Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第15652号 / 工博第3310号 / 新制||工||1500(附属図書館) / 28189 / 京都大学大学院工学研究科都市社会工学専攻 / (主査)教授 小尻 利治, 教授 椎葉 充晴, 教授 角 哲也 / 学位規則第4条第1項該当

Limited research has been performed in Ontario to ascertain risk factors for West Nile Virus (WNV) and to develop a unified risk prediction strategy. The aim of the current body of work was to use spatio-temporal modelling in conjunction with surveillance and environmental data to determine which pre-WNV season factors could forecast a high risk season and to explore how well mosquito surveillance data could predict human cases in space and time during the WNV season. Generalized linear mixed modelling found that mean minimum monthly temperature variables and annual WNV-positive mosquito pools were most significantly predictive of number of human WNV cases (p<0.001). Spatio-temporal cluster analysis found that positive mosquito pool clusters could predict human case clusters up to one month in advance. These results demonstrate the usefulness of mosquito surveillance data as well as publicly available climate data for assessing risk and informing public health practice.

O excesso de vitaminas lipossolúveis na dieta pode ser acumulado no fígado e causar hipervitaminose em animais. Os objetivos deste trabalho foram determinar a exigência nutricional em vitamina A para juvenis da tilápia do Nilo Oreochromis niloticus, avaliar o desempenho da espécie através do ganho de peso e conversão alimentar e quantificar os depósitos de retinol hepático em animais de uma população revertida sexualmente para o sexo masculino (R; 13,76 ± 1,21 g) e outra não revertida (NR; 9,83 ± 2,30 g). Os peixes foram estocados em aquários de polipropileno de 100 L, em ambiente com condições controladas de temperatura (25,0 ± 1,0 o C) e luminosidade (12h00m:12h00m), e alimentados ad libitum duas vezes ao dia, durante 75 dias, com dietas semipurificadas, suplementadas com 0; 600; 1200; 1800; 2400; 3000; 3600; 4200; 4800 e 5400 UI kg -1 de dieta de retinil palmitato (Rovimix A 500 Roche ® ), em delineamento experimental inteiramente casualizado em esquema fatorial 2x10 (n=4). Ao final do experimento todos os lotes de animais foram sacrificados para a análise de retinol hepático. Sinais severos de deficiência nutricional em vitamina A foram encontrados em animais dos tratamentos 0; 600 e 1200 UI vitamina A kg -1 de dieta; sinais moderados foram também encontrados em animais dos tratamentos entre 1800 e 3600 UI vit A kg -1 de dieta, em ambos os grupos. As interações grupo*nível não foram significativas (P<0,05) para todas as variáveis de desempenho analisadas. Níveis crescentes de inclusão da vitamina A influenciaram o peso final e ganho de peso dos peixes (P<0.05), mas não influenciaram o consumo de ração (P>0,05). Houve um efeito de grupo para todas as variáveis analisadas (P<0,0001). A análise cromatográfica somente detectou depósitos de vitamina A no fígado dos animais alimentados com a dieta contendo 5400 UI kg -1 de retinol. / Excess dietary fat-soluble vitamins can be accumulated in the liver and cause hypervitaminosis in animals. The aim of this research was to establish the vitamin A requirement for Nile tilapia Oreochromis niloticus, evaluating weight gain and food conversion ratio, and quantifying hepatic retinol deposits in a sex reversed, all male population (R; 13.76 ± 1.21 g) and a mixed sex population (NR; 9.83 ± 2.30 g ). Fish were stocked in 100-L plastic aquaria, in controlled environmental conditions of temperature (25,0 ± 1,0 ºC) and luminosity (12h00m : 12h00m), and fed ad libitum, twice a day, seven days a week, during seventy five days with semi-purified diets supplemented with 0; 600; 1,200; 1,800; 2,400; 3,000; 3,600; 4,200; 4,800 and 5,400 IU of retinol palmitate per kg of diet (Rovimix A 500 Roche ® ; 30 % vitamin A) in a totally randomized experimental design, factorial arrangement 2x10 (n=4). At the end of the experiment all groups were sacrificed and liver tissue excised for the hepatic retinol analyses. Severe signs of nutritional deficiency of vitamin A were observed in fish of treatments 0; 600 and 1,200 IU vitamin A kg -1 diet; moderate signs were also found in fish of treatments 1,800 trough 3,600 IU vitamin A kg -1 diet, both populations. Interactions group*level were not significant (P<0.05) to all analyzed performance variables. Increasing levels of dietary vitamin A influenced final weight and weight gain of the fish (P<0.05), but did not influence feed consumption (P>0.05). A group effect was observed regarding all performance variables (P<0.0001). Hepatic retinol quantification (High Performance Liquid Chromatogaphy) detected vitamin A only in fish fed 5,400 IU of retinol per kg of diet.

