Structural and Biochemical Correlates of Na(+), K(+)-ATPase Driven Ion Uptake Across the Posterior Gill Epithelium of the True Freshwater Crab, Dilocarcinus pagei (Brachyura, Trichodactylidae)


Autoria(s): FURRIEL, Rosa Prazeres Melo; FIRMINO, Kelly Cristina Silva; MASUI, Douglas Chodi; FALEIROS, Rogerio Oliveira; TORRES, Antonio Hernandes; MCNAMARA, John Campbell
Contribuinte(s)

UNIVERSIDADE DE SÃO PAULO

Data(s)

19/10/2012

19/10/2012

2010

Resumo

To better comprehend the structural and biochemical underpinnings of ion uptake across the gills of true freshwater crabs, we performed an ultrastructural, ultracytochemical and morphometric investigation, and kinetically characterized the Na(+), K(+)-ATPase, in posterior gill lamellae of Dilocarcinus pagei. Ultrastructurally, the lamellar epithelia are markedly asymmetrical: the thick, mushroom-shaped, proximal ionocytes contain elongate mitochondria (41% cell volume) associated with numerous (approximate to 14 mu m(2) membrane per mu m(3) cytoplasm), deep invaginations that house the Na(+), K(+)-ATPase, revealed ultracytochemically. Their apical surface is amplified (7.5 mu m(2) mu m(-2)) by stubby evaginations whose bases adjoin mitochondria below the subcuticular space. The apical membrane of the thin, distal ionocytes shows few evaginations (1.6 mu m(2) mu m(-2)), each surrounding a mitochondrion, abundant in the cytoplasm below the subcuticular space; basolateral invaginations and mitochondria are few. Fine basal cytoplasmic bridges project across the hemolymph space, penetrating into the thick ionocytes, suggesting ion movement between the epithelia. Microsomal Na(+), K(+)-ATPase specific activity resembles marine crabs but is approximate to 5-fold less than in species from fluctuating salinities, and freshwater shrimps, suggesting ion loss compensation by strategies other than Na(+) uptake. Enzyme apparent K(+) affinity attains 14-fold that of marine crabs, emphasizing the relevance of elevated K(+) affinity to the conquest of fresh water. Western blotting and biphasic ouabain inhibition disclose two alpha-subunit isoforms comprising distinct functional isoenzymes. While enzyme activity is not synergistically stimulated by NH(4)(+) and K(+), each increases affinity for the other, possibly assuring appropriate intracellular K(+) concentrations. These findings reveal specific structural and biochemical adaptations that may have allowed the establishment of the Brachyura in fresh water. J. Exp. Zool. 313A:508-523, 2010. (C) 2010 Wiley-Liss, Inc.

CNPq

FAPESP

FAPESP Fundacao de Amparo a Pesquisa do Estado de Sao Paulo[2008/57830-7]

FAPESP Fundacao de Amparo a Pesquisa do Estado de Sao Paulo[2007/04870-9]

Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq)[471933/2008-2]

Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq)[304174/2006-8]

Identificador

JOURNAL OF EXPERIMENTAL ZOOLOGY PART A-ECOLOGICAL GENETICS AND PHYSIOLOGY, v.313A, n.8, p.508-523, 2010

1932-5223

http://producao.usp.br/handle/BDPI/20970

10.1002/jez.622

http://dx.doi.org/10.1002/jez.622

Idioma(s)

eng

Publicador

WILEY-BLACKWELL

Relação

Journal of Experimental Zoology Part A-ecological Genetics and Physiology

Direitos

restrictedAccess

Copyright WILEY-BLACKWELL

Palavras-Chave #SHRIMP MACROBRACHIUM-OLFERSII #BLUE-CRAB #AMMONIA EXCRETION #CALLINECTES-SAPIDUS #ALPHA-SUBUNIT #SHORE CRAB #MICROSOMAL (NA+,K+)-ATPASE #CHASMAGNATHUS-GRANULATUS #NA+,K+-ATPASE ACTIVITY #CONCENTRATED SEAWATER #Zoology
Tipo

article

original article

publishedVersion