分类： 地球科学 >> 地理学 提交时间： 2021-01-15 合作期刊: 《干旱区科学》
摘要： Corn straw return to the field is a vital agronomic practice for increasing soil organic carbon (SOC) and its labile fractions, as well as soil aggregates and organic carbon (OC) associated with water-stable aggregates (WSA). Moreover, the labile SOC fractions play an important role in OC turnover and sequestration. The aims of this study were to determine how different corn straw returning modes affect the contents of labile SOC fractions and OC associated with WSA. Corn straw was returned in the following depths: (1) on undisturbed soil surface (NTS), (2) in the 0–10 cm soil depth (MTS), (3) in the 0–20 cm soil depth (CTS), and (4) no corn straw applied (CK). After five years (2014–2018), soil was sampled in the 0–20 and 20–40 cm depths to measure the water-extractable organic C (WEOC), permanganate oxidizable C (KMnO4-C), light fraction organic C (LFOC), and WSA fractions. The results showed that compared with CK, corn straw amended soils (NTS, MTS and CTS) increased SOC content by 11.55%–16.58%, WEOC by 41.38%–51.42%, KMnO4-C and LFOC by 29.84%–34.09% and 56.68%–65.36% in the 0–40 cm soil depth. The LFOC and KMnO4-C were proved to be the most sensitive fractions to different corn straw returning modes. Compared with CK, soils amended with corn straw increased mean weight diameter by 24.24%–40.48% in the 0–20 cm soil depth. The NTS and MTS preserved more than 60.00% of OC in macro-aggregates compared with CK. No significant difference was found in corn yield across all corn straw returning modes throughout the study period, indicating that adoption of NTS and MTS would increase SOC content and improve soil structure, and would not decline crop production.
分类： 生物学 >> 生物物理学 >> 影像医学与生物医学工程 提交时间： 2016-05-12
Chen, Minghai
Li, Wei
Zhang, Zhiping
Liu, Sanying
Zhang, Xiaowei
Zhang, Xian-En
Cui, Zongqiang
Zhang, Xian-En
Chen, Minghai
Liu, Sanying
摘要： Monitoring protein protein interactions (PPIs) in live subjects is critical for understanding these fundamental biological processes. Bimolecular fluorescence complementation (BiFC) provides a good technique for imaging PPIs; however, a BiFC system with a long wavelength remains to be pursued for in vivo imaging. Here, we conducted systematic screening of split reporters from a bacterial phytochrome-based, near-infrared fluorescent protein (iRFP). Several new near-infrared phytochrome BiFC systems were built based on selected split sites including the amino acids residues 97/98, 99/100,122/123, and 123/124. These new near-infrared BiFC systems from a bacterial phytochrome were verified as powerful tools for imaging PPIs under physiological conditions in live cells and in live mice. The interaction between HIV-1 integrase (IN) and cellular cofactor protein Lens epithelium-derived growth factor (LEDGF/p75) was visualized in live cells using the newly constructed iRFP BiFC system because of its important roles in HIV-1 integration and replication. Because the HIV IN-LEDGF/p75 interaction is an attractive anti-HIV target, drug evaluation assays to inhibit the HIV IN-LEDGF/p75 interaction were also performed using the newly constructed BiFC system. The results showed that compound 6 and carbidopa inhibit the HIV IN-LEDGF/p75 interaction in a dose-dependent manner under physiological conditions in the BiFC assays. This study provides novel near-infrared BiFC systems for imaging protein interactions under physiological conditions and provides guidance for splitting other bacterial phytochrome-like proteins to construct BiFC systems. The study also provides a new method for drug evaluation in live cells based on iRFP BiFC systems and supplies some new information regarding candidate drugs for anti-HIV therapies. (C) 2015 Elsevier Ltd. All rights reserved.
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