Figure 1. E. faecalis induces early larval arrest in C. elegans: (A) Images of C. elegans L1 larvae fed E. coli OP50 (Top) or E. faecalis OG1RF (Bottom) for 24 h, 48 h and 72 h. Scale bar, 100 um. (B) Mean +/- SEM of body length in populations of L1 larvae fed OP50 or OG1RF for 24 h, 48 h and 72 h. Reported length of L1, L2, L3 and L4 larvae is indicated on the right y axis. (C) Kaplan Meier survival curves for wild type animals fed on OG1RF and deltafsrB E. faecalis (TX5266). Also see Table 1. (D) Mean +/- SEM of body length in populations of L1 larvae fed OP50, OG1RF or TX5266 for 24 h, 48 h and 72 h. (E) Mean +/- SEM of body length in populations of 48 h starved, E. faecalis-fed and E. coli-fed larvae transferred to E. coli plates and measured at regular intervals of 12 hours. n=15-20 animals/ treatment/experiment in panels 1B, 1D and 1E where each point represents the mean of body length of a population of animals (N>3 experiments). *, p less than equal to 0.05; **, p less than equal to 0.01; ***, p less than equal to 0.001; ns-non-significant. In panel D, * indicates significance with respect to OP50-fed animals at the same time point. (F) (i) Cartoon showing vulval invariant cell lineages and morphogenesis in wild-type hermaphrodites (Burdine et al., 1998; Sulston and Horvitz, 1977; Cui and Han, 2003). At larval stage, L3, vulval precursor cells P(5-7).p adopt primary (1) or secondary (2) cell fates and undergo invariant cell divisions to produce 22 cells organized into toroids, VulA, vulB1, vulB2, vulC, vulD, vulE, and vulF, shown by A, B1, B2, C, D, E, and F cell types (Sharma-Kishore et al., 1999). Blue coloured oval cells indicate
egl-17::cfp expression in specific lineages. (ii) Cartoon showing early L4 vulva, when
egl-17::cfp is exclusively seen in granddaughters of P6.p (1), and mid-L4 stage, where the expression is shifted to 2 lineage cells, vulC and vulD. (iii) Merged DIC and fluorescence images showing stage specific
egl-17::cfp in vulval cells. P6.p (1 cell stage/L2), P6.px (2 cell/midL3), P6.pxx (4 cell/mid to late L3), and P6.pxxx (8 cell/early L4 onwards), x denotes one round of mitotic division. Gonads are demarcated with white line. In all animals, anterior is to the left. Scale bar, 5 um. (G) Expression of
egl-17::cfp in C. elegans L1 larvae fed OP50 or OG1RF for 20 h and 84 h. Duration of feeding on E. coli or E. faecalis are shown on X-axis and the bars represent % positive or negative
egl-17::cfp in vulva cells. Numbers on the bars indicate the number of animals which are positive or negative for
egl-17::cfp expression. Zero on top of blue bars indicate that there are no OP50-fed animals which do not show
egl-17::cfp expression. (H) Confocal images of
egl-17::cfp in C. elegans L1 larvae fed OP50 or OG1RF for 20 h and 84 h. White circles depict gonad primordium and yellow P6.p lineage. In all animals anterior is to the left. Scale bar, 5 um. (I) Scanning electron microscopy images of larvae fed OP50 for 4 h and fed OG1RF for 72 h. Arrow heads indicate alae. n= 25-30 animals/ treatment. Scale bar, 20 um.