L7 - Axis Development Be able to describe the basic process of building…
L7 - Axis Development
- Be able to describe the basic process of building an embryo.
- Define the body axes and sequential gene expression in development.
- Define maternal effect genes & their influence on gene expression inembryos.
- Detail the process of pattern formation in wildtype Drosophila,
particularly the A-P axis genes: bicoid, caudal, hunchback, nanos & D-V axis genes: toll, cactus, dorsal, spätzle.
- Understand morphogen gradients are important in development, & that many are transcription factors.
- Understand the experiments (& outcomes) that highlight the role of bicoid in development.
- Be able to define position of dorsal protein (active & inactive) in D-V axis generation.
- Understand the homeotic selector gene & homeodomain function.
Drosophila - a powerful model in mapping embryology
- Many genes involved in the embryological development of Drosophila have compatriots in human genes. Homology allows extrapolation from drosophila model
- Demonstrates many general principles of development conserved across animals (e.g. morphogen gradients; pattern formation).
- Experimentally very powerful for hypothesis testing (e.g. mutagenesis & transgenics; fully sequenced genome).
Dorso-Ventral Axis formation
- The first signals that guide development are derived from maternal factors (proteins + mRNA) deposited within the oocyte
- Are actually about 50 genes involved in setting up the two axes.
- These gene products set up a framework of positional information (by way of concentration gradients) and enable zygotic gene expression to begin
- Cascade of activation (synergistic and/or sequential) – which becomes increasingly complex as the cascade expands.