1. Introduction to patterning

Question 1

What is the role of yolk in egg cells?

Answer 1

Yolk - energy store deposited in oogenesis

Question 2

Wha are maternally deposited factors in egg cells?

Answer 2

Maternally deposited
- RNAs (test by FISH)
- proteins (test by immuno)

They can be localised / distributed in the egg -> used for spatial patterning (ex. A-P axis) / cell differentiation (ex. muscle cells)

Question 3

Explain regulation of gene expression

Answer 3

Structure:
- Proximal control: enhancers (CIS elements), TF binding sites, promoter (RNA pol binding site)

• Distal control: enhancers

High level of complexity - tight gene expression control

Question 4

What are some of the main signalling pathways in development?

Answer 4

• Wnt/ beta-catenin
• Hedgehog
• TGFbeta (Nodal, BMP)
• Delta-Notch
• FGF
• Hippo

Question 5

What was the general trend in Hedgehog pathway evolution?

Answer 5

Hedgehog observed in many different species - some have only components encoded by diff genes of the whole pathway - in evolution assembly of different elements - not de novo arised

Question 6

By what cell mechanisms can spatial patterning be achieved?

Answer 6

Spatial aptterning achieved by:
- Cell lineage
- Cell interaction with other cells in:
short (induction) / long range signalling (morphogen gradient, ..)

Question 7

What factors influence morphogen gradient formation?

Answer 7

Morphogen gradient formation influenced by:
- diffusion
- morphogen decay
- interaction with other morphogens

Question 8

What are the most studied Drosophila genes?

Answer 8

Hox genes - A-P patterning - Hox gene mutations disrupt the normal body plan

Hox genes also in mammals - evolutionary conserved - evolved in chromosome duplication events - common ancestor