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  • Articles  (22,845)
  • Animals  (21,529)
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  • American Association for the Advancement of Science (AAAS)  (22,835)
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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 34 (1993), S. 53-57 
    ISSN: 1040-452X
    Keywords: Spermatozoa ; Gene expression ; Mutation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Basic chromosomal proteins were extracted from the sperm of fertile and infertile human males. The relative proportions of protamine 1, 2, and 3 were determined by scanning microdensitometry following electrophoresis of total protamine in polyacrilamide gels. The findings were as follows: (1) The proportion of protamine P(2 + 3) in sperm obtained from infertile males was lower than that in fertile males. (2) Protamine P(2 + 3) in infertile human males showed reduced affinity to DNA. The possibility that some cases of human male infertility may be due to mutation within the protamine P2 gene is discussed. © 1993 Wiley-Liss, Inc.
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 32 (1992), S. 331-338 
    ISSN: 1040-452X
    Keywords: Cellularization ; Embryogenesis ; Mutation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: drop out (dop) is a recessive maternal-effect locus identified in a screen for female-sterile mutations in Drosophila polytene region 71C-F. Phenotypic analyses of the dop mutation indicate that the gene is required for proper formation of the cellular blastoderm. In embryos derived from either homozygous or hemizygous dop mothers, cytoplasmic clearing, nuclear migration and division, and pole cell formation appear normal. However, developmental defects are observed prior to and during cellularization of the blastoderm. At the beginning of nuclear cycle 14, the distinct separation of the internal yolk mass and the cortical cytoplasm breaks down. Subsequently, a population of somatic nuclei located at the periphery of the syncytial blastoderm becomes irregularly spaced and nonuniform in their distribution. Despite a somewhat regular formation of the cortical actin network, cellularizaiton in mutant embryos is extremely variable. Such embryos fail to gastrulate normally and produce variable amounts of defective cuticle. Overall, our analyses suggest that the dop gene functions in maintaining the separation of yolk and cortical cytoplasm and in stabilizing the distribution of somatic nuclei in the Drosophila syncytial blastoderm.
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Electrophoresis 18 (1997), S. 675-681 
    ISSN: 0173-0835
    Keywords: Minisatellite ; DNA polymorphism ; Mutation ; DNA-sequencing ; DNA-electrophoresis ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: In a study of DNA sequence and length variation in the repeat array of small D7S22 alleles, 100 alleles typed as the common 14 repeat allele (14R) and 92 rare ones were selected for further characterization. A polymerase chain reaction (PCR) based allele length measurement method revealed a discontinuous distribution of alleles. The 92 rare alleles were grouped by their number of repeats. All, except four 6R alleles were distributed within the 11R-19R allele groups. The 14Rs revealed no further length variation while 7 out of the 92 rare alleles showed small length deviations from the other alleles within their respective groups. Nucleotide sequencing of the repeat array was performed in 17 alleles selected from each of the nine allele groups. The micro length variation within allele groups was caused by the presence of either 33, 36 or 37 bp repeats in given positions. A comparison of three 14Rs revealed no further sequence variation between these. Nine out of the fourteen repeats in the 14R differed in sequence and/or size. Based on this difference the repeat array sequence was converted into a code of different variant repeats. The 6R showed a variant repeat code quite unlike that of the 14R, while the encoded allele structure of the other rare alleles suggested that most of them may have evolved from a 14R allele by deletion or duplication of repeat units. Nucleotide sequencing of progenitor and mutant in a D7S22 de novo mutation as well as typing in a polymorphic site near the repeat array suggested that the event was an intra-allelic deletion of exactly three repeats. The present findings indicate that the 14R is ancestral to most rare small alleles, and that mutations in small alleles most often are intra-allelic events leading to a change in bp size equal to an integer number of repeats.
