Dissertations / Theses on the topic 'Aril functions'

This study investigates the ecology of an arid zone calcrete through an interdisciplinary design composed of multivariate analyses, hydrology, isotopic ecology and genetics. Our results indicate that the biotic community (microbes and stygofauna) is closely linked to the hydrodynamic conditions influenced by different rainfall regimes. The inflow of rainfall triggered shifts towards more deterministic dynamics, revealing a complex web of interactions. This investigation provides crucial untangling of the ecological dynamics regulating biotic communities in groundwaters.

The Aryl Hydrocarbon Receptor (AhR) and the Aryl Hydrocarbon Nuclear Translocator (ARNT) play a role in mediating transcriptional responses to environmental pollutants, including the highly toxic compound 2,3,7,8-tetrachlorodibenzo -p-dioxin (TCDD) but also endogenous physiological ligands. More recent studies have also indicated that the AhR plays a role in the immune system notably in effector Th17 cells where it seems to be critical for the production of the IL-22 cytokine. It is known that AhR ligands such as dioxins can suppress CD8 T cell mediated antiviral immune responses but it is not known whether this reflects a direct role of the AhR in CD8 T cells.Accordingly, one objective of the present study was to explore AhR and ARNT expression in CD8 T cells. The initial strategy was to probe AhR and ARNT expression by western blot analysis. A second approach was to develop a mouse model that would fate mark single lymphocytes that have activated AhR signaling pathways. A third strategy was to examine the impact of deletion of AhR and ARNT on CD8 T-cell function.The data show that AhR and ARNT expression in CD8 T cells is limited to immune activated effector cells and these transcription factors are not expressed in naïve CD8 T cells. There are only low levels of AhR complexes in conventional CD8 positive cytotoxic T cells. To investigate AhR function at the single cell level we developed a mouse model to fate mark cells that have activated AhR signaling. In this model a mouse expressing Cre recombinase ‘knocked in’ to the CYP1A locus (CYP1A1Cre+/-) was backcrossed to the R26REYFP reporter mouse. In R26REYFP mice, a gene encoding EYFP is knocked into the ubiquitously expressed Rosa26 locus preceded by a loxP flanked stop sequence. CYP1A1 expression is controlled by AhR/ARNT complexes and the concept of our model was that cells that express AhR and ARNT complexes and are triggered with AhR ligands will express Cre recombinase and delete the loxP flanked stop sequence in the R26REYFP reporter locus and hence begin to express YFP.In vitro experiments demonstrated the validity of this AhR reporter model. The in vitro data reveal that expression of functional AhR/ARNT complexes occurs during Th17 and Tc17 cell differentiation but only a very low frequency of cytotoxic T cells activates the AhR. In vivo data found no evidence for AhR activation during T cell development in the thymus but show strong evidence for activation of AhR/ARNT signaling in innate lymphocytes in the gut. The ARNT transcription factor is highly expressed in cytotoxic T cells. These cells do not express functional AhR complexes, yet we considered that ARNT might play a role in CD8 T cell biology because of its ability to dimerise with the transcription factor Hif-1a. Our studies of T cells lacking ARNT expression revealed that in CD4 T cells the ARNT transcription factor regulates IL-17 and IL-22 production. In CD8 T cells we discovered that Hif-1a/ARNT signaling controls glycolysis in immune activated cells by sustaining expression of glucose transporters and multiple rate limiting glycolytic enzymes. ARNT was not required for CD8 T cell proliferation but was required for immune activated CD8 T cells to normally differentiate to express perforin and granzymes and to acquire the migratory program of effector T cells. Importantly, we discovered that Hif-1a/ARNT signaling is regulated by mTOR (mammalian target of rapamycin) thus revealing a fundamental mechanism linking nutrient sensing and transcriptional control of CD8 T-cell differentiation.

Australia’s rangelands encompass approximately 80% of the continent and generate significant wealth through a range of industries. The rangelands comprise four major ecosystem types, these are: grasslands, shrublands, woodlands and savanna. The ecological legacy of early pastoral development in most of Australia‟s semi-arid shrublands is largely one of degradation and desertification (Wilcox and McKinnon, 1974; Curry et al. 1994; McKeon et al. 2004; Mabbutt et al. 1963; Pringle and Tinley, 2001). Since the 1980‟s, there has been a slow and general shift by the pastoral industry towards sustainable stocking rates (Watson et al. 2007; Pringle and Tinley, 2001).To implement grazing systems that better align stocking rates with carrying capacity in the semi-arid shrublands, pastoralists require a much more advanced understanding of patch patterning and ecological processes at a paddock scale. This understanding of theory could improve the management decisions made by pastoralists and other land managers (e.g. mining environmental officers, carbon offset developers, conservation park rangers, Indigenous communities) and assist them in their immediate challenge of cost-effective rehabilitation of degraded areas. Landscape function theory was largely developed for this purpose.Landscape function theory was developed as a way to assess and interpret patch patterns and ecological processes that occur at a range of spatial scales (Ludwig et al. 1997). Landscape function theory is used to explain the concept of „functional heterogeneity‟ which is an information-rich phenomenon that has enabled the development of cross-scale metrics. Landscape function theory is based on four primary principles, these are: 1. Patchiness can be characterised by patch size, orientation, spacing and soil surface condition. 2. Natural landscapes have a characteristic spatial self-organisation, often expressed as patchiness. 3. Deviations from the „characteristics‟ or „natural‟ patchiness are seen as degrees of dysfunctionality and there is a long continuum from highly functional to highly dysfunctional patches. 4. Restoration or replacement of missing or ineffective processes in the landscape will improve soil surface conditions and soil habitat quality.Landscape function theory and the associated landscape function analysis (LFA) methodology have become an accepted standard for the ecological assessment of rangeland environments. However, there have been a limited number of studies in Australia that have thoroughly examined the four principles that underpin the landscape function theory. Further interrogation of the principles that underpin the theory has the potential to enhance its utility and validate its assumptions. Therefore, the aim of this thesis was to test the four principles of landscape function theory in a semi-arid shrubland environment.The overarching hypothesis of this thesis was that clear spatial patch patterns occur at a range of scales within the case study paddocks and these patterns determine the ecological functionality and resilience of the area. Specifically, I sought to find evidence of distinct patch-interpatch patterns and associations at a range of scales in the lower Murchison region of Western Australia (WA) and examined the impact that grazing and seasonal conditions can have on this natural patchiness. The study involved four components: 1. Empirical quantification of patch-scale heterogeneity and investigation into the existence of a gradient of functionality at a patch-scale. 2. Measurement of patch patterning at a paddock scale and an evaluation of sequences and associations of patch-interpatches in the context of their contribution to landscape functionality. 3. Investigation of the impact of grazing and seasonal conditions on perennial grass populations and the potential impacts of this on patch patterning and ecological processes. 4. Investigation of livestock grazing behaviour and its implications for patch patterning and ecological processes.Significant variation was detected (P<0.05) between the physical and chemical properties of 11 different patch-interpatch subclasses. Heterogeneity within individual patches was also significant (P<0.05) and the greatest variation occurred within ecologically stable, high-order patches. Higher-order patch-interpatch subclasses were highly functional and when compared to the lower-order patch-interpatch subclasses, the former had: higher soil respiration rates (>45%) (P<0.05), this indicates these subclasses are more biologically active; more than twice the number of perennial plant species within the patch (P<0.05); higher soil infiltration rates (>70% more rapid) (P<0.05), this indicates these subclasses can capture more rainfall and surface runoff when it occurs; and five times more carbon and nitrogen. A gradient of highly functional patches and highly dysfunctional interpatches was identified.Distinct patch patterning between different land-types was found. The granitic shrubland land-type had a much greater proportion of the lower-order resource-shedding interpatch subclass (>85% of the area) compared to the other land-types. In contrast, Acacia sandplains had a higher proportion of the ecologically functional patches compared to granitic shrublands. Depending on the land-type, it was concluded that a functional ecosystem will generally have balanced proportions of particular patch-interpatch subclasses as this is likely to lead to the efficient capture and cycling of water and nutrients. In contrast, a degraded ecosystem will have higher proportions of ecologically dysfunctional patch-interpatch subclasses. A number of significant spatial associations and repeating sequences of individual patch-interpatch subclasses were found to occur in the study area. In the case study paddocks, distance-from-water did not have any significant effect on the relative proportions of the different patch-interpatch subclasses.Native perennial grasses support perennial shrub patches in maintaining ecological stability and landscape processes in semi-arid shrublands. Perennial grasses were monitored over a 12 month period to determine whether summer rest from Merino sheep grazing had an impact on perennial grass populations. The change in the number of perennial grasses over the 12 month period was variable ranging from a 36.7% increase to mortality rates as high as 80.2%. There was evidence to suggest that the grasses in the exclosure treatments (i.e. no grazing) may have been conditioned by previous grazing events in such a way that made them highly susceptible to extended periods of moisture stress. Land-type, distance-from-water and stocking rate did not have a significant impact on the change in the number of perennial grasses over the 12 month period. Resting perennial grasses during the summer may be of benefit; however, given the high mortality rates in most of the paddocks, it was clear that seasonal conditions had a substantial overriding influence on the outcome.Five major factors influenced sheep grazing behaviour in the study paddock; these include: land-type, greenness cover, time of day, air temperature and distance-from-water. The GPS-collared sheep demonstrated a clear grazing preference for the higher value land-types (i.e. alluvial plains and hardpan washplains). The results also indicated that the sheep were selectively grazing areas with high greenness cover (as expressed by Normalised Difference Vegetation Index [NDVI]). The results highlight the importance of understanding the selective grazing characteristics of Merino sheep when designing paddock layouts and developing management plans. This is because repetitive, selective grazing of high-value land-types has the potential to modify the natural patch patterning and ecological processes.This study found empirical evidence which substantiates landscape function theory and concludes that it has significant application at a range of spatial scales in the semi-arid shrublands. The results explain why landscape function theory is the current standard for the assessment and interpretation of rangeland environments in Australia. Landscape function theory is the result of an evolutionary synthesis of earlier work, and it continues to be progressively refined as our knowledge of the complex patterns and ecological processes of the rangelands is improved.Based on the findings of this study, I consider that there are three areas of further inquiry which could assist land managers to practically apply landscape function theory and contribute towards the restoration of degraded Australian rangelands, these are: determination of the „functional‟ composition of patch-interpatches subclasses for a range of land-types in the Australian rangelands that could be used as benchmarks for land managers; further empirical quantification of the ecological processes that drive landscape function to assist in simulation modeling and the estimation of cost / benefit of rehabilitation efforts; and the potential role that grazing management can play in the restoration of dysfunctional patch-interpatch patterns and ecological processes in the semi-arid shrublands.