The effect of native hyaluronan addition on CMC of excluded surfactants (Tween 20, BETADET THC 2, SDS, CTAT a CTAB) in physiological solution (0,15 M NaCl) has been investigated by fluoresence spectroscopy with Pyrene and Nile red as probes. The greatest influence on CMC has been observed in systems with cationic surfactant. System of cetyltrimethylamonnium bromid has been closely studied. Solubilization experiments with a hydrophobic dye Sudan red has been realized and aggregation number of this system has been determinated via fluorescence quenching with cetylpyridinium chloride as quencher and Pyrene as fluorescence probe. Addition of hyaluronan (native or hydrophobicaly modified) reduces aggregation number of system.

<div> <div> <div> <p>Flaviviruses is a genus within the family Flaviviridae. The genus consists of more than 70 viruses, including important threatening human pathogens such as dengue virus (DENV), West Nile virus (WNV), and Zika virus (ZIKV). These viruses are causative agents for a range of mild to lethal diseases and there are currently no US- licensed therapeutic treatments for infection. The virus genome is a positive-sense, single-stranded RNA, encoding ten viral proteins. Of the ten flavivirus proteins, Non- Structural protein 1 (NS1) remains the most elusive in terms of its functions. To date NS1 has been linked to disease pathology and progression and plays roles in virus replication and assembly. However, little is understood how NS1 orchestrates these functions and how NS1 from different viruses function distinctively from one another. Moreover, flavivirus NS1 has a peculiar ability to associate with lipid membranes. During the life cycle of NS1, the protein travels through the classical secretory path- way, similar to infectious virus particles, and is secreted into the extracellular space as mostly hexameric oligomers containing a lipid core. How the protein binds to lipids and whether such lipid binding is important for NS1 functions and overall flavivirus pathology remain unknown. Using structure-based mutagenesis, we found a group of mutants on WNV NS1, which particularly altered the viral specific infectivity but maintained wild-type level of virus replication. Purified mutated virus particles revealed that the specific infectivity alteration was not because of the particle but interaction of the virus particles and NS1 mutated proteins. Here we demonstrated that specific residues on NS1 were responsible for distinctly roles in NS1 functions and the virus specific infectivity was regulated by NS1 protein. In other structure-base study, we focused on the membrane association ability of NS1. All structure-predicted regions on NS1 were examined for its contribution for the membrane/lipid binding function. This interaction was required for NS1 biology activities including intracel- lular trafficking, oligomerization, and endocytosis. The lipidomes from deletion of each membrane association region revealed differences in lipid classes binding to each region and the composition flexiblity of the lipid cargo of NS1 hexamer. </p> </div> </div> </div>

The objectives of the study are to: (1) Critically analyse the 1959 Nile River agreements from a human rights perspective (2) examine the applicability of international human rights law in water distribution and use and (3) investigating how human rights norms and principles can be used, if at all, as a means of solving water conflicts over the use of trans-boundary rivers. The study adopts a human rights approach in its consideration of the problem of conflicts that may arise in connection with the use of trans-boundary rivers. It is particularly significant as it seeks to explore the solution from the human rights of the people in the riparian countries. It is believed that the study will contribute to the development of basin-wide cooperation among riparians by being employed in negotiations and planning of projects. / Thesis (LLM (Human Rights and Democratisation in Africa))--University of Pretoria, 2008. / Dissertation submitted to the Faculty of Law University of Pretoria, in partial fulfilment of the requirements for the degree Masters of Law (LLM in Human Rights and Democratisation in Africa). Prepared under the supervision of Dr Raymond A. Atuguba of the Faculty of Law, University of Ghana Legon, Accra, Ghana / http://www.chr.up.ac.za/ / Centre for Human Rights / LLM

