濒危植物掌叶木种子生态特征

重点研究了贵州茂兰国家级自然保护区喀斯特森林国家一级保护树种掌叶木（Handeliodendron bodinieri)母树的种子生态特征。单因素方差分析表明在同株母树的不同果序球果量和不同母树的球果出种量均未显示明显差异,而不同母树果序出球果量、种子重量分异具有权显著差异,这反应了掌叶木母树的有性生殖基本同步,球果的发育程度比较接近。掌叶木种子干粒重为201．66g,种子的平均重量为0．20g,占乔木树种平均重量的61％;种子含空粒比例高达8．1％;饱满的种子中具有生活力者占78％,反映出掌叶木种子有较高的败育率;种子的平均含水量为13．56％,自然散播的种子萌发率仅为1％,种子在自然环境下受松鼠、鼠和金龟子类等动物的破坏率高达98．25％。在同样贮藏条件下,播种环境对种子的发芽率影响显著,质地疏松、透气性好或火烧地有利于掌叶木种子的萌发,其种子萌发率可达84．98％。     

土壤有机质对农田管理措施的动态响应

土壤有机质在农田肥力、环境保护、农业可持续发展等方面具有重要意义。它不仅决定农作物产量,而且在全球碳素循环中起着重要作用。由于大气CO2浓度升高与全球气候变暖等一系列环境问题的加剧,全球碳素循环受到越来越多的关注。农田具有大气CO2源和库的双重潜力。历史上由于人类对农田的过度开垦和耕种,造成土壤有机质含量大幅度下降,降低了农田的作物产量潜力;同时导致大量的碳以CO2形式由陆地生态系统排放到大气圈,加剧了全球温室效应。大量研究结果表明,诸如耕作、种植制度、施肥等农田管理措施能够显著地影响土壤有机质动态,而免耕、提高复种指数、合理的轮作换茬、有机肥料和化肥的施用以及弃耕农田还林还草等保护性管理措施则能够提高农田土壤有机质含量,使农田起到大气CO2汇的作用。综述了近年来农田管理对土壤有机质动态影响研究方面的进展。     

The cooperativity between hydrogen and halogen bond in the XY···HNC···XY (X,Y = F,Cl, Br) complexes

The cooperativity between hydrogen and halogen bonds in XY···HNC···XY (X, Y = F, Cl, Br) complexes was studied at the MP2/aug-cc-pVTZ level. Two hydrogen-bonded dimers, five hydrogen-bonded dimers, and ten trimers were obtained. The hydrogen- and halogen-bonded interaction energies in the trimers were larger than those in the dimers, indicating that both the hydrogen bonding interaction and the halogen bonding interaction are enhanced. The binary halogen bonding interaction plays the most important role in the ternary system. The hydrogen donor molecule influences the magnitude of the halogen bonding interaction much more than the hydrogen bonding interaction in the trimers with respect to the dimers. Our calculations are consistent with the conclusion that the stronger noncovalent interaction has a bigger effect on the weaker one. The variation in the vibrational frequency in the HNC molecule was considered. The NH antisymmetry vibration frequency has a blue shift, whereas the symmetry vibration frequency has a red shift. A dipole moment enhancement is observed upon formation of the trimers. The variation in topological properties at bond critical points was obtained using the atoms in molecules method, and was consistent with the results of the interaction energy analysis.     

MiR-152 May Silence Translation of CaMK II and Induce Spontaneous Immune Tolerance in Mouse Liver Transplantation

Spontaneous immune tolerance in mouse liver transplantation has always been a hotspot in transplantation-immune research. Recent studies revealed that regulatory T cells (Tregs), hepatic satellite cells and Kupffer cells play a potential role in spontaneous immune tolerance, however the precise mechanism of spontaneous immune tolerance is still undefined. By using Microarray Chips, we investigated different immune regulatory factors to decipher critical mechanisms of spontaneous tolerance after mouse liver transplantation. Allogeneic (C57BL/6-C3H) and syngeneic (C3H-C3H) liver transplantation were performed by 6-8 weeks old male C57BL/6 and C3H mice. Graft samples (N = 4 each group) were collected from 8 weeks post-operation mice. 11 differentially expressed miRNAs in allogeneic grafts (Allografts) vs. syngeneic grafts (Syngrafts) were identified using Agilent Mouse miRNA Chips. It was revealed that 185 genes were modified by the 11 miRNAs, furthermore, within the 185 target genes, 11 of them were tightly correlated with immune regulation after Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis and Genbank data cross-comparison. Verified by real-time PCR and western blot, our results indicated that mRNA expression levels of IL-6 and TAB2 were respectively down regulated following miR-142-3p and miR-155 augment. In addition, increased miR-152 just silenced mRNA of CaMK II and down-regulated translation of CaMK II in tolerated liver grafts, which may play a critical role in immune regulation and spontaneous tolerance induction of mouse liver transplantation.     

Disseminated prostate cancer cells can instruct hematopoietic stem and progenitor cells to regulate bone phenotype

Prostate cancer metastases and hematopoietic stem cells (HSC) frequently home to the bone marrow, where they compete to occupy the same HSC niche. We have also shown that under conditions of hematopoietic stress, HSCs secrete the bone morphogenetic proteins (BMP)-2 and BMP-6 that drives osteoblastic differentiation from mesenchymal precursors. As it is not known, we examined whether metastatic prostate cancer cells can alter regulation of normal bone formation by HSCs and hematopoietic progenitor cells (HPC). HSC/HPCs isolated from mice bearing nonmetastatic and metastatic tumor cells were isolated and their ability to influence osteoblastic and osteoclastic differentiation was evaluated. When the animals were inoculated with the LNCaP C4-2B cell line, which produces mixed osteoblastic and osteolytic lesions in bone, HPCs, but not HSCs, were able to induced stromal cells to differentiate down an osteoblastic phenotype. Part of the mechanism responsible for this activity was the production of BMP-2. On the other hand, when the animals were implanted with PC3 cells that exhibits predominantly osteolytic lesions in bone, HSCs derived from these animals were capable of directly differentiating into tartrate-resistant acid phosphatase-positive osteoclasts through an interleukin-6-mediated pathway. These studies for the first time identify HSC/HPCs as novel targets for future therapy involved in the bone abnormalities of prostate cancer.     

Redox-responsive vesicles prepared from supramolecular cyclodextrin amphiphiles

Redox-responsive vesicles self-assembled by supramolecular cyclodextrin amphiphiles, consisting of the guest (N-1-decyl-ferrocenylmethylamine, 1) and the host (2-O-carboxymethyl-β-cyclodextrin, CM-β-CD), were prepared. The morphologies and sizes of these novel vesicles in an aqueous solution were observed by transmission electron microscopy (TEM) and were confirmed by atomic force microscopy (AFM) and dynamic light scattering (DLS) measurements. The effects of the host-guest ratio, the concentration and the solvent composition of water and methanol on vesicles were investigated in detail. The interactions between the host and the guest, the complex stoichiometry, the stability constant and conformations of 1·CM-β-CD in aqueous solution were investigated by cyclic voltammetry (CV), UV and nuclear magnetic resonance (NMR) measurements. According to the complex stoichiometry and ‘tadpole-like’ spatial conformations, the supramolecular cyclodextrin amphiphiles made from 1·CM-β-CD were proposed to form the membranes of the vesicles. This kind of vesicle system was responsive to an oxidizing agent, which could pave the way to combine supramolecular host-guest chemistry and membrane chemistry for potentially functional applications.