title: Differential NOS expression in freshwater and aestivating Protopterus dolloi (lungfish): heart vs kidney readjustments.
abstract: African lungfish Protopterus dolloi is an obligatory air-breather, which aestivates in a cocoon during the dry season. Aestivation associates with functional modifications in many tissues and organs, including heart and kidney. Due to its pleiotropic modulatory effects, nitric oxide (NO), generated by nitric oxide synthases (NOSs), may coordinate organ rearrangement, allowing adaptive adjustments under stressful environmental conditions. By immunofluorescence, Western blotting and NADPH-diaphorase, we examined cardiac and renal localization and activity of NOSs isoforms in both freshwater (FW) and aestivating [6 days (6DA) and 40 days (40DA) of estivation] P. dolloi. In heart and kidney endothelial NOS (eNOS) is the major isoform with respect to inducible and neuronal NOS (iNOS and nNOS, respectively). Cardiac eNOS locates in the epicardium, the trabecular endothelial endocardium, and myocardiocytes of both FW and aestivating fish. Western blotting revealed that cardiac eNOS expression increases in 6DA, but decreases in 40DA fish. In FW fish kidney eNOS is present in vascular endothelial cells and in podocytes of renal corpuscles. In tubular epithelial cells it is restricted to the apical pole. With aestivation, both renal localization and expression of eNOS increase. NADPH-diaphorase revealed an enhancement of cardiac and renal NOS activities during aestivation. Results suggest that in P. dolloi NO contributes, in an autocrine-paracrine fashion, to cardiac and renal readjustments during aestivation. Our findings are of evolutionary interest, since they document for the first time the presence of a NOS system in a ancestral fish, indicative of deep phylogenetic roots of NO bio-synthesis.
authors.affiliation: Department of Cellular Biology, University of Calabria, 87030 Arcavacata di Rende, CS, Italy.
authors.forename: Daniela
authors.initials: D
authors.lastname: Amelio
authors.forename: Filippo
authors.initials: F
authors.lastname: Garofalo
authors.forename: Elvira
authors.initials: E
authors.lastname: Brunelli
authors.forename: Ai May
authors.initials: AM
authors.lastname: Loong
authors.forename: Wai Peng
authors.initials: WP
authors.lastname: Wong
authors.forename: Yuen Kwong
authors.initials: YK
authors.lastname: Ip
authors.forename: Bruno
authors.initials: B
authors.lastname: Tota
authors.forename: Maria Carmela
authors.initials: MC
authors.lastname: Cerra
mesh_terms: D000818:Animals; D015153:Blotting, Western; D004956:Estivation / Q000502:physiology*; D005399:Fishes / Q000378:metabolism*; D005618:Fresh Water; D007150:Immunohistochemistry; D007668:Kidney / Q000378:metabolism*; D009206:Myocardium / Q000378:metabolism*; D009252:NADPH Dehydrogenase / Q000032:analysis; D019001:Nitric Oxide Synthase / Q000032:analysis* / Q000096:biosynthesis*
chemical_list: D019001:Nitric Oxide Synthase; D009252:NADPH Dehydrogenase