Figure 2.

Deletion of the 62 bp region from the let-7::gfp transcriptional reporter causes precocious and sustained GFP expression in transgenic lines. (A,F,K) N ≥ 30 animals for each stage. (A) GFP is expressed precociously in the seam cells of animals where the 62 bp element has been deleted from the reporter construct (Δhbl-1::gfp). (B) GFP image of an L1 let-7::gfp animal showing that there is no GFP expression in the seam cells. (C) Nomarski DIC image showing the stage of the animal in (B). (D) GFP image of an L1 Δhbl-1::gfp animal showing expression in the seam cells, as indicated by arrows. (E) Nomarski DIC image showing the stage of the animal in (D). (F) GFP is expressed precociously in the VPCs of Δhbl-1::gfp animals. (G) GFP image of an L2 let-7::gfp animal showing that there is no GFP expression in the VPCs. (H) Nomarski DIC image showing the stage of the animal in (G). (I) GFP image of an L2 Δhbl-1::gfp animal showing expression in the VPCs, as indicated by arrows. (J) Nomarski DIC image showing the stage of the animal in (I). (K) GFP expression persists in later larval stages in Δhbl-1::gfp animals. (L) GFP image of an mL3 let-7::gfp animal showing no GFP expression in the hyp7, indicated by brackets, while there is expression in the seam cells, indicated by asterisks. (M) Nomarski DIC image showing the stage of the animal in (L). (N) GFP and Nomarski DIC images of an mL3 Δhbl-1::gfp animal showing expression in the hyp7, as indicated by brackets. Asterisks indicate seam cells. Lack of GFP expression in all of the seam cells may be due to mosaicism in the transgenic line. (O) Nomarski DIC image showing the stage of the animal in (N). Scale bars all represent 20 microns. Anterior is left and dorsal is top on all images.