A new strategy for cellulases application in high temperature industrial scenarios with syringic acid assisting

In the process of bioethanol production, more stable and active cellulase in high temperature condition is required. In this study, syringic acid was applied in cellulase hydrolysis system. At 70°C, TvEG3 activity increased 201.36%, CtBglA activity decreased 72.79% by syringic acid. With syringic acid assisting, TvEG3 thermostability was improved, CtBglA thermostability was reduced. Syringic acid scarcely affected CtCBH. In hydrolysis system with the cellulases containing TvEG3, CtCBH, and CtBglA, the reducing sugar yield improved by 28.37% with syringic acid assisting. With the molecular dynamic simulation in syringic acid system, the backbone root-mean-square deviation (RMSD) and the residue root-mean-square fluctuation (RMSF) of TvEG3, CtCBH reduced, while the RMSD and RMSF of CtBglA increased. The reduction in the number of secondary structures, especially α-helix, caused the structure of CtBglA in the presence of syringic acid to collapse at high temperature. More secondary structures in TvEG3 and more α-helix in CtCBH in the presence of syringic acid make them more stable at high temperatures. These means syringic acid can stabilize TvEG3 and CtCBH structure, destabilize CtBglA structure at high temperature. In summary, this study not only provides insight into cellulase hydrolysis at high temperature with syringic acid assisting but also demonstrates the promoting mechanism of syringic acid.     

Enrichment of homoacetogens converting H2/CO2 into acids and ethanol and simultaneous methane production

An anaerobic granular sludge was enriched to utilize H₂/CO₂ in a continuous gas-fed up-flow anaerobic sludge reactor by applying operating conditions expected to produce acetic acid, butyric acid, and ethanol. Three stages of fermentation were found: Stage I with acetic acid accumulation with the highest concentration of 35 mM along with a pH decrease from initial 6 to 4.5. In Stage II, H₂/CO₂ was replaced by 100% H₂ to induce solventogenesis, whereas butyric acid was produced with the highest concentration of 2.5 mM. At stage III with 10 µM tungsten (W) addition, iso-valeric acid, valeric acid, and caproic acid were produced at pH 4.5–5.0. In the batch tests inoculated with the enriched sludge taken from the bioreactor (day 70), however, methane production occurred at pH 6. Exogenous 15 mM acetate addition enhanced both the H₂ and CO₂ consumption rate compared to exogenous 10, 30, and 45 mM acetate by the enriched sludge. Exogenous acetate was failed to be converted to ethanol using H₂ as electron donor by the enriched acetogens.     

Biological monitoring of deltamethrin in sprayers by HPLC method.

Using HPLC, the authors had investigated the three metabolites of deltamethrin (DM) in the urine of spraymen and one suicide, namely: dibromovinyl-dimethylcyclopropane carboxylic acid (Br2A), 3-phenoxybenzyl-hydroxy-ethyl acetate (PHE) and 3-phenoxyl-benzoic acid (BA). Br2A was chosen as the biological monitoring parameter for DM exposed people, and the urine samples of one suicide and 11 farmers sprayed DM or DM plus methamidophos were examined for Br2A quantitatively which was detected in 8 of 11 sprayers and in the suicide case.     

THE DISCOVERY OF THE GENUS SHELFORDIA CAMERON (HYMENOPTERA: BRACONTOAE: BRACONINAE) IN CHINA, WITH DESCRIPTION OF ONE NEW SPECIES

The genus Shelfordia is discovered in China for the first time, and one new species of this genus (S. chinensis sp. nov.) is fully described and illustrated in the present paper. The type specimen is deposited in the Parasitic Hymenoptera Collection, Zhejiang University, Hangzhou, China.     

Syntheses of cyclic prodrugs of RGD peptidomimetics with various macrocyclic ring sizes: evaluation of physicochemical, transport and antithrombic properties.

