Reed Dowling


Presentation: 10:45 a.m.-12:00 p.m., Kennedy Union Ballroom



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In this project, we analyze the changes to DNA upon irradiation with UV light. We used threespectroscopic techniques: UV-Vis absorption, Circular Dichroism (CD), and fluorescence to follow thechanges in four different nucleic acid sequences irradiated at selected exposure times with an Hg Lamp.We analyze: calf thymus DNA, poly (deoxyadenylic-deoxythymidylic) acid [poly(dA-dT) 2 ], poly(deoxyguanylic-deoxycytidylic) acid [poly(dG-dC) 2 ] and poly (deoxyadenylic acid) · poly (deoxythymidylicacid) [poly(dA) · poly(dT)]. In all cases, both the CD and UV-Vis spectra undergo sequence dependentchanges. On the other hand, fluorescence was observed only when thymine and adenine base pairs arepresent and is enhanced when the thymine nucleobases are adjacent to each other on the same strand.Poly(dA) · poly(dT) undergoes changes more rapidly than the other sequences investigated andtherefore represents the most interesting results obtained in this project. In particular, after irradiationwith UV light we observed: 1) a fluorescent photo-product with an emission spectrum with a maximumat approximately 402 nm produced upon excitation of the samples at 298 nm; 2) the CD spectrum ofpoly(dA) · poly(dT) gradually undergoes an inversion, suggesting a change in helicity, beforedisappearing due to the unfolding of the double strand.

Publication Date


Project Designation

Independent Research

Primary Advisor

Angela Mammana; Dr. Gregory Carroll is an off-campus advisor and co-author on the research.

Primary Advisor's Department



Stander Symposium, College of Arts and Sciences

Spectroscopic Study of UV-Irradiated DNA