Departamento de Bioquímica, Facultad de Ciencias, Universidad de Bilbao, Bilbao, Spain.
Plant Physiol. 1978 Dec;62(6):987-90. doi: 10.1104/pp.62.6.987.
Nitrate uptake has been studied in nitrogen-deficient cells of the marine diatom Skeletonema costatum. When these cells are incubated in the presence of nitrate, this ion is quickly taken up from the medium, and nitrite is excreted by the cells. Nitrite is excreted following classical saturation kinetics, its rate being independent of nitrate concentration in the incubation medium for nitrate concentration values higher than 3 micromolar. Nitrate uptake shows mixed-transfer kinetics, which can be attributed to the simultaneous contributions of mediated and diffusion transfer. Cycloheximide and p-hydroxymercuribenzoate inhibit the carrier-mediated contribution to nitrate uptake, without affecting the diffusion component. When cells are preincubated with nitrate, the net nitrogen uptake is increased.
已对海洋硅藻小环藻的氮饥饿细胞中的硝酸盐摄取进行了研究。当这些细胞在硝酸盐存在下孵育时，该离子会从培养基中迅速被吸收，而亚硝酸盐会被细胞排出。亚硝酸盐的排泄遵循经典的饱和动力学，其排泄速率与孵育介质中的硝酸盐浓度无关，只要硝酸盐浓度高于 3 微摩尔。硝酸盐摄取显示混合转运动力学，这可归因于介导转运和扩散转运的同时贡献。环己亚胺和对羟汞苯甲酸抑制硝酸盐摄取的载体介导贡献，而不影响扩散成分。当细胞用硝酸盐预孵育时，净氮吸收增加。
