Schwarz M, Lerner H R, Reinhold L
Department of Botany, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel.
Plant Physiol. 1991 May;96(1):69-76. doi: 10.1104/pp.96.1.69.
The in vivo functioning of mitochondria isolated from two tobacco cell lines in suspension culture (Nicotiana tabacum/gossii), wild type, and NaCl-adapted (A190), has been compared in the face of rising external salinity. The O(2) uptake of both state 3 and state 4 mitochondria was progressively inhibited with increasing external NaCl concentration in the case of both lines. Phosphorylation, however, was maintained at a higher level in the case of A190 mitochondria, as indicated both by stability of ADP:O ratio and rate of incorporation of (32)Pi. The superior phosphorylation performance of A190 mitochondria also emerged when phosphorylation was calculated per reducing equivalent, but not per unit DeltamuH(+) (electrochemical potential gradient for protons). However, the overall DeltamuH(+) was maintained at a higher level in A190 mitochondria due to the fact that the depolarization accompanying increase in external NaCl concentration was compensated for in A190 mitochondria by an increase in the transmembrane pH gradient, but not in wild type mitochondria. Increased proton permeability of the inner membrane is among the probable causes suggested for the loss of phosphorylation ability in wild type mitochondria; in contrast, A190 mitochondria maintain better membrane integrity under saline stress.
在外部盐度不断升高的情况下，对从悬浮培养的两种烟草细胞系（烟草/戈西烟草）、野生型和适应氯化钠的细胞系（A190）中分离出的线粒体的体内功能进行了比较。对于这两种细胞系，随着外部氯化钠浓度的增加，状态3和状态4线粒体的氧气摄取均逐渐受到抑制。然而，就ADP:O比率的稳定性和（32）Pi的掺入率而言，A190线粒体的磷酸化维持在较高水平。当按每个还原当量而非每单位ΔμH⁺（质子电化学势梯度）计算磷酸化时，A190线粒体的优越磷酸化性能也显现出来。然而，A190线粒体中总的ΔμH⁺维持在较高水平，这是因为外部氯化钠浓度增加时伴随的去极化在A190线粒体中通过跨膜pH梯度的增加得到补偿，而野生型线粒体中则没有。内膜质子通透性增加是野生型线粒体磷酸化能力丧失的可能原因之一；相反，A190线粒体在盐胁迫下能保持更好的膜完整性。
