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Hawkins HJ, Cargill RIM, Van Nuland ME, Hagen SC, Field KJ, Sheldrake M, Soudzilovskaia NA, Kiers ET. Mycorrhizal mycelium as a global carbon pool. Curr Biol 2023; 33:R560-R573. [PMID: 37279689 DOI: 10.1016/j.cub.2023.02.027] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
For more than 400 million years, mycorrhizal fungi and plants have formed partnerships that are crucial to the emergence and functioning of global ecosystems. The importance of these symbiotic fungi for plant nutrition is well established. However, the role of mycorrhizal fungi in transporting carbon into soil systems on a global scale remains under-explored. This is surprising given that ∼75% of terrestrial carbon is stored belowground and mycorrhizal fungi are stationed at a key entry point of carbon into soil food webs. Here, we analyze nearly 200 datasets to provide the first global quantitative estimates of carbon allocation from plants to the mycelium of mycorrhizal fungi. We estimate that global plant communities allocate 3.93 Gt CO2e per year to arbuscular mycorrhizal fungi, 9.07 Gt CO2e per year to ectomycorrhizal fungi, and 0.12 Gt CO2e per year to ericoid mycorrhizal fungi. Based on this estimate, 13.12 Gt of CO2e fixed by terrestrial plants is, at least temporarily, allocated to the underground mycelium of mycorrhizal fungi per year, equating to ∼36% of current annual CO2 emissions from fossil fuels. We explore the mechanisms by which mycorrhizal fungi affect soil carbon pools and identify approaches to increase our understanding of global carbon fluxes via plant-fungal pathways. Our estimates, although based on the best available evidence, are imperfect and should be interpreted with caution. Nonetheless, our estimations are conservative, and we argue that this work confirms the significant contribution made by mycorrhizal associations to global carbon dynamics. Our findings should motivate their inclusion both within global climate and carbon cycling models, and within conservation policy and practice.
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Affiliation(s)
- Heidi-Jayne Hawkins
- Department of Biological Sciences, University of Cape Town, Cape Town 7701, South Africa; Conservation International, Forrest House, Belmont Park, Cape Town 7700, South Africa.
| | - Rachael I M Cargill
- Amsterdam Institute for Life and Environment, Vrije Universiteit, De Boelelaan 1085, NL-1081 HV Amsterdam, The Netherlands; AMOLF, Science Park 102, Amsterdam, The Netherlands
| | - Michael E Van Nuland
- Amsterdam Institute for Life and Environment, Vrije Universiteit, De Boelelaan 1085, NL-1081 HV Amsterdam, The Netherlands; Society for the Protection of Underground Networks, SPUN, 3500 South DuPont Highway, Dover, DE 19901, USA
| | | | - Katie J Field
- Plants, Photosynthesis and Soil, School of Biosciences, The University of Sheffield, Western Bank, Sheffield S10 2TN, UK
| | - Merlin Sheldrake
- Amsterdam Institute for Life and Environment, Vrije Universiteit, De Boelelaan 1085, NL-1081 HV Amsterdam, The Netherlands; Society for the Protection of Underground Networks, SPUN, 3500 South DuPont Highway, Dover, DE 19901, USA
| | | | - E Toby Kiers
- Amsterdam Institute for Life and Environment, Vrije Universiteit, De Boelelaan 1085, NL-1081 HV Amsterdam, The Netherlands; Society for the Protection of Underground Networks, SPUN, 3500 South DuPont Highway, Dover, DE 19901, USA
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Chen L, Rejesus RM, Aglasan S, Hagen SC, Salas W. The impact of cover crops on soil erosion in the US Midwest. J Environ Manage 2022; 324:116168. [PMID: 36174470 DOI: 10.1016/j.jenvman.2022.116168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Revised: 08/28/2022] [Accepted: 08/31/2022] [Indexed: 06/16/2023]
Abstract
This study examines the impact of cover crop adoption on soil erosion levels in the United States (US) Midwest. Based on a novel county-level panel data set with information on soil erosion levels and remotely-sensed cover crop acreage, we estimate linear panel fixed effect econometric models and conduct a number of robustness checks to investigate the direct impact of cover crops on two major types of soil erosion (wind and water erosion). Although we find that counties with higher cover crop acreage have statistically lower soil erosion levels due to water, wind, or both, we believe that the magnitudes of the estimated effects are modest. Longer-term multi-year use of cover crops also do not seem to increase the soil erosion reducing effects of cover crops over time. Results from the empirical analysis provide further empirical evidence on the impact of cover crops on soil erosion based on data that captures farmer behavior at the county-level and covers a wider geographical region in the US. Our findings also give insights to policy makers in terms of further understanding the magnitude of the soil erosion benefits from cover crops.
