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Sample records for sporulation medium modified

  1. Sporulation of Clostridium cylindrosporum on a Defined, Low-Manganese Medium

    OpenAIRE

    Sacks, L. E.; Smith, M. R.

    1987-01-01

    Clostridium cylindrosporum HC-1 grew and sporulated well on a defined medium. This is the first demonstration of sporulation of a purinolytic clostridium on a defined medium; manganese levels were below those considered essential for sporulation of most Bacillus species. Sporulation appeared to be initiated before exhaustion of the purine substrate.

  2. The effect of sporulation medium on Alicyclobacillus acidoterrestris guaiacol production in apple juice

    OpenAIRE

    Molva, Çelenk; Baysal, Ayşe Handan

    2016-01-01

    The present study evaluated the effect of sporulation medium on guaiacol formation from vanillin and vanillic acid by Alicyclobacillus acidoterrestris DSM 3922 in the reconstituted apple juice (pH 3.82, °Brix 11.3). For sporulation, potato dextrose agar and Bacillus acidoterrestris agar were used. After heat-activation, spores were turned into vegetative cells and inoculated into juice samples to a final concentration of 103 or 105 CFU/mL. Samples were incubated at 37 °C for 264 h and guaiaco...

  3. Differential effects of sporulation temperature on the high pressure resistance of Clostridium botulinum type E spores and the interconnection with sporulation medium cation contents.

    Science.gov (United States)

    Lenz, Christian A; Vogel, Rudi F

    2015-04-01

    High pressure thermal (HPT) processing can be used to improve traditional preservation methods and increase food safety and durability, whereas quality related characteristics can be largely maintained. Clostridium (C.) botulinum type E is a non-proteolytic, psychrotrophic, toxin-producing spore former, commonly associated with aquatic environments in temperate regions of the northern hemisphere. Sporulation in nature is likely to occur under varying conditions including temperature and nutrient availability, which might affect resistance properties of resulting spores. In our study, we determined the effect of sporulation temperature (13-38 °C) on the resistance of three Clostridium botulinum type E strains to differently intense HPT treatments (200 MPa at 40 and 80 °C, and 800 MPa at 40 and 80 °C). Furthermore, the effect of cations on sporulation temperature-mediated alterations in HHP resistance was investigated. Results indicate that low and high sporulation temperatures can increase and decrease sporal HPT resistance, respectively, in a treatment-dependent (pressure level, treatment temperature) manner, whereas the trends observed are largely unaffected by pressure dwells (1 s-10 min). Furthermore, results show that the cation content of the sporulation medium (Ca(2+), Mg(2+), Mn(2+)) marginally influences and partially counteracts effects on the HPT resistance of spores grown at low and elevated temperatures, respectively. This suggests that sporulation temperature and medium cations provoke changes in some common spore resistance structures. Sporulation conditions can markedly affect spore resistance properties and, thus, should be considered for the experimental setup of worst case studies aiming to evaluate the effectiveness of food processes in terms of the inactivation of C. botulinum type E spores. Copyright © 2014 Elsevier Ltd. All rights reserved.

  4. A Novel Cell Type Enables B. subtilis to Escape from Unsuccessful Sporulation in Minimal Medium.

    Science.gov (United States)

    Defeu Soufo, Hervé Joël

    2016-01-01

    Sporulation is the most enduring survival strategy developed by several bacterial species. However, spore development of the model organism Bacillus subtilis has mainly been studied by means of media or conditions optimized for the induction of sporogenesis. Here, I show that during prolonged growth during stationary phase in minimal medium, B. subtilis undergoes an asymmetric cell division that produces small and round-shaped, DNA containing cells. In contrast to wild-type cells, mutants harboring spo0A or spoIIIE / sftA double mutations neither sporulate nor produce this special cell type, providing evidence that the small round cells emerge from the abortion of endospore formation. In most cases observed, the small round cells arise in the presence of sigma H but absence of sigma F activity, different from cases of abortive sporulation described for rich media. These data suggest that in minimal media, many cells are able to initiate but fail to complete spore development, and therefore return to normal growth as rods. This work reveals that the continuation of asymmetric cell division, which results in the formation of the small round cells, is a way for cells to delay or escape from-unsuccessful-sporulation. Based on these findings, I suggest to name the here described cell type as "dwarf cells" to distinguish them from the well-known minicells observed in mutants defective in septum placement or proper chromosome partitioning.

  5. A Novel Cell Type Enables B. subtilis To Escape From Unsuccessful Sporulation In Minimal Medium

    Directory of Open Access Journals (Sweden)

    Herve Joel Defeu Soufo

    2016-11-01

    Full Text Available Sporulation is the most enduring survival strategy developed by several bacterial species. However, spore development of the model organism Bacillus subtilis has mainly been studied by means of media or conditions optimized for the induction of sporogenesis. Here, I show that during prolonged growth during stationary phase in minimal medium, B. subtilis undergoes an asymmetric cell division that produces small and round-shaped, DNA containing cells. In contrast to wild-type cells, mutants harboring spo0A or spoIIIE/sftA double mutations neither sporulate nor produce this special cell type, providing evidence that the small round cells emerge from the abortion of endospore formation. In most cases observed, the small round cells arise in the presence of sigma H but absence of sigma F activity, different from cases of abortive sporulation described for rich media. These data suggest that in minimal media, many cells are able to initiate but fail to complete spore development, and therefore return to normal growth as rods. This work reveals that the continuation of asymmetric cell division, which results in the formation of the small round cells, is a way for cells to delay or escape from - unsuccessful - sporulation. Based on these findings, I suggest to name the here described cell type as dwarf cells to distinguish them from the well-known minicells observed in mutants defective in septum placement or proper chromosome partitioning.

  6. Influence of glutamate on growth, sporulation, and spore properties of Bacillus cereus ATCC 14579 in defined medium

    NARCIS (Netherlands)

    Vries, de Y.P.; Atmadja, R.D.; Hornstra, L.M.; Vos, de W.M.; Abee, T.

    2005-01-01

    A chemically defined medium in combination with an airlift fermentor system was used to study the growth and sporulation of Bacillus cereus ATCC 14579. The medium contained six amino acids and lactate as the main carbon sources. The amino acids were depleted during exponential growth, while lactate

  7. Optimizing sporulation of Clostridium perfringens

    NARCIS (Netherlands)

    Jong, de A.E.I.; Beumer, R.R.; Rombouts, F.M.

    2002-01-01

    Many sporulation media have been developed for Clostridium perfringens, but none stimulates sporulation for all strains. The aim of our experiments was to develop a sporulation method using Duncan and Strong (DS) medium, which supports sporulation of a wide variety of strains. Different inoculation

  8. Nitrate salts suppress sporulation and production of enterotoxin in Clostridium perfringens strain NCTC8239.

    Science.gov (United States)

    Yasugi, Mayo; Otsuka, Keisuke; Miyake, Masami

    2016-10-01

    Clostridium perfringens type A is a common source of food-borne illness in humans. Ingested vegetative cells sporulate in the small intestinal tract and in the process produce C. perfringens enterotoxin (CPE). Although sporulation plays a critical role in the pathogenesis of food-borne illness, the molecules triggering/inhibiting sporulation are still largely unknown. It has previously been reported by our group that sporulation is induced in C. perfringens strain NCTC8239 co-cultured with Caco-2 cells in Dulbecco's Modified Eagle Medium (DMEM). In contrast, an equivalent amount of spores was not observed when bacteria were co-cultured in Roswell Park Memorial Institute-1640 medium (RPMI). In the present study it was found that, when these two media are mixed, RPMI inhibits sporulation and CPE production induced in DMEM. When a component of RPMI was added to DMEM, it was found that calcium nitrate (Ca[NO 3 ] 2 ) significantly inhibits sporulation and CPE production. The number of spores increased when Ca(NO 3 ) 2 -deficient RPMI was used. The other nitrate salts significantly suppressed sporulation, whereas the calcium salts used did not. qPCR revealed that nitrate salts increased expression of bacterial nitrate/nitrite reductase. Furthermore, it was found that nitrite and nitric oxide suppress sporulation. In the sporulation stages, Ca(NO 3 ) 2 down-regulated the genes controlled by Spo0A, a master regulator of sporulation, but not spo0A itself. Collectively, these results indicate that nitrate salts suppress sporulation and CPE production by down-regulating Spo0A-regulated genes in C. perfringens strain NCTC8239. Nitrate reduction may be associated with inhibition of sporulation. © 2016 The Societies and John Wiley & Sons Australia, Ltd.

  9. Effect of sporulation medium on wet-heat resistance and structure of Alicyclobacillus acidoterrestris DSM 3922-type strain spores and modeling of the inactivation kinetics in apple juice.

    Science.gov (United States)

    Molva, Celenk; Baysal, Ayse Handan

    2014-10-17

    Alicyclobacillus acidoterrestris is a spoilage bacterium in fruit juices leading to high economic losses. The present study evaluated the effect of sporulation medium on the thermal inactivation kinetics of A. acidoterrestris DSM 3922 spores in apple juice (pH3.82±0.01; 11.3±0.1 °Brix). Bacillus acidocaldarius agar (BAA), Bacillus acidoterrestris agar (BATA), malt extract agar (MEA), potato dextrose agar (PDA) and B. acidoterrestris broth (BATB) were used for sporulation. Inactivation kinetic parameters at 85, 87.5 and 90°C were obtained using the log-linear model. The decimal reduction times at 85°C (D85°C) were 41.7, 57.6, 76.8, 76.8 and 67.2min; D87.5°C-values were 22.4, 26.7, 32.9, 31.5, and 32.9min; and D90°C-values were 11.6, 9.9, 14.7, 11.9 and 14.1min for spores produced on PDA, MEA, BATA, BAA and BATB, respectively. The estimated z-values were 9.05, 6.60, 6.96, 6.15, and 7.46, respectively. The present study suggests that the sporulation medium affects the wet-heat resistance of A. acidoterrestris DSM 3922 spores. Also, the dipicolinic acid content (DPA) was found highest in heat resistant spores formed on mineral containing media. After wet-heat treatment, loss of internal volume due to the release of DPA from spore core was observed by scanning electron microscopy. Since, there is no standardized media for the sporulation of A. acidoterrestris, the results obtained from this study might be useful to determine and compare the thermal resistance characteristics of A. acidoterrestris spores in fruit juices. Copyright © 2014 Elsevier B.V. All rights reserved.

  10. Protein patterns of yeast during sporulation

    International Nuclear Information System (INIS)

    Litske Petersen, J.G.; Kielland-Brandt, M.C.; Nilsson-Tillgren, T.

    1979-01-01

    High resolution two-dimensional gel electrophoresis was used to study protein synthesis during synchronous meiosis and ascospore formation of Saccharomyces cerevisiae. The stained protein patterns of samples harvested at any stage between meiotic prophase and the four-spore stage in two sporulating strains showed the same approximately 250 polypeptides. Of these only a few seemed to increase or decrease in concentration during sporulation. The characteristic pattern of sporulating yeast was identical to the pattern of glucose-grown staitonary yeast cells adapted to respiration. The latter type of cells readily initiates meiosis when transferred to sporulation medium. This pattern differed from the protein patterns of exponentially growing cells in glucose or acetate presporulation medium. Five major proteins in stationary and sporulating yeast cells were not detected in either type of exponential culture. Two-dimensional autoradiograms of [ 35 S]methionine-labelled yeast proteins revealed that some proteins were preferentially labelled during sporulation, while other proteins were labelled at later stages. These patterns differed from the auroradiograms of exponentially growing yeast cells in glucose presporulation medium in a number of spots. No differences were observed when stained gels or autoradiograms of sporulating cultures and non-sporulating strains in sporulation medium were compared. (author)

  11. 6S-1 RNA function leads to a delay in sporulation in Bacillus subtilis.

    Science.gov (United States)

    Cavanagh, Amy T; Wassarman, Karen M

    2013-05-01

    We have discovered that 6S-1 RNA (encoded by bsrA) is important for appropriate timing of sporulation in Bacillus subtilis in that cells lacking 6S-1 RNA sporulate earlier than wild-type cells. The time to generate a mature spore once the decision to sporulate has been made is unaffected by 6S-1 RNA, and, therefore, we propose that it is the timing of onset of sporulation that is altered. Interestingly, the presence of cells lacking 6S-1 RNA in coculture leads to all cell types exhibiting an early-sporulation phenotype. We propose that cells lacking 6S-1 RNA modify their environment in a manner that promotes early sporulation. In support of this model, resuspension of wild-type cells in conditioned medium from ΔbsrA cultures also resulted in early sporulation. Use of Escherichia coli growth as a reporter of the nutritional status of conditioned media suggested that B. subtilis cells lacking 6S-1 RNA reduce the nutrient content of their environment earlier than wild-type cells. Several pathways known to impact the timing of sporulation, such as the skf- and sdp-dependent cannibalism pathways, were eliminated as potential targets of 6S-1 RNA-mediated changes, suggesting that 6S-1 RNA activity defines a novel mechanism for altering the timing of onset of sporulation. In addition, 6S-2 RNA does not influence the timing of sporulation, providing further evidence of the independent influences of these two related RNAs on cell physiology.

  12. Banana peel culture as an indigenous medium for easy identification of late-sporulation human fungal pathogens.

    Science.gov (United States)

    Kindo, A J; Tupaki-Sreepurna, A; Yuvaraj, M

    2016-01-01

    Fungi are increasing in incidence as human pathogens and newer and rarer species are continuously being encountered. Identifying these species from growth on regular culture media may be challenging due to the absence of typical features. An indigenous and cheap medium, similar to the natural substrate of these fungi, was standardised in our laboratory as an aid to species identification in a conventional laboratory setting. Ripe banana peel pieces, sterilised in an autoclave at 121°C temperature and 15 lbs pressure for 15 min promoted good growth of hyphae and pycnidia or acervuli in coelomycetes, flabelliform and medusoid fruiting bodies of basidiomycetes and fruit bodies such as cleistothecium in ascomycetes. The growth from the primary isolation medium was taken and inoculated onto the pieces of double-autoclaved ripe banana peel pieces in a sterile glass Petri dish with some moisture (sprinkles of sterile distilled water). A few sterile coverslips were placed randomly inside the Petri dish for the growing fungus to stick on to it. The plates were kept at room temperature and left undisturbed for 15-20 days. At a time, one coverslip was taken out and placed on a slide with lactophenol cotton blue and focused under the microscope to look for fruit bodies. Lasiodiplodia theobromae, Macrophomina phaseolina, Nigrospora sphaerica, Chaetomium murorum, Nattrassia mangiferae and Schizophyllum commune were identified by characteristic features from growth on banana peel culture. Banana peel culture is a cheap and effective medium resembling the natural substrate of fungi and is useful for promoting characteristic reproductive structures that aid identification.

  13. Comparison of a modified peptone water transport medium with two ...

    African Journals Online (AJOL)

    A laboratory modified peptone water medium was evaluated alongside Stuart and Amies media for their relative suitability as transport media for aerobic bacteria isolated from wound specimens obtained from Central Hospital, Benin City, Nigeria. The survival rates of isolates from the three media were assessed ...

  14. Cell-density-dependent lysis and sporulation of Myxococcus xanthus in agarose microbeads.

    OpenAIRE

    Rosenbluh, A; Nir, R; Sahar, E; Rosenberg, E

    1989-01-01

    Vegetative cells of Myxococcus xanthus were immobilized in 25-microns-diameter agarose microbeads and incubated in either growth medium or sporulation buffer. In growth medium, the cells multiplied, glided to the periphery, and then filled the beads. In sporulation buffer, up to 90% of the cells lysed and ca. 50% of the surviving cells formed resistant spores. A strong correlation between sporulation and cell lysis was observed; both phenomena were cell density dependent. Sporulation proficie...

  15. Degradation testing of Mg alloys in Dulbecco's modified eagle medium: Influence of medium sterilization.

    Science.gov (United States)

    Marco, Iñigo; Feyerabend, Frank; Willumeit-Römer, Regine; Van der Biest, Omer

    2016-05-01

    This work studies the in vitro degradation of Mg alloys for bioabsorbable implant applications under near physiological conditions. For this purpose, the degradation behaviour of Mg alloys in Dulbecco's modified eagle medium (DMEM) which is a commonly used cell culture medium is analysed. Unfortunately, DMEM can be contaminated by microorganisms, acidifying the medium and accelerating the Mg degradation process by dissolution of protective degradation layers, such as (Mgx,Cay)(PO4)z. In this paper the influence of sterilization by applying UV-C radiation and antibiotics (penicillin/streptomycin) is analysed with two implant material candidates: Mg-Gd and Mg-Ag alloys; and pure magnesium as well as Mg-4Y-3RE as a reference. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. Degradation testing of Mg alloys in Dulbecco's modified eagle medium: Influence of medium sterilization

    International Nuclear Information System (INIS)

    Marco, Iñigo; Feyerabend, Frank; Willumeit-Römer, Regine; Van der Biest, Omer

    2016-01-01

    This work studies the in vitro degradation of Mg alloys for bioabsorbable implant applications under near physiological conditions. For this purpose, the degradation behaviour of Mg alloys in Dulbecco's modified eagle medium (DMEM) which is a commonly used cell culture medium is analysed. Unfortunately, DMEM can be contaminated by microorganisms, acidifying the medium and accelerating the Mg degradation process by dissolution of protective degradation layers, such as (Mg_x,Ca_y)(PO_4)_z. In this paper the influence of sterilization by applying UV-C radiation and antibiotics (penicillin/streptomycin) is analysed with two implant material candidates: Mg–Gd and Mg–Ag alloys; and pure magnesium as well as Mg–4Y–3RE as a reference. - Highlights: • Contamination of DMEM by microorganisms increases the degradation rate of Mg. • Mg and its alloys show passivation during long term immersion tests in DMEM. • The use of a control sample position is essential to assess H_2 evolution in DMEM.

  17. Substitution of the radiation requirement for sporulation by host tissue in Dendrophoma obscurans

    International Nuclear Information System (INIS)

    Binder, F.L.; Lilly, V.G.

    1975-01-01

    Cultures of Dendrophoma obscurans growing on a 10--2 glucose-casein hydrolysate medium required radiation for sporulation. When leaf discs from host tissue or certain plants, particularly members of the Rosaceae, were added to the basal medium, sporulation occurred abundantly in darkness on the leaf surface. The ability to replace the radiation requirement for sporulation did not occur with all plant tissue tested. The active substance in powdered host tissue could be extracted with certain organic solvents but not with water. This crude extract could be concentrated, autoclaved, and when added to the basal medium supported sporulation in darkness

  18. Phosphate limitation induces sporulation in the chytridiomycete Blastocladiella emersonii.

    Science.gov (United States)

    Bongiorno, Vagner Alexandre; Ferreira da Cruz, Angela; Nunis da Silva, Antonio; Corrêa, Luiz Carlos

    2012-09-01

    The cell cycle is controlled by numerous mechanisms that ensure correct cell division. If growth is not possible, cells may eventually promote autophagy, differentiation, or apoptosis. Microorganisms interrupt their growth and differentiate under general nutrient limitation. We analyzed the effects of phosphate limitation on growth and sporulation in the chytridiomycete Blastocladiella emersonii using kinetic data, phase-contrast, and laser confocal microscopy. Under phosphate limitation, zoospores germinated and subsequently formed 2-4 spores, regardless of the nutritional content of the medium. The removal of phosphate at any time during growth induced sporulation of vegetative cells. If phosphate was later added to the same cultures, growth was restored if the cells were not yet committed to sporulation. The cycles of addition and withdrawal of phosphate from growth medium resulted in cycles of germination-growth, germination-sporulation, or germination-growth-sporulation. These results show that phosphate limitation is sufficient to interrupt cell growth and to induce complete sporulation in B. emersonii. We concluded that the determination of growth or sporulation in this microorganism is linked to phosphate availability when other nutrients are not limiting. This result provides a new tool for the dissection of nutrient-energy and signal pathways in cell growth and differentiation.

  19. Potato carrot agar with manganese as an isolation medium for Alternaria, Epicoccum and Phoma

    DEFF Research Database (Denmark)

    Sørensen, Jens Laurids; Mogensen, Jesper Mølgaard; Thrane, Ulf

    2009-01-01

    A semi-selective medium for isolation of Alternaria spp., Epicoccum sp. and Phoma spp. from soil and plant samples was developed. The basal medium was a modified potato carrot agar (PCA), containing 10 g/L of potato and carrot. It is known that the target genera sporulate well on standard PCA when...

  20. Asexual sporulation facilitates adaptation

    NARCIS (Netherlands)

    Zhang, Jianhua; Debets, A.J.M.; Verweij, P.E.; Melchers, W.J.G.; Zwaan, B.J.; Schoustra, S.E.

    2015-01-01

    Understanding the occurrence and spread of azole resistance in Aspergillus fumigatus is crucial for public health. It has been hypothesized that asexual sporulation, which is abundant in nature, is essential for phenotypic expression of azole resistance mutations in A. fumigatus facilitating

  1. Effect of iodoacetic acid on 59Fe uptake and aconitase aivity during sporulation of Bacillus cereus T

    International Nuclear Information System (INIS)

    Twari, B.K.; Sharma, D.

    1975-01-01

    Iodoacetic acid (IAA), a well known inhibitor of glycolysis, inhibited sporulation of B. cereus T when added to the culture just prior to the transition stage at 2-2.5 hr. In the inhibited culture, no considerable aconitase activity and 59 Fe uptake were observed. Time studies with IAA in modified G-medium had shown that whenever it was added it prevented further glycolysis of glucose. Addition of IAA at zero hr had no effect on aconitase activity and 59 Fe uptake whether glucose was present or absent from the medium. IAA added at rising pH at 3 hr. i.e. after transition period had no effect on the pH characteristics and sporulation of the organism. IAA seems to inhibit the induction of metal transport system. There exists a considerable correlation between aconitase activity and 59 Fe uptake during growth and sporulation of B. cereus T in modified G-medium in the presence and absence of glucose. (author)

  2. Temporal Expression of a Master Regulator Drives Synchronous Sporulation in Budding Yeast

    Directory of Open Access Journals (Sweden)

    Minghao Chia

    2016-11-01

    Full Text Available Yeast cells enter and undergo gametogenesis relatively asynchronously, making it technically challenging to perform stage-specific genomic and biochemical analyses. Cell-to-cell variation in the expression of the master regulator of entry into sporulation, IME1, has been implicated to be the underlying cause of asynchronous sporulation. Here, we find that timing of IME1 expression is of critical importance for inducing cells to undergo sporulation synchronously. When we force expression of IME1 from an inducible promoter in cells incubated in sporulation medium for 2 hr, the vast majority of cells exhibit synchrony during premeiotic DNA replication and meiotic divisions. Inducing IME1 expression too early or too late affects the synchrony of sporulation. Surprisingly, our approach for synchronous sporulation does not require growth in acetate-containing medium, but can be achieved in cells grown in rich medium until saturation. Our system requires solely IME1, because the expression of the N6-methyladenosine methyltransferase IME4, another key regulator of early sporulation, is controlled by IME1 itself. The approach described here can be combined easily with other stage-specific synchronization methods, and thereby applied to study specific stages of sporulation, or the complete sporulation program.

  3. Temporal Expression of a Master Regulator Drives Synchronous Sporulation in Budding Yeast.

    Science.gov (United States)

    Chia, Minghao; van Werven, Folkert J

    2016-09-07

    Yeast cells enter and undergo gametogenesis relatively asynchronously, making it technically challenging to perform stage-specific genomic and biochemical analyses. Cell-to-cell variation in the expression of the master regulator of entry into sporulation IME1, has been implicated to be the underlying cause of asynchronous sporulation. Here we find that timing of IME1 expression is of critical importance for inducing cells to undergo sporulation synchronously. When we force expression of IME1 from an inducible promoter in cells incubated in sporulation medium for two hours, the vast majority of cells exhibit synchrony during pre-meiotic DNA replication and meiotic divisions. Inducing IME1 expression too early or too late affects the synchrony of sporulation. Surprisingly, our approach for synchronous sporulation does not require growth in acetate containing medium, but can be achieved in cells grown in rich medium until saturation. Our system solely requires IME1 because the expression of the N6-methyladenosine methyltransferase IME4, another key regulator of early sporulation, is controlled by IME1 itself. The approach described here can be easily combined with other stage specific synchronization methods, and thereby applied to study specific stages of sporulation or the complete sporulation program. Copyright © 2016 Author et al.

  4. Influence of the measurement medium and matrix modifiers on the ...

    African Journals Online (AJOL)

    An electrothermal atomic absorption (ETAAS) method has been developed for the direct determination of Si in natural waters. Measurements were carried out on previously alkalinized samples and using a mixture of Pd and Mg(NO3)2 as matrix modifier, with an ashing temperature of 1400 oC and an atomization ...

  5. Proteomic signatures differentiating Bacillus anthracis Sterne sporulation on soil relative to laboratory media.

    Science.gov (United States)

    Wunschel, D S; Hutchison, J R; Deatherage Kaiser, B L; Merkley, E D; Hess, B M; Lin, A; Warner, M G

    2017-12-18

    The process of sporulation is vital for the stability and infectious cycle of Bacillus anthracis. The spore is the infectious form of the organism and therefore relevant to biodefense. While the morphological and molecular events occurring during sporulation have been well studied, the influence of growth medium and temperature on the proteins expressed in sporulated cultures is not well understood. Understanding the features of B. anthracis sporulation specific to natural vs. laboratory production will address an important question in microbial forensics. In an effort to bridge this knowledge gap, a system for sporulation on two types of agar-immobilized soils was used for comparison to cultures sporulated on two common types of solid laboratory media, and one liquid sporulation medium. The total number of proteins identified as well as their identity differed between samples generated in each medium and growth temperature, demonstrating that sporulation environment significantly impacts the protein content of the spore. In addition, a subset of proteins common in all of the soil-cultivated samples was distinct from the expression profiles in laboratory medium (and vice versa). These differences included proteins involved in thiamine and phosphate metabolism in the sporulated cultures produced on soils with a notable increase in expression of ATP binding cassette (ABC) transporters annotated to be for phosphate and antimicrobial peptides. A distinct set of ABC transporters for amino acids, sugars and oligopeptides were found in cultures produced on laboratory media as well as increases in carbon and amino acid metabolism-related proteins. These protein expression changes indicate that the sporulation environment impacts the protein profiles in specific ways that are reflected in the metabolic and membrane transporter proteins present in sporulated cultures.

  6. Sporulation in the Budding Yeast Saccharomyces cerevisiae

    Science.gov (United States)

    Neiman, Aaron M.

    2011-01-01

    In response to nitrogen starvation in the presence of a poor carbon source, diploid cells of the yeast Saccharomyces cerevisiae undergo meiosis and package the haploid nuclei produced in meiosis into spores. The formation of spores requires an unusual cell division event in which daughter cells are formed within the cytoplasm of the mother cell. This process involves the de novo generation of two different cellular structures: novel membrane compartments within the cell cytoplasm that give rise to the spore plasma membrane and an extensive spore wall that protects the spore from environmental insults. This article summarizes what is known about the molecular mechanisms controlling spore assembly with particular attention to how constitutive cellular functions are modified to create novel behaviors during this developmental process. Key regulatory points on the sporulation pathway are also discussed as well as the possible role of sporulation in the natural ecology of S. cerevisiae. PMID:22084423

  7. Effect of different saccharides on growth, sporulation rate and d ...

    African Journals Online (AJOL)

    MFCS

    2012-05-17

    May 17, 2012 ... general, high sporulation rate was related with high growth rate and high viable cell count (>1.5 x 1012 cfu/ml). .... The sterile culture medium (180 ml) in a 1000 ml Erlenmeyer flask was ... The column temperature was set at 85°C. A series of ..... inactivation of certain sugar-metabolizing operons, such as lac ...

  8. Degradation testing of Mg alloys in Dulbecco's modified eagle medium: Influence of medium sterilization

    Energy Technology Data Exchange (ETDEWEB)

    Marco, Iñigo, E-mail: inigo.marco@mtm.kuleuven.be [Department of Materials Engineering, KU Leuven, Kasteelpark Arenberg, 44, 3001 Leuven (Belgium); Feyerabend, Frank; Willumeit-Römer, Regine [Institute of Materials Research, Division Metallic Biomaterials, Helmholtz-Zentrum Geesthacht, Max-Planck-Str., 1, 21502 Geesthacht (Germany); Van der Biest, Omer [Department of Materials Engineering, KU Leuven, Kasteelpark Arenberg, 44, 3001 Leuven (Belgium)

    2016-05-01

    This work studies the in vitro degradation of Mg alloys for bioabsorbable implant applications under near physiological conditions. For this purpose, the degradation behaviour of Mg alloys in Dulbecco's modified eagle medium (DMEM) which is a commonly used cell culture medium is analysed. Unfortunately, DMEM can be contaminated by microorganisms, acidifying the medium and accelerating the Mg degradation process by dissolution of protective degradation layers, such as (Mg{sub x},Ca{sub y})(PO{sub 4}){sub z}. In this paper the influence of sterilization by applying UV-C radiation and antibiotics (penicillin/streptomycin) is analysed with two implant material candidates: Mg–Gd and Mg–Ag alloys; and pure magnesium as well as Mg–4Y–3RE as a reference. - Highlights: • Contamination of DMEM by microorganisms increases the degradation rate of Mg. • Mg and its alloys show passivation during long term immersion tests in DMEM. • The use of a control sample position is essential to assess H{sub 2} evolution in DMEM.

  9. Growth and sporulation of Bacillus cereus ATCC 14579 under defined conditions: temporal expression of genes for key sigma factors

    NARCIS (Netherlands)

    Vries, de Y.P.; Hornstra, L.M.; Vos, de W.M.; Abee, T.

    2004-01-01

    An airlift fermentor system allowing precise regulation of pH and aeration combined with a chemically defined medium was used to study growth and sporulation of Bacillus cereus ATCC 14579. Sporulation was complete and synchronous. Expression of sigA, sigB, sigF, and sigG was monitored with real-time

  10. Clostridium perfringens Sporulation and Sporulation-Associated Toxin Production

    Science.gov (United States)

    Li, Jihong; Paredes-Sabja, Daniel; Sarker, Mahfuzur R.; McClane, Bruce A.

    2015-01-01

    The ability of Clostridium perfringens to form spores plays a key role during the transmission of this Gram-positive bacterium to cause disease. Of particular note, the spores produced by food poisoning strains are often exceptionally resistant to food environment stresses such as heat, cold and preservatives, which likely facilitates their survival in temperature-abused foods. The exceptional resistance properties of spores made by most type A food poisoning strains and some type C foodborne disease strains involves their production of a variant small acid soluble protein-4 that binds more tightly to spore DNA compared to the small acid soluble protein-4 made by most other C. perfringens strains. Sporulation and germination by C. perfringens and Bacillus spp. share both similarities and differences. Finally, sporulation is essential for production of C. perfringens enterotoxin, which is responsible for the symptoms of C. perfringens type A food poisoning, the second most common bacterial foodborne disease in the USA. During this foodborne disease, C. perfringens is ingested with food and then, using sporulation-specific alternate sigma factors, this bacterium sporulates and produces the enterotoxin in the intestines. PMID:27337447

  11. Energy and calcium ion dependence of proteolysis during sporulation of Bacillus subtilis cells

    International Nuclear Information System (INIS)

    O'Hara, M.B.; Hageman, J.H.

    1990-01-01

    The authors have shown, with an optimized [ 14 C]leucine-labeling and chasing procedure, that intracellular protein degradation in sporulating cells of Bacillus subtilis 168 (trpC2) is apparently energy dependent. Sodium arsenate, sodium azide, carbonyl cyanide m-chlorophenylhydrozone, and N,N'-dicyclohexylcarbodiimide, at levels which did not induce appreciable lysis (≤ 10%) over 10-h periods of sporulation, inhibited intracellular proteolysis by 13 to 93%. Exponentially growing cells acquired arsenate resistance. In contrast to earlier reports, the authors found that chloramphenicol strongly inhibited proteolysis even when added 6 h into the sporulation process. Restricting the calcium ion concentration in the medium had no effect on rates or extent of vegetative growth, strongly inhibited sporulation, and inhibited rates of proteolysis by 60% or more. Inhibitors of energy metabolism, at the same levels which inhibited proteolysis, did not affect the rate or degree of uptake of Ca 2+ by cells. Restricting the Ca 2+ concentration in the medium reduced by threefold of the specific activity in cells of the major intracellular serine proteinase after 12 h of sporulation. finally, cells of a mutant of B. subtilis bearing an insertionally inactivated gene for the Ca 2+ -dependent intracellular proteinase-1 degraded protein in chemically defined sporulation medium at a rate indistinguishable from that of the wild-type cells for period of 8 h

  12. Metallic nanoshells with semiconductor cores: optical characteristics modified by core medium properties.

    Science.gov (United States)

    Bardhan, Rizia; Grady, Nathaniel K; Ali, Tamer; Halas, Naomi J

    2010-10-26

    It is well-known that the geometry of a nanoshell controls the resonance frequencies of its plasmon modes; however, the properties of the core material also strongly influence its optical properties. Here we report the synthesis of Au nanoshells with semiconductor cores of cuprous oxide and examine their optical characteristics. This material system allows us to systematically examine the role of core material on nanoshell optical properties, comparing Cu(2)O core nanoshells (ε(c) ∼ 7) to lower core dielectric constant SiO(2) core nanoshells (ε(c) = 2) and higher dielectric constant mixed valency iron oxide nanoshells (ε(c) = 12). Increasing the core dielectric constant increases nanoparticle absorption efficiency, reduces plasmon line width, and modifies plasmon energies. Modifying the core medium provides an additional means of tailoring both the near- and far-field optical properties in this unique nanoparticle system.

  13. Spatio-Temporal Evolution of Sporulation in Bacillus thuringiensis Biofilm.

    Science.gov (United States)

    El-Khoury, Nay; Majed, Racha; Perchat, Stéphane; Kallassy, Mireille; Lereclus, Didier; Gohar, Michel

    2016-01-01

    Bacillus thuringiensis can produce a floating biofilm which includes two parts: a ring and a pellicle. The ring is a thick structure which sticks to the culture container, while the pellicle extends over the whole liquid surface and joins the ring. We have followed over time, from 16 to 96 h, sporulation in the two biofilm parts. Sporulation was followed in situ in 48-wells polystyrene microtiterplates with a fluorescence binocular stereomicroscope and a spoIID-yfp transcriptional fusion. Sporulation took place much earlier in the ring than in the pellicle. In 20 h-aged biofilms, spoIID was expressed only in the ring, which could be seen as a green fluorescent circle surrounding the non-fluorescent pellicle. However, after 48 h of culture, the pellicle started to express spoIID in specific area corresponding to protrusions, and after 96 h both the ring and the whole pellicle expressed spoIID. Spore counts and microscopy observations of the ring and the pellicle harvested separately confirmed these results and revealed that sporulation occured 24 h-later in the pellicle comparatively to the ring, although both structures contained nearly 100% spores after 96 h of culture. We hypothesize that two mechanisms, due to microenvironments in the biofilm, can explain this difference. First, the ring experiences a decreased concentration of nutrients earlier than the pellicle, because of a lower exchange area with the culture medium. An second, the ring is exposed to partial dryness. Both reasons could speed up sporulation in this biofilm structure. Our results also suggest that spores in the biofilm display a phenotypic heterogeneity. These observations might be of particular significance for the food industry, since the biofilm part sticking to container walls - the ring - is likely to contain spores and will therefore resist both to washing and to cleaning procedures, and will be able to restart a new biofilm when food production has resumed.

  14. Q-PYTHIA: a medium-modified implementation of final state radiation

    Science.gov (United States)

    Armesto, Néstor; Cunqueiro, Leticia; Salgado, Carlos A.

    2009-10-01

    We present a Monte Carlo implementation, within PYTHIA, of medium-induced gluon radiation in the final state branching process. Medium effects are introduced through an additive term in the splitting functions computed in the multiple-soft scattering approximation. The observable effects of this modification are studied for different quantities as fragmentation functions and the hump-backed plateau, and transverse momentum and angular distributions. The anticipated increase of intra-jet multiplicities, energy loss of the leading particle and jet broadening are observed as well as modifications of naive expectations based solely on analytical calculations. This shows the adequacy of a Monte Carlo simulator for jet analyses. Effects of hadronization are found to wash out medium effects in the soft region, while the main features remain. To show the performance of the implementation and the feasibility of our approach in realistic experimental situations we provide some examples: fragmentation functions, nuclear suppression factors, jet shapes and jet multiplicities. The package containing the modified routines is available for public use. This code, which is not an official PYTHIA release, is called Q-PYTHIA. We also include a short manual to perform the simulations of jet quenching.

  15. Molecular determinants of sporulation in Ashbya gossypii.

    Science.gov (United States)

    Wasserstrom, Lisa; Lengeler, Klaus B; Walther, Andrea; Wendland, Jürgen

    2013-09-01

    Regulation of development and entry into sporulation is critical for fungi to ensure survival of unfavorable environmental conditions. Here we present an analysis of gene sets regulating sporulation in the homothallic ascomycete Ashbya gossypii. Deletion of components of the conserved pheromone/starvation MAP kinase cascades, e.g., STE11 and STE7, results in increased sporulation. In kar3 mutants sporulation is severely reduced, while deletion of KAR4 as well as of homologs of central Saccharomyces cerevisiae regulators of sporulation, IME1, IME2, IME4, and NDT80, abolishes sporulation in A. gossypii. Comparison of RNAseq transcript profiles of sporulation-deficient mutants identified a set of 67 down-regulated genes, most of which were up-regulated in the oversporulating ste12 mutant. One of these differentially expressed genes is an endoglucanase encoded by ENG2. We found that Eng2p promotes hyphal fragmentation as part of the developmental program of sporulation, which generates single-celled sporangia. Sporulation-deficient strains are arrested in their development but form sporangia. Supply of new nutrients enabled sporangia to return to hyphal growth, indicating that these cells are not locked in meiosis. Double-strand break (DSB) formation by Spo11 is apparently not required for sporulation; however, the absence of DMC1, which repairs DSBs in S. cerevisiae, results in very poor sporulation in A. gossypii. We present a comprehensive analysis of the gene repertoire governing sporulation in A. gossypii and suggest an altered regulation of IME1 expression compared to S. cerevisiae.

  16. Cell viability and protein turnover in nongrowing Bacillus megaterium at sporulation suppressing temperature.

    Science.gov (United States)

    Kucerová, H; Strnadová, M; Ludvík, J; Chaloupka, J

    1999-01-01

    In Bacillus megaterium, a temperature that suppresses sporulation (43 degrees C) only slightly exceeds both the optimum growth temperature and the temperature still permitting sporulation (40-41 degrees C). Here we show that, when cells grown at 35 degrees C and transferred to a sporulation medium, were subjected to shifts between 35 degrees C and the sporulation suppressing temperature (SST, 43 degrees C), their development and proteolytic activities were deeply affected. During the reversible sporulation phase that took place at 35 degrees C for 2-3 h (T2-T3), the cells developed forespores and their protein turnover was characterized by degradation of short-lived proteins and proteins made accessible to the proteolytic attack because of starvation. During the following irreversible sporulation phase refractile heat-resistant spores appeared at T4-T5. Protein turnover rate increased again after T2 and up to T8 60-70% prelabelled proteins were degraded. The SST suppressed sporulation at its beginning; at T3 no asymmetric septa were observed and the amount of heat-resistant spores at T8 was by 4-5 orders lower than at 35 degrees C. However, the cells remained viable and were able to sporulate when transferred to a lower temperature. Protein degradation was increased up to T3 but then its velocity sharply dropped and the amount of degraded protein at T8 corresponded to slightly more than one-half of that found at 35 degrees C. The cytoplasmic proteolytic activity was enhanced but the activity in the membrane fraction was decreased. When a temperature shift to SST was applied at the beginning of the irreversible sporulation phase (T2.5), the sporulation process was impaired. A portion of forespores lyzed, the others were able to complete their development but most spores were not heat-resistant and their coats showed defects. Protein degradation increased again because an effective proteolytic system was developed during the reversible sporulation phase but the

  17. Sporulation genes associated with sporulation efficiency in natural isolates of yeast.

    Science.gov (United States)

    Tomar, Parul; Bhatia, Aatish; Ramdas, Shweta; Diao, Liyang; Bhanot, Gyan; Sinha, Himanshu

    2013-01-01

    Yeast sporulation efficiency is a quantitative trait and is known to vary among experimental populations and natural isolates. Some studies have uncovered the genetic basis of this variation and have identified the role of sporulation genes (IME1, RME1) and sporulation-associated genes (FKH2, PMS1, RAS2, RSF1, SWS2), as well as non-sporulation pathway genes (MKT1, TAO3) in maintaining this variation. However, these studies have been done mostly in experimental populations. Sporulation is a response to nutrient deprivation. Unlike laboratory strains, natural isolates have likely undergone multiple selections for quick adaptation to varying nutrient conditions. As a result, sporulation efficiency in natural isolates may have different genetic factors contributing to phenotypic variation. Using Saccharomyces cerevisiae strains in the genetically and environmentally diverse SGRP collection, we have identified genetic loci associated with sporulation efficiency variation in a set of sporulation and sporulation-associated genes. Using two independent methods for association mapping and correcting for population structure biases, our analysis identified two linked clusters containing 4 non-synonymous mutations in genes - HOS4, MCK1, SET3, and SPO74. Five regulatory polymorphisms in five genes such as MLS1 and CDC10 were also identified as putative candidates. Our results provide candidate genes contributing to phenotypic variation in the sporulation efficiency of natural isolates of yeast.

