保山地区碱性温泉中的高温菌

保山地区位于云南省西部,是全省温泉分布比较密集的地区之一。温泉作为地热资源已引起有关部门的重视,70年代已进行了地热资源的调查和开发利用研究。但是对于温泉中潜在的高温菌资源,尚未进行过系统考察、研究。现将我们对于保山地区pH8.0以上的高温温泉中的高温菌研究结果报告于后。       

Formation of Ascorbate Oxidase in Cultured Pumpkin Cells

Ascorbate oxidase activity rapidly increased during callus formationfrom pumpkin fruit tissue. The activity reached a maximum at5 days after transfer and then declined. In callus which hadbeen subcultured at about 4-week intervals for more than oneyear, the activity also increased after transfer to fresh mediumand reached a maximum in the early logarithmic phase of growth.Light had little effect on the appearance of ascorbate oxidaseactivity in pumpkin callus. In the callus grown in the presenceof 10µM CuSO₄, the activity was about 10 times that inthe presence of 0.1 µM CuSO₄, suggesting that the formatonof ascorbate oxidase in pumpkin callus is stimulated by copper,a prosthetic metal of the enzyme. From 45 to 75% of the totalascorbate oxidase activity in pumpkin cell suspension cultureswas found in the medium. Ascorbate oxidase activity in the medium,as well as that in the cells, increased soon after transferto fresh medium, and reached a maximum at about 5 days. (Received July 2, 1987; Accepted November 21, 1987)     

QTL mapping of phosphorus efficiency and relative biologic characteristics in maize (Zea mays L.) at two sites

The phosphorus efficiency, relative biologic characteristics and relative root exudations as well as the quantitative trait loci associated with these traits were determined for an F_2:3 population derived from the cross of two contrasting maize (Zea mays L.) genotypes, 082 and Ye107. A total of 241 F_2:3 families were evaluated in replicated trials under normal phosphorus (50 kg P/ha) and low phosphorus (0 kg P/ha) conditions in 2007 at two sites (Kaixian and Southwest University). The genetic map constructed by 275 SSR and 146 AFLP markers spanned 1,681.3 cM in length with an average interval of 3.84 cM. The heritability of PE, PAE, RPH, RBW, RRW, RLA, TPS, RTW, RFN, RAP and RH was all high ( $h_{\text{b}}^2 > 60\% $ ) whereas the heritability of root exudations was all low ( $h_{\text{b}}^2 > 60\% $ ).By using composite interval mapping (CIM), a total of 30 and 45 distinct QTLs were identified at Kaixian and Southwest University. At two sites, the number of same QTL located on common region was 16, five for PE (bins 1.07, 4.09, 5.05, 5.07, 5.08), three for RBW (bins 3.04, 5.04, 6.05), three for RRW (bins 5.05, 5.06, 5.07), one for RLA (bins 3.04), two for TPS (bins 3.08, 5.07), two for RTW (bins 5.05, 5.06). These QTLs explained 21% of the phenotypic variation of PE, 5–9% of RBW, 13–16% of RRW, 9% of TPS, 7% of RTW, respectively. The 16 common QTLs displayed mostly partial dominance or over-dominance gene action. Most QTL alleles conferring high values for the traits came from two parents. Mapping analysis identified chromosomal regions associated with two or more traits in a cluster, which was consistent with correlation among traits. The result showed either pleiotropy or tight linkage among QTL. Five common regions for same QTL at different site were found in the interval bnlg1556-bnlg1564 (bins 1.06), mmc0341-umc1101 (bins 4.08), mmc0282-phi333597 (bins 5.05), bnlg1346-bnlg1695 (bins 5.07) and bnlg118a-umc2136 (bins 5.08), which were important for PE. The information reported in the present paper may be useful for improving phosphorus efficiency by means of marker-assisted selection.     

