Scanning ion-selective electrode technique and X-ray microanalysis provide direct evidence of contrasting Na+transport ability from root to shoot in salt-sensitive cucumber and salt-tolerant pumpkin under NaCl stress

2014 ◽  
Vol 152 (4) ◽  
pp. 738-748 ◽  
Author(s):  
Bo Lei ◽  
Yuan Huang ◽  
Jingyu Sun ◽  
Junjun Xie ◽  
Mengliang Niu ◽  
...  
Keyword(s):  
Direct Evidence ◽  
Nacl Stress ◽  
Ion Selective Electrode ◽  
Salt Tolerant ◽  
Na Transport ◽  
Selective Electrode ◽  
X Ray ◽  
Electrode Technique

Ammonia excretion by the skin of zebrafish (Danio rerio) larvae

2008 ◽  
Vol 295 (6) ◽  
pp. C1625-C1632 ◽  
Author(s):  
Tin-Han Shih ◽  
Jiun-Lin Horng ◽  
Pung-Pung Hwang ◽  
Li-Yih Lin
Keyword(s):  
Direct Evidence ◽  
Ammonia Excretion ◽  
Bafilomycin A1 ◽  
Selective Electrode ◽  
Zebrafish Larvae ◽  
Trapping Mechanism ◽  
Morpholino Oligonucleotides ◽  
Electrode Technique ◽  
External Ph ◽  
Freshwater Teleosts

The mechanism of ammonia excretion in freshwater teleosts is not well understood. In this study, scanning ion-selective electrode technique was applied to measure H+ and NH4+ fluxes in specific cells on the skin of zebrafish larvae. NH4+ extrusion was relatively high in H+ pump-rich cells, which were identified as the H+-secreting ionocyte in zebrafish. Minor NH4+ extrusion was also detected in keratinocytes and other types of ionocytes in larval skin. NH4+ extrusion from the skin was tightly linked to acid secretion. Increases in the external pH and buffer concentration (5 mM MOPS) diminished H+ and NH4+ gradients at the larval surface. Moreover, coupled decreases in NH4+ and H+ extrusion were found in larvae treated with an H+-pump inhibitor (bafilomycin A1) or H+-pump gene ( atp6v1a) knockdown. Knockdown of Rhcg1 with morpholino-oligonucleotides also decreased NH4+ excretion. This study demonstrates ammonia excretion in epithelial cells of larval skin through an acid-trapping mechanism, and it provides direct evidence for the involvement of the H+ pump and an Rh glycoprotein (Rhcg1) in ammonia excretion.

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