Fig. 1

Effect of starvation and refeeding on PRIle-piwi1 expression and gonad size. a–i″ PRIle-piwi1 expression in the gonad region (a–i), fission zone region (a′–i′), and posterior growth zone (a″–i″) during starvation (a–e″) and refeeding (f–i″). Expression decreases and becomes undetectable in all three body regions as worms are starved over 28 days and is reestablished in all three body regions when starved worms are fed over 18 days. All images were taken at the same magnification; worms shrink when starved. (k–l′) MGP staining in the gonad region of segment 6 in well-fed and starved worms. Testes are evident in well-fed animals (dashed box in k; black arrowhead in k′) but not detectable in starved animals (dashed box in l, white arrowhead in l′). k′ and l′ are magnified views of the boxed regions in k and l. Curved dotted line in k′ and l′ indicates the position of the septum between segments 5 and 6. m Quantification of testis size in starved and well-fed animals. Animals starved for 1 month had no detectable gonads (n = 24); well-fed animals typically had gonads, but these were highly variable in size (n = 14). n–o′ EdU incorporation in gonads of developing head segments being formed by fission. Magenta label indicates proliferative (EdU-positive) cells. n′ and o′ are magnified views of the boxed regions in n and o. Black arrowheads indicate the presence of gonad expression or gonad structures; white arrowheads indicate the absence of such expression or structures. Fission zones are marked by gray bars. Anterior is left in this and all other figures. t testis, o ovary, s stomach. Scale bars 100 µm