Leone, Francisco A.
Lucena, Malson N.
Fabri, Leonardo M.
Garcon, Daniela P.
Fontes, Carlos F. L.
Faleiros, Rogerio O.
Moraes, Cintya M.
McNamara, John C.
Total Authors: 8
 Univ Sao Paulo, Fac Filosofia Ciencias & Letras Ribeirao Preto, Dept Quim, Ave Bandeirantes 3900, BR-14040901 Ribeirao Preto, SP - Brazil
 Univ Fed Mato Grosso do Sul, Inst Biociencias, Campo Grande, MS - Brazil
 Univ Fed Triangulo Mineiro, Iturama, MG - Brazil
 Univ Fed Rio de Janeiro, Inst Bioquim Med, Rio De Janeiro, RJ - Brazil
 Univ Fed Espirito Santo, Dept Ciencias Agr & Biol, Sao Mateus, ES - Brazil
 Univ Sao Paulo, Fac Filosofia Ciencias & Letras Ribeirao Preto, Dept Biol, Ribeirao Preto, SP - Brazil
 Univ Sao Paulo, Ctr Biol Marinha, Sao Sebastiao, SP - Brazil
Total Affiliations: 7
COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY B-BIOCHEMISTRY & MOLECULAR BIOLOGY;
Web of Science Citations:
We analyzed the modulation by exogenous FXYD2 peptide and by endogenous protein kinases A and C, and Ca2+-calmodulin-dependent kinase, of gill (Na+, K+)-ATPase activity in the semi-terrestrial mangrove crab Ucides cordatus after 10-days acclimation to different salinities. Osmotic and ionic regulatory ability and gill (Na-+,Na- K+)-ATPase activity also were evaluated. (Na+, K+)-ATPase activity is stimulated by exogenous pig kidney FXYD2 peptide, while phosphorylation by endogenous protein kinases A and C and Ca2+/calmodulin-dependent kinase inhibits activity. Stimulation by FXYD2 and inhibition by protein kinase C and Ca2+/calmodulin-dependent kinase are salinity-dependent. This is the first demonstration of inhibitory phosphorylation of a crustacean (Na+, K+)-ATPase by Ca2+/calmodulin-dependent kinase. At low salinities, the (Na+, K+)ATPase exhibited a single, low affinity ATP-binding site that showed Michaelis-Menten behavior. Above 18%S, a second, cooperative, high affinity ATP-binding site appeared, corresponding to 10-20% of total (Na+, K+)ATPase activity. Hemolymph osmolality was strongly hyper-/hypo-regulated in crabs acclimated at 2 to 35 parts per thousand S. Cl- was well hyper-/hypo-regulated although Na+ much less so, becoming isonatremic at elevated salinity. (Na+, K+)-ATPase activity was greatest in isosmotic crabs (26 parts per thousand S), decreasing notably at 35 parts per thousand S and also diminishing progressively from 18to 2 parts per thousand S. Hyper-osmoregulation in U. cordatus showed little dependence on gill (Na+, K+)-ATPase activity, suggesting a role for other ion transporters. These findings reveal that the salinity acclimation response in U. cordatus consists of a suite of enzymatic and osmoregulatory adjustments that maintain its osmotic homeostasis in a challenging, mangrove forest environment. (AU)