The notochord plays an important role in the differentiation of the paraxial mesoderm and the neural tube. We have analyzed the role of the notochord in somite differentiation and subsequent formation of the vertebral column using a mouse mutant, Danforth's short-tail (Sd). In this mutant, the skeletal phenotype is most probably a result of degeneration and subsequent loss of the notochord. The Sd gene is known to interact with undulated (un), a sclerotome mutant. Double mutants between Sd and un alleles show an increase in the severity of the defects, mainly in the ventral parts of the vertebrae. We also show that part of the Sd phenotype is strikingly similar to that of the un alleles. As un is known to be caused by a mutation in the Pax-1 gene, we analyzed Pax-1 expression in Sd embryos. In Sd embryos, Pax-1 expression is reduced, providing a potential molecular basis for the genetic interaction observed. A complete loss of Pax-1 expression in morphologically intact mesenchyme was found in the lower thoracic-lumbar region, which is phenotypically very similar to the corresponding region in a Pax-1 null mutant, Undulated short-tail. The sclerotome developmental abnormalities in Sd coincide closely, both in time and space, with notochordal changes, as determined by whole-mount T antibody staining. These findings indicate that an intact notochord is necessary for normal Pax-1 expression in sclerotome cells, which is in turn required for the formation of the ventral parts of the vertebrae. The observed correlation among structural changes of the notochord, Pax-1 expression levels and skeletal phenotypes, suggests that Pax-1 might be an intrinsic mediator of notochordal signals during the dorsoventral specification of vertebrae.

Avery
G.
,
Chow
M.
,
Holtzer
H.
(
1956
).
An experimental analysis of the development of the spinal column, V. Reactivity of chick somites.
J. Exp. Zool
132
,
409
425
Balling
R.
,
Lau
C. F.
,
Dietrich
S.
,
Wallin
J.
,
Gruss
P.
(
1991
).
Development of the skeletal system.
Ciba Found. Symp
165
,
132
143
Bopp
D.
,
Burri
M.
,
Baumgartner
S.
,
Frigerio
G.
,
Noll
M.
(
1986
).
Conservation of a large protein domain in the segmentation gene Paired and in functionally related genes of Drosophila.
Cell
47
,
1033
1040
Bovolenta
P.
,
Dodd
J.
(
1991
).
Perturbation of neuronal differentiation and axon guidance in the spinal cord of mouse embryos lacking a floor plate: analysis of Danforth's short-tail mutation.
Development
113
,
625
639
Center
E. M.
,
Spigelman
S. S.
,
Wilson
D. B.
(
1982
).
Perichordal sheath of heterozygous and homozygous Danforth's short-tail mice.
J. Hered
73
,
299
300
Chalepakis
G.
,
Fritsch
R.
,
Fickenscher
H.
,
Deutsch
U.
,
Goulding
M.
,
Gruss
P.
(
1991
).
The molecular basis of the undulated / Pax-1 mutation.
Cell
66
,
873
884
Christ
B.
,
Wilting
J.
(
1992
).
From somites to vertebral column.
Ann. Anat
174
,
23
32
Cooper
G. W.
(
1965
).
Induction of somite chondrogenesis by cartilage and notochord: A correlation between inductive activity and specific stages of cytodifferentiation.
Dev. Biol
12
,
185
212
Detwiler
S. R.
,
Holtzer
H.
(
1956
).
The developmental dependence of the vertebral column upon the spinal cord in the urodele.
J. Exp. Zool
132
,
299
310
Deutsch
U.
,
Dressler
G.R.
,
Gruss
P.
(
1988
).
Pax-1, a member of a paired box homologous murine gene family, is expressed in segmented structures during development.
Cell
53
,
617
625
Dietrich
W.
,
Katz
H.
,
Lincoln
S. E.
,
Shin
H.-S.
,
Friedman
J.
,
Dracopoli
N. C.
,
Lander
E. S.
(
1992
).
A genetic map of the mouse suitable for typing intraspecific crosses.
Genetics
131
,
423
447
Dunn
L. C.
,
Gluecksohn-Schoenheimer
S.
,
Bryson
V.
(
1940
).
