Developmental Biology Ligoxygakis 1 Flashcards
1
Q
Breaking symmetry
A
- All cells have same developmental potential
- However end point = differentiation
2
Q
1st step of symmetry breaking
A
- Maternal specification
2. De novo program
3
Q
Drosphilia Origins of polarity
A
- A-P polarity of embryo
- Maternal effect genes
- Cooperation btw nurse and follicle cells
4
Q
Movement of oocyte nucleus
A
- Nucleus moves from central posterior → asymmetrical anterior
- Involves GRK, EGFR
- Gurken mRNA
5
Q
Mutagenesis study
A
- Heidelberg screen
- Maternal
- Zygotic
6
Q
Following fertilisation
A
- Bicoid + hunchback gradients along AP axis
- 3’UTR of nos can be replaced w/ 3’UTR of bcd mRNA
- Nos inhibits translation of hb + bcd mRNA
- BCD gradient
7
Q
Embryo segmentation
A
- Mitosis
- Syncytium
- 13th division, 600 nuclei
8
Q
Gap genes
A
- Mutant screens (3 points)
- Regulated by maternal TF
- Hunchback, Kruppel (7 total)
- Gap proteins = TF, diffuse into syncytial cytoplasm
- Regulate expression of pair-rule genes
9
Q
Pair rule genes
A
- Transcribed in 7 broad strips
- Some genes (even-skipped) are controlled directly by GAP proteins
- Each stripe = gene activation
- Regulatory elements = fused to LacZ reporter
- Each stripe of pair rule protein defines a stripe of segment polarity expression
- Each segment polarity gene is induced by 2 pair rule proteins → 14 segment polarity stripes
- Nucleus → Cytoplasm
- Makes a gradient
10
Q
Segment polarity genes
A
- Overlaps of pair rule gene pattern causes activation of segment polarity
- TF like engrailed
- Mediate cell interactions
11
Q
Body patterning
A
- Segments need to take on individual identities
- ANT-C (head + anterior thorax)
- BX-C (posterior thorax)
- Homeodomain protein, homeobox
- Hox genes
12
Q
Let-23 signalling
A
- Originally ‘graded’ signal model (P6p most, decreases for others)
- But, Let23 only needed in p6p
- Sequential signal model
