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Wei Yang, Lei Ji, Li-Rong Tan, Shi-Mo Li, Yan Wang, Hong-Xia Liu*, and Yu-Ming Luo*
Abstract: One pair of primers was designed based on the sequence of tmr locus for specific and sensitive detection of Agrobacterium tumefaciens. Only the A. tumefaciens strain can produce the 236bp target fragment among the fourteen bacterial species that tested. The sensitivity of the specific PCR system was determined by a nested-PCR amplification which can numbered the copies of the template DNA. According to the results, it can give positive band when only 100 copies were in the template. The protocol was carried out for detection A. tumefaciens of twelve soil samples collected from six different gardens in Shanghai where crown gall happened. Two of the samples which collected from symptomless gardens also give the positive band. Based on the results we can make a conclusion that this pair of primers can be a useful tool in detecting A. tumefaciens, especially in detecting latent infection of this devastating pathogen.[...] Read More.
Keywords: Agrobacterium tumefaciens, detection, polymerase chain reaction (PCR).
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Ali M. Elshafei*, Latifa A. Mohamed and Mohamed M. Hassan
Abstract: Cell-free extracts of nitrate-grown Penicillium viridicatum could catalyze the hydrolytic cleavage of N-glycosidic bond of adenosine, guanosine and inosine to the corresponding base and ribose by a ribonucleoside hydrolase; however, there is no evidence for the degradation of these compounds through phosphorylation. The rate of hydrolysis of the three ribonucleosides was in the order inosine> guanosine> adenosine. It was proven that adenosine hydrolyzing enzyme is not associated with the cell membrane. Maximum enzyme activity was observed at pH 4 and 50°C. Heat inactivation kinetics and the effect of the nature of the buffer on enzyme activity revealed that, the cleavage of the three purine ribonucleosides is affected by one intracellular nucleoside hydrolase. It was proven experimentally that, all the metal ions tested had a remarkable inhibitory effect on the activity of the ribonucleoside hydrolase. Results obtained indicate that extracts of P. viridicatum catalyzed the conversion of guanosine into guanine and ribose by a nucleoside hydrolase and the resulting guanine was then deaminated to xanthine by an inducible guanine deaminase. In addition, xanthosine was not split into ribose and xanthine by the same extracts under the same experimental conditions and even at different pH values of the reaction mixture.[...] Read More.
Keywords: Purine ribonucleosides, adenosine, guanosine, inosine, hydrolase, Penicillium viridicatum.
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Ekrem Kirecci*, Suleyman Aslan and Nevin Turut
Abstract: In this study, we aim to perform a microbiological evaluation on the anthrax cases encountered in small and large ruminants as well as in equidae in the Eastern Mediterranean region of Turkey between March 2005 and July 2010. Blood specimens from 44 animals raised in the Mediterranean region of Turkey and suspected of having anthrax in light of the clinical examination results between 2005 and 2010, were subjected to bacteriological analysis. Conventional methods such as Giemsa and Gram staining as well as culture and motility tests were carried out. Smears prepared from blood specimens were treated with Giemsa and Bacillus anthracis pathogens with typical capsules were investigated. During culture test, specimens were cultivated in nutrient broth, blood agar, and MacConkey agar after which they were incubated at 37°C for 24 - 48 h in an aerobic environment. Colony morphologies and microscopic appearances of the bacteria that grew in the nutrient broth and blood agar were evaluated. Thus, bacteria displaying an appearance of typical hair-like shape and a configuration of long chains similar to bamboo sticks, with nonmotile and R-form like colony view, were diagnosed as B. anthracis. The animals with suspected anthrax in this study were comprised of 19 cattle, 14 goats, 10 sheeps and 1 mule. In 12 (27.3%) of 44 specimens, B. anthracis was isolated and identified. B. anthracis was isolated from the animals with suspected anthrax. Anthrax, recognized as a dangerous zoonosis across the entire world, is still of endemic status in our country and preventive measures should include prevention of illegal animal slaughter by performing efficient supervision, applying routine vaccination programs and raising awareness among the livestock owners.[...] Read More.
Keywords: Anthrax, animals, Bacillus anthracis, pathogens.
