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1.
The aim of this research was to develop effective alternative therapies to reduce antibiotic use in animal agriculture. In this study, the efficacy of copper-modified palygorskite (CM-Pal) in preventing diarrhea caused by Salmonella was specifically examined both in vitro and in vivo. The CM-Pal was prepared with palygorskite (Pal) and copper nitrate. The antibacterial activity of the CM-Pal was detected by comparing the differences in cell numbers on plate count agar before and after adding the CM-Pal to Salmonella typhimurium cultures. Seventy ICR mice were then allocated into seven groups. Five groups (the treatment groups) were infected with S. typhimurium by intraperitoneal (i.p.) injection and were given Pal, CM-Pal, montmorillonite powder, gentamicin, and physiological saline, respectively. One group (the prevention group) was given CM-Pal before infection with S. typhimurium. Another group (the uninfected group) was not infected with S. typhimurium. The effects of Pal, CM-Pal, montmorillonite powder, and gentamicin on the treatment or prevention of diarrhea in the mice were examined by stool studies, fecal scoring, and assessment of growth performance and villus height. The CM-Pal had satisfactory anti-bacterial properties in vitro: the antibacterial rate was 100% after 2 h incubation with S. typhimurium NJS1 cultures (1×106 colony-forming units (CFU)/ml). In the in vivo experiment, the CM-Pal exerted superior effects in the treatment and prevention of diarrhea in mice compared with Pal, montmorillonite powder, and gentamicin. In the CM-Pal group, no mice showed signs of diarrhea at 24 h post infection (p.i.), and all mice fully recovered from infection. However, the Pal group, montmorillonite group, and gentamicin group only recovered after 48, 48, and 96 h, respectively. The villus height level in the CM-Pal treatment group recovered at 3 d p.i. However, the recovery time of the other groups was longer (at least 5 d). The CM-Pal prevention group had a better effect on weight gain than the other groups. This study suggested that CM-Pal may be an effective alternative to conventional antibiotics for the treatment and prevention of animal diarrhea caused by Salmonella.  相似文献   

2.
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3.
The production of elastase by Bacillus sp. EL31410 at various temperatures was investigated. In order to study the effect of temperature on elastase fermentation, different cultivation temperatures, ranging from 39 °C to 28 °C, were evaluated in shake flask. The result indicated that 37 °C was best for cell growth at earlier stage; while maximum elastase activity was obtained when the cells were cultivated at 30 °C. This result was verified by batch fermentation in 5-L bioreactor under 37 °C and 30 °C temperature, respectively. The specific cell growth rate at 37 °C was higher than that at 30 °C during earlier stage of cultivation. The maximum value [5.5 U/(h·g DCW)] of elastase formation rate occurred at 24 h at 30 °C compared to 4.6 U/(h·g DCW) at 30 h at 37 °C. Based on these results, two-stage temperature shift strategy and oscillatory temperature cultivation mode were evaluated in the next study. When compared to single temperature of 37 °C or 30 °C, both two-stage temperature shift strategy and oscillatory temperature strategy improved biomass but did not yield the same result as expected for elastase production. The maximum biomass (both 8.6 g/L) was achieved at 30 h at 37 °C, but at 42 h using two-stage temperature cultivation strategy. The highest elastase production (652 U/ml) was observed at 30 °C in batch process. It was concluded that cultivation at constant temperature of 30 °C was appropriate for elastase production by Bacillus sp. EL31410. Project (No. 20276064) supported by the National Natural Science Foundation of China  相似文献   

4.
The Bacillus strain BH072 isolated from a honey sample showed strong antifungal activity against phytopathogen. Gene cloning test demonstrated that the strain had a tasA gene encoding an antifungal TasA protein. Although the wild strain simultaneously produced various antifungal substances, only the physicochemical property and antifungal activity of TasA protein were unclear due to the difficulty in extraction. In this study, tasA gene encoding the protein from Bacillus sp. BH072 was amplified by using the polymerase chain reaction (PCR) method and cloned into pET 28a (+) vector, and then expressed in host cells Escherichia coli BL21 (DE3). The expressed proteins were collected by centrifugation and ultrasonic treatment, and then purified by using nickel-nitrilotriacetic acid (Ni-NTA) metal affinity column and dialysis methods. The result of sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) test showed that an expected protein band appeared with a size of 31 kDa. The expressed products possessed antifungal activity against the phytopathogenic indicator strain Botrytis cinerea. A genetically engineered strain tasA of E. coli was established in this study which can efficiently express Tas A protein.  相似文献   

