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Biomedical subjects

A Gal

Publications and source records attributed to A Gal.

At least 181 records · Page 10Linked to original sources
PubMed1991

No evidence of linkage between the locus for autosomal dominant retinitis pigmentosa and D3S47 (C17) in three Australian families.

A linkage analysis has been performed on three Australian families segregating for autosomal dominant retinitis pigmentosa (ADRP). No evidence of linkage has been found in any of the pedigrees studied between the locus D3S47 and the gene for ADRP. The D3S47 locus was found to show very close linkage with the ADRP gene in a large Irish pedigree. Our study together with a similar report on a British family indicates that there is genetic heterogeneity in this disease.

Adolescent↗
PubMed1991

Multipoint linkage analysis in X-linked ocular albinism of the Nettleship-Falls type.

An extensive linkage analysis was performed by studying ten Xp22 loci in ten families segregating for X-linked ocular albinism of the Nettleship-Falls type (XOA). Linkage was confirmed between the XOA locus (OA1) and both DXS16 (theta max = 0.10, zeta max = 4.09) and DXS237 (theta max = 0.12, zeta max = 2.53). Linkage was found between OA1 and the loci DXS85 (theta max = 0.00, zeta max = zeta max = 4.37), DXS143 (theta max = 0.04, zeta max = 3.74), STS (theta max = 0.05, zeta max = 2.48), DXF30S1 (DXS278) (theta max = 0.07, zeta max = 8.79) and DXF30S2/3 (DXS278) (theta max = 0.00, zeta max = 14.93). An indication for linkage was found between OA1 and the loci DXS43 (theta max = 0.10, zeta max = 1.58) and DXS31 (theta max = 0.12, zeta max = 1.55). The analysis of multiple informative meioses suggests the order Xpter-(DXS31, DXS89)-(DXF30S1, DXS237)-(DXF30S2/3, OA1)-DXS143-(DXS16, DXS43)-Xcen. Various multipoint linkage analyses using the DNA loci order DXF30S1-STS-DXS237-DXS143-DXS16 significantly favour the position of OA1 between DXS237 and DXS143. These results further determine the genetic map around the XOA locus on the distal Xp and may be useful for DNA diagnosis in families with XOA.

Albinism, Ocular↗
PubMed1991

Pro-347-Arg mutation of the rhodopsin gene in autosomal dominant retinitis pigmentosa.

It has been shown recently that autosomal dominant retinitis pigmentosa may be caused by point mutations of the rhodopsin gene in a portion of families. In this communication, a large six-generation family with autosomal dominant RP is described. Molecular analysis by PCR amplification followed by restriction digestion or heteroduplex analysis suggested a point mutation in codon 347, in which two different mutations (Pro-347-Ser and Pro-347-Leu) have already been reported. Direct sequencing of the patients' DNA revealed a previously undescribed CCG----CGG transversion in codon 347 predicting a Pro----Arg substitution. Ophthalmological data of the patients are summarized and compared to those of patients with other mutations in the rhodopsin gene.

Base Sequence↗
PubMed1991

Ring Y chromosome: molecular characterization by DNA probes.

A young male with a karyotype of 46,X,+ mar is described. Physical mapping of the marker chromosome by using Y-specific single-copy or moderately repeated DNA sequences as molecular probes showed that, in addition to the heterochromatic part of the Yq, a considerable portion of the euchromatin in both Yp and Yq had been lost. These findings suggest that the marker chromosome is a ring Y, for the generally accepted model of ring formation implies breakages in both chromosome arms. The clinical features of the patient correlated well with the phenotypic changes expected from the loss of genetic material from the Y.

Adolescent↗
PubMed1991

X-linked megalocornea. Ocular findings and linkage analysis.

A family with X-linked megalocornea (XMC) is presented. The most typical ocular features of the disease (cornea globosa, arcus lipoides, mosaic dystrophy of the cornea, pigment dispersion, and cataract) are described and their diagnostic value is discussed by reviewing the literature. Linkage data suggest that the XMC locus maps in the region Xq13-q25, most probably in Xq21-q22.