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Affiliation(s)
- Le Chen
- North Carolina State University, Raleigh, NC, USA
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Harris NL, Hagen SC, Saatchi SS, Pearson TRH, Woodall CW, Domke GM, Braswell BH, Walters BF, Brown S, Salas W, Fore A, Yu Y. Attribution of net carbon change by disturbance type across forest lands of the conterminous United States. Carbon Balance Manag 2016. [PMID: 27909460 DOI: 10.1186/s13021-0160068-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
BACKGROUND Locating terrestrial sources and sinks of carbon (C) will be critical to developing strategies that contribute to the climate change mitigation goals of the Paris Agreement. Here we present spatially resolved estimates of net C change across United States (US) forest lands between 2006 and 2010 and attribute them to natural and anthropogenic processes. RESULTS Forests in the conterminous US sequestered -460 ± 48 Tg C year-1, while C losses from disturbance averaged 191 ± 10 Tg C year-1. Combining estimates of net C losses and gains results in net carbon change of -269 ± 49 Tg C year-1. New forests gained -8 ± 1 Tg C year-1, while deforestation resulted in losses of 6 ± 1 Tg C year-1. Forest land remaining forest land lost 185 ± 10 Tg C year-1 to various disturbances; these losses were compensated by net carbon gains of -452 ± 48 Tg C year-1. C loss in the southern US was highest (105 ± 6 Tg C year-1) with the highest fractional contributions from harvest (92%) and wind (5%). C loss in the western US (44 ± 3 Tg C year-1) was due predominantly to harvest (66%), fire (15%), and insect damage (13%). The northern US had the lowest C loss (41 ± 2 Tg C year-1) with the most significant proportional contributions from harvest (86%), insect damage (9%), and conversion (3%). Taken together, these disturbances reduced the estimated potential C sink of US forests by 42%. CONCLUSION The framework presented here allows for the integration of ground and space observations to more fully inform US forest C policy and monitoring efforts.
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Affiliation(s)
- N L Harris
- Ecosystem Services Unit, Winrock International, 2121 Crystal Drive Suite 500, Arlington, VA 22202 USA
- Forests Program, World Resources Institute, 10 G Street NE Suite 800, Washington, DC 20002 USA
| | - S C Hagen
- Applied Geosolutions, 55 Main Street Suite 125, Newmarket, NH 03857 USA
| | - S S Saatchi
- NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 USA
| | - T R H Pearson
- Ecosystem Services Unit, Winrock International, 2121 Crystal Drive Suite 500, Arlington, VA 22202 USA
| | - C W Woodall
- USDA Forest Service, Northern Research Station, Saint Paul, MN 55108 USA
| | - G M Domke
- USDA Forest Service, Northern Research Station, Saint Paul, MN 55108 USA
| | - B H Braswell
- Applied Geosolutions, 55 Main Street Suite 125, Newmarket, NH 03857 USA
| | - B F Walters
- USDA Forest Service, Northern Research Station, Saint Paul, MN 55108 USA
| | - S Brown
- Ecosystem Services Unit, Winrock International, 2121 Crystal Drive Suite 500, Arlington, VA 22202 USA
| | - W Salas
- Applied Geosolutions, 55 Main Street Suite 125, Newmarket, NH 03857 USA
| | - A Fore
- NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 USA
| | - Y Yu
- NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 USA
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Lacy P, Mahmudi-Azer S, Bablitz B, Hagen SC, Velazquez JR, Man SF, Moqbel R. Rapid mobilization of intracellularly stored RANTES in response to interferon-gamma in human eosinophils. Blood 1999; 94:23-32. [PMID: 10381494] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/13/2023] Open
Abstract
The CC chemokine RANTES is synthesized, stored, and upregulated in response to interferon-gamma (IFN-gamma) in human peripheral blood eosinophils. In this report, we propose that RANTES is rapidly mobilized from eosinophil crystalloid granules during agonist-induced degranulation. We stimulated purified eosinophils (>99%) from atopic asthmatics with 500 U/mL IFN-gamma to analyze the kinetics of mobilization and release of RANTES (0 to 240 minutes). We used subcellular fractionation, immunogold analysis, two-color confocal laser scanning microscopy (CLSM), and enzyme-linked immunosorbent assay (ELISA) to trace the movement of eosinophil-derived RANTES from intracellular stores to release. RANTES was rapidly mobilized (10 minutes) and released after 120 minutes of stimulation (80 +/- 15 pg/mL per 2 x 10(6) cells). RANTES appeared to be stored in at least two intracellular compartments: the matrix of crystalloid granules, detected by major basic protein and eosinophil peroxidase activities, and a specialized small secretory vesicle present in light membrane fractions. The extragranular RANTES was mobilized more rapidly than that of crystalloid granules during IFN-gamma stimulation. This effect was not observed in eosinophils treated with IFN-alpha, interleukin-3 (IL-3), IL-5, granulocyte-macrophage colony-stimulating factor (GM-CSF), or genistein followed by IFN-gamma. Our findings suggest that RANTES may be mobilized and released by piecemeal degranulation upon stimulation, involving transport through a putative pool of small secretory vesicles.
