1
|
Wu Y, Li H, Cui J, Han Y, Li H, Miao B, Tang Y, Li Z, Zhang J, Wang L, Liang C. Precipitation variation: a key factor regulating plant diversity in semi-arid livestock grazing lands. Front Plant Sci 2024; 15:1294895. [PMID: 38645388 PMCID: PMC11027165 DOI: 10.3389/fpls.2024.1294895] [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] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/15/2023] [Accepted: 02/06/2024] [Indexed: 04/23/2024]
Abstract
Livestock presence impacts plant biodiversity (species richness) in grassland ecosystems, yet extent and direction of grazing impacts on biodiversity vary greatly across inter-annual periods. In this study, an 8-year (2014-2021) grazing gradient experiment with sheep was conducted in a semi-arid grassland to investigate the impact of grazing under different precipitation variability on biodiversity. The results suggest no direct impact of grazing on species richness in semi-arid Stipa grassland. However, increased grazing indirectly enhanced species richness by elevating community dominance (increasing the sheltering effect of Stipa grass). Importantly, intensified grazing also regulates excessive community biomass resulting from increased inter-annual wetness (SPEI), amplifying the positive influence of annual humidity index on species richness. Lastly, we emphasize that, in water-constrained grassland ecosystems, intra-annual precipitation variability (PCI) was the most crucial factor driving species richness. Therefore, the water-heat synchrony during the growing season may alleviate physiological constraints on plants, significantly enhancing species richness as a result of multifactorial interactions. Our study provides strong evidence for how to regulate grazing intensity to increase biodiversity under future variable climate patterns. We suggest adapting grazing intensity according to local climate variability to achieve grassland biodiversity conservation.
Collapse
Affiliation(s)
- Yantao Wu
- College of Life Sciences, Inner Mongolia University, Hohhot, China
- Key Laboratory of Ecology and Resource Use of the Mongolian Plateau, Ministry of Education of China, Collaborative Innovation Center for Grassland Ecological Security, School of Ecology and Environment, Inner Mongolia University, Hohhot, Inner Mongolia, China
| | - Hao Li
- Key Laboratory of Ecology and Resource Use of the Mongolian Plateau, Ministry of Education of China, Collaborative Innovation Center for Grassland Ecological Security, School of Ecology and Environment, Inner Mongolia University, Hohhot, Inner Mongolia, China
| | - Jiahe Cui
- Key Laboratory of Ecology and Resource Use of the Mongolian Plateau, Ministry of Education of China, Collaborative Innovation Center for Grassland Ecological Security, School of Ecology and Environment, Inner Mongolia University, Hohhot, Inner Mongolia, China
- College of Resources Environment and Tourism, Capital Normal University, Beijing, China
| | - Ying Han
- Key Laboratory of Ecology and Resource Use of the Mongolian Plateau, Ministry of Education of China, Collaborative Innovation Center for Grassland Ecological Security, School of Ecology and Environment, Inner Mongolia University, Hohhot, Inner Mongolia, China
| | - Hangyu Li
- Key Laboratory of Ecology and Resource Use of the Mongolian Plateau, Ministry of Education of China, Collaborative Innovation Center for Grassland Ecological Security, School of Ecology and Environment, Inner Mongolia University, Hohhot, Inner Mongolia, China
| | - Bailing Miao
- Inner Mongolia Meteorological Institute, Hohhot, China
| | | | - Zhiyong Li
- Key Laboratory of Ecology and Resource Use of the Mongolian Plateau, Ministry of Education of China, Collaborative Innovation Center for Grassland Ecological Security, School of Ecology and Environment, Inner Mongolia University, Hohhot, Inner Mongolia, China
| | - Jinghui Zhang
- Key Laboratory of Ecology and Resource Use of the Mongolian Plateau, Ministry of Education of China, Collaborative Innovation Center for Grassland Ecological Security, School of Ecology and Environment, Inner Mongolia University, Hohhot, Inner Mongolia, China
| | - Lixin Wang
- Key Laboratory of Ecology and Resource Use of the Mongolian Plateau, Ministry of Education of China, Collaborative Innovation Center for Grassland Ecological Security, School of Ecology and Environment, Inner Mongolia University, Hohhot, Inner Mongolia, China
| | - Cunzhu Liang
- Key Laboratory of Ecology and Resource Use of the Mongolian Plateau, Ministry of Education of China, Collaborative Innovation Center for Grassland Ecological Security, School of Ecology and Environment, Inner Mongolia University, Hohhot, Inner Mongolia, China
| |
Collapse
|
2
|
Wang Y, Wang S, Zhao L, Liang C, Miao B, Zhang Q, Niu X, Ma W, Schmid B. Stability and asynchrony of local communities but less so diversity increase regional stability of Inner Mongolian grassland. eLife 2022; 11:74881. [PMID: 36206306 PMCID: PMC9545536 DOI: 10.7554/elife.74881] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Accepted: 08/26/2022] [Indexed: 01/10/2023] Open
Abstract
Extending knowledge on ecosystem stability to larger spatial scales is urgently needed because present local-scale studies are generally ineffective in guiding management and conservation decisions of an entire region with diverse plant communities. We investigated stability of plant productivity across spatial scales and hierarchical levels of organization and analyzed impacts of dominant species, species diversity, and climatic factors using a multisite survey of Inner Mongolian grassland. We found that regional stability across distant local communities was related to stability and asynchrony of local communities. Using only dominant instead of all-species dynamics explained regional stability almost equally well. The diversity of all or only dominant species had comparatively weak effects on stability and synchrony, whereas a lower mean and higher variation of precipitation destabilized regional and local communities by reducing population stability and synchronizing species dynamics. We demonstrate that, for semi-arid temperate grassland with highly uneven species abundances, the stability of regional communities is increased by stability and asynchrony of local communities and these are more affected by climate rather than species diversity. Reduced amounts and increased variation of precipitation in the future may compromise the sustainable provision of ecosystem services to human well-being in this region.
