Report of the Second International Workshop on Human Chromosome 6.
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Centromere↗
Biomedical subjects
A Volz
Publications and source records attributed to A Volz.
Exclusion of ferritins and iron-responsive element (IRE)-binding proteins as candidates for the hemochromatosis gene.
We have looked for genes for ferritin and its translational control protein that could account for anomalies in the expression of ferritin (FT) and the transferrin receptor in the duodenum of individuals with hemochromatosis (HC). We show that there are probably only two FTH-like sequences near the HC locus on the short arm of chromosome 6 and no FTL-like sequences. We report the cloning of the previously uncharacterized FTH sequence from 6p (FTHL15) and show that it is probably a processed pseudogene. This gene has been mapped with a panel of radiation hybrid cells to near 6p12. Additionally, we show that there are no sequences on chromosome 6p for a protein that coordinately regulates expression of ferritin and the transferrin receptor.
Animals↗
Presence of an expressed beta-tubulin gene (TUBB) in the HLA class I region may provide the genetic basis for HLA-linked microtubule dysfunction.
An expressed beta-tubulin gene (TUBB) has previously been localized to chromosome region 6pter-p21 in man. By using a panel of deletion mutant cell lines and radiation-reduced hybrids containing fragments of chromosome 6, the TUBB locus could be mapped to the HLA class I region at 6p21.3. A long range restriction map including TUBB and several HLA class I genes was then generated by rotating field gel electrophoresis. The results show that TUBB maps to a segment 170-370 kb telomeric of HLA-C. This location suggests that a mutation at the TUBB locus could be the cause for certain forms of HLA-linked microtubule dysfunction, including immotile cilia syndrome.
Animals↗
Physical mapping of a functional cluster of epidermal differentiation genes on chromosome 1q21.
Genes of three protein families, which are in part specifically expressed in the course of terminal differentiation of human epidermis, have previously been mapped to chromosome 1q21. Here we show that these genes are physically linked within 2.05 Mb of DNA. The order is calpactin I light chain, trichohyalin, profilaggrin, involucrin/small proline-rich protein, loricrin, and calcyclin. The colocalization in the 1q21 region together with their functional interdependence during epidermal differentiation raises the question whether these genes share regulatory elements which control their transcriptional activities. As several of them are potential candidate genes for dyskeratotic skin diseases, this physical map should be of great value for genetic linkage analyses.
Annexins↗
A cosmid library specific for human chromosome regions 6p21.3 and 6q27.
We have explored the potential of irradiation-fusion gene transfer (IFGT) hybrids as a source of well-defined human chromosome fragments from which probes can be derived. Extensive characterization of the IFGT hybrid 4J4 with a full panel of markers from Chromosome (Chr) 6 showed that the human DNA content derives largely from 6p21.3 and 6q27. A cosmid library has been constructed from 4J4 DNA, and 370 recombinants containing human DNA have been isolated and overlapping clones ordered into 20 contigs. Regional localization of representative clones from each contig, determined by fluorescent in situ hybridization (FISH), places 13 contigs in 6q27 and 6 in 6p21.3. Preliminary screening of cDNA libraries with selected cosmids has identified two expressed sequences. Since there are a number of medically important genes in both these regions of human Chr 6 with several disease loci linked to the HLA-A region in 6p21.3 and various tumor suppressor genes to 6q27, this library will provide a valuable resource to aid the isolation of candidate genes for these diseases. In addition, unique markers for detailed physical and genetic mapping of these regions of human Chr 6 can be easily obtained.
Base Sequence↗
Regulation of CD18 expression in human neutrophils as related to shape changes.
