Zengliang Yu

Enhanced enzymatic saccharification of rice straw by microwave pretreatment.

In this study, Box-Behnken design and response surface methodology were employed to plan experiments and optimize the microwave pretreatment of rice straw. Experimental results show that microwave intensity (MI), irradiation time (IT) and substrate concentration (SC) were main factors governing the enzymatic saccharification of rice straw. The maximal efficiencies of cellulose, hemicellulose and total saccharification were respectively increased by 30.6%, 43.3% and 30.3% under the optimal conditions of MI 680 W, IT 24 min and SC 75 g/L. The chemical composition analysis of straw further confirmed that microwave pretreatment could disrupt the silicified waxy surface, break down the lignin-hemicellulose complex and partially remove silicon and lignin.

Hexavalent chromium removal from aqueous solution by algal bloom residue derived activated carbon: Equilibrium and kinetic studies

A novel approach to prepare activated carbon from blue-green algal bloom residue has been tried for first time and its adsorption capability to remove hexavalent chromium Cr(VI) from aqueous solution has been examined. For this algal bloom residue derived activated carbon, the physical characters regarding adsorption capability were analyzed by scanning electron microscope (SEM), energy dispersive X-ray spectroscope (EDS) and Fourier transform infrared (FTIR) spectroscopy. Batch studies showed that initial pH, absorbent dosage, and initial concentration of Cr(VI) were important parameters for Cr(VI) absorption. It was found that initial pH of 1.0 was most favorable for Cr(VI) removal. The adsorption process followed the pseudo-second-order equation and Freundlich isotherm. The maximum adsorption capacity for Cr(VI) was 155.52 mg g(-1) in an acidic medium, which is comparable to best result from activated carbons derived from biomass. Therefore, this work put forward a nearly perfect solution which on one hand gets rid of environment-unfriendly algae residue while on the other hand produces high-quality activated carbon that is in return advantageous to environment protection.

Constitutive nitric oxide acting as a possible intercellular signaling molecule in the initiation of radiation-induced DNA double strand breaks in non-irradiated bystander cells

The initiation and propagation of the early processes of bystander signaling induced by low-dose α-particle irradiation are very important for understanding the underlying mechanism of the bystander process. Our previous investigation showed that the medium collected from cell culture exposed to low-dose α-particle rapidly induced phosphorylated form of H2AX protein foci formation among the non-irradiated medium receptor cells in a time-dependent manner. Using NG-methyl-L-arginine, 4-amino-5-methylamino-2′,7′-difluorofluorescein diacetate and Nω-nitro-L-arginine (L-NNA) treatment before exposure to 1 cGy α-particle, we showed in the present study that nitric oxide (NO•) produced in the irradiated cells was important and necessary for the DNA double strand break inducing activity (DIA) of conditioned medium and the generation of NO• in irradiated confluent AG1522 cells is in a time-dependent manner and that almost all NO• was generated within 15 min post-irradiation. Concurrently, the kinetics of NO• production in the medium of irradiated cells after irradiation was rapid and in a time-dependent manner as well, with a maximum yield observed at 10 min after irradiation with electron spin resonance analysis. Furthermore, our results that 7-Nitroindazole and L-NNA, but not aminoguanidine hemisulfate, treatment before exposure to 1 cGy α-particle significantly decrease the DIA of the conditioned medium suggested that constitutive NO• from the irradiated cells possibly acted as an intercellular signaling molecule to initiate and activate the early process (⩽30 min) of bystander response after low-dose irradiation.