In most tropical river systems there has been a lack of integrated ecological research to investigate the dynamics and impacts of invasive species on recipient river systems. This is in sharp contrast to temperate river systems. This thesis investigated the nature, extent, and impact of Nile tilapia, Oreochromis niloticus (Linnaeus, 1758), on indigenous congenerics within the Limpopo River basin in northern South Africa. An integrated approach was adopted to gain a better understanding of factors that allow Nile tilapia to be a successful invader and also to gain an insight into its invasion rate and conservation implications within South Africa. Morphometric and genetic variation between Nile tilapia, indigenous congenerics and their associated hybrids were determined. Intermediate meristic characters obscured the identification of hybrid specimens from pure morpho-specimens and species identity was only confirmed through mtDNA analysis. Preliminary evidence points to unidirectional hybridization among Oreochromis congeners in the Limpopo River system. The hypothesis that bigger Nile tilapia males may have a competitive advantage over spawning grounds and in female mate choice is proposed. The trophic ecology of Nile tilapia was investigated using both stomach contents and stable isotope analysis. A high similarity in stomach contents was observed but interspecific differences were revealed in the isotopic composition of diets that suggest fine scale patterns of resource partitioning that could be achieved by the ability of fish to selectively feed on what is immediately available and the ability to perceive the dynamics that determine food resource availability. Ecological niche models were used to determine the potential invasive range of Nile tilapia and revealed broad invasive potential over most river systems in southern Africa that overlapped the natural range of endemic congenerics. It was noted that model performance and the degree of niche conservatism varied significantly with variable selection and spatial extent of study area. This implied that the spatial distribution of suitable and unsuitable environmental variables varied between the native and introduced ranges of Nile tilapia and also indicated the ability of Nile tilapia to survive in conditions incongruent with its native range. The extreme hardiness and adaptive life history characteristics of Nile tilapia have probably predisposed it to be a successful invader in novel systems within southern Africa. Lastly, a qualitative risk assessment method was developed as a potential application to determine the risk of establishment and spread of the invasive Nile tilapia. Results showed that in the absence of quantitative data on ecosystem structure and functioning, habitat suitability analysis in terms of known physiological tolerance limits to minimum water temperature, presence or absence of dams, seasonality of river flows and the presence of indigenous fish species of concern could be adequate for identifying vulnerable river systems. The model developed also provides an objective method that is easy to implement, modify and improve on as new data become available. Furthermore, the model can be applied to highlight areas of uncertainty where future research should be directed. / Thesis (PhD)--University of Pretoria, 2012. / Zoology and Entomology / Unrestricted

West Nile Virus (WNV) forms part of the Japanese encephalitis serocomplex in the genus Flavivirus, family Flaviviridae. This enveloped positive single-stranded RNA (+ssRNA ) virus is the etiological agent of West Nile fever, and in more severe cases WNV neuroinvasive disease, in both humans and animals. WNV is distributed worldwide and is phylogenetically classified into five distinct lineages. The WNV genome is ~11 Kb in length and encodes a single open reading frame (ORF) that is post-translationally cleaved into three structural proteins and seven non-structural proteins. In this study, two contemporary and two historic South African WNV strains were genetically characterised as lineage 2 strains based on complete genome sequences. Genetic change as a result of passage number and propagation system was quantified on both the consensus genome- and quasispecies level. A lack of variation was observed amongst the consensus genome sequences of WNV strains subject to changes in propagation system from BHK-21 cell culture to mouse brain and vice versa. In contrast, variation amongst the latter was observed on the quasispecies level. Genome-wide single nucleotide polymorphism (SNP) profiles as well as full-length haplotype sequences reconstructed from ultra deep sequence data indicated that high levels of quasispecies diversity persists, particularly in the capsid gene region, during changes in propagation environment. The changes in frequency of variants were consistent throughout isolates propagated in different systems. The increased variation in the capsid gene region may result from selective pressures brought about by differences in host cell type between propagation systems. This study is the first to demonstrate quasispecies dynamics resulting from changes in propagation system of a lineage 2 WNV based on the reconstruction of full-length haplotype sequences from ultra deep sequence data. The approach demonstrates a cost-effective alternative to the estimation of viral population structure in light of viral evolutionary dynamics, which may in turn be assessed by the single plasmid reverse genetic system designed in this study. Although early attempts at rescuing an infectious WNV clone were unsuccessful, the system shows promise in the application of future studies concerning vaccine and diagnostic development, virulence studies and disease control. / Dissertation (MSc)--University of Pretoria, 2013. / gm2013 / Zoology and Entomology / Unrestricted