5.
Chemical composition of Gongronema latifolium leaves was determined using standard methods. Aqueous and methanol G. latifolium extracts were tested against thirteen pathogenic bacterial isolates. Crude protein, lipid extract, ash, crude fibre and nitrogen flee extractives obtained are： 27.2%, 6.07%, 11.6%, 10.8% and 44.3% dry matter respectively. Potassium, sodium, calcium, phosphorus and cobalt contents are 332, 110, 115, 125 and 116 mg/kg respectively. Dominant essential amino acids are leucine, valine and phenylalanine. Aspartic acid, glutamic acid and glycine are 13.8%, 11,9% and 10.3% respectively of total amino acid. Saturated and unsaturated fatty acids are 50.2% and 39.4% of the oil respectively. Palmitic acid makes up 36% of the total fatty acid. Extracts show no activity against E. faecalis, Y. enterolytica, E. aerogenes, B. cereus and E. agglomerans. Methanol extracts were active against S, enteritidis, S. cholerasius ser typhimurium and P. aeruginosa （minimum inhibitory concentration （MIC） 1 mg; zone of growth inhibition 7, 6.5 and 7 mm respectively）. Aqueous extracts show activity against E. coli （MIC 5 mg） and P. aeruginosa （MIC 1 mg） while methanol extracts are active against P. aeruginosa and L. monocytogenes. G. lafifolium has potential food and antibacterial uses.  相似文献   

6.
Technological advances in the form of ubiquitous computing has altered the learning landscape today. Contemporary modes of learning afford curricular innovations in schools. While learning journeys of decades ago entailed field trips to places of interest such as museums and zoos where students completed tasks or worksheets after each trip, the learning journeys of today are facilitated by technological tools such as smart devices and global positioning systems. Learners are moving away from being mere content consumers through technology-facilitated dialoguing and content creation (Tay and Lee 2014; Tan et al. 2011). In this paper we unpack tenets of a technology-facilitated curricular innovation (CI) through a case study analysis of the development and implementation of a Digital Learning Trails (DLT) project. Through tracing the trajectory of the DLT project, we identify factors related to the scalability and sustainability of this CI that was developed in one school and subsequently used by more than 200 schools in Singapore. We posit that scaling curricular innovations in schools can be conceptually provisioned through a rhizomatic lens where innovation is characterized by multiple trajectories, allowing for recontextualizations of CIs. We argue that, (1) the pedagogic process in the context of education and scaling is based on supporting apprentice-schools to make multiple recontextualizations; (2) the enculturation process of a school adopting and implementing a particular innovation is based on a rhizomatic rather than linear, conception of the development of expertise; and (3) the process of CI implementation is based on developing the capability to not only make multiple recontextualizations but also to accumulate enough capital to send out new ‘roots and shoots’ as it spreads.  相似文献   

7.
INTRODUCTION Left ventricular hypertrophy has been thought to be the principal predicators of predisposing risk factor of cardiac morbidity and mortality (Devereux, 1995; Levy et al., 1990). The pathogenesis that mediates cardiac hypertrophy is poorly understood. Cardiachypertrophy can be induced by hemodynamic over-load, ischemic disease, neurohumoral factors and intrinsic defects in cardiac structural protein genes (Sadoshima and Izumo, 1997; Vikstrom and Lein-wand, 1996). Another in…  相似文献   

8.
Non-dispersive solvent extraction (NDSE) with p-xylene as extractant was employed as a novel separation method to recover both p-toluic (PT) acid and water from purified terephthalic acid (PTA) wastewater. The mass transport behavior of PT acid from aqueous solution to p-xylene was investigated by experiments and numerical simulation. Experiments showed that NDSE is feasible and effective. Residual PT acid in the raffinate can be reduced to lower than the permitted limit of wastewater re-use (100 g/m3) with extraction time longer than 60 s in industrial conditions. A mathematical model of PT acid mass transport was developed to optimize the membrane module performance. The model was validated with the experimental results with relative errors of less than 6%. Numerical analysis for mass transfer through the lumen side, the porous membrane layer, and the shell side showed that PT acid transport in the aqueous solution is the rate determining step. The effects of the membrane and operating parameters on membrane module performance were investigated by means of computational simulations. The key parameters suggested for industrial NDSE design are: fiber inner radius r1=200–250 µm, extraction time te=50–60 s, aqueous/organic volumetric ratio a/o=9.0, and temperature T=318 K.  相似文献   

9.
The aim of this study is to assess the antibacterial and anti-biofilm properties of the lipid extract from Mantidis ootheca against the gentamycin resistant Pseudomonas aeruginosa. The chemical composition of the lipid extract and its relative proportion were determined using the technique of gas chromatography coupled with mass spectrometry (GC-MS). Antibacterial susceptibility tests were performed using a disc diffusion assay and the minimum inhibition concentration (MIC) was determined by way of the agar dilution method. The anti-biofilm test was carried out with crystal violet staining and scanning electron microscopy (SEM). There were 16 compounds detected, and the most abundant components were sesquiterpenoids, monoterpenes, and trace aromatic compounds. The MIC for P. aeruginosa was 4 mg/ml and the eradication effect on preformed biofilms was established and compared with a ciprofloxacin control. The results of our study indicated that a lipid extract from M. ootheca could be used as a topical and antibacterial agent with anti-biofilm activity in the future.  相似文献   

