[Effect of cultivation in zinc media on the growth of and the degree of zinc in organic form in transgenic metallothionein mushroom].

Metallothioneins (MTs) are a family of low molecular weight, cysteine-rich and metal-binding functional proteins. Transgenic MT mushroom can be used as functional food additives, but its zinc-enriching ability has not been studied systemically until now. The zinc contents in mycelia of transgenic MT mushroom (Pleurotus ostreatus) and wild type mushroom mycelia cultivated in different zinc concentration media were analyzed by ICP-OES. The growth status, zinc-enriching ability and degree of zinc in organic form (DZOF) were also analyzed. Results showed that MT mushroom mycelia grew rapidly, but the growth was inhibited when the zinc content in solid media was higher than 1.6 mmol x L(-1). MT mushroom mycelia could enrich more zinc than that of wild type, and the zinc content in MT mushroom mycelia could be 2.56-27.49 mg x kg(-1) when it was cultivated in a liquid media with 0.6-1.2 mmol x L(-1) zinc. DZOF of MT mushroom mycelia in a liquid media with 0.6 mmol x L(-1) zinc at 7 d was significantly higher (88.7%) than that in the wild type (82.1%, alpha = 0.05), but there was no significant difference in DZOF when the MT mushroom mycelia was cultivated in a liquid media with different zinc content at 7 d.

[Decontamination of heavy metals in wastewater by transgenic Synechococcus sp. PCC 7002 with mouse metallothionein-I gene].

The growth characteristics and the decontamination of heavy metals in analogous heavy metals wastewater by transgenic Synechococcus sp. PCC 7002 with mouse metallothionein-I gene were studied. The results show that transgenic Synechococcus sp. PCC 7002 not only has a higher tolerance to heavy metals, but also has a higher growth rate than wild strain. The concentration of Cd2+, Pb2+ and Hg2+ decreases with the progress of cultivation, and its maximum decreasing extent occurs at 1 - 3 day. After three days of cultivation, the absorption of Cd2+, Pb2+ and Hg2+ by transgenic Synechococcus sp. PCC 7002 is 10.75, 58.89 and 112.61 mg g(-1) of dried cells respectively, which is 3.16, 2.18 and 100.45 times higher than wild cells. The mono-factor and overall model developed fit the experiment data well.

[Distribution of Pb and Zn in transgenic metallothionein tobacco].

Transgenic metallothionein (MT) plant can clear the heavy metals from soil and environment, but the distribution of metals in plants has not been studied systematically. The Pb and Zn contents in different parts of transgenic MT tobacco plant of sixth generation and traditional plant (same culture variety as control) were analyzed. The Pb and Zn contents in total transgenic plant were 21.8% and 27.2% higher than control, respectively. The distribution of Pb and Zn in different organs varied in these two types of plants. The Pb and Zn contents in old leaves, stem and root in transgenic plants were significantly higher than those in wild type tobacco, while there was no significant difference in young leaves. The Pb contents in old leaves and root were 30.2% and 47.8% higher than those in the control, and the Zn contents in old leaves, stem and root were 4.7%, 29.2% and 21.6% higher than those in the control. These data showed that Pb was accumulated in old leaves and root easily, while Zn was accumulated in old leaves and stem easily.

Survival of human metallothionein-2 transplastomic Chlamydomonas reinhardtii to ultraviolet B exposure.

Solar ultraviolet (UV) radiation has a great influence on green organisms, especially plankton like Chlamydomonas. A human metallothionein-2 gene, which is generally considered to have an anti-radiation function by its coding product, was transferred into the chloroplast genome of Chlamydomonas reinhardtii. To dynamically measure the UV effects on Chlamydomonas cells grown in liquid tris-acetate-phosphate medium, a new method was developed based on the relationship between the chlorophyll content of an algal culture and its absorbance at 570 nm after the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. In this experiment, both the wild-type and the transplastomic C. reinhardtii cells were cultivated in 96-well microplates containing liquid tris-acetate-phosphate medium in the absence or presence of zinc, copper, cadmium and cysteine. The transgenic C. reinhardtii showed a higher resistance than wild-type to UV-B exposure under all the examined conditions. Metals in the medium had positive impacts on both types of cells, but had significant influence only on the transplastomic cells. However, the high cell viability of the transgenic alga at the end of the 8 h UV-B treatment disappeared after a 20-h recovery culture. Cysteine did not protect cells from UV-B damage, but clearly enhanced the growth of both wild-type and transgenic C. reinhardtii.

