Neuro flashcards chapter 3 and 4
pleiotrophy - when one gene inlfuences many different traits, especially when those traits seem unrelated to one another ex. half of all cats with white fur and blue eyes are also deaf
redundancy - when sevral genes contribute to producing a single trait ex. sevral proteins from the dorsal lip of the blastapore organize induction to the neural plate
The process of dividing to produce cells that differentiate into neurons is called neurogenesis. neurogenesis is the process of nonneuronal cells in a germinal zone dividing to produce daughter cells that leave the germinal zone and change into neurons.
production of new glia is called gliogenesis
When we speak of the birthdate of a cell, we are talking about the point in development when this particular cell stopped dividing and began differenti-ating into a particular fate.
The Cortex Develops in an Inside-Out Manner
Adult-born neurons originate in three germinal zones:
(1) the olfactory neuroepithelium - cells that continue to divide to provide new olfactory sensory neurons
(2) the subventricular zone - cells that migrate rostrally to continue to replace interneurons in the adult olfactory bulb
(3) the subgranular zone - first germinal zone for adult born neurons
class notes - jan 21
stem cells - a cell that is unlimited self renewing potential (be able to divide and divide and divide.. and is capible in any fate) and totipotent/pluripotent/multipotent (able to give rise to any cell in that particular organism)
neural stem cell (what we have after neural indiction)- self renewing multipotent cell that gives rise to neurons and glia, line the neural tube and have an extensive capacity for self renewal and this process repeats again and again through a persons lifetime. stem cells divide at the middle of neural tube
cancer cell - divding in unlimited ways
neuroshphere assay
put cells in dish add growth factor and looking for self renewal and then looking for differentiation, multi potency, etc
subventricular zone
lining of neural stem cells surrounding the ventricles in adults
progenitor cell
precursor cell derived from stem cell; migrates and produces either neuron ot gilial cell
produce nondividing cells (neuroblasts and glioblasts)
neuroblast
not yet neutron, no connections, inbetween stem cell and neuron
product of a progenitor cell that rises to different types of neurons
glioblast
in between stem cell and glial
product of progeneitor cell that gives rise to different types of glial cell
fate - cells inevitablility
commited - on the path to fate, but not yet there
how do stem cells know what to become?
transcription factors
chemical signal (transcription factor) turns genes on(gene expression), specific proteins are made (related to cell differentiation) and then specific cells
stages of brain development
cell birth (neurogenesis)
cell migration
cell differentiation
cell maturation ( dendrite and axon growth)
synaptogeneis (formation of synapses)
cell death and synaptic pruning
myleogenesis (forming of myelin)
transcription factors and growth factors act to support growth and differention in developing neurons. brain can more easilt cope w/ injury during this time ( first 5 mths of gestation)
cell migration
begins shortly after first neurons are generated, continues for 6weeks in cortext and hippocampus
damage has more serious consequences
radial glial cell: path making cell that a migrating neuron follows to destination
human brain 6 layers in cortext, mice have 5
we are moslty talking about the M phase of mytosis in this course
ventricular zone - layer up from ventricular surface
subventricular zone - zone above ventricular zone
radioglial cells are multipotent
class notes - jan 23
radial migration - migrating radially inside to outside
tangial migration - migrating around
these two happen in parallel
microglia — these are not of neural origin, they come from the yak sack (gut) they are the first inhabitants of the brain. in rats born on day 7 way earlier than others. create tunnels to allow cells to migrate tangentially. if they do not go to the brain they are called macrophages
SVZ and hippocamapus is where neurogeneis happens in adult brain
neurons born in SVZ go to olfactory bulb and no where else
neurognesis happens by double cortin in ex. 3.17 A page 36
making the cerebellar surface
bergman glia - microglia housed in cerbellum
perkinje - born at 4th ventricular migrate to form a single layer of cells. migrate along bergman glia to form single layer of cells. these release sonic hedgehog and this triggers external granule layer to divide and makke more cells and create internal granule layer
granule cells - external and internal layer. inter layer inlcudes subset of cells with fibers called parallel fibres they go through cerebellum. born at rhombic lip and migrate tangentially to form layer. when they form outter layer they make reelin to stop perkinjie from migrating farther
dendritic arbor
abnormal cerebellum in dancing mice
in weaver mice, no sonice headge hog produced so perkinjie cells normal alignment internal layer of granule cells missing. astrotactin released by weaver cells to help grip and migrate and this is what is missing in those weaver mice
in reeler mouse, has muation in reelin gene, thats why perkinje cells are everywhere which can release shh but not in an organized way. has a worse deficit than weaver mouse.
