Succinic acid production from wheat using a biorefining strategy

The biosynthesis of succinic acid from wheat flour was investigated in a two-stage bio-process. In the first stage, wheat flour was converted into a generic microbial feedstock either by fungal fermentation alone or by combining fungal fermentation for enzyme and fungal bio-mass production with subsequent flour hydrolysis and fungal autolysis. In the second stage, the generic feedstock was converted into succinic acid by bacterial fermentation by Actinobacillus succinogenes. Direct fermentation of the generic feedstock produced by fungal fermentation alone resulted in a lower succinic acid production, probably due to the low glucose and nitrogen concentrations in the fungal broth filtrate. In the second feedstock production strategy, flour hydrolysis conducted by mixing fungal broth filtrate with wheat flour generated a glucose-rich stream, while the fungal bio-mass was subjected to autolysis for the production of a nutrient-rich stream. The possibility of replacing a commercial semi-defined medium by these two streams was investigated sequentially. A. succinogenes fermentation using only the wheat-derived feedstock resulted in a succinic acid concentration of almost 16 g l^–1 with an overall yield of 0.19 g succinic acid per g wheat flour. These results show that a wheat-based bio-refinery employing coupled fungal fermentation and subsequent flour hydrolysis and fungal autolysis can lead to a bacterial feedstock for the efficient production of succinic acid.     

Homologous expression of recombinant lignin peroxidase in Phanerochaete chrysosporium

The glyceraldehyde-3-phosphate dehydrogenase (gpd) promoter was used to drive expression of lip2, the gene encoding lignin peroxidase (LiP) isozyme H8, in primary metabolic cultures of Phanerochaete chrysosporium. The expression vector, pUGL, also contained the Schizophyllum commune ura1 gene as a selectable marker. pUGL was used to transform a P. chrysosporium Ura11 auxotroph to prototrophy. Ura+ transformants were screened for peroxidase activity in liquid cultures containing high-carbon and high-nitrogen medium. Recombinant LiP (rLiP) was secreted in active form by the transformants after 4 days of growth, whereas endogenous lip genes were not expressed under these conditions. Approximately 2 mg of homogeneous rLiP/liter was obtained after purification. The molecular mass, pI, and optical absorption spectrum of rLiPH8 were essentially identical to those of the wild-type LiPh8 (wt LiPH8), indicating that heme insertion, folding, and secretion functioned normally in the transformant. Steady-state and transient-state kinetic properties for the oxidation of veratryl alcohol between wtLiPH8 and rLiPH8 were also identical.     

桥小脑角区脑膜瘤显微外科手术17例分析

目的:探讨桥小脑角脑膜瘤的临床表现及相应的手术治疗方案,提高显微外科手术治疗效果.方法:回顾分析我院近5年来收治的17例桥小脑角脑膜瘤患者,均采用枕下乙状窦后手术入路.结果:本组肿瘤全切率为88.3%面神经和位听神经功能大部分保留,无死亡病例.结论:术前详细的检查和完善的手术方案制订对桥小脑角区脑膜瘤的手术治疗至关重要,显微外科手术是治疗桥小脑角区脑膜瘤安全有效的方法     

Comparative analyses of linkage maps and segregation distortion of two F₂ populations derived from japonica crossed with indica rice

To facilitate genetic research, we constructed two linkage maps by employing two F? populations derived from rice inter-subspecific crosses, japonica Tainung 67 (TNG67)/indica Taichung Sen 10 (TCS10) and japonica TNG67/indica Taichung Sen 17 (TCS17). We established linkage map lengths of 1481.6 cM and 1267.4 cM with average intervals of 13.8 cM and 14.4 cM by using 107 and 88 PCR markers for coverage of 88% of the rice genome in TNG67/TCS10 and TNG67/TCS17, respectively. The discrepancy in genetic maps in the two populations could be due to different cross combinations, crossing-over events, progeny numbers and/or markers. The most plausible explanation was segregation distortion; 18 markers (16.8%) distributed at nine regions of seven chromosomes and 10 markers (11.4%) at four regions of four chromosomes displayed severe segregation distortion (p < 0.01)in TNG67/TCS10 and TNG67/TCS17, respectively. All segregation-distorted markers in these two populations corresponded to reported reproductive barriers, either gametophytic or zygotic genes but not to hybrid breakdown genes. The observed recombination frequency, which was higher or lower than the intrinsic frequency, revealed the association of segregation distortion skewed to the same or different genotypes at the consecutive markers. The segregation distortion, possibly caused by reproductive barriers, affects the evaluation recombination frequencies and consequently the linkage analysis of QTLs and positional cloning.     

