W11L3 evolutionary developmental biology

Question 1

Some drosophila developmental mutants

Answer 1

-mutant bithorax (halteres develop as wing)
-mutant antennapedia (leg develop instead of antennae)

Question 2

What is bicoid

Answer 2

-a homeodomain type transcription factor that is materially inherited as mRNA at the anterior end

Question 3

Role of bicoid

Answer 3

-create a protein gradient in the AP axis
-Bicoid TF regulates expression of a gene ‘Hunchback’ (another TF)
-Multiple cis-regulatory sites are required for full expression of hunchback.

Question 4

Even skipped (eve) regulation

Answer 4

• have an regulatory module for enhancer, consist of multiple binding site
• this control the expression of eve stripe at the location, help shape the segment boundary

Question 5

The role of transcription factor in early development

Answer 5

• Early development genes contain cis-acting regulatory elements
• Their binding ability to transcription factors depending on gradient concentrations
• Some TFs repress expression, some promote expression
• This enables these ‘segmentation’ genes to be expressed in discrete regions

Question 6

Hox genes

Answer 6

-hox gene regulated the identity of body part, conserved in many animal
-arrange in the way they are expressed in the AP axis
-The eight Hox proteins share a similar (180 bp) sequence. This suggests tandem duplications were involved with the origin of Hox genes

Question 7

The hox gene paradox

Answer 7

-how does Hox gene that are extremely similar in sequence able to produce different animal bodies

Question 8

explaination for hox gene paradox

Answer 8

-Coding divergence, gene duplication and downstream genes changes explain some of the variance
-change to gene and protein regulation mechanism have also been important

Question 9

Hox gene in mouse

Answer 9

• The mouse genome contains 39 Hox genes
• Four Hox clusters arose through duplication in an ancestor

Question 10

The effects of RNA processing on Hox gene expression

Answer 10

-differential translational efficiency of Hox mRNA
-Different hox protein is form (isoform)
-differential miRNA regulation

Question 11

Why Co-option is a major mechanism in EvoDevo

Answer 11

Rather than build completely new genetic pathways from scratch, it is often “easier” for organisms to reuse existing systems in a new context

Question 12

what is pannier

Answer 12

Pannier: a transcription factor that plays a role in dorsal cell fate during embryogenesis

Question 13

Pannier intron and color variant

Answer 13

-Repeated inversions within a pannier intron drive diversification of intraspecific colour paIerns of ladybird beetles
-this lead to change in the location the gene is expressed at
-inversion may create new cis regulatory

Question 14

mRNA splicing produces sex-specific dsx transcripts

Answer 14

Exon 1,2 and 3 code for transformer
-if there is the the 5th exon , create male
-if there is a fourth exon, create female

Question 15

Papilio polytes characteristic

Answer 15

• Papilio polytes : with and without wing ‘tails’
• Female and males can look similar in some forms
• Other females are Batesian mimics – and resemble distantly related species

Question 16

doublesex: mRNA splicing and protein evolution

Answer 16

-specific isoform were expressed in developing wings of female papilio
-Extensive levels of protein coding changes were observed between all mimetic forms

Question 17

Co-option of sex determination gene doublesex(gene for sex determination) for mimicry

Answer 17

-diverse female mimicry have a single locus containing doublesex linked with all phenotype
-doublesex splice variation linked with phenotype
-causing protein coding change linked with phenotype

Question 18

EvoDevo – can we apply the knowledge for beneficial application?

Answer 18

• CRSPR-Cas9 gene drive targeting doublesex cause complete population suppression in caged mosquitoes
  XX doublesex mutants
• develop with male characters
• cannot take blood meal
• cannot obtain energy
• cannot produce eggs

Question 19

cis-regulatory vs. protein coding mutations

Answer 19

-Protein mutations in pigment transporters of island flycatchers cause striking phenotypic differences
-but regulatory mutations in bumblebee also cause striking phenotypic differences

Question 20

why does mutation in cis regulatory region of gene are more likely to underlie most phenotypic evolution

Answer 20

-due to current understanding of gene regulation network, gene structure and fuction
-conservation in developmental gene (hard to mutate due to constrain)

Question 21

Why are protein coding mutations
more common in the literature

Answer 21

-Parallel evolution among different species has helped identify protein coding variation
-all cause but polymorphic variation in the same gene, MC1R

Question 22

The role of transposable elements in evolutionary developmental biology

Answer 22

• TEs can move to new positions within the same chromosome, or different chromosomes
• Originally identified in maize by Barbara McClintock
• Several classes: retrotransposons (copy and paste), DNA transposons (cut and paste)

Question 23

pepper moth and TE

Answer 23

-TE insertion into the gene cortex causes melanism
-certain haplotype are only found in light/ dark moth
-During development cortex expression is higher in the dark carbonaria form than the light typica form

Question 24

Cortex in other orgaism

Answer 24

-cortex modifies wing phenotypes in many butterflies and moths.
-Expression during development determines colour and cell morphology