  18. Enhanced photocatalytic reduction of Hg(II) in aqueous medium by 2-aminothiazole-modified TiO2 particles

    OpenAIRE

    Cristante,Valtair M.; Araujo,Adriana B.; Jorge,Sônia M. A.; Florentino,Ariovaldo O.; Valente,José P. S.; Padilha,Pedro M.

    2006-01-01

    This work describes the synthesis and characterization of 2-aminothiazole-modified titania and its application on Hg (II) photoreduction in aqueous medium. Infrared spectroscopy confirmed the chemical modification of the titania matrix. The number of 2-aminothiazole groups attached to the titania was determined by Kjeldahl's method. The photocatalytic experiments were carried out in a cylindrical photoreactor thermostatted at 298 K. The resulting modified photocatalyst 2-aminothiazole titania...

  19. Development and Validation of a Liquid Medium (M7H9C) for Routine Culture of Mycobacterium avium subsp. paratuberculosis To Replace Modified Bactec 12B Medium

    Science.gov (United States)

    Whittington, Ann-Michele; Waldron, Anna; Begg, Douglas J.; de Silva, Kumi; Purdie, Auriol C.; Plain, Karren M.

    2013-01-01

    Liquid culture of Mycobacterium avium subsp. paratuberculosis from clinical samples, such as feces, is the most sensitive antemortem test for the diagnosis of Johne's disease in ruminants. In Australia, New Zealand, the United States, and some other countries, the Bactec 460 system with modified Bactec 12B medium (Becton, Dickinson) has been the most commonly used liquid culture system, but it was discontinued in 2012. In this study, a new liquid culture medium, M7H9C, was developed. It consists of a Middlebrook 7H9 medium base with added Casitone, albumin, dextrose, catalase, egg yolk, mycobactin J, and a cocktail of antibiotics. We found that polyoxyethylene stearate (POES) was not essential for the cultivation of M. avium subsp. paratuberculosis in either the Bactec 12B or the M7H9C medium. The limit of detection determined using pure cultures of the C and S strains of M. avium subsp. paratuberculosis was 7 bacilli per 50 μl inoculum in the two media. The new medium was validated using 784 fecal and tissue samples from sheep and cattle, >25% of which contained viable M. avium subsp. paratuberculosis. Discrepant results for the clinical samples between the two media were mostly associated with samples that contained <10 viable bacilli per gram, but these results were relatively uncommon, and the performances of the two media were not significantly different. M7H9C medium was less than half the cost of the Bactec 12B medium and did not require regular examination during incubation, but a confirmatory IS900 PCR test had to be performed on every culture after the predetermined incubation period. PMID:24048541

  20. Efficient wireless power charging of electric vehicle by modifying the magnetic characteristics of the medium

    Science.gov (United States)

    Mahmud, Mohammad Hazzaz

    There is a developing enthusiasm for electric vehicle (EV) innovations as a result of their lessened fuel utilization and greenhouse emission especially through wireless power transfer (WPT) due to the convenience and continuous charging. Numerous research initiatives target on wireless power transfer (WPT) system in the attempt to improve the transportation for last few decades. But several problems like less efficiency, high frequency, long distance energy transfer etc. were always been occupied by the wireless power transfer system. Two ideas have been developed in this research to resolve the two main problems of WPT for electric vehicles which are low efficiency due to large distance between the two coils and slow charging time. As the first phase of study, a proper model, including the coils and cores were required. The selected model was a finite element (FE) modeling. Another part of this study was to create a modified cement that will act as a semi-conductive material for covering the transmitting antenna area. A high frequency wide band gap switch will be used for transferring high amount of power in a very short time. More over this research also proves that, if cores could be added with the transmitter coil and receiver coil then the output efficiency dramatically increased comparing with without core model of transmitter and receiver. The wireless charging is not restricted to parking lot, since it's planned to be embedded into parking space concrete or roadway concrete or asphalt. Therefore, it can also be installed at junctions (behind red lights), stop signs or any spot that the vehicle might stop for several moments. This technology will become more feasible, if the charging time decreases. Therefore, a new model of for wireless power transfer has been proposed in this study which has shown significant improvement. Another motive of this study was to improve the conductivity and permeability in such a way that the medium that is on the top of the

  1. Development of modified flyash as a permeable reactive barrier medium for a former manufactured gas plant site, Northern Ireland

    Science.gov (United States)

    Doherty, R.; Phillips, D. H.; McGeough, K. L.; Walsh, K. P.; Kalin, R. M.

    2006-05-01

    A sequential biological permeable reactive barrier (PRB) was determined to be the best option for remediating groundwater that has become contaminated with a wide range of organic contaminants (i.e., benzene, toluene, ethylbenzene, xylene and polyaromatic hydrocarbons), heavy metals (i.e., lead and arsenic), and cyanide at a former manufactured gas plant after 150 years of operation in Portadown, Northern Ireland. The objective of this study was to develop a modified flyash that could be used in the initial cell within a sequential biological PRB to filter complex contaminated groundwater containing ammonium. Flyash modified with lime (CaOH) and alum was subjected to a series of batch tests which investigated the modified cation exchange capacity (CEC) and rate of removal of anions and cations from the solution. These tests showed that a high flyash composition medium (80%) could remove 8.65 mol of ammonium contaminant for every kilogram of medium. The modified CEC procedure ruled out the possibility of cation exchange as the major removal mechanism. The medium could also adsorb anions as well as cations (i.e., Pb and Cr), but not with the same capacity. The initial mechanism for Pb and Cr removal is probably precipitation. This is followed by sorption, which is possibly the only mechanism for the removal of dichromate anions. Scanning electron microscopic analysis revealed very small (productive zeolite formation. Surface area measurements showed that biofilm growth on the medium could be a major factor in the comparative reduction of surface area between real and synthetic contaminant groundwaters. The modified flyash was found to be a highly sorptive granular material that did not inhibit microbiological activity, however, leaching tests revealed that the medium would fail as a long-term barrier material.

  2. Hydrous iron oxide modified diatomite as an active filtration medium for phosphate capture.

    Science.gov (United States)

    Wang, Zhe; Lin, Yan; Wu, Deyi; Kong, Hainan

    2016-02-01

    A simple method to functionalize diatomite with hydrous iron oxide was attempted and its performance as a new active filtration material to remove and recover phosphate from water was investigated under varying solution conditions. The Langmuir phosphate adsorption capacity increased from 0.6 mgP/g for raw diatomite to 4.89, 14.71, 25.02 mgP/g for hydrous iron oxide modified diatomite (HIOMD), depending on the amount of iron loaded. Loading of hydrous iron oxide caused the increase in true and bulk density and a decline in filtration rate, but to a lesser extent. It was shown that the HIOMD product with suitable iron content could retain a good filtration performance with a greatly increased adsorption capacity for phosphate. The phosphate adsorption increased by decreasing pH and by increasing ionic strength at high pH levels. The adsorption process was interpreted by ligand exchange. Coexisting oxyanions of sulfate, nitrate, citrate, carbonate, silicate and humic acid showed different effects on phosphate fixation but it was presumed that their influence at their concentrations and pH levels commonly encountered in effluent or natural waters was limited, i.e., HIOMD had a reasonably good selectivity. Results in repeated adsorption, desorption and regeneration experiment showed that the adsorbed phosphate could be recovered and the material could be reused after regeneration. The column test showed that HIOMD could be potentially utilized as an adsorption filtration medium for phosphate removal and recovery from water. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. Ultrasensitivity of the Bacillus subtilis sporulation decision.

    Science.gov (United States)

    Narula, Jatin; Devi, Seram N; Fujita, Masaya; Igoshin, Oleg A

    2012-12-11

    Starving Bacillus subtilis cells execute a gene expression program resulting in the formation of stress-resistant spores. Sporulation master regulator, Spo0A, is activated by a phosphorelay and controls the expression of a multitude of genes, including the forespore-specific sigma factor σ(F) and the mother cell-specific sigma factor σ(E). Identification of the system-level mechanism of the sporulation decision is hindered by a lack of direct control over Spo0A activity. This limitation can be overcome by using a synthetic system in which Spo0A activation is controlled by inducing expression of phosphorelay kinase KinA. This induction results in a switch-like increase in the number of sporulating cells at a threshold of KinA. Using a combination of mathematical modeling and single-cell microscopy, we investigate the origin and physiological significance of this ultrasensitive threshold. The results indicate that the phosphorelay is unable to achieve a sufficiently fast and ultrasensitive response via its positive feedback architecture, suggesting that the sporulation decision is made downstream. In contrast, activation of σ(F) in the forespore and of σ(E) in the mother cell compartments occurs via a cascade of coherent feed-forward loops, and thereby can produce fast and ultrasensitive responses as a result of KinA induction. Unlike σ(F) activation, σ(E) activation in the mother cell compartment only occurs above the KinA threshold, resulting in completion of sporulation. Thus, ultrasensitive σ(E) activation explains the KinA threshold for sporulation induction. We therefore infer that under uncertain conditions, cells initiate sporulation but postpone making the sporulation decision to average stochastic fluctuations and to achieve a robust population response.

  4. Sporulation in Bacteria: Beyond the Standard Model.

    Science.gov (United States)

    Hutchison, Elizabeth A; Miller, David A; Angert, Esther R

    2014-10-01

    Endospore formation follows a complex, highly regulated developmental pathway that occurs in a broad range of Firmicutes. Although Bacillus subtilis has served as a powerful model system to study the morphological, biochemical, and genetic determinants of sporulation, fundamental aspects of the program remain mysterious for other genera. For example, it is entirely unknown how most lineages within the Firmicutes regulate entry into sporulation. Additionally, little is known about how the sporulation pathway has evolved novel spore forms and reproductive schemes. Here, we describe endospore and internal offspring development in diverse Firmicutes and outline progress in characterizing these programs. Moreover, comparative genomics studies are identifying highly conserved sporulation genes, and predictions of sporulation potential in new isolates and uncultured bacteria can be made from these data. One surprising outcome of these comparative studies is that core regulatory and some structural aspects of the program appear to be universally conserved. This suggests that a robust and sophisticated developmental framework was already in place in the last common ancestor of all extant Firmicutes that produce internal offspring or endospores. The study of sporulation in model systems beyond B. subtilis will continue to provide key information on the flexibility of the program and provide insights into how changes in this developmental course may confer advantages to cells in diverse environments.

  5. Influence of substrates, light, filter paper and pH on the sporulation of Cercospora sojina

    Directory of Open Access Journals (Sweden)

    Diana Erica Gómez

    2013-06-01

    Full Text Available Fungi require special substrates for their isolation, vegetative growth and sporulation. In experiments conducted in the laboratory, the influence of substrates, light, filter paper and pH on the sporulation of Cercospora sojina conidia, the causal agent of soybean frogeye leaf spot, was assessed. The media potato sucrose agar, V-8 agar, tomato extract agar, soybean leaf extract agar, soybean seed extract agar, soybean meal agar, soybean flour agar and wheat flour agar were tested, added on the surface, with and without filter paper and under two light regimes, with 12 h light at 25°± 2°C and in the dark. A triple factorial 8x2x2 (substrates x light/dark x with/without filter paper design with four replicates was used. V-8 agar medium was employed and the pH was adjusted with HCl 0.1N or NaOH 0.1N before autoclaving to the values: 3, 4, 5, 6, 7 and 8, and the pH of V-8 agar medium is 6.7. The evaluation was done on the seventh day of incubation. Data underwent regression analysis. Sporulation was maximized on the agar media V-8, seed extract, oat flour, tomato extract, and potato sucrose in the presence of filter paper and 12h light. On V-8 medium, maximal sporulation was obtained with pH 6.7.

  6. Pirated Siderophores Promote Sporulation in Bacillus subtilis.

    Science.gov (United States)

    Grandchamp, Gabrielle M; Caro, Lews; Shank, Elizabeth A

    2017-05-15

    In microbial communities, bacteria chemically and physically interact with one another. Some of these interactions are mediated by secreted specialized metabolites that act as either intraspecies or interspecies signals to alter gene expression and to change cell physiology. Bacillus subtilis is a well-characterized soil microbe that can differentiate into multiple cell types, including metabolically dormant endospores. We were interested in identifying microbial interactions that affected sporulation in B. subtilis Using a fluorescent transcriptional reporter, we observed that coculturing B. subtilis with Escherichia coli promoted sporulation gene expression via a secreted metabolite. To identify the active compound, we screened the E. coli Keio Collection and identified the sporulation-accelerating cue as the siderophore enterobactin. B. subtilis has multiple iron acquisition systems that are used to take up the B. subtilis- produced siderophore bacillibactin, as well as to pirate exogenous siderophores such as enterobactin. While B. subtilis uses a single substrate binding protein (FeuA) to take up both bacillibactin and enterobactin, we discovered that it requires two distinct genes to sporulate in response to these siderophores (the esterase gene besA for bacillibactin and a putative esterase gene, ybbA , for enterobactin). In addition, we found that siderophores from a variety of other microbial species also promote sporulation in B. subtilis Our results thus demonstrate that siderophores can act not only as bacterial iron acquisition systems but also as interspecies cues that alter cellular development and accelerate sporulation in B. subtilis IMPORTANCE While much is known about the genetic regulation of Bacillus subtilis sporulation, little is understood about how other bacteria influence this process. This work describes an interaction between Escherichia coli and B. subtilis that accelerates sporulation in B. subtilis The interaction is mediated by the E

  7. Radiation damage and its repair in non-sporulating bacteria

    International Nuclear Information System (INIS)

    Moseley, B.E.B.

    1984-01-01

    A review is given of radiation damage and its repair in non-sporulating bacteria. The identification and measurement of radiation damage in the DNA of the bacteria after exposure to ultraviolet radiation and ionizing radiation is described. Measuring the extent of DNA repair and ways of isolating repair mutants are also described. The DNA repair mechanisms for UV-induced damage are discussed including photoreactivation repair, excision repair, post-replication recombination repair and induced error-prone repair. The DNA repair mechanisms for ionizing radiation damage are also discussed including the repair of both single and double-strand breaks. Other aspects discussed include the effects of growth, irradiation medium and recovery medium on survival, DNA repair in humans, the commercial use of UV and ionizing radiations and the future of ionizing irradiation as a food treatment process. (U.K.)

  8. Catabolite repression of enzyme synthesis does not prevent sporulation.

    OpenAIRE

    Lopez, J M; Uratani-Wong, B; Freese, E

    1980-01-01

    In the presence of excess glucose, a decrease of guanine nucleotides in Bacillus subtilis initiated sporulation but did not prevent catabolite repression of three enzymes. Therefore, the ultimate mechanism(s) repressing enzyme synthesis differs from that suppressing sporulation.

  9. Modified genetic algorithms to model cluster structures in medium-size silicon clusters

    International Nuclear Information System (INIS)

    Bazterra, Victor E.; Ona, Ofelia; Caputo, Maria C.; Ferraro, Marta B.; Fuentealba, Patricio; Facelli, Julio C.

    2004-01-01

    This paper presents the results obtained using a genetic algorithm (GA) to search for stable structures of medium size silicon clusters. In this work the GA uses a semiempirical energy function to find the best cluster structures, which are further optimized using density-functional theory. For small clusters our results agree well with previously reported structures, but for larger ones different structures appear. This is the case of Si 36 where we report a different structure, with significant lower energy than those previously found using limited search approaches on common structural motifs. This demonstrates the need for global optimization schemes when searching for stable structures of medium-size silicon clusters

  10. Medium modified two-body scattering amplitude from proton-nucleus total cross-sections

    Science.gov (United States)

    Tripathi, R. K.; Wilson, J. W.; Cucinotta, F. A.

    2001-01-01

    Recently (R.K. Tripathi, J.W. Wilson, F.A. Cucinotta, Nucl. Instr. and Meth. B 145 (1998) 277; R.K. Tripathi, F.A. Cucinotta, J.W. Wilson, NASA-TP-1998-208438), we have extracted nucleon-nucleon (N-N) cross-sections in the medium directly from experiment. The in-medium N-N cross-sections form the basic ingredients of several heavy-ion scattering approaches including the coupled-channel approach developed at the NASA Langley Research Center. Here, we investigate the ratio of real to imaginary part of the two-body scattering amplitude in the medium. These ratios are used in combination with the in-medium N-N cross-sections to calculate total proton-nucleus cross-sections. The agreement is excellent with the available experimental data. These cross-sections are needed for the radiation risk assessment of space missions. c2001 Elsevier Science B.V. All rights reserved.

  11. Modeling heat resistance of Bacillus weihenstephanensis and Bacillus licheniformis spores as function of sporulation temperature and pH.

    Science.gov (United States)

    Baril, Eugénie; Coroller, Louis; Couvert, Olivier; Leguérinel, Ivan; Postollec, Florence; Boulais, Christophe; Carlin, Frédéric; Mafart, Pierre

    2012-05-01

    Although sporulation environmental factors are known to impact on Bacillus spore heat resistance, they are not integrated into predictive models used to calculate the efficiency of heating processes. This work reports the influence of temperature and pH encountered during sporulation on heat resistance of Bacillus weihenstephanensis KBAB4 and Bacillus licheniformis AD978 spores. A decrease in heat resistance (δ) was observed for spores produced either at low temperature, at high temperature or at acidic pH. Sporulation temperature and pH maximizing the spore heat resistance were identified. Heat sensitivity (z) was not modified whatever the sporulation environmental factors were. A resistance secondary model inspired by the Rosso model was proposed. Sporulation temperatures and pHs minimizing or maximizing the spore heat resistance (T(min(R)), T(opt(R)), T(max(R)), pH(min(R)) and pH(opt(R))) were estimated. The goodness of the model fit was assessed for both studied strains and literature data. The estimation of the sporulation temperature and pH maximizing the spore heat resistance is of great interest to produce spores assessing the spore inactivation in the heating processes applied by the food industry. Copyright © 2011 Elsevier Ltd. All rights reserved.

  12. Influence of culture media and environmental factors on mycelial growth and sporulation of Lasiodiplodia theobromae (Pat.) Griffon and Maubl.

    Science.gov (United States)

    Saha, A; Mandal, P; Dasgupta, S; Saha, D

    2008-05-01

    Lasiodiplodia theobromae, a common tea (Camellia sinensis) pathogen, usually does not sporulate or sporulates poorly in common media, which makes spore production difficult. In this study the effects of culture media, carbon source, nitrogen source, temperature, pH and light on mycelial growth and sporulation were evaluated. Among several carbon sources tested, glucose and sucrose were found superior for growth. Potassium nitrate supplemented media showed maximum growth amongst the tested inorganic nitrogen sources while peptone produced maximum growth among the tested organic nitrogen sources. Tea root extract supplemented potato dextrose agar medium was found to be the most suitable for mycelial growth and sporulation of L. theobromae. The fungus grow at temperatures ranging from 40 to 36 degrees C, with optimum growth at 28 degrees C and no growth was noted at 40 degrees C. There was no significant effect of different light period on growth of L. theobromae, but light enhanced sporulation. The fungus grow at pH 3.0-8.0 and optimum growth was observed at pH 6.0. Tea root extract supplemented potato dextrose agar medium with pH 6.0 was the most suitable for production of conidia of L. theobromae at 28 degrees C. Hence this media may be recommended for inoculum production for further studies.

  13. Modified sulphur cement: A low porosity encapsulation material for low, medium and alpha waste

    International Nuclear Information System (INIS)

    Dalen, A. van; Rijpkema, J.E.

    1989-01-01

    Modified sulphur cement, available under the trade name Chement 2000, is a thermoplastic candidate material for the matrix of low, intermediate and alpha radioactive waste. The main source of sulphur is the desulphurization of fossil fuels. In view of the future increase of this product a modified compound of sulphur has been developed at the US Bureau of Mines. Modified sulphur cement as matrix material has properties in common with Portland or blast furnace cement and bitumen. The mechanical strength is comparable to hydraulic cement products. The process to incorporate waste materials is identical to bitumization. The leachability and the resistance to attack by chemicals is nearly the same as for bituminized products. This study showed also that the radiation resistance is high without radiolytic gas production and without change in dimensions (swelling). The rigidity of the matrix is a disadvantage when internal pressures are built up. The thermal conductivity and the heat of combustion of sulphur is low resulting in slow damage to the waste form under fire conditions, even when the temperature of self ignition in air is 220 0 C. The low leachability, the very slow effective diffusion of H 2 O and HTO, and the low permeability is due to the small pore diameters in the modified sulphur matrix. The loading capacity of modified sulphur cement depends on grain size and distribution and is for ungraded ashes, precipitates, dried sludges, etc., in the order of 40-50% of weight. The price of Chement 2000 per tonne is equal to those of blown bitumen

  14. Electrochemical Reduction of Oxygen on Anthraquinone/Carbon Nanotubes Nanohybrid Modified Glassy Carbon Electrode in Neutral Medium

    Directory of Open Access Journals (Sweden)

    Zheng Gong

    2013-01-01

    Full Text Available The electrochemical behaviors of monohydroxy-anthraquinone/multiwall carbon nanotubes (MHAQ/MWCNTs nanohybrid modified glassy carbon (MHAQ/MWCNTs/GC electrodes in neutral medium were investigated; also reported was their application in the electrocatalysis of oxygen reduction reaction (ORR. The resulting MHAQ/MWCNTs nanohybrid was characterized by scanning electron microscope (SEM and transmission electron microscope (TEM. It was found that the ORR at the MHAQ/MWCNTs/GC electrode occurs irreversibly at a potential about 214 mV less negative than at a bare GC electrode in pH 7.0 buffer solution. Cyclic voltammetric and rotating disk electrode (RDE techniques indicated that the MHAQ/MWCNTs nanohybrid has high electrocatalytic activity for the two-electron reduction of oxygen in the studied potential range. The kinetic parameters of ORR at the MHAQ/MWCNTs nanohybrid modified GC electrode were also determined by RDE and EIS techniques.

  15. Regulation of cellulase expression, sporulation, and morphogenesis by velvet family proteins in Trichoderma reesei.

    Science.gov (United States)

    Liu, Kuimei; Dong, Yanmei; Wang, Fangzhong; Jiang, Baojie; Wang, Mingyu; Fang, Xu

    2016-01-01

    Homologs of the velvet protein family are encoded by the ve1, vel2, and vel3 genes in Trichoderma reesei. To test their regulatory functions, the velvet protein-coding genes were disrupted, generating Δve1, Δvel2, and Δvel3 strains. The phenotypic features of these strains were examined to identify their functions in morphogenesis, sporulation, and cellulase expression. The three velvet-deficient strains produced more hyphal branches, indicating that velvet family proteins participate in the morphogenesis in T. reesei. Deletion of ve1 and vel3 did not affect biomass accumulation, while deletion of vel2 led to a significantly hampered growth when cellulose was used as the sole carbon source in the medium. The deletion of either ve1 or vel2 led to the sharp decrease of sporulation as well as a global downregulation of cellulase-coding genes. In contrast, although the expression of cellulase-coding genes of the ∆vel3 strain was downregulated in the dark, their expression in light condition was unaffected. Sporulation was hampered in the ∆vel3 strain. These results suggest that Ve1 and Vel2 play major roles, whereas Vel3 plays a minor role in sporulation, morphogenesis, and cellulase expression.

  16. Investigation of Electrochemical Behaviour of Quercetin on the Modified Electrode Surfaces with Procaine and Aminophenyl in Non-Aquous Medium

    Directory of Open Access Journals (Sweden)

    Ibrahim Ender Mulazimoglu

    2008-01-01

    Full Text Available In this study, cyclic voltammetry and electrochemical ımpedance spectroscopy have been used to investigate the electrochemical behaviour of quercetin (3,3′,4′,5,7-pentahydroxyflavone on the procaine and aminophenyl modified electrode. The modification of procaine and aminophenyl binded electrode surface with quercetin was performed in +0,3/+2,8 V (for procaine and +0,4/+1,5 V (for aminophenyl potential range using 100 mV s-1 scanning rate having 10 cycle. A solution of 0.1 M tetrabutylammonium tetrafluoroborate in acetonitrile was used as a non-aquous solvent. For the modification process a solution of 1 mM quercetin in 0.1 M tetrabutylammonium tetrafluoroborate was used. In order to obtain these two surface, a solution of 1 mM procaine and 1 mM nitrophenyl diazonium salt in 0.1 M tetrabutylammonium tetrafluoroborate was used. By using these solutions bare glassy carbon electrode surface was modified. Nitrophenyl was reduced to amine group in 0.1 M HCl medium on the nitrophenyl modified glassy carbon elelctrode surface. Procaine modified glassy carbon electrode surface was quite electroactive. Although nitrophenyl modified glassy carbon elelctrode surface was electroinactive, it was activated by reducing nitro group into amine group. For the characterization of the modified surface 1 mM ferrocene in 0.1 M tetrabutylammonium tetrafluoroborate for cyclic voltammetry and 1 mM ferricyanide/ferrocyanide (1:1 mixture in 0,1 M KCl for electrochemical impedance spectroscopy were used.

  17. Enhanced Bioavailability of Curcumin Nanoemulsions Stabilized with Phosphatidylcholine Modified with Medium Chain Fatty Acids.

    Science.gov (United States)

    Ochoa-Flores, Angélica A; Hernández-Becerra, Josafat A; Cavazos-Garduño, Adriana; Soto-Rodríguez, Ida; Sanchez-Otero, Maria Guadalupe; Vernon-Carter, Eduardo J; García, Hugo S

    2017-01-01

    Curcumin is a natural, oil-soluble polyphenolic compound with potent anticancer, anti-inflammatory, and antioxidant activities. In its free form, it is very poorly absorbed in the gut due to its very low solubility. The use of nanoemulsions as carrier is a feasible way for improving curcumin bioavailability. To this end, the choice of emulsifying agent for stabilizing the nanoemulsions is of the upmost importance for achieving a desired functionality. Phosphatidylcholine (PC) and phosphatidycholine enriched (PCE) with medium chain fatty acids (42.5 mol %) in combination with glycerol as co-surfactant, were used for preparing oil-in water nanoemulsions coded as NEPC and NEPCE, respectively. NEPCE displayed significantly smaller mean droplet size (30 nm), equal entrapment efficiency (100%), better droplet stability and suffered lower encapsulation efficiency loss (3%) during storage time (120 days, 4ºC) than NEPC. Bioavailability, measured in terms of area under the curve of curcumin concentration versus time, and maximum curcumin plasma concentration, was in general terms significantly higher for NEPCE than for NEPC, and for curcumin coarse aqueous suspension (CCS). Also, NEPCE produced significantly higher curcumin concentrations in liver and lung than NEPC and CCS. These data support the role of phosphatidylcholine enriched with medium chain fatty acids to increase the bioavailability of nanoemulsions for therapeutic applications. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  18. Giant halos in medium nuclei within modified relativistic mean field (MRMF) model

    Energy Technology Data Exchange (ETDEWEB)

    Nugraha, A. M., E-mail: alpi.mahisha@gmail.com; Sulaksono, A. [Departemen Fisika, FMIPA, Universitas Indonesia, Kampus UI Depok (Indonesia); Sumaryada, T. [Department of Physics, Bogor Agricultural University, Jalan Meranti Kampus IPB Dramaga Bogor 16680 (Indonesia)

    2016-04-19

    The large number of neutrons in a region beyond a closed shell core indicates the presence of giant halos in nuclei. In this work, by using the Rotival method within a modified relativistic mean field (MRMF) model, we predict theoretically the formation of giant halos in Cr and Zr isotopes. The MRMF model is a modification of standard RMF model augmented with isoscalar and isovector tensor terms, isovector-isoscalar vector cross coupling term and electromagnetic exchange term for Coulomb interaction in local density approximation (LDA).

  19. CodY-Dependent Regulation of Sporulation in Clostridium difficile.

    Science.gov (United States)

    Nawrocki, Kathryn L; Edwards, Adrianne N; Daou, Nadine; Bouillaut, Laurent; McBride, Shonna M

    2016-08-01

    Clostridium difficile must form a spore to survive outside the gastrointestinal tract. The factors that trigger sporulation in C. difficile remain poorly understood. Previous studies have suggested that a link exists between nutritional status and sporulation initiation in C. difficile In this study, we investigated the impact of the global nutritional regulator CodY on sporulation in C. difficile strains from the historical 012 ribotype and the current epidemic 027 ribotype. Sporulation frequencies were increased in both backgrounds, demonstrating that CodY represses sporulation in C. difficile The 027 codY mutant exhibited a greater increase in spore formation than the 012 codY mutant. To determine the role of CodY in the observed sporulation phenotypes, we examined several factors that are known to influence sporulation in C. difficile Using transcriptional reporter fusions and quantitative reverse transcription-PCR (qRT-PCR) analysis, we found that two loci associated with the initiation of sporulation, opp and sinR, are regulated by CodY. The data demonstrate that CodY is a repressor of sporulation in C. difficile and that the impact of CodY on sporulation and expression of specific genes is significantly influenced by the strain background. These results suggest that the variability of CodY-dependent regulation is an important contributor to virulence and sporulation in current epidemic isolates. This report provides further evidence that nutritional state, virulence, and sporulation are linked in C. difficile This study sought to examine the relationship between nutrition and sporulation in C. difficile by examining the global nutritional regulator CodY. CodY is a known virulence and nutritional regulator of C. difficile, but its role in sporulation was unknown. Here, we demonstrate that CodY is a negative regulator of sporulation in two different ribotypes of C. difficile We also demonstrate that CodY regulates known effectors of sporulation, Opp and Sin

  20. [Viability of nematophagous fungi Arthrobotrys robusta, Duddingtonia flagrans and Monacrosporium thaumasium after sporulation in different culture media].

    Science.gov (United States)

    Maciel, Alessandro S; de Araujo, Jackson V; Campos, Artur K

    2006-01-01

    Due to the shortage of studies that indicate the culture mediums that optimize the sporulation of namatophagous fungi for use in researche, the sporulation of the fungal isolates A. robusta (I31), D. flagrans (CG768) and M. thaumasium (NF34A) was evaluated in laboratorial conditions for 10 days in the means water-agar 2% (WA 2%), potato-dextrose-agar 2% (PDA 2%), corn-meal-agar 2% (CMA 2%) and yeast-phosphate-sulphate-sucrose-agar (YPSSA). The largest conidia production (P BDA 2% while in the isolates I31 and NF34A produced larger conidia number in YPSSA (P 0.05).

  1. Conserved oligopeptide permeases modulate sporulation initiation in Clostridium difficile.

    Science.gov (United States)

    Edwards, Adrianne N; Nawrocki, Kathryn L; McBride, Shonna M

    2014-10-01

    The anaerobic gastrointestinal pathogen Clostridium difficile must form a metabolically dormant spore to survive in oxygenic environments and be transmitted from host to host. The regulatory factors by which C. difficile initiates and controls the early stages of sporulation in C. difficile are not highly conserved in other Clostridium or Bacillus species. Here, we investigated the role of two conserved oligopeptide permeases, Opp and App, in the regulation of sporulation in C. difficile. These permeases are known to positively affect sporulation in Bacillus species through the import of sporulation-specific quorum-sensing peptides. In contrast to other spore-forming bacteria, we discovered that inactivating these permeases in C. difficile resulted in the earlier expression of early sporulation genes and increased sporulation in vitro. Furthermore, disruption of opp and app resulted in greater virulence and increased the amounts of spores recovered from feces in the hamster model of C. difficile infection. Our data suggest that Opp and App indirectly inhibit sporulation, likely through the activities of the transcriptional regulator SinR and its inhibitor, SinI. Taken together, these results indicate that the Opp and App transporters serve a different function in controlling sporulation and virulence in C. difficile than in Bacillus subtilis and suggest that nutrient availability plays a significant role in pathogenesis and sporulation in vivo. This study suggests a link between the nutritional status of the environment and sporulation initiation in C. difficile. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

  2. Modified chemically defined medium for enhanced respiratory growth of Lactobacillus casei and Lactobacillus plantarum groups.

    Science.gov (United States)

    Ricciardi, A; Ianniello, R G; Parente, E; Zotta, T

    2015-09-01

    Members of the Lactobacillus casei and Lactobacillus plantarum groups are capable of aerobic and respiratory growth. However, they grow poorly in aerobiosis in the currently available chemically defined media, suggesting that aerobic and respiratory growth require further supplementation. The effect of Tween 80, L-alanine, L-asparagine, L-aspartate, L-proline and L-serine on anaerobic and respiratory growth of Lact. casei N87 was investigated using a 2(5) factorial design. The effectiveness of modified CDM (mCDM) was validated on 21 strains of Lact. casei and Lact. plantarum groups. Tween 80 supplementation did not affect anaerobic growth, but improved respiratory growth. L-asparagine, L-proline and L-serine were stimulatory for respiring cells, while the presence of L-aspartate, generally, impaired biomass production. mCDM promoted the growth of Lact. casei and Lact. plantarum, with best results for strains showing a respiratory phenotype. The nutritional requirements of anaerobic and respiratory cultures of members of the Lact. casei and Lact. plantarum groups differ. Tween 80 and selected amino acids derived from pathways related to TCA cycle, pyruvate conversion and NADH recycling are required for respiration. The availability of mCDM will facilitate the study of aerobic metabolism of lactobacilli under controlled conditions. © 2015 The Society for Applied Microbiology.

  3. Sporulation dynamics of poultry Eimeria oocysts in Chennai.

    Science.gov (United States)

    Venkateswara Rao, P; Raman, M; Gomathinayagam, S

    2015-12-01

    The infective form of Eimeria is the highly resistant oocyst, which is shed in the faeces of infected animals. Present study was carried out to understand the sporulation dynamics of six Eimeria oocysts viz. E. acervulina, E. brunetti, E. maxima, E. mitis, E. necatrix and E. tenella in Chennai. Faecal samples of poultry were collected from various poultry farms located in and around Tamil Nadu. Oocysts of various Eimeria species were examined microscopically for sporulation on a 6 h interval basis till complete sporulation is acheived. The sporulation time recorded was 168, 120, 216, 192, 96 and 96 h for E. acervulina, E. brunetti, E. maxima, E. mitis, E. necatrix and E. tenella respectively. It can be concluded on comparison with previous studies that humid weather conditions delay the sporulation time and dry weather and wet litter is the ideal condition for rapid sporulation.

  4. Chancroid in Sheffield. A report of 22 cases diagnosed by isolating Haemophilus ducreyi in a modified medium.

    Science.gov (United States)

    Hafiz, S; Kinghorn, G R; McEntegart, M G

    1981-01-01

    The causative organism of chancroid, Haemophilus ducreyi, is generally considered to be very fastidious and its isolation, maintenance, and detailed study very demanding. In this study a modified medium was developed, which allowed the organism to be isolated more frequently than previously would have been expected. Twenty-two cases of chancroid were confirmed by the isolation of H ducreyi in 160 patients with genital ulceration examined over a one-year period. The cases were apparently unrelated, and in only five was there a history of recent sexual contact abroad. Concurrent infection with other sexually transmitted diseases was present in 18 (81.8%) patients, and in 14 (63.6%) both H ducreyi and herpes simplex virus were isolated form the same genital ulcers. Thus, these findings indicate that chancroid is underdiagnosed in England and that H ducreyi may frequently occur as a secondary invader of damaged genital skin and mucosa. PMID:6976815

  5. Measurement of cellular copper levels in Bacillus megaterium during exponential growth and sporulation.

    Science.gov (United States)

    Krueger, W B; Kolodziej, B J

    1976-01-01

    Both atomic absorption spectrophotometry (AAS) and neutron activation analysis have been utilized to determine cellular Cu levels in Bacillus megaterium ATCC 19213. Both methods were selected for their sensitivity to detection of nanogram quantities of Cu. Data from both methods demonstrated identical patterms of Cu uptake during exponenetial growth and sporulation. Late exponential phase cells contained less Cu than postexponential t2 cells while t5 cells contained amounts equivalent to exponential cells. The t11 phase-bright forespore containing cells had a higher Cu content than those of earlier time periods, and the free spores had the highest Cu content. Analysis of the culture medium by AAS corroborated these data by showing concomitant Cu uptake during exponential growth and into t2 postexponential phase of sporulation. From t2 to t4, Cu egressed from the cells followed by a secondary uptake during the maturation of phase-dark forespores into phase-bright forespores (t6--t9).

  6. High Electrocatalytic Performance of CuCoNi@CNTs Modified Glassy Carbon Electrode towards Methanol Oxidation in Alkaline Medium

    Directory of Open Access Journals (Sweden)

    Amina A. Hamza

    2017-01-01

    Full Text Available A novel non-precious multiwalled carbon nanotubes (CNTs—supported metal oxide electrocatalyst was developed for methanol electrooxidation in alkaline medium. The catalyst was fabricated by simultaneous electrodeposition of copper-cobalt-nickel ternary nanostructures (CuCoNi on a glassy carbon electrode (GCE modified with CNTs. The proposed electrode was characterized using X-ray diffraction (XRD, energy dispersive X-ray (EDX, and scanning electron microscopy (SEM. The electrochemical behavior and the electrocatalytic performance of the suggested electrode towards the oxidation of methanol were evaluated by cyclic voltammetry (CV, linear sweep voltammetry (LSV, and chronoamperometry (CA in alkaline medium. Several parameters were investigated, e.g., deposition time, potential scan rate, etc. Compared to Cu, Co, or Ni mono electrocatalysts, the electrode based on ternary-metals exhibited superior electrocatalytic activity and stability towards methanol electrooxidation. For instance, CuCoNi@CNTs/GCE has shown at least 2.5 times electrocatalytic activity and stability compared to the mono eletrocatalysts. Moreover, the present study found that the optimized loading level is 1500 s of simultaneous electrodeposition. At this loading level, it was found that the relation between the Ip/ν1/2 function and scan rate gives the characteristic features of a catalytic process. The enhanced activity and stability of CuCoNi@CNTs/GCE was attributed to (i a synergism between three metal oxides coexisting in the same structure; (ii the presence of CNTs as a support for the metal oxides, that offers high surface area for the deposited tertiary alloy and suppresses the aggregation and sintering of the metals oxide with time; as well as (iii the increase of the conductivity of the deposited semiconducting metal oxides.

  7. Efficient Sporulation of Saccharomyces cerevisiae in a 96 Multiwell Format.

    Science.gov (United States)

    Paulissen, Scott M; Huang, Linda S

    2016-09-17

    During times of nutritional stress, Saccharomyces cerevisiae undergoes gametogenesis, known as sporulation. Diploid yeast cells that are starved for nitrogen and carbon will initiate the sporulation process. The process of sporulation includes meiosis followed by spore formation, where the haploid nuclei are packaged into environmentally resistant spores. We have developed methods for the efficient sporulation of budding yeast in 96 multiwell plates, to increase the throughput of screening yeast cells for sporulation phenotypes. These methods are compatible with screening with yeast containing plasmids requiring nutritional selection, when appropriate minimal media is used, or with screening yeast with genomic alterations, when a rich presporulation regimen is used. We find that for this method, aeration during sporulation is critical for spore formation, and have devised techniques to ensure sufficient aeration that are compatible with the 96 multiwell plate format. Although these methods do not achieve the typical ~80% level of sporulation that can be achieved in large-volume flask based experiments, these methods will reliably achieve about 50-60% level of sporulation in small-volume multiwell plates.

  8. Sporulation during growth in a gut isolate of Bacillus subtilis.

    Science.gov (United States)

    Serra, Cláudia R; Earl, Ashlee M; Barbosa, Teresa M; Kolter, Roberto; Henriques, Adriano O

    2014-12-01

    Sporulation by Bacillus subtilis is a cell density-dependent response to nutrient deprivation. Central to the decision of entering sporulation is a phosphorelay, through which sensor kinases promote phosphorylation of Spo0A. The phosphorelay integrates both positive and negative signals, ensuring that sporulation, a time- and energy-consuming process that may bring an ecological cost, is only triggered should other adaptations fail. Here we report that a gastrointestinal isolate of B. subtilis sporulates with high efficiency during growth, bypassing the cell density, nutritional, and other signals that normally make sporulation a post-exponential-phase response. Sporulation during growth occurs because Spo0A is more active per cell and in a higher fraction of the population than in a laboratory strain. This in turn, is primarily caused by the absence from the gut strain of the genes rapE and rapK, coding for two aspartyl phosphatases that negatively modulate the flow of phosphoryl groups to Spo0A. We show, in line with recent results, that activation of Spo0A through the phosphorelay is the limiting step for sporulation initiation in the gut strain. Our results further suggest that the phosphorelay is tuned to favor sporulation during growth in gastrointestinal B. subtilis isolates, presumably as a form of survival and/or propagation in the gut environment. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

  9. One pot synthesis of Ag nanoparticle modified ZnO microspheres in ethylene glycol medium and their enhanced photocatalytic performance

    International Nuclear Information System (INIS)

    Tian Chungui; Li Wei; Pan Kai; Zhang Qi; Tian Guohui; Zhou Wei; Fu Honggang

    2010-01-01

    Ag nanoparticles (NPs) modified ZnO microspheres (Ag/ZnO microspheres) were prepared by a facile one pot strategy in ethylene glycol (EG) medium. The EG played two important roles in the synthesis: it could act as a reaction media for the formation of ZnO and reduce Ag + to Ag 0 . A series of the characterizations indicated the successful combination of Ag NPs with ZnO microspheres. It was shown that Ag modification could greatly enhance the photocatalytic efficiency of ZnO microspheres by taking the photodegradation of Rhodamine B as a model reaction. With appropriate ratio of Ag and ZnO, Ag/ZnO microspheres showed the better photocatalytic performance than commercial Degussa P-25 TiO 2 . Photoluminescence and surface photovoltage spectra demonstrated that Ag modification could effectively inhibit the recombination of the photoinduced electron and holes of ZnO. This is responsible for the higher photocatalytic activity of Ag/ZnO composites. -- Graphical abstract: A 'one-pot' strategy was developed for preparing the Ag/ZnO microspheres in ethylene glycol. The composites exhibited superior photocatalytic performance for photodegradation of Rhodamine B dye in water. Display Omitted

  10. Genomic determinants of sporulation in Bacilli and Clostridia: towards the minimal set of sporulation-specific genes.

