Yu Yu Ping, Jackson Sandra L, Garrill Ashley
School of Biological Sciences, University of Canterbury, Private Bag 4800, Christchurch 8020, New Zealand.
Plant Cell Physiol. 2004 Mar;45(3):275-80. doi: 10.1093/pcp/pch032.
We show that two distinct distributions of F-actin are present in the hyphal apex of the oomycete Achlya bisexualis, that have been chemically fixed with a combination of methylglyoxal and formaldehyde and stained with Alexa phalloidin. In approximately one half of the hyphae examined, an F-actin depleted zone within the apical F-actin cap was observed. The remaining hyphae had a continuous apical cap. In live, growing hyphae two types of cytoplasmic organization were observed at the tips, one in which a clear zone was present which may correlate with the F-actin depleted zone, and one where no such clear zone existed which may represent the continuous cap. We suggest that the F-actin depleted zone may be a structural component of the actin network in a subpopulation of oomycete hyphae and may be comparable to similar F-actin depleted zones at the apices of other tip growing cells such as pollen tubes and root hairs. This observation has implications with regard to models of hyphal extension. Hyphae fixed with formaldehyde alone showed continuous apical F-actin caps. Our ability to resolve the F-actin depleted zone likely reflects the cross-linking capabilities of methylglyoxal. The methylglyoxal-formaldehyde combination fixative gave more stained hyphae, brighter staining and more complete staining of F-actin compared to formaldehyde alone.
我们发现，在用甲基乙二醛和甲醛组合进行化学固定并用Alexa鬼笔环肽染色的双性绵霉卵菌的菌丝顶端，存在两种不同的F-肌动蛋白分布。在所检查的大约一半菌丝中，在顶端F-肌动蛋白帽内观察到一个F-肌动蛋白耗尽区。其余的菌丝有一个连续的顶端帽。在活体生长的菌丝顶端观察到两种类型的细胞质组织，一种有一个清晰区域，可能与F-肌动蛋白耗尽区相关，另一种没有这样的清晰区域，可能代表连续的帽。我们认为，F-肌动蛋白耗尽区可能是卵菌菌丝亚群中肌动蛋白网络的一个结构成分，可能与花粉管和根毛等其他顶端生长细胞顶端的类似F-肌动蛋白耗尽区相当。这一观察结果对菌丝延伸模型有影响。仅用甲醛固定的菌丝显示出连续的顶端F-肌动蛋白帽。我们分辨F-肌动蛋白耗尽区的能力可能反映了甲基乙二醛的交联能力。与单独使用甲醛相比，甲基乙二醛-甲醛组合固定剂使更多的菌丝被染色、染色更亮且F-肌动蛋白染色更完整。
