气态烃诱导下油气微生物数量及功能基因变化特征

【目的】烃类渗漏是地球化学循环中的自然垂直运移现象。油气微生物勘探技术就是通过检测油气微生物在烃类渗漏条件下形成的异常特征进而预测下伏油气藏。然而,上浮烃类比重小,使得油气微生物丰度小,缺乏对油气藏地表烃类与油气微生物的深入认识。【方法】本研究在人工模拟环境下,采用培养法和定量PCR对油气微生物数量和油气功能基因的变化特征进行研究。【结果】人工模拟的不同渗漏环境,在一定的驯化培养周期下分别考察甲烷氧化菌和丁烷氧化菌数量变化特征,甲烷氧化菌与丁烷氧化菌在不同烃源中呈现不同的发育情况;同时,在气态烃高浓度阳性对照和微渗漏条件下,油气指示基因pmo A与bom X基因丰度呈现增长现象,然而经过吹脱实验基因丰度仍能指示出曾经发育的油气微生物,在油气微生物勘探检测分析时间尺度上精度高于数量水平的检测。【结论】本研究考察了土壤中油气微生物的数量和功能基因变化特征,为烃类渗漏与油气微生物之间的相关性研究奠定了基础,为油气微生物勘探提供直接实验依据。     

Inhibition of mevalonate 5-diphosphate decarboxylase by fluorinated substrate analogs

Mevalonate 5-diphosphate decarboxylase (MDD) is a peroxisomal enzyme in the cholesterol biosynthetic pathway, which plays an important role in regulating cholesterol biosynthesis. In the present study, rat MDD was cloned and purified to apparent homogeneity. Two fluorinated MDD substrate analogs, P'-geranyl 2-fluoromevalonate 5-diphosphate (4) and 2-fluoromevalonate 5-diphosphate (6), were synthesized, and both were found to be irreversible inhibitors of rat MDD. These two inhibitors were characterized, and mechanisms of the inactivation process were proposed. Kinetic studies indicate both analogs only bind into mevalonate binding-site of MDD. Compound 4 shows competitive inhibition on mevalonate kinase (MVK), and its IC(50) value was determined to be comparable with that of geranyl diphosphate. Further kinetic studies indicate compound 4 only bind into ATP binding-site of MVK. These studies provide an example for a single inhibitor to carry out sequential blocking of two enzymes in cholesterol biosynthesis, which may provide useful information for drug discovery for the purpose of treating cardiovascular disease and cancer or for pest control.     

DNA and adenovirus tumor vaccine expressing truncated survivin generates specific immune responses and anti-tumor effects in a murine melanoma model

Survivin is overexpressed in major types of cancer and is considered an ideal "universal" tumor-associated antigen that can be targeted by immunotherapeutic vaccines. However, its anti-apoptosis function raises certain safety concerns. Here, a new truncated human survivin, devoid of the anti-apoptosis function, was generated as a candidate tumor vaccine. Interleukin 2 (IL-2) has been widely used as an adjuvant for vaccination against various diseases. Meanwhile, the DNA prime and recombinant adenovirus (rAd) boost heterologous immunization strategy has been proven to be highly effective in enhancing immune responses. Therefore, the efficacy of a new cancer vaccine based on a truncated form of survivin, combined with IL-2, DNA prime, and rAd boost, was tested. As prophylaxis, immunization with the DNA vaccine alone resulted in a weak immune response and modest anti-tumor effect, whereas the tumor inhibition ratio with the DNA vaccine administered with IL-2 increased to 89?% and was further increased to nearly 100?% by rAd boosting. Moreover, complete tumor rejection was observed in 5 of 15 mice. Efficacy of the vaccine administered therapeutically was enhanced by nearly 300?% when combined with carboplatin. These results indicated that vaccination with a truncated survivin vaccine using DNA prime-rAd boost combined with IL-2 adjuvant and carboplatin represents an attractive strategy to overcoming immune tolerance to tumors and has potential therapeutic benefits in melanoma cancer.     

