PHOTOREACTIVATION IN COLPIDIUM COLPODA

Quantum Relations in Photoreactivation of Colpidium

1. The amount of visible or long ultraviolet light (UV) required to photoreactivate Colpidium colpoda injured with known dosages of short UV (2654 A) was determined. 2. The effect of the short UV was tested by the delay in division of exposed animals compared to controls. Photoreactivation was tested by the effect of postillumination on the delay of division of treated colpidia compared to cont...

A Theoretical Consideration of the Action of X-rays on the Protozoan Colpidium Colpoda

1. The theory which Crowther has advanced to account for the variation of the lethal dose of roentgen rays among the individuals of a group of Colpidium colpoda is reviewed. 2. It is shown that the use of his small-body theory to explain the small value of lambda(e) leads to certain further assumptions about the nature of the destructive effect. 3. An alternative hypothesis is discussed.

The Kinetics of Excystment in Colpoda Duodenaria

1. Extensive experimental data have been collected on the time required for the excystment process of the small ciliate Colpoda duodenaria throughout a range of temperatures of 8 degrees through 32 degrees C. and a range of concentrations of yeast extract excystment media of 0.08 through 22.4 gm./liter. 2. The excystment process has been separated into two periods, the first inversely proportio...

Clxii. Allelocatalytic Effect in Cultures of Colpidium

Photoreactivation in humans.

Photoreactivation is a DNA repair pathway that requires the presence of a photoreactivating enzyme, DNA photolyase. DNA photolyase recognizes and binds specifically to ultraviolet radiation (UVR)-induced cyclobutane pyrimidine dimers in DNA. Exposure of the photolyase-dimer complex to wavelengths in the range of 300-500 nm results, upon absorption of a photon, in the return of the dimerized pyr...