Collapse
Affiliation(s)
- Yonghui Wang
- Ministry of Education Key Laboratory of Ecology and Resource Use of the Mongolian Plateau & Inner Mongolia Key Laboratory of Grassland Ecology, School of Ecology and Environment, Inner Mongolia University
| | - Shaopeng Wang
- Institute of Ecology, College of Urban and Environmental Sciences, and Key Laboratory for Earth Surface Processes of the Ministry of Education, Peking University
| | - Liqing Zhao
- Ministry of Education Key Laboratory of Ecology and Resource Use of the Mongolian Plateau & Inner Mongolia Key Laboratory of Grassland Ecology, School of Ecology and Environment, Inner Mongolia University
| | - Cunzhu Liang
- Ministry of Education Key Laboratory of Ecology and Resource Use of the Mongolian Plateau & Inner Mongolia Key Laboratory of Grassland Ecology, School of Ecology and Environment, Inner Mongolia University
| | - Bailing Miao
- Ministry of Education Key Laboratory of Ecology and Resource Use of the Mongolian Plateau & Inner Mongolia Key Laboratory of Grassland Ecology, School of Ecology and Environment, Inner Mongolia University
| | - Qing Zhang
- Ministry of Education Key Laboratory of Ecology and Resource Use of the Mongolian Plateau & Inner Mongolia Key Laboratory of Grassland Ecology, School of Ecology and Environment, Inner Mongolia University
| | - Xiaxia Niu
- Ministry of Education Key Laboratory of Ecology and Resource Use of the Mongolian Plateau & Inner Mongolia Key Laboratory of Grassland Ecology, School of Ecology and Environment, Inner Mongolia University
| | - Wenhong Ma
- Ministry of Education Key Laboratory of Ecology and Resource Use of the Mongolian Plateau & Inner Mongolia Key Laboratory of Grassland Ecology, School of Ecology and Environment, Inner Mongolia University
| | - Bernhard Schmid
- Department of Geography, Remote Sensing Laboratories, University of Zürich
| |
Collapse
|
3
|
Dong L, Zheng Y, Wang J, Li J, Li Z, Zhang J, Wang L, Miao B, Liang C. Intra- and interannual dynamics of grassland community phylogenetic structure are influenced by meteorological conditions before the growing season. Front Plant Sci 2022; 13:870526. [PMID: 36212278 PMCID: PMC9541524 DOI: 10.3389/fpls.2022.870526] [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] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Accepted: 09/05/2022] [Indexed: 06/16/2023]
Abstract
The impact of global climate change on ecosystem structure has attracted much attention from researchers. However, how climate change and meteorological conditions influence community phylogenetic structure remains poorly understood. In this research, we quantified the responses of grassland communities' phylogenetic structure to long- and short-term meteorological conditions in Inner Mongolia, China. The net relatedness index (NRI) was used to characterize phylogenetic structure, and the relationship between the NRI and climate data was analyzed to understand the dynamics of community phylogenetic structure and its relationship with extreme meteorological events. Furthermore, multiple linear regression and structural equation models (SEMs) were used to quantify the relative contributions of meteorological factors before and during the current growing season to short-term changes in community phylogenetic structure. In addition, we evaluated the effect of long-term meteorological factors on yearly NRI anomalies with classification and regression trees (CARTs). We found that 1) the degree of phylogenetic clustering of the community is relatively low in the peak growing season, when habitat filtering is relatively weak and competition is fiercer. 2) Extreme meteorological conditions (i.e., drought and cold) may change community phylogenetic structure and indirectly reduce the degree of phylogenetic clustering by reducing the proportion of dominant perennial grasses. 3) Meteorological conditions before the growing season rather than during the current growing season explain more variation in the NRI and interannual NRI anomalies. Our results may provide useful information for understanding grassland community species assembly and how climate change affects biodiversity.
Collapse
Affiliation(s)
- Lei Dong
- Yinshanbeilu Grassland Eco-hydrology National Observation and Research Station, China Institute of Water Resources and Hydropower Research, Beijing, China
- Institute of Water Resources for Pastoral Areas, Ministry of Water Resources, Hohhot, China
| | - Ying Zheng
- Yinshanbeilu Grassland Eco-hydrology National Observation and Research Station, China Institute of Water Resources and Hydropower Research, Beijing, China
- Institute of Water Resources for Pastoral Areas, Ministry of Water Resources, Hohhot, China
| | - Jian Wang
- Yinshanbeilu Grassland Eco-hydrology National Observation and Research Station, China Institute of Water Resources and Hydropower Research, Beijing, China
- Institute of Water Resources for Pastoral Areas, Ministry of Water Resources, Hohhot, China
| | - Jinrong Li
- Yinshanbeilu Grassland Eco-hydrology National Observation and Research Station, China Institute of Water Resources and Hydropower Research, Beijing, China
- Institute of Water Resources for Pastoral Areas, Ministry of Water Resources, Hohhot, China
| | - Zhiyong Li
- School of Ecology and Environment, Inner Mongolia University, Hohhot, China
| | - Jinghui Zhang
- School of Ecology and Environment, Inner Mongolia University, Hohhot, China
| | - Lixin Wang
- School of Ecology and Environment, Inner Mongolia University, Hohhot, China
| | - Bailing Miao
- Meteorological Research Institute of Inner Mongolia, Inner Mongolia Meteorological Service, Hohhot, China
| | - Cunzhu Liang
- School of Ecology and Environment, Inner Mongolia University, Hohhot, China
| |
Collapse
|
4
|
Wu Y, Guo Z, Li Z, Liang M, Tang Y, Zhang J, Miao B, Wang L, Liang C. The main driver of soil organic carbon differs greatly between topsoil and subsoil in a grazing steppe. Ecol Evol 2022; 12:e9182. [PMID: 35949532 PMCID: PMC9353232 DOI: 10.1002/ece3.9182] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Revised: 07/08/2022] [Accepted: 07/14/2022] [Indexed: 11/10/2022] Open
