• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 11
  • 6
  • 4
  • 3
  • 1
  • 1
  • Tagged with
  • 29
  • 29
  • 14
  • 14
  • 11
  • 9
  • 6
  • 6
  • 6
  • 5
  • 5
  • 4
  • 4
  • 4
  • 4
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Tagging systems for sequencing large cohorts

Neiman, Mårten January 2010 (has links)
Advances in sequencing technologies constantly improves the throughput andaccuracy of sequencing instruments. Together with this development comes newdemands and opportunities to fully take advantage of the massive amounts of dataproduced within a sequence run. One way of doing this is by analyzing a large set ofsamples in parallel by pooling them together prior to sequencing and associating thereads to the corresponding samples using DNA sequence tags. Amplicon sequencingis a common application for this technique, enabling ultra deep sequencing andidentification of rare allelic variants. However, a common problem for ampliconsequencing projects is formation of unspecific PCR products and primer dimersoccupying large portions of the data sets. This thesis is based on two papers exploring these new kinds of possibilities andissues. In the first paper, a method for including thousands of samples in the samesequencing run without dramatically increasing the cost or sample handlingcomplexity is presented. The second paper presents how the amount of high qualitydata from an amplicon sequencing run can be maximized. The findings from the first paper shows that a two-tagging system, where the first tagis introduced by PCR and the second tag is introduced by ligation, can be used foreffectively sequence a cohort of 3500 samples using the 454 GS FLX Titaniumchemistry. The tagging procedure allows for simple and easy scalable samplehandling during sequence library preparation. The first PCR introduced tags, that arepresent in both ends of the fragments, enables detection of chimeric formation andhence, avoiding false typing in the data set. In the second paper, a FACS-machine is used to sort and enrich target DNA covered emPCR beads. This is facilitated by tagging quality beads using hybridization of afluorescently labeled target specific DNA probe prior to sorting. The system wasevaluated by sequencing two amplicon libraries, one FACS sorted and one standardenriched, on the 454 showing a three-fold increase of quality data obtained. / QC20100907
12

Applications of Four-Colour Fluorescent Primer Extension Technology for SNP Analysis and Discovery

Ahlford, Annika January 2010 (has links)
Studies on genetic variation can reveal effects on traits and disease, both in humans and in model organisms. Good technology for the analysis of DNA sequence variations is critical. Currently the development towards assays for large-scale and parallel DNA sequencing and genotyping is progressing rapidly. Single base primer extension (SBE) is a robust reaction principle based on four-colour fluorescent terminating nucleotides to interrogate all four DNA nucleotides in a single reaction. In this thesis, SBE methods were applied to the analysis and discovery of single nucleotide polymorphism (SNP) in the model organism Drosophila melanogaster and in humans. The tag-array minisequencing system in a microarray format is convenient for intermediate sized genotyping projects. The system is scalable and flexible to adapt to specialized and novel applications. In Study I of the thesis a tool was established to automate quality control of clustered genotype data. By calculating “Silhouette scores”, the SNP genotype assignment can be evaluated by a single numeric measure. Silhouette scores were then applied in Study I to compare the performance of four DNA polymerases and in Study III to evaluate freeze-dried reagents in the tag-array minisequencing system. The characteristics of the tag-array minisequencing system makes it suitable for inexpensive genome-wide gene mapping in the fruit fly. In Study II a high-resolution SNP map, and 293 genotyping assays, were established across the X, 2nd and 3rd chromosomes to distinguish commonly used Drosophila strains. A database of the SNP markers and a program for automatic allele calling and identification of map positions of mutants was also developed. The utility of the system was demonstrated by rapid mapping of 14 genes that disrupt embryonic muscle patterning. In Study III the tag-array minisequencing system was adapted to a lab-on-a-chip format for diagnostic testing for mutations in the TP53 gene. Freeze-drying was evaluated for storing reagents, including thermo-sensitive enzymes, on the microchip to reduce the complexity of the integrated test. Correct genotyping results were obtained using freeze-dried reagents in each reaction step of the genotyping protocol, both in test tubes and in single polymer test chambers. The results showed the potential of the approach to be implemented in fully integrated systems. The four-colour chemistry of SBE has been developed further to allow massively parallel sequencing (MPS) of short DNA fragments as in the Genome Analyzer system (Solexa/Illumina). In Study IV MPS was used to compare Nimblegen arrays and the SureSelect solution-based system for targeted enrichment of 56 continuous human candidate-gene regions totalling 3.1 Mb in size. Both methods detected known SNPs and discovered novel SNPs in the target regions, demonstrating the feasibility for complexity reduction of sequencing libraries by hybridization methods.
13

Genetic diagnosis and identification of novel genes in neuromuscular disorders using next generation sequencing / Diagnostic génétique et identification de nouveau gènes impliqués dans les maladies neuromusculaires par séquençage haut débit

