Publications by authors named "Roland Geyer"

42 Publications

Synthetic microfiber emissions to land rival those to waterbodies and are growing.

PLoS One 2020 16;15(9):e0237839. Epub 2020 Sep 16.

Bren School of Environmental Science and Management, University of California, Santa Barbara, CA, United States of America.

Synthetic microfibers are found virtually everywhere in the environment, but emission pathways and quantities are poorly understood. By connecting regionalized global datasets on apparel production, use, and washing with emission and retention rates during washing, wastewater treatment, and sludge management, we estimate that 5.6 Mt of synthetic microfibers were emitted from apparel washing between 1950 and 2016. Half of this amount was emitted during the last decade, with a compound annual growth rate of 12.9%. Waterbodies received 2.9 Mt, while combined emissions to terrestrial environments (1.9 Mt) and landfill (0.6 Mt) were almost as large and are growing. Annual emissions to terrestrial environments (141.9 kt yr-1) and landfill (34.6 kt yr-1) combined are now exceeding those to waterbodies (167.2 kt yr-1). Improving access to wastewater treatment is expected to further shift synthetic microfiber emissions from waterbodies to terrestrial environments. Preventing emissions at the source would therefore be a more effective mitigation measure.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0237839PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7494121PMC
October 2020

Environmental Benefits of Novel Nonhuman Food Inputs to Salmon Feeds.

Environ Sci Technol 2019 02 31;53(4):1967-1975. Epub 2019 Jan 31.

Bren School of Environmental Science and Management , University of California , Santa Barbara , California 93106 , United States.

Global population growth and changing diets increase the importance, and challenges, of reducing the environmental impacts of food production. Farmed seafood is a relatively efficient way to produce protein and has already overtaken wild fisheries. The use of protein-rich food crops, such as soy, instead of fishmeal in aquaculture feed diverts these important protein sources away from direct human consumption and creates new environmental challenges. Single cell proteins (SCPs), including bacteria and yeast, have recently emerged as replacements for plant-based proteins in salmon feeds. Attributional life cycle assessment is used to compare salmon feeds based on protein from soy, methanotrophic bacteria, and yeast ingredients. All ingredients are modeled at the industrial production scale and compared based on seven resource use and emissions indicators. Yeast protein concentrate showed drastically lower impacts in all categories compared to soy protein concentrate. Bacteria meal also had lower impacts than soy protein concentrate for five of the seven indicators. When these target meals were incorporated into complete feeds the relative trends remain fairly constant, but benefits of the novel ingredients are dampened by high impacts from the nontarget ingredients. Particularly, primary production requirements (PPR) are about equal and constant across all feeds for both analyses since PPR was driven by fishmeal and oil. The bacteria-based feed has the highest climate change impacts due to the use of methane to feed the bacteria who then release carbon dioxide. Overall, the results of this study suggest that incorporating SCP ingredients into salmon feeds can help reduce the environmental impacts of salmon production. Continued improvements in SCP production would further increase the sustainability of salmon farming.
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http://dx.doi.org/10.1021/acs.est.8b03832DOI Listing
February 2019

Production, use, and fate of all plastics ever made.

Sci Adv 2017 07 19;3(7):e1700782. Epub 2017 Jul 19.

Sea Education Association, Woods Hole, MA 02543, USA.

Plastics have outgrown most man-made materials and have long been under environmental scrutiny. However, robust global information, particularly about their end-of-life fate, is lacking. By identifying and synthesizing dispersed data on production, use, and end-of-life management of polymer resins, synthetic fibers, and additives, we present the first global analysis of all mass-produced plastics ever manufactured. We estimate that 8300 million metric tons (Mt) as of virgin plastics have been produced to date. As of 2015, approximately 6300 Mt of plastic waste had been generated, around 9% of which had been recycled, 12% was incinerated, and 79% was accumulated in landfills or the natural environment. If current production and waste management trends continue, roughly 12,000 Mt of plastic waste will be in landfills or in the natural environment by 2050.
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http://dx.doi.org/10.1126/sciadv.1700782DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5517107PMC
July 2017

Life Cycle Assessment of Solar Photovoltaic Microgrid Systems in Off-Grid Communities.

Environ Sci Technol 2017 01 23;51(2):1043-1052. Epub 2016 Dec 23.

First Solar , 350 W. Washington St., Suite 600, Tempe, Arizona 85281, United States.

Access to a reliable source of electricity creates significant benefits for developing communities. Smaller versions of electricity grids, known as microgrids, have been developed as a solution to energy access problems. Using attributional life cycle assessment, this project evaluates the environmental and energy impacts of three photovoltiac (PV) microgrids compared to other energy options for a model village in Kenya. When normalized per kilowatt hour of electricity consumed, PV microgrids, particularly PV-battery systems, have lower impacts than other energy access solutions in climate change, particulate matter, photochemical oxidants, and terrestrial acidification. When compared to small-scale diesel generators, PV-battery systems save 94-99% in the above categories. When compared to the marginal electricity grid in Kenya, PV-battery systems save 80-88%. Contribution analysis suggests that electricity and primary metal use during component, particularly battery, manufacturing are the largest contributors to overall PV-battery microgrid impacts. Accordingly, additional savings could be seen from changing battery manufacturing location and ensuring end of life recycling. Overall, this project highlights the potential for PV microgrids to be feasible, adaptable, long-term energy access solutions, with health and environmental advantages compared to traditional electrification options.
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http://dx.doi.org/10.1021/acs.est.6b05455DOI Listing
January 2017

Development of rubber-enriched dandelion varieties by metabolic engineering of the inulin pathway.

Plant Biotechnol J 2017 Jun 9;15(6):740-753. Epub 2017 Feb 9.

Fraunhofer Institute for Molecular Biology and Applied Ecology (IME), Muenster, Germany.

