Figure 4.

Expression pattern of the F-box gene during embryogenesis of the beetle T. castaneum. (a) F-box gene TC_04309 is initially expressed in the germ rudiment at the rims of the invaginating mesoderm, a position where activated Map-kinase is also seen [76]. Expression is strongest in the posterior (white arrow) and weakens towards the anterior. Ventral view, anterior is up posterior points down. Hl, head lobes. (b) Expression is seen as spots in the thoracic legs (arrowhead), at the base of the labral head appendages (small arrow head) and in segmentally repeated spots in the lateral body wall. T3, thoracic segment 3. Only the anterior half of the embryo is shown. (c) At a similar stage as shown in (b) where all body segments are present, the F-box gene is expressed in the anlagen of the hindgut (arrow). (d) When the legs have grown longer, F-box gene expression is extended covering the distal end. As seen in (c, d), expression in the labrum, in the hindgut-primordium and weakly at the lateral sites of the abdominal segments persists. (e) The hindgut has invaginated and grows out, forming a tube where the F-box gene is expressed in its posterior, proximal end around the future posterior gut opening (arrow). (f) At the retracted germ band stage, F-box is expressed around the anterior gut opening (white arrow) that has formed between the head lobes. (g) In the same embryo shown in (f), F-box gene expression is seen in the walls of the hindgut (arrow).