A NEW THEORY ON THE MECHANICS OF CILIARY AND FLAGELLAR MOTILITY. I. SUPPORTING OBSERVATIONS

¹ Department of Zoology, University of North Carolina, Chapel Hill, North Carolina 27514

1. Controlled partial maceration and negative staining of ciliary and flagellar axonemes (with phosphotungstate) have revealed that under these conditions: (a) Doublet microtubules have an inherent tendency for bending or coiling; (b) Central singlet microtubules of 9 + 2 axonemes, or the cores of the "9 + 1" flagellar axonemes, stiffen or straighten; (c) Active bending of the doublets occurs in the direction away from their dynein arms, so that the A-subtubule is on the convex side.

2. In partially macerated 9 + 2 axonemal isolates, examination of electron micrographs indicates that the bending of the doublets of one lateral half is in a direction opposite to that of the doublets of the other lateral half. This is a consequence of (1, c) above.

3. Evidence is presented for (2) above, in micrographs showing the direction of bending of specifically identified doublet microtubules of isolated ciliary axonemes.