Evidence that the synchronized production of new basal bodies is not associated with dna synthesis in Stentor coeruleus

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Abstract
Stentors were induced to produce synchronously thousands of new ciliated oral membranellar band basal bodies in less than 3 h. DNA synthesis does not accompany this process, as determined by [3H]thymidine incorporation into isolated bands and by sensitivity to DNA synthesis inhibitors (mitomycin C, ethidium bromide, cytosine arabinoside and hydroxyurea). Yet DNA could be detected in the cortex and the band at basal body sites by autoradiography. Since [3H]thymidine incorporation into membranellar band was eliminated in concentrations of ethidium bromide that had no effect on basal body formation, the previous reports of ciliate kinetosomal (basal body) DNA are interpreted as due to mitochondrial contamination. Specific cortical patterns of DNA that could have been easily misinterpreted as basal body-related were especially apparent in autoradiographs using [3H]actinomycin D as a ‘stain’. In no experiment involving induced basal body regeneration could evidence be found for a correlation between new basal body production and DNA synthesis; RNA and protein synthesis correlated with basal body and cilia regeneration were, however, easily detected by the same techniques. We concluded that there is no evidence that basal body DNA synthesis is required for new basal body production.