<i>riok-1</i> is required for normal germ cell proliferation.

<p>(A) Overview of the adult <i>C. elegans</i> hermaphrodite gonad. One of the two gonad U-shaped tubular gonad is shown. The single somatic distal tip cell (DTC) maintains a population of self-renewing germline stem cells. Germ cells enter into the meiotic prophase I in the transition zone and then progress to the pachytene stage. During these stages, germ cells are only partially enclosed in a membrane and share a common cytoplasmic core. As germ cells exit pachytene, they move through the “loop” region and enter diplotene and begin to fully cellularise. A signal from sperm directs the most proximal oocytes to undergo maturation and fertilisation occurs are the oocyte moves through the spermatheca into the uterus. (B-C) Dissected gonads were stained with anti-pH3 staining to detect proliferating germ cells and DAPI to visualise DNA. Asterisks indicate the distal end of the gonad. Scale bar = 15μm. (D-E) <i>riok-1(RNAi)</i> gonads had a reduced number of pH3 stained cells in the mitotic zone (D) Wild-type worms with <i>riok-1</i> knocked down at 20°C and 25°C <i>(n = 50)</i> (E)) <i>rrf-1;pCB19(RNAi)</i> and <i>rrf-1</i>:<i>riok-1(RNAi)</i> worms at 20°C and 25°C <i>(n = 50)</i>. Error bars represent SEM; _**** = P values &lt;0.0001.