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Xin-sheng Liu, Yong-lu Wang*, Yong-guang Zhang, Yu-zhen Fang, Li Pan, Jian-liang Lü, Peng Zhou, Zhong-wang Zhang, Cheng Qi-wei, Gang Wang, Ji-wei Wang, Hui Lou and Shou-tian Jiang
Abstract: Structural protein VP1 of foot-and-mouth disease virus (FMDV) is the most frequently studied protein due to its significant roles in virus attachment, protective immunity, and serotype specificity. The coding sequence of VP1was amplified and then identified by polymerase chain reaction (PCR) and sequencing. To achieve high-level expression of VP1 protein, we optimized VP1 gene base on Escherichia coli preferred codons and synthesized the optimized gene. The synthetical gene was cloned into the fusion expression vector pET-28a and expressed in E. coli BL21(DE3). After induced with Isopropyl -D-1-Thiogalactopyranoside (IPTG) and optimized the conditions of expression, the VP1 fusion protein was highly expressed and identified in inclusion bodies by SDS-PAGE and Western blotting. Based on the primary and secondary structure analysis of VP1, Three-dimensional structure of VP1 was developed by homology modeling methods. The validation of 3-D structure was done with the help of PROCHECK encompassing amino acid residues in the most favored region of almost all strains. Potential epitopes of VP1 was predicted with different methods. In this study, the VP1 protein was expressed in E. coli efficiently and highly purified VP1 was obtained, which laid a foundation of refolding and further study on activity of the protein. The VP1 model in the productive conformation can now be used for structure-based design purposes as well as structure-function relation of VP1 protein.[...] Read More.
Keywords: Foot-and-mouth disease virus, VP1 protein, codon optimization, homology modeling.
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文章
K. A. Yongabi*, D. M. Lewis and P. L. Harris
Abstract: Findings from a preliminary lab-scale study show strong potentials of phytodisinfectants as a low-cost, appropriate and ecological alternative technology in purifying water in rural Cameroon. A survey of plants used in water purification in Bamenda, Cameroon, indicated that there are many plants used in water treatment. A rapid screening on the coagulative and disinfection potential of four most frequently used plants was carried out on; Moringa oleifera, Jatropha curcas, calyx of Hibiscus sabdarifa, sclerotium of Pleurotus tuberregium against their crude methanol extracts, aluminum sulphate and sodium hypochlorite controls on turbid surface water samples. A beaker experiment with varying weights (0.5 to 5 g) of dried pulverized plant materials and alum (control) were placed in 200 ml each of the three-turbid water samples and left for thirty minutes retention time. A 95% reduction in bacterial loads of the water samples by M. oleifera in fifteen minutes residence time was observed. J. curcas seeds, as well as H. sabdarifa calyx also reduced the bacterial loads between 75 to 90%. All the plant extracts except P. tuberregium inhibited an Escherichia coli isolate from the turbid water with highest zone of inhibition (15 mm) recorded for M. oleifera seed extract. The inhibition zones produced by three of the plant extracts were comparable to aluminum sulphate (6 mm) and sodium hypochlorite (17 mm). Crude methanol extracts from M. oleifera seeds, J. curcas seeds and H. sabdariffa calyx used directly on turbid water drastically reduced the total aerobic mesophilic bacterial counts far more than the unextracted plant powders. The turbidity of both phytodisinfectant and alum treated water samples drastically reduced while no turbidity reduction was observed with sodium hypochlorite treated water samples. The pH of alum treated water was observed to decrease from neutral to 5.0 while pH of phytocoagulant treated water was 7.0. This report suggest that M. oleifera seeds, J. curcas seeds and calyx of Hibiscus sabdariffa posses both phytodisinfectant and phytocoagulant property in water purification. Scerotium of P. tuberregium poses only phytocoagulant (mycocoagulant) activity. Plant materials can be used as phytocoagulants and phytodisinfectants in treating turbid water and can be applied in wastewater treatment. Further studies on the application of Phytodisinfectants in domestic water purification, especially the phytodisinfection potentials of M. oleifera are exigent.[...] Read More.
Keywords: Phytodisinfectants, phytobiotechnology, phytocoagulants, bacteria turbid water, plants, Moringa oleifera, Cameroon.
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文章
Guo Shaoxia,* Han Tingting and Liu Runjin
Abstract: The effects of Arbuscular mycorrhizal (AM) fungi on the characteristics of leaf development of Paeonia suffruticosa at different levels of salt stress (0, 8, 16 and 24%) were studied. Potted ‘Feng Dan’ seedlings were inoculated with Glomus mosseae, and the non-inoculated was used as the control. The results showed that under salt stress leaf relative water content, sclerophyllous index of leaves and leaf succulence level of P. suffruticosa seedlings inoculated with G. mosseae were significantly higher than those of non-inoculated seedling, and specific leaf area was significantly lower than that of the control. Leaf water loss rate of the non-inoculated peony was faster, the percentage of water loss in the total amount of water each time point is the highest. These results suggest that G. mosseae may play an important role in the leaf traits and enhanced salt tolerance of tree peony seedlings.[...] Read More.
Keywords: Arbuscular mycorrhizal fungi, characteristics of leaf development, Paeonia suffruticosa, salt stress.
