L14 Drosophila, neurogenesis Flashcards
How is neurons formed in drosophila?
When the mesoderm invaginates to form internal structure of the embryo the neuroectoderm comes to lie ventrally….this will give rise to neurons
Which side is the neural tube situated in vertebrates and drosophila?
Vertebrates - Dorsal
Drosophila - Ventral
What does the BMP and Dpp signal mean?
BMP - Bone morphogenetic protein
Dpp - Decapentaglegic signal
What is BMP/Dpp?
A bone morphogenetic protein (BMP) / decapentaplegic signal (Dpp) signal
Why is the BMP/Dpp signal important?
The BMP/Dpp pathway is fundamental in creating a gradient of signaling activity that specifies dorsal and ventral cell fates in developing embryos
Which BMP/Dpp signaling pathway contributes to vertebrates and flies?
- Bonemorphogenetic protein (BMP) - ventral in vertebrates
- Decapentaplegic signal (Dpp) - dorsal in Drosophila/flies
Do all cells in the fly neuroectoderm become neurons?
Not all cells in the fly neuroectoderm will become neurons some will remain ectodermal
Why are proneural clusters involvement of lateral inhibition important?
This process ensures that only one cell within the cluster becomes a neural precursor. Often mediated by the Notch signalling pathway
Which important patterning mechanism does neurogenesis use?
Lateral inhibition.
For neurogenesis, what do specific pro-neural genes do?
Achaete/scute genes (specific pro-neural genes) set up clusters of equivalent cells which help determine which cells will differentiate into neurons via NOTCH/DELTA pathway
What does the Notch/Delta signalling pathway ensue?
The Notch/Delta signaling pathway ensures selection of a single cell out of the cluster by inhibiting neighbouring cells from adopting the same fate hence why only a single cell differentiates
What does Achaete Scute proteins do?
They can also influence levels of delta expression as well as determining the fate of cells
What is delta?
Delta is a transmembrane ligand
It only can influence neighbouring cells
What is the role of delta?
Delta is a ligand for the Notch receptor meaning it binds to the receptor
What does a strong notch signal do?
They downregulate (reduce) Achaete/Scute.
What is the result of downregulation of Achete/Scute?
As a result the small difference in
Achaete/Scute expression will
become amplified
What activates Neural genes?
High and continuous
achaete/scute, Expression activates Neural genes
What happens after selection of a neuroblast?
- After selection of a Neuroblast, it will generate a number of neuronal and glial cells, in a very stereotypic manner
- Neuroblast itself will drop down from the epithelium into the interior of the embryo
Do all cells in the drosophila epidermis have a polarity?
All cells in the Drosophila epidermis have an inherent polarity:
Apico-Basal polarity
What is the function of the Bazooka/Insc/Pins protein complex?
The Bazooka/Inscuteable (Insc)/Partner of Inscuteable (Pins) protein complex is crucial for establishing and maintaining cell polarity, particularly during asymmetric cell divisions in various organisms, notably Drosophila
Directs the localisation of proteins and certain RNAs on the opposite side of the cell
What does the Bazooka/Insc/Pins complex do in the plane of cell divsion?
The complex also orients the mitotic spindle, which determines the plane of division. This results two cells that are formed differently
What does the stem cell of a neuroblast further develop into?
They undergo further asymmetric division to form a neuroblast or GMC (ganglion mother cell)
How are the sensory organs formed in drosophila?
Drosophila sensory organs develop from a single cell into four. Numb protein determines which cell becomes a sensory neuron. This process differs from embryonic neurogenesis in Numb/Pins localization.
Numb protein - key cell fate determinant
