• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 54
  • 35
  • 19
  • 9
  • 3
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 138
  • 138
  • 34
  • 33
  • 28
  • 17
  • 17
  • 16
  • 14
  • 14
  • 14
  • 12
  • 12
  • 12
  • 12
  • 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.
91

Mitochondrial DNA analysis of Nonosabasut, a Beothuk Indian chief

Reed, April May January 2001 (has links)
The purpose of this experiment was to examine changes in strength and power measures accompanying traditional and ballistic training during in-season competition. Fourteen collegiate women volleyball players were trained for 11 weeks with periodized traditional and ballistic resistance training. There was a 5% decrease (p<0.05) in approach jump and reach height during the traditional training period (pre to mid), and a 5% increase (p<0.05) during the ballistic training period (mid to post), but values were not different from pre to post. There were significant decreases (p<0.05) in contact time during drop jumps (15% mid to post) and minimum dip height in countermovement jumps (7% mid to post and 16% pre to post) during ballistic training. Traditional resistance training displayed significant decreases in speed related measures, while ballistic training displayed significant increases in these same variables. A combination of traditional and ballistic training can maintain jump height over the competitive season. / Department of Biology
92

An assessment of the impact of environmental factors on the quality of post-mortem DNA profiling.

Gunawardane, Dalugama Mudiyanselage Don Dimuth Nilanga January 2009 (has links)
DNA profiling has ignited public interest and consequently their expectations for the capabilities of forensic criminal and science investigations. The prospect of characterising the genetic makeup of individuals or trace samples from a wide variety of depositional and post-mortem circumstances raises the question of how reliable the methods are given the potential for prolonged exposure to variation in environmental factors, i.e. temperature, pH, UV irradiation and humidity, that are known to induce damage to DNA. Thus, it is crucial to verify the validity of the DNA profiling for characterising the genetic makeup of post-mortem tissues. This project aimed to assess the reliability of sequence and microsatellite based genotyping of tissues (muscle, hair and bone) sampled from carcasses over a two year post-mortem period. This assessment investigated the impact of environment induced DNA degradation in the local geographic region that is typical of the circumstances that confront forensic practitioners in southern Australia and to utilise rigorous controls by studying animals whose time of death and burial was known and for which we had pre-decay tissue samples available. A ‘body farm’ with 12 pig carcasses on the northern Adelaide plains, ~60km north of Adelaide, which has a typical southern Australian Mediterranean climate, i.e. cold wet winters and hot dry summers. Pigs (Sus scrofa) were used as an experimental analogue for human subjects because of the logistical and ethical reasons. The pig carcasses were allocated among three treatments: four were left on the surface, four were buried at 1m depth, and four were buried at 2 m depth. These ‘burial’ conditions mimic a range of conditions encountered typically in forensic and archaeological studies. Cortical bone samples were taken from each pig carcass at one week, one month, three months, six months, one year and two years post-mortem and muscle and hair over the same sampling period for as long as those tissue types were present. A set of PCR primers to amplify two (short and a long) fragments from the hypervariable part of the mitochondrial control region (HVRI) that is used in forensic and evolutionary studies of humans and many other mammal species were developed. Also a panel of four pig microsatellite loci with fluorescent labels to facilitate automated multiplex genotyping. These loci matched as closely as possible the core motifs and allele lengths typical of the commercially available microsatellite marker kits used in Australian forensic science labs so that our experiments were as