Gametic differentiation in Chlamydomonas reinhardtii. III. Cell wall lysis and microfilament-associated mating structure activation in wild- type and mutant strains
Gametic differentiation in Chlamydomonas reinhardtii. III. Cell wall lysis and microfilament-associated mating structure activation in wild- type and mutant strains
复制标题
莱茵衣藻的配子分化。
作者：
U. Goodenough;R. Weiss
交配型加（MT+）和负（MT-）配子的莱茵衣藻的细胞融合进行了结构分析和实验操作。细胞壁裂解，融合的必要前奏，显示需要鞭毛凝集之间的主管配子;戊二醛固定的配子（“尸体”）的一个交配型将引起双方凝集和细胞壁裂解在相反的交配型，而nonagglutinating无能（IMP）突变株没有效果。融合过程是由一个狭窄的受精小管介导的，受精小管从mt+配子延伸并与mt-配子建立接触。微管的形成需要与ml+细胞膜相关的专门的交配结构的“激活”;激活导致微丝从交配结构进入生长的受精小管。交配结构的激活取决于配子鞭毛凝集;由凝集素伴刀豆球蛋白A介导的同种凝集没有影响。携带IMP-1 MT+突变的配子能够凝集但不与MT-细胞融合; IMP-1配子显示具有结构缺陷的交配结构，其不响应配子凝集而产生微丝。
Cell fusion between mating type plus (mt+) and minus (mt-) gametes of Chlamydomonas reinhardtii is analyzed structurally and subjected to experimental manipulation. Cell wall lysis, a necessary prelude to fusion, is shown to require flagellar agglutination between competent gametes; glutaraldehyde-fixed gametes ("corpses") of one mating type will elicit both agglutination and cell wall lysis in the opposite mating type, whereas nonagglutinating impotent (imp) mutant strains are without effect. The fusion process is mediated by a narrow fertilization tubule which extends from the mt+ gamete and establishes contact with the mt- gamete. Formation of the tubule requires the "activation" of a specialized mating structure associated with the ml+ cell membrane; activation causes microfilaments to polymerize from the mating structure into the growing fertilization tubule. Mating structure activation is shown to depend on gametic flagellar agglutination; isoagglutination mediated by the lectin concanavalin A has no effect. Gametes carrying the imp-l mt+ mutation are able to agglutinate but not fuse with mt- cells; the imp-l gametes are shown to have structurally defective mating structures that do not generate microfilaments in response to gametic agglutination.