    Science.gov (United States)

    Galperin, Michael Y; Mekhedov, Sergei L; Puigbo, Pere; Smirnov, Sergey; Wolf, Yuri I; Rigden, Daniel J

    2012-11-01

    Three classes of low-G+C Gram-positive bacteria (Firmicutes), Bacilli, Clostridia and Negativicutes, include numerous members that are capable of producing heat-resistant endospores. Spore-forming firmicutes include many environmentally important organisms, such as insect pathogens and cellulose-degrading industrial strains, as well as human pathogens responsible for such diseases as anthrax, botulism, gas gangrene and tetanus. In the best-studied model organism Bacillus subtilis, sporulation involves over 500 genes, many of which are conserved among other bacilli and clostridia. This work aimed to define the genomic requirements for sporulation through an analysis of the presence of sporulation genes in various firmicutes, including those with smaller genomes than B. subtilis. Cultivable spore-formers were found to have genomes larger than 2300 kb and encompass over 2150 protein-coding genes of which 60 are orthologues of genes that are apparently essential for sporulation in B. subtilis. Clostridial spore-formers lack, among others, spoIIB, sda, spoVID and safA genes and have non-orthologous displacements of spoIIQ and spoIVFA, suggesting substantial differences between bacilli and clostridia in the engulfment and spore coat formation steps. Many B. subtilis sporulation genes, particularly those encoding small acid-soluble spore proteins and spore coat proteins, were found only in the family Bacillaceae, or even in a subset of Bacillus spp. Phylogenetic profiles of sporulation genes, compiled in this work, confirm the presence of a common sporulation gene core, but also illuminate the diversity of the sporulation processes within various lineages. These profiles should help further experimental studies of uncharacterized widespread sporulation genes, which would ultimately allow delineation of the minimal set(s) of sporulation-specific genes in Bacilli and Clostridia. Published 2012. This article is a U.S. Government work and is in the public domain in the USA.

  11. The routine use of modified Borelli's lactritmel agar (MBLA).

    Science.gov (United States)

    Kaminski, G W

    1985-07-01

    The original formula of Borelli's lactritmel agar (BLA)(3) which contains wheat flour, milk and honey, has been modified by replacing the wheat flour with dehydrated Bacto Corn Meal Agar (Difco) and by slightly altering the concentrations of the milk and honey. The modified medium (MBLA) is less turbid, less particulate, and easier to prepare than BLA. Although Trichophyton rubrum usually produces a wine-red pigment with BLA, most strains initially produce a yellow pigment, with the red pigment developing later. The corn meal in MBLA reduces this tendency and stimulates the early formation of deep wine red pigment, MBLA enhances sporulation of dermatophytes and various fungi which fail to sporulate on other media, and maintains characteristic growth without developing pleomorphic degeneration. It has been used routinely since 1972 as a reliable aid to the differentiation of T. rubrum and T. mentagrophytes. Since 1975 selective MBLA has been used as a routine primary isolation medium for dermatophytes, and has proved to be most useful.

  12. A Modified Constitutive Model for Tensile Flow Behaviors of BR1500HS Ultra-High-Strength Steel at Medium and Low Temperature Regions

    Science.gov (United States)

    Zhao, Jun; Quan, Guo-Zheng; Pan, Jia; Wang, Xuan; Wu, Dong-Sen; Xia, Yu-Feng

    2018-01-01

    Constitutive model of materials is one of the most requisite mathematical model in the finite element analysis, which describes the relationships of flow behaviors with strain, strain rate and temperature. In order to construct such constitutive relationships of ultra-high-strength BR1500HS steel at medium and low temperature regions, the true stress-strain data over a wide temperature range of 293-873 K and strain rate range of 0.01-10 s-1 were collected from a series of isothermal uniaxial tensile tests. The experimental results show that stress-strain relationships are highly non-linear and susceptible to three parameters involving temperature, strain and strain rate. By considering the impacts of strain rate and temperature on strain hardening, a modified constitutive model based on Johnson-Cook model was proposed to characterize flow behaviors in medium and low temperature ranges. The predictability of the improved model was also evaluated by the relative error (W(%)), correlation coefficient (R) and average absolute relative error (AARE). The R-value and AARE-value for modified constitutive model at medium and low temperature regions are 0.9915 & 1.56 % and 0.9570 & 5.39 %, respectively, which indicates that the modified constitutive model can precisely estimate the flow behaviors for BR1500HS steel in the medium and low temperature regions.

  13. The Clostridium sporulation programs: diversity and preservation of endospore differentiation.

    Science.gov (United States)

    Al-Hinai, Mohab A; Jones, Shawn W; Papoutsakis, Eleftherios T

    2015-03-01

    Bacillus and Clostridium organisms initiate the sporulation process when unfavorable conditions are detected. The sporulation process is a carefully orchestrated cascade of events at both the transcriptional and posttranslational levels involving a multitude of sigma factors, transcription factors, proteases, and phosphatases. Like Bacillus genomes, sequenced Clostridium genomes contain genes for all major sporulation-specific transcription and sigma factors (spo0A, sigH, sigF, sigE, sigG, and sigK) that orchestrate the sporulation program. However, recent studies have shown that there are substantial differences in the sporulation programs between the two genera as well as among different Clostridium species. First, in the absence of a Bacillus-like phosphorelay system, activation of Spo0A in Clostridium organisms is carried out by a number of orphan histidine kinases. Second, downstream of Spo0A, the transcriptional and posttranslational regulation of the canonical set of four sporulation-specific sigma factors (σ(F), σ(E), σ(G), and σ(K)) display different patterns, not only compared to Bacillus but also among Clostridium organisms. Finally, recent studies demonstrated that σ(K), the last sigma factor to be activated according to the Bacillus subtilis model, is involved in the very early stages of sporulation in Clostridium acetobutylicum, C. perfringens, and C. botulinum as well as in the very late stages of spore maturation in C. acetobutylicum. Despite profound differences in initiation, propagation, and orchestration of expression of spore morphogenetic components, these findings demonstrate not only the robustness of the endospore sporulation program but also the plasticity of the program to generate different complex phenotypes, some apparently regulated at the epigenetic level. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  14. Updates on the sporulation process in Clostridium species.

    Science.gov (United States)

    Talukdar, Prabhat K; Olguín-Araneda, Valeria; Alnoman, Maryam; Paredes-Sabja, Daniel; Sarker, Mahfuzur R

    2015-05-01

    Sporulation is an important strategy for certain bacterial species within the phylum Firmicutes to survive longer periods of time in adverse conditions. All spore-forming bacteria have two phases in their life; the vegetative form, where they can maintain all metabolic activities and replicate to increase numbers, and the spore form, where no metabolic activities exist. Although many essential components of sporulation are conserved among the spore-forming bacteria, there are differences in the regulation and the pathways among different genera, even at the species level. While we have gained much information from the most studied spore-forming bacterial genus, Bacillus, we still lack an in-depth understanding of spore formation in the genus Clostridium. Clostridium and Bacillus share the master regulator of sporulation, Spo0A, and its downstream pathways, but there are differences in the activation of the Spo0A pathway. While Bacillus species use a multi-component phosphorylation pathway for phosphorylation of Spo0A, termed phosphorelay, such a phosphorelay system is absent in Clostridium. On the other hand, a number of genes regulated by the different sporulation-specific transcription factors are conserved between different Clostridium and Bacillus species. In this review, we discuss the recent findings on Clostridium sporulation and compare the sporulation mechanism in Clostridium and Bacillus. Copyright © 2014 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

  15. Sensor kinase KinB and its pathway-associated key factors sense the signal of nutrition starvation in sporulation of Bacillus subtilis.

    Science.gov (United States)

    Liu, Weipeng; He, Zeying; Gao, Feng; Yan, Jinyuan; Huang, Xiaowei

    2018-01-03

    Bacillus subtilis responds to environmental stress cues and develops endospores for survival. In the process of endospore formation, sporulation initiation is a vital stage and this stage is governed by autophosphorylation of the sensor histidine kinases. The second major sensor kinase KinB perceives the intracellular changes of GTP and ATP during sporulation. However, determination of the environmental signals as well as its related signaling pathway of KinB requires further elucidation. Our current study found that, contrary to the sporulation failure induced by ΔkinA in the nutrient-rich 2× SG medium, the sensor kinase KinB sensed the environmental cues in the nutrient-poor MM medium. Two other membrane proteins, KapB and KbaA, also responded similarly to the same external signal as KinB. Both KapB and KbaA acted upstream of KinB, but they exerted their regulation upon KinB independently. Furthermore, we demonstrated that both the SH3 domain and the α-helix structure in KapB are required for sensing or transducing the signal of sporulation initiation. Collectively, our work here supplied the direct evidences that KinB and its pathway sense the external signal of nutrient starvation in MM medium, and further analyzes the interrelationship among KinB, KbaA, and KapB. © 2018 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

  16. Increased dipicolinic acid production with an enhanced spoVF operon in Bacillus subtilis and medium optimization.

    Science.gov (United States)

    Takahashi, Fumikazu; Sumitomo, Nobuyuki; Hagihara, Hiroshi; Ozaki, Katsuya

    2015-01-01

    Dipicolinic acid (DPA) is a multi-functional agent for cosmetics, antimicrobial products, detergents, and functional polymers. The aim of this study was to design a new method for producing DPA from renewable material. The Bacillus subtilis spoVF operon encodes enzymes for DPA synthase and the part of lysine biosynthetic pathway. However, DPA is only synthesized in the sporulation phase, so the productivity of DPA is low level. Here, we report that DPA synthase was expressed in vegetative cells, and DPA was produced in the culture medium by replacement of the spoVFA promoter with other highly expressed promoter in B. subtilis vegetative cells, such as spoVG promoter. DPA levels were increased in the culture medium of genetically modified strains. DPA productivity was significantly improved up to 29.14 g/L in 72 h culture by improving the medium composition using a two-step optimization technique with the Taguchi methodology.

  17. Δ(1-pyrroline-5-carboxylate/glutamate biogenesis is required for fungal virulence and sporulation.

    Directory of Open Access Journals (Sweden)

    Ziting Yao

    Full Text Available Proline dehydrogenase (Prodh and Δ(1-pyrroline-5-carboxylate dehydrogenase (P5Cdh are two key enzymes in the cellular biogenesis of glutamate. Recombinant Prodh and P5Cdh proteins of the chestnut blight fungus Cryphonectria parasitica were investigated and showed activity in in vitro assays. Additionally, the C. parasitica Prodh and P5Cdh genes were able to complement the Saccharomyces cerevisiae put1 and put2 null mutants, respectively, to allow these proline auxotrophic yeast mutants to grow on media with proline as the sole source of nitrogen. Deletion of the Prodh gene in C. parasitica resulted in hypovirulence and a lower level of sporulation, whereas deletion of P5Cdh resulted in hypovirulence though no effect on sporulation; both Δprodh and Δp5cdh mutants were unable to grow on minimal medium with proline as the sole nitrogen source. In a wild-type strain, the intracellular level of proline and the activity of Prodh and P5Cdh increased after supplementation of exogenous proline, though the intracellular Δ(1-pyrroline-5-carboxylate (P5C content remained unchanged. Prodh and P5Cdh were both transcriptionally down-regulated in cells infected with hypovirus. The disruption of other genes with products involved in the conversion of arginine to ornithine, ornithine and glutamate to P5C, and P5C to proline in the cytosol did not appear to affect virulence; however, asexual sporulation was reduced in the Δpro1 and Δpro2 mutants. Taken together, our results showed that Prodh, P5Cdh and related mitochondrial functions are essential for virulence and that proline/glutamate pathway components may represent down-stream targets of hypovirus regulation in C. parasitica.

  18. Chromosomal Arrangement of Phosphorelay Genes Couples Sporulation and DNA Replication.

    Science.gov (United States)

    Narula, Jatin; Kuchina, Anna; Lee, Dong-Yeon D; Fujita, Masaya; Süel, Gürol M; Igoshin, Oleg A

    2015-07-16

    Genes encoding proteins in a common regulatory network are frequently located close to one another on the chromosome to facilitate co-regulation or couple gene expression to growth rate. Contrasting with these observations, here, we demonstrate a functional role for the arrangement of Bacillus subtilis sporulation network genes on opposite sides of the chromosome. We show that the arrangement of two sporulation network genes, one located close to the origin and the other close to the terminus, leads to a transient gene dosage imbalance during chromosome replication. This imbalance is detected by the sporulation network to produce cell-cycle coordinated pulses of the sporulation master regulator Spo0A∼P. This pulsed response allows cells to decide between sporulation and continued vegetative growth during each cell cycle spent in starvation. The simplicity of this coordination mechanism suggests that it may be widely applicable in a variety of gene regulatory and stress-response settings. VIDEO ABSTRACT. Copyright © 2015 Elsevier Inc. All rights reserved.

  19. Modified geometrical optics of a smoothly inhomogeneous isotropic medium: The anisotropy, Berry phase, and the optical Magnus effect

    International Nuclear Information System (INIS)

    Bliokh, K.Yu.; Bliokh, Yu.P.

    2004-01-01

    We present a modification of the geometrical optics method, which allows one to properly separate the complex amplitude and the phase of the wave solution. Applying this modification to a smoothly inhomogeneous isotropic medium, we show that in the first geometrical optics approximation the medium is weakly anisotropic. The refractive index, being dependent on the direction of the wave vector, contains the correction, which is proportional to the Berry geometric phase. Two independent eigenmodes of right-hand and left-hand circular polarizations exist in the medium. Their group velocities and phase velocities differ. The difference in the group velocities results in the shift of the rays of different polarizations (the optical Magnus effect). The difference in the phase velocities causes an increase of the Berry phase along with the interference of two modes leading to the familiar Rytov law about the rotation of the polarization plane of a wave. The theory developed suggests that both the optical Magnus effect and the Berry phase are accompanying nonlocal topological effects. In this paper the Hamilton ray equations giving a unified description for both of these phenomena have been derived and also a novel splitting effect for a ray of noncircular polarization has been predicted. Specific examples are also discussed

  20. Modified geometrical optics of a smoothly inhomogeneous isotropic medium: the anisotropy, Berry phase, and the optical Magnus effect.

    Science.gov (United States)

    Bliokh, K Yu; Bliokh, Yu P

    2004-08-01

    We present a modification of the geometrical optics method, which allows one to properly separate the complex amplitude and the phase of the wave solution. Appling this modification to a smoothly inhomogeneous isotropic medium, we show that in the first geometrical optics approximation the medium is weakly anisotropic. The refractive index, being dependent on the direction of the wave vector, contains the correction, which is proportional to the Berry geometric phase. Two independent eigenmodes of right-hand and left-hand circular polarizations exist in the medium. Their group velocities and phase velocities differ. The difference in the group velocities results in the shift of the rays of different polarizations (the optical Magnus effect). The difference in the phase velocities causes an increase of the Berry phase along with the interference of two modes leading to the familiar Rytov law about the rotation of the polarization plane of a wave. The theory developed suggests that both the optical Magnus effect and the Berry phase are accompanying nonlocal topological effects. In this paper the Hamilton ray equations giving a unified description for both of these phenomena have been derived and also a novel splitting effect for a ray of noncircular polarization has been predicted. Specific examples are also discussed.

  1. Proteins that interact with GTP during sporulation of Bacillus subtilis

    International Nuclear Information System (INIS)

    Mitchell, C.; Vary, J.C.

    1989-01-01

    During sporulation of Bacillus subtilis, several proteins were shown to interact with GTP in specific ways. UV light was used to cross-link [α- 32 P]GTP to proteins in cell extracts at different stages of growth. After electrophoresis, 11 bands of radioactivity were found in vegetative cells, 4 more appeared during sporulation, and only 9 remained in mature spores. Based on the labeling pattern with or without UV light to cross-link either [α- 32 P]GTP or [γ- 32 P]GTP, 11 bands of radioactivity were apparent guanine nucleotide-binding proteins, and 5 bands appeared to be phosphorylated and/or guanylated. Similar results were found with Bacillus megaterium. Assuming the GTP might be a type of signal for sporulation, it could interact with and regulate proteins by at least three mechanisms

  2. Optimized Carrier Based Multilevel Generated Modified Dual Three-Phase Open-Winding Inverter for Medium Power Applications

    DEFF Research Database (Denmark)

    Padmanaban, Sanjeevi Kumar; Blaabjerg, Frede; Wheeler, Patrick

    2016-01-01

    This paper presents a novel carrier based multilevel modulation for modified dual three-phase open-winding inverter applicable for low-voltage/high-current applications. A standard three-phase voltage source inverter (VSI) is connected across the open-winding of both ends of the motor. Each VSI i...

  3. Effects of Artemisia annua extracts on sporulation of Eimeria oocysts.

    Science.gov (United States)

    Fatemi, Ahmadreza; Razavi, Seyyed Mostafa; Asasi, Keramat; Goudarzi, Majid Torabi

    2015-03-01

    The present study aimed to compare the effect of different Artemisia annua extracts on sporulation rate of mixed oocysts of Eimeria acervulina, Eimeria necatrix, and Eimeria tenella. Three types of A. annua extracts including petroleum ether (PE), ethanol 96° (E), and water (W) extracts were prepared. Artemisinin, a sesquiterpene lactone endoperoxide derived from the A. annua analysis of each extract was done by high-performance liquid chromatography with ultraviolet detection (HPLC-UV). Fresh fecal samples containing three Eimeria species were floated and counted, and the oocysts were transferred into 50 tubes, each containing 10(5) oocysts per milliliter. Five tubes were control. Each of the other 45 tubes contained one of three doses (1 part per thousand (ppt), 2 ppt, and 5 ppt) and one of three extracts (PE, E, and W extracts) with five replications. The tubes were incubated for 48 h at 25-29 °C and aerated. Sporulation inhibition assay was used to evaluate the activity of extracts. The results showed that the E and PE extracts inhibit sporulation in 2 and 5 ppt concentrations, but the W extract stimulates it in all concentrations. The proportions of oocyst inhibition relative to control were 31 % (5 ppt) and 29 % (2 ppt) for PE and 34 % (5 ppt) and 46 % (2 ppt) for E extract. Furthermore, many oocysts in PE and E groups were wrinkled and contained abnormal sporocysts. The proportions of sporulation stimulation relative to control were 22 % (5 ppt), 24 % (2 ppt), and 27 % (1 ppt) in W extract. Our study is the first to demonstrate that all types of A. annua extracts do not necessarily have a similar activity, and the interaction of all contents and their relative concentrations is an important factor for sporulation stimulation or inhibition. It seems, some parts of unmetabolized excreted PE and E extracts could inhibit oocyst sporulation and eventually affect infection transmission.

  4. Global analysis of the sporulation pathway of Clostridium difficile.

    Science.gov (United States)

    Fimlaid, Kelly A; Bond, Jeffrey P; Schutz, Kristin C; Putnam, Emily E; Leung, Jacqueline M; Lawley, Trevor D; Shen, Aimee

    2013-01-01

    The Gram-positive, spore-forming pathogen Clostridium difficile is the leading definable cause of healthcare-associated diarrhea worldwide. C. difficile infections are difficult to treat because of their frequent recurrence, which can cause life-threatening complications such as pseudomembranous colitis. The spores of C. difficile are responsible for these high rates of recurrence, since they are the major transmissive form of the organism and resistant to antibiotics and many disinfectants. Despite the importance of spores to the pathogenesis of C. difficile, little is known about their composition or formation. Based on studies in Bacillus subtilis and other Clostridium spp., the sigma factors σ(F), σ(E), σ(G), and σ(K) are predicted to control the transcription of genes required for sporulation, although their specific functions vary depending on the organism. In order to determine the roles of σ(F), σ(E), σ(G), and σ(K) in regulating C. difficile sporulation, we generated loss-of-function mutations in genes encoding these sporulation sigma factors and performed RNA-Sequencing to identify specific sigma factor-dependent genes. This analysis identified 224 genes whose expression was collectively activated by sporulation sigma factors: 183 were σ(F)-dependent, 169 were σ(E)-dependent, 34 were σ(G)-dependent, and 31 were σ(K)-dependent. In contrast with B. subtilis, C. difficile σ(E) was dispensable for σ(G) activation, σ(G) was dispensable for σ(K) activation, and σ(F) was required for post-translationally activating σ(G). Collectively, these results provide the first genome-wide transcriptional analysis of genes induced by specific sporulation sigma factors in the Clostridia and highlight that diverse mechanisms regulate sporulation sigma factor activity in the Firmicutes.

  5. How Quorum Sensing Connects Sporulation to Necrotrophism in Bacillus thuringiensis.

    Science.gov (United States)

    Perchat, Stéphane; Talagas, Antoine; Poncet, Sandrine; Lazar, Noureddine; Li de la Sierra-Gallay, Inès; Gohar, Michel; Lereclus, Didier; Nessler, Sylvie

    2016-08-01

    Bacteria use quorum sensing to coordinate adaptation properties, cell fate or commitment to sporulation. The infectious cycle of Bacillus thuringiensis in the insect host is a powerful model to investigate the role of quorum sensing in natural conditions. It is tuned by communication systems regulators belonging to the RNPP family and directly regulated by re-internalized signaling peptides. One such RNPP regulator, NprR, acts in the presence of its cognate signaling peptide NprX as a transcription factor, regulating a set of genes involved in the survival of these bacteria in the insect cadaver. Here, we demonstrate that, in the absence of NprX and independently of its transcriptional activator function, NprR negatively controls sporulation. NprR inhibits expression of Spo0A-regulated genes by preventing the KinA-dependent phosphorylation of the phosphotransferase Spo0F, thus delaying initiation of the sporulation process. This NprR function displays striking similarities with the Rap proteins, which also belong to the RNPP family, but are devoid of DNA-binding domain and indirectly control gene expression via protein-protein interactions in Bacilli. Conservation of the Rap residues directly interacting with Spo0F further suggests a common inhibition of the sporulation phosphorelay. The crystal structure of apo NprR confirms that NprR displays a highly flexible Rap-like structure. We propose a molecular regulatory mechanism in which key residues of the bifunctional regulator NprR are directly and alternatively involved in its two functions. NprX binding switches NprR from a dimeric inhibitor of sporulation to a tetrameric transcriptional activator involved in the necrotrophic lifestyle of B. thuringiensis. NprR thus tightly coordinates sporulation and necrotrophism, ensuring survival and dissemination of the bacteria during host infection.

  6. Effects of selected herbicides and fungicides on growth, sporulation and conidial germination of entomopathogenic fungus Beauveria bassiana.

    Science.gov (United States)

    Celar, Franci A; Kos, Katarina

    2016-11-01

    The in vitro fungicidal effects of six commonly used fungicides, namely fluazinam, propineb, copper(II) hydroxide, metiram, chlorothalonil and mancozeb, and herbicides, namely isoxaflutole, fluazifop-P-butyl, flurochloridone, foramsulfuron, pendimethalin and prosulfocarb, on mycelial growth, sporulation and conidial germination of entomopathogenic fungus Beauveria bassiana (ATCC 74040) were investigated. Mycelial growth rates and sporulation at 15 and 25 °C were evaluated on PDA plates containing 100, 75, 50, 25, 12.5, 6.25 and 0% of the recommended application rate of each pesticide. The tested pesticides were classified in four scoring categories based on reduction in mycelial growth and sporulation. All pesticides, herbicides and fungicides tested had fungistatic effects of varying intensity, depending on their rate in the medium, on B. bassiana. The most inhibitory herbicides were flurochloridone and prosulfocarb, and fluazinam and copper(II) hydroxide were most inhibitory among the fungicides, while the least inhibitory were isoxaflutole and chlorothalonil. Sporulation and conidial germination of B. bassiana were significantly inhibited by all tested pesticides compared with the control treatment. Flurochloridone, foramsulfuron, prosulfocarb and copper(II) hydroxide inhibited sporulation entirely at 100% rate (99-100% inhibition), and the lowest inhibition was shown by fluazifop-P-butyl (22%) and metiram (33%). At 100% dosage, all herbicides in the test showed a high inhibitory effect on conidial germination. Conidial germination inhibition ranged from 82% with isoxaflutole to 100% with fluorochloridone, pendimethalin and prosulfocarb. At 200% dosage, inhibition rates even increased (96-100%). All 12 pesticides tested had a fungistatic effect on B. bassiana of varying intensity, depending on the pesticide and its concentration. B. bassiana is highly affected by some herbicides and fungicides even at very low rates. Flurochloridone, foramsulfuron

  7. Asexual sporulation signalling regulates autolysis of Aspergillus nidulans via modulating the chitinase ChiB production.

    Science.gov (United States)

    Pócsi, I; Leiter, E; Kwon, N-J; Shin, K-S; Kwon, G-S; Pusztahelyi, T; Emri, T; Abuknesha, R A; Price, R G; Yu, J-H

    2009-08-01

    Elucidation of the regulation of ChiB production in Aspergillus nidulans. Mutational inactivation of the A. nidulans chiB gene resulted in a nonautolytic phenotype. To better understand the mechanisms controlling both developmental progression and fungal autolysis, we examined a range of autolysis-associated parameters in A. nidulans developmental and/or autolytic mutants. Investigation of disorganization of mycelial pellets, loss of biomass, extra-/intracellular chitinase activities, ChiB production and chiB mRNA levels in various cultures revealed that, in submerged cultures, initialization of autolysis and stationary phase-induced ChiB production are intimately coupled, and that both processes are controlled by the FluG-BrlA asexual sporulation regulatory pathway. ChiB production does not affect the progression of apoptotic cell death in the aging A. nidulans cultures. The endochitinase ChiB plays an important role in autolysis of A. nidulans, and its production is initiated by FluG-BrlA signalling. Despite the fact that apoptosis is an inseparable part of fungal autolysis, its regulation is independent to FluG-initiated sporulation signalling. Deletion of chiB and fluG homologues in industrial filamentous fungal strains may stabilize the hyphal structures in the autolytic phase of growth and limit the release of autolytic hydrolases into the culture medium.

  8. Mechanical strengths of modified PET mortar composites in aggressive MgSO4 medium: ACI & B.S predictions

    OpenAIRE

    Kazi Tani N; Benosman A.S.; Senhadji Y.; Taïbi H.; Mouli M.

    2018-01-01

    Composites mortars based on plastic aggregates are often considered as an innovative materials of the future because of their potential and the advantages they present. In this paper, a comparative study was carried out on the effect of magnesium sulfate MgSO4 (5%) attack on the durability of composite mortars modified by recycled polyethylene terephthalate (PET). Laboratory tests were accomplished on limestone sand and cement mortars where the blended Portland cement was partially replaced b...

  9. A sensor for acetaminophen in a blood medium using a Cu(II)-conducting polymer complex modified electrode

    International Nuclear Information System (INIS)

    Boopathi, Mannan; Won, Mi-Sook; Shim, Yoon-Bo

    2004-01-01

    Complexation of Cu ions in a terthiophene carboxylic acid (TTCA) polymer film resulted an enhanced anodic current for acetaminophen oxidation when compared to polymer coated and bare glassy carbon electrodes in human blood and buffer media. Scanning electron microscopy (SEM) and ESCA experiments indicate the involvement of copper in the electrocatalytic oxidation of acetaminophen. No interference was observed from other biologically important and phenolic compounds used with this modified electrode. Especially, the non-interference from N-acetylcysteine, an antidote for the treatment of acetaminophen poisoning, reveals the proposed method's superiority in medicinal applications. In addition, the present modified electrode avoids surface fouling at higher concentrations of acetaminophen. The calibration range obtained with CV was based between 2.0x10 -5 and 5.0x10 -3 M [r 2 =0.997 (n=5, R.S.D.=2.5%); DL=5.0x10 -6 M (S/N=3)]. The analytical utility of the modified electrode was achieved by analyzing the content of acetaminophen in different drugs without pretreatment using CV and amperometric techniques

  10. Determination of Uranium in Aqueous and Organic Medium From Product and Waste Processes by Potentiometric Titration Using Modified Davies Gray Method

    International Nuclear Information System (INIS)

    Putro, K.P; Suripto, A

    1998-01-01

    Determination of uranium in aqueous and organic solution generated from nuclear fuels production and liquid radioactive waste at Fuel Element Production Installation for Research Reactor, by modified Davies-Gray method using phosphoric acid as medium and vanadium as catalyst has been carried out. The performed at different concentration of phosphoric acid, vanadium and the effect of impurities, as Al, Fe, Si, Cl and F in sample are measurement. Determination of uranium in organic solvent are the sample volume, agitation time and the optimum concentration of uranium to measurement. It was observed that, the optimum conditions for uranium analysis were : 5 -400 mg uranium in 3.2 M phosphoric acid medium containing 220 mg/l vanadium as catalyst. The impurities of Al ≤ 40.5 μg/ml, Fe ≤ 67.6 μg/ml, Si ≤ 20.3 μg/ml, Cl ≤ 135.1 μg/ml and F 13.5 μg/ml have not effect, but the concentration of F ≥ 40.5 μg/ml have effect in analysis result. The uranium content detectable in organic medium has been found between 0.01 to 0.10 g/l and the reproducibility range between 0.09 to 0.15 as well as the sample volume should be in the range of 5 and 10 ml by the agitation time for 4 minute

  11. Analysis of Bacillus subtilis sporulation with spore-converting bacteriophage PMB12.

    OpenAIRE

    Kinney, D M; Bramucci, M G

    1981-01-01

    Previous observations concerning the ability of the spore-converting bacteriophage PMB12 to cause sporulation in certain sporulation-deficient mutants of Bacillus subtilis 168 were extended to include a spoOK mutant and a mutant temperature sensitive for sporulation due to a ribosomal mutation. Mutants of PMB12 that were unable to induce sporulation in the spoOK mutant were isolated to determine whether PMB12-encoded products had to affect the sporulation-specific functions of both the transc...

  12. Factors Affecting Onset of Sporulation in Phytophthora ramorum

    Science.gov (United States)

    To elucidate the sporulation potential of the sudden oak death pathogen, Phytophthora ramorum, on rhododendron, we conducted a series of experiments looking at the relationship between moisture period, lesion size, and onset of sporangia production. Inoculations were performed using P. ramorum isol...

  13. Control of sporulation-specific cell division in Streptomyces coelicolor

    NARCIS (Netherlands)

    Noens, Elke

    2007-01-01

    During developmental cell division in sporulation-committed aerial hyphae of streptomycetes, up to a hundred septa are simultaneously produced, in close harmony with synchromous chromosome condensation and segregation. Several unique protein families are involved in the control of this process,

  14. Selectivity in protein degradation during sporulation of Bacillus subtilis

    International Nuclear Information System (INIS)

    Mitani, Takahiko; Kadota, Hajime

    1976-01-01

    The breakdown of cellular protein was investigated in Bacillus subtilis ATCC 6051 labeled with glycine-2- 3 H or L-phenylalanine-U- 14 C at the different stages of vegetative growth and sporulation. The growth of the culture was determined by measuring optical density at 660 nm. The heat-resistant spores were scored by plating after heating at 80 deg C for 10 minutes. A question whether the turnover of glycine-labeled protein is similar to that of phenylalanine-labeled protein was experimentally studied. The patterns obtained with the glycine-labeled protein were different from those of phenylalanine-labeled protein. This was not multiple turnover. The cellular protein which was labeled with glycine at an early stage of sporulation showed rapid degradation, but the degradation of the protein labeled with glycine at later stages did not occur at all. Another question whether the labeled glycine incorporated into cells at the different stages of growth and sporulation was present in the spore coat fraction of matured spores was studied. Experiment demonstrated that the glycine incorporated into cells at the late sporulation stage was mainly utilized for the biosynthesis of the spore coat protein. These data suggest that the spore coat protein which contains relatively large amount of glycine is rarely subject to further degradation. (Iwakiri, K.)

  15. SUB1 Plays a Negative Role during Starvation Induced Sporulation Program in Saccharomyces cerevisiae.

    Science.gov (United States)

    Gupta, Ritu; Sadhale, Parag P; Vijayraghavan, Usha

    2015-01-01

    Saccharomyces cerevisiae Sub1 is involved in several cellular processes such as, transcription initiation, elongation, mRNA processing and DNA repair. It has also been reported to provide cellular resistance during conditions of oxidative DNA damage and osmotic stress. Here, we report a novel role of SUB1 during starvation stress-induced sporulation, which leads to meiosis and spore formation in diploid yeast cells. Deletion of SUB1 gene significantly increased sporulation efficiency as compared to the wild-type cells in S288c genetic background. Whereas, the sporulation functions of the sub1(Y66A) missense mutant were similar to Sub1. SUB1 transcript and protein levels are downregulated during sporulation, in highly synchronized and sporulation proficient wild-type SK1 cells. The changes in Sub1 levels during sporulation cascade correlate with the induction of middle sporulation gene expression. Deletion of SUB1 increased middle sporulation gene transcript levels with no effect on their induction kinetics. In wild-type cells, Sub1 associates with chromatin at these loci in a temporal pattern that correlates with their enhanced gene expression seen in sub1Δ cells. We show that SUB1 genetically interacts with HOS2, which led us to speculate that Sub1 might function with Set3 repressor complex during sporulation. Positive Cofactor 4, human homolog of Sub1, complemented the sub1Δ sporulation phenotype, suggesting conservation of function. Taken together, our results suggest that SUB1 acts as a negative regulator of sporulation.

  16. The influence of serum substituents on serum-free Vero cell conditioned culture media manufactured from Dulbecco's modified Eagle medium in mouse embryo culture.

    Science.gov (United States)

    Lee, Jong-Seon; Kim, Ju-Hwan; Seo, Young-Seok; Yang, Jung-Bo; Kim, Yong-Il; Kim, Hye-Jin; Lee, Ki-Hwan

    2013-09-01

    This study was conducted to examine the influences of supplementation of the serum substituents and available period of serum-free Vero cell conditioned media (SF-VCM) manufactured from Dulbecco's modified Eagle medium cultured with Vero cells for in vitro development of mouse preimplantation embryos. A total of 1,099 two-cell embryos collected from imprinting control region mice were cultured in SF-VCM with 10% and 20% human follicular fluid (hFF), serum substitute supplement (SSS), and serum protein substitute (SPS). Development of embryos was observed every 24 hours. Results between different groups were analyzed by chi-square test, and considered statistically significant when P-value was less than 0.05. The rates of embryonic development cultured in SF-VCM supplemented with serum substituents were significantly higher compare with serum-free group (P media up to 4 weeks did not affect on embryonic development.

  17. Hybrid molecularly imprinted poly(methacrylic acid-TRIM)-silica chemically modified with (3-glycidyloxypropyl)trimethoxysilane for the extraction of folic acid in aqueous medium

    Energy Technology Data Exchange (ETDEWEB)

    Midori de Oliveira, Fernanda; Gava Segatelli, Mariana [Departamento de Química, Universidade Estadual de Londrina, Rod. Celso Garcia Cid, PR 445 Km 380, Campus Universitário, Londrina, PR CEP 86051-990 (Brazil); Tarley, César Ricardo Teixeira, E-mail: ctarleyquim@yahoo.com.br [Departamento de Química, Universidade Estadual de Londrina, Rod. Celso Garcia Cid, PR 445 Km 380, Campus Universitário, Londrina, PR CEP 86051-990 (Brazil); Instituto Nacional de Ciência e Tecnologia (INCT) de Bioanalítica, Universidade Estadual de Campinas (UNICAMP), Instituto de Química, Departamento de Química Analítica, Cidade Universitária Zeferino Vaz s/n, CEP 13083-970 Campinas, SP (Brazil)

    2016-02-01

    In the present study a hybrid molecularly imprinted poly(methacrylic acid-trimethylolpropane trimethacrylate)-silica (MIP) was synthesized and modified with (3-glycidyloxypropyl)trimethoxysilane (GPTMS) with posterior opening of epoxy ring to provide hydrophilic properties of material in the extraction of folic acid from aqueous medium. The chemical and structural aggregates of hybrid material were characterized by means of Fourier Transform Infrared (FT-IR), Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Thermogravimetric analysis (TGA) and textural data. Selectivity data of MIP were compared to non-imprinted polymer (NIP) through competitive sorption studies in the presence of caffeine, paracetamol or 4-aminobenzamide yielding relative selectivity coefficients (k′) higher than one unit, thus confirming the selective character of MIP even in the presence of structurally smaller compounds than the folic acid. The lower hydrophobic sorption by bovine serum albumin (BSA) in the MIP as compared to unmodified MIP proves the hydrophilicity of polymer surface by using GPTMS with opening ring. Under acid medium (pH 1.5) the sorption of folic acid onto MIP from batch experiments was higher than the one achieved for NIP. Equilibrium sorption of folic acid was reached at 120 min for MIP, NIP and MIP without GPTMS and kinetic sorption data were well described by pseudo-second-order, Elovich and intraparticle diffusion models. Thus, these results indicate the existence of different binding energy sites in the polymers and a complex mechanism consisting of both surface sorption and intraparticle transport of folic acid within the pores of polymers. - Highlights: • The molecularly imprinted hybrid polymer showed high adsorption capacity for folic acid. • The molecularly imprinted hybrid polymer showed high selectivity for folic acid. • The molecularly imprinted hybrid polymer modified with GPTMS excludes higher amount of BSA.

  18. Inducible Expression of spo0A as a Universal Tool for Studying Sporulation in Clostridium difficile.

    Science.gov (United States)

    Dembek, Marcin; Willing, Stephanie E; Hong, Huynh A; Hosseini, Siamand; Salgado, Paula S; Cutting, Simon M

    2017-01-01

    Clostridium difficile remains a leading nosocomial pathogen, putting considerable strain on the healthcare system. The ability to form endospores, highly resistant to environmental insults, is key to its persistence and transmission. However, important differences exist between the sporulation pathways of C. difficile and the model Gram-positive organism Bacillus subtilis . Amongst the challenges in studying sporulation in C. difficile is the relatively poor levels of sporulation and high heterogeneity in the sporulation process. To overcome these limitations we placed P tet regulatory elements upstream of the master regulator of sporulation, spo0A , generating a new strain that can be artificially induced to sporulate by addition of anhydrotetracycline (ATc). We demonstrate that this strain is asporogenous in the absence of ATc, and that ATc can be used to drive faster and more efficient sporulation. Induction of Spo0A is titratable and this can be used in the study of the spo0A regulon both in vitro and in vivo , as demonstrated using a mouse model of C. difficile infection (CDI). Insights into differences between the sporulation pathways in B. subtilis and C. difficile gained by study of the inducible strain are discussed, further highlighting the universal interest of this tool. The P tet -spo0A strain provides a useful background in which to generate mutations in genes involved in sporulation, therefore providing an exciting new tool to unravel key aspects of sporulation in C. difficile.

  19. Inducible Expression of spo0A as a Universal Tool for Studying Sporulation in Clostridium difficile

    Directory of Open Access Journals (Sweden)

    Marcin Dembek

    2017-09-01

    Full Text Available Clostridium difficile remains a leading nosocomial pathogen, putting considerable strain on the healthcare system. The ability to form endospores, highly resistant to environmental insults, is key to its persistence and transmission. However, important differences exist between the sporulation pathways of C. difficile and the model Gram-positive organism Bacillus subtilis. Amongst the challenges in studying sporulation in C. difficile is the relatively poor levels of sporulation and high heterogeneity in the sporulation process. To overcome these limitations we placed Ptet regulatory elements upstream of the master regulator of sporulation, spo0A, generating a new strain that can be artificially induced to sporulate by addition of anhydrotetracycline (ATc. We demonstrate that this strain is asporogenous in the absence of ATc, and that ATc can be used to drive faster and more efficient sporulation. Induction of Spo0A is titratable and this can be used in the study of the spo0A regulon both in vitro and in vivo, as demonstrated using a mouse model of C. difficile infection (CDI. Insights into differences between the sporulation pathways in B. subtilis and C. difficile gained by study of the inducible strain are discussed, further highlighting the universal interest of this tool. The Ptet-spo0A strain provides a useful background in which to generate mutations in genes involved in sporulation, therefore providing an exciting new tool to unravel key aspects of sporulation in C. difficile.

  20. Genome-Wide Transcriptional Profiling of Clostridium perfringens SM101 during Sporulation Extends the Core of Putative Sporulation Genes and Genes Determining Spore Properties and Germination Characteristics

    NARCIS (Netherlands)

    Xiao, Y.; Hijum, S.A.F.T. van; Abee, T.; Wells-Bennik, M.H.

    2015-01-01

    The formation of bacterial spores is a highly regulated process and the ultimate properties of the spores are determined during sporulation and subsequent maturation. A wide variety of genes that are expressed during sporulation determine spore properties such as resistance to heat and other adverse

  1. Genome-wide transcriptional profiling of Clostridium perfringens SM101 during sporulation extends the core of putative sporulation genes and genes determining spore properties and germination characteristics

    NARCIS (Netherlands)

    Xiao, Y.; Hijum, van S.A.F.T.; Abee, T.; Wells-Bennik, M.H.J.

