Figure 5

In situ hybridisation mapping of mex-3 mRNA distribution in early embryos of Romanomermis culicivorax . We used the R. culicivorax mex-3 gene to prove application of the in situ technique in this species and investigated the segregation patterns of segregation of this maternal RNA in early development. The R. culicivorax mex-3 expression pattern is similar to that of C. elegans[83]. R. culicivorax embryos contain dark pigment granules that are asymmetrically segregated in development. (A) At the 2-cell stage, maternal mex-3 mRNA is detected in the S1 blastomere. The cytoplasmic pigment granules are predominantly in the P1 blastomere. (B) At the 4-cell stage, mex-3 mRNA is detected in daughters of the anterior S1 cell. Cytoplasmic pigment granules are predominantly in the S2 blastomere. (C) At a later stage (>20 cells), mex-3 mRNA is absent. The pigment granules are found in descendants of S2 (S2d). (D) During early morphogenesis, the pigment granules are found in S2 descendants forming hypodermis, (S2d, hyp). (A-C) fixed embryos; (D) live embryo. Scale bar 10 μm. Orientation: anterior left.