可控多孔生物陶瓷的制备技术中浆料性能及其影响因素的研究

浆料的性能是可控多孔生物陶瓷技术的重要影响因素。本文对浆料性能的几个主要影响因素进行了专门研究和探讨,同时对浆料稳定性、流动性和可逆性进行了研究,从而获得浆料性能的几个主要影响因素的具体情况,得到了浆料制备的最佳工艺参数。     

Bid-cardiolipin interaction at mitochondrial contact site contributes to mitochondrial cristae reorganization and cytochrome C release

Release of cytochrome c from the mitochondrial intermembrane space is critical to apoptosis induced by a variety of death stimuli. Bid is a BH3-only prodeath Bcl-2 family protein that can potently activate this efflux. In the current study, we investigated the mitochondrial localization of Bid and its interactions with mitochondrial phospholipids, focusing on their relationships with Bid-induced cytochrome c release. We found that Bid binding to the mitochondria required only three of its eight helical structures (alpha4-alpha6), but not the BH3 domain, and the binding could not be inhibited by the antideath molecule Bcl-x(L). Membrane fractionations indicated that tBid bound to mitochondrial outer membranes at both contact and noncontact sites. Bid could interact with specific cardiolipin species on intact mitochondria as identified by mass spectrometry. Like the binding to the mitochondria, this interaction could not be blocked by the mutation in the BH3 domain or by Bcl-x(L.) However, a cardiolipin-specific dye, 10-N-nonyl acridine orange, could preferentially suppress Bid binding to the mitochondrial contact site and inhibit Bid-induced mitochondrial cristae reorganization and cytochrome c release. These findings thus suggest that interactions of Bid with mitochondrial cardiolipin at the contact site can contribute significantly to its functions.     

Salinity-induced changes in the rhizosphere microbiome improve salt tolerance of Hibiscus hamabo

Plant and Soil - Different grazing management practices have a significant impact on the sustainability of grassland ecosystems. This study invested the vertical distribution of soil nitrogen (N)...     

An Invasive Plant Promotes Its Arbuscular Mycorrhizal Symbioses and Competitiveness through Its Secondary Metabolites: Indirect Evidence from Activated Carbon

Secondary metabolites released by invasive plants can increase their competitive ability by affecting native plants, herbivores, and pathogens at the invaded land. Whether these secondary metabolites affect the invasive plant itself, directly or indirectly through microorganisms, however, has not been well documented. Here we tested whether activated carbon (AC), a well-known absorbent for secondary metabolites, affect arbuscular mycorrhizal (AM) symbioses and competitive ability in an invasive plant. We conducted three experiments (experiments 1–3) with the invasive forb Solidago canadensis and the native Kummerowia striata. Experiment 1 determined whether AC altered soil properties, levels of the main secondary metabolites in the soil, plant growth, and AMF communities associated with S. canadensis and K. striata. Experiment 2 determined whether AC affected colonization of S. canadensis by five AMF, which were added to sterilized soil. Experiment 3 determined the competitive ability of S. canadensis in the presence and absence of AMF and AC. In experiment 1, AC greatly decreased the concentrations of the main secondary metabolites in soil, and the changes in concentrations were closely related with the changes of AMF in S. canadensis roots. In experiment 2, AC inhibited the AMF Glomus versiforme and G. geosporum but promoted G. mosseae and G. diaphanum in the soil and also in S. canadensis roots. In experiment 3, AC reduced S. canadensis competitive ability in the presence but not in the absence of AMF. Our results provided indirect evidence that the secondary metabolites (which can be absorbed by AC) of the invasive plant S. canadensis may promote S. canadensis competitiveness by enhancing its own AMF symbionts.     