    2015-01-01

    The formation of bacterial spores is a highly regulated process and the ultimate properties of the spores are determined during sporulation and subsequent maturation. A wide variety of genes that are expressed during sporulation determine spore properties such as resistance to heat and other adverse

  2. Biocidal action of ozone-treated polystyrene surfaces on vegetative and sporulated bacteria

    International Nuclear Information System (INIS)

    Mahfoudh, Ahlem; Barbeau, Jean; Moisan, Michel; Leduc, Annie; Seguin, Jacynthe

    2010-01-01

    Surfaces of materials can be modified to ensure specific interaction features with microorganisms. The current work discloses biocidal properties of polystyrene (PS) Petri-dish surfaces that have been exposed to a dry gaseous-ozone flow. Such treated PS surfaces are able to inactivate various species of vegetative and sporulated bacteria on a relatively short contact time. Denaturation of proteins seems likely based on a significant loss of enzymatic activity of the lysozyme protein. Characterization of these surfaces by atomic-force microscopy (AFM), Fourier-transform infra-red (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) reveals specific structural and chemical modifications as compared to untreated PS. Persistence of the biocidal properties of these treated surfaces is observed. This ozone-induced process is technically simple to achieve and does not require active precursors as in grafting.

  3. Streptomyces sporulation - Genes and regulators involved in bacterial cell differentiation

    OpenAIRE

    Larsson, Jessica

    2010-01-01

    Streptomycetes are Gram-positive bacteria with a complex developmental life cycle. They form spores on specialized cells called aerial hyphae, and this sporulation involves alterations in growth, morphogenesis and cell cycle processes like cell division and chromosome segregation. Understanding the developmental mechanisms that streptomycetes have evolved for regulating for example cell division is of general interest in bacterial cell biology. It can also be valuable in the design of new dru...

  4. Effects of whey on the colonization and sporulation of arbuscular ...

    African Journals Online (AJOL)

    The aim of this study is to research the effect of 2 different doses of whey [50 ml kg-1(W50) and 100 ml kg-1(W100)], an important organic waste, on colonization and sporulation of arbuscular mycorhizal fungus (AMF) Glomus intraradices'(G.i.) inoculated to lentil plant and the effects of changing P ratio in the soil and plant as ...

  5. The Influence of Sporulation Conditions on the Spore Coat Protein Composition of Bacillus subtilis Spores.

    Science.gov (United States)

    Abhyankar, Wishwas R; Kamphorst, Kiki; Swarge, Bhagyashree N; van Veen, Henk; van der Wel, Nicole N; Brul, Stanley; de Koster, Chris G; de Koning, Leo J

    2016-01-01

    Spores are of high interest to the food and health sectors because of their extreme resistance to harsh conditions, especially against heat. Earlier research has shown that spores prepared on solid agar plates have a higher heat resistance than those prepared under a liquid medium condition. It has also been shown that the more mature a spore is, the higher is its heat resistance most likely mediated, at least in part, by the progressive cross-linking of coat proteins. The current study for the first time assesses, at the proteomic level, the effect of two commonly used sporulation conditions on spore protein presence. 14 N spores prepared on solid Schaeffer's-glucose (SG) agar plates and 15 N metabolically labeled spores prepared in shake flasks containing 3-( N -morpholino) propane sulfonic acid (MOPS) buffered defined liquid medium differ in their coat protein composition as revealed by LC-FT-MS/MS analyses. The former condition mimics the industrial settings while the latter conditions mimic the routine laboratory environment wherein spores are developed. As seen previously in many studies, the spores prepared on the solid agar plates show a higher thermal resistance than the spores prepared under liquid culture conditions. The 14 N: 15 N isotopic ratio of the 1:1 mixture of the spore suspensions exposes that most of the identified inner coat and crust proteins are significantly more abundant while most of the outer coat proteins are significantly less abundant for the spores prepared on solid SG agar plates relative to the spores prepared in the liquid MOPS buffered defined medium. Sporulation condition-specific differences and variation in isotopic ratios between the tryptic peptides of expected cross-linked proteins suggest that the coat protein cross-linking may also be condition specific. Since the core dipicolinic acid content is found to be similar in both the spore populations, it appears that the difference in wet heat resistance is connected to the

  6. The Influence of Sporulation Conditions on the Spore Coat Protein Composition of Bacillus subtilis Spores

    Science.gov (United States)

    Abhyankar, Wishwas R.; Kamphorst, Kiki; Swarge, Bhagyashree N.; van Veen, Henk; van der Wel, Nicole N.; Brul, Stanley; de Koster, Chris G.; de Koning, Leo J.

    2016-01-01

    Spores are of high interest to the food and health sectors because of their extreme resistance to harsh conditions, especially against heat. Earlier research has shown that spores prepared on solid agar plates have a higher heat resistance than those prepared under a liquid medium condition. It has also been shown that the more mature a spore is, the higher is its heat resistance most likely mediated, at least in part, by the progressive cross-linking of coat proteins. The current study for the first time assesses, at the proteomic level, the effect of two commonly used sporulation conditions on spore protein presence. 14N spores prepared on solid Schaeffer’s-glucose (SG) agar plates and 15N metabolically labeled spores prepared in shake flasks containing 3-(N-morpholino) propane sulfonic acid (MOPS) buffered defined liquid medium differ in their coat protein composition as revealed by LC-FT-MS/MS analyses. The former condition mimics the industrial settings while the latter conditions mimic the routine laboratory environment wherein spores are developed. As seen previously in many studies, the spores prepared on the solid agar plates show a higher thermal resistance than the spores prepared under liquid culture conditions. The 14N:15N isotopic ratio of the 1:1 mixture of the spore suspensions exposes that most of the identified inner coat and crust proteins are significantly more abundant while most of the outer coat proteins are significantly less abundant for the spores prepared on solid SG agar plates relative to the spores prepared in the liquid MOPS buffered defined medium. Sporulation condition-specific differences and variation in isotopic ratios between the tryptic peptides of expected cross-linked proteins suggest that the coat protein cross-linking may also be condition specific. Since the core dipicolinic acid content is found to be similar in both the spore populations, it appears that the difference in wet heat resistance is connected to the

  7. The influence of sporulation conditions on the spore coat protein composition of Bacillus subtilis spores.

    Directory of Open Access Journals (Sweden)

    Wishwas R. Abhyankar

    2016-10-01

    Full Text Available Spores are of high interest to the food and health sectors because of their extreme resistance to harsh conditions, especially against heat. Earlier research has shown that spores prepared on solid agar plates have a higher heat resistance than those prepared under a liquid medium condition. It has also been shown that the more mature a spore is, the higher is its heat resistance most likely mediated, at least in part, by the progressive cross-linking of coat proteins. The current study for the first time assesses, at the proteomic level, the effect of two commonly used sporulation conditions on spore protein presence. 14N spores prepared on solid SG agar plates and 15N metabolically labelled spores prepared in shake flasks containing MOPS buffered defined liquid medium differ in their coat protein composition as revealed by LC-FT-MS/MS analyses. The former condition mimics the industrial settings while the latter conditions mimic the routine laboratory environment wherein spores are developed. As seen previously in many studies, the spores prepared on the solid agar plates show a higher thermal resistance than the spores prepared under liquid culture conditions. The 14N: 15N isotopic ratio of the 1:1 mixture of the spore suspensions exposes that most of the identified inner coat and crust proteins are significantly more abundant while most of the outer coat proteins are significantly less abundant for the spores prepared on solid SG agar plates relative to the spores prepared in the liquid MOPS buffered defined medium. Sporulation condition-specific differences and variation in isotopic ratios between the tryptic peptides of expected cross-linked proteins suggest that the coat protein cross-linking may also be condition specific. Since the core dipicolinic acid content is found to be similar in both the spore populations, it appears that the difference in wet heat resistance is connected to the differences in the coat protein composition and

  8. Large-scale functional genomic analysis of sporulation and meiosis in Saccharomyces cerevisiae.

    OpenAIRE

    Enyenihi, Akon H; Saunders, William S

    2003-01-01

    We have used a single-gene deletion mutant bank to identify the genes required for meiosis and sporulation among 4323 nonessential Saccharomyces cerevisiae annotated open reading frames (ORFs). Three hundred thirty-four sporulation-essential genes were identified, including 78 novel ORFs and 115 known genes without previously described sporulation defects in the comprehensive Saccharomyces Genome (SGD) or Yeast Proteome (YPD) phenotype databases. We have further divided the uncharacterized sp...

  9. Pre-sporulation stages of Streptomyces differentiation: state-of-the-art and future perspectives

    Science.gov (United States)

    Yagüe, Paula; López-García, Maria T.; Rioseras, Beatriz; Sánchez, Jesús; Manteca, Ángel

    2013-01-01

    Streptomycetes comprise very important industrial bacteria, producing two-thirds of all clinically relevant secondary metabolites. They are mycelial microorganisms with complex developmental cycles that include programmed cell death (PCD) and sporulation. Industrial fermentations are usually performed in liquid cultures (large bioreactors), conditions in which Streptomyces strains generally do not sporulate, and it was traditionally assumed that there was no differentiation. In this work, we review the current knowledge on Streptomyces pre-sporulation stages of Streptomyces differentiation. PMID:23496097

  10. Transcriptional Profile during Deoxycholate-Induced Sporulation in a Clostridium perfringens Isolate Causing Foodborne Illness.

    Science.gov (United States)

    Yasugi, Mayo; Okuzaki, Daisuke; Kuwana, Ritsuko; Takamatsu, Hiromu; Fujita, Masaya; Sarker, Mahfuzur R; Miyake, Masami

    2016-05-15

    Clostridium perfringens type A is a common source of foodborne illness (FBI) in humans. Vegetative cells sporulate in the small intestinal tract and produce the major pathogenic factor C. perfringens enterotoxin. Although sporulation plays a critical role in the pathogenesis of FBI, the mechanisms inducing sporulation remain unclear. Bile salts were shown previously to induce sporulation, and we confirmed deoxycholate (DCA)-induced sporulation in C. perfringens strain NCTC8239 cocultured with human intestinal epithelial Caco-2 cells. In the present study, we performed transcriptome analyses of strain NCTC8239 in order to elucidate the mechanism underlying DCA-induced sporulation. Of the 2,761 genes analyzed, 333 were up- or downregulated during DCA-induced sporulation and included genes for cell division, nutrient metabolism, signal transduction, and defense mechanisms. In contrast, the virulence-associated transcriptional regulators (the VirR/VirS system, the agr system, codY, and abrB) were not activated by DCA. DCA markedly increased the expression of signaling molecules controlled by Spo0A, the master regulator of the sporulation process, whereas the expression of spo0A itself was not altered in the presence or absence of DCA. The phosphorylation of Spo0A was enhanced in the presence of DCA. Collectively, these results demonstrated that DCA induced sporulation, at least partially, by facilitating the phosphorylation of Spo0A and activating Spo0A-regulated genes in strain NCTC8239 while altering the expression of various genes. Disease caused by Clostridium perfringens type A consistently ranks among the most common bacterial foodborne illnesses in humans in developed countries. The sporulation of C. perfringens in the small intestinal tract is a key event for its pathogenesis, but the factors and underlying mechanisms by which C. perfringens sporulates in vivo currently remain unclear. Bile salts, major components of bile, which is secreted from the liver for

  11. Selective inhibition of Bacillus subtilis sporulation by acridine orange and promethazine.

    Science.gov (United States)

    Burke, W F; Spizizen, J

    1977-03-01

    Two structurally similar compounds were found to inhibit sporulation in Bacillus subtilis 168. A dye, acridine orange, and an antischizophrenic drug, promethazine, blocked spore formation at concentrations subinhibitory to vegetative growth, while allowing synthesis of serine protease, antibiotic, and certain catabolite-repressed enzymes. The sporulation process was sensitive to promethazine through T2, whereas acridine orange was inhibitory until T4. The drug-treated cells were able to support the replication of phages phie and phi29, although the lytic cycles were altered slightly. The selective inhibition of sporulation by these compounds may be related to the affinity of some sporulation-specific genes to intercalating compounds.

  12. Medio EMJH modificado para el cultivo de Leptospira interrogans serogrupo Ballum Modified EMJH medium for cultivation of Leptospira interrogans serogroup Ballum

    Directory of Open Access Journals (Sweden)

    A. González

    2006-04-01

    . Antigenicity stability was evaluated by Western blotting using a specific antiserum. Cell yields commonly obtained in EMJH were triplicated without virulence or antigenicity depletions after culturing in a modified EMJH medium with an increased concentration of Tween 80, and the incorporation of sodium acetate and beef extract. Neither the increased concentration of at least 6 components of EMJH nor the incorporation of a variety of new nutrients stimulated cell yields or the growth rate of the microorganism. The results allow us to make use of an enriched culture medium that promotes high cell yields of this fastidious serogroup most prevalent in humans in Cuba.

  13. Artificial neural network-based predictive model for bacterial growth in a simulated medium of modified-atmosphere-packed cooked meat products.

    Science.gov (United States)

    Lou, W; Nakai, S

    2001-04-01

    The data of Devilieghere et al. (Int. J. Food Microbiol. 1999, 46, 57--70) on bacterial growth in a simulated medium of modified-atmosphere-packed cooked meat products was processed for estimating maximum specific growth rate mu(max) and lag phase lambda of Lactobacillus sake using artificial neural networks-based model (ANNM) computation. The comparison between ANNM and response surface methodology (RSM) model showed that the accuracy of ANNM prediction was higher than that of RSM. Two-dimensional and three-dimensional plots of the response surfaces revealed that the relationships of water activity a(w), temperature T, and dissolved CO(2) concentration with mu(max) and lambda were complicated, not just linear or second-order relations. Furthermore, it was possible to compute the sensitivity of the model outputs against each input parameter by using ANNM. The results showed that mu(max) was most sensitive to a(w), T, and dissolved CO(2) in this order; whereas lambda was sensitive to T the most, followed by a(w), and dissolved CO(2) concentrations.

  14. Sensitive determination of glucose in Dulbecco's modified Eagle medium by high-performance liquid chromatography with 1-phenyl-3-methyl-5-pyrazolone derivatization: application to gluconeogenesis studies.

    Science.gov (United States)

    Ling, Zhaoli; Xu, Ping; Zhong, Zeyu; Wang, Fan; Shu, Nan; Zhang, Ji; Tang, Xiange; Liu, Li; Liu, Xiaodong

    2016-04-01

    A new pre-column derivative high-performance liquid chromatography (HPLC) method for determination of d-glucose with 3-O-methyl-d-glucose (3-OMG) as the internal standard was developed and validated in order to study the gluconeogenesis in HepG2 cells. Samples were derivatized with 1-phenyl-3-methy-5-pyrazolone at 70°C for 50 min. Glucose and 3-OMG were extracted by liquid-liquid extraction and separated on a YMC-Triart C18 column, with a gradient mobile phase composed of acetonitrile and 20 mm ammonium acetate solution containing 0.09% tri-ethylamine at a flow rate of 1.0 mL/min. The eluate were detected using a UV detector at 250 nm. The assay was linear over the range 0.39-25 μm (R(2) = 0.9997, n = 5) and the lower limit of quantitation was 0.39 μm (0.070 mg/mL). Intra- and inter-day precision and accuracy were gluconeogenesis in Dulbecco's modified Eagle medium (DMEM) cultured HepG2 cells. Glucose concentration was determined to be about 1-2.5 μm in this gluconeogenesis assay. In conclusion, this method has been shown to determine small amounts of glucose in DMEM successfully, with lower limit of quantitation and better sensitivity when compared with common commercial glucose assay kits. Copyright © 2015 John Wiley & Sons, Ltd.

  15. Repeated triggering of sporulation in Bacillus subtilis selects against a protein that affects the timing of cell division

    NARCIS (Netherlands)

    Siebring, Jeroen; Elema, Matthijs J. H.; Vega, Fatima Drubi; Kovacs, Akos T.; Haccou, Patsy; Kuipers, Oscar P.

    Bacillus subtilis sporulation is a last-resort phenotypical adaptation in response to starvation. The regulatory network underlying this developmental pathway has been studied extensively. However, how sporulation initiation is concerted in relation to the environmental nutrient availability is

  16. The effect of salinity on the growth, sporulation and infection of Phytophthora ramorum

    Science.gov (United States)

    Phytophthora ramorum, a threat to Eastern U.S. forests, has been found in waterways outside the boundaries of infested ornamental nurseries. Very little is known about what factors are conducive to its survival and sporulation in water. This study examined the effect of salt on growth, sporulation,...

  17. Genome-wide transcriptional profiling of Clostridium perfringens SM101 during sporulation

    NARCIS (Netherlands)

    Xiao, Yinghua; Hijum, van Sacha A.; Abee, Tjakko; Wells-Bennik, Marjon H.

    2014-01-01

    In this study we focus on the identification of new genes tentatively involved in sporulation and those that influence properties of spores and their ability to germinate. To this end, the sporulation stages of C. perfringens enterotoxic strain SM101 were characterized based on morphological

  18. Effect of plant sterols and tannins on Phytophthora ramorum growth and sporulation

    Science.gov (United States)

    The acquisition of plant sterols, mediated via elicitins, is required for growth and sporulation of Phytophthora spp. In this paper, we looked at the interaction between elicitins, sterols, and tannins. When ground leaf tissue was added to growth media, P. ramorum growth and sporulation was greates...

  19. Phosphatases modulate the bistable sporulation gene expression pattern in Bacillus subtilis

    NARCIS (Netherlands)

    Veening, JW; Hamoen, LW; Kuipers, OP

    Spore formation in the Gram- positive bacterium Bacillus subtilis is a last resort adaptive response to starvation. To initiate sporulation, the key regulator in this process, Spo0A, needs to be activated by the so-called phosphorelay. Within a sporulating culture of B. subtilis, some cells initiate

  20. A mechanism for cell cycle regulation of sporulation initiation in Bacillus subtilis

    NARCIS (Netherlands)

    Veening, Jan-Willem; Murray, Heath; Errington, Jeff

    2009-01-01

    Coordination of DNA replication with cellular development is a crucial problem in most living organisms. Bacillus subtilis cells switch from vegetative growth to sporulation when starved. Sporulation normally occurs in cells that have stopped replicating DNA and have two completed chromosomes: one

  1. Sporulation of Bremia lactucae affected by temperature, relative humidity, and wind in controlled conditions

    NARCIS (Netherlands)

    Su, H.; Bruggen, van A.H.C.; Subbarao, K.V.; Scherm, H.

    2004-01-01

    The effects of temperature (5 to 25degreesC), relative humidity (81 to 100%), wind speed (0 to 1.0 in s(-1)), and their interactions on sporulation of Bremia lactucae on lettuce cotyledons were investigated in controlled conditions. Sporulation was affected significantly (P <0.0001) by

  2. Sporulation and survival of Toxoplasma gondii oocysts in different types of commercial cat litters

    Science.gov (United States)

    Toxoplasma gondii oocysts are environmentally resistant and can survive outdoors for months in the dry and cold climates. In the present study, sporulation and survival of T. gondii oocysts was studied in different types of cat litters commercially available in the US. Oocysts sporulated within 2-...

  3. Sporulation dynamics and spore heat resistance in wet and dry biofilms of Bacillus cereus

    NARCIS (Netherlands)

    Hayrapetyan, Hasmik; Abee, Tjakko; Nierop Groot, Masja

    2016-01-01

    Environmental conditions and growth history can affect the sporulation process as well as subsequent properties of formed spores. The sporulation dynamics was studied in wet and air-dried biofilms formed on stainless steel (SS) and polystyrene (PS) for Bacillus cereus ATCC 10987 and the

  4. Genome-Wide Transcriptional Profiling of Clostridium perfringens SM101 during Sporulation Extends the Core of Putative Sporulation Genes and Genes Determining Spore Properties and Germination Characteristics.

    Science.gov (United States)

    Xiao, Yinghua; van Hijum, Sacha A F T; Abee, Tjakko; Wells-Bennik, Marjon H J

    2015-01-01

    The formation of bacterial spores is a highly regulated process and the ultimate properties of the spores are determined during sporulation and subsequent maturation. A wide variety of genes that are expressed during sporulation determine spore properties such as resistance to heat and other adverse environmental conditions, dormancy and germination responses. In this study we characterized the sporulation phases of C. perfringens enterotoxic strain SM101 based on morphological characteristics, biomass accumulation (OD600), the total viable counts of cells plus spores, the viable count of heat resistant spores alone, the pH of the supernatant, enterotoxin production and dipicolinic acid accumulation. Subsequently, whole-genome expression profiling during key phases of the sporulation process was performed using DNA microarrays, and genes were clustered based on their time-course expression profiles during sporulation. The majority of previously characterized C. perfringens germination genes showed upregulated expression profiles in time during sporulation and belonged to two main clusters of genes. These clusters with up-regulated genes contained a large number of C. perfringens genes which are homologs of Bacillus genes with roles in sporulation and germination; this study therefore suggests that those homologs are functional in C. perfringens. A comprehensive homology search revealed that approximately half of the upregulated genes in the two clusters are conserved within a broad range of sporeforming Firmicutes. Another 30% of upregulated genes in the two clusters were found only in Clostridium species, while the remaining 20% appeared to be specific for C. perfringens. These newly identified genes may add to the repertoire of genes with roles in sporulation and determining spore properties including germination behavior. Their exact roles remain to be elucidated in future studies.

  5. [Regulation of sporulation by two-component system YvcPQ in Bacillus thuringiensis].

    Science.gov (United States)

    Fan, Qingyun; Zhang, Shumeng; Gong, Yujing; He, Jin

    2017-01-04

    To study the regulation of sporulation controlled by two-component system (TCS) YvcPQ. β-galactosidase experiment was used to verify the regulation of YvcP on kapD expression; bacterial one-hybrid assay, EMSA and RT-qPCR were applied to study the regulation of AbrB on yvcPQ expression; markerless gene deletion coupled with spore count was used to reveal the influence of yvcPQ and kapD expressions on sporulation. transcriptional regulator AbrB up-regulated the expression of yvcPQ; YvcP promoted the expression of kapD to inhibit sporulation. AbrB up-regulated the transcription of yvcPQ operon, then the increased YvcP strengthened the transcriptional acitivation of sporulation inhibitor gene kapD, and subsequently inhibited sporulation.

  6. Initiation of sporulation in Clostridium difficile: a twist on the classic model.

    Science.gov (United States)

    Edwards, Adrianne N; McBride, Shonna M

    2014-09-01

    The formation of dormant endospores is a complex morphological process that permits long-term survival in inhospitable environments for many Gram-positive bacteria. Sporulation for the anaerobic gastrointestinal pathogen Clostridium difficile is necessary for survival outside of the gastrointestinal tract of its host. While the developmental stages of spore formation are largely conserved among endospore-forming bacteria, the genus Clostridium appears to be missing a number of conserved regulators required for efficient sporulation in other spore-forming bacteria. Several recent studies have discovered novel mechanisms and distinct regulatory pathways that control the initiation of sporulation and early-sporulation-specific gene expression. These differences in regulating the decision to undergo sporulation reflects the unique ecological niche and environmental conditions that C. difficile inhabits and encounters within the mammalian host. © 2014 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

  7. THE EFFECT OF GROWTH PARAMETERS ON THE ANTIBIOTIC ACTIVITY AND SPORULATION IN BACILLUS SPP. ISOLATED FROM SOIL

    Directory of Open Access Journals (Sweden)

    Alev Usta

    2013-04-01

    Full Text Available Fifty-two Bacillus strains, which were isolated from different soil samples, were screened for antibiotic properties. The Bacillus strains were checked for antibacterial properties by the cross-streak method against 5 test pathogens, and 25 Bacillus strains had an effect on the test microorganisms. One strain of Bacillus, which exhibited the largest inhibition zone (25 mm against Shigella sonnei, was named Bacillus sp. EA62. The antibacterial activity from Bacillus sp. EA62 was tested in six different culture media against Shigella sonnei using the agar well diffusion method. The best activity medium was selected and used for further studies. The influence of the incubation period, pH, and different glucose and nitrogen concentrations on the antibacterial activity was studied. The optimal conditions for the strongest antibiotic activity were found to be 72 hours (18 mm, pH 7.5 (23 mm, 3% glucose (25 mm, and 0.3% nitrogen concentration (23 mm. Additionally, the relationship between the antibiotic activity and sporulation was investigated. Accordingly, it was determined that the increase of the activity paralleled sporulation.

  8. Diglycolic acid modified zirconium phosphate and studies on the extraction of Am(III) and Eu(III) from dilute nitric acid medium

    Energy Technology Data Exchange (ETDEWEB)

    Selvan, B. Robert; Suneesh, A.S.; Venkatesan, K.A.; Antony, M.P. [Indira Gandhi Centre for Atomic Research, Kalpakkam (India). Fuel Chemistry Division; Dasthaiah, K.; Gardas, R.L. [Indian Institute of Technology - Madras, Chennai (India). Dept. of Chemistry

    2017-06-01

    Diglycolic acid modified zirconium phosphate (ZrP-DGA) was prepared and studied for the extraction of Am(III) and Eu(III) from dilute nitric acid medium. The distribution coefficient (K{sub d}, mL.g{sup -1}) of Am(III) and Eu(III) was measured as a function of time, pH and concentration of Eu(III) ion etc. The K{sub d} of Am(III) and Eu(III) increased with increase of pH, reached a maximum value of distribution coefficient at pH 1.5 - 2, followed by decrease in K{sub d} values. Rapid extraction of Am(III) and Eu(III) in ZrP-DGA was observed followed by the establishment of equilibrium occurred in 100 min. Kinetics of extraction was fitted in to pseudo second order rate equation. The amount of Eu(III) loaded in ZrP-DGA increased with increase in the concentration of Eu(III) ion in aqueous phase and the isotherm was fitted in to Langmuir and Freundlich adsorption models. The extraction of Am(III) in ZrP-DGA was higher as compared to Eu(III) and the interference of Eu(III) on the extraction of Am(III) was studied. The distribution coefficient of some lanthanides in ZrP-DGA was measured and the K{sub d} of lanthanides increased across the lanthanide series. The extracted trivalent metal ions were recovered in three contacts of loaded ZrP-DGA with 0.5 M nitric acid.

  9. Global iTRAQ-based proteomic profiling of Toxoplasma gondii oocysts during sporulation.

    Science.gov (United States)

    Zhou, Chun-Xue; Zhu, Xing-Quan; Elsheikha, Hany M; He, Shuai; Li, Qian; Zhou, Dong-Hui; Suo, Xun

    2016-10-04

    Toxoplasma gondii is a medically and economically important protozoan parasite. However, the molecular mechanisms of its sporulation remain largely unknown. Here, we applied iTRAQ coupled with 2D LC-MS/MS proteomic analysis to investigate the proteomic expression profile of T. gondii oocysts during sporulation. Of the 2095 non-redundant proteins identified, 587 were identified as differentially expressed proteins (DEPs). Based on Gene Ontology enrichment and KEGG pathway analyses the majority of these DEPs were found related to the metabolism of amino acids, carbon and energy. Protein interaction network analysis generated by STRING identified ATP-citrate lyase (ACL), GMP synthase, IMP dehydrogenase (IMPDH), poly (ADP-ribose) glycohydrolase (PARG), and bifunctional dihydrofolate reductase-thymidylate synthase (DHFR-TS) as the top five hubs. We also identified 25 parasite virulence factors that were expressed at relatively high levels in sporulated oocysts compared to non-sporulated oocysts, which might contribute to the infectivity of mature oocysts. Considering the importance of oocysts in the dissemination of toxoplasmosis these findings may help in the search of protein targets with a key role in infectiousness and ecological success of oocysts, creating new opportunities for the development of better means for disease prevention. The development of new preventative interventions against T. gondii infection relies on an improved understanding of the proteome and chemical pathways of this parasite. To identify proteins required for the development of environmentally resistant and infective T. gondii oocysts, we compared the proteome of non-sporulated (immature) oocysts with the proteome of sporulated (mature, infective) oocysts. iTRAQ 2D-LC-MS/MS analysis revealed proteomic changes that distinguish non-sporulated from sporulated oocysts. Many of the differentially expressed proteins were involved in metabolic pathways and 25 virulence factors were identified

  10. Involvement of Clostridium botulinum ATCC 3502 sigma factor K in early-stage sporulation.

    Science.gov (United States)

    Kirk, David G; Dahlsten, Elias; Zhang, Zhen; Korkeala, Hannu; Lindström, Miia

    2012-07-01

    A key survival mechanism of Clostridium botulinum, the notorious neurotoxic food pathogen, is the ability to form heat-resistant spores. While the genetic mechanisms of sporulation are well understood in the model organism Bacillus subtilis, nothing is known about these mechanisms in C. botulinum. Using the ClosTron gene-knockout tool, sigK, encoding late-stage (stage IV) sporulation sigma factor K in B. subtilis, was disrupted in C. botulinum ATCC 3502 to produce two different mutants with distinct insertion sites and orientations. Both mutants were unable to form spores, and their elongated cell morphology suggested that the sporulation pathway was blocked at an early stage. In contrast, sigK-complemented mutants sporulated successfully. Quantitative real-time PCR analysis of sigK in the parent strain revealed expression at the late log growth phase in the parent strain. Analysis of spo0A, encoding the sporulation master switch, in the sigK mutant and the parent showed significantly reduced relative levels of spo0A expression in the sigK mutant compared to the parent strain. Similarly, sigF showed significantly lower relative transcription levels in the sigK mutant than the parent strain, suggesting that the sporulation pathway was blocked in the sigK mutant at an early stage. We conclude that σ(K) is essential for early-stage sporulation in C. botulinum ATCC 3502, rather than being involved in late-stage sporulation, as reported for the sporulation model organism B. subtilis. Understanding the sporulation mechanism of C. botulinum provides keys to control the public health risks that the spores of this dangerous pathogen cause through foods.

  11. Effects of Bile Acids and Nisin on the Production of Enterotoxin by Clostridium perfringens in a Nutrient-Rich Medium

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    Miseon Park

    2018-01-01

    Full Text Available Clostridium perfringens is the second most common cause of bacterial foodborne illness in the United States, with nearly a million cases each year. C. perfringens enterotoxin (CPE, produced during sporulation, damages intestinal epithelial cells by pore formation, which results in watery diarrhea. The effects of low concentrations of nisin and bile acids on sporulation and toxin production were investigated in C. perfringens SM101, which carries an enterotoxin gene on the chromosome, in a nutrient-rich medium. Bile acids and nisin increased production of enterotoxin in cultures; bile acids had the highest effect. Both compounds stimulated the transcription of enterotoxin and sporulation-related genes and production of spores during the early growth phase. They also delayed spore outgrowth and nisin was more inhibitory. Bile acids and nisin enhanced enterotoxin production in some but not all other C. perfringens isolates tested. Low concentrations of bile acids and nisin may act as a stress signal for the initiation of sporulation and the early transcription of sporulation-related genes in some strains of C. perfringens, which may result in increased strain-specific production of enterotoxin in those strains. This is the first report showing that nisin and bile acids stimulated the transcription of enterotoxin and sporulation-related genes in a nutrient-rich bacterial culture medium.

  12. Effects of Bile Acids and Nisin on the Production of Enterotoxin by Clostridium perfringens in a Nutrient-Rich Medium.

    Science.gov (United States)

    Park, Miseon; Rafii, Fatemeh

    2018-01-01

    Clostridium perfringens is the second most common cause of bacterial foodborne illness in the United States, with nearly a million cases each year. C. perfringens enterotoxin (CPE), produced during sporulation, damages intestinal epithelial cells by pore formation, which results in watery diarrhea. The effects of low concentrations of nisin and bile acids on sporulation and toxin production were investigated in C. perfringens SM101, which carries an enterotoxin gene on the chromosome, in a nutrient-rich medium. Bile acids and nisin increased production of enterotoxin in cultures; bile acids had the highest effect. Both compounds stimulated the transcription of enterotoxin and sporulation-related genes and production of spores during the early growth phase. They also delayed spore outgrowth and nisin was more inhibitory. Bile acids and nisin enhanced enterotoxin production in some but not all other C. perfringens isolates tested. Low concentrations of bile acids and nisin may act as a stress signal for the initiation of sporulation and the early transcription of sporulation-related genes in some strains of C. perfringens , which may result in increased strain-specific production of enterotoxin in those strains. This is the first report showing that nisin and bile acids stimulated the transcription of enterotoxin and sporulation-related genes in a nutrient-rich bacterial culture medium.

  13. The APSES protein Sok2 is a positive regulator of sporulation in Ashbya gossypii.

    Science.gov (United States)

    Wasserstrom, Lisa; Dünkler, Alexander; Walther, Andrea; Wendland, Jürgen

    2017-12-01

    Ashbya gossypii is a homothallic, flavinogenic, filamentous ascomycete that starts overproduction of riboflavin and fragments its mycelium quantitatively into spore producing sporangia at the end of a growth phase. Mating is not required for sporulation and the standard homothallic laboratory strain is a MATa strain. Here we show that ectopic expression of Saccharomyces cerevisiae MATα2 in A. gossypii completely suppresses sporulation, inhibits riboflavin overproduction and downregulates among others AgSOK2. AgSok2 belongs to a fungal-specific group of (APSES) transcription factors. Deletion of AgSOK2 strongly reduces riboflavin production and blocks sporulation. The initiator of meiosis, AgIME1, is a transcription factor essential for sporulation. We characterized the AgIME1 promoter region required for complementation of the Agime1 mutant. Reporter assays with AgIME1 promoter fragments fused to lacZ showed that AgSok2 does not control AgIME1 transcription. However, global transcriptome analysis identified two other essential regulators of sporulation, AgIME2 and AgNDT80, as potential targets of AgSok2. Our data suggest that sporulation and riboflavin production in A. gossypii are under mating type locus and nutritional control. Sok2, a target of the cAMP/protein kinase A pathway, serves as a central positive regulator to promote sporulation. This contrasts Saccharomyces cerevisiae where Sok2 is a repressor of IME1 transcription. © 2017 John Wiley & Sons Ltd.

  14. Selection of G1 Phase Yeast Cells for Synchronous Meiosis and Sporulation.

    Science.gov (United States)

    Stuart, David T

    2017-01-01

    Centrifugal elutriation is a procedure that allows the fractionation of cell populations based upon their size and shape. This allows cells in distinct cell cycle stages can be captured from an asynchronous population. The technique is particularly helpful when performing an experiment to monitor the progression of cells through the cell cycle or meiosis. Yeast sporulation like gametogenesis in other eukaryotes initiates from the G1 phase of the cell cycle. Conveniently, S. cerevisiae arrest in G1 phase when starved for nutrients and so withdrawal of nitrogen and glucose allows cells to abandon vegetative growth in G1 phase before initiating the sporulation program. This simple starvation protocol yields a partial synchronization that has been used extensively in studies of progression through meiosis and sporulation. By using centrifugal elutriation it is possible to isolate a homogeneous population of G1 phase cells and induce them to sporulate synchronously, which is beneficial for investigating progression through meiosis and sporulation. An additionally benefit of this protocol is that cell populations can be isolated based upon size and both large and small cell populations can be tested for progression through meiosis and sporulation. Here we present a protocol for purification of G1 phase diploid cells for examining synchronous progression through meiosis and sporulation.

  15. Effects of microbial loading and sporulation temperature on atmospheric plasma inactivation of Bacillus subtilis spores

    Science.gov (United States)

    Deng, X. T.; Shi, J. J.; Shama, G.; Kong, M. G.

    2005-10-01

    Current inactivation studies of Bacillus subtilis spores using atmospheric-pressure glow discharges (APGD) do not consider two important factors, namely microbial loading at the surface of a substrate and sporulation temperature. Yet these are known to affect significantly microbial resistance to heat and hydrogen peroxide. This letter investigates effects of microbial loading and sporulation temperature on spore resistance to APGD. It is shown that microbial loading can lead to a stacking structure as a protective shield against APGD treatment and that high sporulation temperature increases spore resistance by altering core water content and cross-linked muramic acid content of B. subtilis spores.

  16. Identification of diacetonamine from soybean curd residue as a sporulation-inducing factor toward Bacillus spp.

    Science.gov (United States)

    Ikeda, Aki; Kim, Dongyeop; Hashidoko, Yasuyuki

    2017-12-01

    Under bioassay-guided investigation, a sporulation-inducing factor (SIF) toward Bacillus spp. was searched for in methanol (MeOH) extracts of soybean curd residues, and diacetonamine (1) was identified as the active compound. SIF was first isolated as a monoacetylated derivative (2, 4.1 mg from 655 g soybean curd residues), and its chemical structure was elucidated by field desorption mass spectrometry, electron ionization mass spectrometry, and nuclear magnetic resonance (NMR) analyses. After 48-h incubation, 40 µM diacetonamine hydrochloride (1b) exhibited sporulation-inducing activity with 35% sporulation frequency toward a Bacillus amyloliquefaciens wild-type strain (AHU 2170), whereas 40 µM diacetone acrylamide (3) showed 99% sporulation induction, which was much higher than that of 1b. Although Bacillus megaterium NBRC 15308 was sporulated by the treatment with 400 µM 1b with 36 and 70% sporulation frequency after 72- and 96-h incubation respectively, 3 at the same concentration showed only 2% sporulation after 72-h incubation. Hence, diacetonamine (1) was characterized as a genuine SIF from soybean curd residues, but it was uncertain whether 1 is a natural product or an artifact. Spores of B. amyloliquefaciens induced by 1b survived after treatment with heating at 95 °C for 10 min, also suggesting that 1 is genuine SIF in soybean curd residue. As sporulation induction is likely linked to activation of antibiotic production in some spore-forming Firmicutes bacteria, compound 1 would be a possible chemical tool to develop an effective fermentation technology in Bacillus species.

  17. Reconsidering the sporulation characteristics of hypervirulent Clostridium difficile BI/NAP1/027.

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    David A Burns

    Full Text Available Clostridium difficile is the leading cause of antibiotic-associated diarrhoea and a major burden to healthcare services worldwide. In recent years, C. difficile strains belonging to the BI/NAP1/027 type have become highly represented among clinical isolates. These so-called 'hypervirulent' strains are associated with outbreaks of increased disease severity, higher relapse rates and an expanded repertoire of antibiotic resistance. Spores, formed during sporulation, play a pivotal role in disease transmission and it has been suggested that BI/NAP1/027 strains are more prolific in terms of sporulation in vitro than 'non-epidemic' C. difficile types. Work in our laboratory has since provided credible evidence to the contrary suggesting that the strain-to-strain variation in C. difficile sporulation characteristics is not type-associated. However, the BI/NAP1/027 type is still widely stated to have an increased rate of sporulation. In this study, we analysed the sporulation rates of 53 C. difficile strains, the largest sample size used to-date in such a study, including 28 BI/NAP1/027 isolates. Our data confirm that significant variation exists in the rate at which different C. difficile strains form spores. However, we clearly show that the sporulation rate of the BI/NAP1/027 type was no higher than that of non-BI/NAP1/027 strains. In addition, we observed substantial variation in sporulation characteristics within the BI/NAP1/027 type. This work highlights the danger of assuming that all strains of one type behave similarly without studying adequate sample sizes. Furthermore, we stress the need for more rigorous experimental procedures in order to quantify C. difficile sporulation more accurately in the future.

  18. Increased Sporulation of Vesicular-Arbuscular Mycorrhizal Fungi by Manipulation of Nutrient Regimens †

    OpenAIRE

    Douds, David D.; Schenck, N. C.

    1990-01-01

    Adjustment of pot culture nutrient solutions increased root colonization and sporulation of vesicular-arbuscular mycorrhizal (VAM) fungi. Paspalum notatum Flugge and VAM fungi were grown in a sandy soil low in N and available P. Hoagland nutrient solution without P enhanced sporulation in soil and root colonization of Acaulospora longula, Scutellospora heterogama, Gigaspora margarita, and a wide range of other VAM fungi over levels produced by a tap water control or nutrient solutions contain...

  19. Esporulação de Pyricularia grisea em diferentes meios de cultura e regimes de luz Sporulation of Pyricularia grisea on different culture media and light regimes

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    Maria Fernanda Antunes da Cruz

    2009-08-01

    Full Text Available Diferentes fatores influenciam o crescimento e a esporulação dos fungos, tais como: composição do meio de cultivo, temperatura e luz. O objetivo do trabalho foi determinar o melhor meio de cultivo e regime de luz para a esporulação de Pyricularia grisea. Um isolado deste, obtido da cultivar de trigo 'BRS 194', foi repicado por disco micelial em oito meios de cultivo (farinha integral de arroz, aveia, centeio, cevada, trigo, triticale; BSA e extrato de tomate e submetido a três regimes de luz (escuro, fotoperíodo de 12h e luz contínua. As placas permaneceram por 10 dias, em câmara de crescimento sob temperatura de 23-25°C. Em seguida, o número de conídios foi determinado em câmara de Neubauer. O meio de cultivo à base de farinha integral de trigo propiciou a maior esporulação do fungo em todos os regimes de luz, e a maior esporulação ocorreu em regime de luz contínua para todos os meios de cultivos testados. Os meios de arroz e BSA propiciaram uma menor produção de conídios pelo fungo.A set of conditions is necessary for the growth and sporulation of fungi, particularly the composition of culture media, temperature and light. The objective of this research was to determine the ideal culture medium and light regime for the sporulation of P. grisea. Micelial discs of an isolate, obtained from cultivar 'BRS 194' of wheat, were transferred to eight culture media (rice wholemeal, oat, rye, barley, wheat, triticale, PSA and tomato sauce and kept in the dark, under continuous light and 12h of light. In a growing chamber, for 10 days at 23-25°C. Then, the number of conidia was determined in a Neubauer chamber. The higher sporulation, regardless of light regime, was observed on wheat wholemeal culture medium. The continuous light provided higher sporulation this fungus in all culture medium. The lowest production of conidia was observed on rice wholemeal and PSA culture media.

