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Pausch J, Holz M, Zhu B, Cheng W. Rhizosphere priming promotes plant nitrogen acquisition by microbial necromass recycling. Plant Cell Environ 2024; 47:1987-1996. [PMID: 38369964 DOI: 10.1111/pce.14858] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2023] [Revised: 02/02/2024] [Accepted: 02/04/2024] [Indexed: 02/20/2024]
Abstract
Nitrogen availability in the rhizosphere relies on root-microorganism interactions, where root exudates trigger soil organic matter (SOM) decomposition through the rhizosphere priming effect (RPE). Though microbial necromass contribute significantly to organically bound soil nitrogen (N), the role of RPEs in regulating necromass recycling and plant nitrogen acquisition has received limited attention. We used 15N natural abundance as a proxy for necromass-N since necromass is enriched in 15N compared to other soil-N forms. We combined studies using the same experimental design for continuous 13CO2 labelling of various plant species and the same soil type, but considering top- and subsoil. RPE were quantified as difference in SOM-decomposition between planted and unplanted soils. Results showed higher plant N uptake as RPEs increased. The positive relationship between 15N-enrichment of shoots and roots and RPEs indicated an enhanced necromass-N turnover by RPE. Moreover, our data revealed that RPEs were saturated with increasing carbon (C) input via rhizodeposition in topsoil. In subsoil, RPEs increased linearly within a small range of C input indicating a strong effect of root-released C on decomposition rates in deeper soil horizons. Overall, this study confirmed the functional importance of rhizosphere C input for plant N acquisition through enhanced necromass turnover by RPEs.
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Affiliation(s)
- Johanna Pausch
- Agroecology, BayCEER, University of Bayreuth, Bayreuth, Bayern, Germany
| | - Maire Holz
- Leibniz Centre for Agricultural Landscape Research (ZALF), Müncheberg, Germany
| | - Biao Zhu
- Institute of Ecology, College of Urban and Environmental Sciences, and Key Laboratory for Earth Surface Processes of the Ministry of Education, Peking University, Beijing, China
| | - Weixin Cheng
- Department of Environmental Studies, University of California, Santa Cruz, California, USA
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Zhou J, Gube M, Holz M, Song B, Shan I, Shi L, Kuzyakov Y, Dippold MA, Pausch J. Ectomycorrhizal and non-mycorrhizal rhizosphere fungi increase root-derived C input to soil and modify enzyme activities: A 14 C pulse labelling of Picea abies seedlings. Plant Cell Environ 2022; 45:3122-3133. [PMID: 35909089 DOI: 10.1111/pce.14413] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Revised: 07/11/2022] [Accepted: 07/29/2022] [Indexed: 06/15/2023]
Abstract
Consequences of interactions between ectomycorrhizal fungi (EcMF) and non-mycorrhizal rhizosphere fungi (NMRF) for plant carbon (C) allocation belowground and nutrient cycling in soil remain unknown. To address this topic, we performed a mesocosm study with Norway spruce seedlings [Picea abies (L.) H. Karst] inoculated with EcMF, NMRF, or a mixture of both (MIX). 14 CO2 pulse labelling of spruce was applied to trace and visualize the 14 C incorporation into roots, rhizohyphosphere and hyphosphere. Activities and localization of enzymes involved in the C, nitrogen (N) and phosphorus (P) cycling were visualized using zymography. Spruce seedlings inoculated with EcMF and NMRF allocated more C to soils (EcMF: 10.7%; NMRF: 3.5% of total recovered C) compared to uninoculated control seedlings. The 14 C activity in the hyphosphere was highest for EcMF and lowest for NMRF. In the presence of both, NMRF and EcMF (MIX), the 14 C activity was 64% lower compared with EcMF inoculation alone. This suggests a suppressed C allocation via EcMF likely due to the competition between EcMF and NMRF for N and P. Furthermore, we observed 57% and 49% higher chitinase and leucine-aminopeptidase activities in the rhizohyphosphere of EcMF compared to the uninoculated control, respectively. In contrast, β-glucosidase activity (14.3 nmol cm-2 h-1 ) was highest in NMRF likely because NMRF consumed rhizodeposits efficiently. This was further supported by that enzyme stoichiometry in soil with EcMF shifted to a higher investment of nutrient acquisition enzymes (e.g., chitinase, leucine-aminopeptidase, acid phosphatase) compared to NMRF inoculation, where investment in β-glucosidase increased. In conclusion, the alleviation of EcMF from C limitation promotes higher activities of enzymes involved in the N and P cycle to cover the nutrient demand of EcMF and host seedlings. In contrast, C limitation of NMRF probably led to a shift in investment towards higher activities of enzymes involved in the C cycle.
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Affiliation(s)
- Jie Zhou
- Biogeochemistry of Agroecosystems, Department of Crop Science, Georg August University of Göttingen, Göttingen, Germany
- College of Agronomy and Biotechnology, China Agricultural University, Beijing, China
| | - Matthias Gube
- Department of Soil Science of Temperate Ecosystems, Department of Agricultural Soil Science, Georg August University of Göttingen, Göttingen, Germany
| | - Maire Holz
- Group of Isotope Biogeochemistry and Gas Fluxes, Leibniz Centre for Agricultural Landscape Research (ZALF) e.V., Müncheberg, Germany
| | - Bin Song
- Forest Botany and Tree Physiology, Georg August University of Göttingen, Göttingen, Germany
| | - Immo Shan
- Forest Botany and Tree Physiology, Georg August University of Göttingen, Göttingen, Germany
| | - Lingling Shi
- Department of Economic Plants and Biotechnology, Yunnan Key Laboratory For Wild Plant Resources, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan, China
- Centre for Mountain Futures (CMF), Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan, China
| | - Yakov Kuzyakov
- Department of Soil Science of Temperate Ecosystems, Department of Agricultural Soil Science, Georg August University of Göttingen, Göttingen, Germany
- Agro-Technological Institute, Peoples Friendship University of Russia (RUDN University), Moscow; Institute of Environmental Sciences, Kazan Federal University, Kazan, Russia
| | - Michaela A Dippold
- Biogeochemistry of Agroecosystems, Department of Crop Science, Georg August University of Göttingen, Göttingen, Germany
- Geo-Biosphere Interactions, Department of Geosciences Faculty of Sciences, University of Tuebingen, Tuebingen, Germany
| | - Johanna Pausch
- Department of Agroecology, Bayreuth Center of Ecology and Environmental Research (BayCEER), University of Bayreuth, Bayreuth, Germany
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Schliffke S, Maire C, Holz M, Bokemeyer C, Westphal M, Lamszus K, Mohme M. P16.06 Immunophenotyping of tumor-infiltrating T cells in primary CNS lymphoma. Neuro Oncol 2021. [DOI: 10.1093/neuonc/noab180.198] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Abstract
BACKGROUND
Primary CNS lymphoma represents a malignant disease with dismal prognosis. Standard of care is high dose chemotherapy and radiation. However, this combination cannot be applied to the elderly and fragile population. Immunotherapy holds great promise to be effective in these patients. This study therefore aims to explore the phenotype of tumor-infiltrating lymphocytes (TIL) in order to analyze the potential for immune checkpoint inhibition.
