The proximal portion of Chlamydomonas flagella contains a distinct set of inner dynein arms.

A specific type of inner dynein arm is located primarily or exclusively in the proximal portion of Chlamydomonas flagella. This dynein is absent from flagella less than 6 microns long, is assembled during the second half of flagellar regeneration time and is resistant to extraction under conditions causing complete solubilization of two inner arm heavy chains and partial solubilization of three other heavy chains. This and other evidence described in this report suggest that the inner arm row is composed of five distinct types of dynein arms.

Three distinct inner dynein arms in Chlamydomonas flagella: molecular composition and location in the axoneme.

The molecular composition and organization of the row of axonemal inner dynein arms were investigated by biochemical and electron microscopic analyses of Chlamydomonas wild-type and mutant axonemes. Three inner arm structures could be distinguished on the basis of their molecular composition and position in the axoneme as determined by analysis of pf30 and pf23 mutants. The three inner arm structures repeat every 96 nm and are referred to here as inner arms I1, I2, and I3.

Basal body/centriolar DNA: molecular genetic studies in Chlamydomonas.

In Chlamydomonas reinhardtii, mutations on an unusual linkage group, the uni linkage group (ULG), affect structure and function of basal bodies. The ULG shows Mendelian segregation, but its genetic map is circular. Molecular cloning of fragments of the ULG was accomplished by taking advantage of restriction fragment length polymorphisms generated by crosses to Chlamydomonas smithii.

Loci affecting flagellar assembly and function map to an unusual linkage group in Chlamydomonas reinhardtii.

The uni1 mutant of Chlamydomonas reinhardtii lacks one of the paired flagella seen in wild-type cells. The missing flagellum is cis to the eye spot and at this site the basal body is incomplete, lacking a transition zone. Together with nine other loci affecting flagellar assembly and two loci affecting flagellar function uni1 defines an approximately equal to 100-centimorgan linkage group with a circular map.

Mutant strains of Chlamydomonas reinhardtii that move backwards only.

Mutations at three independent loci in Chlamydomonas reinhardtii result in a striking alteration of cell motility. Mutant cells representing the three mbo loci move backwards only, propelled by a symmetrical "flagellar" type of bending pattern. The characteristic asymmetric "ciliary" type of flagellar bend pattern responsible for forward movement that predominates in wild-type cells is seldom seen in the mutants.