Multi-target-directed design,syntheses, and characterization of fluorescent bisphosphonate derivatives as multifunctional enzyme inhibitors in mevalonate pathway

Background

Mevalonate pathway is an important cellular metabolic pathway present in all higher eukaryotes and many bacteria. Four enzymes in mevalonate pathway, including MVK, PMK, MDD, and FPPS, play important regulatory roles in cholesterol biosynthesis and cell proliferation.

Methods

The following methods were used: cloning, expression and purification of enzymes in mevalonate pathway, organic syntheses of multifunctional enzyme inhibitors, measurement of their IC₅₀ values for above four enzymes, kinetic studies of enzyme inhibitions, molecular modeling studies, cell viability tests, and fluorescence microscopy.

Results and conclusions

We report our multi-target-directed design, syntheses, and characterization of two blue fluorescent bisphosphonate derivatives compounds 15 and 16 as multifunctional enzyme inhibitors in mevalonate pathway. These two compounds had good inhibition to all these four enzymes with their IC₅₀ values at nanomolar to micromolar range. Kinetic and molecular modeling studies showed that these two compounds could bind to the active sites of all these four enzymes. The fluorescence microscopy indicated that these two compounds could easily get into cancer cells.

General significance

Multifunctional enzyme inhibitors are generally more effective than single enzyme inhibitors, with fewer side effects. Our results showed that these multifunctional inhibitors could become lead compounds for further development for the treatment of soft-tissue tumors and hypercholesteremia.     

Preparation and diagnostic use of a novel recombinant single-chain antibody against rabies virus glycoprotein

Rabies virus (RABV) causes a fatal infectious disease, but effective protection may be achieved with the use of rabies immunoglobulin and a rabies vaccine. Virus-neutralizing antibodies (VNA), which play an important role in the prevention of rabies, are commonly evaluated by the RABV neutralizing test. For determining serum VNA levels or virus titers during the RABV vaccine manufacturing process, reliability of the assay method is highly important and mainly dependent on the diagnostic antibody. Most diagnostic antibodies are monoclonal antibodies (mAbs) made from hybridoma cell lines and are costly and time consuming to prepare. Thus, production of a cost-effective mAb for determining rabies VNA levels or RABV titers is needed. In this report, we describe the prokaryotic production of a RABV-specific single-chain variable fragment (scFv) protein with a His-tag (scFv98H) from a previously constructed plasmid in a bioreactor, including the purification and refolding process as well as the functional testing of the protein. The antigen-specific binding characteristics, affinity, and relative affinity of the purified protein were tested. The scFv98H antibody was compared with a commercial RABV nucleoprotein mAb for assaying the VNA level of anti-rabies serum samples from different sources or testing the growth kinetics of RABV strains for vaccine manufactured in China. The results indicated that scFv98H may be used as a novel diagnostic tool to assay VNA levels or virus titers and may be used as an alternative for the diagnostic antibody presently employed for these purposes.     

Tumor necrosis factor receptor 2 signaling induces selective c-IAP1-dependent ASK1 ubiquitination and terminates mitogen-activated protein kinase signaling

TRAF2 and ASK1 play essential roles in tumor necrosis factor alpha (TNF-alpha)-induced mitogen-activated protein kinase signaling. Stimulation through TNF receptor 2 (TNFR2) leads to TRAF2 ubiquitination and subsequent proteasomal degradation. Here we show that TNFR2 signaling also leads to selective ASK1 ubiquitination and degradation in proteasomes. c-IAP1 was identified as the ubiquitin protein ligase for ASK1 ubiquitination, and studies with primary B cells from c-IAP1 knock-out animals revealed that c-IAP1 is required for TNFR2-induced TRAF2 and ASK1 degradation. Moreover, in the absence of c-IAP1 TNFR2-mediated p38 and JNK activation was prolonged. Thus, the ubiquitin protein ligase activity of c-IAP1 is responsible for regulating the duration of TNF signaling in primary cells expressing TNFR2.