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BACKGROUND The developing mouse limb is widely used as a model system for studying tissue patterning. Despite this, few references are available that can be used for the correct identification of developing limb structures, such as muscles and tendons. Existing textual references consist of two-dimensional (2D) illustrations of the adult rat or mouse limb(More)
Muscle gene expression is induced a few hours after vegetal cells of a Xenopus blastula are placed in contact with animal cells that normally develop into epidermis and nerve cells. We have used a muscle-specific actin gene probe to determine the timing of gene activation in animal-vegetal conjugates. Muscle actin RNA is first transcribed in a minority of(More)
Phagocytic myeloid cells provide the principle line of immune defence during early embryogenesis in lower vertebrates. They may also have important functions during normal embryo morphogenesis, not least through the phagocytic clearance of cell corpses arising from apoptosis. We have identified two cDNAs that provide sensitive molecular markers of embryonic(More)
Episcopic fluorescence image capturing (EFIC) and high-resolution episcopic microscopy (HREM) are related techniques that are used to generate digital volume data and create three-dimensional (3D) images. Both techniques require specimens that are embedded in an appropriate medium, and images are captured from successive sections before removal from the(More)
Muscle actin genes are the earliest yet described to show cell type-specific activation in amphibian embryos. Gene-specific probes show that alpha-skeletal and alpha-cardiac actin genes start to be transcribed simultaneously at the end of gastrulation, but only in those regions of the mesoderm that subsequently form embryonic muscle. Their expression(More)
The bHLH protein eHAND is a sensitive marker for cardiovascular precursors in the Xenopus embryo. The earliest site of expression is a broad domain within the lateral plate mesoderm of the tailbud embryo. This domain comprises precursors that contribute to the posterior cardinal veins in later stages. Surprisingly, expression is profoundly asymmetric at(More)
The Smads are intracellular signalling molecules that transduce signals from receptors for members of the TGF-beta superfamily to the nucleus. We have cloned the Xenopus orthologue of Smad3 (XSmad3). It is 94.6% identical to human Smad3 at the amino acid level. It is expressed as a maternal mRNA which disappears after stage 10.5, but reappears at the early(More)
The yeast UBC9 gene encodes a protein with homology to the E2 ubiquitin-conjugating enzymes that mediate the attachment of ubiquitin to substrate proteins [1]. Depletion of Ubc9p arrests cells in G2 or early M phase and stabilizes B-type cyclins [1]. p18(Ubc9), the Xenopus homolog of Ubc9p, associates specifically with p88(RanGAP1) and p340(RanBP2) [2].(More)
This chapter describes two episcopic imaging methods, episcopic fluorescence image capturing (EFIC) and high-resolution episcopic microscopy (HREM). These allow analysis of molecular signals in a wide variety of biological samples such as tissues or embryos, in their precise anatomical and histological context. Both methods are designed to work with(More)
Cloned cDNA probes that recognize muscle-specific alpha-actin gene transcripts have been used to analyze two kinds of experimental embryos in Xenopus. In one, genetically marked nuclei of larval muscle cells were transplanted to wild-type enucleated eggs; alpha-actin genes became transcriptionally inactive in the resulting blastulae but were reactivated(More)