Browsing by Author "Xu, Chao"

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    Large Ecosystem Service Benefits of Assisted Natural Regeneration
    (Wiley, 2018-02-01) Yang, Yusheng; Wang, Lixin; Yang, Zhijie; Xu, Chao; Xie, Jingsheng; Chen, Guangshui; Lin, Chengfang; Guo, Jianfen; Liu, Xiaofei; Xiong, Decheng; Lin, Weisheng; Chen, Shidong; He, Zongming; Lin, Kaimiao; Jiang, Miaohua; Lin, Teng-Chiu; Earth Sciences, School of Science
    China manages the largest monoculture plantations in the world, with 24% being Chinese fir plantations. Maximizing the ecosystem services of Chinese fir plantations has important implications in global carbon cycle and biodiversity protection. Assisted natural regeneration (ANR) is a practice to convert degraded lands into more productive forests with great ecosystems services. However, the quantitative understanding of ANR ecosystem service benefits is very limited. We conducted a comprehensive field manipulation experiment to evaluate the ANR potentials. We quantified and compared key ecosystem services including surface runoff, sediment yield, dissolved organic carbon export, plant diversity, and aboveground carbon accumulation of ANR of secondary forests dominated by Castanopsis carlesii to that of Chinese fir and C. carlesii plantations. Our results showed that ANR of C. carlesii forest reduced surface runoff and sediment yield up to 50% compared with other young plantations in the first 3 years and substantially increased plant diversity. ANR also reduced the export of dissolved organic carbon by 60–90% in the first 2 years. Aboveground biomass of the young ANR forest was approximately 3–4 times of that of other young plantations, while aboveground biomass of mature ANR forests was approximately 1.4 times of that of mature Chinese fir plantations of the same age. If all Chinese fir plantations in China were replaced by ANR forests, potentially 0.7 Pg more carbon will be stored in aboveground in one rotation (25 years). The results indicate that ANR triggers positive feedbacks among soil and water conservation, biodiversity protection, and biomass accumulation and thereby enhances ecosystem services.
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    Recent Photosynthates Are the Primary Carbon Source for Soil Microbial Respiration in Subtropical Forests
    (AGU, 2022-11-28) Yang, Zhijie; Lin, Teng-Chiu; Wang, Lixin; Chen, Shidong; Liu, Xiaofei; Xiong, Decheng; Xu, Chao; Arthur, Mary; McCulley, Rebecca; Shi, Sihong; Yang, Yusheng; Earth and Environmental Sciences, School of Science
    Tropical and subtropical forests represent the largest terrestrial carbon pool. Elucidating the carbon sources for soil microbial respiration (Rm) in tropical and subtropical forests is of fundamental importance to the global carbon cycle in a warming world. Based on hourly measurements, we quantified Rm of in situ forest soil and soil cores from a subtropical forest. We found recent photosynthates, not soil organic carbon (SOC), contributed 88% ± 12% of the carbon source fueling Rm. The control of recent photosynthates on Rm is also supported by the close relationship between Rm and photosynthetically active radiation as well as literature data synthesis results. These results challenge conventional models based on the tenet that Rm is mainly regulated by soil temperature in all forest ecosystems. The results imply that the widely observed warming-induced Rm increases are largely explained by the enhanced input of recent photosynthates in tropical forests, not SOC consumption.
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    RPRD1A and RPRD1B Are Human RNA Polymerase II C-Terminal Domain Scaffolds for Ser5 Dephosphorylation
    (Nature Publishing Group, 2014-08) Ni, Zuyao; Xu, Chao; Guo, Xinghua; Hunter, Gerald O.; Kuznetsova, Olga V.; Tempel, Wolfram; Marcon, Edyta; Zhong, Guoqing; Guo, Hongbo; Kuo, Wei-Hung William; Li, Joyce; Young, Peter; Olsen, Jonathan B.; Wan, Cuihong; Loppnau, Peter; El Bakkouri, Majida; Senisterra, Guillermo A.; He, Hao; Huang, Haiming; Sidhu, Sachdev S.; Emili, Andrew; Murphy, Shona; Mosley, Amber L.; Arrowsmith, Cheryl H.; Min, Jinrong; Greenblatt, Jack F.; Department of Biochemistry & Molecular Biology, IU School of Medicine
    The RNA polymerase II (RNAPII) carboxyl-terminal domain (CTD) heptapeptide repeats (Y1-S2-P3-T4-S5-P6-S7) undergo dynamic phosphorylation and dephosphorylation during the transcription cycle to recruit factors that regulate transcription, RNA processing and chromatin modification. We show here that RPRD1A and RPRD1B form homodimers and heterodimers through their coiled-coil domains and interact preferentially via CTD interaction domains (CIDs) with CTD repeats phosphorylated at S2 and S7. Our high resolution crystal structures of the RPRD1A, RPRD1B and RPRD2 CIDs, alone and in complex with CTD phosphoisoforms, elucidate the molecular basis of CTD recognition. In an interesting example of cross-talk between different CTD modifications, our data also indicate that RPRD1A and RPRD1B associate directly with RPAP2 phosphatase and, by interacting with CTD repeats where phospho-S2 and/or phospho-S7 bracket a phospho-S5 residue, serve as CTD scaffolds to coordinate the dephosphorylation of phospho-S5 by RPAP2.