REP - L4 - Breaking up symmetry Flashcards
What kind of symmetry do most animals have?
Bilateral.
What are Bilateria?
Bilaterally symmetrical animals
What does bilateral mean?
Having 2 sides?
What do all bilateria have?
Defined dorsal-ventral and anterior-posterior axes.
What is cephalisation?
Centralization of neural and sensory organs in the head or anterior region of the body.
In drosophyla how are anterior-posterior axes determined?
Maternal effect genes.
What’s the point of maternal effect genes?
By-passing transcription - translation into protein can happen straight away.
Where in the egg is the RNA including the maternal effect genes deposited?
Nurse cell and oocyte.
What genes are responsible for promoting anterior development?
Bicoid and hunchback.
What genes are responsible for promoting posterior development?
Caudal and Nanos.
How do cells that that receive different concentrations of a morphogen from eachother respond?
Differently.
What does AVE stand for?
Anterior visceral Endoderm.
What does the anterior visceral endoderm do?
Expresses transcription factors that induce expression of genes (signalling molecules) that tell adjacent tissues to become anterior.
What difference is there between the anterior-posterior axis development of the drosophyla and the mouse?
In the drosophyla the anterior posterior axis is established before fertilisation whereas in the mouse it is established long after.
Where is the Dorsal protein located in the drosophyla embryo?
Nucleus of ventral region.
Why can’t we just look at where the RNA is found when studying body axis genes?
Because the protein location is more important for activity.
What are snail and twist?
Transcription factors -
Put simply what does dorsol do?
- Activates Snail and Twist in ventral region.
- Activates dpp in dorsal region.
What do you get in the absence of dorsal gene?
All dorsal, no ventral.
What is ß-catenin?
Gene that codes for a protein that is used for adhering cells.
In the xenapus model what do maternal genes do?
Determine D-V Axis.
What are some difference between drosophyla and xenopus in regards to dorsal-ventral axis development?
- In drosophyla DV-axis established after 14 cell divisions - established upon fertilisation in xenopus.
- In drosophyla Maternal effect gene throughout embryo - restricted in xenopus.
- In drosophyla regulated by transcription factors - transcription factors and enzymes in xenopus.
- In drosophyla dorsal moves into nucleus on ventral side only - whereas it moves into nucleus on dorsal side in xenopus.
