Discrete and Polymeric Complexes Comprising Bis-nor-seco-CB[10] and Oligoammonium Ions

ABSTRACT Title of Document: DISCRETE AND POLYMERIC COMPLEXES COMPRISING BIS-NOR-SECO-CB[10] AND OLIGOAMMONIUM IONS Regan C. Nally, Ph.D., 2009 Directed By: Professor Lyle D. Isaacs Department of Chemistry and Biochemistry Supramolecular architectures composed of multiple components are challenging to produce, as the enthalpic gain must be greater than the entropic penalty of strict geometrical arrangements. Therefore, it is the goal of supramolecular chemists to strategically design and synthesize molecules that will exhibit selectivity toward formation of a particular complex. This dissertation describes the formation of supramolecular architectures of increasing size and is organized in the following way. Chapter 1 introduces the reader to the field of supramolecular polymer chemistry. Chapter 2 describes the synthesis of a series of monovalent ditopic guests (II-1 - II-6) and their complexation properties toward double cavity cucurbituril host bis-ns-CB[10]. We observed the preferential formation of 1:1, 2:2, and oligomeric complexes rather than the desired n:n supramolecular polymers. Guest II-7 which contains a longer biphenyl spacer successfully precludes the formation of the 1:1 complex but results in the formation of the 2:2 complex (bis-ns-CB[10]2*II-72) rather than supramolecular polymer. Guest II-8 is heterovalent and ditopic and is shown to reversibly form 2:2 and 1:2 complexes (bis-ns-CB[10]2*II-82 and bis-ns-CB[10]*II-82) in response to changes in host:guest stoichiometry. Lastly, this equilibrium can be manipulated by the addition of exogenous CB[6] which selectively targets the hexanediammonium ion binding region of II-8 and delivers the penta-molecular complex bis-ns-CB[10]*II-82*CB[6]2. Chapter 3 describes the formation of a main chain supramolecular polymer from a mixture of poly(diallyldimethylammonium chloride) (III-1) and bis-ns-CB[10]. The bis-ns-CB[10] molecular container behaves as a molecular handcuff, bringing together two ends of individual polymers to form III-1n* bis-ns-CB[10]m, resulting in an extension of the length of polymer. The effect of bis-ns-CB[10] on the physical properties of the polymer was investigated using viscometry in aqueous solution. A decrease in the ηrel was observed upon increasing concentrations of bis-ns-CB[10] to a solution of III-1. Atomic force microscopy (AFM), and diffusion-ordered spectroscopy (DOSY) were performed to probe the mode of interaction between polymer III-1 and bis-ns-CB[10]. Collectively, the data supports the two roles for bis-ns-CB[10]: 1) as a deaggregation agent, and 2) as a molecular handcuff that non-covalently links individual polymer strands resulting in overall extension of the polymer

Emerging infectious disease implications of invasive mammalian species : the greater white-toothed shrew (Crocidura russula) is associated with a novel serovar of pathogenic Leptospira in Ireland

The greater white-toothed shrew (Crocidura russula) is an invasive mammalian species that was first recorded in Ireland in 2007. It currently occupies an area of approximately 7,600 km2 on the island. C. russula is normally distributed in Northern Africa and Western Europe, and was previously absent from the British Isles. Whilst invasive species can have dramatic and rapid impacts on faunal and floral communities, they may also be carriers of pathogens facilitating disease transmission in potentially naive populations. Pathogenic leptospires are endemic in Ireland and a significant cause of human and animal disease. From 18 trapped C. russula, 3 isolates of Leptospira were cultured. However, typing of these isolates by standard serological reference methods was negative, and suggested an, as yet, unidentified serovar. Sequence analysis of 16S ribosomal RNA and secY indicated that these novel isolates belong to Leptospira alstonii, a unique pathogenic species of which only 7 isolates have been described to date. Earlier isolations were limited geographically to China, Japan and Malaysia, and this leptospiral species had not previously been cultured from mammals. Restriction enzyme analysis (REA) further confirms the novelty of these strains since no similar patterns were observed with a reference database of leptospires. As with other pathogenic Leptospira species, these isolates contain lipL32 and do not grow in the presence of 8-azagunaine; however no evidence of disease was apparent after experimental infection of hamsters. These isolates are genetically related to L. alstonii but have a novel REA pattern; they represent a new serovar which we designate as serovar Room22. This study demonstrates that invasive mammalian species act as bridge vectors of novel zoonotic pathogens such as Leptospira

Scientific foundations for an IUCN red list of ecosystems

An understanding of risks to biodiversity is needed for planning action to slow current rates of decline and secure ecosystem services for future human use. Although the IUCN Red List criteria provide an effective assessment protocol for species, a standard global assessment of risks to higher levels of biodiversity is currently limited. In 2008, IUCN initiated development of risk assessment criteria to support a global Red List of ecosystems. We present a new conceptual model for ecosystem risk assessment founded on a synthesis of relevant ecological theories. To support the model, we review key elements of ecosystem definition and introduce the concept of ecosystem collapse, an analogue of species extinction. The model identifies four distributional and functional symptoms of ecosystem risk as a basis for assessment criteria: A) rates of decline in ecosystem distribution; B) restricted distributions with continuing declines or threats; C) rates of environmental (abiotic) degradation; and D) rates of disruption to biotic processes. A fifth criterion, E) quantitative estimates of the risk of ecosystem collapse, enables integrated assessment of multiple processes and provides a conceptual anchor for the other criteria. We present the theoretical rationale for the construction and interpretation of each criterion. The assessment protocol and threat categories mirror those of the IUCN Red List of species. A trial of the protocol on terrestrial, subterranean, freshwater and marine ecosystems from around the world shows that its concepts are workable and its outcomes are robust, that required data are available, and that results are consistent with assessments carried out by local experts and authorities. The new protocol provides a consistent, practical and theoretically grounded framework for establishing a systematic Red List of the world’s ecosystems. This will complement the Red List of species and strengthen global capacity to report on and monitor the status of biodiversity

