-Sensitive Esterase) Activity of Goldfish, Carassius Auratus

1979 ◽  
Vol 78 (1) ◽  
pp. 255-264
Author(s):  
ARTHUR H. HOUSTON ◽  
KAREN M. MEAROW
Keyword(s):  
Carbonic Anhydrase ◽  
Carassius Auratus ◽  
Specific Activity ◽  
Thermal Sensitivity ◽  
Carbonic Anhydrase Activity ◽  
Red Cell ◽  
Goldfish Carassius Auratus ◽  
Species Activity ◽  
Plasma Chloride ◽  
Stable Plasma

1. Carbonic anhydrase activity in ‘membrane’ and ‘cytosol’ fractions of goldfish erythrocytes was assayed by the p-nitrophenyl acetate procedure following thermal acclimation. 2. The thermal sensitivity of ‘membrane’-associated activity was apparently unaltered by acclimation. ‘Cytosol’ activity in warm-acclimated specimens was somewhat more thermosensitive than that of animals maintained at low temperature. 3. Significant increases in specific activity, and activity per unit volume of packed cells and blood were observed at higher temperatures when assays were conducted at the temperatures at which the system actually functions in the fish. By contrast, when determinations were carried out at a standard temperature (41 °C) corresponding to the upper incipient lethal for this species, activity was either unaffected, or declined as acclimation temperatures increased. 4. Changes in carbonic anhydrase activity following acclimation are consistent with the hypothesis that this system is implicated in the maintenance of stable plasma chloride levels, and the suggestion that alterations in red cell chloride levels with temperature are, in part at least, attributable to concomitant variations in enzyme activity.

Salinity tolerance and osmoregulation in the silver perch, Bidyanus bidyanus Mitchell (Teraponidae), an endemic Australian freshwater teleost

1995 ◽  
Vol 46 (6) ◽  
pp. 947 ◽  
Author(s):  
R Guo ◽  
PB Mather ◽  
MF Capra
Keyword(s):  
Fresh Water ◽  
Salt Water ◽  
Ultrastructural Feature ◽  
Chloride Cells ◽  
Freshwater Teleost ◽  
Accessory Cells ◽  
Tubular System ◽  
Branchial Epithelium ◽  
Australian Freshwater ◽  
Freshwater Teleosts

Juvenile silver perch, Bidyanus bidyanus, were subjected to direct transfer from fresh water to various test salinities. No mortality was observed when the fish were transferred from fresh water to a salinity of 12, but 40% mortality was observed at a salinity of 15 after seven days. Pre-acclimation of silver perch to a salinity of 12 for seven days resulted in only marginally better survival at higher salinities. Plasma osmotic concentrations of silver perch rose slightly in salinities below 9 but rapidly at higher salinities, following the same track as the iso-osmotic line. Minimum body water content was observed in individuals subjected to a salinity of 15 for 24 h. As found in other freshwater teleosts, chloride cells were found in the branchial epithelium of silver perch. Accessory cells were observed beside the chloride cells in both freshwater and salt-water conditions. Fish subjected to a salinity of 12 for seven days showed chloride cells with a more developed tubular system than controls. The length of the junctions between chloride cells and accessory cells was significantly shorter in fish adapted to a salinity of 12 than in controls. The ultrastructural feature of 'interdigitations' of accessory cells was not observed during salt-water adaptation. These data indicate that silver perch is the least tolerant of high salinities and the most truly freshwater Australian teleost species examined to date.

Immunolocalization of ion-transport proteins to branchial epithelium mitochondria-rich cells in the mudskipper (Periophthalmodon schlosseri)

2000 ◽  
Vol 203 (15) ◽  
pp. 2297-2310 ◽  
Author(s):  
J.M. Wilson ◽  
D.J. Randall ◽  
M. Donowitz ◽  
A.W. Vogl ◽  
A.K. Ip
Keyword(s):  
Boundary Layer ◽  
Carbonic Anhydrase ◽  
Ion Transport ◽  
Basolateral Membrane ◽  
Anion Channel ◽  
Carbonic Anhydrase Activity ◽  
Transport Proteins ◽  
Ph Effects ◽  
Periophthalmodon Schlosseri ◽  
Branchial Epithelium

The branchial epithelium of the mudskipper Periophthalmodon schlosseri is densely packed with mitochondria-rich (MR) cells. This species of mudskipper is also able to eliminate ammonia against large inward gradients and to tolerate extremely high environmental ammonia concentrations. To test whether these branchial MR cells are the sites of active ammonia elimination, we used an immunological approach to localize ion-transport proteins that have been shown pharmacologically to be involved in the elimination of NH(4)(+) (Na(+)/NH(4)(+) exchanger and Na(+)/NH(4)(+)-ATPase). We also investigated the role of carbonic anhydrase and boundary-layer pH effects in ammonia elimination by using the carbonic anhydrase inhibitor acetazolamide and by buffering the bath water with Hepes, respectively. In the branchial epithelium, Na(+)/H(+) exchangers (both NHE2- and NHE3-like isoforms), a cystic fibrosis transmembrane regulator (CFTR)-like anion channel, a vacuolar-type H(+)-ATPase (V-ATPase) and carbonic anhydrase immunoreactivity are associated with the apical crypt region of MR cells. Associated with the MR cell basolateral membrane and tubular system are the Na(+)/K(+)-ATPase and a Na(+)/K(+)/2Cl(−) cotransporter. A proportion of the ammonia eliminated by P. schlosseri involves carbonic anhydrase activity and is not dependent on boundary-layer pH effects. The apical CFTR-like anion channel may be serving as a HCO(3)(−) channel accounting for the acid-base neutral effects observed with net ammonia efflux inhibition.

