Figure 3. m Impinges on Denticle Formation.

(A) Consequences of alterations of m function and expression on denticle formation. The m¹ mutation leads to morphological alteration of denticles, with a characteristic abnormal triangular shape. A similar phenotype is observed with Df(1)m-MR, a deficiency in which the entire m locus is deleted. Overexpression of m, by crossing the Ptc-Gal4 driver line to EP345-m, does not modify the cuticular phenotype in the corresponding regions (arrowheads). Re-expression of wild-type m products driven by the 0.4Kmin-gal4 transgenic lines, but not 0.4KminKO-Gal4 lines, rescues the characteristic denticles defects of m¹ embryos. All pictures correspond to the A4 segment.

(B) High magnification views of wild-type (wt) and m¹ denticles (fourth rows of A4), as observed in either light (left) or scanning electron microscopy (right). Whereas the absence of m does not affect the denticle height (h), the width (w) is reduced, producing denticles of smaller area that display an abnormal shape lacking the median constriction characteristic of wild-type denticles. See Table S2 for quantification of these defects.