Abstract
Soil organic carbon (SOC) dynamics is regulated by a complex interplay of factors such as climate and potential anthropogenic activities. Livestocks play a key role in regulating the C cycle in grasslands. However, the interrelationship between SOC and these drivers remains unclear at different soil layers, and their potential relationships network have rarely been quantitatively assessed. Here, we completed a six‐year manipulation experiment of grazing exclusion (no grazing: NG) and increasing grazing intensity (light grazing: LG, medium grazing: MG, heavy grazing: HG). We tested light fraction organic carbon (LFOC) and heavy fraction organic carbon (HFOC) in 12 plots along grazing intensity in three soil layers (topsoil: 0–10 cm, mid‐soil: 10–30 cm, subsoil: 30–50 cm) to assess the drivers of SOC. Grazing significantly reduced SOC of the soil profile, but with significant depth and time dependencies. (1) SOC and SOC stability of the topsoil is primarily regulated by grazing duration (years). Specifically, grazing duration and grazing intensity increased the SOC lability of topsoil due to an increase in LFOC. (2) Grazing intensity was the major factor affecting the mid‐soil SOC dynamics, among which MG had significantly lower SOC than did NG. (3) Subsoil organic carbon dynamics were mainly regulated by climatic factors. The increase in mean annual temperature (MAT) may have promoted the turnover of LFOC to HFOC in the subsoil. Synthesis and applications. When evaluating the impacts of grazing on soil organic fraction, we need to consider the differences in sampling depth and the duration of grazing years. Our results highlight that the key factors influencing SOC dynamics differ among soil layers. Climatic and grazing factors have different roles in determining SOC in each soil layer.
Collapse
Affiliation(s)
- Yantao Wu
- Key Laboratory of Ecology and Resource Use of the Mongolian Plateau Ministry of Education of China Hohhot China
- Collaborative Innovation Center for Grassland Ecological Security Ministry of Education of China Hohhot China
- School of Ecology and Environment Inner Mongolia University Hohhot China
| | - Zhiwei Guo
- Key Laboratory of Ecology and Resource Use of the Mongolian Plateau Ministry of Education of China Hohhot China
- Collaborative Innovation Center for Grassland Ecological Security Ministry of Education of China Hohhot China
- School of Ecology and Environment Inner Mongolia University Hohhot China
| | - Zhiyong Li
- Key Laboratory of Ecology and Resource Use of the Mongolian Plateau Ministry of Education of China Hohhot China
- Collaborative Innovation Center for Grassland Ecological Security Ministry of Education of China Hohhot China
- School of Ecology and Environment Inner Mongolia University Hohhot China
| | - Maowei Liang
- Department of Environmental Sciences University of Virginia Charlottesville USA
| | | | - Jinghui Zhang
- Key Laboratory of Ecology and Resource Use of the Mongolian Plateau Ministry of Education of China Hohhot China
- Collaborative Innovation Center for Grassland Ecological Security Ministry of Education of China Hohhot China
- School of Ecology and Environment Inner Mongolia University Hohhot China
| | - Bailing Miao
- Inner Mongolia Meteorological Institute Hohhot China
| | - Lixin Wang
- Key Laboratory of Ecology and Resource Use of the Mongolian Plateau Ministry of Education of China Hohhot China
- Collaborative Innovation Center for Grassland Ecological Security Ministry of Education of China Hohhot China
- School of Ecology and Environment Inner Mongolia University Hohhot China
| | - Cuizhu Liang
- Key Laboratory of Ecology and Resource Use of the Mongolian Plateau Ministry of Education of China Hohhot China
- Collaborative Innovation Center for Grassland Ecological Security Ministry of Education of China Hohhot China
- School of Ecology and Environment Inner Mongolia University Hohhot China
| |
Collapse
|
5
|
Miao B, Feder L, Shrock JE, Milchberg HM. Phase front retrieval and correction of Bessel beams. Opt Express 2022; 30:11360-11371. [PMID: 35473082 DOI: 10.1364/oe.454796] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Accepted: 03/05/2022] [Indexed: 06/14/2023]
Abstract
Bessel beams generated with non-ideal axicons are affected by aberrations. We introduce a method to retrieve the complex amplitude of a Bessel beam from intensity measurements alone, and then use this information to correct the wavefront and intensity profile using a deformable mirror.
Collapse
|
6
|
Chou E, Ganti A, Katranji K, Cotarla I, Sharma C, Miao B, Garg M, Seal B. OFP01.09 Economic Burden of Metastatic Non-Small Cell Lung Cancer (mNSCLC) in a Large United States (US) Claims Database. J Thorac Oncol 2021. [DOI: 10.1016/j.jtho.2020.10.041] [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: 11/26/2022]
|
7
|
Miao B, Feder L, Shrock JE, Goffin A, Milchberg HM. Optical Guiding in Meter-Scale Plasma Waveguides. Phys Rev Lett 2020; 125:074801. [PMID: 32857573 DOI: 10.1103/physrevlett.125.074801] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 07/05/2020] [Accepted: 07/20/2020] [Indexed: 06/11/2023]
Abstract
We demonstrate a new highly tunable technique for generating meter-scale low density plasma waveguides. Such guides can enable laser-driven electron acceleration to tens of GeV in a single stage. Plasma waveguides are imprinted in hydrogen gas by optical field ionization induced by two time-separated Bessel beam pulses: The first pulse, a J_{0} beam, generates the core of the waveguide, while the delayed second pulse, here a J_{8} or J_{16} beam, generates the waveguide cladding, enabling wide control of the guide's density, depth, and mode confinement. We demonstrate guiding of intense laser pulses over hundreds of Rayleigh lengths with on-axis plasma densities as low as N_{e0}∼5×10^{16} cm^{-3}.
