Developmental Biology Tutorial No. 2 – The Making of a Vertebrate Limb.
"How is the vertebrate limb patterned?"
If you do not wish to read about vertebrate limb development it is advised you scroll straight down to the kittens strategically placed at the bottom of the page to help you overcome the trauma of momentarily being forced to think about work.
- Gilbert, 6th Ed, chapter 16 (and pages 65-66 of 6th edition but not the 7th) Yes, this is a book and i have no links to it. It requires the use of methods other than clicking... unfortunately.
- Pattern formation: Old models out on a limb. ah, scientific humour at its best "out on a limb" indeed. Laugh? I almost died :|
- Patterning Systems—From One End of the Limb to the Other.
- The contribution of chicken embryology to the understanding of vertebrate limb development.
The formation of the limb bud and the identity of the fore and hind limbs
- Vertebrate limb development - the early stages in chick and mouse.
- Roles for FGF8 in the Induction, Initiation, and Maintenance of Chick Limb Development.
- Fgf10 is essential for limb and lung formation.
- WNT Signals Control FGF-Dependent Limb Initiation and AER Induction in the Chick Embryo.
- The T-box genes Tbx4 and Tbx5 regulate limb outgrowth and identity.
- Tbx5 is required for forelimb bud formation and continued outgrowth.
- Tbx5 and Tbx4 trigger limb initiation through activation of the Wnt/Fgf signaling cascade.
(For background interest this is one of the many papers on the role of Tbx5 in genetic disease. It causes Holt-Oram syndrome: A dominantly inherited malformation syndrome with short stature, upper limb anomaly, minor craniofacial anomalies, and absence of TBX5 mutations: Report of a Thai family )
Induction of the apical ectodermal ridge and limb outgrowth
Allocation to the AER
- Radical fringe positions the apical ectodermal ridge at the dorsoventral boundary of the vertebrate limb.
D/V patterning of the outgrowth
- Dorsalizing signal Wnt-7a required for normal polarity of D-V and A-P axes of mouse limb. (I hope this isn't vital because I can't access more than the abstract. Anyone who can leave a link in the comments please, thanks)
- Induction of the LIM homeobox gene Lmx1 by WNT6a establishes dorsoventral pattern in the vertebrate limb.
AER function, the roles of FGF's in limb outgrowth
- FGF-4 replaces the apical ectodermal ridge and directs outgrowth and patterning of the limb.
- A role for FGF-8 in the initiation and maintenance of vertebrate limb bud outgrowth.
- Fibroblast growth factor receptor 2 mediated reciprocal regulation loop between FGF8 and FGF10 is essential for limb induction.
- Fgf8 is required for outgrowth and patterning of the limbs.
Development of the antero- posterior axis
- Sonic hedgehog mediates the polarizing activity of the ZPA.
- Hoxb-8 has a role in establishing early anterior-posterior polarity in chick forelimb but not hindlimb.
- Shh and Gli3 are dispensable for limb skeleton formation but regulate digit number and identity.
- Signal relay by BMP antagonism controls the SHH/FGF4 feedback loop in vertebrate limb buds.
- Gremlin is the BMP antagonist required for maintenance of Shh and Fgf signals during limb patterning.
In the interest of actually making research that bit more interesting i have developed "ScopusWhacking". Woo and yay. Aim for the search to return only one research article when provided with just one surname and one other word. Usually works 1/3 of the time. At least it does in bio. God i'm bored…
Caption anybody? No prizes well, no prizes that involve the consumption of vinegar shots