Epidermal carbonic anhydrase activity and exoskeletal metal content during the molting cycle of the blue crab,Callinectes sapidus

2016 ◽  
Vol 325 (3) ◽  
pp. 200-208 ◽  
Author(s):  
Stacy Calhoun ◽  
Enmin Zou
Keyword(s):  
Carbonic Anhydrase ◽  
Blue Crab ◽  
Metal Content ◽  
Callinectes Sapidus ◽  
Carbonic Anhydrase Activity ◽  
Molting Cycle

scholarly journals BIOCHEMICAL AND ULTRASTRUCTURAL ASPECTS OF CA2+ TRANSPORT BY MITOCHONDRIA OF THE HEPATOPANCREAS OF THE BLUE CRAB CALLINECTES SAPIDUS

1974 ◽  
Vol 61 (2) ◽  
pp. 301-315 ◽  
Author(s):  
Chung-Ho Chen ◽  
John W. Greenawalt ◽  
Albert L. Lehninger
Keyword(s):  
Calcium Phosphate ◽  
Blue Crab ◽  
Atp Hydrolysis ◽  
Callinectes Sapidus ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Molting Cycle ◽  
Hypertonic Medium ◽  
Dense Deposits ◽  
Crab Hepatopancreas

Mitochondria isolated from the hepatopancreas of the blue crab Callinectes sapidus show up to 12-fold stimulation of respiration on addition of Ca2+, which is accompanied by Ca2+ accumulation (Ca2+:site = 1.9) and H+ ejection (H+:Ca2+ = 0.85). Sr2+ and Mn2+ are also accumulated; Mg2+ is not. A strongly hypertonic medium (383 mosM), Mg2+, and phosphate are required for maximal Ca2+ uptake. Ca2+ uptake takes precedence over oxidative phosphorylation of ADP for respiratory energy. Once Ca2+ is accumulated by the crab mitochondria, it is stable and only very slowly released, even by uncoupling agents. ATP hydrolysis also supports Ca2+ uptake. Respiration-inhibited crab hepatopancreas mitochondria show both high-affinity and low-affinity Ca2+-binding sites, which are inactive in the presence of uncoupling agents. Crab hepatopancreas mitochondria have an enormous capacity for accumulation of Ca2+, up to 5,500 ng-atoms Ca2+ per mg protein, with an equivalent amount of phosphate. Freshly isolated mitochondria contain very large amounts of Ca2+, Mg2+, phosphate, K+, and Na+; their high Ca2+ content is a reflection of the vary large amount of extra-mitochondrial Ca2+ in the whole tissue. Electron microscopy of crab mitochondria loaded with Ca2+ and phosphate showed large electron-dense deposits, presumably of precipitated calcium phosphate. They consisted of bundles of needle-like crystals, whereas Ca2+-loaded rat liver mitochondria show only amorphous deposits of calcium phosphate under similar conditions. The very pronounced capacity of crab hepatopancreas mitochondria for transport of Ca2+ appears to be adapted to a role in the storage and release of Ca2+ during the molting cycle of this crustacean.

scholarly journals Acid-Base Balance in Callinectes Sapidus During Acclimation from High to Low Salinity

1982 ◽  
Vol 101 (1) ◽  
pp. 255-264 ◽  
Author(s):  
RAYMOND P. HENRY ◽  
JAMES N. CAMERON
Keyword(s):  
Carbonic Anhydrase ◽  
Blue Crab ◽  
Callinectes Sapidus ◽  
Weak Acid ◽  
Strong Ion Difference ◽  
Acid Base Balance ◽  
Acid Base ◽  
Ion Regulation ◽  
Low Salinity ◽  
Base Balance

When transferred from 865 to 250 m-osmol salinity, the blue crab C. sapidus maintains its blood Na+ and Cl− concentrations significantly above those in the medium. When branchial carbonic anhydrase is inhibited by acetazolamide, ion regulation fails and the animals do not survive the transfer. An alkalosis occurs in the blood at low salinity, indicated by an increase in HCO3− and pH at constant PCO2. The alkalosis is closely correlated with an increase in the Na+-Cl− difference, a convenient indicator of the overall strong ion difference. The contribution of changes in PCO2 to acid-base changes was negligible, but the change in the total weak acid (proteins) may be important. It is suggested that the change in blood acidbase status with salinity is related to an increase in the strong ion difference, which changes during the transition from osmoconformity to osmoregulation in the blue crab, and which is related to both carbonic anhydrase and ionactivated ATPases. Note:

Membrane-associated carbonic anhydrase in gills of the blue crab, Callinectes sapidus

1987 ◽  
Vol 252 (5) ◽  
pp. R966-R971 ◽  
Author(s):  
R. P. Henry
Keyword(s):  
Carbonic Anhydrase ◽  
Blue Crab ◽  
Callinectes Sapidus ◽  
Rapid Development ◽  
Respiratory Acidosis ◽  
Basal Membrane ◽  
Ion Regulation ◽  
Co2 Excretion

The presence of the enzyme carbonic anhydrase (CA) on the basal membrane of the branchial endothelial cells in the blue crab and its physiological significance were studied in vivo using a membrane-impermeant CA inhibitor, quaternary ammonium sulfanilamide (QAS). Injection of QAS into the hemolymph of Callinectes sapidus resulted in the rapid development of a respiratory acidosis; PCO2 rose almost 2 Torr, pH was lowered by approximately 0.25 units, and total CO2 rose by 2 mM. These results support the hypothesis that membrane-associated CA exposed to hemolymph is present in the crustacean gill and that it is physiologically significant in mobilizing hemolymph HCO-3 to CO2 to facilitate CO2 excretion across the gill. The recovery from this acidosis coincides with the clearance of the inhibitor from the hemolymph. Hemolymph osmotic and ionic parameters were unaffected by QAS, reconfirming the role of branchial cytoplasmic CA in ion regulation and also providing a convenient bioassay for determining CA inhibitor permeability in the intact organism.

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