L'homéostasie cellulaire implique une régulation fine de la production ainsi que de l'élimination des protéines. La dérégulation de cette homéostasie entraîne des effets néfastes touchant de nombreuses voies de signalisation et de métabolisme et pouvant conduire à diverses maladies telles que le cancer ou la neurodégénérescence. De ce fait, la dégradation des protéines est un processus hautement contrôlé effectué par le système ubiquitine-protéasome (UPS) qui permet le ciblage, l’étiquetage et la dégradation des protéines mal repliées, endommagées ou en fin de vie. Le protéasome est un complexe multiprotéique vital présent dans toutes les cellules eucaryotes dont la biogenèse, la fonction de dégradation et la régulation dans le cytoplasme sont bien connues. Cependant, la fonction du protéasome dans le noyau, notamment en réponse au stress, est encore peu comprise. Les cellules ont développé de nombreux mécanismes adaptatifs en réponse à la variation de l'apport en nutriments comme l’augmentation de la dégradation et le recyclage des protéines. Chez l’humain, le protéasome est dégradé dans le cytoplasme par autophagie lors d’une privation de nutriments mais les mécanismes de régulation du protéasome nucléaire en réponse au stress métabolique restent peu connus. Nous avons trouvé que le protéasome 26S et la sous-unité régulatrice PSME3 forment des foyers nucléaires dans différents types cellulaires de mammifère en réponse à une privation en nutriments. Les foyers, nommés SIPAN pour Starvation-Induced Proteasome Assemblies in the Nucleus, ne sont colocalisés avec aucune structure ou corps nucléaires connus. La formation des SIPAN est réversible lors d’une réintégration des nutriments, suggérant une réponse spécifique liée à un stress métabolique. La manipulation de la quantité d’acides aminés intracellulaire a révélé que les acides aminés non-essentiels jouent un rôle important dans la formation et la résolution des SIPAN. Une analyse métabolomique a permis de trouver des voies reliées au métabolisme des nucléotides et des acides aminés qui pourraient fournir des facteurs clés pour la dissipation des foyers du protéasome. Le fort dynamisme des SIPAN, la présence d’événements de fusion et leur instabilité vis-à-vis des conditions cellulaires suggèrent que les SIPAN résultent d’une séparation de phase liquide-liquide (LLPS). De plus, nous avons trouvé que l’ubiquitine conjuguée est présente dans les SIPAN et que l’ubiquitination et la déubiquitination semblent être impliquées dans la formation et la résolution, respectivement. Nous avons ensuite découvert que la perte du récepteur à l’ubiquitine RAD23B empêche la formation des SIPAN. En effet, les domaines de liaison au protéasome UBL et de liaison à l’ubiquitine UBA1/UBA2 sont nécessaires pour la formation des SIPAN. De manière intéressante, la perte de RAD23B ou du complexe régulateur PSME3 retarde l’induction de l’apoptose et promeut la survie cellulaire. Enfin, en utilisant un inducteur de l’apoptose, nous avons observé l’apparition de ces foyers du protéasome dans le noyau des cellules dont certaines caractéristiques sont similaires aux SIPAN. Notre étude aborde une question très importante dans la compréhension des rôles et du dynamisme du protéasome nucléaire, en particulier dans l'adaptation au stress, qui peut réguler le niveau des protéines nucléaires. De façon générale, cela nous aidera à mieux comprendre le rôle du protéasome dans l’homéostasie nucléaire et son implication dans les maladies humaines. / Cellular homeostasis involves specific regulation of the production as well as the elimination of proteins. The deregulation of this equilibrium leads to harmful effects affecting many signaling and metabolic pathways and can lead to various diseases, such as cancer or neurodegeneration. Hence, protein degradation is a highly controlled process performed by the ubiquitin-proteasome system (UPS) that allows targeting, labeling and degradation of misfolded, damaged, or end-of-life proteins. The proteasome is a vital multiprotein complex found in all eukaryotic cells whose biogenesis, degradative function, and regulation in the cytoplasm are well known. However, the function of the proteasome in the nucleus, particularly in response to stress, is still poorly understood. Cells have evolved many adaptive mechanisms in response to varying nutrient supply such as increased protein degradation and recycling. In humans, the proteasome is degraded in the cytoplasm by autophagy during nutrient deprivation, but the regulatory mechanisms of the nuclear proteasome in response to metabolic stress remain poorly understood. We have found that the 26S proteasome and regulatory subunit PSME3 form nuclear foci in different mammalian cell types in response to nutrient deprivation. These foci, called SIPAN for Starvation-Induced Proteasome Assemblies in the Nucleus, do not colocalize with any known nuclear structures or bodies. The formation of SIPAN is reversible upon nutrient replenishment, suggesting