Please read the abstract in the section 00front of this document / Dissertation (MSc (Medical Virology))--University of Pretoria, 2005. / Medical Virology / unrestricted

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Flavobacterium columnare, a Gram-negative rod-shaped bacterium, is the causative agent of columnaris disease in a variety of fish hosts but is of particular significance to the catfish industry located in the southeastern United States. Columnaris infections are a leading cause of mortalities in catfish ponds, occurring alone or in conjunction with other diseases. Typical diagnostic methods for columnaris infections involve the use of selective media following the observation of gross signs of disease. A real-time quantitative PCR (qPCR) assay to estimate the quantity of bacteria present in environmental and tissue samples was developed and validated. The genetic variability seen in F. columnare makes detection of isolates from different genomovars (genetic groups) essential to an assay for diagnostic application. Isolates from catfish generally fall into one of two different genomovars, one being virulent to catfish, while the other genomovar is thought to be largely opportunistic. The qPCR assay described herein was designed specifically to detect F. columnare isolates from the two major genomovars most often associated with farm-raised catfish. The assay was shown specific to F. columnare, regardless of genomovar, and demonstrated sensitivity consistent with similar qPCR assays. In addition, the assay provides quantitative information, estimating the bacterial loads in fish tissue and the environment. Two different applications of the assay are presented: (1) Estimate bacterial burden in fish tissue following immersion challenges to identify variation in transmission rates between channel and blue x channel hybrid catfish, and (2) Estimate the environmental burden of F. columnare in catfish ponds over the course of a single calendar year. This assay will provide an invaluable tool for researchers and diagnosticians in expanding our understanding of F. columnare and how it interacts with the host and environment.

Background Lower respiratory tract infection (LRTI) is a major cause of morbidity and mortality in children under 5 years of age. Bacterial pathogens contribute significantly to this process. Culture of respiratory tract specimens is labour-intensive and slow. Polymerase chain reaction (PCR) is comparatively, a rapid, sensitive method of detecting low levels of nucleic acid for clinically relevant bacteria. This study compares the yield of bacteria obtained from culture and the FTDResp33 multiplex PCR of nasopharyngeal swabs (NPs) during LRTI episodes in children, in the Drakenstein Child Health Study. Methods At each episode of LRTI, 2 NPs were obtained, one for culture and one for PCR testing. Bacterial yields and concordance for the 5 commonest bacteria were compared using frequencies and proportions. Results From 13th August 2012 to 23rd November 2020, there were 859 episodes of LRTI in 434 children [median age 9.2 (IQR 3.8; 18.9) months; 0.2% HIV-infected]. S. pneumoniae, S. aureus, M. catarrhalis, H. influenzae and K. pneumoniae were the predominant bacteria detected by either method. Concordance between culture and PCR for S. pneumoniae, S. aureus, and K. pneumoniae was 84.9%, 89.7% and 86.3% respectively. Culture and PCR for H. influenzae had a concordance of 76.9%. The greatest discordance between culture and PCR was for the detection of M. catarrhalis (34.4%). Median bacterial loads on PCR for all 5 organisms were significantly associated with semi-quantitative culture results (p<0.001 for each). Adjusting for age and hospitalization, children on antibiotics at the time of sampling, had a reduced chance of having a positive culture (OR 0.1; 95% CI 0.1-0.4), and a reduction in PCR yield (OR 0.8; 95% CI 0.4-1.6). Conclusion: Significant concordance existed between PCR and culture for 4 of the 5 common bacteria, affirming PCR as a comparable method of testing to culture.

This study focused on isolating important wood decay fungi from two field sites located in Harrison County, MS, and Oktibbeha County, MS. Southern Yellow Pine samples of various types and treatments including: Cu8, CuOm, ACQ, PCP, proprietary organic biocide, and un-treated were collected, and fungal isolates were cultured. DNA was extracted from isolated fungal cultures and amplified by polymerase chain reaction (PCR). The internal transcribe spacer (ITS) region was sequenced, and fungal cultures were identified by comparison to sequences on GenBank using BLAST. A total of 68 fungal isolates were recovered and successfully identified from 196 samples. Thirteen basidiomycete isolates were identified, with Veluticeps fimbriata occurring most frequently. The white-rot ascomycete, Daldinia fissa was also common. Two sequence-specific oligonucleotide probes (SSOP) were designed using Lasergene® PrimerSelect software. Unsuccessful attempts were made to attach poly (dT) tails to the probes in order to cross link the probes to nylon membranes.

