Molecular Characterization of a Bacterial Consortium Enriched from an Oilfield that Degrades Phenanthrene

Characterization of functional and phylogenetic genes was carried out on a bacterial consortium, enriched from a water treatment system of an oilfield, that could use phenanthrene as the sole carbon source. The mixed culture degraded 130 mg phenanthrene l⁻¹ in 16 days, which is significantly faster than previously reported pure cultures. The existence of catabolic genes (nahAc, C23O) in the mixed culture was quantitated by most probable number PCR. The plasmid encoding phenanthrene catabolic genes increased relative to the chromosome genes. Heterogeneous bacteria were present according to both PCR denaturing gradient gel electrophoresis and cloning methods, suggesting the possible existence of cooperation between different biochemical PAH-transforming pathways. Revisions requested 15 December 2005; Revisions received 23 January 2006     

荧光显微术在当代植物细胞生物学研究中的应用

自从八十年前第一次在显微镜下观察到生物组织经紫外线照射后发射荧光的现象以来,荧光显微术不断获得进步,现已发展成细胞生物学中一个重要的研究手段。高度的灵敏性和专一性、制样与观察程序的简便、尤其是适宜于活细胞研究等特点,是它所具有的独特长处。荧光显微术特别是免疫荧光技术在现代医学生物学研究中的应用是一个     

Antioxidant activity applying an improved ABTS radical cation decolorization assay.

A method for the screening of antioxidant activity is reported as a decolorization assay applicable to both lipophilic and hydrophilic antioxidants, including flavonoids, hydroxycinnamates, carotenoids, and plasma antioxidants. The pre-formed radical monocation of 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS*+) is generated by oxidation of ABTS with potassium persulfate and is reduced in the presence of such hydrogen-donating antioxidants. The influences of both the concentration of antioxidant and duration of reaction on the inhibition of the radical cation absorption are taken into account when determining the antioxidant activity. This assay clearly improves the original TEAC assay (the ferryl myoglobin/ABTS assay) for the determination of antioxidant activity in a number of ways. First, the chemistry involves the direct generation of the ABTS radical monocation with no involvement of an intermediary radical. Second, it is a decolorization assay; thus the radical cation is pre-formed prior to addition of antioxidant test systems, rather than the generation of the radical taking place continually in the presence of the antioxidant. Hence the results obtained with the improved system may not always be directly comparable with those obtained using the original TEAC assay. Third, it is applicable to both aqueous and lipophilic systems.     

Conformational epitope of the type III group B Streptococcus capsular polysaccharide.

The protective epitope of the type III group B streptococcal polysaccharide (GBSPIII) is length dependent and conformational. To obtain a more accurate characterization of the conformational epitope, ELISA inhibition and surface plasmon resonance studies were conducted on two GBSPIII-specific mAbs using a large panel of oligosaccharide probes. The results of the studies confirmed that 2 repeating units (RU) is the minimum binding unit and that, while increases in chain length from 2 RU to 7 RU caused further optimization of the epitope, it remained monovalent. A 3-fold increase in affinity was observed between 7 RU and 20 RU, which, by surface plasmon resonance studies on a Fab, was shown to be due to both further optimization of the individual epitope and the occurrence of multivalency of epitope. The data support our hypothesis that the conformational epitope is an extended helical segment of the GBSPIII. GBSPIII exists mainly in the random coil form, which structurally mimics short oligosaccharide self Ags, but it can infrequently and spontaneously form extended helices. Although not prevalent in GBSPIII, the immune system preferentially selects these helical epitopes because they are unique to the polysaccharide. Contrary to a previously proposed model of GBSPIII binding in which the binding of the first Ab propagates a continuum of helical epitopes, our binding kinetics are consistent only with the helical epitope's being discontinuous and infrequent.     

Structural Identification of Kudinchagenin I

A novel triterpenoid, kudinchagenin Ⅰ was isolated from the leaves of Ilex kudincha C. J. Tseng and its structure was determined to be 3β-hydroxy- 11 (12), 13 ( 18 ), 19 ( 29 ) - triene-28,20β-lactonic-ursane by a combination of spectroscopic methods and single crystal X-ray analysis.     