Poursaeed, Nasim 17 December 2012 (has links)
Les maladies neuromusculaires sont des maladies souvent très sévères et très handicapantes, et un fardeau pour les patients, leurs familles, ainsi que pour le système de santé. Le but de ce projet était de mettre au point et de valider une approche de capture de séquence et de séquençage haut débit pour identifier les mutations en cause chez les patients atteints de maladies neuromusculaires et également trouver les nouveaux gènes qui sont impliqués dans une sous-classe de myopathies, les myopathies centronucléaires. Nous avons montré que l’approche de capture de séquence et de séquençage haut débit peux être utile dans le domaine des maladies neuromusculaires car elle est moins coûteuse que les approches conventionnelles « gène par gène » mise en oeuvre dans les laboratoires de diagnostics génétiques.Cette stratégie devrait élargir les spectres cliniques connus et identifier de nouvelles maladies alléliques (des mutations dans un gène causant différentes maladies). De plus, cela sera utile pour l’élargissement des connaissances sur les corrélations génotypes-phénotypes qui sont nécessaires à une prise en charge plus adaptée et au développement de stratégies thérapeutiques. / Neuromuscular disorders (NMD) are genetic diseases affecting muscles, nerves and neuromuscular junctions. They are rare and often severe with different age of onset from childhood to adulthood with significant burden to the patients, their families and public health system. For testing the possibility of using massively parallel sequencing as a routine technique in molecular diagnosis of neuromuscular disorders, the first aim of my PhD project was to use massively parallel sequencing technique in patients with different NMDs for disease-causing mutation detection. The second aim of my PhD project was to find novel gene(s) implicated in centronuclear myopathies (CNM). CNM are inherited neuromuscular disorders and a type of congenital myopathies, characterized mainly by presence of central and one or more internalized nuclei in muscle fibers with different severities and age of onset, using massively parallel sequencing. About 20% of CNM patients don’t have any mutations in four implicated genes. Disease- causing mutation(s)/ gene(s) in these patients need to be identified. We could show that next generation sequencing is a robust technique for gene identification if a homogenous cohort of patients is available and also is useful to use as a routine technique in molecular diagnosis as it istime and cost effective technique.
14

Integrative Analysis of Genomic Aberrations in Cancer and Xenograft Models

January 2015 (has links)
abstract: No two cancers are alike. Cancer is a dynamic and heterogeneous disease, such heterogeneity arise among patients with the same cancer type, among cancer cells within the same individual’s tumor and even among cells within the same sub-clone over time. The recent application of next-generation sequencing and precision medicine techniques is the driving force to uncover the complexity of cancer and the best clinical practice. The core concept of precision medicine is to move away from crowd-based, best-for-most treatment and take individual variability into account when optimizing the prevention and treatment strategies. Next-generation sequencing is the method to sift through the entire 3 billion letters of each patient’s DNA genetic code in a massively parallel fashion. The deluge of next-generation sequencing data nowadays has shifted the bottleneck of cancer research from multiple “-omics” data collection to integrative analysis and data interpretation. In this dissertation, I attempt to address two distinct, but dependent, challenges. The first is to design specific computational algorithms and tools that can process and extract useful information from the raw data in an efficient, robust, and reproducible manner. The second challenge is to develop high-level computational methods and data frameworks for integrating and interpreting these data. Specifically, Chapter 2 presents a tool called Snipea (SNv Integration, Prioritization, Ensemble, and Annotation) to further identify, prioritize and annotate somatic SNVs (Single Nucleotide Variant) called from multiple variant callers. Chapter 3 describes a novel alignment-based algorithm to accurately and losslessly classify sequencing reads from xenograft models. Chapter 4 describes a direct and biologically motivated framework and associated methods for identification of putative aberrations causing survival difference in GBM patients by integrating whole-genome sequencing, exome sequencing, RNA-Sequencing, methylation array and clinical data. Lastly, chapter 5 explores longitudinal and intratumor heterogeneity studies to reveal the temporal and spatial context of tumor evolution. The long-term goal is to help patients with cancer, particularly those who are in front of us today. Genome-based analysis of the patient tumor can identify genomic alterations unique to each patient’s tumor that are candidate therapeutic targets to decrease therapy resistance and improve clinical outcome. / Dissertation/Thesis / Doctoral Dissertation Biomedical Informatics 2015
15

Využití metody paralelního sekvenování při stanovování zešikmení X inaktivace / Use of massive parallel sequencing in determination of skewed X inactivation

Veselková, Tereza January 2016 (has links)
Skewed X chromosome inactivation has been often studied as a possible factor that influences manifestation of X-linked diseases in heterozygous women. Yet the association between phenotype and degree of skewing stays unclear for most disorders. Current works rely mostly on methods that are based on methyl-sensitive restriction while determining the X inactivation pattern and mainly the HUMARA assay which investigates the methylation profile in the AR gene. However those methods have some known disadvantages and therefore we are still seeking new methodical approaches. We used DNA isolated from whole blood and in some cases also buccal swabs to asses X inactivation patterns in 54 women using methylation-based methods for loci AR, CNKSR2 and RP2. Transcription-based assay was utilized to evaluate skewing of X inactivation in 32 of those women, whose samples were available for RNA extraction, using massive parallel sequencing and polymorphisms LAMP2 c.156A>T, IDS c.438C>T and ABCD1 c.1548G>A. Partly thanks to almost no stuttering during PCR the RP2 locus was the most informative in our study (71 % of women) and approximately the same number of women (69 %) were informative for the HUMARA assay. However when comparing the results of those two methods we determined difference greater than 10 % in...
16

