Figure 1

Hsp23 expression in stage 11 embryos. (A) Detection of Hsp23protein in a lateral [arrow] and midline associated population [brackets]. (B) In situ hybridization for hsp23 mRNA showing distribution identical to that of panel A. (B') High magnification view of the midline region of two abdominal segments showing the relative position of hsp23-positive cells (purple) with regards to the expression of Engrailed (brown). (C) The expression of β-Galactosidase under the control of a 1.8 kb proximal fragment of the hsp23 promoter displays a similar distribution to that shown in panels A and B. (C') Confocal view similar to panel B' showing the co-localization of β-Galactosidase and endogenous Hsp23 in the midline associated cells. (D-G) Confocal high magnification views of a similar region indicated by brackets in A. (D) Co-expression of the neuronal marker Elav (green) and Hsp23 (red). (E) Absence of the midline marker sim-lacZ (green) in Hsp23-positive cells (red). (F and G) Co-localization of hsp23 promoter activity (green) and Ftz (red) in the MP2 neuroblasts both before (F) and after (G) their mitotic division. Ventral views of stage 11 embryos are shown in all panels with the anterior oriented toward the left.