PRINCIPAL INVESTIGATOR(S ): Richard S. Young, John W. Tremor, Richard 



Willoughby, Robert L. Corbett, Kenneth A. Souza, 

 and Paul D. Sebesta 



EXPERIMENT TITLE/NUMBER : The Effect of Weightlessness on the Dividing Eggs of 



Rana pipiens , P-1047 



PROGRAM/MISSION : Biosatellite II 



CLASSIFICATION : Animal - Bullfrog eggs ( Rana pipiens ) 



DISCIPLINE(S) : Genetics, Cell biology 



OBJECTIVES : To determine if weightlessness affects the ability of the 

 fertilized frog egg to divide, differentiate and develop normally. 



PROTOCOL : On day F-3, 60 female frogs were injected with gonadotrophin to 

 induce ovulation. At F-12.5 hr., stripped eggs were fertilized and divided 

 into clusters of 5. They were then kept at 43 F to prevent division. The 

 eggs were placed in groups of 10 in the first eight modules to be fixed, and 

 in groups of 5 for the remainder. The experiment called for fixation at F-0, 

 F+1 hr, F+2, F+3, F+32, F+40, F+68 hrs. The last module pair was to return 

 with live embryos. Three hardware packages were prepared; one for flight, one 

 for backup, and one for control. 



EQUIPMENT : The package contained 16 acrylic modules divided into 2 chambers, 

 a 10 ml egg chamber and a 4 ml-fixative chamber, a coolant line around the 

 package to maintain it at 42.5 F on the pad, thermistors to each of 4 modules, 

 a fifth thermistor as a switch to change the temperature to 70 F at launch. 



RESULTS : The first cleavage, the most sensitive to gravity, occurred before 

 launch, due to a 3 hr. delay. No differences were observed in abnormalities 

 between flight and Earth control eggs; they all fell well within the range of 

 expected abnormal development. No differences in development of the frog eggs 

 could be detected. 



CONCLUSIONS : The fertilized eggs divided, differentiated, and developed 

 normally in two days of weightlessness despite initiation of exposure at the 

 middle of the two-cell stage. 



PUBLICATIONS : 529, 530, 579, 581 



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