Thesis (M.S.)--Naval Postgraduate School, 1966. / Thesis advisor(s): Haderlie, Eugene C. Cover title. "May 1966." Includes bibliographical references (p. 44).

Thesis (Ph. D.)--University of Melbourne, 1972. / Includes bibliographical references.

Thesis (M. Sc.)--University of Hong Kong, 2009. / Includes bibliographical references (p. 62-71).

Thesis--Wisconsin. / Vita. Includes bibliographical references.

Thesis (Ph. D.)--State University of New York at Binghamton, Department of Biological Sciences. / Includes bibliographical references.

Thesis (Ph.D.)--Hong Kong University of Science and Technology, 2006. / Includes bibliographical references. Also available in electronic version.

Sessile marine invertebrate larvae can recognize suitable settlement substrata by using various environmental cues, including organic/microbial "biofilms". In laboratory assays the effect of biofilm age on the settlement of a range of fouling species was assessed: the species included barnacle, bryozoan, spirorbin and ascidian larvae. The larvae of most species responded differentially to films of varying ages. A general trend of reversal of the effect of filming on the settlement response of the barnacle Balanus amphitrite amphitrite- from inhibitory to facilitatory - was noted with increasing film age. The settlement of the solitary ascidian Ciona intestinalis clearly was facilitated on filmed substrata of all ages. The larvae of the arborescent bryozoan Bugula flabellata generally were inhibited by biofilming (irrespective of film age), and the settlement of the polychaete Spirorbis spirorbis was found to be enhanced on "older" (12d) films only. In a series of manipulative panel experiments in a tidal rapid on the west coast of Scotland the effects of biofilming on subsequent larval settlement in the field were quantified. Inhibitory and facilitatory responses to biofilming were noted and these varied markedly between species and between two local habitats of contrasting flow regimes. The larvae of certain year-round settling species were found to vary in their response to biofilmed substrata depending on the season. Quantitative data were obtained for biofilms on artificial substrata by enumerating bacteria, diatoms, protozoans, fungi and the percent cover of microbial exopolymeric substances. These permitted comparisons of biofilms both in field and laboratory experiments. The results of the present study emphasize the importance of microbial surface film cues in explaining recruitment patterns of macrofouling assemblages during the first stages of substratum colonization.

This thesis analyses the development of safety regulation for the intentional release of genetically modified organisms (GMOs) between 19 89-92, especially in Britain in its European context, and by contrast to the USA. The thesis emphasizes the practical dilemmas of GMO regulation in accommodating uncertainties about public unease and environmental harm. It serves as a case study of safety regulation as a constructed rationality, of national regulatory styles, and of environmental precaution. In anticipating hazards prior to evidence of harm, GMO regulation had a contested 'rational' basis. Regulators encountered disputes in defining the risk problem, in establishing risk-management institutions, and in reducing scientific uncertainty about potential harm. Insofar as GMO regulation had a precautionary content, it undermined the 'rational' stereotype of risk-assessment steps. Both the precautionary potential and its limits derived from the project of overcoming obstacles to a biotechnology market. This meant symbolically normalizing GMOs as benign products, while specifying testable ecological uncertainties rooted in some naturalistic analogy. Technical 'risk' abstracted potential harm from issues of socioagronomic control which underlay the earlier environmental controversy. The thesis argues for recasting theoretical models of safety regulation as a 'technical' or 'procedural' rationality. GMO regulation contained poles of tension which such theoretical models attribute to antagonistic rationalities. Broadly speaking, the regulatory system was managing an internal contradiction between social legitimacy and commercialization. The difficulties of GMO regulation arose from its implicit role in legitimizing biotechnology, by default of any democratic procedure for adjudicating a contentious technoscientific development.

With an increasing amount of whole genome sequence data becoming available on a daily basis we have an opportunity to study the interactions and dynamics of different organisms on a whole genome level. In the past, reports of horizontal gene transfer have focused mainly on the identification of single genes that show distorted phylogenetic profiles to that of the organism it was isolated from. This study firstly did whole genome comparisons between the rice nuclear and plastid genomes to determine the level and dynamics gene transfer and insertion of the chloroplast ad mitochondrial genomes into that of the nuclear genome of rice. Secondly, it looked to identify sequence similarities between the rice genome and microbial genomes by performing whole genome comparisons between the rice genome and that of several microbial genomes. These sequences were analyzed further to identify possible instances of horizontal transfer of DNA from microbes to the rice genome. Using this approach, this study reports several fragments in the rice genome with significant sequence similarity to that of microbial DNA fragments. This study also provides evidence supporting horizontal transfer of several of these fragments. This study provides valuable information regarding intra- as well as inter-genome DNA transfer dynamics. / Thesis (PhD)--University of Pretoria, 2009. / Plant Science / unrestricted

