A highly informative CACA repeat polymorphism upstream of the human dystrophin gene (DMD).
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Base Sequence↗
Biomedical subjects
A Tolun
Publications and source records attributed to A Tolun.
Localization of an ataxia-telangiectasia locus to a 3-cM interval on chromosome 11q23: linkage analysis of 111 families by an international consortium.
Linkage of at least two complementation groups of ataxia-telangiectasia (AT) to the chromosomal region 11q23 is now well established. We provide here an 18-point map of the surrounding genomic region, derived from linkage analysis of 40 CEPH families. On the basis of this map, 111 AT families from Turkey, Israel, England, Italy, and the United States were analyzed, localizing the AT gene(s) to an 8-cM sex-averaged interval between the markers STMY and D11S132/NCAM. A new Monte Carlo method for computing approximate location scores estimates this location as being at least 10(8) times more likely than the next most likely interval, with a support interval midway between STMY and D11S132 that is either 5.2 cM (sex-averaged and conservatively based on 3 lod scores from the maximum-location score) or 2.8 cM (male specific, based on a 2.72:1 interval-specific female-to-male distance ratio.
Ataxia Telangiectasia↗
Analysis of fragile X-mental retardation families using flanking polymorphic DNA probes.
Fragile-X mental retardation (FRAX-MR) is one of the more common X-linked disorders affecting 1 in 1,500 newborn males. This disease is characterized by the expression of fragile site in the region q27.3 of the X-chromosome of affected boys when their lymphocytes are cultured in folate deficient medium. In most patients there is macroorchidism postpubertally. The clinical diagnosis of carrier females based on the expression of fragile site in Xq27.3 is usually difficult and sometimes impossible. About half of the carrier females escape diagnosis by this method. Furthermore, prenatal diagnosis is not always feasible. Using Restriction Fragment Length Polymorphism (RFLP) and cloned DNA segments from the region Xq27-Xqter as probes, we have investigated Swedish families with FRAX-MR in three generations. Interesting observations, previously unreported to our knowledge, have been made in some patients and carrier mothers, using one of the probes which is localized to the distal end of Xq. The significance of these findings and the linkage of the disease locus to the different probes used in this study is presented.
DNA↗
Separation of the minimal replication region of the F plasmid into a replication origin segment and a trans-acting segment.
An analysis was carried out on the replication functions within a 2.3 kilobase (kb) segment of the F plasmid which contains an origin (ori s) of replication and is capable of autonomous replication in Escherichia coli. Two separable regions were delineated for this segment: an origin region of approximately 1,140 bp in length and a segment of approximately 1,140 bp that functions in trans to support replication of the origin region. The trans-acting segment is functional as part of an F replicon or when inserted into the E. coli chromosome. A prominent feature of the trans-acting segment is a coding sequence for a 29 K protein (Murotsu et al. 1981).
DNA Replication↗
Direct repeats of the F plasmid incC region express F incompatibility.
The nucleotide sequence of the incompatibility region incC, located at 45.8--46.4 kb on the F plasmid map, was determined. This region consists of 543 bp and contains sufficient information to code for only two small polypeptides of 34 and 30 amino acids each. Deletion of the ATG start codons for these two polypeptides has no effect on expression of incC incompatibility. A prominent feature of this sequence is the presence of five 22 bp direct repeats. A 58 bp segment of the incC region that contains two of these direct repeats was inserted into plasmid pACYC184, which is compatible with the F plasmid. The pACYC184 plasmid containing the direct-repeat sequences now expresses incompatibility with the F'lac plasmid and replication-proficient derivatives of the mini-F plasmid.
Bacterial Proteins↗
Purification of RNA-DNA hybrids by exclusion chromatography.
A simple method for selection of RNA-DNA hybrids has been developed and applied to the purification of adenovirus-specific messenger RNA. Cytoplasmic RNA prepared from adenovirus type 2 (ad2)-infected HeLa cells or from an ad2-transformed rat cell line was hybridized in solution to the complementary strands of ad2 DNA. The hybridization mixture was subsequently fractionated by chromatography on a Sepharose 2B column. The intact probe DNA as well as the RNA-DNA hybrids are excluded from the gel matrix and elute with the void volume. Nonhybridized RNA, in contrast, is included into the gel matrix and elutes as a broad peak well separated from the excluded fractions. Fractions corresponding to the void volume, were collected and the RNA-DNA hybrids were denatured in 90% formamide. The selected RNA was separated from the DNA by affinity chromatography on poly(U)-Sepharose. Restriction endonuclease fragments of DNA with a large enough size to make them excluded from the agarose column were also used for hybridization. In these experiments hybridizations were carried out under conditions which would allow R-loop formation (Thomas, M., White, R.L., and Davis, R.W. (1976) Proc. Natl. Acad. Sci. U.S.A. 73, 2294-2298) and the hybridized RNA was separated from unhybridized RNA by Sepharose chromatography. The validity of the method was demonstrated by programming an in vitro protein-synthesizing system with selected RNA.
