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Results for “Polymorphism, Restriction Fragment Length”

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At least 685 records · Page 38Linked to original sources
PubMed1991

Identification of restriction fragment length polymorphism and random amplified polymorphic DNA markers linked to downy mildew resistance genes in lettuce, using near-isogenic lines.

Near-isogenic lines were used to identify restriction fragment length polymorphism (RFLP) and random amplified polymorphic DNA (RAPD) markers linked to genes for resistance to downy mildew (Dm) in lettuce. Two pairs of near-isogenic lines that differed for Dm1 plus Dm3 and one pair of near-isogenic lines that differed for Dm11 were used as sources of DNA. Over 500 cDNAs and 212 arbitrary 10-mer oligonucleotide primers were screened for their ability to detect polymorphism between the near-isogenic lines. Four RFLP markers and four RAPD markers were identified as linked to the Dm1 and Dm3 region. Dm1 and Dm3 are members of a cluster of seven Dm genes. Marker CL922 was absolutely linked to Dm15 and Dm16, which are part of this cluster. Six RAPD markers were identified as linked to the Dm11 region. The use of RAPD markers allowed us to increase the density of markers in the two Dm regions in a short time. These regions were previously only sparsely populated with RFLP markers. The rapid screening and identification of tightly linked markers to the target genes demonstrated the potential of RAPD markers for saturating genetic maps.

Base Sequence↗
PubMed1995

HLA class II genotyping by polymerase chain reaction-restriction fragment length polymorphism method (PCR-RFLP) in systemic lupus erythematosus patients.

Recently, genotyping of HLA class II alleles by digestion of polymerase chain reaction (PCR) amplified polymorphic DNA region with restriction endonucleases (PCR-RFLP) has been reported and claimed to be a simple and reliable technique. We tested the use of PCR-RFLP for genotyping of DQA 1, DQB 1, DPB 1 and DRB 1 alleles of 40 normal individuals and 19 patients with systemic lupus erythematosus (SLE). In agreement with previous reports, we observed an association of SLE with the DRB 1*1501-DQA 1*0102-DQB 1*0602 haplotype and noted an unreported association with DPB 1*0501. Although these observations must be confirmed with larger sample sizes, we believe that the PCR-RFLP is simpler and more practical than the sequence-specific oligonucleotides (PCR-SSO) for genotyping and can be invaluable to the more widespread molecular determination of HLA-class II specificities, including in non-specialized laboratories.

Genotype↗
PubMed2000

Molecular characterization of environmental mycobacterium strains by PCR-restriction fragment length polymorphism of hsp65 and by sequencing of hsp65, and of 16S and ITS1 rDNA.

Fifteen mycobacterial strains from the environment, not clearly identifiable by biochemical properties, were analyzed with molecular markers: PCR-restriction enzyme analysis of hsp65 and sequencing of hsp65, and of the internal transcribed spacer 1 (ITS1) and 16S rDNA. The 16S rDNA sequencing closely related the strains to a slow-growing mycobacterial group including Mycobacterium simiae, Mycobacterium lentiflavum, Mycobacterium genavense, Mycobacterium triplex and Mycobacterium heidelbergense. A stretch of T bases at the level of 16S rDNA enabled the separation of M. simiae and M. lentifiavum from M. genavense, M. triplex and M. heidelbergense; hence the attribution of some environmental strains to the first or second group. But the distances between the two clades were very short and the relative positions of environmental strains and of reference strains were not resolved in terms of node robustness (low bootstrap values) in the distance tree. However, the hsp65 restriction profiles suggested assigning six strains to the M. lentiflavum species, although these strains had been found closely related to M. genavense and M. triplex from 16S rDNA nucleotide signatures. The clustering of environmental strains into the same three clusters was deduced from analysis of three sequence data (hsp65, and ITS1 and 16S rDNA), but the taxonomic affiliation of environmental strains to reference strains remained tentative. Among environmental strains and reference strains, the distances found from hsp65 sequences had the same amplitude as those found between different strains of Mycobacterium gordonae. From ITS1 rDNA sequences, the distances found between the strains of the Mycobacterium avium complex also had the same amplitude as those found between environmental strains and reference strains. From our results, it appears that the environmental strains and the reference strains could constitute a complex of subspecies or closely related species. Their taxonomic status must be confirmed by DNA/DNA hybridization experiments.

Bacterial Proteins↗
PubMed1993

Restriction fragment length polymorphisms distinguish Leptospira borgpetersenii serovar hardjo type hardjo-bovis isolates from different geographical locations.

Genetic variability among Leptospira borgpetersenii serovar hardjo type hardjo-bovis isolates representing several geographical regions was determined by restriction endonuclease analysis. Five previously unidentified EcoRI digestion patterns and one previously unidentified HhaI digestion pattern were seen with the various isolates. The copy number and genomic distribution of an L. borgpetersenii insertion sequence (IS1533) was determined. Hardjo-bovis isolate 033 (the type strain for hardjo-bovis) contained 40 well dispersed copies of IS1533. IS1533 probes were used to compare hardjo-bovis isolates by DNA blot hybridization analysis. Use of these probes showed the presence of additional genetic heterogeneity among hardjo-bovis isolates, which restriction endonuclease analysis did not show. Pulsed-field gel electrophoretic analysis of DNAs from several isolates suggested that some polymorphisms arose by genomic rearrangements. All hardjo-bovis isolates were categorized into 14 distinct groups on the basis of common hybridization and endonuclease digestion patterns. Most of these groups were isolated from distinct geographical regions, suggesting that several different clonal populations of hardjo-bovis exist.

Americas↗
PubMed1989

Restriction fragment length polymorphisms in the apo B gene in relation to coronary artery disease.

We have determined the frequencies of the alleles at the EcoRI (E), XbaI (X) and PvuII (P) polymorphic restriction sites in the apo B gene in 124 white men with coronary artery disease (CAD) and in 146 white men free from CAD. The frequencies of the E- (restriction site absent) and X- alleles were both significantly higher in normocholesterolaemic men with CAD than in those without CAD, but the frequency of the P+ allele (restriction site present) was similar in the 2 groups. The frequency of the E- allele was significantly higher in CAD men with hypertriglyceridaemia than in normal men without hypertriglyceridaemia. In the normocholesterolaemic men without CAD, the mean serum cholesterol concentration was higher in those with genotype X++ than in those with genotype X--. Mean serum LDL-apo B and LDL-cholesterol concentrations did not differ significantly between men with different XbaI or EcoRI genotypes. Serum apo A-I levels differed significantly between normal men with different XbaI genotypes. Serum HDL-cholesterol levels differed significantly between CAD men with different XbaI genotypes. These results suggest that in white men the E- and X- alleles are in linkage disequilibrium with a nearby allele that is causally related to CAD. It is also possible that the amino acid substitution at position 4154 in apo B, brought about by the nucleotide change responsible for the EcoRI polymorphism, has a direct effect on the atherogenicity of LDL.

Adult↗