School of Life Sciences, Oxford Brookes University, Headington, Oxford OX3 0BP, UK.
New Phytol. 2011 Oct;192(2):328-37. doi: 10.1111/j.1469-8137.2011.03821.x. Epub 2011 Jul 15.
Temperature has a direct effect at the cellular level on an organism. For instance, in the case of biomembranes, cooling causes lipids to lose entropy and pack closely together. Reducing temperature should, in the absence of other factors, increase the viscosity of a lipid membrane. We have investigated the effect of temperature variation on plasma membrane (PM) viscosity. We used dispersion tracking of photoactivated green fluorescent protein (GFP) and fluorescence recovery after photobleaching in wild-type and desaturase mutant Arabidopsis thaliana plants along with membrane lipid saturation analysis to monitor the effect of temperature and membrane lipid composition on PM viscosity. Plasma membrane viscosity in A. thaliana is negatively correlated with ambient temperature only under constant-temperature conditions. In the more natural environment of temperature cycles, plants actively manage PM viscosity to counteract the direct effects of temperature. Plasma membrane viscosity is regulated by altering the proportion of desaturated fatty acids. In cold conditions, cell membranes accumulate desaturated fatty acids, which decreases membrane viscosity and vice versa. Moreover, we show that control of fatty acid desaturase 2 (FAD2)-dependent lipid desaturation is essential for this homeostasis of membrane viscosity. Finally, a lack of FAD2 function results in aberrant temperature responses.
温度在细胞水平上对生物体有直接影响。例如，在生物膜的情况下，冷却会导致脂质失去熵并紧密堆积。在没有其他因素的情况下，降低温度应该会增加脂质膜的粘度。我们研究了温度变化对质膜（PM）粘度的影响。我们使用光活化绿色荧光蛋白（GFP）的分散跟踪和荧光漂白后恢复以及膜脂质饱和度分析来监测温度和膜脂质组成对 PM 粘度的影响。在恒定温度条件下，只有在 PM 粘度与环境温度呈负相关的情况下，拟南芥中的 PM 粘度才与环境温度呈负相关。在温度循环的更自然环境中，植物主动管理 PM 粘度以抵消温度的直接影响。通过改变不饱和脂肪酸的比例来调节质膜粘度。在寒冷条件下，细胞膜积累不饱和脂肪酸，从而降低膜粘度，反之亦然。此外，我们表明，控制脂肪酸去饱和酶 2（FAD2）依赖性脂质去饱和对于这种膜粘度的动态平衡至关重要。最后，缺乏 FAD2 功能会导致异常的温度响应。
