Lecture 8 - Mid-blastula transition Flashcards
What happens during the early stages of oocyte development? [2]
- New proteins are synthesised from maternal mRNAs during cleavage stages
- Very little transcription occursw
What is the mid-blastula transition?
The point where cell cycles start to have G1/G2 phases
What type of genes do animal cells express?
Ectodermic genes
What type of genes do vegetal cells express?
Endodermic genes
How is the mesoderm formed?
Vegetal pole instructs cells from the animal pole to become mesodermic
What are the characteristics of the mesoderm inducers in Xenopus?
- Secreted proteins
- Can induce different types of mesoderm along the D/V axis
What RNA is required for mesoderm induction?
Vg1
What is VegT?
A transcription factor, maternally expressed in the vegetal half of the oocyte
What is the role of maternal VegT?
It induces zygotic expression of Nodal ligands
What kind of signalling leads to the formation of the Dorsal mesoderm?
High nodal singalling
What kind of signalling leads to the formation of the Ventral mesoderm?
Low nodal signalling
What transcription factor complex does Nodal signalling create?
Smad2/3 Smad4 complex
What doe RT-PCR allow us to see?
Specific gene expression (quantitative)
What does inhibiting the Nodal signalling cause?
Loss of the mesoderm in Xenopus embryo
What is the role of Nodal signalling in the endoderm?
Required for some endodermic gene expression
