Chloride turnover and ion-transporting activities of yolk-sac preparations (yolk balls) separated from Mozambique tilapia embryos and incubated in freshwater and seawater.
J Exp Biol
; 208(Pt 20): 3851-8, 2005 Oct.
Article
en En
| MEDLINE
| ID: mdl-16215213
ABSTRACT
We have recently established a unique in vitro experimental model for mitochondrion-rich cell (MRC) research, a ;yolk-ball' incubation system, in which the yolk sac is separated from the embryonic body of Mozambique tilapia embryos and subjected to in vitro incubation. To evaluate the ion-transporting property of the yolk balls, we examined Cl- content and turnover in yolk balls incubated in freshwater and seawater for 48 h, and distribution patterns of three ion transporters, Na+/K+-ATPase, Na+/K+/2Cl- cotransporter (NKCC) and cystic fibrosis transmembrane conductance regulator (CFTR), in MRCs in the yolk-sac membrane. The Cl- turnover rate measured by whole-body influx of 36Cl- was about 60 times higher in yolk balls in seawater than in freshwater, while there was no essential difference in Cl- content between them. Na+/K+-ATPase-immunoreactive MRCs were larger in yolk balls from seawater than yolk balls from freshwater. Distribution patterns of ion-transporting proteins allowed us to classify MRCs in freshwater yolk balls into three types cells showing only basolateral Na+/K+-ATPase, cells showing basolateral Na+/K+-ATPase and apical NKCC, and cells showing basolateral Na+/K+-ATPase and basolateral NKCC. The seawater yolk balls, on the other hand, were characterized by the appearance of MRCs possessing basolateral Na+/K+-ATPase, basolateral NKCC and apical CFTR. Those seawater-type MRCs were considered to secrete Cl- through the CFTR-positive apical opening to cope with diffusional Cl- influx. These findings indicate that the yolk balls preserve the Cl- transporting property of intact embryos, ensuring the propriety of the yolk ball as an in vitro experimental model for the yolk-sac membrane that contains MRCs.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Agua de Mar
/
Saco Vitelino
/
Cloruros
/
Tilapia
/
Transporte Iónico
/
Agua Dulce
Tipo de estudio:
Prognostic_studies
Límite:
Animals
País/Región como asunto:
Africa
Idioma:
En
Revista:
J Exp Biol
Año:
2005
Tipo del documento:
Article
País de afiliación:
Japón