Fig. 1: PGL-1 tethering represses an mRNA reporter in vivo.

a Left, C. elegans adult hermaphrodite possesses two gonadal arms with proliferating germ cells at one end (asterisk) and differentiating gametes at the other. Gonads make sperm (blue) first and then oocytes (pink). Right, P granules (magenta) reside at the nuclear periphery of all germ cells until late oogenesis. Modified from⁷⁵. b Linear diagram of C. elegans PGL-1. N-terminal dimerization domain (NtDD, yellow), central dimerization domain (CDD, orange), C-terminal region (C-region), and RGG repeats (blue). c Protein–mRNA tethering assay. The reporter mRNA encodes GFP (green)-histone H2B and harbors three boxB hairpins in its 3′UTR; a ubiquitous germline promoter drives expression (see Methods). λN22 peptide (light blue) is inserted into PGL-1 with a SNAP tag (magenta). Binding of PGL-1::SNAP::λN22 to boxB hairpins recruits reporter mRNA. Modified from⁷⁶. d–g GFP reporter expression in germ cells of live animals. (d, e) Brightfield image. (f, g) GFP fluorescence (green); auto fluorescence (red). n, number of animals scored for GFP expression. %, germlines with detectable GFP. Scale bar, 10 μm, in (d) applies to (d–g). Fisher’s exact test of PGL-1::SNAP vs. PGL-1::SNAP::λN22/+ (p-value < 0.0001). h–k Representative images in fixed gonads. (h, i) GFP fluorescence (green). (j, k) SNAP staining (magenta) and DNA (DAPI, cyan). n, number of germlines scored for GFP expression. Fisher’s exact test of PGL-1::SNAP vs. PGL-1::SNAP::λN22/+ (p-value < 0.0001). Scale bar, 10 μm, in (h) applies to images. Scale bar, 10 µm. Figure 1 and Fig. 5 results were performed in parallel, and thus results from (e, g, i, k) are the same as reported in Fig. 5b, d, f, h.