Collapse
Affiliation(s)
- B Miao
- Institute for Research in Electronics and Applied Physics University of Maryland, College Park, Maryland 20742, USA
| | - L Feder
- Institute for Research in Electronics and Applied Physics University of Maryland, College Park, Maryland 20742, USA
| | - J E Shrock
- Institute for Research in Electronics and Applied Physics University of Maryland, College Park, Maryland 20742, USA
| | - A Goffin
- Institute for Research in Electronics and Applied Physics University of Maryland, College Park, Maryland 20742, USA
| | - H M Milchberg
- Institute for Research in Electronics and Applied Physics University of Maryland, College Park, Maryland 20742, USA
| |
Collapse
|
8
|
Abstract
Biotic mechanisms associated with species diversity are expected to stabilize communities in theoretical and experimental studies but may be difficult to detect in natural communities exposed to large environmental variation. We investigated biotic stability mechanisms in a multi-site study across Inner Mongolian grassland characterized by large spatial variations in species richness and composition and temporal fluctuations in precipitation. We used a new additive-partitioning method to separate species synchrony and population dynamics within communities into different species-abundance groups. Community stability was independent of species richness but was regulated by species synchrony and population dynamics, especially of abundant species. Precipitation fluctuations synchronized population dynamics within communities, reducing their stability. Our results indicate generality of biotic stability mechanisms in natural ecosystems and suggest that for accurate predictions of community stability in changing environments uneven species composition should be considered by partitioning stabilizing mechanisms into different species-abundance groups.
Collapse
Affiliation(s)
- Yonghui Wang
- Ministry of Education Key Laboratory of Ecology and Resource Use of the Mongolian Plateau & Inner Mongolia Key Laboratory of Grassland Ecology, School of Ecology and Environment, Inner Mongolia University, Hohhot 010021, People's Republic of China
| | - Xiaxia Niu
- Ministry of Education Key Laboratory of Ecology and Resource Use of the Mongolian Plateau & Inner Mongolia Key Laboratory of Grassland Ecology, School of Ecology and Environment, Inner Mongolia University, Hohhot 010021, People's Republic of China
| | - Liqing Zhao
- Ministry of Education Key Laboratory of Ecology and Resource Use of the Mongolian Plateau & Inner Mongolia Key Laboratory of Grassland Ecology, School of Ecology and Environment, Inner Mongolia University, Hohhot 010021, People's Republic of China
| | - Cunzhu Liang
- Ministry of Education Key Laboratory of Ecology and Resource Use of the Mongolian Plateau & Inner Mongolia Key Laboratory of Grassland Ecology, School of Ecology and Environment, Inner Mongolia University, Hohhot 010021, People's Republic of China
| | - Bailing Miao
- Ministry of Education Key Laboratory of Ecology and Resource Use of the Mongolian Plateau & Inner Mongolia Key Laboratory of Grassland Ecology, School of Ecology and Environment, Inner Mongolia University, Hohhot 010021, People's Republic of China
| | - Qing Zhang
- Ministry of Education Key Laboratory of Ecology and Resource Use of the Mongolian Plateau & Inner Mongolia Key Laboratory of Grassland Ecology, School of Ecology and Environment, Inner Mongolia University, Hohhot 010021, People's Republic of China
| | - Jinghui Zhang
- Ministry of Education Key Laboratory of Ecology and Resource Use of the Mongolian Plateau & Inner Mongolia Key Laboratory of Grassland Ecology, School of Ecology and Environment, Inner Mongolia University, Hohhot 010021, People's Republic of China
| | - Bernhard Schmid
- Department of Geography, University of Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
| | - Wenhong Ma
- Ministry of Education Key Laboratory of Ecology and Resource Use of the Mongolian Plateau & Inner Mongolia Key Laboratory of Grassland Ecology, School of Ecology and Environment, Inner Mongolia University, Hohhot 010021, People's Republic of China
| |
Collapse
|
9
|
Zheng Y, Dong L, Li Z, Zhang J, Li Z, Miao B, Jia C, Liang C, Wang L, Li FY. Phylogenetic structure and formation mechanism of shrub communities in arid and semiarid areas of the Mongolian Plateau. Ecol Evol 2019; 9:13320-13331. [PMID: 31871647 PMCID: PMC6912910 DOI: 10.1002/ece3.5787] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Revised: 09/25/2019] [Accepted: 10/07/2019] [Indexed: 11/23/2022] Open
Abstract
The mechanisms of species coexistence within a community have always been the focus in ecological research. Community phylogenetic structure reflects the relationship of historical processes, regional environments, and interactions between species, and studying it is imperative to understand the formation and maintenance mechanisms of community composition and biodiversity. We studied the phylogenetic structure of the shrub communities in arid and semiarid areas of the Mongolian Plateau. First, the phylogenetic signals of four plant traits (height, canopy, leaf length, and leaf width) of shrubs and subshrubs were measured to determine the phylogenetic conservation of these traits. Then, the net relatedness index (NRI) of shrub communities was calculated to characterize their phylogenetic structure. Finally, the relationship between the NRI and current climate and paleoclimate (since the Last Glacial Maximum, LGM) factors was analyzed to understand the formation and maintenance mechanisms of these plant communities. We found that desert shrub communities showed a trend toward phylogenetic overdispersion; that is, limiting similarity was predominant in arid and semiarid areas of the Mongolian Plateau despite the phylogenetic structure and formation mechanisms differing across habitats. The typical desert and sandy shrub communities showed a significant phylogenetic overdispersion, while the steppified desert shrub communities showed a weak phylogenetic clustering. It was found that mean winter temperature (i.e., in the driest quarter) was the major factor limiting steppified desert shrub phylogeny distribution. Both cold and drought (despite having opposite consequences) differentiated the typical desert to steppified desert shrub communities. The increase in temperature since the LGM is conducive to the invasion of shrub plants into steppe grassland, and this process may be intensified by global warming.
