PRINCIPAL INVESTIGATOR(S ): Irwin I. Oster 



EXPERIMENT TITLE/NUMBER : Genetic Implications of Space Flight, P-1160 



PROGRAM/MISSION : Biosatellite II 



CLASSIFICATION : Animal - Fruit fly ( Drosophila melanoeaster ) 



DISCIPLINE(S) : Radiobiology, Genetics, Behavioral science 



OBJECTIVES : To determine to what extent weightlessness may affect the 

 responses of somatic cells to ionizing gamma radiation, using immature stages 

 (instar pupal stages) of Drosophila melanogaster . 



PROTOCOL : Eggs were collected using the Sonnenblick method. Sixty 1st instar 

 larvae placed in each module (the package had 8 modules). Ten 1st instar 

 larvae w/ring chromosomes were selected for cytologic preparations. 

 Additional larvae were added to bring count to 290. After the flight, the 

 larvae were examined for visual chromosome changes and some were allowed to 

 develop and breed. The larvae were exposed to a dose of 1200 to 1500r of 



Sr. One unit was shielded. A similar configuration was used on an 

 Earth-based control. Three additional controls were maintained. Optimum 

 conditions of humidity, temperature, and food were maintained. 



EQUIPMENT : Drosophila flight package consisting of eight larvae modules 

 equippped with dosimeters and thermistors, an Sr source, and LiF radiation 

 detectors . 



RESULTS : Higher mortality of orbited larvae than Earth radiation-exposed 

 larvae was noted with no detectable effect on developmental time. Chromosomes 

 flown and irradiated showed a statistically significant increase in chromosome 

 change over Earth controls. The nonirradiated flown material did not appear 

 different from the Earth control. Flight and flight irradiated chromosomes 

 showed evidence of chromosome nondisjunctions. 



CONCLUSIONS : Radiation interacts with weightlessness to induce more premature 

 aging and chromosome damage in actively growing and metabolizing specimens 

 than in those irradiated at Earth level. Possibly some factor, more than 

 likely weightlessness, is capable of causing improper chromosome separation 

 and the formation of chromosome translations. 



PUBLICATIONS : 41 4, 415, 416, 417 



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