Reduction and Removal of Aqueous Cr(VI) by Glow Discharge Plasma at the Gas-Solution Interface

Aqueous chromium(VI) reduction and removal induced by glow discharge taking place at the gas-solution interface in an argon atmosphere was studied. The effect of initial pH and hydroxyl radical scavenger (ethanol) on the reduction efficiency was examined. High reduction efficiency was obtained when initial pH ≤ 2.0 or ≥ 8.0. In particular, addition of ethanol into the solution substantially increased the reduction efficiency and facilitated chromium removal from the solution in the form of sediment after discharge. The optimum pH values for Cr(VI) removal were within 6.0-7.0. Fourier transform-infrared (FTIR) spectroscopy and X-ray diffraction (XRD) analysis confirmed that the main constituent of the sediment is chromium hydroxide.

Antagonistic effects of volatiles generated by Bacillus subtilis on spore germination and hyphal growth of the plant pathogen, Botrytis cinerea.

Botrytis cinerea is one of the most serious post-harvest pathogens of fruits and vegetables. Volatiles generated by Bacillus subtilis JA significantly inhibited both spore germination and elongation of germ tubes in Botrytis cinerea using a two-compartment agar-plate assay. The volatiles caused protoplasm retraction from the hyphal tips to the spores.

Effects of arbuscular mycorrhizal fungi on the growth, nutrient uptake and glycyrrhizin production of licorice (Glycyrrhiza uralensis Fisch)

The growth of licorice in arid areas faces nutritional and environmental stresses. Arbuscular mycorrhizal (AM) fungi have been shown to increase the abilities of plants to develop. However, little is known regarding the role of AM fungi in licorice (Glycyrrhiza uralensis) growth. In the present study, by inoculation with two AM fungi, Glomus mosseae (Nicolson & Gerdemann) Gerd. & Trappe and Glomus veriforme (P. Karst.), the effects on licorice growth in sand were examined by measuring plant height, number of leaves, shoot and root fresh weight, and by analyzing morphological parameters of the root system in sand. The influence of the two microorganisms on the accumulation of mineral nutritions and bioactive components in licorice were also investigated. The results showed that mycorrhyzae were of the Arum-type and their colonization frequency (F %), colonization intensity (M %) and colonization intensity (m %) of AM fungi inoculation were found to be 80.0–84.6%, 49.4–60.0% and 58.4–71.9%, respectively. The inoculation significantly improved plant growth during early and late growth stages in comparison with the control. Moreover, inoculation of G. mosseae and G. versiforme, alone or in combination, improved plant phosphorus acquisition in the leaf over non-inoculation plants. In addition, mycorrhiza formation enhanced the glycyrrhizin concentration in roots, but resulted in a considerable reduction of the root oxidase activity. The results indicate that the inoculation with AM fungi could be a useful approach to increase the licorice pharmic quality.

Mutation of Gluconobacter oxydans and Bacillus megaterium in a two‐step process of l‐ascorbic acid manufacture by ion beam

Aim:  To increase the transformation rate of l‐sorbose to 2‐keto‐l‐gulonic (2‐KLG) acid in a two‐step process of l‐ascrobic acid manufacture by ion beam.

Targeted Irradiation of Shoot Apical Meristem of Arabidopsis Embryos Induces Long-Distance Bystander/Abscopal Effects

Abstract Yang, G., Wu, L. J., Chen, L. Y., Pei, B., Wang, Y. G., Zhan F. R., Wu, Y. J. and Yu, Z. L. Targeted Irradiation of Shoot Apical Meristem of Arabidopsis Embryos Induces Long-Distance Bystander/Abscopal Effects. Radiat. Res. 167, 298– 305 (2007). Bystander effects induced by low-dose ionizing radiation have been shown to occur widely in many cell types and may have a significant impact on radiation risk assessment. Although the region of radiation damage is known to be much greater than the initial target volume irradiated, it remains to be seen whether this response is limited to the specific organ irradiated, spans a limited region of the body, or even covers the whole body of the target. To determine whether long-distance bystander/abscopal effects exist in whole organisms and to clarify the problem of intercellular communication, in the present study a specific cell group, the shoot apical meristem in Arabidopsis embryo, was irradiated with a defined number of protons and examined for root development postirradiation. The results showed that after direct damage to the shoot apical meristem from ion traversals, root hair differentiation, primary root elongation and lateral root initiation were all inhibited significantly in postembryonic development, suggesting that radiation-induced long-distance bystander/abscopal responses might exist in the whole organism. To further scrutinize the mechanism(s) underlying these inhibitory effects, a DR5-GUS transgenic Arabidopsis was used. The results showed that accumulation of the reporter GUS gene transcript in irradiated shoot apical meristem embryos decreased in the postembryonic development. Treatment with either 2,4-dichlorophenoxyacetic acid, a synthetic plant auxin, or DMSO, a effective reactive oxygen species (ROS) scavenger, could rescue the reporter GUS enzyme accumulation and the length of primary root in irradiated shoot apical meristem embryos, indicating that ROS or probably the ROS related auxin and auxin-dependent transcription process may be involved in radiation-induced long-distance bystander/abscopal effects.

