Siamois, Goosecoid, and axis
Axis formation is established very early in the development of vertebrates. Much research has been done in this area, especially with Xenopus, and the consensus is that the dorsal lip plays a key role in establishing the dorsal-ventral and anterior-posterior axes and organizing the develoment of the organism. Pioneering experiments were done by Spemann and Mangold in the 1920's: by transplanting a dorsal lip from one embryo to a point opposite the native dorsal lip on a second embryo, they were able to induce the formation of a second notochord and most of a complete second organism in the manner of a siamese twin. The paper the two published summarized thusly: A piece of the upper blastoporal lip of an amphibian embryo undergoing gastrulation exerts an organizing effect on its environment in such a way that, if transplanted to an ind
ifferent region of another embryo, it causes there the formation of a secondary embryonic anlage. Such a piece can therefore be designated as an organizer. The homeobox gene which is implicated in this activity is known as siamois. A second homeobox gene, goosecoid, was later implicated in the formation of the a-p axis, and both genes are regulated at least indirectly by the $-catenin protein, which is a component of the Wnt signaling pathway. This paper will attempt to explain the relationship among these genes and gene products and summarize the current research in the field. The pathway begins with the accumulation of $-catenin in the dorsal blastomeres, specifically in a region known as the Nieuwkoop center. It then acts as a transcriptional activator with regard to siamois, along with other wnt factors such as frizzled, disheve
Some common words found in the essay are:
Spemann Mangold, Xwnt8 Kessler's, Eng-Gsc VP16, , Goosecoid Gsc, Kessler Yao, dorsal lip, dorsal lip embryo, plays key role, axis formation, xwnt8 kessler's, formation organizer, lip embryo, key role, axial development, plays key, homeobox gene,
Approximate Word count = 568
Approximate Pages = 2 (250 words per page double spaced)
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