(A) Schematic of study design. WT cells are photoautotrophic and rely on light for both growth and clock signaling. Transgenic cells expressing the GalP sugar transporter can use glucose as an alternative energy source.

(B) Growth of GalP-expressing cells in the dark. A series of micrographs demonstrates the length increase of GalP cells under dark conditions. WT cells contract slightly under prolonged dark conditions.

(C) Increase in total biomass, defined as the normalized sum of all cell lengths, before and after a light-dark transition for WT cells (black) and GalP-expressing cells (red) in the presence of 0.4% glucose.

(D) Clock response to a dark pulse reported by fluorescence in single cells. PkaiBC::eyfp-ssrA fluorescence traces before and after a dark pulse (shaded bar) for selected WT cells (black) and GalP-expressing cells grown in the presence of glucose (red). LL, constant light.