good a model as possible of the human forensic DNA technology. In this study it was possible to retrieve samples from muscle tissue up to 90 days, hair up to one year and bone at two years post-mortem. The analyses showed that the long and short HVRI region PCR fragments were only amplifiable up to 30 days from muscle tissue and that these fragments were amplifiable up to one year from hair. In contrast, in cortical bone both PCR fragments were amplifiable up to two years. The long fragment disappeared in muscle tissue completely after 30 days and in hair after six months. However, the long fragment was present in cortical bone even at two years. Overall, there was a general trend of loss of concentration of both the long and short fragments over time. Comparisons of the HVRI nucleotide sequences among tissues sampled from individual animals showed substitution changes in muscles as early as 30 days (3 out of 6 individuals) and hair at six months (1 out of 6 individuals). In contrast, in cortical bone substitutions first appeared at 365 days (1 out of 6 individuals). The most common substitution observed in all tissues types was the C-T transition, with A-G transversions observed in two episodes and C-A transversion observed in one episode. Analyses of microsatellite genotypes in muscle tissues showed high allele peaks on chromatograms up to day seven samples. However, by three months PCR was not successful from muscle tissue. While, bone tissue had lower allele peak heights compared to the muscle tissues, alleles were detectable up to six months. Allele drop out occurred for one animal (at 2 meters) in muscle tissue at the dinucleotide locus and for another animal (kept on surface) also in muscle tissue at a tetranucleotide locus. Stuttering was observed for a single animal at dinucleotide locus in muscle tissue (buried sample 2 meter depth). No stuttering or allele drop outs were seen in the bone tissue. Overall the four loci completely disappeared after 30 days in muscle tissue and after 180 days in bone tissue. In summary, analyses showed that post-mortem DNA degradation was present in all the three tissue types (muscle, hair and bone). The types of damage identified were DNA fragmentation, nucleotide substitutions and DNA loss, which resulted in a diminished frequency of successful PCR for mitochondrial and nuclear markers over time and stuttering and allele drop out in microsatellite genotyping. In addition, two nucleotide substitutions were concentrated in ‘hotspots’ that correlate with sites of elevated mutation rate in vivo. Also the frequency of successful PCR of longer nuclear and mitochondrial PCR products declined markedly more quickly than for shorter products. These changes were first observed at much shorter post mortem intervals in muscle and much longer post mortem intervals in hair and bone tissue. When considering the carcass deposition treatments, tissues that were retrieved from buried carcases showed higher levels of DNA degradation compared to tissues retrieved from carcases left on the surface. Overall, muscle tissue is a good source for DNA analysis in immediate post mortem samples, whereas hair and bone tissue are good source for DNA analysis from older samples. When comparing the microsatellite genotyping and mtDNA analyses, mtDNA is a reliable source for DNA analysis from tissue recovered from bodies that had decayed for longer post-mortem durations such as months to years, whereas microsatellite genotyping gives reliable results for tissue from shorter post mortem intervals (hours to few days). Therefore it is recommended that when analysing mtDNA sequences, cloning and sequencing PCR products can help to identify the base pair substitutions especially for tissue retrieved from longer post mortem intervals. In addition, increasing the template DNA concentrations and "neutralising" co-extracted DNA inhibitors should be considered when dealing with tissue from longer post mortem intervals. Finally, the more stringent protocols used in ancient DNA studies should be considered when dealing with tissue with much longer post mortem intervals in forensic settings. / Thesis (Ph.D.) -- University of Adelaide, School of Medical Sciences, 2009
93

