Characterization of a mutant with abnormal flagellar morphogenesis in Chlamydomonas reinhardtii.

我的特点是一个新的鞭毛突变体在莱茵衣藻。当突变体在光照（~ 4，800 lux）下培养时，大多数细胞没有鞭毛。然而，当将培养物置于黑暗中时，超过70%的细胞在转移后16小时内鞭毛化。鞭毛形态从“杆状”（与野生型鞭毛相同）到“盘状”。电子显微镜观察发现，盘状鞭毛内有轴丝，轴丝在膨大的膜内弯曲成环状。另一方面，将黑暗中的鞭毛细胞（70%*）置于光照下，所有细胞在转移后8小时内没有鞭毛。在10^-10 ^M DCMU存在下，鞭毛形成的光抑制恢复<-6><-5>。在400- 420 nm和660- 680 nm波长范围内，光抑制的效果最好。突变体的鞭毛再生也被光抑制，抑制模式与放线菌酮（20 μ g/ml）相似。突变体的轴丝保持环状后，被脱膜与0.5%的Nonidet P-40。突变体鞭毛的SDS-PAGE显示，分子量为250 kDa和7.4 kDa的2条条带缺失，分子量为240 kDa、150 kDa和130 kDa的3条条带密度增加。从这些结果，我认为光合作用的产物抑制了突变体的鞭毛形成，并且形成的鞭毛在轴丝本身之间的结合中存在缺陷。四联体分析表明，突变体的表型是由单基因突变引起的。

I have characterized a novel flagellar mutant in Chlamydomonas reinhardtii. When the mutant was cultured under the light (-4,800 lux), most cells had no flagella. However, when the cultures were put in the dark, greater than 70% of the cells flagellated within 16 h after the transfer. The flagellar morphology varied from "rod-shape" (same as the wild-type flagella) to "disk-shape" . Electron microscopy showed that the disk-shaped flagella had the axonemes which were curved into a loop within the swollen membrane. On the other hand, flagellated cells (70%*) in the dark were put under the light, all cells had no flagella within 8 h after the transfer. Light inhibition of flagellation was restored in the presence of 10^<-6>-10^<-5> M DCMU. The spectral dependency of the photo-inhibition of flagellation showed maximal effectiveness at 400-420nmand 660-680nm. Flagellar regeneration of the mutant was also inhibited by light, and the inhibition pattern was similar to that of cycloheximide (20 mug/ml). Axonemes of the mutant maintained looped shape after being demembranated with 0.5% Nonidet P-40. SDS PAGE of the mutant flagella showed that two bands with molecular weights of 250 kDa and 7.4 kDa were missing and three other bands with molecular weights 240 kDa, 150 kDa and 130 kDa increased their densities. From these results, I suppose that product(s) of photosynthesis inhibit flagellation of the mutant, and formed flagella have defect(s) in the binding between the axoneme itself. Tetrad analysis showed that phenotypes of the mutant resulted from a single gene mutation.