Studies on the epitope of neuronal growth inhibitory factor (GIF) with using of the specific antibody.

Human neuronal growth inhibitory factor (GIF), a metalloprotein classified as metallothionein-3, is specifically expressed in mammal central nervous system (CNS). In these Studies the specific antibody to human GIF was prepared and used to search the epitope of human GIF by enzyme-linked immunosorbent assay (ELISA) and sequence comparison. The result of ELISA showed the epitope of human GIF may locate on a octapeptide (EAAEAEAE) in the alpha-domain of human GIF, and the result of nerve cell culture indicated that the biological activity of GIF may be affected by the specific antibody.

[Molecular cloning and identification and biological activity of GIF-interacting protein(s)].

In order to examine the elusive functional mechanism of GIF (Neuronal growth inhibitory factor, GIF) and elucidate the possible relationship between GIF and Alzheimer's disease, we constructed bait1 plasmid (pHyblex-GIF) by cloning GIF cDNA directly in frame with plasmid pHyblex, and used the yeast two-hybrid system to screen Alzheimer's disease human brain cDNA library and found the GIF-interacting proteins. The final results from coimmunoprecipitation and western blotting experiments confirmed that interacting proteins specifically binds to GIF. After sequencing the nucleotide of the putative positive plasmids and searching for homologues, we found that one of these is the part of human nuclear dUTPase protein sequence. Then the dUTPase genes are cloned into pGEX-4T-1, the fusion expression vector of GST,and highly expressed in E. coli BL21. The proteins dUTPase and GIF were purified and obtained by affinity chromatography, thrombin digestion and gel filtration on Sephacryl S100. It demonstrated that the proteins dUTPase and GIF had the growth inhibitory activity on co-cultured neuron in vitro. The inhibitory curve was very similar to the GIF. It's possible that dUTPase is one of the proteins interacting with GIF in Alzheimer's disease human brain extracts.

Differential display proteome analysis of PC-12 cells transiently transfected with metallothionein-3 gene.

Metallothionein-3 (MT-3), also known as growth inhibitory factor, possesses several unique properties other than the common features of metallothionein family. To investigate the mechanisms underlying its multifaceted roles in the central nervous system, we employed differential display proteomics techniques to study holistic protein changes of PC-12 cells induced by transient transfection of MT-3. Ten significantly and reproducibly changed proteins were identified and their functional implications are discussed in some detail.

[Affection of metallothionein-3 to dUTPase's accommodating cellular toxicity of dUTP].

Metallothionein-3 (MT-3), renamed as growth inhibitory factor (GIF), is a brain specific member of the metallothionein family. Human dUTPase is a recently found protein in brain that can interact with hMT-3. They have the growth inhibitory activity on neuron cell by interaction. To study the affection of hMT-3 to dUTPase's eliminating the cellular toxicity caused by dUTP, the pSVHA-dUTPase and pFLag-hMT-3 genes have been transfected into HEK293 cells. In addition, the dUTPase and hMT-3 proteins were expressed in BL21 to study the role of hMT-3 on the hydrolyzation of dUTP by dUTPase. The results demonstrate that the cells co-transfected with dUTPase and hMT-3 genes have more strong resistibility to dUTP than the cells transfected only with dUTPase gene. And that the hMT-3 protein can accelerate the hydrolyzation of dUTP by dUTPase. All these indicate that hMT-3 can cooperate with dUTPase to protect better the 293 cells from dUTP. This research offered the theoretic elements for the application of hMT-3 and dUTPase in chemic cure.