Combretaceae contain several species with bioactive properties - especially the genera Combretum and Terminalia. Pteleopsis myrtifolia and Quisqualis littorea belong to this family and have not previously been thoroughly investigated for their bioactivity. Leaf and fruit extracts of P. myrtifolia and leaf extracts of Q. littorea were separated by three different thin layer chromatography eluent systems. For all leaf and fruit material, the largest amount of acetone soluble material was extracted with extractants of intermediate polarity. Antibacterial activity of 30 extracts was investigated using a microplate serial dilution method and bioautography. The four most important nosocomial pathogens that are used worldwide namely two Gram-positive: Staphylococcus aureus and Enterococcus faecalis, and two Gram-negative bacteria: Pseudomonas aeruginosa and Escherichia coli were used as test organisms. Areas of growth inhibition were best defined after an eluent system that separates compounds of intermediate polarity had been used. The Gram-positive bacteria were most sensitive to some extracts of P. myrtifolia leaves. Fruit extracts exhibited minimum inhibitory concentrations (MIC) values as low as 0.04 mg/ml, less than that of the allopathic antibiotics, ampicillin and chloramphenicol. Q.littorea leaf extracts had an average MIC value of 0.32 mg/ml for Gram-negative bacteria. The average antibacterial activity expressed as total activity for each bacterium was higher in the leaves than in the fruit of P. myrtifolia. After considering the amount of antibacterial compounds extracted, toxicity of extractants to test organisms and miscibility of several extractants, acetone was eventually chosen as the best extractant for future extractions. Results obtained in this investigation showed clearly that P. myrtifolia leaves, fruit, and Q. littorea leaves contain several antibacterial compounds. Five different extracts of P. myrtifolia leaves were tested for growth inhibitory effects on different human cell lines (MCF-12, MCF-7, H157, WHCO3, HeLa). The non-cancerous MCF-12A cell line’s growth was not inhibited extensively, and the cancer cell lines - MCF-7, H157, WHCO3 and HeLa, differed in their sensitivity to the plant extracts. This indicated that the plant extracts’ effects were selective and not due to general toxicity. The effect of some extracts on certain cell lines, especially WHCO3, was growth inhibitory but not lethal. This is the desired effect – to inhibit growth of cancer cells, but not to be toxic to cells in general. The presence of tannin in extracts either promoted or inhibited growth inhibition of different cell lines. The same extractants that were used for cytotoxic tests were investigated for their antioxidant activity. All extracts gave positive scavenging capacity with the 1,2-diphenyl-2-picrylhydrazyl assay. The cold water, methanol and hot water extracts had vitamin C equivalents of 0.34, 0.20 and 0.147 mg/g respectively, all more than that of black tea. The solvent-solvent separation of P. myrtifolia leaves was started with acetone as an initial extractant. Separation was undertaken with immiscible solvents of different polarities. All fractions had antibacterial activity against the Gram-positive bacteria. The chloroform fraction was antibacterial to all bacteria tested, and had the largest amount of antibacterial compounds. Pure compounds were isolated from the chloroform fraction by column chromatography. One pure compound’s structure was elucidated as a pentacyclic triterpenoid, taraxerol (C30H50O). Taraxerol had MIC values of 0.04, 0.016, 0.63 and 0.31 mg/ml for the bacteria S. aureus, E. faecalis, P. aeruginosa and E. coli respectively. It significantly inhibited growth of the human lung cancer cell line H157 and did not display free radical scavenger activity. This is the first report of the antibacterial activity of several extracts from P. myrtifolia and Q. littorea, growth inhibition effects of several P. myrtifolia leaf extracts on the human cell lines MCF-12, MCF-7, H157 and WHCO3, the isolation of taraxerol from P. myrtifolia leaves, taraxerol’s antibacterial activity for above-mentioned test organisms, and growth inhibition effects on human cancer cell lines MCF-7, H157, WHCO3 and HeLa. / Thesis (PhD (Pharmacology))--University of Pretoria, 2008. / Pharmacology / unrestricted