a specific response to metabolic stress. Manipulation of the intracellular amino acid pool revealed that non-essential amino acids play important roles in the formation and resolution of SIPAN. A metabolomics study has identified pathways related to nucleotide and amino acid metabolism that may provide key factors for the dissipation of the proteasome foci. The strong dynamism of SIPAN, the presence of fusion events and their instability towards cellular conditions suggest that SIPAN result from liquid-liquid phase separation (LLPS). Additionally, we have found that conjugated ubiquitin is present in SIPAN and that ubiquitination and deubiquitination appear to be involved in their formation and resolution, respectively. We then discovered that the depletion of the ubiquitin receptor RAD23B prevents the formation of SIPAN. Indeed, the UBL proteasome binding domain and UBA1/UBA2 ubiquitin binding domains are required for SIPAN formation. Interestingly, the depletion of RAD23B or the proteasome regulatory particle PSME3 delays the induction of apoptosis and promotes cell survival. Finally, we found that an apoptosis-inducing agent promotes proteasome foci formation in the nucleus of cells, and these organelles share similarities with SIPAN. Our study addresses a very important question in understanding the roles and dynamism of the proteasome in the nucleus, specifically during stress adaptation, which can regulate the level of nuclear proteins. In general, this will help us to better understand the role of the proteasome in nuclear homeostasis and its involvement in human diseases.

Syfte: Att studera den tillgängliga litteraturen om hur minskad näringstillförsel i form av fasta, Anorexia nervosa (AN), protein-energiundernäring (PEU) och sondmatning påverkar det orala ekosystemet. Material och metod: Det utfördes en narrative review på artiklar som identifierats med hjälp av Pubmed databas. Artiklar som handlar om minskad näringstillförsel och dess konsekvenser för den orala miljön har granskats. Resultat: Fasta hade effekt på salivens sammansättning, flödeshastighet och buffringskapacitet. Personer med svält tillståndet Anorexia nervosa (AN) upplevde bland annat förändringar i slemhinnor, saliv pH-värde och salivflödeshastighet. Personer med protein-energiundernäring (PEU) löpte stor risk för flera orala förändringar som medför bland annat högre kariesförekomst och sämre prognos för inflammatoriska lesioner. Flera av bakterierna som dominerade hos personer med sondmatning var patogena bakterier som kan vara hälsoskadliga. Slutsats: Vid fasta uppstår det förändringar i salivflödeshastighet, sammansättning, mängd och buffringskapacitet. AN kan leda till förändringar i saliven. PEU innebär stor risk för flera orala förändringar som medför bland annat högre kariesförekomst och sämre prognos för inflammatoriska lesioner. Tidig PEU har en fortsatt negativ effekt på salivens funktion även i tonårsåldern. Flera av bakterierna som dominerar hos personer med sondmatning är patogenabakterier som kan vara hälsohotande. Flera orala, mikrobiella och biologiska förändringar manifesterar sig i samband med minskad näringstillförsel. Det behövs fler studier för att få en bättre förståelse av dessa förändringars kliniska betydelse. / Aim: To review the available literature on how reduced nutrient supply in the form of fasting, Anorexia nervosa (AN), protein-energy malnutrition (PEU) as well as tube feeding affect the oral ecosystem. Material and method: A narrative review was performed on articles identified using the Pubmed database. Articles about nutritional deficiencies and their consequences on the oral environment have been reviewed. Results: Fasting influenced saliva composition, flow rate and buffering capacity. People with Anorexia nervosa (AN) experienced, among other things, changes inmucous membranes, saliva pH-value and saliva flow rate. It was shown that people with protein-energy malnutrition are at high risk for several oral changesthat lead to a higher incidence of caries and a worse prognosis for inflammatory lesions etc. Several of the bacteria that dominated in people with enteral nutrition were pathogenic bacteria; that can be damaging to health. Conclusions: During fasting, changes in saliva flow rate, composition, amount, and buffering capacity occur. People with AN experience among other things, changes in mucous membranes, pH value and flow rate of saliva. PEU involves a high risk of several oral changes that lead to, among other things, a higher incidence of caries and a worse prognosis for inflammatory lesions. Early PEU has a continued negative effect on saliva function in adolescence. Several of the bacteria that predominate in people with tube feeding are pathogenic bacteria that can be health-threatening. Several oral, microbial, and biological changes manifest themselves in connection with malnutrition. More studies are needed to gain a better understanding of the clinical significance of these changes.