MATERIAL AND METHODS
We performed ex vivo multicolor flow-cytometry on surgical specimens of nine patients with intracerebral lymphoma, including seven with primary CNS lymphoma after isolation of TILs following standard protocols. Data was analyzed using a Fortessa LSR flow cytometer and Diva software. The study was approved by the local ethics committee (PV4904).
RESULTS
Our ex vivo phenotyping demonstrated a predominant infiltration of CD8+ T cells, which outnumber CD4+ T cells by a ratio of 2:1 (p<0.01). Regulatory T cells (Tregs) were not increased in the tumor microenvironment and the NK cell frequency was reduced compared to the peripheral blood. While CD4+ T helper cells displayed significantly increased surface expression of multiple activation and checkpoint markers, including TIGIT, PD-1, Tim3 and CD57, cytotoxic CD8+ T cells predominantly expressed only TIGIT and PD-1. On average 70% and 80% of CD8+ T cells expressed PD-1 and TIGIT, respectively, compared to 35% and 60% of PD-1 and TIGIT on CD4+ T cells (p<0.05). CD8+ T cells furthermore showed an increased expression of CD39 and a simultaneous downregulation of CD73, both ectoenzyms involved in the modulation of intratumoral ATP, thereby indicating a metabolic immune modulation by the tumor.
CONCLUSION
Taken together, our study demonstrates a strong infiltration of cytotoxic CD8+ T cells into cerebral lymphoma, which potentially can be disinhibited using checkpoint immunotherapy. Our profiling suggests that PD-1 and TIGIT present appealing targets for such kind of immune disinhibition.
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Affiliation(s)
- S Schliffke
- University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - C Maire
- University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - M Holz
- University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - C Bokemeyer
- University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - M Westphal
- University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - K Lamszus
- University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - M Mohme
- University Medical Center Hamburg-Eppendorf, Hamburg, Germany
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Holz M, Zarebanadkouki M, Kuzyakov Y, Pausch J, Carminati A. Root hairs increase rhizosphere extension and carbon input to soil. Ann Bot 2018; 121:61-69. [PMID: 29267846 PMCID: PMC5786240 DOI: 10.1093/aob/mcx127] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Accepted: 09/22/2017] [Indexed: 05/17/2023]
Abstract
BACKGROUND AND AIMS Although it is commonly accepted that root exudation enhances plant-microbial interactions in the rhizosphere, experimental data on the spatial distribution of exudates are scarce. Our hypothesis was that root hairs exude organic substances to enlarge the rhizosphere farther from the root surface. METHODS Barley (Hordeum vulgare 'Pallas' - wild type) and its root-hairless mutant (brb) were grown in rhizoboxes and labelled with 14CO2. A filter paper was placed on the soil surface to capture, image and quantify root exudates. KEY RESULTS Plants with root hairs allocated more carbon (C) to roots (wild type: 13 %; brb: 8 % of assimilated 14C) and to rhizosheaths (wild type: 1.2 %; brb: 0.2 %), while hairless plants allocated more C to shoots (wild type: 65 %; brb: 75 %). Root hairs increased the radial rhizosphere extension three-fold, from 0.5 to 1.5 mm. Total exudation on filter paper was three times greater for wild type plants compared to the hairless mutant. CONCLUSION Root hairs increase exudation and spatial rhizosphere extension, which probably enhance rhizosphere interactions and nutrient cycling in larger soil volumes. Root hairs may therefore be beneficial to plants under nutrient-limiting conditions. The greater C allocation below ground in the presence of root hairs may additionally foster C sequestration.
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Affiliation(s)
- Maire Holz
- Division of Agricultural Soil Science, University of Göttingen, Göttingen, Germany
- For correspondence.