Natural rubber (NR) is an important raw material for a large number of industrial products. The primary source of NR is the rubber tree Hevea brasiliensis, but increased worldwide demand means that alternative sustainable sources are urgently required. The Russian dandelion (Taraxacum koksaghyz Rodin) is such an alternative because large amounts of NR are produced in its root system. However, rubber biosynthesis must be improved to develop T. koksaghyz into a commercially feasible crop. In addition to NR, T. koksaghyz also produces large amounts of the reserve carbohydrate inulin, which is stored in parenchymal root cell vacuoles near the phloem, adjacent to apoplastically separated laticifers. In contrast to NR, which accumulates throughout the year even during dormancy, inulin is synthesized during the summer and is degraded from the autumn onwards when root tissues undergo a sink-to-source transition. We carried out a comprehensive analysis of inulin and NR metabolism in T. koksaghyz and its close relative T. brevicorniculatum and functionally characterized the key enzyme fructan 1-exohydrolase (1-FEH), which catalyses the degradation of inulin to fructose and sucrose. The constitutive overexpression of Tk1-FEH almost doubled the rubber content in the roots of two dandelion species without any trade-offs in terms of plant fitness. To our knowledge, this is the first study showing that energy supplied by the reserve carbohydrate inulin can be used to promote the synthesis of NR in dandelions, providing a basis for the breeding of rubber-enriched varieties for industrial rubber production.
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http://dx.doi.org/10.1111/pbi.12672DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5425391PMC
June 2017

Does centrifugation matter? Centrifugal force and spinning time alter the plasma metabolome.

Metabolomics 2016 15;12(10):159. Epub 2016 Sep 15.

University Institute of Clinical Chemistry, Inselspital, Bern University Hospital, University of Bern, INO F, 3010 Bern, Switzerland.

Background: Centrifugation is an indispensable procedure for plasma sample preparation, but applied conditions can vary between labs.

Aim: Determine whether routinely used plasma centrifugation protocols (1500× 10 min; 3000× 5 min) influence non-targeted metabolomic analyses.

Methods: Nuclear magnetic resonance spectroscopy (NMR) and High Resolution Mass Spectrometry (HRMS) data were evaluated with sparse partial least squares discriminant analyses and compared with cell count measurements.

Results: Besides significant differences in platelet count, we identified substantial alterations in NMR and HRMS data related to the different centrifugation protocols.

Conclusion: Already minor differences in plasma centrifugation can significantly influence metabolomic patterns and potentially bias metabolomics studies.
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http://dx.doi.org/10.1007/s11306-016-1109-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5025507PMC
September 2016

Conformational Restriction and Enantioseparation Increase Potency and Selectivity of Cyanoguanidine-Type Histamine H4 Receptor Agonists.

J Med Chem 2016 Apr 5;59(7):3452-70. Epub 2016 Apr 5.

Institute of Pharmacy, Pharmaceutical/Medicinal Chemistry, Faculty of Chemistry and Pharmacy, University of Regensburg , Universitätsstraße 31, D-93053 Regensburg, Germany.

2-Cyano-1-[4-(1H-imidazol-4-yl)butyl]-3-[2-(phenylsulfanyl)ethyl]guanidine (UR-PI376, 1) is a potent and selective agonist of the human histamine H4 receptor (hH4R). To gain information on the active conformation, we synthesized analogues of 1 with a cyclopentane-1,3-diyl linker. Affinities and functional activities were determined at recombinant hHxR (x: 1-4) subtypes on Sf9 cell membranes (radioligand binding, [(35)S]GTPγS, or GTPase assays) and in part in luciferase assays on human or mouse H4R (HEK-293 cells). The most potent H4R agonists among 14 racemates were separated by chiral HPLC, yielding eight enantiomerically pure compounds. Configurations were assigned based on X-ray structures of intermediates and a stereocontrolled synthetic pathway. (+)-2-Cyano-1-{[trans-(1S,3S)-3-(1H-imidazol-4-yl)cyclopentyl]methyl}-3-[2-(phenylsulfanyl)ethyl]guanidine ((1S,3S)-UR-RG98, 39a) was the most potent H4R agonist in this series (EC50 11 nM; H4R vs H3R, >100-fold selectivity; H1R, H2R, negligible activities), whereas the optical antipode proved to be an H4R antagonist ([(35)S]GTPγS assay). MD simulations confirmed differential stabilization of the active and inactive H4R state by the enantiomers.
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http://dx.doi.org/10.1021/acs.jmedchem.6b00120DOI Listing
April 2016

Investigating the Energy-Water Usage Efficiency of the Reuse of Treated Municipal Wastewater for Artificial Groundwater Recharge.

Environ Sci Technol 2016 Feb 26;50(4):2044-53. Epub 2016 Jan 26.

Bren School of Environmental Science & Management, University of California at Santa Barbara , Santa Barbara, California 93106-5131, United States.

This project investigates the energy-water usage efficiency of large scale civil infrastructure projects involving the artificial recharge of subsurface groundwater aquifers via the reuse of treated municipal wastewater. A modeling framework is introduced which explores the various ways in which spatially heterogeneous variables such as topography, landuse, and subsurface infiltration capacity combine to determine the physical layout of proposed reuse system components and their associated process energy-water demands. This framework is applied to the planning and evaluation of the energy-water usage efficiency of hypothetical reuse systems in five case study regions within the State of California. Findings from these case study analyses suggest that, in certain geographic contexts, the water requirements attributable to the process energy consumption of a reuse system can exceed the volume of water that it is able to recover by as much as an order of magnitude.
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http://dx.doi.org/10.1021/acs.est.5b04465DOI Listing
February 2016

Molecular Mechanisms by Which a Fucus vesiculosus Extract Mediates Cell Cycle Inhibition and Cell Death in Pancreatic Cancer Cells.

Mar Drugs 2015 Jul 20;13(7):4470-91. Epub 2015 Jul 20.

