School of Engineering Department of Chemical and Biological Engineering 74 Influence of Random Base in Poly(A) tail to the Function of Mammalian mRNA Supervisor: KUANG Becki Yi / CBE Student: DANI Raissa Gavrila / BIOT Course: UROP1100, Fall mRNA or messenger RNA has a vital role in all organisms since it directly corresponds to the protein coding gene and allows protein to be produced within the cell. Post RNA transcription within the nucleus, the RNA will undergo a post-translational modification through splicing, 5’ 7-methylguanosine capping, and 3’ polyadenylation. A report by Chang et.al utilized the TAIL-Seq and they found that the poly(A) tail of mRNA has an insertion of other base pairs. Guanine insertion, in particular, was found favorable and can further stabilize the mRNA molecule. This report will thus further investigate the effect of inserting other base pairs such as cytosine residue in the poly(A) tail and observe its effect on the half life of the mRNA. RNAs with different poly(A) tails will be made through in vitro transcription and will be subjected for transfection into the mammalian cell. A luciferase assay will then be used to analyze the half-life of the protein by quantifying the luminescence of the oxyluciferin. Influence of Random Base in Poly(A) tail to the Function of Mammalian mRNA Supervisor: KUANG Becki Yi / CBE Student: SHI Naiyu / BIEN Course: UROP3100, Fall The COVID-19 pandemic has brought messenger ribonucleic acid (mRNA) vaccines to the general public. mRNAis a single-stranded RNA. It delivers the genetic information of the DNA to the cytoplasm to synthesize proteins. To protect mRNA from degradation, a poly(A) tail is added at the 3’ end. Despite the name suggesting it is a string of adenines, random insertions of guanine (G), cytosine (C) and uracil (U) inside poly(A) tails have been found. These insertions seem to have the capability of affecting the half-life and the translation efficiency of the mRNA, however, whether these insertions are the reason for the changes and how they influence the functions and properties of mRNA are not known. This project aims to investigate the influence of insertions of G in poly(A) tails of mammalian mRNA.