TY - JOUR
T1 - tbx6, a Brachyury-related gene expressed by ventral mesendodermal precursors in the zebrafish embryo
AU - Hug, Barbara
AU - Walter, Virginia
AU - Grunwald, David Jonah
N1 - Funding Information:
We thank Sharon Johnson for excellent assistance with the ®sh stocks. We thank our colleagues in the ®eld for supplying many reagents required for these studies: anti-Ntl antibody (S. Schulte-Merker), eve1 plasmid (J.-S. Joly), ntl plasmid (S. Schulte-Merker), snail1 plasmid (J. Postlethwait), activinA (W. Fischer and W. Vale), and mutant lines of zebra®sh (C. Kimmel). We thank D. Chapman, S. Mackem, G. Papaioannou, and L. Silver for sharing unpublished results regarding the expression of tbx6 in the mouse and the chick embryo and C. Sagerstrom, Y. Grinblat, and H. Sive for advice on culturing animal caps. We thank our Utah colleagues, including B. Bisgrove, C. Cretekos, B. Riley, C. Thummel, E. Wilson, and Y. Zhu, for their insights, advice, and criticism. B.H. was supported by a predoctoral fellowship from an NIH Genetics Training Grant. This work was supported by grants from the NIH (1 RO1 RR10253-01) and NSF (MCB-9420984).
PY - 1997/3/1
Y1 - 1997/3/1
N2 - Classical embryology experiments have indicated the existence of dorsal-type and ventral-type mesoderms that arise as a consequence of mesoderm induction during vertebrate development. Here we report that the zebrafish tbx6 gene, a member of the Brachyury-related T-box family of genes, is exclusively expressed by ventral mesendoderm. Three observations link the expression of tbx6 to ventral mesoderm specification. First, the gene is initially expressed at the onset of gastrulation within a ventrolateral subpopulation of cells that express the pan-mesodermal gene, no tail (Brachyury). Second, the mesoderm-inducing factors activin and bFGF activate tbx6 expression in animal caps. Third, dorsalization of the mesendodermal precursor population following exposure of embryos to lithium ions causes down-regulation of tbx6 transcription. tbx6 is expressed transiently in the involuting derivatives of the ventral mesendoderm, which give rise to nonaxial mesodermal tissues; its expression is extinguished as tissue differentiation progresses. Transcription of tbx6 commences about an hour after initiation of expression of the pan-mesendodermal gene no tail and the organizer gene goosecoid. The dependence of tbx6 expression on no tail activity was examined in no tail mutant embryos. The activation of tbx6 transcription in ventral mesoderm does not depend on no tail gene activity. However, no tail appears to contribute to the maintenance of normal levels of tbx6 transcription and may be required for tbx6 transcription in the developing tail.
AB - Classical embryology experiments have indicated the existence of dorsal-type and ventral-type mesoderms that arise as a consequence of mesoderm induction during vertebrate development. Here we report that the zebrafish tbx6 gene, a member of the Brachyury-related T-box family of genes, is exclusively expressed by ventral mesendoderm. Three observations link the expression of tbx6 to ventral mesoderm specification. First, the gene is initially expressed at the onset of gastrulation within a ventrolateral subpopulation of cells that express the pan-mesodermal gene, no tail (Brachyury). Second, the mesoderm-inducing factors activin and bFGF activate tbx6 expression in animal caps. Third, dorsalization of the mesendodermal precursor population following exposure of embryos to lithium ions causes down-regulation of tbx6 transcription. tbx6 is expressed transiently in the involuting derivatives of the ventral mesendoderm, which give rise to nonaxial mesodermal tissues; its expression is extinguished as tissue differentiation progresses. Transcription of tbx6 commences about an hour after initiation of expression of the pan-mesendodermal gene no tail and the organizer gene goosecoid. The dependence of tbx6 expression on no tail activity was examined in no tail mutant embryos. The activation of tbx6 transcription in ventral mesoderm does not depend on no tail gene activity. However, no tail appears to contribute to the maintenance of normal levels of tbx6 transcription and may be required for tbx6 transcription in the developing tail.
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U2 - 10.1006/dbio.1996.8490
DO - 10.1006/dbio.1996.8490
M3 - Article
C2 - 9119115
AN - SCOPUS:0031106250
SN - 0012-1606
VL - 183
SP - 61
EP - 73
JO - Developmental Biology
JF - Developmental Biology
IS - 1
ER -