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  • 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.
71

DNA microarray for authentication of medicinal dendrobium species. / CUHK electronic theses & dissertations collection

January 2003 (has links)
by Zhang Yanbo. / "December 2003." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references (p. 163-185). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.
72

Bioinformatics analyses for next-generation sequencing of plasma DNA.

January 2012 (has links)
1997年,Dennis等證明胚胎DNA在孕婦母體中存在的事實開啟了產前無創診斷的大門。起初的應用包括性別鑒定和恒河猴血型系統的識別。隨著二代測序的出現和發展,對外周血游離DNA更加成熟的分析和應用應運而生。例如當孕婦懷孕十二周時, 應用二代測序技術在母體外周血DNA中預測胎兒21號染色體是否是三倍體, 其準確性達到98%。本論文的第一部分介紹如何應用母體外周血DNA構建胎兒的全基因組遺傳圖譜。這項研究極具挑戰,原因是孕後12周,胎兒對外周血DNA貢獻很小,大多數在10%左右,另外外周血中的胎兒DNA大多數短於200 bp。目前的演算法和程式都不適合於從母體外周血DNA中構建胎兒的遺傳圖譜。在這項研究中,根據母親和父親的基因型,用生物資訊學手段先構建胎兒可能有的遺傳圖譜,然後將母體外周血DNA的測序資訊比對到這張可能的遺傳圖譜上。如果在母親純和遺傳背景下,決定父親的特異遺傳片段,只要定性檢測父親的特異遺傳片段是否在母體外周血中存在。如果在母親雜合遺傳背景下,決定母親的遺傳特性,就要進行定量分析。我開發了單倍型相對劑量分析方案,統計學上判斷母親外周血中的兩條單倍型相對劑量水準,顯著增加的單倍型即為最大可能地遺傳給胎兒的單倍型。單倍型相對劑量分析方案可以加強測序資訊的分析效率,降低測序數據波動,比單個位點分析更加穩定,強壯。 / 隨著靶標富集測序出現,測序價格急劇下降。第一部分運用母親父親的多態位點基因型的組合加上測序的資訊可以計算出胎兒DNA在母體外周血中的濃度。但是該方法的局限是要利用母親父親的多態位點的基因型,而不能直接從測序的資訊中推測胎兒DNA在母體外周血中的濃度。本論文的第二部分,我開發了基於二項分佈的混合模型直接預測胎兒DNA在母體外周血中的濃度。當混合模型的似然值達到最大的時候,胎兒DNA在母體外周血中的濃度得到最優估算。由於靶標富集測序可以提供高倍覆蓋的測序資訊,從而有機會直接根據概率模型識別出母親是純和而且胎兒是雜合的有特異信息量的位點。 / 除了母體外周血DNA水準分析推動產前無創診斷外,表觀遺傳學的分析也不容忽視。 在本論文的第三部分,我開發了Methyl-Pipe軟體,專門用於全基因組的甲基化的分析。甲基化測序數據分析比一般的基因組測序分析更加複雜。由於重亞硫酸鹽測序文庫的沒有甲基化的胞嘧啶轉化成尿嘧啶,最後以胸腺嘧啶的形式存在PCR產物中, 但是對於甲基化的胞嘧啶則保持不變。 因此,為了實現將重亞硫酸鹽處理過的測序序列比對到參考基因組。首先,分別將Watson和Crick鏈的參考基因組中胞嘧啶轉化成全部轉化為胸腺嘧啶,同時也將測序序列中的胞嘧啶轉化成胸腺嘧啶。然後將轉化後的測序序列比對到參考基因組上。最後根據比對到基因組上的測序序列中的胞嘧啶和胸腺嘧啶的含量推到全基因組的甲基化水準和甲基化特定模式。Methyl-Pipe可以用於識別甲基化水平顯著性差異的基因組區別,因此它可以用於識別潛在的胎兒特異的甲基化位點用於產前無創診斷。 / The presence of fetal DNA in the cell-free plasma of pregnant women was first described in 1997. The initial clinical applications of this phenomenon focused on the detection of paternally inherited traits such as sex and rhesus D blood group status. The development of massively parallel sequencing technologies has allowed more sophisticated analyses on circulating cell-free DNA in maternal plasma. For example, through the determination of the proportional representation of chromosome 21 sequences in maternal plasma, noninvasive prenatal diagnosis of fetal Down syndrome can be achieved with an accuracy of >98%. In the first part of my thesis, I have developed bioinformatics algorithms to perform genome-wide construction of the fetal genetic map from the massively parallel sequencing data of the maternal plasma DNA sample of a pregnant woman. The construction of the fetal genetic map through the maternal plasma sequencing data is very challenging because fetal DNA only constitutes approximately 10% of the maternal plasma DNA. Moreover, as the fetal DNA in maternal plasma exists as short fragments of less than 200 bp, existing bioinformatics techniques for genome construction are not applicable for this purpose. For the construction of the genome-wide fetal genetic map, I have used the genome of the father and the mother as scaffolds and calculated the fractional fetal DNA concentration. First, I looked at the paternal specific sequences in maternal plasma to determine which portions of the father’s genome had been passed on to the fetus. For the determination of the maternal inheritance, I have developed the Relative Haplotype Dosage (RHDO) approach. This method is based on the principle that the portion of maternal genome inherited by the fetus would be present in slightly higher concentration in the maternal plasma. The use of haplotype information can enhance the efficacy of using the sequencing data. Thus, the maternal inheritance can be determined with a much lower sequencing depth than just looking at individual loci in the genome. This algorithm makes it feasible to use genome-wide scanning to diagnose fetal genetic disorders prenatally in a noninvasive way. / As the emergence of targeted massively parallel sequencing, the sequencing cost per base is reducing dramatically. Even though the first part of the thesis has already developed a method to estimate fractional fetal DNA concentration using parental genotype informations, it still cannot be used to deduce the fractional fetal DNA concentration directly from sequencing data without prior knowledge of genotype information. In the second part of this thesis, I propose a statistical mixture model based method, FetalQuant, which utilizes the maximum likelihood to estimate the fractional fetal DNA concentration directly from targeted massively parallel sequencing of maternal plasma DNA. This method allows fetal DNA concentration estimation superior to the existing methods in term of obviating the need of genotype information without loss of accuracy. Furthermore, by using Bayes’ rule, this method can distinguish the informative SNPs where mother is homozygous and fetus is heterozygous, which is potential to detect