Amelio Daniela, Garofalo Filippo, Brunelli Elvira, Loong Ai May, Wong Wai Peng, Ip Yuen Kwong, Tota Bruno, Cerra Maria Carmela
Department of Cellular Biology, University of Calabria, 87030 Arcavacata di Rende, CS, Italy.
Nitric Oxide. 2008 Feb;18(1):1-10. doi: 10.1016/j.niox.2007.10.004. Epub 2007 Oct 30.
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.
非洲肺鱼多鳍鱼是一种必须进行空气呼吸的鱼类，在旱季会在茧中夏眠。夏眠与包括心脏和肾脏在内的许多组织和器官的功能改变有关。由于一氧化氮合酶（NOSs）产生的一氧化氮（NO）具有多效性调节作用，它可能协调器官重排，使机体在压力环境条件下进行适应性调整。通过免疫荧光、蛋白质免疫印迹和NADPH黄递酶法，我们检测了淡水环境（FW）以及夏眠状态下（夏眠6天和40天）的多鳍鱼心脏和肾脏中NOS同工型的定位和活性。在心脏和肾脏中，内皮型一氧化氮合酶（eNOS）相对于诱导型一氧化氮合酶和神经型一氧化氮合酶（分别为iNOS和nNOS）是主要的同工型。心脏eNOS定位于淡水鱼和夏眠鱼的心外膜、小梁状内皮心内膜以及心肌细胞中。蛋白质免疫印迹显示，心脏eNOS的表达在夏眠6天的鱼中增加，但在夏眠40天的鱼中减少。在淡水鱼的肾脏中，eNOS存在于血管内皮细胞和肾小体的足细胞中。在肾小管上皮细胞中，它仅限于顶端。随着夏眠的进行，eNOS在肾脏中的定位和表达均增加。NADPH黄递酶显示在夏眠期间心脏和肾脏的NOS活性增强。结果表明，在多鳍鱼中，NO以自分泌-旁分泌方式在夏眠期间对心脏和肾脏的重新调整起作用。我们的发现具有进化意义，因为它们首次证明了在一种原始鱼类中存在NOS系统，这表明NO生物合成具有深厚的系统发育根源。
