Axon Navigation
What 2 components are growth cones made up of?
Actin bundles and microtubules.
What are the 2 main types of MAPs we discussed and which direction do they travel in?
Kinesin travels towards the plus end, dynein travels towards the minus ends.
What is a good way to assay cargo transport over a specific amount of time.
Kymographs
What city is Dr. T from?
Melton Mowbray.
In actin filaments, what is the difference between the positive and negative ends?
Plus end is for polymerization, minus end is for depolymerization.
Why would an axon need to participate in local translation?
When a rapid, localized response is necessary.
Ex: response to injury, synaptic plasticity or maintenance, or guidance cues for migration.
Why is it important for to know why different types of neurons may grow better on different substrates?
What does Taxol do to microtubules?
It stabilizes MT's, preventing their depolymerization and promoting their growth.
If an axon is a pioneer, what kind/amount of filopodia would you expect it to have?
Abundant, expansive filopodia.
Name the 2 adaptor proteins involved in mitochondrial transport and describe their function.
Miro binds to the mitochondria, Milton binds to the kinesin.
What would the slope of a line on a kymograph reveal about cargo transport?
Directionality and velocity of transport.
How tall is Dr. T?
3 apples tall.
Fas2
List the different types of cargo and whether they participate in fast or slow transport.
Fast: synaptic vesicles, organelles (mitochondria), endosomes, mRNA granules.
Slow: cytoskeletal proteins (neurofilaments, tubulin).
What would LAMP1-EGFP allow researchers to vizualize?
It would allow them to monitor the pathway the cargo is taking along a neuron.
What are pioneer axons and why are they important?
They are the first axons to emerge and navigate to a a target. They are important because other neurons use them as guidance cues so they know where to migrate.
What is the difference between SAMs and CAMs and what function do they serve when bound together?
SAMs bind to the ECM but not the cell and CAMs bind to cell membranes. When they are bound together, they can form a transmembrane unit that allows for recognition of intracellular components.
Describe the different processes of Rab GTPase mediated transport vs. Non-Rab mediated transport.
Rab mediated: cargo attachment via adaptor molecules binding to the kinesin motor complex, direct binding of Rab to motor complex, directional movement of the kinesin down the MT's guided by Rab, or regulating the kinesin by turning it on or off so it can reach the specific location.
Non-Rab mediated: Mitochondrial transport- a complex forms with mitochondria, motor protein, Miro, and Milton that can move the mitochondria along the MT's in response to calcium signals.
How can DRG be used to study axon guidance molecules? Be specific, include all experimental groups.
DRG explants can be taken from specific time points and co-cultured with a specific tissue to see how the axons grow out. If axons grow toward the tissue, the signal it is secreting is attractive. If axons grow away from the tissue, it is secreting a repulsive signal. Under control conditions, the axons would grow out in all directions.
What are the names of Dr. T's chihuahuas?
(Nicknames and legal names accepted)
Poo-poo, Roids, and Fresh