Development of a massively-parallel, biological circuit simulator

Genetic expression and control pathways can be successfully modeled as electrical circuits. Given the vast quantity of genomic data, very large and complex genetic circuits can be constructed. To tackle such problems, the massively-parallel, electronic circuit simulator, Xyce/sup /spl trade//, is being adapted to address biological problems. Unique to this biocircuit simulator is the ability to simulate not just one or a set of genetic circuits in a cell, but many cells and their internal circuits interacting through a common environment. Currently, electric circuit analogs for common biological and chemical machinery have been created. Using such analogs, one can construct expression, regulation and reaction networks. Individual species can be connected to other networks or cells via nondiffusive or diffusive channels (i.e. regions where species diffusion limits mass transport). Within any cell, a hierarchy of networks may exist operating at different time-scales to represent different aspects of cellular processes. Though under development, this simulator can model interesting biological and chemical systems. Prokaryotic genetic and metabolic regulatory circuits have been constructed and their interactions simulated for Escherichia coli's tryptophan biosynthesis pathway. Additionally, groups of cells each containing an internal reaction network and communicating via a diffusion limited environment can produce periodic concentration waves. Thus, this biological circuit simulator has the potential to explore large, complex systems and environmentally coupled problems.