ASGSB 1998 Annual Meeting Abstracts

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BPAC EXPERIMENT TO EXAMINE THE EFFECTS OF SPACEFLIGHT ON THE PHOTOSYNTHETIC APPARATUS.    J.A. Guikema¹, E. Hilaire², and S. Jiao¹. ¹Div. Biol, Ackert Hall and ²Dept Plant Pathol, Throckmorton Plant Sciences Center, Kansas State University, Manhattan, KS 66506.

As part of the Cooperative US/Ukrainian Experiment (CUE), an experiment was designed using the Plant Growth Facility to monitor the effects of spaceflight on the photosynthetic apparatus of Brassica rapa. Pre-flight operations included modifying the chamber environment to support optimal B. rapa growth. This included studies on plant nutrition and on the rooting environment, as well as studies on appropriate lighting and temperature conditions. During the STS-87 mission, germination was initiated in microgravity by applying nutrient solution to positioned seeds, and growth was monitored throughout by photography. Ground controls were similarly activated, delayed 48 hr such that identical conditions of temperature, humidity, and gas concentrations could be programmed in the Orbiter Environmental Simulator chamber. At two time points during the flight, a subset of the plants were harvested and were fixed on orbit for subsequent microscopic examination. Landing occurred in the 14^th day of plant growth, and fresh tissue was harvested beginning 2 hr following landing. Cotyledon leaves were frozen at the Kennedy Space Center, for subsequent biochemical examination at Kansas State University, while the first tier of true leaves were examined immediately for a suite of photosynthetic characteristics. Preliminary data obtained from cotyledon tissue suggests a reduction of PSI activity caused by growth on STS-87, and this reduced activity corresponds with a reduction in PSI proteins observed by western blot analysis.

(supported by NASA grants NAGW-2328, NAG10-0142, and the Kansas NASA EPSCoR program.)

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