Novel, highly functional rod-like copolymers have been synthesized by alternating copolymerization of N, N, Nâ , Nâ -tetraalkyl-4, 4â -diaminostilbenes (TDAS) with maleic anhydride. Dynamic light scattering, 2H solid state NMR and persistence length measurement reveal high chain rigidity of the polymer backbone. Double quantum heteronuclear local field solid state NMR spectroscopy (2Q-HLF Solid State NMR) has been employed to investigate the chain structure of 13C labelled copolymer. The torsional angle of the H-13C-13C-H part of the anhydride ring was zero degrees, indicating an all cis configuration of the H-13C-13C-H moiety of the anhydride ring. Rod-coil block copolymers containing rigid polyampholyte blocks were designed and synthesized by addition-fragmentation chain transfer (RAFT) copolymerization. The rigid polyampholytes blocks were formed by hydrolysis of alternating copolymers and the flexible coil block consists of poly(oligo(ethylene glycol) methacrylate). The rod-coil block copolymers form polyion complex (PIC) aggregates even when the polyampholyte blocks are charge imbalanced. The aggregates did not dissociate upon the addition of high concentrations of NaCl unlike the dissociation of flexible polyampholytes in NaCl solution. These unique solution properties are induced by â like-charge attractions' of the rigid polyampholytic alternating copolymer chains. An example, of what is birefringent to be a novel class of material, has been prepared which enables the control of the birefringence of a polymer film by controlling the rotation of aromatic groups pendant to the polymer backbone. A linear rigid bisphenol monomer, 4,4â -dihydroxyterphenyl (DHTP), has been incorporated into poly(aryl ether sulfone)s (PAES) in a study to impart crystallization to these amorphous polymers. Three bisphenols, 4, 4â -isopropylidenediphenol, 4, 4â -(hexafluoroisopropylidene)diphenol and 4,4â -dihydroxybiphenyl have been copolymerized with DHTP and dichlorodiphenylsulfone. Only the segmented polysulfone containing 50% BP and 50% DHTP was semi-crystalline. This PAES had a melting temperature (Tm) 320oC in the first heating cycle of a DSC measurement and the presence of crystallites was confirmed by wide angle X-ray diffraction (WAXS).<br>Ph. D.

Persistent organic pollutants (POPs) and adipose tissue hypoxia have been shown to independently affect adipocyte functions. The goals of this study were to (1) determine the effect of PCB-77, PCB-153, and DDE on the differentiation of human preadipocytes, and (2) investigate the cross-talk between PCB-77 and hypoxia in differentiated human adipocytes. First, human preadipocytes were exposed to PCB-77, PCB-153, or DDE during the entire 14-day differentiation period. We found no effect of low POP levels on lipid accumulation. Second, differentiated human adipocytes were exposed to a combination of PCB-77 and hypoxia. We demonstrated gene-specific cross-talk between PCB-77 and hypoxia, showing an additive effect of PCB-77 on VEGF, MCP-1, and adiponectin, as well as an inhibition of PCB-77-induced expression of CYP1A1 by hypoxia. This work has expanded our understanding of the role of POPs and hypoxia in differentiated human adipocytes.

The aryl hydrocarbon receptor (AhR) is a cytosolic ligand-activated transcription factor whose toxicity and carcinogenesis is mediated through various polyaromatic hydrocarbons and other environmental pollutants. The role of AhR in carcinogenesis is an area of concern due its altered levels in various tumors. AhR binds structurally diverse ligands and may elicit different responses upon ligand binding. The crystal structure of mouse AhR PAS-A domain was already obtained due to the robustness of mouse AhR in comparison to human. There is a possibility of overexpressing mouse AhR ligand binding domain in its soluble and functional form, which could be used to perform ligand binding studies. This forms the aim of this thesis. Mouse AhR ligand binding domain was constructed as mAhR aa211-384, which was purified under native conditions with the use of 6 histidine tag but soluble overexpression was not possible. Thus a solubility enhancing tag called maltose binding protein (MBP) was used for purification of mAhR aa211-384 under native conditions, which still did not yield soluble overexpression. The strategy was modified to solubilize the protein by denaturation with the use of 8M Urea, which solubilized the protein but included an issue of protein binding to column. Subsequent use of an even stronger denaturant, 6M guanidine hydrochloride, solubilized most of the protein and purified mAhR aa211-384 in huge amount. Successful refolding of mAhR aa211-384 with the help of MBP was made possible by gradual reduction of denaturant in the presence of arginine, but 6 histidine tag failed to refold the protein. The refolded protein was tested for its secondary structure by circular dichroism. Thus, mAhR aa211-384 was solubilized and purified under denaturing conditions with the help of both 6 histidine and MBP, however efficient refolding of mAhR aa211-384 was only possible with the help of MBP but not 6 histidine. The MBP-refolded mAhR aa211-384 stayed in solution even after the removal of 0.1 M arginine, thus confirming the effectiveness of MBP in protein refolding in comparison to 6 histidine tag.