dominant inherited disorder. / Besides the genetic analysis at the DNA level, epigenetic markers are also valuable for noninvasive diagnosis development. In the third part of this thesis, I have also developed a bioinformatics algorithm to efficiently analyze genomewide DNA methylation status based on the massively parallel sequencing of bisulfite-converted DNA. DNA methylation is one of the most important mechanisms for regulating gene expression. The study of DNA methylation for different genes is important for the understanding of the different physiological and pathological processes. Currently, the most popular method for analyzing DNA methylation status is through bisulfite sequencing. The principle of this method is based on the fact that unmethylated cytosine residues would be chemically converted to uracil on bisulfite treatment whereas methylated cytosine would remain unchanged. The converted uracil and unconverted cytosine can then be discriminated on sequencing. With the emergence of massively parallel sequencing platforms, it is possible to perform this bisulfite sequencing analysis on a genome-wide scale. However, the bioinformatics analysis of the genome-wide bisulfite sequencing data is much more complicated than analyzing the data from individual loci. Thus, I have developed Methyl-Pipe, a bioinformatics program for analyzing the DNA methylation status of genome-wide methylation status of DNA samples based on massively parallel sequencing. In the first step of this algorithm, an in-silico converted reference genome is produced by converting all the cytosine residues to thymine residues. Then, the sequenced reads of bisulfite-converted DNA sequences are aligned to this modified reference sequence. Finally, post-processing of the alignments removes non-unique and low-quality mappings and characterizes the methylation pattern in genome-wide manner. Making use of this new program, potential fetal-specific hypomethylated regions which can be used as blood biomarkers can be identified in a genome-wide manner. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Jiang, Peiyong. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 100-105). / Abstracts also in Chinese. / Chapter SECTION I : --- BACKGROUND --- p.1 / Chapter CHAPTER 1: --- Circulating nucleic acids and Next-generation sequencing --- p.2 / Chapter 1.1 --- Circulating nucleic acids --- p.2 / Chapter 1.2 --- Next-generation sequencing --- p.3 / Chapter 1.3 --- Bioinformatics analyses --- p.9 / Chapter 1.4 --- Applications of the NGS --- p.11 / Chapter 1.5 --- Aims of this thesis --- p.12 / Chapter SECTION II : --- Mathematically decoding fetal genome in maternal plasma --- p.14 / Chapter CHAPTER 2: --- Characterizing the maternal and fetal genome in plasma at single base resolution --- p.15 / Chapter 2.1 --- Introduction --- p.15 / Chapter 2.2 --- SNP categories and principle --- p.17 / Chapter 2.3 --- Clinical cases and SNP genotyping --- p.20 / Chapter 2.4 --- Sequencing depth and fractional fetal DNA concentration determination --- p.24 / Chapter 2.5 --- Filtering of genotyping errors for maternal genotypes --- p.26 / Chapter 2.6 --- Constructing fetal genetic map in maternal plasma --- p.27 / Chapter 2.7 --- Sequencing error estimation --- p.36 / Chapter 2.8 --- Paternal-inherited alleles --- p.38 / Chapter 2.9 --- Maternally-derived alleles by RHDO analysis --- p.39 / Chapter 2.1 --- Recombination breakpoint simulation and detection --- p.49 / Chapter 2.11 --- Prenatal diagnosis of β- thalassaemia --- p.51 / Chapter 2.12 --- Discussion --- p.53 / Chapter SECTION III : --- Statistical model for fractional fetal DNA concentration estimation --- p.56 / Chapter CHAPTER 3: --- FetalQuant: deducing the fractional fetal DNA concentration from massively parallel sequencing of maternal plasma DNA --- p.57 / Chapter 3.1 --- Introduction --- p.57 / Chapter 3.2 --- Methods --- p.60 / Chapter 3.2.1 --- Maternal-fetal genotype combinations --- p.60 / Chapter 3.2.2 --- Binomial mixture model and likelihood --- p.64 / Chapter 3.2.3 --- Fractional fetal DNA concentration fitting --- p.66 / Chapter 3.3 --- Results --- p.71 / Chapter 3.3.1 --- Datasets --- p.71 / Chapter 3.3.2 --- Evaluation of FetalQuant algorithm --- p.75 / Chapter 3.3.3 --- Simulation --- p.78 / Chapter 3.3.4 --- Sequencing depth and the number of SNPs required by FetalQuant --- p.81 / Chapter 3.5 --- Discussion --- p.85 / Chapter SECTION IV : --- NGS-based data analysis pipeline development --- p.88 / Chapter CHAPTER 4: --- Methyl-Pipe: Methyl-Seq bioinformatics analysis pipeline --- p.89 / Chapter 4.1 --- Introduction --- p.89 / Chapter 4.2 --- Methods --- p.89 / Chapter 4.2.1 --- Overview of Methyl-Pipe --- p.90 / Chapter 4.3 --- Results and discussion --- p.96 / Chapter SECTION V : --- CONCLUDING REMARKS --- p.97 / Chapter CHAPTER 5: --- Conclusion and future perspectives --- p.98 / Chapter 5.1 --- Conclusion --- p.98 / Chapter 5.2 --- Future perspectives --- p.99 / Reference --- p.100
73