10.
Phytophthora capsici is a phytopathogen that causes a destructive pepper blight that is extremely difficult to control. Using a fungicide application against the disease is costly and relatively ineffective and there is also a huge environmental concern about the use of such chemicals. The genus Trichoderma has been known to have a potential biocontrol issue. In this paper we investigate the mechanism for causing the infection of T. asperellum against P. capsici. Trichoderma sp. (isolate CGMCC 6422) was developed to have a strong antagonistic action against hyphae of P. capsici through screening tests. The strain was identified as T. asperellum through using a combination of morphological characteristics and molecular data. T. asperellum was able to collapse the mycelium of the colonies of the pathogen through dual culture tests by breaking down the pathogenic hyphae into fragments. The scanning electron microscope showed that the hyphae of T. asperellum surrounded and penetrated the pathogens hyphae, resulting in hyphal collapse. The results show that seven days after inoculation, the hyphae of the pathogen were completely degraded in a dual culture. T. asperellum was also able to enter the P. capsici oospores through using oogonia and then developed hyphae and produced conidia, leading to the disintegration of the oogonia and oospores. Seven days after inoculation, an average 10.8% of the oospores were infected, but at this stage, the structures of oospores were still intact. Subsequently, the number of infected oospores increased and the oospores started to collapse. Forty-two days after inoculation, almost all the oospores were infected, with 9.3% of the structures of the oospores being intact and 90.7% of the oospores having collapsed.  相似文献   

11.
Crypthecodinium cohnii (dinoflagellate) and Schizochytrium sp. (thraustochytrid) are the main sources for docosahexaenoic acid (DHA). The present study aimed to evaluate the antioxidant activity of petroleum ether, ethyl acetate, n-butanol, and water fractions of alcohol aqueous extracts of these two microalgae and to provide a theoretical basis for comprehensive utilization. The antioxidant activity was determined by total antioxidant capacity (TAC) determination, 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay, ferrous ion-chelating ability (FICA) assay, and reducing power (RP) assay. The total phenolic content (TPC) and total flavonoid content (TFC) were also measured by the Folin-Ciocalteu and spectrophotometry methods, respectively. The results indicated that the extracts from these two microalgae possessed good antioxidant capacity. Analysis showed that most antioxidant performance indicators (TAC, DPPH, and RP) were positively correlated with the TPC of the extracts, suggesting that the phenolics might be the major components in C. cohnii and Schizochytrium sp., contributing to their antioxidative function. Therefore, the polar fractions of C. cohnii and Schizochytrium sp. could be further examined and considered for application in health products or cosmetics.  相似文献   

12.
Stress affects the male reproductive system and can cause sub-fertility or infertility. Although Phyllanthus emblica L. (PE) extract has been shown to have high antioxidant capacity and protective properties in damaged tissue, the preventive effects of PE extract on testicular function from stress-related impairment have never been demonstrated. This study aimed to investigate the effects of PE aqueous leaf extract on testicular impairment and protein marker changes in rats suffering from chronic stress. Adult male rats were divided into four groups: a control group, a chronic stress (CS) group, and two groups with CS that received different doses of PE extract (50 or 100 mg/kg body weight (BW)). In the treatment groups, the animals were given PE extract daily before stress induction for 42 consecutive days. Stress was induced through immobilization (4 h/d) followed by forced cold swimming (15 min/d). Sperm quality and the histology of the testes and caudal epididymis were examined, as were levels of serum corticosterone, testosterone, and malondialdehyde (MDA). The expressions of testicular steroidogenic acute regulatory (StAR) and tyrosine-phosphorylated proteins were investigated using immuno-Western blot analysis, as these proteins are assumed to play important roles in spermatogenesis and androgen synthesis. The results showed that PE (50 mg/kg BW) significantly increased sperm concentration and testosterone levels, while decreasing corticosterone levels, MDA levels, sperm head abnormalities, and acrosome-reacted sperm in CS rats. In addition, PE at both doses was found to diminish testicular histopathology in the CS rats. We also found that 50 mg/kg BW of PE significantly improved StAR protein expression and altered the intensities of some tyrosine-phosphorylated proteins in testis. We conclude that PE leaf extract at 50 mg/kg BW can prevent testicular damage in rats with CS.  相似文献   