Co-infecção Plasmodium falciparum e Schistosoma haematobium: papel dos genes HLA não-clássicos de classe I (HLA-G, -E e -F) na suscetibilidade à malária / Plasmodium falciparum and Schistosoma haematobium co-infection: role of non-classical HLA class I genes (HLA-G, -E and -F) in susceptibility to malaria

Paulin Sonon 31 October 2018 (has links)
A malária causada pelo Plasmodium falciparum (P. falciparum) e a bilharzíase urogenital causada pelo Schistosoma haematobium (S. haematobium) constituem duas doenças infecciosas tropicais alarmantes, sendo ambas endêmicas no Benin. Considerando que a malária (Th1) e a esquistossomose (Th2) apresentem perfis de citocinas divergentes, na presença de co-infecção, o S. haematobium poderia modular as respostas especificamente dirigidas contra o P. falciparum. Uma vez que, os genes que codificam as moléculas nãoclássicas de histocompatibilidade (HLA-G/-E/-F) possuam propriedades imunomoduladoras, pouca atenção tem sido dedicada ao estudo desses genes em populações da África Subsaariana, que são as de maior diversidade genética. O objetivo deste estudo foi avaliar a variabilidade dos genes HLA-G/-E/-F na população Toffin do Benin, e identificar fatores genéticos de suscetibilidade/resistência à malária causada pelo P. falciparum e/ou bilharziose urogenital, usando uma coorte de crianças (de 4 a 8 anos de idade) não aparentadas. Foram avaliados os segmentos codificantes e reguladores, englobando aproximadamente 5.1 kb do HLA-G, 7.7 kb do HLA-E e 6.2 kb do HLA-F, usando sequenciamento da nova geração. As frequências alélicas e haplotípicas do HLA-G/-E/-F, a diversidade genética, a diversidade nucleotídica, o equilíbrio de Hardy-Weinberg (HW) e de Tajima\'s D foram realizados utilizando o software ARLEQUIN v3.5.2. O desequilíbrio de ligação (LD) entre sítios variáveis com frequência alélica mínima (MAF) acima de 1% foi avaliado calculando o coeficiente de correlação r2 e os gráficos de LD foram visualizados usando o software Haploview 4.2. O estudo de associação foi implementada nos softwares PLINK v1.90b4.6 e R v3.4.2, usando modelos de regressão linear ou logística múltipla. 96, 37 e 68 sítios variáveis foram detectados ao longo de HLA-G/-E- F, respectivamente. Foram identificados 16, 19 e 15 haplótipos da promotora, 19, 15 e 29 haplótipos da codificadora, 12, 7 e 2 haplótipos da região 3\' não traduzida (3\'UTR), respectivamente, e ainda, 33 , 31 e 32 haplótipos estendidos, respectivamente. Todos os haplótipos promotores/codificadores/3\'UTR respeitaram os padrões já descritos na população mundial. O HLA-E foi o mais conservado, exibindo principalmente duas proteinas (E*01:01 e E*01:03), seguido do HLA-F, três proteínas (F*01:01, F*01:02 e F*01:03) e HLA-G, quatro proteínas: três normais (G*01:01, G*01:03 eSONON, P. Resumo xi G*01:04) e uma truncada (G*01:05N). Embora os alelos do HLA-G-E/-F observados na população Toffin tenham sido os mais frequentemente observados em vários países do mundo, as frequências dos haplótipos da região codificadora foram semelhantes às descritas para outras populações africanas (Guiné-Conakry e Burkina-Faso), quando comparadas com os países não-Africanos (Brasileiros), indicando que as variações ao longo desses genes estavam presentes nos Africanos antes da dispersão humana. Foram analisados 105 polimorfismos (MAF> 5%, valor P de HW> 0.05 e qualidade de genótipos> 97%) e 56 haplótipos com frequência mínima de 5%. Consideramos significativos, apenas os resultados exibindo valores de P <0.01 para polimorfismos e valores de P <0.01 antes da correção e valores de P <0.05 após correção de Bonferroni, para haplótipos. Encontramos as seguintes associações: i) o alelo inserção de 14 pares de bases do HLA-G (14 pb Ins) (em modelo dominante) foi associado ao risco de ocorrência de infecção por P. falciparum (infecções totais como infecções sintomáticas) e ao número de episódios de infecção (número elevado de episódios de infecções totais como de infecções sintomáticas), ii) polimorfismos HLA-G (- 1155 A e +755 A, em completo LD) (em modelo recessivo), e iii) haplótipo E.01.03.05- compatível em sinergia com o alelo -1988 C do HLA-E (em modelo aditivo) foram associados à proteção contra malária (em níveis de infecção como de densidade parasitária), e iv) o haplótipo E.Promo.2 foi associado à protecção contra a co-infecção do P. falciparum em crianças infectadas por S. haematobium. Excetuando o 14 pb Ins, estudos funcionais adicionais são necessários para revelar o papel desses marcadores na expressão dos genes HLA-G, -E e -F, para entender melhor o mecanismo de associação com doenças. / Plasmodium falciparum (P. falciparum) malaria and the urogenital bilharziasis caused by Schistosoma haematobium (S. haematobium) infection constitute the two alarming tropical infectious diseases; and both are endemic in Benin. Considering that malaria (Th1) and schistosomiasis (Th2) have divergent cytokine profiles, the presence of co-infection could modulate the responses specifically directed against P. falciparum. We hypothesize that the non-classical genes and molecules (HLA-G, -E and -F) of major histocompatibility complex (MHC) could be involved in this immunomodulation. Although these molecules have well known immunomodulatory properties, little attention has been devoted to the study of these non-classical class I HLA genes in sub-Saharan African populations. This study aimed to evaluate the diversity of HLA-G, -E and -F gene variable sites in the Beninese Toffin population, and to identify susceptibility/resistance genetic factors associated with P. falciparum malaria and/or urogenital bilharziasis in a Beninese cohort of unrelated schoolaged children (4 to 8 years old). We evaluated the complete gene variability (5.1 kb for HLAG, 7.7 kb for HLA-E and 6.2 kb for HLA-F) in the Beninese Toffin population using massive parallel sequencing. HLA-G, -E and -F allele and haplotype frequencies, gene diversity, average nucleotide diversity, Tajima\'s D and Hardy-Weinberg (HW) equilibrium were performed using ARLEQUIN v3.5.2 software. The linkage disequilibrium (LD) pattern among variable sites with a minimum allele frequency (MAF) above 1% was evaluated computing the correlation coefficient r2 and the LD plots were visualized using Haploview 4.2 software. The genetic association study was implemented on PLINK v1.90b4.6 and R v3.4.2 softwares using multiple logistic or linear regression models. Overall, 96, 37 and 68 variable sites were detected along the entire HLA-G, -E and -F, respectively, arranged into regionspecific haplotypes; i.e., promoter haplotypes (16, 19, and 15, respectively), coding haplotypes (19, 15, and 29, respectively), 3\' untranslated region (3\' UTR) haplotypes (12, 7 and 2, respectively) and extended haplotypes (33, 31 and 32, respectively). All promoter/coding/3\'UTR haplotypes followed the patterns already described in worldwide populations. Among the three genes, HLA-E was the most conserved, exhibiting mainly two full-length encoded-molecules (E*01:01 and E*01:03), followed by HLA-F (three full-lengthSONON, P. Abstract xiii proteins; F*01:01, F*01:02 and F*01:03) and HLA-G (four proteins; three full-length (G*01:01, G*01:03 and G*01:04) and one truncated (G*01:05N)). Although HLA-G/E/F alleles in the Toffin population were the most frequently observed worldwide, the frequencies of the coding haplotypes were closely similar to those described for other West African populations (Guinea-Conakry and Burkina-Faso) than for non-African ones (Brazilian population), indicating that variable sites along these genes were present in Africa before human dispersion. A total of 105 polymorphisms and 56 haplotypes were analyzed in the genetic association study to malaria and schistosomiasis susceptibility. Only results exhibiting respectively P-values < 0.01 and P-values < 0.05 (after Bonferroni correction) for polymorphisms and for haplotypes were considered as significant. The following associations were observed: i) HLA-G 14 base pairs (14bp) insertion was associated (under dominant model) with the risk of the occurrence of P. falciparum infection (all infections and symptomatic infections) and with high number of infection episodes (all infections and symptomatic infections), ii) HLA-G -1155 A and +755 A alleles (under recessive model) and iii) E.01.03.05-compatible haplotype in synergy with HLA-E -1988 C allele (under additive model) were associated with protection against P. falciparum (at infection as well as parasitic levels), and finally iv) the E.Promo.2 haplotype was associated with protection against malaria-schistosomiasis co-infection. The functional role of the genetic markers (alleles or haplotypes) associated with malaria and schistosomiasis suceptibility/resistance need to be investigated to better understand the mechanism that may explain these associations.
17