The study analyses the distribution and quantitative expression of surface CD18 of neutrophils exposed to distinct stimuli that produce different types of continuous shape changes, including types that are associated with locomotion and others that are not. The chemotactic peptide N-formyl-L-norleucyl-L-leucyl-L-phenylalanine, colchicine and nocodazole were used to induce a polarized locomotor morphology, phorbol myristate acetate, 1,2-dioctanoylglycerol and 1-oleoyl-2-acetyl-glycerol to induce non-polar motile cells ruffling all over the surface and 2H2O to induce non-polar cells performing circus movements as have been previously described. Except for colchicine and nocodazole, these stimuli increased surface expression of CD18. Thus, stimulated shape changes are frequently, though not always, associated with increased surface expression of CD18. High concentrations (10(-7) to 10(-5) M) of phorbol myristate acetate but not of chemotactic peptide induced down-regulation of surface CD18. Cytochalasin D (10(-4) M) stimulated CD18 expression even though it inhibited shape changes. The surface distribution of CD18 determined by light microscopy was uniform in unstimulated cells or in various forms of stimulation except for cells treated with 10(-5) M cytochalasin D. Cytochalasin D (10(-5) M) produced CD18 accumulation at the pole opposite the F-actin cap. Experiments with colchicine, nocodazole, 2H2O and cytochalasin D suggest that microtubules as well as microfilaments modulate surface expression of CD18. The results suggest that protein kinase C and phosphatases play a role in regulating surface expression of CD18 in neutrophils.(ABSTRACT TRUNCATED AT 250 WORDS)
Amino Acid Sequence↗
Regional mapping of the gene for autosomal dominant spinocerebellar ataxia (SCA1) by localizing the closely linked D6S89 locus to 6p24.2----p23.05.
The locus for one subtype of autosomal dominant spinocerebellar ataxias (SCA1) is closely linked (within 1-2 cM) to D6S89, which contains a highly polymorphic dinucleotide repeat sequence. D6S89 has been mapped previously to 6p24----p21.3, between the HLA and F13A1 loci. Mutant cell lines were used to correlate the absence or presence of D6S89 with cytogenetically detectable interstitial 6p deletions. The results allowed us to map D6S89 to the 6p24.2----p23.05 region. The close linkage of SCA1 to D6S89 indicates that this locus is most likely located in the 6p24----p23 segment.
Cell Line, Transformed↗
Longevity of adult ventricular rat heart muscle cells in serum-free primary culture.
The study had two aims: first, to improve the longevity of isolated adult cardiomyocytes in serum-free culture, and, second, to investigate whether catecholamines which promote hypertrophy in vivo can prolong survival of isolated adult rat cardiomyocytes in serum-free culture. The basic cell culture medium consists of serum-free medium 199 with 10(-7) M insulin. In this medium 50% of the initially plated cardiomyocytes survive in elongated form for 2 days. Omission of glutamine and supplementation of the basic medium with 5 mM creatine, 2 mM carnitine and 5 mM taurine extends survival of elongated cells to 14 days. In supplemented medium, normal cell ATP content is maintained (27 nmol/mg protein after 15 days), but cells gradually atrophy and reduce their protein mass. The trophic effects of catecholamines (epinephrine, norepinephrine, phenylephrine; 10 microM, added on day 3 of culture) were investigated. After addition of catecholamines the cells spread. Spreading can be prevented by prazosin (10 microM) and phentolamine (10 microM) but not by propranolol (10 microM), indicating that spreading is stimulated via the alpha 1-adrenoreceptor. Cells also spread in the presence of the phorbol ester phorbol myristate acetate (10 microM). Catecholamines reduce the progressive cell atrophy and protein loss. With 10 microM phenylephrine, cellular ATP content remained constant at 27 nmol/mg protein until day 15. The results indicate that agents which stimulate protein kinase C (alpha 1-agonists, phorbol esters) stimulate cell spreading, protein synthesis and long-term survival of cardiomyocytes in vitro.
Animals↗
Possibilities and limitations of carrier diagnosis in families with Duchenne muscular dystrophy caused by deletions in the major hot spot region using pulsed-field gel electrophoresis.
The cDNA probes cf56a, b identify deletions in 45% of the investigated patients with Duchenne and Becker muscular dystrophy (DMD/BMD). But carrier detection by junction fragments using normal gel electrophoresis conditions separating fragments up to a size of about 25 kilobases is possible only in selected cases. We, therefore, applied separation of Sfi I-digested DNA by rotating-field gel electrophoresis (RFE) in combination with Southern blot transfer and hybridization using cf56a for this purpose. In this study we compared hybridizing fragments of DNA from three DMD families with different deletion patterns: distal to the Sfi I-site F located between exon 48/49 (family A), proximal to the Sfi I-site F including the P20 intron (family B), and bridging the Sfi I-site F (family C). Junction fragments in the DNA of 2 affected boys and their mothers were detected in families B and C. Carrier determination on this basis was performed for family C. Given these three families are representative for other families with similar deletions, it will be possible to offer carrier diagnosis using RFE in 38% of the studied families with DMD/BMD caused by deletions in the major hot spot region.
