Fig. 7. Models of factors regulating GLD-1 accumulation levels. (A) Schematic representation of GLD-1 accumulation in the distal germline with factors inhibiting accumulation (barred lines) and factors promoting accumulation (arrows). GLP-1/Notch signaling and FBF sequentially inhibit GLD-1 accumulation at the distal-most end of the germline, while GLD-2 and NOS-3 redundantly promote GLD-1 accumulation. (B,C) Alternative models describing the genetic relationships between glp-1 signaling and nos-3 and gld-2 relative to GLD-1 accumulation. (B) glp-1 signaling inhibits GLD-1 accumulation by inhibiting the redundant activities of nos-3 and gld-2. Alternatively (C), glp-1 signaling works in parallel with nos-3 and gld-2, and GLD-1 accumulation reflects the net influence of these factors. (D) Genetic pathway regulating GLD-1 accumulation. In the distal end fbf and gene x inhibit nos-3 and gld-2, respectively. More proximally, where glp-1 signaling is low, nos-3 and gld-2 promote GLD-1 accumulation. (E) Genetic model of genes functioning in the proliferation versus meiotic entry decision. glp-1 signaling inhibits the gld-1 and gld-2 pathways in the most distal end. For gld-1, this inhibition involves fbf-1/-2 inhibiting the promotion of gld-1 by nos-3. gld-2 is inhibited by something (x) other than, or in addition to, fbf-1/-2. As glp-1 signaling is reduced in more proximal cells, nos-3 and gld-2 promote GLD-1 protein accumulation, and both gld-1 and gld-2 promote meiotic development and/or inhibit proliferation (see text).