Targeted gene knockout of inner arm 1 in Tetrahymena thermophila

Cilia and flagella contain at least eight different types of dynein arms. I t is not entirely clear how the different types of arms are organized along the axoneme. In addition, the role each different type of dynein plays in ciliary or flagellar motility is not known. To initiate studies of dynein o rganization and function in cilia, we have introduced a mutation into one d ynein heavy chain gene (DYH6) in Tetrahymena thermophila by targeted gene k nockout. We have generated mutant cells that lack wild-type copies of the D YH6 gene. We have shown that the DYH6 gene encodes one heavy chain (HC2) of Tetrahymena 18S dynein and that 18S dynein occupies the I1 position in the ciliary axoneme. We have also shown that Tetrahymena I1 is required for no rmal motility, normal feeding and normal doubling rate.