Nickel(II) and cobalt(II) complexes of hydroxyl-substituted triazamacrocyclic ligand as potential antitumor agents

The stability constants for the formation of nickel(II) and cobalt(II) complexes of the ligand [1,4,7]triazecan-9-ol (L) were presented. Antitumor activity of two complexes was reported. Nuclei of [NiL]-stimulated BEL-7402 cells clearly exhibited condensation and break down into chromatin clumps typical of apoptosis. Also it exhibited perturbation effects to cell cycle, and optimal induction of apoptosis was found by Flow-Cytometric analysis. But CoL complex did not exhibit introduction effects to BEL-7402 cells apoptosis; and could not perturb cell cycle. NiL and CuL complexes could cleave supercoiled DNA (pBR 322 DNA) to nicked and linear DNA, and DNA of cells treated with NiL or CuL complex was obviously damaged; while CoL complex only could cleave supercoiled DNA (pBR 322 DNA) to nicked DNA, and DNA of cells treated with CoL complex had no significant difference with control.     

Novel symmetric amphiphilic dendritic poly(L-lysine)-b-poly(L-lactide)-b-dendritic poly(L-lysine) with high plasmid DNA binding affinity as a biodegradable gene carrier

This study communicates the molecular design, preparation, and biological application of novel symmetric amphiphilic polycationic dendritic poly(L-lysine)-b-poly(L-lactide)-b-dendritic poly(L-lysine) D2-LLA15-D2 bearing two two-generation poly(L-lysine) PLL dendrons D2 and a central hydrophobic biodegradable poly(L-lactide) block LLA15. First, an amino-protected precursor of L1-OH was designed and synthesized and was further employed to prepare L1-LLA15 with an organic 4-(dimethylamino)-pyridine-mediated living-ring-opening polymerization of l-lactide. Subsequently, the hydroxy end-capped L1-LLA15 was coupled to synthesize a new triblock L1-LLA15-L1 with two one-generation amino-protected PLL dendrons L1. Furthermore, with a repeated trifluoroacetic-acid-mediated amino deprotection-protection cycle, new amphiphilic triblock D2-LLA15-D2 was successfully prepared. By means of NMR, mass spectrometry, and gel permeation chromatography, these synthetic precursors and final amphiphilic product were characterized to bear well-defined triblock structures. In addition, this synthesized amphiphilic triblock polycationic macromolecule was applied as a new polycationic plasmid DNA carrier, and its DNA binding affinity was examined via an agarose electrophoresis and a fluorescence titration assay along with two important references of hydrophilic dendritic D2-HEX-D2 and double-hydrophilic D2-PEG-4K-D2 bearing the same two D2 dendrons; much enhanced DNA binding affinity was interestingly revealed for the new amphiphilic structural D2-LLA15-D2. Moreover, the assembled polyplex microparticles of plasmid DNA/polycationic carrier were further analyzed by dynamic light scattering and transmission electron microscopy, indicating their averaged nanoparticle size around 150-200 nm. As for the cytotoxicity of the new D2-LLA15-D2, MTT assays were conducted with a human hepatocellular carcinoma cell line (SMMC-7721), indicating a very low cytotoxicity as compared with commercial linear PLL-23K and PEI-2K, and a DNase I degradation of the assembled polyplex particles was also done in the HBS buffer solution to evaluate their stabilities. Finally, employing the new amphiphilic D2-LLA15-D2 as gene carrier, in vitro gene transfection experiments were conducted with the SMMC-7721 cell line, indicating a transfection efficiency increase of at least 10 times higher than that of the naked plasmid DNA under a N/P charge ratio of 10. Therefore, these interesting results may provide a new possible way to construct efficient polycationic macromolecular gene carriers with low toxicity and less expensive low-generation PLL dendrons.     

Prediction of Protein-Protein Interactions Using Protein Signature Profiling

Protein domains are conserved and functionally independent structures that play an important role in interactions among related proteins. Domain-domain inter- actions have been recently used to predict protein-protein interactions (PPI). In general, the interaction probability of a pair of domains is scored using a trained scoring function. Satisfying a threshold, the protein pairs carrying those domains are regarded as "interacting". In this study, the signature contents of proteins were utilized to predict PPI pairs in Saccharomyces cerevisiae, Caenorhabditis ele- gans, and Homo sapiens. Similarity between protein signature patterns was scored and PPI predictions were drawn based on the binary similarity scoring function. Results show that the true positive rate of prediction by the proposed approach is approximately 32% higher than that using the maximum likelihood estimation method when compared with a test set, resulting in 22% increase in the area un- der the receiver operating characteristic (ROC) curve. When proteins containing one or two signatures were removed, the sensitivity of the predicted PPI pairs in- creased significantly. The predicted PPI pairs are on average 11 times more likely to interact than the random selection at a confidence level of 0.95, and on aver- age 4 times better than those predicted by either phylogenetic profiling or gene expression profiling.