Thesis (MSc)--Stellenbosch University, 2004.<br>ENGLISH ABSTRACT: Bush encroachment in savannas leads to reduced diversity, productivity and profitability of rangelands. This holds important implications for the livestock and eco-tourism industries, as well as for subsistence ranchers in the South African semi-arid savannas, who depend on this vegetation type for economic and livelihood purposes. Soil moisture, nutrients, rue and herbivory are generally regarded as the principal factors determining vegetation structure and function within savannas. The factors and processes involved in the determination of the tree:grass ratio within savannas are, however, not clearly understood. We investigated the role of soil type and management strategy (cattle, game and communal grazing) in the determination of the presence and distribution of plant species in general, and on the presence and distribution of the encroaching tree species, Acacia mellifera, specifically. Both shortand long-term trends were investigated. The study area, the Kimberley Triangle, (Northern Cape Province, South Africa), was ideal for this kind of study because it has different management strategies practised on several soil types, and bush encroachment is a widespread phenomenon. Contrary to the belief that heavy livestock grazing is the main cause of increases in the tree:grass ratio, we found that soil type, through its effects on plant growth and on the presence and availability of soil moisture and nutrients, is more important in determining vegetation composition than management strategy. It was found that the various types of grazing management mainly influenced vegetation structure and function by affecting the competitive interactions between Ns-fixing woody species and non-Ns-fixing grasses. Of the soil factors affecting vegetation composition, soil texture was a good indicator of the physical conditions for plant growth in an area, and also of the presence and availability of soil moisture and nutrients. We found that sand and clay soils are relatively resistant to bush encroachment as compared to loamy-sand and -clay mixes. This is because woody growth is impaired in the first-mentioned habitats by soil texture, soil moisture regimes and heavy utilisation. In soils with combinations of loam, sand and clay, soil texture and moisture are not limiting to woody growth and if the repressive competitive effect of grasses on woody vegetation is removed, opportunities are created for recruitment of woody species and encroachment. Additionally, rockiness increases soil moisture infiltration. In the study area, woody species, and specifically A. mellifera, are associated with these areas. We suggest that in the study area, rocky areas are naturally encroached. This is in agreement with the patchdynamic approach to savanna vegetation dynamics. Because soil moisture is such an important factor in the determination of the tree:grass ratio in the study area, we further suggest that in above-average rainfall years, when soil moisture conditions are optimal for woody seed germination, establishment and growth, heavy grazing should be avoided, as it would provide the opportunity for encroachment. Keywords: Bush encroachment; N2-fixing species; game, cattle, communal grazing; soil texture; soil moisture; soil nutrients; Acacia mellifera; tree-grass competition.<br>AFRIKAANSE OPSOMMING: Bosindringing in savanna gebiede het verlaagde diversiteit, produktiwiteit en winsgewendheid van natuurlike weivelde tot gevolg. Behalwe dat dit die Suid-Afrikaanse vee- en ekotoerisme bedrywe raak, is verskeie bestaansboerderye afhanklik van die plantegroei-tipe vir oorlewing. Grondvog, grondvoedingstowwe, vuur en beweiding word algemeen aanvaar as die belangrikste faktore wat die struktuur en funksie van savannas bepaal. Daar is egter nog nie duidelikheid oor die prosesse wat betrokke is in die bepaling van die boom-gras verhouding in savannas nie. In dié studie het ons ondersoek ingestel na die invloed van grond tipe en beweidingstrategieë (beweiding deur beeste, wild, of kommunale beweiding) op die algemene verspreiding van verskillende plant spesies, en ook op die van die indringer spesie, Acacia mellifera. Beide kort- en lang-termyn patrone is ondersoek. Die studiegebied, die Kimberley Driehoek in die Noord-Kaap, Suid-Afrika, was ideaal vir so 'n ondersoek omdat verskillende beweiding strategieë op verskeie grond-tipes beoefen word maar bosindringing steeds 'n algemene verskynsel in die gebied is. Ons bevinding was dat, ten spyte van die feit dat daar oor die algemeen geglo word dat swaar beweiding die hoof oorsaak van bosindringing is, grond-tipe belangriker is in die bepaling van die spesie-samestelling van 'n gebied. Dit is as gevolg van die feit dat grond-tipe die groei van plante beïnvloed deur die teenwoordigheid en beskikbaarheid van grondvog en -nutriënte te bepaal. Die verskillende beweidingstrategieë beïnvloed meerendeels die kompetatiewe interaksies tussen N2-bindende hout-agtige spesies teenoor nie-Nj-bindende gras-agtige spesies. Grond-tekstuur was 'n goeie aanduiding van die algemene toestande vir plantegroei en ook van die teenwoordigheid en beskikbaarheid van grondvog en -nutriënte. Ons het bevind dat sand en klei grond, relatief tot leem, sand en klei kombinasies, weerstandbiedend is teen bosindringing as gevolg van die tekstuur, water-regimes en swaar beweidings vlakke wat op die grond-tipes voorkom. Omdat grond-tekstuur en grondvog nie beperkend is op die leem-, sand- en klei-grond kombinasies nie, kan bosindringing maklik hier voorkom as die onderdrukkende effek wat grasse op houtagtige plantegroei het, deur swaar beweiding verwyder word. A. mellifera is ook oor die algemeen met klipperige gebiede geassosieer omdat klipperigheid lei tot verhoogde infiltrasie van grondvog. In die studie-gebied is klipperige areas dan ook van nature ingedring deur A. mellifera. Dit stem ooreen met die siening dat savannas bestaan uit "laslappe" van verskillende plantegroei (patch-dynamic approach). Dit was duidelik dat grondvog 'n belangrike bepalende faktor is in die bepaling van die boom-gras verhouding in die studiegebied. Ons stel dus voor dat in bo-gemiddelde reënval jare, swaar beweiding vermy moet word, omdat houtagtige saailinge gedurende die tydperke maklik kan ontkiem en vestig juis omdat grondvog dan nie beperkend is nie. Sleutelwoorde: Bosindringing; N2-bindende spesies; bees, wild, kommunale beweiding; grond tekstuur; grond-vog; grond-nutriënte; Acacia mellifera; boom-gras kompetisie.

Thesis (MScConEcol (Conservation Ecology and Entomology))--University of Stellenbosch, 2011.<br>ENGLISH ABSTRACT: I evaluated the impact of Prosopis invasion and clearing on ecological structure, function and agricultural productivity in heavily grazed Nama Karoo rangeland on two sheep farms near the town of Beaufort West in the Western Cape Province of South Africa. My aims were to (1) determine the effects of invasion and clearing on rangeland vegetation composition, diversity (alien and indigenous species richness) and structure (alien and indigenous species cover), soil vegetation cover (plant canopy and basal cover) and agricultural productivity (grazing capacity), (2) describe the vegetation processes that underlay the invasion and clearing impacts and (3) evaluate the success of clearing in facilitating unaided restoration of ecological structure, function and agricultural productivity in formerly invaded rangeland. I hypothesised that invasion would significantly change rangeland vegetation composition and structure, leading to greater alien species richness and cover and lower indigenous species richness and cover while clearing would lead to lower alien species diversity and cover and greater indigenous species richness and cover. In addition I hypothesized that invasion would reduce rangeland plant canopy and basal cover and grazing capacity while clearing would substantially increase them. Finally I predicted that vegetation composition, alien and indigenous species cover and richness, plant canopy and basal cover and grazing capacity would revert to pre-invasion status and levels within four to six years of clearing. My results suggest that in heavily grazed Nama Karoo rangeland Prosopis invasion (~15 percent canopy cover) and clearing can significantly change rangeland vegetation composition, with invasion leading to greater alien species cover and lower indigenous species richness, while clearing leads to lower alien species richness and cover and greater indigenous species richness and cover. However invasion seems to have no effect on alien species richness and overall indigenous species cover. Clearing appears to facilitate the spontaneous restoration of alien species cover and indigenous species richness within four to six years but not species composition, alien species richness and indigenous species cover. In addition my results also indicate that Prosopis invasion can lower rangeland plant canopy and basal cover and grazing capacity while clearing, even under heavy grazing, can substantially raise them. Clearing however does not seem to facilitate the restoration of rangeland plant canopy and basal cover and grazing capacity to pre-invasion levels within four to six years after clearing.<br>AFRIKAANSE OPSOMMING: Ek het die impak van Prosopis indringing en verwydering van indringers op ekologiese struktuur, funksie en landbou produktiwiteit in ‘n swaar beweide Nama Karoo gebied op twee skaapplase naby Beaufort-Wes in die Wes-Kaap provinsie van Suid-Afrika geëvalueer. My doelwitte was om (1) te bepaal wat die gevolge van die indringing en verwydering van indringers op die natuurlike plantegroei samestelling, diversiteit (uitheemse en inheemse spesiesrykheid) en struktuur (uitheemse en inheemse spesies bedekking) sal wees, sowel as die effek op plantegroei bedekking (kroon en basalebedekking) en landbou produktiwiteit (weidingkapasiteit), (2) die plantegroei prosesse te beskryf wat onderliggend deur die impakte van indringing en verwydering van indringers veroorsaak word, en (3) die sukses van die verwydering van indringers te evalueer deur die fasilitering van blote restorasie van ekologiese struktuur en funksie en landbou produktiwiteit in voorheen ingedringde gebiede. My hipotese is dat indringing ‘n aansienlike verandering in natuurlike plantegroeisamestelling en struktuur sal veroorsaak, wat sal lei tot groter uitheemse spesiesrykheid en bedekking met minder inheemse spesiesrykheid en bedekking, terwyl die verwydering van indringers sou lei tot minder uitheemse spesie diversiteit en bedekking met 'n groter inheemse spesiesrykheid en bedekking. Verder vermoed ek dat indringing die natuurlike kroon- en basalebedekking en weidingkapasiteit sal verminder, terwyl die verwydering van indringers dit aansienlik sal verhoog. Ten slotte voorspel ek dat plantegroei samestelling, uitheemse en inheemse spesiesbedekking en -rykheid, kroon- en basalebedekking en weidingkapasiteit sou terugkeer na voor-indringing status en vlakke binne vier tot ses jaar na die verwydering van indringers. My resultate daarop dat die indringing van Prosopis (~ 15 persent kroonbedekking) en die verwydering van indringers in swaar beweide Nama Karoo gebiede ‘n aansienlike verandering in die gebied se natuurlike plantegroei samestelling toon, waar indringing gelei het tot groter uitheemse spesiesbedekking en minder inheemse spesiesrykheid, terwyl die verwydering van indringers lei tot minder uitheemse spesiesrykheid en groter inheemse spesiesrykheid en - bedekking. Dit lyk egter of indringing geen effek op uitheemse spesiesrykheid en algehele inheemse spesiesbedekking het nie. Die verwydering van indringers blyk om die spontane herstel van indringerbedekking en inheemse spesiesrykheid binne vier tot ses jaar te fasiliteer, maar nie spesiesamestelling, uitheemse spesiesrykheid of inheemse spesiesbedekking nie. Benewens dui my resultate ook aan dat Prosopis indringing die natuurlike kroon- en basalebedekking sowel as weidingskapasiteit verlaag, terwyl die verwydering van indringers, selfs onder swaar beweiding, die bedekking aansienlik kan verhoog. Verwydering van indringers lyk egter nie asof dit die herstel van die gebied se natuurlike kroon- en basalebedekking en weidingkapasiteit na voor-indringing vlakke toe kan fasiliteer binne vier tot ses jaar na die verwydering van indringers nie.

