川芎嗪对Aβ25-35诱导体外大鼠海马神经元细胞凋亡的影响

本文通过Aβ25-35诱导体外原代培养的SD乳大鼠海马神经元,建立Aβ毒性损伤细胞模型,结合AnnexinV-FITC/PI荧光双染法流式细胞术、MTT比色法、实时荧光定量PCR及Western blot方法检测川芎嗪(tetrameth-ylpyrazine,TMP)对原代培养的海马神经元细胞活性、早期凋亡率和Bax、Bcl-2基因表达的影响。结果显示川芎嗪高、中剂量可明显增强细胞活性,增加神经元细胞的存活率(P<0.01),可显著抑制海马神经元细胞早期凋亡(P<0.01),抑制凋亡蛋白Bax的表达(P<0.01),增强抗凋亡蛋白bcl-2的表达(P<0.01)。川芎嗪可通过调节Bax/Bcl-2平衡抵抗Aβ25-35诱导的海马神经元凋亡,降低Aβ的神经元毒性,对海马神经元损伤有明显的保护作用。     

Cloning and Expression of the Exo-β-D-1,3-glucanase Gene (exgS) from Aspergillus saitoi

A gene of exo-1,3-β-D-glucanase (exgS) was cloned from a koji mold, Aspergillus saitoi, genomic DNA using PCR. The exgS has an ORF comprising 2832 bp, which contains one intron of 45 bp, and encodes 945 amino acids. The deduced amino acid sequences showed that the ExgS has a non-homologous linker region consisting of 180 amino acids, which encompassed highly conserved regions observed in Exg homologues from filamentous fungi. A recombinant protein (ExgS) has been recovered from the cultural filtrate of an Aspergillus oryzae strain that carried an expression vector containing full length of the exgS. The N-terminal amino acid sequences of the recombinant exo-1,3-β-D-glucanase (ExgS) were identical to that of native ExgS from A. saitoi.     

Cloning and Expression of an Endo-1,6-β-D-glucanase Gene (neg1) from Neurospora crassa

A gene (neg1) encoding an endo-1,6-β-D-glucanase from Neurospora crassa was cloned. The putative neg1 was 1443-bp long and encoded a mature endo-1,6-β-D-glucanase protein of 463 amino acids and signal peptide of 17 amino acids. The purified recombinant protein (Neg1) obtained from Escherichia coli showed 1,6-β-D-glucanase activity. No genes similar in sequence were found in yeasts and fungi.     

Extension of the Ring Oxygen Helicity Rule to Phenyl and p-Nitrophenyl Glycopyranosides

The Cotton effect below 200 nm was first studied in aromatic glycopyranosides with our new technique of optical rotatory dispersion (ORD). The phenyl and p-nitrophenyl α- and β-d-glycopyranosides showed a strong Cotton effect at around 180 nm which practically governed the optical rotations in the visible wavelength region. The rotational strength and sign of this Cotton effect were shown to reflect the anomeric configurations and conformations, which led to an extension of the ring oxygen helicity rule for alkyl and alkyl 1-thioglycosides to aromatic glycopyranosides.     

Preparation of Optically Pure cis-2,4-Dimethyl-l-cyclohexanones,the Key Intermediates in Cycloheximide Synthesis,Using Microbial Resolution

Asymmetric hydrolysis of acetate (10) of (±)-t-2,t-4-dimethyl-r-l-cyclohexanol with Bacillus subtilis var. niger gave (?)-(lS,2S,4S)-2,4-dimethyl-l-cyclohexanol (6a) and (+)-(1R,2R,4R)-acetate (10b) with high optical purities. Optically pure (?) and (+)-alcohols (6a and 6b) were prepared via corresponding 3,5-dinitrobenzoates. Oxidation of alcohols (6a and 6b) with chromic acid gave optically pure (?)-(2S,4S) and (+)-(2R,4R)-2,4-dimethyl-l-cyclohexanones (2a and 2b), respectively.     

Simple Determination of Trace Amounts of Anionic Surfactants in River Water by Spectrophotometry Combined with Solid-phase Extraction

A simple and sensitive specrophotometric method combined with solid-phase extraction (SPE) for the simultaneous determination of sodium linear-dodecylbenzenesulfonate (DBS) and sodium dodecyl sulfate (SDS) is described. The C2 (ethyl group bonded silicagel) cartridge could be repeatedly used more than 500 times for SPE, and it enabled the anionic surfactants to be concentrated by 50-fold. The calibration graph for DBS was linear in the range from 1.6×10^?8 M to 5.0×10^?7 M and for SDS from 2.0×10^?9 M to 3.0×10^?7 M. The relative standard deviation (n=5) for 5.0×10^?7 M DBS was 3.1% and for 2.5×10^?7 M SDS was 1.7%. The proposed method was applied to the simultaneous determination of DBS and SDS in river-water samples.     

Estimation of Aeration and Agitation Conditions in Respect to Oxygen Supply and Ventilation

In inosine fermentation, the yield of the product was closely related to the partial pressure of carbon dioxide in the culture system rather than the bicarbonate ion concentration in the culture liquid. The inhibitory effect of carbon dioxide was restored by the methods of reducing the partial pressure of carbon dioxide lower than a certain level. Both ventilation and chemical absorption were applicable for the restoration of the carbon dioxide inhibition, but ventilation had great advantages over the other method from an industrial view-point. In the estimation of aeration-agitation conditions for the scale-up of submerged fermentation in which carbon dioxide was inhibitory, the rate of aeration was to be established to make sufficient ventilation and overcome this inhibition. A scheme for the procedure for the estimation of aeration-agitation conditions under the consideration of influences of carbon dioxide on submerged fermentation was proposed in this paper.     

Cell-Bound Serine Proteinase of Sporulating Cells of Bacillus subtilis

2-Deuterio-2-cyclohexen-l-one, 3-deuterio-2-cyclohexen-l-one and 2-methyl-2-cyclohexen-1-one were reduced by Clostridium La 1 giving a single bioconversion product resulting from reduction of the carbon-carbon double bond. Stereochemistry of the reaction was studied.     

Purification and Properties of UDP-galactose 4-Epimerase from Bifidobacterium bifidum

UDP-galactose 4-epimerase (EC 5.1.3.2) was purified to a homogeneous state from Bifidobacterium bifidutn grown on a glucose medium. The molecular weight was estimated to be about 90,000. The purified enzyme was very stable and 60 % of its initial activity survived three months of storage at 4°C even at a low protein concentration (0.2 mg/ml). The optimum pH was 9.0, and the Km values for UDP-galactose and UDP-glucose were 5.4 × 10^-4 M and 1.4×10 ^-3 M. UDP was a competitive inhibitor. The enzyme activity was stimulated by various sugar phosphates, but was slightly inhibited by fructose 1,6-diphosphate (FDP). A high concentration of galactose or glucose, which had no effect by itself, inhibited the activity in combination with UMP. The inhibition by FDP was also enhanced by combination with UMP.