SIMULTANEOUS OVER-EXPRESSION OF INSULIN-LIKE GROWTH FACTOR- Ⅱ (IGF- Ⅱ ) AND IGF- Ⅱ RECEPTOR(IGF- Ⅱ R) GENES IN HUMAN PRIMARY CANCER-IMPLICATION OF AUTOCRINE AND PARACRINE MECHANISM IN AUTONOMOUS GROWTH OF HEPATIC CANCER

This is first report about the simultaneous over-expression of both Insulin-like growth factor (IGF- I ) and its receptor (IGF- I R) at mRNA level in human primary hepatic Cancer (PHC). In 10 PHC samples from China, IGF-I and IGF- I R were both over-expressed, whereas only a background signal was detected in normal liver. In 5 pairs of PHC and its non- tumorous adjacent liver tissues from South Africa, IGF- I and IGF- I R were also over-expressed in PHC. mRNA expression of IGF- I in all 5 cases and IGF- I R in 4 of 5 cases were higher in cancer than non- tumorous adjacent liver tissues. These results strongly implicate that an autocrine and/ or paracrine mechanism might be Involved in formation and progression of PHC.

Characterization of NPR1 Genes from Norton and Cabernet Sauvignon Grapevine

Non-expressor of pathogenesis-related genes 1 （NPR1） plays a significant role in the defense responses of plants to pathogens by regulating the expression of defense-related genes. In the present study, we isolated two NPR1 genes from Vitis aestivalis cv. Norton and Vitis vinifera cv. Cabernet Sauvignon, which were referred to as VaNPR1.1 and VvNPR1. 1-CS, respectively. They encode a protein of 584 amino acids with a predicted molecular weight of 64.8 kDa and a theoretical isoelectric point （pI） of 5.74. The predicted amino acid sequences of VaNPR1.1 and VvNPR1.1-CS differ by only one amino acid. Over-expression of VaNPR1.1 gene in Arabidopsis npr1-1 mutant plants restores the transcriptional expression of AtPR-1 gene, though not to the full scale. This result demonstrated that a grapevine VaNPR1.1 possesses a similar function to the Arabidopsis NPR1 in the regulation of defense-related genes. Over-expression of VaNPR1.1 in transgenic Arabidopsis plant increased tolerance to salinity, but had no effect on the drought tolerance. We conclude that VaNPR1.1 is a functional ortholog of AtNPR1 and also involved in grapevine＇s response to the salt stress.

Overexpression of the PdpapERF109 gene enhances resistance of Populus davidiana×P.alba var.pyramidalis to Fusarium oxysporum infection

The key transcription factor gene PdP apE RF109 was cloned from Populus davidiana×P.alba var.pyramidalis(Pdpap),and after overexpression of P dP ap ERF109 in transformants,the gene functions in the resistance response to Fusarium oxysporum infection.Compared with the wild Pdpap,after inoculation with F.oxysporum,the physiological and biochemical characteristics,including relative fresh weight,peroxidase activity,and the percentage of electrolyte leakage showed that,after overexpression of the PdPapERF109 gene,the transformants grew well and displayed significant resistance to F.oxysporum infection.By comparing the reactive oxygen species scavenging capacity of Pdpap plants after pathogen infection,the P dPapERF109-overexpressing plants had significantly better reactive oxygen species scavenging ability than the wild plants.Comprehensive analysis of plant morphology and various physiological and biochemical parameters showed that the overexpression of the P dpapERF109 gene significantly improved the resistance of Pdpap plants to F.oxysporum root rot.Therefore,increasing the expression of the homologous ERF109 gene can be an effective strategy to increase disease resistance in hybrid poplars.

Can overexpression of TGF-β1 gene change the sex ratio in transgenic mice?

Mouse TGF-β1 gene was microinjected into male pronuclei of F2 hybrid fertilized eggs obtained by mating CSJLF1 and C57BL/6J inbred strains to generate transgenic mice with over-expressed TGF-β1 gene. The rate of founder production is 31% and Southern blot analysis of founder mice tail DNAS gave an integration efficiency of 33%. TGF-β1 gene could be stably integrated to the chromosomes of transgenic mice and transmitted to their progeny at a rate of 33% in the second generation. Dot blot analysis of tail RNA of some transgenic mice indicated a moderate expression of the transgene. The most interesting finding of the present work is the striking deviation from the normal male:female sex ratio in transgenic mice,with an average ratio of 6.7:1. The possible nature of the predominance of male sex in transgenic mice overexpressing TGF-β1 is discussed.

