Postimplantation Mga expression and embryonic lethality of two gene-trap alleles.

Background: The dual-specificity T-box/basic helix-loop-helix leucine zipper transcription factor MGA is part of the MAX-interacting network of proteins. In the mouse, MGA is necessary for the survival of the pluripotent epiblast cells of the peri-implantation embryo and a null, gene-trap allele Mga results in embryonic lethality shortly after implantation. We have used this allele to document expression of Mga in postimplantation embryos and also investigated a second, hypomorphic gene-trap allele, Mga.

Integrated β-catenin, BMP, PTEN, and Notch signalling patterns the nephron.

The different segments of the nephron and glomerulus in the kidney balance the processes of water homeostasis, solute recovery, blood filtration, and metabolite excretion. When segment function is disrupted, a range of pathological features are presented. Little is known about nephron patterning during embryogenesis.

Detection of β-galactosidase activity: X-gal staining.

X-gal staining is a rapid and convenient histochemical technique used to detect reporter gene expression. A prerequisite is the creation or acquisition of transgenic reporter mouse lines, in which the bacterial LacZ gene has been knocked into the gene of interest or placed under the control of regulatory elements corresponding to the gene of interest. Expression is marked by a dark blue stain and can be detected at the single cell level, providing a robust visual readout of gene expression in the developing kidney.

A wt1-controlled chromatin switching mechanism underpins tissue-specific wnt4 activation and repression.

Wt1 regulates the epithelial-mesenchymal transition (EMT) in the epicardium and the reverse process (MET) in kidney mesenchyme. The mechanisms underlying these reciprocal functions are unknown. Here, we show in both embryos and cultured cells that Wt1 regulates Wnt4 expression dichotomously.

Left-right asymmetry in gut development: what happens next?

The gastrointestinal tract is an asymmetrically patterned organ system. The signals which initiate left-right asymmetry in the developing embryo have been extensively studied, but the downstream steps required to confer asymmetric morphogenesis on the gut organ primordia are less well understood. In this paper we outline key findings on the tissue mechanics underlying gut asymmetry, across a range of species, and use these to synthesise a conserved model for asymmetric gut morphogenesis.

High-efficiency Rosa26 knock-in vector construction for Cre-regulated overexpression and RNAi.

Introduction: Rosa26 is a genomic mouse locus commonly used to knock-in cDNA constructs for ubiquitous or conditional gene expression in transgenic mice. However, the vectors generally used to generate Rosa26 knock-in constructs show instability problems, which have a severe impact on the efficiency of the system.

Results: We have optimized the cloning procedure to generate targeting vectors for Cre-regulated expression of constructs within several days with minimal hands-on time, thereby enabling high-throughput approaches.

The dynamics of spleen morphogenesis.

The mammalian spleen has important functions in immunity and haematopoiesis but little is known about the events that occur during its early embryonic development. Here we analyse the origin of the cells that gives rise to the splenic mesenchyme and the process by which the precursors assume their position along the left lateral side of the stomach. We report a highly conserved regulatory element that regulates the Nkx2-5 gene throughout early spleen development.

Regulation of pigmentation in zebrafish melanophores.

In comparison with the molecular genetics of melanogenesis in mammals, the regulation of pigmentation in poikilothermic vertebrates is poorly understood. Mammals undergo morphological colour change under hormonal control, but strikingly, many lower vertebrates display a rapid physiological colour change in response to the same hormones. The recent provision of extensive genome sequencing data from teleost zebrafish, Danio rerio, provides the opportunity to define the genes and proteins mediating this physiological pigment response and characterise their function biologically.