A new mutation in the mouse affecting spinal column and urogenital system.
J. Hered
31
,
343
348
Epstein
D. J.
,
Vekemans
M.
,
Gros
P.
(
1991
).
splotch (Sp2H), a mutation affecting development of the mouse neural tube, shows a deletion within the paired homeodomain of Pax-3.
Cell
67
,
767
774
Franz
T.
,
Kothary
R.
,
Surani
M. A. H.
,
Halata
Z.
,
Grim
M.
(
1993
).
The splotch mutation interferes with muscle development in the limbs.
Anat. Embryol
187
,
153
160
Glisin
V.
,
Crkvenjakov
R.
,
Byus
C.
(
1974
).
Ribonucleic acid isolated by cesium chloride centrifugation.
Biochemistry
13
,
2633
2637
Gluecksohn-Schoenheimer
S.
(
1945
).
The embryonic development of mutants of the Sd -strain in mice.
Genetics
30
,
29
38
Goulding
M. D.
,
Chalepakis
G.
,
Deutsch
U.
,
Erselius
J.
,
Gruss
P.
(
1991
).
Pax-3, a novel murine DNA binding protein expressed during early neurogenesis.
EMBO J
10
,
1135
1147
Goulding
M. D.
,
Lumsden
A.
,
Gruss
P.
(
1993
).
Signals from the notochord and floor plate regulate the region-specific expression of two Pax genes in the developing spinal cord.
Development
117
,
1001
1016
Grobstein
C.
,
Holtzer
H.
(
1955
).
In vitro studies of cartilage induction in mouse somite mesoderm.
J. Exp. Zool
128
,
333
357
Gruneberg
H.
(
1953
).
Genetical studies on the skeleton of the mouse. VI. Danforth's short-tail.
J. Genet
51
,
317
326
Gruneberg
H.
(
1954
).
Genetical studies on the skeleton of the mouse. XII. The development of undulated.
J. Genet
52
,
441
455
Gruneberg
H.
(
1958
).
Genetical studies on the skeleton of the mouse. XXII. The development of Danforth's short-tail.
J. Embryol. exp. Morph
6
,
124
148
Gruss
P.
,
Walther
C.
(
1992
).
Pax in development.
Cell
69
,
719
722
Hatta
K.
,
Kimmel
C.
,
Ho
R.
,
Walker
C.
(
1991
).
The cyclops mutation blocks specification of the floor plate of the zebrafish central nervous system.
Nature
350
,
339
341
Kessel
M.
,
Balling
R.
,
Gruss
P.
(
1990
).
Variations of cervical vertebrae after expression of a Hox-1.1 transgene in mice.
Cell
61
,
301
308
Kessel
M.
,
Gruss
P.
(
1991
).
Homeotic transformations of murine vertebrae and concomitant alteration of Hox codes induced by retinoic acid.
Cell
67
,
1
20
Kispert
A.
,
Herrmann
B. G.
(
1993
).
The Brachyury gene encodes a novel DNA binding protein.
EMBO J
12
,
3211
3220
Koseki
H.
,
Jochen
Z.
,
Mizutani
Y.
,
Simon-Chazottes
D.
,
Guenet
J.-L.
,
Balling
R.
,
Gossler
A.
(
1993
).
Fine genetic mapping of the proximal part of mouse Chromosome 2 excludes Pax-8 as a candidate gene for Danforth's short tail (Sd).
Mammalian Genome
4
,
324
327
Jessell
T. M.
,
Bovolenta
P.
,
Placzek
M.
,
Tessier-Lavigne
M.
,
Dodd
J.
(
1989
).
Polarity and patterning of the neural tube: the origin and function of the floor plate.
Ciba Found. Symp
144
,
255
280
Melton
D. A.
,
Krieg
P. A.
,
Rebagliati
M. R.
,
Maniatis
T.
,
Zinn
K.
,
Green
M. R.
(
1984
).
Efficient in vitro synthesis of biologically activeRNA and RNA hybridization probes from plasmids containing a bacteriophage SP6 promotor.
Nucl. Acids Res
12
,
7035
7050
Paavola
L. G.
,
Wilson
D. B.
,
Center
E. M.
(
1980
).