Co-infecção Plasmodium falciparum e Schistosoma haematobium: papel dos genes HLA não-clássicos de classe I (HLA-G, -E e -F) na suscetibilidade à malária / Plasmodium falciparum and Schistosoma haematobium co-infection: role of non-classical HLA class I genes (HLA-G, -E and -F) in susceptibility to malaria

Sonon, Paulin 31 October 2018 (has links)
A malária causada pelo Plasmodium falciparum (P. falciparum) e a bilharzíase urogenital causada pelo Schistosoma haematobium (S. haematobium) constituem duas doenças infecciosas tropicais alarmantes, sendo ambas endêmicas no Benin. Considerando que a malária (Th1) e a esquistossomose (Th2) apresentem perfis de citocinas divergentes, na presença de co-infecção, o S. haematobium poderia modular as respostas especificamente dirigidas contra o P. falciparum. Uma vez que, os genes que codificam as moléculas nãoclássicas de histocompatibilidade (HLA-G/-E/-F) possuam propriedades imunomoduladoras, pouca atenção tem sido dedicada ao estudo desses genes em populações da África Subsaariana, que são as de maior diversidade genética. O objetivo deste estudo foi avaliar a variabilidade dos genes HLA-G/-E/-F na população Toffin do Benin, e identificar fatores genéticos de suscetibilidade/resistência à malária causada pelo P. falciparum e/ou bilharziose urogenital, usando uma coorte de crianças (de 4 a 8 anos de idade) não aparentadas. Foram avaliados os segmentos codificantes e reguladores, englobando aproximadamente 5.1 kb do HLA-G, 7.7 kb do HLA-E e 6.2 kb do HLA-F, usando sequenciamento da nova geração. As frequências alélicas e haplotípicas do HLA-G/-E/-F, a diversidade genética, a diversidade nucleotídica, o equilíbrio de Hardy-Weinberg (HW) e de Tajima\'s D foram realizados utilizando o software ARLEQUIN v3.5.2. O desequilíbrio de ligação (LD) entre sítios variáveis com frequência alélica mínima (MAF) acima de 1% foi avaliado calculando o coeficiente de correlação r2 e os gráficos de LD foram visualizados usando o software Haploview 4.2. O estudo de associação foi implementada nos softwares PLINK v1.90b4.6 e R v3.4.2, usando modelos de regressão linear ou logística múltipla. 96, 37 e 68 sítios variáveis foram detectados ao longo de HLA-G/-E- F, respectivamente. Foram identificados 16, 19 e 15 haplótipos da promotora, 19, 15 e 29 haplótipos da codificadora, 12, 7 e 2 haplótipos da região 3\' não traduzida (3\'UTR), respectivamente, e ainda, 33 , 31 e 32 haplótipos estendidos, respectivamente. Todos os haplótipos promotores/codificadores/3\'UTR respeitaram os padrões já descritos na população mundial. O HLA-E foi o mais conservado, exibindo principalmente duas proteinas (E*01:01 e E*01:03), seguido do HLA-F, três proteínas (F*01:01, F*01:02 e F*01:03) e HLA-G, quatro proteínas: três normais (G*01:01, G*01:03 eSONON, P. Resumo xi G*01:04) e uma truncada (G*01:05N). Embora os alelos do HLA-G-E/-F observados na população Toffin tenham sido os mais frequentemente observados em vários países do mundo, as frequências dos haplótipos da região codificadora foram semelhantes às descritas para outras populações africanas (Guiné-Conakry e Burkina-Faso), quando comparadas com os países não-Africanos (Brasileiros), indicando que as variações ao longo desses genes estavam presentes nos Africanos antes da dispersão humana. Foram analisados 105 polimorfismos (MAF> 5%, valor P de HW> 0.05 e qualidade de genótipos> 97%) e 56 haplótipos com frequência mínima de 5%. Consideramos significativos, apenas os resultados exibindo valores de P <0.01 para polimorfismos e valores de P <0.01 antes da correção e valores de P <0.05 após correção de Bonferroni, para haplótipos. Encontramos as seguintes associações: i) o alelo inserção de 14 pares de bases do HLA-G (14 pb Ins) (em modelo dominante) foi associado ao risco de ocorrência de infecção por P. falciparum (infecções totais como infecções sintomáticas) e ao número de episódios de infecção (número elevado de episódios de infecções totais como de infecções sintomáticas), ii) polimorfismos HLA-G (- 1155 A e +755 A, em completo LD) (em modelo recessivo), e iii) haplótipo E.01.03.05- compatível em sinergia com o alelo -1988 C do HLA-E (em modelo aditivo) foram associados à proteção contra malária (em níveis de infecção como de densidade parasitária), e iv) o haplótipo E.Promo.2 foi associado à protecção contra a co-infecção do P. falciparum em crianças infectadas por S. haematobium. Excetuando o 14 pb Ins, estudos