Mestrado em Economia Monetária e Financeira<br>O objetivo desta dissertação de mestrado é estudar a relação de longo prazo entre a distribuição funcional e interpessoal do rendimento e o crescimento do PIB em Portugal para o período entre 1985 e 2016. O modelo econométrico escolhido é ARDL-bounds test. Há evidências de que a transferência de rendimento do fator capital para o fator trabalho tem efeitos positivos no crescimento de longo prazo de Portugal. O aumento nos rendimentos de topo (TOP 0,01%) também tem efeitos positivos, mas menores no crescimento de longo prazo. As razões invocadas para o aumento do peso do profit share são essencialmente as mesmas que o aumento dos rendimentos de topo. Conclui-se que os governos devem concentrar-se em medidas para aumentar o wage share e, consequentemente, propiciarão a aceleração do crescimento económico de longo prazo.<br>The objective of this master's thesis is to study the long-term relationship between the interpersonal and functional distribution of income and GDP growth in Portugal for the period between 1985 and 2016.The econometric model chosen is the ARDL-bounds test.There is evidence that the transfer of income from the capital to the labor factor has positive effects on the long term growth of Portugal. The increase in top yields (TOP 0,01%) also have positive but smaller effects.As the reasons given for the increase in the weight of profit share are essentially the same as the increase in top income, it is concluded that governments should be focused on measures to increase wage share and consequently reduce income inequality, having positive long-term economic growth effects.<br>info:eu-repo/semantics/publishedVersion

