Internal Seminar: Luscombe Unit and Dani Unit

Join us for May's first Internal Seminar Series on May 1, from 17:00 to 18:00 in B250. This month's first seminar features the Genomics and Regulatory Systems Unit (Nicholas M. Luscombe) and Femtosecond Spectroscopy Unit (Keshav Dani).

Genomics and Regulatory Systems Unit (Nicholas M. Luscombe)

Speaker : Filipe Tavares-Cadete

Title : How DNA is packaged inside human cells helps control gene expression

Abstract : The long molecules of DNA are tightly packaged inside the cell nucleus. Via folds and loops, locations that might be far apart in the linear DNA sequence are brought close together in the living cell. These long-range contacts between distant parts of the genome can impact gene expression. For example, physical interactions between a distal regulatory region encoded in the genome (like an enhancer) and the beginning of a gene (in other words, the gene promoter) can determine whether the gene is transcriptionally active within certain cell types. We have used a genome-wide technique called Hi-C to examine the pattern of physical interactions between ~20,000 gene promoters encoded in the human genome and their regulatory regions, and identified over 1.6 million interactions. By performing these experiments in two distinct human cell types, we also identified how DNA makes different types of contacts depending on what genes need to be activated. Finally, it is known that ~95% of disease-associated mutations occur outside of genes’ coding sequences, creating a challenge to understand how they affect human health; using our method, we find that many of these mutations are found in regulatory regions, and that they may cause diseases by perturbing normal gene expression.

Femtosecond Spectroscopy Unit (Keshav Dani)

Speaker : Dr. Michael K. L. Man

Title : Tracking electrons through time, momentum, space and energy.

Abstract : Understanding the electronic structure of a material, i.e. knowing the ‘position’ of electrons in momentum-space, real-space, energy as they evolve in time, provides a rich understanding of the evolving properties of a solid. In the context of photoexcited electrons, the pico- and femtosecond scale provide the fundamental timescale of ‘motion’ of excited electrons in solids. Traditionally, such fast times scales are only accessible with light, and require us to infer the electronic structure via the measured optical properties. Over the past three years at the Femtosecond Spectroscopy Unit, we have been developing technology that allows us to combine femtosecond optics with electron spectroscopy and thereby directly measure the ‘motion’ of photoexcited electrons in materials as they traverse through real space, momentum space and energy space on the femto- to picosecond timescale. In this talk, we will present our very early results.