Project description:We screened for differentially expressed genes in the developing notochord using the Affymetrix microarray system in Xenopus laevis. At late gastrula, we dissected four regions from the embryo, anterior mesoderm, posterior mesoderm, notochord and presomitic mesoderm. Three types of comparison were carried out to generate a list of predominantly notochord expressed genes: (1) Posterior mesoderm vs. anterior mesoderm; notochord genes are expected to be increased since the notochord is located in the posterior mesoderm. (2) Posterior mesoderm vs. whole embryos; notochord genes are expected to be increased. (3) Notochord vs. somite. This comparison sub-divided the group of posterior mesodermal genes identified in (1) and (2). All tissues are dissected using tungsten needles. We first dissected dorsal tissue above the archenteron from late gastrula to early neurula. To loosen tissue, we treated the dissected dorsal explant in a 1% cysteine solution (pH 7.4) and removed the neuroectodermal layer. Anterior mesoderm was dissected corresponding to about the anterior one-third of the archenteron roof, and the rest was collected as posterior mesoderm. The posterior mesodermal explant was dissected into notochord and somites, following a clearly visible border between the two tissues. The accuracy of all dissection was confirmed by RT-PCR of marker genes.
Project description:Renal precusors of the Xenopus pronephros arise from dorso-lateral mesoderm at the early neurula stage. This process is under the control of retinoic acid (RA). We have used microarrays to identify RA targets in dorso-latearl mesoderm by performing differential expression analysis between control and RA-depleted situations
Project description:Left-right axis determination is a fundamental and conserved developmental process, with consequences for human pathology. At the molecular level, this process requires at least two centers of nodal-type TGFbeta signals: the first center, containing nodal/Xn; Microarrays were used to determine differences in gene expression in posterior mesoderm of Xenopus embryos. We compared controls and Derriere depleted embryos. Experiment Overall Design: Microarrays were used to determine differences in gene expression in posterior mesoderm of Xenopus embryos. We compared controls and embryos depleted of Derriere protein using MO oligonucleotides.
Project description:The response of ectodermal explants, neuralized by noggin and treated with cycloheximide, following activation of hormone-inducible zic1 injected into the parent embryos compared to those from beta globin injected embryos as controls, is expected to provide information on the direct targets of the Zic1 transcription factor. Experiment Overall Design: Activation of zic1 in ectodermal explants following inhibition of new protein synthesis allowed the direct targets of zic1 to be identified by comparison with controls. After RNA extraction, purification and checks with PCR with actin primers for any mesoderm contamination samples were prepared for hybridization to Xenopus laevis Affymetrix GeneChip arrays.
Project description:The canonical Wnt/β-catenin signaling pathway plays multiple roles during Xenopus gastrulation, including posteriorization of the neural plate, patterning of the mesoderm, and induction of the neural crest. Wnt signaling stabilizes β-catenin, which then activates target genes. However, few targets of this signaling pathway that mediate early developmental processes are known. Here we sought to identify transcriptional targets of the Wnt/β-catenin signaling pathway using a genome-wide approach.
Project description:Left-right axis determination is a fundamental and conserved developmental process, with consequences for human pathology. At the molecular level, this process requires at least two centers of nodal-type TGFbeta signals: the first center, containing nodal/Xn Microarrays were used to determine differences in gene expression in posterior mesoderm of Xenopus embryos. We compared controls and Derriere depleted embryos. Keywords: loss of function