Strategies used for genetically modifying bacterial genome: site-directed mutagenesis, gene inactivation, and gene over-expression

With the availability of the whole genome sequence of Escherichia coli or Corynebacterium glutamicum, strategies for directed DNA manipulation have developed rapidly. DNA manipulation plays an important role in understanding the function of genes and in constructing novel engineering bacteria according to requirement. DNA manipulation involves modifying the autologous genes and expressing the heterogenous genes. Two alternative approaches, using electroporation linear DNA or recombinant suicide plasmid, allow a wide variety of DNA manipulation. However, the over-expression of the desired gene is generally executed via plasmid-mediation. The current review summarizes the common strategies used for genetically modifying E. coli and C. glutamicum genomes, and discusses the technical problem of multi-layered DNA manipulation. Strategies for gene over-expression via integrating into genome are proposed. This review is intended to be an accessible introduction to DNA manipulation within the bacterial genome for novices and a source of the latest experimental information for experienced investigators.

Enhancing production of ergosterol in Pichia pastoris GS115 by over-expression of 3-hydroxy-3-methylglutaryl CoA reductase from Glycyrrhiza uralensis

The rate-limiting enzyme in the mevalonic acid(MVA)pathway which can lead to triterpenoid saponin glycyrrhizic acid(GA)is 3-hydroxy-3-methylglutaryl-CoA reductase(HMGR).In order to reveal the effect of copy number variation in the HMGR gene on the MVA pathway,the HMGR gene from Glycyrrhiza uralensis Fisch.(GuHMGR)was cloned and over-expressed in Pichia pastoris GS115.Six recombinant P.pastoris strains containing different copy numbers of the GuHMGR gene were obtained and the content of ergosterol was analyzed by HPLC.The results showed that all the recombinant P.pastoris strains contained more ergosterol than the negative control and the strains with 8 and 44 copies contained significantly more ergosterol than the other strains.However,as the copy number increased,the content of ergosterol showed an increasing–decreasing–increasing pattern.This study provides a rationale for increasing the content of GA through over-expressing the GuHMGR gene in cultivars of G.uralensis.

Improve Ethanol Yield Through Minimizing Glycerol Yield in Ethanol Fermentation of Saccharomyces cerevisiae

In ethanol fermentation of Saccharomyces cerevisiae （S. cerevisiae）, glycerol is one of the main by-products. The purpose of this investigation was to increase ethanol yield through minimizing glycerol yield by using mutants in which FPS1 encoding a channel protein that mediates glycerol export and GPD2 encoding one of glycerol-3-phosphate dehydrogenase were knocked-out using one-step gene replacement. GLT1 and GLN1 that encode glutamate synthase and glutamine synth.etase, respectively,were overexpressed using two-step gene replacment in fpsl△gpd2△ mutant.The fermentation properties of ZAL69（fpsl△：：LEU2 gpd2△：：URA3） and ZAL808 （fps1△：：LEU2 gpd2△：：URA3 PPGK1-GLT1 PPGK1-GLN1） under microaerobic conditions were investigated and compared with those of wild type（DC124）. Consumption of glucose, yield of ethanol, yield of glycerol, acetic acid, and pyruvic acid were monitored. Compared with wild type, the ethanol yield of ZAL69 and ZAL808 were improved by. 13.17% and 6.66 %, respectively, whereas glycerol yield decreased by 37.4 % and 41.7 %. Meanwhile, acetic acia yield and pyruvic acid yield aecreasea aramatlcally comparea to wild type. Our results indicate that FPS1 and GPD2 deletion of S. cerevisiae resulted in reduced glycerol yield and increased ethanol yield, but simultaneous overexpression of GLT1 and GLN1 infps1△gpd2△ mutant did not have a higher ethanol yield thanfps1△gpd2△ mutant.

Lentivirus-mediated Persephin overexpression in Parkinson's disease rats

Persephin, together with glial cell line-derived neurotrophic factor and neurturin, has a neurotrophic effect and promotes the survival of motor neurons cultured in vitro. In this study, dopaminergic neurons in the substantia nigra of rats were transfected with the Persephin gene. One week later 6-hydroxydopamine was injected into the anterior medial bundle to establish a Parkinson＇s disease model in the rats. Results found that the number of dopaminergic neurons in the substantia nigra increased, tyrosine hydroxylase expression was upregulated and concentrations of dopamine and its metabolites in corpus striatum were increased after pretreatment with Persephin gene. In addition, the rotating effect of the induced Parkinson＇s disease rats was much less in the group pretreated with the Persephin gene. Persephin has a neuroprotective effect on the 6-hydroxydopamine-induced Parkinson＇s disease through protecting dopaminergic neurons.