Alessa L, Kropf D L
University of Utah, Department of Biology, 1400 East, Salt Lake City, UT 84112-0840, USA.
Development. 1999 Jan;126(1):201-9. doi: 10.1242/dev.126.1.201.
Spatial and temporal changes in F-actin during polarity establishment in Pelvetia compressa zygotes were investigated using vital staining with rhodamine phalloidin (RP). F-actin was localized to a patch in the cortex of young zygotes. When unilateral light was applied to induce a growth axis (photopolarization) in a population of zygotes, the cortical F-actin patches localized at the shaded pole (rhizoid pole of growth axis). Treatments that prevented photopolarization prevented localization of F-actin patches to the shaded pole. When the direction of the light treatment was reversed, the previous growth axis was abandoned and a new axis was established in the opposite direction. The F-actin patch repositioned to the new rhizoid pole within minutes of light reversal, indicating that F-actin was an immediate marker of the nascent growth axis. Repositioning probably occurred by disassembly of the initial patch and reassembly of a new one. The patch grew in size as zygotes developed, eventually becoming a ring just prior to rhizoid outgrowth. The rhizoid emerged at the site of the F-actin ring and, following germination, the ring was located in the subapical zone of the elongating tip.
利用罗丹明鬼笔环肽（RP）进行活体染色，研究了皱紫菜合子极性建立过程中F-肌动蛋白的时空变化。F-肌动蛋白定位于幼合子皮层的一个斑块中。当对一群合子施加单侧光以诱导生长轴（光极化）时，皮层F-肌动蛋白斑块定位于遮光极（生长轴的假根极）。阻止光极化的处理可防止F-肌动蛋白斑块定位于遮光极。当光处理方向反转时，先前的生长轴被舍弃，相反方向建立了新的轴。在光反转后的几分钟内，F-肌动蛋白斑块重新定位到新的假根极，表明F-肌动蛋白是新生生长轴的即时标记。重新定位可能是通过初始斑块的解体和新斑块的重新组装发生的。随着合子的发育，斑块尺寸增大，最终在假根长出之前变成一个环。假根在F-肌动蛋白环的位置出现，萌发后，环位于伸长尖端的亚顶端区域。