Adenoviruses, Human↗
Sequence of inverted terminal repetitions from different adenoviruses: demonstration of conserved sequences and homology between SA7 termini and SV40 DNA.
We have established the nucleotide sequence for the inverted terminal repetition of human adenovirus type 3, a subgroup B adenovirus. The repetition, which is 136 bp long, shows a high degree of homology with the known sequence for the inverted repetition of adenovirus type 5 (Steenbergh et al., 1977) a subgroup C adenovirus. Partial sequence information convering 120 bp of the inverted terminal repetitions of human serotype 12, a subgroup A member, and of simian adenovirus type 7 has also been obtained. A comparison of the established sequences shows that the terminal repetitions, in particular the first 50 bp from the ends, contain sequences that have been well conserved in adenovirus evolution. For instance, only six mismatched base pairs were detected among the first 50 bp in the repetitions of simian adenovirus type 7 and human adenovirus type 5, although the homology between simian adenovirus 7 and human subgroup C adenoviruses was estimated to be only 30%. A 14 bp sequence located 9-22 nucleotides from the ends is present in DNAs from all the human serotypes examined as well as in simian adenovirus 7 DNA. Furthermore, the simian adenovirus 7 repetition contains a 21 bp sequence which is present in SV40 DNA, close to the origin of DNA replication.
Adenoviridae↗
Two complementary strand-specific termination sites for adenovirus DNA replication.
Adenovirus type 2 DNA, specifically labeled at the termini for DNA replication, was prepared by isolation of viral DNA molecules which were completed during short pulses with 3H-thymidine. The distribution of radioactivity in the two complementary strands at the termini for DNA replication was determined by liquid phase hybridization and gelelectrophoresis. At the right-hand terminus, nearly all radioactivity was found in the viral h strand, whereas at the left-hand terminus, most radioactivity was confined to the viral l strand. The results suggest that both molecular ends serve as origins and termini for replication of adenovirus type 2 DNA.
Adenoviridae↗
Nature of the single-stranded DNA in replicating adenovirus type 5 DNA.
Single-stranded regions in replicating adenovirus type 5 DNA were isolated and hybridized in solution to the separated strands of adenovirus 2 or 5 DNA. The results showed that the two strands of adenovirus 5 DNA are exposed to almost the same extent during replication, suggesting that displacement synthesis may start from either end of the viral DNA.
Adenoviruses, Human↗
Termination sites for adenovirus type 2 DNA replication.
Termination sites for replication of adenovirus type 2 DNA have been demonstrated at both ends of the viral chromosome by the procedure of Danna and Nathans (1972). Single-stranded DNA from replicating intermediates was also characterized by hybridization with separated strands of viral DNA. The results indicate that both strands are exposed during replication.
Adenoviridae↗
Repair of radiation-induced strand breaks as related to the inducible inhibitor of postirradiation DNA degradation.
The repair of radiation-produced single-strand breaks observed under alkaline conditions is very apparent in cells which possess an inducible inhibitor of postirradiation DNA degradation. Previous induction of the inhibitor with ultraviolet light increases the amount of repair. In those cells which are genetically not inducible there is no increase following ultraviolet irradiation.
Centrifugation, Density Gradient↗
Carrier detection by DNA analysis in Duchenne muscular dystrophy families.
We applied DNA analysis techniques to Turkish families whose members were afflicted with Duchenne/Becker muscular dystrophy. The aim of this study was to establish a prenatal diagnosis of this anomaly and to determine the carrier state. All of the techniques used in established diagnosis centers are now applied routinely in our laboratory. Both Southern analysis and polymerase chain reaction (PCR) methods were used for deletion detection in patients and restriction enzyme fragment length polymorphism (RFLP) determination for linkage analysis in women at risk. CA repeated sequence length polymorphism, the most recent technique for linkage analysis, was also applied. About 250 individuals from seventy-nine families were investigated and thirty-six entire families were screened. Twenty-five women were found to be carriers while thirty seven were non-carriers. The carrier state could not be determined in three women.
Chromosome Deletion↗