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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.
11

Evaluation of the Genetic Differences Between Two Subtypes of Campylobacter fetus (Fetus and Venerealis) in Canada

Mukhtar, Lenah 19 August 2013 (has links)
The pathogen Campylobacter fetus (CF) is classified into two subspecies, Campylobacter fetus subspecies fetus (CFF) and Campylobacter fetus subspecies venerealis (CFV). Even though CFF and CFV are genetically closely related, they exhibit differences in their host adaptation; CFF inhabits the gastrointestinal tract of both humans and several animal species, while classical CFV is specific to the bovine genital tract and is of particular concern with respect to international bovine trade regulation. Traditionally, differentiation between the two subspecies has been achieved using a limited number of biochemical tests but more rapid and definitive genetic methods of discrimination are desired. A recent study suggested that the presence of a genomic island only in CFV could discriminate between the two sub- species but this hypothesis could not be confirmed on a collection of isolates originating in Canada. To identify alternative gene targets that would support accurate subspecies discrimination, this study has applied several approaches including suppression subtractive hybridization and whole genome sequencing supplemented with optical mapping. A subtractive hybridization screen, using a well-characterized CFV isolate recovered during routine screening of bulls in an Artificial Insemination center in western Canada and that lacked much of the genomic island and a typical Canadian CFF isolate, yielded 50 clones; characterization of these clones by hybridization screening against selected CF isolates and by nucleotide sequence BLAST analysis identified three potentially CFV-specific clones that contained inserts originating from a second genomic island. Further screening using a larger CF sample set found that only Clone #35 was truly CFV-specific. Optical maps (NcoI digest) of the Canadian CFF and CFV isolates used for the subtractive hybridization showed that certain regions of these genomes were quite distinct from those of two reference strains. Whole genome sequencing of these two isolates identified two target genes (PICFV5_ORF548 and CFF_Feature #3) that appear to be selectively retained in the two subspecies. Screening of a collection of CF isolates by PCRs targeting these three loci (SSH_Clone #35, PICFV5_ORF548 and CFF_Feature #3) supported their use for subspecies discrimination. This work demonstrates the complex genomic diversity associated with these CF subtypes and the challenge posed by their discrimination using limited genetic loci.
12

Caracterização molecular das linhagens de Zymomonas mobilis da coleção de micro-organismos UFPEDA

