PRINCIPAL INVESTIGATOR(S ): Irving Davis 



EXPERIMENT TITLE/NUMBER : Radiobiology Experiments in Discoverer Satellites. 



II. Clostridia Spore Labilization: A Biological 

 System to Quantitate Radiation 



PROGRAM/MISSION : Discoverer XVII, XVIII 



CLASSIFICATION : Microorganism ( Clostridium sporogenes ) 



DISCIPLINE(S) : Cell biology, Radiobiology 



OBJECTIVES : To provide a means of quantitating and correlating space 

 radiations with microbiological activity. 



PROTOCOL : Aliquots of cell suspensions of 4 x 10" 5 cell/ml were delivered to 

 2.0 ml ampules and heat sealed. All cultures were stored at 5 C until used. 

 Caramelized glucose, pH 7.5, was used as the medium to test for labilization 

 for the spores. Postf light, the vials were opened, and analyzed for growth. 



EQUIPMENT : Caramelized glucose, glass ampules, refrigeration units for the 

 ground, thermistors, track plates, chemical dosimeters, needle sets. 



RESULTS : The probable dose received on Discoverer XVII was 40-50 rad with 71% 

 inhibition noted postflight. On Discoverer XVIII, the probable dose was less 

 than 0.1 rad with 12% inhibition of postflight growth. 



CONCLUSIONS : Laboratory studies have shown that when similar spores are 

 exposed to radiation and subsequently treated with caramelized glucose, the 

 labilization effect is quantitatively inhibited. The same effect was observed 

 in the flight samples. This experiment shows the usefulness of Clostridia for 

 study of space radiation hazards. 



PUBLICATIONS : 140, 141 



157 



