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DEVELOPMENT OF A HIGH-RESOLUTION REMOTE SENSING IMAGER SYSTEM FOR THE MONITORING OF GFP REPORTER GENES FOR SPACE BIOLOGY EXPERIMENTS.  A.C. Schuerger¹, A-L. Paul², J.T. Richards¹, and R.J. Ferl².  ¹Dynamac Corp., Kennedy Space Center, FL and ²Hort. Sci. Dept., Univ. of Florida, Gainesville, FL.

   Green fluorescent protein (GFP) reporter genes have been proposed as non-destructive means of monitoring gene expression in plants grown in space biology experiments.  In order to accurately monitor the GFP-tagged reporter genes a remote sensing imaging (RSI) system was developed based on off-the-shelf hardware and software components.  The RSI system was composed of a high-resolution 16-bit astronomical CCD camera with a pixel array of 2184 (H) x 1472 (V) (CCD chip was a Kodak model KAF-3200).   Individual pixels measured 6.8 x 6.8 µm and the CCD chip could be cooled to –13 C using an internal peltier cooler.  The RSI system also was configured with a set of eight narrow bandpass filters centered at 440, 510, 550, 685, 700, 720, 740 and 760 nm (all filters with 10 nm FWHM) mounted in a PC-controlled filter wheel.  A broad-spectrum xenon-arc lamp was used to generate a set of eight spectral reflectance images in the visible and near-infrared regions.  A second light source centered at 470 nm (20 nm FWHM) was used to excite the GFP reporter genes (510 nm) and to excite chlorophyll fluorescence (685 and 740 nm) in plant leaves.   All images were calibrated and processed using Maxim DL (Diffraction Ltd., Nepean, Ontario) or Mira Pro 6.0 (Axiom Res., Tucson, AZ).  The RSI system could image features on leaves of transgenic Arabidopsis thaliana plants at the sub-trichome level.  Green fluorescence of expressed GFP reporter genes was clearly observable in small groups of cells throughout the plant canopies.  Spectral reflectance images were used to estimate leaf biomass, chlorophyll concentration in leaves, and overall health of plant canopies.  The RSI system can be modularized or miniaturized for space biology experiments depending on the mission objectives and constraints. 

(Supported by NASA: AO-99-HEDS-01-032 and NAG10-291.)

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