912 resultados para Genetic Analysis
Resumo:
Les théories poétiques de l’inscape et du sprung rhythm établies par le poète britannique Gerard Manley Hopkins (1844-1889) ont dérouté les critiques des années durant. La plupart d’entre eux se sont appuyés sur les poèmes publiés en quête d’indices quant à la signification de ses théories. Cette thèse approfondit l’analyse mise de l’avant en révélant que la genèse de la théorie de l’inscape provient des notes de Hopkins — alors étudiant de premier cycle — sur le philosophe présocratique Parménide, et est influencée par les commentaires sur l’oeuvre De la nature du philosophe. Un examen des lettres de Hopkins à ses collègues poètes Robert Bridges et Richard Watson Dixon révèle que le sprung rhythm découle de l’inscape, sa théorie de base. La technique du sprung rhythm consiste donc en l’application de l’inscape au schéma métrique de la poésie. Cette étude établit d’abord une définition opérationnelle de chacune de ces théories pour ensuite les appliquer aux manuscrits afin de déterminer dans quelle mesure Hopkins y adhérait et les exploitait lors de la rédaction de deux de ses poèmes canoniques, God’s Grandeur et The Windhover. L’étude s’inscrit ainsi dans le champ de la critique génétique, une approche mise au point en France, particulièrement à l’Institut des textes et manuscrits modernes (ITEM). Ce sont donc sur des oeuvres littéraires françaises ou sur des textes en prose qu’ont porté la majorité des analyses à ce sujet. Suppressions, ajouts, substitutions et constantes entre différentes versions témoignent de ce qu’étaient les priorités de Hopkins dans sa quête pour atteindre l’effet désiré. Par conséquent, cette thèse s’efforce de dévoiler la signification des théories poétiques de Hopkins en établissant leur genèse et leur application respectives dans deux de ses poèmes selon une perspective de critique génétique. Elle contribue également à enrichir la critique génétique en l’appliquant à des oeuvres littéraires écrites en anglais et sous forme de poésie plutôt que de prose. Enfin, son objectif ultime est de raviver l’intérêt pour le poète Hopkins en tant que sujet viable d’étude, et de favoriser l’appréciation de ses prouesses tant comme théoricien poétique que comme poète.
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2012
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Many, but not all, of the current 21 serotypes of Yersinia pseudotuberculosis have been investigated with regard to the chemical structures of their O-specific polysaccharide (OPS) and the genetic basis of their biosynthesis. Completion of the genetics and structures of the remaining serotypes will enhance our understanding of the emerging relationship between genetics and structures within this species. Here, we present a structural and genetic analysis of the Y. pseudotuberculosis serotype O:1c OPS. Our results showed that this OPS has the same backbone as Y. pseudotuberculosis O:2b, but with a 3,6-dideoxy-D-ribo-hexofuranose (paratofuranose, Parf) side-branch instead of a 3,6-dideoxy-D-xylo-hexopyranose (abequopyranose, Abep). The 3'-end of the gene cluster is the same as for O:2b and has the genes for synthesis of the backbone and for processing the completed repeat unit. The 5'-end of the cluster consists of the same genes as O:1b for synthesis of Parf and a related gene for its transfer to the repeating unit backbone.
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The native Asian oyster, Crassostrea ariakensis is one of the most common and important Crassostrea species that occur naturally along the coast of East Asia. Molecular species diagnosis is a prerequisite for population genetic analysis of wild oyster populations because oyster species cannot be discriminated reliably using external morphological characters alone due to character ambiguity. To date there have been few phylogeographic studies of natural edible oyster populations in East Asia, in particular this is true of the common species in Korea C. ariakensis. We therefore assessed the levels and patterns of molecular genetic variation in East Asian wild populations of C. ariakensis from Korea, Japan, and China using DNA sequence analysis of five concatenated mtDNA regions namely; 16S rRNA, cytochrome oxidase I, cytochrome oxidase II, cytochrome oxidase III, and cytochrome b. Two divergent C. ariakensis clades were identified between southern China and remaining sites from the northern region. In addition, hierarchical AMOVA and pairwise UST analyses showed that genetic diversity was discontinuous among wild populations of C. ariakensis in East Asia. Biogeographical and historical sea level changes are discussed as potential factors that may have influenced the genetic heterogeneity of wild C. ariakensis stocks across this region.
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Inter-simple sequence repeat (ISSR) analysis was used to assess genetic diversity among 10 pairs of male and female Laminaria gametophytes. A total of 58 amplification loci was obtained from 10 selected ISSR primers, of which 34 revealed polymorphism among the gametophytes. Genetic distances were calculated with the Dice coefficient ranging from 0.006 to 0.223. A dendrogram based on the unweighted pair-group method arithmetic (UPGMA) average showed that most male and female gametophytes of the same species were clustered together and that 10 pairs of gametophytes were divided into four groups. This was generally consistent with the taxonomic categories. The main group consisted of six pairs of gametophytes, which were selected from Laminaria japonica Aresch. by intensive inbreeding through artificial hybridization. One specific marker was cloned, but was not converted successfully into a sequence characterized amplified region (SCAR) marker. Our results demonstrate the feasibility of applying ISSR markers to evaluate Laminaria germplasm diversities.