STW assignment one - stem cell research!
types of stem cells: embryonic stem cells, induced pluripotent stem cells and adult stem cells ( somatic stem cells)
four transcription factors reduce cells to. stem cells - yeminaka figured this out
we can take a little piece of skin and take the cells with a viral approach to turn on trans factors and turn it to a stem cell for that person which includes their DNA.
myths about stem cells
scientists doing stem cell research are doing unethical studies
the first stem cell was taken from a young black women patient who had cancer without their consent and oberved they could self renew. ongoing law suit about this.
they are taken from aborted fetuses
not true. embryotic system cells are cell line orginating from one cell of the blastocyst from IVF that are donated
they are limited in their therapeutic potential
yes they are not a cure-all but also have proven beneficial effects.. bone marrow, heart, eyes
cortext among species
6 layers for humans - seem homogenous, different cell types layered on top of eachother, expansion in the middle layers
PFC expands and matures the longest and expands most through evolution, smaller in something such as money, largest in humans
in humans maturation goes on for 20+ years, why?
has to do w compremise between space and brain size in terms of uterine development. the baby would not be able to come out if the brain sized was enlarged enough during prenatal maturation
human brain weight is way larger to body weight than other mammals
neoteny
rate of maturation/development of an organism is slowed or delayed
allows more cells to be produced
adults retain more brain cells to be produced
evolution across species not within species
can be exposed to enviornmental toxins, teratogens, etc
transgenics in animal models
knockout model - segment of dna either deleted or stop code of particular gene of interest ex. shh. this means that the particular animal doesnt have the gene.
knock in model - put in in the gene to overexpress. the gene ex. humainzed genes into mice
conditional - condition where the gene is expressed or repressed, often cell type specific ex. only express gene in dopamine neurons
induceble - dont do anything, are inerte until you induce the gene. systems where gene can be tuned on by light or other ways, not expressed until it is induced
consitutitive - the transgene is everywhere it is not inducible or condtiional it is expressed in all genes everywhere
they make a dna construct of gene, put in blastocyst, do ivf in mice and look at what babies express this and breed them to keep inheriting the genes
maturation process
ahead of furrow dividing, after maturing r8 first
looking at the fly eye: drosophilla, 700 ish cells within the eyes, 8 receptors in each hexagon, r1 to r8 each one contains 8 photo receptor cells r7 (in middle) is a uv receptor to allow in light. r8 under r7
as we move furrow caudal to rostral where the furrow ends cells are maturated. when furrow is halfway the stuff behind is matured and in front is not
r8 matures first direct app response with delta notch signlaing iduces 2 and 5 and so on, they mature, then 31 and 46 finally 7.
at back of the eye hh is expressed and stops cells from dividing and induced tf of dpp which induces proneural genes
7 has the sevenless receptor for a transcription factor
boss secreted by receptor 8 binds to sevenless recpetor and induces r7 receptor
hedgehog expressed across the furrow (an obersvation of bump or fold moving across the eye when cells divide or move, not doing anthing its just what is happening) which stops cell dividion and starts differentiation. hh induces dpp, leads to inducing proneural genes. r8 matures first with delta noch signaling induces 2 and 5 they mature, then 3 and 1, 4 and 6 and finally boss ligand in r8 binds to seveless receptor and induces differentiation within r7
delta noch competition induces pro-neural genes in mammals as well. through delta noch signlaing some becomes more delta become neural and glial blast
experiment on directions of neuron (intrinsic or given by enviornment)
thymadine labeling of cells on ferret brain, gave injections on day 29 of gestation and they look at which layer cells end up at they end up at layer 6. if u inject on post gestation day 1 the cells will end up on layer 2 and 3
if cells have intrinsic cues they will go to 6 if the are more envionrmnetal they go to 2 and 3. findings were that they go to both.
if cells are done dividing they go where they meant to if newer cells they can change