Division of Molecular Oncology, Institute for Experimental Cancer Research, Medical Faculty, CAU, University Hospital Schleswig-Holstein, 24105 Kiel, Germany.

Pancreatic cancer is one of the most aggressive cancer entities, with an extremely poor 5-year survival rate. Therefore, novel therapeutic agents with specific modes of action are urgently needed. Marine organisms represent a promising source to identify new pharmacologically active substances. Secondary metabolites derived from marine algae are of particular interest. The present work describes cellular and molecular mechanisms induced by an HPLC-fractionated, hydrophilic extract derived from the Baltic brown seaweed Fucus vesiculosus (Fv1). Treatment with Fv1 resulted in a strong inhibition of viability in various pancreatic cancer cell lines. This extract inhibited the cell cycle of proliferating cells due to the up-regulation of cell cycle inhibitors, shown on the mRNA (microarray data) and protein level. As a result, cells were dying in a caspase-independent manner. Experiments with non-dividing cells showed that proliferation is a prerequisite for the effectiveness of Fv1. Importantly, Fv1 showed low cytotoxic activity against non-malignant resting T cells and terminally differentiated cells like erythrocytes. Interestingly, accelerated killing effects were observed in combination with inhibitors of autophagy. Our in vitro data suggest that Fv1 may represent a promising new agent that deserves further development towards clinical application.
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http://dx.doi.org/10.3390/md13074470DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4515628PMC
July 2015

Marine pollution. Plastic waste inputs from land into the ocean.

Science 2015 Feb;347(6223):768-71

Sea Education Association, Woods Hole, MA 02543, USA.

Plastic debris in the marine environment is widely documented, but the quantity of plastic entering the ocean from waste generated on land is unknown. By linking worldwide data on solid waste, population density, and economic status, we estimated the mass of land-based plastic waste entering the ocean. We calculate that 275 million metric tons (MT) of plastic waste was generated in 192 coastal countries in 2010, with 4.8 to 12.7 million MT entering the ocean. Population size and the quality of waste management systems largely determine which countries contribute the greatest mass of uncaptured waste available to become plastic marine debris. Without waste management infrastructure improvements, the cumulative quantity of plastic waste available to enter the ocean from land is predicted to increase by an order of magnitude by 2025.
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http://dx.doi.org/10.1126/science.1260352DOI Listing
February 2015

Synthesis and functional characterization of imbutamine analogs as histamine H3 and H4 receptor ligands.

Arch Pharm (Weinheim) 2014 Feb 12;347(2):77-88. Epub 2013 Nov 12.

Faculty of Chemistry and Pharmacy, Department of Pharmaceutical/Medicinal Chemistry II, University of Regensburg, Regensburg, Germany.

Imbutamine (4-(1H-imidazol-4-yl)butanamine) is a potent histamine H3 (H3R) and H4 receptor (H4R) agonist (EC50 values: 3 and 66 nM, respectively). Aiming at improved selectivity for the H4R, the imidazole ring in imbutamine was methyl-substituted or replaced by various differently substituted heterocycles (1,2,3-triazoles, 1,2,4-triazoles, pyridines, pyrimidines) as potential bioisosteres. Investigations in [(35)S]GTPγS binding assays using membranes of Sf9 insect cells expressing the respective human histamine receptor subtype revealed only very weak activity of most of the synthesized hetarylalkylamines at both receptors. By contrast, the introduction of substituents at the 4-imidazolyl ring was most effective regarding H4R selectivity. This holds for methyl substitution in position 2 and, especially, in position 5. 5-Methylimbutamine (H4R: EC50  = 59 nM, α = 0.8) was equipotent with imbutamine at the hH4R, but revealed about 16-fold selectivity for the hH4R compared to the hH3R (EC50 980 nM, α = 0.36), whereas imbutamine preferred the hH3R. The functional activities were in agreement with radioligand binding data. The results support the hypothesis that, by analogy with histamine, methyl substitution in histamine homologs offers a way to shift the selectivity in favor of the H4R.
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http://dx.doi.org/10.1002/ardp.201300316DOI Listing
February 2014

Absorptive chemistry based extraction for LC-MS/MS analysis of small molecule analytes from biological fluids - an application for 25-hydroxyvitamin D.

Clin Chem Lab Med 2014 Mar;52(3):363-71

Background: Already available sample preparation technologies for liquid chromatography-tandem mass spectrometry have substantial shortcomings with respect to automation. A novel approach is based on gel-like polymeric material with defined absorption chemistry, which is immobilized in micro-plate wells. It is referred to as Tecan Immobilized Coating Extraction™ (TICE™) technology and it enables easy automation on liquid handling systems. We aimed to study the performance of Tecan AC Extraction Plate™ based on this principle by addressing 25-hydroxyvitamin D (25OHD) as an exemplary analyte.

Methods: A protocol for extraction of 25OHD from serum samples based on TICE™ technology was implemented on a robotic liquid handling system Freedom EVO® (Tecan). An isotope-dilution ultra-performance liquid chromatography-tandem mass spectrometry method was used for quantification. Performance was tested according to a comprehensive protocol.

Results: Linearity was found over a range from 4.3 to 65.8 ng/mL for 25OHD3. The coefficients of variation for the intra-day and inter-day precision were <6% and accuracy ranged between 96.9% and 99.8% for 25OHD3. Recovery was 84% and efficient control of matrix effects was verified. High sample throughput could be observed with 96 samples prepared in <60 min. Close agreement of results was found for clinical samples analyzed with a second tandem mass spectrometry method based on protein precipitation and two-dimensional ultra-performance liquid chromatography for sample preparation (r=0.988, n=73).

Conclusions: The new TICE™ technology was found to be a useful process for sample preparation in clinical mass spectrometry. Full automation suited for routine analysis was achieved.
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http://dx.doi.org/10.1515/cclm-2013-0534DOI Listing
March 2014

Synthesis and pharmacological characterization of new tetrahydrofuran based compounds as conformationally constrained histamine receptor ligands.

