JOURNAL OF TEXTURE STUDIES, Issue 2 2010
HATSUE MORITAKA
ABSTRACT The flow velocity through the human throat and rheological properties of 0.2,0.8% agar and 0.8,2.4% gelatin were investigated. The maximum flow velocity decreased with increasing concentrations of agar and gelatin, with marked changes from 0 to 0.4% in agar, and from 0 to 1.4% in gelatin, with no further changes at concentration higher than 0.4% in agar but changes at concentration up to 2.4% in gelatin. Although the hardness and adhesiveness increased with increasing concentrations of agar and gelatin, the cohesiveness decreased. In the sensory evaluation, agar and gelatin became difficult to swallow with increasing agar and gelatin concentration. PRACTICAL APPLICATIONS This research contributes to enhance the knowledge of the investigation area of the flow velocity of bolus in a pharynx. Moreover, this research is useful in order to make the foods for person with difficulties in chewing and swallowing. In fact, the results demonstrate the importance of measuring the flow velocity of bolus in the pharynx part not only the rheological properties of food. [source]

COMPARISON OF PHYSICAL PROPERTIES OF AGAR, LOW GEL STRENGTH AGAR AND GELATIN, AS SUPPLEMENTARY FOOD FOR PEOPLE WITH SWALLOWING DIFFICULTY

JOURNAL OF TEXTURE STUDIES, Issue 4 2002
ATSUKO IGARASHI
ABSTRACT Low gel strength agar (LGSA), recently developed as a supplementary food for swallowing was compared with ordinary agar and gelatin. LGSA was developed to have physical properties close to that of gelatin, while keeping one property of agar, i. e. its setting temperature which can be controlled comparatively easier than gelatin. Each specimen was prepared with and without orange flavor. After determination of their basic properties, i. e. hardness, adhesiveness, cohesiveness and gumminess, three samples of two flavors, six in all, were studied for ease of swallowing using electromyography and sensory evaluation, on middle age (40 to 60 years old) and senior age (60 to 70 years old) subjects. Those experiments revealed nearly the same results with all samples, except for a slight difference in gumminess in LGSA and gelatin. No significant difference in electromyograms were noted in six samples or with age of subjects. It is feasible to employ agar materials together with gelatin in institutions whose members have swallowing disorders. [source]

EFFECTS OF AGAR AND PECTIN ON GASTRIC EMPTYING AND POST-PRANDIAL GLYCAEMIC PROFILES IN HEALTHY HUMAN VOLUNTEERS

CLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 11 2007
Masaki Sanaka
SUMMARY 1Dietary fibre, such as pectin, delays gastric emptying and may enhance post-prandial glucose tolerance. Agar, which is high in fibre content, is widely used in the traditional Japanese diet. Although long-term diet therapy with agar decreases fasting plasma glucose levels in diabetes, knowledge is lacking about the acute effects of agar on gastric emptying and the post-prandial glycaemic profiles. The present study was designed to investigate the acute effects of agar. 2Ten healthy male volunteers were studied on three occasions with three different test meals (450 kcal/500 mL): (i) a fibre-free meal; (ii) a meal with 2.0 g agar; or (iii) a meal with 5.2 g pectin. On each occasion, participants underwent a [13C]-acetate breath test along with serial blood sampling. To quantify gastric emptying, the half [13CO2] excretion time () and the time for maximal [13CO2] excretion rate (tlag) were determined. The post-prandial glycaemic response was expressed as an incremental change from the fasting value at each sampling time. Data were analysed using repeated-measures analysis of variance (anova), followed by a post hoc paired Student's t -test with Bonferroni adjustment. 3The time-course for respiratory [13CO2] excretion differed significantly among the three test meals (P = 0.0004, anova). Compared with the control meal, [13CO2] excretion was significantly lower following consumption of the agar meal (between 40 and 105 min post-prandially; P < 0.025, Student's t -test) and the pectin meal (between 40 and 180 min post-prandially; P < 0.025, Student's t -test). Among the three meals, significant differences were found in (P = 0.002, anova) and tlag (P = 0.011, anova). Compared with the control meal, the agar and pectin meals exhibited a significantly prolonged (P = 0.007 and P < 0.0001, respectively, Student's t -test) and tlag (P = 0.006 and P = 0.002, respectively, Student's t -test). Neither the agar nor pectin meal affected the post-prandial glucose profile. 4In healthy adults, agar and pectin delay gastric emptying but have no impact on the post-prandial glucose response. [source]

Heterologous complementation of the exopolysaccharide synthesis and carbon utilization phenotypes of Sinorhizobium meliloti Rm1021 polyhydroxyalkanoate synthesis mutants

FEMS MICROBIOLOGY LETTERS, Issue 2 2004
Punita Aneja
Abstract A reduced exopolysaccharide phenotype is associated with inability to synthesize polyhydroxyalkanaote (PHA) stores in Sinorhizobium meliloti strain Rm1021. Loss of function mutations in phbB and phbC result in non-mucoid colony morphology on Yeast Mannitol Agar, compared to the mucoid phenotype exhibited by the parental strain. This phenotype is attributed to reduction in succinoglycan synthesis. We have used complementation of this phenotype and the previously described d -3-hydroxybutyrate/acetoacetate utilization phenotype to isolate a heterologous clone containing a Bradyrhizobium japonicum phbC gene. Sequence analysis confirmed that this clone contains one of the five predicted phbC genes in the B. japonicum genome. The described phenotypic complementation strategy should be useful for isolation of novel PHA synthesis genes of diverse origin. [source]

