Development and diversity Flashcards
Describe biochemistry
the study of material with some biological activity that has been extracted from a living tissue
Describe some biochemical techniques
- fractionation
- repeated assay
Describe Bmps
- Bone Morphogenetic Proteins
- intercellular signalling proteins
Describe FGF’s
- Fibroblast Growth Factor
- intercellular signalling protein
How are inbred mutation lines created?
- male eats food with mutagen
- developing sperm have different mutations
- cross with WT females
- offspring have different mutations
- outcross offspring separately
What can inbred mutation lines be used for
examination of homozygous embryos for adults for developmental defects
Most of the genes identified in the mutant screens were involved in two sorts of activity…
- Control of transcription (TFs)
- Intercellular communication (signaling)
What is the developmental gene toolkit
- genes in an organism’s genome whose products control development
- evolved before the Cambrian
- ancestral trait of most animals
Describe some conserved genes of the gene toolkit
- Hox
- MyoD
- FGF
- Wnt
- Bmp
Describe sponge development
fewer genes in the toolkit
Describe Wnt in AP axis development
signal localisation
Wnt signalling works by
- controlling nuclear import β- catenin
- specification of endoderm and mesoderm
- early role in axis patterning
DV axis specification by Bmp is ancestral to the
Bilateria
Describe the Hox genes
- a conserved mechanism for AP cell identity
- cluster(s) of homologous genes
- encode TFs that bind DNA through the Homeodomain
- expressed in subdomains along the AP axis
- colinear
Homeodomain
DNA binding domain
Discuss colinearity
order of genes in cluster is same
as order of expression along axis
Where can Hox genes be traced to?
common ancestor of the Cnidaria and Bilaterian animals
Describe tandem duplication
- creates linked copies of a gene
Describe the Hox cluster in early vertebrate evolution
- duplicated to give 4 clusters on different chromosomes
- whole genome duplication
Describe the effects of sequence differences in the DNA binding domain
two proteins may bind to different DNA sequences
Describe neofunctionalisation in Hox
- new developmental functions by changes in expression
- ancestral role in AP development
- new role in limb development
How do changes in gene expression evolve?
new TF-enhancer interactions generate new expression domains
Describe some possible TF-enhancer interactions
- new TF evolves to recognise new DNA sequence
- enhancer sequence evolves such that another TF can bind it
- enhancer sequence evolves so binding of TF lost
