Chiral discrimination and interaction mechanism between enantiomers and serum albumins

The chiral discrimination studies of biological system are theoretically and practically significant for the development of chiral drugs and life science. Our work has embarked upon the interaction between serum albumin (SA) (including human SA and bovine SA), R,S‐1‐(4‐methoxyphenyl)ethylamine, and R,S‐1‐(3‐methoxyphenyl)ethylamine. The formation of intermediate transition state, binding sites, and chiral discrimination ability can be investigated by ultraviolet‐visible spectra and fluorescence spectra. Moreover, both the changes of hydrophobic microenvironment and energy transfer can be detected by synchronous fluorescence spectra and fluorescence lifetime. Copyright © 2013 John Wiley & Sons, Ltd.     

Biodegradation of high concentration of nitrobenzene by Pseudomonas corrugata embedded in peat-phosphate esterified polyvinyl alcohol

Efficiency on biodegradation of high concentration of nitrobenzene (NB) by peat-phosphate esterified polyvinyl alcohol-embedded NB-degrading bacteria Pseudomonas corrugata was conducted compared to free bacteria cells. Its biodegradation kinetics, reuse ability, degradation effect in the absence of the essential element needed for the growth of bacteria and degradation efficiency of the raw water from the contaminated site were also invested. Results show that the degradation rate when the concentration of NB was at 600, 750, and 900 mg/L reached 91.02, 83.23, and 55.9 %, which was higher than that observed in free bacteria at the same concentration levels. Biodegradation kinetics of the material could be well described by first- and zero-order kinetics when the concentration of NB was at 300, 450 mg/L and 600, 750, 900 mg/L, respectively. Stable degradation activity (stayed at a level of approximately 70 %) was displayed during the 11th repeat-batch experiment. The affect of absence of phosphorus in the medium can be abated ascribed to the addition of peat, which contributes with organic matter and other elements such as nitrogen and phosphorus necessary to maintain metabolically active the microorganisms. Effective biodegradation of the raw water from the experimental site revealed that the material can be a potential candidate for treating NB-contaminated wastewater in the practical setting.     

Inhibition of Fe-induced colon oxidative stress by lactobacilli in mice

Iron (Fe) can promote hydrogen peroxide (H₂O₂) and hydroxyl radical generation in the colonic surface and promote growth of Fe-dependent bacteria. Some Lactobacillus strains are resistant to oxygen free-radicals, allowing them to survive in a Fe-modulated mucosal environment and influence colon microbial ecology and redox state. Here, we investigated the capacity of lactobacilli with different antioxidant abilities to modify the bacterial profile and prevent oxidative stress in the colon of Fe-overloaded mice. Survival time of Lactobacillus rhamnosus LGG (LGG) in the presence of H₂O₂ and hydroxyl radical was significantly longer compared with the mid- and non-antioxidative strains, Lactobacillus paracasei Fn032 and Lactobacillus plantarum Fn001, respectively. Different Lactobacillus strains are specific in free-radical scavenging activities of their cell-free extracts, which increased to varying extent depending on strains when bacteria were exposed to simulated gastric and pancreatic juice. Fe-overloaded mice showed increased colonic luminal ferrous Fe content, Enterococcus and Escherichia coli concentrations, mucosal malondialdehyde and free-radicals, and decreased mucosal total antioxidative capacity and oxidative enzymatic activity. Translocation of endotoxin to the liver was also significantly increased (P < 0.05). Lactobacilli inhibited ferrous Fe accumulation, especially in LGG and Fn032. LGG significantly inhibited the increase of colonic mucosal free-radicals and malondialdehyde content (P < 0.05). Fn032 only inhibited malondialdehyde (P < 0.05). LGG and Fn032 significantly inhibited increases in colonic Enterococcus (P < 0.05). Fn001 showed no significant antioxidative ability in vivo. The difference of these effects in vivo were well agreed with scavenging activities against reactive oxygen species (ROS) of simulated gastrointestinals fluid pretreated cells in vitro. In conclusion, ROS scavenging activities was essential for Lactobacillus to prevent oxidative stress in vivo and inhibition of ROS-producing bacterial growth and mucosal barrier injury.     

