Team:Northwestern/Description
PROJECT DESCRIPTION
INSPIRATION
Over the past few decades there has been an increased incidence of skin cancer in many populated areas. This is a pressing concern for areas with high UV exposure, including Peru, Argentina, New Zealand, and Australia with the latter two countries having the highest skin cancer rates in the world [1]. Extended exposure to UV light causes DNA damage that leads to various health problems. As such, there is a dire need for making sure civilians are cognizant of the UV exposure in their area.
Currently, products on the market that detect UV levels and exposure include HPLC and digital UV meters. However, they do not relay how much damage is actually occurring to DNA as a result of UV exposure. There are also products on the market that use UV sensitive yeast to make educational kits for students to learn more about UV exposure and damage. While this kit is helpful, it does not distinguish between differing levels of UV damage. With our sensor, we hope to bridge this gap by correlating the amount of fluorescence to the amount of UV-induced DNA damage.
PROJECT DESCRIPTION
When UV light is absorbed by DNA, it can induce dimerization of two adjacent pyrimidine bases [2]. This linkage can result in the dimer being read as a single base, halting DNA replication.
Figure 1: Thymine dimers form as a result of UV radiation and damage.
In order to visualize this type of UV damage, we take advantage of natural systems that have already evolved for years to sense and respond to UV light via various mechanisms. For instance, the SOS system responds to UV-induced DNA lesions by halting the cell cycle and activating DNA repair mechanisms [3]. Specifically, we will utilize the nucleotide excision repair (NER) mechanism, one of the first responses of the SOS system to address UV-induced DNA lesions. The NER mechanism in Escherichia coli begins with the protein UvrA, whose expression increases by 10-fold from around 25 molecules to 250 molecules upon SOS induction [4]. We plan to measure this increase via a biological circuit with a fluorescence reporter gene, GFP, and a promoter for the uvrA gene.
We will construct a plasmid containing GFP downstream of the native E. coli uvrA promoter. As a result, when a cell experiences DNA damage from UV radiation, a series of reactions will be triggered that allow for the cell to produce fluorescent signals based on the amount of damage. This biosensor will have novel applications in demonstrating not only UV exposure but DNA damage itself in an intuitive and informative way. We believe that it would be impactful to use our biosensors as an educational kit with practical usage for scientific demonstrations for school children undergoing primary/secondary education. Our hope is that this project will promote public awareness about UV-induced DNA damage and its consequences.