Der Abbau der PBS unter Stickstoffmangel ist in Cyanobakterien ein ubiquitärer Mechanismus. Essenziell für den Abbau ist das Protein NblA. Das in Nostoc sp. PCC 7120 gut untersuchte ~7 kDa große Protein interagiert als Homodimer mit den PBS und dem Chaperon ClpC. Soweit bekannt kodieren alle Cyanobakterien ein essenzielles NblA-Protein. Der Modellorganismus Synechocystis sp. PCC 6803, dagegen kodiert mit NblA1 und NblA2 sogar zwei für den PBS-Abbau entscheidende Proteine. In dieser Arbeit konnte erstmalig durch in vitro und in vivo Interaktionsstudien mithilfe von pull down-Versuchen und FRET gezeigt werden, dass NblA1 und NblA2 als biologisch aktive Form ein Heterodimer bilden. In vitro-pulldown-Versuche zeigten für Synechocystis eine Interaktion des Heterodimers mit den PBS und ClpC. Durch die Ausbildung dieses ternären Komplexes markiert NblA1/NblA2 die PBS für den Abbau durch eine Clp-Protease mit ClpC als Chaperonpartner. In Photobionten gibt es eine Reihe von clp-Genen, so besitzen Cyanobakterien vier proteolytische clp Untereinheiten. Aus diesen bilden sich gemischte Heptamere aus je zwei Clp-Untereinheiten. Zwei lösliche, im Cytoplasma vorkommende Proteasen wurden bis jetzt zweifelsfrei identifiziert, eine dritte, an der Thylakoidmembran assoziierte Protease wird außerdem vermutet. Diese putative Protease, vermutlich aus dem Chaperon ClpC und den proteolytischen Untereinheiten ClpP1 und ClpR aufgebaut, wurde heterolog exprimiert. Mittels Koreinigung konnte ein funktioneller proteolytischer Kern gereinigt werden, der zusammen mit dem Chaperon ClpC eine aktive Clp-Protease bildet. Durch Größenausschlusschromatografie und Untersuchungen zur Proteaseaktivität konnte diese dann erstmalig charakterisiert werden. Des Weiteren zeigten in vitro-Degradationsversuche mit der aktiven Protease zweifelsfrei, dass das NblA1/NblA2-Heterodimer durch ClpC-ClpP1/ClpR abgebaut wird. Der Abbau von NblA1/NblA2 kann demnach auch ohne ein Substrat durch die Protease erfolgen. / The degradation of pycobilisomes under nitrogen deficiency, which is visible as a color change from blue green to yellow green, is an ubiquitary mechanism. Essential for the degradation is the small NblA protein. The well characterized NblA protein from Nostoc sp. PCC 7120 builds as biological active form a homodimer and interacts with the phycobilisomes and ClpC. However, the model organism Synechocystis sp. PCC 6803 possess two nblA genes, nblA1 and nblA2, which are both essential for phycobilisome degradation. In this work it could be shown by interaction studies and Förster resonance energy transfer that NblA1 and NblA2 builds as biological active form a heterodimer. Furthermore it could be shown that the NblA proteins form a ternary complex with ClpC (the HSP100 chaperone partner of Clp proteases) and phycobiliproteins in vitro. This complex is susceptible to ATP-dependent degradation by a Clp protease. Clp proteases of Cyanobacteria consist, besides the chaperones ClpC and ClpX of three different proteolytic subunits (ClpP1, 2, 3) and the ClpP variant ClpR which lacks the catalytic triad typical of Serine-type proteases. In Synechococcus 7942 two Clp proteases could be identified by gel filtration and immunoblot analyses, which provided evidence that each protease consists of a unique proteolytic core comprised of two separate Clp subunits, one core consisting of ClpP1 and ClpP2, and the other of ClpP3 and ClpR, in which subunits ClpP1/ClpP2 interact with ClpX and the ClpP3/ClpR protease with ClpC. In addition to these two soluble proteases, a third, membrane associated proteolytic complex is assumed, consisting of ClpP1 and ClpR. In Synechocystis 6803, homologs of the Clp machinery could be found by BLAST analyzes. This putative ClpP1/ClpR protease could be characterized in vitro by size-exclusion chromatography and degradation assays. Furthermore it could be shown a degradation of the NblA1/NblA2 heterodimer by the protease.

