CpG island promoter region methylation patterns of the inactive-X-chromosome hypoxanthine phosphoribosyltransferase (Hprt) gene.

Inactive-X-chromosome genes in mammalian females have methylated CpG islands. We have questioned whether there are variable levels of cytosine methylation at different CpG sites within the island that might indicate the presence of primary sites of methylation which may be critical for the maintenance of gene repression and candidate sites for the initiation of inactivation. To address these questions, we have analyzed the methylation patterns of 32 CpG sites of the X-linked hypoxanthine phosphoribosyltransferase (Hprt) gene on the active and inactive X chromosomes of mouse tissues and cell lines, using genomic sequencing of bisulfite-treated genomic DNA.

Linkage of phosphoribosylpyrophosphate synthetases 1 and 2, Prps1 and Prps2, on the mouse X chromosome.

The X Chromosome (Chr) genes for phosphoribosylpyrophosphate synthetases 1 and 2, Prps1 and Prps2, were mapped on the mouse X Chr with interspecific backcrosses between C57BL/6 (B6) and M. spretus (S). Southern analysis showed that Prps1 mapped between Plp and DXWas31, a mouse X Chr region that is homologous to Xq21-24 on the human X Chr while Prps2 mapped between DXWas31 and Amg, a region that is homologous to the map position of PRPS2 on Xp22 of the human X Chr.

Bi-directional effects of intrathecal NMDA and substance P on rat dorsal horn neuronal responses.

Intrathecal NMDA (5 ng) facilitated wind-up but not C-fibre evoked responses, whereas 50 ng facilitated C-fibre and A delta-fibre evoked responses but not wind-up of convergent dorsal horn neurones in the halothane anaesthetized rat. Higher doses of NMDA and SP (10-500 ng) were without effect. Co-administered SP (10 ng) with NMDA (5 ng) facilitated A delta-fibre evoked responses and wind-up.

The murine Xe169 gene escapes X-inactivation like its human homologue.

Among a number of genes that escape X-chromosome inactivation in humans, three have been evaluated in mice and unexpectedly all three are subject to X-inactivation. We report here the cloning and expression studies of a novel mouse gene, Xe169, and show that it escapes X-inactivation like its human homologue. Xe169 was assigned to band F2/F3 on the mouse X chromosome by fluorescent in situ hybridization and Southern analysis indicates that the gene is located outside the pseudoautosomal region.

Enhanced responses of rat dorsal horn neurons after UV irradiation of the hindpaw; roles of the NMDA receptor.

Recordings were made from nociceptive dorsal horn neurones in the anaesthetized rat 3 and 5 days after ultraviolet (UV) irradiation of the hindpaw. The electrically evoked A beta-fibre-evoked responses from the paw were enhanced and their thresholds were lowered. Spontaneous neuronal activity was increased but the C-fibre-evoked responses were unaltered.

Mapping of the X-linked cataract (Xcat) mutation, the gene implicated in the Nance Horan syndrome, on the mouse X chromosome.

The Xcat mutation in the mouse, an X-linked inherited disorder, is characterized by the congenital onset of cataracts. The cataracts have morphologies similar to those of cataracts found in the human Nance Horan (X-linked cataract dental) syndrome, suggesting that Xcat is an animal model for Nance Horan. The Xcat mutation provides an opportunity to investigate, at the molecular level, the pathogenesis of cataract.

Mouse rump-white mutation associated with an inversion of chromosome 5.

The rump-white (Rw) mutation in the mouse was previously mapped as part of a cluster of spotting genes on Chromosome (Chr) 5 that includes the dominant spotting (W) and patch (Ph) loci. Recent studies have shown that the W locus encodes the KIT tyrosine kinase cell surface receptor and that Ph is a deletional mutation encompassing the platelet-derived growth factor receptor alpha subunit (Pdgfra) gene. However, the molecular basis of the Rw mutation remains to be established.

Generation of five high-complexity painting probe libraries from flow-sorted mouse chromosomes.

Mouse metaphase chromosomes were purified by flow sorting from the murine fibroblast cell line Mus spretus clone 5A. We sorted chromosomes that fell into five individual peaks based on the Hoechst 33258/chromomycin A3 DNA histogram: three peaks corresponding to the least amount of DNA and two peaks representing chromosomes with the most DNA content. This is the first example of the successful application of bivariate flow karyotyping to murine chromosome sorting.

Interspecific backcrosses provide an important new tool for centromere mapping of mouse chromosomes.

