PRINCIPAL INVESTIGATOR (S ): Herbert M. Conrad 



EXPERIMENT TITLE/NUMBER : A Study of the Effect of Weightlessness on the 



Biochemical Response of a Monocotyledonous Seedling, 

 P-1138 



PROGRAM/MISSION : Biosatellite II 



CLASSIFICATION : Plant -' Wheat seedlings ( Triticum vuleare ) 



DISCIPLINE(S) : Behavioral science, Cell biology 



OBJECTIVES : To correlate changes in metabolism and energetics with the re- 

 orientation of plant organs during weightlessness and to study the key enzymes 

 associated with these processes. 



PROTOCOL : Seventy-eight wheat seeds weighing 38-39 mg were used in both the 

 flight package and Earth controls. The seeds were surface-sterilized in 0.05$ 

 Hg Cl 2 and soaked for 3 hours in distilled water at 95 F- The seedlings were 

 placed in polycarbonate stalks containing wet vermiculite. Gas samples were 

 taken and the lids sealed. To determine the extent of root displacement and 

 coleoptile curvature, pictures were taken postflight before the seedlings were 

 divided for analysis. Tissue slices were analyzed for six enzymes, protein 

 content, oxygen consumption, amino acids, and ethylene production. 



EQUIPMENT : Experiment package, cytospectrophotometer. 



RESULTS : Increased GLU-6-P dehydrogenase, GLY-3-P dehydrogenase, and 

 peroxidase was noted. No change was found in malic acid dehydrogenase, 

 transaminase, or cytochrome C reductase. Enzyme kinetics and distribution 

 were normal . 



CONCLUSIONS : The growth of wheat seedlings in space appeared normal. The 

 growth on the clinostat simulated growth in a weightless environment. 

 However, only auxin-mediated reactions were simulated by growth on the 

 horizontal clinostat. The increased enzyme activity was found to be 

 physiologic and not due to structural changes in enzymes while in the weight- 

 less state. The kinetic studies indicated that space flight does not affect 

 the affinity of an enzyme for its substrate. 



PUBLICATIONS : 133, 13 1 * 



140 