  20. Small proteins link coat and cortex assembly during sporulation in Bacillus subtilis

    Science.gov (United States)

    Ebmeier, Sarah E.; Tan, Irene S.; Clapham, Katie Rose; Ramamurthi, Kumaran S.

    2015-01-01

    Summary Mature spores of the bacterium Bacillus subtilis are encased by two concentric shells: an inner shell (the ‘cortex’), made of peptidoglycan; and an outer proteinaceous shell (the ‘coat’), whose basement layer is anchored to the surface of the developing spore via a 26-amino-acid-long protein called SpoVM. During sporulation, initiation of cortex assembly depends on the successful initiation of coat assembly, but the mechanisms that co-ordinate the morphogenesis of both structures are largely unknown. Here, we describe a sporulation pathway involving SpoVM and a 37-amino-acid-long protein named ‘CmpA’ that is encoded by a previously un-annotated gene and is expressed under control of two sporulation-specific transcription factors (σE and SpoIIID). CmpA localized to the surface of the developing spore and deletion of cmpA resulted in cells progressing through the sporulation programme more quickly. Overproduction of CmpA did not affect normal growth or cell division, but delayed entry into sporulation and abrogated cortex assembly. In those cells that had successfully initiated coat assembly, CmpA was removed by a posttranslational mechanism, presumably in order to overcome the sporulation inhibition it imposed. We propose a model in which CmpA participates in a developmental checkpoint that ensures the proper orchestration of coat and cortex morphogenesis by repressing cortex assembly until coat assembly successfully initiates. PMID:22463703

  1. Metagenomic analysis of buffalo rumen microbiome: Effect of roughage diet on Dormancy and Sporulation genes.

    Science.gov (United States)

    Singh, K M; Reddy, B; Patel, A K; Panchasara, H; Parmar, N; Patel, A B; Shah, T M; Bhatt, V D; Joshi, C G

    2014-12-01

    Buffalo rumen microbiome experiences a variety of diet stress and represents reservoir of Dormancy and Sporulation genes. However, the information on genomic responses to such conditions is very limited. The Ion Torrent PGM next generation sequencing technology was used to characterize general microbial diversity and the repertoire of microbial genes present, including genes associated with Dormancy and Sporulation in Mehsani buffalo rumen metagenome. The research findings revealed the abundance of bacteria at the domain level and presence of Dormancy and Sporulation genes which were predominantly associated with the Clostridia and Bacilli taxa belonging to the phyla Firmicutes. Genes associated with Sporulation cluster and Sporulation orphans were increased from 50% to 100% roughage treatment, thereby promoting sporulation all along the treatments. The spore germination is observed to be the highest in the 75% roughage treatment both in the liquid and solid rumen fraction samples with respect to the decrease in the values of the genes associated with spore core dehydration, thereby facilitating spore core hydration which is necessary for spore germination.

  2. The effect of fermentable carbohydrate on sporulation and butanol production by Clostridium acetobutylicum P262

    Energy Technology Data Exchange (ETDEWEB)

    Awang, G.M.; Ingledew, W.M.; Jones, G.A. (Saskatchewan Univ., Saskatoon, SK (Canada). Dept. of Applied Microbiology and Food Science)

    1992-10-01

    This study was conducted to determine whether or not a variation in the type of carbohydrate fermented by Clostridium acetobutylicum could be exploited to inhibit sporulation during the butanol-producing phase of fermentation and thus enhance butanol production. C. acetobutylicum P262 was found to ferment a wide variety of carbohydrates, but butanol production was not necessarily enhanced when percentage sporulation was low. Butanol concentration was more related to the total amount of acidic end-products (acetic and butyric acid) reutilized by the microorganism for solvent production and to the type and amount of carbohydrate utilized. Fermentation of cellobiose led to conditions resulting in complete acid reutilization and the highest butanol concentration (10.4-10.6 g/l). In cultures containing a mixture of glucose and cellobiose, glucose repression of cellobiose utilization resulted in lower butanol concentrations (6.6-7.5 g/l). Sporulation was dependent on the type of carbohydrate utilized by the microorgamism. Glucose had a greater enhancing effect on the sporulation process (22-42%) than starch (9-12%) or cellobiose (22-34%). It was concluded that whereas the type of carbohydrate fermented has a specific effect on the extent of sporulation of a culture, conditions of low sporulation did not enhance butanol concentration unless carbohydrate utilization and the reutilization of acidic products were high. (orig.).

  3. Asexual sporulation facilitates adaptation: The emergence of azole resistance in Aspergillus fumigatus.

    Science.gov (United States)

    Zhang, Jianhua; Debets, Alfons J M; Verweij, Paul E; Melchers, Willem J G; Zwaan, Bas J; Schoustra, Sijmen E

    2015-10-01

    Understanding the occurrence and spread of azole resistance in Aspergillus fumigatus is crucial for public health. It has been hypothesized that asexual sporulation, which is abundant in nature, is essential for phenotypic expression of azole resistance mutations in A. fumigatus facilitating subsequent spread through natural selection. Furthermore, the disease aspergilloma is associated with asexual sporulation within the lungs of patients and the emergence of azole resistance. This study assessed the evolutionary advantage of asexual sporulation by growing the fungus under pressure of one of five different azole fungicides over seven weeks and by comparing the rate of adaptation between scenarios of culturing with and without asexual sporulation. Results unequivocally show that asexual sporulation facilitates adaptation. This can be explained by the combination of more effective selection because of the transition from a multicellular to a unicellular stage, and by increased mutation supply due to the production of spores, which involves numerous mitotic divisions. Insights from this study are essential to unravel the resistance mechanisms of sporulating pathogens to chemical compounds and disease agents in general, and for designing strategies that prevent or overcome the emerging threat of azole resistance in particular. © 2015 The Author(s). Evolution © 2015 The Society for the Study of Evolution.

  4. Temperature and light intensity interaction on Cercospora coffeicola sporulation and conidia germination

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    Marília Goulart da Silva

    2016-04-01

    Full Text Available ABSTRACT Difficulty in obtaining abundant sporulation in culture of many species of Cercospora may be the limiting factor for studies of biology, systematics, and inoculation of the genus. Therefore, it is necessary to understand the nutritional and environmental requirements that influence mycelial growth, sporulation and germination. As it is difficult to obtain conidia of Cercospora coffeicola in vitro, different temperatures (17, 22, 27, and 32 °C and light intensities (80, 160, 240, and 320 μmol m-2 s-1 were evaluated to optimize pathogen sporulation and assess favorable conditions for spore germination, aiming for a strategy of disease control. The dark treatment (0 μmol m-2 s-1 was added for sporulation. A significant interaction was found between temperature and light intensity for both variables. The highest sporulation rate of C. coffeicola occurred at a light intensity of 240 μmol m-2 s-1 and air temperature of 22 °C, reaching 5.9x106 con mL-1. Germination was higher at temperature 17 °C and light intensity of 320 μmol m-2 s-1, reaching 52%. Interaction between light intensity and temperature proved to influence the processes of sporulation and germination of C. coffeicola.

  5. Four linked genes participate in controlling sporulation efficiency in budding yeast.

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    Giora Ben-Ari

    2006-11-01

    Full Text Available Quantitative traits are conditioned by several genetic determinants. Since such genes influence many important complex traits in various organisms, the identification of quantitative trait loci (QTLs is of major interest, but still encounters serious difficulties. We detected four linked genes within one QTL, which participate in controlling sporulation efficiency in Saccharomyces cerevisiae. Following the identification of single nucleotide polymorphisms by comparing the sequences of 145 genes between the parental strains SK1 and S288c, we analyzed the segregating progeny of the cross between them. Through reciprocal hemizygosity analysis, four genes, RAS2, PMS1, SWS2, and FKH2, located in a region of 60 kilobases on Chromosome 14, were found to be associated with sporulation efficiency. Three of the four "high" sporulation alleles are derived from the "low" sporulating strain. Two of these sporulation-related genes were verified through allele replacements. For RAS2, the causative variation was suggested to be a single nucleotide difference in the upstream region of the gene. This quantitative trait nucleotide accounts for sporulation variability among a set of ten closely related winery yeast strains. Our results provide a detailed view of genetic complexity in one "QTL region" that controls a quantitative trait and reports a single nucleotide polymorphism-trait association in wild strains. Moreover, these findings have implications on QTL identification in higher eukaryotes.

  6. A frame work for heat generation/absorption and modified homogeneous–heterogeneous reaction in flow based on non-Darcy–Forchheimer medium

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    Tasawar Hayat

    2018-04-01

    Full Text Available The present work aims to report the consequences of Darcy–Forchheimer medium in flow of Cross fluid model toward a stretched surface. Flow in porous space is categorized by Darcy–Forchheimer medium. Further heat transfer characteristics are examined via thermal radiation and heat generation/absorption. Transformation procedure is used. The arising system of nonlinear ordinary differential equations is solved numerically by means of shooting method. The effects of different flow variables on velocity, temperature, concentration, skin friction, and heat transfer rate are discussed. The obtained outcomes show that velocity was enhanced with the increase in the Weissenberg number but decays with increase in the porosity parameter and Hartman number. Temperature field is boosted by thermal radiation and heat generation; however, it decays with the increase in the Prandtl number. Keywords: Cross Fluid, Heat Generation/Absorption, Homogeneous–Heterogeneous Reactions, Non-Darcy–Forchheimer Medium, Thermal Radiation

  7. σK of Clostridium acetobutylicum is the first known sporulation-specific sigma factor with two developmentally separated roles, one early and one late in sporulation.

    Science.gov (United States)

    Al-Hinai, Mohab A; Jones, Shawn W; Papoutsakis, Eleftherios T

    2014-01-01

    Sporulation in the model endospore-forming organism Bacillus subtilis proceeds via the sequential and stage-specific activation of the sporulation-specific sigma factors, σ(H) (early), σ(F), σ(E), σ(G), and σ(K) (late). Here we show that the Clostridium acetobutylicum σ(K) acts both early, prior to Spo0A expression, and late, past σ(G) activation, thus departing from the B. subtilis model. The C. acetobutylicum sigK deletion (ΔsigK) mutant was unable to sporulate, and solventogenesis, the characteristic stationary-phase phenomenon for this organism, was severely diminished. Transmission electron microscopy demonstrated that the ΔsigK mutant does not develop an asymmetric septum and produces no granulose. Complementation of sigK restored sporulation and solventogenesis to wild-type levels. Spo0A and σ(G) proteins were not detectable by Western analysis, while σ(F) protein levels were significantly reduced in the ΔsigK mutant. spo0A, sigF, sigE, sigG, spoIIE, and adhE1 transcript levels were all downregulated in the ΔsigK mutant, while those of the sigH transcript were unaffected during the exponential and transitional phases of culture. These data show that σ(K) is necessary for sporulation prior to spo0A expression. Plasmid-based expression of spo0A in the ΔsigK mutant from a nonnative promoter restored solventogenesis and the production of Spo0A, σ(F), σ(E), and σ(G), but not sporulation, which was blocked past the σ(G) stage of development, thus demonstrating that σ(K) is also necessary in late sporulation. sigK is expressed very early at low levels in exponential phase but is strongly upregulated during the middle to late stationary phase. This is the first sporulation-specific sigma factor shown to have two developmentally separated roles.

  8. A microPIXE investigation of the interaction of cells of Schizosaccharomyces pombe with the culture medium

    Energy Technology Data Exchange (ETDEWEB)

    Rombouts, P.M.M. [Ion Beam Centre, Advanced Technology Institute, School of Electronics and Physical Sciences, University of Surrey, Guildford GU2 7XH (United Kingdom); Gomez-Morilla, I. [Ion Beam Centre, Advanced Technology Institute, School of Electronics and Physical Sciences, University of Surrey, Guildford GU2 7XH (United Kingdom); Grime, G.W. [Ion Beam Centre, Advanced Technology Institute, School of Electronics and Physical Sciences, University of Surrey, Guildford GU2 7XH (United Kingdom); Webb, R.P. [Ion Beam Centre, Advanced Technology Institute, School of Electronics and Physical Sciences, University of Surrey, Guildford GU2 7XH (United Kingdom); Cuenca, L. [Fluids and Systems Research Centre, School of Engineering, University of Surrey, Guildford GU2 7XH (United Kingdom); Rodriguez, R. [Fluids and Systems Research Centre, School of Engineering, University of Surrey, Guildford GU2 7XH (United Kingdom); Browton, M. [Ion Beam Centre, Advanced Technology Institute, School of Electronics and Physical Sciences, University of Surrey, Guildford GU2 7XH (United Kingdom); Wardell, N. [School of Biomedical and Molecular Sciences, University of Surrey, Guildford GU2 7XH (United Kingdom); Underwood, B. [Fluids and Systems Research Centre, School of Engineering, University of Surrey, Guildford GU2 7XH (United Kingdom); Kirkby, N.F. [Fluids and Systems Research Centre, School of Engineering, University of Surrey, Guildford GU2 7XH (United Kingdom); Kirkby, K.J. [Ion Beam Centre, Advanced Technology Institute, School of Electronics and Physical Sciences, University of Surrey, Guildford GU2 7XH (United Kingdom)]. E-mail: k.kirkby@surrey.ac.uk

    2007-07-15

    Schizosaccharomyces pombe (S. pombe) is a eucaryotic cell type similar to mammalian cells but much more simple. As it also executes its cell cycle rapidly it is very useful for investigating basic processes in cells. In this paper we report a feasibility study of the applicability of microPIXE to investigate the interaction between S. pombe cells and the surrounding culture medium. Cells were cultured in various growth medium prior to preparation for analysis. 1 {mu}l drops of medium and cells were spotted onto polypropylene foils held in contact with a polished copper block previously cooled in liquid nitrogen. The samples were dehydrated by freeze-drying. Micro PIXE analysis was carried out with the IBC microbeam facility using a beam of 2.5 MeV protons focused to 1-2 {mu}m diameter. Initially no elemental contrast was observed between the cells and the medium, but by modifying the dilution of the cell suspension, the cells could be distinguished from the surrounding medium through an increased concentration of P and reduced concentration of Cl. The distribution of Na in the medium around the cells showed evidence of the action of the Na pump. Sporulation appears to be induced in the cells by adding Cu to the growth medium and the uptake of Cu by the cells could be clearly observed. This study shows that it is possible to analyse the mass transport of elements in and out of cells In the future this will enable concentration gradients to be analysed and allow the rate of production or consumption of individual cells to be calculated. By observing these patterns for individual cells (not populations) at various known points in the cell cycle, fundamental data can be derived.

  9. A microPIXE investigation of the interaction of cells of Schizosaccharomyces pombe with the culture medium

    International Nuclear Information System (INIS)

    Rombouts, P.M.M.; Gomez-Morilla, I.; Grime, G.W.; Webb, R.P.; Cuenca, L.; Rodriguez, R.; Browton, M.; Wardell, N.; Underwood, B.; Kirkby, N.F.; Kirkby, K.J.

    2007-01-01

    Schizosaccharomyces pombe (S. pombe) is a eucaryotic cell type similar to mammalian cells but much more simple. As it also executes its cell cycle rapidly it is very useful for investigating basic processes in cells. In this paper we report a feasibility study of the applicability of microPIXE to investigate the interaction between S. pombe cells and the surrounding culture medium. Cells were cultured in various growth medium prior to preparation for analysis. 1 μl drops of medium and cells were spotted onto polypropylene foils held in contact with a polished copper block previously cooled in liquid nitrogen. The samples were dehydrated by freeze-drying. Micro PIXE analysis was carried out with the IBC microbeam facility using a beam of 2.5 MeV protons focused to 1-2 μm diameter. Initially no elemental contrast was observed between the cells and the medium, but by modifying the dilution of the cell suspension, the cells could be distinguished from the surrounding medium through an increased concentration of P and reduced concentration of Cl. The distribution of Na in the medium around the cells showed evidence of the action of the Na pump. Sporulation appears to be induced in the cells by adding Cu to the growth medium and the uptake of Cu by the cells could be clearly observed. This study shows that it is possible to analyse the mass transport of elements in and out of cells In the future this will enable concentration gradients to be analysed and allow the rate of production or consumption of individual cells to be calculated. By observing these patterns for individual cells (not populations) at various known points in the cell cycle, fundamental data can be derived

  10. Application of a modified culture medium for the simultaneous counting of molds and yeasts and detection of aflatoxigenic strains of Aspergillus flavus and Aspergillus parasiticus.

    Science.gov (United States)

    Jaimez, J; Fente, C A; Franco, C M; Cepeda, A; Vázquez, B I

    2003-02-01

    Molds and yeasts from 91 samples of feed and raw materials used in feed formulation were enumerated on a new culture medium to which a beta cyclodextrin (beta-W7M 1.8-cyclodextrin) had been added. This medium was compared with other media normally used in laboratories for the routine analysis of fungi, such as Sabouraud agar, malt agar supplemented with 2% dextrose, and potato dextrose agar. When a t test for paired data (0.05 significance level, 95% confidence interval) was applied, no statistically significant differences between the results obtained with the new culture medium and those obtained with the other media used to enumerate molds and yeasts were found. For the evaluation of contamination due to aflatoxin for all of the samples, Sabouraud agar and yeast extract agar, both supplemented with 0.3% beta-W7M 1.8-cyclodextrin, and APA (aflatoxin-producing ability) medium were used. Aflatoxin was detected in 21% of the feed samples and in 23% of the raw-material samples analyzed, with maximal amounts of 2.8 and 6.0 microg of aflatoxin B1 per kg, respectively, being detected. In any case, the aflatoxin contents found exceeded the legally stipulated limits. The t test for paired data (0.05 significance level, 95% confidence interval) did not show statistically significant differences between the results obtained with the different culture media used for the detection of aflatoxins. The advantage of the new medium developed (Sabouraud agar with 0.3% beta-W7M 1.8-cyclodextrin) is that it allows simultaneous fungal enumeration and determination (under UV light) of the presence of aflatoxin-producing strains without prior isolation and culture procedures involving expensive and/or complex specific media and thus saves work, time, and money.

  11. Computational modelling and analysis of the molecular network regulating sporulation initiation in Bacillus subtilis.

    Science.gov (United States)

    Ihekwaba, Adaoha E C; Mura, Ivan; Barker, Gary C

    2014-10-24

    Bacterial spores are important contaminants in food, and the spore forming bacteria are often implicated in food safety and food quality considerations. Spore formation is a complex developmental process involving the expression of more than 500 genes over the course of 6 to 8 hrs. The process culminates in the formation of resting cells capable of resisting environmental extremes and remaining dormant for long periods of time, germinating when conditions promote further vegetative growth. Experimental observations of sporulation and germination are problematic and time consuming so that reliable models are an invaluable asset in terms of prediction and risk assessment. In this report we develop a model which assists in the interpretation of sporulation dynamics. This paper defines and analyses a mathematical model for the network regulating Bacillus subtilis sporulation initiation, from sensing of sporulation signals down to the activation of the early genes under control of the master regulator Spo0A. Our model summarises and extends other published modelling studies, by allowing the user to execute sporulation initiation in a scenario where Isopropyl β-D-1-thiogalactopyranoside (IPTG) is used as an artificial sporulation initiator as well as in modelling the induction of sporulation in wild-type cells. The analysis of the model results and the comparison with experimental data indicate that the model is good at predicting inducible responses to sporulation signals. However, the model is unable to reproduce experimentally observed accumulation of phosphorelay sporulation proteins in wild type B. subtilis. This model also highlights that the phosphorelay sub-component, which relays the signals detected by the sensor kinases to the master regulator Spo0A, is crucial in determining the response dynamics of the system. We show that there is a complex connectivity between the phosphorelay features and the master regulatory Spo0A. Additional we discovered that the

  12. Effect of medium components and culture conditions in Bacillus subtilis EA-CB0575 spore production.

    Science.gov (United States)

    Posada-Uribe, Luisa F; Romero-Tabarez, Magally; Villegas-Escobar, Valeska

    2015-10-01

    Bacillus subtilis spores have important biotechnological applications; however, achieving both, high spore cell densities and sporulation efficiencies in fermentation, is poorly reported. In this study, medium components and culture conditions were optimized with different statistical methods to increase spore production of the plant growth promoting rhizobacteria B. subtilis EA-CB0575. Key medium components were determined with Plackett-Burman (PB) design, and the optimum concentration levels of two components (glucose, MgSO4·7H2O) were optimized with a full factorial and central composite design, achieving 1.37 × 10(9) CFU/mL of spore cell density and 93.5 % of sporulation efficiency in shake flask. The optimized medium was used to determine the effect of culture conditions on spore production at bioreactor level, finding that maintaining pH control did not affect significantly spore production, while the interaction of agitation and aeration rates had a significant effect on spore cell density. The overall optimization generated a 17.2-fold increase in spore cell density (8.78 × 10(9) CFU/mL) and 1.9-fold increase in sporulation efficiency (94.2 %) compared to that of PB design. These results indicate the potential of B. subtilis EA-CB0575 to produce both, high spore cell densities and sporulation efficiencies, with very low nutrient requirements and short incubation period which can represent savings of process production.

  13. Constitutive expression of ftsZ overrides the whi developmental genes to initiate sporulation of Streptomyces coelicolor.

    Science.gov (United States)

    Willemse, Joost; Mommaas, A Mieke; van Wezel, Gilles P

    2012-03-01

    The filamentous soil bacteria Streptomyces undergo a highly complex developmental programme. Before streptomycetes commit themselves to sporulation, distinct morphological checkpoints are passed in the aerial hyphae that are subject to multi-level control by the whi sporulation genes. Here we show that whi-independent expression of FtsZ restores sporulation to the early sporulation mutants whiA, whiB, whiG, whiH, whiI and whiJ. Viability, stress resistance and high-resolution electron microscopy underlined that viable spores were formed. However, spores from sporulation-restored whiA and whiG mutants showed defects in DNA segregation/condensation, while spores from the complemented whiB mutant had increased stress sensitivity, perhaps as a result of changes in the spore sheath. In contrast to the whi mutants, normal sporulation of ssgB null mutants-which fail to properly localise FtsZ-could not be restored by enhancing FtsZ protein levels, forming spore-like bodies that lack spore walls. Our data strongly suggest that the whi genes control a decisive event towards sporulation of streptomycetes, namely the correct timing of developmental ftsZ transcription. The biological significance may be to ensure that sporulation-specific cell division will only start once sufficient aerial mycelium biomass has been generated. Our data shed new light on the longstanding question as to how whi genes control sporulation, which has intrigued scientists for four decades.

  14. Proteome analysis of Aspergillus niger: Lactate added in starch-containing medium can increase production of the mycotoxin fumonisin B2 by modifying acetyl-CoA metabolism

    DEFF Research Database (Denmark)

    Sørensen, Louise Marie; Lametsch, Rene; Andersen, Mikael Rørdam

    2009-01-01

    Background Aspergillus niger is a filamentous fungus found in the environment, on foods and feeds and is used as host for production of organic acids, enzymes and proteins. The mycotoxin fumonisin B2 was recently found to be produced by A. niger and hence very little is known about production...... and regulation of this metabolite. Proteome analysis was used with the purpose to reveal how fumonisin B2 production by A. niger is influenced by starch and lactate in the medium. Results Fumonisin B2 production by A. niger was significantly increased when lactate and starch were combined in the medium....... Production of a few other A. niger secondary metabolites was affected similarly by lactate and starch (fumonisin B4, orlandin, desmethylkotanin and pyranonigrin A), while production of others was not (ochratoxin A, ochratoxin alpha, malformin A, malformin C, kotanin, aurasperone B and tensidol B...

  15. Myb transcription factors and light regulate sporulation in the oomycete Phytophthora infestans.

    Science.gov (United States)

    Xiang, Qijun; Judelson, Howard S

    2014-01-01

    Life cycle progression in eukaryotic microbes is often influenced by environment. In the oomycete Phytophthora infestans, which causes late blight on potato and tomato, sporangia have been reported to form mostly at night. By growing P. infestans under different light regimes at constant temperature and humidity, we show that light contributes to the natural pattern of sporulation by delaying sporulation until the following dark period. However, illumination does not permanently block sporulation or strongly affect the total number of sporangia that ultimately form. Based on measurements of sporulation-induced genes such as those encoding protein kinase Pks1 and Myb transcription factors Myb2R1 and Myb2R3, it appears that most spore-associated transcripts start to rise four to eight hours before sporangia appear. Their mRNA levels oscillate with the light/dark cycle and increase with the amount of sporangia. An exception to this pattern of expression is Myb2R4, which is induced several hours before the other genes and declines after cultures start to sporulate. Transformants over-expressing Myb2R4 produce twice the number of sporangia and ten-fold higher levels of Myb2R1 mRNA than wild-type, and chromatin immunoprecipitation showed that Myb2R4 binds the Myb2R1 promoter in vivo. Myb2R4 thus appears to be an early regulator of sporulation. We attempted to silence eight Myb genes by DNA-directed RNAi, but succeeded only with Myb2R3, which resulted in suppressed sporulation. Ectopic expression studies of seven Myb genes revealed that over-expression frequently impaired vegetative growth, and in the case of Myb3R6 interfered with sporangia dormancy. We observed that the degree of silencing induced by a hairpin construct was correlated with its copy number, and ectopic expression was often unstable due to epigenetic silencing and transgene excision.

  16. Myb transcription factors and light regulate sporulation in the oomycete Phytophthora infestans.

    Directory of Open Access Journals (Sweden)

    Qijun Xiang

    Full Text Available Life cycle progression in eukaryotic microbes is often influenced by environment. In the oomycete Phytophthora infestans, which causes late blight on potato and tomato, sporangia have been reported to form mostly at night. By growing P. infestans under different light regimes at constant temperature and humidity, we show that light contributes to the natural pattern of sporulation by delaying sporulation until the following dark period. However, illumination does not permanently block sporulation or strongly affect the total number of sporangia that ultimately form. Based on measurements of sporulation-induced genes such as those encoding protein kinase Pks1 and Myb transcription factors Myb2R1 and Myb2R3, it appears that most spore-associated transcripts start to rise four to eight hours before sporangia appear. Their mRNA levels oscillate with the light/dark cycle and increase with the amount of sporangia. An exception to this pattern of expression is Myb2R4, which is induced several hours before the other genes and declines after cultures start to sporulate. Transformants over-expressing Myb2R4 produce twice the number of sporangia and ten-fold higher levels of Myb2R1 mRNA than wild-type, and chromatin immunoprecipitation showed that Myb2R4 binds the Myb2R1 promoter in vivo. Myb2R4 thus appears to be an early regulator of sporulation. We attempted to silence eight Myb genes by DNA-directed RNAi, but succeeded only with Myb2R3, which resulted in suppressed sporulation. Ectopic expression studies of seven Myb genes revealed that over-expression frequently impaired vegetative growth, and in the case of Myb3R6 interfered with sporangia dormancy. We observed that the degree of silencing induced by a hairpin construct was correlated with its copy number, and ectopic expression was often unstable due to epigenetic silencing and transgene excision.

  17. The Phosphotransfer Protein CD1492 Represses Sporulation Initiation in Clostridium difficile.

    Science.gov (United States)

    Childress, Kevin O; Edwards, Adrianne N; Nawrocki, Kathryn L; Anderson, Sarah E; Woods, Emily C; McBride, Shonna M

    2016-12-01

    The formation of spores is critical for the survival of Clostridium difficile outside the host gastrointestinal tract. Persistence of C. difficile spores greatly contributes to the spread of C. difficile infection (CDI), and the resistance of spores to antimicrobials facilitates the relapse of infection. Despite the importance of sporulation to C. difficile pathogenesis, the molecular mechanisms controlling spore formation are not well understood. The initiation of sporulation is known to be regulated through activation of the conserved transcription factor Spo0A. Multiple regulators influence Spo0A activation in other species; however, many of these factors are not conserved in C. difficile and few novel factors have been identified. Here, we investigated the function of a protein, CD1492, that is annotated as a kinase and was originally proposed to promote sporulation by directly phosphorylating Spo0A. We found that deletion of CD1492 resulted in increased sporulation, indicating that CD1492 is a negative regulator of sporulation. Accordingly, we observed increased transcription of Spo0A-dependent genes in the CD1492 mutant. Deletion of CD1492 also resulted in decreased toxin production in vitro and in decreased virulence in the hamster model of CDI. Further, the CD1492 mutant demonstrated effects on gene expression that are not associated with Spo0A activation, including lower sigD and rstA transcription, suggesting that this protein interacts with factors other than Spo0A. Altogether, the data indicate that CD1492 negatively affects sporulation and positively influences motility and virulence. These results provide further evidence that C. difficile sporulation is regulated differently from that of other endospore-forming species. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

  18. CodY Promotes Sporulation and Enterotoxin Production by Clostridium perfringens Type A Strain SM101.

    Science.gov (United States)

    Li, Jihong; Freedman, John C; Evans, Daniel R; McClane, Bruce A

    2017-03-01

    Clostridium perfringens type D strains cause enterotoxemia and enteritis in livestock via epsilon toxin production. In type D strain CN3718, CodY was previously shown to increase the level of epsilon toxin production and repress sporulation. C. perfringens type A strains producing C. perfringens enterotoxin (CPE) cause human food poisoning and antibiotic-associated diarrhea. Sporulation is critical for C. perfringens type A food poisoning since spores contribute to transmission and resistance in the harsh food environment and sporulation is essential for CPE production. Therefore, the current study asked whether CodY also regulates sporulation and CPE production in SM101, a derivative of C. perfringens type A food-poisoning strain NCTC8798. An isogenic codY -null mutant of SM101 showed decreased levels of spore formation, along with lower levels of CPE production. A complemented strain recovered wild-type levels of both sporulation and CPE production. When this result was coupled with the earlier results obtained with CN3718, it became apparent that CodY regulation of sporulation varies among different C. perfringens strains. Results from quantitative reverse transcriptase PCR analysis clearly demonstrated that, during sporulation, codY transcript levels remained high in SM101 but rapidly declined in CN3718. In addition, abrB gene expression patterns varied significantly between codY -null mutants of SM101 and CN3718. Compared to the levels in their wild-type parents, the level of abrB gene expression decreased in the CN3718 codY -null mutant strain but significantly increased in the SM101 codY -null mutant strain, demonstrating CodY-dependent regulation differences in abrB expression between these two strains. This difference appears to be important since overexpression of the abrB gene in SM101 reduced the levels of sporulation and enterotoxin production, supporting the involvement of AbrB repression in regulating C. perfringens sporulation. Copyright © 2017

  19. Stage-specific fluorescence intensity of GFP and mCherry during sporulation In Bacillus Subtilis

    Directory of Open Access Journals (Sweden)

    Bailey Kirra

    2010-11-01

    Full Text Available Abstract Background Fluorescent proteins are powerful molecular biology tools that have been used to study the subcellular dynamics of proteins within live cells for well over a decade. Two fluorescent proteins commonly used to enable dual protein labelling are GFP (green and mCherry (red. Sporulation in the Gram positive bacterium Bacillus subtilis has been studied for many years as a paradigm for understanding the molecular basis for differential gene expression. As sporulation initiates, cells undergo an asymmetric division leading to differential gene expression in the small prespore and large mother cell compartments. Use of two fluorescent protein reporters permits time resolved examination of differential gene expression either in the same compartments or between compartments. Due to the spectral properties of GFP and mCherry, they are considered an ideal combination for co-localisation and co-expression experiments. They can also be used in combination with fluorescent DNA stains such as DAPI to correlate protein localisation patterns with the developmental stage of sporulation which can be linked to well characterised changes in DNA staining patterns. Findings While observing the recruitment of the transcription machinery into the forespore of sporulating Bacillus subtilis, we noticed the occurrence of stage-specific fluorescence intensity differences between GFP and mCherry. During vegetative growth and the initial stages of sporulation, fluorescence from both GFP and mCherry fusions behaved similarly. During stage II-III of sporulation we found that mCherry fluorescence was considerably diminished, whilst GFP signals remained clearly visible. This fluorescence pattern reversed during the final stage of sporulation with strong mCherry and low GFP fluorescence. These trends were observed in reciprocal tagging experiments indicating a direct effect of sporulation on fluorescent protein fluorophores. Conclusions Great care should be taken

  20. Proteome analysis of Aspergillus niger: Lactate added in starch-containing medium can increase production of the mycotoxin fumonisin B2 by modifying acetyl-CoA metabolism

    DEFF Research Database (Denmark)

    Sørensen, Louise Marie; Lametsch, Rene; Andersen, Mikael Rørdam

    2009-01-01

    containing nitrate and starch can increase fumonisin B2 production by A. niger as well as production of some other secondary metabolites. Changes in the balance of intracellular metabolites towards a higher level of carbon passing through acetyl-CoA and a high capacity to regenerate NADPH during growth...... on medium with starch and lactate were found to be the likely cause of this effect. The results lead to the hypothesis that fumonisin production by A. niger is regulated by acetyl-CoA....

  1. Modelling the sporulation of some fungi associated with cheese, at different temperature and water activity regimes.

    Science.gov (United States)

    Camardo Leggieri, Marco; Decontardi, Simone; Battilani, Paola

    2018-08-02

    The objectives of this study were to determine, in-vitro, the influence of temperature (T; 10-30 °C, step 5°), water activity (a w , 0.83-0.99; step 0.04) and time on sporulation (SPO) of some cheese-related fungi belonging to Penicillium spp. and A. versicolor. Overall, sporulation started rapidly (8 h in optimal conditions); it was significantly influenced by T and a w and the fungi studied were clearly distinguished based on their thermo-hydro adaptation. Boundary conditions for sporulation were defined for all the fungi considered and the sporulation rate was successfully modelled, especially based on T and time regimes. Penicillium crustosum, P. nordicum and P. verrucosum showed optimum for SPO at T between 20 and 25 °C and their sporulation continued up to a w  = 0.87 (a w  = 0.83 for P. nordicum). They resulted the fungi best adapted to the environmental conditions of ripening grana cheese storehouses; therefore, it is expected they dominate on the grana cheese surface. Studies on cheese are necessary to validate these results obtained on artificial media and without fungi co-occurrence. Copyright © 2018 Elsevier B.V. All rights reserved.

  2. Morphogenic Protein RodZ Interacts with Sporulation Specific SpoIIE in Bacillus subtilis.

    Science.gov (United States)

    Muchová, Katarína; Chromiková, Zuzana; Bradshaw, Niels; Wilkinson, Anthony J; Barák, Imrich

    2016-01-01

    The first landmark in sporulation of Bacillus subtilis is the formation of an asymmetric septum followed by selective activation of the transcription factor σF in the resulting smaller cell. How the morphological transformations that occur during sporulation are coupled to cell-specific activation of transcription is largely unknown. The membrane protein SpoIIE is a constituent of the asymmetric sporulation septum and is a crucial determinant of σF activation. Here we report that the morphogenic protein, RodZ, which is essential for cell shape determination, is additionally required for asymmetric septum formation and sporulation. In cells depleted of RodZ, formation of asymmetric septa is disturbed and σF activation is perturbed. During sporulation, we found that SpoIIE recruits RodZ to the asymmetric septum. Moreover, we detected a direct interaction between SpoIIE and RodZ in vitro and in vivo, indicating that SpoIIE-RodZ may form a complex to coordinate asymmetric septum formation and σF activation. We propose that RodZ could provide a link between the cell shape machinery and the coordinated morphological and developmental transitions required to form a resistant spore.

  3. A novel regulator controls Clostridium difficile sporulation, motility and toxin production.

    Science.gov (United States)

    Edwards, Adrianne N; Tamayo, Rita; McBride, Shonna M

    2016-06-01

    Clostridium difficile is an anaerobic pathogen that forms spores which promote survival in the environment and transmission to new hosts. The regulatory pathways by which C. difficile initiates spore formation are poorly understood. We identified two factors with limited similarity to the Rap sporulation proteins of other spore-forming bacteria. In this study, we show that disruption of the gene CD3668 reduces sporulation and increases toxin production and motility. This mutant was more virulent and exhibited increased toxin gene expression in the hamster model of infection. Based on these phenotypes, we have renamed this locus rstA, for regulator of sporulation and toxins. Our data demonstrate that RstA is a bifunctional protein that upregulates sporulation through an unidentified pathway and represses motility and toxin production by influencing sigD transcription. Conserved RstA orthologs are present in other pathogenic and industrial Clostridium species and may represent a key regulatory protein controlling clostridial sporulation. © 2016 John Wiley & Sons Ltd.

  4. In vitro activity of natural and chemical products on sporulation of Eimeria species oocysts of chickens.

    Science.gov (United States)

    Gadelhaq, Sahar M; Arafa, Waleed M; Abolhadid, Shawky M

    2018-02-15

    This study was designed to investigate the ability of two herbal extracts and different chemical substances to inhibit or disrupt sporulation of Eimeria species oocysts of the chickens. The two herbal extracts were Allium sativum (garlic) and Moringa olifiera while the chemical substances included commercial disinfectants and diclazuril. Field isolates of Eimeria oocysts were propagated in chickens to obtain a continuous source of oocysts. The collected unsporulated oocysts (10 5 oocysts/5 ml) were dispensed into 5 cm Petri dish. Three replicates were used for each treatment. The treated oocysts were incubated for 48 h at 25-29 °C and 80% relative humidity. The results showed that herbal extracts, the commercial recommended dose of Dettol, TH4, Phenol, Virkon ® S, and Diclazuril 20% have no effect on the sporulation. While Sodium hypochlorite showed a significant degree of sporulation inhibition reached to 49.67%. Moreover, 70% ethanol, and 10% formalin showed 100% sporulation inhibition. It was concluded that 70% ethanol and 10% formalin are the most effective methods to inhibit Eimeria species sporulation. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Sporulation properties and antimicrobial susceptibility in endemic and rare Clostridium difficile PCR ribotypes.

    Science.gov (United States)

    Zidaric, Valerija; Rupnik, Maja

    2016-06-01

    Increased sporulation and antibiotic resistance have been proposed to be associated with certain Clostridium difficile epidemic strains such as PCR ribotype 027. In this study we examined these properties in another widespread PCR ribotype, 014/020, in comparison to prevalent PCR ribotype 002 and a group of rarely represented PCR ribotypes. Highest sporulation was observed in 014/020 strains at 24 h, while after 72 h PCR ribotype 002 and rare PCR ribotypes formed higher total number of spores. PCR ribotype 014/020 strains exhibited slightly higher resistance to tested antimicrobials, followed by group of rare PCR ribotypes and less common PCR ribotype 002. Neither sporulation properties nor antibiotic resistance clearly differed in endemic and rare strains. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. Sporulation of Bacillus spp. within biofilms: a potential source of contamination in food processing environments.

    Science.gov (United States)

    Faille, C; Bénézech, T; Midelet-Bourdin, G; Lequette, Y; Clarisse, M; Ronse, G; Ronse, A; Slomianny, C

    2014-06-01

    Bacillus strains are often isolated from biofilms in the food industries. Previous works have demonstrated that sporulation could occur in biofilms, suggesting that biofilms would be a significant source of food contamination with spores. In this study, we investigated the properties of mono-species and mixed Bacillus biofilms and the ability of Bacillus strains to sporulate inside biofilms. Bacillus strains were able to form mono-species biofilms on stainless steel coupons, with up to 90% spores after a 48 h-incubation. These spores were highly resistant to cleaning but were easily transferred to agar, mimicking the cross-contamination of food, thereby suggesting that biofilms would be of particular concern due to a potential for Bacillus spore food contamination. This hypothesis was strengthened by the fact that Bacillus strains were able to form mixed biofilms with resident strains and that sporulation still occurred easily in these complex structures. Copyright © 2014 Elsevier Ltd. All rights reserved.

  7. Increased sporulation of vesicular-arbuscular mycorrhizal fungi by manipulation of nutrient regimens.

    Science.gov (United States)

    Douds, D D; Schenck, N C

    1990-02-01

    Adjustment of pot culture nutrient solutions increased root colonization and sporulation of vesicular-arbuscular mycorrhizal (VAM) fungi. Paspalum notatum Flugge and VAM fungi were grown in a sandy soil low in N and available P. Hoagland nutrient solution without P enhanced sporulation in soil and root colonization of Acaulospora longula, Scutellospora heterogama, Gigaspora margarita, and a wide range of other VAM fungi over levels produced by a tap water control or nutrient solutions containing P. However, Glomus intraradices produced significantly more spores in plant roots in the tap water control treatment. The effect of the nutrient solutions was not due solely to N nutrition, because the addition of NH(4)NO(3) decreased both colonization and sporulation by G. margarita relative to levels produced by Hoagland solution without P.

  8. Poly(3-hydroxybutyrate) fuels the tricarboxylic acid cycle and de novo lipid biosynthesis during Bacillus anthracis sporulation.

    Science.gov (United States)

    Sadykov, Marat R; Ahn, Jong-Sam; Widhelm, Todd J; Eckrich, Valerie M; Endres, Jennifer L; Driks, Adam; Rutkowski, Gregory E; Wingerd, Kevin L; Bayles, Kenneth W

    2017-06-01

    Numerous bacteria accumulate poly(3-hydroxybutyrate) (PHB) as an intracellular reservoir of carbon and energy in response to imbalanced nutritional conditions. In Bacillus spp., where PHB biosynthesis precedes the formation of the dormant cell type called the spore (sporulation), the direct link between PHB accumulation and efficiency of sporulation was observed in multiple studies. Although the idea of PHB as an intracellular carbon and energy source fueling sporulation was proposed several decades ago, the mechanisms underlying PHB contribution to sporulation have not been defined. Here, we demonstrate that PHB deficiency impairs Bacillus anthracis sporulation through diminishing the energy status of the cells and by reducing carbon flux into the tricarboxylic acid (TCA) cycle and de novo lipid biosynthesis. Consequently, this metabolic imbalance decreased biosynthesis of the critical components required for spore integrity and resistance, such as dipicolinic acid (DPA) and the spore's inner membrane. Supplementation of the PHB deficient mutant with exogenous fatty acids overcame these sporulation defects, highlighting the importance of the TCA cycle and lipid biosynthesis during sporulation. Combined, the results of this work reveal the molecular mechanisms of PHB contribution to B. anthracis sporulation and provide valuable insight into the metabolic requirements for this developmental process in Bacillus species. © 2017 John Wiley & Sons Ltd.

