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Newsham KK, Eidesen PB, Davey ML, Axelsen J, Courtecuisse E, Flintrop C, Johansson AG, Kiepert M, Larsen SE, Lorberau KE, Maurset M, McQuilkin J, Misiak M, Pop A, Thompson S, Read DJ. Arbuscular mycorrhizas are present on Spitsbergen. Mycorrhiza 2017; 27:725-731. [PMID: 28695334 DOI: 10.1007/s00572-017-0785-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [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: 02/28/2017] [Accepted: 06/12/2017] [Indexed: 05/26/2023]
Abstract
A previous study of 76 plant species on Spitsbergen in the High Arctic concluded that structures resembling arbuscular mycorrhizas were absent from roots. Here, we report a survey examining the roots of 13 grass and forb species collected from 12 sites on the island for arbuscular mycorrhizal (AM) colonisation. Of the 102 individuals collected, we recorded AM endophytes in the roots of 41 plants of 11 species (Alopecurus ovatus, Deschampsia alpina, Festuca rubra ssp. richardsonii, putative viviparous hybrids of Poa arctica and Poa pratensis, Poa arctica ssp. arctica, Trisetum spicatum, Coptidium spitsbergense, Ranunculus nivalis, Ranunculus pygmaeus, Ranunculus sulphureus and Taraxacum arcticum) sampled from 10 sites. Both coarse AM endophyte, with hyphae of 5-10 μm width, vesicles and occasional arbuscules, and fine endophyte, consisting of hyphae of 1-3 μm width and sparse arbuscules, were recorded in roots. Coarse AM hyphae, vesicles, arbuscules and fine endophyte hyphae occupied 1.0-30.7, 0.8-18.3, 0.7-11.9 and 0.7-12.8% of the root lengths of colonised plants, respectively. Principal component analysis indicated no associations between the abundances of AM structures in roots and edaphic factors. We conclude that the AM symbiosis is present in grass and forb roots on Spitsbergen.
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Affiliation(s)
- K K Newsham
- Department of Arctic Biology, The University Centre in Svalbard, P.O. Box 156, N-9171, Longyearbyen, Svalbard, Norway.
- British Antarctic Survey, Natural Environment Research Council, High Cross, Madingley Road, Cambridge, CB3 0ET, UK.
| | - P B Eidesen
- Department of Arctic Biology, The University Centre in Svalbard, P.O. Box 156, N-9171, Longyearbyen, Svalbard, Norway
| | - M L Davey
- Department of Arctic Biology, The University Centre in Svalbard, P.O. Box 156, N-9171, Longyearbyen, Svalbard, Norway
| | - J Axelsen
- Department of Arctic Biology, The University Centre in Svalbard, P.O. Box 156, N-9171, Longyearbyen, Svalbard, Norway
| | - E Courtecuisse
- Department of Arctic Biology, The University Centre in Svalbard, P.O. Box 156, N-9171, Longyearbyen, Svalbard, Norway
| | - C Flintrop
- Department of Arctic Biology, The University Centre in Svalbard, P.O. Box 156, N-9171, Longyearbyen, Svalbard, Norway
| | - A G Johansson
- Department of Arctic Biology, The University Centre in Svalbard, P.O. Box 156, N-9171, Longyearbyen, Svalbard, Norway
| | - M Kiepert
- Department of Arctic Biology, The University Centre in Svalbard, P.O. Box 156, N-9171, Longyearbyen, Svalbard, Norway
| | - S E Larsen
- Department of Arctic Biology, The University Centre in Svalbard, P.O. Box 156, N-9171, Longyearbyen, Svalbard, Norway
| | - K E Lorberau
- Department of Arctic Biology, The University Centre in Svalbard, P.O. Box 156, N-9171, Longyearbyen, Svalbard, Norway
| | - M Maurset
- Department of Arctic Biology, The University Centre in Svalbard, P.O. Box 156, N-9171, Longyearbyen, Svalbard, Norway
| | - J McQuilkin
- Department of Arctic Biology, The University Centre in Svalbard, P.O. Box 156, N-9171, Longyearbyen, Svalbard, Norway
| | - M Misiak
- Department of Arctic Biology, The University Centre in Svalbard, P.O. Box 156, N-9171, Longyearbyen, Svalbard, Norway
| | - A Pop
- Department of Arctic Biology, The University Centre in Svalbard, P.O. Box 156, N-9171, Longyearbyen, Svalbard, Norway
| | - S Thompson
- Department of Arctic Biology, The University Centre in Svalbard, P.O. Box 156, N-9171, Longyearbyen, Svalbard, Norway
| | - D J Read
- Department of Arctic Biology, The University Centre in Svalbard, P.O. Box 156, N-9171, Longyearbyen, Svalbard, Norway
- Department of Animal and Plant Sciences, The University of Sheffield, Western Bank, Sheffield, S10 2TN, UK
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Doleman B, Heinink TP, Read DJ, Faleiro RJ, Lund JN, Williams JP. A systematic review and meta-regression analysis of prophylactic gabapentin for postoperative pain. Anaesthesia 2015; 70:1186-204. [DOI: 10.1111/anae.13179] [Citation(s) in RCA: 115] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/29/2015] [Indexed: 12/11/2022]
Affiliation(s)
| | | | | | | | - J. N. Lund
- Department of Surgery; University of Nottingham; Derby UK
| | - J. P. Williams
- Department of Anaesthesia; University of Nottingham; Derby UK
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Affiliation(s)
- D. J. Read
- Department of Applied Mathematics, University of Leeds, Leeds, LS2 9JT, U.K., and Department of Mathematics, University of Reading, Reading RG6 6AX, U.K
| | - K. Jagannathan
- Department of Applied Mathematics, University of Leeds, Leeds, LS2 9JT, U.K., and Department of Mathematics, University of Reading, Reading RG6 6AX, U.K
| | - A. E. Likhtman
- Department of Applied Mathematics, University of Leeds, Leeds, LS2 9JT, U.K., and Department of Mathematics, University of Reading, Reading RG6 6AX, U.K
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Abstract
The authors extend their earlier work on the stability of a reacting binary polymer blend with respect to demixing [D. J. Read, Macromolecules 31, 899 (1998); P. I. C. Teixeira et al., Macromolecules 33, 387 (2000)] to the case where one of the polymers is rod-like and may order nematically. As before, the authors combine the random phase approximation for the free energy with a Markov chain model for the chemistry to obtain the spinodal as a function of the relevant degrees of reaction. These are then calculated by assuming a simple second-order chemical kinetics. Results are presented, for linear systems, which illustrate the effects of varying the proportion of coils and rods, their relative sizes, and the strength of the nematic interaction between the rods.
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Affiliation(s)
- P I C Teixeira
- Instituto Superior de Engenharia de Lisboa, Rua Conselheiro Emídio Navarro 1, P-1950-062 Lisbon, Portugal.
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Upson R, Read DJ, Newsham KK. Widespread association between the ericoid mycorrhizal fungus Rhizoscyphus ericae and a leafy liverwort in the maritime and sub-Antarctic. New Phytol 2007; 176:460-471. [PMID: 17888123 DOI: 10.1111/j.1469-8137.2007.02178.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
A recent study identified a fungal isolate from the Antarctic leafy liverwort Cephaloziella varians as the ericoid mycorrhizal associate Rhizoscyphus ericae. However, nothing is known about the wider Antarctic distribution of R. ericae in C. varians, and inoculation experiments confirming the ability of the fungus to form coils in the liverwort are lacking. Using direct isolation and baiting with Vaccinium macrocarpon seedlings, fungi were isolated from C. varians sampled from eight sites across a 1875-km transect through sub- and maritime Antarctica. The ability of an isolate to form coils in aseptically grown C. varians was also tested. Fungi with 98-99% sequence identity to R. ericae internal transcribed spacer (ITS) region and partial large subunit ribosomal (r)DNA sequences were frequently isolated from C. varians at all sites sampled. The EF4/Fung5 primer set did not amplify small subunit rDNA from three of five R. ericae isolates, probably accounting for the reported absence of the fungus from C. varians in a previous study. Rhizoscyphus ericae was found to colonize aseptically-grown C. varians intracellularly, forming hyphal coils. This study shows that the association between R. ericae and C. varians is apparently widespread in Antarctica, and confirms that R. ericae is at least in part responsible for the formation of the coils observed in rhizoids of field-collected C. varians.
