title: Immunolocalization of Na+,K+-ATPase in the branchial cavity during the early development of the crayfish Astacus leptodactylus (Crustacea, Decapoda).
abstract: The ontogeny of osmoregulation was examined in the branchial cavity of embryonic and early post-embryonic stages of the crayfish Astacus leptodactylus maintained in freshwater, at the sub-cellular level through the detection of the sodium-potassium adenosine triphosphatase (Na(+),K(+)-ATPase). The embryonic rate of development was calculated according to the eye index (EI) which was 430-450 microm at hatching. The distribution of the enzyme was identified by immunofluorescence microscopy using a monoclonal antibody IgGalpha5 raised against the avian alpha-subunit of the Na(+),K(+)-ATPase. Immunoreactivity staining, indicating the presence of Na(+), K(+)-ATPase appeared in the gills of late embryos (EI>/=400 microm), i.e. a few days before hatching time, and steadily increased throughout the late embryonic and early post-embryonic development. The appearance of the enzyme correlates with the ability to osmoregulate which also occurs late in the embryonic development at EI 410-420 microm and with tissue differentiation within the gill filaments. These observations indicate that the physiological shift from osmoconforming embryos to hyper-regulating late embryos and post-hatching stages in freshwater must originate partly from the differentiation in the gill epithelia of ionocytes which are the site of ion pumping, as suggested by the location of Na(+),K(+)-ATPase. Only the gills were immunostained and a lack of specific staining was noted in the lamina and the branchiostegites. Therefore, osmoregulation through Na(+)active uptake is likely achieved in embryos at the gill level; all the newly formed gills in embryos function in ion regulation; other parts of the branchial chamber such as the branchiostegites and lamina do not appear to be involved in osmoregulation.
authors.affiliation: Centre d'Ecologie et de Physiologie Energétiques CEPE-CNRS, UPR 9010, 23 Rue Becquerel, 67087 Strasbourg, France. j-h.lignot@c-strasbourg.fr
authors.forename: Jean-Hervé
authors.initials: JH
authors.lastname: Lignot
authors.forename: Gregorius Nugroho
authors.initials: GN
authors.lastname: Susanto
authors.forename: Mireille
authors.initials: M
authors.lastname: Charmantier-Daures
authors.forename: Guy
authors.initials: G
authors.lastname: Charmantier
mesh_terms: D000818:Animals; D003400:Astacoidea / Q000196:embryology* / Q000201:enzymology / Q000648:ultrastructure; D047108:Embryonic Development; D005260:Female; D016650:Fluorescein-5-isothiocyanate; D019084:Fluorescent Antibody Technique, Indirect; D005456:Fluorescent Dyes; D007150:Immunohistochemistry; D018613:Microscopy, Confocal; D008855:Microscopy, Electron, Scanning; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D005456:Fluorescent Dyes; D000254:Sodium-Potassium-Exchanging ATPase; D016650:Fluorescein-5-isothiocyanate