Uptake of L- and D-alanine by a brackish-water Bivalve, Corbicula japonica, with special reference to their transport pathways and the salinity effect
Uptake of L- and D-alanine by a brackish-water Bivalve, Corbicula japonica, with special reference to their transport pathways and the salinity effect
复制标题
咸水双壳类蚬对 L- 和 D-丙氨酸的吸收，特别是它们的运输途径和盐度效应
DOI：
10.1002/jez.1402630103
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发表时间：
1992
影响因子：
--
通讯作者：
Ayumu Yamada
中科院分区：
文献类型：
--
作者：
O. Matsushima;Ayumu Yamada
本文研究了微咸水双壳贝体动物和离体鳃对L-丙氨酸和D-丙氨酸的摄取及其转运途径和可能的生理作用。动物对L丙氨酸的摄取浓度低至10μM，净转运和净流入均受外界盐度的强烈影响，适应淡水的动物的净转运和净流入速率远低于适应250mOsm的动物。~(14)C-L-丙氨酸在完整动物不同组织中的积累模式表明，鳃是该氨基酸的主要转运部位。14C-L和14C-D-丙氨酸均被α-中性氨基酸抑制，但不被α-酸性或β-氨基酸抑制；所有α-中性氨基酸(甘氨酸、L-谷氨酰胺、L-亮氨酸、L-缬氨酸，甚至D-和L-丙氨酸)对D-丙氨酸内流的抑制作用强于L-丙氨酸。动力学分析表明，D-丙氨酸和L-丙氨酸通过同一载体(S)转运，但载体(S)对L-丙氨酸的亲和力高于对D-丙氨酸的亲和力。转运机制似乎在D-丙氨酸和L-丙氨酸的净摄取或从被膜扩散的氨基酸的重新摄取中发挥着重要作用，这取决于底物的周围浓度。©1992 Wiley-Liss，Inc.
The uptake of L- and D-alanine by intact animals or isolated gills of a brackish-water bivalve, Corbicula japonica, was investigated in relation to their transport pathways and the possible physiological roles. The animals took up L-alanine at concentrations as low as 10 μM. Both the net transport and the influx were strongly affected by external salinity; animals acclimated to fresh water showed much lower rates of net transport and influx than did animals acclimated to 250 mOsm. Patterns of accumulation of 14C-L-alanine in different tissues of intact animals revealed that the gill was the principal site for the transport of the amino acid. Influx of both 14C-L- and 14C-D-alanine into isolated gills was inhibited by α-neutral amino acids, but not by α-acidic or β-amino acids; all α-neutral amino acids examined (glycine, L-glutamine, L-leucine, L-valine, and even D- and L-alanine) inhibited the influx of D-alanine more strongly than the influx of L-alanine. Kinetic analysis of the influx indicated that D- and L-alanine were transported via the same carrier(s), but that the carrier(s) had a higher affinity for L-alanine than for D-alanine. The transport mechanism appears to play a significant role in the net uptake of D- and L-alanine or in the re-uptake of the amino acids diffused from the integument according to the ambient concentrations of the substrates. © 1992 Wiley-Liss, Inc.