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Affiliation(s)
- R Upson
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK
- Biological Sciences Division, British Antarctic Survey, Natural Environment Research Council, High Cross, Madingley Road, Cambridge CB3 0ET, UK
| | - D J Read
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK
| | - K K Newsham
- Biological Sciences Division, British Antarctic Survey, Natural Environment Research Council, High Cross, Madingley Road, Cambridge CB3 0ET, UK
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Graham RS, Bent J, Hutchings LR, Richards RW, Groves DJ, Embery J, Nicholson TM, McLeish TCB, Likhtman AE, Harlen OG, Read DJ, Gough T, Spares R, Coates PD, Grillo I. Measuring and Predicting the Dynamics of Linear Monodisperse Entangled Polymers in Rapid Flow through an Abrupt Contraction. A Small Angle Neutron Scattering Study. Macromolecules 2006. [DOI: 10.1021/ma052357z] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- R. S. Graham
- Department of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, U.K., Department of Chemistry, University of Durham, Durham DH1 3LE, U.K., Department of Applied Mathematics, University of Leeds, Leeds LS2 9JT, U.K., School of Engineering, Design and Technology, University of Bradford, Bradford BD7 1DP, U.K., Institut Laue-Langevin, 34042 Grenoble Cedex 9, France, Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109, Division of Chemical Engineering, University of
| | - J. Bent
- Department of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, U.K., Department of Chemistry, University of Durham, Durham DH1 3LE, U.K., Department of Applied Mathematics, University of Leeds, Leeds LS2 9JT, U.K., School of Engineering, Design and Technology, University of Bradford, Bradford BD7 1DP, U.K., Institut Laue-Langevin, 34042 Grenoble Cedex 9, France, Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109, Division of Chemical Engineering, University of
| | - L. R. Hutchings
- Department of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, U.K., Department of Chemistry, University of Durham, Durham DH1 3LE, U.K., Department of Applied Mathematics, University of Leeds, Leeds LS2 9JT, U.K., School of Engineering, Design and Technology, University of Bradford, Bradford BD7 1DP, U.K., Institut Laue-Langevin, 34042 Grenoble Cedex 9, France, Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109, Division of Chemical Engineering, University of
| | - R. W. Richards
- Department of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, U.K., Department of Chemistry, University of Durham, Durham DH1 3LE, U.K., Department of Applied Mathematics, University of Leeds, Leeds LS2 9JT, U.K., School of Engineering, Design and Technology, University of Bradford, Bradford BD7 1DP, U.K., Institut Laue-Langevin, 34042 Grenoble Cedex 9, France, Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109, Division of Chemical Engineering, University of
| | - D. J. Groves
- Department of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, U.K., Department of Chemistry, University of Durham, Durham DH1 3LE, U.K., Department of Applied Mathematics, University of Leeds, Leeds LS2 9JT, U.K., School of Engineering, Design and Technology, University of Bradford, Bradford BD7 1DP, U.K., Institut Laue-Langevin, 34042 Grenoble Cedex 9, France, Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109, Division of Chemical Engineering, University of
| | - J. Embery
- Department of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, U.K., Department of Chemistry, University of Durham, Durham DH1 3LE, U.K., Department of Applied Mathematics, University of Leeds, Leeds LS2 9JT, U.K., School of Engineering, Design and Technology, University of Bradford, Bradford BD7 1DP, U.K., Institut Laue-Langevin, 34042 Grenoble Cedex 9, France, Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109, Division of Chemical Engineering, University of
| | - T. M. Nicholson
- Department of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, U.K., Department of Chemistry, University of Durham, Durham DH1 3LE, U.K., Department of Applied Mathematics, University of Leeds, Leeds LS2 9JT, U.K., School of Engineering, Design and Technology, University of Bradford, Bradford BD7 1DP, U.K., Institut Laue-Langevin, 34042 Grenoble Cedex 9, France, Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109, Division of Chemical Engineering, University of
| | - T. C. B. McLeish
- Department of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, U.K., Department of Chemistry, University of Durham, Durham DH1 3LE, U.K., Department of Applied Mathematics, University of Leeds, Leeds LS2 9JT, U.K., School of Engineering, Design and Technology, University of Bradford, Bradford BD7 1DP, U.K., Institut Laue-Langevin, 34042 Grenoble Cedex 9, France, Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109, Division of Chemical Engineering, University of
| | - A. E. Likhtman
- Department of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, U.K., Department of Chemistry, University of Durham, Durham DH1 3LE, U.K., Department of Applied Mathematics, University of Leeds, Leeds LS2 9JT, U.K., School of Engineering, Design and Technology, University of Bradford, Bradford BD7 1DP, U.K., Institut Laue-Langevin, 34042 Grenoble Cedex 9, France, Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109, Division of Chemical Engineering, University of
| | - O. G. Harlen
- Department of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, U.K., Department of Chemistry, University of Durham, Durham DH1 3LE, U.K., Department of Applied Mathematics, University of Leeds, Leeds LS2 9JT, U.K., School of Engineering, Design and Technology, University of Bradford, Bradford BD7 1DP, U.K., Institut Laue-Langevin, 34042 Grenoble Cedex 9, France, Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109, Division of Chemical Engineering, University of
| | - D. J. Read
- Department of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, U.K., Department of Chemistry, University of Durham, Durham DH1 3LE, U.K., Department of Applied Mathematics, University of Leeds, Leeds LS2 9JT, U.K., School of Engineering, Design and Technology, University of Bradford, Bradford BD7 1DP, U.K., Institut Laue-Langevin, 34042 Grenoble Cedex 9, France, Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109, Division of Chemical Engineering, University of
| | - T. Gough
- Department of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, U.K., Department of Chemistry, University of Durham, Durham DH1 3LE, U.K., Department of Applied Mathematics, University of Leeds, Leeds LS2 9JT, U.K., School of Engineering, Design and Technology, University of Bradford, Bradford BD7 1DP, U.K., Institut Laue-Langevin, 34042 Grenoble Cedex 9, France, Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109, Division of Chemical Engineering, University of
| | - R. Spares
- Department of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, U.K., Department of Chemistry, University of Durham, Durham DH1 3LE, U.K., Department of Applied Mathematics, University of Leeds, Leeds LS2 9JT, U.K., School of Engineering, Design and Technology, University of Bradford, Bradford BD7 1DP, U.K., Institut Laue-Langevin, 34042 Grenoble Cedex 9, France, Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109, Division of Chemical Engineering, University of
| | - P. D. Coates
- Department of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, U.K., Department of Chemistry, University of Durham, Durham DH1 3LE, U.K., Department of Applied Mathematics, University of Leeds, Leeds LS2 9JT, U.K., School of Engineering, Design and Technology, University of Bradford, Bradford BD7 1DP, U.K., Institut Laue-Langevin, 34042 Grenoble Cedex 9, France, Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109, Division of Chemical Engineering, University of
| | - I. Grillo
- Department of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, U.K., Department of Chemistry, University of Durham, Durham DH1 3LE, U.K., Department of Applied Mathematics, University of Leeds, Leeds LS2 9JT, U.K., School of Engineering, Design and Technology, University of Bradford, Bradford BD7 1DP, U.K., Institut Laue-Langevin, 34042 Grenoble Cedex 9, France, Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109, Division of Chemical Engineering, University of
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Blanchard A, Graham RS, Heinrich M, Pyckhout-Hintzen W, Rciher D, Likhtman AE, McLeish TCB, Read DJ, Straube E, Kohlbrecher J. Small angle neutron scattering observation of chain retraction after a large step deformation. Phys Rev Lett 2005; 95:166001. [PMID: 16281325 DOI: 10.1103/physrevlett.95.166001] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
The process of retraction in entangled linear chains after a fast nonlinear stretch was detected from time-resolved but quenched small angle neutron scattering (SANS) experiments on long, well-entangled polyisoprene chains. The statically obtained SANS data cover the relevant time regime for retraction, and they provide a direct, microscopic verification of this nonlinear process as predicted by the tube model. Clear, quantitative agreement is found with recent theories of contour length fluctuations and convective constraint release, using parameters obtained mainly from linear rheology. The theory captures the full range of scattering vectors once the crossover to fluctuations on length scales below the tube diameter is accounted for.
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Affiliation(s)
- A Blanchard
- Jülich, Institut für Festkörperforschung, Germany
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Spehn EM, Hector A, Joshi J, Scherer-Lorenzen M, Schmid B, Bazeley-White E, Beierkuhnlein C, Caldeira MC, Diemer M, Dimitrakopoulos PG, Finn JA, Freitas H, Giller PS, Good J, Harris R, Högberg P, Huss-Danell K, Jumpponen A, Koricheva J, Leadley PW, Loreau M, Minns A, Mulder CPH, O'Donovan G, Otway SJ, Palmborg C, Pereira JS, Pfisterer AB, Prinz A, Read DJ, Schulze ED, Siamantziouras ASD, Terry AC, Troumbis AY, Woodward FI, Yachi S, Lawton JH. ECOSYSTEM EFFECTS OF BIODIVERSITY MANIPULATIONS IN EUROPEAN GRASSLANDS. ECOL MONOGR 2005. [DOI: 10.1890/03-4101] [Citation(s) in RCA: 392] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Taylor AFS, Gebauer G, Read DJ. Uptake of nitrogen and carbon from double-labelled ( 15 N and 13 C) glycine by mycorrhizal pine seedlings. New Phytol 2004; 164:383-388. [PMID: 33873558 DOI: 10.1111/j.1469-8137.2004.01164.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
• While it is accepted that many ectomycorrhizal fungi can assimilate organic substrates and facilitate transfer of their elemental components to plants, the fate of the carbon contained in these materials remains uncertain. Here we investigate the compartmentation of carbon and nitrogen in ectomycorrhizal seedlings of Pinus sylvestris fed with double-labelled (15 N and 13 C) glycine as their sole N source. • Using isotope ratio mass spectrometry, the quantities of N and C derived from this glycine were determined in sequentially harvested samples of mycorrhizas, roots and shoots. • Whereas considerable quantities of 15 N were observed in the mycorrhizal tips, roots and shoots, comparable amounts of 13 C were observed only in mycorrhizal tips and roots. • It is clearly important to resolve the role of compound specificity as a factor determining the extent of amino-acid C transfer from roots to shoots. However, from the standpoint of the C budget of the whole plant, wherever heterotrophically acquired C is available as an energy source it will reduce demands on photosynthetically fixed sources of the element.
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Affiliation(s)
- A F S Taylor
- Department of Forest Mycology and Pathology, Swedish University of Agricultural Sciences, Box 7026, S-750 07 Uppsala, Sweden
| | - G Gebauer
- Institute for Plant Ecology, University of Bayreuth, D-95440 Bayreuth, Germany
| | - D J Read
- Department of Animal and Plant Sciences, PO Box 601, University of Sheffield, Sheffield S10 2UQ, UK
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Leake JR, McKendrick SL, Bidartondo M, Read DJ. Symbiotic germination and development of the myco-heterotroph Monotropa hypopitys in nature and its requirement for locally distributed Tricholoma spp. New Phytol 2004; 163:405-423. [PMID: 33873615 DOI: 10.1111/j.1469-8137.2004.01115.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
• Germination and symbiotic development of the myco-heterotrophic plant Monotropa hypopitys were studied by sequential recovery of packets of seed buried in dune slacks in relation to distance from mature M. hypopitys and presence and absence of shoots of its autotrophic coassociate Salix repens. • Fungal associates of M. hypopitys growing under S. repens in the dune slacks, and under S. caprea and Pinus sylvestris at two other locations in the UK, were identified by molecular analysis. • While the earliest stage of germination could be found in the absence both of mature M. hypopitys, and S. repens, further development was dependent upon mycorrhizal colonisation, which was most common close to these plants. Molecular analysis showed that when growing with Salix, M. hypopitys associated with the Salix-specific ectomycorrhizal fungus Tricholoma cingulatum, whereas under Pinus it was colonised by the closely related, Pinaceae-specific, T. terreum. • We establish the first definitive chronology of development of M. hypopitys and highlight its critical dependence upon, and specificity for, locally distributed Tricholoma species that link the myco-heterotroph to its autotrophic coassociates.