Cutaneous cryptococcosis associated with lepromatous leprosy

INTERNATIONAL JOURNAL OF DERMATOLOGY, Issue 6 2001
Rubem David Azulay MD
A 65-year-old Brazilian man presented with an erythematous nodular lesion on the left forearm (Fig. 1). The patient had been treated with multidrug therapy for 8 months for lepromatous leprosy. During therapy, he developed recurrent episodes of reactions which were treated with high doses of prednisone and thalidomide. The histopathology of the cutaneous nodular lesion showed a granulomatous inflammatory infiltrate; some histiocytes contained vacuolations and others demonstrated oval-like or coma-like structures (Fig. 2). The specimen was cultivated in Sabouraud agar at room temperature. The colonies were transferred to Petri dishes containing Niger Seed Agar (NSA) (Fig. 3). The confirmed diagnosis was Cryptococcus neoformans var. neoformans based on microscopy and physiology, including the canavanine,glycine,bromothymol blue (CGB) medium (Lazéra MS, Pires FDA, Camillo-Coura L et al. Natural habitat of Cryptococcus neoformans var. neoformans in decaying wood forming hollows in living trees. J Med Vet Mycol 1996; 34: 127,131). The liquor culture was negative. Hemoculture and urine culture were also negative. Latex agglutination test was blood positive and liquor negative. Figure 1. Erythematous nodular lesion on the left forearm measuring 9 cm in diameter Figure 2. Granulomatous infiltrate presenting oval-like or coma-like structures inside the histiocytes (mucicarmine stain, ×,100) Figure 3. Petri dishes with Niger Seed Agar containing numerous colonies of Cryptococcus neoformans var. neoformans The patient's hemogram revealed normocytic anemia and normal total and differential white blood count. The CD4 count was 189/m3 and the CD8 count was 141/m3. Serology for anti-human immunodeficiency virus-I (anti-HIV-I) antibodies was negative. The X-ray of the lungs showed an areolar image in the superior lobe of the right lung. Therapy with prednisone was suspended and fluconazole (300 mg/day) was prescribed. The nodular cutaneous lesion regressed completely after 90 days. The patient was submitted to a second skin biopsy for treatment control. The culture of the specimen taken was still positive and the histopathology showed the same picture as before treatment. After 5 months of continued therapy with fluconazole, another biopsy was performed but no fungus was recovered from the specimen. [source]

Comparison of three plating media for the isolation of Salmonella from poultry environmental samples in Great Britain using ISO 6579:2002 (Annex D)

JOURNAL OF APPLIED MICROBIOLOGY, Issue 6 2009
J.J. Carrique-Mas
Abstract Aims:, To evaluate the performance of three Salmonella plating media (Rambach, Xylose Lysine Deoxycholate agar and modified Brilliant Green Agar plus Novobiocin) as part of the ISO 6579: 2002 (Annex D) on poultry environmental samples. Methods and Results:, The samples analysed were those for the European Union Salmonella baseline surveys of laying (N = 3087), broiler (N = 1550), turkey fattening (N = 1540) and turkey breeding (N = 580) flocks for Great Britain. Results were considered separately for Rambach (including and excluding pale orange colonies) and for growth on selective media [Modified semi-solid Rappaport Vassiliadis (MSRV)] after 24 and 48 h of incubation. Overall, Rambach was the most sensitive medium, provided that pale orange colonies were checked. In all cases, an increase in the sensitivity of detection was obtained by plating growth on MSRV after 48 h of incubation. In broilers and laying flocks, the specificity significantly improved when Rambach only was used. Conclusion:, The use of Rambach results in considerable savings compared with the two-plate method prescribed by ISO 6579:2002 (Annex D) without compromising sensitivity. Significance and Impact of the Study:,Salmonella isolation protocols should be reviewed in terms of their efficiency and cost. [source]

Modelling the photosensitization-based inactivation of Bacillus cereus

JOURNAL OF APPLIED MICROBIOLOGY, Issue 3 2009
Y. Le Marc
Abstract Aims:, To study and to develop a model for the photo-destruction of the foodborne pathogen Bacillus cereus, initially treated with a precursor of endogenous photosensitizers (5-aminolevulinic acid, ALA). Materials and methods:, The cells were incubated in the presence of ALA (3 or 7·5 mmol l,1) for incubation times ranging from 2 to 60 min, inoculated onto the surface of LB Agar plates and submitted to light irradiation. The Weibull model was used to describe the survival curves of B. cereus. Quadratic equations were used to describe the effects of ALA concentration and incubation time on the Weibull model parameters. Results:, ALA-based photosensitization proved to be an effective tool for inactivation of B. cereus. The decrease in viable counts observed after 20 min of irradiation, ranged from 4 to 6 log CFU g,1. Conclusions:, The developed model proved to be a parsimonious and robust solution to describe the observed data. Significance and Impact of the Study:, The study demonstrates the effectiveness of photosensitization on B. cereus on agar plates. The model developed may be useful to optimize inactivation treatments by photosensitization. [source]

Antibiotic resistance profile of the subgingival microbiota following systemic or local tetracycline therapy

JOURNAL OF CLINICAL PERIODONTOLOGY, Issue 6 2004
Rosa Maria J. Rodrigues
Abstract Background: Tetracyclines have been extensively used as adjunctives to conventional periodontal therapy. Emergence of resistant strains, however, has been reported. This study evaluated longitudinally the tetracycline resistance patterns of the subgingival microbiota of periodontitis subjects treated with systemic or local tetracycline therapy+scaling and root planing (SRP). Methods: Thirty chronic periodontitis patients were randomly assigned to three groups: SRP+500 mg of systemic tetracycline twice/day for 14 days; SRP alone and SRP+tetracycline fibers (Actsite®) at four selected sites for 10 days. Subgingival plaque samples were obtained from four sites with probing pocket depths (PPD)6 mm in each patient at baseline, 1 week, 3, 6 and 12 months post-therapy. Samples were dispersed and diluted in pre-reduced anaerobically sterilized Ringer's solution, plated on Trypticase Soy Agar (TSA)+5% blood with or without 4 ,g/ml of tetracycline and incubated anaerobically for 10 days. The percentage of resistant microorganisms were determined and the isolates identified by DNA probes and the checkerboard method. Significance of differences among and within groups over time was sought using the Kruskal,Wallis and Friedman tests, respectively. Results: The percentage of resistant microorganisms increased significantly at 1 week in the tetracycline groups, but dropped to baseline levels over time. The SRP+Actsite® group presented the lowest proportions of resistant species at 6 and 12 months. No significant changes were observed in the SRP group. The predominant tetracycline-resistant species included Streptococcus spp., Veillonela parvula, Peptostreptococcus micros, Prevotella intermedia, Gemella morbillorum and Actinobacillus actinomycetemcomitans (Aa). A high percentage of sites with resistant Aa, Porphyromonas gingivalis and Tanerella forsythensis was observed in all groups at baseline. However, T. forsythensis was not detected in any group and P. gingivalis was not present in the SRP+Actsite® group at 1 year post-therapy. Aa was still frequently detected in all groups after therapy. However, the greatest reduction was observed in the SRP+Actsite® group. Conclusion: Local or systemically administered tetracycline results in transitory selection of subgingival species intrinsically resistant to this drug. Although the percentage of sites harboring periodontal pathogens resistant to tetracycline were quite elevated in this population, both therapies were effective in reducing their prevalence over time. [source]

