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Paul D. Beer - One of the best experts on this subject based on the ideXlab platform.
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active metal template synthesis of a neutral indolocarbazole containing 2 rotaxane Host System for selective oxoanion recognition
Organic and Biomolecular Chemistry, 2017Co-Authors: Asha Brown, Kathleen M Mullen, Thomas Lang, Paul D. BeerAbstract:An active metal template strategy was used to synthesise a neutral indolocarbazole containing [2]rotaxane anion Host System. 1H NMR anion binding investigations reveal that the [2]rotaxane recognises a range of monoanions in acetone-d5 : D2O 95 : 5 with an unusual interlocked Host selectivity for acetate and dihydrogenphosphate oxoanions over halides. The rotaxane displays an overall selectivity for the sulfate dianion, favouring a 2 : 1 Host : guest binding stoichiometry at low sulfate concentration and a 1 : 1 stoichiometry in the presence of excess sulfate. Fluorescence titration demonstrates that the [2]rotaxane is also capable of sensing guest anions via significant changes in its emission spectrum.
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chloride anion templated synthesis of a strapped porphyrin containing catenane Host System
Chemistry: A European Journal, 2015Co-Authors: Asha Brown, Matthew J Langton, Nathan L. Kilah, Amber L. Thompson, Paul D. BeerAbstract:The synthesis, structure and anion-recognition properties of a new strapped-porphyrin-containing [2]catenane anion Host System are described. The assembly of the catenane is directed by discrete chloride anion templation acting in synergy with secondary aromatic donor–acceptor and coordinative pyridine–zinc interactions. The [2]catenane incorporates a three-dimensional, hydrogen-bond-donating anion-binding pocket; solid-state structural analysis of the catenane⋅chloride complex reveals that the chloride anion is encapsulated within the catenane’s interlocked binding cavity through six convergent CH⋅⋅⋅⋅Cl and NH⋅⋅⋅Cl hydrogen-bonding interactions and solution-phase 1H NMR titration experiments demonstrate that this complementary hydrogen-bonding arrangement facilitates the selective recognition of chloride over larger halide anions in DMSO solution.
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nitrate anion templated synthesis of a 2 catenane for nitrate recognition in organic aqueous solvent media
Chemical Communications, 2014Co-Authors: Matthew J Langton, Paul D. BeerAbstract:The first example of a catenane synthesised using a nitrate anion template is demonstrated. Removal of the templating anion reveals a mechanically interlocked molecular Host System which is capable of recognising nitrate selectively over a range of more basic mono-anionic oxoanions in a competitive organic–aqueous solvent mixture.
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a catenane Host System containing integrated triazole c h hydrogen bond donors for anion recognition
Chemical Communications, 2012Co-Authors: Nicholas G White, Paul D. BeerAbstract:A 3,5-bis(triazole)-pyridinium motif is integrated into a catenane structural framework via chloride anion templation. The catenane Host System displays a high degree of selectivity for halide anions over dihydrogen phosphate.
Heinzulrich Reyer - One of the best experts on this subject based on the ideXlab platform.
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food supply modifies the trade off between past and future reproduction in a sexual parasite Host System rana esculenta rana lessonae
Oecologia, 2007Co-Authors: M Waelti, Heinzulrich ReyerAbstract:Life history theory is concerned with the costs of survival, growth and reproduction under different ecological conditions and the allocation of resources to meet these costs. Typical approaches used to address these topics include manipulation of food resources, followed by measures of subsequent reproductive traits, and measures of the relationship between current and future reproductive investment. Rarely, however, do studies test for the interaction of past investment, present resource availability and future investment simultaneously. Here, we investigate this interaction in females of a sexual parasite–Host System consisting of the hybridogenetic frog Rana esculenta (E) and one of its parental species Rana lessonae (L). We kept females from each of two groups (with or without previous reproduction) under two food treatments (low or high) and regularly recorded their growth as well as their body condition and hormone titres as measures of future reproductive condition. After keeping them in hibernation until the following spring, we exposed the females to males, recorded whether they spawned or not and related this response to their condition in the previous autumn. Past reproduction negatively affected growth during summer and condition during autumn which, in turn, reduced the following year’s reproductive output. These costs of previous reproduction were less pronounced under the high than under the low food treatment and lower in R. lessonae than in R. esculenta. Increasing food supply improved reproductive condition more in L than in E females. These species differences in reproductive costs and food requirements provide a mechanistic explanation for why E females skip annual reproduction almost twice as often as L females. Since R. esculenta is a sexual parasite that depends on R. lessonae for successful reproduction, these species-specific life history patterns not only affect individual fitness but also the spatial structure and temporal dynamics of mixed LE populations.
