Permeability and the mechanism of transport of boric acid across the plasma membrane of Xenopus laevis oocytes

被引:24
作者
Dordas, C [1 ]
Brown, PH [1 ]
机构
[1] Univ Calif Davis, Dept Pomol, Davis, CA 95616 USA
关键词
boric acid; permeability; uptake; boron; liposomes; oocytes;
D O I
10.1385/BTER:81:2:127
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
Boron is an essential element for vascular plants and for diatoms, cyanobacteria, and a number of species of marine algal flagellates. Boron was recently established as an essential micronutrient for frogs (Xenopus laevis) and preliminary evidence suggests that it may be essential for all animals. The main form of B, which is available in the natural environment, is in the form of undissociated boric acid. The permeability coefficient and the mechanism of transport of boric acid, however, have not been experimentally determined across any animal membrane or cell. In the experiments described here, the permeability coefficient of boric acid in Xenopus oocytes was 1.5 X 10(-6) cm/s, which is very close with the permeability across liposomes made with phosphatidylcholine and cholesterol (the major lipids in the oocyte membrane). Moreover, we investigated the mechanism of boric acid movement across the membrane of Xenopus oocytes and we compared it with the transport across artificial liposomes. The transport of boric acid across Xenopus oocytes was not affected by inhibitors such as HgCl2, phloretin, or 4,4-diisothiocyanatostilbene-2,2 ' -D-sulfonic acid (DIDS). The kinetics of B uptake was linear with concentration changes, and the permeability remained the same at different external boric acid concentrations. These results suggest that B transport occurs via simple passive diffusion through the lipid bilayer in Xenopus oocytes.
引用
收藏
页码:127 / 139
页数:13
相关论文
共 33 条
[1]   CHARACTERISTICS OF BORON ABSORPTION BY EXCISED BARLEY ROOTS [J].
BINGHAM, FT ;
ELSEEWI, A ;
OERTLI, JJ .
SOIL SCIENCE SOCIETY OF AMERICA PROCEEDINGS, 1970, 34 (04) :613-&
[2]  
BROWN PH, 1994, PHYSIOL PLANTARUM, V91, P435, DOI 10.1111/j.1399-3054.1994.tb02971.x
[3]  
Dannel F, 2000, AUST J PLANT PHYSIOL, V27, P397
[4]   OSMOTIC BEHAVIOR AND PERMEABILITY PROPERTIES OF LIPOSOMES [J].
DEGIER, J .
CHEMISTRY AND PHYSICS OF LIPIDS, 1993, 64 (1-3) :187-196
[5]   Permeability and channel-mediated transport of boric acid across membrane vesicles isolated from squash roots [J].
Dordas, C ;
Chrispeels, MJ ;
Brown, PH .
PLANT PHYSIOLOGY, 2000, 124 (03) :1349-1361
[6]   Permeability of boric acid across lipid bilayers and factors affecting it [J].
Dordas, C ;
Brown, PH .
JOURNAL OF MEMBRANE BIOLOGY, 2000, 175 (02) :95-105
[7]  
Finkelstein A., 1987, Water Movement Through Lipid Bilayers, Pores, and Plasma Membranes: Theory and Reality
[8]   Adverse reproductive and developmental effects in Xenopus from insufficient boron [J].
Fort, DJ ;
Propst, TL ;
Stover, EL ;
Strong, PL ;
Murray, FJ .
BIOLOGICAL TRACE ELEMENT RESEARCH, 1998, 66 (1-3) :237-259
[9]  
Greenwood N. N., 1973, COMPREHENSIVE INORGA, P665
[10]  
HAINES TH, 1995, PERMEABILITY STABILI