盐度对条纹鲈（Morone saxatilis）鳃离子转运蛋白表达的影响。

Effect of salinity on expression of branchial ion transporters in striped bass (Morone saxatilis).

作者信息

Tipsmark Christian Kølbaek, Madsen Steffen Søndergaard, Borski Russell John

机构信息

Department of Zoology, North Carolina State University, Raleigh, North Carolina 27695-7617, USA.

出版信息

J Exp Zool A Comp Exp Biol. 2004 Dec 1;301(12):979-91. doi: 10.1002/jez.a.119.

DOI:10.1002/jez.a.119

PMID:15562450

Abstract

The time course of osmoregulatory adjustments and expressional changes of three key ion transporters in the gill were investigated in the striped bass during salinity acclimations. In three experiments, fish were transferred from fresh water (FW) to seawater (SW), from SW to FW, and from 15-ppt brackish water (BW) to either FW or SW, respectively. Each transfer induced minor deflections in serum [Na+] and muscle water content, both being corrected rapidly (24 hr). Transfer from FW to SW increased gill Na+,K+-ATPase activity and Na+,K+,2Cl- co-transporter expression after 3 days. Abundance of Na+,K+-ATPase alpha-subunit mRNA and protein was unchanged. Changes in Na+,K+,2Cl- co-transporter protein were preceded by increased mRNA expression after 24 hr. Expression of V-type H+-ATPase mRNA decreased after 3 days. Transfer from SW to FW induced no change in expression of gill Na+,K+-ATPase. However, Na+,K+,2Cl- co-transporter mRNA and protein levels decreased after 24 hr and 7 days, respectively. Expression of H+-ATPase mRNA increased in response to FW after 7 days. In BW fish transferred to FW and SW, gill Na+,K+-ATPase activity was stimulated by both challenges, suggesting both a hyper- and a hypo-osmoregulatory response of the enzyme. Acclimation of striped bass to SW occurs on a rapid time scale. This seems partly to rely on the relative high abundance of gill Na+,K+-ATPase and Na+,K+,2Cl- co-transporter in FW fish. In a separate study, we found a smaller response to SW in expression of these ion transport proteins in striped bass when compared with the less euryhaline brown trout. In both FW and SW, NEM-sensitive gill H+-ATPase activity was negligible in striped bass and approximately 10-fold higher in brown trout. This suggests that in striped bass Na+-uptake in FW may rely more on a relatively high abundance/activity of Na+,K+-ATPase compared to trout, where H+-ATPase is critical for establishing a thermodynamically favorable gradient for Na+-uptake.

摘要

在条纹鲈适应盐度变化的过程中，研究了其鳃中渗透调节调整的时间进程以及三种关键离子转运蛋白的表达变化。在三个实验中，鱼分别从淡水（FW）转移到海水（SW）、从SW转移到FW，以及从15ppt的半咸水（BW）转移到FW或SW。每次转移都会引起血清[Na⁺]和肌肉含水量的轻微波动，两者均在24小时内迅速恢复正常。从FW转移到SW后，3天后鳃中Na⁺,K⁺-ATP酶活性和Na⁺,K⁺,2Cl⁻共转运蛋白表达增加。Na⁺,K⁺-ATP酶α亚基mRNA和蛋白质的丰度没有变化。24小时后，Na⁺,K⁺,2Cl⁻共转运蛋白mRNA表达增加，随后蛋白质发生变化。3天后，V型H⁺-ATP酶mRNA表达下降。从SW转移到FW后，鳃中Na⁺,K⁺-ATP酶的表达没有变化。然而，Na⁺,K⁺,2Cl⁻共转运蛋白mRNA和蛋白质水平分别在24小时和7天后下降。7天后，H⁺-ATP酶mRNA表达因转移到FW而增加。在转移到FW和SW的BW鱼中，两种挑战均刺激了鳃中Na⁺,K⁺-ATP酶活性，表明该酶具有高渗和低渗调节反应。条纹鲈对SW的适应在较短时间内发生。这似乎部分依赖于FW鱼中鳃Na⁺,K⁺-ATP酶和Na⁺,K⁺,2Cl⁻共转运蛋白相对较高的丰度。在另一项研究中，我们发现与广盐性较差的褐鳟相比，条纹鲈中这些离子转运蛋白对SW的表达反应较小。在FW和SW中，条纹鲈鳃中对NEM敏感的H⁺-ATP酶活性可忽略不计，而在褐鳟中则高约10倍。这表明，与鳟鱼相比，条纹鲈在FW中摄取Na⁺可能更多地依赖于Na⁺,K⁺-ATP酶相对较高的丰度/活性，在鳟鱼中，H⁺-ATP酶对于建立有利于Na⁺摄取的热力学梯度至关重要。