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1. chinaXiv:201707.00474 [pdf]

Cycloheximide congeners produced by Streptomyces sp. SC0581 and photoinduced interconversion between (E)- and (Z)-2,3-dehydro-anhydrocycloheximides

Yang, Li; Wu, Ping; Xue, Jinghua; Tan, Huitong; Zhang, Zheng; Wei, Xiaoyi
Subjects: Biology >> Botany

Three new cycloheximide congeners, 2,3-dehydro-?-epi-isocycloheximide (1), (E)- and (Z)-2,3-dehydro-anhydrocycloheximides (2 and 3), together with three known compounds, anhydroisoheximide (4), cycloheximide (5), and isocycloheximide (6), were obtained from the cultures of Streptomyces sp. SC0581. Their structures were elucidated by extensive spectroscopic analysis in combination with theoretical conformational analysis and ECD computations. The photoinduced interconversion between 2 and 3 was observed and verified and the possible reaction path and mechanism were proposed by theoretical computations. The antifungal and cytotoxic activities of 1–6 were evaluated and suggested that 2,3-dehydrogenation results in the loss of the activities and supported the OH-? is important to the activities of cycloheximide congeners.

submitted time 2017-07-14 Hits1526Downloads808 Comment 0

2. chinaXiv:201605.01630 [pdf]

Numerical simulation of superhalo electrons generated by magnetic reconnection in the solar wind source region

Yang, Li-Ping; Wang, Ling-Hua; He, Jian-Sen; Tu, Chuan-Yi; Zhang, Shao-Hua; Zhang, Lei; Feng, Xue-Shang
Subjects: Geosciences >> Space Physics

Superhalo electrons appear to be continuously present in the interplanetary medium, even during very quiet times, with a power-law spectrum at energies above similar to 2 keV. Here we numerically investigate the generation of superhalo electrons by magnetic reconnection in the solar wind source region, using magnetohydrodynamics and test particle simulations for both single X-line reconnection and multiple X-line reconnection. We find that the direct current electric field, produced in the magnetic reconnection region, can accelerate electrons from an initial thermal energy of T similar to 10(5) K up to hundreds of keV. After acceleration, some of the accelerated electrons, together with the nascent solar wind flow driven by the reconnection, propagate upwards along the newly-opened magnetic field lines into interplanetary space, while the rest move downwards into the lower atmosphere. Similar to the observed superhalo electrons at 1 AU, the flux of upward-traveling accelerated electrons versus energy displays a power-law distribution at similar to 2 - 100 keV, f (E) similar to E-delta, with a delta of similar to 1.5 - 2.4. For single (multiple) X-line reconnection, the spectrum becomes harder (softer) as the anomalous resistivity parameter alpha (uniform resistivity eta) increases. These modeling results suggest that the acceleration in the solar wind source region may contribute to superhalo electrons.

submitted time 2016-05-13 Hits1181Downloads611 Comment 0

3. chinaXiv:201605.01351 [pdf]

CD163+CD14+macrophages, a potential immune biomarker for malignant pleural effusion

Wang, Fei; Yang, Li; Gao, Qun; Huang, Lan; Zhang, Yi; Wang, Fei; Zhang, Yi; Gao, Qun; Wang, Liping; Zhang, Yi; Wang, Jing; Wang, Shengdian; Zhang, Bin
Subjects: Biology >> Biophysics >> Oncology

Malignant pleural effusion (MPE) is a common complication caused by malignant diseases. However, subjectivity, poor sensitivity, and substantial false-negative rates of cytology assay hamper accurate MPE diagnosis. The aim of this study was to assess whether CD163+CD14+ tumor-associated macrophages (TAMs) could be used as a biomarker for enabling sensitive and specific MPE diagnosis. Pleural effusion samples and peripheral blood samples were collected from 50 MPE patients and 50 non-malignant pleural effusion (NMPE) patients, respectively. Flow cytometry was performed to analyze cell phenotypes, and RT-qPCR was used to detect cytokine expression in these monocytes and macrophages. A blinded validation study (n = 40) was subsequently performed to confirm the significance of CD163+CD14+ TAMs in MPE diagnosis. Student's t test, rank sum test, and receiver operating characteristic curve analysis were used for statistical analysis. Notably, CD163+CD14+ cell frequency in MPE was remarkably higher than that in NMPE (P < 0.001). In a blinded validation study, a sensitivity of 78.9 % and a specificity of 100 % were obtained with CD163+CD14+ TAMs as a MPE biomarker. In total (n = 140), by using a cutoff level of 3.65 %, CD163+CD14+ cells had a sensitivity of 81.2 % and a specificity of 100 % for MPE diagnosis. Notably, MPE diagnosis by estimating CD163+CD14+ cells in pleural effusion could be obtained one week earlier than that obtained by cytological examination. CD163+CD14+ macrophages could be potentially used as an immune diagnostic marker for MPE and has better assay sensitivity than that of cytological analysis.

submitted time 2016-05-11 Hits3488Downloads1240 Comment 0

4. chinaXiv:201605.01335 [pdf]

Dynamics of the Lipid Droplet Proteome of the Oleaginous Yeast Rhodosporidium toruloides

Zhu, Zhiwei; Gong, Zhiwei; Zhang, Sufang; Lin, Xinping; Shen, Hongwei; Zou, Hanfa; Zhao, Zongbao K.; Ding, Yunfeng; Yang, Li; Zhang, Congyan; Xie, Zhensheng; Yang, Fuquan; Zhao, Xudong; Liu, Pingsheng; Zhang, Sufang; Shen, Hongwei; Zhao, Zongbao K.
Subjects: Biology >> Biophysics

Lipid droplets (LDs) are ubiquitous organelles that serve as a neutral lipid reservoir and a hub for lipid metabolism. Manipulating LD formation, evolution, and mobilization in oleaginous species may lead to the production of fatty acid-derived biofuels and chemicals. However, key factors regulating LD dynamics remain poorly characterized. Here we purified the LDs and identified LD-associated proteins from cells of the lipid-producing yeast Rhodosporidium toruloides cultured under nutrient-rich, nitrogen-limited, and phosphorus-limited conditions. The LD proteome consisted of 226 proteins, many of which are involved in lipid metabolism and LD formation and evolution. Further analysis of our previous comparative transcriptome and proteome data sets indicated that the transcription level of 85 genes and protein abundance of 77 proteins changed under nutrient-limited conditions. Such changes were highly relevant to lipid accumulation and partially confirmed by reverse transcription-quantitative PCR. We demonstrated that the major LD structure protein Ldp1 is an LD marker protein being upregulated in lipid-rich cells. When overexpressed in Saccharomyces cerevisiae, Ldp1 localized on the LD surface and facilitated giant LD formation, suggesting that Ldp1 plays an important role in controlling LD dynamics. Our results significantly advance the understanding of the molecular basis of lipid overproduction and storage in oleaginous yeasts and will be valuable for the development of superior lipid producers.

submitted time 2016-05-11 Hits1436Downloads699 Comment 0

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