| | | | - Yakov Kuzyakov
- Department of Soil Science of Temperate Ecosystems and Department of Agricultural Soil Science, University of Göttingen, Göttingen, Germany
- Institute of Environmental Sciences, Kazan Federal University, Kazan, Russia
| | - Johanna Pausch
- Division of Agroecology, University of Bayreuth, Bayreuth, Germany
| | - Andrea Carminati
- Division of Soil Physics, University of Bayreuth, Bayreuth, Germany
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Carminati A, Zarebanadkouki M, Kroener E, Ahmed MA, Holz M. Biophysical rhizosphere processes affecting root water uptake. Ann Bot 2016; 118:561-571. [PMID: 27345032 PMCID: PMC5055629 DOI: 10.1093/aob/mcw113] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Revised: 03/29/2016] [Accepted: 04/08/2016] [Indexed: 05/09/2023]
Abstract
Background Recent advances in imaging techniques now make it possible to visualize the biogeochemical and physical environment around the roots, the rhizosphere. Detailed images of pore space geometry and water content dynamics around roots have demonstrated the heterogeneity of the rhizosphere compared with the soil far from the roots. These findings have inspired new models of root water uptake which aim to describe such small-scale heterogeneity. However, the question remains of how far these image-based findings have really advanced our understanding of how roots extract water from soils. Scope The rhizosphere processes affecting root water uptake are reviewed. Special attention is dedicated to the role of mucilage exuded by roots. Mucilage increases the soil moisture at negative water potentials and it keeps the rhizosphere wet when plants take up water, possibly maintaining the hydraulic connection between roots and soil. However, mucilage becomes viscous and hydrophobic upon severe drying and it limits the water fluxes across the rhizosphere during the rewetting phase. The role of mucilage in maintaining the hydraulic contact between the root surface and the surrounding soil, thereby softening the drops in water potential around the roots in dry soils, remains to be demonstrated. Conclusion Despite detailed images of water content, water fluxes and soil structure in the rhizosphere, a general understanding of how the rhizosphere affects root water uptake is still lacking. The missing elements of the puzzle are the gradient in water potential around roots. Measurements of the xylem water potential at varying soil water potentials and transpiration rates supported by numerical models of root water uptake would allow the estimation of the water potential across the rhizosphere. Such measurements are crucial to comprehend how water enters the roots.
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Affiliation(s)
- A. Carminati
- Division of Soil Hydrology, Georg-August University, Göttingen, Germany
| | - M. Zarebanadkouki
- Division of Soil Hydrology, Georg-August University, Göttingen, Germany
| | - E. Kroener
- Division of Soil Hydrology, Georg-August University, Göttingen, Germany
| | - M. A. Ahmed
- Division of Soil Hydrology, Georg-August University, Göttingen, Germany
- Department of Agricultural Engineering, Faculty of Agriculture, University of Khartoum, Khartoum North, 13314 Shambat, Sudan
| | - M. Holz
- Division of Soil Hydrology, Georg-August University, Göttingen, Germany
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Campbell EK, Holz M, Gerlich D, Maier JP. Laboratory confirmation of C60(+) as the carrier of two diffuse interstellar bands. Nature 2016; 523:322-3. [PMID: 26178962 DOI: 10.1038/nature14566] [Citation(s) in RCA: 391] [Impact Index Per Article: 48.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Accepted: 05/11/2015] [Indexed: 11/09/2022]
Abstract
The diffuse interstellar bands are absorption lines seen towards reddened stars. None of the molecules responsible for these bands have been conclusively identified. Two bands at 9,632 ångströms and 9,577 ångströms were reported in 1994, and were suggested to arise from C60(+) molecules (ref. 3), on the basis of the proximity of these wavelengths to the absorption bands of C60(+) measured in a neon matrix. Confirmation of this assignment requires the gas-phase spectrum of C60(+). Here we report laboratory spectroscopy of C60(+) in the gas phase, cooled to 5.8 kelvin. The absorption spectrum has maxima at 9,632.7 ± 0.1 ångströms and 9,577.5 ± 0.1 ångströms, and the full widths at half-maximum of these bands are 2.2 ± 0.2 ångströms and 2.5 ± 0.2 ångströms, respectively. We conclude that we have positively identified the diffuse interstellar bands at 9,632 ångströms and 9,577 ångströms as arising from C60(+) in the interstellar medium.
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Affiliation(s)
- E K Campbell
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland
| | - M Holz
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland
| | - D Gerlich
- Department of Physics, Technische Universität, 09107 Chemnitz, Germany
| | - J P Maier
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland
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Al-Ali BM, Holz M, Sadik P, Oppeck C, Schmidt K, Oppeck G. Correlation between erectile function and cardiovascular risk factors by assessing arterial stiffness and myocardial perfusion imaging and carotid artery intima-media thickness. MINERVA UROL NEFROL 2015; 67:11-18. [PMID: 25664960] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
AIM Aim of the study was to analyze the relationship between erectile function and cardiovascular risk factors by assessing arterial stiffness and myocardial scintigraphy and carotid artery intima-media thickness. METHODS Fifty-nine consecutive asymptomatic men aged 30-86 years, were included. Myocardial scintigraphy, Doppler sonography of carotid artery and arterial stifness parameters were performed. Erectile function was evaluated with a validated erectile function index quesionnaire. RESULTS The control group included 18 subjects and the study group included 41 subjects with abnormal IIEF-5 scores. We compared both group's IIEF-5 scores there was significant correlation between IIEF-5 and cholesterol (P<0.05) and HbA1c (P<0.05). Moreover, there was a significant correlation in patients with abnormal IIEF-5 scores and pathologic myocardial perfusion imaging (P<0.05) and triglyceride (P<0.05). A two-factor ANOVA showed two significant interactions patients with abnormal cholesterol and abnormal pulse wave velocity, augmentation index had lower IIEF-5 scores; patients with abnormal triglyceride values, and abnormal Hb1Ac had lower IIEF-5 scores. CONCLUSION Eretile dysfunction (ED) prevalence is high in cardiologic patients referred for myocardial nuclear imaging. There is a significant relation between ED, diabetes and hyperlipidemia, and advanced age. Myocardial nuclear scan and arterial stiffness parameters could be used to stratify the cardiovascular risk factors in ED patients.
