Dorsoventral Patterning of the Zebrafish Embryo
103
the transfonnation of the broad and unifonn expression of bmp2b to a
graded pattern, with bmp2b mRNA levels progressively dropping from
the ventral to dorsal side. This transformation is governed by the antagonizing action of Bmp2b and its mediator Smad5 on one side and the
Bmp2b antagonist Chordino on the other side. Judging from in situ
hybridization patterns in wild-type and mutant embryos, the establishment of this Bmp2b gradient, which is thought to have morphogenetic character-defining positional values and cell fates along the dorsoventral axis, appears completed by the onset of gastrulation.
In a third phase, which takes place during gastrulation, the Bmp2/4
gradient is interpreted and cell specifications occur according to the
local Bmp2/4 concentrations. This phase is independent of sbn smad5,
and it is currently unclear which alternative transcription factor mediating Bmp2/4 signaling might confer this independence of Smad5.
References
Attisano Land Wrana JL (1998) Mads and Smads in TGF~ signalling. Curr
Opin Cell BioI 10:188-194
Bauer H, Meier A, Hild M, Stachel S, Economides A, Hazelett D, Harland
RM, Hammerschmidt M (1998) Follistatin and Noggin are excluded from
the zebrafish organizer. Dev BioI 204:488-507
Blader P, Rastegar S, Fischer N, Strahle U (1997) Cleavage of the BMP-4 antagonist Chordin by zebrafish Tolloid. Science 278: 1937-1940
Conners SA, Trout J, Ekker M, Mullins MC (1999) The role of toltoidlminifin
in dorsoventral pattern formation of the zebrafish embryo. Development
126: 3119-3130
Dosch R, Gawantka V, Delius H, Blumenstock C, Niehrs C (1997) Bmp4 acts
as a morphogen in dorsoventral patterning in Xenopus. Development
124:2325-2334
Dudley AT, Lyons KM, Robertson EJ (1995) A requirement for bone morphogenetic protein-7 during development of the mammalian kidney and eye.
Genes Dev 9:2795-2807
Fainsod A, DeiBler K, Yelin R, Marom K, Epstein M, Pillemer G, Steinbeisser
H, Blum M (1997) The dorsalizing and neural inducing gene Jollistatin is
an antagonist of BMP-4. Mech Dev 63:39-50
Finelli AL, Bossie CA, Xie T, Padgett RW (1994) Mutational analysis of the
Drosophila toltoid gene, a human BMP-l homolog. Development
120:861-870
103
the transfonnation of the broad and unifonn expression of bmp2b to a
graded pattern, with bmp2b mRNA levels progressively dropping from
the ventral to dorsal side. This transformation is governed by the antagonizing action of Bmp2b and its mediator Smad5 on one side and the
Bmp2b antagonist Chordino on the other side. Judging from in situ
hybridization patterns in wild-type and mutant embryos, the establishment of this Bmp2b gradient, which is thought to have morphogenetic character-defining positional values and cell fates along the dorsoventral axis, appears completed by the onset of gastrulation.
In a third phase, which takes place during gastrulation, the Bmp2/4
gradient is interpreted and cell specifications occur according to the
local Bmp2/4 concentrations. This phase is independent of sbn smad5,
and it is currently unclear which alternative transcription factor mediating Bmp2/4 signaling might confer this independence of Smad5.
References
Attisano Land Wrana JL (1998) Mads and Smads in TGF~ signalling. Curr
Opin Cell BioI 10:188-194
Bauer H, Meier A, Hild M, Stachel S, Economides A, Hazelett D, Harland
RM, Hammerschmidt M (1998) Follistatin and Noggin are excluded from
the zebrafish organizer. Dev BioI 204:488-507
Blader P, Rastegar S, Fischer N, Strahle U (1997) Cleavage of the BMP-4 antagonist Chordin by zebrafish Tolloid. Science 278: 1937-1940
Conners SA, Trout J, Ekker M, Mullins MC (1999) The role of toltoidlminifin
in dorsoventral pattern formation of the zebrafish embryo. Development
126: 3119-3130
Dosch R, Gawantka V, Delius H, Blumenstock C, Niehrs C (1997) Bmp4 acts
as a morphogen in dorsoventral patterning in Xenopus. Development
124:2325-2334
Dudley AT, Lyons KM, Robertson EJ (1995) A requirement for bone morphogenetic protein-7 during development of the mammalian kidney and eye.
Genes Dev 9:2795-2807
Fainsod A, DeiBler K, Yelin R, Marom K, Epstein M, Pillemer G, Steinbeisser
H, Blum M (1997) The dorsalizing and neural inducing gene Jollistatin is
an antagonist of BMP-4. Mech Dev 63:39-50
Finelli AL, Bossie CA, Xie T, Padgett RW (1994) Mutational analysis of the
Drosophila toltoid gene, a human BMP-l homolog. Development
120:861-870