Goodenough U W, Detmers P A, Hwang C
J Cell Biol. 1982 Feb;92(2):378-86. doi: 10.1083/jcb.92.2.378.
Gametes of Chlamydomonas reinhardi become activated for cell fusion as the consequence of sexual adhesion between membranes of mating-type plus and minus flagella. By using tannic acid plus en bloc uranyl acetate staining, and by fixing at very early stages in the mating reaction, we have demonstrated the following. (a) Activation of the minus mating structure entails major modifications in the structure of the organelle, causing it to double in size and to concentrate surface coat material, termed fringe, into a central zone. (b) The unactivated plus mating structure is endowed with fringe that moves with the tip of the actin-filled fertilization tubule during activation. Pre-fusion images suggest the occurrence of a specific recognition event between the plus and minus fringes. (c) Gametes carrying the imp-1 mutation fail to form a fringe and are unable to fuse. The imp-1 mutation is linked to the mating-type plus (mt+) locus, suggesting that the gene specifying the synthesis or insertion of fringe is encoded in this sector of the genome. (d) Gametes carrying the imp-11 mutation fail to form both a normal fringe and a normal submembranous density beneath the fringe, and are also unable to fuse. The imp-11 mutation converted a wild-type minus cell into a pseudo-plus strain; a model to explain this conversion proposes that the normal imp-11 gene product represses plus-specific genes concerned with Chlamydomonas gametogenesis.
莱茵衣藻的配子由于正交配型和负交配型鞭毛膜之间的性黏附而被激活以进行细胞融合。通过使用单宁酸加醋酸铀整体染色，并在交配反应的非常早期阶段进行固定，我们证明了以下几点。(a) 负交配结构的激活需要对细胞器的结构进行重大修饰，使其尺寸翻倍，并将称为边缘的表面涂层物质集中到一个中心区域。(b) 未激活的正交配结构具有边缘，在激活过程中，边缘会随着充满肌动蛋白的受精小管的尖端移动。融合前的图像表明正、负边缘之间发生了特定的识别事件。(c) 携带imp-1突变的配子无法形成边缘，也无法融合。imp-1突变与正交配型（mt+）位点相关联，这表明指定边缘合成或插入的基因在基因组的该区域编码。(d) 携带imp-11突变的配子既无法形成正常的边缘，也无法在边缘下方形成正常的膜下密度，同样也无法融合。imp-11突变将野生型负细胞转化为假正菌株；一个解释这种转化的模型提出，正常的imp-11基因产物会抑制与衣藻配子发生有关的正特异性基因。