by Kwok Fung, Lo. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1997. / Includes bibliographical references (leaves 89-97). / Acknowledgement --- p.i / Table of Content --- p.ii / Abstract --- p.vi / List of Abbreviation --- p.viii / List of Tables and figures --- p.ix / Chapter Chapter 1. --- Introduction --- p.1 / Chapter 1.1 --- The immunoglobulin --- p.1 / Chapter 1.1.1 --- Immunoglobulin structure --- p.1 / Chapter 1.1.2 --- Immunogloblulin genes --- p.1 / Chapter 1.1.3 --- Immunogloblulin gene recombination --- p.3 / Chapter 1.1.4 --- Antibody diversity --- p.4 / Chapter 1.1.4.1 --- Imprecise joining --- p.5 / Chapter 1.1.4.2 --- N region addition --- p.5 / Chapter 1.1.4.3 --- Somatic mutation --- p.6 / Chapter 1.2 --- Hypermutation --- p.6 / Chapter 1.2.1 --- Features of hypermutation --- p.6 / Chapter 1.2.2 --- Germinal centre & Affinity maturation --- p.8 / Chapter 1.2.3 --- Mutational Hotspots --- p.9 / Chapter 1.2.4 --- Intrinsic characteristics of hypermutation --- p.10 / Chapter 1.2.5 --- Models for the mechanism of hypermutation --- p.11 / Chapter 1.2.5.1 --- DNA replication --- p.11 / Chapter 1.2.5.2 --- DNA repair --- p.12 / Chapter 1.2.5.3 --- Gene conversion --- p.13 / Chapter 1.2.5.4 --- Transcription --- p.15 / Chapter 1.2.5.5 --- Homologous recombination of reverse transcribed mRNA --- p.16 / Chapter 1.2.5.6 --- Transcription-coupled repair --- p.17 / Chapter 1.3 --- Scope of investigation --- p.17 / Chapter Chapter 2 --- Material and Method --- p.20 / Chapter 2.1 --- Materials --- p.20 / Chapter 2.2 --- Methods (first generation of LMPCR) --- p.21 / Chapter 2.2.1 --- Animal and cell lines --- p.21 / Chapter 2.2.2 --- Oxazolone antigen immunization --- p.21 / Chapter 2.2.2.1 --- Preparation of Bordetella pertussis --- p.21 / Chapter 2.2.2.2 --- Coupling of phenyloxazolone with CSA or BSA --- p.22 / Chapter 2.2.2.3 --- Preparation of aluminium hydroxide adjuvant --- p.23 / Chapter 2.2.2.4 --- Mice immunization --- p.23 / Chapter 2.2.3 --- Detection of anti-phOx antibody by enzyme-linked immunosorbent assay (ELISA) --- p.24 / Chapter 2.2.3.1 --- Reagents --- p.24 / Chapter 2.2.3.2 --- Assay procedure --- p.24 / Chapter 2.2.4 --- Extraction of genomic DNA (mice/cell line) --- p.25 / Chapter 2.2.4.1 --- Reagents --- p.25 / Chapter 2.2.4.2 --- Isolation of DNA from cell line (NQ2.12.4 & NQ5.4.3) --- p.25 / Chapter 2.2.4.3. --- DNA extraction from mice --- p.26 / Chapter 2.2.5 --- Ligation-mediated polymerase chain reaction (LMPCR) --- p.26 / Chapter 2.2.5.1 --- Procedure --- p.26 / Chapter 2.2.5.1.1 --- First primer extension --- p.29 / Chapter 2.2.5.1.2 --- Ligation --- p.29 / Chapter 2.2.5.1.3 --- PCR amplification --- p.30 / Chapter 2.2.5.1.4 --- Labelling of LMPCR product --- p.30 / Chapter 2.2.6 --- Marker preparation --- p.31 / Chapter 2.2.7 --- Polyacrylamide gel electrophoresis --- p.32 / Chapter 2.2.7.1 --- Reagents --- p.32 / Chapter 2.2.7.2 --- Procedure --- p.32 / Chapter 2.2.8 --- Southern blot hybridization --- p.33 / Chapter 2.2.8.1 --- Reagents --- p.33 / Chapter 2.2.8.2 --- DNA blotting --- p.34 / Chapter 2.2.8.3 --- Preparation of 32P labelling DNA probe --- p.34 / Chapter 2.2.8.4 --- Prehybridization