Fig. 6

A model for the light entrainment mechanism of the cricket circadian clock. The clock includes two major oscillatory loops, one for Gb’per and Gb’tim, like in Drosophila, and the other for Gb’cry2. The latter is comprised of Gb’cry1 and two Gb’cry2 isoforms, Gb’cry2c and Gb’cry2f, and their product proteins form a complex that suppresses the transcription mediated by Gb’CLK/Gb’CYC complex [23]. Light is perceived by the retinular cells in the compound eye expressing Gb’opLW, and the information is transmitted to the clock neuron in the optic lobe through neurotransmitters. This neurotransmission causes upregulation of Gb’c-fosB in the clock neurons, which finally affects the Gb’cry2 oscillatory loop. The change in the Gb’cry2 loop may reset the whole clock system since the Gb’cry2 loop interact with the Gb’per/Gb’tim loop by influencing Gb’CLK/Gb’CYC. In addition to the Gb’cry2 pathway, the Gb’Pdp1 pathway resets the clock by upregulating Gb’Clk expression when light off was delayed [22]