Adult↗
PubMed1991

[Autosomal dominant hereditary retinopathia pigmentosa with genetic heterogeneity].

There is considerable clinical variability in autosomal dominant retinitis pigmentosa (ADRP). The underlying biochemical defect had remained unknown until recently, so that it was not possible to determine the primary cause(s) of this phenotypic diversity. Recently, different point mutations and base pair deletions have been identified in the rhodopsin gene in a proportion of patients with ADRP, providing convincing evidence for allelic genetic heterogeneity in this disease. We screened a total of 65 patients with ADRP in Germany, Austria, and Switzerland for the presence of the point mutations described recently at codons 58 and 347 in patients in the USA. Our results show that the frequency of point mutations at codon 347 in the patients studied here is about 3%, a figure similar to that found in the USA. The frequency of the mutation at codon 58 seems to be generally low. The identification of patients with point mutations in the rhodopsin gene offers the possibility, for the first time, of studying the correlation between genotype and disease phenotype.

Chromosome Aberrations↗
PubMed1990

Interaction between light harvesting chlorophyll-a/b protein (LHCII) kinase and cytochrome b6/f complex. In vitro control of kinase activity.

We have previously reported that the cytochrome b6/f complex may be involved in the redox activation of light harvesting chlorophyll-a/b protein complex of photosystem II (LHCII) kinase in higher plants (Gal, A., Shahak, Y., Schuster, G., and Ohad, I. (1987) FEBS Lett. 221, 205-210). The aim of this work was to establish whether a relation between the cytochrome b6/f and LHCII kinase activation can be demonstrated in vitro. Preparations enriched in cytochrome b6/f obtained from spinach thylakoids by detergent extraction and precipitation with ammonium sulfate followed by different procedures of purification, contained various amounts of LHCII kinase activity. Analysis of the cytochrome b6/f content and kinase activity of fractions obtained by histone-Sepharose and immunoaffinity columns, immunoprecipitation and sucrose density centrifugation, indicate functional association of kinase and cytochrome b6/f. Phosphorylation of LHCII by fractions containing both cytochrome b6/f and kinase was enhanced by addition of plastoquinol-1. LHCII phosphorylation and kinase activation could be obtained in fractions prepared by use of beta-D-octyl glucoside but not when 3-[(cholamidopropyl)dimethyl-ammonio]-1-propanesulfonate was used as the solubilizing detergent. Kinase activity could be inhibited by halogenated quinone analogues (2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone and 2,3-diiodo-5-t-butyl-p-benzoquinone) known to inhibit cytochrome b6/f activity. However, kinase activity was inhibited by these analogues in all preparations including those which could not phosphorylate LHCII. We thus propose that the redox activation of LHCII phosphorylation is mediated by kinase interaction with cytochrome b6/f while the deactivation may be related to a distinct quinone binding site of the enzyme molecule.

Ammonium Sulfate↗
PubMed1990

Gene of type II autosomal dominant retinitis pigmentosa maps on the long arm of chromosome 3.

Linkage analysis has been performed on a large Australian family segregating for the autosomal dominant form of retinitis pigmentosa (ADRP). The majority of patients had no subjective symptoms of night blindness until their second decade and good visual acuity until late in life. The disease in this family has been classified as Type II ADRP according to the subdivisions provided by both Massof and Finkelstein and Fishman and colleagues. Linkage (Omax:0.08 at Zmax:4.78) is here demonstrated between the disease locus and D3S47 (a marker locus on the long arm of chromosome 3), which showed in an earlier study very close linkage without recombination to the disease locus in an Irish pedigree with a clinically more severe and early onset (Type I) ADRP.

Chromosome Aberrations↗
PubMed1990

[X-chromosomal hereditary night blindness: detection of carriers by segregation analysis with linked DNA markers].