Truncation of the cellulose binding domain improved thermal stability of endo-β-1,4-glucanase from Bacillus subtilis JA18

The C-terminus region of endo-beta-glucanase Egl499 from Bacillus subtilis JA18 was suggested to be a putative family 3 cellulose-binding domain (CBD) by computer analysis. To prove this proposal, C-terminus truncation mutant Egl330 was constructed and expressed. Compared with Egl499, Egl330 lost the cellulose binding capability at 4 degrees C, confirming the C-terminus region was a CBD. Binding of the CBD to Avicel was inhibited by carboxymethylcellulose (CMC), but not by barley beta-glucan and glucose at concentration of 0.1% and 0.5%. Kinetic analysis showed both the turnover rate (k(cat)) and the catalytic efficiency (k(cat)/K(m)) of Egl330 increased for the substrate CMC compared to Egl499. A great improvement in thermal stability was observed in Egl330. The half life of Egl330 at 65 degrees C increased to three folds that of Egl499, from 10 to 29 min. After treated at 80 degrees C for 10 min, Egl330 could recover more than 60% of its original activity while Egl499 only recovered 12% activity. UV spectrometry analysis showed Egl330 and Egl499 differed in refolding efficiency after heat treatment.

In Situ Visualization of DSBs to Assess the Extranuclear/Extracellular Effects Induced by Low-Dose α-Particle Irradiation

Abstract Hu, B., Han, W., Wu, L., Feng, H., Liu, X., Zhang, L., Xu, A., Hei, T K. and Yu, Z. In Situ Visualization of DSBs to Assess the Extranuclear/Extracellular Effects Induced by Low-Dose α-Particle Irradiation. Radiat. Res. 164, 286–291 (2005). Extranuclear/extracellular effects may have a significant effect on low-dose radiation risk assessment as well as on the shape of the dose–response relationship. Numerous studies using different end points such as sister chromatid exchanges, micronuclei and mutation have shown that this phenomenon exists in many cell types. However, these end points mostly reflect the late events after radiation damage, and little is known about the early response in this phenomenon. DNA double-strand breaks (DSBs) induced by ionizing radiation or carcinogenic chemicals can be visualized in situ using γ-H2AX immunofluorescence staining, and there is evidence that the number of γ-H2AX foci can be closely correlated with DSBs induced. Here we used γ-H2AX as a biomarker to assess the extranuclear/extracellular effects induced by low-dose α particles in situ. The results show that a greater fraction of positive cells with DSBs (48.6%) was observed than the number of cells whose nuclei were actually traversed by the 1-cGy dose of α particles (9.2%). The fraction of DSB-positive cells was greatly reduced after treatment with either lindane or DMSO. These results suggest that in situ visualization of DSBs can be used to assess radiation-induced extranuclear/extracellular effects soon after irradiation. Moreover, the in situ DSB assay may provide a means to evaluate the spatial effect on unirradiated cells that are located in the neighboring region of cells irradiated by α particles.