长期不同施肥制度下几种土壤微生物学特征变化

 为阐明土壤微生物对土壤健康的生物指示功能, 以国家褐潮土肥力与肥料效益监测基地的长期肥料试验为平台, 应用BIOLOG ECO微平板培养法与常规分析法研究了长期施肥15年后不同施肥制度对土壤微生物生物量、活性、群落代谢功能多样性及土壤肥力的影响。研究结果表明, 与对照(CK)相比, 长期化肥与有机肥配施土壤中土壤有机质(SOM)、全氮(STN)、全磷(STP)含量升高, 土壤C/N与pH值降低, 土壤微生物量碳(Soil microbial biomass carbon, SMBC)、生物微生物量氮(Soil microbial biomass nitrogen, SMBN)、微生物商(qMB)及脲酶(Urease)活性升高, BIOLOG ECO微平板平均颜色变化率(Average well color development, AWCD)、土壤微生物代谢功能多样性指数变化不明显。和长期单施化肥处理(NPK)相比, 长期化肥与有机肥配施处理中上述几种微生物学特征(SMBC、SMBN、qMB、Urease及AWCD、代谢功能多样性指数)均呈极显著增加。NPK处理与CK相比虽然SOM、STN、STP含量稍有升高, 土壤C/N与pH值降低, SMBC、SMBN、qMB及Urease活性增高, 但是AWCD、土壤微生物代谢功能多样性指数却显著下降。过氧化氢酶活性(Catalase)在各处理土壤中的差异不显著。土壤微生物碳源利用的主成分分析表明, 长期不同施肥各处理在土壤微生物利用碳源的种类和能力上有差异。此试验说明, 土壤微生物受农业管理措施和多种环境因素的影响, 土壤微生物学特征可作为土壤质量的敏感指标, 为提高作物产量、增强肥力提供理论参考。     

Overexpression of γ-aminobutyric acid transporter subtype I leads to susceptibility to Kainic acid-induced seizure in transgenic mice

INTroDUCTION.7-aminobutyric acid (GABA), a major in-hibitory neurotransmitter in vertebrate brain, in--duces neuronal inhibition via GABA receptors. Adeficiency of GABAergic inhibition has been hy-pothesized to be a principal factor in the patho-genesis of epilepsy[1]. GABA transporters are im-portant components of the GABAergic system, andfunction in part to terminate the GABA transmis-sion through rapid re-uptake of GABA into thepresynaptic neurons and surrounding gliaJ cells[2…     

恶性血液病中着丝粒和着丝粒周染色体重排的研究进展

用染色体特异的卫星DNA探针进行染色体荧光原位杂交(FISH)分析恶性血液病,发现着丝粒和着丝粒周染色体的重排并非罕见.分子生物学技术和基因组计划的发展,促进了对异染色质分子本质的研究.本文就着丝粒和着丝粒周异染色质的分子结构及其重排机制作一综述。 Abstract:Fluorescence in situ hybridization(FISH) analysis with chromosome-specific satellite DNA probes of various hematopoietie malignancies have revealed that centric and pericentric chromosome rearrangements occurred more frequently than hitherto admitted.The development of molecular biology and genome project have fostered much interest in the structure and function of centromeric heterochromatin.In this paper,recent advances in molecular structure and rearrangement mechanisms of centric and pericentric heterochromatin are reviewed and future study is also discussed.     

米曲霉(Aspergillus oryzae)果胶酸内切水解酶(PGA)在原核系统中重组表达

果胶酶具有广阔的商业用途,在食品工业上主要用于果汁和酒类的澄清、提高植物油的提取率、提高水果的硬度和植物纤维脱胶。米曲霉(Aspergillusoryzae)一直用于传统发酵食品的生产,自然条件下其果胶酶的产量较低。文献报道的果胶酶的重组表达成功的例子较少,且活性较低。通过RT-PCR的方法,获得不含信号肽的果胶酸内切水解酶A(polygalacturonaseA,PGA)的cDNA,PGAcDNA连入pET-28a( )载体,构建pET-28a( )-pga质粒。pET-28a( )-pga转化Turner(DE3)placⅠ细胞,得到转化子pET-28a( )-pga-Turner(DE3)placⅠ,首次实现了米曲霉PGA在大肠杆菌系统中过表达,进一步对PGA在大肠杆菌系统中表达的条件进行了研究。在37℃、220r/min条件培养pET-28a( )-pga-Turner(DE3)placⅠ细胞,OD600至0·8左右时,用500μmol/Lisopropylβ-D-thiogalactogalactopyranoside(IPTG)进行诱导表达,在15℃和170r/min条件下继续培养24h,表达效果最好,相对于每毫升培养基而言,产酶可达到70u/mL,是米曲霉自然条件产酶量的87·5倍,远优于文献报道的重组表达的PGA酶活。     

Sequence Analysis of Segment 8 of Five Chinese Isolates of Rice Gall Dwarf Virus and Expression of a Main Outer Capsid Protein in Escherichia coli

