Fig. 1

Sleep phenotypes of shmt mutants. a A schematic representation of a point mutation leading to a premature stop codon in shmt (thus shmt-early stop or shmt-es). Also shown is the amino acid sequences of the shmt-es mutant line used here. Single gRNA generated insertion and/or deletion (indel) in the shmt gene, introducing a frameshift and a stop codon (asterisk). b A diagram of D-Ser synthesis pathway. c mRNA level of isoform A shmt in shmt-es was significantly reduced. d Sleep profiles of shmt-es (red) (n = 57) and wt (black) (n = 236) flies, plotted in 30 min bins. White background indicates the light phase (ZT 0–12); shaded background indicates the dark phase (ZT 12–24). e Statistical analyses. Daytime and nighttime sleep durations were significantly reduced in shmt-es flies. In this and other figures, open bars denote daytime sleep and filled bars nighttime sleep. f Drug treatment of both L- and D-Ser rescued the nighttime sleep duration of shmt-es flies to the wt level. The number of flies used in the experiment was denoted under each bar. ***P < 0.001, n.s. P > 0.05, Mann–Whitney test was used in (c, e), two-way ANOVA test with Bonferroni posttests was used in (f) to compare the sleep durations between wt and shmt-es, Kruskal–Wallis test with Dunn’s posttest was used in (f) to compare the sleep durations of shmt-es under different drug treatments. Error bars represent s.e.m. Male flies were used