Collapse
Affiliation(s)
- Ying Zheng
- Ministry of Education Key Laboratory of Ecology and Resource Use of the Mongolian Plateau & Inner Mongolia Key Laboratory of Grassland EcologySchool of Ecology and EnvironmentInner Mongolia UniversityHohhotChina
| | - Lei Dong
- Ministry of Education Key Laboratory of Ecology and Resource Use of the Mongolian Plateau & Inner Mongolia Key Laboratory of Grassland EcologySchool of Ecology and EnvironmentInner Mongolia UniversityHohhotChina
- State Key Laboratory of Vegetation and Environmental ChangeInstitute of BotanyChinese Academy of SciencesBeijingChina
| | - Zhiyong Li
- Ministry of Education Key Laboratory of Ecology and Resource Use of the Mongolian Plateau & Inner Mongolia Key Laboratory of Grassland EcologySchool of Ecology and EnvironmentInner Mongolia UniversityHohhotChina
| | - Jinghui Zhang
- Ministry of Education Key Laboratory of Ecology and Resource Use of the Mongolian Plateau & Inner Mongolia Key Laboratory of Grassland EcologySchool of Ecology and EnvironmentInner Mongolia UniversityHohhotChina
| | - Zijing Li
- Ministry of Education Key Laboratory of Ecology and Resource Use of the Mongolian Plateau & Inner Mongolia Key Laboratory of Grassland EcologySchool of Ecology and EnvironmentInner Mongolia UniversityHohhotChina
| | - Bailing Miao
- Meteorological Research Institute of Inner MongoliaHohhotChina
| | - Chengzhen Jia
- Ecological and Agricultural Meteorological Center of Inner MongoliaHohhotChina
| | - Cunzhu Liang
- Ministry of Education Key Laboratory of Ecology and Resource Use of the Mongolian Plateau & Inner Mongolia Key Laboratory of Grassland EcologySchool of Ecology and EnvironmentInner Mongolia UniversityHohhotChina
| | - Lixin Wang
- Ministry of Education Key Laboratory of Ecology and Resource Use of the Mongolian Plateau & Inner Mongolia Key Laboratory of Grassland EcologySchool of Ecology and EnvironmentInner Mongolia UniversityHohhotChina
| | - Frank Yonghong Li
- Ministry of Education Key Laboratory of Ecology and Resource Use of the Mongolian Plateau & Inner Mongolia Key Laboratory of Grassland EcologySchool of Ecology and EnvironmentInner Mongolia UniversityHohhotChina
| |
Collapse
|
10
|
Salehi F, Goers AJ, Hine GA, Feder L, Kuk D, Miao B, Woodbury D, Kim KY, Milchberg HM. MeV electron acceleration at 1 kHz with <10 mJ laser pulses: erratum. Opt Lett 2018; 43:1610. [PMID: 29601042 DOI: 10.1364/ol.43.001610] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Indexed: 06/08/2023]
Abstract
In this erratum the funding section of Opt. Lett.42, 215 (2017)OPLEDP0146-959210.1364/OL.42.000215 has been updated.
Collapse
|
11
|
Woodbury D, Feder L, Shumakova V, Gollner C, Schwartz R, Miao B, Salehi F, Korolov A, Pugžlys A, Baltuška A, Milchberg HM. Laser wakefield acceleration with mid-IR laser pulses. Opt Lett 2018; 43:1131-1134. [PMID: 29489797 DOI: 10.1364/ol.43.001131] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Accepted: 01/30/2018] [Indexed: 06/08/2023]
Abstract
We report on, to the best of our knowledge, the first results of laser plasma wakefield acceleration driven by ultrashort mid-infrared (IR) laser pulses (λ=3.9 μm, 100 fs, 0.25 TW), which enable near- and above-critical density interactions with moderate-density gas jets. Relativistic electron acceleration up to ∼12 MeV occurs when the jet width exceeds the threshold scale length for relativistic self-focusing. We present scaling trends in the accelerated beam profiles, charge, and spectra, which are supported by particle-in-cell simulations and time-resolved images of the interaction. For similarly scaled conditions, we observe significant increases in the accelerated charge, compared to previous experiments with near-infrared (λ=800 nm) pulses.
Collapse
|
12
|
Salehi F, Goers AJ, Hine GA, Feder L, Kuk D, Miao B, Woodbury D, Kim KY, Milchberg HM. MeV electron acceleration at 1 kHz with <10 mJ laser pulses. Opt Lett 2017; 42:215-218. [PMID: 28081077 DOI: 10.1364/ol.42.000215] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Accepted: 11/30/2016] [Indexed: 06/06/2023]
Abstract
We demonstrate laser-driven acceleration of electrons to MeV-scale energies at 1 kHz repetition rate using <10 mJ pulses focused on near-critical density He and H2 gas jets. Using the H2 gas jet, electron acceleration to ∼0.5 MeV in ∼10 fC bunches was observed with laser pulse energy as low as 1.3 mJ. Increasing the pulse energy to 10 mJ, we measure ∼1 pC charge bunches with >1 MeV energy for both He and H2 gas jets.
