Sir Kenneth Mather Memorial Prize 2017/18 – Rosina Savisaar

I am very happy and grateful to have been awarded the Sir Kenneth Mather memorial prize.  I am also very thankful to Prof Laurence D. Hurst for the nomination and for his excellent supervision during my PhD at the University of Bath. I have now finished my thesis and am working at Nile University in Giza, Egypt, where I teach bioinformatics. I try to sneak in some (population) genetics whenever I can.

I am interested in how the mechanistic details of gene expression constrain sequence evolution. For example, correct splicing requires the binding of splicing factors to regulatory motifs in the mRNA transcript. These motifs often occur inside coding regions. This leads to a fascinating situation where certain parts of the coding sequence have to do two jobs at once: specify the amino acid sequence in that region of the protein but also maintain the binding motif for the splicing factor.

In my thesis work, I studied patterns of selection on such regulatory motifs in human coding sequences. Most importantly, I found that selection to preserve splice promoting motifs is not only widespread (roughly one in five fourfold degenerate sites are constrained) but also strong. Hence, contrary to the received wisdom, human synonymous sites are frequently under strong negative selection. The need to ensure correct splicing is thus an important determinant of how our coding regions evolve.