影响德氏乳杆菌乳酸亚种H~+-ATPase活性的因素

通过测定四株德氏乳杆茵乳酸亚种H+-ATPase的活性,确定反应温度、pH值、底物添加量、培养时间以及金属离子对酶活性的影响.实验结果表明,德氏乳杆菌乳酸亚种H+-ATPase的最适反应条件为:温度42℃;pH 7.5;ATP添加量为3 mmol/L;茵株最适培养时间为8 h和24 h.Mg2+、Na+、K+对四株茵的H+-ATPase活性均有促进作用,Mn2+、Ba2+、Al3+、Li+对这4株茵的H+-ATPase活性有不同程度的抑制作用,其中Mg2+的促进作用最明显,而Al3+的抑制作用最明显.     

Modelling pathogen competition and displacement– <Emphasis Type="Italic">Phytophthora infestans</Emphasis> in Scandinavia

Populations of Phytophthora infestans have displaced less fit populations in a number of regions, but not in Scandinavia. In order to study this process, a simple epidemic model was developed, based on the Lotka-Volterra model for competition. The model contains two epidemics, each with logistic growth of two separate populations that interact with each other in that they compete for the same resource base (the plant). In Scandinavia, epidemics from suspected oospore infections are thought to start earlier than those originating from tubers, so routines were added to allow the epidemics to start at different time points. A numerical solution to the model was developed using the deSolve package of the open-source statistical program ‘R’. The resulting model allows examination of the relative importance of different values for the apparent infection rates and starting parameters for the two sub-epidemics. If epidemics from oospore infections start earlier than those from tuber infections, the delay for epidemic initiation via tuber infection would require extremely high values of r in order for this population to dominate at the end of the season. This could be one reason for the lack of persistent clones in the Scandinavian Phytophthora infestans population.     

Phytophthora infestans in a single field in southwest Sweden early in spring: symptoms, spatial distribution and genotypic variation

Sixty-eight isolates of Phytophthora infestans were collected from an early planted, fleece-protected potato field in southwest Sweden in May 2001. No infection was observed in the neighbouring fields. In the field investigated, infected plants were found in six discrete foci, with symptoms almost exclusively observed in the lower part of the canopy and numerous infections found on stems and on leaves touching the ground. The structure of the population was analysed based on mating type, mitochondrial haplotype and microsatellites (SSRs) as markers. Both mating types were present and haplotypes Ia and IIa were detected. Among 61 isolates analysed with microsatellite markers, 14 multilocus genotypes were distinguished based on six polymorphic loci. Out of the six foci, three included 3–5 genotypes each. There were unique genotypes in all foci, except two closely situated to each other. These findings strongly suggest that soilborne oosporic inoculum contributed significantly to initiate the late-blight epidemic in the investigated field.     

Virulence spectrum of Puccinia hordei in barley production systems in Ethiopia

Barley leaf rust caused by Puccinia hordei is an important disease of barley in Ethiopia. In the 2003 and 2004 cropping seasons, surveys of P. hordei were conducted on fields in the main rainy, residual moisture and short rainy season-barley production systems. A total of 381 isolates were analysed on 12 barley differential hosts carrying different Rph resistance genes ( Rph1 – Rph12 ). Based on infection phenotypes on leaf rust ( Rph ) resistance genes, seven pathotypes were identified, namely ETPh7611, ETPh7631, ETPh6611, ETPh7651, ETPh7671, ETPh7653 and ETPh7633, with frequencies of 63·0, 21·5, 6·8, 2·9, 2·6, 2·1 and 1·2%, respectively. ETPh7611 and ETPh7631 were the most common pathotypes found in all the surveyed areas of the three production systems. ETPh7653 was found in the small rainy season production system only. ETPh7671, ETPh7653 and ETPh7633 were the most virulent, but the least frequent, pathotypes. All isolates were virulent on resistance genes Rph1 , Rph4 , Rph8 , Rph9 , Rph11 and Rph12 . Virulence against Rph3 and Rph7 was absent. Genes Rph2 , Rph6+2 , Rph5 and Rph10 were effective against 96·3, 88·9, 65 and 2·4% of the rust isolates tested, respectively.     

Characteristics of silver-plated silk fabric with plasma pre-treatment

Plasma gases of oxygen and argon were employed for pre-treating silk fabric before conducting electroless silver plating in this study. The effect of plasma pre-treatment with oxygen and argon gases on the electroless silver-plated silk fabric was investigated. Based on the observation of micro-structure using SEM, it was found that there was an increase in the amount of silver particles deposited on the silk fibre surface after plasma pre-treatment. The functional properties of plasmainduced electroless silver-plated silk fabrics were also evaluated. The increase in weight of the silver-plated silk after plasma pre-treatment was determined. When compared, the oxygen plasma treatment could improve the effect of silver plating on the silk fabric. Additionally, anti-static, anti-bacterial, UV protection and water-repellent properties of the silver-plated silk fabric were determined in this study.     

Effect of different human hair bleaching conditions on the hair coloration with hair boosting shampoo as colorant

In this paper, detailed simulation of human hair bleaching was conducted. The materials and chemical used as well as the hair bleaching procedures were described. After bleaching, the colour change of the hair was evaluated in accordance with CIE Lab system and the hair bleaching results was analysed. Following the hair bleaching process, hair coloration was employed with the use of colour boosting shampoo with henna of three different colours. The effect of different bleached hair samples on colour uptake property was examined by spectrophotometer method. Based on this study, it was concluded that the original hair colour did affect the colour uptake using the colour boosting shampoo with henna significantly. In order to have a visible coloring result, hair bleaching treatment was therefore highly recommended before conducting the hair coloration process.     