The objective of this work was to synthesize cyclic prodrugs 1a-d of RGD peptidomimetics 2a-d with various ring sizes (n[CH2] = 1, 3, 5 and 7) and to evaluate the effect of ring size on their transport, physicochemical, enzymatic stability, and antithrombic properties. The syntheses of cyclic prodrugs 1a-d were achieved by converging two key intermediates, Boc-Phe-O-CH2-OCO-OpNP (5) and H2N-(CH2)n-CO-Asp(OBzl)-OTce (8a-d), to give linear precursors Boc-Phe-O-CH2-OCO-HN-(CH2)n-CO-Asp(OBzl)-OTce (9a-d). The N- and C-terminus protecting groups were removed from 9a-d to give 10a-d. Linear precursors 10a-d were cyclized, and the remaining Bzl-protecting group was removed to produce cyclic prodrugs 1a-d in around 20% overall yield. The linear RGD peptidomimetics (2a-d) were synthesized using standard Boc-amino acid chemistry by solution-phase method. Increasing the ring size by adding methylene groups also increases the hydrophobicity of the cyclic prodrugs and parent RGD peptidomimetics. The transport properties of cyclic prodrugs 1c and 1d were 2.6- and 4.4-fold better than those of parent compounds 2c and 2d, respectively. These results suggest that increasing the hydrophobicity of the cyclic prodrugs and parent RGD peptidomimetics enhanced their transport properties. The hydrodynamic radii of the cyclic prodrugs were also smaller than those of their respective parent compounds, suggesting that the change in size may contribute to their transport properties. The chemical stability of the cyclic prodrugs was affected by the ring size, and the cyclic prodrug with the larger ring size (i.e. 1d) was more stable than the smaller one (i.e. 1a). All the cyclic prodrugs were more stable at pH 4 than at pH 7 and 10. Prodrug-to-drug conversion could be induced by isolated esterase as well as esterase found in human plasma. An increase in the length of methylene group (n[CH2] = 1, 3, 5, 7) enhanced the antithrombic activity of the prodrugs and the parent compounds. In summary, the ring size of cyclic prodrugs affected their transport, physicochemical, and antithrombic properties.     

A rapid method for determination of Proteus vulgaris with a piezoelectric quartz crystal sensor coated with a thin liquid film

A rapid method for microorganism detection using a piezoelectric quartz crystal sensor (PQC) coated with a thin liquid culture medium film was developed and applied to detect the cell number of Proteus vulgaris. This method employed the viscosity and density response of PQC and utilized the coagulation of gelatine medium solution in which the microorganisms had grown to determine the microorganism indirectly. Three time points (TT₁, DT, TT₂) were obtained from the coagulation curve and were found to be in good linear relationship with the logarithm of the initial number of P. vulgaris in the range 1·3 × 10²−1·3 × 10⁵ cells/ml. The detection was rapid and accurate because the coagulation of the thin liquid culture medium film was quick and the time points in the response curve were sharp and so were easy to determine accurately. The detection time was less than 4 h and only a micro sample was needed. A 5 h preincubation was needed before detection. Some experimental conditions are discussed in detail.     

培养大鼠颈上神经节单烟碱受体通道及突触电流的膜片钳研究

在培养１─２周的大鼠颈上神经节交感神经元标本上,用膜片钳技术记录了单烟碱受体通道电流及胆碱能突触电流,并分析了它们之间的关系。单烟碱受体通道至少有三种亚导状态,即１５ｐＳ,２７ｐＳ,３８ｐＳ,其中以２７ｐＳ最常见。通道有两种开放模式,即单个短促开放与长串开放。对应的平均开放时间分别为τ＿１＝１．７１ｍｓ,τ＿２＝１２．２４ｍｓ。对自发突触电流的分析表明,其下降相的衰减时间常数（τ＝１５．７±１ｍｓ）与上述长串开放的持续时间相当,提示在突触传递过程中,突触前末梢释放的ＡＣｈ引起了突触后神经元烟碱受体通道的长串开放。     

脏器微血管对荧光素钠通透性的实验方法

大鼠颈动脉注射１％ＦｌＮａ,荧光显微镜下活体观察肠系膜微血管血流状态及ＦｌＮａ的渗出情况,并在不同时间点经股动脉采血,测定血浆内ＦｌＮａ浓度随时间的变化,利用组织匀浆测定不同脏器中ＦｌＮａ的分布,再辅以冰冻切片进行观察。活体观察发现,ＦｌＮａ注入体内后,经微血管迅速向周围组织渗出,最后汇集于淋巴管,血浆及组织匀浆ＦｌＮａ浓度的测定表明,ＦｌＮａ浓度随时间的变化呈指数衰减,各脏器ＦｌＮａ的分布极不相同。冰冻切片也显示了同样的分布差别。这些结果表明,我们所建立的方法可直观、定量地反映ＦｌＮａ在微血管的通透情况。