Identification of NBS-Type Resistance Gene Homologs in Tobacco Genome

Tobacco (Nicotiana tabacum) is an important cash crop and an ideal experimental system for studies on plant–pathogen interaction. The sequenced tobacco genome provides an opportunity for examining resistance gene homologs (RGHs) in the tobacco genome. Thirty nucleotide-binding site-type RGHs were annotated from genomic data, and another 281 putative RGHs were identified via PCR amplification from wild and cultivated tobacco. The newly identified RGHs are similar to other known RGHs, and some were categorized into new groups or branches that are different from known Nicotiana R genes or RGHs. Of the 281RGHs, 146 were identified from a single tobacco genome. We did not find any polymorphism at the RGHs in cultivated accessions, implying that strong domestication selection and/or demographic effects might have caused a sharp reduction in nucleotide diversity. Three positive selection sites were found in several RGH groups, while purifying selection is pervasive in the RGH family. Our results provide a primary RGH pool and several positively selected sites for the further functional validation of resistance genes in tobacco.     

Pleiotropic function of intersectin homologue Cin1 in Cryptococcus neoformans

The manifestation of virulence traits in Cryptococcus neoformans is thought to rely on intracellular transport, a process not fully explored in this pathogenic fungus. Through interaction cloning, we identified a multi‐modular protein, Cin1 (cryptococcal intersectin 1), whose domain structure is similar to that of the human endocytic protein ITSN1. Cin1 contains an N‐terminal EH domain, a central coiled‐coil region, a WH2 domain, two SH3 domains and a C‐terminal RhoGEF (DH)‐PH domain. Interestingly, alternative mRNA splicing resulted in two Cin1 isoforms, and Cin1 homologues are also restricted to basidiomycetous fungi. Disruption of the CIN1 gene had a pleiotropic effect on growth, normal cytokinesis, intracellular transports and the production of several virulence factors. Additionally, Cin1 interacts with cryptococcal Cdc42 and Wsp1 (a WASP homologue) proteins in vitro, suggesting a conserved role in the regulation of the actin cytoskeleton. However, deletion of RhoGEF or SH3 and RhoGEF domains did not result in any phenotypic changes, suggesting that functional redundancy exists in proteins containing similar domains or that the activities by other domains are necessary for Cin1 function. Our study presents the first evidence of a multi‐modular protein whose function in intracellular transport underlies the growth, differentiation and virulence of a pathogenic microorganism.     

固本颗粒胶囊对大鼠COPD模型血清IL-8及TNF-α影响的实验研究

目的:根据COPD慢性气道炎症学说,探讨固本颗粒胶囊对COPD模型大鼠血清中相关细胞因子的影响,从而阐明其防治COPD的作用机理,为固本颗粒胶囊的临床应用提供实验依据.方法:将50只Wistar大鼠随机分成正常对照组、模型对照组、强的松组、固本颗粒胶囊低剂量组、固本颗粒胶囊高剂量组,每组10只,以烟熏及气管内滴注脂多糖的方式建立大鼠COPD模型,予相应药物干预,观察记录大鼠一般状况,至实验结束,酶联免疫吸附法检测大鼠血清中相关细胞因子(IL-8、TNF-α)的含量.相关实验数据用SPSS10.0统计软件进行统计学处理.结果:大鼠一般状况及组织病理学改变提示COPD模型复制成功,与正常对照组比较,模型对照组大鼠血清中相关细胞因子(IL-8、TNF-α)的含量水平失衡.在改善COPD模型大鼠的一般状况、病理学改变及细胞因子含量比例失衡的作用结果来看,各治疗组与模型对照组均有显著差异(P＜0.05).综合比较,强的松组治疗作用最为显著,固本颗粒高剂量次之,固本颗粒低剂量组作用最弱.结论:①.固本颗粒胶囊能有效缓解COPD模型大鼠临床表现及气道炎症,其作用机制在于:能纠正COPD大鼠体内细胞因子水平失衡;②.上述作用,具有一定的量效关系,即随着给药剂量的增加有加强趋势.     

先天性尿道下裂的矫治(附1 000例报告)

目的:总结先天性尿道下裂的矫治经验.方法:尿道下裂患者1000例,年龄1～26岁,平均4岁.冠状沟型118例,阴茎体型593例.阴茎阴囊型189例,会阴型100例.791例采用尿道板切开卷管成形法(TIP),117例采用Duckett+Duplay术,92例采用二期手术,一期行阴茎伸直及皮辩转移,二期行尿道成形术(TIP).术中遵循微创原则,使用显微器械,尽量保留原有的正常组织结构.结果:随访6月至2年,TIP术741例手术一次成功,Duckett+Duplay术99例一次成功,分期手术二期成功86例.并发尿道皮肤瘘51例,尿道狭窄17例,尿道憩室6例,均经再次手术治愈.结论:尿道下裂矫治手术中,首先保留尿道板手术,并发症少,成功率高,值得推广,阴茎严重弯曲者或重度尿道下裂患者可选Duckett+Duplay术或者分期手术.     

Genetic relationships between resistances to Fusarium head blight and crown rot in bread wheat (Triticum aestivum L.)