THERMAL DEATH TIMES OF ESCHERICHIA COLI IN YOUNG COCONUT ENDOSPERM BEVERAGE

JOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 2009
ALONZO A. GABRIEL
ABSTRACT The decimal reduction times (D values) of Escherichia coli (American Type Culture Collection 25922) were established in a young coconut endosperm beverage, a famous local drink in the Philippines and in many tropical countries. Artificially inoculated cells were heated to 60, 70 and 80C at various heating times prior to survivor enumeration by surface plating onto pre-solidified Eosine Methylene Blue Agar. Results showed that the surviving populations significantly (P < 0.05) decreased with increasing exposure time and temperature. The calculated D values ranged from 0.26 ± 0.01 to 0.56 ± 0.08 min. Validation of the results by establishing the thermal resistance of other E. coli isolates in the coconut beverage medium was recommended. PRACTICAL APPLICATION The study established the thermal inactivation rates of Escherichia coli (American Type Culture Collection 25922) in a young coconut endosperm beverage medium in various heating temperatures. The results obtained from this study may be used in the calculations of appropriate thermal process schedules for the test beverage against the test organism. [source]

SURVIVAL OF THREE SALMONELLA SEROTYPES ON BEEF TRIMMINGS DURING SIMULATED COMMERCIAL FREEZING AND FROZEN STORAGE

JOURNAL OF FOOD SAFETY, Issue 2 2001
G.A DYKES
ABSTRACT This study investigated the survival of three Salmonella serotypes (S. Brandenberg, S. Dublin and S. Typhimurium) on beef trimmings during simulated commercial freezing, frozen storage for 9 months and subsequent abusive slow thawing and refreezing conditions. This was achieved by plating samples monthly and after thawing and refreezing on nonselective Tryptic Soy Agar (TSA) and selective Xylose Lysine Desoxycholate Agar (XLD) and incubating both at 37C for 24 h to determine Salmonella counts, aerobic counts and the presence, if any, of sublethal injury of this pathogen. Two freezing temperatures (,18C or ,35C) to simulate slow or rapid freezing respectively, and two inoculation levels (103 cfu g,1 or 105 cfu g,1) were used. Aerobic counts and counts of all the Salmonella serotypes did not change significantly (p > 0.05) during frozen storage or for any of the other treatments applied in this study. This finding was attributed to the insulating nature of the subcutaneous fat layer in this manufacturing cut. These results are important with respect to food safety associated with ground beef processing. [source]

The use of simple dynamic mucosal models and confocal microscopy for the evaluation of lyophilised nasal formulations

JOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 6 2007
Fiona McInnes
A range of methods is reported in the literature for assessing hydration and adhesion parameters in the performance of nasal bioadhesive formulations; however, these tests do not always represent the dynamic conditions in the nasal cavity. Lyophilised formulations intended for nasal administration were evaluated using in-vitro tests designed in an attempt to mimic relevant processes in the nasal cavity, and intended to discriminate between different formulations. Initial investigative studies using scanning electron microscopy revealed that the lyophilisate had a highly porous internal structure, expected to provide an ideal porous pathway for re-hydration. Vapour sorption analysis demonstrated substantial weight gain of the lyophilisates on exposure to 95% relative humidity, ranging from 38% to 66%. Agar was used as a synthetic mucosal model designed to provide a standardised quantity of water available for rehydration of the formulations in in-vitro tests. A dynamic adhesion test and a texture analyser sliding test were designed to quantify different aspects of the spreading and adhesion of the hydrating formulations on the synthetic mucosal surface. Examination of the lyophilised formulations using confocal microscopy allowed visualisation and quantification of the initial rate of water ingress into the lyophilisates, which was found to consist of an initial rapid phase, followed by a slower steady-state phase. The results demonstrated that the use of a combination of methods representing the dynamic conditions of the nasal cavity is advisable in order to evaluate a formulation fully and to avoid misleading conclusions. [source]

Factors affecting adventitious regeneration from in vitro leaf explants of ,Improved French' plum, the most important dried plum cultivar in the USA

