Department of Biostatistics Seminar/Workshop Series

Identification of a set of signature cell-cycle genes whose relative order of phase is conserved across species

Shyamal D. Peddada, PhD

Principal Investigator, Biostatistics Branch National Institute of Environmental Health Sciences (NIH)

Wednesday, May 16, 1:30-2:30pm, MRBIII Room 1220

Cell-cycle in eukaryotes is a well-coordinated process with cells going through four distinct phases before dividing. Genes with periodic expression are known as cell-cycle genes. To discover evolutionarily conserved cell-cycle genes, biologists are often interested in identifying genes that are periodic in multiple organisms. Since cell-cycle is a carefully orchestrated process, one may hypothesize that the relative order of time to peak expression among the core set of cell-cycle genes is conserved evolutionarily. In this talk we introduce a novel statistical methodology by formulating the problem of interest as an order restricted inference problem on a unit circle. Standard order restricted inference methods do not directly apply here due to the geometry of the circle. We introduce a simple conditional test, whose null distribution can be approximated by central chi-square distribution, to test the hypothesis of interest. Using the proposed statistical methodology, we discover six cell-cycle genes whose relative order is potentially conserved evolutionarily. In addition to cell-biology, the proposed methodology can potentially have applications in studying the phase of circadian clock genes in patients with neurological diseases (such as Alzheimer or Parkinson etc.).