The analysis of cDNA sequences: an algorithm for alignment.

January 1997 (has links)
by Lam Fung Ming. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1997. / Includes bibliographical references (leaves 45-47). / Chapter CHAPTER 1 --- INTRODUCTION --- p.1 / Chapter CHAPTER 2 --- BACKGROUND --- p.4 / Section 2.1 DNA Cloning --- p.5 / Section 2.1.1 Principles of cell-based DNA cloning --- p.5 / Section 2.1.2. Polymerase Chain Reaction --- p.8 / Section 2.2 DNA Libraries --- p.10 / Section 2.3. Expressed Sequence Tags --- p.11 / "Section 2.4 dbEST - Database for ""Expressed Sequence Tag""" --- p.13 / Chapter CHAPTER 3 --- REDUCTION OF PARTIAL SEQUENCE REDUNDANCY AND CDNA ALIGNMENT --- p.15 / Section 3.1 Materials --- p.15 / Section 3.2 Our Algorithm --- p.16 / Section 3.3 Data Storage --- p.24 / Section 3.4 Criterion of Alignment --- p.27 / Section 3.5 Pairwise Alignment --- p.29 / Chapter CHAPTER 4 --- RESULTS AND DISCUSSION --- p.32 / Chapter CHAPTER 5 --- CONCLUSION AND FUTURE DEVELOPMENT --- p.42 / REFERENCES --- p.45 / APPENDIX --- p.i
74

