The
cad protein isdistributed in a gradient from the posterior pole up to approximately 50% egglength. The
cad protein gradient is acheived through repression oftranslation of the uniformly distributed
cad transcript in the anterior of theembryo.
The
cad protein isexpressed in a gradient from the posterior tip of the embryo reaching up to 30%egg length.
cad protein is first detected just before the formation of pole cells, and is cytoplasmic. After embryonic cycle 9,
cad protein becomes nuclear. During embryonic cycles 10-13,
cad protein is distributed in an anterior-posterior gradient, and is once again detected in the cytoplasm as well as the nucleus. At gastrulation,
cad protein is detected in a 4-5 cell wide stripe at 13-19% egg length, and in the pole cell nuclei. At germ band extension,
cad protein is detected in the posterior of the germ band and in the hindgut and postrior midgut rudiments. After germ band retraction,
cad protein is detected in posterior epidermal structures such as the anal pads.
The expression of
cadprotein is dynamic during embryogenesis. In early embryos, a posterior toanterior gradient of protein, with highest concentrations in the posterior polecovers up to 90% egg length. As embryogenesis proceeds, the gradient moves moreposteriorly, covering 70-20% egg length. In the late embryo, just prior to germband extension, protein expression coelesces in a posterior ring aprroximately3-4 cells wide which spans between 10% and 15% egg length. Throughoutembryogenesis, protein is detected in the pole cells. During germ bandextension
cad protein is detected at the germ band terminus and in the polecells. Specifically, protein is detected in cells which give rise to the analpads, the posterior midgut and the malpighian tubules.
