PHOTOREVERSAL OF NUCLEAR AND CYTOPLASMIC EFFECTS OF SHORT ULTRAVIOLET RADIATION ON PARAMECIUM CAUDATUM

Open Access
Publisher Website
Google Scholar
Abstract
Lethal doses of UV wavelengths 226, 233, and 239 m[mu] (obtained from an atmospheric pressure Hg arc with a modified natural quartz monochromator) induce death in P. caudatum with protoplasmic changes markedly different from those induced by longer wavelengths. Sublethal doses of the same wavelengths cause rapid immobilization of paramecia due to cessation of beat and subsequent loss of cilia. Recovery from minimal immobilizing doses occurs in 85% of paramecia immobilized with 226 m[mu]; susequent division delay in recovered animals is slight. At longer wavelengths the degree of recovery from minimal immobilizing doses diminishes and division delay increases. Immobilization induced in P. caudatum by any of the wavelengths tested (226, 233, 239, 248, and 267 m[mu]) is non-photoreversible by visible light applied concurrently with the UV; division delay however is photoreversible under these conditions. An action spectrum for immobilization in P. caudatum was determined for the wavelengths 226, 233, 239, 248, and 267 m[mu], and found to resemble the absorption of protein and lipid in this wavelength region.