Mitochondrial associations with specific microtubular components of the cortex of Tetrahymena thermophila. II. Response of the mitochondrial pattern to changes in the microtubule pattern.

Mitochondria in Tetrahymena thermophila are known to associate with the cell cortex in asymmetrical patterns corresponding to the asymmetrical organization of the microtubular components of the cortex. Specific mitochondrion-microtubule associations are seen at the light-microscope and ultrastructural levels. The hypothesis that the mitochondrial pattern is determined by the microtubular pattern was tested. Using the phenotypes of various mutations to generate changes in the organization of the cortex, the response of the mitochondrial pattern to the cortical change was assayed. The results consistently show that changes in the local organization of the cortical microtubule systems are followed by a corresponding change in the cortical mitochondrial pattern. However, the mitochondrial pattern is unaffected by a mutation which changes the 'long-distance' patterning of certain organelles, but which does not influence the local microtubular organization. Thus, the data support the hypothesis that there is a causal relationship between the arrangement of the cortical microtubules and the corresponding mitochondrial pattern.