Pharangeal Arch Devo

jambomber's version from 2015-04-25 16:41

Section 1

Question Answer
What is the evidence that arch development is independant of NCCs?Still form when NCCs are ablated
What gene is disrupted in zfish VGO mutants?Tbx1
How do we know that Tbx1 functions cell autonomously? Where does it function?Mosaic animals (Wt cells in a mutant background - partial rescue) Endoderm
What is the phenotype of vgo mutants? defects in the pharyngeal archeses, g fusion and loss of neural crest-derived pharyngeal cartilages, reductions in endodermal pouches and aortic arches, and the absence of the thymus
How was it shown that Tbx functions w/in endo?Transplant mesencyme into arches - partial rescue of NCC derived structures- suggest endoderm producing a signal
What is the effect of no RA signallin?No caudal arch devo 3+4 in quail
How is RA production organised?Expression of enzymes involved in biosynth Raldh2 to level of 2nd arch in splanchic mesoderm
What is the evidence for RA's importance?Pan RAR antagonist causes loss of arches 3+4 in Z fish. Can be rescued w/ exogenous RA
What regulates pharyngeal pouch formation?Combined Fgf 3/8 signal. Double k/o disrupts pouches + most arches
How was importance of Fgf signals demo'ed?Treat embryos w/ SU to inhibit Fgf signals- observe loss of arches in a-p sequence
Where do Fgf signals come from?Cranial mesoderm + Neural keel- both required to resuce formation in a Fgf mutant background

Section 2

Question Answer
What are the morphogenetic movements occuring 1) Destabilisation 2) Reorganisation into a bilayered pouch
How was Cranial mesoderm demostrated to be essential for the morph movements in pouch formationCFP:Nitroreductase Metronidozole Cell autonomous killing. Malformed pouches
Where are wnts expressed in pharangeal devo? Which wnts?Wnt11R in mesoderm. Wnt4a ectoderm
What markers do wnt signals colocalise with?nkx2.5= mesoderm =11r Offset = Ectoderm=4a
What did the Crump paper show?That Fgfs are important for pharangeal sementation
What effects of Wnt-?4a - = Failure to destabilise bilayer+ migrate, 11r= Failure to re-establish bilayer
What is different about wnt signalling in this context? EvidenceOccurs through non canonical pathway. DNve TCF (downstream canonical) no effect on arch segemntation. Deletion of DEV( part of non Canon) causes interferance
How is TCf related to wnt signalling?B catenin binds it and serves as a coactivator
What is Alcama?Activated leucocyt cell adhesion molecule- localises progressivel to PM during pouch formaion
How does wnt4a organise Alcama?Through cdc42- localises Alcama to PM - enabling cell adhesion. DNve causes diffuse localisation