ARAÚJO, Livia Caroline Alexandre de 20 February 2014 (has links)
Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2016-06-29T12:07:11Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertação Livia Araujo.pdf: 1983609 bytes, checksum: cbba526737c10f6743b3fd015372721a (MD5) / Made available in DSpace on 2016-06-29T12:07:11Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertação Livia Araujo.pdf: 1983609 bytes, checksum: cbba526737c10f6743b3fd015372721a (MD5) Previous issue date: 2014-02-20 / CAPEs / Zymomonas mobilis vem despertando um grande interesse no meio científico, industrial e biotecnológico devido ao seu alto potencial fermentativo. Do ponto de vista taxonômico, Z. mobilis é a única espécie do gênero Zymomonas, e é subdivida em três subespécies: Z. mobilis subsp. mobilis, Z. mobilis subsp. pomaceae e Z. mobilis subsp. francensis. A diferenciação destas subespécies é baseada em testes fisiológicos. Estes testes consomem tempo e são frequentemente duvidosos. Por isso, técnicas moleculares são propostas como uma alternativa rápida e confiável para diferenciação destas bactérias. O presente estudo teve como objetivo realizar a caracterização molecular das 32 linhagens de Zymomonas mobilis depositadas na Coleção de Microrganismos UFPEDA, através da análise das sequências do gene 16S rDNA e ARDRA. As linhagens foram cultivadas em meio SSDL por 24 horas à 30º, seguida de centrifugação e extração de DNA cromossômico. As reações de PCR foram realizadas com iniciadores e condições específicas para a amplificação do gene 16S rDNA. Os produtos do gene 16S rDNA amplificados foram purificados, sequenciados e clivados com as enzimas de restrição Hae III, NdeII e StuI. Os dados obtidos pelo sequenciamento do gene 16S rDNA foram analisados, comparados e alinhados, pelo programas BLASTn e MultiAlin, com sequências de linhagens de Z. mobilis previamente depositadas no banco de dados GenBank. Um dendograma foi construido através do programa ClustalW pelo método de neighbor-joining Os perfis de restrição teórico das enzimas de restrição Hae III, NdeII e StuI foram gerados a partir do WebCutter 2.0. Dendogramas foram construídos a partir da matriz de similaridade genética de Jaccard, calculada pela análise dos perfis de restrição teóricos de cada enzima. A análise das sequências obtidas no presente estudo revelou o elevado grau de conservação no gene 16SrDNA, confirmando a relação de proximidade das linhagens de Zymomonas mobilis depositadas na Coleção de Micro-organismos UFPEDA e a aproximidade com a Z. mobilis subsp. mobilis LMG445, sugerindo que as linhagens desta coleção pertencem a esta subespécie.Além disso, conclui-se que a análise do perfil restrição teórico do gene 16S rDNA possibilita a diferenciação de Z. mobilis,a nível de subespécie, mas não é eficaz para analisar a variabilidade genética entre as linhagens de Z. mobilis UFPEDA. Baseados nestes resultados, outros marcadores filogenéticos devem ser empregados para analisar a variabilidade genética destas linhagens, possibilitando um melhor conhecimento da diversidade desta bactéria. / Zymomonas mobilis has attracted great interest in the scientific, industrial and biotechnological medium due to its high fermentation potential. The taxonomic viewpoint, Z. mobilis is the only species of the genus Zymomonas , and is subdivided into three subspecies : Z. mobilis subsp. mobilis, Z. mobilis subsp. pomaceae and Z. mobilis subsp. francensis. The differentiation of these subspecies is based on physiological tests. These tests are time consuming and often unreliable. Therefore, molecular techniques are proposed as a fast and reliable alternative to differentiation of these bacteria. This study aims to perform molecular characterization of 32 strains of Zymomonas mobilis deposited in the Collection of Microorganisms UFPEDA by sequence analysis of 16S rDNA gene and the theoretical restriction profile of this gene. The strains were grown in SSDL for 24 hours at 30 ° , followed by centrifugation and extraction of chromosomal DNA . PCR reactions were performed with primers and specific conditions for amplification of the 16S rDNA gene. The amplified products of 16S rDNA were purified, sequenced, and cleaved with restriction enzymes Hae III, NdeII and StuI . The data obtained by 16S rDNA gene were analyzed, compared and aligned by BLASTn and MultiAlin programs with sequences of strains of Z. mobilis previously deposited in the GenBank databas . A dendogram was constructed using the program ClustalW method by neighbor-joining. Profiles theoretical restriction of restriction enzyme Hae III, NdeII and StuI were generated from WebCutter 2.0. Dendrograms were constructed from the genetic Jaccard similarity matrix, calculated by analyzing the theoretical restriction profiles of each enzyme. The analysis of the sequences obtained in this study revealed the high degree of conservation in 16SrDNA gene, confirming the close relationship of strains of Zymomonas mobilis deposited in the Collection of Micro-organisms UFPEDA and closeness with Z. mobilis subsp. mobilis LMG445, suggesting that the strains in this collection belong to this subespécie. In addition, it is concluded that the theoretical restriction profile analysis of the 16S rDNA gene allows differentiation of Z. mobilis , the level of subspecies , but it is not effective to analyze the genetic variability between strains of Z. mobilis UFPEDA . Based on these results , other phylogenetic markers should be employed to analyze the genetic variability of these strains , allowing a better understanding of the diversity of this bacteria.
13

Evaluation of the Genetic Differences Between Two Subtypes of Campylobacter fetus (Fetus and Venerealis) in Canada

Mukhtar, Lenah January 2013 (has links)
The pathogen Campylobacter fetus (CF) is classified into two subspecies, Campylobacter fetus subspecies fetus (CFF) and Campylobacter fetus subspecies venerealis (CFV). Even though CFF and CFV are genetically closely related, they exhibit differences in their host adaptation; CFF inhabits the gastrointestinal tract of both humans and several animal species, while classical CFV is specific to the bovine genital tract and is of particular concern with respect to international bovine trade regulation. Traditionally, differentiation between the two subspecies has been achieved using a limited number of biochemical tests but more rapid and definitive genetic methods of discrimination are desired. A recent study suggested that the presence of a genomic island only in CFV could discriminate between the two sub- species but this hypothesis could not be confirmed on a collection of isolates originating in Canada. To identify alternative gene targets that would support accurate subspecies discrimination, this study has applied several approaches including suppression subtractive hybridization and whole genome sequencing supplemented with optical mapping. A subtractive hybridization screen, using a well-characterized CFV isolate recovered during routine screening of bulls in an Artificial Insemination center in western Canada and that lacked much of the genomic island and a typical Canadian CFF isolate, yielded 50 clones; characterization of these clones by hybridization screening against selected CF isolates and by nucleotide sequence BLAST analysis identified three potentially CFV-specific clones that contained inserts originating from a second genomic island. Further screening using a larger CF sample set found that only Clone #35 was truly CFV-specific. Optical maps (NcoI digest) of the Canadian CFF and CFV isolates used for the subtractive hybridization showed that certain regions of these genomes were quite distinct from those of two reference strains. Whole genome sequencing of these two isolates identified two target genes (PICFV5_ORF548 and CFF_Feature #3) that appear to be selectively retained in the two subspecies. Screening of a collection of CF isolates by PCRs targeting these three loci (SSH_Clone #35, PICFV5_ORF548 and CFF_Feature #3) supported their use for subspecies discrimination. This work demonstrates the complex genomic diversity associated with these CF subtypes and the challenge posed by their discrimination using limited genetic loci.
14

