Flashcards
MCDB 153: Lec 2-4: Early Neural Development
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- 1establish asymmetryasymmetric division
symmetric div - 2asymmetric divisionsister cells born diff
some cyt comps not distrib evenly
get diff things after div
ex: TS comps
diff cyt = diff path - 3symmetric divisionby induction
sister cells become diff as a result of influences (signal) acting on them after birth
neighbor cells send diff signals and cause differentiation
synth dif prot - use diff DNA - 4differentiation causes: "sculpt and build embryo"SIMP D
Signaling (induction)
Interaction
Movement
Proliferation
Death (apoptosis) - 5early animal developmentembryos resemble eachother
= common evol ancestor
many mechs early in development are common in in/invertebrates - 6universal mech of animal devEngrailed - deletion: rescue with a different species
mouse + fly engr gene = normal
all species use sim protein molecs to:
define SPECIALIZED CELLS
define DIFFERENCES between body regions
create the BODY PATTERN
= develop adult organism - 7what drives gastrulation acronym?E-D-E-F-E-S-B-I-G-E
change of cell SHAPE
cells rearrange POSITIONS with respect to one another
Filopodial-ECM interactions - 81) change cell shape gastrEPI CELLS AT BOTTOM of blastula change shape (cytoskeleton) and begin to INVAGINATE, producing a broad flat dome
forms gastrula - 92) rearrangecells in DOME rearrange into long, narrow GUT tube
- 103filopodia + ECM
at same time, cells extend FILOPODIA to gram ECM and pull tube inward (strong lateral attachments btwn cells) - 114surface cells slide along the surface toward the BLASTOPORE and then migrate inward into the INSIDE of the EMBRYO
- 125GUT + EPI
movt are complete when the end of the gut tube contacts the epi cells at the opposite end of the embryo, creating a hole (future mouth); other end is the future anus - 13fates of ectodermneural - nervous system
epidermal - epidermis
mesoderm goes nerual b/c interact w/ neurogenic region - 14net result of gastrulationendoderm ==> gut
ectoderm ==> neural (tube,crest) or epidermal
mesoderm ==> notochord - 15eventual fate of neural tube, crest; lumenneural tube - CNS
neural crest - PNS
lumen - ventricles in brain - 16microtubules actinMICROTUBULES
1) non-cov
2) dynamic polymers (elongate/shorten)
3) assembled from alpha, beta tubulin subunits
proper regulation essential for cell function and viability
ACTIN - also dynamic - 17NEURULATION how do ecto ==> epi/ **neuralchanges in cytoskeleton (allso, att btwn cells)
cells that become epidermis get shorter/flatter
microtubules in neural plate cells elongate, actin filaments contract ==> form neural tube
cellular rearrangements - CAMs
cadherins fold and make neural tube
n-cad = nerual cad - made by inner
e-cad = epi - made by outer - 18Inductioncells closest to signal get enough to sense to tell to differentiate
works by gradient - cells closer get more effect; decreases with difference - 19cell cycle w/ inductioncell cycle w/ ind = 30 min
normally 24 hrs
divide faster b/c
1) normal div - have to copy DNA, compartments. early div (before blast) - don't have to make new comps, not grow in mas
2) copy dna = cell makes many origins of rep = more DNA synth - 20frog development up to blastulaneed mechs to build asymm
frog - cyt not symm
cytoplasm: grey crescent, site of sperm entry
inner- more asymm ==> div, not same cyt
early div vertical, later horizontal
neighboring cells send signaling molecules and change cell shape - 21determination vs differentiationdetermination - point when cell committed to particular fate, even though not yet exhibiting differentiated properties
differentiation - acquisition/expression of differentiated properties - 22embryonic fragments and determination/fates1) remove animal from PREGASTRULA, culture, becomes EPIDERMIS
2) remove animal cap from GASTRULA, culture, becomes NEURAL
= thought epidermal was default - 23dorsal lip experiment spemman and mangoldtook cells from DORSAL LIP and put in ectopic (wrong) site ==> promote 2nd nervous system ==> cells that would have been epidermal changed phenotype (got second head)
==> controlled fate of cells in other embryo
dorsal lip - organizer cells - 243 ways to isolate neuralization factors1) isolate factor from dorsal blastopore
(failed b/c not enough starting material, bad fractionation techs)
2) trial and error w/ "candidates"
(fail b/c too many positive results)
3) test other tissues for activity
(fragments from diff organs, organisms were inductive) - 25ID of noggin as Neur factorA) egg - normal
B) egg + UV ==> no NS (ventralized)
C) egg + Li ==> large NS (hyperdorsalized)
D) egg + UV + mRNA from Li egg ==> normal (some prot code for NF)
E) organizer region mRNA ==> rev transcriptase ==> cDNA
org cDNA + UV ==> normal (cDNA code for NF) - 26which cDNA codesadded 6 diff cDNA in plasmids to e Coli
plate
each colony had a plasmid
plate + UV separately
plate w/ cDNA for NF expr NS
==> code seq ==> AA seq ==> IMF
showed noggin in organizer - 27dom-neg activinactivin - epi
dom-neg receptor = neural
-signaling blocked so neural
-sugg neur default
proposed activin inh neuralization of ecto
= neural is default, epi needs inducer - 28disoc animal cap expprior to gastrulation
animal cap ==> epi
signal goes to more cells b/c closer
animal cap dissoc ==> neural
weak signal
= neural default - 29sogchordin homolog in flies
sog KO ==> epidermilzation
sog + ==> neuralization
interacts w/ dpp
antagonize eachother
dpp KO ==> neuralization
dpp + ==> epidermalization - 30bmp4epi
sim to dpp
BMP4 + dissoc animal - epi
= need signaling - 31neuralation occurs first whereanterior end
- 32bmp4 bindingbinds receptor - epi
inh by noggin, chordin (mesoderm)
noggin - neural inducer b/c inh epi
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- Flashcards on MCDB 153: Lec 2-4: Early Neural Development, created by Phil Nosrat on 21/04/2016.
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