Links between species and the effect they have on ecosystem function is becoming increasingly recognised. Examples of such links include the complex, often multi-staged process of animal mediated seed dispersal, seed-caching by mammals and the tripartite relationship that occurs between many fungus-eating (mycophageous) mammal species, mycorrhizal fungi and woody plants. In this thesis, the role a small omnivorous marsupial, Bettongia penicillata ogilbyi (woylie), plays in ecosystem function, using its interaction with Santalum spicatum (Western Australian sandalwood) as a model, was examined. The study was conducted in a semi-arid open wandoo (Eucalyptus wandoo) woodland, in Western Australia. Dryandra Woodland, (32°48'8, l16°54'E) 160 km southeast of Perth, is one of the largest and most diverse remnants supporting over 800 native plant species and 24 mammal species, seven of which are threatened. Dryandra Woodland experiences a Mediterranean climate with warm to hot, dry summers and mild, wet winters. Bettongia penicillata Grey 1837 is a small, nocturnal marsupial within the family Potoroidae. Since European settlement, the distribution and numbers of woylies have decreased dramatically. Factors attributed to this decline include habitat loss, the introduction of feral predators such as the cat (Felis catus), the European red fox (Vulpes vulpes) and competing herbivores. From its original distribution across the south-western third of the continent, only three remnant natural populations remain in the south-west of Western Australia at Perup Nature Reserve, Tutanning Nature Reserve and Dryandra Woodland representing a reduction in range of approximately 97%. Santalum spicatum (R. Br) DC (Western Australian sandalwood), family Santalaceae, is a small, hemiparasitic tree which has virtually disappeared from the 300-600 mm rainfall zone due to widespread clearing of natural woodland and excessive unregulated harvesting. Furthermore, it has been suggested that seed dispersal is limited in areas where woylies have become extinct. Four broad objectives were addressed in this thesis: 1. To determine the population and dietary requirements of woylies in Dryandra Woodland 2. To determine the impact woylies have on the regeneration of sandalwood, by measuring recruitment of sandalwood in an area where woylies are present compared with an area where they are absent 3. To examine, in detail, seed dispersal and seed caching behaviour in the woylie by radiolabelling seeds with scandium 46. This will include the types of seeds cached, how caches are located, whether secondary or tertiary caching occurs, seed preference, germination rate from caches and seedling predation 4. To develop a rationale for woylie conservation and reintroduction based on an understanding on the woylie's role in ecosystem function and species' coexistence. Two experimental sites, with both woylies and sandalwood, and a control site, with sandalwood but no woylies were used in this study. Site A is outside the main block of Dryandra Woodland, 1.65 km from the main entrance to the Woodland. This site lies parallel to the main Wandering-Narrogin road and across from farmland situated next to woodland. The sandalwood was planted in the 1950s and has numerous mature sandalwood trees, saplings and seedlings. Site B is within the woodland, 3.2 km from the Dryandra village. Site B was planted in the late 1970s to early 1980s and has very few new sandalwood recruits and the few seedlings that did occur were found on soil mounds along the fenced area parallel to and across from a dirt road. The control site, with sandalwood but no woylies was at the Wickepen Water Reserve, 40 km south-east of Dryandra Woodland. This site had many mature sandalwood trees but very little recruitment growing away from the parent crown. Trapping sessions, lasting four nights per experimental site, were commenced in May 2002 and repeated at regular intervals until December 2005 giving a total of 1300 trap nights at site A and 1400 at site B. The 2005 trapping sessions were carried out four times a year to cover the seasons for dietary analysis for Bettongia penicillata ogilbyi (woylie) and Trichosurus vulpecula (brushtail possum). Because the number of trapped and re-trapped woylies were so low, the Jolly-Seber method, used to estimate possum numbers, could not be used to estimate woylie populations at either site. Instead, the minimum number of animals known to be alive (KTBA) was calculated by counting the number of times an individual woylie was trapped over at least three sessions. Findings from this study indicate that woylie numbers are declining in Dryandra. Site A had a very low number of woylies KTBA with only two females trapped once in June 2002 and one individual male, trapped intermittently until February 2004. Subsequent trapping failed to catch woylies until December 2005. Because of the low number of woylie captures at this site no population data could be analysed. The number of woylies KTBA at site B was consistently higher than site A, although still low. A total of 11 individual females and 17 individual males were trapped between May 2002 and December 2005 giving a sex ratio of 1:1.5 females to males. The trapping effort in the spring of 2003 resulted in an estimated population of brushtail possums ranging from 17 at site A to 70 at site B thus giving a density of approximately 1.4 and 5.8 brush tail possums ha- 1, respectively. The trapping effort in spring 2005 resulted in an estimated population of brushtail possums of 25 at site A and 35 at site B, thus giving a density of 2.1 and 2.9 brushtail possums ha -1, respectively. The trap success per 100 trap nights for brushtail possums was significantly (p <0.0001) higher than that of woylies at both experimental sites during 2003 and 2005. Total trap success was compared between sites for woylies and brushtail possums. There was a significant ex;= 16.41, p <0.01) difference in the trap success between the sites for woylies, and a highly significant ex;= 42.04, p <0.001) difference for brushtail possums for the 2003 trapping. The trap success for woylies, per 100 trap nights, was not significantly ex;= 4.1358, p >0.100) different between seasons for site B in 2005. Similarly, the trap success for brushtail possums, per 100 trap nights, was not significantly ex; =2.8565, p >0.200) different. However, brushtail possums, for all seasons, had a significantly (ex12 =103.9, p <0.0001) higher trap success compared with woylies for site B. Site A was not analysed due to the lack of woylies at this site from 2004 onwards. Trapping at the control site failed to catch woylies, and only one possum was caught during the trapping effort. Fungal spores occurred in 100% en= 16) of woylie scats for winter, spring and summer. During the three seasons analysed, woylies consumed an equal balance of spore types from hypogeal (n = 7) and epigeal en= 7) fungi. Overall, woylies ate eight spore types in winter and 12 spore types in spring. Fungi appeared to be important in the diet of brushtail possums during autumn and summer as a higher percentage of brushtail possums had fungal spores in their scats during these seasons compared with spring (x12= 13.94,p <0.001) and winter (x12 =8.65, p <0.005). The percentage of brushtail possums that consumed fungi during winter and spring did not (x12 = 1.128, 0.250 > p <0.500) differ, nor did the percentage of brushtail possums that ate fungi in autumn and summer (X12 = 0.00046, 0.925> p <0.99). The major spore type consumed throughout the year by both the brushtail possum and the woylie was Mesophellia. However, the amount of Mesophellia consumed by the brushtail possum differed between seasons (F = 83.472, df=1, p <0.001) as it was only dominant in the diet during the hotter months (i.e. summer and autumn). Austrogautieria and Mesophellia were the only spore types present in both brushtail possum and woylie scat samples in summer. In contrast to Mesophellia, spores of Gastrotylopilus dominated the brushtail possum and woylie scat samples during the cooler seasons (winter and spring) and were absent in summer and autumn. They occurred in significantly higher densities in winter than spring (F= 10.390, df = 1 p = 0.002) in brushtail possum scats. Overall, woylie scats contained a higher density of spores for all spore types than in brushtail possum scats. The total spore densities per gram of scat for woylies were 348.4 x 104 ± SE 277.1 x 104 for winter, 170.7 x 104 ± SE 110.3 x 104 for spring and 1353.4 x 104 ± SE 450.6 x 104 for summer. At site A the spatial distribution of adult sandalwood trees, adult to juvenile, adult to seedling and juvenile to juvenile were aggregated (p <0.05), whilst seedling to seedling distribution was highly aggregated (p <0.005). The density of adults was approximately 24 trees ha-1, there were approximately 107 saplings ha-1 and approximately 128 seedlings ha- 1. The furthest sandalwood seedling found growing away from an adult was 91 m. At site B the distribution of mature adult trees, adults to saplings and saplings to saplings were all highly aggregated (p <0.005). Adults occurred at an approximate density of 81 trees ha-1, and saplings at 38 trees ha-1. At the control site, mature trees were highly aggregated (p <0.005) with a density of 15.7 trees ha-1. There were very few seedlings and saplings at the site, all of which were clumped under or around the crown of the parent tree. Log-linear analysis indicated a significant two-way interaction between the presence of woylies and the distance the offspring were found in relation to adult trees (x; = 288.4,p <0.0001) and between the presence of woylies and the age of the offspring (saplings and seedlings) (x; = 34, p <0.0001). Thus, in Dryandra, where woylies were present, there were higher numbers of both seedlings and saplings growing more than 1 m from adult trees, compared with Wickepin Water Reserve, where woylies were not present. Conversely, in the absence of woylies, more seedlings and saplings grew less than 1 m from adult trees. For the three year survival rates of seedlings surveyed for the three sites, log-linear analysis indicated a significant two-way interaction between site and seedling survival (x23 = 218, p <0.0001) and between seedling survival and under/away from parent crown (x23 = 107, p <0.0001). Site A experienced significantly higher mortality of seedlings growing away from the crown after three years compared with site B, whilst the control site suffered significant seedling mortality under the crown. There was a highly significant (one-way ANOVA, F(2,99)= 125.58, p <0.0001) difference between Dryandra Woodland and Wickepin Water Reserve in the mean number of whole seeds found under adult sandalwood trees. The mean number of whole seeds under the parent crown at site A was 0.97 ± 0.16, range 1 to 2 (n = 34). At site B the mean was 0.76 ± 1.67, range 1 to 9 (n = 34), while at the control site the mean was 59.97 ± 11.19, range 10 to 330 (n = 34). A posteriori analysis indicated that the mean number of whole seeds under the parent crown at Wickepin Water Reserve, where woylies were extinct, was significantly greater than those at Dryandra Woodland where woylies were still present (p <0.0001). Log-linear analysis indicated a significant two-way interaction between the presence of woylies and the distance the offspring were found in relation to adult trees (x22 = 288.4, p <0.0001) and between the presence of woylies and the age of the offspring (saplings and seedlings) (x22= 34, p <0.0001). To enable large numbers of seeds to be tracked effectively over a period of time, two experiments were undertaken using a labelling technique with the isotope scandium-46 (Sc46). Scandium-46 is a moderate beta and a high level gamma-emitting radionuclide with a half life of 83.6 days and a maximum photon energy of 1.12 Mega electron volts (MeV) 100%. It is the high gamma emissions that allow seeds labelled with Sc46 to be tracked using a Geiger Muller (GM) counter to determine their fate. Scandium-46 is absorbed by the seed hull and each seed typically received ~ 1 microcurie (uCi) [37 ki1obecquerel (kBq)] of activity, sufficiently strong to allow detection of buried seeds from about 30 cm with a GM counter. The seeds labelled for the May 2005 experiment were sandalwood, S. acuminatum (quandong), Acacia acuminata (jam) and Gastrolobium microcarpum whilst in the February 2006 experiment only sandalwood seeds were used. In the May 2005 experiment, woylies ate or cached all the sandalwood seeds before any interaction with either S. acuminatum (quandong), Acacia acuminata (jam) or Gastrolobium microcarpum seeds ocurred. In the first night all the sandalwood seeds had been removed with 26 cached and 24 seeds eaten in situ under or within 1 m from the source tree. The woylies took three nights to remove all the quandong. On the third night the rate of removal increased which resulted in 6 cached seeds and 39 seeds were consumed in situ. The next type of seed to be removed was the Acacia acuminata which were all consumed by one woylie. No Acacia seed caches were found. On the fifth night of the experiment the majority of Gastrolobium seeds were observed to be eaten in situ by one woylie. Two caches of Gastrolobium seeds were located, one cache with 22 seeds and one with 15 seeds buried within 8 m of each other. In the February 2006 experiment, of the 500 seeds deployed under the source tree over four nights, 211 (42.2%) were eaten in situ, 185 (37%) were cached and 104 (20.8%) had an unknown fate. Individual seeds were buried between 1 and 6 cm deep (mean 3.15 ± SE 0.11 em). By November 2006, 185 primary, 120 secondary, 52 tertiary, 35 quaternary and 17 quintic caches had been located. Of the 185 seeds initially buried, 40 (21.6%) seeds had been dug-up and eaten in situ, 5 (2.7%) were left undisturbed in the caches, 20 (10.8%) were removed from the area, their fate unknown, and the remaining 120 (65%) seeds were re-cached into secondary caches. Of the 120 secondary caches, 38 (32%) seeds were dug up and eaten in situ, 12 (10%) were left undisturbed, 18 (15%) were removed from the area, their fate unknown, and 52 (43%) had been re-cached into tertiary caches. Subsequently, seven (13.5%) of the seeds were consumed from these caches, 10 (19.2%) were left undisturbed and 35 (67%) seeds were re-cached to quaternary caches. From the quaternary caches, 12 (34.2%) seeds were dug-up and eaten in situ, 6 (17.1%) caches were left undisturbed and 17 seeds were dug-up and recached for a fifth time. Of these quintic caches, 4 were dug-up and eaten, 5 (29.4%). The most common site for primary through to quintic caches was A. acuminata. The next most common area for primary to quaternary caches was out in the open not near any particular vegetation type. The exception was the location of quintic caches which had a higher percentage of caches under fallen logs (24% n = 4) compared with out in the open (18% n = 3). There were a relatively high number of seeds cached within 30 em of a sandalwood tree in all types of caches. The fate of 17 individual seeds that were cached and re-cached in five different caches was mapped, however, it remains unknown whether the same woylie that made the primary cache went on to move the seeds five times or whether it was several different woylies moving the seeds around. The fate of cached seeds was monitored for germination rates in situ. All the seeds were eventually consumed from the May 2005 experiment before any germination could take place. For the 2006 experiment, overall germination rates were low with only 6 (15.8%) of seeds from the 38 undisturbed caches germinating. Of these, two from the secondary caches germinated out in the open and did not survive. The single seed from an undisturbed tertiary cache germinated beneath a fallen log as did one of the seeds that germinated and survived from the undisturbed quintic cache while another successfully germinated beneath a G. microcarpum bush. Olfaction appeared to be the principle method used by woylies to locate buried seeds, a process which they are very efficient at. There was a significant (x12 = 6.5, 0.025> p <0.01) difference in the number of artificially cached seeds dug-up by woylies compared with disturbance of the control 'caches'. Of the 80 caches, 65 (81.2%) were located by woylies over three nights. During the same time period, 39 (48.7%) of the control 'caches' showed signs of being disturbed, thus suggesting that woylies were, at least in part, responding to the smell of disturbed soil as well as the actual seed. Furthermore, there was also a highly significant (x12 = 7.5, 0.01> p <0.005) difference between the number of seeds located by woylies under leaf litter compared to the control. All of the 20 seeds under the leaf litter were located within two nights compared with only six (30%) of the control 'caches' in the leaf litter showing signs of disturbance. The predation rates of buried seeds and emerging seedlings was measured. After distributing 100 sandalwood seeds under a random sandalwood tree at each site, there was significantly (x12 = 12.25, p <0.0001) less seed disturbance at Site A on the first night compared to site B. Conversely, on the third night there was significantly (x12 = 10.96, p <0.0001) more seed disturbance at site A compared with site B. All of the 100 seeds had been eaten in situ or removed by woylies at the end of the third night at site B whilst at site A the 100 seeds were eaten in situ or removed by woylies by the end of the fourth night. It is without doubt that woylies are prolific seed cachers and that their relationship with sandalwood is complex and mutual in nature. The woylies benefit by consuming some of the large nutritious seeds sandalwood produces. In-turn, sandalwood benefits by having a vector, the woylie, to disperse their seeds many of which are buried in areas conducive to germination, for example, under fallen logs and near sandalwood's host species. Woylies are able to very efficiently locate buried seeds by using olfaction and possibly visual clues of disturbed earth during random foraging for hypogeous fungi, although there was no evidence to suggest they use spatial memory to locate seeds. To determine if woylies use emerging seedlings as markers, seedlings were grown in the greenhouse and transplanted in Dryandra. Of the 46 seedlings transplanted at site A, 14 (30%) were intact and growing after one month. A total of 23 seedlings (50%) were dug-up by woylies. Of these, 17 (37%) were discarded whilst the remainder of the endosperm was eaten in situ leaving the endocarp on the ground. In the remaining six (13%) seedlings the endocarps were removed from the area, presumably to be eaten elsewhere rather than re-cached as they would have been split open during the germination process and, therefore, no longer suitable for storage. Similar numbers and fates were recorded at site B with 10 ( 43%) left intact, 22 (51%) of the seedlings had been dug-up by woylies and discarded whilst the remainder of the epicarp was eaten in situ leaving the endocarp on the ground. Three (7%) of the seedlings were dug-up by woylies but again the endocarps were removed from the area. Six (14%) seedlings at site B were also grazed and two (5%) seedlings died. There was no significant (x12 = 3.96, p <0.25) difference between sites for the fate of seedlings. The majority of seeds that were retrieved by woylies from the seedlings were eaten in situ at both sites. There was no significant (x12 = 1.583, 0.25 < p > 0.10) difference between sites for seeds eaten in situ or removed from the area. The fate of the seeds removed from the area was unknown. It was concluded that woylies have both a mutualistic and antagonistic relationship with sandalwood and its propagules and as a result may strongly influence the recruitment and spatial distribution of sandalwood by reducing the number of seeds and seedlings available for dispersal and regeneration, respectively. Woylies are both pre and postdispersal predators consuming seeds under the parent trees, seeds that have been dispersed away from the parent trees and buried and germinating seeds. Evidence has been provided to support the early anecdotal reports that woylies use emerging seedlings as 'markers' to locate buried seeds. This is the first study of its type in Australia to demonstrate, unequivocally, the consequences of the loss of a key seed-dispersal vector, the woylie, on sandalwood recruitment and regeneration in Dryandra Woodland. Through seed-caching and seed-predation, woylies have been shown to substantially alter the fate and distribution of sandalwood seeds and seedlings. The loss of woylies from 97% of their former range will undoubtedly have serious implications for sandalwood and possibly other plant species. In losing this seed-dispersing and seed-caching animal from our ecosystems we have lost a keystone species. The woylie sandalwood interaction seems to have shaped the morphology of the sandalwood seed and fruiting phenology by making the propagules attractive and rewarding to the woylie. In this way both the woylie and sandalwood benefit from this interaction. Such close interactions have a positive impact on the health and functioning of ecosystems and landscapes.

