A unique myosin heavy chain cDNA (AMHC1), which is expressed exclusively in the atria of the developing chicken heart, was isolated and used to study the generation of diversified cardiac myocyte cell lineages. The pattern of AMHC1 gene expression during heart formation was determined by whole-mount in situ hybridization. AMHC1 is first activated in the posterior segment of the heart when these myocytes initially differentiate (Hamburger and Hamilton stage 9+). The anterior segment of the heart at this stage does not express AMHC1 although the ventricular myosin heavy chain isoform is strongly expressed beginning at stage 8+. Throughout chicken development, AMHC1 continues to be expressed in the posterior heart tube as it develops into the diversified atria. The early activation of AMHC1 expression in the posterior cardiac myocytes suggests that the heart cells are diversified when they differentiate initially and that the anterior heart progenitors differ from the posterior heart progenitors in their myosin isoform gene expression. The expression domain of AMHC1 can be expanded anteriorly within the heart tube by treating embryos with retinoic acid as the heart primordia fuse. Embryos treated with retinoic acid prior to the initiation of fusion of the heart primordia express AMHC1 throughout the entire heart-forming region and fusion of the heart primordia is inhibited. These data indicate that retinoic acid treatment produces an expansion of the posterior (atrial) domain of the heart and suggests that diversified fates of cardiomyogenic progenitors can be altered.

REFERENCES

Auffray
C.
,
Rougeon
R.
(
1980
)
Purification of mouse immunoglobulin heavy chain messenger RNAs from total myeloma tumor RNA.
Eur. J. Biochem
107
,
303
–.
Bisaha
J. G.
,
Bader
D.
(
1991
)
Identification and characterization of a ventricular-specific avian myosin heavy chain, VMHC1: Expression in differentiating cardiac and skeletal muscle.
Dev. Biol
148
,
355
364
Chen
E.
,
Seeburg
P. H.
(
1985
)
Supercoil sequencing: A fast and simple method for sequencing plasmids.
DNA
4
,
165
170
Chomczynski
P.
,
Sacchi
N.
(
1987
)
Single-step method of RNA isolation by acid guanidium thiocyanate-phenol-chloroform extraction.
Anal. Biochem
162
,
156
159
Conlan
R. A.
,
Rossant
J.
(
1992
)
Exogenous retinoic acid rapidly induces anterior ectopic expression of murine Hox-2 genes in vivo.
Development
116
,
357
368
Coutinho
L. L.
,
Morris
J.
,
Ivarie
R.
(
1992
)
Whole mount in situ detection of low abundance transcripts of the myogenic factor qmf1 and myosin heavy chain protein in quail embryos.
Biotechniques
13
,
722
724
Coutinho
L. L.
,
Morris
J.
,
Marks
H. L.
,
Buhr
R. J.
,
Ivarie
R.
(
1993
)
Delayed somite formation in a quail line exhibiting myofiber hyperplasia is accompanied by delayed expression of myogenic regulatory factors and myosin heavy chain.
Development
117
,
563
569
De Jong
F.
,
Geerts
W. J. C.
,
Lamers
W. H.
,
Los
J. A.
,
Moorman
A. F. M.
(
1990
)
Isomyosin expression pattern during formation of the tubular chicken heart: A three dimensional immunohistochemical analysis.
Anat. Rec
226
,
213
227
Evans
D.
,
Miller
J. B.
,
Stockdale
F. E.
(
1988
)
Developmental patterns of expression and coexpression of myosin heavy chains in atria and ventricles of the avian heart.
Dev. Biol
127
,
376
383
Feinberg
A. P.
,
Vogelstein
B.
(
1983
)
A technique for radiolabeling DNA restriction endonuclease fragments to high specific activity.
Anal. Biochem
132
,
6
13
Gonzalez-Sanchez
A.
,
Bader
D.
(
1984
)
Immunochemical analysis of myosin heavy chains in the developing chicken heart.
Dev. Biol
103
,
151
158
Gonzalez-Sanchez
A.
,
Bader
D.
(
1990
)
In vitro analysis of cardiac progenitor cell differentiation.
Dev. Biol
139
,
197
209
Hamburger
V.
,
Hamilton
H. L.
(
1951
)
A series of normal stages in the development of the chick embryo.
J. Morph
88
,
49
67
Han
Y.
,
Dennis
J. E.
,
Cohen-Gould
L.