高产信号分子AI-2乳酸菌的筛选及其Pfs基因的克隆和表达

【目的】从锡盟地区酸马奶酒分离的乳酸菌中筛选出高产信号分子自体诱导物2(Autoinducer-2,AI-2)的乳酸菌,通过优化其重组蛋白Pfs的诱导条件体外合成信号分子AI-2。【方法】利用生物学发光法对不同乳酸菌产信号分子AI-2的产量进行比较,以高产信号分子AI-2乳酸菌基因组DNA为模板,扩增其S-腺苷高半胱氨酸核苷酶(S-adenosylhomocysteine nucleosidase,Pfs)基因,构建原核表达载体。利用异丙基-β-D-硫代吡喃半乳糖苷(IPTG)进行重组蛋白的诱导表达,通过优化培养基、诱导温度、诱导前菌体密度、IPTG浓度以及诱导时间得到高表达的Pfs蛋白,使其与底物作用最终体外合成信号分子AI-2。【结果】10株乳酸菌均可产信号分子AI-2,其中屎肠球菌8-3分泌信号分子AI-2的产量明显高于其他菌株;重组蛋白的最佳诱导条件为:选取SOC(Super optimal broth with catabolite repression)作为诱导表达培养基,菌液OD600为0.5–0.7时加入终浓度为0.1 mmol/L的IPTG,37°C诱导12 h;利用最优诱导条件获得了浓度为4.08 g/L的纯化Pfs蛋白,体外合成了信号分子AI-2。【结论】酸马奶酒中分离出的10株乳酸菌均可产生信号分子AI-2,且屎肠球菌8-3可通过Pfs基因的作用生成信号分子AI-2。     

Expression of Kv1.2 in microglia and its putative roles in modulating production of proinflammatory cytokines and reactive oxygen species

Microglial cells are endowed with different potassium ion channels but their expression and specific functions have remained to be fully clarified. This study has shown Kv1.2 expression in the amoeboid microglia in the rat brain between 1 (P1) and 10 (P10) days of age. Kv1.2 expression was localized in the ramified microglia at P14 and was hardly detected at P21. In postnatal rats exposed to hypoxia, Kv1.2 immunoreactivity in microglia was markedly enhanced. Quantitative RT-PCR analysis confirmed Kv1.2 mRNA expression in microglial cells in vitro . It was further shown that Kv1.2 and protein expression coupled with that of interleukin 1β (IL-1β) and tumor necrosis factor-α (TNF-α) was significantly increased when the cells were subjected to hypoxia. The same increase was observed in cells exposed to adenosine 5'-triphosphate (ATP) and lipopolysaccharide (LPS). Concomitantly, the intracellular potassium concentration decreased significantly. Blockade of Kv1.2 channel with rTityustoxin-Kα (TsTx) resulted in partial recovery of intracellular potassium concentration accompanied by a reduced expression of IL-1β and TNF-α mRNA and protein expression and intracellular reactive oxygen species (ROS) production. We conclude that Kv1.2 in microglia modulates IL-1β and TNF-α expression and ROS production probably by regulating the intracellular potassium concentration.     

益智不同组织多糖含量及其生物合成途径分析

为了解益智（Alpinia oxyphylla）多糖生物合成途径关键酶功能,对其茎、叶、果实中的多糖含量及其单糖组成进行了研究,并采用Real-Time qPCR分析了益智多糖生物合成关键酶基因的表达模式。结果表明,益智多糖含量依次为果实 > 叶 > 茎,主要由葡萄糖、木糖、甘露糖、半乳糖和阿拉伯糖组成;利用益智转录组数据共获得47 690条unigenes,其中31 892条在NR、Swiss-Prot、KEGG、COG、KOG、GO和Pfam数据库获得注释,其中208个unigenes参与益智多糖的生物合成,涉及15个酶。表达分析表明,所筛选的18个基因在茎、叶、果实中均有表达,14个基因在果实中的表达量最高,以糖基转移酶基因和UDP-葡萄糖焦磷酸化酶基因的表达量最高,且其表达模式与不同组织中葡萄糖含量的变化一致。     

Effects of AM Inoculation and Organic Amendment, Alone or in Combination, on Growth, P Nutrition, and Heavy-Metal Uptake of Tobacco in Pb-Cd-Contaminated Soil

