Department of Biology, Faculty of Marine and Environmental Sciences, Instituto Universitario de Investigación Marina (INMAR), Campus de Excelencia Internacional del Mar (CEI-MAR) University of Cadiz, 11510, Puerto Real, Cádiz, Spain.
Laboratory of Ecophysiology and Molecular Evolution, Brazilian National Institute for Research of the Amazon, Manaus, AM, Brazil; Graduate Program at Inland Fisheries and Freshwater Biology, Brazilian National Institute for Research of the Amazon, Manaus, AM, Brazil.
Comp Biochem Physiol A Mol Integr Physiol. 2020 Jul;245:110706. doi: 10.1016/j.cbpa.2020.110706. Epub 2020 Apr 15.
Stress responses in teleosts include the release of hormones into the bloodstream. Their effects depend on the species and on the environmental conditions. The Amazon basin collects waters of diverse chemical composition, and some fish are able to inhabit several of them. However, the effects of these waters on the stress axis are still unknown. Here we show how acute air-exposure differently affects stress biomarkers in tambaqui (Colossoma macropomum), a tropical model species, when acclimated to two Amazonian waters (Rio Negro -RN- water rich in humic acids and poor in ions, and groundwater -IG- with no humic acids and higher concentration of ions). This study described primary and secondary stress responses after air exposure including plasma cortisol, energy metabolites, pH and ions, skin mucus energy metabolites, as well as gills and kidney Na/K-ATPase and Na/H-exchanger (NHE) activities. Several differences were described in these stress biomarkers due to the acclimation water. The most remarkable ones include increased mucus glucose only in RN-fish, and mucus lactate only in IG-fish after air exposure. Moreover, an inverse relationship between plasma cortisol and Na concentrations as well as a direct relationship between plasma ammonia and branchial NHE activity were observed only in RN-fish. Our results demonstrate how important is to study stress responses in fish acclimated to different environments, as physiological differences can be magnified during episodes of high energy expenditure. In addition to having a direct application in aquaculture, this study will improve the management of critical ecosystems such as the Amazon.
硬骨鱼类的应激反应包括将激素释放到血液中。它们的影响取决于物种和环境条件。亚马逊盆地汇集了多种化学成分的水，有些鱼类能够栖息在其中的几种水中。然而，这些水对应激轴的影响尚不清楚。在这里，我们展示了热带模式物种巨臀脂鲤（Colossoma macropomum）在适应两种亚马逊水（富含腐殖酸、离子贫乏的黑河（Rio Negro）水和没有腐殖酸、离子浓度较高的地下水（IG））后，急性空气暴露如何不同地影响应激生物标志物。本研究描述了空气暴露后的初级和次级应激反应，包括血浆皮质醇、能量代谢物、pH 值和离子、皮肤黏液能量代谢物以及鳃和肾脏 Na/K-ATP 酶和 Na/H-交换器（NHE）活性。由于适应水的不同，这些应激生物标志物存在一些差异。最显著的差异包括空气暴露后，仅在 RN 鱼类的黏液中葡萄糖增加，仅在 IG 鱼类的黏液中乳酸增加。此外，仅在 RN 鱼类中观察到血浆皮质醇与 Na 浓度之间呈负相关，以及血浆氨与鳃 NHE 活性之间呈正相关。我们的研究结果表明，研究适应不同环境的鱼类的应激反应是非常重要的，因为在高能量消耗期间，生理差异可能会放大。除了在水产养殖中有直接应用外，本研究还将改善亚马逊等关键生态系统的管理。
