The action of deoxyribonuclease, ribonuclease, perchloric acid, and pronase on the fine structure of basal bodies of sectioned Paramecium was observed as part of a more extensive autoradiographic electron microscope analysis directed toward the problem of basal body DNA. DNase was found to have no detectable effect on basal body fine structure. Pronase first solubilized the linkers and C tubules of the triplets, then attacked the protein portion of the axosome, a localized portion of the ciliary axoneme adjacent to the distal end of the basal body, the rim fiber, and newly described lumen spiral complex. Prolonged pronase treatment disrupted the remaining microtubular elements, basal body plates, and cartwheel. RNase removed material from the axosome and the lumen complex, a conspicuous structure occupying the central portion of the basal body and consisting of a twisted or looped 90-A diam fiber or, more probably, pair of fibers, in association with large, dense granules. The apparent removal of both RNA and protein from this basal body structure by either of the two corresponding enzymes suggests an unusual organization of the two components. Observations from this and other laboratories suggest that the basal body RNA is single stranded. Its function is unknown but alternatives are discussed.

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