Developmental genetics Flashcards
(26 cards)
Evo-devo
The study of genetics, evolution and development
What are the different cell fate
Stem cells
- muscle cells
- blood cells
- nerve cells
- cardiac cells
- liver cells
- intestinal cells
What is an expression gradient?
- cell differentiation primarily due to changes in gene expression in space and time
- spatial expression
- temporal expression
Maternal effect genes
- lays the groundwork for both the dorsal:ventral and anterior:posterior, transcription factors deposited in the egg
- the phenotype of an organism is determined by the genotype of the mother, irrespective of its own genotype
- often due to the mother supplying mRNA or proteins to the egg
GAP genes-A-P cardinal genes
- each gap gene organizes the formation of a localized set of segments
- is regulated by BCD and HB-M (these proteins act as transcription factors of these genes)
Homeotic genes
- encode transcription factors called homeodomain proteins
- activate genes that produce the morphological characteristics of each segment through cell-cell signaling pathways
Homeodomain proteins
Interact with regulatory elements of other genes that is unique to each segment (to give unique identity to that segment)
Hox genes
- similar sets of homeobox genes are fund in mouse and human
- one HOM-C cluster in insects; 4 HOX clusters in mammals
- these gense are expressed in the same segmental fashion (right-left within hte cluseter defines gene expression within the developing embryo from posterior to anterior regions)
Homologs
Where two or more species have a genetic common ancestor
Paralogs
Similar genes between two species evolved through gene duplication, and have differnt funcitons in the two species
Orthologs
Genes that were derived from a common ancestor between two species, and have the same function in the two species
What are the main players?
- bicoid (BCD)
- nanos (NOS)
- hunchback (HB-M)
- caudal
What is bicoid?
- the mRNA from the mother attaches to microtubules that are localized to the anterior end of the embryo
- these mRNAs function as transcription actors or translation repressors
- creats a protein gradien from A to P
- as protein concentrations increase (artificially) at the anterior end, the cephalic furrow and the head structure move toward the posterior end
- mRNA acts as a transcription factor
- in BCD mutant mothers, the head and thoracic structures are converted to the abdomen resulting in an ambryo with only posterior structures
What is nanos?
- mRNA is localized to the posterior region of the embryo by binding to the opposite ends of microtubules as bicoid
- NOS acts as a translation repressor
- this mRNA established as P to A protein concentration gradient
What is hunchback?
- mRNA is evenly distributed
- translation of mRNA is repressed bu NOS and therefore, the least amount of HB-M protein is found in the posterior regions and increase gradually toward the anterior regions
What is caudal?
- mRNA that is evenly distributed
- translation of mRNA is repressed by BCD adn therefore the least amount of caudal protein is found in the anterior regions and increases gradually toward the posterior regions
What is zygotic hunchack (HB-Z)
- first expressed gap gene
- anterior localized transcription factor
- activated by high BCD*
What is kruppel (KR)
- secondary gap gene (becuase it is regulated by maternal effect proteins and other gap genes)
- repressed by high levels of BCD and HB-Z *
- activated by low levels of BCD and HB-Z *
What is knirps (kni)
- repressed by any BCD *
- activated by low levels of HB-M *
What types of genes that Gap genes turn on?
- genes that specify correct segment number
- assign identity to each segment
Strategies for studying developing gene expression
- CRISPR-Cas9 with HDR (replace gene)
- RNAi or CRISPRi (knockdown gene)
- targeted degradation
- aberrant expression
What do class A genes encode for?
Sepal
What do classes A and B genes encode for?
Petal
What do classes B and C genes encode for?
Stamen
