三峡库区多年高水位运行对消落带狗牙根生长恢复的影响

为深入了解三峡库区多年高水位运行对消落带优势植物生长恢复的影响,分别于2008年和2017年定量调研了库区长寿段消落带狗牙根(Cynodon dactylon)种群的变化,探讨了库区高水位运行对消落带狗牙根萌发、生长和物质分配的影响。结果表明,多年的高水位运行导致不定芽形成和萌发显著被促进,形成更多的分株;高水位运行导致狗牙根分株的株高、茎宽和叶片数被显著抑制,而叶长和种群的总叶片数被显著促进,且随着消落带水位的降低叶长呈降低趋势,而叶宽和总叶片数呈增加趋势;高水位运行导致狗牙根种群匍匐茎和地下茎的茎长、茎节数和总茎长均被显著促进,且随着消落带水位降低匍匐茎茎长和茎节数呈显著的降低趋势,而地下茎茎长和茎节数呈增加趋势;高水位运行导致狗牙根地下茎储存的干质量呈增加趋势,而分株和匍匐茎的干质量呈降低趋势,而且在种群物质分配中地下茎所占的比例呈增大趋势,低水位狗牙根种群的分株和高水位种群的匍匐茎所占的比例也呈增加趋势。因此,狗牙根不仅具有很强的耐淹和生长恢复能力,也具有很强的拓殖能力,可以作为库区中低位消落带恢复和重建的主要原生物种。     

Resveratrol induces AMPK and mTOR signaling inhibition-mediated autophagy and apoptosis in multiple myeloma cells

Resveratrol,a natural compound extracted from the skins of grapes,berries,or other fruits,has been shown to have anti-tumor effects against multiple myeloma(MM)...     

Studying bona fide SARS-CoV-2 biology in a BSL-2 biosafety environment using a split-virus-genome system

<正>Dear Editor,Severe acute respiratory syndrome coronavirus 2(SARSCoV-2) was identified as the pathogen causing the coronavirus disease(COVID-19), which sometimes resulted in fatal pneumonia(Hu et al., 2021). SARS-CoV-2 is a biosafety level 3(BSL-3) pathogen, and the requirement for high containment conditions is a bottleneck for basic research on viral biology.     

In-depth Profiling and Quantification of the Lysine Acetylome in Hepatocellular Carcinoma with a Trapped Ion Mobility Mass Spectrometer

Hepatocellular carcinoma (HCC) is the third most common cause of cancer-related death worldwide with limited therapeutic options. Comprehensive investigation of protein posttranslational modifications in HCC is still limited. Lysine acetylation is one of the most common types of posttranslational modification involved in many cellular processes and plays crucial roles in the regulation of cancer. In this study, we analyzed the proteome and K-acetylome in eight pairs of HCC tumors and normal adjacent tissues using a timsTOF Pro instrument. As a result, we identified 9219 K-acetylation sites in 2625 proteins, of which 1003 sites exhibited differential acetylation levels between tumors and normal adjacent tissues. Interestingly, many novel tumor-specific K-acetylation sites were characterized, for example, filamin A (K865), filamin B (K697), and cofilin (K19), suggesting altered activities of these cytoskeleton-modulating molecules, which may contribute to tumor metastasis. In addition, we observed an overall suppression of protein K-acetylation in HCC tumors, especially for enzymes from various metabolic pathways, for example, glycolysis, tricarboxylic acid cycle, and fatty acid metabolism. Moreover, the expression of deacetylase sirtuin 2 (SIRT2) was upregulated in HCC tumors, and its role of deacetylation in HCC cells was further explored by examining the impact of SIRT2 overexpression on the proteome and K-acetylome in Huh7 HCC cells. SIRT2 overexpression reduced K-acetylation of proteins involved in a wide range of cellular processes, including energy metabolism. Furthermore, cellular assays showed that overexpression of SIRT2 in HCC cells inhibited both glycolysis and oxidative phosphorylation. Taken together, our findings provide valuable information to better understand the roles of K-acetylation in HCC and to treat this disease by correcting the aberrant acetylation patterns.     