  9. The sporulation of the green alga Ulva prolifera is controlled by changes in photosynthetic electron transport chain.

    Science.gov (United States)

    Wang, Hui; Lin, Apeng; Gu, Wenhui; Huan, Li; Gao, Shan; Wang, Guangce

    2016-04-22

    Sporulation and spore release are essential phases of the life cycle in algae and land plants. Ulva prolifera, which is an ideal organism for studying sporulation and spore release, was used as the experimental material in the present study. The determination of photosynthetic parameters, combined with microscopic observation, treatment with photosynthetic inhibitors, limitation of carbon acquisition, and protein mass spectrometry, was employed in this experiment. Cycle electron transport (CEF) was found enhanced at the onset of sporangia formation. The inhibition effect of dibromothymoquinone (DBMIB) towards sporulation was always strong during the sporulation process whereas the inhibition effect of 3-(3',4'-dichlorophenyl)-1,1-dimethylurea (DCMU) was continuously declined accompanied with the progress of sporulation. The changes of photosynthesis resulted from the limitation of CO2 acquisition could stimulate sporulation onset. Quantitative protein analysis showed that enzymes involved in carbon fixation, including RUBISCO and pyruvate orthophosphate dikinase, declined during sporogenesis, while proteins involved in sporulation, including tubulin and centrin, increased. These results suggest that enhanced cyclic electron flow (CEF) and oxidation of the plastoquinone pool are essential for sporangia formation onset, and changes in photosynthetic electron transport chain have significant impacts on sporulation of the green algae.

  10. Particle-size distribution modified effective medium theory and validation by magneto-dielectric Co-Ti substituted BaM ferrite composites

    Science.gov (United States)

    Li, Qifan; Chen, Yajie; Harris, Vincent G.

    2018-05-01

    This letter reports an extended effective medium theory (EMT) including particle-size distribution functions to maximize the magnetic properties of magneto-dielectric composites. It is experimentally verified by Co-Ti substituted barium ferrite (BaCoxTixFe12-2xO19)/wax composites with specifically designed particle-size distributions. In the form of an integral equation, the extended EMT formula essentially takes the size-dependent parameters of magnetic particle fillers into account. It predicts the effective permeability of magneto-dielectric composites with various particle-size distributions, indicating an optimal distribution for a population of magnetic particles. The improvement of the optimized effective permeability is significant concerning magnetic particles whose properties are strongly size dependent.

  11. Temperature effect on the electrode kinetics of ethanol oxidation on Pd modified Pt electrodes and the estimation of intermediates formed in alkali medium

    International Nuclear Information System (INIS)

    Mahapatra, S.S.; Dutta, A.; Datta, J.

    2010-01-01

    Ethanol has been recognized as the ideal fuel for direct alcohol fuel cell (DAFC) systems due to its high energy density, non-toxicity and its bio-generation. However the complete conversion of ethanol to CO 2 is still met with challenges, due to dearth of suitable catalysts for the electro-oxidation. In the present work the effect of temperature on the catalytic oxidation of ethanol in alkaline medium over electrodeposited Pt and Pt-Pd alloyed nano particles on carbon support and also on the product formation during the course of reaction have been studied within the temperature range of 20-80 o C. The information on surface morphology, structural characteristics and bulk composition of the catalyst was obtained using SEM, XRD and EDX. BET surface area and pore widths of the catalyst particles were calculated by applying the BET equation to the adsorption isotherms. The electrochemical techniques like cyclic voltammetry, chronoamperometry and impedance spectroscopy were employed to investigate the electrochemical parameters related to electro-oxidation of ethanol in alkaline pH on the catalyst surfaces under the influence of temperature. The results show that the oxidation kinetics of ethanol on the alloyed Pt-Pd/C catalysts is significantly improved compared to that on Pt alone. The observations were interpreted in terms of the synergistic effect of higher electrochemical surface area, preferred OH - adsorption on the surface and the ad-atom contribution of the alloyed matrix. A pronounced influence of temperature on the reaction kinetics was manifested in the diminution of charge transfer resistance and activation energy of the ethanol oxidation with Pd incorporation into the Pt matrix, ensuring greater tolerance of the alloyed catalyst towards ethanolic residues. The higher yield of the reaction products like acetate and CO 3 -2 on the alloyed catalyst compared to Pt alone in alkaline medium, as estimated by ion chromatography, further substantiates the

  12. Developmental changes in translatable RNA species and protein synthesis during sporulation in the aquatic fungus Blastocladiella emersonii

    International Nuclear Information System (INIS)

    Silva, A.M. da; Costa Maia, J.C. da; Juliani, M.H.

    1986-01-01

    Protein synthesis during sporulation in Blastocladiella emersonii is developmentally regulated as revealed using ( 35 S)methionine pulse labeling and two-dimensional gel electrophoresis. A large increase in the synthesis of several proteins is associated with particular stages. A large number of basic proteins are synthesized exclusively during late sporulation. Changes in translatable mRNA species were also detected by two-dimensional gel electrophoresis of the polypeptides produced in a cell-free rabbit reticulocyte lysate primed with RNA prepared at different stages of sporulation. The synthesis of several proteins during sporulation seems to be transcriptionally controlled. Most of the sporulation-specific messages are not present in the mature zoospores. (Author)

  13. Growth and sporulation of Bacillus subtilis under microgravity (7-IML-1)

    Science.gov (United States)

    Mennigmann, Horst-Dieter

    1992-01-01

    The experiment was aimed at measuring the growth and sporulation of Bacillus subtilis under microgravity. The hardware for the experiment consists of a culture chamber (15 ml) made from titanium and closed by a membrane permeable for gases but not for water. Two variants of this basic structure were built which fit into the standard Biorack container types 1 and 2 respectively. Growth of the bacteria will be monitored by continuously measuring the optical density with a built-in miniaturized photometer. Other parameters (viability, sporulation, fine structure, size distribution of cells and spores, growth kinetics, etc.) will be measured on the fixed samples and on those where metabolism was temporarily halted, respectively.

  14. Influence of the Oil Pequi in the Growth Mycelial and Sporulation of Colletotrichum Musae and Growth Micelial Of Rhizopus sp. in vitro.

    Directory of Open Access Journals (Sweden)

    B. L. Mendes

    2013-07-01

    Full Text Available Abstract: The anthracnose caused by Colletotrichum musae and soft rot caused by Rhizopus sp are post-harvest diseases that influenced quality of exported fruits. To control these diseases fungicides are used, but in light of these waste products in the fruit and the environment, alternative control methods such as using biofungicides have been studied. The objective of this study was to evaluate the effect of pequi oil on mycelia growth and sporulation of Colletotrichum musae and mycelia growth of Rhizopus sp. in vitro. The oil was added in aliquots of 5, 10, 15, 20, 25, and 50L in the center of Petri dishes containing approximately 15mL of Potato-Dextrose-ar (PDA and distributed over the surface of the medium with Drigalskys handle. After 24 hours, a disc of 8mm diameter from mycelium of fungi was peaked to the center of the plates. As a control, were used Petri dishes containing only PDA. Five replicates were used for each aliquot. After analysis, it was concluded that the pequi oil is ineffective for controlling these pathogens because induced mycelium growth and sporulation.Key Words: Phytopathogens, alternative control, anthracnose, soft rot

  15. Temperature effect on the electrode kinetics of ethanol oxidation on Pd modified Pt electrodes and the estimation of intermediates formed in alkali medium

    Energy Technology Data Exchange (ETDEWEB)

    Mahapatra, S.S.; Dutta, A. [Department of Chemistry, Bengal Engineering and Science University, PO-B. Garden, Shibpur, Howrah 711 103, West Bengal (India); Datta, J., E-mail: jayati_datta@rediffmail.co [Department of Chemistry, Bengal Engineering and Science University, PO-B. Garden, Shibpur, Howrah 711 103, West Bengal (India)

    2010-12-01

    Ethanol has been recognized as the ideal fuel for direct alcohol fuel cell (DAFC) systems due to its high energy density, non-toxicity and its bio-generation. However the complete conversion of ethanol to CO{sub 2} is still met with challenges, due to dearth of suitable catalysts for the electro-oxidation. In the present work the effect of temperature on the catalytic oxidation of ethanol in alkaline medium over electrodeposited Pt and Pt-Pd alloyed nano particles on carbon support and also on the product formation during the course of reaction have been studied within the temperature range of 20-80 {sup o}C. The information on surface morphology, structural characteristics and bulk composition of the catalyst was obtained using SEM, XRD and EDX. BET surface area and pore widths of the catalyst particles were calculated by applying the BET equation to the adsorption isotherms. The electrochemical techniques like cyclic voltammetry, chronoamperometry and impedance spectroscopy were employed to investigate the electrochemical parameters related to electro-oxidation of ethanol in alkaline pH on the catalyst surfaces under the influence of temperature. The results show that the oxidation kinetics of ethanol on the alloyed Pt-Pd/C catalysts is significantly improved compared to that on Pt alone. The observations were interpreted in terms of the synergistic effect of higher electrochemical surface area, preferred OH{sup -} adsorption on the surface and the ad-atom contribution of the alloyed matrix. A pronounced influence of temperature on the reaction kinetics was manifested in the diminution of charge transfer resistance and activation energy of the ethanol oxidation with Pd incorporation into the Pt matrix, ensuring greater tolerance of the alloyed catalyst towards ethanolic residues. The higher yield of the reaction products like acetate and CO{sub 3}{sup -2} on the alloyed catalyst compared to Pt alone in alkaline medium, as estimated by ion chromatography, further

  16. A Dual Role for the Bacillus anthracis Master Virulence Regulator AtxA: Control of Sporulation and Anthrax Toxin Production.

    Science.gov (United States)

    Dale, Jennifer L; Raynor, Malik J; Ty, Maureen C; Hadjifrangiskou, Maria; Koehler, Theresa M

    2018-01-01

    Bacillus anthracis is an endemic soil bacterium that exhibits two different lifestyles. In the soil environment, B. anthracis undergoes a cycle of saprophytic growth, sporulation, and germination. In mammalian hosts, the pathogenic lifestyle of B. anthracis is spore germination followed by vegetative cell replication, but cells do not sporulate. During infection, and in specific culture conditions, transcription of the structural genes for the anthrax toxin proteins and the biosynthetic operon for capsule synthesis is positively controlled by the regulatory protein AtxA. A critical role for the atxA gene in B. anthracis virulence has been established. Here we report an inverse relationship between toxin production and sporulation that is linked to AtxA levels. During culture in conditions favoring sporulation, B. anthracis produces little to no AtxA. When B. anthracis is cultured in conditions favoring toxin gene expression, AtxA is expressed at relatively high levels and sporulation rate and efficiency are reduced. We found that a mutation within the atxA promoter region resulting in AtxA over-expression leads to a marked sporulation defect. The sporulation phenotype of the mutant is dependent upon pXO2-0075 , an atxA -regulated open reading frame located on virulence plasmid pXO2. The predicted amino acid sequence of the pXO2-0075 protein has similarity to the sensor domain of sporulation sensor histidine kinases. It was shown previously that pXO2-0075 overexpression suppresses sporulation. We have designated pXO2-0075 " skiA " for "sporulation kinase inhibitor." Our results indicate that in addition to serving as a positive regulator of virulence gene expression, AtxA modulates B. anthracis development.

  17. High content of pyridinic- and pyrrolic-nitrogen-modified carbon nanotubes derived from blood biomass for the electrocatalysis of oxygen reduction reaction in alkaline medium

    International Nuclear Information System (INIS)

    Zheng, Jie; Guo, Chaozhong; Chen, Chunyan; Fan, Mingzhi; Gong, Jianping; Zhang, Yanfang; Zhao, Tianxin; Sun, Yuelin; Xu, Xiaofan; Li, Mengmeng; Wang, Ran; Luo, Zhongli; Chen, Changguo

    2015-01-01

    Graphical abstract: Display Omitted -- Highlights: •An ORR electrocatalyst was fabricated from blood biomass and carbon nanotube. •The N-CNT catalyst exhibits good ORR activity, methanol resistance and stability. •The pyrolysis process produces high contents of pyridinic and pyrrolic N species. •The pyridinic-N group may play more important role in the active sites for ORR. -- Abstract: Here we present a facile synthetic route to design nitrogen-doped nanostructured carbon-based electrocatalyst for oxygen reduction reaction (ORR) by the copyrolysis of blood biomass from pig and carbon nanotubes (CNTs) at high temperatures. The nitrogen-doped CNTs obtained at 800 °C not only results in excellent ORR activity with four-electron transfer selectivity in alkaline medium, but also exhibits superior methanol-tolerant property and long-term stability. It is confirmed that high-temperature pyrolysis processes can facilitate to produce higher contents of pyridinic- and pyrrolic-N binding groups in electrocatalysts, contributing to the enhancement of ORR performance in terms of onset potential, half-wave potential, and limited current density. We also propose that the planar-N configuration may be the active site that is responsible for the improved ORR electrocatalytic performance. The straight-forward and cheap synthesis of the active and stable electrocatalyst makes it a promising candidate for electrochemical power sources such as fuel cells or metal-air batteries

  18. Humid Heat Autoclaving of Hybrid Nanoparticles Achieved by Decreased Nanoparticle Concentration and Improved Nanoparticle Stability Using Medium Chain Triglycerides as a Modifier.

    Science.gov (United States)

    Gou, Jingxin; Chao, Yanhui; Liang, Yuheng; Zhang, Ning; He, Haibing; Yin, Tian; Zhang, Yu; Xu, Hui; Tang, Xing

    2016-09-01

    Humid heat autoclaving is a facile technique widely used in the sterilization of injections, but the high temperature employed would destroy nanoparticles composed of biodegradable polymers. The aim of this study was to investigate whether incorporation of medium chain triglycerides (MCT) could stabilize nanoparticles composed of poly (ethylene glycol)-b-polycaprolactone (PEG-b-PCL) during autoclaving (121°C, 10 min). Polymeric nanoparticles with different MCT contents were prepared by dialysis. Block copolymer degradation was studied by GPC. The critical aggregation concentrations of nanoparticles at different temperatures were determined using pyrene fluorescence. The size, morphology and weight averaged molecular weight of pristine/autoclaved nanoparticles were studied using DLS, TEM and SLS, respectively. Drug loading content and release profile were determined using RP-HPLC. The protecting effect of MCT on nanoparticles was dependent on the amount of MCT incorporated. Nanoparticles with high MCT contents, which assumed an emulsion-like morphology, showed reduced block copolymer degradation and particle disassociation after incubation at 100°C for 24 h. Nanoparticles with high MCT content showed the lowest critical aggregation concentration (CAC) under either room temperature or 60°C and the lowest particle concentration among all samples. And the particle size, drug loading content, physical stability and release profile of nanoparticles with high MCT contents remained nearly unchanged after autoclaving. Incorporation of high amount of MCT changed the morphology of PEG-b-PCL based nanoparticles to an emulsion-like structure and the nanoparticles prepared could withstand autoclaving due to improved particle stability and decreased particle concentration caused by MCT incorporation.

  19. Short- to Medium-term Outcomes After a Modified Broström Repair for Lateral Ankle Instability With Immediate Postoperative Weightbearing.

    Science.gov (United States)

    Petrera, Massimo; Dwyer, Tim; Theodoropoulos, John S; Ogilvie-Harris, Darrell J

    2014-07-01

    Anatomic techniques of ankle ligament repair have the advantage of restoring the anatomy and kinematics of the joint. This study presents a technique for anatomic reconstruction of the lateral ligament complex by way of lateral ligament advancement using suture anchors associated with immediate protected full weightbearing; 2- to 5-year clinical outcomes are reported. This technique of providing an anatomic reconstruction with a secure fixation will enable early rehabilitation with immediate, protected weightbearing, with favorable outcomes. Case series; Level of evidence, 4. Fifty-five patients with chronic lateral ankle instability who failed nonoperative management underwent modified Broström repair (lateral ligament fibular advancement) between 2005 and 2008. The anterior talofibular ligament and calcaneofibular ligament were released from the fibula and advanced using 2 double-loaded metallic suture anchors (3.5 mm). Full weightbearing in a walking boot was allowed from the first postoperative day. Patients were assessed preoperatively and at a minimum 2-year follow-up using the Foot and Ankle Outcome Score. Complication, failure (recurrent instability), and return-to-sport rates were also recorded. Six patients (11%) were lost to follow-up, leaving a study group of 49 patients (23 men, 26 women). The mean age at the time of surgery was 25 years (range, 18-37 years), with a mean duration of symptoms of 1.8 years (range, 6 months to 5 years). The mean follow-up time was 42 months (range, 24-60 months). Significant improvement was seen in the Foot and Ankle Outcome Score from preoperatively to postoperatively (from 36 to 75.4, P ankle-related quality of life subscale from 35 to 78 (P anchor fixation is an effective procedure for the treatment of chronic lateral ankle instability and allows immediate weightbearing. © 2014 The Author(s).

  20. Virulence, sporulation, and elicitin production in three clonal lineages of Phytophthora ramorum

    Science.gov (United States)

    Phytophthora ramorum populations are clonal and consist of three lineages. Recent studies have shown that the clonal lineages may have varying degrees of aggressiveness on some host species, such as Quercus rubra. In this study, we examined virulence, sporulation and elicitin production of five P. ...

  1. Sporulation and Germination patterns - hedging a bet on long term microbial survivability in dry soil

    Science.gov (United States)

    Claes, N.; Or, D.

    2012-04-01

    Soil hosts unparalleled diversity of microbial life that is constantly challenged by the vagaries of fluctuating ambient conditions. Desiccation stresses play a key role not only by directly affecting individual bacterial cells, but also by shaping diffusion pathways and cell dispersion. The gradual thinning and fragmentation of the aqueous environment during drying have led to different survival mechanisms including dormancy and sporulation, resulting in a highly resistive state capable of surviving extreme and prolonged environmental stresses until conditions improve in the future. Our aim is to investigate how temporal changes in hydration status shape microbial communities over time, based on simple survival strategy rules for each individual bacterium. The two survival strategies considered are dormancy and sporulation. Dormancy is the state in which bacterial cells significantly reduce their metabolism with minor morphological adaptations. The required energy and time for attaining this state are low relative to sporulation costs. Sporulation involves several morphological and biochemical changes that result in a resistive capsule that endures extreme stresses over long periods of time. The working hypothesis is that different micro-ecological conditions and community compositions would result from temporal patterns and magnitude of desiccation stresses. An Individual Based Model (IBM) considering habitats on rough soil surfaces and local effects of micro-hydrological conditions on dispersion and nutrient diffusion would enable systematic study of emerging communities over extended periods. Different population compositions are expected to emerge based on low and high frequency, duration and amplitudes of wetting-drying cycles reflecting relative success or failure of survival strategy.

  2. Sporulation environment influences spore properties in Bacillus: evidence and insights on underlying molecular and physiological mechanisms.

    Science.gov (United States)

    Bressuire-Isoard, Christelle; Broussolle, Véronique; Carlin, Frédéric

    2018-05-17

    Bacterial spores are resistant to physical and chemical insults, which make them a major concern for public health and for industry. Spores help bacteria to survive extreme environmental conditions that vegetative cells cannot tolerate. Spore resistance and dormancy are important properties for applications in medicine, veterinary health, food safety, crop protection, and other domains. The resistance of bacterial spores results from a protective multilayered structure and from the unique composition of the spore core. The mechanisms of sporulation and germination, the first stage after breaking of dormancy, and organization of spore structure have been extensively studied in Bacillus species. This review aims to illustrate how far the structure, composition and properties of spores are shaped by the environmental conditions in which spores form. We look at the physiological and molecular mechanisms underpinning how sporulation media and environment deeply affect spore yield, spore properties like resistance to wet heat and physical and chemical agents, germination, and further growth. For example, spore core water content decreases as sporulation temperature increases, and resistance to wet heat increases. Controlling the fate of Bacillus spores is pivotal to controlling bacterial risks and process efficiencies in, for example, the food industry, and better control hinges on better understanding how sporulation conditions influence spore properties.

  3. Prediction of quantitative phenotypes based on genetic networks: a case study in yeast sporulation

    Directory of Open Access Journals (Sweden)

    Shen Li

    2010-09-01

    Full Text Available Abstract Background An exciting application of genetic network is to predict phenotypic consequences for environmental cues or genetic perturbations. However, de novo prediction for quantitative phenotypes based on network topology is always a challenging task. Results Using yeast sporulation as a model system, we have assembled a genetic network from literature and exploited Boolean network to predict sporulation efficiency change upon deleting individual genes. We observe that predictions based on the curated network correlate well with the experimentally measured values. In addition, computational analysis reveals the robustness and hysteresis of the yeast sporulation network and uncovers several patterns of sporulation efficiency change caused by double gene deletion. These discoveries may guide future investigation of underlying mechanisms. We have also shown that a hybridized genetic network reconstructed from both temporal microarray data and literature is able to achieve a satisfactory prediction accuracy of the same quantitative phenotypes. Conclusions This case study illustrates the value of predicting quantitative phenotypes based on genetic network and provides a generic approach.

  4. Differences in virulence and sporulation of Phytophthora kernoviae isolates originating from two distinct geographical regions

    Science.gov (United States)

    Phytophthora kernoviae has only been isolated from the United Kingdom (U.K.) and New Zealand. To understand what differences may exist between isolates from these two distinct geographical regions, virulence studies on three host plants and sporulation on host leaves were conducted on select isolat...

  5. The identification of four histidine kinases that influence sporulation in Clostridium thermocellum.

    Science.gov (United States)

    Mearls, Elizabeth B; Lynd, Lee R

    2014-08-01

    In this study, we sought to identify genes involved in the onset of spore formation in Clostridium thermocellum via targeted gene deletions, gene over-expression, and transcriptional analysis. We determined that three putative histidine kinases, clo1313_0286, clo1313_2735 and clo1313_1942 were positive regulators of sporulation, while a fourth kinase, clo1313_1973, acted as a negative regulator. Unlike Bacillus or other Clostridium species, the deletion of a single positively regulating kinase was sufficient to abolish sporulation in this organism. Sporulation could be restored in these asporogenous strains via overexpression of any one of the positive regulators, indicating a high level of redundancy between these kinases. In addition to having a sporulation defect, deletion of clo1313_2735 produced L-forms. Thus, this kinase may play an additional role in repressing L-form formation. This work suggests that C. thermocellum enters non-growth states based on the sensory input from multiple histidine kinases. The ability to control the development of non-growth states at the genetic level has the potential to inform strategies for improved strain development, as well as provide valuable insight into C. thermocellum biology. Copyright © 2014 Elsevier Ltd. All rights reserved.

  6. Microarray analysis identified Puccinia striiformis f. sp. tritici genes involved in infection and sporulation.

    Science.gov (United States)

    Puccinia striiformis f. sp. tritici (Pst) causes stripe rust, one of the most important diseases of wheat worldwide. To identify Pst genes involved in infection and sporulation, a custom oligonucleotide Genechip was made using sequences of 442 genes selected from Pst cDNA libraries. Microarray analy...

  7. Molecular Mechanisms Regulating Sporulation in the Filamentous Fungus Ashbya gossypii

    DEFF Research Database (Denmark)

    Wasserstrom, Lisa

    Sporulation is a complex developmental program that fungi enter to ensure survival in unfavorable environmental conditions. Many fungal species are able to produce spores sexually through meiosis, which is beneficial since it introduces genetic variability into a population. The sexually reproduc...

  8. Identification of new developmentally regulated genes involved in Streptomyces coelicolor sporulation.

    Science.gov (United States)

    Salerno, Paola; Persson, Jessica; Bucca, Giselda; Laing, Emma; Ausmees, Nora; Smith, Colin P; Flärdh, Klas

    2013-12-05

    The sporulation of aerial hyphae of Streptomyces coelicolor is a complex developmental process. Only a limited number of the genes involved in this intriguing morphological differentiation programme are known, including some key regulatory genes. The aim of this study was to expand our knowledge of the gene repertoire involved in S. coelicolor sporulation. We report a DNA microarray-based investigation of developmentally controlled gene expression in S. coelicolor. By comparing global transcription patterns of the wild-type parent and two mutants lacking key regulators of aerial hyphal sporulation, we found a total of 114 genes that had significantly different expression in at least one of the two mutants compared to the wild-type during sporulation. A whiA mutant showed the largest effects on gene expression, while only a few genes were specifically affected by whiH mutation. Seven new sporulation loci were investigated in more detail with respect to expression patterns and mutant phenotypes. These included SCO7449-7451 that affect spore pigment biogenesis; SCO1773-1774 that encode an L-alanine dehydrogenase and a regulator-like protein and are required for maturation of spores; SCO3857 that encodes a protein highly similar to a nosiheptide resistance regulator and affects spore maturation; and four additional loci (SCO4421, SCO4157, SCO0934, SCO1195) that show developmental regulation but no overt mutant phenotype. Furthermore, we describe a new promoter-probe vector that takes advantage of the red fluorescent protein mCherry as a reporter of cell type-specific promoter activity. Aerial hyphal sporulation in S. coelicolor is a technically challenging process for global transcriptomic investigations since it occurs only as a small fraction of the colony biomass and is not highly synchronized. Here we show that by comparing a wild-type to mutants lacking regulators that are specifically affecting processes in aerial hypha, it is possible to identify previously

  9. High-Throughput Genetic Screens Identify a Large and Diverse Collection of New Sporulation Genes in Bacillus subtilis.

    Science.gov (United States)

    Meeske, Alexander J; Rodrigues, Christopher D A; Brady, Jacqueline; Lim, Hoong Chuin; Bernhardt, Thomas G; Rudner, David Z

    2016-01-01

    The differentiation of the bacterium Bacillus subtilis into a dormant spore is among the most well-characterized developmental pathways in biology. Classical genetic screens performed over the past half century identified scores of factors involved in every step of this morphological process. More recently, transcriptional profiling uncovered additional sporulation-induced genes required for successful spore development. Here, we used transposon-sequencing (Tn-seq) to assess whether there were any sporulation genes left to be discovered. Our screen identified 133 out of the 148 genes with known sporulation defects. Surprisingly, we discovered 24 additional genes that had not been previously implicated in spore formation. To investigate their functions, we used fluorescence microscopy to survey early, middle, and late stages of differentiation of null mutants from the B. subtilis ordered knockout collection. This analysis identified mutants that are delayed in the initiation of sporulation, defective in membrane remodeling, and impaired in spore maturation. Several mutants had novel sporulation phenotypes. We performed in-depth characterization of two new factors that participate in cell-cell signaling pathways during sporulation. One (SpoIIT) functions in the activation of σE in the mother cell; the other (SpoIIIL) is required for σG activity in the forespore. Our analysis also revealed that as many as 36 sporulation-induced genes with no previously reported mutant phenotypes are required for timely spore maturation. Finally, we discovered a large set of transposon insertions that trigger premature initiation of sporulation. Our results highlight the power of Tn-seq for the discovery of new genes and novel pathways in sporulation and, combined with the recently completed null mutant collection, open the door for similar screens in other, less well-characterized processes.

  10. High-Throughput Genetic Screens Identify a Large and Diverse Collection of New Sporulation Genes in Bacillus subtilis

    Science.gov (United States)

    Brady, Jacqueline; Lim, Hoong Chuin; Bernhardt, Thomas G.; Rudner, David Z.

    2016-01-01

    The differentiation of the bacterium Bacillus subtilis into a dormant spore is among the most well-characterized developmental pathways in biology. Classical genetic screens performed over the past half century identified scores of factors involved in every step of this morphological process. More recently, transcriptional profiling uncovered additional sporulation-induced genes required for successful spore development. Here, we used transposon-sequencing (Tn-seq) to assess whether there were any sporulation genes left to be discovered. Our screen identified 133 out of the 148 genes with known sporulation defects. Surprisingly, we discovered 24 additional genes that had not been previously implicated in spore formation. To investigate their functions, we used fluorescence microscopy to survey early, middle, and late stages of differentiation of null mutants from the B. subtilis ordered knockout collection. This analysis identified mutants that are delayed in the initiation of sporulation, defective in membrane remodeling, and impaired in spore maturation. Several mutants had novel sporulation phenotypes. We performed in-depth characterization of two new factors that participate in cell–cell signaling pathways during sporulation. One (SpoIIT) functions in the activation of σE in the mother cell; the other (SpoIIIL) is required for σG activity in the forespore. Our analysis also revealed that as many as 36 sporulation-induced genes with no previously reported mutant phenotypes are required for timely spore maturation. Finally, we discovered a large set of transposon insertions that trigger premature initiation of sporulation. Our results highlight the power of Tn-seq for the discovery of new genes and novel pathways in sporulation and, combined with the recently completed null mutant collection, open the door for similar screens in other, less well-characterized processes. PMID:26735940

  11. A Mutation in the Bacillus subtilis rsbU Gene That Limits RNA Synthesis during Sporulation.

    Science.gov (United States)

    Rothstein, David M; Lazinski, David; Osburne, Marcia S; Sonenshein, Abraham L

    2017-07-15

    Mutants of Bacillis subtilis that are temperature sensitive for RNA synthesis during sporulation were isolated after selection with a 32 P suicide agent. Whole-genome sequencing revealed that two of the mutants carried an identical lesion in the rsbU gene, which encodes a phosphatase that indirectly activates SigB, the stress-responsive RNA polymerase sigma factor. The mutation appeared to cause RsbU to be hyperactive, because the mutants were more resistant than the parent strain to ethanol stress. In support of this hypothesis, pseudorevertants that regained wild-type levels of sporulation at high temperature had secondary mutations that prevented expression of the mutant rsbU gene. The properties of these RsbU mutants support the idea that activation of SigB diminishes the bacterium's ability to sporulate. IMPORTANCE Most bacterial species encode multiple RNA polymerase promoter recognition subunits (sigma factors). Each sigma factor directs RNA polymerase to different sets of genes; each gene set typically encodes proteins important for responses to specific environmental conditions, such as changes in temperature, salt concentration, and nutrient availability. A selection for mutants of Bacillus subtilis that are temperature sensitive for RNA synthesis during sporulation unexpectedly yielded strains with a point mutation in rsbU , a gene that encodes a protein that normally activates sigma factor B (SigB) under conditions of salt stress. The mutation appears to cause RsbU, and therefore SigB, to be active inappropriately, thereby inhibiting, directly or indirectly, the ability of the cells to transcribe sporulation genes. Copyright © 2017 American Society for Microbiology.

  12. Time Series Analysis of the Bacillus subtilis Sporulation Network Reveals Low Dimensional Chaotic Dynamics.

    Science.gov (United States)

    Lecca, Paola; Mura, Ivan; Re, Angela; Barker, Gary C; Ihekwaba, Adaoha E C

    2016-01-01

    Chaotic behavior refers to a behavior which, albeit irregular, is generated by an underlying deterministic process. Therefore, a chaotic behavior is potentially controllable. This possibility becomes practically amenable especially when chaos is shown to be low-dimensional, i.e., to be attributable to a small fraction of the total systems components. In this case, indeed, including the major drivers of chaos in a system into the modeling approach allows us to improve predictability of the systems dynamics. Here, we analyzed the numerical simulations of an accurate ordinary differential equation model of the gene network regulating sporulation initiation in Bacillus subtilis to explore whether the non-linearity underlying time series data is due to low-dimensional chaos. Low-dimensional chaos is expectedly common in systems with few degrees of freedom, but rare in systems with many degrees of freedom such as the B. subtilis sporulation network. The estimation of a number of indices, which reflect the chaotic nature of a system, indicates that the dynamics of this network is affected by deterministic chaos. The neat separation between the indices obtained from the time series simulated from the model and those obtained from time series generated by Gaussian white and colored noise confirmed that the B. subtilis sporulation network dynamics is affected by low dimensional chaos rather than by noise. Furthermore, our analysis identifies the principal driver of the networks chaotic dynamics to be sporulation initiation phosphotransferase B (Spo0B). We then analyzed the parameters and the phase space of the system to characterize the instability points of the network dynamics, and, in turn, to identify the ranges of values of Spo0B and of the other drivers of the chaotic dynamics, for which the whole system is highly sensitive to minimal perturbation. In summary, we described an unappreciated source of complexity in the B. subtilis sporulation network by gathering

  13. The dev Operon Regulates the Timing of Sporulation during Myxococcus xanthus Development.

    Science.gov (United States)

    Rajagopalan, Ramya; Kroos, Lee

    2017-05-15

    Myxococcus xanthus undergoes multicellular development when starved. Thousands of rod-shaped cells coordinate their movements and aggregate into mounds in which cells differentiate into spores. Mutations in the dev operon impair development. The dev operon encompasses a clustered regularly interspaced short palindromic repeat-associated (CRISPR-Cas) system. Null mutations in devI , a small gene at the beginning of the dev operon, suppress the developmental defects caused by null mutations in the downstream devR and devS genes but failed to suppress defects caused by a small in-frame deletion in devT We provide evidence that the original mutant has a second-site mutation. We show that devT null mutants exhibit developmental defects indistinguishable from devR and devS null mutants, and a null mutation in devI suppresses the defects of a devT null mutation. The similarity of DevTRS proteins to components of the CRISPR-associated complex for antiviral defense (Cascade), together with our molecular characterization of dev mutants, support a model in which DevTRS form a Cascade-like subcomplex that negatively autoregulates dev transcript accumulation and prevents DevI overproduction that would strongly inhibit sporulation. Our results also suggest that DevI transiently inhibits sporulation when regulated normally. The mechanism of transient inhibition may involve MrpC, a key transcription factor, whose translation appears to be weakly inhibited by DevI. Finally, our characterization of a devI devS mutant indicates that very little exo transcript is required for sporulation, which is surprising since Exo proteins help form the polysaccharide spore coat. IMPORTANCE CRISPR-Cas systems typically function as adaptive immune systems in bacteria. The dev CRISPR-Cas system of M. xanthus has been proposed to prevent bacteriophage infection during development, but how dev controls sporulation has been elusive. Recent evidence supported a model in which DevR and DevS prevent

  14. Role of the alpha-glucanase Agn2p in ascus-wall endolysis following sporulation in fission yeast

    NARCIS (Netherlands)

    Dekker, Nick; van Rijssel, Jos; Distel, Ben; Hochstenbach, Frans

    2007-01-01

    During sporulation in the ascomyceteous fungus Schizosaccharomyces pombe, diploid cells undergo differentiation into asci containing four haploid ascospores, which are highly resistant to environmental stresses. Although the morphogenetic processes involved in ascospore formation have been studied

  15. Sporulation of Bacillus sphaericus 2297: an electron microscope study of crystal-like inclusion biogenesis and toxicity to mosquito larvae.

    Science.gov (United States)

    Kalfon, A; Charles, J F; Bourgouin, C; de Barjac, H

    1984-04-01

    Sporulation of Bacillus sphaericus strain 2297 in a synchronous liquid culture was studied by electron microscopy. The t0 of sporulation occurred 7 h after the beginning of the lag phase. Crystal-like inclusions first appeared at t2 and reached their final size between t5 and t6. The release of the spore/inclusion complex occurred at about t15 (22 h after inoculation). Toxicity against Culex pipiens larvae was related to sporulation and appeared during the early stages of sporulation. The LC50 (24 h) decreased about 10(5)-fold between t0-2 and t7, in correlation with the formation of crystalline inclusions. Heat resistance of spores appeared later than toxicity.

  16. The kinetics of oocyst shedding and sporulation in two immunologically distinct strains of Eimeria maxima, GS and M6.

    Science.gov (United States)

    Al-Badri, Riadh; Barta, John Robert

    2012-11-01

    The kinetics of oocyst shedding and sporulation of two immunologically distinct strains of Eimeria maxima (GS and M6) were compared. Both strains had a prepatent period of approximately 120 h followed by peak oocyst shedding at 144-150 h post inoculation. Mean total oocyst output determined for each strain demonstrated that the fecundity of the M6 strain (12.8 × 10(3) ± 1.95) of E. maxima was roughly twice that of the GS strain (6.9 × 10(3) ± 3.33) when inoculated at the rate of 1,000 infective oocysts per bird. The process of oocyst sporulation was followed by repetitive sampling of sporulating oocysts at 26 °C with aeration over a 138 hour period. Sporulation was divided into five morphologically distinguishable stages whose abundance peaked at the following times during sporulation: unsporulated oocysts at 0 h; sporoblast anlagen at 18 h; sporoblasts without sporocyst walls at 22 h; and sporocysts without mature sporozoites at 38 h. The time to 50 % sporulation of E. maxima oocysts observed in the present study was approximately 53 h for both strains and all viable oocysts had completed sporulation by 60 h. In the present study, the prepatent periods, duration of oocyst shedding, and the relative kinetics of sporulation of the GS and M6 strains of E. maxima were found to be virtually identical despite the immunological distinctiveness of these two parasite strains.

  17. Sporulation of Metarhizium anisopliae var. Acridum and Beauveria bassiana on Rhammatocerus schistocercoides under humid and dry conditions

    Directory of Open Access Journals (Sweden)

    Magalhães Bonifácio Peixoto

    2000-01-01

    Full Text Available The sporulation of the fungi Metarhizium anisopliae var. acridum and Beauveria bassiana in cadavers of the grasshopper Rhammatocerus schistocercoides was studied in dry and humid environments. Both fungi were equally virulent against R. schistocercoides. However, internally, M. anisopliae produced more conidia than B. bassiana at 53% and 75% relative humidity. Externally, there was no sporulation at 53% and 75% RH, and M. anisopliae produced more conidia than B. bassiana at 100% RH.

  18. A single amino acid mutation in Spo0A results in sporulation deficiency of Paenibacillus polymyxa SC2.

    Science.gov (United States)

    Hou, Xiaoyang; Yu, Xiaoning; Du, Binghai; Liu, Kai; Yao, Liangtong; Zhang, Sicheng; Selin, C; Fernando, W G D; Wang, Chengqiang; Ding, Yanqin

    2016-01-01

    Sporulating bacteria such as Bacillus subtilis and Paenibacillus polymyxa exhibit sporulation deficiencies during their lifetime in a laboratory environment. In this study, spontaneous mutants SC2-M1 and SC2-M2, of P. polymyxa SC2 lost the ability to form endospores. A global genetic and transcriptomic analysis of wild-type SC2 and spontaneous mutants was carried out. Genome resequencing analysis revealed 14 variants in the genome of SC2-M1, including three insertions and deletions (indels), 10 single nucleotide variations (SNVs) and one intrachromosomal translocation (ITX). There were nine variants in the genome of SC2-M2, including two indels and seven SNVs. Transcriptomic analysis revealed that 266 and 272 genes showed significant differences in expression in SC2-M1 and SC2-M2, respectively, compared with the wild-type SC2. Besides sporulation-related genes, genes related to exopolysaccharide biosynthesis (eps), antibiotic (fusaricidin) synthesis, motility (flgB) and other functions were also affected in these mutants. In SC2-M2, reversion of spo0A resulted in the complete recovery of sporulation. This is the first global analysis of mutations related to sporulation deficiency in P. polymyxa. Our results demonstrate that a SNV within spo0A caused the sporulation deficiency of SC2-M2 and provide strong evidence that an arginine residue at position 211 is essential for the function of Spo0A. Copyright © 2016 The Author(s). Published by Elsevier Masson SAS.. All rights reserved.

  19. Incorporation of glycine and serine into sporulating cells of Bacillus subtilis

    International Nuclear Information System (INIS)

    Mitani, Takahiko; Kadota, Hajime

    1976-01-01

    The changes during growth and sporulation in activities of cells of Bacillus subtilis to incorporate various amino acids were investigated with wild-type strain and its asporogenous mutant. In the case of wild type strain the uptake of valine, phenylalanine, and proline was largest during the logarithmic growth period. The uptake of these amino acids decreased rapidly during the early stationary phase. The uptake of valine and cysteine increased again to some extent just prior to the forespore stage. The uptake of glycine and serine, however, was largest at the forespore stage at which the formation of spore coat took place. From these observed phenomena it was assumed that the remarkable incorporation of glycine and serine into the wild type strain during sporulation was closely related to the formation of spore coat. (auth.)

  20. Environmental factors affecting sporulation of Fuligo septica (Myxomycetes on sugar cane bagasse

    Directory of Open Access Journals (Sweden)

    Chiappeta Alda de Andrade

    2003-01-01

    Full Text Available The influence of environmental factors on sporulation of Fuligo septica (L. Wigg. and the abundance of this species on sugar cane bagasse (Saccharum officinarum L., stored outdoors was studied.In Northeastern Brazil, between January/1997 and January/1998, a total of 29 specimens were collected through monthly collections of aethalia. The relationships between the abundance of aethalia and rainfall, temperature, relative humidity of the air and insolation were studied. Results indicated that on the substrate analyzed, F. septica was an abundant species. Sporulation occurred in all seasons of the year, with a well-defined peak at the end of winter and beginning of spring (August/September,which was strongly influenced by rainfall.