,
Bader
D. M.
,
Fischman
D. A.
(
1992
)
Expression of sarcomeric myosin in the presumptive myocardium of chicken embryos occurs within six hours of myocyte commitment.
Dev. Dynamics
193
,
257
265
Lehrach
H. D.
,
Diamond
D.
,
Wozney
J. M.
,
Boegtker
H.
(
1977
)
RNA molecular weight determinations by gel electrophoresis under denaturing conditions, a critical reexamination.
Biochemistry
16
,
4743
4750
Manasek
F. J.
(
1968
)
Embryonic development of the heart. I. A light and electron microscope study of myocardial development in the early chick embryo.
J. Morph
125
,
329
366
McNally
E. M.
,
Kraft
R.
,
Bravo-Zehnder
M.
,
Taylor
D. A.
,
Leinwand
L. A.
(
1989
)
Full-length rat alpha and beta cardiac myosin heavy chain sequences.
J. Mol. Biol
210
,
665
671
Moore
L. A.
,
Arrizubieta
M. J.
,
Tidyman
W. E.
,
Herman
L. A.
,
Bandman
E.
(
1992
)
Analysis of the chicken fast myosin heavy chain family: localization of isoform-specific antibody epitopes and regions of divergence.
J. Mol. Biol
225
,
1143
1151
New
D. A. T.
(
1955
)
A new technique for the cultivation of the chick embryo in vitro.
J. Embryol. Exp. Morph
3
,
320
331
O'Brien
T. X.
,
Lee
K. J.
,
Chien
K. R.
(
1993
)
Positional specification of ventricular myosin light chain 2 expression in the primitive murine heart tube.
Proc. Natl. Acad. Sci. USA
90
,
5157
5161
Osmond
M. K.
,
Butler
A. J.
,
Voon
F. C. T.
,
Bellairs
R.
(
1991
)
The effects of retinoic acid on heart formation in the early chick embryo.
Development
113
,
1405
1417
Peng
I.
,
Dennis
J. E.
,
Rodriguez-Boulan
E.
,
Fischman
D. A.
(
1990
)
Polarized release of enveloped viruses in the embryonic chick heart: demonstration of epithelial polarity in the presumptive myocardium.
Dev. Biol
141
,
164
172
Pownall
M. E.
,
Emerson
C. P.
Jr
(
1992
)
Sequential activation of three myogenic regulatory genes during somite morphogenesis in quail embryos.
Dev. Biol
151
,
67
79
Robbins
J.
,
Horan
T.
,
Glick
J.
,
Kropp
K.
(
1986
)
The chicken myosin heavy chain family.
J. Biol. Chem
261
,
6606
6612
Ruiz i Altaba
A.
,
Jessell
T.
(
1991
)
Retinoic acid modifies mesodermal patterning in early Xenopus embryos.
Genes Dev
5
,
175
187
Saez
L.
,
Leinwand
L. A.
(
1986
)
Characterization of diverse forms of myosin heavy chain expressed in adult human skeletal muscle.
Nucl. Acids Res
14
,
2951
2969
Satin
J.
,
Fujii
S.
,
DeHaan
R.
(
1988
)
Development of cardiac beat rate in early chick embryos is regulated by regional cues.
Dev. Biol
129
,
103
113
Stalsberg
H.
,
DeHaan
R. L.
(
1969
)
The precardiac areas and formation of the tubular heart in the chick embryo.
Dev. Biol
19
,
128
159
Stanier
D. Y. R.
,
Fishman
M. C.
(
1992
)
Patterning the zebrafish heart tube: acquisition of anteroposterior polarity.
Dev. Biol
153
,
91
101
Stanier
D. Y. R.
,
Lee
R. K.
,
Fishman
M. C.
(
1993
)
Cardiovascular development in the zebrafish I. Myocardial fate and and heart tube formation.
Development
119
,
31
40
Sweeney
L. J.
,
Zak
R.
,
Manasek
F. J.
(
1987
)
Transitions in cardiac isomyosin expression during differentiation of the embryonic chick heart.
Circ. Res
61
,
287
295
Thaller
C.
,
Eichele
G.
(
1987
)
Identification and spatial distribution of retinoids in the developing chick limb bud.
Nature
327
,
625
628
Tickle
C.
,
Lee
J.
,
Eichele
G.
(
1985
)
A quantitative analysis of the effect of all-trans-retinoic acid on the pattern of chick wing development.
Dev. Biol
109
,
82
95
This content is only available via PDF.