funcionais adicionais são necessários para revelar o papel desses marcadores na expressão dos genes HLA-G, -E e -F, para entender melhor o mecanismo de associação com doenças. / Plasmodium falciparum (P. falciparum) malaria and the urogenital bilharziasis caused by Schistosoma haematobium (S. haematobium) infection constitute the two alarming tropical infectious diseases; and both are endemic in Benin. Considering that malaria (Th1) and schistosomiasis (Th2) have divergent cytokine profiles, the presence of co-infection could modulate the responses specifically directed against P. falciparum. We hypothesize that the non-classical genes and molecules (HLA-G, -E and -F) of major histocompatibility complex (MHC) could be involved in this immunomodulation. Although these molecules have well known immunomodulatory properties, little attention has been devoted to the study of these non-classical class I HLA genes in sub-Saharan African populations. This study aimed to evaluate the diversity of HLA-G, -E and -F gene variable sites in the Beninese Toffin population, and to identify susceptibility/resistance genetic factors associated with P. falciparum malaria and/or urogenital bilharziasis in a Beninese cohort of unrelated schoolaged children (4 to 8 years old). We evaluated the complete gene variability (5.1 kb for HLAG, 7.7 kb for HLA-E and 6.2 kb for HLA-F) in the Beninese Toffin population using massive parallel sequencing. HLA-G, -E and -F allele and haplotype frequencies, gene diversity, average nucleotide diversity, Tajima\'s D and Hardy-Weinberg (HW) equilibrium were performed using ARLEQUIN v3.5.2 software. The linkage disequilibrium (LD) pattern among variable sites with a minimum allele frequency (MAF) above 1% was evaluated computing the correlation coefficient r2 and the LD plots were visualized using Haploview 4.2 software. The genetic association study was implemented on PLINK v1.90b4.6 and R v3.4.2 softwares using multiple logistic or linear regression models. Overall, 96, 37 and 68 variable sites were detected along the entire HLA-G, -E and -F, respectively, arranged into regionspecific haplotypes; i.e., promoter haplotypes (16, 19, and 15, respectively), coding haplotypes (19, 15, and 29, respectively), 3\' untranslated region (3\' UTR) haplotypes (12, 7 and 2, respectively) and extended haplotypes (33, 31 and 32, respectively). All promoter/coding/3\'UTR haplotypes followed the patterns already described in worldwide populations. Among the three genes, HLA-E was the most conserved, exhibiting mainly two full-length encoded-molecules (E*01:01 and E*01:03), followed by HLA-F (three full-lengthSONON, P. Abstract xiii proteins; F*01:01, F*01:02 and F*01:03) and HLA-G (four proteins; three full-length (G*01:01, G*01:03 and G*01:04) and one truncated (G*01:05N)). Although HLA-G/E/F alleles in the Toffin population were the most frequently observed worldwide, the frequencies of the coding haplotypes were closely similar to those described for other West African populations (Guinea-Conakry and Burkina-Faso) than for non-African ones (Brazilian population), indicating that variable sites along these genes were present in Africa before human dispersion. A total of 105 polymorphisms and 56 haplotypes were analyzed in the genetic association study to malaria and schistosomiasis susceptibility. Only results exhibiting respectively P-values < 0.01 and P-values < 0.05 (after Bonferroni correction) for polymorphisms and for haplotypes were considered as significant. The following associations were observed: i) HLA-G 14 base pairs (14bp) insertion was associated (under dominant model) with the risk of the occurrence of P. falciparum infection (all infections and symptomatic infections) and with high number of infection episodes (all infections and symptomatic infections), ii) HLA-G -1155 A and +755 A alleles (under recessive model) and iii) E.01.03.05-compatible haplotype in synergy with HLA-E -1988 C allele (under additive model) were associated with protection against P. falciparum (at infection as well as parasitic levels), and finally iv) the E.Promo.2 haplotype was associated with protection against malaria-schistosomiasis co-infection. The functional role of the genetic markers (alleles or haplotypes) associated with malaria and schistosomiasis suceptibility/resistance need to be investigated to better understand the mechanism that may explain these associations.
18

