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Analysis of the regulatory capacity of the pufferfish HoxDa 5' gene desert

ContributorsBelahbib, Julien
Master program titleTravail de maîtrise universitaire en Biologie, orientation Génétique développement et évolution
Defense date2013
Abstract

The Hox genes are of high importance for the construction of the body plan and the development of the limbs. Regulation of where and when these genes are activated is of key importance and the regulatory sequences implicated in this system can help better understand the evolutionary processes which lead to the variety of forms displayed by animals. In this thesis, I focus on the role played by HoxD genes in digital development. The gene desert located on the 5' end of the HoxD cluster is known to contain enhancers for digital enhancers in mouse. They are implicated in the coordination and expression patterns of HoxD genes in presumptive digits. This gene desert is conserved throughout evolution; we investigated the fish homologous counterpart of this gene desert to see if it also was involved in patterning the appendages. To this end we identified the mouse gene desert counterpart in pufferfish genome because of its reduced size. We divided it into 15 sequences each attached to a ß-globine minimal promoter and a GFP reporter gene. These constructs were then injected in to Danio rerio embryos at the one cell stage and screened 24 and 48 hours post-fertilization. Our findings show that no reporter activity was detected in the fins but that the enhancers in the gene desert display strong neuronal activity. Although BAC transgenic experiments suggest that the relevant fin enhancers are indeed located in the 5' gene desert, we have not succeeded in identifying their exact locations. This may be due to the incompleteness of the screen or technical limitations on the strategy. Conservation analysis of the 5' gene desert amongst various teleosts surprisingly shows that this region is more conserved than non-coding sequences located within the HoxD cluster itself. However, many of these conserved fragments did not give significant reporter activity in our transgenesis assay, questions regarding the reasons for their extreme conservation can be raised.

eng
Keywords
  • HOX
  • Centromeric gene desert
Citation (ISO format)
BELAHBIB, Julien. Analysis of the regulatory capacity of the pufferfish HoxDa 5′ gene desert. 2013.
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Master thesis
accessLevelRestricted
Identifiers
  • PID : unige:34558
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