Neural crest survival and differentiation in zebrafish depends on mont blanc/tfap2a gene function.

Neural crest progenitor cells are the main contributors to craniofacial cartilage and connective tissue of the vertebrate head. These progenitor cells also give rise to the pigment, neuronal and glial cell lineages. To study the molecular basis of neural crest differentiation, we have cloned the gene disrupted in the mont blanc (mob(m610)) mutation, which affects all neural crest derivatives.

mPet-1, a mouse ETS-domain transcription factor, is expressed in central serotonergic neurons.

Here we describe the expression pattern of a previously unknown mouse gene mPet-1. The isolated cDNA codes for an ETS-domain transcription factor of 237 amino acids in length, which is localized to the nucleus. mPet-1 is a member of the winged helix transcription factor gene family like its rat homologue Pet-1 and the human homologue FEV.

Spatio-temporal distribution of chondromodulin-I mRNA in the chicken embryo: expression during cartilage development and formation of the heart and eye.

To define genes specifically expressed in cartilage and during chondrogenesis, we compared by differential display-polymerase chain reaction (DD-PCR) the mRNA populations of differentiated sternal chondrocytes from chicken embryos with mRNA species modulated in vitro by retinoic acid (RA). Chondrocyte-specific gene expression is downregulated by RA, and PCR-amplified cDNAs from both untreated and RA-modulated cells were differentially displayed. Amplification products only from RNA of untreated chondrocytes were further analyzed, and a cDNA-fragment of the chondromodulin-I (ChM-I) mRNA was isolated.

Characterization of the HSD17B4 gene: D-specific multifunctional protein 2/17beta-hydroxysteroid dehydrogenase IV.

The HSD17B4 gene codes for a 80 kDa multifunctional enzyme containing three distinct functional domains and is localized in peroxisomes. The N-terminal part exhibits 3-hydroxyacyl-CoA dehydrogenase and 17beta-hydroxysteroid dehydrogenase activity whereas the central part shows enoyl-CoA hydratase activity. The carboxy-terminal part of the protein has sterol-carrier-protein activity.

Teeth. Where and how to make them.

Organs have to develop at precisely determined sites to ensure functionality of the whole organism. Organogenesis is typically regulated by a series of interactions between morphologically distinct tissues. The developing tooth of the mouse is an excellent model to study these processes and we are beginning to understand the networks regulating reciprocal tissue interactions at the molecular level.

Pax9-deficient mice lack pharyngeal pouch derivatives and teeth and exhibit craniofacial and limb abnormalities.

Pax genes have been shown to play important roles in mammalian development and organogenesis. Pax9, a member of this transcription factor family, is expressed in somites, pharyngeal pouches, mesenchyme involved in craniofacial, tooth, and limb development, as well as other sites during mouse embryogenesis. To analyze its function in vivo, we generated Pax9 deficient mice and show that Pax9 is essential for the development of a variety of organs and skeletal elements.

Pax genes and organogenesis: Pax9 meets tooth development.

Pax genes encode a family of transcription factors that play key roles during embryogenesis. They are required for the development of a variety of organs including the nervous and muscular system, skeleton, eye, ear, kidney, thymus, and pancreas. Whereas the developmental roles of many of the nine known Pax genes have been analyzed in great detail, a functional analysis of Pax9 has just begun.

Molecular, genetic and biochemical characterization of lactate dehydrogenase-A enzyme activity mutations in Mus musculus.

Four independent heterozygous lactate dehydrogenase (LDH) mutations with approximately 60% of wild-type enzyme activity in whole blood have been recovered. The mutant line Ldh1a2Neu proved to be homozygous lethal, whereas for the three lines Ldh1a7Neu, Ldh1a11Neu, and Ldh1a12Neu homozygous mutants with about 20% residual activity occurred in the progeny of heterozygous inter se matings. However, the number of homozygous mutants was less than expected, suggesting an increased lethality of these animals.

Segment-specific expression of the gap junction gene connexin31 during hindbrain development.

 During segmentation of the mouse hindbrain (d8.0-8.5 pc), expression of the gap junction gene connexin31 (cx31) is precisely restricted to rhombomeres (r) 3 and 5.

Pax genes and organogenesis.

Pax genes are a family of developmental control genes that encode nuclear transcription factors. They are characterized by the presence of the paired domain, a conserved amino acid motif with DNA-binding activity. Originally, paired-box-containing genes were detected in Drosophila melanogaster, where they exert multiple functions during embryogenesis.