Anna Yañez Oliver - Academia.edu (original) (raw)
Papers by Anna Yañez Oliver
Nature Precedings, 2009
On the basis of 16S rRNA gene sequencing, the SAR11 clade of marine bacteria has almost universal... more On the basis of 16S rRNA gene sequencing, the SAR11 clade of marine bacteria has almost universal distribution, being detected as abundant sequences in all marine provinces. Yet SAR11 sequences are rarely detected in fosmid libraries, suggesting that the widespread abundance may be an artefact of PCR cloning and that SAR 11 has a relatively low abundance. Here the relative abundance of SAR11 is explored in both a fosmid library and a metagenomic sequence data set from the same biological community taken from fjord surface water from Bergen, Norway. Pyrosequenced data and 16S clone data confirmed an 11-15% relative abundance of SAR11 within the community. In contrast not a single SAR11 fosmid was identified in a pooled shotgun sequenced data set of 100 fosmid clones. This under-representation was evidenced by comparative abundances of SAR11 sequences assessed by taxonomic annotation; functional metabolic profiling and fragment recruitment. Analysis revealed a similar under-representa...
Nature Communications, 2018
Soil microbial communities play a crucial role in ecosystem functioning, but it is unknown how co... more Soil microbial communities play a crucial role in ecosystem functioning, but it is unknown how co-occurrence networks within these communities respond to disturbances such as climate extremes. This represents an important knowledge gap because changes in microbial networks could have implications for their functioning and vulnerability to future disturbances. Here, we show in grassland mesocosms that drought promotes destabilising properties in soil bacterial, but not fungal, co-occurrence networks, and that changes in bacterial communities link more strongly to soil functioning during recovery than do changes in fungal communities. Moreover, we reveal that drought has a prolonged effect on bacterial communities and their co-occurrence networks via changes in vegetation composition and resultant reductions in soil moisture. Our results provide new insight in the mechanisms through which drought alters soil microbial communities with potential long-term consequences, including future plant community composition and the ability of aboveground and belowground communities to withstand future disturbances.
Frontiers in Microbiology, 2016
Despite several lines of observational evidence, there is a lack of consensus on whether higher f... more Despite several lines of observational evidence, there is a lack of consensus on whether higher fungal:bacterial (F:B) ratios directly cause higher soil carbon (C) storage. We employed RNA sequencing, protein profiling and isotope tracer techniques to evaluate whether differing F:B ratios are associated with differences in C storage. A mesocosm 13 C labeled foliar litter decomposition experiment was performed in two soils that were similar in their physico-chemical properties but differed in microbial community structure, specifically their F:B ratio (determined by PLFA analyses, RNA sequencing and protein profiling; all three corroborating each other). Following litter addition, we observed a consistent increase in abundance of fungal phyla; and greater increases in the fungal dominated soil; implicating the role of fungi in litter decomposition. Litter derived 13 C in respired CO 2 was consistently lower, and residual 13 C in bulk SOM was higher in high F:B soil demonstrating greater C storage potential in the F:B dominated soil. We conclude that in this soil system, the increased abundance of fungi in both soils and the altered C cycling patterns in the F:B dominated soils highlight the significant role of fungi in litter decomposition and indicate that F:B ratios are linked to higher C storage potential.
Journal of the American Chemical Society Jacs, 2004
The identification of spatial patterns and their relationships to ecological events is an importa... more The identification of spatial patterns and their relationships to ecological events is an important specialization within ecology which is now branching into the microbial world. In spatial ecology, the detection of patterns at a given spatial scale can be used to explain ecological mechanisms and processes. Furthermore, through the application of spatial statistical analyses, factors leading to ecological events can be determined and verified. One of the most commonly studied aspects of spatial ecology, recently applied in microbial ecology, is the species–area relationship (SAR). The temporal analogue of the SAR, the species–time relationship (STR), on the other hand has received far less attention, even in the science of general ecology. Like SARs, the STRs are influenced by a variety of factors including dispersal, abiotic and biotic interactions, and species-species interactions. The application of these ecological conceptual tools to microbial ecology is a rapidly developing field. This chapter proposes that the STRs are a powerful and appropriate tool for studies of microbial diversity and that they make a contribution to understanding ecological communities. From a fundamental perspective, we focus on how microbial STRs compare with those for animals and plant communities, and how they are improving our understanding of community assembly and dynamics. As we believe a key future importance of studying STRs will be for applied benefit, we also discuss how microbial STRs have been used to distinguish between anthropogenic perturbations and underlying natural dynamics and have provided ecological insights for clinical benefit in bacterial infections.