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Electrophoresis 16 (1995), S. 186-196 
    ISSN: 0173-0835
    Keywords: Genetics ; Two-dimensional electrophoresis ; Denaturing gradient electrophoresis ; Cystic fibrosis ; Mutation ; Breast cancer ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: A major effort in the analysis of DNA currently focuses on identifying genes and their pathological variants underlying disease. Once such disease genes have been isolated a major task of molecular medicine is to identify the spectrum of DNA sequence variations responsible for the aberrant function of such genes. These efforts, however, are hindered by the vast amount of genetic information to scan for variations and the limited capacity of analytical techniques in terms of accuracy and speed. Recently, a number of techniques were developed, so-called “genome scanning” techniques, which allow complete genomes to be analyzed for sequence variation in parallel, i.e., at multiple sites or loci simultaneously rather than serially at predefined loci. Here we present the background and applications of a particular electrophoretic parallel processing approach, generically termed two-dimensional DNA typing. The approach is based on separating DNA fragments by two-dimensional electrophoresis [1], including denaturing gradient gel electrophoresis, thus allowing hundreds of fragments to be simultaneously assessed by comparative analysis for variations in size and sequence. The method is suitable for hybridization analysis with locus-specific and multilocus probes of genomic DNA restriction fragments derived from human and other DNA, and for analysis of polymerase chain reaction (PCR) fragments derived from large genes. Two-dimensional DNA typing has been applied, e.g., in linkage analysis of pedigrees, analysis of tumor genomes for rearrangements, and to scan the cystic fibrosis transmembrane regulator gene for sequence variations such as point mutations.
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  • 5
    ISSN: 0173-0835
    Keywords: Capillary electrophoresis ; DNA melting ; Kinetics ; Mutation ; Separation efficiency ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Constant denaturant capillary electrophoresis (CDCE) separation takes place in the heated portion of the capillary where faster-moving, unmelted DNA fragments are in equilibrium with slower-moving, partially melted forms. Within a certain temperature range, the position of the melting equilibrium and thus the average electrophoretic mobility of each mutant is different. The resulting difference in mobility allow sequences containing single base pair point mutations to be separated from each other. We report the results of experiments in which we explored the rules defining separation efficiency by varying the parameters of CDCE. We discovered an unusual peak broadening mechanism. In contrast to most other DNA electrophoresis systems, peak width in CDCE steadily decreases with the square root of the separation speed. Moreover, the peak width displays a sharp maximum at a specific temperature. To account for these observations, we use a model which describes CDCE separation as a random walk. According to this model, peaks in CDCE are broad because the kinetics of the melting equilibrium are slow and there-fore the number of random walk steps represented by melting/renaturation transitions is relatively small. In addition to providing a satisfactory interpretation of the data, the model also predicts that separation efficiency will increase as the ionic strength of the running buffer is increased and as the concentration of denaturant in the buffer is decreased. These predictions were verified and were used to establish conditions for high-resolution CDCE suitable for separating complex mixtures of single base pair mutants.
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Electrophoresis 16 (1995), S. 719-721 
    ISSN: 0173-0835
    Keywords: Hypervariable DNA ; Mutation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Object of this investigation was the isolation of a single-locus probe from a multi-locus fingerprint. Individual specific multi-locus fingerprints in man were generated by using the oligonucleotide probe (ATTTT)5. An isolated (ATTTT)5-positive DNA fragment was analyzed using polymerase chain reaction (PCR) cycle-sequencing and nonradioactive direct-blotting electrophoresis. A digoxigenated oligonucleotide synthesized according to this sequence was used as a single-locus probe. Two hypervariable loci were detected on Southern blots. Formal genetic investigations for the two loci were performed in order to estimate the allele frequencies. Locus 1 shows an individual-specific banding pattern with an autosomal-codominant inheritance and can be used for forensic investigations. Locus 2 also represents a polymorphic pattern, but the inheritance is not according to the Mendelian rules. Probably we have detected a highly mutagenic locus in the human genome.
