转录因子WRKY和NPR1在系统获得抗性信号转导中的相互作用机制

WRKY和NPR1是系统获得抗性（SAR）信号转导途径中的2类重要转录因子。简要讨论了WRKY和NPR1在水杨酸（SA）诱导的SAR信号转导途径中的相互作用,以及进一步认识这种相互作用机制对提高植物自身抗性的广泛应用前景。     

RNA原位杂交技术的一些应用技巧

目的:检测基因在动物组织或细胞中的时空表达模式。方法:转录反义RNA探针;利用RNA原位杂交技术检测人和小鼠牙原基中若干基因的表达。结果与结论:通过优化条件,转录出完整的反义RNA探针,并成功地利用RNA原位杂交技术在组织中检测到基因的表达;分析了一些在RNA原位杂交的过程中可能碰到的问题及其解决方法。     

Bacterial magnetic particles (BMPs)-PEI as a novel and efficient non-viral gene delivery system

BACKGROUND: Non-viral methods of gene delivery, especially using polyethylenimine (PEI), have been widely used in gene therapy or DNA vaccination. However, the PEI system has its own drawbacks, which limits its applications. METHODS: We have developed a novel non-viral delivery system based on PEI coated on the surface of bacterial magnetic nanoparticles (BMPs). The ability of BMPs-PEI complexes to bind DNA was determined by retardation of plasmid DNA in agarose gel electrophoresis. The transfection efficiency of BMPs-PEI/DNA complexes into eukaryotic cells was determined by flow cytometric analysis. The MTT assay was invited to investigate the cytotoxicity of BMPs-PEI/DNA complexes. The expression efficiency in vivo of BMPs-PEI bound to the plasmid pCMVbeta encoding beta-galactosidase was evaluated intramuscularly inoculated into mice. The immune responses of in vivo delivery of BMPs-PEI bound plasmid pcD-VP1 were determined by MTT assay for T cell proliferation and ELISA for detecting total IgG antibodies. RESULTS: BMPs-PEI complexes could bind DNA and provide protection from DNase degradation. The transfection efficiency of BMPs-PEI/DNA complexes was higher than that in PEI/DNA complexes. Interestingly, in contrast to PEI, the BMPs-PEI complex was less cytotoxic to cells in vitro. We further demonstrated that the BMPs-PEI system can deliver an exogenous gene to animals and allow it to be expressed in vivo. Such expression resulted in higher levels of humoral and cellular immune responses against the target antigen compared to controls. CONCLUSIONS: We have developed a novel BMPs-PEI gene delivery system with a high transfection efficiency and low toxicity, which presents an attractive strategy for gene therapy and DNA vaccination.     

Prospective identification of myogenic endothelial cells in human skeletal muscle

We document anatomic, molecular and developmental relationships between endothelial and myogenic cells within human skeletal muscle. Cells coexpressing myogenic and endothelial cell markers (CD56, CD34, CD144) were identified by immunohistochemistry and flow cytometry. These myoendothelial cells regenerate myofibers in the injured skeletal muscle of severe combined immunodeficiency mice more effectively than CD56+ myogenic progenitors. They proliferate long term, retain a normal karyotype, are not tumorigenic and survive better under oxidative stress than CD56+ myogenic cells. Clonally derived myoendothelial cells differentiate into myogenic, osteogenic and chondrogenic cells in culture. Myoendothelial cells are amenable to biotechnological handling, including purification by flow cytometry and long-term expansion in vitro, and may have potential for the treatment of human muscle disease.     

Lambing rate using vitrified blastocysts is improved by culture with BSA and hyaluronan

Fatty acid-free bovine serum albumin (BSA(FAF)) can be added to supplement medium used in the culture of sheep embryos. BSA(FAF) was able to support blastocyst and subsequent embryo development at rates equivalent to that of fetal calf serum (FCS)-supplemented medium when fresh embryos were transferred. Furthermore, culture with BSA(FAF) significantly increased development of vitrified blastocysts transferred into synchronized sheep. The addition of the glycosaminoglycan, hyaluronan (HA) to the culture medium in the third and fifth day also increased cryo-tolerance of blastocysts and in turn lambing rate was improved.     

Cloning,characterization, and transformation of the phosphoethanolamine <Emphasis Type="Italic">N</Emphasis>-methyltransferase gene (<Emphasis Type="Italic">ZmPEAMT1</Emphasis>) in maize (<Emphasis Type="Italic">Zea mays</Emphasis> L.)