Molecular Ecology, 2016
This document is the author's final manuscript version of the journal article, incorporating any ... more This document is the author's final manuscript version of the journal article, incorporating any revisions agreed during the peer review process. There may be differences between this and the publisher's version. You are advised to consult the publisher's version if you wish to cite from this article.
Journal of the Chemical Society, Perkin Transactions 2, 1996
A series of norbornane- and bicyclo[2.2.2]octane-fused tetracyanonaphthoquinodimethane (benzoTCNQ... more A series of norbornane- and bicyclo[2.2.2]octane-fused tetracyanonaphthoquinodimethane (benzoTCNQ) derivatives, 4,6,8,10 and 12 has been synthesized. Cyclic voltammetry measurements revealed two one-electron reduction waves for the benzo-TCNQ systems 4, 8 and 10 which possess either a cyclobutane or a norbornane moiety fused to the quinonoid ring, but a single (presumably two-electron) reduction wave for 6 and 12 which possess a bicyclo[2.2.2]octane group fused to the gmnonoid ring. The benzo-TCNQ systems were found to be potent electron acceptors. The results of (U)HF/3-21G calculations carried out on representative benzo-TCNQ derivatives suggest that steric interactions between the quinonoid ring and its adjacent fused alicyclic group are largely responsible for the observed decrease in the electron affinities along the series: 8 > 4 > 6. The MO calculations further suggest that LUMO energies of neutral TCNQ derivatives are qualitatively reliable predictors of electron affinities. The calculated (gas phase) internal reorganization energies, λi, for the benzo-TCNQ systems are ca. 54 kJ mol–1 and are comparable to that calculated for the dicyanovinyl (DCV) system, 27. The similarity between the λi values for the benzo-TCNQ systems and 27, together with the experimental finding that benzo-TCNQ systems are reduced at ca. 1.7 V less negative potentials than 27, should make the norbornane- and bicyclo [2.2.2] octane-benzo-TCNQ systems superior to the DCV moiety as acceptor chromophores in giant multichromophoric systems.
The ISME Journal, 2015
Pulmonary symptoms in cystic fibrosis (CF) begin in early life with chronic lung infections and c... more Pulmonary symptoms in cystic fibrosis (CF) begin in early life with chronic lung infections and concomitant airway inflammation leading to progressive loss of lung function. Gradual pulmonary function decline is interspersed with periods of acute worsening of respiratory symptoms known as CF pulmonary exacerbations (CFPEs). Cumulatively, CFPEs are associated with more rapid disease progression. In this study multiple sputum samples were collected from adult CF patients over the course of CFPEs to better understand how changes in microbiota are associated with CFPE onset and management. Data were divided into five clinical periods: pre-CFPE baseline, CFPE, antibiotic treatment, recovery, and post-CFPE baseline. Samples were treated with propidium monoazide prior to DNA extraction, to remove the impact of bacterial cell death artefacts following antibiotic treatment, and then characterised by 16S rRNA gene-targeted high-throughput sequencing. Partitioning CF microbiota into core and rare groups revealed compositional resistance to CFPE and resilience to antibiotics interventions. Mixed effects modelling of core microbiota members revealed no significant negative impact on the relative abundance of Pseudomonas aeruginosa across the exacerbation cycle. Our findings have implications for current CFPE management strategies, supporting reassessment of existing antimicrobial treatment regimens, as antimicrobial resistance by pathogens and other members of the microbiota may be significant contributing factors.