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Affiliation(s)
- B M Al-Ali
- Department of Urology Medical University Graz, Graz, Austria -
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Ahmed MA, Kroener E, Holz M, Zarebanadkouki M, Carminati A. Mucilage exudation facilitates root water uptake in dry soils. Funct Plant Biol 2014; 41:1129-1137. [PMID: 32481063 DOI: 10.1071/fp13330] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Accepted: 03/25/2014] [Indexed: 05/14/2023]
Abstract
As plant roots take up water and the soil dries, water depletion is expected to occur in the rhizosphere. However, recent experiments showed that the rhizosphere was wetter than the bulk soil during root water uptake. We hypothesise that the increased water content in the rhizosphere was caused by mucilage exuded by roots. It is probably that the higher water content in the rhizosphere results in higher hydraulic conductivity of the root-soil interface. In this case, mucilage exudation would favour the uptake of water in dry soils. To test this hypothesis, we covered a suction cup, referred to as an artificial root, with mucilage. We placed it in soil with a water content of 0.03cm3cm-3, and used the root pressure probe technique to measure the hydraulic conductivity of the root-soil continuum. The results were compared with measurements with roots not covered with mucilage. The root pressure relaxation curves were fitted with a model of root water uptake including rhizosphere dynamics. The results demonstrated that when mucilage is added to the root surface, it keeps the soil near the roots wet and hydraulically well conductive, facilitating the water flow from dry soils towards the root surface. Mucilage exudation seems to be an optimal plant trait that favours the capture of water when water is scarce.
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Affiliation(s)
- Mutez A Ahmed
- Division of Soil Hydrology, Georg-August University of Göttingen, Göttingen 37077, Germany
| | - Eva Kroener
- Division of Soil Hydrology, Georg-August University of Göttingen, Göttingen 37077, Germany
| | - Maire Holz
- Division of Soil Hydrology, Georg-August University of Göttingen, Göttingen 37077, Germany
| | - Mohsen Zarebanadkouki
- Division of Soil Hydrology, Georg-August University of Göttingen, Göttingen 37077, Germany
| | - Andrea Carminati
- Division of Soil Hydrology, Georg-August University of Göttingen, Göttingen 37077, Germany
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Lamszus K, Kathagen A, Holz M, Schulte A, Westphal M. "GO OR GROW" - LINKS BETWEEN CELLULAR FUNCTION, GLUCOSE METABOLISM AND GLIOMA MICROENVIRONMENT. Neuro Oncol 2014. [DOI: 10.1093/neuonc/nou206.19] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Detscher E, Hertz HG, Holz M, Mao XA. Ion-Ion De-Association and Association of Strong Electrolytes at High Dilution from Nuclear Magnetic Relaxation Measurements. ACTA ACUST UNITED AC 2014. [DOI: 10.1515/zna-1995-4-523] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
Proton magnetic relaxation rates in the system N(CH)3)4Br/NiBr2/D2O, N(CH3)4Br/MnBr2/ D2O, Ni(00CCH3)2/D2O and Mn(00CCH3)2/D2O have been measured as a function of the solute concentration in the range 0.002 < c* ⪍ 1 m. Division by the concentration c* and by a quantity characterizing the ionic motion yields the association parameter (4-parameter). A decreases and increases with decreasing concentration for the systems involving cation-cation and cation-anion interaction, respectively. The relaxation rates of 35C1-, 133Cs+ , and 25Mg++ in diamagnetic aqueous solutions have also been measured down to high dilution. Here as well in most cases we have found an increase of the A-parameter with decreasing salt concentration, indicating ion-ion association at high dilution. A comparison with the results of the Debye-Hückel theory is given; there is qualitative agreement. Our experimental results for 35C1- generally do not support theoretical considerations in the literature, where a Cl--Cl- association was postulated
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Affiliation(s)
- E. Detscher
- Institut für Physikalische Chemie und Electrochemie der Universität Karlsruhe, D-76128 Karlsruhe
| | - H. G. Hertz
- Institut für Physikalische Chemie und Electrochemie der Universität Karlsruhe, D-76128 Karlsruhe
| | - M. Holz
- Institut für Physikalische Chemie und Electrochemie der Universität Karlsruhe, D-76128 Karlsruhe
| | - Xi-an Mao
- Institut für Physikalische Chemie und Electrochemie der Universität Karlsruhe, D-76128 Karlsruhe
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Heyn MP, Braun D, Dencher NA, Fahr A, Holz M, Lindau M, Seiff F, Wallat I, Westerhausen J. Chromophore Location and Charge Displacement in Bacteriorhodopsin. ACTA ACUST UNITED AC 2014. [DOI: 10.1002/bbpc.198800260] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Wichmann JM, Mitrić R, Weise C, Holz M, Lindinger A. Modification of the secondary structure of angiotensin II by substitution of hydrogen with Cs cations: an experimental and theoretical study. Phys Chem Chem Phys 2012; 14:9301-5. [PMID: 22234530 DOI: 10.1039/c2cp22808d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
MALDI mass spectrometry in combination with post-source decay (PSD) analysis is a fast and easy to apply method for peptide sequencing. In this study, the PSD technique was used to investigate the influence of the adaption of one, two, and three caesium cations to angiotensin II in the gas phase. The PSD spectra of caesium-aggregated angiotensin II show far less fragmentation in comparison to the protonated one. In the case of singly (doubly) Cs(+) substituted angiotensin II, the PSD mass spectrum shows only fragments with one (two) Cs cation(s). These results are interpreted in terms of additional interactions of the caesium cation(s) with the peptide. In order to investigate this suggestion, the molecular structures were calculated with semi-empirical molecular dynamic (MD) simulations and further optimized at the quantum chemical level (BP86, SVP) of theory. On the one hand, secondary structures of Cs(+) substituted angiotensin II are more compact than the structure of protonated angiotensin II, indicating electrostatic interactions of the Cs cations and the heterocyclic structures. Moreover, oxyphilic interactions of the cations with the oxygen atoms of the peptide backbone also contribute as further van-der-Waals interactions of the Cs(+) substituted angiotensin II. These interactions are able to explain its higher stability due to reduced dissociation in comparison to the protonated angiotensin II. On the other hand, most MD simulations of doubly and triply Cs(+) substituted angiotensin II show a formation of a [2 Cs] cluster, surrounded by the peptide molecule. The formation of this cluster would explain the lack of singly Cs(+) substituted fragments in the PSD mass spectrum of doubly Cs(+) substituted angiotensin II.
