Sodium uptake in different life stages of crustaceans: the water fleaDaphnia magnaStrauss

Author:

Bianchini Adalto1,Wood Chris M.2

Affiliation:

1. Fundação Universidade Federal do Rio Grande, Departamento de Ciências Fisiológicas, Campus Carreiros, Av. Itália s/n,96.201-900 Rio Grande, RS, Brazil

2. McMaster University, Department of Biology, 1280 Main Street West, Hamilton,ON, L8S 4K1, Canada

Abstract

SUMMARYThe concentration-dependent kinetics and main mechanisms of whole-body Na+ uptake were assessed in neonate and adult water flea Daphnia magna Strauss acclimated to moderately hard water (0.6 mmol l–1 NaCl, 1.0 mmol l–1 CaCO3 and 0.15 mmol l–1 MgSO4·7H2O; pH 8.2). Whole-body Na+ uptake is independent of the presence of Cl– in the external medium and kinetic parameters are dependent on the life stage. Adults have a lower maximum capacity of Na+ transport on a mass-specific basis but a higher affinity for Na+ when compared to neonates. Based on pharmacological analyses,mechanisms involved in whole-body Na+ uptake differ according to the life stage considered. In neonates, a proton pump-coupled Na+channel appears to play an important role in the whole-body Na+uptake at the apical membrane. However, they do not appear to contribute to whole-body Na+ uptake in adults, where only the Na+channel seems to be present, associated with the Na+/H+exchanger. In both cases, carbonic anhydrase contributes by providing H+ for the transporters. At the basolateral membrane of the salt-transporting epithelia of neonates, Na+ is pumped from the cells to the extracellular fluid by a Na+,K+-ATPase and a Na+/Cl– exchanger whereas K+ and Cl– move through specific channels. In adults, a Na+/K+/2Cl– cotransporter replaces the Na+/Cl– exchanger. Differential sensitivity of neonates and adults to iono- and osmoregulatory toxicants, such as metals, are discussed with respect to differences in whole-body Na+ uptake kinetics, as well as in the mechanisms of Na+ transport involved in the whole-body Na+ uptake in the two life stages.

Publisher

The Company of Biologists

Subject

Insect Science,Molecular Biology,Animal Science and Zoology,Aquatic Science,Physiology,Ecology, Evolution, Behavior and Systematics

同舟云学术

1.学者识别学者识别

2.学术分析学术分析

3.人才评估人才评估

"同舟云学术"是以全球学者为主线,采集、加工和组织学术论文而形成的新型学术文献查询和分析系统,可以对全球学者进行文献检索和人才价值评估。用户可以通过关注某些学科领域的顶尖人物而持续追踪该领域的学科进展和研究前沿。经过近期的数据扩容,当前同舟云学术共收录了国内外主流学术期刊6万余种,收集的期刊论文及会议论文总量共计约1.5亿篇,并以每天添加12000余篇中外论文的速度递增。我们也可以为用户提供个性化、定制化的学者数据。欢迎来电咨询!咨询电话:010-8811{复制后删除}0370

www.globalauthorid.com

TOP

Copyright © 2019-2024 北京同舟云网络信息技术有限公司
京公网安备11010802033243号  京ICP备18003416号-3