PHOTOREACTIVATION IN COLPIDIUM COLPODA

Abstract

Irradiation of the ciliate C. colpoda with known dosages of monochromatic u.-v. radiations of short wavelengths retards division. A lag is observed before divisions begin, and, following larger dosages, rate of division may decline. Short visible (blue, violet) and long u.-v. wavelengths effectively reverse the injurious action of short u.-v. Following such exposures, the overall effect resembles that seen with smaller dosages of short u.-v. Photoreversal will occur even 4 hrs. after u.-v. treatment. Blue, violet and long u.-v. are effective in photoreversal but green and yellow light are not. Blue light was used routinely for photoreversal studies. Photoreversal of effects of various wavelengths of short u.-v. was obtained, the degree being somewhat less at the long and short end of the spectrum for a comparable amt. of blue light. This finding suggests that u.-v. may selectively affect some cellular constituents and that photoreversal may involve a change in only some of the altered constituents.