PRINCIPAL INVESTIGATOR (S ): Arnold H. Sparrow, Lloyd A. Schairer, and 



Kodumundi M. Marimuthu 



EXPERIMENT TITLE/NUMBER : Radiobiological Studies of Tradescantia Plants 



Orbited in Biosatellite II, P-1123 



PROGRAM/MISSION : Biosatellite II 



CLASSIFICATION : Plant - ( Tradescantia ) 



DISCIPLINE(S) : Radiobiology, Genetics, Behavioral science, Cell biology 



OBJECTIVES : To determine the effect of weightlessness and other spacecraft 

 environmental conditions on spontaneous and radiation-induced somatic mutation 

 rates and on selected cytologic changes. 



PROTOCOL : Data obtained from irradiated and nonirradiated flight plants were 

 compared with data from nonf light irradiated and nonirradiated control plants. 

 Thirty-two plants were flown in a package in the spacecraft behind the 

 radiation shield, and identical nonf light control packages (with and without 

 irradiation) were maintained at the launch site. All these plants were 

 observed after the flight for: (1) somatic mutation (blue to pink or 

 colorless cells); (2) cell size (giant and dwarf conditions); (3) loss of 

 reproductive integrity (cell death and stunting in stamen hair growth); (4) 

 pollen grain mortality (early and late stages); (5) megaspore development; (6) 

 normal cell divisions; and (7) chromosome aberrations. 



EQUIPMENT : Experimental packages constructed of polypropylene plastic, each 

 designed to hold 32 plants with roots sealed in a tube filled with nutrient 

 solution, thermistor, dosimeters (LiF) . 



RESULTS : Irradiated and nonirradiated flight plants were compared with 

 comparable controls. Bud blasting with flower opening was noted R+8. No 

 differences in cell size, chromosome aberration or somatic mutation were 

 found. Irradiated flight plants showed increased pollen abortion, pollen 

 micronuclei and stamen hair stunting. Disturbed spindle function of root tips 

 was observed. The Earth irradiated had higher mutation rate than flight. 

 Mutation rates were equal for nonirradiated material. Inflight dosimetry to 

 root zone was 125-285r, 2l8-225r in bud zone. 



CONCLUSIONS : Clearly differences exist between flight and nonflight material 

 and the significance and possible mechanisms for these effects are being 

 studied in continuing nonflight tests in an effort to better assess the 

 possible hazards to living systems of the stresses encountered during orbital 

 flight. 



PUBLICATIONS : 375, 376, 468, 494, 495, 496, 497 



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