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文章
Y. Erfani, A. Rasti*, A. Mirsalehian, S. M. Mirafshar, V. Ownegh
Abstract: Multidrug resistant strains of Escherichia coli are becoming a major challenge in treatment of patients with urinary tract infection. Developing effective screening methods for selection of antimicrobial resistant strains is necessary. In this study, we have compared descriptively results of E-test with Disk diffusion agar method in selection of multidrug resistant strains of E. coli among patients with urinary tract infection. In disk diffusion test, 19 of 256 urine collections were resistant to 5 antibiotics used in the study. Later E-test was performed on these 19 collections with the same 5 antibiotics. In E-test, 10.5% of the specimens were sensitive to Bacterim, 21.1% to gentamicin, 47.7% to nitrofurantoin, 10.5% to ciprofloxacin and 10.5% to Ceftazidime. Results indicate that performing E-test on strains that were resistant in disk diffusion test may increase specificity in determination of multidrug resistant strains of E. coli in patients with urinary tract infection. This antibiotic susceptibility study showed difference between E-test and disk diffusion agar in assessing the antibiotic susceptibility and found E-test accuracy and its superiority to disk diffusion in detecting multidrug resistance.[...] Read More.
Keywords: Escherichia coli, resistance, E-test, disk diffusion.
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文章
Hai-han Zhang, Ming Tang* and Yan Yang
Abstract: The growth models, diameter growth rates and biomass yield of three ectomycorrhizal (ECM) fungi, Suillus tomentosus (Kauff.) Sing. Snell and Dick, Suillus laricinus (Berk.in Hook.) O. Kuntze and Aminita vaginata (Bull.: Fr.) Vitt., were investigated under water stress induced by polyethylene glycol-6000 (PEG-6000) in pure culture. The results showed that the growth models of the three ectomycorrhizal fungi were not significantly affected by water stress, but the growth rates and biomass were changed. Lower water stress (-0.15 MPa) could stimulate the growth of three ectomycorrhizal fungi, but greater water stress restricted growth, and inhibitory effect became greater with the increasing water stress from -0.30 to -1.37 MPa. Their drought resistance was ordered by S. laricinus>S. tomentosus>A. vaginata. With the increasing water stress ( -0.02 ~ -0.73 MPa), the contents of gibberellin (GA) and auxin (IAA) in mycelium reduced from 26.53 to 0 g g -1 and 180.98 to 0 g g-1 respectively. S. laricinus accumulated the most (184.36 g g-1) abscisic acid (ABA) at -0.30 MPa; when water stress was beyond the tolerance of S. laricinus (-0.49 MPa); however, it inhibited the accumulation of abscisic acid (ABA).[...] Read More.
Keywords: Abscisic acid, ectomycorrhizal fungus, phytohormone, water stress.
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Bombiti Nzanza*, Diana Marais and Puffy Soundy
Abstract: Recent trends in soil microbiology suggest that certain soil microbes have a positive effect on seedling growth and development. A study was conducted to investigate the interactive effect of the plant-growth promoting fungi Trichoderma harzianum and the arbuscular mycorrhizal fungi (AMF) in growth and development of tomato (Solanun lycopersicum) seedlings grown under greenhouse conditions. A 3 x 3 factorial experiment was laid out in a completely randomised design with six replications. At harvest (42 DAP), when compared with the control, T. harzianum and/or AMF treated plants improved shoot length, root length, dry shoot mass and dry root mass. Pre-inoculation with AMF increased shoot N, P and S content of tomato seedlings, whereas pre-sowing with T. harzianum alone increased the shoot N. Generally, shoot Zn and Mn content were affected by both fungi, with the best result observed when AMF was applied 2 weeks after T. harzianum. The percentage of roots colonised by AMF was less than 15% regardless of the time when T. harzianum was applied. However, the percentage of roots colonised by T. harzianum was greater than 90% at all times. In conclusion, this study suggested that T. harzianum and AMF have the potential to improve tomato seedling growth and development.[...] Read More.
Keywords: Essential mineral nutrients, mycorrhiza, plant-growth promoting fungi, seedling quality, Solanum lycopersicum.
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Sun D. B., Wu R., Guo D. H.*, He X. J., Zheng J. S., Wang J. F., Lin Y. C., Han X., Wang Y. Q. and Guo T. T.
Abstract: To investigate the presence of Fusobacterium necrophorum (F. necrophorum) and Dichelobacter nodosus (D. nodosus) in dairy cattle footrot, a loop -mediated isothermal amplification method for detection of D. nodosus (Dn-LAMP) was developed and evaluated using species-specific16S rRNA gene as target gene. The Dn-LAMP showed no cross reaction with several common pathogens from cattle, and detection limit of the Dn-LAMP was 10 cfu/mL of D. nodosus. Amplicons of the Dn-LAMP could be detected by visual inspection. 189 hoof swabs from footrot-infected dairy cows in Heilongjiang province of China were detected using Dn -LAMP and Fn-LAMP for diagnosis of F. necrophorum, respectively. In 189 hoof swabs, 9 were positive for D. nodosus, and 95 were positive for F. necrophorum. These data suggested that combination of Dn -LAMP with Fn-LAMP will have a potential use for etiology investigation of footrot in dairy cattle.[...] Read More.
Keywords: Dichelobacter nodosus, Fusobacterium necrophorum, LAMP.
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