Org Biomol Chem 2013 Jun;11(24):4040-55

Institut für Organische Chemie, Universität Regensburg, Universitätsstr. 31, 93053 Regensburg, Germany.

A series of tetrahydrofuran based compounds with a bicyclic core that provides conformational restriction were synthesized and investigated by radioligand displacement studies and functional [(35)S]GTPγS binding assays at the human histamine receptor (hHR) subtypes. The amines and ((1S,3R,5S,6R)- and ((1S,3S,5S,6R)-3-(1H-imidazol-5-yl)-2-oxabicyclo[3.1.0]hexan-6-yl)methanamine), exhibited submicromolar Ki values at the hH3R with 10-fold higher affinities than their corresponding (6S)-epimers and 25- and >34-fold selectivity over the hH4R, respectively. Both compounds act as neutral antagonists at the hH3R with KB values of 181 and 32 nM, respectively. The cyanoguanidines of the imidazole series and the oxazole analogues turned out to be inactive at all hHR subtypes.
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http://dx.doi.org/10.1039/c3ob40441bDOI Listing
June 2013

Spatially-explicit life cycle assessment of sun-to-wheels transportation pathways in the U.S.

Environ Sci Technol 2013 Jan 3;47(2):1170-6. Epub 2013 Jan 3.

Bren School of Environmental Science and Management, University of California, Santa Barbara, California 93106-5131, USA.

Growth in biofuel production, which is meant to reduce greenhouse gas (GHG) emissions and fossil energy demand, is increasingly seen as a threat to food supply and natural habitats. Using photovoltaics (PV) to directly convert solar radiation into electricity for battery electric vehicles (BEVs) is an alternative to photosynthesis, which suffers from a very low energy conversion efficiency. Assessments need to be spatially explicit, since solar insolation and crop yields vary widely between locations. This paper therefore compares direct land use, life cycle GHG emissions and fossil fuel requirements of five different sun-to-wheels conversion pathways for every county in the contiguous U.S.: Ethanol from corn or switchgrass for internal combustion vehicles (ICVs), electricity from corn or switchgrass for BEVs, and PV electricity for BEVs. Even the most land-use efficient biomass-based pathway (i.e., switchgrass bioelectricity in U.S. counties with hypothetical crop yields of over 24 tonnes/ha) requires 29 times more land than the PV-based alternative in the same locations. PV BEV systems also have the lowest life cycle GHG emissions throughout the U.S. and the lowest fossil fuel inputs, except for locations with hypothetical switchgrass yields of 16 or more tonnes/ha. Including indirect land use effects further strengthens the case for PV.
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http://dx.doi.org/10.1021/es302959hDOI Listing
January 2013

A novel approach to signal normalisation in atmospheric pressure ionisation mass spectrometry.

J Pharm Biomed Anal 2012 Jul 5;66:399-401. Epub 2012 Apr 5.

Institute of Clinical Chemistry, University of Munich, Munich, Germany.

The aim of our study was to test an alternative principle of signal normalisation in LC-MS/MS. During analyses, post column infusion of the target analyte is done via a T-piece, generating an "area under the analyte peak" (AUP). The ratio of peak area to AUP is assessed as assay response. Acceptable analytical performance of this principle was found for an exemplary analyte. Post-column infusion may allow normalisation of ion suppression not requiring any additional standard compound. This approach can be useful in situations where no appropriate compound is available for classical internal standardisation.
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http://dx.doi.org/10.1016/j.jpba.2012.03.055DOI Listing
July 2012

LC-MS method for screening unknown microbial carotenoids and isoprenoid quinones.

J Microbiol Methods 2012 Jan 19;88(1):28-34. Epub 2011 Oct 19.

Institute of Biochemistry, Faculty of Veterinary Medicine, University of Leipzig, An den Tierkliniken 1, D-04103 Germany.

The structure of secondary metabolites from microorganisms provides a useful tool for microbial characterization and chemotaxonomic classification. Microbial isoprenoid quinones, for example, are well described and used to distinguish among photosynthetic microorganism groups. In addition, isoprenoid quinones can also be found, together with carotenoids, in non-photosynthetic microorganisms. The aim of the present study was to develop a LC-MS/MS method which can analyze and identify these microbial isoprenoids. Positive atmospheric pressure chemical ionization (APCI) together with collisionally induced dissociation was applied for generation of informative fragment spectra by mass spectrometry. Enhanced product ion (EPI) scan in a linear ion trap with information dependent data acquisition (IDA) enabled generation of MS fragment data even from minor isoprenoids. The developed liquid chromatography method enabled separation of isoprenoid patterns from their ester derivatives. Discovery and structural characterization of isoprenoid quinones and carotenoids were carried out by comparing characteristics of fragment spectra from unknown compounds with fragment spectra of a range of isoprenoid standard compounds and using published data. Throughout the study 17 microorganisms (e.g., Acremonium butyri, Arthrobacter spp., Brevibacterium linens, Bullera variabilis, Exophiala dermatitidis, Lecythophora hoffmannii, Panthoea agglomerans, Rhodotorula spp., Xanthophyllomyces dendrorhous) were screened and probable structures of isoprenoid quinones and carotenoids were suggested. The method lays some foundations on the analysis of yet unknown isoprenoids in microorganisms by using LCMS/MS techniques.
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http://dx.doi.org/10.1016/j.mimet.2011.10.001DOI Listing
January 2012

Synthesis and histamine H(3) and H(4) receptor activity of conformationally restricted cyanoguanidines related to UR-PI376.

Arch Pharm (Weinheim) 2011 Dec 11;344(12):775-85. Epub 2011 Oct 11.

Department of Pharmaceutical/Medicinal Chemistry II, University of Regensburg, Germany.