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Affiliation(s)
- J R Leake
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK
| | - S L McKendrick
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK
| | - M Bidartondo
- Department of Plant and Microbial Ecology, University of California, Berkeley, CA 94720-3102, USA
| | - D J Read
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK
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Heinrich M, Pyckhout-Hintzen W, Allgaier J, Richter D, Straube E, McLeish TCB, Wiedenmann A, Blackwell RJ, Read DJ. Small-Angle Neutron Scattering Study of the Relaxation of a Melt of Polybutadiene H-Polymers Following a Large Step Strain. Macromolecules 2004. [DOI: 10.1021/ma0304372] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- M. Heinrich
- Forschungszentrum Jülich, Institut für Festkörperforschung, Postfach 1913, D-52425 Jülich, Germany; Martin-Luther-Universität Halle-Wittenberg, Fachbereich Physik, D-06099 Halle, Germany; Department of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, U.K.; Hahn-Meitner Institut, D-14091 Berlin, Germany; Department of Applied Maths and Theoretical Physics, Centre for Mathematical Sciences, Wilberforce Road, Cambridge, CB3 0WA, U.K.; and Department of Applied Mathematics, University of Leeds,
| | - W. Pyckhout-Hintzen
- Forschungszentrum Jülich, Institut für Festkörperforschung, Postfach 1913, D-52425 Jülich, Germany; Martin-Luther-Universität Halle-Wittenberg, Fachbereich Physik, D-06099 Halle, Germany; Department of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, U.K.; Hahn-Meitner Institut, D-14091 Berlin, Germany; Department of Applied Maths and Theoretical Physics, Centre for Mathematical Sciences, Wilberforce Road, Cambridge, CB3 0WA, U.K.; and Department of Applied Mathematics, University of Leeds,
| | - J. Allgaier
- Forschungszentrum Jülich, Institut für Festkörperforschung, Postfach 1913, D-52425 Jülich, Germany; Martin-Luther-Universität Halle-Wittenberg, Fachbereich Physik, D-06099 Halle, Germany; Department of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, U.K.; Hahn-Meitner Institut, D-14091 Berlin, Germany; Department of Applied Maths and Theoretical Physics, Centre for Mathematical Sciences, Wilberforce Road, Cambridge, CB3 0WA, U.K.; and Department of Applied Mathematics, University of Leeds,
| | - D. Richter
- Forschungszentrum Jülich, Institut für Festkörperforschung, Postfach 1913, D-52425 Jülich, Germany; Martin-Luther-Universität Halle-Wittenberg, Fachbereich Physik, D-06099 Halle, Germany; Department of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, U.K.; Hahn-Meitner Institut, D-14091 Berlin, Germany; Department of Applied Maths and Theoretical Physics, Centre for Mathematical Sciences, Wilberforce Road, Cambridge, CB3 0WA, U.K.; and Department of Applied Mathematics, University of Leeds,
| | - E. Straube
- Forschungszentrum Jülich, Institut für Festkörperforschung, Postfach 1913, D-52425 Jülich, Germany; Martin-Luther-Universität Halle-Wittenberg, Fachbereich Physik, D-06099 Halle, Germany; Department of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, U.K.; Hahn-Meitner Institut, D-14091 Berlin, Germany; Department of Applied Maths and Theoretical Physics, Centre for Mathematical Sciences, Wilberforce Road, Cambridge, CB3 0WA, U.K.; and Department of Applied Mathematics, University of Leeds,
| | - T. C. B. McLeish
- Forschungszentrum Jülich, Institut für Festkörperforschung, Postfach 1913, D-52425 Jülich, Germany; Martin-Luther-Universität Halle-Wittenberg, Fachbereich Physik, D-06099 Halle, Germany; Department of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, U.K.; Hahn-Meitner Institut, D-14091 Berlin, Germany; Department of Applied Maths and Theoretical Physics, Centre for Mathematical Sciences, Wilberforce Road, Cambridge, CB3 0WA, U.K.; and Department of Applied Mathematics, University of Leeds,
| | - A. Wiedenmann
- Forschungszentrum Jülich, Institut für Festkörperforschung, Postfach 1913, D-52425 Jülich, Germany; Martin-Luther-Universität Halle-Wittenberg, Fachbereich Physik, D-06099 Halle, Germany; Department of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, U.K.; Hahn-Meitner Institut, D-14091 Berlin, Germany; Department of Applied Maths and Theoretical Physics, Centre for Mathematical Sciences, Wilberforce Road, Cambridge, CB3 0WA, U.K.; and Department of Applied Mathematics, University of Leeds,
| | - R. J. Blackwell
- Forschungszentrum Jülich, Institut für Festkörperforschung, Postfach 1913, D-52425 Jülich, Germany; Martin-Luther-Universität Halle-Wittenberg, Fachbereich Physik, D-06099 Halle, Germany; Department of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, U.K.; Hahn-Meitner Institut, D-14091 Berlin, Germany; Department of Applied Maths and Theoretical Physics, Centre for Mathematical Sciences, Wilberforce Road, Cambridge, CB3 0WA, U.K.; and Department of Applied Mathematics, University of Leeds,
| | - D. J. Read
- Forschungszentrum Jülich, Institut für Festkörperforschung, Postfach 1913, D-52425 Jülich, Germany; Martin-Luther-Universität Halle-Wittenberg, Fachbereich Physik, D-06099 Halle, Germany; Department of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, U.K.; Hahn-Meitner Institut, D-14091 Berlin, Germany; Department of Applied Maths and Theoretical Physics, Centre for Mathematical Sciences, Wilberforce Road, Cambridge, CB3 0WA, U.K.; and Department of Applied Mathematics, University of Leeds,
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12
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Read DJ. Calculation of Scattering from Stretched Copolymers Using the Tube Model: Incorporation of the Effect of Elastic Inhomogeneities. Macromolecules 2004. [DOI: 10.1021/ma030438u] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- D. J. Read
- Department of Applied Mathematics, University of Leeds, Leeds LS2 9JT, United Kingdom
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13
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Bent J, Hutchings LR, Richards RW, Gough T, Spares R, Coates PD, Grillo I, Harlen OG, Read DJ, Graham RS, Likhtman AE, Groves DJ, Nicholson TM, McLeish TCB. Neutron-Mapping Polymer Flow: Scattering, Flow Visualization, and Molecular Theory. Science 2003; 301:1691-5. [PMID: 14500974 DOI: 10.1126/science.1086952] [Citation(s) in RCA: 148] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Flows of complex fluids need to be understood at both macroscopic and molecular scales, because it is the macroscopic response that controls the fluid behavior, but the molecular scale that ultimately gives rise to rheological and solid-state properties. Here the flow field of an entangled polymer melt through an extended contraction, typical of many polymer processes, is imaged optically and by small-angle neutron scattering. The dual-probe technique samples both the macroscopic stress field in the flow and the microscopic configuration of the polymer molecules at selected points. The results are compared with a recent "tube model" molecular theory of entangled melt flow that is able to calculate both the stress and the single-chain structure factor from first principles. The combined action of the three fundamental entangled processes of reptation, contour length fluctuation, and convective constraint release is essential to account quantitatively for the rich rheological behavior. The multiscale approach unearths a new feature: Orientation at the length scale of the entire chain decays considerably more slowly than at the smaller entanglement length.
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Affiliation(s)
- J Bent
- Department of Chemistry, Durham University, UK
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14
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Abstract
Progress towards understanding the extent to which mycorrhizal fungi are involved in the mobilization of nitrogen (N) and phosphorus (P) from natural substrates is reviewed here. While mycorrhiza research has emphasized the role of the symbiosis in facilitation of capture of these nutrients in ionic form, attention has shifted since the mid-1980s to analysing the mycorrhizal fungal abilities to release N and P from the detrital materials of microbial faunal and plant origins, which are the primary sources of these elements in terrestrial ecosystems. Ericoid, and some ectomycorrhizal fungi have the potential to be directly involved in attack both on structural polymers, which may render nutrients inaccessible, and in mobilization of N and P from the organic polymers in which they are sequestered. The advantages to the plant of achieving intervention in the microbial mobilization-immobilization cycles are stressed. While the new approaches may initially lack the precision achieved in studies of readily characterized ionic forms of N and P, they do provide insights of greater ecological relevance. The results support the hypothesis that selection has favoured ericoid and ectomycorrhizal systems with well developed saprotrophic capabilities in those ecosystems characterized by retention of N and P as organic complexes in the soil. The need for further investigation of the abilities of arbuscular mycorrhizal fungi to intervene in nutrient mobilization processes is stressed.
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Affiliation(s)
- D J Read
- Department of Animal & Plant Science, University of Sheffield, Sheffield, S10 2TN, UK
| | - J Perez-Moreno
- Colegio de Postgraduados, Microbiologia Edafologia-a-Irenat, Montecillo, Texcoco, CP 56320, Mexico
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15
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Heinrich M, Pyckhout-Hintzen W, Allgaier J, Richter D, Straube E, Read DJ, McLeish TCB, Groves DJ, Blackwell RJ, Wiedenmann A. Arm Relaxation in Deformed H-Polymers in Elongational Flow by SANS. Macromolecules 2002. [DOI: 10.1021/ma011923x] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | | | | | | | - E. Straube
- Martin-Luther-Universität Halle-Wittenberg, Fachbereich Physik, D-06099 Halle, Germany
| | - D. J. Read
- Department of Applied Mathematics, University of Leeds, Leeds, LS2 9JT, U.K
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16
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Read DJ, Teixeira PIC, Duckett RA, Sweeney J, McLeish TCB. Theoretical and finite-element investigation of the mechanical response of spinodal structures. Eur Phys J E Soft Matter 2002; 8:15-31. [PMID: 15010980 DOI: 10.1007/pl00022337] [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] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
In recent years there have been major advances in our understanding of the mechanisms of phase separation in polymer and copolymer blends, to the extent that good control of phase-separated morphology is a real possibility. Many groups are studying the computational simulation of polymer phase separation. In the light of this, we are exploring methods which will give insight into the mechanical response of multiphase polymers. We present preliminary results from a process which allows the production of a two-dimensional finite-element mesh from the contouring of simulated composition data. We examine the stretching of two-phase structures obtained from a simulation of linear Cahn-Hilliard spinodal phase separation. In the simulations, we assume one phase to be hard, and the other soft, such that the shear modulus ratio G is large (>or= 10(3)). We indicate the effect of varying composition on the material modulus and on the distribution of strains through the stretched material. We also examine in some detail the symmetric structures obtained at 50% composition, in which both phases are at a percolation threshold. Inspired by simulation results for the deformation of these structures, we construct a "scaling" theory, which reproduces the main features of the deformation. Of particular interest is the emergence of a lengthscale, below which the deformation is non-affine. This length is proportional to G(1/4), and hence is still quite small for all reasonable values of this ratio. The same theory predicts that the effective composite modulus scales also as G(1/4), , which is supported by the simulations.