Methods for Analyzing Genomes

Ståhl, Patrik L. January 2010 (has links)
The human genome reference sequence has given us a two‐dimensional blueprint of our inherited code of life, but we need to employ modern‐day technology to expand our knowledge into a third dimension. Inter‐individual and intra‐individual variation has been shown to be larger than anticipated, and the mode of genetic regulation more complex. Therefore, the methods that were once used to explain our fundamental constitution are now used to decipher our differences. Over the past four years, throughput from DNA‐sequencing platforms has increased a thousand‐fold, bearing evidence of a rapid development in the field of methods used to study DNA and the genomes it constitutes. The work presented in this thesis has been carried out as an integrated part of this technological evolution, contributing to it, and applying the resulting solutions to answer difficult biological questions. Papers I and II describe a novel approach for microarray readout based on immobilization of magnetic particles, applicable to diagnostics. As benchmarked on canine mitochondrial DNA, and human genomic DNA from individuals with cystic fibrosis, it allows for visual interpretation of genotyping results without the use of machines or expensive equipment. Paper III outlines an automated and cost‐efficient method for enrichment and titration of clonally amplified DNA‐libraries on beads. The method uses fluorescent labeling and a flow‐cytometer to separate DNA‐beads from empty ones. At the same time the fraction of either bead type is recorded, and a titration curve can be generated. In paper IV we combined the highly discriminating multiplex genotyping of trinucleotide threading with the digital readout made possible by massively parallel sequencing. From this we were able to characterize the allelic distribution of 88 obesity related SNPs in a population of 462 individuals enrolled at a childhood obesity center. Paper V employs the throughput of present day DNA sequencingas it investigates deep into sun‐exposed skin to find clues on the effects of sunlight during the course of a summer holiday. The tumor suppressor p53 gene was targeted, only to find that despite its well‐documented involvement in the disease progression of cancers, an estimated 35,000 novel sun‐induced persistent p53 mutations are added and phenotypically tolerated in the skin of every individual every year. The last paper, VI, describes a novel approach for finding breast cancer biomarkers. In this translational study we used differential protein expression profiles and sequence capture to select and enrich for 52 candidate genes in DNA extracted from ten tumors. Two of the genes turned out to harbor protein‐altering mutations in multiple individuals.
19

Desenvolvimento de marcadores de microssatélites e diversidade genética em acessos de Lippia alba (Mill.) N.E.Br. (Verbenaceae)

