Characterization of Lamprey Emx gene: Bridging the Gap from Non-Vertebrate Chordates to Gnathostomes
Loading...
Authors
Tank, Elizabeth M.H.
Issue Date
2003
Type
Thesis
Language
en_US
Keywords
Alternative Title
Abstract
Lampreys possess a unique phylogenetic position between non-vertebrate
chordates and jawed vertebrates (gnathostomes) and thus provide important
insights into the evolutionary transition between these groups. The Emx gene
family plays a major role in the development of the forebrain, a system that
gnathostomes possess and non-vertebrate chordates do not. Three copies of the
Emx gene are seen in gnathostomes. Examination of Emx in lampreys can
therefore shed light on forebrain evolution and gene duplication. An Emx gene
was isolated and cloned from Petromyzon marinus and characterized through
phylogenetic and expression analysis. Phylogenetic analysis concluded that
lamprey Emx is as equally similar to Emxl as to Emx2 in gnathostomes. Emx
transcript was found in lamprey embryos between day 6 and day 19. Initial
expression in embryos was located in the neural tube and somites, an expression
that is not characteristic of Emx in gnathostomes. Yet all other expression
domains including the dorsal telencephalon, olfactory epithelium, otic vesicle,
pronephrus and pharyngeal arches has been observed in gnathostomes. One
Emx gene was isolated, yet it is not certain that only one exists. This suggests
that the function and expression domains of Emx ,were already developed in
lamprey and thus maintained in gnathostomes and the Emx gene duplication
event occurred after the lamprey / gnathostome divergence.
Description
v, 28 p.
Citation
Publisher
Kalamazoo College
License
U.S. copyright laws protect this material. Commercial use or distribution of this material is not permitted without prior written permission of the copyright holder.