L7 Neural development and regeneration

Question 1

CNS

Answer 1

brain, brainstem, spinal cord, eye

CNS controls higher order thoughts, integrates and mounts co-ordinated responses to environmental signals

Question 2

Neuron

Answer 2

Nerve cell

define information flow: dendrite (input), soma (integration), axon (action potential - output), synapse (connection)

Question 3

Neural circuit

Answer 3

function of each neuron depends entirely on its connections i.e. neural circuitry, which can be depicted in different ways

Question 4

neurodevelopmental disorders

Answer 4

see onenote

genetic disorder that affect the normal central nervous system

some genes are important in the proper generation of neurons, specific regions/neural types or neural circuits

depends on stage of neurogenesis and whether the gene function is confined to a particular part of the CNS

Question 5

neurodevelopmental vs neurodegenerative

Answer 5

genetic disorder that affect the normal central nervous system

term indicates when the phenotype occurs during development or is only observed later in life
- gives us a hint to the function of the affected gene(s)

Question 6

Proliferation, fate, migration, terminal differentiation

Answer 6

see onenote

Question 7

Retina as neural development model

Answer 7

see onenote

Question 8

Multipotency

Answer 8

see onenote

Cells can generate multiple types

fate specification: which fate genes tell these progenitors what neuron type to make?

Question 9

Gene networks

Answer 9

see onenote slides

What combination in what sequence makes what neuron?

combine transgenes to watch gene expression with live imaging

cannot be examined in species where we have to rely on post-mortem analysis of fixed non-living tissue/cells

Question 10

Lineage experiments

Answer 10

see onenote slides

Lineage describes gene networks in each progenitor over time - allows us to determine combination and sequence of genes

Lineage experiment: examine temporal sequence of gene expression in progenitors, does each progenitor only turn on 1 fate gene?

Anthonal 5 to make photoreceptor and ganglion cells

Visual homeobox genes 1 and 2 to make bipolar cells

Pancreas TF 1 a to make horizontal amacrine cells?

live imagine revealed more complex and very stereotypical gene interactions within progenitors refuting the one gene one fate theory

Question 11

Gene loss of function

Answer 11

see onenote slides

Necessity of a gene (reverse genetics): mutant or morphant

Question 12

Gene loss of function - Assessing cell death

Answer 12

Activated caspase 3 staining labels apoptopic cells, key converging factor that triggers DNA fragmentation

Terminal dUTP nick-end labelling (TUNEL) marks DNA breaks (fragmentation)

Question 13

Combine transgenesis to mark all cells that activate the promoter with MO knockdown

Answer 13

see onenote

can visualise what happens to cells that turned on the promoter but unable to generate the resulting protein

Question 14

Assess fate of wrongly located cells using neuron type markers

Answer 14

see onenote slides

transgenes or immunostaining with antibodies against proteins

Question 15

Gene gain of function

Answer 15

see onenote slides

Sufficiency of a gene (reverse genetics): GAL4/UAS

Question 16

Cell autonomy

Answer 16

see onenote

genes can function within a given cell (autonomous) or influence surrounding cells (non-autonomous e.g. secreted factor)

embryo transplantation studies to generate chimeras

Question 17

Studying neural development

Answer 17

see onenote

Wt cells transplanted into WT or morpholino

Do they grow like normal WT or are they influenced by their surroundings?
E.g. if any of a cell type is missing, the body will make more of those - responding to the surroundings, how the brain makes the right sub-types in the right proportions

Question 18

Cell cycle and proliferation

Answer 18

see onenote slides

DNA replication inhibitor geminin shows phase specific expression - fusion to transgenes allows us to visualise this

labelling DNA histones shows DNA localisation and shape and identifies mitosis

DNA replication factor cdt1 shows differential phase dependent expression to geminin

specific proteins expressed at distinct phases and can be stained for immunihistochemically

Question 19

Spinal cord regeneration

Answer 19

see onenote slides

Mode: Spinal cord - role of fibroblast growth factor (Fgf)
Relevance: Human astrocyte culture

Fgf has multiple roles:
1. proliferation (first 6 days)
2. glia bridge formation (3 weeks)
Distinguished by timing using inducible heat shock

Fgf increases proliferation, supports “bridge” morphology