Schneegurt M A, McDaniel C N
Department of Biology, Rensselaer Polytechnic Institute, Troy, New York 12180-3590.
Plant Physiol. 1986 May;81(1):36-40. doi: 10.1104/pp.81.1.36.
The rate at which l-leucine was transported into suspension-cultured Nicotiana tabacum cv Wisconsin 38 cells increased more than 2-fold over a period of hours when the cells were preincubated in a 1% sucrose solution. This increase in uptake rate was eliminated if certain tris buffers were included in the preincubation solution while other buffers had little effect. Calcium could reverse the effect of the inhibitory buffers only if the buffer and calcium were present together from the beginning of the preincubation period. It was the amine group of the inhibitory buffers which was responsible for the inhibition. Preincubation in a complete culture medium (EM Linsmaier, F Skoog 1965 Physiol Plant 18: 100-127) led to minimal changes in l-leucine uptake rate over a 10 hour preincubation period indicating that the uptake rate was stabilized by this medium. The complete medium stabilized the l-leucine uptake rate as a result of its ionic composition and not because of its osmolarity. Most of the increased uptake rate observed after preincubation in a 1% sucrose solution could be inhibited by 2,4-dinitrophenol or carbonyl cyanide m-chlorophenyl hydrazone, or high concentrations of l-phenyl-alanine or l-leucine. Therefore much of the increase could be accounted for by an increase in active transport of l-leucine.
当将悬浮培养的烟草品种威斯康星38细胞在1%蔗糖溶液中预孵育数小时后，L-亮氨酸转运进入这些细胞的速率增加了两倍多。如果在预孵育溶液中加入某些Tris缓冲液，这种摄取速率的增加就会消除，而其他缓冲液则几乎没有影响。只有在预孵育期开始时缓冲液和钙同时存在，钙才能逆转抑制性缓冲液的作用。抑制性缓冲液的胺基是造成抑制的原因。在完全培养基（EM Linsmaier，F Skoog，1965年，《植物生理学》18: 100 - 127）中预孵育10小时，L-亮氨酸摄取速率的变化最小，这表明该培养基使摄取速率稳定。完全培养基因其离子组成而非渗透压使L-亮氨酸摄取速率稳定。在1%蔗糖溶液中预孵育后观察到的大部分摄取速率增加可被2,4-二硝基苯酚或羰基氰化物间氯苯腙，或高浓度的L-苯丙氨酸或L-亮氨酸抑制。因此，大部分增加可归因于L-亮氨酸主动转运的增加。