No description available.

Immune activation is generally acknowledged to be costly. These costs are frequently assumed to result from trade-offs arising due to the reallocation of resources from other life-history traits to be invested in immunity. Here, I investigated the energetic basis of the costs associated with immune activation in Drosophila melanogaster. I found that immune activation significantly reduced fly fecundity (45%) and also caused a decline in metabolic rate (6%) but had no effect on body weight. To understand the factors behind reduced fecundity and metabolic rate I measured feeding and found that food intake was reduced by almost 31% in immune-challenged D. melanogaster. These findings suggest that fecundity costs of immune activation result not from the commonly accepted resource reallocation hypothesis but probably because resource acquisition is impaired during immune responses. The individuals of any animal population generally vary greatly in their ability to resist infectious disease. This variation arises due to both environmental heterogeneity and genetic diversity. Genetic variation in disease susceptibility has generally been considered to lie in the nuclear genome. Here, for the first time, I explored the influence of mitochondrial genetic (mtDNA) variation on disease susceptibility. I crossed 22 mitochondrial haplotypes onto a single nuclear genome and also studied epistasis interactions between mitochondrial and nuclear genomes (mitonuclear epistasis) by crossing five haplotypes onto five different genetic backgrounds. I found that fly susceptibility to Serratia marcescens was influenced significantly by mtDNA allelic variation. Furthermore, the effect of mitonuclear epistasis on fly susceptibility to S. marcescens was twice as great as the individual effects of either mitochondrial or nuclear genome. However, susceptibility to Beauveria bassiana was not affected by mtDNA allelic variation. These findings suggest the mitochondrial genome may play an important role in host-parasite coevolution. The Mother’s Curse hypothesis suggests that sex-specific selection due to maternal mitochondrial inheritance means that mitochondria are poorly adapted to function in males, resulting in impaired male fitness. Mother’s Curse effects have previously only been studied for two phenotypic traits (sperm-infertility and ageing) and their generality for broader life-history has not been explored. I investigated the impact of mtDNA allelic variation on 10 phenotypic traits and tested whether the patterns of phenotypic variation in males and females conformed to the expectations of the Mother’s Curse hypothesis. I found that seven of the 10 traits were significantly influenced by mtDNA allelic variation. However, there was no evidence that the effects of this variation differed between males and females. I therefore concluded that Mother’s Curse is unlikely to be a general phenomenon, nor to provide a general explanation for sexual dimorphism in life-history traits. Overall, this thesis explored the impacts of immunity costs, mitochondrial genetic variation, mitonuclear epistasis and sex-specific mitochondrial selection on D. melanogaster life-history.

