Chapter 8 & 9 Flashcards
what makes goosecoid?
spemann organizer
what activates the release of goosecoid? what does goosecoid do?
nodal expression from the Nieuwkoop Center
- blocks BMPs so NS is formed (not skin)
what are the two types of proteins released by the organizer? give examples of each
nuclear (goosecoid, twin, siamois)
secreted (chordin, frzb, noggin, Shh, nodal, dickkopf, cerberus)
- secreted proteins are released by nuclear proteins
where in the cell are E-cadherins found?
epidermis (skin)
what does Chordin do?
binds directly to BMPs to inactivate it
- turned on by migrated IMZ cells
- rescues ectodermal cells from skin fate
what is the default pathway of ectodermal cells?
neural tissue
what are BMPs?
bone morphogenic proteins
- induces the skin fate
- occurs when chordin is blocked (no NS)
who created einstucking?
Otto Mangold (1933)
talk about the einstucking experiment where he took 4 regions of the archenteron from a LATE gastrula and put them into an EARLY gastrula blastocoel
when he took different regions of the archenteron (already has NS and has migrated) and grafted them, each region formed an extra part of an embryo depending on which section of the the tissue he extracted it from
talk about the einstucking experiment where he took the dorsal blastopore lip of an EARLY gastrula and put it into another EARLY gastrula
vs
taking the lip from a LATER stage gastrula and putting it into another EARLY gastrula
the early gastrula lip formed a second head
the later stage gastrula lip formed a second tail
- proved that the first organizer cells make the head first, and then the later cells form a tail
what two molecules explain the einstucking experiment?
BMP
Wnt
what happens when both BMP and Wnt are activated?
form epidermis (skin)
what happens when only Wnt are active and BMPs are blocked?
- what is blocking BMP?
posterior NS (spinal cord)
- chordin is blocking BMP
what happens when both BMP and Wnt are blocked? what does this mean in relation to the einstucking experiment?
anterior NS (brain)
- means that BMP and Wnt are both being blocked initially, and then Wnt eventually becomes activated
which region has the highest expression of Wnt (anterior or posterior)?
posterior (tail)
where are Wnt antagonists found? give examples
found in the head & form a gradient
- Frzb (MAIN ONE)
- Dickkopf, Cerberus, IGF (insulin-like GFs)
what does retinoic acid do? where do they have the highest expression
activates Wnt, Fgfs, and Shh
- found in the tail region (posterior)
what three molecules help differentiate the left side axis?
Vg1, Nodal (Xnr1), Pitx2
- Vg1 & Nodal are mainly on left side
- Pitx2 is only on left side
- due to the use of microtubules
what is an amniote?
things that have an amniotic sac
- adaptation to lay eggs on land instead of in the water
what is the chorioaliantoic MB? (CAM)
similar to placenta, but in chicks
- gas exchange, waste removal, protect embryo
what main structure helps form axes in chicks?
Hensens Node -> dorsal blastopore lip
- migrates cells inside to become mesoderm and induction of NS
describe the shape of a chick embryo. How do the cells migrate in the dorsal lip?
shaped like a disc (stuffed crust pizza)
- cells from top migrate inward, and then out & up