Thesis (Ph. D.)--Ohio State University, 2005.<br>Title from first page of PDF file. Document formatted into pages; contains xii, 286 p.; also includes graphics (some col.). Includes bibliographical references (p. 273-286). Available online via OhioLINK's ETD Center

Durant ma thèse, j'ai recherché les conditions pour l'activation / fonctionnalisation de liaisons C-H pour la construction de bi(hétéro)aryles tolérant des groupement fonctionnels réactifs tels que des silyles, des alcènes, des esters ou encore des amides. Par rapport aux protocoles de couplage classiques tels que les réactions de Suzuki, Stille ou Negishi, la fonctionalisation de liaisons C-H fournit des procédures moins coûteuses et plus écologiques si elle tolère des groupements utiles en synthèse. D'abord, nous avons observé que les thiophènes substitués par des silyles en C2 peuvent être arylés avec des bromures d'aryle sans désilylation en présence du précatalyseur Pd(OAc)2/dppb. Les produits de couplage sont obtenus avec de bons rendements et avec inhibition de la réaction de désilylation. Ensuite, nous avons démontré que le système Pd(OAc)2/KOAc sans ligand phosphine, favorise l'arylation directe des hétéroaromatiques et inhibe la réaction de type Heck avec des thiophenes substitués par des alcènes substituées sur les carbones 2 ou 3. Ensuite, nous avons démontré que les fonctions esters sur les hétéroaromatiques peuvent être avantageusement utilisées comme groupements protecteurs, permettant l'arylation directe d'hétéroaromatiques sur le carbone C5. Enfin, l'heteroarylation directe de 2- ou 4-bromobenzamides avec des hétéroarènes catalysée au palladium a été étudiée. En présence de KOAc comme base, aucune formation de liaisons C-C ou C-N par couplage de deux bromobenzamides n'a été observée<br>During my thesis, I focused on condition for the activation / functionalisation of C-H bonds for the construction of biaryl derivatives tolerant to the reactive functional groups such as silyl, alkenes, esters or amides. Compared to classic cross-coupling protocols (Suzuki, Stille or Negishi), C-H bond functionalisation provides a costly effective and environmentally attractive procedures. At first, we observed that the silyl-substituted thiophenes can be directly arylated with aryl bromides without desilylation, using the simple Pd(OAc)2/dppb precatalyst for both conversion and desilylation inhibition. Then, we have demonstrated that the Pd(OAc)2/KOAc catalyst system without phosphine ligand, even using as few as 0.1 mol% of Pd catalyst, promotes the direct arylation of heteroaromatics and inhibits the Heck type reaction with 1,2-disubstituted alkenes. In addition, we demonstrated that easily accessible esters on heteroaromatics can be advantageously employed as blocking groups in the course of the direct arylation of several heteroaromatic derivatives. Finally, the palladium-catalyzed direct heteroarylation of 2- or 4-bromobenzamide with heteroarenes was studied. In the presence of KOAc as the base, no formation of C-N or C-C bonds by coupling of two bromobenzamide was observed