Recent developments in genetic data analysis: what can they tell us about human demographic history?
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Over the last decade, a number of new methods of population genetic analysis based on likelihood have been introduced. This review describes and explains the general statistical techniques that have recently been used, and discusses the underlying population genetic models. Experimental papers that use these methods to infer human demographic and phylogeographic history are reviewed. It appears that the use of likelihood has hitherto had little impact in the field of human population genetics, which is still primarily driven by more traditional approaches. However, with the current uncertainty about the effects of natural selection, population structure and ascertainment of single-nucleotide polymorphism markers, it is suggested that likelihood-based methods may have a greater impact in the future.
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The 3'-terminal 853 nt (and the putative 283 aa) sequence of the VP2-encoding gene from 29 field strains of porcine parvovirus (PPV) were determined and compared both to each other and with other published sequences. Sequences were examined using maximum-parsimony and statistical analyses for nucleotide diversity and sequence variability. Among the nucleotide sequences of the PPV field strains, 26 polymorphic sites were encountered; 22 polymorphic sites were detected in the putative amino acid sequence. Mapping polymorphic sites of protein data onto the three-dimensional (3D) structure of PPV VP2 revealed that almost all substitutions were located on the external surface of the viral capsid. Mapping amino acid substitutions to the alignment between PPV VP2 sequences and the 3D structure of canine parvovirus (CPV) capsid, many PPV substitutions were observed to map to regions of recognized antigenicity and/or to contain phenotypically important residues for CPV and other parvoviruses. In spite of the high sequence similarity, genetic analysis has shown the existence of at least two virus lineages among the samples. In conclusion, these results highlight the need for close surveillance on PPV genetic drift, with an assessment of its potential ability to modify the antigenic make-up of the virus.
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The goal of many plant scientists’ research is to explain natural phenotypic variation in term of simple changes in DNA sequence. DNA-based molecular markers are extensively used for the construction of genome-wide molecular maps and to perform genetic analysis for simple and complex traits. The PhD thesis was divided into two main research lines according to the different approaches adopted. The first research line is to analyze the genetic diversity in an Italian apple germplasm collection for the identification of markers tightly linked to targeted genes by an association genetic method. This made it possible to identify synomym and homonym accessions and triploids. The fruit red skin color trait has been used to test the reliability of the genetic approaches in this species. The second line is related to the development of molecular markers closely linked to the Rvi13 and Rvi5 scab resistance genes, previously mapped on apple’s chromosome 10 and 17 respectively by using the traditional linkage mapping method. Both region have been fine-mapped with various type of markers that could be used for marker-assisted selection in future breeding programs and to isolate the two resistance genes.
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We have investigated genetic parentage in a Swiss population of tawny owls (Strix aluco). To this end, we performed genetic analysis for six polymorphic loci of 49 avian microsatellite loci tested for cross-species amplification. We found one extra-pair young out of 137 (0.7%) nestlings in 37 families (2.7%). There was no intra-specific brood parasitism. Our results are in accordance with previous findings for other raptors and owls that genetic monogamy is the rule. Female tawny owls cannot raise offspring without a substantial contribution by their mates. Hence one favoured hypothesis is that high paternal investment in reproduction selects for behaviour that prevents cuckoldry.
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With the identification of common single locus point mutations as risk factors for thrombophilia, many DNA testing methodologies have been described for detecting these variations. Traditionally, functional or immunological testing methods have been used to investigate quantitative anticoagulant deficiencies. However, with the emergence of the genetic variations, factor V Leiden, prothrombin 20210 and, to a lesser extent, the methylene tetrahydrofolate reductase (MTHFR677) and factor V HR2 haplotype, traditional testing methodologies have proved to be less useful and instead DNA technology is more commonly employed in diagnostics. This review considers many of the DNA techniques that have proved to be useful in the detection of common genetic variants that predispose to thrombophilia. Techniques involving gel analysis are used to detect the presence or absence of restriction sites, electrophoretic mobility shifts, as in single strand conformation polymorphism or denaturing gradient gel electrophoresis, and product formation in allele-specific amplification. Such techniques may be sensitive, but are unwielding and often need to be validated objectively. In order to overcome some of the limitations of gel analysis, especially when dealing with larger sample numbers, many alternative detection formats, such as closed tube systems, microplates and microarrays (minisequencing, real-time polymerase chain reaction, and oligonucleotide ligation assays) have been developed. In addition, many of the emerging technologies take advantage of colourimetric or fluorescence detection (including energy transfer) that allows qualitative and quantitative interpretation of results. With the large variety of DNA technologies available, the choice of methodology will depend on several factors including cost and the need for speed, simplicity and robustness. © 2000 Lippincott Williams & Wilkins.