Recently, we identified highly potent agonists of the human histamine H(4) receptor (hH(4) R) among a series of imidazolylbutylcyanoguanidines. Aiming at improved selectivity for the hH(4) R relative to the H(3) receptor (hH(3) R), the flexible tetramethylene linker connecting imidazole ring and cyanoguanidine group was replaced by conformationally restricted carbocycles. Introduction of a para- or a meta-phenylene spacer yielded only very weakly active compounds at both hH(3) R and hH(4) R (investigated in [(35) S]GTPγS binding assays using Sf9 insect cell membranes expressing hH(x) R subtypes). By contrast, the incorporation of a more flexible cyclohexane-1,4-diyl linker resulted in EC(50) or K(B) values ≥110 nM at hH(4) R and hH(3) R. Quality of action, potency and receptor subtype selectivity of the investigated compounds depend on the stereochemistry: Cis-configured diastereomers prefer the hH(4) R and are partial agonists, whereas trans-isomers are antagonists at the hH(4) R. At the hH(3) R the trans-diastereomers are superior to the cis-isomers by a factor of 10. The results on imidazolylcycloalkylcyanoguanidines suggest that variation of ring size and optimization of the stereochemistry may be useful to increase the potency and selectivity of hH(4) R agonists relative to the hH(3) R.
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http://dx.doi.org/10.1002/ardp.201100144DOI Listing
December 2011

Resolution of natural microbial community dynamics by community fingerprinting, flow cytometry, and trend interpretation analysis.

Adv Biochem Eng Biotechnol 2011 ;124:151-81

Department of Isotope Biogeochemistry, UFZ, Helmholtz Centre for Environmental Research, Permoserstr. 15, 04318, Leipzig, Germany.

Natural microbial communities generally have an unknown structure and composition because of their still not yet cultivable members. Therefore, understanding the relationships among the bacterial members, prediction of their behaviour, and controlling their functions are difficult and often only partly successful endeavours to date. This study aims to test a new idea that allows to follow community dynamics on the basis of a simple concept. Terminal restriction fragment length polymorphism (T-RFLP) analysis of bacterial 16S ribosomal RNA genes was used to describe a community profile that we define as composition of a community. Flow cytometry and analysis of DNA contents and forward scatter characteristics of the single cells were used to describe a community profile, which we define as structure of a community. Both approaches were brought together by a non-metric multidimensional scaling (n-MDS) for trend interpretation of changes in the complex community data sets. This was done on the basis of a graphical evaluation of the cytometric data, leading to the newly developed Dalmatian plot tool, which gave an unexpected insight into the dynamics of the unknown bacterial members of the investigated natural microbial community. The approach presented here was compared with other techniques described in the literature. The microbial community investigated in this study was obtained from a BTEX contaminated anoxic aquifer. The indigenous bacteria were allowed to colonise in situ microcosms consisting of activated carbon. These microcosms were amended with benzene and one of the electron acceptors nitrate, sulphate or ferric iron to stimulate microbial growth. The data obtained in this study indicated that the composition (via T-RFLP) and structure (via flow cytometry) of the natural bacterial community were influenced by the hydro-geochemical conditions in the test site, but also by the supplied electron acceptors, which led to distinct shifts in relative abundances of specific community members. It was concluded that engineered environments can be successfully monitored by single cell analytics in combination with established molecular tools and sophisticated statistical analyses, a combination that holds great promise for studying and monitoring natural microbial community behaviour.
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http://dx.doi.org/10.1007/10_2010_82DOI Listing
May 2014

Tracking toxicants: toward a life cycle aware risk assessment.

Environ Sci Technol 2011 Jan 26;45(1):45-50. Epub 2010 Oct 26.

Department of Environmental Science and Management, University of California, Santa Barbara, California, USA.

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http://dx.doi.org/10.1021/es101467zDOI Listing
January 2011

Life cycle assessment of overhead and underground primary power distribution.

Environ Sci Technol 2010 Jul;44(14):5587-93

Bren School of Environmental Science and Management, University of California, Santa Barbara, California 93106-5131, USA.

Electrical power can be distributed in overhead or underground systems, both of which generate a variety of environmental impacts at all stages of their life cycles. While there is considerable literature discussing the trade-offs between both systems in terms of aesthetics, safety, cost, and reliability, environmental assessments are relatively rare and limited to power cable production and end-of-life management. This paper assesses environmental impacts from overhead and underground medium voltage power distribution systems as they are currently built and managed by Southern California Edison (SCE). It uses process-based life cycle assessment (LCA) according to ISO 14044 (2006) and SCE-specific primary data to the extent possible. Potential environmental impacts have been calculated using a wide range of midpoint indicators, and robustness of the results has been investigated through sensitivity analysis of the most uncertain and potentially significant parameters. The studied underground system has higher environmental impacts in all indicators and for all parameter values, mostly due to its higher material intensity. For both systems and all indicators the majority of impact occurs during cable production. Promising strategies for impact reduction are thus cable failure rate reduction for overhead and cable lifetime extension for underground systems.
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http://dx.doi.org/10.1021/es9037879DOI Listing
July 2010

Chiral NG-acylated hetarylpropylguanidine-type histamine H2 receptor agonists do not show significant stereoselectivity.

Bioorg Med Chem Lett 2010 May 27;20(10):3173-6. Epub 2010 Mar 27.

Institute of Pharmacy, Pharmaceutical/Medicinal Chemistry, University of Regensburg, D-93040 Regensburg, Germany.

