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Record 7 of 3370
Evidence for the involvement of carbonic anhydrase and urease in calcium carbonate formation in the gravity-sensing organ of Aplysia californica
External Online Source: doi:10.1007/s002239900330
Author and Affiliation:
Pedrozo, H. A.(University of Texas Health Science Center at San Antonio, Department of Physiology, 7703 Floyd Curl Drive, San Antonio, Texas 78284-7756, United States)
Schwartz, Z.
Dean, D. D.
Harrison, J. L.
Campbell, J. W.
Wiederhold, M. L.
Boyan, B. D.
Abstract: To better understand the mechanisms that could modulate the formation of otoconia, calcium carbonate granules in the inner ear of vertebrate species, we examined statoconia formation in the gravity-sensing organ, the statocyst, of the gastropod mollusk Aplysia californica using an in vitro organ culture model. We determined the type of calcium carbonate present in the statoconia and investigated the role of carbonic anhydrase (CA) and urease in regulating statocyst pH as well as the role of protein synthesis and urease in statoconia production and homeostasis in vitro. The type of mineral present in statoconia was found to be aragonitic calcium carbonate. When the CA inhibitor, acetazolamide (AZ), was added to cultures of statocysts, the pH initially (30 min) increased and then decreased. The urease inhibitor, acetohydroxamic acid (AHA), decreased statocyst pH. Simultaneous addition of AZ and AHA caused a decrease in pH. Inhibition of urease activity also reduced total statoconia number, but had no effect on statoconia volume. Inhibition of protein synthesis reduced statoconia production and increased statoconia volume. In a previous study, inhibition of CA was shown to decrease statoconia production. Taken together, these data show that urease and CA play a role in regulating statocyst pH and the formation and maintenance of statoconia. CA produces carbonate ion for calcium carbonate formation and urease neutralizes the acid formed due to CA action, by production of ammonia.
Publication Date: Sep 01, 1997
Document ID:
20040172918
(Acquired Dec 09, 2004)
Subject Category: LIFE SCIENCES (GENERAL)
Document Type: Journal Article
Publication Information: Calcified tissue international (ISSN 0171-967X); Volume 61; 3; 247-55
Publisher Information: United States
Description: In English
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: Copyright
NASA Terms: CALCIUM CARBONATES; CARBONIC ANHYDRASE; GRAVIRECEPTORS; METABOLISM; MOLLUSKS; ORGANS; ENZYMOLOGY; GRAVITATION; HOMEOSTASIS; ION CONCENTRATION; SENSE ORGANS
Other Descriptors: APLYSIA/ENZYMOLOGY/METABOLISM/ULTRASTRUCTURE; CALCIUM CARBONATE/METABOLISM; CARBONIC ANHYDRASES/METABOLISM; UREASE/METABOLISM; ANIMALS; GRAVITATION; HOMEOSTASIS; HYDROGEN-ION CONCENTRATION; IN VITRO; SENSE ORGANS/METABOLISM; SUPPORT, U.S. GOV'T, NON-P.H.S; NASA DISCIPLINE NEUROSCIENCE; NON-NASA CENTER
Availability Source: Other Sources
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