Förekomsten av mikrosporidien Nosema sp. hos honungsbin (Apis mellifera) i Sverige; : en jämförelse mellan fyra honungsbiraser under höst- och vintersäsong

Sondell, Jennifer January 2021 (has links)
Honey bees are fundamental for maintaining biodiversity in our ecosystems, but a recent decline in honey bee colonies has caused a growing concern for honey bee health worldwide. One component of colony collapses is Nosema (Microsporidia), which is associated with colony collapses in many subtropical regions. However, infection by Nosema is also known to accumulate within the honey bee hive during overwintering in colder climates. In this study, the prevalence of Nosema is compared between four honey bee subspecies during fall and winter and is focused on two hypotheses: 1) infection by Nosema is more prevalent in honey bees during winter and 2) infection by Nosema differs between different honey bee subspecies. Bees were dissected, and their guts were analysed for Nosema spores using a light microscope. Results showed a difference in amount of Nosema infected colonies between winter and fall. Also, results showed a difference between Buckfast bee (A. mellifera hybrid) and Carniolan bee (A. mellifera carnica) in Nosema infected colonies during the fall period. These results indicate that infection by Nosema in cold climates might be more prevalent than previously thought. Additionally, there might be differences in resilience between honey bee subspecies, but infection of Nosema seem to depend less on subspecies than season. More research is needed on Nosema in cold regions to assess the effect of Nosema on honey bees in Sweden and worldwide to prevent future colony collapses of honey bees.
15

Cryptic song? Taxonomy of the warbler Plain Prinia based on song analysis

Magnusson, Jesper January 2022 (has links)
The warbler Prinia inornata (Plain Prinia) is a common songbird found across large parts of southern Asia, and it is currently divided into ten geographically distinct subspecies. It has been suggested by some ornithologists to possibly be a complex of cryptic species, i.e. several species so similar to each other that they have been taxonomically misclassified as being conspecific. This study used audio recordings to compare songs between individuals from different regions in order to see if there are distinct geographical differences, and if so, how these correspond to the current taxonomy. The comparison was made using two methods: A qualitative auditory analysis, and statistical models (NMDS and PCA) based on measurements from spectrograms.  The results show that two main types of song exist that are highly distinct from each other, each taking up roughly half of the geographical range. The two main types can be further divided into a few subtypes, potentially as many as seven in total. The geographical distribution of these subtypes matches that of some of the current subspecies, but the results do not support the current taxonomy as a whole. It is therefore likely that P. inornata comprises at least two species (corresponding to the two main types), possibly more.
16

Peregrine Falcon (Falco peregrinus) Subspecies Phylogenomics Using Whole Genome Re-Sequencing

Meeks, Garrett W. 12 1900 (has links)
Peregrine falcon subspecies taxonomy is widely debated due to uncertainty in their evolutionary history and unresolved phylogenetic reconstruction using both morphological and molecular data. Previous genetic work has shown limited support for subspecies taxonomy largely as a result of molecular markers used, potential contemporary gene flow, incomplete lineage sorting, and ancestral polymorphisms. With the advent of next-generation sequencing, the cost of generating large amounts of sequence data has dropped significantly, making whole genome re-sequencing (WGR) studies of non-model organisms more tangible. In this study, WGR methods have been utilized to investigate the phylogenetic relationships among all 20 currently recognized peregrine falcon subspecies. By generating whole-genome data for all 20 subspecies, subspecies specific diagnostic SNPs have been identified to aid in subspecies delimitation. Results of this study broadly support current subspecies, however, reveal that further study is needed to investigate regional relationships among subspecies in Asia, Australia, and western North America. With these results, conservation efforts can be further supported by allowing for accurate delimitation of local subspecies and subspecies boundaries.
17

Biogeography And Systematics Of The Nerodia Clarkii/nerodia Fasciata Clade In Florida