Uma abordagem para detecção e remoção de artefatos em sequencias ESTs / An approach to detect and remove artifacts in EST sequences

Baudet, Christian 12 January 2006 (has links)
Orientador: Zanoni Dias / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Computação / Made available in DSpace on 2018-08-08T07:27:54Z (GMT). No. of bitstreams: 1 Baudet_Christian_M.pdf: 13612079 bytes, checksum: 648d18039dc13dcd5a2f422cc7863666 (MD5) Previous issue date: 2006 / Resumo: O sequenciamento de ESTs (Expressed Sequence Tag) [2] e uma tecnica que trabalha com bibliotecas de cDNAs tendo como objetivo a obtençao de uma boa aproximaçao para o ?ndice genico, que e a listagem de genes existentes no genoma do organismo estudado. Antes da serem analisadas, as sequencias obtidas do sequenciamento dos ESTs devem ser processadas para eliminaçao de artefatos. Artefatos sao trechos que nao pertencem ao organismo ou que possuem baixa qualidade ou baixa complexidade. Trechos de vetores, adaptadores e caudas poli-A podem ser citados como exemplos de artefatos. A eliminaçao dos artefatos deve ser feita para que a an'alise das sequencias produzidas no projeto nao seja prejudicada por estes ?ru?dos?. Por exemplo, artefatos presentes em sequencias freq¨uentemente produzem erros em processos de clusterizaçao, pois eles podem determinar se sequencias serao unidas em um mesmo cluster ou separadas em clusters diferentes. Observando a importancia da realizaçao de um bom processo de limpeza das sequencias, o trabalho desenvolvido nesta dissertaçao teve como principal objetivo a obtençao de um conjunto eficiente de procedimentos de detecçao e remoçao de artefatos. Este conjunto foi produzido a partir de uma nova estrategia de deteçao de artefatos. Normalmente, cada projeto de seq¨uenciamento possui seu proprio conjunto de procedimentos dividido em varias etapas. Estas etapas sao, em geral, ligadas entre si e o resultado de uma pode influenciar o resultado de outra. A nossa estrategia visa a realizaçao destas etapas de forma totalmente independente. Alem da avaliaçao desta nova estrategia, o trabalho tambem realizou um estudo mais detalhado sobre dois tipos de artefatos: baixa qualidade e derrapagem. Para cada um deles, algoritmos foram propostos e validados atraves de testes com conjuntos de seq¨u?encias produzidas em projetos reais de sequenciamento. O conjunto final de procedimentos, baseado nos estudos desenvolvidos durante a escrita deste texto, foi testado com as sequencias do projeto SUCEST [100, 103, 113] e mostrou bons resultados. O clustering produzido com as sequencias processadas por nossos metodos apresentou melhores consistencia interna e externa e menores taxas de redundancia quando comparado ao clustering original do projeto / Abstract: Expressed Sequence Tag (EST) Sequencing [2] is one technique that works with cDNA libraries. It aims to achieve a good approximation for the gene index of an organism. Before analyzing the sequences obtained by sequencing ESTs, they must be processed for artifact removal. An artifact is a sequence that does not belong to the studied organism or that has low quality or low complexity. As example of artifacts, we have adapters, poly- A tails, vectors, etc. Artifacts removal must be performed because their presence can produce ?noises? in the sequencing project data analysis. For example, artifact can join two sequences in a same cluster inappropriately or separate them in two different clusters when they should be put together. Motivated by the sequence cleaning process importance, our main objective in this work was to develop an efficient set of procedures to detect and to remove sequence artifacts. Usually, each EST sequencing project has its own procedure set divided in many steps. These steps are, in general, linked and the result of one given step might influence the result of the next one. Our strategy was to perform each step independently assuring that any execution order of those steps would lead to the same result. Additionally to the new strategy evaluation, this work also studied detailedly two type of artifacts: low quality and slippage. For each one, algorithms were proposed and validated through tests with sequences of real sequencing projects. The final set of procedure, developed in this work, was evaluated using the sequences of the SUCEST project [100, 103, 113] and produced good results. The resulting clustering from our method has better external and internal consistency and lower redundacy rate than those produced by the SUCEST project clustering / Mestrado / Ciência da Computação / Mestre em Ciência da Computação
94

Smart Sequence Similarity Search (S⁴) system

Chen, Zhuo 01 January 2004 (has links)
Sequence similarity searching is commonly used to help clarify the biochemical and physiological features of newly discovered genes or proteins. An efficient similarity search relies on the choice of tools and their associated subprograms and numerous parameter settings. To assist researchers in selecting optimal programs and parameter settings for efficient sequence similarity searches, the web-based expert system, Smart Sequence Similarity Search (S4) was developed.
95

Elektrochemický biosenzor pro studium metylace DNA / Electrochemical biosensor for the study of DNA methylation

Petrula, Jakub January 2017 (has links)
This bachelor’s thesis deals with design and optimalisation of custom biosensor for detection of methylated DNA. Teoretical part explains the mechanism and importance of DNA methylation. Next section describes analytical methods used in connection with DNA methylation and some basic direct and indirect methods of detection. Final part is dedicated to experiment itself, which is divided into several sections. Section one deals witch modification of working electrode and optimalisation of detection method. Second section introduces two different ways of DNA methylation detection. First is based on direct detection and second one on detection through the biosensor. Final part shows determination of methylcytosine from sample based on analysing characteristic attributes of signal and numeric algorithm based on curve fitting.
96

Taxonomická revize rodu Anisus v České republice (Mollusca: Planorbidae) / Taxonomic revision of the genera Anisus in the Czech Republic (Mollusca: Planorbidae)

Zavoral, Tomáš January 2010 (has links)
The aim of this work is to critically review the anatomical and morphological characters being currently used in the determination of Central European species of the genus Anisus and to confront them with molecular characters. For the molecular analysis mitochondrial genes for 16S rRNA and cytochrome c oxidase - subunit I (COI) were used. DNA analysis showed that known species occuring in the Czech Republic form well distinguishable genetic lines. Subsequent revisions of the anatomical characters of these lines have proven that these characters are due to their variability not suitable for determination, especially for the differentiating of the species A. spirorbis and A. leucostoma. The conchological characters have proven more suitable, especially the ratio of the size of the last and penultimate whorl. With the help of this character, we can safely determine a population within which there are transitional forms in other morphological and anatomical characters.
97