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Affiliation(s)
- D J Read
- Department of Applied Mathematics, University of Leeds, Leeds, LS2 9JT, UK.
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17
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Abstract
• A novel in-growth core system, enabling functional studies of natural communities of arbuscular mycorrhizal (AM) mycelia in soil is described and tested. • The cores have windows covered with nylon mesh of 35 µm pore size that prevent in-growth of roots but permit penetration of AM hyphae. They were inserted into grassland turf and contained either sterilized sand and a 'bait' seedling of Trifolium repens or nonsterile natural soil without bait plants. The impacts of hyphal severance, achieved by periodic rotation of some of the cores, upon AM colonization of bait plants (experiment 1) and transfer of 33 P from soil to plants outside the cores (experiment 2) were examined. • Severance of AM hyphae reduced both AM colonization of bait plants and their shoot P concentrations. The shoot 33 P concentrations of plants with mycelial access to 33 PO4 -labelled cores were 10-fold greater than those which had no mycelial access. • It is concluded that this novel approach enables the functioning of mycorrhizal mycelial networks to be evaluated under conditions closely simulating those occurring in nature.
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Affiliation(s)
- D Johnson
- Department of Animal and Plant Science, University of Sheffield, Sheffield S10 2TN, UK
| | - J R Leake
- Department of Animal and Plant Science, University of Sheffield, Sheffield S10 2TN, UK
| | - D J Read
- Department of Animal and Plant Science, University of Sheffield, Sheffield S10 2TN, UK
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18
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Affiliation(s)
- E. J. Wallace
- Department of Physics & Astronomy and Polymer IRC, University of Leeds, Leeds LS2 9JT, U.K.; and Department of Applied Mathematics, University of Leeds, Leeds LS2 9JT, U.K
| | - D. M. A. Buzza
- Department of Physics & Astronomy and Polymer IRC, University of Leeds, Leeds LS2 9JT, U.K.; and Department of Applied Mathematics, University of Leeds, Leeds LS2 9JT, U.K
| | - D. J. Read
- Department of Physics & Astronomy and Polymer IRC, University of Leeds, Leeds LS2 9JT, U.K.; and Department of Applied Mathematics, University of Leeds, Leeds LS2 9JT, U.K
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19
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Emmerton KS, Callaghan TV, Jones HE, Leake JR, Michelsen A, Read DJ. Assimilation and isotopic fractionation of nitrogen by mycorrhizal fungi. New Phytologist 2001. [PMID: 0 DOI: 10.1046/j.1469-8137.2001.00178.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Affiliation(s)
- K. S. Emmerton
- Department of Animal and Plant Sciences, The University of Sheffield, Sheffield S10 2TN, UK
| | - T. V. Callaghan
- Abisko Scientific Research Station, Royal Swedish Academy of Sciences, S‐981 07, Abisko, Sweden
- Sheffield Centre for Arctic Ecology, The University of Sheffield, Sheffield S10 2TN, UK
| | - H. E. Jones
- Institute of Terrestrial Ecology, Merlewood Research Station, Grange‐over‐Sands, Cumbria LA11 6JU, UK
| | - J. R. Leake
- Department of Animal and Plant Sciences, The University of Sheffield, Sheffield S10 2TN, UK
| | - A. Michelsen
- Department of Plant Ecology, University of Copenhagen, Øster Farimagsgade 2 D, DK‐1353 Copenhagen K, Denmark
| | - D. J. Read
- Department of Animal and Plant Sciences, The University of Sheffield, Sheffield S10 2TN, UK
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20
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Perez-Moreno J, Read DJ. Exploitation of pollen by mycorrhizal mycelial systems with special reference to nutrient recycling in boreal forests. Proc Biol Sci 2001; 268:1329-35. [PMID: 11429131 PMCID: PMC1088745 DOI: 10.1098/rspb.2001.1681] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.3] [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: 11/12/2022] Open
Abstract
Very large quantities of pollen are released annually by wind-pollinated trees, which dominate northern forest ecosystems. Since pollen is enriched in both nitrogen and phosphorus, this recurrent pulse of deposition constitutes a significant potential source of these elements in what are known to be severely nutrient-limited systems. Here, we demonstrate for the first time, to our knowledge, that an ectomycorrhizal fungus, Paxillus involutus, is able to scavenge effectively for nitrogen and phosphorus in pollen and to return a significant proportion of each nutrient to its autotrophic host, Betula pendula. More than 75 and 96%, respectively, of the nitrogen and phosphorus were removed from pollen in microcosms containing the mycorrhizal fungus, 29 and 25%, respectively, being transferred to the plants. In contrast, in microcosms without the mycorrhizal fungus only 42 and 35%, respectively, of nitrogen and phosphorus were lost from the pollen, presumably as a result of export by saprotrophs, and only 12 and 7%, respectively, were transferred to the plants. We hypothesize that this process of resource recapture, by contributing significantly to the ability of the trees to sustain the necessary annual investment in pollen production, will have a major impact upon their reproductive capabilities and hence 'fitness'.
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Affiliation(s)
- J Perez-Moreno
- Microbiologia, Edafologia-IRENAT, Colegio de Postgraduados, Montecillo, Edo. de Mexico, CP 56230, Mexico
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Högberg P, Nordgren A, Buchmann N, Taylor AF, Ekblad A, Högberg MN, Nyberg G, Ottosson-Löfvenius M, Read DJ. Large-scale forest girdling shows that current photosynthesis drives soil respiration. Nature 2001; 411:789-92. [PMID: 11459055 DOI: 10.1038/35081058] [Citation(s) in RCA: 540] [Impact Index Per Article: 23.5] [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: 11/08/2022]
Abstract
The respiratory activities of plant roots, of their mycorrhizal fungi and of the free-living microbial heterotrophs (decomposers) in soils are significant components of the global carbon balance, but their relative contributions remain uncertain. To separate mycorrhizal root respiration from heterotrophic respiration in aboreal pine forest, we conducted a large-scale tree-girdling experiment, comprising 9 plots each containing about 120 trees. Tree-girdling involves stripping the stem bark to the depth of the current xylem at breast height terminating the supply of current photosynthates to roots and their mycorrhizal fungi without physically disturbing the delicate root-microbe-soil system. Here we report that girdling reduced soil respiration within 1-2 months by about 54% relative to respiration on ungirdled control plots, and that decreases of up to 37% were detected within 5 days. These values clearly show that the flux of current assimilates to roots is a key driver of soil respiration; they are conservative estimates of root respiration, however, because girdling increased the use of starch reserves in the roots. Our results indicate that models of soil respiration should incorporate measures of photosynthesis and of seasonal patterns of photosynthate allocation to roots.
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Affiliation(s)
- P Högberg
- Department of Forest Ecology, SLU, Umeå, Sweden.
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22
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Affiliation(s)
- D. J. Read
- Department of Applied Mathematics, University of Leeds, Leeds, LS2 9JT, U.K.; and IRC in Polymer Science and Technology, Department of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, U.K
| | - T. C. B. McLeish
- Department of Applied Mathematics, University of Leeds, Leeds, LS2 9JT, U.K.; and IRC in Polymer Science and Technology, Department of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, U.K
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23
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Leake JR, Donnelly DP, Saunders EM, Boddy L, Read DJ. Rates and quantities of carbon flux to ectomycorrhizal mycelium following 14C pulse labeling of Pinus sylvestris seedlings: effects of litter patches and interaction with a wood-decomposer fungus. Tree Physiol 2001; 21:71-82. [PMID: 11303651 DOI: 10.1093/treephys/21.2-3.71] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
We used a novel digital autoradiographic technique that enabled, for the first time, simultaneous visualization and quantification of spatial and temporal changes in carbon allocation patterns in ectomycorrhizal mycelia. Mycorrhizal plants of Pinus sylvestris L. were grown in microcosms containing non-sterile peat. The time course and spatial distribution of carbon allocation by P. sylvestris to mycelia of its mycorrhizal partners, Paxillus involutus (Batsch) Fr. and Suillus bovinus (L.): Kuntze, were quantified following 14C pulse labeling of the plants. Litter patches were used to investigate the effects of nutrient resource quality on carbon allocation. The wood-decomposer fungus Phanerochaete velutina (D.C.: Pers.) Parmasto was introduced to evaluate competitive and territorial interactions between its mycelial cords and the mycelial system of S. bovinus. Growth of ectomycorrhizal mycelium was stimulated in the litter patches. Nearly 60% of the C transferred from host plant to external mycorrhizal mycelium (> 2 mm from root surfaces) was allocated to mycelium in the patches, which comprised only 12% of the soil area available for mycelial colonization. Mycelia in the litter patch most recently colonized by mycorrhizal mycelium received the largest investment of carbon, amounting to 27 to 50% of the total 14C in external mycorrhizal mycelium. The amount of C transfer to external mycelium of S. bovinus following pulse labeling was reduced from a maximum of 167 nmol in systems with no saprotroph to a maximum of 61 nmol in systems interacting with P. velutina. The 14C content of S. bovinus mycelium reached a maximum 24-36 h after labeling in control microcosms, but allocation did not reach a peak until 56 h after labeling, when S. bovinus interacted with mycelium of P. velutina. The mycelium of S. bovinus contained 9% of the total 14C in the plants (including mycorrhizae) at the end of the experiment, but this was reduced to 4% in the presence of P. velutina. The results demonstrate the dynamic manner in which mycorrhizal mycelia deploy C when foraging for nutrients. The inhibitory effect of the wood-decomposer fungus P. velutina on C allocation to external mycorrhizal mycelium has important implications for nutrient cycling in forest ecosystems.
