Fig. 7. Rump regulates posterior localization of nos mRNA. The nos-tub:nos+2 transgene (see Fig. 2D) was introduced into either nos^BN or rump¹ nos^BN/Df(rump) nos^BN Drosophila females and provides the sole source of maternal nos mRNA. (A) Embryos that develop to produce cuticle were binned as follows: seven or eight partial or complete segments (7-8 seg); four, five or six partial or complete segments (4-6 seg); three or fewer segments (0-3 seg). The nos-tub:nos+2 transgene produces embryos with a range of segmentation (nos^-, n=455). When rump is eliminated, segmentation is significantly reduced (nos^- rump^-, n=220, P<0.001). (B,C) Eve-stained embryos were binned according to the number of Eve stripes observed in the presence (n=153) or absence (n=212) of rump (P<0.001). Embryos representative of seven- and four-stripe bins are shown in C. (D,E) Posterior localization of nos-tub:nos+2 RNA was evaluated by in situ hybridization to 0- to 2-hour embryos and classified as substantial (++), weak or diffuse (+), or undetectable (-) as illustrated in E. Localization is significantly reduced by elimination of rump (nos^-, n=382; nos^- rump^-, n=417, P<0.001).