L’objectif de cette thèse est de déterminer une reconstruction de l’altération continentale dans le bassin du Nil depuis 100.000 ans, afin de mieux comprendre l’impact des variations climatiques sur les sols, les apports à la Méditerranée et le cycle du carbone. Ce travail repose sur une étude géochimique fine des argiles extraites d’archives sédimentaires du delta du Nil sur une échelle de temps de 100.000 ans. Il repose sur une approche inédite du couplage d’un traceur de source (isotopes du néodyme) et de traceurs d’altérations (isotopes du lithium). Les résultats de cette étude mettent en évidence une réponse rapide de l’altération continentale aux variations hydro-climatique en Afrique du Nord. De plus, les changements climatiques en Atlantique Nord et du ralentissement de l’AMOC ont eu une influence importante sur la diminution de l’intensité d’altération continentale dans le bassin du Nil. A l’actuel, les taux d’altération, et la consommation de CO2 associée, des trapps d’Ethiopie sont relativement faibles par rapport aux autres régions basaltiques. Nos résultats montrent cependant que durant l’African Humid Period, la consommation de CO2 dans cette région était 2 à 3 fois plus importante qu’aujourd’hui. Cela indique que les trapps d’Ethiopie ont pu jouer un rôle non négligeable dans le cycle du CO2, et en particulier lors des périodes de fort runoff. Enfin, des développements analytiques ont été réalisés afin de pouvoir exploiter les compositions isotopiques en lithium des carbonates biogéniques marins, comme nouveaux traceurs des apports en eau douce du Nil. Les résultats obtenus suggèrent une influence des effets dits « vitaux » et des processus de diagénèse. / This thesis presents a reconstruction of the chemical weathering in the Nile basin since 100.000 years. His objective is to better understand the impact of climatic variations on chemical weathering, to better. This work is based on the geochemistry study on marine core recorded in the Nile delta, on a time scale of 100.000 years. It use a novel approach with the coupling of à source tracer (εNd) and chemical weathering tracers (δ7Li and elementary ratios) on the fine fraction (< 2µm). In addition, it was analyzed samples of each actual Nil sources and a core sample from Tana Lack (Ethiopie). The results of this studies have enabled to reconstruct the chemical weathering variations in the Nile basin since 100.000 years. It show a rapid respond of chemical weathering to climate variations. This was also observed by important impact of North Atlantic climate variations on the decrease of chemical weathering in the Nile basin. At present, the chemical weathering flux and the CO2 consumption of the Ethiopian traps are low comparted to the other basaltic regions, as the Deccan. However, our results show that during the most humid periods (African Humid Period) the CO2 consumption was 2 to 3 time higher than today. This indicates that the Ethiopian traps could be have played a non-negligible role in the global CO2 cycle during the Cenozoic, and principally during the most humid periods in North Africa. Finally, analytical developments have been realized to be able to exploit the lithium isotopes on biogenic carbonates as a new tracer of Nile water flood. The results suggest an influence of “vital” effect and diagenetic process.

Natural products offer many possibilities for the treatment of disease. More than 70% of the Earth’s surface is ocean, and recent exploration and access has allowed for new additions to this catalog of natural treasures. The Central Red Sea off the coast of Saudi Arabia serves as a newly accessible location, which provides the opportunity to bioprospect marine sponges with the purpose of identifying novel antiviral scaffolds. Antivirals are underrepresented in present day clinical trials, as well as in the academic screens of marine natural product libraries. Here a high-throughput pipeline was initiated by prefacing the antiviral screen with an Image-based High-Content Screening (HCS) technique in order to identify candidates with antiviral potential. Prospective candidates were tested in a biochemical or cell-based assay for the ability to inhibit the NS3 protease of the West Nile Virus (WNV NS protease) as well as replication and reverse transcription of the Human Immunodeficiency Virus 1 (HIV-1). The analytical chemistry techniques of High-Performance Liquid Chromatograpy (HPLC), Liquid Chromatography-Mass Spectrometry (LC-MS), and Nuclear Magnetic Resonance (NMR) where used in order to identify the compounds responsible for the characteristic antiviral activity of the selected sponge fractions. We have identified a 3-alkyl pyridinium from Amphimedon chloros as the causative agent of the observed WNV NS3 protease inhibition in vitro. Additionally, we identified debromohymenialdisine, hymenialdisine, and oroidin from Stylissa carteri as prospective scaffolds capable of HIV-1 inhibition.