Fusarium head blight (FHB) and crown rot (CR) are two wheat diseases caused by the same Fusarium pathogens. Progress towards CR resistance could benefit from FHB-resistant germplasm if the same genes are involved in resistance to these two different diseases. Two independent studies were conducted to investigate the relationship between host resistances to these two diseases. In the first study 32 genotypes were assessed and no significant correlation between their reactions to FHB and CR was detected. The second study was based on a QTL analysis of a doubled haploid population derived from a variety with resistance to both diseases. Results from this study showed that loci conferring resistance to FHB and CR are located on different chromosomes. Together, these results suggest that, despite a common aetiology, different host genes are involved in the resistance against FHB and CR in wheat. Thus, although it is possible that genes affecting both diseases may exist in other germplasm or under different conditions, separate screening seems to be needed in identifying sources of CR resistance.     

A new carbazole-based phenanthrenyl ruthenium complex as sensitizer for a dye-sensitized solar cell

Three new amphiphilic ruthenium complexes (Ru-1, Ru-2 and Ru-3) based on phenanthrenyl derivatives have been synthesized and used as photosensitizers for dye-sensitized solar cells (DSSCs). The ruthenium complex Ru-1 containing a carbazole group showed especially improved photophysical properties (red-shifted metal-to-ligand charge-transfer transition absorptions and enhanced molar extinction coefficients) and interesting electrochemical properties, resulting in its improved open circuit potential and high overall light-to-electric power conversion efficiency of 5.3% (AM1.5, 75 mW/cm²). These facts indicate that the carbazole-based phenanthrenyl ruthenium complex is a promising candidate for improving the conversion efficiency of dye-sensitized solar cells.     

A new study of cell disruption to release recombinant thermostable enzyme from Escherichia coli by thermolysis

Extraction of intracellular protein from Escherichia coli is traditionally achieved by mechanical, chemical or enzymatic disruption technology. In this study, a novel thermolysis method was used to disrupt E. coli cells to release a recombinant thermostable esterase. We found that heat treatment of E. coli was highly effective to destroy the integrity of bacterial cell walls and release the recombinant hyperthermophilic esterase at temperatures above 60 degrees C. The effects of temperature, pH and cell concentration on the efficiency of cell disruption were examined. The most effective temperature for cell disruption was at 80 degrees C. The pH and cell concentration had only minor effect on the release of the hyperthermophilic esterase. In addition, we found that the hyperthermophilic esterase could be purified at the early stage of the thermolysis, which is a major advantage of the thermolysis method. Finally, a comparison between thermolysis and traditional methods for the disruption of cells and the release of the thermostable enzyme was made.     

Developmental expression of CagMdkb during gibel carp embryogenesis

Midkine (Mdk) genes have been revealed to have different expression patterns in vertebrates and therefore, additional studies on Mdk expression patterns are required in more species. In this study, CagMdkb has been cloned and characterized from a SMART cDNA library of 10-somite stage embryos of Carassius auratus gibelio. Its full length cDNA is 1091 bp and encodes a sequence of 147 amino acids, which shows 97.3% identity to zebrafish Mdkb on the amino acid level. RT-PCR analysis reveals that CagMdkb is first transcribed in gastrula embryos and maintains a relatively stable expression level during subsequent embryogenesis. Western blot analysis reveals a 19 kDa maternal CagMdkb protein band and the zygotic CagMdkb protein is expressed from gastrula stage. At around 10 somite stage, the 19 kDa CagMdkb is processed to another protein band of about 17 kDa, which might be the secreted form with the 21-residue signal peptide removed. With immunofluorescence analysis, maternal CagMdkb protein was found to be localized in each blastamere cell of early embryos. The zygotic CagMdkb positive fluorescence signal was detected from a pair of large neurons at 18-somite stage. At the later stages, CagMdkb protein was also extended to numerous small neurons in the forebrain, midbrain and hindbrain, as well as to nerve fibers in the spinal cord. Co-localization with 3A10 antibody revealed CagMdkb immunoreactivity on developing Mauthner neurons, a member of reticulospinal neurons. In addition, ectopic expression of CagMdkb in early embryos of gibel carp and zebrafish suppressed head formation and CagMdkb function was found to depend on secretory activity. All these findings indicate that CagMdkb plays an important role in neural development during gibel carp embryogenesis and there is functional conservation of Mdkb in fish head formation.     

新疆短命植物小拟南芥耐盐性的初步研究

利用种子萌发及石蜡切片等方法对新疆短命植物小拟南芥(Arabidopsis pumila)在盐胁迫下种子的萌发率及植株生长发育的变化进行了研究,结果显示:(1)盐胁迫对小拟南芥种子萌发具有抑制作用,当去除盐分后,部分种子能够重新萌发.(2)盐分影响幼苗的形态及内部结构,低盐(50 mmol/L)时,幼苗基生叶较大且数量增加;叶中栅栏组织细胞大,排列舒展;根中导管数量明显增多,植株生长健壮而旺盛;而较高盐(150 mmol/L)时,叶片变小增厚,色深绿,底部叶变黄白色,叶中栅栏组织细胞窄小,排列紧密;根中导管数急剧下降,植株生长受到明显抑制.(3)盐胁迫对成株期植株的高度、花序轴长、角果数等性状都有显著影响,但在NaCl浓度达500 mmol/L时,植株仍然存活且有一定的结实率,显示此时的耐盐性比萌发期和幼苗期有显著提高.研究表明,小拟南芥从幼苗至成株期耐盐性逐渐增强,该特征与其对自然生存环境的适应相关.