Journal of the Chemical Society, Perkin Transactions 2, 1989
Environmental Microbiology Reports, 2015
This document is the author's final manuscript version of the journal article, incorporating any ... more This document is the author's final manuscript version of the journal article, incorporating any revisions agreed during the peer review process. There may be differences between this and the publisher's version. You are advised to consult the publisher's version if you wish to cite from this article.
Methods in Ecology and Evolution, 2015
1. Studying fungal biodiversity using data generated from Illumina MiSeq sequencing platforms pos... more 1. Studying fungal biodiversity using data generated from Illumina MiSeq sequencing platforms poses a number of bioinformatic challenges with the analysis typically involving a large number of tools for each analytical step from quality filtering to generating identified operational taxonomic unit (OTU) abundance tables. 2. Here, we introduce PIPITS, an open-source stand-alone suite of software for automated processing of Illumina MiSeq sequences for fungal community analysis. PIPITS exploits a number of state of the art applications to process paired-end reads from quality filtering to producing OTU abundance tables. 3. We provide detailed descriptions of the pipeline and show its utility in the analysis of 9 396 092 sequences generated on the MiSeq platform from Illumina MiSeq. 4. PIPITS is the first automated bioinformatics pipeline dedicated for fungal ITS sequences which incorporates ITSx to extract subregions of ITS and exploits the latest RDP Classifier to classify sequences against the curated UNITE fungal data set.
Environmental Microbiology Reports, 2014
It is well established that the release of anthropogenic derived CO 2 into the atmosphere will be... more It is well established that the release of anthropogenic derived CO 2 into the atmosphere will be mainly absorbed by the oceans, with a concomitant drop in pH; a process termed ocean acidification. As such, there is considerable interest in how changes in increased CO 2 and lower pH will affect marine biota, such as bacteria, which play central roles in oceanic biogeochemical processes. Set within an ecological framework, we investigated the direct effects of elevated CO 2 , contrasted with ambient conditions, on the resistance and resilience of marine bacterial communities in a replicated temporal seawater mesocosm experiment. The results of the study strongly indicate that marine bacterial communities are highly resistant to the elevated CO 2 and lower pH conditions imposed, as demonstrated from measures of turnover using taxa-time relationships and distance-decayrelationships. In addition, no significant differences in community abundance, structure or composition were observed. Our results suggest that there are no direct effects on marine bacterial communities and that the bacterial fraction of microbial plankton holds enough flexibility and evolutionary capacity to withstand predicted future changes from elevated CO 2 and subsequent ocean acidification.
The Journal of Physical Chemistry, 1993
The temperature dependence of electron transfer over a wide range of driving forces extending fro... more The temperature dependence of electron transfer over a wide range of driving forces extending from far in the “normal” to deep into the “inverted” region is studied with the aid of a limited number of closely related and fully rigid bridged donor-acceptor systems. The ...
J. Chem. Soc., Perkin Trans. 1, 1990
The synthesis and single crystal X-ray structures of three rigid bichromophoric systems are descr... more The synthesis and single crystal X-ray structures of three rigid bichromophoric systems are described, namely the dicyanovinyl derivatives of 7,12-dimethoxydodecahydro-1,4:6,13-dimethanopentacen-15-one, 3, 8,13-dimethoxyhexadecahydro-1,4:5,16:6,17:7, 14-tetramethanohexacen-17-one, 4 and 6,11-dimethoxy-4b, 12b-dimethyldodecahydro-4,13;5,12-dimethano-2H-indeno-[5′,6′:3′,4′]cyclo-buta[1′,2′:3,4]cyclobuta[1,2-b]anthracen-2-one 5. Compounds 3 and 4 were synthesized from dimethanonaphthacene 8via Diels–Alder reaction with tetrachlorodimethoxycyclopentadiene 9(in the case of 3) and via successive Diels–Alder reactions, firstly with hexachlorocyclopentadiene, 14, and then with 9, in the case of 4. The synthesis of 5 was achieved through ring expansion of the dichloroketene [2 + 2] cycloadduct formed from 21. Differences in the rates of photoinduced intramolecular electron transfer in 3–5, compared with those for 1 and 2, are rationalized in terms of the differing configurations of the hydrocarbon bridges in these systems, as revealed by X-ray crystallography.