The rice gall dwarf disease, caused by the Rice gall dwarf virus (RGDV) is a serious disease occurring in rice in many regions of Guangdong province. As a basis to control the disease we have studied the genomic diversity of a variety of isolates from different locations. Genome segment 8(S8), encoding a main outer capsid protein (Pns8) of RGDV five isolates (BL, CH, DQ, GZ, XY) from Guangdong province was cloned and sequenced. The results revealed that all the S8 segments of the five isolates consisted of 1 578 nucleotides and had a single open reading frame (ORF) extending for 1 301 nucleotides from nucleotide 21 which encoded a polypeptide of 426 amino acids with an estimated molecular weight of 47.4 kDa. The S8 full-length sequence and the ORF sequence shared 97.3%-98.8% and 97.3%-99.1% nucleotide sequence identities within the five Chinese isolates, and shared 94.8%-95.6% and 95.0%-96.0% identities with those of the Thailand isolate respectively. The deduced amino acid sequence of Pns8 in GZ isolate was identical to that in the Thailand isolate, while the amino acid sequence variability of Pns8 within five Chinese isolates ranged from 0.5% to 2.1%. These results indicate that the S8 segment of RGDV is highly conserved in different isolates from different locations. The S8 cDNA from the XY isolate was cloned into the plasmid vector pET-28b( ) and a fused expression protein with an apparent molecular mass of 51kDa was specifically detected in an analysis of Escherichia coli Rossetta(DE3)Ⅱcells. To our knowledge, this is the first report on analysis of the RGDV segment 8 sequence and genetic comparison of different RGDV isolates and their protein expression.     

Expression and Immunoreactivity of a Human Group A Rotavirus Vp4

Rotavirus capsid protein Vp4 plays an important role in the virus adhering and entering the cells. In this study, a Vp4 gene cloned from a rotavirus strain TB-Chen was highly expressed in E.coli BL21 (DE3). The results of the Western blot showed that the protein possesses specific immuno-reactivities and can be specifically recognized by guinea pig antibodies against rotavirus strain SA11 or Wa. Some Vp4 dimers were formed during renaturation. These data obtained from this study provide a strong basis for further study on the structure and function of the Vp4.     

p38 MAPK Signal is Necessary for TNF-α Gene Expresion in RAW Cells

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Atg5 regulates late endosome and lysosome biogenesis

Autophagy is an evolutionarily conserved lysosome-based degradation process.Atg5 plays a very important role in autophagosome formation.Here we show that Atg5 is required for biogenesis of late endosomes and lysosomes in an autophagy-independent manner.In Atg5 cells,but not in other essential autophagy genes defecting cells,recycling and retrieval of late endosomal components from hybrid organelles are impaired,causing persistent hybrid organelles and defective formation of late endosomes and lysosomes.Defective retrieval of late endosomal components from hybrid organelles resulting from impaired recruitment of a component of V1-ATPase to acidic organelles blocks the pH-dependent retrieval of late endosomal components from hybrid organelles.Lowering the intracellular pH restores late endosome/lysosome biogenesis in Atg5 cells.Our data demonstrate an unexpected role of Atg5 and shed new light on late endosome and lysosome biogenesis.     

Nanoparticle mediated controlled delivery of dual growth factors

Peripheral nerve functional recovery after nerve injury generally requires multiple growth factors by synergistic effect.However,the optical combination of multiple synergistic growth factors for axonal regeneration has been scarcely considered up to now.Meanwhile,the use of growth factors in promoting nerve regeneration was limited by its short biological half-life in vivo,its vulnerability to structure disruption or hydrolyzation,leading to loss of bioactivity.Herein,a novel polymeric nanoparticle delivery system composed of heparin andε-poly-L-lysine(PL)was prepared for control release of nerve growth factor(NGF)and basic fibroblast growth factor(bFGF).The nanoparticles were synthesized by polyelectrolyte complexation in aqueous solution at room temperature,followed by cross-linking with biological genipin.The obtained nanoparticles had a spherical shape,with a mean diameter of about 246 nm,and high growth factors encapsulation efficiency as well as good stability.NGF and bFGF were encapsulated in the nanoparticles and showed a continuous and slow release behavior in vitro.The bioactivities of the released growth factors were evaluated,and exhibited the synergistic effect.The controlled release of the dual synergistic growth factors would improve the treatment of peripheral nerve injury to mimic the natural cellular microenvironments.     

Commentary on “Prevalence and evolution of drug resistance HIV-1 variants in Henan, China”

Critical to the implementation and scale-up of successful antiretroviral therapy worldwide is an understanding of the efficacy, toxicities and durability of antiretroviral regimens in the specific populations, which they are utilized. In order to obtain this information monitoring and evaluation or operational research must be done in each country or population. The article by Li et al in this issue represents an outstanding example of the importance of data obtained in the populations treated . The authors proactively evaluated the outcomes at 3 and 6 months of 118 and 124 HIV infected individuals, respectively, treated with zidovudine, didanosine and nevirapine in one region in China.