Skip to content
Login Register

#anterior-posterior patterning

2 public questions tagged with this topic.

Morphogen Induction-l

Which one of the following morphogens is involved in anterior-posterior patterning in Drosophila?

Anterior-posterior axis in Drosophila is initially established by maternally localized mRNAs along oocyte cortex. Bicoid transcript anchored anteriorly by cytoskeletal proteins, Nanos posteriorly, creates opposing gradients determining polarity. Bicoid protein diffuses posteriorly forming concentration gradient that activates gap genes hunchback and orthodenticle in threshold-dependent manner specifying head and thorax, while repressing caudal translation posteriorly refining pattern. Notch signaling mediates later segmentation boundary sharpening and neuroectoderm decisions but does not provi

Ref: St Johnston and Nusslein-Volhard, Development 1992, Bicoid Establishes Drosophila AP Polarity.

View Details
Limb Development -l

Which structure provides signaling for anterior-posterior patterning in limb buds?

Anterior-posterior patterning that orders thumb to little-finger identity is governed by posterior distal mesenchyme termed zone of polarizing activity. ZPA cells secrete Sonic hedgehog, establishing a posterior-to-anterior morphogen gradient decoded through Gli3 processing into activator and repressor forms. High SHH posteriorly maintains Gli activator for digits 5-4, low anterior allows Gli3 repressor for digit 1. Apical ridge drives proximal-distal outgrowth, progress zone regulates timing, but only ZPA transplantation anteriorly produces mirror-image duplication, proving its instructive ro

Ref: Gilbert, Developmental Biology, 12th ed., Chapter 19: Limb patterning – ZPA and SHH in AP axis.

View Details