A set of chiral imidazolylpropylguanidines and 2-aminothiazolylpropylguanidines bearing N(G)-3-phenyl- or N(G)-3-cyclohexylbutanoyl residues was synthesized and investigated for histamine H(2) receptor (H(2)R) agonism (guinea pig (gp) right atrium, GTPase assay on recombinant gp and human (h)H(2)R) and for hH(2)R selectivity compared to hH(1)R, hH(3)R and hH(4)R. In contrast to previous studies on arpromidine derivatives, the present investigation of acylguanidine-type compounds revealed only very low eudismic ratios (1.1-3.2), indicating the stereochemistry of the acyl moiety to play only a minor role in this series of H(2)R agonists.
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http://dx.doi.org/10.1016/j.bmcl.2010.03.082DOI Listing
May 2010

Intact phospholipid and quinone biomarkers to assess microbial diversity and redox state in microbial mats.

Microb Ecol 2010 Jul 17;60(1):226-38. Epub 2010 Mar 17.

Department of Microbiology, University of Barcelona, Barcelona, Spain.

Microbial mats are stratified microbial communities composed by highly inter-related populations and therefore are frequently chosen as model systems to study diversity and ecophysiological strategies. The present study describes an integrated approach to analyze microbial quinones and intact polar lipids (IPLs) in microbial mats within layers as thin as 500 microm by liquid chromatography-tandem mass spectrometry. Quinone profiles revealed important depth-related differences in community composition in two mat systems. The higher abundance of ubiquinones, compared to menaquinones, reflected the clear predominance of microorganisms belonging to aerobic alpha-, beta-, and gamma-Proteobacteria in Ebro delta estuarine mats. Hypersaline photosynthetic Camargue mats (France) showed a predominance of menaquinone-9 at the top of the mat, which is consistent with an important contribution of facultative aerobic or anaerobic bacteria in its photic zone. Quinone indices also indicated a higher diversity of non-phototrophs and a more anaerobic character in the hypersaline mats. Besides, the dissimilarity index suggested that the samples were greatly influenced by a depth-related redox state gradient. In the analysis of IPLs, there was a predominance of phosphatidylglycerols and sulfoquinovosyldiacylglycerols, the latter being an abundant biomarker of Cyanobacteria. This combined approach based on quinone and IPL analysis has proven to be a useful method to establish differences in the microbial diversity and redox state of highly structure microbial mat systems at a fine-scale level.
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http://dx.doi.org/10.1007/s00248-010-9645-2DOI Listing
July 2010

Synthesis and structure-activity relationships of cyanoguanidine-type and structurally related histamine H4 receptor agonists.

J Med Chem 2009 Oct;52(20):6297-313

Department of Pharmaceutical/Medicinal Chemistry, Faculty of Chemistry and Pharmacy, University of Regensburg, Universitatsstrasse 31, D-93053 Regensburg, Germany.

Recently, we identified high-affinity human histamine H3 (hH3R) and H4 receptor (hH4R) ligands among a series of NG-acylated imidazolylpropylguanidines, which were originally designed as histamine H2 receptor (H2R) agonists. Aiming at selectivity for hH4R, the acylguanidine group was replaced with related moieties. Within a series of cyanoguanidines, 2-cyano-1-[4-(1H-imidazol-4-yl)butyl]-3-[(2-phenylthio)ethyl]guanidine (UR-PI376, 67) was identified as the most potent hH4R agonist (pEC50 = 7.47, alpha = 0.93) showing negligible hH1R and hH2R activities and significant selectivity over the hH3R (pKB = 6.00, alpha = -0.28), as determined in steady-state GTPase assays using membrane preparations of hH(x)R-expressing Sf9 cells. In contrast to previously described selective H4R agonists, this compound and other 3-substituted derivatives are devoid of agonistic activity at the other HR subtypes. Modeling of the binding mode of 67 suggests that the cyanoguanidine moiety forms charge-assisted hydrogen bonds not only with the conserved Asp-94 but also with the hH4R-specific Arg-341 residue. 2-Carbamoyl-1-[2-(1H-imidazol-4-yl)ethyl]-3-(3-phenylpropyl)guanidine (UR-PI97, 88) was unexpectedly identified as a highly potent and selective hH3R inverse agonist (pKB = 8.42, >300-fold selectivity over the other HR subtypes).
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http://dx.doi.org/10.1021/jm900526hDOI Listing
October 2009

Desulfitobacterium aromaticivorans sp. nov. and Geobacter toluenoxydans sp. nov., iron-reducing bacteria capable of anaerobic degradation of monoaromatic hydrocarbons.

Int J Syst Evol Microbiol 2010 Mar 5;60(Pt 3):686-695. Epub 2009 Aug 5.

Institute of Groundwater Ecology, Helmholtz Zentrum München - German Research Center for Environmental Health, Ingolstädter Landstraße 1, D-85764 Neuherberg, Germany.

Dissimilatory iron reduction plays a significant role in subsurface environments. Currently, it is assumed that members of the genus Geobacter constitute the majority of the iron-reducing micro-organisms that oxidize aromatic compounds in contaminated subsurface environments. Here, we report the isolation of two phylogenetically distinct pure cultures of iron-reducing degraders of monoaromatic hydrocarbons, strain TMJ1(T), which belongs to the genus Geobacter within the Deltaproteobacteria, and strain UKTL(T), belonging to the genus Desulfitobacterium within the Clostridia. Both strains utilize a wide range of substrates as carbon and energy sources, including the aromatic compounds toluene, phenol and p-cresol. Additionally, strain UKTL(T) utilizes o-xylene and TMJ1(T) utilizes m-cresol. Anaerobic degradation of toluene in both strains and o-xylene in strain UKTL(T) is initiated by activation with fumarate addition to the methyl group. The genomic DNA G+C contents of strains TMJ1(T) and UKTL(T) are 54.4 and 47.7 mol%, respectively. Based on a detailed physiological characterization and phylogenetic analysis of the 16S rRNA genes of both strains, we propose the names Desulfitobacterium aromaticivorans sp. nov. (type strain UKTL(T) =DSM 19510(T) =JCM 15765(T)) and Geobacter toluenoxydans sp. nov. (type strain TMJ1(T) =DSM 19350(T) =JCM 15764(T)) to accommodate these strains. To the best of our knowledge, strain UKTL(T) is the first described spore-forming, iron-reducing bacterium that can degrade aromatic hydrocarbons.
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http://dx.doi.org/10.1099/ijs.0.003525-0DOI Listing
March 2010

Parametric assessment of climate change impacts of automotive material substitution.