ANNALS OF APPLIED BIOLOGY, Issue 1 2010
C. Petri
An adventitious shoot regeneration protocol from in vitro leaves of the most important dried plum cultivar in the USA, ,Improved French', has been established. Factors affecting regeneration were studied in order to optimise regeneration. The proliferation medium in which the shoots, used as the source of leaf explants, were cultured had a strong influence on subsequent regeneration. Shoot regeneration was observed at a mean frequency of 52% when a Murashige-based and Skoog-based shoot culture medium with 3 ,M N6 -benzylaminopurine and 0.25 ,M indole-3-butyric acid (IBA) was employed compared with shoot regeneration frequencies of less than 5% for a Quoirin-based and Lepoivre-based shoot culture medium, with 8.9 ,M N6 -benzylaminopurine and 0.49 ,M IBA. The shoot regeneration medium contained ,-naphthaleneacetic acid at 2.0,6.0 ,M and thidiazuron at 4.5,15.0 ,M. 2,4 Dichlorophenoxy-acetic acid at 9.0 ,M was included in the medium but only for the first 4 days of culture. Shoot regeneration frequencies were positively related to thidiazuron concentration and significantly greater (P < 0.05) for 9,15 ,M thidiazuron than for the media with 4.5 ,M thidiazuron. Leaf explants, incubated in a 16-h-light/8-h-dark photoperiod or in the dark for 1 week followed by exposure to light, showed significantly more organogenic activity (P < 0.01) than was observed for leaves cultured in the dark for 2 or 3 weeks before they were transferred to the light. The utilisation of Bacto agar (0.7%) as the gelling agent increased organogenesis compared with media gelled with TC Agar (0.7%), or an agar,gellan gum blend (AgargelÔ) (0.45%). The addition of the ethylene inhibitor silver thiosulphate at 60,120 ,M also improved organogenesis. When all the studied factors were optimised, a regeneration rate of 65% was achieved. Rooting frequency of regenerated shoots was significantly increased (P < 0.05) by the use of full-strength Murashige and Skoog salts (40%) or 100 mg L,1 phloroglucinol (53%) to the rooting medium. [source]

EFFECTS OF AGAR AND PECTIN ON GASTRIC EMPTYING AND POST-PRANDIAL GLYCAEMIC PROFILES IN HEALTHY HUMAN VOLUNTEERS

Development of a robust hydrogel system based on agar and sodium alginate blend

POLYMER INTERNATIONAL, Issue 2 2008
Ramavatar Meena
Abstract BACKGROUND: As part of an ongoing research and development programme of our laboratory on functional modification of seaweed polysaccharides for preparing hydrogels with improved properties, we report herein the preparation of a robust hydrogel system based on grafting of agar and sodium alginate blend (Agar/Na-Alg) with acrylamide (AAm) to obtain the copolymer Agar/Na-Alg- graft -PAAm. RESULTS: A robust hydrogel system with superior absorbency and pH resistance has been developed based on a PAAm-grafted seaweed polysaccharide blend of Agar/Na-Alg. The blend (Agar/Na-Alg) and grafted product (Agar/Na-Alg- graft -PAAm) were evaluated using Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, swelling capacity, rheology and scanning electron microscopy. The swelling capacity of the grafted copolymer exhibited an enhancement over that of the blend from 14 to 24 g g,1 in acidic medium. The blend and grafted copolymer produced hydrogels with lower gelling points of 31 and 29 °C and gel strengths were 170 and 120 g cm,2, respectively. CONCLUSION: This study constitutes an example of value addition of seaweed polysaccharides targeting new applications. The copolymer hydrogel may be useful in health, personal care and agricultural applications. Copyright © 2007 Society of Chemical Industry [source]

Growth-induced changes in the proteome of Helicobacter pylori

ELECTROPHORESIS, Issue 5-6 2006
Christina Uwins
Abstract Helicobacter pylori is a major human pathogen that is responsible for a number of gastrointestinal infections. We have used 2-DE to characterise protein synthesis in bacteria grown either on solid agar-based media or in each of two broth culture media (Brucella and brain heart infusion (BHI) broth). Significant differences were observed in the proteomes of bacteria grown either on agar-based or in broth media. Major changes in protein abundance were identified using principal component analysis (PCA), which delineated the profiles derived for the three key growth conditions (i.e. agar plates, Brucella and BHI broth). Proteins detected across the gel series were identified by peptide mass mapping and Edman sequencing. A number of proteins associated with protein synthesis in general as well as specific amino acid synthesis were depressed in broth-grown bacteria compared to plate-grown bacteria. A similar reduction was also observed in the abundance of proteins involved in detoxification. Two of the most abundant spots, identified as UreB and GroEL, in plate-grown bacteria showed a >140-fold drop in abundance in bacteria grown in Brucella broth compared to bacteria grown on agar plates. Two protein spots induced in bacteria grown in broth culture were both identified as glyceraldehyde 3-phosphate dehydrogenase based on their N -terminal amino acid sequences derived by Edman degradation. The underlying causes of the changes in the proteins abundance were not clear, but it was likely that a significant proportion of the changes were due to the alkaline pH of the broth culture media. [source]

Mouse lymphoma thymidine kinase gene mutation assay: Follow-up meeting of the international workshop on Genotoxicity testing,Aberdeen, Scotland, 2003,Assay acceptance criteria, positive controls, and data evaluation,

ENVIRONMENTAL AND MOLECULAR MUTAGENESIS, Issue 1 2006
Martha M. Moore
Abstract The Mouse Lymphoma Assay (MLA) Workgroup of the International Workshop on Genotoxicity Testing (IWGT), comprised of experts from Japan, Europe, and the United States, met on August 29, 2003, in Aberdeen, Scotland, United Kingdom. This meeting of the MLA Workgroup was devoted to reaching a consensus on the appropriate approach to data evaluation and on acceptance criteria for both the positive and negative/vehicle controls. The Workgroup reached consensus on the acceptance criteria for both the agar and microwell versions of the MLA. Recommendations include acceptable ranges for mutant frequency, cloning efficiency, and suspension growth of the negative/vehicle controls and on criteria to define an acceptable positive control response. The recommendation for the determination of a positive/negative test chemical response includes both the requirement that the response exceeds a defined value [the global evaluation factor (GEF)] and that there also be a positive dose,response (evaluated by an appropriate statistical method). Environ. Mol. Mutagen., 2006. Published 2005 Wiley-Liss, Inc. [source]

Enterococcus faecalis with the gelatinase phenotype regulated by the fsr operon and with biofilm-forming capacity are common in the agricultural environment