This thesis describes novel reaction protocols for the synthesis of diaryliodonium salts and also provides an insight to the mechanism of α-arylation of carbonyl compounds with diaryliodonium salts.  The first chapter gives a general introduction to the field of hypervalent iodine chemistry, mainly focusing on recent developments and applications of diaryliodonium salts. Chapter two describes the synthesis of electron-rich to electron-poor diaryliodonium triflates, in moderate to excellent yields from a range of arenes and iodoarenes. In chapter three, it is described that molecular iodine can be used together with arenes in a direct one-pot, three-step synthesis of symmetric diaryliodonium triflates. A large scale synthesis of bis(4-tert-butylphenyl)iodonium triflate is also described, controlled and verified by an external research group, further demonstrating the reliability of this methodology. The fourth chapter describes the development of a sequential one-pot synthesis of diaryliodonium salts from aryl iodides and boronic acids, furnishing symmetric and unsymmetric, electron-rich to electron-poor diaryliodonium tetrafluoroborates in moderate to excellent yields. This method was developed to overcome the regiochemical limitations imposed by the reaction mechanism in the protocols described in the preceding chapters. Chapter five describes a one-pot synthesis of heteroaromatic iodonium salts under similar conditions described in chapter two. The final chapter describes the reaction of enolates with chiral diaryliodonium salts or together with a phase transfer catalyst yielding racemic products. DFT calculations were performed, which revealed a low lying energy transition state (TS) between intermediates, which is believed to be responsible for the lack of selectivity observed in the experimental work. It is also proposed that a [2,3] rearrangement is preferred over a [1,2] rearrangement in the α-arylation of carbonyl compounds. The synthetic methodology described in this thesis is the most generally applicable, efficient and high-yielding to date for the synthesis of diaryliodonium salts, making these reagents readily available for various applications in synthesis.

Palladium complexes have the ability to catalyse cross-coupling of two organic moieties through the formation of transient metal-carbon bonds, thus bringing them closer to each other to facilitate the formation of a new bond. Palladium-catalysed coupling reactions are one of the most important carbon-carbon forming reactions available to organic chemists and many of these reactions rely on the reactivity of aryl-palladium complexes. The investigation of new aryl-palladium precursors is thus of great interest, especially as more sustainable and economic methods can be developed. This thesis describes the use of carboxylic acids and sodium arylsulfinates as such new arylating agents. Protocols for microwave-assisted palladium(II)-catalysed decarboxylative synthesis of electron-rich styrenes and 1,1-diarylethenes were developed. However, these transformations had very limited substrate scopes which prompted the investigation of sodium arylsulfinates as alternative arylating agents. These substrates were employed in the microwave-assisted palladium(II)-catalysed desulfitative addition to nitriles, and the substrate scope was demonstrated by combining a wide array of sodium arylsulfinates and nitriles to yield the corresponding aryl ketones. The application of the desulfitative reaction in a continuous flow setup was demonstrated, and aluminium oxide was identified as safe alternative to borosilicate glass as a reactor material. The mechanisms of the decarboxylative and desulfitative transformations were investigated by density functional theory (DFT) calculations. The desulfitative reaction was also investigated by direct electrospray ionization mass spectrometry (ESI-MS), providing further mechanistic insight. Finally, a protocol for the safe and convenient synthesis of a wide range of sodium arylsulfinates was developed.

This thesis is devoted to the study of linear relationships in symmetric block ciphers. A block cipher is designed so that the ciphertext is produced as a nonlinear function of the plaintext and secret master key. However, linear relationships within the cipher can still exist if the texts and components of the cipher are manipulated in a number of ways, as shown in this thesis. There are four main contributions of this thesis. The first contribution is the extension of the applicability of integral attacks from word-based to bitbased block ciphers. Integral attacks exploit the linear relationship between texts at intermediate stages of encryption. This relationship can be used to recover subkey bits in a key recovery attack. In principle, integral attacks can be applied to bit-based block ciphers. However, specific tools to define the attack on these ciphers are not available. This problem is addressed in this thesis by introducing a refined set of notations to describe the attack. The bit patternbased integral attack is successfully demonstrated on reduced-round variants of the block ciphers Noekeon, Present and Serpent. The second contribution is the discovery of a very small system of equations that describe the LEX-AES stream cipher. LEX-AES is based heavily on the 128-bit-key (16-byte) Advanced Encryption Standard (AES) block cipher. In one instance, the system contains 21 equations and 17 unknown bytes. This is very close to the upper limit for an exhaustive key search, which is 16 bytes. One only needs to acquire 36 bytes of keystream to generate the equations. Therefore, the security of this cipher depends on the difficulty of solving this small system of equations. The third contribution is the proposal of an alternative method to measure diffusion in the linear transformation of Substitution-Permutation-Network (SPN) block ciphers. Currently, the branch number is widely used for this purpose. It is useful for estimating the possible success of differential and linear attacks on a particular SPN cipher. However, the measure does not give information on the number of input bits that are left unchanged by the transformation when producing the output bits. The new measure introduced in this thesis is intended to complement the current branch number technique. The measure is based on fixed points and simple linear relationships between the input and output words of the linear transformation. The measure represents the average fraction of input words to a linear diffusion transformation that are not effectively changed by the transformation. This measure is applied to the block ciphers AES, ARIA, Serpent and Present. It is shown that except for Serpent, the linear transformations used in the block ciphers examined do not behave as expected for a random linear transformation. The fourth contribution is the identification of linear paths in the nonlinear round function of the SMS4 block cipher. The SMS4 block cipher is used as a standard in the Chinese Wireless LAN Wired Authentication and Privacy Infrastructure (WAPI) and hence, the round function should exhibit a high level of nonlinearity. However, the findings in this thesis on the existence of linear relationships show that this is not the case. It is shown that in some exceptional cases, the first four rounds of SMS4 are effectively linear. In these cases, the effective number of rounds for SMS4 is reduced by four, from 32 to 28. The findings raise questions about the security provided by SMS4, and might provide clues on the existence of a flaw in the design of the cipher.

abstract: The explicit role of soil organisms in shaping soil health, rates of pedogenesis, and resistance to erosion has only just recently begun to be explored in the last century. However, much of the research regarding soil biota and soil processes is centered on maintaining soil fertility (e.g., plant nutrient availability) and soil structure in mesic- and agro- ecosystems. Despite the empirical and theoretical strides made in soil ecology over the last few decades, questions regarding ecosystem function and soil processes remain, especially for arid areas. Arid areas have unique ecosystem biogeochemistry, decomposition processes, and soil microbial responses to moisture inputs that deviate from predictions derived using data generated in more mesic systems. For example, current paradigm predicts that soil microbes will respond positively to increasing moisture inputs in a water-limited environment, yet data collected in arid regions are not congruent with this hypothesis. The influence of abiotic factors on litter decomposition rates (e.g., photodegradation), litter quality and availability, soil moisture pulse size, and resulting feedbacks on detrital food web structure must be explicitly considered for advancing our understanding of arid land ecology. However, empirical data coupling arid belowground food webs and ecosystem processes are lacking. My dissertation explores the resource controls (soil organic matter and soil moisture) on food web network structure, size, and presence/absence of expected belowground trophic groups across a variety of sites in Arizona.<br>Dissertation/Thesis<br>Ph.D. Biology 2014

