肿瘤坏死因子－α（TNF－α）及白细胞介素1β（IL1－β）对胶质增生的影响及机理

本文利用小鼠大脑机械损伤模型及体外培养的胶质细胞,采用同位素渗入法观察了细胞介素及其抗体对胶质细胞增生的影响。结果表明：体外培养时ＴＮＦ－α在浓度为１０～２００ｕ／ｍｌ培养液时均能促进胶质细胞增生（Ｐ＜０．０５）,ＩＬ１－β在浓度为５～２００ｕ／ｍｌ培养液时能促进胶质细胞增生,ＴＮＦ－α＋ＩＬ１－β其促进胶质细胞增生作用更强烈,ＴＮＦ－α抗体能完全阻断ＴＮＦ－α的促增生作用,部分阻断ＴＮＦ－α＋ＩＬ１－β的促增生作用。在体实验时,ＩＬ１－β及ＴＮＦ－α的作用与离体时相似,ＩＬ１－β及ＴＮＦ－α亦能促进胶质细胞增生,二者共同作用时促细胞增生作用更强。以上结果提示,外源性ＴＮＦ－α及ＩＬ１－β能促进中枢神经损伤后胶质细胞增生且具有协同作用。     

Comparison of the expression of Bacillus thuringiensis full-length and N-terminally truncated vip3A gene in Escherichia coli

AIMS: Studies were performed to demonstrate the function of the putative signal peptide of Vip3A proteins in Escherichia coli. METHODS AND RESULTS: The full-length vip3A-S184 gene was isolated from a soil-isolated Bacillus thuringiensis, and the vip3AdeltaN was constructed by deleting 81 nucleotides at the 5'-terminus of vip3A-S184. Both were transformed and expressed in E. coli. About 19.2% of Vip3A-S184 proteins secreted soluble proteins and others formed inclusion bodies in the periplasmic space. In contrast, the Vip3AdeltaN was insoluble and formed inclusion bodies in the cytoplasm. Bioassay indicated that Vip3A-S184 showed different toxicity against Spodoptera exigua, Helicoverpa armigera and S. litura, but Vip3AdeltaN showed no toxicity to either of them because of the deletion of the first 27 amino acids at the N-terminus. CONCLUSIONS: The results suggest that the deleted N-terminal sequences were essential for the secretion of Vip3A-S184 protein in E. coli and might be required for toxicity. SIGNIFICANCE AND IMPACT OF THE STUDY: The function of the putative signal peptide of Vip3A protein in E. coli was investigated. These would be helpful to make clear the unknown secretion pathway of Vip3A protein in B. thuringiensis and determine the receptor-binding domain or toxic fragment of Vip3A-S184 protein.     

Biodegradation and detoxification of nicotine in tobacco solid waste by a Pseudomonas sp.

A Pseudomonas sp. grew with nicotine optimally 3 g l^–1 and at 30 °C and pH 7. Nicotine was fully degraded within 10 h. The resting cells degraded nicotine in tobacco solid waste completely within 6 h in 0.02 m sodium phosphate buffer (pH 7) at maximally 56 mg nicotine h^–1 g dry cell^–1.     

Identification of genes necessary for jinggangmycin biosynthesis from Streptomyces hygroscopicus 10-22