Tetrahedron, 1995
A method is described for constructing totally rigid triad (nichromophoric) systems, D2-B1-D1-B2-... more A method is described for constructing totally rigid triad (nichromophoric) systems, D2-B1-D1-B2-A, in which the chromophores D2 (= dimethylaniline), D1 (= 1,4-dimethoxynaphthalene), and A (= dicyanovinyl) are fused to rigid hydrocarbon bridges, B1 and B2, comprising linearly fused norbornane and bicyclo[2.2.0]hexane units.
Journal of Cystic Fibrosis, 2015
Background-Best practice when performing culture-independent microbiological analysis of sputum s... more Background-Best practice when performing culture-independent microbiological analysis of sputum samples involves their rapid freezing and storage at −80 °C. However, accessing biobanked collections can mean that material has been passed through repeated freeze-thaw cycles. The aim of this study was to determine the impact of these cycles on microbial community profiles. Methods-Sputum was collected from eight adults with cystic fibrosis, and each sample was subjected to six freeze-thaw cycles. Following each cycle, an aliquot was removed and treated with propidium monoazide (PMA) prior to DNA extraction and 16S rRNA gene pyrosequencing. Results-The impact of freeze-thaw cycles was greatest on rare members of the microbiota, with variation beyond that detected with within-sample repeat analysis observed after three cycles.
The Journal of Physical Chemistry, 1988
Factors Affecting Charge Separation and Recombination in Photoexcited Rigid ... Michael N. Paddon... more Factors Affecting Charge Separation and Recombination in Photoexcited Rigid ... Michael N. Paddon-Row,* Anna M. Oliver: Department of Chemistry, University of New South Wales, PO Box I , Kensington NSW 2033, Australia ... John M. Warman,* Kenneth J. Smit, ...
Nature Precedings, 2009
On the basis of 16S rRNA gene sequencing, the SAR11 clade of marine bacteria has almost universal... more On the basis of 16S rRNA gene sequencing, the SAR11 clade of marine bacteria has almost universal distribution, being detected as abundant sequences in all marine provinces. Yet SAR11 sequences are rarely detected in fosmid libraries, suggesting that the widespread abundance may be an artefact of PCR cloning and that SAR 11 has a relatively low abundance. Here the relative abundance of SAR11 is explored in both a fosmid library and a metagenomic sequence data set from the same biological community taken from fjord surface water from Bergen, Norway. Pyrosequenced data and 16S clone data confirmed an 11-15% relative abundance of SAR11 within the community. In contrast not a single SAR11 fosmid was identified in a pooled shotgun sequenced data set of 100 fosmid clones. This under-representation was evidenced by comparative abundances of SAR11 sequences assessed by taxonomic annotation; functional metabolic profiling and fragment recruitment. Analysis revealed a similar under-representa...
Nature Communications, 2018
Soil microbial communities play a crucial role in ecosystem functioning, but it is unknown how co... more Soil microbial communities play a crucial role in ecosystem functioning, but it is unknown how co-occurrence networks within these communities respond to disturbances such as climate extremes. This represents an important knowledge gap because changes in microbial networks could have implications for their functioning and vulnerability to future disturbances. Here, we show in grassland mesocosms that drought promotes destabilising properties in soil bacterial, but not fungal, co-occurrence networks, and that changes in bacterial communities link more strongly to soil functioning during recovery than do changes in fungal communities. Moreover, we reveal that drought has a prolonged effect on bacterial communities and their co-occurrence networks via changes in vegetation composition and resultant reductions in soil moisture. Our results provide new insight in the mechanisms through which drought alters soil microbial communities with potential long-term consequences, including future plant community composition and the ability of aboveground and belowground communities to withstand future disturbances.
