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Ray C. Anderson 《American journal of human genetics》1954,6(3):359-360
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《American journal of human genetics》1980,32(6):96A-162A
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《American journal of human genetics》1982,34(6):79A-116A
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Genetics and pharmacology can elicit surprisingly different phenotypes despite targeting the same protein. This Essay explores these unexpected differences and their implications for biology and medicine. 相似文献
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Myoclonic epilepsy with ragged red fibers (MERRF) is a mitochondrial disease that is characterized by myoclonic epilepsy with ragged red fibers (RRF) in muscle biopsies. The aim of this study was to analyze Brazilian patients with MERRF. Six patients with MERRF were studied and correlations between clinical findings, laboratory data, electrophysiology, histology and molecular features were examined. We found that blood lactate was increased in four patients. Electroencephalogram studies revealed generalized epileptiform discharges in five patients and generalized photoparoxysmal responses during intermittent photic stimulation in two patients. Muscle biopsies showed RRF in all patients using modified Gomori-trichrome and succinate dehydrogenase stains. Cytochrome c oxidase (COX) stain analysis indicated deficient activity in five patients and subsarcolemmal accumulation in one patient. Molecular analysis of the tRNA(Lys) gene with PCR/RFLP and direct sequencing showed the A8344G mutation of mtDNA in five patients. The presence of RRFs and COX deficiencies in muscle biopsies often confirmed the MERRF diagnosis. We conclude that molecular analysis of the tRNA(Lys) gene is an important criterion to help confirm the MERRF diagnosis. Furthermore, based on the findings of this study, we suggest a revision of the main characteristics of this disease. 相似文献
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B. Dujon M. Bolotin-Fukuhara D. Coen J. Deutsch P. Netter P. P. Slonimski L. Weill 《Molecular & general genetics : MGG》1976,143(2):131-165
| 1. | A series of CS revertants has been selected from various strains (both + and –) carrying a CR mitochondrial mutation at the RIB1 locus. The properties of mitochondrial recombination exhibited by these CS revertants in various crosses, have been examined systematically. The allele of the CS revertants has been defined in crosses with + and – tester strains using two criteria: the polarity of recombination and a new criterium called relative output coefficient. We found that mutations of appear frequently associated with the mutations at the RIB1 locus selected from – strains but not with those selected from + strains. A new allelic form of (n) which had not been found amongst wild type yeast strains is characterised. Similarly n mutation was found frequently associated with CR mutants at the RIB1 locus selected from – CS strains but not with those selected from + CS strains. The n mutants, and the + and – strains, explain the groups of polarity previously observed by Coen et al. (1970). |
| 2. | Main features of mitochondrial crosses with n strains (+×n, –×n and n×n) are analysed. Recombination is possible between the different mitochondrial genetic markers. No high polarity of recombination is observed and the frequency of recombinants are similar to those found in homosexual crosses (+×+ and –×–). A striking property, observed for the first time, exists in crosses between + +×n CS strains and some – CREO mutants: the – CREO are unable to integrate by recombination their CR allele into the + mit-DNA of – CS strains while being capable of integrating it into + CS or – CS genomes. |
| 3. | It is proposed that the locus is the site of initiation of non reciprocal recombination events, the +/– pairing specifically initiates the non-reciprocal act while +/n or –/n pairings do not. |
| 4. | The molecular nature of the n mutation and its bearing on the structure of the locus are discussed. It is suggested that n mutations correspond to macrolesions (probably deletions) of a segment of the mit-DNA covering the and RIB1 loci. If n is a partial deletion of the – sequence the + could be an additionnal deletion of the n sequence. |
| 5. | The occurrence of spontaneous CR and ER mitochondrial mutations has been analysed by the Luria and Delbrück fluctuation test in – and n isonuclear strains. Results of these tests indicate that an intracellular selection of resistant copies preexisting the action of the antibiotic occurs. |
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