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Affiliation(s)
- J M Wichmann
- Freie Universität Berlin, Institut für Experimentalphysik, Arnimallee 14, 14195, Berlin, Germany
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Patil KJ, Heil SR, Holz M, Zeidler MD. Self-Diffusion Coefficient and Apparent Molar Volume Studies of Crown Ethers in Aqueous (D2O) and CDCl3 Solutions. ACTA ACUST UNITED AC 2010. [DOI: 10.1002/bbpc.19971010112] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Holz M, Weinärtner H, Sacco A. Isotope Effects upon Translational Diffusion as a Probe for Translation-Rotation Coupling in Molecular Liquids. ACTA ACUST UNITED AC 2010. [DOI: 10.1002/bbpc.19900940326] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Pfaar O, Raap U, Holz M, Hörmann K, Klimek L. Pathophysiology of itching and sneezing in allergic rhinitis. Swiss Med Wkly 2009; 139:35-40. [PMID: 19169901 DOI: 10.4414/smw.2009.12468] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Itching and sneezing represent two of the main bothersome symptoms, apart from nasal obstruction and rhinorrhea in allergic rhinitis. Apparently, activation of the central and peripheral nervous system plays a major role in the pathophysiology of this process. Sensory nerves of the afferent trigeminal system including myelinated Adelta-fibres and thin, non-myelinated C-fibres of the nasal mucosa transmit signals generating sensations, including itching and motor reflexes, such as sneezing. These nerves can be stimulated by products of allergic reactions and by external physical and chemical irritants. Via axon reflex inflammatory neuropeptides including the tachykinins substance P (SP) and neurokinin A (NKA) and the calcitonin gene related peptide are released, leading to vasodilatation, increased vascular permeability (concept of "neurogenic inflammation"), glandular activation, leukocyte recruitment and differentiation of immune cells including mast cells, eosinophils, lymphocytes and macrophages. The present paper describes nasal (micro-) anatomy and innervation and explains the central and peripheral mechanisms initiating itching and sneezing in allergic rhinitis. Further, the role of neuropeptides and neurotrophins with regard to neuronal and immune cell activation which might play a key role in the future treatment of allergic rhinitis are discussed.
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Affiliation(s)
- Oliver Pfaar
- Center for Allergy and Rhinology, Wiesbaden, Germany.
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Bardakci M, Tillich JE, Holz M. Characterization of Structure and Transport in Porous Media by Pulsed Field Gradient (PFG) NMR Technique. Part I: Master Curve and Characteristic Inner Length. Chem Eng Technol 2006. [DOI: 10.1002/ceat.200600043] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Schellkes E, Hong X, Holz M, Huniar U, Ahlrichs R, Freyland W. High temperature 93Nb NMR and Raman spectroscopic investigation of the structure and dynamics of solid and liquid NbCl5-alkali chloride solutions. Phys Chem Chem Phys 2003. [DOI: 10.1039/b309570n] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Affiliation(s)
- M Holz
- Institut für pharmazeutische Technologie und Biopharmazie, Philipps-Universität Marburg, Germany
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Abstract
An NMR technique is described which allows the observation of ionic charge carriers moving in the electric field within a porous system saturated with electrolyte solution. This method, which was recently developed in our laboratory, gives experimental access to the study of electric transport in disordered media on a microscopic level and offers new potential for morphology studies. We performed 1H NMR PFG self-diffusion measurements on ions combined with ionic drift velocity measurements by electrophoretic NMR (ENMR), each as a function of observation time Delta. In this way we obtained time-dependent self-diffusion coefficients D(+/-) (Delta) and time-dependent electric mobilities mu(+/-) (Delta) of polyatomic cations and anions in porous media. The porous media used were gels and glass bead packs. From the behaviour of D(+/-) (Delta) and mu(+/-) (Delta) at long observation times the tortuosities T(p) (D(+/-)) and T(p) (mu(+/-)) are derived, allowing a direct experimental check of the validity of the Einstein relation (D(+/-) is proportional to mu(+/-)) in a disordered medium. The tortuosities obtained via the diffusivity of ions are compared with those obtained via the diffusivity of water molecules. We also make a first attempt to derive the specific surface S/V(p) from the time-dependence of the ionic mobility at short observation times and discuss possible advantages of those measurements in morphology studies of porous media.
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Affiliation(s)
- M Holz
- Institut für Physikalische Chemie, Universität Karlsruhe, D-76128, Karlsruhe, Germany.
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Tillich J, Heil S, Holz M. New approach to the characterization of porous media by NMR flow-diffraction studies and time-dependent velocity measurements. Magn Reson Imaging 2001. [DOI: 10.1016/s0730-725x(01)00358-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Heil SR, Holz M. Electrical transport in a disordered medium: NMR measurement of diffusivity and electrical mobility of ionic charge carriers. J Magn Reson 1998; 135:17-22. [PMID: 9799669 DOI: 10.1006/jmre.1998.1536] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Electrical transport in porous media plays an important role in many fields of pure and applied science. The basic microscopic processes of the charge transport have attracted considerable theoretical interest for a long time. However, on a microscopic level there was up to now no experimental access to this problem. In the present paper we demonstrate, by using a suited porous system, that two combined NMR methods can offer such a first experimental access. We apply common PFG NMR methods and the special electrophoretic NMR (ENMR) technique for the measurement of self-diffusion coefficient D+ and electric mobility u+ of a cation ((C4H9)+4) in a disordered gel-like medium (Sephadex LH-20) filled with electrolyte solution. We find a, qualitatively expected, observation time-dependence of D+, but for the first time such a time-dependence is also observed for u+, which means the detection of the phenomenon of "anomalous field assisted diffusion" or "anomalous mobility." For the measurement of the short-time behavior of the mobility a new pulse sequence is presented. The time-dependent mobilities were measured at three different external electrical fields E. From the long-time behavior of D+, u+, and DH2O three independent values for the tortuosity T of the porous system could be derived. We find equality of the tortuosities T(D+) and T(u+), which represents a first experimental proof of the validity of the Einstein relation (D+ approximately u+) in a disordered medium. Finally, we discuss advantages of the possible use of "anomalous field assisted diffusion" over the commonly used "anomalous diffusion" in morphology studies by dynamic imaging in porous media.