ENVIRONMENTAL MICROBIOLOGY, Issue 6 2009
Lilia Macovei
Summary The prevalence of gelatinase activity and biofilm formation among environmental enterococci was assessed. In total, 396 enterococcal isolates from swine and cattle faeces and house flies from a cattle farm were screened for gelatinase activity. The most prevalent phenotype on Todd,Hewitt agar with 1.5% skim milk was the weak protease (WP) (72.2% of isolates), followed by the strong protease (SP) 18.7%, and no protease (NP) (9.1%). The majority of WP isolates was represented by Enterococcus hirae (56.9%), followed by Enterococcus faecium (25.9%), Enterococcus casseliflavus (10.4%), Enterococcus gallinarum (5.2%) and Enterococcus saccharolyticus (1.7%). All WP isolates were negative for gelE (gelatinase) and sprE (serine protease) as well as the fsrABDC operon that regulates the two proteases, and only four isolates (7.0%) formed biofilms in vitro. All SP isolates were Enterococcus faecalis positive for the fsrABDC, gelE, sprE genes and the majority (91.2%) formed a biofilm. Diversity of NP isolates was relatively evenly distributed among E. hirae, E. faecium, E. casseliflavus, E. gallinarum, Enterococcus durans, E. saccharolyticus and Enterococcus mundtii. All NP isolates were negative for the fsr operon and only four E. hirae (11.1%) formed a biofilm. Of further interest was the loss of the gelatinase phenotype (18.9% of isolates) from SP isolates after 4 month storage at 4,8°C and several passages of subculture. Results of reverse transcription PCR analysis indicated that mRNA was produced for all the genes in the frs operon and sequencing of the gelE gene did not reveal any significant mutations. However, gelatinase was not detectable by Western blot analysis. Our study shows that E. faecalis with the complete fsr operon and the potential to form a biofilm are relatively common in the agricultural environment and may represent a source/reservoir of clinically relevant strains. In addition, many environmental enterococci, especially E. hirae, produce an unknown WP that can hydrolyse casein but does not contribute to biofilm formation. The stability of the gelatinase phenotype in E. faecalis and its regulation will require additional studies. [source]

Self-produced extracellular stimuli modulate the Pseudomonas aeruginosa swarming motility behaviour

ENVIRONMENTAL MICROBIOLOGY, Issue 10 2007
Julien Tremblay
Summary Pseudomonas aeruginosa presents three types of motilities: swimming, twitching and swarming. The latter is characterized by rapid and coordinated group movement over a semisolid surface resulting from morphological differentiation and intercellular interactions. A striking feature of P. aeruginosa swarming motility is the formation of migrating tendrils producing colonies with complex fractal-like patterns. Previous studies have shown that normal swarming motility is intimately related to the production of extracellular surface-active molecules: rhamnolipids (RLs), composed of monorhamnolipids (mono-RLs) and dirhamnolipids (di-RLs), and 3-(3-hydroxyalkanoyloxy) alkanoic acids (HAAs). Here, we report that (i) di-RLs attract active swarming cells while HAAs behave as strong repellents, (ii) di-RLs promote and HAAs inhibit tendril formation and migration, (iii) di-RLs and HAAs display different diffusion kinetics on a surface as di-RLs spread faster than HAAs in agar, (iv) di-RLs and HAAs have no effect on swimming cells, suggesting that swarming cells are different from swimming cells not only in morphology but also at the regulatory level and (v) mono-RLs act as wetting agents. We propose a model explaining how HAAs and di-RLs together modulate the behaviour of swarming migrating cells by acting as self-produced negative and positive chemotactic-like stimuli. [source]

Role of ethylenediaminetetraacetic acid on lead uptake and translocation by tumbleweed (Salsola kali L.)

ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 5 2007
Guadalupe de la Rosa
Abstract Tumbleweed plants (Salsola kali L.) grown in agar and liquid media demonstrated a high capacity to accumulate Pb in their different parts without affecting biomass. Whereas shoot elongation and biomass were not significantly affected by high tissue concentrations of Pb, root growth was significantly affected relative to controls. Roots, stems, and leaves demonstrated Pb concentrations of 31,000, 5,500, and 2,100 mg/kg dry weight, respectively, when plants were grown in the agar medium containing 80 mg Pb/L. Application of ethylenediaminetetraacetic acid (EDTA) to Pb-contaminated media dramatically reduced the total acquisition of Pb from both types of media. However, EDTA significantly increased the translocation of Pb from roots to the aerial parts, as evidenced by a multifold increase (23- and 155-fold for agar and liquid media, respectively) in the translocation concentration factor. The concentration of the antioxidant thiol compounds significantly increased (p < 0.05) in plants grown with uncomplexed Pb treatments relative to control plants. Scanning-electron microscopy and electron dispersive x-ray spectroscopic evaluation of leaf samples demonstrated an interesting pattern of Pb translocation in the presence or absence of EDTA. Large Pb crystals were found across the leaf tissues (palisade, spongy parenchyma, and conducting tissues) in the absence of EDTA. Lead nanoparticles also were seen when plants were grown in Pb-EDTA solution. Ultramicroscopic features of tumbleweed provide clear evidence for the unrestricted conduction of Pb from the root to the aerial parts, and this property makes the plant a good candidate for phytoremediation. [source]

A bipotent neural progenitor cell line cloned from a cerebellum of an adult p53 -deficient mouse generates both neurons and oligodendrocytes