13.
Functional studies have suggested the important role of early growth response 1 (EGR1) and Laminin α2-chain (LAMA2) in human eye development. Genetic studies have reported a significant association of the single nucleotide polymorphism (SNP) in the LAMA2 gene with myopia. This study aimed to evaluate the association of the tagging SNPs (tSNPs) in the EGR1 and LAMA2 genes with high myopia in two independent Han Chinese populations. Four tSNPs (rs11743810 in the EGR1 gene; rs2571575, rs9321170, and rs1889891 in the LAMA2 gene) were selected, according to the HapMap database (http://hapmap.ncbi.nlm.nih.gov), and were genotyped using the ligase detection reaction (LDR) approach for 167 Han Chinese nuclear families with extremely highly myopic offspring (<?10.0 diopters) and an independent group with 485 extremely highly myopic cases (<?10.0 diopters) and 499 controls. Direct sequencing was used to confirm the LDR results in twenty randomly selected subjects. Family-based association analysis was performed using the family-based association test (FBAT) software package (Version 1.5.5). Population-based association analysis was performed using the Chi-square test. The association analysis power was estimated using online software (http://design.cs.ucla.edu). The FBAT demonstrated that all four tSNPs tested did not show association with high myopia (P>0.05). Haplotype analysis of tSNPs in the LAMA2 genes also did not show a significant association (P>0.05). Meanwhile, population-based association analysis also showed no significant association results with high myopia (P>0.05). On the basis of our family- and population-based analyses for the Han Chinese population, we did not find positive association signals of the four SNPs in the LAMA2 and EGR1 genes with high myopia.  相似文献   

14.
Antioxidative and cytotoxic effects of chamomile (Matricaria chamomilla) fermented by Lactobacillus plantarum were investigated to improve their biofunctional activities. Total polyphenol (TP) content was measured by the Folin-Denis method, and the antioxidant activities were assessed by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) method and β-carotene bleaching method. AGS, HeLa, LoVo, MCF-7, and MRC-5 (normal) cells were used to examine the cytotoxic effects by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium (MTT) assay. The TP content of fermented chamomile reduced from 21.75 to 18.76 mg gallic acid equivalent (mg GAE)/g, but the DPPH radical capturing activity of fermented chamomile was found to be 11.1% higher than that of nonfermented chamomile after 72 h of fermentation. Following the β-carotene bleaching, the antioxidative effect decreased because of a reduction in pH during fermentation. Additionally, chamomile fermented for 72 h showed a cytotoxic effect of about 95% against cancer cells at 12.7 mg solid/ml of broth, but MRC-5 cells were significantly less sensitive against fermented chamomile samples. These results suggest that the fermentation of chamomile could be applied to develop natural antioxidative and anticancer products.  相似文献   

15.
This key paper is intended to produce a comparison of Bildung and globalization, acknowledging that Bildung and globalization are both fuzzy concepts. Our comparison of globalization and Bildung therefore is to be seen as a construction. To reach this objective, we start with the identification of dimensions of the concept of globalization based predominantly on sociological research. This analysis is followed by explication of dimensions of the concept of Bildung as they can be identified before a frame of globalization. We want to find out whether it makes sense to see globalization as one part of a new model of Bildung. In the conclusion, we demonstrate the normativity of each and any theory of Bildung in globalizing times, and we explain why it is necessary to reflect on the normativity of the different concepts. We indicate where we see connections with the other papers of this special issue of “Zeitschrift für Erziehungswissenschaft”.  相似文献   

16.
This retrospective chart review study examined the factor structure of the Career Futures Inventory-Revised (CFI-R; Rottinghaus et al. in J Career Assess 20:123–139, 2012) and its utility as a career counseling outcome measure using a sample of 332 clients from a university career center. The CFI-R examines career agency and other career adaptability dimensions germane to clients’ career concerns. Confirmatory factor analysis results supported the proposed factor structure. Changes in CFI-R scale scores are reported for 116 clients who received counseling. The use of the CFI-R as an effectiveness outcome measure for individual, group, and classroom career interventions is addressed.  相似文献   

17.
V. V. Raman 《Resonance》2011,16(7):670-681
The nature of matter, or body considered in general, consists not in its being something which is hard or heavy or coloured, or which affects the senses in any way, but simply in its being something which is extended in length, breadth and depth.  相似文献   

18.
Mathematical understanding continues to be one of the major goals of mathematics education. However, what is meant by “mathematical understanding” is underspecified. How can we operationalize the idea of mathematical understanding in research? In this article, I propose particular specifications of the terms mathematical concept and mathematical conception so that they may serve as useful constructs for mathematics education research. I discuss the theoretical basis of the constructs, and I examine the usefulness of these constructs in research and instruction, challenges involved in their use, and ideas derived from our experience using them in research projects. Finally, I provide several examples of articulated mathematical concepts.  相似文献   

19.
V. V. Raman 《Resonance》2012,17(4):393-405
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20.
V. V. Raman 《Resonance》2011,16(2):190-199
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