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Affiliation(s)
- S R Heil
- Institut für Physikalische Chemie und Elektrochemie, Universität Karlsruhe, Kaiserstr. 12, Karlsruhe, D-76128, Germany.
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Guinard JX, Zoumas-Morse C, Dietz J, Goldberg S, Holz M, Heck E, Amoros A. Does consumption of beer, alcohol, and bitter substances affect bitterness perception? Physiol Behav 1996; 59:625-31. [PMID: 8778845 DOI: 10.1016/0031-9384(95)02124-8] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The relation between consumption of beer, alcohol, and bitter substances was investigated by comparing 20 each of male adults, low users ( < 720 ml/week) and high users ( > 3.61/week) of beer for sensitivity to and like/dislike for the bitterness of isohumulones. Intake of beer, alcohol, and bitter substances was measured with a food frequency questionnaire and a 14-day recall journal. Intake of alcohol (including alcohol from sources other than beer) and bitter substances was higher for high users of beer than for low users. The average bitterness units (BUs) in the beers consumed by the two groups did not differ, indicating that high users do not consume more bitter beers than low users. Detection thresholds for isohumulones in water did not differ between the two groups, but high users had higher difference thresholds for isohumulones in beer (p < 0.10). In time-intensity measurements of bitterness in beer, low users of beer recorded significantly higher maximum intensities (p < 0.001) and shorter total durations (p < 0.001) than high users, with no difference between the two groups for time to maximum intensity and area under the TI curve. There was no significant difference between the two groups for BUs of beers produced by ad lib mixing of low- and high-bitterness beers, or for mean hedonic ratings of various concentrations of isohumulones in beer. These results suggest that intakes of beer, alcohol, and bitter substances are not major determinants of taste responses to the bitterness of isohumulones.
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Affiliation(s)
- J X Guinard
- Department of Nutrition, Pennsylvania State University, University Park 16802, USA
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Abstract
PURPOSE Liposomal formulations of Cyclosporin A (CyA)3 have been described in more than 30 publications to substitute Cremophor EL (CrEL), a triricinoleate ester of ethoxylated glycerol, as drug carrier. However, conflicting reports did not allow to draw consistent conclusions about the influence of liposomes on CyA pharmacokinetics (PK) and pharmacodynamics. METHODS A series of liposomal CyA-formulations with varying liposome composition and lipid dose but constant CyA dose was compared in rats. Data were analysed with a PK-model taking into account the varying volume of distribution with the varying lipid concentration in blood. RESULTS Surface properties and lipid type of liposomes are not important PK predictors of liposomal CyA, at least for small dosages of liposomes. Rather, the absolute lipid amount and the lipophilicity of cyclosporins are critical factors influencing the PK of liposomal CyA. The higher the concentration of lipid in blood and the greater the lipophilicity of cyclosporin is, the higher are the concentrations of CyA in blood. CONCLUSIONS These relations may explain the inconsistent literature results. Together with earlier observations from our group the above findings indicate, that CyA is not caged in the liposomal membranes. Reports in literature, which claim lower clearance and a lower volume of distribution of CyA in obese rats compared to lean rats, support our assumption about the involved mechanisms. A semi-quantitative model of CyA distribution is presented, which points to the variable free fraction of CyA in plasma as the crucial factor for all previously reported phenomena in liposomal CyA formulations.
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Affiliation(s)
- A Fahr
- Drug Delivery Systems, Sandoz Pharma AG, Basel, Switzerland
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Otto H, Marti T, Holz M, Mogi T, Stern LJ, Engel F, Khorana HG, Heyn MP. Substitution of amino acids Asp-85, Asp-212, and Arg-82 in bacteriorhodopsin affects the proton release phase of the pump and the pK of the Schiff base. Proc Natl Acad Sci U S A 1990; 87:1018-22. [PMID: 2153966 PMCID: PMC53401 DOI: 10.1073/pnas.87.3.1018] [Citation(s) in RCA: 195] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Photocycle and flash-induced proton release and uptake were investigated for bacteriorhodopsin mutants in which Asp-85 was replaced by Ala, Asn, or Glu; Asp-212 was replaced by Asn or Glu; Asp-115 was replaced by Ala, Asn, or Glu; Asp-96 was replaced by Ala, Asn, or Glu; and Arg-82 was replaced by Ala or Gln in dimyristoylphosphatidylcholine/3-[(3-cholamidopropyl)dimethylammonio]-1- propanesulfonate micelles at pH 7.3. In the Asp-85----Ala and Asp-85----Asn mutants, the absence of the charged carboxyl group leads to a blue chromophore at 600 and 595 nm, respectively, and lowers the pK of the Schiff base deprotonation to 8.2 and 7, respectively, suggesting a role for Asp-85 as counterion to the Schiff base. The early part of the photocycles of the Asp-85----Ala and Asp-85----Asn mutants is strongly perturbed; the formation of a weak M-like intermediate is slowed down about 100-fold over wild type. In both mutants, proton release is also slower but clearly precedes the rise of M. The amplitude of the early (less than 0.2 microseconds) reversed photovoltage component in the Asp-85----Asn mutant is very large, and the net charge displacement is close to zero, indicating proton release and uptake on the cytoplasmic side of the membrane. The data suggest an obligatory role for Asp-85 in the efficient deprotonation of the Schiff base and in the proton release phase, probably as proton acceptor. In the Asp-212----Asn mutant, the rise of the absorbance change at 410 nm is slowed down to 220 microsecond, its amplitude is small, and the release of protons is delayed to 1.9 ms. The absorbance changes at 650 nm indicate perturbations in the early time range with a slow K intermediate. Thus Asp-212 also participates in the early events of charge translocation and deprotonation of the Schiff base. In the Arg-82----Gln mutant, no net transient proton release was observed, whereas, in the Arg-82----Ala mutant, uptake and release were reversed. The pK shift of the purple-to-blue transition in the Asp-85----Glu, Arg-82----Ala, and Arg-82----Gln mutants and the similarity in the photocycle and photoelectrical signals of the Asp-85----Ala, Asp-85----Asn, and Asp-212----Asn mutants suggest the interaction between Asp-85, Arg-82, Asp-212, and the Schiff base as essential for proton release.
