Physical fine-mapping of a deletion spanning the Norrie gene

Summary Norrie disease (ND), atrophia bulborum hereditaria, is caused by a gene defect on the proximal short arm of the X-chromosome. As shown by us and others, microdeletions spanning the DXS7 locus are not uncommon in this disorder, and there is recent evidence that, at least in some of the Norrie deletion patients, the monoamine oxidase (MAO) A and B genes are deleted as well. Molecular hybridization experiments with 19 cloned DNA fragments have enabled us to construct a preliminary long-range restriction map around DXS77, DXS7, MAO-A and MAO-B, and to localize the distal end point of an ND deletion between DXS77 and DXS7.     

Submicroscopic interstitial deletion of the X chromosome explains a complex genetic syndrome dominated by Norrie disease

Norrie disease (ND), an X-linked recessive disorder, is characterized by congenital blindness followed by bulbar atrophy. We have examined a three-generation family in which ND is part of a complex X-linked syndrome with severe mental retardation, hypogonadism, growth disturbances, and increased susceptibility to infections as additional features. This syndrome is apparently due to an interstitial deletion, as evidenced by the failure of the L1.28 DNA probe (DXS7 locus, Xp11.3) to detect complementary DNA sequences on the defective X chromosome of an affected male and of several obligatory heterozygotes. Attempts to further define this deletion with other DNA probes from the proximal short arm of the X chromosome or by prometaphase chromosome analysis were unsuccessful.     

Solid media with elemental sulphur for detection of sulphuroxidizing microbes

Two solid media containing finely dispersed elemental sulphur and permitting autotrophic growth of sulphur-oxidizing organisms are described. On these media, colonies of sulphur-oxidizing cells are surrounded by a clear zone. A facultative S-oxidizingStreptomyces was isolated with the new technique.     

Detection and characterization of point mutations in the choroideremia candidate gene by PCR-SSCP analysis and direct DNA sequencing

By making use of positional cloning strategies we recently isolated a candidate gene for choroideremia (CHM), which is transcribed in retina, choroid, and/or retinal pigment epithelium. The gene contains an open reading frame that is structurally altered in 10 CHM patients with sizable deletions and in a female patient with a balanced translocation involving the Xq21 band. Employing PCR-SSCP analysis and direct DNA sequencing we have now detected and characterized different point mutations in five patients with CHM. Each of these mutations introduces a termination codon into the open reading frame of the CHM candidate gene, thereby predicting a distinct truncated protein product. Together these findings provide convincing evidence for the candidate gene being identical with the choroideremia gene.     

Physical and genetic mapping of a novel chromosome 19 ERCC1 marker showing close linkage with myotonic dystrophy.

Recent genetic linkage analyses have mapped the myotonic dystrophy locus to the region of 19q13.2-13.3 lying distal to the gene for creatine kinase subunit M (CKM). The human excision repair gene ERCC1 has also been mapped to this region of chromosome 19. A novel polymorphic DNA marker, pEO.8, has been isolated from a chromosome 19 ERCC1-containing cosmid that maps to a 300-kb NotI fragment encompassing both CKM and ERCC1. Genetic linkage analysis reveals close linkage between pEO.8 and myotonic dystrophy (DM) (zmax = 19.3, theta max = 0.01). Analysis of two key recombinant events suggests a mapping of DM distal to pEO.8 and CKM.     

The gene for X-linked progressive mixed deafness with perilymphatic gusher during stapes surgery (DFN3) is linked to PGK

Summary A linkage analysis has been performed in a large Dutch kindred with progressive mixed deafness with perilymphatic gusher during stapes surgery (DFN3) using a panel of X-chromosomal RFLPs. Tight linkage (z_max=3.07 at =0.00) was demonstrated with the locus for phosphoglycerate kinase (PGK), which is located at Xq13. Tight linkage was excluded for DXS9 (probe RC8) and DXS41 (probe 99.6) on Xp and for blood clotting factor 9 (FIX) on distal Xq. Deafness is one of the predominant clinical features in males with deletions of the Xq21 band. Our results suggest that this association may be due to involvement of the DFN3 gene.     

Stimulatory and inhibitory effects of adrenaline and 8-bromo-cAMP on insulin-sensitive 2-deoxyglucose transport in rat adipocytes

The effects of adrenaline and 8-bromo-cAMP on 2-deoxyglucose uptake in isolated rat adipocytes were investigated under conditions of unidirectional flux, in which the transport process is rate limiting. Adrenaline showed a dualistic effect in the absence of insulin. At concentrations below 1 microM adrenaline stimulated 2-deoxyglucose uptake; at higher concentrations adrenaline inhibited the uptake. In the presence of insulin at the maximum effective concentration, addition of adrenaline further increased the 2-deoxyglucose uptake by about 50%. In the presence of insulin 8-bromo-cAMP had the same effect as adrenaline. In the absence of insulin, 8-bromo-cAMP only inhibited 2-deoxyglucose uptake.     

Creatine Kinase–Mediated ATP Supply Fuels Actin-Based Events in Phagocytosis

Phagocytosis requires locally coordinated cytoskeletal rearrangements driven by actin polymerization and myosin motor activity. How this actomyosin dynamics is dependent upon systems that provide access to ATP at phagosome microdomains has not been determined. We analyzed the role of brain-type creatine kinase (CK-B), an enzyme involved in high-energy phosphoryl transfer. We demonstrate that endogenous CK-B in macrophages is mobilized from the cytosolic pool and coaccumulates with F-actin at nascent phagosomes. Live cell imaging with XFP-tagged CK-B and β-actin revealed the transient and specific nature of this partitioning process. Overexpression of a catalytic dead CK-B or CK-specific cyclocreatine inhibition caused a significant reduction of actin accumulation in the phagocytic cup area, and reduced complement receptor–mediated, but not Fc-γR–mediated, ingestion capacity of macrophages. Finally, we found that inhibition of CK-B affected phagocytosis already at the stage of particle adhesion, most likely via effects on actin polymerization behavior. We propose that CK-B activity in macrophages contributes to complement-induced F-actin assembly events in early phagocytosis by providing local ATP supply.     

Cloning of the breakpoints of a deletion associated with choroideremia

Summary In order to characterize a previously described submicroscopic deletion encompassing (part of) the choroideremia (tapetochoroidal dystrophy: TCD) gene, we have cloned a 10.5-kb EcoRI fragment from the patient's DNA: this fragment carries the junction between both deletion endpoints (junction fragment). The distal portion of this fragment defines a new marker within, or just distal to the TCD gene. This marker has been employed to confirm the diagnosis in several affected family members, and to rule out carriership in a female at risk with conspicuous clinical signs.This work was presented in part at the 5th International Retinitis Pigmentosa Congress, Melbourne 1988