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Histochemical Data Collection of Transgene Expression using Arabidopsis thaliana Plants L.J. Bradford1, A-L. Paul2, R.J. Ferl2 1Alabama A&M University, Normal, AL, and 2  Dept. of Horticultural Sciences, University of Florida.

   The native arabidopsis gene Alcohol dehydrogenase (Adh) has been shown to be expressed when plants undergo spaceflight-associated stress.  It is hypothesized that the lack of convection in spaceflight environments contributes to localized hypoxia in plants.  Although hypoxic stress can be evaluated many ways, expression of alcohol dehydrogenase (Adh) is regarded as a hallmark of a response to reduced oxygen in the environment. The present work used transgenic Arabidopsis plants containing a reporter gene composed of the Adh gene promoter attached to the Beta-glucuronidase (GUS) coding region.  Expression of the Adh/GUS transgene reflects levels of native Adh gene expression and was used to evaluate Adh expression in plants exposed to varying degrees of hypoxic stress. Preliminary ground experiments were used to articulate the correlation between the degree of Adh/GUS expression in stained tissues and the expression of native Adh gene on the basis of real-time reverse transcriptase polymerase chain reaction (RT-PCR) The purpose of the pre-flight experiments was to research data that could be used to survey Adh expression in response to various degrees of hypoxic stress.  Findings from these experiments have shown Arabidopsis native Adh gene expression to be proportional to reporter GUS gene expression after controlled hypoxic stress inductions.  Research was also conducted under both ground control conditions (Percival Growth Chamber) and ambient "spaceflight" conditions (Orbital Environmental Simulator, OES) during a simulated spaceflight mission, LASSE (Launching a Simulated Spaceflight Experiment).  These experiments were designed to investigate whether the conditions of spaceflight and closed environments, such as increased levels of ethylene and carbon dioxide (CO2), had any effect on gene expression.  Quantitative RT-PCT results from LASSE indicate that gene expression can be differentially influenced by such gaseous conditions associated with the closed environment typical of spaceflight conditions.

(Supported by NASA's 2003 Spaceflight and Life Sciences Training Program )