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Affiliation(s)
- H Otto
- Biophysics Group, Freie Universität Berlin, Federal Republic of Germany
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Holz M, Sacco A, Trotta M. Rotational molecular motion and solvation of Na+ and Cs+ in water-dimethylacetamide. A nuclear magnetic relaxation study. J SOLUTION CHEM 1990. [DOI: 10.1007/bf00646613] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Otto H, Marti T, Holz M, Mogi T, Lindau M, Khorana HG, Heyn MP. Aspartic acid-96 is the internal proton donor in the reprotonation of the Schiff base of bacteriorhodopsin. Proc Natl Acad Sci U S A 1989; 86:9228-32. [PMID: 2556706 PMCID: PMC298467 DOI: 10.1073/pnas.86.23.9228] [Citation(s) in RCA: 248] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Above pH 8 the decay of the photocycle intermediate M of bacteriorhodopsin splits into two components: the usual millisecond pH-independent component and an additional slower component with a rate constant proportional to the molar concentration of H+, [H+]. In parallel, the charge translocation signal associated with the reprotonation of the Schiff base develops a similar slow component. These observations are explained by a two-step reprotonation mechanism. An internal donor first reprotonates the Schiff base in the decay of M to N and is then reprotonated from the cytoplasm in the N----O transition. The decay rate of N is proportional to [H+]. By postulating a back reaction from N to M, the M decay splits up into two components, with the slower one having the same pH dependence as the decay of N. Photocycle, photovoltage, and pH-indicator experiments with mutants in which aspartic acid-96 is replaced by asparagine or alanine, which we call D96N and D96A, suggest that Asp-96 is the internal proton donor involved in the re-uptake pathway. In both mutants the stoichiometry of proton pumping is the same as in wild type. However, the M decay is monophasic, with the logarithm of the decay time [log (tau)] linearly dependent on pH, suggesting that the internal donor is absent and that the Schiff base is directly reprotonated from the cytoplasm. Like H+, azide increases the M decay rate in D96N. The rate constant is proportional to the azide concentration and can become greater than 100 times greater than in wild type. Thus, azide functions as a mobile proton donor directly reprotonating the Schiff base in a bimolecular reaction. Both the proton and azide effects, which are absent in wild type, indicate that the internal donor is removed and that the reprotonation pathway is different from wild type in these mutants.
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Affiliation(s)
- H Otto
- Biophysics Group, Freie Universität Berlin, Federal Republic of Germany
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Weingärtner H, Holz M, Sacco A, Trotta M. The effect of site‐specific isotopic substitutions on transport coefficients of liquid methanol. J Chem Phys 1989. [DOI: 10.1063/1.457016] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Holz M, Drachev LA, Mogi T, Otto H, Kaulen AD, Heyn MP, Skulachev VP, Khorana HG. Replacement of aspartic acid-96 by asparagine in bacteriorhodopsin slows both the decay of the M intermediate and the associated proton movement. Proc Natl Acad Sci U S A 1989; 86:2167-71. [PMID: 2648392 PMCID: PMC286872 DOI: 10.1073/pnas.86.7.2167] [Citation(s) in RCA: 162] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The photocycle, electrical charge translocation, and release and uptake of protons from the aqueous phase and release and uptake of protons from the aqueous phase were investigated for bacteriorhodopsin mutants with aspartic acid-96 replaced by asparagine or glutamic acid. At neutral pH the main effect of the Asp-96----Asn mutation is to slow by 2 orders of magnitude the decay of the M intermediate and the concomitant charge displacement associated with the reprotonation of the Schiff base from the cytoplasmic side of the membrane. The proton uptake measured with the indicator dye pyranine is likewise slowed without affecting the stoichiometry of proton pumping. The corresponding results for the Asp-96----Glu mutant, on the other hand, are very close to those for the wild-type protein. These results provide a kinetic explanation for the fact that at pH 7 and saturating light intensities the steady-state proton pumping is almost abolished in the Asp-96----Asn mutant but is close to normal in the Asp-96----Glu mutant. Thus, the pump is simply turning over much more slowly in the Asp-96----Asn mutant. The time constants of the decay of M and the associated charge translocation increase strongly with increasing pH for the Asp-96----Asn mutant but are virtually pH-independent for the Asp-96----Glu mutant and wild-type bacteriorhodopsin. At pH 5 the M decay of the Asp-96----Asn mutant is as fast as for wild type. These results suggest that Asp-96 serves as an internal proton donor in the proton-uptake pathway from the cytoplasm to the Schiff base.
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Affiliation(s)
- M Holz
- Biophysics Group, Freie Universität Berlin, Federal Republic of Germany
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Holz M, Strecker EP, Weiss KH. NMR tomography for the visualization of the diffusion of Gd-DTPA in agar-gel and in brain tissue--in vitro studies. Eur J Radiol 1987; 7:137-41. [PMID: 3595623] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Serial magnetic resonance images of a diffusion model and of brain specimens have been performed to study the diffusion behavior of a paramagnetic complex (Gd-DTPA). The model consisted of solidified agar gel with layered Gd-DTPA solution on top of the gel. Corresponding studies have been performed with the brain specimen to visualize the penetration of the marker through the extracellular space into the brain tissue. Diffusion coefficients for the agar gel and the brain tissue model have been calculated. Magnetic resonance tomography proves to be a promising method for the study of complicated diffusion processes of paramagnetic complexes in biological tissue.
