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Formation of the vertebrate heart requires a complex interplay of several temporally regulated signalling cascades. In Xenopus laevis, cardiac specification occurs during gastrulation and requires signals from the dorsal lip and underlying endoderm. Among known Xenopus Wnt genes, only Wnt-11 shows a spatiotemporal pattern of expression that correlates with(More)
Wnt ligands and Frizzled (Fz) receptors have been shown to activate multiple intracellular signaling pathways. Activation of the Wnt-beta-catenin pathway has been described in greatest detail, but it has been reported that Wnts and Fzs also activate vertebrate planar cell polarity (PCP) and Wnt-Ca2+ pathways. Although the intracellular protein Dishevelled(More)
Six genes are homeobox-containing transcription factors, many of which are expressed in head structures. We isolated a full-length cDNA of a previously unknown Xenopus member of this family. It shares a high sequence homology with mouse and human Six1, which during development are expressed in mesoderm and muscle. In contrast, XSix1 is prominently expressed(More)
Adult mammalian cardiac stem cells express the LIM-homeodomain transcription factor Islet1 (Isl1). They are considered remnants of Isl1-positive embryonic cardiac progenitor cells. During amniote heart development, Isl1-positive progenitor cells give rise mainly to the outflow tract, the right ventricle, and parts of the atria. This led to the hypothesis(More)
FHL2 is a LIM-domain protein expressed in myoblasts but down-regulated in malignant rhabdomyosarcoma cells, suggesting an important role of FHL2 in muscle development. To investigate the importance of FHL2 during myoblast differentiation, we performed a yeast two-hybrid screen using a cDNA library derived from myoblasts induced for differentiation. We(More)
Popeye genes code for putative transmembrane proteins that are predominantly expressed in heart and skeletal muscle. Here we report on the isolation and expression of a previously unknown Xenopus member of this family, Xenopus Popeye-1 (Xpop-1). Xpop-1 is 60-65% identical to other vertebrate Pop-1 genes at the protein level. Whole-mount in situ(More)
The two paralogues of the Xenopus flotillin1 gene (flotillin1A and flotillin1B), which encodes a putative membrane-associated protein, were cloned from egg, cleavage, and tadpole cDNA libraries. Both mRNAs are present during oogenesis and cleavage stages. After the onset of zygotic transcription, flotillin1 transcripts are first expressed throughout the(More)
Molecular asymmetries in the animal-vegetal axis of the Xenopus oocyte are well known to regulate the formation of gametes and germ layers. Likewise, many transplantation and explant studies demonstrate that maternal dorsalizing activities are localized to the future dorsal side of the embryo after fertilization, but to date only a few of the molecules(More)
Aging tissue is characterized by a continuous decline in functional ability. Adult stem cells are crucial in maintaining tissue homeostasis particularly in tissues that have a high turnover rate such as the intestinal epithelium. However, adult stem cells are also subject to aging processes and the concomitant decline in function. The Drosophila midgut has(More)
Drosophila heart development is an invaluable system to study the orchestrated action of numerous factors that govern cardiogenesis. Cardiac progenitors arise within specific dorsal mesodermal regions that are under the influence of temporally coordinated actions of multiple signaling pathways. The Drosophila Iroquois complex (Iro-C) consists of the three(More)