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low proportions of reproducing hemiclonal females increase the stability of a sexual parasite Host System rana esculenta r lessonae
Journal of Animal Ecology, 2004Co-Authors: Heinzulrich Reyer, M O Walti, I Battig, Res Altwegg, B HellriegelAbstract:Summary 1. The number of reproductive events per lifetime affects all levels of ecological complexity, including the structure and dynamics of species communities. Here we investigate a sexual parasite‐Host System with two water frog species of which one ( Rana esculenta , E) is a hemiclonal hybrid that depends on one of its parental species ( R. lessonae , L) for successful reproduction. Previous theoretical models have shown that relative fecundities are important for the species composition and stability of this System, but empirical data from natural mixed LE-populations were lacking. 2. We used three different methods to estimate the proportion of annually reproducing hybrid and parental females: (a) screening for eggs through a tiny incision into the belly skin, (b) measuring plasma hormone titres from blood samples and (c) counts of egg clumps deposited into the pond. 3. After accounting for the respective adult population sizes of the two female types ‐ calculated from mark‐recapture analyses ‐ we found that all three estimates revealed a higher proportion of reproducing L- than E-females. Ratios ranged from 1·43 (method c), to 1·90 (a) to 2·38 (b), with an average of 1·90. 4. We also investigated three potential causes for the fecundity difference (age structure, hybrid sterility and differences in reproductive costs) but could not find compelling evidence for any of them. We hypothesize that size-related differences in energy budgets offer the most probable explanation. 5. The consequences of the observed species differences in annual reproductive success were analysed with a theoretical model. The higher proportion of reproducing R. lessonae females increases the possibilities for stable coexistence in mixed LE-populations under a variety of combinations of mating patterns, relative fecundity and larval performance. The results, however, also indicate new limits for coexistence and highlight the paramount importance of larval competition for explaining the composition and dynamics of mixed LE-populations.
Asha Brown - One of the best experts on this subject based on the ideXlab platform.
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active metal template synthesis of a neutral indolocarbazole containing 2 rotaxane Host System for selective oxoanion recognition
Organic and Biomolecular Chemistry, 2017Co-Authors: Asha Brown, Kathleen M Mullen, Thomas Lang, Paul D. BeerAbstract:An active metal template strategy was used to synthesise a neutral indolocarbazole containing [2]rotaxane anion Host System. 1H NMR anion binding investigations reveal that the [2]rotaxane recognises a range of monoanions in acetone-d5 : D2O 95 : 5 with an unusual interlocked Host selectivity for acetate and dihydrogenphosphate oxoanions over halides. The rotaxane displays an overall selectivity for the sulfate dianion, favouring a 2 : 1 Host : guest binding stoichiometry at low sulfate concentration and a 1 : 1 stoichiometry in the presence of excess sulfate. Fluorescence titration demonstrates that the [2]rotaxane is also capable of sensing guest anions via significant changes in its emission spectrum.