Made available in DSpace on 2017-07-10T18:13:13Z (GMT). No. of bitstreams: 1 Ariane Furtado de Lima.pdf: 1547772 bytes, checksum: 2b187bf1d3cfbc9d8257e7d583283199 (MD5) Previous issue date: 2013-03-25 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The effects of feeding privation on growth of larvae of jundiá Rhamdia voulezi as well as the feeding preference during larval period were evaluated. For this purpose two experiments were conducted which began soon after complete absorption of the yolk sac, the fourth day after hatching (DAH). The feeding privation experiment was performed in 8 treatments consisting of different diets, including the control treatment (CT) in which there was no food supply. The food was provided for the first time in the 4th, 5th, 6th, 7th, 8th, 9th and 10th DAH corresponding to treatments: T4, T5, T6, T7, T8, T9 and T10, respectively. The food consisted of zooplankton and newly hatched artemia. We performed 3 trials of selectivity to analyze the feeding preference throughout the larval period, comprising different larval stages and classes of standard length. In this, the larvae were fed exclusively on zooplankton collected from fish ponds. The results demonstrated that the larvae fed on the fourth to sixth DAH had a significantly higher growth than those fed later, from the seventh DAH. The point of no return was recorded in the same period in the 7th DAH. With respect to feeding selectivity, there were variations in the patterns of prey selection in different days of life analyzed. Initially on the 5th DAH, preflexion stage, larvae strongly selected rotiferas (unidentified) and cladocerans (Diaphanosoma spinulosum, D. brevireme, Moina sp., M. micrura, M. minuta). In the remaining days of life examined, the cladocerans continued to be strongly selected. However on the 8th DAH, flexion stage, they selected less intensely the copepods Argyrodiaptomus azevedoi and Termocyclops decipiens and more strongly A. furcatus, Notodiaptomus spinuliferus and Metacyclops mendocinus at 10 DAH, postflexion stage. The delay of the first feeding drastically affected the growth of the larvae, and that if feeding is started before the point of no return there are chances of recovery. So, it is important to have suitable availability of food, with a variety of type and size so that they can compensate for the morphological limitations of larvae in the early of their development. Concomitant to its growth, the larvae tend to specialize in certain prey items. The size of prey consumed is related to the size of the larvae and the gape size. Initially larvae have a preference for smaller prey, rotifers and cladocerans, and later when they are more developed prefer to feed on larger prey, the copepods. / Neste estudo foram avaliados os efeitos da privação alimentar sobre o crescimento das larvas de jundiá Rhamdia voulezi bem como a preferência alimentar durante o período larval. Para isto foram realizados dois experimentos que tiveram início logo após a absorção completa do saco vitelínico, que ocorreu no 4o dia após a eclosão (DAE). O primeiro experimento de privação alimentar foi realizado com 8 tratamentos constituídos por diferentes regimes alimentares, incluindo o tratamento controle (TC) no qual não houve fornecimento de alimento. O alimento foi fornecido pela primeira vez no 4o, 5o, 6o, 7o, 8o, 9o e 10o DAE, correspondendo aos tratamentos: T4; T5, T6, T7, T8; T9 e T10, respectivamente. A alimentação consistiu de zooplâncton e artêmia recém-eclodida. Para avaliar a preferência alimentar, foram realizados 3 ensaios de seletividade alimentar ao longo de todo o período larval, compreendendo diferentes estágios de desenvolvimento e classes de comprimento padrão. Neste, as larvas foram alimentadas exclusivamente com zooplâncton coletado de tanques de cultivo. Os resultados demonstraram que as larvas de jundiá que receberam alimento do 4o ao 6o DAE tiveram desenvolvimento significativamente maior que aquelas alimentadas mais tardiamente, a partir do 7o DAE. O ponto de não retorno foi registrado neste mesmo período, no 7o DAE. Com relação à seletividade alimentar, houve variações nos padrões de seleção de presas nos diferentes dias de vida analisados. Inicialmente no 5o DAE, estágio de pré-flexâo, as larvas selecionaram fortemente os rotiferas (não identificados) e os cladoceras (Diaphanosoma spinulosum, D. brevireme, Moina sp., M. micrura, M. minuta). Nos demais dias de vida analisados, os cladoceras continuaram a ser fortemente selecionados. Entretanto no 8o DAE, estágio de flexão, selecionaram menos intensamente os copepodas Argyrodiaptomus azevedoi e Termocyclops decipiens e no 10o DAE, estágio de pós-flexão, consumiram especialmente Argyrodiaptomus furcatus, Notodiaptomus spinuliferus e Metacyclops mendocinus. Conclui-se que o retarde da primeira alimentação afeta drasticamente o crescimento das larvas, e que, se a alimentação for iniciada antes do ponto de não retorno há chances de recuperação e sobrevivência larval. Para isto, é importante que haja disponibilidade adequada de alimento, com variedade de tipo e de tamanho de modo que possam compensar as limitações morfológicas das larvas no início do seu desenvolvimento. Concomitante ao seu crescimento, as larvas tendem a se especializar em determinados itens presa, existindo uma seleção de presas tanto pelo tipo como também pelo tamanho, onde o tamanho da presa consumida está relacionado com o tamanho da larva e o tamanho de sua boca. Inicialmente as larvas de jundiá têm preferência por itens presas menores, os rotíferos e cladoceras, posteriormente, quando estão mais desenvolvidas, preferem alimentar-se de presas maiores, os copepodas.