Lopes, Juliana Mainenti Leal 03 March 2015 (has links)
Submitted by isabela.moljf@hotmail.com (isabela.moljf@hotmail.com) on 2017-04-27T13:44:40Z No. of bitstreams: 1 julianamainentileallopes.pdf: 2178130 bytes, checksum: ac4968430d3e36932e81380861925cd4 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-05-12T15:49:17Z (GMT) No. of bitstreams: 1 julianamainentileallopes.pdf: 2178130 bytes, checksum: ac4968430d3e36932e81380861925cd4 (MD5) / Made available in DSpace on 2017-05-12T15:49:17Z (GMT). No. of bitstreams: 1 julianamainentileallopes.pdf: 2178130 bytes, checksum: ac4968430d3e36932e81380861925cd4 (MD5) Previous issue date: 2015-03-03 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / CNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico / FAPEMIG - Fundação de Amparo à Pesquisa do Estado de Minas Gerais / Estudos recentes sugerem que a duplicação completa dos genomas é muito mais comum do que sua estabilidade, ocorrendo em todas as angiospermas. Nesse contexto, Lippia alba (Mill.) N.E.Br. (Verbenaceae) constitui um modelo interessante de estudo, pois além de ser a espécie mais estudada dentro do gênero Lippia, é amplamente utilizada na medicina popular apresentando importância econômica, sobretudo em função da riqueza de seus óleos essenciais. Estudos recentes demonstraram a existência de pelo menos cinco diferentes níveis de ploidia em Lippia alba, revelando grande plasticidade do genoma. A fim de contribuir para entender a variação genética e o processo de poliploidização em Lippia alba, o presente trabalho objetivou identificar novos marcadores genéticos do tipo microssatélite e estimar a diversidade genética em 100 acessos de Lippia alba. Foram avaliados nove loci já descritos e 16 novos marcadores. O tamanho dos fragmentos foi detectado por eletroforese capilar usando o sequenciador MegaBACE1000 (GE Healthcare, Buckinghamshire, UK). A identificação dos alelos foi inferida utilizando o software Fragment Profile (GE Healthcare, Buckinghamshire, UK). Os dados finais foram exportados para uma planilha do Excel® e foram transformados nos arquivos de entrada específicos para cada programa computacional. Os valores de PIC (polymorphism information content) e heterozigosidade foram calculados por meio do programa Cervus v3.0.7. Os coeficientes de similaridades de Jaccard e Dice foram calculados para construir um dendrograma de acordo com o algoritmo UPGMA (Unweighted Pair Group Method with Arithmetic Mean) por meio dos softwares NTSYS e PAST. Para a análise por inferência Bayesiana, foi utilizado o programa STRUCTURE v 2.3.4. Foi possível observar a formação de grupos de acordo com o nível de ploidia e inferir a possível origem de alguns citótipos baseada na similaridade genética entre os acessos. Os resultados contribuem para fortalecer a hipótese de que os acessos tenham surgido por autopoliploidia. / Recent studies suggest that complete genome duplication is much more common than its stability, occurring in almost all angiosperms. Lippia alba (Mill.) N.E.Br. (Verbenaceae), is the most studied species within the genus Lippia, and it is widely used in folk medicine presenting economic importance mainly due to the richness of their essential oils. Recent studies have demonstrated the existence of at least five different ploidy levels in Lippia alba revealing a large genome plasticity making the species an interesting model of study. To better understand the genetic variation and the polyploidization process in Lippia alba, this study aimed to identify new genetic microsatellite markers and estimate the genetic diversity for 100 Lippia alba accessions. We assessed 9 loci already described and 16 new markers. The size of the fragments was detected by capillary electrophoresis using MegaBACE1000 sequencer (GE Healthcare, Buckinghamshire, UK). The identification of alleles was inferred using the Fragment Profile software (GE Healthcare, Buckinghamshire, UK). Final data were exported to an Excel spreadsheet according to the input files of each software used. PIC values (polymorphism information content) and heterozygosity were calculated using Cervus v3.0.7 software. Jaccard and Dice similarity coefficient were calculated to construct a dendrogram according to UPGMA algorithm (Unweighted Pair Group Method with Arithmetic Mean) using NTSYS and PAST softwares. Bayesian inference analysis was performed using STRUCTURE v 2.3.4 program. It was possible to observe the formation of groups according to the ploidy level and infer the possible origin of some cytotypes based on genetic similarity among accessions. Results contribute to support the hypothesis that the cytotypes have emerged by autopolyploidy.
20

Mapeamento cromossômico de DNA satélite e comportamento meiótico no complexo Poliploide Lippia alba (Mill.) N. E. Br.

