Developmental Defects in Brain Segmentation
Caused by Mutations of the Homeobox Genes
orthodentical and empty spiracles
Frank Hirth1, Stavros Therianos1,
Thomas Loop1, Walter J. Gehring2,
Heinrich Reichert1 and Katsuo Furukubo-Tokunaga
1Laboratory of Neurobiology, Institute of
Zoology, University of Basel, CH-4051 Basel, Switzerland
2Department of Cell Biology, Biocenter,
University of Basel, CH4056 Basel, Switzerland
Originially published in: Hirth, et al., 1995, Neuron, 15, 769-778
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We have studied the roles of the homeobox genes orthodenticle (otd)
and empty spiracles (ems) in embryonic brain development of Drosophila.
The embryonic brain is composed of three segmental neuromeres. The otd
gene is expressed predominantly in the anterior neuromere; expression of
ems is restricted to the two posterior neuromeres. Mutation of
otd eliminates the first (protocerebral) brain neuromere. Mutation
of ems eliminates the second (deutocerebral) and third (tritocerebral)
neuromeres. otd is also necessary for development of the dorsal
protocerebrum of the adult brain. We conclude that these homeobox genes
are required for the development of specific brain segments in Drosphila,
and that the regionalized expression of their homologs in vertrebrate brains
suggests an evolutionary conserved program for brain development.
Expression of Engrailed in the Embryonic Brain
Expression of orthodentical in the Embryonic Brain.
Expression of ems in the Embryonic Brain.
The Embryonic Brain in otd Mutants.
The Embryonic Brain in ems Mutants.
Summary of the Segmental Organizytion of the Embryonic Drosophila Brain