Anterior-posterior axis formation in Xenopus laevis
Jansen, H.J.
Citation
Jansen, H. J. (2009, March 25). Anterior-posterior axis formation in Xenopus laevis.
Retrieved from https://hdl.handle.net/1887/13698
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Summary
The research described in this thesis mainly focussed on making and refining a model that describes axial patterning during gastrulation in the frog Xenopus laevis.
The introduction in chapter 1 describes in brief what is known about processes that are important for the research described in this thesis.
Chapter 2 describes that axial information arises in the mesoderm and subsequently in the neurectoderm. Also is shown that this information, under influence of the Spemann organiser and cellular movements, is translated from a time sequence into a space sequence.
The model describing this is refined in chapter 3 where the function, important for axial patterning, of the Spemann organiser is clarified. This function is neural induction.
Embryos without a neural plate do not develop a axial pattern. When a neural plate is induced in these embryos, these embryos can form a axial pattern.
In chapter 4 is described that retinoids, important for axial patterning and formed in the mesoderm, have a patterning effect on neurectoderm. If the function of these retinoids is inhibited by blocking the retinoid recptors with an antagonist, the part of the axis that is normally patterned by retinoids is not formed. An important conclusion in this chapter is that retinoids are candidates for transfer of axial information from mesoderm to neurectoderm and can, in this way, coordinate the expression of axial information between mesoderm and neurectoderm.
The hox genes that are used as axial markers in the previous chapters also play an essential role in the formation of the axis. How they do this is less well studied. In chapter 5 a study is described where the transcriptional targets of Hoxc6 or Antennapedia are investigated.
By doing this in the frog Xenopus laevis and the fruitfly Drosophila melanogaster and compare the results, conclusions can be drawn about the processes that are important for the function of Hoxc6/Antp, because the target genes will be the same. From this study could be concluded that celldivision, cellmigration, and suppresion of head formation are processes that are important for the function of Hoxc6/Antp.
In chapter 6 the most important conclusions from the described research are summarised and discussed in relation to the literature.
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