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Affiliation(s)
- J R Leake
- Department of Animal and Plant Sciences, University of Sheffield, UK
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24
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Edwards D, Duckett JG, Read DJ. Preface. Philos Trans R Soc Lond B Biol Sci 2000. [DOI: 10.1098/rstb.2000.0611] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- D. Edwards
- Department of Earth Sciences, Cardiff University, PO Box 914, Cardiff CF10 3YE, UK
| | - J. G. Duckett
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK
| | - D. J. Read
- School of Biological Sciences, Queen Mary & Westfield College, Mile End Road, London E1 4NS, UK
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Read DJ, Ducket JG, Francis R, Ligron R, Russell A. Symbiotic fungal associations in 'lower' land plants. Philos Trans R Soc Lond B Biol Sci 2000; 355:815-30; discussion 830-1. [PMID: 10905611 PMCID: PMC1692782 DOI: 10.1098/rstb.2000.0617] [Citation(s) in RCA: 129] [Impact Index Per Article: 5.4] [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: 11/12/2022] Open
Abstract
An analysis of the current state of knowledge of symbiotic fungal associations in 'lower' plants is provided. Three fungal phyla, the Zygomycota, Ascomycota and Basidiomycota, are involved in forming these associations, each producing a distinctive suite of structural features in well-defined groups of 'lower' plants. Among the 'lower' plants only mosses and Equisetum appear to lack one or other of these types of association. The salient features of the symbioses produced by each fungal group are described and the relationships between these associations and those formed by the same or related fungi in 'higher' plants are discussed. Particular consideration is given to the question of the extent to which root fungus associations in 'lower' plants are analogous to 'mycorrhizas' of 'higher' plants and the need for analysis of the functional attributes of these symbioses is stressed. Zygomycetous fungi colonize a wide range of extant lower land plants (hornworts, many hepatics, lycopods, Ophioglossales, Psilotales and Gleicheniaceae), where they often produce structures analogous to those seen in the vesicular-arbuscular (VA) mycorrhizas of higher plants, which are formed by members of the order Glomales. A preponderance of associations of this kind is in accordance with palaeohbotanical and molecular evidence indicating that glomalean fungi produced the archetypal symbioses with the first plants to emerge on to land. It is shown, probably for the first time, that glomalean fungi forming typical VA mycorrhiza with a higher plant (Plantago lanceolata) can colonize a thalloid liverwort (Pellia epiphylla), producing arbuscules and vesicles in the hepatic. The extent to which these associations, which are structurally analogous to mycorrhizas, have similar functions remains to be evaluated. Ascomycetous associations are found in a relatively small number of families of leafy liverworts. The structural features of the fungal colonization of rhizoids and underground axes of these plants are similar to those seen in mycorrhizal associations of ericaceous plants like Vaccinium. Cross inoculation experiments have confirmed that a typical mycorrhizal endophyte of ericaceous plants, Hymenoscyphus ericae, will form associations in liverworts which are structurally identical to those seen in nature. Again, the functional significance of these associations remains to be examined. Some members of the Jungermanniales and Metzgeriales form associations with basidiomycetous fungi. These produce intracellular coils of hyphae, which are similar to the pelotons seen in orchid mycorrhizas, which also involve basidiomycetes. The fungal associates of the autotrophic Aneura and of its heterotrophic relative Cryptothallus mirabilis have been isolated. In the latter case it has been shown that the fungal symbiont is an ectomycorrhizal associate of Betula, suggesting that the apparently obligate nature of the association between the hepatic and Betula in nature is based upon requirement for this particular heterotroph.
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Affiliation(s)
- D J Read
- Department of Animal and Plant Sciences, Uiniverity of Sheffield, UK
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Affiliation(s)
- P. I. C. Teixeira
- IRC in Polymer Science and Technology, Department of Physics, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - D. J. Read
- IRC in Polymer Science and Technology, Department of Physics, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - T. C. B. McLeish
- IRC in Polymer Science and Technology, Department of Physics, University of Leeds, Leeds LS2 9JT, United Kingdom
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McKENDRICK SL, Leake JR, Taylor DL, Read DJ. Symbiotic germination and development of myco-heterotrophic plants in nature: ontogeny of Corallorhiza trifida and characterization of its mycorrhizal fungi. New Phytol 2000; 145:523-537. [PMID: 33862904 DOI: 10.1046/j.1469-8137.2000.00603.x] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The processes of symbiotic germination and seedling development were analysed in the myco-heterotrophic orchid Corallorhiza trifida, seeds of which were buried in 'packets' either adjacent to or at varying distances from adult plants in defined communities of ectomycorrhizal tree species. Germination occurred within eight months of burial under Betula-Alnus and within seven months under Salix repens. It was always associated with penetration of the suspensor by a clamp-forming mycorrhizal fungus. Four distinct developmental stages were defined and the rates of transition through these stages were plotted. There was no evidence of a relationship between extent of germination or rate of development and the presence of naturally distributed plants of C. trifida at the spatial scale of 1 m. The best germination and the most rapid rate of development of C. trifida seedlings occurred in a Salix repens community located at a considerable distance from any extant C. trifida population. Determination of internal transcribed spacer (ITS) RFLPs and of gene sequences of the fungi involved in symbiotic germination and growth of C. trifida, revealed them to belong exclusively to the Thelephora-Tomentella complex of the Thelephoraceae. These fungi are known also to be ectomycorrhizal associates of trees. It is hypothesized that the rate of growth of the C. trifida seedlings is determined by the ability of the fungal symbionts to transfer carbon from their ectomycorrhizal co-associates.
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Affiliation(s)
- S L McKENDRICK
- 1 Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK
| | - J R Leake
- 1 Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK
| | - D L Taylor
- 1 Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK
| | - D J Read
- 1 Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK
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McKENDRICK SL, Leake JR, Read DJ. Symbiotic germination and development of myco-heterotrophic plants in nature: transfer of carbon from ectomycorrhizal Salix repens and Betula pendula to the orchid Corallorhiza trifida through shared hyphal connections. New Phytol 2000; 145:539-548. [PMID: 33862911 DOI: 10.1046/j.1469-8137.2000.00592.x] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Seedlings of the myco-heterotrophic orchid Corallorhiza trifida which had been germinated in the field in mesh bags developed hyphal links and mycorrhizas with Betula pendula and Salix repens, but not with Pinus sylvestris, when transplanted into soil microcosms. The fungus connecting the myco-heterotroph to Betula and Salix formed endomycorrhiza in the orchid with typical pelotons, but formed ectomycorrhizas with the autotrophs. The orchid plants, when linked to Betula and Salix by fungal hyphae, gained 6-14% in weight over 25-28 wk. In microcosms supporting P. sylvestris, and in control microcosms which lacked autotrophs, the Corallorhiza plants lost 13% of their weight over the same period. In the course of the 28-wk experimental period new Corallorhiza seedlings, in addition to those added as part of the experiment, appeared in the microcosms containing Salix and Betula but not in the Pinus microcosms. Shoots of Betula and Salix plants grown in association with Corallorhiza were fed with 14 CO2 , and the movement of the isotope was subsequently traced by a combination of digital autoradiography and tissue oxidation. Direct transfer of C from both autotrophs to the myco-heterotroph occurred in all cases where the associates had become connected by a shared fungal symbiont. Orchid seedlings lacking these hyphal connections, introduced to the microcosms as controls immediately before isotope feeding, failed to assimilate significant amounts of C. The results provide the first experimental confirmation that growth of Corallorhiza trifida can be sustained by supply of C received directly from an autotrophic partner through linked fungal mycelia.
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Affiliation(s)
- S L McKENDRICK
- 1 Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK
| | - J R Leake
- 1 Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK
| | - D J Read
- 1 Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK
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Wallenda T, Stober C, Högbom L, Schinkel H, George E, Högberg P, Read DJ. Nitrogen Uptake Processes in Roots and Mycorrhizas. Ecological Studies 2000. [DOI: 10.1007/978-3-642-57219-7_6] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
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Hector A, Schmid B, Beierkuhnlein C, Caldeira MC, Diemer M, Dimitrakopoulos PG, Finn JA, Freitas H, Giller PS, Good J, Harris R, Hogberg P, Huss-Danell K, Joshi J, Jumpponen A, Korner C, Leadley PW, Loreau M, Minns A, Mulder CP, O'Donovan G, Otway SJ, Pereira JS, Prinz A, Read DJ, Scherer-Lorenzen M, Schulze ED, Siamantziouras ASD, Spehn EM, Terry AC, Troumbis AY, Woodward FI, Yachi S, Lawton JH. Plant diversity and productivity experiments in european grasslands. Science 1999; 286:1123-7. [PMID: 10550043 DOI: 10.1126/science.286.5442.1123] [Citation(s) in RCA: 801] [Impact Index Per Article: 32.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
At eight European field sites, the impact of loss of plant diversity on primary productivity was simulated by synthesizing grassland communities with different numbers of plant species. Results differed in detail at each location, but there was an overall log-linear reduction of average aboveground biomass with loss of species. For a given number of species, communities with fewer functional groups were less productive. These diversity effects occurred along with differences associated with species composition and geographic location. Niche complementarity and positive species interactions appear to play a role in generating diversity-productivity relationships within sites in addition to sampling from the species pool.