  1. Two dynamin-like proteins stabilize FtsZ rings during Streptomyces sporulation.

    Science.gov (United States)

    Schlimpert, Susan; Wasserstrom, Sebastian; Chandra, Govind; Bibb, Maureen J; Findlay, Kim C; Flärdh, Klas; Buttner, Mark J

    2017-07-25

    During sporulation, the filamentous bacteria Streptomyces undergo a massive cell division event in which the synthesis of ladders of sporulation septa convert multigenomic hyphae into chains of unigenomic spores. This process requires cytokinetic Z-rings formed by the bacterial tubulin homolog FtsZ, and the stabilization of the newly formed Z-rings is crucial for completion of septum synthesis. Here we show that two dynamin-like proteins, DynA and DynB, play critical roles in this process. Dynamins are a family of large, multidomain GTPases involved in key cellular processes in eukaryotes, including vesicle trafficking and organelle division. Many bacterial genomes encode dynamin-like proteins, but the biological function of these proteins has remained largely enigmatic. Using a cell biological approach, we show that the two Streptomyces dynamins specifically localize to sporulation septa in an FtsZ-dependent manner. Moreover, dynamin mutants have a cell division defect due to the decreased stability of sporulation-specific Z-rings, as demonstrated by kymographs derived from time-lapse images of FtsZ ladder formation. This defect causes the premature disassembly of individual Z-rings, leading to the frequent abortion of septum synthesis, which in turn results in the production of long spore-like compartments with multiple chromosomes. Two-hybrid analysis revealed that the dynamins are part of the cell division machinery and that they mediate their effects on Z-ring stability during developmentally controlled cell division via a network of protein-protein interactions involving DynA, DynB, FtsZ, SepF, SepF2, and the FtsZ-positioning protein SsgB.

  2. Effect of powdered spice treatments on mycelial growth, sporulation and production of aflatoxins by toxigenic fungi

    OpenAIRE

    Chalfoun,Sára Maria; Pereira,Marcelo Cláudio; Resende,Mario Lúcio V.; Angélico,Caroline Lima; Silva,Rozane Aparecida da

    2004-01-01

    The effect of ten powdered spice plants was evaluated at the concentration of 1, 2, 3 and 4% to observe the mycelial growth and sporulation of Aspergillus niger and Eurotium repens. The spices were added to the culture media PDA and CYA20S. Clove completely inhibited the mycelial growth of the tested fungi. The other spices: cinnamon, garlic, thyme, mint, anis, oregano and onion were, in a decreasing order, promising antifungals. Bay leaf and basil did not show a pronounced fungistatic effect...

  3. Crystal Structures of the SpoIID Lytic Transglycosylases Essential for Bacterial Sporulation.

    Science.gov (United States)

    Nocadello, Salvatore; Minasov, George; Shuvalova, Ludmilla S; Dubrovska, Ievgeniia; Sabini, Elisabetta; Anderson, Wayne F

    2016-07-15

    Bacterial spores are the most resistant form of life known on Earth and represent a serious problem for (i) bioterrorism attack, (ii) horizontal transmission of microbial pathogens in the community, and (iii) persistence in patients and in a nosocomial environment. Stage II sporulation protein D (SpoIID) is a lytic transglycosylase (LT) essential for sporulation. The LT superfamily is a potential drug target because it is active in essential bacterial processes involving the peptidoglycan, which is unique to bacteria. However, the absence of structural information for the sporulation-specific LT enzymes has hindered mechanistic understanding of SpoIID. Here, we report the first crystal structures with and without ligands of the SpoIID family from two community relevant spore-forming pathogens, Bacillus anthracis and Clostridium difficile. The structures allow us to visualize the overall architecture, characterize the substrate recognition model, identify critical residues, and provide the structural basis for catalysis by this new family of enzymes. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  4. Effect of UV-C irradiation on growth, sporulation and pathogenicity of cochliobolus sativus isolates

    International Nuclear Information System (INIS)

    Jawhar, M.; Arabi, M.I.E.

    1999-12-01

    More than 30 isolates of Cochliobolus sativus, the causal agent of common root rot disease; were collected from different regions of Syria. Seven of them were exposed to UV-C light for 40 or 60 h . at a dose rate of 2.52x10 -3 W/cm 2 . A significant increases in the mycelium growth and sporulation were detected (p<0.001). Within the studied range of UV wave length, these two parameters were increased upon increasing the period of exposure to UV-C light. The pathogenicity of four isolates was evaluated after 60 h. of UV irradiation. The response to UV irradiation varied among these isolates, and resulted in an increase in their virulence level (as assessed by evaluating disease severity on sub-crown internodes). Five barley genotypes possessing different levels of resistance to C. sativus were studied. Arabi Abiad was the most susceptible cultivar whereas, Taka 76 line was moderately susceptible. It is concluded that it is possible to implement the positive effect of low doses of UV-C in stimulating the sporulation of fungi, which are difficult to sporulate on artificial media. (author)

  5. Noise in a phosphorelay drives stochastic entry into sporulation in Bacillus subtilis.

    Science.gov (United States)

    Russell, Jonathan R; Cabeen, Matthew T; Wiggins, Paul A; Paulsson, Johan; Losick, Richard

    2017-10-02

    Entry into sporulation in Bacillus subtilis is governed by a phosphorelay in which phosphoryl groups from a histidine kinase are successively transferred via relay proteins to the response regulator Spo0A. Spo0A~P, in turn, sets in motion events that lead to asymmetric division and activation of the cell-specific transcription factor σ F , a hallmark for entry into sporulation. Here, we have used a microfluidics-based platform to investigate the activation of Spo0A and σ F in individual cells held under constant, sporulation-inducing conditions. The principal conclusions were that: (i) activation of σ F occurs with an approximately constant probability after adaptation to conditions of nutrient limitation; (ii) activation of σ F is tightly correlated with, and preceded by, Spo0A~P reaching a high threshold level; (iii) activation of Spo0A takes place abruptly just prior to asymmetric division; and (iv) the primary source of noise in the activation of Spo0A is the phosphorelay. We propose that cells exhibit a constant probability of attaining a high threshold level of Spo0A~P due to fluctuations in the flux of phosphoryl groups through the phosphorelay. © 2017 The Authors.

  6. Impact of Serine/Threonine Protein Kinases on the Regulation of Sporulation in Bacillus subtilis.

    Science.gov (United States)

    Pompeo, Frédérique; Foulquier, Elodie; Galinier, Anne

    2016-01-01

    Bacteria possess many kinases that catalyze phosphorylation of proteins on diverse amino acids including arginine, cysteine, histidine, aspartate, serine, threonine, and tyrosine. These protein kinases regulate different physiological processes in response to environmental modifications. For example, in response to nutritional stresses, the Gram-positive bacterium Bacillus subtilis can differentiate into an endospore; the initiation of sporulation is controlled by the master regulator Spo0A, which is activated by phosphorylation. Spo0A phosphorylation is carried out by a multi-component phosphorelay system. These phosphorylation events on histidine and aspartate residues are labile, highly dynamic and permit a temporal control of the sporulation initiation decision. More recently, another kind of phosphorylation, more stable yet still dynamic, on serine or threonine residues, was proposed to play a role in spore maintenance and spore revival. Kinases that perform these phosphorylation events mainly belong to the Hanks family and could regulate spore dormancy and spore germination. The aim of this mini review is to focus on the regulation of sporulation in B. subtilis by these serine and threonine phosphorylation events and the kinases catalyzing them.

  7. Dominant Epistasis Between Two Quantitative Trait Loci Governing Sporulation Efficiency in Yeast Saccharomyces cerevisiae

    Science.gov (United States)

    Bergman, Juraj; Mitrikeski, Petar T.

    2015-01-01

    Summary Sporulation efficiency in the yeast Saccharomyces cerevisiae is a well-established model for studying quantitative traits. A variety of genes and nucleotides causing different sporulation efficiencies in laboratory, as well as in wild strains, has already been extensively characterised (mainly by reciprocal hemizygosity analysis and nucleotide exchange methods). We applied a different strategy in order to analyze the variation in sporulation efficiency of laboratory yeast strains. Coupling classical quantitative genetic analysis with simulations of phenotypic distributions (a method we call phenotype modelling) enabled us to obtain a detailed picture of the quantitative trait loci (QTLs) relationships underlying the phenotypic variation of this trait. Using this approach, we were able to uncover a dominant epistatic inheritance of loci governing the phenotype. Moreover, a molecular analysis of known causative quantitative trait genes and nucleotides allowed for the detection of novel alleles, potentially responsible for the observed phenotypic variation. Based on the molecular data, we hypothesise that the observed dominant epistatic relationship could be caused by the interaction of multiple quantitative trait nucleotides distributed across a 60--kb QTL region located on chromosome XIV and the RME1 locus on chromosome VII. Furthermore, we propose a model of molecular pathways which possibly underlie the phenotypic variation of this trait. PMID:27904371

  8. Dimer formation and transcription activation in the sporulation response regulator Spo0A.

    Science.gov (United States)

    Lewis, Richard J; Scott, David J; Brannigan, James A; Ladds, Joanne C; Cervin, Marguerite A; Spiegelman, George B; Hoggett, James G; Barák, Imrich; Wilkinson, Anthony J

    2002-02-15

    The response regulator Spo0A is the master control element in the initiation of sporulation in Bacillus subtilis. Like many other multi-domain response regulators, the latent activity of the effector, C-terminal domain is stimulated by phosphorylation on a conserved aspartic acid residue in the regulatory, N-terminal domain. If a threshold concentration of phosphorylated Spo0A is achieved, the transcription of genes required for sporulation is activated, whereas the genes encoding stationary phase sentinels are repressed, and sporulation proceeds. Despite detailed genetic, biochemical and structural characterisation, it is not understood how the phosphorylation signal in the receiver domain is transduced into DNA binding and transcription activation in the distal effector domain. An obstacle to our understanding of Spo0A function is the uncertainty concerning changes in quaternary structure that accompany phosphorylation. Here we have revisited this question and shown unequivocally that Spo0A forms dimers upon phosphorylation and that the subunit interactions in the dimer are mediated principally by the receiver domain. Purified dimers of two mutants of Spo0A, in which the phosphorylatable aspartic acid residue has been substituted, activate transcription from the spoIIG promoter in vitro, whereas monomers do not. This suggests that dimers represent the activated form of Spo0A. Copyright 2002 Elsevier Science Ltd.

  9. In-planta Sporulation Capacity Enhances Infectivity and Rhizospheric Competitiveness of Frankia Strains.

    Science.gov (United States)

    Cotin-Galvan, Laetitia; Pozzi, Adrien C; Schwob, Guillaume; Fournier, Pascale; Fernandez, Maria P; Herrera-Belaroussi, Aude

    2016-01-01

    Frankia Sp+ strains maintain their ability to sporulate in symbiosis with actinorhizal plants, producing abundant sporangia inside host plant cells, in contrast to Sp- strains, which are unable to perform in-planta sporulation. We herein examined the role of in-planta sporulation in Frankia infectivity and competitiveness for root infection. Fifteen strains belonging to different Sp+ and Sp- phylogenetic lineages were inoculated on seedlings of Alnus glutinosa (Ag) and A. incana (Ai). Strain competitiveness was investigated by performing Sp-/Sp+ co-inoculations. Plant inoculations were standardized using crushed nodules obtained under laboratory-controlled conditions (same plant species, age, and environmental factors). Specific oligonucleotide primers were developed to identify Frankia Sp+ and/or Sp- strains in the resulting nodules. Single inoculation experiments showed that (i) infectivity by Sp+ strains was significantly greater than that by Sp- strains, (ii) genetically divergent Sp+ strains exhibited different infective abilities, and (iii) Sp+ and Sp- strains showed different host preferences according to the origin (host species) of the inocula. Co-inoculations of Sp+ and Sp- strains revealed the greater competitiveness of Sp+ strains (98.3 to 100% of Sp+ nodules, with up to 15.6% nodules containing both Sp+ and Sp- strains). The results of the present study highlight differences in Sp+/Sp- strain ecological behaviors and provide new insights to strengthen the obligate symbiont hypothesis for Sp+ strains.

  10. Rap phosphatase of virulence plasmid pXO1 inhibits Bacillus anthracis sporulation.

    Science.gov (United States)

    Bongiorni, Cristina; Stoessel, Ricarda; Shoemaker, Dorinda; Perego, Marta

    2006-01-01

    This study shows that the Bacillus anthracis pXO1 virulence plasmid carries a Rap-Phr system, BXA0205, which regulates sporulation initiation in this organism. The BXA0205Rap protein was shown to dephosphorylate the Spo0F response regulator intermediate of the phosphorelay signal transduction system that regulates the initiation of the developmental pathway in response to environmental, metabolic, and cell cycle signals. The activity of the Rap protein was shown to be inhibited by the carboxy-terminal pentapeptide generated through an export-import processing pathway from the associated BXA0205Phr protein. Deregulation of the Rap activity by either overexpression or lack of the Phr pentapeptide resulted in severe inhibition of sporulation. Five additional Rap-Phr encoding systems were identified on the chromosome of B. anthracis, one of which, BA3790-3791, also affected sporulation initiation. The results suggest that the plasmid-borne Rap-Phr system may provide a selective advantage to the virulence of B. anthracis.

  11. Sporulation boundaries and spore formation kinetics of Bacillus spp. as a function of temperature, pH and a(w).

    Science.gov (United States)

    Baril, Eugénie; Coroller, Louis; Couvert, Olivier; El Jabri, Mohammed; Leguerinel, Ivan; Postollec, Florence; Boulais, Christophe; Carlin, Frédéric; Mafart, Pierre

    2012-10-01

    Sporulation niches in the food chain are considered as a source of hazard and are not clearly identified. Determining the sporulation environmental boundaries could contribute to identify potential sporulation niches. Spore formation was determined in a Sporulation Mineral Buffer. The effect of incubation temperature, pH and water activity on time to one spore per mL, maximum sporulation rate and final spore concentration was investigated for a Bacillus weihenstephanensis and a Bacillus licheniformis strain. Sporulation boundaries of B. weihenstephanensis and of B. licheniformis were similar to, or included within, the range of temperatures, pH and water activities supporting growth. For instance, sporulation boundaries of B. weihenstephanensis were evaluated at 5°C, 35°C, pH 5.2 and a(w) 0.960 while growth boundaries were observed at 5°C, 37°C, pH 4.9 and a(w) 0.950. Optimum spore formation was determined at 30°C pH 7.2 for B. weihenstephanensis and at 45°C pH 7.2 for B. licheniformis. Lower temperatures and pH delayed the sporulation process. For instance, the time to one spore per mL was tenfold longer when sporulation occurred at 10°C and 20°C, for each strain respectively, than at optimum sporulation temperature. The relative effect of temperature and pH on sporulation rates and on growth rates is similar. This work suggests that the influence of environmental factors on the quantitative changes in sporulation boundaries and rates was similar to their influence on changes in growth rate. Copyright © 2012 Elsevier Ltd. All rights reserved.

  12. Effect of tcdR Mutation on Sporulation in the Epidemic Clostridium difficile Strain R20291.

    Science.gov (United States)

    Girinathan, Brintha P; Monot, Marc; Boyle, Daniel; McAllister, Kathleen N; Sorg, Joseph A; Dupuy, Bruno; Govind, Revathi

    2017-01-01

    Clostridium difficile is an important nosocomial pathogen and the leading cause of hospital-acquired diarrhea. Antibiotic use is the primary risk factor for the development of C. difficile -associated disease because it disrupts normally protective gut flora and enables C. difficile to colonize the colon. C. difficile damages host tissue by secreting toxins and disseminates by forming spores. The toxin-encoding genes, tcdA and tcdB , are part of a pathogenicity locus, which also includes the tcdR gene that codes for TcdR, an alternate sigma factor that initiates transcription of tcdA and tcdB genes. We created a tcdR mutant in epidemic-type C. difficile strain R20291 in an attempt to identify the global role of tcdR . A site-directed mutation in tcdR affected both toxin production and sporulation in C. difficile R20291. Spores of the tcdR mutant were more heat sensitive than the wild type (WT). Nearly 3-fold more taurocholate was needed to germinate spores from the tcdR mutant than to germinate the spores prepared from the WT strain. Transmission electron microscopic analysis of the spores also revealed a weakly assembled exosporium on the tcdR mutant spores. Accordingly, comparative transcriptome analysis showed many differentially expressed sporulation genes in the tcdR mutant compared to the WT strain. These data suggest that regulatory networks of toxin production and sporulation in C. difficile strain R20291 a re linked with each other. IMPORTANCE C. difficile infects thousands of hospitalized patients every year, causing significant morbidity and mortality. C. difficile spores play a pivotal role in the transmission of the pathogen in the hospital environment. During infection, the spores germinate, and the vegetative bacterial cells produce toxins that damage host tissue. Thus, sporulation and toxin production are two important traits of C. difficile . In this study, we showed that a mutation in tcdR , the toxin gene regulator, affects both toxin

  13. Tolerance Induction of Temperature and Starvation with Tricalcium Phosphate on Preservation and Sporulation in Bacillus amyloliquefaciens Detected by Flow Cytometry.

    Science.gov (United States)

    Shahrokh Esfahani, Samaneh; Emtiazi, Giti; Shafiei, Rasoul; Ghorbani, Najmeh; Zarkesh Esfahani, Seyed Hamid

    2016-09-01

    The Bacillus species have many applications in the preparation of various enzymes, probiotic, biofertilizer, and biomarkers for which the survival of resting cells and spore formation under different conditions are important. In this study, water and saline along with different mineral substances such as calcium carbonate, calcium phosphate, and silica were used for the detection of survival and preservation of Bacillus amyloliquefaciens. The results showed intensive death of resting cells at 8 °C, but significant survival at 28 °C after one month. However, preservation by minerals significantly decreased the rate of death and induced sporulation at both the temperatures. The resting cells were maintained at room temperature (about 60 % of the initial population survived after a month) in the presence of tricalcium phosphate. The results showed that temperature has more effect on sporulation compare with starvation. The sporulation in normal saline at 28 °C was 70 times more than that at 8 °C; meanwhile, addition of tricalcium phosphate increases sporulation by 90 times. Also, the FTIR data showed the interaction of tricalcium phosphate with spores and resting cells. The discrimination of sporulation from non-sporulation state was performed by nucleic acid staining with thiazole orange and detected by flow cytometry. The flow cytometric studies confirmed that the rates of sporulation in pure water were significantly more at 28 °C. This is the first report on the detection of bacterial spore with thiazole orange by flow cytometry and also on the interaction of tricalcium phosphate with spores by FTIR analyses.

  14. Two-Component Signal Transduction Systems That Regulate the Temporal and Spatial Expression of Myxococcus xanthus Sporulation Genes.

    Science.gov (United States)

    Sarwar, Zaara; Garza, Anthony G

    2016-02-01

    When starved for nutrients, Myxococcus xanthus produces a biofilm that contains a mat of rod-shaped cells, known as peripheral rods, and aerial structures called fruiting bodies, which house thousands of dormant and stress-resistant spherical spores. Because rod-shaped cells differentiate into spherical, stress-resistant spores and spore differentiation occurs only in nascent fruiting bodies, many genes and multiple levels of regulation are required. Over the past 2 decades, many regulators of the temporal and spatial expression of M. xanthus sporulation genes have been uncovered. Of these sporulation gene regulators, two-component signal transduction circuits, which typically contain a histidine kinase sensor protein and a transcriptional regulator known as response regulator, are among the best characterized. In this review, we discuss prototypical two-component systems (Nla6S/Nla6 and Nla28S/Nla28) that regulate an early, preaggregation phase of sporulation gene expression during fruiting body development. We also discuss orphan response regulators (ActB and FruA) that regulate a later phase of sporulation gene expression, which begins during the aggregation stage of fruiting body development. In addition, we summarize the research on a complex two-component system (Esp) that is important for the spatial regulation of sporulation. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

  15. Effects of CO/sub 2/ and membranes on sporulation in axenic cultures of flax rust. [Melampsora lini

    Energy Technology Data Exchange (ETDEWEB)

    Boasson, R.; Shaw, M.

    1985-01-01

    Uredospore production by axenically grown flax rust (Melampsora lini (Ehrenb.) Lev.) was measured as carotenoids (extinction units at 458 nm) per milligram protein. Sporulation was not affected by raising (flushing with 1-5% (v/v) CO/sub 2/ in air) or lowering (KOH well in culture flasks) the level of CO/sub 2/ in the air space above the cultures. Significant (two- to four-fold) increases in sporulation occurred beneath impermeable membranes of parafilm or Saran wrap placed on the surface of young (3 weeks from seeding) mycelial mats for 2 weeks. The stimulatory effect was confined strictly to those areas of the mycelial mats in contact with the membranes. Both Parafilm and Saran wrap were easily and cleanly peeled away from the mycelial mats. Permeable Unipore and HVHP membranes, to which the fungus adhered strongly, did not stimulate sporulation. The fungus did not adhere to Unipore or HVHP membranes treated with silicone or paraffin oil; membranes thus treated stimulated sporulation. The stimulatory effect of membranes on sporulation appears to depend on the nature of the contact between the membrane surface and the mycelium and to be unrelated to the effect of the membranes on the diffusion of gases or other volatile substances. 11 references, 2 figures, 4 tables.

  16. [Sporulation or competence development? A genetic regulatory network model of cell-fate determination in Bacillus subtilis].

    Science.gov (United States)

    Lu, Zhenghui; Zhou, Yuling; Zhang, Xiaozhou; Zhang, Guimin

    2015-11-01

    Bacillus subtilis is a generally recognized as safe (GRAS) strain that has been widely used in industries including fodder, food, and biological control. In addition, B. subtilis expression system also plays a significant role in the production of industrial enzymes. However, its application is limited by its low sporulation frequency and transformation efficiency. Immense studies have been done on interpreting the molecular mechanisms of sporulation and competence development, whereas only few of them were focused on improving sporulation frequency and transformation efficiency of B. subtilis by genetic modification. The main challenge is that sporulation and competence development, as the two major developmental events in the stationary phase of B. subtilis, are regulated by the complicated intracellular genetic regulatory systems. In addition, mutual regulatory mechanisms also exist in these two developmental events. With the development of genetic and metabolic engineering, constructing genetic regulatory networks is currently one of the most attractive research fields, together with the genetic information of cell growth, metabolism, and development, to guide the industrial application. In this review, the mechanisms of sporulation and competence development of B. subtilis, their interactions, and the genetic regulation of cell growth were interpreted. In addition, the roles of these regulatory networks in guiding basic and applied research of B. subtilis and its related species were discussed.

  17. Neurotoxin synthesis is positively regulated by the sporulation transcription factor Spo0A in Clostridium botulinum type E.

    Science.gov (United States)

    Mascher, Gerald; Mertaoja, Anna; Korkeala, Hannu; Lindström, Miia

    2017-10-01

    Clostridium botulinum produces the most potent natural toxin, the botulinum neurotoxin (BoNT), probably to create anaerobiosis and nutrients by killing the host, and forms endospores that facilitate survival in harsh conditions and transmission. Peak BoNT production coincides with initiation of sporulation in C. botulinum cultures, which suggests common regulation. Here, we show that Spo0A, the master regulator of sporulation, positively regulates BoNT production. Insertional inactivation of spo0A in C. botulinum type E strain Beluga resulted in significantly reduced BoNT production and in abolished or highly reduced sporulation in relation to wild-type controls. Complementation with spo0A restored BoNT production and sporulation. Recombinant DNA-binding domain of Spo0A directly bound to a putative Spo0A-binding box (CTTCGAA) within the BoNT/E operon promoter, demonstrating direct regulation. Spo0A is the first neurotoxin regulator reported in C. botulinum type E. Unlike other C. botulinum strains that are terrestrial and employ the alternative sigma factor BotR in directing BoNT expression, C. botulinum type E strains are adapted to aquatic ecosystems, possess distinct epidemiology and lack BotR. Our results provide fundamental new knowledge on the genetic control of BoNT production and demonstrate common regulation of BoNT production and sporulation, providing a key intervention point for control. © 2017 Society for Applied Microbiology and John Wiley & Sons Ltd.

  18. Comparative Transcriptomic and Proteomic Analyses Reveal a FluG-Mediated Signaling Pathway Relating to Asexual Sporulation of Antrodia camphorata.

    Science.gov (United States)

    Li, Hua-Xiang; Lu, Zhen-Ming; Zhu, Qing; Gong, Jin-Song; Geng, Yan; Shi, Jin-Song; Xu, Zheng-Hong; Ma, Yan-He

    2017-09-01

    Medicinal mushroom Antrodia camphorata sporulate large numbers of arthroconidia in submerged fermentation, which is rarely reported in basidiomycetous fungi. Nevertheless, the molecular mechanisms underlying this asexual sporulation (conidiation) remain unclear. Here, we used comparative transcriptomic and proteomic approaches to elucidate possible signaling pathway relating to the asexual sporulation of A. camphorata. First, 104 differentially expressed proteins and 2586 differential cDNA sequences during the culture process of A. camphorata were identified by 2DE and RNA-seq, respectively. By applying bioinformatics analysis, a total of 67 genes which might play roles in the sporulation were obtained, and 18 of these genes, including fluG, sfgA, SfaD, flbA, flbB, flbC, flbD, nsdD, brlA, abaA, wetA, ganB, fadA, PkaA, veA, velB, vosA, and stuA might be involved in a potential FluG-mediated signaling pathway. Furthermore, the mRNA expression levels of the 18 genes in the proposed FluG-mediated signaling pathway were analyzed by quantitative real-time PCR. In summary, our study helps elucidate the molecular mechanisms underlying the asexual sporulation of A. camphorata, and provides also useful transcripts and proteome for further bioinformatics study of this valuable medicinal mushroom. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Missense Mutations Allow a Sequence-Blind Mutant of SpoIIIE to Successfully Translocate Chromosomes during Sporulation.

    Science.gov (United States)

    Bose, Baundauna; Reed, Sydney E; Besprozvannaya, Marina; Burton, Briana M

    2016-01-01

    SpoIIIE directionally pumps DNA across membranes during Bacillus subtilis sporulation and vegetative growth. The sequence-reading domain (γ domain) is required for directional DNA transport, and its deletion severely impairs sporulation. We selected suppressors of the spoIIIEΔγ sporulation defect. Unexpectedly, many suppressors were intragenic missense mutants, and some restore sporulation to near-wild-type levels. The mutant proteins are likely not more abundant, faster at translocating DNA, or sequence-sensitive, and rescue does not involve the SpoIIIE homolog SftA. Some mutants behave differently when co-expressed with spoIIIEΔγ, consistent with the idea that some, but not all, variants may form mixed oligomers. In full-length spoIIIE, these mutations do not affect sporulation, and yet the corresponding residues are rarely found in other SpoIIIE/FtsK family members. The suppressors do not rescue chromosome translocation defects during vegetative growth, indicating that the role of the γ domain cannot be fully replaced by these mutations. We present two models consistent with our findings: that the suppressors commit to transport in one arbitrarily-determined direction or delay spore development. It is surprising that missense mutations somehow rescue loss of an entire domain with a complex function, and this raises new questions about the mechanism by which SpoIIIE pumps DNA and the roles SpoIIIE plays in vivo.

  20. ISOLATION, CHARACTERIZATION MORPHOLOGICAL AND EVALUATION OF MYCELIAL GROWTH AND SPORULATION OF VARIOUS MEANS CULTURE OF Quambalaria sp.

    Directory of Open Access Journals (Sweden)

    Ediellen Mayara Corrêa Gomes

    2016-12-01

    Full Text Available The characterization of microorganisms is strategic for plant protection. The objective was to analyze the morphological characteristics and the mycelial growth and sporulation on different culture media fungus Quambalaria sp. Morphological characterization was based on color, type of colonies, type and size of spores were used taxonomic keys and specialized literature for description and identification of fungal structures. For the assessment of mycelial growth and sporulation were used means potato dextrose agar culture (PDA, vegetable-agar (V8 agar and oatmeal agar (OA. two isolates were obtained denominated Q1 and Q2 showed that different types of colonies and mycelial growth, and the spores of both characterized as hyaline, miniature format with obovoid the fusiform and its chambered hyphae. A linear relationship between sporulation and mycelial growth was observed, that is, the larger the sporulation, the greater mycelial growth. The means of V8-agar culture was the most stimulated mycelial growth and sporulation isolated Q1 and the BDA through the isolated Q2, with the MIGS of 11.07 and 10.57 mm day-1, respectively. The results of this study allow us to base the start of a study on the Quambalaria gender, in northern Brazil and to add to the few reported studies on this pathosystem. Keywords: leaf spot; eucalyptus; phytopathogen; forest pathology.

  1. Missense Mutations Allow a Sequence-Blind Mutant of SpoIIIE to Successfully Translocate Chromosomes during Sporulation.

    Directory of Open Access Journals (Sweden)

    Baundauna Bose

    Full Text Available SpoIIIE directionally pumps DNA across membranes during Bacillus subtilis sporulation and vegetative growth. The sequence-reading domain (γ domain is required for directional DNA transport, and its deletion severely impairs sporulation. We selected suppressors of the spoIIIEΔγ sporulation defect. Unexpectedly, many suppressors were intragenic missense mutants, and some restore sporulation to near-wild-type levels. The mutant proteins are likely not more abundant, faster at translocating DNA, or sequence-sensitive, and rescue does not involve the SpoIIIE homolog SftA. Some mutants behave differently when co-expressed with spoIIIEΔγ, consistent with the idea that some, but not all, variants may form mixed oligomers. In full-length spoIIIE, these mutations do not affect sporulation, and yet the corresponding residues are rarely found in other SpoIIIE/FtsK family members. The suppressors do not rescue chromosome translocation defects during vegetative growth, indicating that the role of the γ domain cannot be fully replaced by these mutations. We present two models consistent with our findings: that the suppressors commit to transport in one arbitrarily-determined direction or delay spore development. It is surprising that missense mutations somehow rescue loss of an entire domain with a complex function, and this raises new questions about the mechanism by which SpoIIIE pumps DNA and the roles SpoIIIE plays in vivo.

  2. Generation of mariner-based transposon insertion mutant library of Bacillus sphaericus 2297 and investigation of genes involved in sporulation and mosquito-larvicidal crystal protein synthesis.

    Science.gov (United States)

    Wu, Yiming; Hu, Xiaomin; Ge, Yong; Zheng, Dasheng; Yuan, Zhiming

    2012-05-01

    Bacillus sphaericus has been used with great success in mosquito control programs worldwide. Under conditions of nutrient limitation, it undergoes sporulation via a series of well defined morphological stages. However, only a small number of genes involved in sporulation have been identified. To identify genes associated with sporulation, and to understand the relationship between sporulation and crystal protein synthesis, a random mariner-based transposon insertion mutant library of B. sphaericus strain 2297 was constructed and seven sporulation-defective mutants were selected. Sequencing of the DNA flanking of the transposon insertion identified several genes involved in sporulation. The morphologies of mutants were determined by electron microscopy and synthesis of crystal proteins was analyzed by SDS-PAGE and Western blot. Four mutants blocked at early stages of sporulation failed to produce crystal proteins and had lower larvicidal activity. However, the other three mutants were blocked at later stages and were able to form crystal proteins, and the larvicidal activity was similar to wild type. These results indicated that crystal protein synthesis in B. sphaericus is dependent on sporulation initiation. © 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

  3. Post-mortem sporulation of Ceratomyxa shasta (Myxozoa) after death in adult Chinook salmon

    Science.gov (United States)

    Kent, Michael L.; Soderlund, K.; Thomann, E.; Schreck, Carl B.; Sharpton, T.J.

    2014-01-01

    Ceratomyxa shasta (Myxozoa) is a common gastrointestinal pathogen of salmonid fishes in the Pacific Northwest of the United States. We have been investigating this parasite in adult Chinook salmon (Oncorhynchus tshawytscha) in the Willamette River, Oregon. In prior work, we observed differences in the pattern of development of C. shasta in adult salmon compared to juvenile salmon. Adult salmon consistently had large numbers of prespore stages in many of the fish that survived to spawn in the fall. However, myxospores were rarely observed, even though they were exposed and presumably infected for months before spawning. We evaluated the ability of C. shasta to sporulate following fish death because it is reported that myxosores are common in carcasses of Chinook salmon. We collected the intestine from 30 adult salmon immediately after artificial spawning and death (T0). A total of 23 fish were infected with C. shasta based on histology, but only a few myxospores were observed in 1 fish by histology. Intestines of these fish were examined at T0 and T7 (latter held at 17 C for 7 days) using quantified wet mount preparations. An increase in myxospore concentrations was seen in 39% of these fish, ranging between a 1.5- to a 14.5-fold increase. The most heavily infected fish exhibited a 4.6-fold increase from 27,841 to 129,352 myxospores/cm. This indicates, supported by various statistical analyses, that under certain conditions presporogonic forms are viable and continue to sporulate after death in adult salmon. Considering the life cycle of C. shasta and anadromous salmon, the parasite may have evolved 2, non-mutually exclusive developmental strategies. In young fish (parr and smolts), the parasite sporulates shortly after infection and is released into freshwater from either live or dead fish before their migration to seawater, where the alternate host is absent. The second strategy occurs in adult salmon, particularly spring Chinook salmon, which become infected upon

  4. Modeling curvature-dependent subcellular localization of a small sporulation protein in Bacillus subtilis

    Science.gov (United States)

    Wasnik, Vaibhav; Wingreen, Ned; Mukhopadhyay, Ranjan

    2012-02-01

    Recent experiments suggest that in the bacterium, B. subtilis, the cue for the localization of small sporulation protein, SpoVM, that plays a central role in spore coat formation, is curvature of the bacterial plasma membrane. This curvature-dependent localization is puzzling given the orders of magnitude difference in lengthscale of an individual protein and radius of curvature of the membrane. Here we develop a minimal model to study the relationship between curvature-dependent membrane absorption of SpoVM and clustering of membrane-associated SpoVM and compare our results with experiments.

  5. Comparison of the pathogenicity, growth, sporulation and morphology of Pezicula alba Guthrie (Gloeosporium album Osterw.

    Directory of Open Access Journals (Sweden)

    H. Borecka

    2013-12-01

    Full Text Available Sixteen isolates of Pezicula alba Guthr. were examined. The intensity of growth on various media, pathogenicity to apple fruits and twigs, colour of cultures and size of conidia were measured. Some isolates are pathogenic to fruits, some others to twigs; one isolate (only no. 19 is pathogenic to both twigs and fruits; many isolates are not - pathogenic at all. Culture growth, sporulation and size of conidia are not correlated with the pathogenicity of the isolate. The mean size of conidia is 21.29µm x 3.48µm.

  6. Assessment of pheromone production and response in fission yeast by a halo test of induced sporulation

    DEFF Research Database (Denmark)

    Egel, R; Willer, M; Kjaerulff, S

    1994-01-01

    We describe a rapid, sensitive and semi-quantitative plate assay for monitoring pheromone activity in the fission yeast Schizosaccharomyces pombe. It is based on the observation that meiosis requires stimulation by pheromone and exploits diploid strains that will only sporulate after addition...... of exogenous pheromone. The tester strains are heterozygous for mating type, are non-switching, and are mutated in one of the early subfunctions (either mat1-Mc or mat1-Pc), so that meiosis is only induced after exposure to exogenous pheromone (M-factor or P-factor, respectively). Pheromone activity...

  7. Spore coat protein synthesis in cell-free systems from sporulating cells of Bacillus subtilis.

    Science.gov (United States)

    Nakayama, T; Munoz, L E; Sadaie, Y; Doi, R H

    1978-09-01

    Cell-free systems for protein synthesis were prepared from Bacillus subtilis 168 cells at several stages of sporulation. Immunological methods were used to determine whether spore coat protein could be synthesized in the cell-free systems prepared from sporulating cells. Spore coat protein synthesis first occurred in extracts from stage t2 cells. The proportion of spore coat protein to total proteins synthesized in the cell-free systems was 2.4 and 3.9% at stages t2 and t4, respectively. The sodium dodecyl sulfate-urea-polyacrylamide gel electrophoresis patterns of immunoprecipitates from the cell-free systems showed the complete synthesis of an apparent spore coat protein precursor (molecular weight, 25,000). A polypeptide of this weight was previously identified in studies in vivo (L.E. Munoz, Y. Sadaie, and R.H. Doi, J. Biol. Chem., in press). The synthesis in vitro of polysome-associated nascent spore coat polypeptides with varying molecular weights up to 23,000 was also detected. These results indicate that the spore coat protein may be synthesized as a precursor protein. The removal of proteases in the crude extracts by treatment with hemoglobin-Sepharose affinity techniques may be preventing the conversion of the large 25,000-dalton precursor to the 12,500-dalton mature spore coat protein.

  8. Growth and sporulation of Trichoderma polysporum on organic substrates by addition of carbon and nitrogen sources

    International Nuclear Information System (INIS)

    Rajput, A.Q.; Shahzad, S.

    2015-01-01

    During the present study nine different organic substrates viz., rice grains, sorghum grains, wheat grains, millet grains, wheat straw, rice husk, cow dung, sawdust and poultry manure were used for mass multiplication of Trichoderma polysporum. Grains, especially sorghum grains were found to be the best substrate for T. polysporum. Wheat straw and rice husk were less suitable, whereas, cow dung, sawdust and poultry manure were not suitable for growth of the fungus. Sucrose at the rate of 30,000 ppm and ammonium nitrate at the rate of 3,000 ppm were found to be the best carbon and nitrogen sources for growth and sporulation of T. polysporum. Amendment of the selected C and N sources to wheat straw, rice husk and millet grains resulted in significantly higher growth and conidia production by T. polysporum as compared to un-amended substrates. Sorghum and rice grains showed suppression in growth and sporulation of T. polysporum when amended with C and N sources. During studies on shelf life, populations of T. polysporum attained the peck at 60-135 days intervals on different substrates and declined gradually thereafter. However, even after 330 days, the populations were greater than the population at 0-day. At 345-360 days interval, populations were less than the initial populations at 0- days. Shelf life on C+N amended wheat straw and rice husk were more as compared to un-amended substrates. (author)

  9. clpC operon regulates cell architecture and sporulation in Bacillus anthracis.

    Science.gov (United States)

    Singh, Lalit K; Dhasmana, Neha; Sajid, Andaleeb; Kumar, Prasun; Bhaduri, Asani; Bharadwaj, Mitasha; Gandotra, Sheetal; Kalia, Vipin C; Das, Taposh K; Goel, Ajay K; Pomerantsev, Andrei P; Misra, Richa; Gerth, Ulf; Leppla, Stephen H; Singh, Yogendra

    2015-03-01

    The clpC operon is known to regulate several processes such as genetic competence, protein degradation and stress survival in bacteria. Here, we describe the role of clpC operon in Bacillus anthracis. We generated knockout strains of the clpC operon genes to investigate the impact of CtsR, McsA, McsB and ClpC deletion on essential processes of B. anthracis. We observed that growth, cell division, sporulation and germination were severely affected in mcsB and clpC deleted strains, while none of deletions affected toxin secretion. Growth defect in these strains was pronounced at elevated temperature. The growth pattern gets restored on complementation of mcsB and clpC in respective mutants. Electron microscopic examination revealed that mcsB and clpC deletion also causes defect in septum formation leading to cell elongation. These vegetative cell deformities were accompanied by inability of mutant strains to generate morphologically intact spores. Higher levels of polyhydroxybutyrate granules accumulation were also observed in these deletion strains, indicating a defect in sporulation process. Our results demonstrate, for the first time, the vital role played by McsB and ClpC in physiology of B. anthracis and open up further interest on this operon, which might be of importance to success of B. anthracis as pathogen. © 2014 Society for Applied Microbiology and John Wiley & Sons Ltd.

  10. Crescimento e esporulação de Bipolaris euphorbiae cultivado sob diferentes condições nutricionais Growth and sporulation of Bipolaris euphorbiae cultivated under different nutritional conditions

    Directory of Open Access Journals (Sweden)

    Mara Cristina Penariol

    2008-10-01

    , calcium phosphate, sodium phosphate, phosphoric acid, ammonium phosphate and addition of organic sources of macro and micronutrients as supplement in the culture medium for the growth and sporulation of B. euphorbiae. Starch was the carbon source that promoted the greater fungus growth and was considered the most favorable to sporulation. The nitrogen source sodium nitrate and the phosphorus source monobasic potassium phosphate and calcium phosphate provided the best growth and sporulation of B. euphorbiae, but the others phosphorus source analyzed, except phosphoric acid, favored the fungus sporulation. The supplementation of the culture medium with peptone and yeast extract promoted a better growth and sporulation of the fungus and the addition of vitamins favored the production of conidia.

  11. Sporulation and germination gene expression analysis of Bacillus anthracis Sterne spores in skim milk under heat and different intervention techniques

    Science.gov (United States)

    To investigate how B. anthracis Stene spores survive in milk under heat (80 degree C, 10 minutes), pasteurization (72 degree C, 15 seconds) and pasteurization plus microfiltration, the expression levels of genes that related to sporulation and germination were tested using real-time PCR assays. Tw...

  12. A derepression system based on the Bacillus subtilis sporulation pathway offers dynamic control of heterologous gene expression

    NARCIS (Netherlands)

    Nijland, Reindert; Veening, Jan-Willem; Kuipers, Oscar P.