Protein kinase C-δ is involved in induction of <Emphasis Type="Italic">NOX1</Emphasis> gene expression by aldosterone in rat vascular smooth muscle cells

In this study, we focused on the relationship between aldosterone and NOX1 expression in vascular smooth muscle cells (VSMCs). For the first time, with the use of specific inhibitors of protein kinase C (PKC), we report that PKCδ mediates upregulation of NOX1 induced by 10 nM aldosterone in cultured VSMCs. Participation of PKC in the mediation of NOX1 regulation was further confirmed by the effect of diacylglycerol, a PKC agonist, on the NOX1 RNA in A7r5 cells with Northern blot analysis. To establish cause and effect, we next silenced the PKCδ gene partly by RNA interference and found knockdown of PKCδ gene attenuated aldosterone-induced NOX1 expression, generation of superoxide, as well as protein synthesis in VSMCs. Taken together, these data indicated PKCδ might mediate aldosterone-dependent NOX1 upregulation in VSMCs. In addition, we showed that the cascade from aldosterone to PKCδ activation had the participation of the mineralocorticoid receptor.     

The β1-adrenergic receptor mediates extracellular signal-regulated kinase activation via Gαs

β-Adrenergic receptors can activate extracellular signal-regulated kinases (ERKs) via different mechanisms. In this study, we investigated the molecular mechanism of β1-adrenergic receptor (β1AR)-mediated ERK activation in African green monkey kidney COS-7 cells. Treatment of cells with isoproterenol (ISO), a β1AR selective agonist, induced phosphorylation of ERK1/2 in a dose-dependent manner. ISO-stimulated ERK phosphorylation was not influenced by the Gβγ inhibitor, βAR kinase carboxyl terminal (βARKct) or by the Gi inhibitor, pertussis toxin (PTX), but it was clearly abolished via inhibition of protein kinase A (PKA) with H89, or of mitogen-activated protein kinase kinase (MEK1) with PD98059, revealing that the Gαs subunit is involved in ERK regulation through the PKA/MEK1 pathway. We also tested the effect of the adenylate cyclase activator forskolin on ERK activation, and the result was identical to that of ISO stimulation. Moreover, pretreatment with the epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor AG1478 or with the Src tyrosine kinase inhibitor PP2 did not affect ERK activation. These observations suggest a mechanism of β1AR-mediated ERK activity that involves the Gαs subunit, but not EGFR or Src tyrosine kinase.     

Characterization and mapping of a novel mutant sms1 (senescence and male sterility 1) in rice

Plant senescence plays diverse important roles in development and environmental responses.However,the molecular basis of plant senescence is remained largely unknown.A rice spontaneous mutant with the character of early senescence and male sterility (sms) was found in the breeding line NT10-748.In order to identify the gene SMS1 and the underlying mechanism,we preliminarily analyzed physiological and biochemical phenotypes of the mutant.The mutant contained lower chlorophyll content compared with the wild t...     

大豆初生根凯氏带对铜离子的通透性

采用在根内生成有色铜沉淀的方法研究大豆(Glycine max)初生根凯氏带对铜离子的通透性。用真空泵抽取浓度为200 μmol·L^–1 的CuSO₄溶液进入根中, 然后在重力作用下从根基部灌注400 μmol·L^–1的K₄[Fe(CN)₆]溶液, 两种物质在根内相遇即可产生棕色的Cu₂[Fe(CN)₆]沉淀, 根据沉淀的位置来确定铜离子所经过的途径。结果表明: Cu²⁺可以穿过内皮层凯氏带, 在木质部导管壁以及凯氏带至木质部之间的细胞壁处产生棕色沉淀, 侧根发生的部位也产生了大量的沉淀; 当抽取K₄[Fe(CN)₆]溶液后再灌注CuSO₄溶液, 发现Cu²⁺仍然可以穿过凯氏带, 并在凯氏带外侧以及外皮层细胞的细胞壁处产生棕色沉淀。研究结果证明凯氏带并不是一个可以完全阻止离子进出的完美屏障。     

Insect oviposition behavior affects the evolution of adaptation to <Emphasis Type="Italic">Bt</Emphasis> crops: consequences for refuge policies

The major lepidopteran insect pests of cotton and maize harbor intra-specific variation for behavior determining the selection of host plants for oviposition. Yet, the consequences of behavioral adaptation for fitness have neither been modeled nor monitored for Bt cotton and maize crops, the most widely grown transgenic herbivore-resistant plants. Here, we present a general two-locus heuristic model to examine potential outcomes of natural selection when pest populations initially have low frequencies of alleles for both physiological and behavioral adaptation to Bt crops. We demonstrate that certain ecological conditions allow for the evolution of behavioral choices favoring alternative oviposition hosts that limit the increase in resistance alleles, even when they are phenotypically dominant. These results have implications for current refuge policies, which should be adapted to promote the evolution of certain behavioral choices for alternative oviposition hosts in addition to dilution of physiological resistance alleles. Collection of data on oviposition host preference as a component of monitoring schemes will provide important insights into mechanisms underlying the durability of Bt-transgenic host-plant resistance.