Seed rain and its relationship with above-ground vegetation of degraded Kobresia meadows

Seed rain is a crucial element in vegetation regeneration, but has been rarely studied in high altitude regions, particularly degraded Kobresia meadow. Weed infestation is a distinctive feature of pasture degradation in Kobresia meadows on the Tibetan plateau, the ecological mechanism of which is closely related with vegetation’s seed rain. In this paper we assess the effect of vegetation degradation on seed rain and consider its implication for restoration of degraded Kobresia meadows in the headwater area of Yellow river, through analysis of seed species composition, number of seeds landing per m² of soil surface, and their relationship with above ground vegetation. Vegetation degradation had an impact on the species composition and numbers of seeds in seed rain and their relationship with above-ground vegetation. Within the un-degraded meadow, which provided a closed vegetation cover, 35 % of the seed rain was of sedge and gramineae species. However, within the degraded meadows, as the extent of degradation increased, so the total number of seeds m^?2 increased, with those derived from sedge and gramineae species forming a declining proportion of the total. Degradation of Kobresia meadow on the Tibetan plateau is exacerbated by the seed input of weed species (such as Oxytropis ochrocephala, Carum carvi, Aconitum pendulum, Pedicularis kansuensis in this study). Therefore, a major priority for the restoration of such degraded meadows should be the elimination of these weeds from the above ground vegetation by human intervention.     

Molecular cloning and sequence analysis of methionine adenosyltransferase from the economic seaweed Undaria pinnatifida

The methionine adenosyltransferase gene (MAT) had been isolated from an economic seaweed Undaria pinnatifida by PCR using degenerate primers. The cDNA was 1,491 bp in length with an open reading frame of 1,194 nucleotides, encoding a deduced protein of 397 amino acids. The protein had a predicted molecular weight of 43.2 kDa, and the isoelectric point was 5.244. The sequence contains a 92 bp 5′-untranslated region (UTR) and a 205 bp 3′-UTR. The methionine adenosyltransferase (MAT) sequence of U. pinnatifida (UpMAT) shared 68–92 % identities with the previous published MAT sequences of other species. Phylogenetic analysis indicated that the phylogenetic relationship of UpMAT with some other seaweeds was closer than with those of higher plants. Under different stress conditions, the relative mRNA expression levels of the MAT of U. pinnatifida (UpMAT) were measured by real-time quantitative PCR, and the results demonstrated that the UpMAT might help to protect the alga against various abiotic stresses.     

Genetic Structure and Aggressiveness of Rhizoctonia solani AG1‐IA,the Cause of Sheath Blight of Rice in Southern China

One hundred and eighty isolates of Rhizoctonia solani AG1‐IA, the causal agent of rice sheath blight, were obtained from six locations in southern China. The genetic structure of R. solani isolates was investigated using random amplified polymorphic DNA (RAPD) markers, and a considerable genetic variation among R. solani isolates was observed. Most of the genetic diversity was distributed within populations, rather than among them. The distribution pattern of the genetic variation of R. solani appears to be the result of high gene flow (Nm) and low‐genetic differentiation among populations. The aggressiveness of R. solani was visually assessed by rice seedlings of five different cultivars in the glasshouse. All isolates tested were found to induce significantly different levels of disease severity, reflecting considerable variation in aggressiveness. The isolates were divided into highly virulent, moderately virulent and weakly virulent groups, and the moderately virulent isolates were dominant in R. solani population. No significant correlation was observed among the genetic similarity, pathogenic aggressiveness and geographical origins of the isolates. Information obtained from this study may be useful for breeding for improved resistance to sheath blight.     