Differential protein expression induced by transient transfection of metallothionein-3 gene in SH-SY5Y neuroblastoma cell line.

Metallothionein-3(MT-3), also known as growth inhibitory factor (GIF), is predominantly expressed in central nervous system (CNS). It belongs to the family of metallothionein(MT) but has several unique properties that are not shared by other family members such as MT-1/MT-2. In the past few years, MT-3 had been postulated to be a multipurpose protein which could play important neuromodulatory and neuroprotective roles in CNS besides the common roles of MTs. However, the primary function of MT-3 and the mechanism underlying its multiple functions were not elucidated so far. In present study, human neuroblastoma cell line SH-SY5Y was employed to study the overall cellular protein changes induced by transient transfection of MT-3 gene, based on comparative proteome analysis. Averagely about 750 spots were visualized by Coomassie staining in one 2D gel, in which 17 proteins were shown to display significant and reproducible changes by semiquantitative analysis with ImageMaster 2D Elite software. Among them, 12 proteins were up-regulated while other 5 proteins were down-regulated. Using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, 10 proteins were further identified to be zinc finger protein, glutamate transporter, and enhancer protein, etc., which were involved in several important pathways regulating the functions of central nervous system. The results showed that MT-3 might exert its unique functions by regulating the expression of these proteins.

Cloning and expression of metallothionein mutant alpha-KKS-alpha in Anabaena sp. PCC 7120.

The mouse metallothionein (mMT) mutant alpha-KKS-alpha has a higher capacity for binding heavy metals than wild type mMT. The mMT mutant alpha-KKS-alpha gene was placed under the control of the strong promoter PpbsA to generate the intermediate vector pRL-alpha-KKS-alpha. pRLalpha-KKS-alpha was then linked with the plasmid pDC-08 to construct shuttle expression vector pDC-alphaKKS-alpha. This expression vector was transformed into Anabaena sp. PCC 7120 using triparental conjugative transfer. After antibiotic selection (ampicillin and kanamycin), transgenic Anabaena was identified by PCR and Western blotting. The expression level of the mMT mutation alpha-KKS-alpha reached 7.4 mg/g dry cells weight, as detected by ELISA, and heavy metal resistance of the transgenic Anabaena was significantly improved.

[Isolation and identification of proteins with anti-tumor and fibrinolysogen kinase activities from Eisenia foetida].

Proteins from Eisenia foetida possess many biological activities. A group of proteins precipitated by ethanol were isolated and purified by Sephadex G-75 and HiPrep 16/60 DEAE columns, then identified by one- or two- dimensional electrophoresis and mass spectrometry. 2D gel experiments displayed that the pI of proteins from Eisenia foetida were mainly from 3.0 to 4.0. Anti-tumor and kinase activities were determined by in vitro experiments. The enthanol fraction D2(8) showed both of the activities. These ethanol-precipitated proteins were identified further by native polyacrylamide electrophoresis, the protein spots were cut off from gels and digested by trypsin, the peptide mass fingerprints (PMFs) were determined by mass spectrometry. PMF, molecular weight, amino acid composition and N-terminus of 6 proteins were characterized, and band 9 was identified as D2(8). The results suggested that there exist proteins in Eisenia foetida possessed both anti-tumor and fibrinolysogen kinase activities. These methods can be used for identification of the natural bioactive proteins.

[Functional di-domain of neuronal growth inhibitory factor].

Neuronal growth inhibitory factor (GIF), known also as metallothionein-III (MT-III), was the first validated to be capable of inhibiting growth of neuronal cells in nervous system, its beta-domain being functional. GIF functional di-domain (GIFbeta- beta) was constructed to study the structure and function of GIF. N terminal beta-domain and C terminal beta-domain cDNAs were amplified by PCR, inserted into vector pGEX-4T-1 and expressed in Escherichia coli, as carboxyl terminal extension of glutathione-S-transferase (GST), by IPTG induction. After digestion by thrombin, the fusion protein was isolated by passing through a glutathione-Sepharose 4B affinity chromatography column and was purified by gel fit ration on Sephacryl-S100. About 60 mg protein per liter of bacterial cell culture was achieved. The results of SDS-PAGE, amino acid composition, molecular mass, the ratio of metal/protein and sulfhydryl group/protein showed that the purified protein was the GIFbeta- beta. Circular dichroism (CD) spectroscopy show GIFbeta- beta has characteristic metal-sulfhydryl clusters of metallothionein family. Inhibitory activities detected by the MTT reduction assay are: GIF > GIFbeta-beta > GIF beta-domain.