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 11 2005
Mitsutoshi Tominaga
Abstract Here we report developmental characteristics of a clonal cell line 2Y-3t established from a multifocal neoplasm that arose in a cerebellum of an adult p53 -deficient mouse. The tumorigenicity of the line was not observed in soft agar assay or in nude mouse assay. In serum-containing medium, 2Y-3t cells were epithelial-like in morphology and were mitotic. When they were cultured in serum-free medium, the expressions of neural stem and/or progenitor cell markers were decreased. Concomitantly, the expressions of neuronal and oligodendrocyte markers were increased in concert with morphological differentiation, and DNA synthesis ceased. None of astrocyte markers were detected under these culture conditions. Double-labelling studies revealed that two cell populations coexisted, expressing neuronal or oligodendrocyte markers. Triiodothyronine (T3) increased the oligodendrocyte population when 2Y-3t cells were cultured in serum-free medium. Recloning of the line gave rise to three types of subclones. Sixteen subclones were capable of generating both neurons and oligodendrocytes, four subclones were capable of generating only neurons and one subclone was capable of generating only oligodendrocytes. Thus, 2Y-3t cells have characteristics of bipotent neural progenitor cells capable of generating both neurons and oligodendrocytes. In addition, the line expressed mRNA for Pax-2 and had GAD67-positive cells when cultured in serum-free medium. However, none of the mRNAs for Zic-1, Math1, zebrin or Calbindin-D28k were detected, suggesting that the 2Y-3t line might generate the GABAergic interneuron lineage of the mouse cerebellum. [source]

Structural studies of the capsular polysaccharide and lipopolysaccharide O-antigen of Aeromonas salmonicida strain 80204-1 produced under in vitro and in vivo growth conditions

FEBS JOURNAL, Issue 22 2004
Zhan Wang
Aeromonas salmonicida is a pathogenic aquatic bacterium and the causal agent of furunculosis in salmon. In the course of this study, it was found that when grown in vitro on tryptic soy agar, A. salmonicida strain 80204-1 produced a capsular polysaccharide with the identical structure to that of the lipopolysaccharide O-chain polysaccharide. A combination of 1D and 2D NMR methods, including a series of 1D analogues of 3D experiments, together with capillary electrophoresis-electrospray MS (CE-ES-MS), compositional and methylation analyses and specific modifications was used to determine the structure of these polysaccharides. Both polymers were shown to be composed of linear trisaccharide repeating units consisting of 2-acetamido-2-deoxy- d -galacturonic acid (GalNAcA), 3-[(N -acetyl-L-alanyl)amido]-3,6-dideoxy- d -glucose{3-[(N -acetyl- l -alanyl)amido]-3-deoxy- d -quinovose, Qui3NAlaNAc} and 2-acetamido-2,6-dideoxy- d -glucose (2-acetamido-2-deoxy- d -quinovose, QuiNAc) and having the following structure: [,3)- , - d -GalpNAcA-(1,3)- , - d -QuipNAc-(1,4)- , - d -Quip3NAlaNAc-(1-]n, where GalNAcA is partly presented as an amide and AlaNAc represents N -acetyl- l -alanyl group. CE-ES-MS analysis of CPS and O-chain polysaccharide confirmed that 40% of GalNAcA was present in the amide form. Direct CE-ES-MS/MS analysis of in vivo cultured cells confirmed the formation of a novel polysaccharide, a structure also formed in vitro, which was previously undetectable in bacterial cells grown within implants in fish, and in which GalNAcA was fully amidated. [source]

Pollen morphology, leaf surfaces, mycobiota diversity and leaf spots of three species of Zygophyllum growing along Cairo-Suez desert road, Eastern (Arabian) desert in Egypt

FEDDES REPERTORIUM, Issue 1-2 2007
S. M. El Naggar
Three native species of Zygophyllum: Z. coccinum L., Z. decumbens L. and Z. simplex L. (Zygophyllaceae) have been investigated morphologically, palynologically and mycologically. Twenty-two fungal species belonging to 11 genera were collected from leaf surfaces (11 genera and 22 species) and anthers/ pollen grains (7, 13) of Zygophyllum coccinum, Z. decumbens and Z. simplex on Czapek-Dox agar at 25 °C. Fungal diversity of the two microhabitats is basically similar and the most prevalent fungi were Alternaria alternata /A. phragmospora, Cladosporium cladosporioides /C. herbarum and Ulocladium botrytis /U. consortiale. Alternaria alternata, Cladosporium cladosporioides and C. herbarum -leaf spots were rarely recorded in the three studied plant species. Leaf lamina size and sculpture of the studied taxa almost seem to be the most reliable factors of the fungal biodiversity on the studied plant species. On the other hand, reticulate-micro reticulate pollen type is the only pollen type recorded in the present study which reflects that the very narrow range of spectrum of fungal biodiversity between the studied plant species. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) Pollenmorphologie, Blattoberfläche, mykobiotische Diversität und Blattflecken von drei Zygophyllum -Arten entlang der Wüstenstraße Kairo,Suez, Östliche (Arabische) Wüste Ägyptens Drei einheimische Zygophyllum -Arten (Z. coccinum, Z. decumbens und Z. simplex (Zygophyllaceae) wurden morphologisch, palynologisch und mykologisch untersucht. 22 Pilzarten aus elf Gattungen wurden von Blattoberflächen gesammelt (11 Gattungen, 22 Arten) und Antheren/Pollenkörner (7, 13) von Zygophyllum coccinum, Z. decumbens und Z. simplex mittels Czapek-Dox agar bei 25 °C untersucht. Die Pilzdiversität beider Mikrohabitate ist basisähnlich und die häufigsten Taxa sind: Alternaria alternata /A. phragmospora, Cladosporium cladosporioides /C. herbarum und Ulocladium botrytis /U. consor- tiale. Blattflecken von Alternaria alternata, Cladosporium cladosporioides und C. herbarum wurden auf den untersuchten Pflanzen selten verzeichnet. Die Größe der Blattlamina und die Skulptur der untersuchten Taxa scheinen die zuverlässigsten (häufigsten) Faktoren für die Pilz-Biodiversität auf den untersuchten Pflanzen zu sein. Andererseits ist der retikulate-microretikulate Pollentyp in vorliegender Studie der einzige Pollentyp, der dieses enge Spektrum der Pilz-Biodiversität zwischen den untersuchten Pflanzen aufzeigt (widerspiegelt). [source]