A series of large chromosomal deletions in Streptomyces hygroscopicus 10-22 were aligned on the physical map of the wild-type strain and the mutants were assessed for their ability to produce the aminocyclitol antibiotic 5102-I (jinggangmycin). Twenty-eight mutants were blocked for jinggangmycin production and all of them were found to lack a 300 kb AseI-F fragment of the wild-type chromosome. An ordered cosmid library of the 300 kb AseI-F fragment was made and one of the cosmids conferred jinggangmycin productivity to Streptomyces lividans ZX1. Three of the overlapping cosmids (18G7, 5H3 and 9A2) also hybridized to the valA gene of the validamycin pathway from S. hygroscopicus 5008 as a probe. This gene resembles acbC from Actinoplanes sp. 50/110, which encodes a C7-cyclitol synthase that catalyses the transformation of sedoheptulose 7-phosphate into 2-5-epi-valiolone for acarbose biosynthesis. The valA/acbC-homolog (orf1) of S. hygroscopicus 10-22 was shown to be essential for jinggangmycin biosynthesis as an engineered mutant with a specific in-frame deletion removing a 609 bp sequence internal to orf1 completely abolished jinggangmycin production and the corresponding knock-out mutant (JXH4) could be complemented for jinggangmycin production by the introduction of an orf1-containing construct. Concurrently, the identities of the genes common to S. hygroscopicus strains 10-22 and 5008 prompted a comparison of the chemical structures of jinggangmycin and validamycin, which led to a clear demonstration that they are identical.The first two authors contributed equally to this study.     

Systematic Artifacts in Support Vector Regression-Based Compound Potency Prediction Revealed by Statistical and Activity Landscape Analysis

Support vector machines are a popular machine learning method for many classification tasks in biology and chemistry. In addition, the support vector regression (SVR) variant is widely used for numerical property predictions. In chemoinformatics and pharmaceutical research, SVR has become the probably most popular approach for modeling of non-linear structure-activity relationships (SARs) and predicting compound potency values. Herein, we have systematically generated and analyzed SVR prediction models for a variety of compound data sets with different SAR characteristics. Although these SVR models were accurate on the basis of global prediction statistics and not prone to overfitting, they were found to consistently mispredict highly potent compounds. Hence, in regions of local SAR discontinuity, SVR prediction models displayed clear limitations. Compared to observed activity landscapes of compound data sets, landscapes generated on the basis of SVR potency predictions were partly flattened and activity cliff information was lost. Taken together, these findings have implications for practical SVR applications. In particular, prospective SVR-based potency predictions should be considered with caution because artificially low predictions are very likely for highly potent candidate compounds, the most important prediction targets.     

Carriage of Neisseria meningitidis and Neisseria lactamica in northern Greece

In response to an increase in the number of cases of invasive meningococcal disease (IMD) in northern regions of Greece, a survey was carried out to determine if there was an increase in carriage of Neisseria meningitidis, particularly in areas where there have been increases in immigrant populations from neighbouring countries. The second objective was to determine if there was an increase in the serogroup C:2a:P1.5,2 a phenotype associated with recent outbreaks or changes in antibiotic sensitivities. As carriage of Neisseria lactamica is associated with development of natural immunity to IMD, the third objective was to determine the carriage rate of N. lactamica in this population. Among 3167 individuals tested, meningococci were isolated from 334 (10.5%). Compared with our previous studies, the proportion of meningococcal carriers was significantly increased among children in secondary education (11.3%) (chi2=9.67, P<0.005) and military recruits (37.4%) (chi2=21.11, P<0.000). Only 5/334 (1.5%) isolates expressed the phenotype associated with the increase in IMD in Greece. N. lactamica was isolated from 146/3167 (4.6%) participants. It was isolated from 71/987 (7.2%) children attending primary or nursery schools; however, the highest proportion of carriers (11.3%) was found in the boarding school for young Albanian men. In the 21-59-year age range, the majority of N. lactamica isolates (22/25, 88%) were from women, probably due to closer or more prolonged contact with children in the primary school age range. Smoking was significantly associated with isolation of meningococci from men but not from women. Penicillin-insensitive strains (25/334, 7.5%) were identified in all four regions examined; the majority (14/25, 56%) were obtained from military personnel. We conclude that there was a higher proportion of carriers in the population of northern Greece; however, the increase in carriage rate was not associated with the influx of immigrants from neighbouring countries, and there was not a higher incidence of the C:2a:P1.5,2 strain responsible for increased disease activity in Greece in either the immigrant or local populations.     