Collapse
|
13
|
Brunetti L, Chapy H, Miao B, Kagan L. P232 Endogenous serum immunoglobulin levels in hospitalized patients. Ann Allergy Asthma Immunol 2016. [DOI: 10.1016/j.anai.2016.09.244] [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: 10/20/2022]
|
14
|
Zhao DD, Huang ZY, Hong LQ, Liao T, Tang YE, Na N, Li H, Miao B, Hua XF, Sun QQ. [Massive hemorrhage caused by fungal infections after donation-after-cardiac-death kidney transplantation: clinical features, prevention and treatment experience]. Zhonghua Yi Xue Za Zhi 2016; 96:1570-2. [PMID: 27266684 DOI: 10.3760/cma.j.issn.0376-2491.2016.20.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
OBJECTIVE To study the characteristics and prevention and treatment strategies of massive hemorrhage caused by fungal infections after donation-after-cardiac-death (DCD) kidney transplantation. METHODS A total of 91 cases of DCD kidney transplantation between August 25, 2013 and June 30, 2015 in Third Affiliated Hospital of Sun Yat-sen Univservity were retrospectively analyzed. The characteristics of and prevention and treatments strategies for postoperative massive hemorrhage caused by fungal infections were summarized. RESULTS Ninety-one cases of DCD kidney transplantation were divided into 2 groups based on regimens for preventing postoperative fungal infections: fluconazole prophylaxis group: a total of 26 cases of renal transplant before June 11, 2014 received fluconazole regimen, from postoperative day 0 to 2 weeks; micafungin prophylaxis group: a total of 65 cases of renal transplant after June 11, 2014 received micafungin regimen, also for 2 weeks from postoperative day 0. Two cases in fluconazole group developed postoperative massive hemorrhage. In case 1, the hemorrhage occurred at 2 weeks after transplantation. Graft nephrectomy was performed during surgical exploration for hemostasis, yet the massive hemorrhage relapsed 2 weeks later. Endoluminal exclusion of external iliac artery using endovascular covered stent-graft at the anastomosis site was performed and the massive bleeding was successfully stopped. The patient was restored to hemodialysis and waited for second kidney transplantation. Candia albicans was detected in the culture of blood and drainage liquid from incision. The other case of hemorrhage occurred at 3 weeks after transplantation. Graft nephrectomy plus endovascular exclusion using covered stent-graft were also performed to stop the massive bleeding. Massive fungal hyphae and spores were observed at the stump of renal graft artery under microscope. The patient received second kidney transplantation after 6 months successfully. No massive hemorrhage caused by fungal infections occurred in micafungin prophylaxis group. CONCLUSIONS Massive hemorrhage cased by fungal infections after DCD kidney transplantation is usually characterized by delayed and recurrent course, and may result in graft nephrectomy or even death of patients. Endovascular exclusion using covered stent can successfully stop bleeding and rescue life of patients. Two-week preemptive prophylaxis of fungal infections using micafungin can effectively prevent delayed fungal massive hemorrhage in DCD kidney transplantation.
Collapse
Affiliation(s)
- D D Zhao
- Department of Kidney Transplantation, Third Affiliated Hospital of Sun Yat-sen University, Guangzhou 510760, China
| | | | | | | | | | | | | | | | | | | |
Collapse
|
15
|
Goers AJ, Hine GA, Feder L, Miao B, Salehi F, Wahlstrand JK, Milchberg HM. Multi-MeV Electron Acceleration by Subterawatt Laser Pulses. Phys Rev Lett 2015; 115:194802. [PMID: 26588390 DOI: 10.1103/physrevlett.115.194802] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Indexed: 06/05/2023]
Abstract
We demonstrate laser-plasma acceleration of high charge electron beams to the ∼10 MeV scale using ultrashort laser pulses with as little energy as 10 mJ. This result is made possible by an extremely dense and thin hydrogen gas jet. Total charge up to ∼0.5 nC is measured for energies >1 MeV. Acceleration is correlated to the presence of a relativistically self-focused laser filament accompanied by an intense coherent broadband light flash, associated with wave breaking, which can radiate more than ∼3% of the laser energy in a ∼1 fs bandwidth consistent with half-cycle optical emission. Our results enable truly portable applications of laser-driven acceleration, such as low dose radiography, ultrafast probing of matter, and isotope production.
Collapse
Affiliation(s)
- A J Goers
- Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20742, USA
| | - G A Hine
- Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20742, USA
| | - L Feder
- Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20742, USA
| | - B Miao
- Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20742, USA
| | - F Salehi
- Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20742, USA
| | - J K Wahlstrand
- Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20742, USA
| | - H M Milchberg
- Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20742, USA
| |
Collapse
|
16
|
Yan H, Liang C, Li Z, Liu Z, Miao B, He C, Sheng L. Impact of precipitation patterns on biomass and species richness of annuals in a dry steppe. PLoS One 2015; 10:e0125300. [PMID: 25906187 PMCID: PMC4407894 DOI: 10.1371/journal.pone.0125300] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Accepted: 03/12/2015] [Indexed: 11/21/2022] Open
Abstract
Annuals are an important component part of plant communities in arid and semiarid grassland ecosystems. Although it is well known that precipitation has a significant impact on productivity and species richness of community or perennials, nevertheless, due to lack of measurements, especially long-term experiment data, there is little information on how quantity and patterns of precipitation affect similar attributes of annuals. This study addresses this knowledge gap by analyzing how quantity and temporal patterns of precipitation affect aboveground biomass, interannual variation aboveground biomass, relative aboveground biomass, and species richness of annuals using a 29-year dataset from a dry steppe site at the Inner Mongolia Grassland Ecosystem Research Station. Results showed that aboveground biomass and relative aboveground biomass of annuals increased with increasing precipitation. The coefficient of variation in aboveground biomass of annuals decreased significantly with increasing annual and growing-season precipitation. Species richness of annuals increased significantly with increasing annual precipitation and growing-season precipitation. Overall, this study highlights the importance of precipitation for aboveground biomass and species richness of annuals.