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Affiliation(s)
- P Lacy
- Pulmonary Research Group, Department of Medicine, University of Alberta, Edmonton, Alberta, Canada
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Lacy P, Levi-Schaffer F, Mahmudi-Azer S, Bablitz B, Hagen SC, Velazquez J, Kay AB, Moqbel R. Intracellular localization of interleukin-6 in eosinophils from atopic asthmatics and effects of interferon gamma. Blood 1998; 91:2508-16. [PMID: 9516152] [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] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Eosinophils, prominent cells in asthmatic inflammation, have been shown to synthesize, store, and release an array of up to 18 cytokines and growth factors, including interleukin-6 (IL-6). In this report, we show that IL-6 immunofluorescence localizes to the matrix of the crystalloid granule in peripheral blood eosinophils from atopic asthmatics using confocal laser scanning microscopy (CLSM). Granule localization of IL-6 was confirmed using dot-blot analysis and enzyme-linked immunosorbent assay (ELISA) on subcellular fractions of highly purified eosinophils produced from density centrifugation across a 0% to 45% Nycodenz gradient. IL-6 was found to coelute with eosinophil crystalloid granule marker proteins, including eosinophil peroxidase (EPO), major basic protein (MBP), arylsulfatase B, and beta-hexosaminidase. Immunoreactivity to IL-6 colocalized with granule-associated IL-2 and IL-5 in subfractionated eosinophils. We also made the novel and compelling observation that interferon gamma (IFNgamma), a Th1-type cytokine, stimulated an early elevation in eosinophil IL-6 immunoreactivity. A 2.5-fold enhancement of IL-6 immunoreactivity in eosinophil granules was observed within 10 minutes of IFNgamma treatment (500 U/mL), as determined by subcellular fractionation and CLSM. These findings suggest that IFNgamma has short-term effects on human eosinophil function and imply that a physiologic role exists for Th1-type cytokine modulation of Th2-type responses in these cells.
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Affiliation(s)
- P Lacy
- Pulmonary Research Group, Department of Medicine, University of Alberta, Edmonton, Alberta, Canada
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Abstract
The gene Wh, causing anophthalmia in the Syrian hamster, Mesocricetus auratus, is a pleiotropic gene affecting eye development, pigmentation, hearing, and reproduction. Male hamsters homozygous for this gene are usually sterile. Since both Wh and the pineal organ are known to suppress reproductive function, the objective of this study was twofold: (1) to determine whether Wh, by itself, influences testicular differentiation; and (2) to determine whether removal of the pineal gland will restore fertility to both experimentally blinded (B), genetically normal [wh/wh(B)] hamsters and mutant, eyeless (Wh/Wh) hamsters. Accordingly, one testis from each of ten wh/wh(B) and ten Wh/Wh hamsters at approximately 60 days of age was removed, and these testes were compared at the gross and light microscopic level. Since all testes were identical at 60 days of age and contained normal differentiating germ cells, the gene Wh does not appear to affect initial testicular differentiation. Testicular tissues from at least ten wh/wh, wh/wh(B), heterozygous (Wh/wh), and Wh/Wh hamsters, at 135 days of age, were also compared. Testes from all wh/wh(B), and 70% of the Wh/Wh hamsters were hypoplasic and aspermic. Approximately 30% of the testes from Wh/Wh hamsters contained some seminiferous tubules with normal sperm present. Pinealectomy fully restored adult testicular size and morphology in all wh/wh(B) and Wh/Wh hamsters. Thus, it was demonstrated that the atrophy of testes from Wh/Wh individuals is a pineal-mediated phenomenon due to failure of eye development and the subsequent lack of a functional visual pathway. Testes from Wh/Wh hamsters appear to be completely competent to respond to the normal, antigonadotrophic effects of the pineal.
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