Mesodermal fate decisions of a stem cell: the Wnt switch

Stem cells are a powerful resource for cell-based transplantation therapies in osteodegenerative disorders, but before some kinds of stem cells can be applied clinically, several aspects of their expansion and differentiation need to be better controlled. Wnt molecules and members of the Wnt signaling cascade have been ascribed a role in both these processes in vitro as well as normal development in vivo. However some results are controversial. In this review we will present the hypothesis that both canonical and non-canonical signaling are involved in mesenchymal cell fate regulation, such as adipogenesis, chondrogenesis and osteogenesis, and that in vitro it is a timely switch between the two that specifies the identity of the differentiating cell. We will specifically focus on the in vitro differentiation of adipocytes, chondrocytes and osteoblasts contrasting embryonic and mesenchymal stem cells as well as the role of Wnts in mesenchymal fate specification during embryogenesis

Structure of the mouse 3-Methyladenine DNA Glycosylase gene and exact localization upstream of the α-globin gene cluster on Chromosome 11

In this paper we describe the genomic organization of the mouse 3-Methyladenine DNA Glycosylase (MPG) gene and localize three putative regulatory elements around this gene. The MPG gene plays a key role in the excision repair of methylated adenine residues and has been localized upstream of the α-globin gene cluster in human and mouse. The human MPG gene has been fully characterized, whereas up to now only the cDNA sequence of the mouse MPG gene had been published. Here, we describe a detailed restriction map, the intron/exon structure, the CpG-rich putative promoter sequence, and the exact localization of the mouse MPG gene with respect to the murine α-globin gene cluster. Our analysis reveals a remarkable different exon/intron structure of the mouse MPG gene compared with its human homolog. Two prominent DNase hypersensitive sites (HSS) were found 0.1 and 1.5 kb upstream of the coding sequence. In addition to these elements, an erythroid prominent HSS was mapped at the intron/exon boundary of the last exon. The characterization and localization of the MPG gene in mouse makes it now possible to carry out transgenic and gene targeting experiments and are essential to understand the control of gene expression of the MPG gene in particular and of the whole region in general

Characterization and localization of the mProx1 gene directly upstream of the mouse α-globin gene cluster: Identification of a polymorphic direct repeat in the 5′UTR

The α-globin major regulatory element (αMRE) positioned far upstream of the gene cluster is essential for the proper expression of the α-globin genes. Analysis of the human and mouse α-globin Upstream Flanking Regions (αUFR) has identified three nonglobin genes in the order Dist1-MPG-Prox1-α-globin. Further characterization of the whole region indicates that the αMRE and several other erythroid DNase HSSs are associated with the transcription unit of the Prox1 gene. In this paper we describe the characterization and localization of the mouse Prox1 cDNA and compare it with its human homolog, the -14 gene, and another human cDNA sequence named hProx1. Our results show a strong conservation between the -14 gene and the mouse Prox1 gene with the exception of the first exon of the mProx1 gene. This exon is absent in the -14 cDNA but is present and conserved in the human Prox1 cDNA, indicating that the human -14/hProx1 gene is alternatively spliced or transcribed. The mProx1 gene encodes a predicted protein of 491 amino acids (aa) whose function is not known. In the 5′UTR of this gene, a 35-bp repeat (VNTR) is positioned, which is highly polymorphic among laboratory inbred mice (Mus domesticus). Our results strongly suggest that the mProx1 VNTR arose during the divergence of M. spretus and M. domesticus. Besides its use in evolutionary studies and positional cloning, the mProx1 VNTR might be invaluable for monitoring the expression of a transgenic mProx1 gene. The cloning of the mProx1 gene will be helpful to analyze its possible role on α-globin as well on MPG expression in the mouse

A New Perspective on the Pb Isotopic Composition of Mars

New Pb isotope data for ALH 84001 and Nakhla has been collected via SIMS. These new data define highly accurate μ and κ values. Additionally, with the inclusion of previous solution analyses, a new age for ALH 84001 has been obtained

Do Lunar Impact Breccias Date Basin Forming Events?

Our research on the U-Pb ages of lunar phosphate grains on textually distinct breccias from Apollo 14 and 17 reveal different impact histories than previously suggested

Poverty amidst plenty: food insecurity in the United States

The United States faces domestic food security issues that differ from those encountered by many countries. Yet, in 2001, 10.7% of U.S. households were estimated to be food insecure at some point during the year. Food security, poverty, and food insecurity are strongly linked by economic conditions. Job transitions, layoffs, and family disruptions result in periods of low income and vulnerability to food insecurity. Economic and food assistance programs have helped protect many U.S. households when the market economy has failed to do so. These programs have reduced vulnerability to falling income and food insecurity during economic downturns in the business cycle. However effective food assistance programs have been for reducing short-term vulnerability, they do not enhance a household's ability to achieve sustainable food security. Prospects for improving long-term food security are tied to the same economic forces shaping a household's income and budget, particularly those related to labor productivity and wages. Copyright 2005 International Association of Agricultural Economics.