The actin cytoskeleton is involved in the regulation of the plasmodesmal size exclusion limit

Plasmodesmata (PD) are the communication channels which allow the trafficking of macromolecules between neighboring cells. Such cell-to-cell movement of macromolecules is regulated during plant growth and development; however, little is known about the regulation mechanism of PD size exclusion limit (SEL). Plant viral movement proteins (MPs) enhance the invasion of viruses from cell to cell by increasing the SEL of the PD and are therefore a powerful means for the study of the plasmodesmal regulation mechanisms. In a recent study, we reported that the actin cytoskeleton is involved in the increase of the PD SEL induced by MPs. Microinjection experiments demonstrated that actin depolymerization was required for the Cucumber mosaic virus (CMV) MP-induced increase in the PD SEL. In vitro experiments showed that CMV MP severs actin filaments (F-actin). Furthermore, through the analyses of two CMV MP mutants, we demonstrated that the F-actin severing ability of CMV MP was required to increase the PD SEL. These results are similar to what has been found in Tobacco mosaic virus MP. Thus, our data suggest that actin dynamics may participate in the regulations of the PD SEL.Key words: plasmodesmata, size exclusion limit, movement protein, actin filaments, F-actin severing     

A simple and sensitive HPLC fluorescence method for determination of tadalafil in mouse plasma

A simple and sensitive high-performance liquid chromatographic (HPLC) method utilizing fluorescence detection was developed for the determination of the phosphodiesterase type 5 inhibitor tadalafil in mouse plasma. This method utilizes a simple sample preparation (protein precipitation) with high recovery of tadalafil (∼98%), which eliminates the need for an internal standard. For constituent separation, the method utilized a monolithic C₁₈ column and a flow rate of 1.0 mL/min with a mobile phase gradient consisting of aqueous trifluoroacetic acid (0.1% TFA in deionized water pH 2.2, v/v) and acetonitrile. The method calibration was linear for tadalafil in mouse plasma from 100 to 2000 ng/mL (r > 0.999) with a detection limit of approximately 40 ng/mL. Component fluorescence detection was achieved using an excitation wavelength of 275 nm with monitoring of the emission wavelength at 335 nm. The intra-day and inter-day precision (relative standard deviation, RSD) values for tadalafil in mouse plasma were less than 14%, and the accuracy (percent error) was within −14% of the nominal concentration. The method was utilized on mouse plasma samples from research evaluating the potential cardioprotective effects of tadalafil on mouse heart tissue exposed to doxorubicin, a chemotherapeutic drug with reported cardiotoxic effects.     

Bio-inorganic Synthesis of ZnO Powders Using Recombinant His-tagged ZnO Binding Peptide as a Promoter

Inorganic-binding peptides termed as genetically engineered polypeptides for inorganics (GEPIs), are small peptide sequences selected via combinatorial biology-based protocols of phage or cell surface display technologies. Recent advances in nanotechnology and molecular biology allow the engineering of these peptides with specific affinity to inorganics, often used as molecular linkers or assemblers, to facilitate materials synthesis, which provides a new insight into the material science and engineering field. As a case study on this biomimetic application, here we report a novel biosynthetic ZnO binding protein and its application in promoting bio-inorganic materials synthesis. In brief, the gene encoding a ZnO binding peptide(ZBP) was genetically fused with His₆-tag and GST-tag using E.coli expression vector pET-28a (+) and pGEX-4T-3. The recombinant protein GST-His-ZBP was expressed, purified with Ni–NTA system, identified by SDS–PAGE electrophoresis and Western blot analysis and confirmed by liquid chromatography-mass spectrometry/mass spectrometry (LC–MS/MS) analysis. Affinity adsorption test demonstrated that the fusion protein had a specific avidity for ZnO nanoparticles (NPs). Results from the bio-inorganic synthesis experiment indicated that the new protein played a promoting part in grain refinement and accelerated precipitation during the formation of the ultra-fine precursor powders in the Zn(OH)₂ sol. X-ray diffraction (XRD) analysis on the final products after calcining the precursor powders showed that hexagonal wurtzite ZnO crystals were obtained. Our work suggested a novel approach to the application about the organic–inorganic interactions.     

Morphological and molecular characterization of <Emphasis Type="Italic">Mariannaea aquaticola</Emphasis> sp. nov. collected from freshwater habitats

Mariannaea aquaticola sp. nov. is described, illustrated, and compared with closely related taxa. Phylogenetic analysis of rDNA ITS and 28S sequences show that Mariannaea aquaticola has affinity with Nectriaceae, which is in agreement with other Mariannaea species. Other morphologically similar genera such as Verticillium and Clonostachys are shown to be phylogenetically distant to Mariannaea. The generic concept of Mariannaea is discussed, and the affinity to Nectriaceous teleomorphs is suggested as additional generic character. A key to Mariannaea species is provided.     

