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The use of Green Fluorescent Protein (GFP) as a reporter gene system is an accurate and non destructive means for generating organ, tissue and cell-specific data on gene expression in plants. While many commercial imagining systems are available for standard terrestrial laboratory imaging of GFP, none of these systems begin to meet the requirements for a flight unit that could be utilized to monitor plant gene expression in spaceflight habitats. We present here data derived from ground testing of a prototype GFP flight imaging unit, the TAGES Imaging System (TIS). The TIS software is designed to collect multiple images of the same view to facilitate the stacking of the images for enhanced detail resolution. Analyses of stacking software and tactics for improving resolution are being evaluated. The TIS is being developed as a component of the payload hardware design of the next generation of Plant Growth Facility (PGF).

We report here on a series of KC-135 parabolic flight studies investigating various aspects of water distribution in plant nutrient delivery systems being developed for spaceflight applications. Several types of porous tubes were evaluated. Under microgravity conditions, fluid was observed to creep up the end walls of polycarbonate substrate compartments. Capillary mats wrapped around the porous tubes wetted up in a uniform fashion regardless of the level of gravity to which they were being exposed, and they were found to eliminate the end-wall creep wetting-up pattern. Results from observations using 1-2 mm glass beads and 1-2 mm Turface substrates are presented. The Turface’s absorption of water effectively minimized fluid redistribution as the compartment alternated between microgravity and 1-1.8g conditions.

The development of a spaceflight-rated Porous Tube Insert Module (PTIM) nutrient delivery tray has facilitated a series of studies evaluating various aspects of water and nutrient delivery to plants as they would be cultivated in space. We report here on our first experiment using the PTIM with a software-driven feedback moisture sensor control strategy for maintaining root zone wetness level set-points. One-day-old wheat seedlings (Tritium aestivum cv Apogee; N=15) were inserted into each of three Substrate Compartments (SCs) pre-packed with 0.25–1 mm Profile™ substrate and maintained at root zone relative water content levels of 70, 80 and 90%. The SCs contained a bottom-situated porous tube around which a capillary mat was wrapped. Three Porous Tubes were planted using similar protocols (but without the substrate) and also maintained at these three moisture level set-points. Half-strength modified Hoagland’s nutrient solution was used to supply water and nutrients.

Wheat seeds were automatically imbibed and germinated within a Porous Tube Insert Module (PTIM) apparatus developed to support both porous tube and substrate-based nutrient delivery systems (PTNDS, SNDS) in space. The PTIM was operated under both; (1) a programmable fixed feed mode, and (2) a moisture sensor feedback control mode. For the former, increased levels of water use efficiency were evident within the PTNDS component of the study. For the latter, moisture sensors within the SNDS were evaluated at setpoints of 65-85% relative water content. Data demonstrating the ability of this approach to control moisture levels and the vertical moisture distribution patterns obtained over an 18 d grow-out interval are presented.

The Magnetic Field Apparatus (MFA) is a newly developed hardware system for space flight experimentation. The main goal of the MFA is to provide a platform to conduct experiments exposing plant tissues to a high gradient magnetic field (HGMF) in a microgravity environment. The MFA is being developed as a Space Shuttle middeck facility, and once completed will be classified as generic Life Science Laboratory Equipment (LSLE) and available to all NASA-sponsored investigators. The first flight of the MFA will be on STS-107 (currently scheduled for mid-2001). It will be configured to carry dry flax (Linum usitatissimum L.) seeds into space, imbibe the seeds on-orbit, and expose the emerging roots to a high-gradient magnetic field. Time-lapse digital imagery will document root development, and the hardware will support chemical fixation at the appropriate time to preserve the specimens and terminate the experiment.

The Porous Tube Insert Module (PTIM) is a plant growth apparatus utilizing a porous tube design. The PTIM is under development by the Bionetics Corporation and has been designed as an insert to the Plant Generic Bioprocessing Apparatus (PGBA: Developed by Bioserve Space Technologies). The Water Offset Nutrient Delivery ExpeRiment (WONDER) will perform a side by side evaluation of the PTIM's Porous Tube Nutrient Delivery System (PTNDS) and a Substrate Nutrient Delivery System (SNDS). The PGBA will serve as the environmental chamber and environmental control system for the PTIM. The PGBA will also host the WONDER sequencer software within its control computer. The PTIM integrates six porous tubes wrapped with seed mats. In the SNDS, the tubes and mats are embedded within a substrate material while in the PTNDS, they are exposed to the chamber environment. The PTIM hydraulic equipment includes porous tubes fed by computer controlled miniature pumps and valves.

Engineers and scientists from BioServe Space Technologies and Kennedy Space Center (KSC) are developing a flight-rated payload for the evaluation of two space-based plant nutrient delivery systems (NDS's). The hardware is comprised of BioServe's Plant Generic Bioprocessing Apparatus (PGBA) and KSC's Porous Tube Insert Module (PTIM). The PGBA, a double-middeck locker, will serve as the host carrier for the PTIM and will provide computer control of temperature, relative humidity, and carbon dioxide levels. The PTIM will insert into the PGBA's growth chamber and will facilitate the side-by-side comparison of the two NDS's: 1) the porous tube NDS, consisting of six porous tubes with seeds mounted in close proximity to the tubes, and 2) a substrate-based NDS, with three compartments each containing a porous tube embedded in a particulate substrate.