735 



John D. Spikes and Dennis C. Hall 



-h 

 Photodynamic action systems contained 1.0 x 10 M dye. Illumi- 

 nation with shaking in contact vrith air was carried out \n.th. the 

 same apparatus used for manometric measurements. After treatment; 

 the algae were washed several times in distilled water and then 

 resuspended in distilled water. In the routine screening of dyes 

 for photodynamic activity, algal suspensions containing dye were 

 incuhated in the dark at 15 °C. for one hour. Samples were then 

 illuminated for one hour. "Dark" and "light" samples were washed 

 several times and then assayed for photosynthetic and Hill reac- 

 tion activity. Appropriate light and dark controls were also 

 carried out. 



A General Electric 15-vatt germicidal lamp was used in the 

 \iltraviolet radiation studies. Ultraviolet radiation intensities 

 were measured \-n.th a Luckiesh-Taylor "germicidal attachment" in 

 conjimction with a General Electric Model 80WUOVl6 light meter. 

 Gamma radiation studies were carried out with a 525 curie cobalt- 

 60 source. The irradiation chamber was maintained at a constant 

 temperature. The energy flux in the chamber was measured periodi- 

 cally v/ith the Fricke ferrous sulfate method; the dose rate was 

 73-1 ± 0'3 X 103 rads per hour. 



RESULTS 



Photodynamic effects on Hill reaction and photosynthesls - 



A large number of dyes were examined for "dark" and photo- 

 dynamic effects on Chlorella Hill reaction and photosynthesis. 

 Most of the dyes showed no photodynamic sensitization. The 

 inactive dyes included Acridine oraage, Acriflavine, Alcian blue, 

 Auramine 0, Aureomycin, Azure A, Azure C, Biofluor, Camoquin di- 

 hydrychloride, Dinitrophenol, Eosin B, Eosin Y, Fuchsins, Hema- 

 toporphyrin, Janus green B, Malachite green, 8-Methoxypsoralen, 

 Neutral red, Nile blue A, Orange G, para-Rosanilin hydrochloride, 

 Pentaquine phosphate, Phenosafranin, Pyronin B, Pyronin Y, 

 Rhodaraine B, Rhodamine G, Riboflavin, Riboflavin-5 ' -phosphate, 

 Safranin 0, Sodium magnesium chlorophyllin, Toluidine blue 0, 

 Toluylene blue, and Trypan blue. Seven of the dyes were photo- 

 dynamically active, including Erythrosin B, Ethyl eosin. 

 Methylene blue. New methylene blue N, Phenazine methosulfate. 

 Rose bengal, and Thionin. Some dyes, including Malachite green, 

 Methylene blue, Nile blue A and Rose bengal produced inactivation 

 in the dark at higher concentrations. Photosynthesis was usually 

 more sensitive to dark inactivation than the Hill reaction. 



The dye. Rose bengal, which combined good photosensitizing 