Authors:
Roland Geyer

Environ Sci Technol 2008 Sep;42(18):6973-9

Donald Bren School of Enuironmental Science and Management, University of California, Santa Barbara, California 93106-5131, USA.

Quantifying the net climate change impact of automotive material substitution is not a trivial task. It requires the assessment of the mass reduction potential of automotive materials, the greenhouse gas (GHG) emissions from their production and recycling, and their impact on GHG emissions from vehicle use. The model presented in this paper is based on life cycle assessment (LCA) and completely parameterized, i.e., its computational structure is separated from the required input data, which is not traditionally done in LCAs. The parameterization increases scientific rigor and transparency of the assessment methodology, facilitates sensitivity and uncertainty analysis of the results, and also makes it possible to compare different studies and explain their disparities. The state of the art of the modeling methodology is reviewed and advanced. Assessment of the GHG emission impacts of material recycling through consequential system expansion shows that our understanding of this issue is still incomplete. This is a critical knowledge gap since a case study shows thatfor materials such as aluminum, the GHG emission impacts of material production and recycling are both of the same size as the use phase savings from vehicle mass reduction.
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http://dx.doi.org/10.1021/es800314wDOI Listing
September 2008

Microbial community shifts as a response to efficient degradation of chlorobenzene under hypoxic conditions.

Biodegradation 2008 Jun 20;19(3):435-46. Epub 2007 Sep 20.

Department of Environmental Microbiology, UFZ, Helmholtz Centre for Environmental Research, Permoserstrasse 15, 04318 Leipzig, Germany.

Limitations in the availability of oxygen restrict aerobic biodegradation of chloroaromatic compounds in groundwater ecosystems. In this context the activity of ring-cleaving chlorocatechol dioxygenases (CC12O) is crucial for effective mineralization. Previously we demonstrated that oxygen-related enzyme characteristics of CC12O can vary widely among the Proteobacteria (Balcke et al. submitted). Here, we investigated how strains with different ability to transform intermediary 3-chlorocatechol integrate into biodegradation of chlorobenzene (CB) under low or high oxygen availability. Pseudomonas veronii UFZ B549 and Acidovorax facilis UFZ B530, which had differing oxygen affinities for CC12O, were mixed together at different proportions (20:80; 80:20), and compared for degradation of chlorobenzene under oxic (215 microM O2) and hypoxic (11 microM O2) conditions. Changes in community composition in binary mixed cultures were determined and compared with an indigenous groundwater community, cultivated under comparable conditions. Community shifts were determined by FISH (fluorescent in situ hybridization) in our model system and SSCP (single stranded conformation polymorphism) fingerprinting in the groundwater community, as well as by analysis of respiratory quinones of taxonomic value. Hypoxia led to enrichment of Acidovoracae in the groundwater and binary cultures. Under hypoxic conditions cis,cis-2-chloromuconate released to the medium by A. facilis allowed for concomitant growth of P. veronii, although its low-affinity type CC12O would not imply growth on CB. Vice versa, increasing abundance of P. veronii induced intermediary 3-chlorocatechol accumulation, which was reduced by growth of A. facilis. Thus, reduced oxygen availability caused syntrophic rather than competitive interactions.
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http://dx.doi.org/10.1007/s10532-007-9149-zDOI Listing
June 2008

Aquincola tertiaricarbonis gen. nov., sp. nov., a tertiary butyl moiety-degrading bacterium.

Int J Syst Evol Microbiol 2007 Jun;57(Pt 6):1295-1303

Umweltforschungszentrum Leipzig-Halle, Department Umweltmikrobiologie, Permoserstr. 15, D-04318 Leipzig, Germany.

Strains L10(T), L108 and CIP I-2052 were originally obtained from methyl tert-butyl ether (MTBE)-contaminated groundwater and from a wastewater treatment plant, respectively. All share the ability to grow on tert-butanol, an intermediate of MTBE degradation. Cells are strictly aerobic, motile by a polar flagellum and exhibit strong pili formation. Poly beta-hydroxybutyrate (PHB) granules are formed. The DNA G+C content is 69-70.5 mol% and the main ubiquinone is Q-8. The major cellular fatty acids are 16 : 1 cis-9 and 16 : 0 and the only hydroxy fatty acid is 10 : 0 3-OH. The major phospholipids are phosphatidylethanolamine (PE) 16 : 1/16 : 1 and phosphatidylglycerol 16 : 0/16 : 1. A significant amount of PE 17 : 0/16 : 1 is present. The 16S rRNA gene sequences of these strains are almost identical and form a separate line of descent in the Rubrivivax-Roseateles-Leptothrix-Ideonella-Aquabacterium branch of the Betaproteobacteria with 97 % similarity to 16S rRNA genes of the type strains of Rubrivivax gelatinosus, Leptothrix mobilis and Ideonella dechloratans. However, physiological properties, DNA-DNA relatedness values and the phospholipid and cellular fatty acid profiles distinguish the novel isolates from the three closely related genera. Therefore, it is concluded that strains L10(T), L108 and CIP I-2052 represent a new genus and novel species for which the name Aquincola tertiaricarbonis gen. nov., sp. nov., is proposed. The type strain is strain L10(T) (=DSM 18512(T)=CIP 109243(T)).
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http://dx.doi.org/10.1099/ijs.0.64663-0DOI Listing
June 2007

Monitoring diel variations of physiological status and bacterial diversity in an estuarine microbial mat: an integrated biomarker analysis.

Microb Ecol 2007 Oct 9;54(3):523-31. Epub 2007 Mar 9.