Centromere mapping of mouse chromosomes has been problematic due to a paucity of appropriate markers. As a result, the mapping of centromeres has most often relied on the use of Robertsonian chromosomes to mark chromosome ends. Many Robertsonian translocations have been shown to suppress recombination in pericentric regions; therefore, centromere mapping data generated by using Robertsonian chromosomes must be interpreted with caution.

Chromosomal mapping of mouse 5S rRNA genes by direct R-banding fluorescence in situ hybridization.

The mouse 5S rRNA gene was mapped by direct R-banding fluorescence in situ hybridization (FISH) with biotinylated probes. Two genomic fragments amplified by PCR from total genomic DNA of BALB/c mice and Mus spretus, a 0.16-kb fragment that included the 121-bp 5S rRNA gene and a 1.

Direct determination of NotI cleavage sites in the genomic DNA of adult mouse kidney and human trophoblast using whole-range restriction landmark genomic scanning.

Restriction landmark genomic scanning (RLGS) is a method for visualizing restriction landmarks, employing direct labeling of restriction sites of genomic DNA and high-resolution two-dimensional electrophoresis. We determined the conditions for both the first and second dimensions of RLGS that define all of the restriction fragments which carry the NotI landmark. Using this system, we determined the number of cleavable NotI sites of genomic DNA from the mouse kidney (C57BL/6) and from the human placenta.

Deconjugation of bilirubin-IX alpha glucuronides: a physiologic role of hepatic microsomal beta-glucuronidase.

beta-Glucuronidase is an acid hydrolase located in both the lysosomal and microsomal compartments of the hepatocyte. The function of the latter remains undefined. We postulated that microsomal beta-glucuronidase may be responsible for the deconjugation of bilirubin-IX alpha glucuronides which are synthesized primarily in the hepatic microsomal compartment.

In situ analysis of centromere segregation in C57BL/6 x Mus spretus interspecific backcrosses.

The analysis of major satellite sequence differences between Mus spretus and laboratory mice provides a robust method for analyzing the centromere location for the genetic maps of each mouse chromosome. Fluorescence in situ hybridization (FISH) of a genomic probe, pMR196, for the laboratory mouse major satellite sequences was used to identify C57BL/6Ros (B6) pericentromeric heterochromatin in progeny of reciprocal backcross matings. These included 80 (B6 x M.

The effect of intrathecal administration of RP67580, a potent neurokinin 1 antagonist on nociceptive transmission in the rat spinal cord.

The effect of intrathecal application of the selective neurokinin 1 (NK1) receptor antagonist RP67580 and its enantiomer RP68651 was studied on the responses of dorsal horn nociceptive neurones to formalin in the rat. The first and second phases of the formalin response were inhibited by RP67580 in a dose-related manner (1-10 micrograms), whereas RP68651 (5 micrograms) facilitated the second phase of the response. The same doses of RP67580 had minimal effects on the acute C-fibre responses.

Colocalization of X-linked agammaglobulinemia and X-linked immunodeficiency genes.

Mice that bear the X-linked immunodeficiency (xid) mutation have a B lymphocyte-specific defect resulting in an inability to make antibody responses to polysaccharide antigens. A backcross of 1114 progeny revealed the colocalization of xid with Bruton's agammaglobulinemia tyrosine kinase (btk) gene, which is implicated in the human immune deficiency, X-linked agammaglobulinemia. Mice that carry xid have a missense mutation that alters a highly conserved arginine near the amino-terminus of the btk protein, Btk.

New mdx mutation disrupts expression of muscle and nonmuscle isoforms of dystrophin.

The dystrophin gene encodes several tissue-specific protein isoforms that are generated by alternative splicing and by transcription from at least three separate promoters. We have characterized the mutation in a new strain of mdx mice that results in aberrant splicing of both the 14 and 4.8 kilobase dystrophin mRNAs and disrupts expression of the muscle and brain 427K and nonmuscle 70K isoforms of dystrophin.

Improving diabetes care for American Indians.

In 1986, a diabetes control program was implemented in the Billings area of the IHS. Baseline health-care practices in the program were described using a structured audit. The program included adoption of the IHS Minimum Standards of Care for diabetes, technical assistance, and professional and patient education.

Close physical linkage of the FLT1 and FLT3 genes on chromosome 13 in man and chromosome 5 in mouse.

Receptor-type tyrosine kinases (RTK) with five or seven immunoglobulin-like domains in their extracellular region are encoded by genes grouped in clusters. In human, two such clusters have been individualized, in chromosomal regions 4q11-q12 and 5q33-qter respectively. We define here a third cluster located on chromosome 13q and containing two contiguous RTK genes, FLT1 and FLT3.