Carbonic anhydrase in mouse skeletal muscle and its influence on contractility

1994 ◽  
Vol 72 (5-6) ◽  
pp. 244-249 ◽  
Author(s):  
Claude H. Côté ◽  
Nicolas Jomphe ◽  
Abdul Odeimat ◽  
Pierre Frémont
Keyword(s):  
Skeletal Muscle ◽  
Carbonic Anhydrase ◽  
Specific Activity ◽  
Physiological Role ◽  
Electrophoretic Analysis ◽  
Carbonic Anhydrase Activity ◽  
Type I ◽  
Carbonic Anhydrase Iii ◽  
Metabolism Enzyme

Carbonic anhydrase III (EC 4.2.1.1) is the most abundant cytosolic protein in type I skeletal muscle fibers. Investigations of its physiological role have mostly been conducted with rat muscles, which sometimes are unsuitable for in vitro studies. The objective of the present study was to characterize the carbonic anhydrase in the mouse soleus muscle to verify if this muscle can be used as a model to further study the enzyme's function. Total carbonic anhydrase specific activity in the mouse soleus was comparable to the value for rat. However, 60% of the total carbonic anhydrase activity in the mouse was of the sulfonamide-sensitive type and, therefore, not related to carbonic anhydrase III. Electrophoretic analysis revealed the presence of a 29-kDa protein in total and cytosolic extracts of the mouse soleus. Immunoblotting with an antibody developed against rat carbonic anhydrase III showed that it was also specific for this 29-kDa peptide, which presumably is the mouse carbonic anhydrase III. Inhibition of the sulfonamide-sensitive activity had no effect on contractile and fatigue characteristics, whereas inhibition of the sulfonamide-resistant carbonic anhydrase III activity led to a significant increase in resistance to fatigue. We conclude that the mouse soleus may represent an excellent model to understand the contribution of different carbonic anhydrase isoforms to muscle physiology.Key words: muscle fatigue, carbonic anhydrase III, sulfonamide, metabolism, enzyme.

Tubular system membranes of teleost chloride cells: osmotic response and transport sites

1980 ◽  
Vol 238 (3) ◽  
pp. R171-R184 ◽  
Author(s):  
C. W. Philpott
Keyword(s):  
Binding Sites ◽  
Transport Model ◽  
Specific Activity ◽  
Freeze Fracture ◽  
Chloride Cells ◽  
Asymmetric Structure ◽  
Enzyme Complex ◽  
Luminal Surface ◽  
Essential Components ◽  
Tubular System

Chloride cells represent the sites of branchial osmoregulatory activity of teleosts. The cells undergo characteristic changes with osmotic challenge and the response is mediated by hormones. Either increased salinity or cortisol treatment will elicit well-known changes in chloride cells; these changes are clearly interrelated and may be collectively referred to as the “hyperosmotic response” of chloride cells. Fundamental features of the “hyperosmotic response” include proliferation and hypertrophy of chloride cells, an amplification of the cell's extensive tubular network or tubular system (TS), an increase in the specific activity of the transport-associated enzyme, Na-K-ATPase, and a concomitant increase in electrolyte transport. The TS displays frequent examples of continuity with the basolateral plasmalemma and the Na-K-ATPase enzyme complex resides in the membranes of the TS. The enzyme complex maintains its conventional polarity with regard to internal substrate and sodium binding sites and external or TS luminal surface, potassium, and ouabain binding sites. The luminal surface of the TS is anionic at pH 1.8 and above. The TS membranes display in situ, in isolation, and by freeze fracture, a characteristic asymmetric structure consisting of repeating particles; larger particles are associated with the cytoplasmic surface of the membrane and smaller particles with the external or luminal surface of tubules. The dimensions of the particles, and their disposition with respect to the cytoplasmic and external surfaces of the TS membrane, support the hypothesis that they are the visual manifestation of the transport-associated Na-K-ATPase complex. The TS and its associated transport activity represent essential components of a recently proposed paracellular transport model for chloride cells. The TS of the pseudobranch cell is also discussed in this review.

Shell repair rates and carbonic anhydrase activity during shell repair in Helisoma duryi (Mollusca)

1983 ◽  
Vol 61 (3) ◽  
pp. 597-602 ◽  
Author(s):  
S. C. Kunigelis ◽  
A. S. M. Saleuddin
Keyword(s):  
Carbonic Anhydrase ◽  
Specific Activity ◽  
Regulatory System ◽  
Carbonic Anhydrase Activity ◽  
Mantle Tissue ◽  
Deposition Rates ◽  
Single Plane ◽  
Shell Repair ◽  
Shell Regeneration ◽  
Shell Deposition

Mantle tissue carbonic anhydrase titres were found to vary with shell deposition rates. Following shell injury at the growing edge, linear shell deposition rates and mantle tissue carbonic anhydrase specific activity were found to increase significantly. Increased mantle enzyme activity was detected for a period of 10 days following injury. Replacement of shell in the region of excision was found to occur on a plane slightly lower than that of the surrounding normal shell. This requires the establishment of a new growing edge so a single plane of deposition may be restored. This suggests that the process of shell regeneration does not only include the patching of the actual injury but also allows for the establishment of a new growing edge to correct for the displacement of the plane of shell deposition. These two components of the shell regeneration process have been designated phases I and II, respectively. A third phase allows for the thickening of the mineralized layers of the newly deposited shell. Localization of elevated carbonic anhydrase activity in the portion of the mantle directly underlying the shell injury suggests that a regulatory system is present which enables the animal to detect, define, and localize shell injury repair, expediting the process.

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