Molecular Genetics of Pattern Formation I Flashcards
Robertsonian translocaion
long arms of 14 fused to 21
-leads to downs
Aneupolidy is typically…
embryonic lethal
-13 and 18 can survive post fatally
trisomy 13
midline defects, clef lip, csn malformormations, holopresencpahy-single ventricle
trisomy 18
clenched hands, low ears, rocker bottom feet
signle gene mutations causing genetic defects
especially important in SHH and HOW
-also have organ specific ones
Large doses of intrauterine vitamin a (vit a aka)
facial abnormalities, neural tube defects,
- in acne meds
- retinoic acid
when is risk of brith defects from teratogens highest
3-8 weeks
Signal transduction via receptor kinases pathway
ligand binds to receptor, dimerization, signalling cascade involving phosphrylation ensures, activated protein complex is a TF
Where does retinoic acid bind
to nucelar receptors always located in nuceleus
TGF beta signalling/SMADS pathway
draw slide 12
+main pathway for antagonism
TGf beta (can also be BMP4 or activin) binds to receptor
Second receptor recruited+TGF (or BMP4) binds+phosphorylates receptor
Recruits/Phosphorylates Smad 2 or 3
Smad 2/3 oligomerizes with Smad 4 and goes to nucleus where can recruit other gene proteins and activate trx of specific target gene
use something that antagonizes tgif-beta/bmp4
Fgf heparan sulfate
Fibroblast growth factors
4 receptors
used in critical early axis format and for dev of several organs (bone and cartilage)
Heparan sulfate on cell surface helps FGF present to Tyrosine kinase receptors and helps active dimeric receptor even when FGF is monomer
Preimplantation timeline
First meiosis-several divisions, morula, then blastocyst-day5
ICM embryoblast+trophoblast
when does implantation occur
what can icm cells become
day 6
ICM cells can become ecto, meso, or end
Two TFs i eqrly embryonic cell lineages
all cells express both at moral
some cell preferentatillly 1 vs other at 16 cells
the cells segregate-one forms TE other forms ICM
-happens again to form endoderm vs epiblast
eventually both cells restrict each other with reciprocal inhibition
2nd week germ disc’s mesoderm
Little embryonic mesoderm-forms connective tissue, control nervous system formation
what are embryonic endoderm dn mesoderm derived from
cell that enter primitive streak
endodermal enter first during gastrulation
-mesdermal arise from epiblast and enter, spread extensively
engrossing of epiblast cells are thought to replace hypoblast cells (become yolk sac lining)-ingressing cells fan out to form mesodermal layer
embryonic node
area of active invagination into inner embryo