Developmental Biology III




January 27, 2012

Organ specification


Halder G, Callaerts P , Gehring WJ
Induction of ectopic eyes by targetted expression of the eyeless gene of Drosophila.
Science 267: 1788-1792, 1995

Before you read this paper

The animal eye, a photosensitive organ, shows a wide diversity in morphological complexity, ranging from a simple cluster of photoreceptor cells to a complex image-forming "camera eye". One of the long and significant problems in the evolution of the eye originated from the fact that the image-forming eye develops in many times into a wide variety of taxa.

In this paper, the authors showed that the targeted expression of eyeless gene in some imaginal primordia of the fruit fly can induce ectopic eyes on the wings, legs, and on the antennae. The induction of ectopic eye is also observed by expression of mouse gene homologue, Small eye. They proposed that this eyeless gene homologue is a master control gene for eye morphogenesis commonly used throughout the metazoa.

In this class, we will discuss on the character of a "master control gene" in development (its definition and function), imaging the experiment for finding such gene(s) in other developmental processes. I will introduce a historically famous phenomenon called "transdetermination" in relation to this topics.