Question

In Drosophila oocytes, concentrations of a gene product called nanos are high near the posterior and decline toward the head. nanos might be an example of a:

A. Segment identity gene

B. Homeotic gene

C. Morphogen

D. Pair rule gene

E. Gap gene

Answer 1

Correct option is : C. Morphogen

{ Nanos

Posterior morphogen
- Mutant of nanos has no abdomen (Acron, head, thorax, telson)
- Nanos mRNA is bound to the cytoskeleton
- secured to posterior due to Scaffold and Oskar (docked posterior, scaffold binds)
- At Syncytial blastoderm--> nanos mRNA is translated to protein
- Nanos protein blocks the translation of Hunchback mRNA in posterior portion of embryo
- Nanos protein activates posterior gap genes at cellular blastoderm stage (Knirps and Giant)}