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(Referência obtida automaticamente do Web of Science, por meio da informação sobre o financiamento pela FAPESP e o número do processo correspondente, incluída na publicação pelos autores.)

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)

Texto completo
Autor(es):
Melo Furriel, Rosa Prazeres [1] ; Silva Firmino, Kelly Cristina [1] ; Masui, Douglas Chodi [1] ; Faleiros, Rogerio Oliveira [2] ; Torres, Antonio Hernandes [2] ; McNamara, John Campbell [2]
Número total de Autores: 6
Afiliação do(s) autor(es):
[1] Univ Sao Paulo, Dept Quim, Fac Filosofia Ciencias & Letras Ribeirao Preto, BR-14040901 Sao Paulo - Brazil
[2] Univ Sao Paulo, Dept Biol, Fac Filosofia Ciencias & Letras Ribeirao Preto, BR-14040901 Sao Paulo - Brazil
Número total de Afiliações: 2
Tipo de documento: Artigo Científico
Fonte: JOURNAL OF EXPERIMENTAL ZOOLOGY PART A-ECOLOGICAL GENETICS AND PHYSIOLOGY; v. 313A, n. 8, p. 508-523, OCT 1 2010.
Citações Web of Science: 23
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. (AU)

Processo FAPESP: 07/04870-9 - Estratégias fisiológicas adaptativas nos crustáceos: a invasão da água doce e as bases moleculares e estruturais da osmorregulação
Beneficiário:John Campbell McNamara
Linha de fomento: Auxílio à Pesquisa - Regular
Processo FAPESP: 08/57830-7 - Osmorregulacao e excrecao de amonia em crustaceos decapodes
Beneficiário:Rosa dos Prazeres Melo Furriel
Linha de fomento: Auxílio à Pesquisa - Regular