As toxic pollutants commonly found in tobacco (Nicotiana tabacum L.) products, lead (Pb) and cadmium (Cd) can enter the human body via smoking and thus pose a potential health risk to smokers. We conducted a greenhouse experiment to study the effects of arbuscular mycorrhizal (AM) inoculation with Glomus intraradices BEG 141 and organic amendment with cattle manure, alone or in combination, on the growth, P nutrition, and heavy-metal uptake by tobacco plants grown in soil to which was added Pb-Cd at 0/0, 350/1, 500/10, and 1,000/100?mg?kg^?1, respectively. In general, AM colonization and plant growth were greatly reduced by Pb-Cd contamination, whereas organic amendment alleviated Pb-Cd stress and showed some beneficial effects on AM symbiosis and some soil parameters. AM inoculation, alone or in combination with organic amendment, increased plant dry weights and improved P nutrition significantly at all Pb-Cd addition levels, and, in most cases, it decreased Pb and Cd concentrations in tobacco plants and DTPA-extractable concentrations in soil. AM inoculation increased total glomalin-related soil protein (GRSP) concentrations in soil to which Pb-Cd was added. The higher soil pH and GRSP contents and the lower DTPA-extractable Pb and Cd concentrations contributed by AM inoculation and/or organic amendment may be contributing factors that lead to higher growth promotion and lower metal toxicity and uptake by plants. Our findings suggest that AM inoculation in combination with organic manure may be a potential method for not only tobacco production but phytostabilization of Pb-Cd-contaminated soil.     

Synthesis of 4-hydroxyisoleucine by the aldolase-transaminase coupling reaction and basic characterization of the aldolase from Arthrobacter simplex AKU 626

Arthrobacter simplex AKU 626 was found to synthesize 4-hydroxyisoleucine from acetaldehyde, alpha-ketobutyrate, and L-glutamate in the presence of Escherichia coli harboring the branched chain amino acid transaminase gene (ilvE) from E. coli K12 substrain MG1655. By using resting cells of A. simplex AKU 626 and E. coli BL21(DE3)/pET-15b-ilvE, 3.2 mM 4-hydroxyisoleucine was produced from 250 mM acetaldehyde, 75 mM alpha-ketobutyrate, and 100 mM L-glutamate with a molar yield to alpha-ketobutyrate of 4.3% in 50 mM Tris-HCl buffer (pH 7.5) containing 2 mM MnCl(2) x 4H(2)O at 28 degrees C for 2 h. An aldolase that catalyzes the aldol condensation of acetaldehyde and alpha-ketobutyrate was purified from A. simplex AKU 626. Mn(2+) and pyridoxal 5'-monophosphate were effective in stabilizing the enzyme. The native and subunit molecular masses of the purified aldolase were about 180 and 32 kDa respectively. The N-terminal amino acid sequence of the purified enzyme showed no significant homology to known aldolases.     

Electron tomography of viruses

Understanding the molecular architectures of enveloped and complex viruses is a challenging frontier in structural biology. In these viruses, the structural and compositional variation from one viral particle to another generally precludes the use of either crystallization or image averaging procedures that have been successfully implemented in the past for highly symmetric viruses. While advances in cryo electron tomography of unstained specimens provide new opportunities for identification and molecular averaging of individual subcomponents such as the surface glycoprotein spikes on purified viruses, electron tomography of stained and plunge-frozen cells is being used to visualize the cellular context of viral entry and replication. Here, we review recent developments in both areas as they relate to our understanding of the biology of heterogeneous and pleiomorphic viruses.     

The Diversity and Anti-Microbial Activity of Endophytic Actinomycetes Isolated from Medicinal Plants in Panxi Plateau,China

Traditional Chinese medicinal plants are sources of biologically active compounds, providing raw material for pharmaceutical, cosmetic and fragrance industries. The endophytes of medicinal plants participate in biochemical pathways and produce analogous or novel bioactive compounds. Panxi plateau in South-west Sichuan in China with its unique geographical and climatological characteristics is a habitat of a great variety of medicinal plants. In this study, 560 endophytic actinomycetes were isolated from 26 medicinal plant species in Panxi plateau. 60 isolates were selected for 16S rDNA-RFLP analysis and 14 representative strains were chosen for 16S rDNA sequencing. According to the phylogenetic analysis, seven isolates were Streptomyces sp., while the remainder belonged to genera Micromonospora, Oerskovia, Nonomuraea, Promicromonospora and Rhodococcus. Antimicrobial activity analysis combined with the results of amplifying genes coding for polyketide synthetase (PKS-I, PKS-II) and nonribosomal peptide synthetase (NRPS) showed that endophytic actinomycetes isolated from medicinal plants in Panxi plateau had broad-spectrum antimicrobial activity and potential natural product diversity, which further proved that endophytic actinomycetes are valuable reservoirs of novel bioactive compounds.