L13 Drosophilia, patterning the embryo Flashcards
Describe the gradient of nuclear localisation of the Dorsal protein
High on Ventral side
Low on Dorsal side
What does the promoters of important Dorsoventral genes require?
They require different levels of Dorsal protein to be activated
What is the snail gene?
The snail gene in Drosophila melanogaster is involved in the development of the mesoderm during embryogenesis
How is the snail expression activated?
Snail expression is activated by high concentrations of the Dorsal protein in the nuclei of ventral cells
Do snail genes have a low or high affinity for Dorsal binding sites?
They have a low affinity therefore only expressed when a high level of nuclear Dorsal is present
What is a promoter?
A promoter is a control region in the DNA that controls expression of a gene and it promotes transcription
What signal is expressed when low levels of nuclear dorsal is present?
Rhomboid is expressed
What is the Rhomboid gene?
Plays a crucial role in epidermal growth factor receptor (EGFR) signalling pathway in Drosophila.
It makes Neuroectoderm
The antero/posterior gradients of Bicoid and Nanos activates transcription factors called?
It leads to activation of a number of genes encoding transcription factors which are known as GAP genes
What are gap genes’ functions as transcription factors?
Gap genes encode transcription factors, which are proteins that regulate the expression of other genes
They control the expression of subsequent sets of genes involved in segmentation, particularly the pair-rule genes
The nuclear gradient of dorsal lead to expression of different genes along the D/V axis, how does this work?
This works because the different genes have different “activation thresholds”.
What is the striped pair rule expression?
During Drosophila embryogenesis, the embryo is divided into segments.
Pair-rule genes are a crucial class of genes that contribute to this segmentation process.
What does Decapentaplegic (Dpp) do in the dorsal ectoderm?
In the dorsal ectoderm, Decapentaplegic (Dpp), sets up a second signaling center on the dorsal side of the embryo.
This dpp signal is conserved in VERTEBRATES, where it is known as the?
Bone Morphogenetic Protein (BMP) signal.
What is responsible for striped pair- rule expression?
Gap genes.
What is para segments?
Pair-Rule Gene expression stripes are slightly shifted relative to the visible segments.
The Pair Rule gene expression expression stripes are known as PARA SEGMENTS
What specifies the identity of a gene?
The homeotic selector genes … (HOX genes)
What do homeotic mutations do ?
One structure is replaced with another
In most organisms where are Hox genes present?
They are present in a single complex: The Hox Complex (in Drosophila it’s broken into 2 pieces, we have 4)
What leads to the formation of 14 stripes?
High level of Eve and Ftz drive expression of a transcription factor ..this leads to formation of 14 stripes, one in each segment.
What do the segmentation genes do?
The SEGMENTATION genes elaborate the pair rule pattern into a segmental pattern
In addition to the transcriptional regulator Engrailed (En) , what are the two highly important signaling proteins expressed in adjacent cells?
Wingless (Wg), and Hedgehog (Hh)
What are wingless and hedgehog?
They are protein signals that act across cell boundaries.
What are hox genes?
The hox genes are interesting because they are highly conserved and present in most if not all multicellular organism, and can also there lead to such odd transformations when they are misregulated.
What is the bithorax complex responsible for?
The bithorax complex is responsible for diversification of the posterior segments
