Confocal imaging has shown that CELLULOSE SYNTHASE (CESA) particles move through the plasma membrane as they synthesize cellulose. However, the resolution limit of confocal microscopy circumscribes what can be discovered about these tiny biosynthetic machines. Here, we applied Structured Illumination Microscopy (SIM), which improves resolution two-fold over confocal or widefield imaging, to explore the dynamic behaviors of CESA particles in living plant cells. SIM imaging reveals that Arabidopsis thaliana CESA particles are more than twice as dense in the plasma membrane as previously estimated, helping explain the dense arrangement of cellulose observed in new wall layers. CESA particles tracked by SIM display minimal variation in velocity, suggesting coordinated control of CESA catalytic activity within single complexes and that CESA complexes might move steadily in tandem to generate larger cellulose fibrils or bundles. SIM data also reveal that CESA particles vary in their overlaps with microtubule tracks and can complete U-turns without changing speed. CESA track patterns can vary widely between neighboring cells of similar shape, implying that cellulose patterning is not the sole determinant of cellular growth anisotropy. Together, these findings highlight SIM as a powerful tool to advance CESA imaging beyond the resolution limit of conventional light microscopy.

中文翻译：

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超分辨率成像阐明了纤维素合酶的新动态行为


共焦成像显示，纤维素合成酶 (CESA) 颗粒在合成纤维素时穿过质膜。然而，共焦显微镜的分辨率限制限制了对这些微型生物合成机器的发现。在这里，我们应用结构照明显微镜 (SIM) 来探索 CESA 颗粒在活植物细胞中的动态行为，该显微镜的分辨率比共焦或宽场成像提高了两倍。 SIM 成像显示，拟南芥 CESA 颗粒在质膜中的密度是之前估计的两倍多，这有助于解释在新壁层中观察到的纤维素的密集排列。 SIM 跟踪的 CESA 颗粒显示出最小的速度变化，表明单个复合物内 CESA 催化活性的协调控制，并且 CESA 复合物可能稳定地串联移动以产生更大的纤维素原纤维或束。 SIM 数据还表明，CESA 粒子与微管轨道的重叠程度不同，并且可以在不改变速度的情况下完成掉头。 CESA 轨迹图案在形状相似的相邻细胞之间可能存在很大差异，这意味着纤维素图案并不是细胞生长各向异性的唯一决定因素。总之，这些发现凸显了 SIM 作为一种强大的工具，可以推动 CESA 成像超越传统光学显微镜的分辨率极限。