Collapse
Affiliation(s)
- Hong Yan
- Key Laboratory of Wetland Ecology and Vegetation Restoration, State Environmental Protection, Northeast Normal University, Changchun, China
| | - Cunzhu Liang
- School of Ecology and Environmental Sciences, Inner Mongolia University, Hohhot, China
| | - Zhiyong Li
- School of Ecology and Environmental Sciences, Inner Mongolia University, Hohhot, China
| | - Zhongling Liu
- School of Ecology and Environmental Sciences, Inner Mongolia University, Hohhot, China
| | - Bailing Miao
- School of Ecology and Environmental Sciences, Inner Mongolia University, Hohhot, China
- Meteorological Research Institute of Inner Mongolia, Hohhot, China
| | - Chunguang He
- Key Laboratory of Wetland Ecology and Vegetation Restoration, State Environmental Protection, Northeast Normal University, Changchun, China
| | - Lianxi Sheng
- Key Laboratory of Wetland Ecology and Vegetation Restoration, State Environmental Protection, Northeast Normal University, Changchun, China
| |
Collapse
|
17
|
Dong C, Miao B, Tan C, Wei D, Wu Y. An Estimate of a Change Point in Variance of Measurement Errors and Its Convergence Rate. COMMUN STAT-THEOR M 2015. [DOI: 10.1080/03610926.2012.762395] [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: 10/27/2022]
|
18
|
Zhao D, Wang L, Na N, Huang Z, Miao B, Hong L. A model of isolated, vascular whole thymus transplantation in nude rats. Transplant Proc 2012; 44:1394-8. [PMID: 22664022 DOI: 10.1016/j.transproceed.2011.10.055] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2011] [Accepted: 10/27/2011] [Indexed: 11/29/2022]
Abstract
BACKGROUND We used a model of vascularized thymus lobes as a whole isolated organ transplantation in rats. MATERIALS AND METHODS Male Fisher rats (F344, RT11v1; n = 10) and male homozygous Rowett nude rats (rnu/rnu; n = 10) were used as donors and recipients, respectively. Both vascular lobes of the thymus as a whole isolated organ were heterotopically transplanted to the neck of recipients. The right common carotid artery of the donor thymus was anastomosed end-to-end to the homonymous artery of the recipient. The anterior vena cava and the left brachiocephalic vein of the donor thymus were anastomosed end-to-side to the right and left external jugular veins of the recipient, respectively. Histological examination was used to monitor graft viability; graft function was assessed using flow cytometry (FCM) and immunologic effects by skin grafts in vivo. RESULTS All recipients survived. Preparation of the donors and recipients took 35.6 ± 5.5 minutes and 60.3 ± 15.1 minutes, respectively. The blood supply to the thymus graft was patent. Histology of the thymus on postoperative days 14, 56, and 112 revealed viable grafts with preserved microarchitecture. FCM analysis showed 37.18 ± 11.1% CD3+ T cells at day 21 after transplantation. Skin grafts from F344 and Rowett rats survived 8-10 and more than 30 days, respectively, whereas all third-party Sprague Dawley grafts were rejected within 5 days. CONCLUSION We developed a novel model of isolated, direct vascularized whole thymus transplantation in nude rats, in which both lobes of the fully vascularized thymus were harvested en bloc for successful transplantation.
Collapse
Affiliation(s)
- D Zhao
- Department of Kidney Transplantation, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, China
| | | | | | | | | | | |
Collapse
|
19
|
Li G, Miao B, Hu Q, Qin G. Effect of current sheets on the solar wind magnetic field power spectrum from the Ulysses observation: from Kraichnan to Kolmogorov scaling. Phys Rev Lett 2011; 106:125001. [PMID: 21517318 DOI: 10.1103/physrevlett.106.125001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2010] [Indexed: 05/30/2023]
Abstract
The MHD turbulence theory developed by Iroshnikov and Kraichnan predicts a k(-1.5) power spectrum. Solar wind observations, however, often show a k(-5/3) Kolmogorov scaling. Based on 3 years worth of Ulysses magnetic field data where over 28,000 current sheets are identified, we propose that the current sheet is the cause of the Kolmogorov scaling. We show that for 5 longest current-sheet-free periods the magnetic field power spectra are all described by the Iroshnikov-Kraichnan scaling. In comparison, for 5 periods that have the most number of current sheets, the power spectra all exhibit Kolmogorov scaling. The implication of our results is discussed.
Collapse
Affiliation(s)
- G Li
- Department of Physics and CSPAR, University of Alabama in Huntsville, Alabama 35899, USA.
| | | | | | | |
Collapse
|
20
|
Chen Y, Zhang K, Miao B, Wang B, Hou J. Temperature dependence of morphology and diameter of silicon nanowires synthesized by laser ablation. Chem Phys Lett 2002. [DOI: 10.1016/s0009-2614(02)00671-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
|
21
|
Guan H, Gong Q, Miao B. [Inquiries about methods of primary eye care and prevention of blindness]. Zhonghua Yan Ke Za Zhi 2001; 37:9-11. [PMID: 11864379] [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] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Abstract
OBJECTIVE To inquire about the methods of developing primary eye care (PEC) and prevention of blindness. METHODS The methods of developing PEC and prevention of blindness in recent 10 years were analyzed retrospectively. RESULTS Five grades of PEC network were established. The training courses 1 007 times were held in Nantong, and the epidemiological survey of the blind was carried out for 6 817 259 people. The blind persons were 13 496 in number, and the prevalence of blindness was 0.20%. Cataract operations were performed on 83.16% of the treatable cataract blind persons. The successful rate of cataract surgery was 98.22%. Eight counties became the national advanced counties of prevention of blindness. Nantong city became the first national advanced city of prevention of blindness in 1997. CONCLUSIONS PEC is the basis of prevention of blindness. To bring PEC into line with the primary health care (PHC) is the key point of developing PEC. Affordable operation, promising quality of the operative procedure and combination of survey and treatment are the three essential factors of developing PEC and prevention of blindness. To create national advanced county and city is the motive force of developing prevention of blindness.
Collapse
Affiliation(s)
- H Guan
- Department of Ophthalmology, Affiliated Hospital, Nantong Medical College, Nantong 226001, China
| | | | | |
Collapse
|
22
|
Abstract
Re-investigation of the aerial parts of Iva frutescens resulted in the isolation of three sesquiterpenes, two of which are new natural products, and their structures were established by spectral data.