Frontiers in Microbiology, 2016
Despite several lines of observational evidence, there is a lack of consensus on whether higher f... more Despite several lines of observational evidence, there is a lack of consensus on whether higher fungal:bacterial (F:B) ratios directly cause higher soil carbon (C) storage. We employed RNA sequencing, protein profiling and isotope tracer techniques to evaluate whether differing F:B ratios are associated with differences in C storage. A mesocosm 13 C labeled foliar litter decomposition experiment was performed in two soils that were similar in their physico-chemical properties but differed in microbial community structure, specifically their F:B ratio (determined by PLFA analyses, RNA sequencing and protein profiling; all three corroborating each other). Following litter addition, we observed a consistent increase in abundance of fungal phyla; and greater increases in the fungal dominated soil; implicating the role of fungi in litter decomposition. Litter derived 13 C in respired CO 2 was consistently lower, and residual 13 C in bulk SOM was higher in high F:B soil demonstrating greater C storage potential in the F:B dominated soil. We conclude that in this soil system, the increased abundance of fungi in both soils and the altered C cycling patterns in the F:B dominated soils highlight the significant role of fungi in litter decomposition and indicate that F:B ratios are linked to higher C storage potential.
Journal of the American Chemical Society Jacs, 2004
The identification of spatial patterns and their relationships to ecological events is an importa... more The identification of spatial patterns and their relationships to ecological events is an important specialization within ecology which is now branching into the microbial world. In spatial ecology, the detection of patterns at a given spatial scale can be used to explain ecological mechanisms and processes. Furthermore, through the application of spatial statistical analyses, factors leading to ecological events can be determined and verified. One of the most commonly studied aspects of spatial ecology, recently applied in microbial ecology, is the species–area relationship (SAR). The temporal analogue of the SAR, the species–time relationship (STR), on the other hand has received far less attention, even in the science of general ecology. Like SARs, the STRs are influenced by a variety of factors including dispersal, abiotic and biotic interactions, and species-species interactions. The application of these ecological conceptual tools to microbial ecology is a rapidly developing field. This chapter proposes that the STRs are a powerful and appropriate tool for studies of microbial diversity and that they make a contribution to understanding ecological communities. From a fundamental perspective, we focus on how microbial STRs compare with those for animals and plant communities, and how they are improving our understanding of community assembly and dynamics. As we believe a key future importance of studying STRs will be for applied benefit, we also discuss how microbial STRs have been used to distinguish between anthropogenic perturbations and underlying natural dynamics and have provided ecological insights for clinical benefit in bacterial infections.
Molecular Ecology, 2016
This document is the author's final manuscript version of the journal article, incorporating any ... more This document is the author's final manuscript version of the journal article, incorporating any revisions agreed during the peer review process. There may be differences between this and the publisher's version. You are advised to consult the publisher's version if you wish to cite from this article.
Journal of the Chemical Society, Perkin Transactions 2, 1996
A series of norbornane- and bicyclo[2.2.2]octane-fused tetracyanonaphthoquinodimethane (benzoTCNQ... more A series of norbornane- and bicyclo[2.2.2]octane-fused tetracyanonaphthoquinodimethane (benzoTCNQ) derivatives, 4,6,8,10 and 12 has been synthesized. Cyclic voltammetry measurements revealed two one-electron reduction waves for the benzo-TCNQ systems 4, 8 and 10 which possess either a cyclobutane or a norbornane moiety fused to the quinonoid ring, but a single (presumably two-electron) reduction wave for 6 and 12 which possess a bicyclo[2.2.2]octane group fused to the gmnonoid ring. The benzo-TCNQ systems were found to be potent electron acceptors. The results of (U)HF/3-21G calculations carried out on representative benzo-TCNQ derivatives suggest that steric interactions between the quinonoid ring and its adjacent fused alicyclic group are largely responsible for the observed decrease in the electron affinities along the series: 8 > 4 > 6. The MO calculations further suggest that LUMO energies of neutral TCNQ derivatives are qualitatively reliable predictors of electron affinities. The calculated (gas phase) internal reorganization energies, λi, for the benzo-TCNQ systems are ca. 54 kJ mol–1 and are comparable to that calculated for the dicyanovinyl (DCV) system, 27. The similarity between the λi values for the benzo-TCNQ systems and 27, together with the experimental finding that benzo-TCNQ systems are reduced at ca. 1.7 V less negative potentials than 27, should make the norbornane- and bicyclo [2.2.2] octane-benzo-TCNQ systems superior to the DCV moiety as acceptor chromophores in giant multichromophoric systems.
