RESUMO
In order to characterize the nature of mutations occurring in non-deleted Duchenne (DMD) and Becker muscular dystrophy (BMD) affected males, a total of 40 unrelated Italian patients was studied for the presence of point mutations within the muscle-specific regulatory region of the dystrophin gene. We decided to investigate the dystrophin promoter sequences because nucleotide variations in these regions could impair the expression of the gene and be the underlying molecular defect in some forms of the disease. In four patients suffering from mental retardation, the brain promoter region was also studied. To screen for point mutations, we applied molecular analysis by parallel denaturing gradient gel electrophoresis (DGGE). No sequence alterations were found in either the muscle or the brain promoters, suggesting that mutations in these regions do not represent a common mechanism of mutation in DMD/BMD.
Assuntos
Análise Mutacional de DNA , Distrofina/genética , Proteínas Musculares/genética , Distrofias Musculares/genética , Proteínas do Tecido Nervoso/genética , Regiões Promotoras Genéticas , Sequência de Bases , Primers do DNA , Eletroforese em Gel de Poliacrilamida , Humanos , Deficiência Intelectual/complicações , Deficiência Intelectual/genética , Itália , Masculino , Dados de Sequência Molecular , Distrofias Musculares/complicações , Desnaturação de Ácido Nucleico , Especificidade de Órgãos , Mutação PuntualRESUMO
Heteroduplex analysis was used to search for small mutations in a sample of 40 Italian DMD/BMB patients in whom large rearrangements were not found. A novel nonsense mutation in exon 17 of the dystrophin gene, consisting of a C to T transition, is described.
Assuntos
Distrofina/genética , Distrofias Musculares/genética , Ácidos Nucleicos Heteroduplexes/análise , Mutação Puntual , Códon sem Sentido/genética , Éxons/genética , Humanos , Itália , Ácidos Nucleicos Heteroduplexes/genética , Fenótipo , Reação em Cadeia da Polimerase , Polimorfismo GenéticoRESUMO
We have studied, by the polymerase chain reaction, the beta-galactosidase cDNA from several Italian patients with infantile GM1-gangliosidosis. One homozygote for a previously undiscovered G > A mutation at position 1479, causing an arginine to histidine change, was detected. The same mutation, in heterozygosis, was identified in 6 unrelated patients, but not in 100 normal chromosomes.
Assuntos
Arginina/genética , Gangliosidose GM1/genética , Histidina/genética , Homozigoto , Mutação Puntual , beta-Galactosidase/genética , Sequência de Bases , Análise Mutacional de DNA , DNA de Cadeia Simples , Humanos , Lactente , Dados de Sequência Molecular , Reação em Cadeia da Polimerase , RNA Mensageiro/genéticaRESUMO
The study of the structural organization of the eukaryotic genome is one of the most important tools for disclosing the evolutionary relationships between species. Artemia (Crustacea, Phyllopoda) offers a very interesting model for speciation studies. The genus, distributed all over the world, comprises both bisexual sibling species and parthenogenetic populations, exhibiting different chromosome numbers (diploidy, polyploidy, and heteroploidy). Digestion of genomic DNA of the parthenogenetic Artemia sp. from Tsing-Tao (China) with the restriction enzymes Eco RI and Alu I reveals that a highly repetitive sequence of 133 bp is present. The Eco RI fragment has been cloned and characterized by genomic organization. The distribution of the Eco RI family of repeats was also studied in several bisexual and parthenogenetic Artemia populations and compared with an Alu I repetitive fragment previously identified in Artemia franciscana.
Assuntos
Artemia/genética , DNA/química , Partenogênese/genética , Sequências Repetitivas de Ácido Nucleico , Animais , Sequência de Bases , Evolução Biológica , Aberrações Cromossômicas , Clonagem Molecular , Frequência do Gene , Dados de Sequência Molecular , Mapeamento por Restrição , Caracteres SexuaisRESUMO
An Alu I family of repeated DNA sequence 113 bp in length was found to be the major component of the heterochromatin in Artemia franciscana. On the basis of the analysis of cloned oligomeric (monomer to examer) heterchromatic fragments we predicted that the sequence could produce a stable curvature in chromosomal DNA. This prediction was confirmed by polyacrylamide gel electrophoresis analysis and by electron microscope observations. The anomalous mobility of these fragments is reversed when the DNA samples are electrophoresed in the presence of distamycin A. Moreover treatment of living Artemia with this drug produces visible decondensation of heterochromatic masses in the interphase nuclei.
