Figure 1. Excessive DTCs Form Instead of the Proximal Anchor Cell in
nhr-25(RNAi) Hermaphrodites. (A) The asymmetric division of the somatic gonad precursors Z1 and Z4 occurs during the L1 stage at around 8 hr posthatching (Kimble and Hirsh, 1979). The following divisions produce two distal tip cells (DTC) and proximal cells, one of which is selected as the anchor cell (AC).(B) Two DTCs and one AC in a normal worm (top) are visualized by
lag-2::gfp and
cdh-3::gfp markers, respectively.
nhr-25 RNAi applied by feeding since the time of hatching causes one (middle) or two (bottom) extra DTCs to form at the expense of the AC (arrows indicate the normal AC position).(C) In situ hybridization reveals that
nhr-25 mRNA is expressed in the early gonad primordium (brackets). Bar = 20 um.(D) The endogenous NHR-25 protein is detected in the nuclei of Z1 and Z4 (arrows) but not in the Z2/Z3 germline precursors (arrowheads). The yellow line shows the approximate shape of the gonad primordium, and
lag-2::gfp expression marks Z1 and Z4 cells.(E) NHR-25 is also present in the immediate Z4 (yellow lines) and Z1 (out of focus) daughters. Bars in (D) and (E) = 10 um. In all panels, anterior is to the left.