Upper Jurassic of the Barrow sub-basin: sedimentology, sequence stratigraphy and implications for reservoir development

Wulff, Keiran January 1991 (has links)
A chronostratigraphic subdivision of the Upper Jurassic synrift sediments in the eastern Barrow Sub-basin was developed from the integration of core logging, petrography, well log sequence analyses and seismic stratigraphy. From this basis, the Callovian to base Cretaceous sediments may be subdivided into five depositional sequences. The development of the sequence boundaries, in most part, is closely related to periods of major changes in basin configuration associated with the sequential breakup of eastern Gondwanaland. Initiation of the Upper Jurassic rift complex occurred during late Callovian early Oxfordian associated with the development of a northeast-southwest trending spreading centre on the Argo Abyssal Plain. The spreading centre propagated southwards during the Late Jurassic. This resulted in active rifting in the Barrow Sub-basin and ultimately led to the separation of the Indian and Australian plates during Valanginian time.Upper Jurassic synrift sediments in the eastern Barrow Sub-basin consist of detached basin floor fan complexes, channelised and canyon fed fan systems, slump deposits, prograding outer shelfal to slope deposits and deep marine claystones. Post-depositional uplift of the eastern shelfal areas during the Late Jurassic resulted in erosion of the transgressive and highstand fluvial-deltaic to shelfal deposits. These periods of uplift and erosion provided much of the sediment redeposited in the basinal areas during the lowstand periods. Seven sandstone facies were recognised in the Upper Jurassic sedimentary section based on core control. Each sandstone has unique reservoir characteristics which can be related to the depositional setting. / The abundance of glauconite and belemnites combined with ichnology and biostratigraphic assemblages associated with marine environments, indicate that deposition of all the sandstone facies occurred within an outer shelfal - deep marine environment. Reservoir quality was best developed in the dominantly medium grained, moderate - well sorted sandstones, (facies 7), which were deposited as detached, basin floor submarine fan sands or interbedded turbidites. In contrast, reservoir quality was relatively poorly developed in the remaining facies which were deposited as slope fans, slumps, or distal turbidite deposits.The abundance of quartz and presence of banded iron, jasper, and potassic feldspar grains support the provenance for the basinal sandstone facies being the Precambrian alkyl granites and banded iron formation of.the Pilbara Shield and Hammersley Ranges. These Precambrian igneous rocks and metasediments mark the eastern boundary of the Barrow Sub-basin study area. To predict the distribution of sedimentary facies in the Upper Jurassic synrift sediments of the eastern Barrow Sub-basin, the interplay between the major controlling depositional processes, namely tectonics, sediment supply and eustasy must be understood. Subdivision of the synrift sedimentary section on the basis of lithostratigraphy can be misleading and does not adequately resolve the facies relationships observed in the well intersection. The results of this research form the basis for a regional sequence analysis and seismic stratigraphic study.
75