A concise guide to developing and using quantitative models in conservation management

Quantitative models are powerful tools for informing conservation management and decision-making. As applied modeling is increasingly used to address conservation problems, guidelines are required to clarify the scope of modeling applications and to facilitate the impact and acceptance of models by practitioners. We identify three key roles for quantitative models in conservation management: (a) to assess the extent of a conservation problem; (b) to provide insights into the dynamics of complex social and ecological systems; and, (c) to evaluate the efficacy of proposed conservation interventions. We describe 10 recommendations to facilitate the acceptance of quantitative models in conservation management, providing a basis for good practice to guide their development and evaluation in conservation applications. We structure these recommendations within four established phases of model construction, enabling their integration within existing workflows: (a) design (two recommendations); (b) specification (two); (c) evaluation (one); and (d) inference (five). Quantitative modeling can support effective conservation management provided that both managers and modelers understand and agree on the place for models in conservation. Our concise review and recommendations will assist conservation managers and modelers to collaborate in the development of quantitative models that are fit-for-purpose, and to trust and use these models appropriately while understanding key drivers of uncertainty.Pablo García‐Díaz, Thomas A.A. Prowse, Dean P. Anderson, Miguel Lurgi Rachelle N. Binny, Phillip Casse

Identification of TLR10 as a key mediator of the inflammatory response to Listeria monocytogenes in intestinal epithelial cells and macrophages

Listeria monocytogenes is a Gram-positive bacterium that can cause septicemia and meningitis. TLRs are central receptors of the innate immune system that drive inflammatory responses to invading microbes such as L. monocytogenes. Although intestinal epithelial cells (IECs) represent the initial point of entry used by L. monocytogenes for infection, the innate immune response to L. monocytogenes in these cells has been poorly characterized to date. The aim of this study was to determine which TLRs are involved in mediating the immune response to L. monocytogenes in IECs. We performed an RNA interference screen of TLRs 1-10 in the HT-29 IEC cell line and observed the most significant reduction in chemokine output following silencing of TLR10. This effect was also observed in the macrophage cell line THP-1. The chemokines CCL20, CCL1, and IL-8 were reduced following knockdown of TLR10. Silencing of TLR10 resulted in increased viability of L. monocytogenes in both HT-29 and THP-1 cells. TLR10 was found to be predominantly expressed intracellularly in epithelia, and activation required viable L. monocytogenes. NF-κB activation was seen to require TLR2 in addition to TLR10. Taken together, these data indicate novel roles for TLR10 in sensing pathogenic infection in both the epithelium and macrophages and have identified L. monocytogenes as a source of ligand for the orphan receptor TLR10

Identification of TLR10 as a key mediator of the inflammatory response to Listeria monocytogenes in intestinal epithelial cells and macrophages

Listeria monocytogenes is a Gram-positive bacterium that can cause septicemia and meningitis. TLRs are central receptors of the innate immune system that drive inflammatory responses to invading microbes such as L. monocytogenes. Although intestinal epithelial cells (IECs) represent the initial point of entry used by L. monocytogenes for infection, the innate immune response to L. monocytogenes in these cells has been poorly characterized to date. The aim of this study was to determine which TLRs are involved in mediating the immune response to L. monocytogenes in IECs. We performed an RNA interference screen of TLRs 1-10 in the HT-29 IEC cell line and observed the most significant reduction in chemokine output following silencing of TLR10. This effect was also observed in the macrophage cell line THP-1. The chemokines CCL20, CCL1, and IL-8 were reduced following knockdown of TLR10. Silencing of TLR10 resulted in increased viability of L. monocytogenes in both HT-29 and THP-1 cells. TLR10 was found to be predominantly expressed intracellularly in epithelia, and activation required viable L. monocytogenes. NF-κB activation was seen to require TLR2 in addition to TLR10. Taken together, these data indicate novel roles for TLR10 in sensing pathogenic infection in both the epithelium and macrophages and have identified L. monocytogenes as a source of ligand for the orphan receptor TLR10

Extracts of Polypore Mushroom Mycelia Reduce Viruses in Honey Bees

Waves of highly infectious viruses sweeping through global honey bee populations have contributed to recent declines in honey bee health. Bees have been observed foraging on mushroom mycelium, suggesting that they may be deriving medicinal or nutritional value from fungi. Fungi are known to produce a wide array of chemicals with antimicrobial activity, including compounds active against bacteria, other fungi, or viruses. We tested extracts from the mycelium of multiple polypore fungal species known to have antiviral properties. Extracts from amadou (Fomes) and reishi (Ganoderma) fungi reduced the levels of honey bee deformed wing virus (DWV) and Lake Sinai virus (LSV) in a dose-dependent manner. In field trials, colonies fed Ganoderma resinaceum extract exhibited a 79-fold reduction in DWV and a 45,000-fold reduction in LSV compared to control colonies. These findings indicate honey bees may gain health benefits from fungi and their antimicrobial compounds

Phylogeny based on <i>secY</i>.

<p>Phylogenetic reconstruction was inferred using the maximum likelihood method. The tree is drawn to scale, with branch lengths measured in the number of substitutions per site.</p