与斜生栅藻中钠的主动排出机制相关的钠、铷和铯的摄取与损失
Uptake and loss of Na, Rb, and Cs in relation to an active mechanism for extrusion of Na in Scenedesmus.
作者信息
Kylin A
出版信息
Plant Physiol. 1966 Apr;41(4):579-84. doi: 10.1104/pp.41.4.579.
The mechanism for extrusion of Na(+) from Scenedesmus cells is characterized physiologically. It is stimulated by phosphate but oxygen is not necessary. Rb(+) and Cs(+) may also be extruded, but in the presence of Na(+) they cannot compete for the sites on the inside of the transport system. When Na(+) is extruded, Rb(+) and, by inference, K(+) seems to be transported as counter ion from the outside, and sodium ions compete only weakly for this external site. The parallelism between these findings and the Na(+)-K(+)-activated adenosine triphosphatases known from animal tissues is pointed out. With low additions of phosphate, the extrusion mechanism can keep the cells practically free from Na(+). Increasing the concentrations of external phosphate stimulates uptake more than extrusion, and a net uptake occurs. As for Rb(+) and Cs(+), they are taken up in the absence of external phosphate, but additions of P will greatly enhance the amounts absorbed. Two different ways of uptake are indicated.
对栅藻细胞中Na⁺ 排出机制进行了生理学特征研究。它受磷酸盐刺激，但氧气并非必需。Rb⁺ 和Cs⁺ 也可能被排出，但在有Na⁺ 存在时，它们无法竞争转运系统内部的位点。当Na⁺ 被排出时，Rb⁺ 以及据此推测的K⁺ 似乎作为反离子从外部被转运进来，而钠离子对这个外部位点的竞争较弱。指出了这些发现与动物组织中已知的Na⁺ -K⁺ -激活的三磷酸腺苷酶之间的相似性。添加少量磷酸盐时，排出机制可使细胞几乎不含Na⁺ 。增加外部磷酸盐浓度对摄取的刺激大于对排出的刺激，会出现净摄取。至于Rb⁺ 和Cs⁺ ，它们在没有外部磷酸盐时被摄取，但添加磷会大大增加吸收量。表明存在两种不同的摄取方式。
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