Debashis Barik

Current Research Interests

I am a postdoc in labs of both Prof. John J. Tyson and Dr. Mark R. Paul (Dept. Mechanical Engineering) since March, 2007.

Chemical reactions are intrinsically noisy due to the inherent uncertainty in the collision event of the reacting molecules. In general, the amount of noise is inversely proportional to the square root of the size of the system (here the number of reacting molecules). A living cell is like a reaction chamber, where chemical reactions are occurring at every instant of time. In a typical yeast cell, the population of proteins, on average, varies from a couple of hundreds to several thousands molecules and the number of mRNA varies ranges from one to ten molecules. Due to the low copy number of mRNA and the low abundance of transcription factors, protein expression levelfluctuates a lot. Simple model of gene expression reveals that the noise in gene expression also critically depends on the times scales of transcription and translation and on the average life times of mRNAs and translated proteins. The fluctuations in the gene expressions level are reflected in the phenotypic behavior of a cell.

Recent single cell measurements on budding yeast cells have quantified not only the average cell cycle time, the durations of the G1 phase and the S/G2/M phases and the durations of several other critical events in the cellcycle, but also the variability of those durations both for the mother and the daughter cells in various growth conditions. For the last two years I have been involved in building mathematical model of budding yeast cell cycle (stochastic model) to explore how the protein-protein and gene-protein interaction networks and noise in individual gene expression contribute to the over variability in the cell cycle.

Education

Publications