Starvation-induced changes in the cell surface of Azospirillum lipoferum

FEMS MICROBIOLOGY ECOLOGY, Issue 1 2000
Thelma Castellanos
Abstract Three starvation regimes (a deficient culture medium, a saline buffer solution and distilled water) were evaluated for their possible effect on cell surface characteristics of Azospirillum lipoferum 1842 related to the initial adsorption of the bacterium to surfaces. The bacteria survived for 7 days in all media although they did not multiply. Upon transfer from a rich growth medium (nutrient agar) to starvation conditions, cell surface hydrophobicity dropped sharply but recovered its initial value within 24 to 48 h, except in phosphate-buffered saline, the length of the recovery period depending on the starvation medium. Starvation affected the sugar affinity of the A. lipoferum cell surface mainly towards p -aminophenyl-,- D -mannopyranoside, to a lesser extent to glucose, but not to other monosaccharides tested. Starvation changed the concentration of several cell surface proteins but did not induce the synthesis of new ones. The cell surface hydrophobic protein (43 kDa) of A. lipoferum 1842 was unaffected by any starvation treatment for a period of up to 48 h, but later disappeared. These data showed that starvation is not a major factor in inducing changes in the cell surface which lead to the primary phase of attachment of Azospirillum to surfaces. [source]

Isolation of a Carnobacterium maltaromaticum- like bacterium from systemically infected lake whitefish (Coregonus clupeaformis)

FEMS MICROBIOLOGY LETTERS, Issue 1 2008
Thomas P. Loch
Abstract Herein we report on the first isolation of a Carnobacterium maltaromaticum -like bacterium from kidneys and swim bladders of lake whitefish (Coregonus clupeaformis) caught from Lakes Michigan and Huron, Michigan. Isolates were Gram-positive, nonmotile, facultatively anaerobic, asporogenous rods that did not produce catalase, cytochrome oxidase, or H2S, and did not grow on acetate agar. Except for carbohydrate fermentation, many phenotypic characteristics of lake whitefish isolates coincided with those of C. maltaromaticum, the causative agent of pseudokidney disease. Partial sequencing of 16S and 23S rRNA genes, as well as the piscicolin 126 precursor gene, yielded 97% and 98% nucleotide matches with C. maltaromaticum, respectively (accession numbers EU546836 and EU546837; EU643471). Phylogenetic analyses showed that lake whitefish isolates of this study are highly related, yet not fully identical to C. maltaromaticum. The presence of the C. maltaromaticum -like bacterium was associated with splenomegaly, renal and splenic congestion, and thickening of the swim bladder wall with accumulation of a mucoid exudate. Examination of stained tissue sections revealed renal and splenic congestion, vacuolation and bile stasis within the liver, and hyperplasia within the epithelial lining of the swim bladder. The concurrent presence of pathological changes and the C. maltaromaticum -like bacteria suggests that this bacterium is pathogenic to lake whitefish. [source]

Structure,fungitoxicity relationships of some volatile flavour constituents of the edible mushrooms Agaricus bisporus and Pleurotus florida

FLAVOUR AND FRAGRANCE JOURNAL, Issue 4 2001
Eugene Sebastian J. Nidiry
Abstract The fungitoxicity of the diethyl ether extracts of two basidiomycete mushrooms, Agaricus bisporus and Pleurotus florida, and 14 flavour constituents present in these mushrooms is being reported. Median effective molar concentrations (EC50) of the compounds for the mycelial growth inhibition of Colletotrichum gloeosporioides on potato,dextrose,agar (PDA) medium were computed and compared. Among the constituents tested for fungitoxicity, 1-octanol exhibited the highest activity. Structure,activity relationship studies of the constituents revealed that high hydrophobicity of the alkyl moiety, the presence of the primary alcoholic group and the absence of branching of the alkyl group are responsible for the high activity of 1-octanol. Copyright © 2001 John Wiley & Sons, Ltd. [source]

Effect of fungicides, endophytes and fungal filtrates on in vitro growth of Spanish isolates of Gremmeniella abietina

FOREST PATHOLOGY, Issue 4 2007
O. Santamaría
Summary The effect of eight fungicides and 15 endophytes isolated from twigs of healthy Pinus halepensis trees on the growth rate of four Spanish isolates of the pathogen Gremmeniella abietina was evaluated in vitro. In the fungicide experiments, four doses of each fungicide tested were added to the growth medium. In the endophyte experiments, dual cultures endophyte-pathogen were paired in Petri dishes. Furthermore, growth of three G. abietina isolates was evaluated on malt agar with pine needle extract amended with filtrates from cultures of endophyte E14, which produced a brownish compound apparently inhibiting G. abietina growth. The results obtained suggested that chlorothalonil and daconil were the most suitable fungicides at low doses to reduce growth of G. abietina isolates from Spain. Four of the endophytes tested in vitro showed strong antagonistic activity against G. abietina and deserve further testing in vivo. The endophyte E14 produced in vitro a brownish compound which almost completely inhibited mycelial growth of G. abietina isolates from Spain. [source]

Phylogeographic variation among isolates of the Sirococcus conigenus P group

FOREST PATHOLOGY, Issue 1 2007
H. Konrad
Summary In this study the phylogeographic variation among isolates of the Sirococcus conigenus P group and the phylogenetic relationships of S. conigenus with Sirococcus clavigignenti-juglandacearum and other species previously placed in the genus Sirococcus were investigated. A collection of 33 isolates originating from Picea, Pinus and Larix in Europe, North America and Bhutan were characterized by sequence analyses of the internal transcribed spacer (ITS) region (including ITS1, 5.8S ribosomal DNA, ITS2) of the nuclear rDNA and a portion of the , -tubulin gene. In phylogenetic analyses most isolates from pine, spruce and larch formed a distinct clade, representing the P group of S. conigenus, which was separated from the T group of this pathogen. Four isolates from Picea in Europe and Canada formed a third clade within S. conigenus and these isolates are referred to as the S group. The P group consisted of five distinct ITS haplotypes, which partly differed in their optimum growth temperature and their growth rates at 25°C on malt extract agar. Nested clade analysis resolved the five haplotypes into three distinct clades and revealed significant genetic/geographic associations for some of the haplotypes. Parsimony analysis of the small subunit (18S) ribosomal DNA sequences confirmed the phylogenetic affinities between S. conigenus and S. clavigignenti-juglandacearum. In contrast, Godronia cassandrae and Hormococcus conorum, which formerly had been placed in the genus Sirococcus, were found to be only distantly related to S. conigenus and S. clavigignenti-juglandacearum. [source]

