Neuro10 - 22 Flashcards
What are lamella and filopodia?
Structured by different kinds of F-actin
Characterise lamella actin bundles
Crosslinked into a net
Characterise filopodia actin bundles
Polarised to form larger bundles
Outline F-actin activity in resting growth cone
Treadmilling, additions being polyumerised at the furthest tip of the filopodia
What occurs when a growth cone comes into contact with attractive cue?
Treadmilling slows, F-actin accumulates > filopodium stabilises, dragging microtubules into the back of filopodium, establishing a new growth direction
What two components comprise filopdial extension?
Molecular clutch, and actin-tubulin link - pulls microtubules into the wake of extending filopodium
What do like neurons do?
Fasciculate
How do like neurons fasciculate?
Repulsed by each other when they come into contact, leading to growth cone collapse
What are semaphorins?
Family of inhibitory axon guidance cues
What is a permissive substrate?
Growth cones need substrates which are permissive for growth, so obstacles that are not, guide growth direction
What is laminin?
Growth promoting EC protein, localised in the optic nerve
What does laminin NOT indicate?
Direction of growth - only indicates that axons CAN grow there
What is noteworthy of laminin?
Only permissive of axon growth in golden concentration - too little or too much leads to no growth
What can channel axons in mice (non-permissively)?
Sema 3A in embryo limb
What are ephrins?
Factors used in early patterning and to guide axons - non-permissive, contact repulsion factors
