Study of the expression patterns of genes involved in heart formation in vertebrate embryos

Correia, Elizabeth Christine Baptista

http://hdl.handle.net/10400.1/721

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Authors

Correia, Elizabeth Christine Baptista

Advisor(s)

Belo, José António

Abstract(s)

During gastrulation myocardial progenitor cells, derivatives of the epiblast, ingress into the primitive streak. After ingression into the primitive streak, myocardial progenitor cells move rapidly craniolaterally in a semilunar fashion and slow down during the most lateral part of their trajectory as they assume residence in the lateral plate mesoderm. After relocation of the myocardial progenitor cells within the lateral plate mesoderm, this tissue splits into two layers, the splanchnic and the somatic mesoderm. A differential screening using Affymetrix GeneChip® system technologies was undertaken (by M. Bento) to identify genes that are specifically expressed during early cardiac development, by using the avian embryo as an experimental system and the already characterized 2.5CarEGFP construct (by A. Tavares). This construct was shown to be able to drive the expression of EGFP into the cell populations that express Car, such as the anterior endoderm, lateral plate mesoderm and heart. These EGFP+ cells were isolated, and a differential screening of this population was made that led to the identification of more than 800 new genes potentially expressed in these haematopoesis, angiogenesis or cardiogenesis precursor lineages. The study of the expression patterns of two novel genes, named clones 12 and 18, obtained in the previously described screening for differentially expressed genes of a heart/ hemangioblast percursor cell population, was performed. An upstream chick genomic search was made in NCBI and Ensembl databases, in order to discover clone 12 putative full length transcript since the available EST did not contain a start codon. In this study the potential alternative splice variants of clone 12, and the cloning of one of its prospective coding sequences is described. The obtained results allow us to suggest that clone 18 might be implicated in vasculogenesis, and clone 12 possibly involved in cardiogenic/hematopoietic processes.