Territo, Gregory 01 January 2013 (has links)
Biogeography provides a window into the evolutionary history of populations, and helps explain the diversity and distribution of life through time. Viewed from a systematic perspective, biogeographic studies generate convincing arguments to explain the relationships among organisms and categorize them into useful taxonomies. When taxonomies do not reflect evolutionary histories, inaccurate representations of biodiversity confound future studies and conservation efforts. Two thamnophiine snakes, Nerodia clarkii and Nerodia fasciata, harbor unique morphological and ecological adaptations that obscured natural groupings, leading to controversial taxonomic delimitations. Additionally, population declines documented in N. clarkii compressicauda and N. clarkii taeniata led managers to list N. clarkii taeniata as threatened in 1977. I generated a baseline for continued biogeographic and systematic study of the Nerodia clarkii/fasciata clade. I used mitochondrial DNA to build a parsimony-based haplotype network, infer the phylogenetic relationships between the two species and their thamnophiine relatives, and estimate the divergence times of major N. clarkii/fasciata clades. With these data, I tested biogeographic and systematic hypotheses about the origin and distribution of diversity in this clade. I used principal components analyses to summarize morphological data and discuss ecological observations in search of characters that may unite genetic or taxonomic units. The analyses revealed a peninsular and a panhandle clade in Florida that appeared to iv diverge as a result of Pleistocene glacial fluctuations. I found no support genetically, morphologically, or ecologically for the current taxonomy, indicating a need for range-wide research to generate revised nomenclature. My results do not support the protection status of N. clarkii taeniata
18

Mycobacterium avium subsp. paratuberculosis Virulence: A Review

Ssekitoleko, Judah, Ojok, Lonzy, Wahed, Ahmed Abd El, Erume, Joseph, Amanzada, Ahmad, Eltayeb, ElSagad, Eltom, Kamal H., Okuni, Julius Boniface 05 May 2023 (has links)
To propose a solution for control of Mycobacterium avium subsp. paratuberculosis (MAP) infections in animals as well as in humans, and develop effective prevention, diagnostic and treatment strategies, it is essential to understand the molecular mechanisms of MAP pathogenesis. In the present review, we discuss the mechanisms utilised by MAP to overcome the host defense system to achieve the virulence status. Putative MAP virulence genes are mentioned and their probable roles in view of other mycobacteria are discussed. This review provides information on MAP strain diversity, putative MAP virulence factors and highlights the knowledge gaps regarding MAP virulence mechanisms that may be important in control and prevention of paratuberculosis.
19

The isolation and characterization of phages with lytic activity against Mycobacterium avium subspecies paratuberculosis, and their application using Bioluminescent Assay in Real-Time Loop-mediated isothermal amplification assay for rapid detection

Basra, Simone 10 January 2013 (has links)
The goal of this project was to incorporate bacteriophage with Bioluminescent Assay in Real-Time Loop-mediated isothermal amplification (BART-LAMP) for the rapid detection of Mycobacterium avium subspecies paratuberculosis (MAP). As the causative agent of Johne’s Disease, there are no rapid detection methods that are suitable in specificity and sensitivity. A screening assay for phage isolation was developed, and over 400 samples were screened for the isolation of a bacteriophage against MAP. One novel Mycobacterium phage was isolated and characterized using transmission electron miscroscopy, host range studies, restriction enzyme digestion, and pH and temperature stability. It was sequenced, annotated, and underwent an in silico protein analysis. No pathogenic or lysogenic genes were detected, and it was found to be related to Gordonia phage GTE2. BART-LAMP was applied to the detection of the isolated phage using purely extracted DNA and crude phage lysate, showing that phages could be detected successfully. / Beef Cattle Research Council; Agriculture and AgriFood Canada through Growing Forward initiative
20

COI Barcoding of the Shorebirds: Rates of Evolution and the Identification of Species

Elbourne, Rebecca 07 December 2011 (has links)
This study assembles COI barcodes from 1814 specimens from the shorebird order, Charadriiformes and examines variation relative to time, rate of evolution and taxonomic level. In the suborder Scolopaci, 95% of sampled species were identified correctly. COI barcode variation within monotypic species was low (0-1% maximum distance) but showed a wide range within polytypic species (0-5%). Preliminary Charadrii results suggest similar trends but success is reduced in the third suborder, Lari. Rates of COI evolution are found to be lowest in the Lari and this leads to reduced species identification in recently radiated families: just 49% of the Laridae and 57% of the Stercoraridae are identified but 100% of the older Alcidae. In the faster Scolopaci, subspecies are at the limit of resolution with some well differentiated subspecies not distinguished by barcodes. The interplay of evolutionary rates, divergence dates and gene flow appears to determine COI barcode differentiation between taxa.

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