Flagellum mutants of Chlamydomonas reinhardii.

Mutants blocked in different stages of flagellar development were isolated and examined by light and electron microscopy. Flagellum-less mutants had normal basal bodies but lacked the flagellar shaft and showed abnormalities in the transitional region. Stumpy mutants had very short flagellar shafts in which electrondense material, sometimes arranged in sheet-like arrays, accumulated in the space between the outer tubules and the distended flagellar membrane. Short-flagellum mutants also showed abnormalities in the flagellar shaft ; abnormally spaced radial spokes were seen in negatively stained frayed flagella of one of these mutants. The flagellum lengths and flagellar regeneration characteristics of two long-flagellum mutants with defective length control were determined ; length was highly variable with some abnormally long flagella, and regeneration was slow and asynchronous.