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Germline mutations within the cyclin-dependent kinase inhibitor 2A (CDKN2A) gene and one of its targets, the cyclin dependent kinase 4 (CDK4) gene, have been identified in a proportion of melanoma kindreds. In the case of CDK4, only one specific mutation, resulting in the substitution of a cysteine for an arginine at codon 24 (R24C), has been found to be associated with melanoma. We have previously reported the identification of germline CDKN2A mutations in 7/18 Australian melanoma kindreds and the absence of the R24C CDK4 mutation in 21 families lacking evidence of a CDKN2A mutation. The current study represents an expansion of these efforts and includes a total of 48 melanoma families from Australia. All of these families have now been screened for mutations within CDKN2A and CDK4, as well as for mutations within the CDKN2A homolog and 9p21 neighbor, the CDKN2B gene, and the alternative exon 1 (E1beta) of CDKN2A. Families lacking CDKN2A mutations, but positive for a polymorphism(s) within this gene, were further evaluated to determine if their disease was associated with transcriptional silencing of one CDKN2A allele. Overall, CDKN2A mutations were detected in 3/30 (10%) of the new kindreds. Two of these mutations have been observed previously: a 24 bp duplication at the 5' end of the gene and a G to C transversion in exon 2 resulting in an M531 substitution. A novel G to A transition in exon 2, resulting in a D108N substitution was also detected. Combined with our previous findings, we have now detected germline CDKN2A mutations in 10/48 (21%) of our melanoma kindreds. In none of the 'CDKN2A-negative' families was melanoma found to segregate with either an untranscribed CDKN2A allele, an R24C CDK4 mutation, a CDKN2B mutation, or an E1beta mutation. The last three observations suggest that these other cell cycle control genes (or alternative gene products) are either not involved at all, or to any great extent, in melanoma predisposition.
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Genetic variation at allozyme and mitochondrial DNA loci was investigated in the Australian lungfish, Neoceratodus forsteri Krefft 1870. Tissue samples for genetic analysis were taken non-lethally from 278 individuals representing two spatially distinct endemic populations (Mary and Burnett rivers), as well as one population thought to be derived from an anthropogenic translocation in the 1890's (Brisbane river). Two of 24 allozyme loci resolved from muscle tissue were polymorphic. Mitochondrial DNA nucleotide sequence diversity estimated across 2,235 base pairs in each of 40 individuals ranged between 0.000423 and 0.001470 per river. Low genetic variation at allozyme and mitochondrial loci could be attributed to population bottlenecks, possibly induced by Pleistocene aridity. Limited genetic differentiation was detected among rivers using nuclear and mitochondrial markers suggesting that admixture may have occurred between the endemic Mary and Burnett populations during periods of low sea level when the drainages may have converged before reaching the ocean. Genetic data was consistent with the explanation that lungfish were introduced to the Brisbane river from the Mary river. Further research using more variable genetic loci is needed before the conservation status of populations can be determined, particularly as anthropogenic demands on lungfish habitat are increasing. In the interim we recommend a management strategy aimed at conserving existing genetic variation within and between rivers.
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Population-wide associations between loci due to linkage disequilibrium can be used to map quantitative trait loci (QTL) with high resolution. However, spurious associations between markers and QTL can also arise as a consequence of population stratification. Statistical methods that cannot differentiate between loci associations due to linkage disequilibria from those caused in other ways can render false-positive results. The transmission-disequilibrium test (TDT) is a robust test for detecting QTL. The TDT exploits within-family associations that are not affected by population stratification. However, some TDTs are formulated in a rigid-form, with reduced potential applications. In this study we generalize TDT using mixed linear models to allow greater statistical flexibility. Allelic effects are estimated with two independent parameters: one exploiting the robust within-family information and the other the potentially biased between-family information. A significant difference between these two parameters can be used as evidence for spurious association. This methodology was then used to test the effects of the fourth melanocortin receptor (MC4R) on production traits in the pig. The new analyses supported the previously reported results; i.e., the studied polymorphism is either causal of in very strong linkage disequilibrium with the causal mutation, and provided no evidence for spurious association.
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The incidence of Squamous Cell Carcinoma (SCG) is growing in certain populations to the extent that it is now the most common skin lesion in young men and women in high ultraviolet exposure regions such as Queensland. In terms of incidence up to 40% of the Australian population over 40 years of age is thought to possess the precancerous Solar Keratosis (SK) lesion and with a small, but significant, chance of progression into SCC, understanding the genetic events that play a role in this process is essential. The major aims of this study were to analyse whole blood derived samples for DNA aberrations in genes associated with tumour development and cellular maintenance, with the ultimate aim of identifying genes associated with non-melanoma skin cancer development. More specifically the first aim of this project was to analyse the SDHD and MMP12 genes via Dual-Labelled Probe Real-Time PCR for copy number aberrations in an affected Solar Keratosis and control cohort. It was found that 12 samples had identifiable copy-number aberrations in either the SDHD or MMP12 gene (this means that a genetic section of either of these two genes is aberrantly amplified or deleted), with five of the samples exhibiting aberrations in both genes. The significance of this study is the contribution to the knowledge of the genetic pathways that are malformed in the progression and development of the pre-cancerous skin lesion Solar Keratosis. © 2008 Springer Science+Business Media, LLC.