中药固真方对一些与细胞增殖有关基因表达的影响

 中药固真方对一些与细胞增殖有关基因表达的影响姚明忠,顾文聪,丁卫,韩志芬,杜国光（上海中医药大学生物化学教研室,上海２０００３２）（北京医科大学生物化学与分子生物学系,北京１０００８３）中药固真方（ＶＲＦ）具有补肾益精、延缓衰老的作用［１］．能提高成...     

A gene encoding a truncated large subunit of Rubisco is transcribed and salt-inducible in rice

Using the rice salt-tolerant mutant 20 as material, a cDNA library was constructed and two salt-inducible clones, SIR5.5 and SIR8.1, were isolated by differential screening. Homology analysis revealed that the two clones together constituted a chimeric rbcL which encoded a truncated large subunit of Rubisco with 337 amino-acids, plus 64 amino-acids of unknown origin. The expressions of both the normal and the chimeric locus appeared to be developmentally regulated and salt-inducible in shoots of the salt-tolerant mutant 20 and its original variety 77–170. In roots, their expressions were salt-inducible in the salt-tolerant mutant 20 whereas no, or only premature, forms were present in the salt-treated original variety 77–170. Higher concentrations of salt reduced the expressions of both normal rbcL and the chimeric locus. ABA showed no effect on their expression.     

Transformation and allelic replacement in Francisella spp.

We describe methods for transposon mutagenesis and allelic replacement in the facultative intracellular pathogen Francisella. Recombinant clones were constructed by insertion of partially cut F. tularensis or F. novicida DNA into pUC19 and then mutagenized with a mini-Tn10-Km transposon. F. novicida could be transformed with these plasmids either by a chemical transformation method or by electroporation, whereas F. tularensis could be transformed only by electroporation. Transformation of F. tularensis by electroporation was enhanced in the absence of the capsule. Southern blot analysis showed that the KmR marker was rescued either by integration of the plasmid into the Francisella chromosome or by allelic replacement. Allelic replacement was found to be the mechanism underlying a site-specific mutation affecting FopA, an outer-membrane protein of Francisella. F. novicida could also be transformed with chromosomal DNA carrying the KmR marker and the transformation frequency obtained using chromosomal DNA was generally greater than that obtained using plasmid DNA. F. novicida was also transformed by an IncQ plasmid containing an F. novicida DNA insert, which replicated autonomously in this host.     

Microcarrier culture of bowes melanoma cells in serum-free medium with Human plasma fraction IV-4+ V

Bowes melanoma cells were cultivated successfully in a serum-free medium which was constructed by the concept of maximum retention of proteins from fractionated human plasma having growth stimulatory activities. The cells could be cultivated in the serum-free medium without any adaptation period. The major serum-free component of the medium was the fraction IV-4 + V of the Cohn fractionation process of human plasma. Approximately six times increase of tissue-type plasminogen activator (t-PA) activity as compared with that in serum-free medium even though the cell growth was much slower. In addition, the growth stimulatory activities of thrombin and fibronectin were investigated during the cultivation of Bowes melanoma cells in this serum-free medium. These proteins contributed significantly to the enhanced growth of cells by reducing doubling time to 25 and 35 h as compared with 55 h in the serum-free medium without them. Especially, fibronectin supported cells to propagate near to the maximum cell density achieved in the medium with 10% FBS.     

Comparison of different biological indices for the assessment of river quality: application to the upper river Moselle (France)

The aim of our study was to assess the water quality of the upper Moselle river by using biological indices. Simultaneous physico-chemical surveys were also undertaken from May 1999 to April 2000. Twelve sampling sites were selected in order to provide a wide range of potential pollution. Chemical analysis did not reveal any major problem of pollution. However a lower water quality resulting from domestic pollution was established for some sampling sites. A biological monitoring combining both macroinvertebrates and macrophytes was performed. Biological indices based on plant community structure and macrophyte composition were not pertinent tools, whereas simple indices based on taxonomic richness of particular groups of macroinvertebrates were strongly correlated with several chemical parameters, showing that such simple biological variables should represent powerful indicators of ecosystem degradation.     