The ISME Journal, 2015
Pulmonary symptoms in cystic fibrosis (CF) begin in early life with chronic lung infections and c... more Pulmonary symptoms in cystic fibrosis (CF) begin in early life with chronic lung infections and concomitant airway inflammation leading to progressive loss of lung function. Gradual pulmonary function decline is interspersed with periods of acute worsening of respiratory symptoms known as CF pulmonary exacerbations (CFPEs). Cumulatively, CFPEs are associated with more rapid disease progression. In this study multiple sputum samples were collected from adult CF patients over the course of CFPEs to better understand how changes in microbiota are associated with CFPE onset and management. Data were divided into five clinical periods: pre-CFPE baseline, CFPE, antibiotic treatment, recovery, and post-CFPE baseline. Samples were treated with propidium monoazide prior to DNA extraction, to remove the impact of bacterial cell death artefacts following antibiotic treatment, and then characterised by 16S rRNA gene-targeted high-throughput sequencing. Partitioning CF microbiota into core and rare groups revealed compositional resistance to CFPE and resilience to antibiotics interventions. Mixed effects modelling of core microbiota members revealed no significant negative impact on the relative abundance of Pseudomonas aeruginosa across the exacerbation cycle. Our findings have implications for current CFPE management strategies, supporting reassessment of existing antimicrobial treatment regimens, as antimicrobial resistance by pathogens and other members of the microbiota may be significant contributing factors.
Journal of the Chemical Society, Perkin Transactions 2, 1989
Environmental Microbiology Reports, 2015
This document is the author's final manuscript version of the journal article, incorporating any ... more This document is the author's final manuscript version of the journal article, incorporating any revisions agreed during the peer review process. There may be differences between this and the publisher's version. You are advised to consult the publisher's version if you wish to cite from this article.
Methods in Ecology and Evolution, 2015
1. Studying fungal biodiversity using data generated from Illumina MiSeq sequencing platforms pos... more 1. Studying fungal biodiversity using data generated from Illumina MiSeq sequencing platforms poses a number of bioinformatic challenges with the analysis typically involving a large number of tools for each analytical step from quality filtering to generating identified operational taxonomic unit (OTU) abundance tables. 2. Here, we introduce PIPITS, an open-source stand-alone suite of software for automated processing of Illumina MiSeq sequences for fungal community analysis. PIPITS exploits a number of state of the art applications to process paired-end reads from quality filtering to producing OTU abundance tables. 3. We provide detailed descriptions of the pipeline and show its utility in the analysis of 9 396 092 sequences generated on the MiSeq platform from Illumina MiSeq. 4. PIPITS is the first automated bioinformatics pipeline dedicated for fungal ITS sequences which incorporates ITSx to extract subregions of ITS and exploits the latest RDP Classifier to classify sequences against the curated UNITE fungal data set.
Environmental Microbiology Reports, 2014
It is well established that the release of anthropogenic derived CO 2 into the atmosphere will be... more It is well established that the release of anthropogenic derived CO 2 into the atmosphere will be mainly absorbed by the oceans, with a concomitant drop in pH; a process termed ocean acidification. As such, there is considerable interest in how changes in increased CO 2 and lower pH will affect marine biota, such as bacteria, which play central roles in oceanic biogeochemical processes. Set within an ecological framework, we investigated the direct effects of elevated CO 2 , contrasted with ambient conditions, on the resistance and resilience of marine bacterial communities in a replicated temporal seawater mesocosm experiment. The results of the study strongly indicate that marine bacterial communities are highly resistant to the elevated CO 2 and lower pH conditions imposed, as demonstrated from measures of turnover using taxa-time relationships and distance-decayrelationships. In addition, no significant differences in community abundance, structure or composition were observed. Our results suggest that there are no direct effects on marine bacterial communities and that the bacterial fraction of microbial plankton holds enough flexibility and evolutionary capacity to withstand predicted future changes from elevated CO 2 and subsequent ocean acidification.