Fungicide sensitivity in Swedish isolates of Phaeosphaeria nodorum

This is the first report of variability in sensitivity of Phaeosphaeria nodorum to the fungicide azoxystrobin, and also reports on sensitivity to propiconazole, prothioconazole and cyprodinil. An in vitro sensitivity test of 42 isolates from five Swedish winter wheat fields, collected in 2003–2005, was performed on malt extract agar amended with six concentrations of each fungicide. Four isolates collected during the early 1990s, before azoxystrobin had been commercially used in agriculture, were used as references. Fragments of DNA from 231 isolates, including the reference isolates, were sequenced for the genes of cytochrome b and CYP51 in search for amino acid substitutions known to cause loss of sensitivity to strobilurins and triazoles, respectively. The majority of the P. nodorum isolates possessed the amino acid substitution G143A, associated with loss of sensitivity in fungi to strobilurins, except in one field where only half of the isolates had the substitution. The EC₅₀ values varied between 0·66 mg L⁻¹ to estimations far above 1000 mg L⁻¹, with an estimated median value of 366 mg L⁻¹. The EC₅₀ values of the reference isolates ranged from 0·02 to 80·72 mg L⁻¹. The P. nodorum population is still sensitive to propiconazole, prothioconazole and cyprodinil, even though some isolates varied in sensitivity to triazoles. Part of the CYP51 gene, a possible target for triazole sensitivity, was sequenced but no nonsynonymous substitutions were found.     

Influence of deposition parameters and kinetics of electroless Ni-P plating on polyester fiber

The electroless nickel-phosphorous (Ni-P) plating on polyester fiber using sodium hypophosphite as a reducing agent in alkaline medium was studied. The effects of plating parameters including concentrations, pH and bath temperature of the plating bath on deposition rate of the electroless Ni-P plating were investigated. The results reveal that the deposition rates increase with the increase in the concentration of nickel sulfate, sodium hypophosphite, pH and bath temperature, respectively. However, it is determined that the deposition rates decrease with the rise of sodium citrate. The kinetics of the deposition reaction was investigated and an empirical rate equation for electroless Ni-P plating on polyester fiber was developed.     

Polyethylenimine-based amphiphilic core-shell nanoparticles: study of gene delivery and intracellular trafficking

Amphiphilic core-shell nanoparticle, which is composed of a hydrophobic core and a branched polyethylenimine (PEI) shell, has been designed and synthesized as a novel gene delivery nanocarrier. In our previous study, we demonstrated that the core-shell nanoparticle was not only able to efficiently complex with plasmid DNA (pDNA) and protect it against enzymatic degradation, but also three times less cytotoxic, and threefold more efficient in gene transfection than branched 25 kDa PEI. This paper reports our further studies in the following three aspects: (1) the ability of the PEI-based nanoparticles to deliver gene in various mammalian cell lines; (2) intracellular distributions of the nanoparticles and their pDNA complexes in HeLa cells; and (3) incorporation of nuclear targeting agent into the nanoparticle/pDNA complexes to enhance the nuclear targeting ability. The PEI-based nanoparticles were able to transfect both human and non-human cell lines and their transfection efficiencies were cell-dependent. Within our four tested cell lines (MCF-7, BEL 7404, C6 and CHO-K1), gene transfer using PEI-based core-shell nanoparticles displayed gene expression levels comparable to, or even better than, the commercial Lipofectamine? 2000. Confocal laser scanning microscopy showed that the nanoparticles and their pDNA complexes were effectively internalized into the HeLa cells. The in vitro time series experiments illustrated that both the nanoparticle/pDNA complexes and PEI-based nanoparticles were distributed in the cytoplasmic region after transfection for 10 and 60 min, respectively. Nuclear localization was also observed in both samples after transfection for 20 and 60 min, respectively. Incorporation of the high mobility group box 1 (HMGB1) protein for nuclear targeting has also been demonstrated with a simple approach: electrostatic complexation between the PEI-based nanoparticles and HMGB1. In the in vitro transfection study in MCF-7 cells, the expression level of the firefly luciferase gene encoded by the pDNA increased remarkably by up to eightfold when the HMGB1 protein was incorporated into the nanoparticle/pDNA complexes. Our results demonstrate that the PEI-based core-shell nanoparticles are promising nanocarriers for gene delivery.     

Optimum condition of ink-jet printing for wool fabric

This paper is aimed at studying the optimum content of pre-treatment print paste used for ink-jet printing of wool fabric. Optimum condition of ink-jet printing with respect to the content of pre-treatment print paste and steaming time has been successfully developed through the orthogonal analysis. The parameters of the pre-treatment print paste including sodium alginate, urea and ammonium tartrate, as well as the post-treatment of steaming time right after ink-jet printing have been investigated. The optimum content of the pre-treatment print paste and the proper condition of post-treatment has been developed to achieve higher colour yield for cyan, yellow, magenta and black color (CYMK). The results of the highest colour yield obtained confirm that steaming time is the most dominating factor when compared with the other factors.