Dottorato in Scienze della Vita. Ciclo XXXI<br>The cytochrome P450 1B1 (CYP1B1) is a heme-thiolate monooxygenase involved in both estrogen and environmental contaminants metabolism. For instance, CYP1B1 catalyzes the hydroxylation of 17-β estradiol (E2) leading to the production of 4-hydroxyestradiol that may act as a potent carcinogenic agent. In addition, CYP1B1 is overexpressed in different tumors including breast cancer. In this scenario, it is worth mentioning that CYP1B1 expression is triggered by estrogens through the estrogen receptor (ER)α in breast cancer cells. In the present study, we evaluated whether the G protein estrogen receptor namely GPER may provide an alternate route toward the expression and function of CYP1B1 in ER-negative breast cancer cells, in cancer-associated fibroblasts (CAFs) obtained from breast cancer patients, in CAFs derived from a cutaneous metastasis of an invasive mammary ductal carcinoma and in breast tumor xenografts. Our results show that GPER along with the EGFR/ERK/c-Fos transduction pathway can lead to CYP1B1 regulation through the involvement of a half-ERE sequence located within the CYP1B1 promoter region. As a biological counterpart, we found that both GPER and CYP1B1 mediate growth effects in vitro and in vivo. Altogether, these data suggest that estrogens in ER-negative cell contexts may engage the alternate GPER signaling toward CYP1B1 regulation. CYP1B1 is a well-known target gene of the aryl hydrocarbon receptor (AHR) that may be activated by the carcinogenic pollutant 3-methylcholanthrene (3MC). Hence, we aimed to provide novel insights into the molecular mechanisms by which 3MC and E2 may activate a cross talk between AHR and GPER transduction pathways leading to the stimulation of breast cancer cells and CAFs. In particular, our results demonstrate that 3MC and E2 trigger the EGFR/ERK/c-Fos signalling through both AHR and GPER toward the up-regulation of CYP1B1 and cyclin D1 as well as the stimulation of growth responses. Altogether, the present findings suggest that a functional interaction between AHR and GPER may occur toward breast cancer progression<br>Università della Calabria

碩士<br>國立陽明大學<br>生理學研究所<br>100<br>The aryl hydrocarbon receptor (AhR) is a ubiquitously expressed and highly evolutionarily conserved ligand-activated transcription factor. AhR is activated by various environmental organic pollutants as well as endogenous tryptophan-derived endogenous ligands. Exposure to environmental AhR ligands is associated with developmental deficit in cognitive function, but the underlying mechanism remains unclear. Accumulating evidence suggests that AhR involves in neuronal survival and neural differentiation. In this study, we aimed to investigate the role of AhR in the expression and function of NMDA receptors and BDNF during neuronal differentiation. P19 mouse embryonic carcinoma cells, a pluripotent AhR-expressing cell line, express NMDA receptor subunit NR2A but not NR1 or NR2B in the undifferentiated stage. Using a fast neuronal differentiation method by overexpression of the proneural basic helix-loop-helix transcription factor Mash1, P19 cells demonstrated apparent neuronal morphology with extensively branching neurites. Neuronal markers such as microtubule-associated protein 2 (MAP-2) and neuronal class III β-tubulin were expressed in Mash1-differentiated P19 cells after Mash1 transfection. NMDA-induced intracellular calcium elevation was also observed in Mash1-differentiated neurons instead of undifferentiated P19 cells. Interestingly, a gradual increase of NR2A and robust induction of NR1 and NR2B were observed in Mash1-differentiated P19 neurons, nevertheless, AhR knockdown using specific siRNA significantly attenuates NR2A, NR2B and NR1 expression with no apparent effect on the NR2A/2B ratio. Besides, activation of AhR by its natural ligand 6-formylindolo[3,2-b]carbazole (FICZ) induces AhR nuclear translocation as well as expression of CYP1A1, NR1, NR2A and NR2B, and these effects were noticeably diminished under AhR knockdown. As to the activity-dependent neurotrophic factor BDNF, FICZ but not NMDA reduced its protein level while contrarily induces its mRNA in Mash1-differentiated P19 neurons, suggesting the AhR participation in the survival of developing neurons supported by BDNF. This in vitro finding was well correlated with the BDNF level in the nestin-Cre/AhR-floxed brain-specific knockout mice, which expressed more abundant BDNF protein in both cerebral cortex and cerebellum than wild type mice. Lastly, we characterized the activity of human AhR and NMDA subunits expression in human neuroblastoma cell lines, and found that SK-N-DZ but not SH-SY5Y express functional AhR. Taken together, our findings indicate that AhR in mouse P19-derived neurons functions to mediate NMDA receptor and BDNF gene expression during neuronal differentiation, which would have significant impact on the neuronal plasticity for brain development. The impact of this AhR mechanism in human neuron development may be further investigated using AhR-expressing multi-potent neuroblastoma SK-N-DZ.

abstract: Climate change has the potential to affect vegetation via changes in temperature and precipitation. In the semi-arid southwestern United States, heightened temperatures will likely lead to accelerated groundwater pumping to meet human needs, and altered storm patterns may lead to changes in flood regimes. All of these hydrologic changes have the potential to alter riparian vegetation. This research, consisting of two papers, examines relationships between hydrology and riparian vegetation along the Verde River in central Arizona, from applied and theoretical perspectives. One paper investigates how dominance of tree and shrub species and cover of certain functional groups change along hydrologic gradients. The other paper uses the Verde River flora along with that river's flood and moisture gradients to answer the question of whether functional groups can be defined universally. Drying of the Verde River would lead to a shift from cottonwood-willow streamside forest to more drought adapted desert willow or saltcedar, a decline in streamside marsh species, and decreased species richness. Effects drying will have on one dominant forest tree, velvet ash, is unclear. Increase in the frequency of large floods would potentially increase forest density and decrease average tree age and diameter. Correlations between functional traits of Verde River plants and hydrologic gradients are consistent with "leaf economics," or the axis of resource capture, use, and release, as the primary strategic trade-off for plants. This corresponds to the competitor-stress tolerator gradient in Grime's life history strategy theory. Plant height was also a strong indicator of hydrologic condition, though it is not clear from the literature if plant height is independent enough of leaf characteristics on a global scale to be considered a second axis. Though the ecohydrologic relationships are approached from different perspectives, the results of the two papers are consistent if interpreted together. The species that are currently dominant in the near-channel Verde River floodplain are tall, broad-leaf trees, and the species that are predicted to become more dominant in the case of the river drying are shorter trees or shrubs with smaller leaves. These results have implications for river and water management, as well as theoretical ecology.<br>Dissertation/Thesis<br>M.S. Plant Biology 2011

Organelles within the endomembrane system of all eukaryotic cells exchange membrane lipids and proteins using membrane-bound transport vesicles. This highly conserved vesicular transport process is essential for life and is highly regulated. Much of this regulation is provided by small monomeric GTP-binding proteins such as Arf and Arl that act as molecular switches, cycling between inactive GDP-bound and active GTP-bound states. This cycle of GTP binding and hydrolysis is controlled by guanine-nucleotide exchange factors (GEFs) and GTPase activating proteins (GAPs), respectively. I have investigated regulatory interactions involving two ArfGAPs, Age1 and Gcs1, involved in post-Golgi vesicular transport in the budding yeast Saccharomyces cerevisiae. In yeast, the Age2 + Gcs1 ArfGAP pair is essential and facilitates post-Golgi transport. I found that overexpression of either the poorly characterized ArfGAP Age1 or the Sfh2 phosphatidylinositol-transfer protein can bypass the requirement for Age2 and Gcs1. Indeed, endogenous Age1 is required for efficient Sfh2-bypass. Moreover, the yeast phospholipase D protein, Spo14, which is activated by Sfh2 and regulates membrane lipid composition, is required for Age1 to effectively alleviate the deleterious effects of defective Age2 + Gcs1 function. My findings suggest that Age1 is regulated by membrane lipid composition and can provide ArfGAP function for post-Golgi transport. Gcs1 is involved in multiple vesicular transport stages, is a dual-specificity GAP for both Arf and Arl1 proteins and, as shown here, also has functions independent of its GAP activity. The absence of Gcs1 causes cold sensitivity for growth and endocytic transport. The cold sensitivity of cells lacking Gcs1 is alleviated by the elimination of either the Arl1 or Ypt6 vesicle-tethering pathway at the trans-Golgi, or by overexpression of Imh1, an effector of the Arl1 pathway. I found elimination of the Ypt6 pathway also prevents Arl1 activation and membrane localization, that Arl1 binding by Imh1 is necessary and sufficient for alleviation, and that the Gcs1 function required for growth and transport in the cold is independent of any GAP activity. My findings suggest that in the absence of this GAP-independent function of Gcs1 the resulting dysregulated Arl1 causes the gcs1? defects through the sequestration of a yet-to-be-determined cellular factor.