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  • 7
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 10 (1989), S. 460-472 
    ISSN: 0192-253X
    Keywords: Transposable elements ; Maize ; Mutation ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The high frequency of mutations in Mutator stocks of maize is the result of transposition of Mu elements. Nine different Mu elements that share the 220 bp Mu terminal inverted repeats have been described. Mul elements have been found inserted into most of the molecularly characterized mutant alleles isolated from Mutator stocks, and most Mutator stocks contain a high number of Mul elements (10-60). However, it is clear that additional Mu elements, which share the Mul termini but have unrelated internal sequences, can also transpose in Mutator stocks. We were interested in comparing the mutation frequency and type of elements that inserted into a particular locus when Mutator stocks with differing numbers of Mul elements were utilized. Furthermore, previous studies with Mu-induced mutations have demonstrated that the element that inserted most frequently was Mul. Therefore, to try to obtain Mu elements different from Mul we utilized a stock that had a low number (3-6) of Mul elements as well as a Mutator stock with a more typical number of Mul elements (20-60).Utilizing both stocks, we isolated numerous mutants at one gene, Bronze1 (Bz1), and compared the type of elements inserted. In this paper we report that both the high and low Mu1 stocks produced bz1 mutants at frequencies characteristic of Mutator stocks, 6.6 and 4.3 ± 10-5, respectively. We describe the isolation of 20 bz1 mutations, and the initial molecular characterization of eight unstable mutations: two from the high Mu1 stock and six from the low Mu1 stock. The six alleles isolated from the low Mu1 stock appear to contain deleted Mu1 elements, and the two alleles isolated from the high Mu1 stock contain elements very similar to Mu1. When the mutants from the low Mu1 stocks were examined, it was found that the Mu1 -related elements increased from 3-6 copies to 9-20 copies in one generation. The high number of Mu1 -related elements was maintained in subsequent out-crosses. This spontaneous activation and amplification of Mu -related elements occurred in at least 1% of the low Mu1 plants.
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Electrophoresis 16 (1995), S. 683-690 
    ISSN: 0173-0835
    Keywords: Gene diagnosis ; Microsatellites ; Mutation ; Simple repetitive DNA ; Multifactorial diseases ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: In principle, gene defects can be investigated directly or indirectly via informative polymorphisms in their vicinity. But because many defects are not yet defined molecularly, these inherited diseases can only be diagnosed indirectly via analysis of informative family situations. Since (multiple) mutation analyses, e.g. via DNA sequencing, are time-consuming and expensive, indirect analysis may still be performed initially - particularly in diseases caused by heterogenous mutations. We focus on diagnoses of neurological and (auto)immune diseases by polymerase chain reaction and separation of the DNA fragments via gel electrophoreses. Even after gene defects have been identified, indirect analysis might be necessary, for example in Huntington's chorea. Although this genetic defect has been characterized as a trinucleotide disease, indirect DNA diagnosis is still performed in particular cases for psychological reasons. The causes of autoimmune diseases are multifactorial and the inheritance is complex, involving several genes. Genome-wide screening programs may involve indirect approaches via analyses of polymorphic microsatellites. Large parts of the immunological genome can be covered when 20 or more genes are investigated simultaneously. Thus the genetic bases of autoimmune diseases are disclosed. Microsatellites themselves could have a biological meaning. We therefore discuss also DNA/protein interactions for simple tandem repeats, the major targets for indirect gene diagnoses. Only indirect evidence exists that certain simple repeats influence genomic (in)stability. Taken together, indirect gene diagnoses supplement direct approaches in a variety of different purposes and in combination with standard electrophoresis techniques.
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  • 9
    ISSN: 0173-0835
    Keywords: Minisatellite ; Mutation ; Recombination ; Conversion ; Sperm ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Minisatellites provide one of the most experimentally tractable systems for studying tandem repeat instability in man. Analysis of mutation processes has been greatly aided by the development of single molecule methods for recovering de novo mutants, and of techniques for exploring allele structure in detail. Application of these approaches to man has shown that minisatellites do not primarily mutate by processes such as replication slippage and unequal crossover intrinsic to the tandem repeat array. Instead, germline repeat instability is largely regulated by cis-acting elements near the array and involves unexpectedly complex processes of gene conversion, of potential relevance to the biology of meiosis. These processes can be explored both in humans and, in principle, in transgenic mouse models of human repeat instability.
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  • 10
    ISSN: 0173-0835
    Keywords: Conversion ; Minisatellite ; Mutation ; Radiation ; Recombination ; Tandem repeat ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Minisatellites provide not only the basis for DNA fingerprinting and DNA profiling but also extremely informative systems for analysing processes of tandem repeat turnover in the human genome. Minisatellite instability appears to involve distinct mutation processes in somatic and germline cells; in the germline, mutation is frequently dominated by inter-allelic conversion-like events most likely occurring at meiosis and apparently regulated by cis-acting mutation initiator elements. Attempts to define these initiators in transgenic mice have so far been thwarted by what appears to be a major human/mouse barrier to the inter-species transfer of repeat instability. Minisatellites not only show high frequency spontaneous mutation in the germline, but also appear to be very sensitive to mutation induction by ionizing radiation, both in experimentally irradiated mice and in human populations exposed following the Chernobyl disaster; the mechanisms of mutation induction by radiation remain enigmatic.
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