Reis, Aryane Campos 03 March 2017 (has links)
Submitted by isabela.moljf@hotmail.com (isabela.moljf@hotmail.com) on 2017-08-18T10:44:31Z No. of bitstreams: 1 aryanecamposreis.pdf: 2882567 bytes, checksum: 1a13439227f336c21faf2248369b319c (MD5) / Rejected by Adriana Oliveira (adriana.oliveira@ufjf.edu.br), reason: on 2017-08-18T12:29:10Z (GMT) / Submitted by isabela.moljf@hotmail.com (isabela.moljf@hotmail.com) on 2017-08-18T13:17:38Z No. of bitstreams: 1 aryanecamposreis.pdf: 2882567 bytes, checksum: 1a13439227f336c21faf2248369b319c (MD5) / Rejected by Adriana Oliveira (adriana.oliveira@ufjf.edu.br), reason: on 2017-08-24T11:27:59Z (GMT) / Submitted by isabela.moljf@hotmail.com (isabela.moljf@hotmail.com) on 2017-08-24T15:19:15Z No. of bitstreams: 0 / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-08-30T14:32:15Z (GMT) No. of bitstreams: 0 / Made available in DSpace on 2017-08-30T14:32:15Z (GMT). No. of bitstreams: 0 Previous issue date: 2017-03-03 / Lippia alba (Verbenaceae), é uma espécie herbácea tropical com grande plasticidade fenotípica e genômica, amplamente utilizada na medicina popular. Recentemente, a espécie foi descrita como um novo complexo autopoliploide contendo cinco números cromossômicos (2x=30, 2x=30+8, 3x=45, 4x=60 e 6x=90), e esforços têm sido feitos a fim de entender sua origem e evolução. No presente trabalho, foram descritos perfis cariotípicos mais detalhados da espécie, por meio de mapeamento cromossômico utilizando sondas espécie-específicas e análises do comportamento meiótico e de viabilidade polínica. A partir do sequenciamento genômico de baixa cobertura (IIlumina MiSeq), foram desenvolvidos novos marcadores citogenéticos (denominados CL66 e CL98) os quais foram utilizados para o mapeamento cromossômico em acessos representando os cinco citótipos do complexo. Para a análise meiótica, seis estágios da divisão (metáfase I; anáfase I + telófase I; metáfase II; anáfase II + telófase II) foram quantificados, e aproximadamente, 100 células foram avaliadas para cada estágio. Os mesmos acessos foram avaliados quanto à viabilidade polínica (1.000 grãos de pólen foram quantificados para cada indivíduo). Os resultados da Hibridização Fluorescente in situ (FISH) revelaram que ambas as repetições satélite estão localizadas na porção terminal dos cromossomos. Em geral, a repetição CL98 mostrou um padrão uniforme nos diferentes acessos. Foram observados dois, três, quatro e seis cromossomos marcados em diploides, triploides, tetraploides e hexaploide, respectivamente, revelando que o número de cromossomos marcados variou proporcionalmente, de acordo com o nível de ploidia do acesso. Por outro lado, a repetição CL66 apresentou-se polimórfica. Variações foram observadas entre os acessos, principalmente, entre os indivíduos diploides. Com relação às análises meióticas, alto percentual de irregularidade foi observado nos citótipos poliploides. Entretanto, alguns acessos 2x também mostraram consideráveis erros durante a microsporogênese. Entre as irregularidades encontradas, destacam-se: pareamento cromossômico anormal; segregação cromossômica desigual; cromossomos perdidos; tríades e políades. Os resultados da viabilidade polínica corroboraram os dados da meiose. A partir do conjunto de dados obtidos foi possível concluir que 1) a metodologia para o desenvolvimento de marcadores cromossômicos específicos para L. alba mostrou-se eficiente; 2) as repetições satélite exibiram diferentes comportamentos (estável e dinâmico) no genoma de L. alba; 3) a ocorrência de microsporogênese irregular em diploides, associada à viabilidade polínica, sugerem que os acessos 2x sejam elementos importantes na formação do complexo poliploide e 4) a ampla variação cariotípica observada na espécie pode ser consequência de múltiplos e independentes eventos de duplicação genômica, aliado a rearranjos cromossômicos. Possivelmente, L. alba encontra-se em processo de estabilização do seu cariótipo tornando a espécie, um importante modelo para estudos de poliploides naturais nos trópicos. / Lippia alba (Verbenaceae) is a tropical aromatic shrub with extensive phenotypical and genomic plasticity widely used in traditional medicine. Recently, the species was described as a new natural autopolyploid complex with five distinct chromosome numbers (2x=30, 2x=30+8, 3x=45, 4x=60 and 6x=90). Strides have been done in order to understand the cytotypes origin and species evolution. In this study, a detailed karyotype of L. alba using Fluorescence in situ Hybridization (FISH) with species-specific probes was described. We also report the meiosis behavior and pollen viability in sixty accessions. Using massive parallel sequencing (IIlumina MiSeq platform) new cytogenetic landmarks (CL66 and CL98) were chosen for probing all cytotypes described for the species. For meiotic analysis, the percentage of abnormalities was quantified, evaluating around 100 cells in six stages (metaphase I; anaphase I + telophase I; metaphase II; anaphase II + telophase II). Around 1,000 pollen per accession were used to estimate pollen viability. FISH results revealed that both satDNA arrays are located preferentially on terminal sites of the chromosomes. In general, the CL98 repeat showed a uniform pattern in different accessions. We observed 2, 3, 4, and 6 marked chromosomes respectively in diploid, triploid, tetraploid and hexaploid accessions revealing that the number of depicted chromosomes varied proportionally according to the ploidy level. On the other hand, the CL66 repeat was polymorphic. Great variations were observed among the accessions mainly within the diploids. In general, the meiotic analysis revealed higher index of abnormalities in polyploid cytotypes. However, some 2x accessions also showed considerable irregularities during the microsporogenesis. Desynapsis, unequal segregation, lost chromosomes, triads and polyads were the most common irregularities observed. Pollen viability analysis corroborated the meiosis data. It was possible to conclude that 1) the development of specific landmarks for L. alba was efficient; 2) the karyotypic profiles of both satDNA revealed different behavior; 3) microsporogenesis analysis and pollen viability of 2x accessions suggest that diploids are the key point for the origin of the polyploid complex and 4) independent and multiples events of genome duplication associated to chromosome rearrangements may have generated great karyotypic variation in the species. L. alba karyotype is possibly under stabilization process making the species an important model to study natural polyploids in the tropics.

Page generated in 0.2278 seconds