[Rapid determination of metallothioneins in foods by capillary zone electrophoresis].

A rapid method for the analysis of metallothioneins (MT) in foods by capillary zone electrophoresis(CZE) was developed. Two isomers of MT (MT1, MT2) in foods were separated and determined. After a series of optimization, the separation and determination of MT1 and MT2 were obtained within 10 min by using the phosphate buffer system consisting of 0.02 mol/L Na2HPO4 and 0.02 mol/L NaH2PO4 (pH 7.0), and UV detection at 200 nm. Under the optimal experimental conditions, the minimum detectable limit was 1 mg/L, and the added standard recoveries of MT1, MT2 in foods were found to be in the range of 82.0%-93.4%. The relative standard deviations (RSD) were found to be lower than 10%. Therefore, with this simple and rapid method, the contents of two isomers in foods can be determined by external standard method after sample pretreatment.

Construction and Expression of a Recombinant Antibody-targeted Plasminogen Activator Composed of a Humanized Monoclonal Antibody against Activated Human Platelets and a Single-chain Urokinase.

To obtain a thromblytic agent with high efficacy and specifity, we have engineered a recombinant chimeric plasminogen activator SZ51Hu-scuPA, which was composed of a humanized monoclonal antibody (SZ51Hu) directed against activated human platelets and a single-chain urokinase (scuPA). The cDNA sequence encoding scuPA was fused through 5' end to 3' end of the CH(3) of SZ51Hu heavy-chain sequence in the expression vector alphalys30(alphalys30-SZ51VH/Hu-scuPA) by PCR. This construct was transfected into a murine myeloma line secreting SZ51Hu light chain with Lipofectin reagent and three lines which showed stable integration and high level expression with concentration of 5 mg/L in supernatant, were selected in the end. Purified SZ51Hu-scuPA migrated as a 160 kD band on non-reduced SDS/PAGE and had the same characteristic of binding to the activated platelets compared with its parent murine antibody molecule SZ51 by Western-blot analysis. The fibrinolytic activity of purified products was 39 000 IU/mg. Thus, by recombinant techniques, an expressed fusion protein was capable of specific binding to activated platelets and plasminogen activation. These observations laid a solid foundation for further study of targeting of thrombolysis in vitro and in vivo.

Purification and Characterization of the Fibrinolytic Enzyme(eFE-D) from Earthworm Eisenia folelide.

The fibrinolytic enzyme eFE-D was isolated and purified from earthworm Elsenia folelide by gel-filtration on Sephacryle S-200, ion-exchange chromatography on DEAE-Sepharose Fast Flow and hydrophobic chromatography on Phenyle-Sepharose Fast Flow as detected by the fibrinolytic activity with a standard fibrin plate method. The most strong fibrinolytic component eFE-D not only hydrolyzed fibrin directly, but also activated the plasminogen to plasmin. Its apparent fibrinolytic value was equal to 2,800 UK IU per mg. Its molecular weight as estimated by SDS-PAGE and MS analysis was 29 kD and 24.849 kD respectively and its isoelectric point (pI) was 4.O. Fibrinolytic enzyme eFE-D was very thermostable with a single polypeptide chain. Studies with protease inhibitors indicated that eFE-D was a kind of serine protease. Its N-terminal amino acid sequence is M-I-G-G-T-N-A-S-P-G-E-F-P-W-Q-L-S-Q-Q-R. The result of amino acid composition analysis showed that the enzyme contained abundant amino acids of low molecular weight, but few aromatic and alkaline amino acids.