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Biomedical subjects

M Burmeister

Publications and source records attributed to M Burmeister.

At least 55 records · Page 3Linked to original sources

The mouse glutathione peroxidase Gpx2 gene maps to chromosome 12; its pseudogene Gpx2-ps maps to chromosome 7.

The GPX2 gene codes for GSHPx-GI, a glutathione peroxidase whose mRNA is readily detectable in the gastrointestinal tract. Although GPX2 is a single gene in humans, there are two genes in the mouse genome with homology to GPX2. By analyzing a panel of mouse interspecies DNA from the Jackson Laboratory's backcross resource, we have chromosomally mapped these two genes. One was mapped to the central region of mouse chromosome 12 between D12Mit4 and D12Mit5, near fos and Tgfb3. This region is homologous to human 14q24.1, where human GPX2 has been mapped, and most likely represents the functional mouse Gpx2 gene. The other Gpx2-like gene was mapped to mouse chromosome 7 between Pcsk3 and Hbb. We have isolated the latter gene from a P1 phage library. Its pseudogene nature is revealed by the sequence analysis: (a) it is intronless; (b) it has a single nucleotide deletion in the coding region; and (c) it has a poly(A) tail at its 3'-untranslated region.

Amino Acid Sequence↗

Cloning and characterization of a novel transcriptional repressor of the nicotinic acetylcholine receptor delta-subunit gene.

We have identified a negative cis-acting regulatory element in the nicotinic acetylcholine receptor delta-subunit gene's promoter. This element resides within a previously identified 47-base pair activity-dependent enhancer. Proteins that bind this region of DNA were cloned from a lambdagt11 innervated muscle expression library. Two cDNAs (MY1 and MY1a) were isolated that encode members of the Y-box family of transcription factors. MY1/1a RNAs are expressed at relatively high levels in heart, skeletal muscle, testis, glia, and specific regions of the central nervous system. MY1/1a are nuclear proteins that bind specifically to the coding strand of the 47-base pair enhancer and suppress delta-promoter activity in a sequence-specific manner. These results suggest a novel mechanism of repression by MY1/1a, which may contribute to the low level expression of the delta-subunit gene in innervated muscle. Finally, the gene encoding MY1/1a, Yb2, maps to the mid-distal region of mouse chromosome 6.

Amino Acid Sequence↗

Ocular retardation mouse caused by Chx10 homeobox null allele: impaired retinal progenitor proliferation and bipolar cell differentiation.

Ocular retardation (or) is a murine eye mutation causing microphthalmia, a thin hypocellular retina and optic nerve aplasia. Here we show that mice carrying the OrJ allele have a premature stop codon in the homeobox of the Chx10 gene, a gene expressed at high levels in uncommitted retinal progenitor cells and mature bipolar cells. No CHX10 protein was detectable in the retinal neuroepithelium of orJ homozygotes. The loss of CHX10 leads both to reduced proliferation of retinal progenitors and to a specific absence of differentiated bipolar cells. Other major retinal cell types were present and correctly positioned in the mutant retina, although rod outer segments were short and retinal lamination was incomplete. These results indicate that Chx10 is an essential component in the network of genes required for the development of the mammalian eye, with profound effects on retinal progenitor proliferation and bipolar cell specification or differentiation. off

Alleles↗

Isolation and characterization of several members of the murine Hsd3b gene family.

The enzyme 3 beta-hydroxysteroid dehydrogenase (3 betaHSD) is essential for all steroid hormone biosynthesis. Six distinct 3 betaHSD cDNAs in the mouse (3 betaHSD I-VI) have been isolated previously. This study reports the isolation of genes or partial genes encoding the 3 betaHSDI, II, III, and IV isoforms. Characterization of the genes revealed that they consist of four exons, the same structure that has been observed for characterized human 3 betaHSD genes. Primer extension and nuclease S1 analysis identified the start sites of transcription of Hsd3b -1 and -4. The proximal promoter regions of Hsd3b-1 and -4 were sequenced and putative cis-acting sequences were determined. Previously, we reported that the then known 3 betaHSD genes (3 betaHSD I-IV) were located in a small region of mouse chromosome 3. To analyze this locus further, six yeast artificial chromosome clones containing the 3 betaHSD sequence were identified. One clone appears to contain the complete 3 betaHSD locus within its 1,400-kbp insert. Further analysis of this YAC, along with analysis of mouse genomic DNA by pulsed-field gel electrophoresis, suggests all members of the 3 betaHSD gene family may be contained on a 400-kbp fragment.