Collapse
Affiliation(s)
- A A Ahmed
- Department of Chemistry, Faculty of Science, El-Minia University, Egypt
| | | | | | | | | | | |
Collapse
|
23
|
Abstract
Mge1, a GrpE-related protein in the mitochondrial matrix of the budding yeast Saccharomyces cerevisiae, is required for translocation of precursor proteins into mitochondria. The effect of Mge1 on nucleotide release from Ssc1, an Hsp70 of the mitochondrial matrix, was analyzed. The release of both ATP and ADP from Ssc1 was stimulated in the presence of Mge1, therefore we conclude that Mge1 functions as a nucleotide release factor for Ssc1. Mge1 bound stably to Ssc1 in vitro; this interaction was resistant to high concentrations of salt but was disrupted by the addition of ATP. ADP was much less effective in releasing Mge1 from Ssc1 whereas ATP gamma S and AMPPNP could not disrupt the Ssc1/Mge1 complex. Ssc1-3, a temperature sensitive SSC1 mutant protein, did not form a detectable complex with Mge1. Consistent with the lack of a detectable interaction, Mge1 did not stimulate nucleotide release from Ssc1-3. A conserved loop structure on the surface of the ATPase domain of DnaK has been implicated in its interaction with GrpE. Since the single amino acid change in Ssc1-3 lies very close to the analogous loop in Ssc1, the role of this loop in the Ssc1:Mge1 interaction was investigated. Deletion of the loop abolished the physical and functional interaction of Ssc1 with Mge1, suggesting that the loop in Ssc1 is also important for the Ssc1:Mge1 interaction. Two mutants with single amino acid changes within the loop did not eliminate the stable binding of Mge1, yet the binding of Mge1 did not stimulate the release of nucleotides from the mutant SSC1 proteins. We propose that the loop region of Ssc1 is important for the physical interaction between Mge1 and Ssc1, and for generation of a conformational change necessary for Mge1-induced nucleotide release.
Collapse
Affiliation(s)
- B Miao
- Department of Biomolecular Chemistry, University of Wisconsin, Madison 53706, USA
| | | | | |
Collapse
|
24
|
Schilke B, Forster J, Davis J, James P, Walter W, Laloraya S, Johnson J, Miao B, Craig E. The cold sensitivity of a mutant of Saccharomyces cerevisiae lacking a mitochondrial heat shock protein 70 is suppressed by loss of mitochondrial DNA. J Biophys Biochem Cytol 1996; 134:603-13. [PMID: 8707841 PMCID: PMC2120932 DOI: 10.1083/jcb.134.3.603] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
SSH1, a newly identified member of the heat shock protein (hsp70) multigene family of the budding yeast Saccharomyces cerevisiae, encodes a protein localized to the mitochondrial matrix. Deletion of the SSH1 gene results in extremely slow growth at 23 degrees C or 30 degrees C, but nearly wild-type growth at 37 degrees C. The matrix of the mitochondria contains another hsp70, Ssc1, which is essential for growth and required for translocation of proteins into mitochondria. Unlike SSC1 mutants, an SSH1 mutant showed no detectable defects in import of several proteins from the cytosol to the matrix compared to wild type. Increased expression of Ssc1 partially suppressed the cold-sensitive growth defect of the SSH1 mutant, suggesting that when present in increased amounts, Ssc1 can at least partially carry out the normal functions of Ssh1. Spontaneous suppressors of the cold-sensitive phenotype of an SSH1 null mutant were obtained at a high frequency at 23 degrees C, and were all found to be respiration deficient. 15 of 16 suppressors that were analyzed lacked mitochondrial DNA, while the 16th had reduced amounts. We suggest that Ssh1 is required for normal mitochondrial DNA replication, and that disruption of this process in ssh1 cells results in a defect in mitochondrial function at low temperatures.
Collapse
Affiliation(s)
- B Schilke
- Department of Biomolecular Chemistry, University of Wisconsin, Madison 53706, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
25
|
Gambill BD, Voos W, Kang PJ, Miao B, Langer T, Craig EA, Pfanner N. A dual role for mitochondrial heat shock protein 70 in membrane translocation of preproteins. J Biophys Biochem Cytol 1993; 123:109-17. [PMID: 8408191 PMCID: PMC2119813 DOI: 10.1083/jcb.123.1.109] [Citation(s) in RCA: 226] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
The role of mitochondrial 70-kD heat shock protein (mt-hsp70) in protein translocation across both the outer and inner mitochondrial membranes was studied using two temperature-sensitive yeast mutants. The degree of polypeptide translocation into the matrix of mutant mitochondria was analyzed using a matrix-targeted preprotein that was cleaved twice by the processing peptidase. A short amino-terminal segment of the preprotein (40-60 amino acids) was driven into the matrix by the membrane potential, independent of hsp70 function, allowing a single cleavage of the presequence. Artificial unfolding of the preprotein allowed complete translocation into the matrix in the case where mutant mt-hsp70 had detectable binding activity. However, in the mutant mitochondria in which binding to mt-hsp70 could not be detected the mature part of the preprotein was only translocated to the intermembrane space. We propose that mt-hsp70 fulfills a dual role in membrane translocation of preproteins. (a) Mt-hsp70 facilitates unfolding of the polypeptide chain for translocation across the mitochondrial membranes. (b) Binding of mt-hsp70 to the polypeptide chain is essential for driving the completion of transport of a matrix-targeted preprotein across the inner membrane. This second role is independent of the folding state of the preprotein, thus identifying mt-hsp70 as a genuine component of the inner membrane translocation machinery. Furthermore we determined the sites of the mutations and show that both a functional ATPase domain and ATP are needed for mt-hsp70 to bind to the polypeptide chain and drive its translocation into the matrix.
Collapse
Affiliation(s)
- B D Gambill
- Department of Biomolecular Chemistry, University of Wisconsin-Madison 53706
| | | | | | | | | | | | | |
Collapse
|