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Affiliation(s)
- A Hector
- Natural Environmental Research Council (NERC) Centre for Population Biology, Imperial College at Silwood Park, Ascot, Berkshire, UK, GB-SL5 7PY. Institut fur Umweltwissenschaften, Universitat Zurich, Winterthurerstrasse 190, Zurich, Switzerland
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McLeish TCB, Allgaier J, Bick DK, Bishko G, Biswas P, Blackwell R, Blottière B, Clarke N, Gibbs B, Groves DJ, Hakiki A, Heenan RK, Johnson JM, Kant R, Read DJ, Young RN. Dynamics of Entangled H-Polymers: Theory, Rheology, and Neutron-Scattering. Macromolecules 1999. [DOI: 10.1021/ma990323j] [Citation(s) in RCA: 234] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- T. C. B. McLeish
- IRC in Polymer Science and Technology, Department of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, U.K.; Department of Chemistry, University of Sheffield, Sheffield, S2 2UN, U.K.; Institut für Festkörperforschung, FZ Jülich GmbH, 52425, Jülich, Germany; ISIS, Rutherford-Appleton Laboratory, Chilton, Oxon, OX11 0QX U.K.; and Department of Physics, University of Sheffield, Sheffield, S2 2UN, U.K
| | - J. Allgaier
- IRC in Polymer Science and Technology, Department of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, U.K.; Department of Chemistry, University of Sheffield, Sheffield, S2 2UN, U.K.; Institut für Festkörperforschung, FZ Jülich GmbH, 52425, Jülich, Germany; ISIS, Rutherford-Appleton Laboratory, Chilton, Oxon, OX11 0QX U.K.; and Department of Physics, University of Sheffield, Sheffield, S2 2UN, U.K
| | - D. K. Bick
- IRC in Polymer Science and Technology, Department of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, U.K.; Department of Chemistry, University of Sheffield, Sheffield, S2 2UN, U.K.; Institut für Festkörperforschung, FZ Jülich GmbH, 52425, Jülich, Germany; ISIS, Rutherford-Appleton Laboratory, Chilton, Oxon, OX11 0QX U.K.; and Department of Physics, University of Sheffield, Sheffield, S2 2UN, U.K
| | - G. Bishko
- IRC in Polymer Science and Technology, Department of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, U.K.; Department of Chemistry, University of Sheffield, Sheffield, S2 2UN, U.K.; Institut für Festkörperforschung, FZ Jülich GmbH, 52425, Jülich, Germany; ISIS, Rutherford-Appleton Laboratory, Chilton, Oxon, OX11 0QX U.K.; and Department of Physics, University of Sheffield, Sheffield, S2 2UN, U.K
| | - P. Biswas
- IRC in Polymer Science and Technology, Department of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, U.K.; Department of Chemistry, University of Sheffield, Sheffield, S2 2UN, U.K.; Institut für Festkörperforschung, FZ Jülich GmbH, 52425, Jülich, Germany; ISIS, Rutherford-Appleton Laboratory, Chilton, Oxon, OX11 0QX U.K.; and Department of Physics, University of Sheffield, Sheffield, S2 2UN, U.K
| | - R. Blackwell
- IRC in Polymer Science and Technology, Department of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, U.K.; Department of Chemistry, University of Sheffield, Sheffield, S2 2UN, U.K.; Institut für Festkörperforschung, FZ Jülich GmbH, 52425, Jülich, Germany; ISIS, Rutherford-Appleton Laboratory, Chilton, Oxon, OX11 0QX U.K.; and Department of Physics, University of Sheffield, Sheffield, S2 2UN, U.K
| | - B. Blottière
- IRC in Polymer Science and Technology, Department of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, U.K.; Department of Chemistry, University of Sheffield, Sheffield, S2 2UN, U.K.; Institut für Festkörperforschung, FZ Jülich GmbH, 52425, Jülich, Germany; ISIS, Rutherford-Appleton Laboratory, Chilton, Oxon, OX11 0QX U.K.; and Department of Physics, University of Sheffield, Sheffield, S2 2UN, U.K
| | - N. Clarke
- IRC in Polymer Science and Technology, Department of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, U.K.; Department of Chemistry, University of Sheffield, Sheffield, S2 2UN, U.K.; Institut für Festkörperforschung, FZ Jülich GmbH, 52425, Jülich, Germany; ISIS, Rutherford-Appleton Laboratory, Chilton, Oxon, OX11 0QX U.K.; and Department of Physics, University of Sheffield, Sheffield, S2 2UN, U.K
| | - B. Gibbs
- IRC in Polymer Science and Technology, Department of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, U.K.; Department of Chemistry, University of Sheffield, Sheffield, S2 2UN, U.K.; Institut für Festkörperforschung, FZ Jülich GmbH, 52425, Jülich, Germany; ISIS, Rutherford-Appleton Laboratory, Chilton, Oxon, OX11 0QX U.K.; and Department of Physics, University of Sheffield, Sheffield, S2 2UN, U.K
| | - D. J. Groves
- IRC in Polymer Science and Technology, Department of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, U.K.; Department of Chemistry, University of Sheffield, Sheffield, S2 2UN, U.K.; Institut für Festkörperforschung, FZ Jülich GmbH, 52425, Jülich, Germany; ISIS, Rutherford-Appleton Laboratory, Chilton, Oxon, OX11 0QX U.K.; and Department of Physics, University of Sheffield, Sheffield, S2 2UN, U.K
| | - A. Hakiki
- IRC in Polymer Science and Technology, Department of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, U.K.; Department of Chemistry, University of Sheffield, Sheffield, S2 2UN, U.K.; Institut für Festkörperforschung, FZ Jülich GmbH, 52425, Jülich, Germany; ISIS, Rutherford-Appleton Laboratory, Chilton, Oxon, OX11 0QX U.K.; and Department of Physics, University of Sheffield, Sheffield, S2 2UN, U.K
| | - R. K. Heenan
- IRC in Polymer Science and Technology, Department of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, U.K.; Department of Chemistry, University of Sheffield, Sheffield, S2 2UN, U.K.; Institut für Festkörperforschung, FZ Jülich GmbH, 52425, Jülich, Germany; ISIS, Rutherford-Appleton Laboratory, Chilton, Oxon, OX11 0QX U.K.; and Department of Physics, University of Sheffield, Sheffield, S2 2UN, U.K
| | - J. M. Johnson
- IRC in Polymer Science and Technology, Department of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, U.K.; Department of Chemistry, University of Sheffield, Sheffield, S2 2UN, U.K.; Institut für Festkörperforschung, FZ Jülich GmbH, 52425, Jülich, Germany; ISIS, Rutherford-Appleton Laboratory, Chilton, Oxon, OX11 0QX U.K.; and Department of Physics, University of Sheffield, Sheffield, S2 2UN, U.K
| | - R. Kant
- IRC in Polymer Science and Technology, Department of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, U.K.; Department of Chemistry, University of Sheffield, Sheffield, S2 2UN, U.K.; Institut für Festkörperforschung, FZ Jülich GmbH, 52425, Jülich, Germany; ISIS, Rutherford-Appleton Laboratory, Chilton, Oxon, OX11 0QX U.K.; and Department of Physics, University of Sheffield, Sheffield, S2 2UN, U.K
| | - D. J. Read
- IRC in Polymer Science and Technology, Department of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, U.K.; Department of Chemistry, University of Sheffield, Sheffield, S2 2UN, U.K.; Institut für Festkörperforschung, FZ Jülich GmbH, 52425, Jülich, Germany; ISIS, Rutherford-Appleton Laboratory, Chilton, Oxon, OX11 0QX U.K.; and Department of Physics, University of Sheffield, Sheffield, S2 2UN, U.K
| | - R. N. Young
- IRC in Polymer Science and Technology, Department of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, U.K.; Department of Chemistry, University of Sheffield, Sheffield, S2 2UN, U.K.; Institut für Festkörperforschung, FZ Jülich GmbH, 52425, Jülich, Germany; ISIS, Rutherford-Appleton Laboratory, Chilton, Oxon, OX11 0QX U.K.; and Department of Physics, University of Sheffield, Sheffield, S2 2UN, U.K
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Abstract
Covalent modification of NTE, a neuronal protein with serine esterase activity, by certain organophosphates (OP) initiates degeneration of long axons in the peripheral and central nervous system. Simple inhibition of NTE esterase activity does not initiate neuropathy; the latter requires aging of the OP bound to the catalytic serine residue so that a negatively-charged species is left attached to the active site. This may indicate that a non-esterase function of NTE is important for axonal maintenance. We have recently cloned NTE and shown that it is unrelated to any known serine hydrolases but contains a novel C-terminal domain which is conserved from bacteria to man. Furthermore, the catalytic serine is located within this domain at the centre of a helical hydrophobic segment of the polypeptide's secondary structure. The integrity of NTE would be severely compromised by the presence of a negatively-charged organophosphate moiety at this site. Implications for possible higher-order structures and functions for NTE are discussed.
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Affiliation(s)
- P Glynn
- MRC Toxicology Unit, University of Leicester, UK.
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Lush MJ, Li Y, Read DJ, Willis AC, Glynn P. Neuropathy target esterase and a homologous Drosophila neurodegeneration-associated mutant protein contain a novel domain conserved from bacteria to man. Biochem J 1998; 332 ( Pt 1):1-4. [PMID: 9576844 PMCID: PMC1219444 DOI: 10.1042/bj3320001] [Citation(s) in RCA: 119] [Impact Index Per Article: 4.6] [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: 02/07/2023]
Abstract
The N-terminal amino acid sequences of proteolytic fragments of neuropathy target esterase (NTE), covalently labelled on its active-site serine by a biotinylated organophosphorus ester, were determined and used to deduce the location of this serine residue and to initiate cloning of its cDNA. A putative NTE clone, isolated from a human foetal brain cDNA library, encoded a 1327 residue polypeptide with no homology to any known serine esterases or proteases. The active-site serine of NTE (Ser-966) lay in the centre of a predicted hydrophobic helix within a 200-amino-acid C-terminal domain with marked similarity to conceptual proteins in bacteria, yeast and nematodes; these proteins may comprise a novel family of potential serine hydrolases. The Swiss Cheese protein which, when mutated, leads to widespread cell death in Drosophila brain [Kretzschmar, Hasan, Sharma, Heisenberg and Benzer (1997) J. Neurosci. 17, 7425-7432], was strikingly homologous to NTE, suggesting that genetically altered NTE may be involved in human neurodegenerative disease.