Evaluation of a high throughput toxicity biosensor and comparison with a Daphnia magna bioassay

A high throughput toxicity biosensor has been designed and constructed using recombinant Escherichia coli cells, containing stress specific promoters (recA, fabA, or katG) or constitutive promoters (lac) fused to luciferase genes originating from Vibrio fisheri. These genetically engineered cells were immobilized in 96 well plates. By optimizing cell immobilization conditions and the strains' response specificity to toxic chemicals, bioluminescent outputs decreased or increased dose-dependently upon adding test chemicals. However, to date the toxicity data obtained using this biosensor have not been compared with the results of other toxicity tests. Phenolics were chosen to evaluate the correlation between the LD50 and the EC50 (GC2) or EC120 (DPD2540) of Daphnia magna and E. coli, respectively. Toxicity data obtained from constitutive strains by bioluminescent level decrements were compared with the results from D. magna as a standard. LD50 values were used as parameters of D. magna toxicity and EC50 of EC120 values were used for the immobilized biosensor. In the DPD2540 test, phenolics, membrane damaging toxic chemicals, for testing immobilized stress specific bacterial strains trigger dose-dependant bioluminescence increase within specific concentration. Although the stress specific responsiveness from the strains could not be compared with D. magna's LD50 values, these responses offer additional information, such as upon the mode of toxic action in the sample, in addition to the cellular toxicity results as indicated by the EC50. This novel high throughput toxicity biosensor can be implemented to investigate the toxicity of any other soluble materials, and can be used as a standardization tool for the evaluation of toxicity.     

Cholinergic Control of Nerve Growth Factor in Adult Rats: Evidence from Cortical Cholinergic Deafferentation and Chronic Drug Treatment

Abstract: It is well documented that nerve growth factor (NGF) plays an important role in maintaining functions of cholinergic basal forebrain neurons. In the present study, we tested the hypothesis that cholinergic activity controls NGF levels in cholinoceptive neurons of the cerebral cortex and hippocampus. To address that question, we used both cholinergic deafferentation of cerebral cortex and hippocampus by cholinergic immunolesion with 192IgG-saporin and chronic pharmacological treatment of sham-treated and immunolesioned rats with the cholinergic agonist pilocarpine and the cholinergic antagonist scopolamine. We observed an increase in NGF protein levels in the cortex and hippocampus after cholinergic immunolesions and also after muscarinic receptor blockade by chronic intracerebroventricular scopolamine infusion in sham-treated rats after 2 weeks. There was no further increase in the accumulation of NGF after scopolamine treatment of immunolesioned rats. Chronic infusion of pilocarpine had no effect on cortical and hippocampal NGF protein levels in sham-treated rats. In rats with cholinergic immunolesions, however, pilocarpine did prevent the lesion-induced accumulation of NGF. There was no effect of cholinergic lesion and drug treatment on cortical or hippocampal NGF mRNA levels, consistent with the importance of NGF retrograde transport as opposed to its de novo synthesis. This study provides strong evidence for the hypothesis that there is cholinergic control of cortical and hippocampal NGF protein but not mRNA levels in adult rats.     

RNA sequencing reveals two major classes of gene expression levels in metazoan cells

The expression level of a gene is often used as a proxy for determining whether the protein or RNA product is functional in a cell or tissue. Therefore, it is of fundamental importance to understand the global distribution of gene expression levels, and to be able to interpret it mechanistically and functionally. Here we use RNA sequencing (RNA‐seq) of mouse Th2 cells, coupled with a range of other techniques, to show that all genes can be separated, based on their expression abundance, into two distinct groups: one group comprised of lowly expressed and putatively non‐functional mRNAs, and the other of highly expressed mRNAs with active chromatin marks at their promoters. These observations are confirmed in many other microarray and RNA‐seq data sets of metazoan cell types.     

Antimicrobial Susceptibility Profiles and Strain Type Diversity of Campylobacter jejuni Isolates from Turkeys in Eastern North Carolina

Campylobacter jejuni is one of the most common bacterial causes of human gastroenteritis, and recent findings suggest that turkeys are an important reservoir for this organism. In this study, 80 C. jejuni isolates from eastern North Carolina were characterized for resistance to nine antimicrobials, and strain types were determined by fla typing, pulsed-field gel electrophoresis (PFGE) with SmaI and KpnI, and (for 41 isolates) multilocus sequence typing (MLST). PFGE analysis suggested that many of the isolates (37/40 [ca. 93%]) in a major genomic cluster had DNA that was partially methylated at SmaI sites. Furthermore, 12/40 (30%) of the isolates in this cluster were completely resistant to digestion by KpnI, suggesting methylation at KpnI sites. MLST of 41 isolates identified 10 sequence types (STs), of which 4 were new. Three STs (ST-1839, ST-2132 and the new ST-2934) were predominant and were detected among isolates from different farms. The majority of the isolates (74%) were resistant to three or more antimicrobials, and resistance to ciprofloxacin was common (64%), whereas resistance to the other drug of choice for treatment of human campylobacteriosis, erythromycin, was never encountered. Most (33/34) of the kanamycin-resistant isolates were also resistant to tetracycline; however, only ca. 50% of the tetracycline-resistant isolates were also kanamycin resistant. Isolates with certain antimicrobial resistance profiles had identical or closely related strain types. Overall, the findings suggest dissemination of certain clonal groups of C. jejuni isolates in the turkey production industry of this region.