Fig. 5. FIGL-1 is expressed in the mitotic zone of the germ line and accumulates in
mel-26 mutants or
cul-3- depleted animals. (A) The localization of FIGL-1 and MEL-26 was determined by immunofluorescence in the gonads of wild-type animals by using affinity-purified antibodies against FIGL-1 (top left) and MEL-26 (top right). The DNA was visualized by Hoechst staining (bottom row). The beginning of meiosis (transition zone) is marked by arrowheads and is defined as the region where 60% of the nuclei are in meiotic prophase, as indicated by the crescent-shaped nuclei (depicted in yellow). The white box delineates the area shown at higher magnification in the inset. Stars mark nuclei before meiotic prophase; the short arrows in insets point to crescent-shaped nuclei in meiotic prophase. Note that the staining of FIGL-1 is significantly reduced (P<0.05) in cells entering into meiosis compared with cells in mitosis. Bars, 10 μm. (B) The expression of FIGL-1 (top panel) was investigated by immunofluorescence as described for panel B in gonads of
mel-26(
ct61sb4) animals. All stainings were performed under the same conditions to allow comparison. The DNA was visualized by Hoechst staining (bottom panel). The inset shows a higher magnification of the boxed area. (C) The fluorescence intensity of FIGL-1 staining in a set area in the mitotic (blue) and meiotic (red) zone of multiple wild-type, mel- 26
(sb45),
mel-26(
ct61sb4) and
cul-3(RNAi) gonads was quantified as described above (see Materials and Methods) and shown in a bar diagram along with standard deviations. Note that FIGL-1 accumulates in gonads of worms that are defective for CUL-3MEL-26 function, and its expression extends into the meiotic zone.