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Affiliation(s)
- M J Lush
- MRC Toxicology Unit, University of Leicester, Leicester LE1 9HN, UK
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Glynn P, Holton JL, Nolan CC, Read DJ, Brown L, Hubbard A, Cavanagh JB. Neuropathy target esterase: immunolocalization to neuronal cell bodies and axons. Neuroscience 1998; 83:295-302. [PMID: 9466418 DOI: 10.1016/s0306-4522(97)00388-6] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.7] [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: 02/06/2023]
Abstract
Determination of the molecular mechanisms involved in organophosphate-induced axonopathy may help to elucidate those involved in normal axonal maintenance and in other neurodegenerative conditions. In this study we aimed to define the cellular distribution of neuropathy target esterase, the primary target protein for neuropathic organophosphates. A synthetic peptide corresponding to the sequence of a proteolytic fragment of neuropathy target esterase purified from chicken brain was used to raise a rabbit antiserum designated R28. The antiserum was shown by immunoprecipitation and western blotting of brain extracts to react with a polypeptide of the expected molecular size (155,000 mol. wt); this reaction was blocked by preincubating the antiserum with the immunizing peptide. Prominent intracellular immunostaining by R28 was seen in neuronal cell bodies and, in some cases, proximal axon segments in frozen sections of chicken brain cortex, optic tectum, cerebellum, spinal cord, and dorsal root ganglia. Cells with glial morphology were not immunostained, neither were normal sciatic nerve or motor end plates. However, 8-12 h following sciatic nerve ligation, immunoreactive material was seen to accumulate both proximal and, to a lesser extent, distal to the ligature, indicating that neuropathy target esterase undergoes fast axonal transport. No gross qualitative or quantitative changes in the above pattern of neuropathy target esterase immunoreactivity were detected in tissue obtained from chickens one or three days following treatment with a neuropathic organophosphate. The presence of neuropathy target esterase in essentially all neurons indicates that the selective vulnerability of long axons to neuropathic organophosphates is dependent on factors additional to the presence of the target protein.
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Affiliation(s)
- P Glynn
- Medical Research Council Toxicology Unit, University of Leicester, UK
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35
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Read DJ. Mean Field Theory for Phase Separation during Polycondensation Reactions and Calculation of Structure Factors for Copolymers of Arbitrary Architecture. Macromolecules 1998. [DOI: 10.1021/ma970953q] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- D. J. Read
- IRC in Polymer Science, Department of Physics, University of Leeds, Leeds LS2 9JT, U.K
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36
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Affiliation(s)
- D. J. Read
- Department of Physics, University of Leeds, IRC in Polymer Science & Technology, Department of Physics, University of Leeds, Leeds, LS2 9JT, U.K
| | - T. C. B. McLeish
- Department of Physics, University of Leeds, IRC in Polymer Science & Technology, Department of Physics, University of Leeds, Leeds, LS2 9JT, U.K
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37
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Francis R, Read DJ. Mutualism and antagonism in the mycorrhizal symbiosis, with special reference to impacts on plant community structure. ACTA ACUST UNITED AC 1995. [DOI: 10.1139/b95-391] [Citation(s) in RCA: 172] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Examination of the roots of land plants has revealed the occurrence of mycorrhiza in the majority of species, over 70% of which are hosts to zygomycetous fungi that form vesicular–arbuscular (VA) associations. On the basis of experiments with a small number of host species showing enhancement of growth following colonization, it is widely assumed that wherever mycorrhizas are observed, the symbiosis is of the mutualistic type. The value of definitions based on structural rather than functional attributes is here brought into question by experiments simulating the ecologically realistic circumstance in which seeds germinate in soil in the presence or absence of established VA mycelium. These reveal a spectrum of fungal impacts in which some species respond mutualistically, while others, putative hosts or nonhosts, are antagonised, showing reduction of yield and survivorship and, hence, a loss of fitness relative to plants grown without VA fungi. Antagonised species normally grow in disturbed, open habitats and fail to establish in closed communities. It is hypothesised that their turf incompatibility arises from a sensitivity to interference by VA fungi, which consigns them to ruderal habitats. Mycorrhizal fungi, thus, play a role in defining the ecological niches occupied by plants and in determining of plant community composition. Key words: mycorrhiza, vesicular–arbuscular, mutualism, symbiosis, antagonism, plant community.
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Glynn P, Read DJ, Guo R, Wylie S, Johnson MK. Synthesis and characterization of a biotinylated organophosphorus ester for detection and affinity purification of a brain serine esterase: neuropathy target esterase. Biochem J 1994; 301 ( Pt 2):551-6. [PMID: 8043002 PMCID: PMC1137116 DOI: 10.1042/bj3010551] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.5] [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: 01/28/2023]
Abstract
We have synthesized a novel stable precursor, saligenin phosphorotrichloridate, which, on reaction with N-monobiotinyldiamines, generates a series of biotinylated covalent inhibitors of serine esterases. A homologue designated S9B [1-(saligenin cyclic phospho)-9-biotinyldiaminononane] was selected to allow detection and rapid isolation of neuropathy target esterase (NTE). This enzyme is the primary target site for those organophosphorus esters (OPs) which cause delayed neuropathy. NTE comprises about 0.03% of the total protein in brain microsomal fractions and has resisted purification attempts over many years. S9B is a potent progressive inhibitor of NTE esteratic activity (second-order rate constant 1.4 x 10(7) M-1.min-1). Incubation of S9B with brain microsomes led to specific covalent labelling of NTE as determined by detection of a biotinylated 155 kDa polypeptide on Western blots. Specificity of S9B labelling was further demonstrated by inhibition with the neuropathic OP mipafox. Biotinyl-NTE in SDS-solubilized S9B-labelled microsomes was adsorbed on to avidin-Sepharose and subsequently eluted, yielding a fraction enriched approx. 1000-fold in NTE by a single step with recoveries of 30%. Essentially pure NTE was obtained after separation from two endogenous biotinylated polypeptides (120 and 70 kDa) in avidin-Sepharose eluates by preparative SDS/PAGE. Other biotinylated saligenin phosphoramidates derived from the same precursor may be useful for detection and isolation of other serine esterases and proteinases.
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Affiliation(s)
- P Glynn
- MRC Toxicology Unit, Carshalton, Surrey, U.K
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40
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Cooke JC, Read DJ, Lewis DH, Fitter AH, Alexander IJ. Mycorrhizas in Ecosystems. Mycologia 1994. [DOI: 10.2307/3760658] [Citation(s) in RCA: 0] [Impact Index Per Article: 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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Abstract
Resolved isomers of O-n-hexyl-S-methylphosphorothioamidate (HXM) which had been synthesised by separate stereospecific routes were analysed by chiral glc: about 2-3% of R-(+) isomer was found in the S-(-) sample and accounted for nearly all the inhibitory power against neuropathy target esterase. Incubation of racemic HXM with rabbit serum led to slow but very specific disposal of R-(+) isomer to undetectable levels with very slight loss of S-(-): the rate of disposal was roughly estimated to be about 1% of the published rate of hydrolysis of paraoxon. Incubation with crystalline chymotrypsin caused a preferential but not totally selective disposal of S-(-) isomer.
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Affiliation(s)
- M K Johnson
- MRC Toxicology Unit, University of Leicester, UK
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Abstract
Phenyl di-n-pentylphosphinate (PPP) is a potent inhibitor of neuropathy target esterase (NTE) with negligible effect on acetylcholinesterase: I50S at 37 degrees C for 20 min and pH 8, respectively are 0.2 microM and > 2mM. PPP is not neuropathic. This is compatible with the fact that inhibited NTE is autopsy material from hens dosed with PPP can always be reactivated in vitro, presumably because no 'aging' reaction has occurred. PPP (10 mg/kg s.c.) given to hens up to 4 days before severely neuropathic doses (1.7 mg/kg) of diisopropylphosphorofluoridate (DFP) prevented neuropathic but not cholinergic effects of DFP. Hens given PPP 3 days after a sub-neuropathic dose of DFP (0.4 mg/kg) developed severe clinical neuropathy (clinical scores of 7 and 5 compared with DFP-plus-solvent scores 0,1,3). These prophylactic and promoting effects are similar to those exerted by phenylmethanesulphonyl fluoride (PMSF) at doses which inhibit NTE. In 3 out of 4 birds a pre-dose with PMSF (15 mg/kg) prevented the promoting effect of 120 mg/kg PMSF given after DFP.
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Affiliation(s)
- M K Johnson
- MRC Toxicology Unit, University of Leicester, UK
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Johnson MK, Read DJ. Screening of O-ethyl O-4-nitrophenyl phosphoramidate (ENPP) for delayed neuropathic potential. Chem Biol Interact 1993; 87:439-42. [PMID: 8344000 DOI: 10.1016/0009-2797(93)90072-7] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
O-Ethyl-O-4-nitrophenylphosphoramidate is a short-acting anticholinesterase and a possible candidate for a prophylactic agent against nerve agents since human acetylcholinesterase inhibited by this agent undergoes rapid spontaneous reactivation which can be accelerated further, if necessary, by treatment with oximes. Doses of the agent > 1 mg/kg (s.c.) given to unprotected rats were fatal in a short time but 2 rats and one hen given 0.5 mg/kg survived. Hens given 2.5 or 4 mg/kg s.c. 20 min after prophylactic physostigmine + atropine survived acute effects and were killed 4.5 or 24 h later. Brain and spinal cord neuropathy target esterase levels of these hens were depressed only 4-10% compared with levels in brains from hens given only oxime + atropine or of undosed animals. Clinical signs of neuropathy were not seen in surviving birds observed for 3 weeks. It appears there would be negligible delayed neuropathic hazard associated with administration of O-ethyl-O-4-nitrophenylphosphoramidate at subacute doses.
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Affiliation(s)
- M K Johnson
- MRC Toxicology Unit, University of Leicester, UK
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44
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Miller SL, Norris JR, Read DJ, Varma AK. Techniques for the Study of Mycorrhiza, Methods in Microbiology, Vol. 23. Mycologia 1993. [DOI: 10.2307/3760493] [Citation(s) in RCA: 0] [Impact Index Per Article: 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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Rüffer-Turner ME, Read DJ, Johnson MK. Purification of neuropathy target esterase from avian brain after prelabelling with [3H]diisopropyl phosphorofluoridate. J Neurochem 1992; 58:135-41. [PMID: 1727426 DOI: 10.1111/j.1471-4159.1992.tb09288.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [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: 12/28/2022]
Abstract
Neuropathy target esterase from hen brains was radiolabelled at the active site with [3H]diisopropyl phosphorofluoridate. The labelled protein was purified by differential centrifugation and Nonidet P40 solubilization, detergent phase partitioning, anion exchange, and preparative sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). The volatilizable counts assay and analytical SDS-PAGE were used to monitor the protein. The 150-kDa subunit polypeptide appears as a single band on analytical SDS-PAGE.
