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Fig. 2. Developmental expression of Xenopus myocardin and MRTF genes. The expression of Xenopus myocardin (A-A'”) was analyzed by whole-mount in situ hybridization and compared to the expression patterns of the cardiac differentiation marker, MHCα (B-B'”), and the pre-cardiac marker, Nkx2-5 (C-C'”) at the stages indicated. Myocardin expression in the stage 24 embryo is localized to the pre-differentiation cardiac mesoderm in a more restricted domain than Nkx2-5, which is also expressed in the pharyngeal arch region (compare A' with C'). MHCα expression is located in an identical domain to myocardin at stage 27 (compare A” with B”). A'”, B'” and C'” are ventral views of the stage 27 embryos illustrated. (D) In the heart of a stage 45 embryo myocardin expression is located throughout the myocardial layer of the atrium (a), ventricle (v), and outflow tract (ot). (E) Myocardin is expressed in the visceral smooth muscle in stage 42 embryos. (F) Higher magnification reveals myocardin expression in individual smooth muscle cells adjacent the dorsal aortae and in the smooth muscle layer of the gut. DA, dorsal aorta; SM, smooth muscle. (G, H) In situ hybridization analysis of stage 27 embryos shows that the myocardin-related transcription factors, MRTF-A and MRTF-B, are not expressed in the pre-cardiac mesoderm (ventral views). (I) RT-PCR analysis of myocardin, MRTF-A and MRTF-B expression in early Xenopus embryos and isolated heart patches from stage 28 embryos confirms a lack of MRTF-A and B expression in the pre-cardiac mesoderm.

Image published in: Small EM et al. (2005)

Copyright © 2005. Image reproduced with permission of the Publisher and the copyright holder. This is an Open Access article distributed under the terms of the Creative Commons Attribution License.

GeneSynonymsSpeciesStage(s)Tissue
mrtfb.SLOC100301959, mkl2, MRTF-BX. laevisSometime during NF stage 1 to NF stage 25embryo
mrtfa.Smkl1, MRTF-AX. laevisSometime during NF stage 1 to NF stage 9embryo
myocd.Lmyocardin, SRF cofactor proteinX. laevisThroughout NF stage 15
nkx2-5.LAR2, csx, nkx-2.5, Nkx-2.5, nkx2.5, nkx2-5-a, nkx2-5-b, tinman, XNkx-2.5, XNkx2-5X. laevisThroughout NF stage 15anterior
myh6.SaMHC, ck231, MHC, MHCa, MHC-alpha, MHCalpha, muz, muzak, XCMHCX. laevisThroughout NF stage 15 to NF stage 24
nkx2-5.LAR2, csx, nkx-2.5, Nkx-2.5, nkx2.5, nkx2-5-a, nkx2-5-b, tinman, XNkx-2.5, XNkx2-5X. laevisSometime during NF stage 15 to NF stage 27mesoderm
cardiac mesoderm
heart primordium
pharyngeal arch
myocd.Lmyocardin, SRF cofactor proteinX. laevisThroughout NF stage 24heart
cardiac mesoderm
heart primordium
nkx2-5.LAR2, csx, nkx-2.5, Nkx-2.5, nkx2.5, nkx2-5-a, nkx2-5-b, tinman, XNkx-2.5, XNkx2-5X. laevisThroughout NF stage 24heart
cardiac mesoderm
heart primordium
myocd.Lmyocardin, SRF cofactor proteinX. laevisSometime during NF stage 24 to NF stage 27mesoderm
cardiac mesoderm
heart primordium
myh6.SaMHC, ck231, MHC, MHCa, MHC-alpha, MHCalpha, muz, muzak, XCMHCX. laevisThroughout NF stage 27heart primordium
heart
cardiac mesoderm
mrtfb.SLOC100301959, mkl2, MRTF-BX. laevisThroughout NF stage 27
mrtfa.Smkl1, MRTF-AX. laevisThroughout NF stage 27
myocd.Lmyocardin, SRF cofactor proteinX. laevisThroughout NF stage 42smooth muscle
alimentary system
dorsal aorta
myocd.Lmyocardin, SRF cofactor proteinX. laevisThroughout NF stage 45heart
outflow tract
myocardium
cardiac ventricle
left atrium

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