The Journal of Physical Chemistry, 1993
The temperature dependence of electron transfer over a wide range of driving forces extending fro... more The temperature dependence of electron transfer over a wide range of driving forces extending from far in the “normal” to deep into the “inverted” region is studied with the aid of a limited number of closely related and fully rigid bridged donor-acceptor systems. The ...
J. Chem. Soc., Perkin Trans. 1, 1990
The synthesis and single crystal X-ray structures of three rigid bichromophoric systems are descr... more The synthesis and single crystal X-ray structures of three rigid bichromophoric systems are described, namely the dicyanovinyl derivatives of 7,12-dimethoxydodecahydro-1,4:6,13-dimethanopentacen-15-one, 3, 8,13-dimethoxyhexadecahydro-1,4:5,16:6,17:7, 14-tetramethanohexacen-17-one, 4 and 6,11-dimethoxy-4b, 12b-dimethyldodecahydro-4,13;5,12-dimethano-2H-indeno-[5′,6′:3′,4′]cyclo-buta[1′,2′:3,4]cyclobuta[1,2-b]anthracen-2-one 5. Compounds 3 and 4 were synthesized from dimethanonaphthacene 8via Diels–Alder reaction with tetrachlorodimethoxycyclopentadiene 9(in the case of 3) and via successive Diels–Alder reactions, firstly with hexachlorocyclopentadiene, 14, and then with 9, in the case of 4. The synthesis of 5 was achieved through ring expansion of the dichloroketene [2 + 2] cycloadduct formed from 21. Differences in the rates of photoinduced intramolecular electron transfer in 3–5, compared with those for 1 and 2, are rationalized in terms of the differing configurations of the hydrocarbon bridges in these systems, as revealed by X-ray crystallography.
Tetrahedron, 1995
A method is described for constructing totally rigid triad (nichromophoric) systems, D2-B1-D1-B2-... more A method is described for constructing totally rigid triad (nichromophoric) systems, D2-B1-D1-B2-A, in which the chromophores D2 (= dimethylaniline), D1 (= 1,4-dimethoxynaphthalene), and A (= dicyanovinyl) are fused to rigid hydrocarbon bridges, B1 and B2, comprising linearly fused norbornane and bicyclo[2.2.0]hexane units.
Journal of Cystic Fibrosis, 2015
Background-Best practice when performing culture-independent microbiological analysis of sputum s... more Background-Best practice when performing culture-independent microbiological analysis of sputum samples involves their rapid freezing and storage at −80 °C. However, accessing biobanked collections can mean that material has been passed through repeated freeze-thaw cycles. The aim of this study was to determine the impact of these cycles on microbial community profiles. Methods-Sputum was collected from eight adults with cystic fibrosis, and each sample was subjected to six freeze-thaw cycles. Following each cycle, an aliquot was removed and treated with propidium monoazide (PMA) prior to DNA extraction and 16S rRNA gene pyrosequencing. Results-The impact of freeze-thaw cycles was greatest on rare members of the microbiota, with variation beyond that detected with within-sample repeat analysis observed after three cycles.
The Journal of Physical Chemistry, 1988
Factors Affecting Charge Separation and Recombination in Photoexcited Rigid ... Michael N. Paddon... more Factors Affecting Charge Separation and Recombination in Photoexcited Rigid ... Michael N. Paddon-Row,* Anna M. Oliver: Department of Chemistry, University of New South Wales, PO Box I , Kensington NSW 2033, Australia ... John M. Warman,* Kenneth J. Smit, ...