Expression of Discoidin Domain Receptor 2 (DDR2) Extracellular Domain in Pichia Pastoris and Functional Analysis in Synovial Fibroblasts and NIT3T3 Cells

Discoidin domain receptor 2 (DDR2) is a kind of protein tyrosine kinases associated with cell proliferation and tumor metastasis, and collagen, identified as a ligand for DDR2, up-regulates matrix metallloproteinase 1 (MMP-1) and MMP-2 expression in cellular matrix. To investigate the roles of DDR2 in destruction of cartilage in rheumatoid arthritis (RA) and tumor metastasis, we tried to express extracellular domain of DDR2 fused with a His tag to increase protein solubility and facilitate purification (without signal peptide and transmembrane domain, designated DR) in Pichia pastoris, purify the expressed protein, and characterize its function, for purpose of future application as a specific DDR2 antagonist. Two clones of relative high expression of His-DR were obtained, After purification by a Ni-NTA (nitric-tri-acetic acid) chromatographic column, soluble fused His-DR over 90% purity were obtained. Competitive binding inhibition assay demonstrated that expressed His-DR could block the binding of DDR2 and natural DDR2 receptors on NIT3T3 and synovial cell surfaces. Results of RT-PCR, Western blotting, and gelatinase zymography showed that His-DR was capable of inhibiting MMP-1 and MMP-2 secretion from NIT3T3 cells and RA synoviocytes stimulated by collagen II. For MMP-1, the inhibitory effect was displayed at the levels of mRNA and protein, whereas for MMP-2 it was demonstrated at the level of protein physiological activity. All these findings suggested that the fused expressed His-DR inhibited the activity of natural DDR2, and relevant MMP-1 and MMP-2 expression in synoviocytes and NIH3T3 cells provoked by collagen II. Wei Zhang and Tianbing Ding equally contributed to this work.     

Growth Medium and Phosphorus Supply Affect Cluster Root Formation and Citrate Exudation by Lupinus albus Grown in a Sand/Solution Split-Root System

We examined cluster root formation and root exudation by white lupin (Lupinus albus L. cv. Kiev Mutant) in response to growth medium and phosphorus supply in a sand/solution split-root system. The split-root system consisted of a nutrient solution compartment and a siliceous sand compartment. Phosphorus was applied at 1 (low-P plants) or 50 (high-P plants) μM as KH₂PO₄ to the solution compartment and at 10, 50 or 250 mg P kg⁻¹ as hydroxyapatite (Ca-P) to the sand compartment. In contrast to the high-P plants, P concentration and P uptake in the low-P plants increased with increasing P supply to the sand compartment. The NaHCO₃-extractable P was lower in the rhizosphere of the low-P plants than the high-P ones. The proton extrusion rate by the solution-grown roots of the low-P plants was higher than that of the high-P plants at the early growth stage. For the low-P plants, the proportion of dry root biomass allocated to cluster roots was higher in the solution compartment than that in the sand compartment. The citrate exudation increased in the sand compartment and decreased in the solution compartment with time, showing a lack of synchronization in citrate exudation by two root halves grown in different media. The cluster root proportion and citrate exudation in both compartments decreased with increasing shoot P concentration. An additional experiment with no P added to either root compartment showed that the proportion of cluster roots was about 9% lower in the sand than solution compartments. The results suggest that cluster root formation and citrate exudation can be significantly affected by the root growth medium in addition to being regulated by shoot P status. More P can be exploited from sparingly available Ca-P by the low-P plants than the high-P ones due to greater citrate exudation under P deficiency.     

Gestation length in rhesus macaques (Macaca mulatta)

We describe some of the sources of variation in gestation length among rhesus macaques. the data were obtained from the timed-mating breeding program at the California Regional Primate Research Center (CRPRC). Information about approximately 700 pregnancies that resulted in spontaneous vaginal deliveries of liveborn young is presented. The average length of these pregnancies was 166.5 days. In this population, older females with higher parities had significantly longer pregnancies and significantly heavier infants than other females did. Other factors, including infant sex, month of conception, maternal reproductive history, and paternal identity, had no consistent effect upon gestation length.