The development of an efficient method of mitochondrial DNA analysis

Tan, Angela Y. C. January 2003 (has links)
Abstract not available
76

The Evolution and Mechanics of Translational Control in Plants

Vaughn, Justin N. 01 August 2011 (has links)
The expression of numerous plant mRNAs is attenuated by RNA sequence elements located in the 5' and 3' untranslated regions (UTRs). For example, in plants and many higher eukaryotes, roughly 35% of genes encode mRNAs that contain one or more upstream open reading frames (uORFs) in the 5' UTR. For this dissertation I have analyzed the pattern of conservation of such mRNA sequence elements. In the first set of studies, I have taken a comparative transcriptomics approach to address which RNA sequence elements are conserved between various families of angiosperm plants. Such conservation indicates an element's fundamental importance to plant biology, points to pathways for which it is most vital, and suggests the mechanism by which it acts. Conserved motifs were detected in 3% of genes. These include di-purine repeat motifs, uORF-associated motifs, putative binding sites for PUMILIO-like RNA binding proteins, small RNA targets, and a wide range of other sequence motifs. Due to the scanning process that precedes translation initiation, uORFs are often translated, thereby repressing initiation at the an mRNA's main ORF. As one might predict, I found a clear bias against the AUG start codon within the 5' untranslated region (5' UTR) among all plants examined. Further supporting this finding, comparative analysis indicates that, for ~42% of genes, AUGs and their resultant uORFs reduce carrier fitness. Interestingly, for at least 5% of genes, uORFs are not only tolerated, but enriched. The remaining uORFs appear to be neutral. Because of their tangible impact on plant biology, it is critical to differentiate how uORFs affect translation and how, in many cases, their inhibitory effects are neutralized. In pursuit of this aim, I developed a computational model of the initiation process that uses five parameters to account for uORF presence. In vivo translation efficiency data from uORF-containing reporter constructs were used to estimate the model's parameters in wild type Arabidopsis. In addition, the model was applied to identify salient defects associated with a mutation in the subunit h of eukaryotic initiation factor 3 (eIF3h). The model indicates that eIF3h, by supporting re-initation during uORF elongation, facilitates uORF tolerance.
77

Population Phylogeny of Hemidactylus frenatus in Taiwan as Inferred from Cytochrome b Sequences

Ho, Chia-Hsin 27 May 2002 (has links)
Phylogeny of 25 Hemidactylus frenatus populations from Taiwan and adjecent islands were resloved by mitochondrial cytochrome b nucleotide sequences and morphological characters. A total of 327 bp were sequenced. Using neighbor-joining and maximum parsimony methods, the phylogenetic trees divide Hemidactylus frenatus into 8 regional groups: Tungshia group; Chiaohsi group; northwest group; central group; Chiayi-Tainan group; south-Penghu group; east-Hengchun group; and southeast group. The results suggest that, the dispersal center should be in the northwest, and then dispersed to the east and the south. Phylogenetic state of Chiaohsi population is not clear. It may be immigrated from northwest or outside of Taiwan. The Penghu and Kaohsiung populations have a short genetic distance, maybe caused from frequently genetic interflow, as well as the Chihpen, Tunghe, Lutao and Lanyu populations. The Principle Component Analysis and Canonical Discriminate Analysis of 16 morphological characters, showed that no differences exist populations.
78

Molecular Characterization of Ductal Carcinoma In Situ: Pilot Studies

Desai, Neil Bipinchandra 28 September 2010 (has links)
Ductal carcinoma in situ (DCIS); is thought directly to precede invasive breast cancer (IBC). Screening mammography has driven the incidence of this key precursor lesion to >65,000 cases per year. However, little is known about the factors controlling the natural history or risk for recurrence following treatment of a particular patients DCIS. Though the heterogeneity of the disease is well established, no histologic or demographic criteria have been able to stratify DCIS for treatment. We hypothesize that at initial diagnosis there exist biologically distinct subsets of DCIS with associated prognoses that may be recognized by molecular markers. Molecular approaches have been limited by technical design issues related to the types of tissue available for analysis, namely degraded formalin-fixed paraffin embedded (FFPE) specimens and small core biopsy samples. However, new technologies promise to overcome these issues. In the first phase of our investigation, we aimed a) to pilot feasibility studies on the use of FFPE DCIS for molecular analyses including gene expression microarray and b) to pilot feasibility study of selective, high throughput sequencing through the use of "exon capture" on small input material that simulated expected DCIS core biopsy amounts. The results of this work offer specific technical guidelines for the molecular study of DCIS. Moreover, they have enabled the initiation of the second phase of this study, which aims to assess molecular profiles of DCIS recurrence and progression.
79

A Bayesian model for curve clustering with application to gene expression data analysis /

Zhou, Chuan, January 2003 (has links)
Thesis (Ph. D.)--University of Washington, 2003. / Vita. Includes bibliographical references (leaves 178-195).
80

Molecular epidemiology of HIV-1 transmission : a case study of source partners of individuals with acute retroviral syndrome /

Truong, Hong-Ha Manh. January 2000 (has links)
Thesis (Ph. D.)--University of Washington, 2000. / Vita. Includes bibliographical references (leaves 94-118).

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