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chloride anion templated synthesis of a strapped porphyrin containing catenane Host System
Chemistry: A European Journal, 2015Co-Authors: Asha Brown, Matthew J Langton, Nathan L. Kilah, Amber L. Thompson, Paul D. BeerAbstract:The synthesis, structure and anion-recognition properties of a new strapped-porphyrin-containing [2]catenane anion Host System are described. The assembly of the catenane is directed by discrete chloride anion templation acting in synergy with secondary aromatic donor–acceptor and coordinative pyridine–zinc interactions. The [2]catenane incorporates a three-dimensional, hydrogen-bond-donating anion-binding pocket; solid-state structural analysis of the catenane⋅chloride complex reveals that the chloride anion is encapsulated within the catenane’s interlocked binding cavity through six convergent CH⋅⋅⋅⋅Cl and NH⋅⋅⋅Cl hydrogen-bonding interactions and solution-phase 1H NMR titration experiments demonstrate that this complementary hydrogen-bonding arrangement facilitates the selective recognition of chloride over larger halide anions in DMSO solution.
Irena Baranowskabosiacka - One of the best experts on this subject based on the ideXlab platform.
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selected molecular mechanisms involved in the parasite Host System hymenolepis diminuta rattus norvegicus
International Journal of Molecular Sciences, 2018Co-Authors: Patrycja Kapczuk, Izabela Gutowska, Patrycja Kupnicka, Dariusz Chlubek, Danuta Kosikbogacka, Natalia łanochaarendarczyk, Irena BaranowskabosiackaAbstract:The rat tapeworm Hymenolepis diminuta is a parasite of the small intestine of rodents (mainly mice and rats), and accidentally humans. It is classified as a non-invasive tapeworm due to the lack of hooks on the tapeworm's scolex, which could cause mechanical damage to Host tissues. However, many studies have shown that metabolites secreted by H. diminuta interfere with the functioning of the Host's gastrointestinal tract, causing an increase in salivary secretion, suppression of gastric acid secretion, and an increase in the trypsin activity in the duodenum chyme. Our work presents the biochemical and molecular mechanisms of a parasite-Host interaction, including the influence on ion transport and Host intestinal microflora, morphology and biochemical parameters of blood, secretion of antioxidant enzymes, expression of Toll-like receptors, mechanisms of immune response, as well as the expression and activity of cyclooxygenases. We emphasize the interrelations between the parasite and the Host at the cellular level resulting from the direct impact of the parasite as well as Host defense reactions that lead to changes in the Host's tissues and organs.
M Waelti - One of the best experts on this subject based on the ideXlab platform.
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food supply modifies the trade off between past and future reproduction in a sexual parasite Host System rana esculenta rana lessonae
Oecologia, 2007Co-Authors: M Waelti, Heinzulrich ReyerAbstract:Life history theory is concerned with the costs of survival, growth and reproduction under different ecological conditions and the allocation of resources to meet these costs. Typical approaches used to address these topics include manipulation of food resources, followed by measures of subsequent reproductive traits, and measures of the relationship between current and future reproductive investment. Rarely, however, do studies test for the interaction of past investment, present resource availability and future investment simultaneously. Here, we investigate this interaction in females of a sexual parasite–Host System consisting of the hybridogenetic frog Rana esculenta (E) and one of its parental species Rana lessonae (L). We kept females from each of two groups (with or without previous reproduction) under two food treatments (low or high) and regularly recorded their growth as well as their body condition and hormone titres as measures of future reproductive condition. After keeping them in hibernation until the following spring, we exposed the females to males, recorded whether they spawned or not and related this response to their condition in the previous autumn. Past reproduction negatively affected growth during summer and condition during autumn which, in turn, reduced the following year’s reproductive output. These costs of previous reproduction were less pronounced under the high than under the low food treatment and lower in R. lessonae than in R. esculenta. Increasing food supply improved reproductive condition more in L than in E females. These species differences in reproductive costs and food requirements provide a mechanistic explanation for why E females skip annual reproduction almost twice as often as L females. Since R. esculenta is a sexual parasite that depends on R. lessonae for successful reproduction, these species-specific life history patterns not only affect individual fitness but also the spatial structure and temporal dynamics of mixed LE populations.