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Affiliation(s)
- M E Rüffer-Turner
- MRC Toxicology Unit, Medical Research Council Laboratories, Surrey, England, U.K
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46
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Johnson MK, Vilanova E, Read DJ. Anomalous biochemical responses in tests of the delayed neuropathic potential of methamidophos (O,S-dimethyl phosphorothioamidate), its resolved isomers and of some higher O-alkyl homologues. Arch Toxicol 1991; 65:618-24. [PMID: 1660708 DOI: 10.1007/bf02098026] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.4] [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: 12/28/2022]
Abstract
The interaction with neural neuropathy target esterase (NTE) and acetylcholinesterase (AChE) in vivo of methamidophos (O,S-dimethyl phosphorothioamidate), its resolved stereoisomers and five higher O-alkyl homologues has been examined along with the ability of these compounds to cause organophosphorus-induced delayed polyneuropathy (OPIDP) in adult hens. For the lower homologues AChE was more sensitive than NTE and it was impossible to achieve high inhibition of NTE in vivo without both prophylaxis and therapy against acute anticholinesterase effects; for the n-hexyl homologue high inhibition of NTE could be achieved without obvious anticholinesterase effects and spontaneous reactivation of inhibited AChE was seen as in vitro. The maximum tolerated dose of L(-) methamidophos or of the ethyl or iso-propyl homologues did not inhibit NTE more than 60%, and surviving birds did not develop OPIDP. The n-propyl, n-butyl and n-hexyl compounds caused typical OPIDP at doses causing a peak of 70-95% inhibition of NTE in brain, spinal cord and sciatic nerve soon after dosing. Racemic methamidophos caused unusually mild OPIDP associated with very high inhibition of NTE at doses estimated to be greater than 8 times the unprotected LD50 and the D-(+) isomer caused OPIDP at about 5-7 x LD50. Clinical effects correlated with histopathology in 19 out of 20 examined birds. In contrast to results of many previous studies with organophosphates and phosphonates, all these cases of OPIDP were associated with formation of inhibited NTE which could be reactivated ex vivo by treatment of autopsy tissue with KF solution.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- M K Johnson
- MRC Toxicology Unit, Medical Research Council Laboratories, Carshalton, Surrey, UK
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Abstract
Conifer–feather moss ecosystems dominate large areas of the boreal forest regions of the world, but the interrelations between these two components of the system are poorly understood. Mycorrhizal roots of the trees grow in close association with the mosses. The possibility that nutrients can be transferred from moss shoots to trees through mycorrhizal fungi was investigated using the feather moss Pleurozium schreberi and mycorrhizal seedlings of Pinus contorta. Shoots of the moss were divided into three categories, viz. green, senescent, and dead, and nutrient contents of aqueous leachates from the segments were measured before and after drying. Significant quantities of nitrogen and phosphorus were released from moss shoots especially after drying. Senescing segments consistently released more N than those that were dead and generally released more than did the green segments. All categories of segments released some protein nitrogen, and drying induced leakage of glucose, fructose, and sucrose. Leachates of entire moss shoots were capable of supporting growth of three mycorrhizal fungi in pure culture. Moss shoots added to chambers containing mycorrhizal plants were colonized by the fungal associates of the plants, particularly intensive growth occurring in the senescent region of the moss shoots. Phosphate (32P) and carbon (14C), previously fed to the moss shoots, was absorbed by mycorrhizal mycelia and transferred over distances of centimetres to infected roots of pine plants and then to their shoots. The significance of these uptake and transfer processes for nutrient cycling in boreal forest ecosystems is discussed. Key words: leachate, nitrogen, phosphorus, sugars, protein, radioisotope.
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Shaw G, Leake JR, Baker AJM, Read DJ. The biology of mycorrhiza in the Ericaceae: XVII. The role of mycorrhizal infection in the regulation of iron uptake by ericaceous plants. New Phytol 1990; 115:251-258. [PMID: 33873945 DOI: 10.1111/j.1469-8137.1990.tb00450.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The role of the ericoid mycorrhizal endophyte Hymenoscyphus ericae (Read) Korf & Kernan in the regulation of iron uptake by ericaceous plants is investigated. Growth of the fungus is not inhibited in solution cultures containing a range (0-144 [ig ml-1 ) of iron concentration ([Fe]ext ) typical of those obtained in extracts from heathland soil. Absorption of iron by the fungus occurs rapidly at low [Fe]ext but more slowly as [Fe]ext increases. Concentrations of iron in the mycelium ([Fe]mye ), reach 6000μg g-1 dry weight. Mycorrhizal (M) roots of Vaccinium macrocarpon Ait. and Calluna vulgaris L. (Hull) showed a very high affinity for iron at low [Fe]ext , a feature not shown by non-mycorrhizal (NM) roots. The involvement of a hydroxamate siderophore in the absorption of Fe by M plants at low [Fe]ext is suggested. Concentrations of iron in shoots ([Fe]ext of NM plants of V. macrocarpon increase linearly with increasing [Fe]ext while those of M plants fall in the mid-range of [Fe]ext relative to initial and final values. Ratios of [Fe]ext to [Fe]ext are lower in M than in NM plants across the range of [Fe]ext examined. The extent of involvement of mycorrhizal infection in excluding the metal from shoots as [Fe]ext increases, is discussed, and the importance of the mechanisms of iron capture and storage in the root are assessed in terms of iron availability in natural heathlands.
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Affiliation(s)
- G Shaw
- Department of Animal and Plant Sciences, The University of Sheffield, Sheffield S10 2TN, UK
| | - J R Leake
- Department of Animal and Plant Sciences, The University of Sheffield, Sheffield S10 2TN, UK
| | - A J M Baker
- Department of Animal and Plant Sciences, The University of Sheffield, Sheffield S10 2TN, UK
| | - D J Read
- Department of Animal and Plant Sciences, The University of Sheffield, Sheffield S10 2TN, UK
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Leake JR, Read DJ. Proteinase activity in mycorrhizal fungi: I. The effect of extracellular pH on the production and activity of proteinase by ericoid endophytes from soils of contrasted pH. New Phytol 1990; 115:243-250. [PMID: 33873961 DOI: 10.1111/j.1469-8137.1990.tb00449.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The effect of pH on the production and specific activity of the extracellular proteinase enzymes of two ecologically distinct ericoid mycorrhizal fungi is described. The proteinase of Hymenoscyphus ericae (Read), Korf & Kernan, isolated from roots of Calluna vulgaris (L.) Hull growing in soil of pH 35, was compared with a similar enzyme from an endophyte of the calcicolous alpine shrub Rhodothamnus chamaecistus (L.) Reichenb. growing in soil of pH 6.5. The fungi were grown in liquid culture at pH values ranging from 3.0 to 8.0 with pure protein, bovine serum albumin, as sole source of N. Both fungi yielded an extracellular acid proteinase with pH optimum for activity between 20 and 30. The production and activity of these enzymes was strongly affected by pH of the culture medium. Maximum enzyme production during exponential growth occurred in both fungi at a culture pH of 4.0-5.0, whereas higher pH treatments severely inhibited enzyme production. The acid proteinase of H. ericae was tolerant of extreme acidity and retained near-optimal activity in solutions of pH 2.0. In contrast, the activity of the enzyme from the Rhodothamnus endophyte was almost completely inhibited at this pH. However, proteinase from the Rhodothamnus endophyte retained activity at much higher pH values than did the proteinase from H. ericae. Unlike H. ericae, the isolated endophyte of Rhodothamnus was able to grow and use protein as sole source of N at pH 7.0 and 8.0. The effects of pH on enzyme production and upon growth of the fungi are discussed in relation to the characteristics of the environments of their host plants.
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Affiliation(s)
- J R Leake
- Department of Animal and Plant Sciences, The University of Sheffield, Sheffield, S10 2TN, U.K
| | - D J Read
- Department of Animal and Plant Sciences, The University of Sheffield, Sheffield, S10 2TN, U.K
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Johnson MK, Vilanova E, Read DJ. Biochemical and clinical tests of the delayed neuropathic potential of some O-alkyl O-dichlorophenyl phosphoramidate analogues of methamidophos (O,S-dimethyl phosphorothioamidate). Toxicology 1989; 54:89-100. [PMID: 2536970 DOI: 10.1016/0300-483x(89)90081-4] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.9] [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: 01/01/2023]
Abstract
The interaction in vivo of four O-alkyl O-2,5-dichlorophenyl phosphoramidates with neural neuropathy target esterase (NTE) and acetylcholinesterase (AChE) and their ability to cause delayed polyneuropathy in hens has been examined. Previous studies in vitro (Vilanova, Johnson & Vicedo, Pestic. Biochem. Physiol., 28 (1987) 224) had led to the prediction that these compounds would not be neuropathic but, rather, would be prophylactic agents against organophosphorus-induced delayed polyneuropathy. In vivo the effects of these esters on the enzymes differ in 2 respects from effects in vitro: (i) Relative sensitivity of the enzymes was different: thus greater than 50% of brain NTE remained 24 h after an oral dose of 15 mg/kg of the n-hexyl ester while only 10-30% of AChE remained although NTE was the more sensitive enzyme in vitro; (ii) In no case could the inhibited NTE or AChE in autopsy samples from birds dosed with any of the 4 esters be reactivated by treatment with potassium fluoride in vitro: the inhibited enzymes produced by incubation of tissue with the esters in vitro had been reactivatable. Prophylaxis, with therapy in some cases, was required to prevent acute anticholinesterase poisoning when doses were sufficient to cause high inhibition of neural NTE. Inhibition in brain was typically 5-10% more than in spinal cord and 10-15% more than in sciatic nerve. Unambiguous signs of polyneuropathy (Grade 3 or more on an 8-point scale) were not seen in birds observed up to 3 weeks after doses which caused less than 70% inhibition of NTE in brain and spinal cord or less than 60% inhibition in sciatic nerve of pair-dosed birds assayed 24 h after dosing. Doses of 300, 10, 100 and 65 mg/kg, respectively, of the methyl, ethyl, n-butyl and n-hexyl esters caused greater than 70% inhibition of NTE in all 3 neural tissues and neuropathy in the majority of observed birds. Analysis of consolidated dose/response data from 36 assayed and 51 observed birds showed that effects of Grade 3 or more were produced in about 90% of birds when inhibition of NTE was greater than 90% in brain, greater than 85% in spinal cord or greater than 75% in sciatic nerve.(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- M K Johnson
- MRC Toxicology Unit, Medical Research Council Laboratories, Carshalton, Surrey, U.K
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