FTA-DNA直接提取法在病原真菌分子鉴定中的应用

目的建立并评价FTA-DNA直接提取法在病原真菌分子鉴定中的应用。方法采用whatman FTA-DNA直接提取法从25个不同种属的45株培养的菌株和6例临床标本中提取病原真菌DNA,用于病原真菌的测序鉴定。配制不同浓度的孢子悬液探索该方法的检测限和安全性。结果 45株菌株扩增后均能得到1条清晰的DNA扩增片段,并成功测序。应用该方法亦成功从腹水、胸水、口腔拭子、宫颈拭子来源的临床标本中直接提取DNA并成功鉴定病原真菌。该DNA提取方法联合降落PCR能检测到1.0×103个cell/mL的孢子悬液,1.0×104个cell/mL及以下浓度的孢子悬液可以被FTA卡完全灭活。结论 FTA-DNA直接提取法可快速有效地从培养的菌株及部分临床标本中提取并保存病原真菌DNA,用于病原真菌的测序鉴定。     

水鳖蕨配子体系统学特征的培养观察

在光学显微镜下观察了水鳖蕨(Sinephropteris delavayi(Franch.)Mickel)配子体发育的详细过程。水鳖蕨孢子培养6 d左右萌发;原丝体单列细胞,或发育出2~3个分支;片状体生长点不明显,成熟配子体近心形。本文还讨论了其生长点、毛状体及性器的发育特点,结果支持Mickel将水鳖蕨独立成属的观点。     

Cardioprotection in ischemia/reperfusion injury: Spotlight on sphingosine-1-phosphate and bradykinin signalling

Complex signal-transduction cascades are known to be involved in regulating cardiomyocyte function, death and survival during acute cardiac ischemia-reperfusion process, but detailed survival signalling pathways are not clear. This review presents and discusses the recent findings bearing upon the evidence on the cardioprotective effect of sphingosine-1-phosphate (S1P) and bradykinin in acute cardiac ischemia-reperfusion and underlying signalling mechanisms, particularly, through activation of P21 activated kinase.     

The alternative pathway in cucumber seedlings under low temperature stress was enhanced by salicylic acid

The alternative pathway is a cyanide-resistant and non-phosphorylatory electron transport pathway in mitochondria of higher plants. Alternative oxidase (AOX) is the terminal oxidase of this pathway. Our present study investigated the effect of exogenous salicylic acid (SA) on alternative pathway in cucumber (Cucumis sativus L.) seedlings under low temperature stress. Results showed that during the process of low temperature stress, the alternative pathway capacity was enhanced as AOX expression increased in SA pretreated seedlings. Compared with seedlings without SA pretreatment, slower decrease of relative water content and lower levels of electrolyte leakage, H₂O₂ and malonyldialdehyde content were detected in SA pretreated seedlings. These results indicated that SA could alleviate the injury caused by low temperature on cucumber seedlings. Since the special protective functions of alternative pathway and AOX in plants, we suggested that the alternative pathway was related to SA-mediated plant resistance to environmental stresses such as low temperature.     

Functional characterization of the translationally controlled tumor protein (<Emphasis Type="Italic">TCTP</Emphasis>) gene associated with growth and defense response in cabbage

The translationally controlled tumor protein (TCTP) is an important component of the target of rapamycin (TOR) signaling pathway, the major regulator of cell growth in animals and fungi. Despite its relevance, knowledge on plant TCTP homologs is still limited. In the present study, the full-length BoTCTP cDNA was isolated from a cabbage (Brassica oleracea L.) cDNA library. The BoTCTP cDNA encodes a polypeptide of 168 amino acids and shared the highly conserved GTPase binding surface in all of the species analyzed. Northern blotting analysis showed that BoTCTP was specifically expressed in the root and stem. Furthermore, the expression of BoTCTP could be obviously enhanced by stress stimuli, including high temperature and salt stresses, while no significant changes in the BoTCTP expression were observed under ABA stress. Functional analysis of BoTCTP was performed by the silencing of BoTCTP using RNA interference (RNAi) and the BoTCTP RNAi plants exhibited reduced vegetative growth rate and decreased tolerance of the cold, high temperature, and salt stresses. The reported results clearly suggest that the BoTCTP gene is involved in the regulation of both growth and stress response in cabbage.     

A multiplex PCR method to detect 14 Escherichia coli serogroups associated with urinary tract infections

Urinary tract infections (UTIs) are one of the most common bacterial infections and are predominantly caused by uropathogenic Escherichia coli (UPEC). E. coli strains belonging to 14 serogroups, including O1, O2, O4, O6, O7, O8, O15, O16, O18, O21, O22, O25, O75 and O83, are the most frequently detected UPEC strains in a diverse range of clinical urine specimens. In the current study, the O-antigen gene clusters of E. coli serogroups O1, O2, O18 and O75 were characterized. A multiplex PCR method based on O-antigen-specific genes was developed for the simultaneous detection of all 14 E. coli serogroups. The multiplex PCR method was shown to be highly specific and reproducible when tested against 186 E. coli and Shigella O-serogroup reference strains, 47 E. coli clinical isolates and 10 strains of other bacterial species. The sensitivity of the multiplex PCR method was analyzed and shown to detect O-antigen-specific genes in samples containing 25 ng of genomic DNA or in mock urine specimens containing 40 colony-forming units (CFUs) per ml. Five urine specimens from hospital were examined using this multiplex PCR method, and the result for one sample was verified by the conventional serotyping methods. The multiplex PCR method developed herein can be used for the detection of relevant E. coli strains from clinical and/or environmental samples, and it is particularly useful for epidemiologic analysis of urine specimens from patients with UTIs.