The Synthetic spider silk fibers spun from Pyriform Spidroin 2, a glue silk protein discovered in orb-weaving spider attachment discs

Geurts, Paul 01 January 2010 (has links)
Spider attachrnentdisc silk fibers are spun into a viscous liquid that rapidly solidifies, gluing dragline silk fibers to substrates for locomotion or web construction. Here we report the identification and artificial spinning of a novel attachment disc glue silk fibroin, Pyriform Spidroin 2 (PySp2), from the golden orb weaver Nephila c/avipes. MS studies support PySp2 is a constituent of the pyriform gland that is spun into attachment discs. Analysis of the PySp2 protein architecture reveals sequence divergence relative to the other silk family members, including the cob weaver glue silk fibroin PySpl. PySp2 contains internal block repeats that consist of two sub-repeat units: one dominated by Ser, Gin and Ala, the other Pro-rich. Artificial spinning of recombinant PySp2 truncations shows that the Ser-Gln-Ala-rich sub-repeat is sufficient for the assembly of polymeric subunits and subsequent fiber formation. These studies support that both orb- and cob-weaving spiders have evolved highly polar block-repeat sequence with the ability to self-assemble into fibers, suggesting a strategy to allow fiber fabrication in the liquid environment of the attachment discs.
98

The conserved C-terminal domain of spider tubuliform spidroin 1 contributes to extensibility in synthetic fibers

Gnesa, Eric Henry 01 January 2011 (has links)
Spider silk is renowned for its extraordinary mechanical properties, having a balance of high tensile strength and extensibility. To date, the majority of studies have focused on the production of dragline silks from synthetic spider silk gene products. Here we report the first mechanical analysis of synthetic egg case silk fibers spun from the Latrodectus hesperus tubuliform silk proteins, TuSp1 and ECP-2. We provide evidence that recombinant ECP-2 proteins can be spun into fibers that display mechanical properties similar to other synthetic spider silks. We also demonstrate that silks spun from recombinant thioredoxin-TuSp 1 fusion proteins that contain the conserved C-terminal domain exhibit increased extensibility and toughness when compared to the identical fibers spun from fusion proteins lacking the C-terminus. Mechanical analyses reveal that the properties of synthetic tubuliform silks can be modulated by altering the post-spin draw ratios of the fibers . Fibers subject to increased draw ratios showed elevated tensile strength and decreased extensibility, but maintained constant toughness. Wide-angle X-ray diffraction studies indicate that post-drawn fibers containing the Cterminal domain of TuSp 1 have more amorphous content when compared to fibers lacking the C-terminus. Taken together, these studies demonstrate that recombinant tubuliform spidroins that contain the conserved C-terminal domain with embedded protein tags can be effectively spun into fibers, resulting in similar tensile strength but increased extensibility relative to non-tagged recombinant dragline silk proteins spun from equivalently sized proteins.
99

Developing Genotypic and Phenotypic Systems for Early Analysis of Drug-Resistant Bacteria

Akuoko, Yesman 11 May 2023 (has links) (PDF)
Antimicrobial resistance in bacteria is a global health challenge with a projected fallout of 10 million deaths annually and cumulative costs of over 1 trillion dollars by 2050. The currently available tools exploited in the detection of bacteria or their DNA can be expensive, time inefficient, or lack multiplex capabilities among others. The research work highlighted in this dissertation advances techniques employed in the phenotypic or genotypic detection of bacteria and their DNA. In this dissertation, I present polymethyl methacrylate-pressure sensitive adhesive microfluidic platforms developed using a time-efficient, inexpensive fabrication technique. Microfluidic devices were then equipped with functionalized monoliths and utilized for sequence-specific capture and detection of picomolar concentrations of bacterial plasmid DNA harvested from cultured bacteria. I then showed multiplex detection of multiple bacteria gene targets in these devices with an improved monolith column. Finally, I demonstrated a genotypic approach to studying single bacteria growth in water-in-oil droplets with nanomolar concentrations of a fluorescence reporter, and detection via laser-induced fluorescence after convenient room temperature 2-h incubation conditions. The systems and methods described herein show potential to advance tools needed to address the surging problems and effects of drug-resistant bacteria.
100