Congenital stationary night blindness is a rare disease with autosomal dominant, autosomal recessive, or X-linked recessive inheritance. The X-chromosomal form is frequently associated with myopia. Female carriers have no symptoms of visual impairment and therefore cannot be identified clinically. The close link recently described between the disease locus and the DXS7 locus, mapped in Xp11.3, as well as other marker loci from this chromosomal region, permits indirect genotype analysis and thus identification of the carriers; with the information thus obtained, improved genetic counseling is possible. The authors studied a large Swiss family with the X-linked trait. Segregation analysis was performed with DXS7 as well as two flanking markers, DXS255 and OTC. It was thus possible to determine the degree or probability of several female members of the family being carriers.

Chromosome Banding↗
PubMed1990

Localizing multiple X chromosome-linked retinitis pigmentosa loci using multilocus homogeneity tests.

Multilocus linkage analysis of 62 family pedigrees with X chromosome-linked retinitis pigmentosa (XLRP) was undertaken to determine the presence of possible multiple disease loci and to reliably estimate their map location. Multilocus homogeneity tests furnished convincing evidence for the presence of two XLRP loci, the likelihood ratio being 6.4 x 10(9):1 in favor of two versus a single XLRP locus and gave accurate estimates for their map location. In 60-75% of the families, location of an XLRP gene was estimated at 1 centimorgan distal to OTC, and in 25-40% of the families, an XLRP locus was located halfway between DXS14 (p58-1) and DXZ1 (Xcen), with an estimated recombination fraction of 25% between the two XLRP loci. There is also good evidence for a third XLRP locus, midway between DXS28 (C7) and DXS164 (pERT87), supported by a likelihood ratio of 293:1 for three versus two XLRP loci.

Chromosome Mapping↗
PubMed1990

Ratio of fetal to maternal DNA is less than 1 in 5000 at different gestational ages in maternal blood.

Using Southern hybridization with the DNA probe pY3.4, we were not able to detect fetal DNA in blood of 36 pregnant women carrying male fetuses. Gestational ages ranged from 8-40 weeks of pregnancy. Using the same DNA probe, we were able to detect the male-specific signal in experimental dilution series down to 1/5000 on autoradiograms. We conclude that the ratio of fetal DNA in maternal circulation, in contrast to previous estimations, must be lower than 1/5000.

Autoradiography↗
PubMed1990

Photoinactivation of photosystem II and degradation of the D 1 protein are reduced in a cytochrome b6/f-less mutant of Chlamydomonas reinhardtii.

The effect of unoccupancy of the QB site by plastoquinone on the photoinactivation of reaction center II in a Cyt b6/f-less mutant of Chlamydomonas reinhardtii, B6, was investigated. In these cells the oxidation of plastoquinol generated by electron flow via RC II to plastoquinone and thus the turnover of PQH2/PQ via the QB site are drastically reduced. Reaction center II of the mutant cells was resistant to photoinactivation relative to the control cells as demonstrated by measurements of light-induced destabilization of S2-QB- charge recombination, rise in intrinsic fluorescence and loss of variable fluorescence. These parameters relate to functions involving the reaction center II D 1 protein. The light-induced degradation of D 1 in the mutant cells was also considerably reduced, with a t1/2 value of 7 h as compared, under similar conditions, to about 1.5 h for the control cells. These results indicate that the photoinactivation of RC II and turnover of the D 1 protein are related and require occupancy of the QB site by PQ and its light-driven reduction.

Chlamydomonas↗
PubMed1990

Posthumous diagnosis of X-linked retinoschisis using DNA analysis.

X-linked juvenile retinoschisis usually results in a rather serious visual handicap in affected males. However, occasionally patients can present with very subtle clinical signs without subjective complaints. For this reason, the family history can be misleading and caution is necessary when analysing the pedigree and giving genetic advice. In this report a family with X-linked retinoschisis is described in which segregation analysis with DNA probes strongly suggests that the deceased grandfather, who was said to have had good vision, had been affected by juvenile retinoschisis.

DNA↗