Mohammed Shilleh, Michael Stefano, Jacqueline Watkins, Kelsey Wyman Chin
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University of Florida APX2 as a Scavenging Mechanism for Superoxides in Chloroplast
Introduction and Background Stress can be defined as a disruption of homeostasis. Chloroplasts are especially sensitive to stress and have many levels of defense against it. These defense mechanisms include adjustment of antenna size, thermal dissipation, photochemistry and, lastly, antioxidant systems that scavenge toxic compounds. Stress can induce the uncoupling of the light and dark reactions that results in the formation of dangerous reactive oxygen species (ROS)such as superoxide radical (O2-), hydrogen …show more content…
(1999) used a transgenic plant that was created by adding genes that code for luciferase to the gene they wanted to study, in this case APX2. Luciferase is used in bioluminescence because it gives off light which allows the quantification of APX2 by the light it gives off in relative light units (RLU). To make sure that adding the luciferase gene to APX2 did not affect the concentrations, they compared Northern blotting of APX2-LUC to APX2 and found that they both activated in the same manner (Stanislaw et al. 1999). To test the activation of APX2-LUC and APX2, leaves from both plants were exposed to both excess light (EL) and low light (LL). The light emitted from the leaves was then measured in RLU, at intervals of 0, 15, 30, 60, and 120 minutes and compared. A higher RLU indicated a high concentration of the enzyme produced by the APX2-LUC and APX2 …show more content…
1999). The comparison of both genes indicates that APX2 was highly active in mRNA coding during the 30 and 60 minute time lapses of excess light exposure, accounting for the most intense moment of the defense system before programmed cell death. This experiment demonstrates how light intensity causes chlorosis and consequent destruction of a plant. Global warming and holes in the ozone layers in our atmosphere can greatly impact plant activity and ecosystem homeostasis with intensifying sunlight (Takle 2001). Plants that have inhabited urbanized areas can be monitored for levels of ROS and luciferase activity to help shine a light on the regions of the world that truly need to make changes to avoid global