Palatability of macrophytes to the invasive freshwater snail Pomacea canaliculata: differential effects of multiple plant traits

FRESHWATER BIOLOGY, Issue 10 2010
PAK KI WONG
Summary 1.,By selective grazing, invasive grazers can alter macrophyte-herbivore relationships in shallow freshwater bodies. Evaluating the palatability of macrophytes and understanding the determinants of plant palatability can help predict grazing impact. In no-choice feeding assays, we tested the palatability of 21 species of freshwater macrophytes to the invasive freshwater apple snail Pomacea canaliculata. 2.,Daily feeding rate varied greatly with plant species, ranging from 1.1 to 22% of snail body mass. We assessed six plant properties and examined their correlation with feeding rate. Total nitrogen content was positively related, and C:N ratio and dry matter content (DMC) negatively related, to snail feeding rate. There was no significant correlation between snail feeding rate and plant phenolic content, but the feeding rate on Myriophyllum aquaticum (the plant with the highest phenolic content) was very low. 3.,We repeated the feeding assays for 15 species that were not palatable as fresh leaves with reconstituted plant tissues formed by mixing ground up dried leaves with agar. The feeding rate still differed greatly among macrophyte species. Phragmites australis and Vallisneria natans (two species with the highest DMC) were eaten much more as reconstituted plant than as fresh leaves, indicating that structure (i.e. DMC) may be important in their defence against snail herbivory. For two plants (M. aquaticum and Alternanthera philoxeroides) that had moderate amounts of nitrogen/phosphorus but were consumed very little as fresh and reconstituted tissues, we incorporated their extracts into a palatable agar-based food. The extracts from both species greatly reduced snail feeding rate, indicating the presence of chemical defences in these two species. 4.,These results indicated that feeding was affected by several plant traits. The snail favoured plants with a high nitrogen content and avoided plants with a high DMC. Only a few plants possessed chemical feeding deterrents that were effective against this snail. Given the invasive spread of P. canaliculata in Asia, ecologists and managers should consider plant palatability when selecting plants for use in wetland restoration and when predicting the impact of further invasion by this species. [source]

Olfactory information saves venom during prey-capture of the hunting spider Cupiennius salei (Araneae: Ctenidae)

FUNCTIONAL ECOLOGY, Issue 2 2006
S. HOSTETTLER
Summary 1The Neotropical spider Cupiennius salei Keyserling (Ctenidae) selects prey in a manner consistent with the amount of venom available in its venom glands. It distinguishes the venom sensitivity of different prey species, and uses its venom economically (according to the venom-optimization hypothesis). 2A prey-choice experiment was performed to test whether spiders use olfactory cues to detect prey and select prey items that are appropriate for their amount of available venom. 3The spider could choose between two similar prey dummies made of agar. We added the odour of two prey species, either by adding minced insects to an agar block or by offering it on filter paper which had previously been exposed to the living prey. Cupiennius salei spiders had either full or emptied venom glands. 4Two insects of distinctive venom sensitivity, but high acceptance, were tested: a sensitive cricket and a less sensitive cockroach. 5Using video surveillance, we found an attraction effect of prey odour in the prey-capture behaviour of C. salei. Spiders preferred agar pieces with minced insects or insect odour on filter paper over non-smelling items. Reaction frequency and attack rates were equal for spiders with full venom glands if they had to choose between cricket and cockroach odour. When the venom glands were empty, however, C. salei significantly preferred the venom-sensitive cricket over the venom-insensitive cockroach. 6We showed for the first time that C. salei uses its olfactory sense to detect prey items, and distinguishes between prey species with low and high sensitivity to spider venom. This study supports the venom-optimization hypothesis. [source]

LPXN, a member of the paxillin superfamily, is fused to RUNX1 in an acute myeloid leukemia patient with a t(11;21)(q12;q22) translocation

GENES, CHROMOSOMES AND CANCER, Issue 12 2009
Hai-Ping Dai
RUNX1 (previously AML1) is involved in multiple recurrent chromosomal rearrangements in hematological malignances. Recently, we identified a novel fusion between RUNX1 and LPXN from an acute myeloid leukemia (AML) patient with t(11;21)(q12;q22). This translocation generated four RUNX1/LPXN and one LPXN/RUNX1 chimeric transcripts. Two representative RUNX1/LPXN fusion proteins, RL and RLs, were both found to localize in the nucleus and could bring the CBFB protein into the nucleus like the wild-type RUNX1. Both fusion proteins inhibit the ability of RUNX1 to transactivate the CSF1R promoter, probably through competition for its target sequences. Unlike RL and RLs, the LPXN/RUNX1 fusion protein LR was found to localize in the cytoplasm. Thus, we believe it has little impact on the transcriptional activity of RUNX1. We also found that fusion proteins RL, RLs, LR, and wild-type LPXN could confer NIH3T3 cells with malignant transformation characteristics such as more rapid growth, the ability to form colonies in soft agar, and the ability to form solid tumors in the subcutaneous tissue of the BALB/c nude mice. Taken together, our data indicated that the RUNX1/LPXN and LPXN/RUNX1 fusion proteins may play important roles in leukemogenesis and that deregulation of cell adhesion pathways may be pathogenetically important in AML. Our study also suggests that LPXN may play an important role in carcinogenesis. © 2009 Wiley-Liss, Inc. [source]