N-methylation of phosphoethanolamine, the committing step in choline (Cho) biosynthesis in plants, is catalyzed by S-adenosyl-l-methionine: phosphoethanolamine N-methyltransferase (PEAMT, EC 2.1.1.103). Herein we report the cloning and characterization of the novel maize phosphoethanolamine N-methyltransferase gene (ZmPEAMT1) using a combination of bioinformatics and a PCR-based allele mining strategy. The cDNA sequence of ZmPEAMT1 gene is 1,806 bp in length and translates a 495 amino acids peptide. The upstream promoter sequence of ZmPEAMT1 were obtained by TAIL-PCR, and contained four kinds of putative cis-acting regulatory elements, including stress-responsive elements, phytohormone-responsive elements, pollen developmental special activation elements, and light-induced signal transduction elements, as well as several other structural features in common with the promoter of rice and Arabidopsis homologies. RT-PCR analysis showed that expression of ZmPEAMT1 was induced by salt stress and suppressed by high temperature. Over-expression of ZmPEAMT1 enhanced the salt tolerance, root length, and silique number in transgenic Arabidopsis. These data indicated that ZmPEAMT1 maybe involved in maize root development and stress resistance, and maybe having a potential application in maize genetic engineering. Note: Nucleotide sequence data are available in GenBank under the following accession numbers: maize (Zea mays, ZmPEAMT1, AY626156; ZmPEAMT2, AY103779); rice (Oryza sativa, OsPEAMT1/Os01g50030, NM_192178; OsPEAMT2/Os05g47540, XM_475841); wheat (Triticum aestivum, TaPEAMT, AY065971); Arabidopsis (Arabidopsis thaliana, AtNMT1/At3g18000, AY091683; AtNMT2/At1g48600, NM_202264; AtNMT3/At1g73600, NM_106018); oilseed rape (Brassica napus, BnPEAMT, AY319479), tomato (Lycopersicon esculentum, AF328858), spinach (Spinacia oleracea, AF237633).     

Changing viral tropism using immunoliposomes alters the stability of gene expression: implications for viral vector design

Many strategies for redirecting the tropism of murine Moloney leukemia virus (MMLV) have been described. Preformed virion-liposome complexes, termed virosomes, have been reported to be relatively stable. Virosomes mediate envelope-independent transduction that allows efficient superinfection of resistant cell lines; however, virosome-mediated transduction behaves in a non-target-specific manner. We developed a novel method using antibodies to direct MMLV to vascular endothelium. We have given the term immunovirosomes to the complexes formed between viruses, liposomes, and antibodies. These immunovirosomes improve the transduction efficiency of the viruses and alter their tropism. We have shown improved transduction when immunovirosomes were targeted at the endocytic receptors CD71 and CD62E/P and rather less good delivery when targeted at CD106. The enhancement of the transduction efficiency was transient, however, suggesting that rerouting the entry pathway of viruses alters the expression properties of the viruses.     

Enhanced cadmium-induced testicular necrosis and renal proximal tubule damage caused by gene-dose increase in a Slc39a8-transgenic mouse line

Resistance to cadmium (Cd)-induced testicular necrosis is an autosomal recessive trait defined as the Cdm locus. Using positional cloning, we previously identified the Slc39a8 (encoding an apical-surface ZIP8 transporter protein) as the gene most likely responsible for the phenotype. In situ hybridization revealed that endothelial cells of the testis vasculature express high ZIP8 levels in two sensitive inbred mouse strains and negligible amounts in two resistant strains. In the present study, we isolated a 168.7-kb bacterial artificial chromosome (BAC), carrying only the Slc39a8 gene, from a Cd-sensitive 129/SvJ BAC library and generated BAC-transgenic mice. The BTZIP8-3 line, having three copies of the 129/SvJ Slc39a8 gene inserted into the Cd-resistant C57BL/6J genome (having its normal two copies of the Slc39a8 gene), showed tissue-specific ZIP8 mRNA expression similar to wild-type mice, mainly in lung, testis, and kidney. The 2.5-fold greater expression paralleled the fact that the BTZIP8-3 line has five copies, whereas wild-type mice have two copies, of the Slc39a8 gene. The ZIP8 mRNA and protein localized especially to endothelial cells of the testis vasculature in BTZIP8-3 mice. Cd treatment reversed Cd resistance (seen in nontransgenic littermates) to Cd sensitivity in BTZIP8-3 mice; reversal of the testicular necrosis phenotype confirms that Slc39a8 is unequivocally the Cdm locus. ZIP8 also localized specifically to the apical surface of proximal tubule cells in the BTZIP8-3 kidney. Cd treatment caused acute renal failure and signs of proximal tubular damage in the BTZIP8-3 but not nontransgenic littermates. BTZIP8-3 mice should be a useful model for studying Cd-induced disease in kidney. kidney; testis; ZIP8; bacterial artificial chromosome