Fig. 1. Multiple regions of the pal-1 3' UTR repress translation in the distal gonad arm. (A) Schematic of an adult gonad arm illustrating the progressive maturation of germ cells. pal-1 mRNA (yellow) is present throughout the germline, yet PAL-1 protein (red) is detectable only in immature oocytes (47% of gonad arms (n=49) exhibit no PAL-1 expression). (B-D) Gonad arms injected with lacZ, lacZ::3' UTR and lacZ::GRE RNA, respectively, and stained with X-gal. Insets show dissected distal gonad arms that were injected with the same RNAs (except in D, where lacZ::2X GRE RNA was used) and hybridized with lacZ antisense probe. (E) Schematics of lacZ reporter constructs with blue bars denoting the percentage of injected gonad arms with distal germline expression. Regions A, B, and the GRE mediate repression. (F) Sequence of the GRE.