Histochemistry of the developing notochord, perichordal sheath and vertebrae in Danforth's short-tail (Sd) and normal C57BL/6 mice.
J. Embryol. exp. Morph
55
,
227
245
Placzek
M.
,
Tessier-Lavigne
M.
,
Yamada
T.
,
Jessell
T.
,
Dodd
J.
(
1990
).
Mesodermal control of neural cell identity: floor plate induction by the notochord.
Science
250
,
985
988
Pourquie
O.
,
Coltey
M.
,
Teillet
M.-A.
,
Ordahl
C.
,
Le Douarin
N. M.
(
1993
).
Control of dorsoventral patterning of somitic derivatives by notochord and floor plate.
Proc. Natl. Acad. Sci. USA
90
,
5242
5246
Rosen
B.
,
Beddington
R. S. P.
(
1993
).
Whole-mount in situ hybridization in the mouse embryo: gene expression in three dimensions.
Trends Genet
9
,
162
167
Takahashi
Y.
,
Monsoro-Burq
A.-H.
,
Bontoux
M.
,
Le Douarin
N. M.
(
1992
).
A role for Quox-8 in the establishment of the dorsoventral pattern during vertebra development.
Proc. Natl. Acad. Sci. USA
89
,
10237
10241
van Straaten
H. W. M.
,
Heckking
J. W. M.
(
1991
).
Development of floor plate, neurons and axonal outgrowth pattern in the early spinal cord of the notochord-deficient chick embryo.
Anat. Embryol
184
,
55
63
Wallace
M. E.
(
1985
).
An inherited agent of mutation with chromosome damage in wild mice.
J. Hered
76
,
271
278
Wallace
M. E.
(
1985
).
A modifier mapped in the mouse.
Genetica
46
,
529
–.
Wallin
J.
,
Mizutani
Y.
,
Imai
K.
,
Miyashita
N.
,
Moriwaki
K.
,
Taniguchi
M.
,
Koseki
H.
,
Balling
R.
(
1993
).
A new Pax gene, Pax-9, maps to mouse chromosome 12.
Mammalian Genome
4
,
354
358
Wang
D.
,
Villasante
A.
,
Lewis
S. A.
,
Cowan
N.
(
1986
).
The mammalian-tubulin repertoire: hematopoietic expression of a novel, heterologous -tubulin isotype.
J. Cell Biol
103
,
1903
1910
Watterson
R. L.
,
Fowler
I.
,
Fowler
B. J.
(
1954
).
The role of the neural tube and notochord in development of the axial skeleton of the chick.
Am. J. Anat
95
,
337
397
Wilkinson
D. G.
,
Bhatt
S.
,
Herrmann
B. G.
(
1990
).
Expression pattern of the mouse T gene and its role in mesoderm formation.
Nature
343
,
657
659
Wolf
C.
,
Thisse
C.
,
Stoetzel
C.
,
Thisse
B.
,
Gerlinger
P.
,
Perrin-Schmitt
F.
(
1992
).
The M-twist gene of Mus is expressed in subsets of mesodermal cells and is closely related to the Xenopus X-twi and Drosophila twist genes.
Dev. Biol
143
,
363
373
Wright
M. E.
(
1947
).
undulated: a new genetic factor in Mus musculus affecting the spine and tail.
Hered
1
,
137
141
Yamada
T.
,
Placzek
M.
,
Tanaka
H.
,
Dodd
J.
,
Jessell
T. M.
(
1991
).
Control of cell pattern in the developing nervous system: polarizing activity of the floor plate and notochord.
Cell
64
,
635
647
Yamada
T.
,
Pfaff
S. L.
,
Edlund
T.
,
Jessell
T. M.
(
1993
).
Control of cell pattern in the neural tube: motor neuron induction by diffusible factors from the notochord and floor plate.
Cell
73
,
673
686
Youn
B. W.
,
Malacinski
G. M.
(
1980
).
Axial structure development in ultraviolet-irradiated (notochord-defective) amphibian embryos.
Dev. Biol
83
,
339
352
This content is only available via PDF.