“…A number of mechanisms can be used by organisms to give a reasonably coherent oscillation, including three-gene repressilator systems [1][2][3], self-repressors with maturation times or other explicit, deterministic time delays (as opposed to intermediate steps which would result from a full treatment of chemical intermediates) [4][5][6][7], more complex negative feedback loops tied to population dynamics [8] combined repression and activation loops [9], highly non-linear protein degradation [10], very large numbers (hundreds) of intermediate steps [11], and self-repressors whose production and gene repression involve diffusion through the nuclear membrane [12,13]. A number of mechanisms can be used by organisms to give a reasonably coherent oscillation, including three-gene repressilator systems [1][2][3], self-repressors with maturation times or other explicit, deterministic time delays (as opposed to intermediate steps which would result from a full treatment of chemical intermediates) [4][5][6][7], more complex negative feedback loops tied to population dynamics [8] combined repression and activation loops [9], highly non-linear protein degradation [10], very large numbers (hundreds) of intermediate steps [11], and self-repressors whose production and gene repression involve diffusion through the nuclear membrane [12,13].…”