Project description:Genetic evidence has implicated several genes as being critical for heart development. However, the inducers of these genes as well as their other targets and the pathways they constitute, remain largely unknown. In the avian embryo, Cerberus (cCer) transcripts are detected in the anterior mesendoderm including the heart precursor cells and in the left lateral plate mesoderm. We have identified a promoter element of chick cCer able to drive EGFP expression into the heart and the hemangioblast precursor cells, allowing us to identify a population of cells that consistently exit from the anterior primitive streak region from as early as stage HH3+ and that later will populate the heart. In order to identify and study novel genes expressed and involved in the correct development and differentiation of the vertebrate H/HPC (Heart/ Hemangioblast Precursor Cells) lineages, a differential screening using Affymetrix GeneChip system technologies was performed. Remarkably, this screening led to the identification of more than 800 transcripts potentially expressed in these precursor lineages. We have identified unknown genes that are differentially expressed in the H/HPC precursor lineages. By developing a procedure to isolate the heart precursor cells using the cer2.5-EGFP construct, we were able to specifically isolate a population of H/HPC expressing already known cardiac markers, and a long list of still uncharacterized genes. From those, we defined by WISH that at least some of these in silico identified transcripts are in fact expressed in these cell populations and more importantly, functionally required for heart formation.More importantly, our study unveiled several uncharacterized genes that can now be used for further studies.
Project description:Genetic evidence has implicated several genes as being critical for heart development. However, the inducers of these genes as well as their other targets and the pathways they constitute, remain largely unknown. In the avian embryo, Cerberus (cCer) transcripts are detected in the anterior mesendoderm including the heart precursor cells and in the left lateral plate mesoderm. We have identified a promoter element of chick cCer able to drive EGFP expression into the heart and the hemangioblast precursor cells, allowing us to identify a population of cells that consistently exit from the anterior primitive streak region from as early as stage HH3+ and that later will populate the heart. In order to identify and study novel genes expressed and involved in the correct development and differentiation of the vertebrate H/HPC (Heart/ Hemangioblast Precursor Cells) lineages, a differential screening using Affymetrix GeneChip system technologies was performed. Remarkably, this screening led to the identification of more than 800 transcripts potentially expressed in these precursor lineages. We have identified unknown genes that are differentially expressed in the H/HPC precursor lineages. By developing a procedure to isolate the heart precursor cells using the cer2.5-EGFP construct, we were able to specifically isolate a population of H/HPC expressing already known cardiac markers, and a long list of still uncharacterized genes. From those, we defined by WISH that at least some of these in silico identified transcripts are in fact expressed in these cell populations and more importantly, functionally required for heart formation.More importantly, our study unveiled several uncharacterized genes that can now be used for further studies. Portions of chick embryos were selected and excised at early stages of development for RNA extraction and hybridization on Affymetrix microarrays. We sought to obtain homogeneous populations of embryos at early gastrula stage in order to increase the temporal resolution of expression profiles. To that end, we hand-selected and excised portions of the embryos according to morphological criteria and EGFP expression. Four GeneChip chicken arrays used for another study were added to the two arrays in this study to ensure a robust model for expression value computation (Note: The 4 samples chick_T2-1, chick_T2-2, chick_T2-3, chick_T2-4, were performed by another group and for a different array, and nothing has to do with our data. They were only run at the same time and used for normalization. Raw data unavailable.). The arrays were normalized to a baseline array with median CEL intensity by applying an Invariant Set Normalization Method. Normalized CEL intensities of the six arrays were used to obtain model-based gene expression indices (MBEI) based on a PM (Perfect Match)-only model. Processed data for all 6 samples can be found in supplementary file linked below.
Project description:Newly-hatched domestic chick serves as an important model for studies of neural and behavioral plasticity, particularly with respect to learning and memory such as filial imprinting. Imprinting is assumed to be a unique case of recognition learning with some characteristic features, such as sensitive period and irreversibility. However, the molecules involved in the memory process are yet to be fully identified. To address this issue, we attempted to identify the genes differentially expressed at an earlier phase of filial imprinting than described in our previous report (Brain Res. Bull.76, 275-281 (2008)). One-day-old chicks were trained for imprinting for 1 h and whole brains were collected and used for cDNA microarray analysis and quantitative RT-PCR. We identified 18 genes upregulated accompanying filial imprinting. These results suggested that the increase of these 18 genes associated with filial imprinting might play an important role in the acquisition of memory in the filial imprinting.
Project description:Hemangioblasts are known as the common precursors for primitive hematopoietic and endothelial lineages. Their existence has been supported mainly by the observation that both cell types develop in close proximity and by in vitro differentiation and genetic studies. However, more compelling evidence will arise from tracking their cell fates using a lineage-specific marker. We report the identification of a hemangioblast-specific enhancer (Hb) located in the cis-regulatory region of chick Cerberus gene (cCer) that is able to direct the expression of enhanced green fluorescent protein (eGFP) to the precursors of yolk sac blood and endothelial cells in electroporated chick embryos. Moreover, we present the Hb-eGFP reporter as a powerful live imaging tool for visualizing hemangioblast cell fate and blood island morphogenesis. We hereby introduce the Hb enhancer as a valuable resource for genetically targeting the hemangioblast population as well as for studying the dynamics of vascular and blood cell development. We used microarray analysis of Hb-eGFP expressing cells to verify the expression of hemangioblast-specific genes in this cell population.