基于rbcL和matK序列探讨马鞭草科部分植物的系统学位置

为探究适用于马鞭草科植物的DNA条形码及该类群的系统分类关系,对豆腐柴(Premna microphylla)的叶绿体基因ycf6-psbM、trnV-atpE、rbcL、trnL-F、psbM-trnD、atpB-rbcL、trnC-ycf6、trnH-psbA、rpl36-infA-rps8和核基因ITS序列进行了PCR扩增和测序,结果表明仅rbcL、trnl-F、trnH-psbA序列的PCR扩增以及测序效果较好,而ITS不能得到明显的扩增条带,ycf6-psbM不能成功测序,其它序列存在有部分双峰或噪值高等问题。根据DNA条形码标准,rbcL序列是所有测试条码中相对最适合的。应用rbcL和matK序列对马鞭草科(Verbenaceae)豆腐柴属、牡荆属(Vitex L.)、马鞭草属(Verbena L.)和大青属(Clerodendrum L.)等4属与唇形科宝盖草属(Lamium L.)、水苏属(Stachys L.)、鼠尾草属(Salvia L.)和香科科属(Teucrium L.)等4属的分类和系统发育关系进行分析,以紫草科Lithospermum multiflorum L.为外群,最大简约法对2个片段的单独和联合矩阵分别构建系统发育树。豆腐柴属和大青属应从马鞭草科划入唇形科,马鞭草属仍归于马鞭草科,而牡荆属的系统学位置还需更多的证据。     

Genome-wide analysis of Nilaparvata lugens nymphal responses to high-density and low-quality rice hosts

The brown planthopper （BPH） Nilaparvata lugens is an economically impor- tant pest on rice plants. In this study, the higher population density and yellow-ripe stage of rice plants were used to construct adverse survival conditions （ASC） against BPH nymphs. Simultaneously, the low population density and tillering stage of rice plants were used to establish a suitable survival condition （SSC） as a control. Solexa/Illumina sequencing was used to identify genes of BPH nymphs responding to ASC. Significantly longer duration development of BPH nymphs and significantly lower brachypterous ratio of BPH adults were observed by ASC compared with SSC. A total of 2 544 differentially expressed genes （DEGs） were obtained and analyzed by BLASTx, Gene Ontology and KEGG Orthology. Gene ontology analysis revealed that the DEGs were mainly involved in categories of cell, cell part, cellular process, binding, catalytic, organelle and metabolic processes. 1138 DEGs having enzyme commission numbers were assigned to different metabolic pathways. The largest clusters were neurodegenerative diseases （137, 12.0%）, followed by carbohy- drate metabolism （113, 9.9%）, amino acid metabolism （94, 8.3%）, nucleotide metabolism （76, 6.7%）, energy metabolism （64, 5.6%）, translation （60, 5.3%）, lipid metabolism （58, 5.1%）, and folding, sorting and degradation （52, 4.6%）. Expressing profile of 11 DEGs during eight nymphal developmental stages of BPH were analyzed by quantitative real- time polymerase chain reaction. The 11 genes exhibited differential expression between ASC and SSC during at least one developmental stage. The DEGs identified in this study provide molecular proof of how BPH reconfigures its gene expression profile to adapt to overcrowding and low-quality hosts.     

ICU内侵袭性真菌感染临床分析及药敏情况

目的 分析重症加强病房(ICU)内侵袭性真菌感染的临床状况、病原菌菌群分布及耐药情况,为临床治疗及减少真菌感染提供参考依据.方法 回顾性分析3年来真菌培养阳性住院患者病例资料,从感染部位、菌种分布、真菌耐药情况等方面进行分析.结果 ICU中侵袭性真菌感染发生率为8.6％;尿液、痰液和血液分别为36.6％、28.8％和11.8％;真菌感染以假丝酵母菌为主要菌属(94.3％),白色假丝酵母菌占51.6％,是感染主要菌种;5种常见抗真菌药物敏感率最高的是两性霉素平均为99.8％,其次为伏立康唑;光滑念珠菌及热带念珠菌耐药比较严重,氟康唑(FLU)的敏感率分别为41.1％、17.6％,伊曲康唑的敏感性分别为6.1％、35.3％.结论 白色假丝酵母菌是ICU侵袭性真菌感染感染的主要病原菌;两性霉素及伏立康唑对5种念珠菌有较好的抗菌活性.