The technological advancement in electrical machinery represents the need to understand the lubricant behaviour in the electrical environment. As shaft voltages are unavoidable in electrical machinery, developing new grease formulations and studying their performance against electric loads is required. The thesis aims to design, develop, install and validate a novel test machine to study grease performance under the influence of electric currents. The system aims to supply damaging electric currents through the bearing, but that was not possible to accomplish due to miscalculations. The test machine is designed to carry out experiments using angular contact bearings. The experiments were performed with four greases, Lithium-complex and polypropylene-based, of high and low base-oil viscosity, respectively. The study compares the frictional moments and self-induced temperatures in the bearings with and without the influence of electric currents. Along with the frictional moment measurements, the lubricant film thickness was estimated using the “electrical-capacitance” method to monitor the status of the lubricant inside the bearing in real-time. The test machine is limited to speeds up to 3600 rpm, and the project lays out a foundation for research in film thickness estimation in rolling element bearings. As a part of the thesis, new slip rings were specified to facilitate the test machine to perform studies at higher speeds up to (17000rpm). / De tekniska framstegen inom elektriska maskiner representerar behovet av att förstå smörjmedlets beteende i den elektriska miljön. Eftersom axelspänningar är oundvikliga i elektriska maskiner krävs utveckling av nya fettformuleringar och studier av deras prestanda mot elektriska belastningar. Avhandlingen syftar till att designa, utveckla, installera och validera en ny testmaskin för att studera fettprestanda under påverkan av elektriska strömmar. Systemet syftar till att leverera skadliga elektriska strömmar genom lagret, men det var inte möjligt att åstadkomma på grund av felberäkningar. Testmaskinen är designad för att utföra experiment med vinkelkontaktlager. Experimenten utfördes med fyra fetter, litiumkomplex- och polypropenbaserade, med hög respektive låg basoljeviskositet. Studien jämför friktionsmomenten och självinducerade temperaturer i lagren med och utan påverkan av elektriska strömmar. Tillsammans med mätningarna av friktionsmomentet uppskattades smörjmedelsfilmtjockleken med hjälp av metoden "elektrisk kapacitans" för att övervaka statusen för smörjmedlet inuti lagret i realtid. Testmaskinen är begränsad till hastigheter upp till 3600 rpm, och projektet lägger en grund för forskning inom filmtjockleksuppskattning i rullager. Som en del av avhandlingen specificerades nya släpringar för att underlätta för testmaskinen att utföra studier vid högre hastigheter upp till (17000rpm).

No / Historical evidence documents mass migration from Ireland to London during the period of the Great Irish Famine of 1845-52. The rural Irish were reliant on a restricted diet based on potatoes but maize, a C(4) plant, was imported from the United States of America in 1846-47 to mitigate against Famine. In London, Irish migrants joined a population with a more varied diet. To investigate and characterize their diet, carbon and nitrogen isotope ratios were obtained from bone collagen of 119 and hair keratin of six individuals from Lukin Street cemetery, Tower Hamlets (1843-54), and bone collagen of 20 individuals from the cemetery at Kilkenny Union Workhouse in Ireland (1847-51). A comparison of the results with other contemporaneous English populations suggests that Londoners may have elevated delta(15) N compared with their contemporaries in other cities. In comparison, the Irish group have lower delta(15) N. Hair analysis combined with bone collagen allows the reconstruction of perimortem dietary changes. Three children aged 5-15 years from Kilkenny have bone collagen delta(13) C values that indicate consumption of maize (C(4)). As maize was only imported into Ireland in quantity from late 1846 and 1847, these results demonstrate relatively rapid bone collagen turnover in children and highlight the importance of age-related bone turnover rates, and the impact the age of the individual can have on studies of short-term dietary change or recent migration. Stable light isotope data in this study are consistent with the epigraphic and documentary evidence for the presence of migrants within the London cemetery.