and Hybridization --- p.35 / Chapter 2.2.9 --- Simplified protocol for the first generation of LMPCR --- p.36 / Chapter 2.3 --- Method (second generation of LMPCR) --- p.37 / Chapter 2.3.1 --- Excess linker removal --- p.37 / Chapter 2.3.1.1 --- Exonuclease III Treatment --- p.37 / Chapter 2.3.1.2 --- Mung bean nuclease Treatment --- p.37 / Chapter 2.3.1.3 --- Chroma Spin Treatment --- p.37 / Chapter 2.3.2 --- HindIII digestion after LMPCR --- p.38 / Chapter 2.3.3 --- DNA sequencing --- p.38 / Chapter 2.3.3.1 --- Cloning of amplified sequences to M13mpl9 plasmid --- p.38 / Chapter 2.3.3.2 --- Plaque hybridization --- p.39 / Chapter 2.3.3.3 --- Preparation of single-stranded templates --- p.39 / Chapter 2.3.3.4 --- Sanger dideoxy sequencing of single-stranded DNA --- p.40 / Chapter 2.3.4 --- Simplified protocol for second generation of LMPCR --- p.41 / Chapter Chapter 3 --- First generation of LMPCR --- p.42 / Chapter 3.1 --- General design --- p.42 / Chapter 3.1.1 --- LMPCR protocol and its modification --- p.42 / Chapter 3.1.2 --- Oligonucleotide design --- p.44 / Chapter 3.1.3 --- Experimental design --- p.48 / Chapter 3.2 --- Result --- p.50 / Chapter 3.2.1 --- Anti-phOx Ig level in normal and immunized mice --- p.50 / Chapter 3.2.2 --- LMPCR analysis of the sense strand of VkOxl --- p.50 / Chapter 3.2.2.1 --- Overall patterns of the LMPCR signals --- p.50 / Chapter 3.2.2.2 --- Southern hybridization --- p.50 / Chapter 3.2.2.3 --- Distribution of signals --- p.57 / Chapter 3.2.2.4 --- LMPCR analysis of the VkOxl-Jk5 anti-phOx transgene --- p.61 / Chapter 3.2.2.5 --- Effect of the number of cells carrying the VkOxl-Jk5 gene on LMPCR --- p.61 / Chapter 3.2.3 --- LMPCR analysis of the antisense strand of VkOxl --- p.64 / Chapter 3.3 --- Discussion --- p.64 / Chapter Chapter 4 --- Second generation of LMPCR --- p.72 / Chapter 4.1 --- Introduction(experi mental modification) --- p.72 / Chapter 4.1.1 --- Tagging the specific LMPCR products by addition of a Hin dIII site in the linker --- p.72 / Chapter 4.1.2 --- "Removal of excess linker, OXUH" --- p.72 / Chapter 4.1.2.1 --- Exonuclease III treatment --- p.73 / Chapter 4.1.2.2 --- Chroma spin treatment --- p.73 / Chapter 4.1.2.3 --- Mung Bean Nuclease treatment --- p.75 / Chapter 4.1.3 --- Other modifications in LMPCR --- p.75 / Chapter 4.2 --- Results --- p.75 / Chapter 4.2.1 --- Effect of including Exonuclease III treatment --- p.75 / Chapter 4.2.2 --- Effect of including Mung Bean Nuclease treatment --- p.76 / Chapter 4.2.3 --- Effect of including Chroma spin treatment --- p.76 / Chapter 4.2.4 --- Strand break positions detected at the sense strand --- p.76 / Chapter 4.2.5 --- DNA sequence analysis of the antisense strand LMPCR products --- p.82 / Chapter 4.3 --- Discussion --- p.84 / References --- p.89 / Appendix I --- p.98

Thesis (Ph. D.)--University of Washington, 2006. / Vita. Includes bibliographical references (p. 139-149).

Thesis (doctoral)--Lund University, 1998. / Includes bibliographical references.

Thesis (doctoral)--Lund University, 1998. / Includes bibliographical references.

published_or_final_version / abstract / Civil Engineering / Doctoral / Doctor of Philosophy