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Abstract
Arrays of lasers that are locked together with the same phase produce far-field patterns with a significant amount of the energy residing in the sidelobes. We describe a technique that channels the majority of the sidelobe energy into the desired central lobe.
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Strecker EP, Holz M, Meyer-Waarden K, Diggs J, Rausch DS, James AE. Influence of NMR measuring sequences and gradient variation on signals from flowing systems. Magnetic resonance tomography on experimental models. Eur J Radiol 1986; 6:53-8. [PMID: 3699038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The influence of flow on MR tomography images and signal intensities has been studied using experimental model tubes and an aqueous NiCl2 solution having the same relaxation time as human blood. We applied the inversion recovery (IR) and the spin-echo (SE) sequence on a .15T MR tomography system. The influence of RF pulse distance (tau) in the IR and SE experiment as well as the influence of magnetic z-gradient strength on the flow images has been investigated. IR images revealed that signals from flowing systems recover more rapidly due to influx of non-inverted longitudinal magnetization into the scan slice. SE images in presence of flow are characterized by signal intensity loss with increasing time caused by the outflow and dephasing of transverse magnetization. With increasing strength of the z-gradient, the MR signals of flowing fluids decrease drastically. Thus for detection of flow, all the above mentioned parameters are of importance.
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Hertz H, Holz M. Longitudinal proton relaxation rates in aqueous Ni2+ solutions as a function of the temperature, frequency, and pH Value. ACTA ACUST UNITED AC 1985. [DOI: 10.1016/0022-2364(85)90153-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Braun BM, Holz M. Separation of local asymmetry and selective solvation effects using the quadrupole relaxation of the23Na+ and87Rb+ ions in acetonitrile-water mixtures. J SOLUTION CHEM 1983. [DOI: 10.1007/bf00647381] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Abstract
We developed a rapid-scanning, light-scattering densitometer by which extensive measurements of band migration speeds and band profiles of chemotactic bands of Escherichia coli in motility buffer both with and without serine have been made. The purpose is to test the applicability of the phenomenological model proposed by Keller and Segel (J. Theor. Biol. 1971. 30:235) and to determine the motility (mu) and chemotactic (delta) coefficients of the bacteria. We extend the previous analytical solution of the simplified Keller-Segel model by taking into account the substrate diffusion which turns out to be significant in the case of oxygen. We demonstrate that unique sets of values of mu and delta can be obtained for various samples at different stages of migration by comparing the numerical solution of the model equation and the experimental data. The rapid-scanning technique also reveals a hitherto unobserved time-dependent fine structure in the bacterial band. We give a qualitative argument to show that the fine structure is an example of the dissipative structure that arises from a nonlinear coupling between the bacterial density and the oxygen concentration gradient. Implications for a further study of the dissipative structure in testing the Keller-Segel model of chemotaxis are briefly discussed.
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Holz M, Chen SH. Rotational-translational models for interpretation of quasi-elastic light scattering spectra of motile bacteria. Appl Opt 1978; 17:3197-3204. [PMID: 20203949 DOI: 10.1364/ao.17.003197] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Quasi-elastic light scattering is a powerful tool for studying dynamic behavior of motile bacteria in liquid suspension. Previously we proposed an ellipsoidal structural model to account for the straight line motion of E. coli bacteria. We have in this article extended our structural model to include rotational motions superimposed on the translational motion of the center of mass. A general formulation is given by which the light scattering spectrum of any rotational-translational motion of a structured particle can be calculated. Specific calculations are carried out for three types of rotational motions, namely, planar wiggling motion, pure rotation, and helical rotation, around the average direction of motion. Further narrowing of the scattered field correlation function as compared with that of the straight line motion is observed in all three cases. We finally compare the helical rotation model with our previous experimental results for E. coli and find a substantial improvement over that of the straight line motion model.
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Weing�rtner H, Holz M, Hertz HG. Some structural aspects in binary aqueous mixtures of simple amides from rotational molecular motions. J SOLUTION CHEM 1978. [DOI: 10.1007/bf00652019] [Citation(s) in RCA: 37] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Abstract
We report the observation of migrating chemotactic bands of Escherichia coli in a buffer solution. The temporal development of the bacterial density profile is observed by the scattered light intensity as the band migrates through a stationary laser beam. We have made a preliminary analysis of the observed band profile with help of the Keller-Segel theory. The model accounts for only some aspects of the observed time evolution of the density profile. The microscopic motility characteristics of the E. coli in the band are simultaneously studied by photon correlation. The measured correlation functions are analyzed to obtain the spatial dependence of the half-width within the band. A simple analytical model is proposed to account for the contribution of the twiddle motion to the correlation function. By analyzing the correlation function as a superposition of straight-line and twiddle motions, we obtain a satisfactory agreement between the theory and the measured angular dependence of the line shape. As a consequence we are able to extract a parameter beta, which measures the average fraction of twiddling bacteria in the center of the band at a given time.
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Abstract
An extensive study has been made of the angular dependence of the intensity as well as the quasi-elastic intensity correlation function of light scattered from a dilute suspension of E. Coli K(12) bacteria in solution using the photon correlation technique. We have demonstrated that it is essential to consider the shape as well as the internal structure of bacteria in order to account fully for both the scattered intensity and the field self-correlation function as reduced from the intensity correlation function. The simple structure model previously proposed accounts well for both the intensity and diffusion data with a reasonable set of parameters. For the case of motile bacteria the observed field correlation function at small scattering angles is well represented by assuming a mixture of diffusive and straight line swimming motions of the bacteria. At larger scattering angles contributions of rotational motions become significant.
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Abstract
Movements of individual E. coli bacteria in solution are detected by a one-dimensional fringe system formed in the focal region of two crossed laser beams. The time modulation of the scattered light intensity is used to deduce the instantaneous speed of the bacterial motion as it enters into the focal region. A method is described as being capable of testing the isotropic speed distribution function without the complications associated with the finite size and structural effects that influence the interpretation of the conventional light-scattering spectra.
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Affiliation(s)
- M Holz
- Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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