Identification and targeted disruption of the mouse gene encoding ESG1 (PH34/ECAT2/DPPA5)

Background  

Embryonic stem cell-specific gene (ESG) 1, which encodes a KH-domain containing protein, is specifically expressed in early embryos, germ cells, and embryonic stem (ES) cells. Previous studies identified genomic clones containing the mouse ESG1 gene and five pseudogenes. However, their chromosomal localizations or physiological functions have not been determined.     

<Emphasis Type="Italic">Cdkn1c</Emphasis> (<Emphasis Type="Italic">p57</Emphasis><Superscript><Emphasis Type="Italic">Kip2</Emphasis></Superscript>) is the major regulator of embryonic growth within its imprinted domain on mouse distal chromosome 7

Background  

Cdkn1c encodes an embryonic cyclin-dependant kinase inhibitor that acts to negatively regulate cell proliferation and, in some tissues, to actively direct differentiation. This gene, which is an imprinted gene expressed only from the maternal allele, lies within a complex region on mouse distal chromosome 7, called the IC2 domain, which contains several other imprinted genes. Studies on mouse embryos suggest a key role for genomic imprinting in regulating embryonic growth and this has led to the proposal that imprinting evolved as a consequence of the mismatched contribution of parental resources in mammals.     

<Emphasis Type="Italic">Dppa3 / Pgc7 / stella</Emphasis> is a maternal factor and is not required for germ cell specification in mice

Background  

In mice, germ cells are specified through signalling between layers of cells comprising the primitive embryo. The function of Dppa3 (also known as Pgc7 or stella), a gene expressed in primordial germ cells at the time of their emergence in gastrulating embryos, is unknown, but a recent study has claimed that it plays a central role in germ cell specification.     

The level of BMP4 signaling is critical for the regulation of distinct T-box gene expression domains and growth along the dorso-ventral axis of the optic cup

Background  

Polarised gene expression is thought to lead to the graded distribution of signaling molecules providing a patterning mechanism across the embryonic eye. Bone morphogenetic protein 4 (Bmp4) is expressed in the dorsal optic vesicle as it transforms into the optic cup. Bmp4 deletions in human and mouse result in failure of eye development, but little attempt has been made to investigate mammalian targets of BMP4 signaling. In chick, retroviral gene overexpression studies indicate that Bmp4 activates the dorsally expressed Tbx5 gene, which represses ventrally expressed cVax. It is not known whether the Tbx5 related genes, Tbx2 and Tbx3, are BMP4 targets in the mammalian retina and whether BMP4 acts at a distance from its site of expression. Although it is established that Drosophila Dpp (homologue of vertebrate Bmp4) acts as a morphogen, there is little evidence that BMP4 gradients are interpreted to create domains of BMP4 target gene expression in the mouse.     

Transcription profiling of fertilization and early seed development events in a solanaceous species using a 7.7 K cDNA microarray from <Emphasis Type="Italic">Solanum chacoense</Emphasis>ovules

Background  

To provide a broad analysis of gene expression changes in developing embryos from a solanaceous species, we produced amplicon-derived microarrays with 7741 ESTs isolated from Solanum chacoense ovules bearing embryos from all developmental stages. Our aims were to: 1) identify genes expressed in a tissue-specific and temporal-specific manner; 2) define clusters of genes showing similar patterns of spatial and temporal expression; and 3) identify stage-specific or transition-specific candidate genes for further functional genomic analyses.     

Specific expression of lacZ and cre recombinase in fetal thymic epithelial cells by multiplex gene targeting at the <Emphasis Type="Italic">Foxn1</Emphasis> locus

Background  

Thymic epithelial cells (TECs) promote thymocyte maturation and are required for the early stages of thymocyte development and for positive selection. However, investigation of the mechanisms by which TECs perform these functions has been inhibited by the lack of genetic tools. Since the Foxn1 gene is expressed in all presumptive TECs from the early stages of thymus organogenesis and broadly in the adult thymus, it is an ideal locus for driving gene expression in differentiating and mature TECs.     

Targeted disruption of the mouse phospholipase C β3 gene results in early embryonic lethality

In order to investigate the biological function of phosphatidylinositol-specific phospholipase C (PLC) we generated mutant mice by gene targeting. Homozygous inactivation of PLCβ₃ is lethal at embryonic day 2.5. These mutants show poor embryonic organization as well as reduced numbers of cells. Identical phenotypes were recorded in homozygous mutants generated from two independently targeted embryonic stem cell clones. Heterozygous mutant mice, however, are viable and fertile for at least two generations. We also showed that mouse PLCβ₃ is expressed in unfertilized eggs, 3-cell and egg cylinder stages of embryos. In conclusion, these results indicate that PLCβ₃ expression is essential for early mouse embryonic development.     

Inactivation of <Emphasis Type="Italic">Dicer1</Emphasis> in Steroidogenic factor 1-positive cells reveals tissue-specific requirement for <Emphasis Type="Italic">Dicer1</Emphasis>in adrenal,testis, and ovary

Background  

The synthesis of microRNA (miRNA) is a multi-step process that requires the action of the ribonuclease Dicer1. Dicer1 is responsible for the final processing of miRNA and has been implicated in cellular processes such as proliferation, apoptosis, and differentiation. Mouse embryos lacking Dicer1 die in early embryogenesis. In this study, we investigated whether Dicer1 is required for development of adrenal, testis, and ovary in mouse embryos.     

Fast identification of folded human protein domains expressed in <Emphasis Type="Italic">E. coli</Emphasis> suitable for structural analysis

Background  

High-throughput protein structure analysis of individual protein domains requires analysis of large numbers of expression clones to identify suitable constructs for structure determination. For this purpose, methods need to be implemented for fast and reliable screening of the expressed proteins as early as possible in the overall process from cloning to structure determination.