Developmental changes of glucocorticoid receptors in the rat pancreas

Glucocorticoids are known to play a role in the maturation of the exocrine pancreas. The exact mechanism of glucocorticoid action in pancreatic ontogeny is, however, not clear. The present study characterized and quantitated the binding of [3H]dexamethasone to cytosol fractions from pancreata of rats at various ages. Trunk blood samples from these rats were also checked for levels of free and bound corticosterone. Specific and saturable bindings for dexamethasone were found in pancreatic cytosol fractions from newborn suckling and adult rats. Competition studies showed a preference for steroids with glucocorticoid activity. Specific binding was relatively low in pancreatic cytosol from newly born and 1-day old pups. A significant rise was seen after day 15. Cytosolic binding capacities were greatest from pancreata obtained from pups at weaning (3rd to 5th weeks). Values then declined toward the adult level. Scatchard analysis revealed a single class of binding sites with a dissociation constant (Kd) of 7.3 (+/- 1.1) X 10(-8) M and number of binding sites equalled to 1.29 (+/- 0.18) X 10(-13) mole/mg of cytosolic protein in adult rat pancreas. Pancreata from 25- and 15-day old rats had Kds of 3.4 (+/- 0.8) X 10(-8) M and 2.7 (+/- 0.7) X 10(-8) M with the number of binding sites equal to 1.77 (+/- 0.21) X 10(-13) mole/mg protein and 1.31 (+/- 0.16) X 10(-13) mole/mg protein respectively. Total plasma corticosterone concentration was low before day 10. It rose significantly by day 15, peaked at day 25, and then declined after weaning. About 5-15% of corticosterone during weaning and about 20-30% before and after weaning were in the free form. The peak level of dexamethasone binding corresponded to an increase in the plasma corticosterone level during weaning. This suggests a close relationship between plasma corticosterone levels and pancreatic glucocorticoid receptors. Both may, therefore, play a role in pancreatic development in the rat.     

Fast classification and compositional analysis of cornstover fractions using Fourier transform near-infrared techniques

The objectives of this research were to determine the variation of chemical composition across botanical fractions of cornstover, and to probe the potential of Fourier transform near-infrared (FT-NIR) techniques in qualitatively classifying separated cornstover fractions and in quantitatively analyzing chemical compositions of cornstover by developing calibration models to predict chemical compositions of cornstover based on FT-NIR spectra. Large variations of cornstover chemical composition for wide calibration ranges, which is required by a reliable calibration model, were achieved by manually separating the cornstover samples into six botanical fractions, and their chemical compositions were determined by conventional wet chemical analyses, which proved that chemical composition varies significantly among different botanical fractions of cornstover. Different botanic fractions, having total saccharide content in descending order, are husk, sheath, pith, rind, leaf, and node. Based on FT-NIR spectra acquired on the biomass, classification by Soft Independent Modeling of Class Analogy (SIMCA) was employed to conduct qualitative classification of cornstover fractions, and partial least square (PLS) regression was used for quantitative chemical composition analysis. SIMCA was successfully demonstrated in classifying botanical fractions of cornstover. The developed PLS model yielded root mean square error of prediction (RMSEP %w/w) of 0.92, 1.03, 0.17, 0.27, 0.21, 1.12, and 0.57 for glucan, xylan, galactan, arabinan, mannan, lignin, and ash, respectively. The results showed the potential of FT-NIR techniques in combination with multivariate analysis to be utilized by biomass feedstock suppliers, bioethanol manufacturers, and bio-power producers in order to better manage bioenergy feedstocks and enhance bioconversion.     

Equilibrium analysis and phase synchronization of two coupled HR neurons with gap junction

The properties of equilibria and phase synchronization involving burst synchronization and spike synchronization of two electrically coupled HR neurons are studied in this paper. The findings reveal that in the non-delayed system the existence of equilibria can be turned into intersection of two odd functions, and two types of equilibria with symmetry and non-symmetry can be found. With the stability and bifurcation analysis, the bifurcations of equilibria are investigated. For the delayed system, the equilibria remain unchanged. However, the Hopf bifurcation point is drastically affected by time delay. For the phase synchronization, we focus on the synchronization transition from burst synchronization to spike synchronization in the non-delayed system and the effect of coupling strength and time delay on spike synchronization in delayed system. In addition, corresponding firing rhythms and spike synchronized regions are obtained in the two parameters plane. The results allow us to better understand the properties of equilibria, multi-time-scale properties of synchronization and temporal encoding scheme in neuronal systems.     

HIV-1 glycoprotein 41 ectodomain induces activation of the CD74 protein-mediated extracellular signal-regulated kinase/mitogen-activated protein kinase pathway to enhance viral infection

Besides mediating the viral entry process, the human immunodeficiency virus (HIV-1) envelope protein gp41 can bind to many host cell components and regulate cell functions. Using a yeast two-hybrid system, we screened a human bone marrow cDNA library and identified a novel gp41-binding protein, CD74 (the MHC class II-associated invariant chain). Here, we report possible biological effects mediated by interaction between gp41 and CD74. We found that HIV-1 gp41 could bind directly to host CD74 in HIV-1-infected cells, and the peptide 6358 derived from gp41 loop region (aa 597-611) could effectively block the gp41-CD74 interaction. As a result of this binding, recombinant soluble gp41 and gp41 peptide 6358 activated the CD74-mediated ERK/MAPK pathway and significantly enhanced HIV-1 infection in vitro. Conversely, the enhancing effect could be suppressed by the recombinant CD74 extracellular domain. These results reveal a novel mechanism underlying gp41 mediation of HIV-1 infection and replication.     

系统发育谱构建方法研究

随着后基因组时代的到来,系统发育谱方法作为一种非同源性的功能注释方法,已经被成功的应用到基因组功能预测、蛋白质相互作用预测等一些重要领域的研究中去。本文阐述了系统发育谱法的基本原理,详细地介绍了现有的几种系统发育谱的构建方法,并提出了利用ortholog来构建基因的系统发育谱的思想。