Adult↗
Mitochondrial DNA evolution in the obscura species subgroup of Drosophila.
Mitochondrial DNA (mtDNA) restriction site maps for nine species of the Drosophila obscura subgroup and for Drosophila melanogaster were established. Taking into account all restriction enzymes (12) and strains (45) analyzed, a total of 105 different sites were detected, which corresponds to a sample of 3.49% of the mtDNA genome. Based on nucleotide divergences, two phylogenetic trees were constructed assuming either constant or variable rates of evolution. Both methods led to the same relationships. Five differentiated clusters were found for the obscura subgroup species, one Nearctic, represented by Drosophila pseudoobscura, and four Palearctic, two grouping the related triads of species Drosophila subobscura, Drosophila madeirensis, Drosophila obscura, Drosophila subsilvestris, and two more represented by one species each, Drosophila bifasciata, and Drosophila tristis. The different Palearctic clusters are as distant between themselves as with the Nearctic one. For the related species D. subobscura, D. madeirensis, and D. guanche, the pair D. subobscura-D. madeirensis is the closest one. The relationships found by nucleotide divergence were confirmed by differences in mitochondrial genome size, with related species sharing similar genome lengths and differing from the distant ones. The total mtDNA size range for the obscura subgroup species was from 15.5 kb for D. pseudoobscura to 17.1 for D. tristis.
Animals↗
Mitochondrial DNA variation and genetic structure in Old-World populations of Drosophila subobscura.
To discover the relation between mitochondrial DNA (mtDNA) polymorphism and the geographic population structure of Drosophila subobscura previously established for other genetic traits, a wide Paleartic survey was carried out. A total of 24 nucleomorphs was observed among 261 isofemale lines assayed by 11 restriction endonucleases with 38 different sites in the mtDNA cleavage map. The differentiation of the Canary Islands populations (delta = 0.0119) compared with the mean among all the other continental and insular populations (delta = 0.0002) is striking. Both the great divergence among Canary Islands nucleomorphs (delta = 0.021) compared with the maximum nucleomorph distance in all other populations (delta = 0.017) and the abundance of endemic nucleomorphs (11) on the Canary Islands (50% of the total number of different nucleomorphs found in the entire distribution area) suggest that this molecular differentiation most probably results from the very old age of the Canary Islands populations rather than from drift and founder effects.
Animals↗
A 6p22 reference map of leukocyte DNA: exclusion of rearrangement in four cases of atypical haemochromatosis.
We describe a 4 Mb reference map of the haemochromatosis gene region in leukocyte DNA from seven controls and four atypical haemochromatosis patients. Three patients had normal coding sequence for HFE, the candidate gene for genetic haemochromatosis (GH). The fourth patient had classical GH but was heterozygous for Cys282Tyr with otherwise normal coding sequence. The genomic DNA was mapped by pulsed-field gel electrophoresis (PFGE) using five rare-cutting enzymes. Seventeen probes including HFE were positioned on the map. Despite proximity to the highly polymorphic major histocompatibility complex (MHC), no polymorphism was observed in the control group with these telomeric probes. Furthermore, major rearrangement of the HFE region was excluded as a mutation contributing to iron overload in these atypical patients. Maps of cloned DNA are linked through genes and other probes to this reference map of the HFE region in uncloned genomic DNA.
Chromosomes, Human, Pair 6↗
[Churg-Strauss syndrome: personnel case report and literature review].
A 58-year-old male presented with a three years history of atopic asthma, fluctuating eosinophilia and, at the moment of diagnosis, systemic vasculitis of brutal onset affecting skin and peripheral nerves. Demonstration of eosinophilic infiltrates and granulomata in involved tissues confirmed the clinical diagnosis of Churg-Strauss syndrome. Therapy with high-dose methylprednisolone and cyclophosphamide was followed by normalization of blood cell count and partial recovery of clinical manifestations, with persisting damage to the peripheral nerves.
Churg-Strauss Syndrome↗