Diff15 - 24 Flashcards
Describe the segmentation in drosophila
Obvious - A1-8, T1-3, three head
Define what is meant by long term band insect
All 14 segments defined simultaneously
What is the outcome of long term band development?
Very very quick - 24 hours
What is the benefit of long term band development?
Developed and ready before food source disappears
What is the downside of long term band developmnet?
Complicated - interaction of all genes required for every segment
Characterise a knirps mutant
“Little boy” - creates a gap in the embryo
Characterise a paired mutant
Deletion of even number segments (halving length)
Characterise an odd-paired mutant
Deletion of odd number segments (halving length)
Characterise a goosebury mutant
Covered in spines of naked cuticle
What are the five classes of genes?
Maternal, gap, pair, segment polarity and selector
Name a maternal gene
Bicoid
What is bicoid?
Maternally loaded DNA binding transcriptional activator
Characterise a bicoid mutant
Fine - maternal bicoid covers, but progeny have no head
Outline bicoid segementation
Like accordian, based on dosage (high = pushed more posteriorly)
Outline French flag model
Outline segment polarity
Hh & Wg feedback onto each other to maintain each others expresion and refine segment borders
What creates naked cuticle between segments?
Wg
What is required for Wg?
Hh
What does a loss of Hh create?
Absence of Wg, hairs everyewhere
Outline the role of selector genes
Hox genes - who am I information for each segment
What controls selector genes?
Combination of gap and pair-rule genes
Example of short germ band insect
Strigamia maritime - centipede
Outline strigamia maritime segmentation
Embryonic separation into three main areas - head, trunk, transition, posterior disc. Starts with head, adds abdominal segments sequentially
Draw the strigamia maritime delta-notch feedback oscillator