3-Hydroxysteroid Dehydrogenases↗

Chromosomal localization of the ankyrinG gene (ANK3/Ank3) to human 10q21 and mouse 10.

The ankyrin3 gene encodes a novel form of ankyrin, AnkyrinG, expressed in multiple tissues but characteristically present at the axonal initial segment and nodes of Ranvier of neurons in the central and peripheral nervous systems. We have localized ANK3 to human Chromosome 10q21 by fluorescence in situ hybridization. The position of the murine homologue was determined by intersubspecific backcross analysis, mapping Ank3 to mouse Chromosome 10, between microsatellite marker D10Mit31 and the Bcr gene. This interval is known to comprise a region syntenic to human 10q. The localization of ANK3 is a preliminary step in identifying neurological disorders potentially associated with the gene.

Animals↗

Genetic map of the region around grizzled (gr) and mocha (mh) on mouse chromosome 10, homologous to human 19p13.3.

Grizzled (gr) is a recessive mouse mutation resulting in a gray coat color and reduced perinatal viability. Mocha (mh) is one of several recessive mouse mutants characterized by platelet storage pool disorder, pigment abnormalities, reduced fertility, kidney function deficiencies, and, in some mutants, inner ear and natural killer cell deficiencies. Murine platelet storage pool deficient mutants may be models for Chediak-Higashi and Hermansky-Pudlak syndromes in humans. The genes for gr and mh are very closely linked to each other (0 +/- 1.2 cM). However, their relative position with respect to molecular markers was previously unknown. Thus, genetic mapping of the gr locus will also yield information about the mh location. To map these two genes genetically, we have performed an intersubspecific backcross of grizzled mice with Mus musculus castaneus. In 539 progeny tested, we found no recombination between the gr gene, the gene for anti-Muellerian hormone (Amh), and the microsatellite markers D10Mit7, D10Mit21, and D10Mit23. One recombination event for each of the flanking markers Basigin (Bsg) and D10Mit22 was identified. These closely linked markers should provide entry points for positional cloning of the gr and mh genes. The region linked to grizzled is homologous to a gene-rich region on human Chromosome 19p13.3.

Animals↗

Linkage analysis of idiopathic generalised epilepsy in families of probands with Juvenile Myoclonic Epilepsy and marker loci in the region of EPM 1 on chromosome 21 q: Unverricht-Lundborg disease and JME are not allelic variants.

The locus for Unverricht-Lundborg disease, EPM 1, has recently been mapped to chromosome 21q22.3. A locus, EJM 1, predisposing to idiopathic generalised epilepsy in families of probands with juvenile myoclonic epilepsy has been localised to chromosome 6p by evidence of linkage to the HLA region. However, segregation analysis suggests a two-locus model for JME and evidence has been obtained for genetic heterogeneity within the JME/IGE phenotype. EPM 1 was therefore investigated as a candidate locus in the set of families segregating for IGE and JME which do not show linkage to markers on chromosome 6p. Linkage analysis was carried out in 25 families using three microsatellite DNA markers around the EPM 1 gene region using different models of inheritance. Multipoint linkage analysis provided definite exclusion for 20cM around PFKL, the closet linked marker to EPM 1, under three out of four models tested. These results strongly suggest that the EPM 1 gene is not linked to the phenotype expressed in these families, and therefore that Unverricht-Lundborg disease and juvenile myoclonic epilepsy are not allelic variants.

Adolescent↗

Fluorescence in situ hybridization establishes the order cen-DXS28(C7)-DXS67(B24)-DXS68(L1)-tel in human chromosome Xp21.3.

We report here on the order of three DNA markers, C7, B24, and L1, based on the arrangement of their fluorescently labeled hybridization sites in interphase cell nuclei. The three markers map distal to the Duchenne muscular dystrophy (DMD), glycerol kinase deficiency (GKD), and adrenal hypoplasia (AHC) loci on human chromosome Xp21.3. Their order has been a matter of controversy. In interphase chromatin, B24 maps between C7 and L1. We estimate from interphase distance that C7 and L1 are 300-500 kb apart. When the three markers are hybridized to interphase cells of Nijmegen1, a patient with DMD, GKD, and AHC, only C7 appears to be deleted, rather than both C7 and L1, as had been reported elsewhere. C7 is also the only one of the three markers deleted in several other DMD patients studied by others. The deletion results indicate that C7 is the most proximal of the three markers and allow the trio of ordered probes to be oriented on the chromosome: cen-C7(DXS28)-B24(DXS67)-L1(DXS68)-tel.

DNA Probes↗