Generalized pattern matching applied to genetic analysis. / 通用性模式匹配在基因序列分析中的應用 / CUHK electronic theses & dissertations collection / Digital dissertation consortium / Tong yong xing mo shi pi pei zai ji yin xu lie fen xi zhong de ying yong

January 2011 (has links)
Approximate pattern matching problem is, given a reference sequence T, a pattern (query) Q, and a maximum allowed error e, to find all the substrings in the reference, such that the edit distance between the substrings and the pattern is smaller than or equal to the maximum allowed error. Though it is a well-studied problem in Computer Science, it gains a resurrection in Bioinformatics in recent years, largely due to the emergence of the next-generation high-throughput sequencing technologies. This thesis contributes in a novel generalized pattern matching framework, and applies it to solve pattern matching problems in general and alternative splicing detection (AS) in particular. AS is to map a large amount of next-generation sequencing short reads data to a reference human genome, which is the first and an important step in analyzing the sequenced data for further Biological analysis. The four parts of my research are as follows. / In the first part of my research work, we propose a novel deterministic pattern matching algorithm which applies Agrep, a well-known bit-parallel matching algorithm, to a truncated suffix array. Due to the linear cost of Agrep, the cost of our approach is linear to the number of characters processed in the truncated suffix array. We analyze the matching cost theoretically, and .obtain empirical costs from experiments. We carry out experiments using both synthetic and real DNA sequence data (queries) and search them in Chromosome-X of a reference human genome. The experimental results show that our approach achieves a speed-up of several magnitudes over standard Agrep algorithm. / In the fourth part, we focus on the seeding strategies for alternative splicing detection. We review the history of seeding-and-extending (SAE), and assess both theoretically and empirically the seeding strategies adopted in existing splicing detection tools, including Bowtie's heuristic and ABMapper's exact seedings, against the novel complementary quad-seeding strategy we proposed and the corresponding novel splice detection tool called CS4splice, which can handle inexact seeding (with errors) and all 3 types of errors including mismatch (substitution), insertion, and deletion. We carry out experiments using short reads (queries) of length 105bp comprised of several data sets consisting of various levels of errors, and align them back to a reference human genome (hg18). On average, CS4splice can align 88. 44% (recall rate) of 427,786 short reads perfectly back to the reference; while the other existing tools achieve much smaller recall rates: SpliceMap 48.72%, MapSplice 58.41%, and ABMapper 51.39%. The accuracies of CS4splice are also the highest or very close to the highest in all the experiments carried out. But due to the complementary quad-seeding that CS4splice use, it takes more computational resources, about twice (or more) of the other alternative splicing detection tools, which we think is practicable and worthy. / In the second part, we define a novel generalized pattern (query) and a framework of generalized pattern matching, for which we propose a heuristic matching algorithm. Simply speaking, a generalized pattern is Q 1G1Q2 ... Qc--1Gc--1 Qc, which consists of several substrings Q i and gaps Gi occurring in-between two substrings. The prototypes of the generalized pattern come from several real Biological problems that can all be modeled as generalized pattern matching problems. Based on a well-known seeding-and-extending heuristic, we propose a dual-seeding strategy, with which we solve the matching problem effectively and efficiently. We also develop a specialized matching tool called Gpattern-match. We carry out experiments using 10,000 generalized patterns and search them in a reference human genome (hg18). Over 98.74% of them can be recovered from the reference. It takes 1--2 seconds on average to recover a pattern, and memory peak goes to a little bit more than 1G. / In the third part, a natural extension of the second part, we model a real biological problem, alternative splicing detection, into a generalized pattern matching problem, and solve it using a proposed bi-directional seeding-and-extending algorithm. Different from all the other tools which depend on third-party tools, our mapping tool, ABMapper, is not only stand-alone but performs unbiased alignments. We carry out experiments using 427,786 real next-generation sequencing short reads data (queries) and align them back to a reference human genome (hg18). ABMapper achieves 98.92% accuracy and 98.17% recall rate, and is much better than the other state-of-the-art tools: SpliceMap achieves 94.28% accuracy and 78.13% recall rate;while TopHat 88.99% accuracy and 76.33% recall rate. When the seed length is set to 12 in ABMapper, the whole searching and alignment process takes about 20 minutes, and memory peak goes to a little bit more than 2G. / Ni, Bing. / Adviser: Kwong-Sak Leung. / Source: Dissertation Abstracts International, Volume: 73-06, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical referencesTexture mapping (leaves 151-161). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

Page generated in 0.0492 seconds