Using a high throughput closed respirometry method to measure oxygen consumption, I determined metabolic rates in asexual and sexual Schmidtea mediterranea and Girardia dorotocephala, as a function of temperature, taxon, stressors, reproductive mode, age, regeneration, and specific dynamic action. This study has shown that oxygen consumption can reliably be measured in planaria using optode closed respirometry, and also provided a reliable method for measuring wet mass in planaria, which has been a challenge to researchers in the past. This research revealed that oxygen consumption in S. mediterranea is 1.5-2.1X greater in the sexual strain over the asexual strain at 13-18°C. Within the sexual strain, oxygen consumption is 1.5 -2.2X greater in sexually mature adults over the sexually immature groups (hatchlings, juveniles, and regenerating sexuals). Furthermore, I was able to quantify differences in sexual morphology between these groups exhibiting significant differences in oxygen consumption. The results of this research supports a theory of higher metabolic costs with sexual maturity in S. mediterranea. Therefore, this study has established sexual and asexual S. mediterranea as simple, yet attractive models for investigating energetic costs between sexual and asexual phenotypes. This research also provided quantitative values for specific dynamic action in planaria, with a maximum increase in oxygen consumption of 160% induced by feeding, as well as metabolic relationships in planaria involving temperature, age, and regeneration. These values establish planaria as one of the simplest animal models in which common metabolic patterns, such as SDA and poikilothermic temperature sensitivity, have been demonstrated. Therefore, this research has contributed to the overall knowledge of the basic physiology in this animal, providing the framework for future metabolic studies in planaria involving environmental factors, reproduction, regeneration, development, and aging. Information from this study may supplement interpretation and understanding of modern cellular, molecular, and genomic studies in planaria.

The narratives about the postexilic Judean community are an ancient biblical account of the socio-economic and political experiences of the Judeans when they were finally restored back to Judah from Babylonian captivity. Although the Judean restoration was celebrated when they were restored by King Cyrus’ decree, real freedom did not prevail in the Persian province of Yehud; corruption, usury, greed, oppression, enslavement and loss of property impacted negatively on the poor. The leadership expropriated from poor citizens land, vineyards, and houses in exchange for food. In addition, the governors also charged heavy interest on money borrowed by poor members of society. Parents and their children were subjected to enslavement. In response to these corrupt practices, Nehemiah challenged the leadership to stop oppressing the poor. Nehemiah went further to provide food to the starving Judeans and other people from surrounding nations which served as a stimulus to strive towards alleviating poverty and starvation among communities. By employing an approach known as hermeneutics of appropriation, this thesis appropriates the experience of the postexilic Judean community to the post-independence Zimbabwean context. Between the years 1999 and 2008 many people lost their lives due to unemployment and lack of income, shelter, nutrition, and access to health-care facilities because of the economic meltdown following the controversial fast-track land reform programme in Zimbabwe. The majority of people are still experiencing the negative impact of the land reform as people strive to make a living in the absence of jobs and income scarcity. Corruption by the leadership has continued to further exacerbate starvation among the poor until today.This study attempts to employ the biblical Nehemiah’s social justice reforms (Neh 5) to challenge the Zimbabwean leadership to focus on rebuilding the country which was ravaged by a decade of both political and socio-economic crises. Lessons drawn from Nehemiah would be used to stimulate the leadership in the Zimbabwean government and members of society at large, to strive towards helping the poor and alleviating poverty. / Old Testament & Ancient Near Eastern Studies / D. Litt. et Phil. (Biblical Studies)