Department of Microbiology, University of Barcelona, Barcelona, Spain.

Microbial mats are highly productive microbial systems and a source of not-yet characterized microorganisms and metabolic strategies. In this article, we introduced a lipid biomarker/microbial isolation approach to detect short-term variations of microbial diversity, physiological and redox status, and also characterize lipid biomarkers from specific microbial groups that can be further monitored. Phospholipid fractions (PLFA) were examined for plasmalogens, indicative of certain anaerobes. The glycolipid fraction was processed for polyhydroxyalkanoates (PHA) and the neutral lipid fraction was used to evaluate respiratory quinone content. Data demonstrate an increase in the metabolic stress, unbalanced growth, proportion of anaerobic bacteria and respiratory rate after the maximal photosynthetic activity. Higher accumulation of polyhydroxyalkanoates at the same sampling point also suggested a situation of carbon storage by heterotrophs closely related to photosynthetic microorganisms. Besides, the characterization of lipid biomarkers (plasmalogens, sphingolipids) from specific microbial groups provided clues about the dynamics and diversity of less-characterized mat members. In this case, lipid analyses were complemented by the isolation and characterization of anaerobic spore formers and sulfate reducers to obtain insight into their affiliation and lipid composition. The results revealed that temporal shifts in lipid biomarkers are indicative of an intense change in the physiology, redox condition, and community composition along the diel cycle, and support the hypothesis that interactions between heterotrophs and primary producers play an important role in the carbon flow in microbial mats.
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http://dx.doi.org/10.1007/s00248-007-9224-3DOI Listing
October 2007

Lysophosphatidylethanolamine is a substrate for the short-chain alcohol dehydrogenase SocA from Myxococcus xanthus.

J Bacteriol 2006 Dec 6;188(24):8543-50. Epub 2006 Oct 6.

Department of Microbiology, University of Georgia, Athens, GA 30602, USA.

Short-chain alcohol dehydrogenases (SCADHs) synthesize a variety of intercellular signals and other chemically diverse products. It is difficult to predict the substrate of a SCADH on the basis of amino acid sequence homology, as the substrates are not known for most SCADHs. In Myxococcus xanthus, the SCADH CsgA is responsible for C signaling during fruiting body development, although the mechanism is unclear. Overexpression of the SCADH SocA compensates for the lack of CsgA and restores development and C signaling in csgA mutants. The potential of SocA in generating the C signal enzymatically was explored by developing a dehydrogenase assay-based screen to purify the SocA substrate(s). A SocA substrate was extracted from M. xanthus cells with acidified ethyl acetate and sequentially purified by solid-phase extraction on silica gel and by reverse-phase high-performance liquid chromatography. The fraction with the highest SocA dehydrogenase activity contained the lysophospholipid 1-acyl 2-hydroxy-sn-glycerophosphoethanolamine (lyso-PE) as indicated by the fragment ions and a phosphatidylethanolamine-specific neutral loss scan following liquid chromatography coupled to mass spectrometry. The abundant lysophospholipid with the mass m/z 450 (molecular ion [M-H]-) had a monounsaturated acyl chain with 16 carbons. SocA oxidizes lyso-PE containing either saturated or unsaturated fatty acids but exhibits poor activity on l-alpha-glycerophosphorylethanolamine, suggesting that an acyl chain is important for activity. Of the five different head groups, only ethanolamine showed appreciable activity. The apparent Km and Vmax for lyso-PE 18:1 were 116 microM and 875 micromol min(-1) mg(-1), respectively. The catalytic efficiency (k(cat)/Km) was 1 x 10(8) M(-1) s(-1). The proposed product, 1-acyloxy-3-(2-aminoethylphosphatyl) acetone was unstable, and the fragmented products were unable to rescue csgA mutant development. The active fraction from thin-layer chromatography also contained an unidentified SocA substrate that had morphogenic properties.
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http://dx.doi.org/10.1128/JB.01047-06DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1698226PMC
December 2006

Novel lipids in Myxococcus xanthus and their role in chemotaxis.

Environ Microbiol 2006 Nov;8(11):1935-49

Department of Microbiology, University of Georgia, Athens, GA 30602, USA.

Organisms that colonize solid surfaces, like Myxococcus xanthus, use novel signalling systems to organize multicellular behaviour. Phosphatidylethanolamine (PE) containing the fatty acid 16:1omega5 (Delta11) elicits a chemotactic response. The phenomenon was examined by observing the effects of PE species with varying fatty acid pairings. Wild-type M. xanthus contains 17 different PE species under vegetative conditions and 19 at the midpoint of development; 13 of the 17 have an unsaturated fatty acid at the sn-1 position, a novelty among Proteobacteria. Myxococcus xanthus has two glycerol-3-phosphate acyltransferase (PlsB) homologues which add the sn-1 fatty acid. Each produces PE with 16:1 at the sn-1 position and supports growth and fruiting body development. Deletion of plsB1 (MXAN3288) results in more dramatic changes in PE species distribution than deletion of plsB2 (MXAN1675). PlsB2 has a putative N-terminal eukaryotic fatty acid reductase domain and may support both ether lipid synthesis and PE synthesis. Disruption of a single sn-2 acyltransferase homologue (PlsC, of which M. xanthus contains five) results in minor changes in membrane PE. Derivatization of purified PE extracts with dimethyldisulfide was used to determine the position of the double bonds in unsaturated fatty acids. The results suggest that Delta5 and Delta11 desaturases may create the double bonds after synthesis of the fatty acid. Phosphatidylethanolamine enriched for 16:1 at the sn-1 position stimulates chemotaxis more strongly than PE with 16:1 enriched at the sn-2 position. It appears that the deployment of a rare fatty acid (16:1omega5) at an unusual position (sn-1) has facilitated the evolution of a novel cell signal.
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http://dx.doi.org/10.1111/j.1462-2920.2006.01073.xDOI Listing
November 2006