Expression in procephalic neuroblasts stage 9-11: tritocerebrum - d1-8, v1-5 (all); deuterocerebrum - v2, v4
is expressed in a stripe in the midgut and its expression is restricted to the midgut epithelium and is not detectable in the visceral mesoderm. lab
expression coextends with Ubx
expression in the adhering mesodermal cell layer. In late stage 12, a gradient of nuclear lab
protein forms with the highest protein levels at the posterior end of the domain in parasegment 8. lab
expression is abolished in the midgut epithelium of Ubx
mutants. It extends anteriorly in a Pc
mutant and posteriorly in an abd-A
mutant showing that Ubx
expression is sufficient to induce lab
expression in the adhering midgut epithelium. The overall level, the protein gradient and the nuclear localization of lab
protein are decreased in wg
Nuclear localization of lab
protein in the endoderm first becomes detectable in late embryonic stage 12.
protein accumulates in the outer layer of the endoderm which underlies parasegment 7 of the visceral mesoderm (where dpp
protein is expressed). When dpp
is ectopically expressed in the anterior visceral mesoderm as a consequence of ectopic Ubx expression, the labial domain is extended anteriorly to include most of the anterior endoderm underlying the visceral mesoderm.
protein expression during embryogenesis is restricted to ectodermal and endodermal derivatives. lab
protein is first detected at stage 9 of embryogenesis, in the posterior and anterior midgut primordia, and in the ventral and lateral regions of the procephalic lobe. At stage 12, expression is detected in a discrete section of the midgut, and in the dorsal ridge. The cells in the procephalic lobe expressing lab
protein begin to differentiate into epidermal and neural populations at stage 12. The complex pattern of lab
expression in the head region as it undergoes the complex process of head involution is described. lab
expression is also detected in progenitor sensory cells of the clypeolabrum, thoracic segments, and the tail region.