    By rewiring the sporulation gene-regulatory network of Bacillus subtilis, we generated a novel expression system relying on derepression. The gene of interest is placed under the control of the abrB promoter, which is active only when Spo0A is absent, and Spo0A is controlled via an IPTG

  13. Effect of environmental conditions and lesion age on sporulation of Phytophthora ramorum on California bay laurel, rhododendron, and camellia

    Science.gov (United States)

    Steve Tjosvold; David Chambers; Sylvia Mori

    2013-01-01

    The objective of our research was to determine the environmental conditions and lesion age favorable for Phytophthora ramorum sporulation under field conditions. For 2 years, new camellia, rhododendron, and California bay laurel (Umbellaria californica (Hook. & Arn.) Nutt.) nursery stock were seasonally inoculated (every 3 months) on foliage....

  14. Computer Vision for High-Throughput Quantitative Phenotyping: A Case Study of Grapevine Downy Mildew Sporulation and Leaf Trichomes.

    Science.gov (United States)

    Divilov, Konstantin; Wiesner-Hanks, Tyr; Barba, Paola; Cadle-Davidson, Lance; Reisch, Bruce I

    2017-12-01

    Quantitative phenotyping of downy mildew sporulation is frequently used in plant breeding and genetic studies, as well as in studies focused on pathogen biology such as chemical efficacy trials. In these scenarios, phenotyping a large number of genotypes or treatments can be advantageous but is often limited by time and cost. We present a novel computational pipeline dedicated to estimating the percent area of downy mildew sporulation from images of inoculated grapevine leaf discs in a manner that is time and cost efficient. The pipeline was tested on images from leaf disc assay experiments involving two F 1 grapevine families, one that had glabrous leaves (Vitis rupestris B38 × 'Horizon' [RH]) and another that had leaf trichomes (Horizon × V. cinerea B9 [HC]). Correlations between computer vision and manual visual ratings reached 0.89 in the RH family and 0.43 in the HC family. Additionally, we were able to use the computer vision system prior to sporulation to measure the percent leaf trichome area. We estimate that an experienced rater scoring sporulation would spend at least 90% less time using the computer vision system compared with the manual visual method. This will allow more treatments to be phenotyped in order to better understand the genetic architecture of downy mildew resistance and of leaf trichome density. We anticipate that this computer vision system will find applications in other pathosystems or traits where responses can be imaged with sufficient contrast from the background.

  15. Sporulation environment of emetic toxin-producing Bacillus cereus strains determines spore size, heat resistance and germination capacity

    NARCIS (Netherlands)

    Voort, van der M.; Abee, T.

    2013-01-01

    Aim Heat resistance, germination and outgrowth capacity of Bacillus cereus spores in processed foods are major factors in causing the emetic type of gastrointestinal disease. In this study, we aim to identify the impact of different sporulation conditions on spore properties of emetic

  16. Phosphorylation of the Bacillus subtilis Replication Controller YabA Plays a Role in Regulation of Sporulation and Biofilm Formation.

    Science.gov (United States)

    García García, Tránsito; Ventroux, Magali; Derouiche, Abderahmane; Bidnenko, Vladimir; Correia Santos, Sara; Henry, Céline; Mijakovic, Ivan; Noirot-Gros, Marie-Françoise; Poncet, Sandrine

    2018-01-01

    Bacillus subtilis cells can adopt different life-styles in response to various environmental cues, including planktonic cells during vegetative growth, sessile cells during biofilm formation and sporulation. While switching life-styles, bacteria must coordinate the progression of their cell cycle with their physiological status. Our current understanding of the regulatory pathways controlling the decision-making processes and triggering developmental switches highlights a key role of protein phosphorylation. The regulatory mechanisms that integrate the bacterial chromosome replication status with sporulation involve checkpoint proteins that target the replication initiator DnaA or the kinase phosphorelay controlling the master regulator Spo0A. B. subtilis YabA is known to interact with DnaA to prevent over-initiation of replication during vegetative growth. Here, we report that YabA is phosphorylated by YabT, a Ser/Thr kinase expressed during sporulation and biofilm formation. The phosphorylation of YabA has no effect on replication initiation control but hyper-phosphorylation of YabA leads to an increase in sporulation efficiency and a strong inhibition of biofilm formation. We also provide evidence that YabA phosphorylation affects the level of Spo0A-P in cells. These results indicate that YabA is a multifunctional protein with a dual role in regulating replication initiation and life-style switching, thereby providing a potential mechanism for cross-talk and coordination of cellular processes during adaptation to environmental change.

  17. Phosphorylation of the Bacillus subtilis Replication Controller YabA Plays a Role in Regulation of Sporulation and Biofilm Formation

    Directory of Open Access Journals (Sweden)

    Tránsito García García

    2018-03-01

    Full Text Available Bacillus subtilis cells can adopt different life-styles in response to various environmental cues, including planktonic cells during vegetative growth, sessile cells during biofilm formation and sporulation. While switching life-styles, bacteria must coordinate the progression of their cell cycle with their physiological status. Our current understanding of the regulatory pathways controlling the decision-making processes and triggering developmental switches highlights a key role of protein phosphorylation. The regulatory mechanisms that integrate the bacterial chromosome replication status with sporulation involve checkpoint proteins that target the replication initiator DnaA or the kinase phosphorelay controlling the master regulator Spo0A. B. subtilis YabA is known to interact with DnaA to prevent over-initiation of replication during vegetative growth. Here, we report that YabA is phosphorylated by YabT, a Ser/Thr kinase expressed during sporulation and biofilm formation. The phosphorylation of YabA has no effect on replication initiation control but hyper-phosphorylation of YabA leads to an increase in sporulation efficiency and a strong inhibition of biofilm formation. We also provide evidence that YabA phosphorylation affects the level of Spo0A-P in cells. These results indicate that YabA is a multifunctional protein with a dual role in regulating replication initiation and life-style switching, thereby providing a potential mechanism for cross-talk and coordination of cellular processes during adaptation to environmental change.

  18. Growth and Development of Colletotrichum gloeosporioides f. alatae During Culture in Liquid Medium

    Directory of Open Access Journals (Sweden)

    Laura E. Cerón Rincón

    2006-01-01

    Full Text Available Some characteristics known as virulence factors for Colletotrichum sp. genus, like: weight of the produced mycelium, sporulation, poligalacturonase activity and pH medium were evaluated during the growth of C. gloeosporioides f. alatae in three liquid medium commonly used for fungi culture (Czapeck, Martin broth and potato broth and additionally (Czapeck with yam extract as the only source of carbon. After of 17 days of growth, maximum values were obtained for the above parameters in the last medium, compared with others growth media evaluated. The implemented medium with yam extract, supply nutritional requirements of the pathogen for the development of characteristic factors related with mechanism of infections that may play a role in the pathogenesis.

  19. Factors influencing the sporulation and cyst formation of Aphanomyces invadans, etiological agent of ulcerative mycosis in Atlantic menhaden, Brevoortia tyrannus

    Science.gov (United States)

    Kiryu, Y.; Blazer, V.S.; Vogelbein, W.K.; Kator, H.; Shields, J.D.

    2005-01-01

    Oomycete infections caused by Aphanomyces invadans occur in freshwater and estuarine fishes around the world. Along the east coast of the USA, skin ulcers caused by A. invadans are prevalent in Atlantic menhaden, Brevoortia tyrannus. From laboratory observations low salinities appear crucial to transmission of the pathogen. To better understand aspects of transmission, we characterized sporulation and cyst formation of secondary zoospores of two isolates of A. invadans at different salinities and temperatures. Sporulation occurred only at low salinities. At room temperature (ca. 20-22 C), using "pond water" augmented with artificial sea salts, the endemic strain WIC and the Thailand strain PA7 of A. invadans produced free-swimming secondary zoospores at salinities of 0, 1 and 2 psu (practical salinity unit = ???), but not at 4 psu or higher. Secondary zoospores of another species, ATCC-62427 (Aphanomyces sp.), were observed at 1, 2, 4 and 8 psu but not at 0 and 12 psu. Secondary zoospores of all three isolates, especially WIC, were abundant and motile 1-2 d post-sporulation. Sporulation was temperature dependent and occurred over a relatively narrow range. No sporulation occurred at 4, 30 or 35 C for either WIC or PA7. For both strains zoospore production within 1-3 d after the initiation of sporulation was more prolific at 25 C than at 20 and 15 C. At 15 C production of zoospores was sustained over 11 d for WIC and 5 d for PA7. At room temperature single WIC secondary zoospores remained motile 12-18 h. Salinities exceeding 4 psu or vigorous shaking caused immediate cyst formation of WIC secondary zoospores. Exposure to menhaden tissue, but not tissues of other fishes to secondary zoospores (WIC), caused rapid (2 h) cyst formation. Cysts were capable of excysting when transferred to 1 psu water within 2-3 h of cyst formation. Cysts that had remained encysted in 6.5 psu for 24 h did not excyst when transferred to 1 psu water. Salinity and temperature requirements

  20. Spatiotemporally regulated proteolysis to dissect the role of vegetative proteins during Bacillus subtilis sporulation: cell-specific requirement of σH and σA.

    Science.gov (United States)

    Riley, Eammon P; Trinquier, Aude; Reilly, Madeline L; Durchon, Marine; Perera, Varahenage R; Pogliano, Kit; Lopez-Garrido, Javier

    2018-04-01

    Sporulation in Bacillus subtilis is a paradigm of bacterial development, which involves the interaction between a larger mother cell and a smaller forespore. The mother cell and the forespore activate different genetic programs, leading to the production of sporulation-specific proteins. A critical gap in our understanding of sporulation is how vegetative proteins, made before sporulation initiation, contribute to spore formation. Here we present a system, spatiotemporally regulated proteolysis (STRP), which enables the rapid, developmentally regulated degradation of target proteins, thereby providing a suitable method to dissect the cell- and developmental stage-specific role of vegetative proteins. STRP has been used to dissect the role of two major vegetative sigma factors, σ H and σ A , during sporulation. The results suggest that σ H is only required in predivisional cells, where it is essential for sporulation initiation, but that it is dispensable during subsequent steps of spore formation. However, evidence has been provided that σ A plays different roles in the mother cell, where it replenishes housekeeping functions, and in the forespore, where it plays an unexpected role in promoting spore germination and outgrowth. Altogether, the results demonstrate that STRP has the potential to provide a comprehensive molecular dissection of every stage of sporulation, germination and outgrowth. © 2018 John Wiley & Sons Ltd.

  1. Triggering sporulation in Bacillus subtilis with artificial two-component systems reveals the importance of proper Spo0A activation dynamics.

    Science.gov (United States)

    Vishnoi, Monika; Narula, Jatin; Devi, Seram Nganbiton; Dao, Hoang-Anh; Igoshin, Oleg A; Fujita, Masaya

    2013-10-01

    Sporulation initiation in Bacillus subtilis is controlled by the phosphorylated form of the master regulator Spo0A which controls transcription of a multitude of sporulation genes. In this study, we investigated the importance of temporal dynamics of phosphorylated Spo0A (Spo0A∼P) accumulation by rewiring the network controlling its phosphorylation. We showed that simultaneous induction of KinC, a kinase that can directly phosphorylate Spo0A, and Spo0A itself from separately controlled inducible promoters can efficiently trigger sporulation even under nutrient rich conditions. However, the sporulation efficiency in this artificial two-component system was significantly impaired when KinC and/or Spo0A induction was too high. Using mathematical modelling, we showed that gradual accumulation of Spo0A∼P is essential for the proper temporal order of the Spo0A regulon expression, and that reduction in sporulation efficiency results from the reversal of that order. These insights led us to identify premature repression of DivIVA as one possible explanation for the adverse effects of accelerated accumulation of Spo0A∼P on sporulation. Moreover, we found that positive feedback resulting from autoregulation of the native spo0A promoter leads to robust control of Spo0A∼P accumulation kinetics. Thus we propose that a major function of the conserved architecture of the sporulation network is controlling Spo0A activation dynamics. © 2013 John Wiley & Sons Ltd.

  2. SpoVT: From Fine-Tuning Regulator in Bacillus subtilis to Essential Sporulation Protein in Bacillus cereus.

    Science.gov (United States)

    Eijlander, Robyn T; Holsappel, Siger; de Jong, Anne; Ghosh, Abhinaba; Christie, Graham; Kuipers, Oscar P

    2016-01-01

    Sporulation is a highly sophisticated developmental process adopted by most Bacilli as a survival strategy to withstand extreme conditions that normally do not support microbial growth. A complicated regulatory cascade, divided into various stages and taking place in two different compartments of the cell, involves a number of primary and secondary regulator proteins that drive gene expression directed toward the formation and maturation of an endospore. Such regulator proteins are highly conserved among various spore formers. Despite this conservation, both regulatory and phenotypic differences are observed between different species of spore forming bacteria. In this study, we demonstrate that deletion of the regulatory sporulation protein SpoVT results in a severe sporulation defect in Bacillus cereus , whereas this is not observed in Bacillus subtilis . Although spores are initially formed, the process is stalled at a later stage in development, followed by lysis of the forespore and the mother cell. A transcriptomic investigation of B. cereus Δ spoVT shows upregulation of genes involved in germination, potentially leading to premature lysis of prespores formed. Additionally, extreme variation in the expression of species-specific genes of unknown function was observed. Introduction of the B. subtilis SpoVT protein could partly restore the sporulation defect in the B. cereus spoVT mutant strain. The difference in phenotype is thus more than likely explained by differences in promoter targets rather than differences in mode of action of the conserved SpoVT regulator protein. This study stresses that evolutionary variances in regulon members of sporulation regulators can have profound effects on the spore developmental process and that mere protein homology is not a foolproof predictor of similar phenotypes.

  3. Poly-β-hydroxybutyrate Metabolism Is Unrelated to the Sporulation and Parasporal Crystal Protein Formation in Bacillus thuringiensis.

    Science.gov (United States)

    Wang, Xun; Li, Zhou; Li, Xin; Qian, Hongliang; Cai, Xia; Li, Xinfeng; He, Jin

    2016-01-01

    Poly-3-hydroxybutyrate (PHB) is a natural polymer synthesized by many bacteria as a carbon-energy storage material. It was accumulated maximally prior to the spore formation but was degraded during the process of sporulation in Bacillus thuringiensis. Intriguingly, B. thuringiensis also accumulates large amounts of insecticidal crystal proteins (ICPs) during sporulation, which requires considerable input of carbon and energy sources. How PHB accumulation affects sporulation and ICP formation remains unclear to date. Intuitively, one would imagine that accumulated PHB provides the energy required for ICP formation. Yet our current data indicate that this is not the case. First, growth curves of the deletion mutants of phaC (encoding the PHB synthase) and phaZ (encoding the PHB depolymerase) were found to be similar to the parent strain BMB171; no difference in growth rate could be observed. In addition we further constructed the cry1Ac10 ICP gene overexpression strains of BMB171 (BMB171-cry), as well as its phaC and phaZ deletion mutants ΔphaC-cry and ΔphaZ-cry to compare their spore and ICP production rates. Again, not much change of ICP production was observed among these strains either. In fact, PHB was still degraded in most ΔphaZ-cry cells as observed by transmission electron microscopy. Together these results indicated that there is no direct association between the PHB accumulation and the sporulation and ICP formation in B. thuringiensis. Some other enzymes for PHB degradation or other energy source may be responsible for the sporulation and/or ICP formation in B. thuringiensis.

  4. Effects of Two Salts Compounds on Mycelial Growth, Sporulation, and Spore Germination of Six Isolates of Botrytis cinerea in the Western North of Algeria

    Directory of Open Access Journals (Sweden)

    Boualem Boumaaza

    2015-01-01

    Full Text Available Six isolates of Botrytis cinerea were isolated from leaves and stems of different tomato varieties taken from four areas in the northwest of Algeria where tomato is mostly grown in greenhouses and high tunnels. The purpose of this research was to determine the effect of two salts, NaCl and CaCl2, on three stages of Botrytis cinerea’s life cycle. All isolates tested were stimulated in 50 to 150 ppm; NaCl was the most effective treatment to increase mycelial growth at two tested concentrations. However, at 300 ppm concentration, CaCl2 completely inhibited the growth of mycelium; they reach 34.78% for the isolate TR46 and 26.72% for isolate F27. The sodium and calcium salts stimulated conidia production in liquid culture. We noticed that the effect of calcium chloride on sporulation was average while sodium chloride. In the medium containing 50 ppm, calcium chloride and sodium chloride increased the germination capacity of most isolates compared with the control. Other calcium salts, at 100 or 300 ppm, decreased the germination percentage of the conidia. With the exception of sodium salts, the inhibitions of germination reduce at 150 or 300 compared with the control. Conidial germination was slightly inhibited by sodium chloride only when the concentration was over 300 ppm.

  5. A model of cell-wall dynamics during sporulation in Bacillus subtilis

    Science.gov (United States)

    Yap, Li-Wei; Endres, Robert G.

    To survive starvation, Bacillus subtilis forms durable spores. After asymmetric cell division, the septum grows around the forespore in a process called engulfment, but the mechanism of force generation is unknown. Here, we derived a novel biophysical model for the dynamics of cell-wall remodeling during engulfment based on a balancing of dissipative, active, and mechanical forces. By plotting phase diagrams, we predict that sporulation is promoted by a line tension from the attachment of the septum to the outer cell wall, as well as by an imbalance in turgor pressures in the mother-cell and forespore compartments. We also predict that significant mother-cell growth hinders engulfment. Hence, relatively simple physical principles may guide this complex biological process.

  6. Clostridium thermocellum: adhesion and sporulation while adhered to cellulose and hemicellulose

    Energy Technology Data Exchange (ETDEWEB)

    Wiegel, J.; Dykstra, M.

    1984-01-01

    During growth in the presence of fibers composed of cellulose or hemicellulose, various strains of the thermophilic soil bacterium Clostridium thermocellum and several newly isolated thermophilic anaerobic soil bacteria adhered to the fibers. Attachment occurred via a fibrous ruthenium red-staining material. C. thermocellum sporulated while attached to the fibers when the pH dropped below 6.4. It is postulated that the attachment is involved in cellulose breakdown and that C. thermocellum gaines an advantage by remaining attached to its insoluble substrates when the environment is not suitable for rapid growth. The tendency to adhere to cellulose fibers was used in the purification of thermophilic cellulolytic anaerobes. 27 references, 7 figures.

  7. The CRO-1 gene of Saccharomyces cerevisiae controls mitotic crossing over, chromosomal stability and sporulation

    International Nuclear Information System (INIS)

    Esposito, M.S.; Maleas, D.T.; Bjornstad, K.A.; Holbrook, L.L.

    1987-01-01

    The properties of a novel temperature-sensitive recombination-defective mutant of Saccharomyces cerevisiae, cro1-1 is described. The cro1-1 mutant is the first instance of a rec mutation that reduces drastically the rates of spontaneous mitotic crossing-over events but not those of gene conversional events. The cro1-1 mutation thus provides evidence that mitotic crossing-over is dependent upon gene products that are not essential for gene conversional events. The cro1-1 mutation also results in enhanced mitotic-chromosomal instability and MATa/MATα cro1-1/cro1-1 mutants are sporulation deficient. These phenotypes indicate that the CRO1 gene modulates mitotic chromosomal integrity and is essential for normal meiosis. The cro1-1 mutant possesses Holliday junction resolvase activity, hence its recombinational defect does not involve failure to execute this putative final recombinational step. 7 refs., 1 fig., 5 tabs

  8. New use of broomcorn millets for production of granular cultures of aphid-pathogenic fungus Pandora neoaphidis for high sporulation potential and infectivity to Myzus persicae.

    Science.gov (United States)

    Hua, Li; Feng, Ming-Guang

    2003-10-24

    Glutinous broomcorn millets from the crop Panicum miliaceum were first used as substrate to produce granular cultures of Pandora neoaphidis, an obligate fungal pathogen specific to aphids. Carrying a water content of 36.5% after being steamed in a regular autoclaving procedure, millet grains of each 15 g (dry weight) in a 100-ml flask were mixed with 3 ml modified Sabouraud dextrose broth containing half a mashed colony of P. neoaphidis grown on egg yolk milk agar and then incubated at 20 degrees C and a light/dark cycle of 12 h/12 h for 21 days. Based on individually monitoring conidial production potential of 20 millet grains sampled from an arbitrarily taken flask at 3-day intervals, the millet cultures incubated for 6-15 days were capable of producing 16.8-23.4 x 10(4) conidia per millet grain with conidial ejection lasting for up to 6 days. The cultured millet grains individually produced significantly more conidia than apterous adults of Myzus persicae killed by P. neoaphidis (8.4 x 10(4) conidia per cadaver) and sporulated twice longer. The modeling of time-dose-mortality data from bioassays on M. persicae apterae exposed to conidial showers from the cultured millet grains and the mycelial mats produced in liquid culture resulted in similar estimates of LC(50) (millets: 21.4, 7.3, and 4.9 conidia mm(-2) on days 5-7 after exposure; mycelial mats: 22.1, 10.6, and 7.7 conidia mm(-2)) although the LT(50) estimated at a given conidial concentration was slightly smaller for the millet cultures than for the mycelial mats. This indicates that the millet grains cultured with P. neoaphidis produced conidia as infective as or slightly more infective to M. persicae than those from the mycelial mats. Based on the sporulation potential, infectivity, and ease and cost of the millet cultures, the method developed in this study highly improved in vitro cultures of P. neoaphidis and may adapt to culturing other entomophthoralean fungi for microbial control of insect pests.

  9. Dynamic sporulation gene co-expression networks for Bacillus subtilis 168 and the food-borne isolate Bacillus amyloliquefaciens: a transcriptomic model.

    Science.gov (United States)

    Omony, Jimmy; de Jong, Anne; Krawczyk, Antonina O; Eijlander, Robyn T; Kuipers, Oscar P

    2018-02-09

    Sporulation is a survival strategy, adapted by bacterial cells in response to harsh environmental adversities. The adaptation potential differs between strains and the variations may arise from differences in gene regulation. Gene networks are a valuable way of studying such regulation processes and establishing associations between genes. We reconstructed and compared sporulation gene co-expression networks (GCNs) of the model laboratory strain Bacillus subtilis 168 and the food-borne industrial isolate Bacillus amyloliquefaciens. Transcriptome data obtained from samples of six stages during the sporulation process were used for network inference. Subsequently, a gene set enrichment analysis was performed to compare the reconstructed GCNs of B. subtilis 168 and B. amyloliquefaciens with respect to biological functions, which showed the enriched modules with coherent functional groups associated with sporulation. On basis of the GCNs and time-evolution of differentially expressed genes, we could identify novel candidate genes strongly associated with sporulation in B. subtilis 168 and B. amyloliquefaciens. The GCNs offer a framework for exploring transcription factors, their targets, and co-expressed genes during sporulation. Furthermore, the methodology described here can conveniently be applied to other species or biological processes.

  10. Salt-sensitivity of σ(H) and Spo0A prevents sporulation of Bacillus subtilis at high osmolarity avoiding death during cellular differentiation.

    Science.gov (United States)

    Widderich, Nils; Rodrigues, Christopher D A; Commichau, Fabian M; Fischer, Kathleen E; Ramirez-Guadiana, Fernando H; Rudner, David Z; Bremer, Erhard

    2016-04-01

    The spore-forming bacterium Bacillus subtilis frequently experiences high osmolarity as a result of desiccation in the soil. The formation of a highly desiccation-resistant endospore might serve as a logical osmostress escape route when vegetative growth is no longer possible. However, sporulation efficiency drastically decreases concomitant with an increase in the external salinity. Fluorescence microscopy of sporulation-specific promoter fusions to gfp revealed that high salinity blocks entry into the sporulation pathway at a very early stage. Specifically, we show that both Spo0A- and SigH-dependent transcription are impaired. Furthermore, we demonstrate that the association of SigH with core RNA polymerase is reduced under these conditions. Suppressors that modestly increase sporulation efficiency at high salinity map to the coding region of sigH and in the regulatory region of kinA, encoding one the sensor kinases that activates Spo0A. These findings led us to discover that B. subtilis cells that overproduce KinA can bypass the salt-imposed block in sporulation. Importantly, these cells are impaired in the morphological process of engulfment and late forespore gene expression and frequently undergo lysis. Altogether our data indicate that B. subtilis blocks entry into sporulation in high-salinity environments preventing commitment to a developmental program that it cannot complete. © 2015 John Wiley & Sons Ltd.

  11. Salt-sensitivity of σH and Spo0A prevents sporulation of Bacillus subtilis at high osmolarity avoiding death during cellular differentiation

    Science.gov (United States)

    Widderich, Nils; Rodrigues, Christopher D.A.; Commichau, Fabian M.; Fischer, Kathleen E.; Ramirez-Guadiana, Fernando H.; Rudner, David Z.; Bremer, Erhard

    2016-01-01

    Summary The spore-forming bacterium Bacillus subtilis frequently experiences high osmolarity as a result of desiccation in the soil. The formation of a highly desiccation-resistant endospore might serve as a logical osmostress escape route when vegetative growth is no longer possible. However, sporulation efficiency drastically decreases concomitant with an increase in the external salinity. Fluorescence microscopy of sporulation-specific promoter fusions to gfp revealed that high salinity blocks entry into the sporulation pathway at a very early stage. Specifically, we show that both Spo0A- and SigH-dependent transcription are impaired. Furthermore, we demonstrate that the association of SigH with core RNA polymerase is reduced under these conditions. Suppressors that modestly increase sporulation efficiency at high salinity map to the coding region of sigH and in the regulatory region of kinA, encoding one the sensor kinases that activates Spo0A. These findings led us to discover that B. subtilis cells that overproduce KinA can bypass the salt-imposed block in sporulation. Importantly, these cells are impaired in the morphological process of engulfment and late forespore gene expression and frequently undergo lysis. Altogether our data indicate that B. subtilis blocks entry into sporulation in high-salinity environments preventing commitment to a developmental program that it cannot complete. PMID:26712348

  12. Evidence that Autophosphorylation of the Major Sporulation Kinase in Bacillus subtilis Is Able To Occur in trans.

    Science.gov (United States)

    Devi, Seram Nganbiton; Kiehler, Brittany; Haggett, Lindsey; Fujita, Masaya

    2015-08-01

    Entry into sporulation in Bacillus subtilis is governed by a multicomponent phosphorelay, a complex version of a two-component system which includes at least three histidine kinases (KinA to KinC), two phosphotransferases (Spo0F and Spo0B), and a response regulator (Spo0A). Among the three histidine kinases, KinA is known as the major sporulation kinase; it is autophosphorylated with ATP upon starvation and then transfers a phosphoryl group to the downstream components in a His-Asp-His-Asp signaling pathway. Our recent study demonstrated that KinA forms a homotetramer, not a dimer, mediated by the N-terminal domain, as a functional unit. Furthermore, when the N-terminal domain was overexpressed in the starving wild-type strain, sporulation was impaired. We hypothesized that this impairment of sporulation could be explained by the formation of a nonfunctional heterotetramer of KinA, resulting in the reduced level of phosphorylated Spo0A (Spo0A∼P), and thus, autophosphorylation of KinA could occur in trans. To test this hypothesis, we generated a series of B. subtilis strains expressing homo- or heterogeneous KinA protein complexes consisting of various combinations of the phosphoryl-accepting histidine point mutant protein and the catalytic ATP-binding domain point mutant protein. We found that the ATP-binding-deficient protein was phosphorylated when the phosphorylation-deficient protein was present in a 1:1 stoichiometry in the tetramer complex, while each of the mutant homocomplexes was not phosphorylated. These results suggest that ATP initially binds to one protomer within the tetramer complex and then the γ-phosphoryl group is transmitted to another in a trans fashion. We further found that the sporulation defect of each of the mutant proteins is complemented when the proteins are coexpressed in vivo. Taken together, these in vitro and in vivo results reinforce the evidence that KinA autophosphorylation is able to occur in a trans fashion

  13. Les bactéries sporulées dans les conserves de légumes (petits pois ...

    African Journals Online (AJOL)

    Unicornis

    brevis (4.53%). Mots clés : Conserves végétales - Petits pois- Bactéries sporulées - Identification biochimique. Abstract. For a consumer more and more aware about the risks for his health, regarding the food he buys, the aim of this study is to verify the hygienic quality of ten batches, each one contains five green peas cans, ...

  14. Impacts of sporulation temperature, exposure to compost matrix and temperature on survival of Bacillus cereus spores during livestock mortality composting.

    Science.gov (United States)

    Stanford, K; Reuter, T; Gilroyed, B H; McAllister, T A

    2015-04-01

    To investigate impact of sporulation and compost temperatures on feasibility of composting for disposal of carcasses contaminated with Bacillus anthracis. Two strains of B. cereus, 805 and 1391, were sporulated at either 20 or 37°C (Sporulation temperature, ST) and 7 Log10 CFU g(-1) spores added to autoclaved manure in nylon bags (pore size 50 μm) or in sealed vials. Vials and nylon bags were embedded into compost in either a sawdust or manure matrix each containing 16 bovine mortalities (average weight 617 ± 33 kg), retrieved from compost at intervals over 217 days and survival of B. cereus spores assessed. A ST of 20°C decreased spore survival by 1·4 log10 CFU g(-1) (P Compost temperatures >55°C reduced spore survival (P compost temperatures were key factors influencing survival of B. cereus spores in mortality compost. Composting may be most appropriate for the disposal of carcasses infected with B. anthracis at ambient temperatures ≤20°C under thermophillic composting conditions (>55°C). © 2015 The Society for Applied Microbiology.

  15. Sporulation and mycelial growth of Fusarium solani in different culture media and steady bright = Esporulação e crescimento micelial de Fusarium solani em diferentes meios de cultura e regimes de luminosidade

    Directory of Open Access Journals (Sweden)

    Jhonata Lemos da Silva

    2012-04-01

    Full Text Available Considering the physiological characterization of Fusarium solani isolated from cassava roots, the objective of this study was to evaluate mycelial growth and sporulation of F. solani in different culture media and lighting regimes. The fungus was grown using five culture media (potato dextrose agar, potato sucrose agar, cassava, agar-agar, and water micophil under three light regimes (continuous darkness, a photoperiod of 12 h, and continuous light during the incubation period of seven day, temperature 25 °C ± 2 °C. The trial was done in completely randomized design with three replications. Discs of 5 mm diameter taken from the edge of the colony grown on PDA medium were transferred to the center of Petri dishes containing 20 mL of each medium. Mycelial growth was determined by measuring the diameter of the colonies in two diametrically opposite directions while sporulation by quantifying conidia by drop method. No significant changes in the production of conidia and mycelial mass in different culture media and lighting regimes tested, and BDA and BSA under the regime of continuous light best sporulation and conidial production were observed. While in the midst AA under continuous darkness was the lowest rates of mycelial growth and sporulation. = Visando a caracterização fisiológica de Fusarium solani isolado de raízes de mandioca, objetivou-se com este trabalho avaliar a esporulação e o crescimento micelial de F. solani em diferentes meios de cultura e regimes de luminosidade. O fungo foi cultivado utilizando cinco meios de cultura (batata dextrose ágar, batata sacarose ágar, mandioca ágar, micophil e ágar-água sob três regimes de luminosidade (escuro contínuo, fotoperíodo de 12 h e luz contínua durante o período de incubação de sete dias, a temperatura de 25 °C ± 2 o C. O ensaio foi conduzido em delineamento inteiramente casualizado, em esquema fatorial (5x3, com três repetições. Discos de 5 mm de di

  16. The effect of growth medium on B. anthracis Sterne spore carbohydrate content.

    Science.gov (United States)

    Colburn, Heather A; Wunschel, David S; Antolick, Kathryn C; Melville, Angela M; Valentine, Nancy B

    2011-06-01

    The expressed characteristics of biothreat agents may be impacted by variations in the culture environment, including growth medium formulation. The carbohydrate composition of B. anthracis spores has been well studied, particularly for the exosporium, which is the outermost spore structure. The carbohydrate composition of the exosporium has been demonstrated to be distinct from the vegetative form containing unique monosaccharides. We have investigated the carbohydrate composition of B. anthracis Sterne spores produced using four different medium types formulated with different sources of medium components. The amount of rhamnose, 3-O-methyl rhamnose and galactosamine was found to vary significantly between spores cultured using different medium formulations. The relative abundance of these monosaccharides compared to other monosaccharides such as mannosamine was also found to vary with medium type. Specific medium components were also found to impact the carbohydrate profile. Xylose has not been previously described in B. anthracis spores but was detected at low levels in two media. This may represent residual material from the brewery yeast extract used to formulate these two media. These results illustrate the utility of this method to capture the impact of growth medium on carbohydrate variation in spores. Detecting carbohydrate profiles in B. anthracis evidentiary material may provide useful forensic information on the growth medium used for sporulation. Copyright © 2011 Elsevier B.V. All rights reserved.

  17. MrSkn7 controls sporulation, cell wall integrity, autolysis, and virulence in Metarhizium robertsii.

    Science.gov (United States)

    Shang, Yanfang; Chen, Peilin; Chen, Yixiong; Lu, Yuzhen; Wang, Chengshu

    2015-04-01

    Two-component signaling pathways generally include sensor histidine kinases and response regulators. We identified an ortholog of the response regulator protein Skn7 in the insect-pathogenic fungus Metarhizium robertsii, which we named MrSkn7. Gene deletion assays and functional characterizations indicated that MrSkn7 functions as a transcription factor. The MrSkn7 null mutant of M. robertsii lost the ability to sporulate and had defects in cell wall biosynthesis but was not sensitive to oxidative and osmotic stresses compared to the wild type. However, the mutant was able to produce spores under salt stress. Insect bioassays using these spores showed that the virulence of the mutant was significantly impaired compared to that of the wild type due to the failures to form the infection structure appressorium and evade host immunity. In particular, deletion of MrSkn7 triggered cell autolysis with typical features such as cell vacuolization, downregulation of repressor genes, and upregulation of autolysis-related genes such as extracellular chitinases and proteases. Promoter binding assays confirmed that MrSkn7 could directly or indirectly control different putative target genes. Taken together, the results of this study help us understand the functional divergence of Skn7 orthologs as well as the mechanisms underlying the development and control of virulence in insect-pathogenic fungi. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  18. Experimental Infection with Sporulated Oocysts of Eimeria maxima (Apicomplexa: Eimeriidae) in Broiler

    Science.gov (United States)

    Brito, Luciana da S.; Pereira, Elder N.; da Silva, Augusta A.; Bentivóglio Costa Silva, Vinícius; Freitas, Fagner L. da C.

    2014-01-01

    Through this study we assessed the metabolic and pathological changes in broilers experimentally infected with oocysts of Eimeria maxima. To perform the experiment, we used 150 broiler strain cooB males, with ten days of age, were randomized according to weight and randomly assigned to two experimental groups: the control group was inoculated with 0.5 mL of distilled water; the infected group inoculated with 0.5 mL of solution containing 5 × 104 sporulated oocysts of Eimeria maxima. The live performance was evaluated on day 0 (day of inoculation), 5°, 10°, 15°, 25°, and 35° dpi, being slaughtered by cervical dislocation, fifteen birds/group. Although the sum in meat production was higher in the control group, the weight of the heart and gizzard of the experimental animals showed no significant difference, while the liver had difference on day 5°, 15°, and 35° dpi. The pathologic evaluation showed congested mucosa and presence of large amounts of mucus at 6 dpi. Therefore, it is concluded that the dose of 5 × 104  E. maxima inoculated in the experimental group was enough to cause harm to the animal organism. PMID:26464925

  19. Metabolic alterations in broiler chickens experimentally infected with sporulated oocysts of Eimeria maxima.

    Science.gov (United States)

    Freitas, Fagner Luiz da Costa

    2014-01-01

    Metabolic and morphometric alterations of the duodenal villi caused by parasitism of chickens by Eimeria maxima were evaluated, using 100 male Cobb birds, randomly distributed into two groups (control and infected). The infected group was inoculated with 0.5 ml of a solution containing 5 × 10³ sporulated oocysts of Eimeria maxima. Ten birds per sample were sacrificed on the 6th, 11th, 22nd and 41st days post-infection (dpi). In order to evaluate the alterations, samples of duodenum, jejunum and ileum fragments were collected after necropsy for histological analysis. Villus biometry was determined by means of a slide graduated in microns that was attached to a binocular microscope. To evaluate the biochemical data, 5 ml of blood were sampled from the birds before sacrifice. The statistical analyses were performed using the GraphPad 5 statistical software for Windows. Tukey's multiple comparison test (p maxima causes both qualitative and quantitative alterations to the structure of the intestinal villi, thereby interfering with the absorption of nutrients such as calcium, phosphorus, magnesium, protein and lipids, with consequent reductions in the birds' weights.

  20. Comparison of expression of key sporulation, solventogenic and acetogenic genes in C. beijerinckii NRRL B-598 and its mutant strain overexpressing spo0A.

    Science.gov (United States)

    Kolek, J; Diallo, M; Vasylkivska, M; Branska, B; Sedlar, K; López-Contreras, A M; Patakova, P

    2017-11-01

    The production of acetone, butanol and ethanol by fermentation of renewable biomass has potential to become a valuable industrial process. Mechanisms of solvent production and sporulation involve some common regulators in some ABE-producing clostridia, although details of the links between the pathways are not clear. In this study, we compare a wild-type (WT) Clostridium beijerinckii NRRL B-598 with its mutant strain OESpo0A, in which the gene encoding Spo0A, an important regulator of both sporulation and solventogenesis, is overexpressed in terms of solvent and acid production. We also compare morphologies during growth on two different media: TYA broth, where the WT culture sporulates, and RCM, where the WT culture does not. In addition, RT-qPCR-based analysis of expression profiles of spo0A, spoIIE, sigG, spoVD, ald and buk1 genes involved in sporulation or solvent production in these strains, were compared. The OESpo0A mutant did not produce spores and butanol titre was lower compared to the WT, but increased amounts of butyric acid and ethanol were produced. The gene spo0A had high levels of expression in the WT under non-sporulating culture conditions while other selected genes for sporulation factors were downregulated significantly. Similar observations were obtained for OESpo0A where spo0A overexpression and downregulation of other sporulation genes were demonstrated. Higher expression of spo0A led to higher expression of buk1 and ald, which could confirm the role of spo0A in activation of the solventogenic pathway, although solvent production was not affected significantly in the WT and was weakened in the OESpo0A mutant.

  1. The comER Gene Plays an Important Role in Biofilm Formation and Sporulation in both Bacillus subtilis and Bacillus cereus.

    Science.gov (United States)

    Yan, Fang; Yu, Yiyang; Wang, Luyao; Luo, Yuming; Guo, Jian-Hua; Chai, Yunrong

    2016-01-01

    Bacteria adopt alternative cell fates during development. In Bacillus subtilis, the transition from planktonic growth to biofilm formation and sporulation is controlled by a complex regulatory circuit, in which the most important event is activation of Spo0A, a transcription factor and a master regulator for genes involved in both biofilm formation and sporulation. In B. cereus, the regulatory pathway controlling biofilm formation and cell differentiation is much less clear. In this study, we show that a novel gene, comER, plays a significant role in biofilm formation as well as sporulation in both B. subtilis and B. cereus. Mutations in the comER gene result in defects in biofilm formation and a delay in spore formation in the two Bacillus species. Our evidence supports the idea that comER may be part of the regulatory circuit that controls Spo0A activation. comER likely acts upstream of sda, a gene encoding a small checkpoint protein for both sporulation and biofilm formation, by blocking the phosphor-relay and thereby Spo0A activation. In summary, our studies outlined a conserved, positive role for comER, a gene whose function was previously uncharacterized, in the regulation of biofilm formation and sporulation in the two Bacillus species.

  2. The comER Gene Plays an Important Role in Biofilm Formation and Sporulation in both Bacillus subtilis and Bacillus cereus

    Science.gov (United States)

    Yan, Fang; Yu, Yiyang; Wang, Luyao; Luo, Yuming; Guo, Jian-hua; Chai, Yunrong

    2016-01-01

    Bacteria adopt alternative cell fates during development. In Bacillus subtilis, the transition from planktonic growth to biofilm formation and sporulation is controlled by a complex regulatory circuit, in which the most important event is activation of Spo0A, a transcription factor and a master regulator for genes involved in both biofilm formation and sporulation. In B. cereus, the regulatory pathway controlling biofilm formation and cell differentiation is much less clear. In this study, we show that a novel gene, comER, plays a significant role in biofilm formation as well as sporulation in both B. subtilis and B. cereus. Mutations in the comER gene result in defects in biofilm formation and a delay in spore formation in the two Bacillus species. Our evidence supports the idea that comER may be part of the regulatory circuit that controls Spo0A activation. comER likely acts upstream of sda, a gene encoding a small checkpoint protein for both sporulation and biofilm formation, by blocking the phosphor-relay and thereby Spo0A activation. In summary, our studies outlined a conserved, positive role for comER, a gene whose function was previously uncharacterized, in the regulation of biofilm formation and sporulation in the two Bacillus species. PMID:27446060

  3. Effect of different concentrations of dl-isoleucine, dl-valine, and dl-alanine on growth and sporulation in Fusarium oxysporum f. udum (Butl.) Sn. et H.

    Science.gov (United States)

    Prasad, M; Chaudhary, S K

    1977-01-01

    D1-alanine and dl-valine, when added as an extra nitrogen for fortifying the already present inorganic nitrogen source, actually acted as growth retardant for F. oxysporum f. udum (Butl.) Sn. et H. Sporulation of microconidia was indifferently affected by these two amino acids. DI-valine stimulated microconidial formation in young cultures only. In both young and old cultures the lowest concentration of dl-valine depressed macronidial sporulation. In old cultures the lowest concentration of valine stimulated chlamydospore differentiation rapidly, higher concentrations being less effective. D1-alanine, as an additional nitrogen source, depressed both macro- and microconidal sporulation. It did not even invigorate chlamydospore formation. D1-isoleucine, on the other hand, belongs to the category of growth promoters and profuse and stimulative sporulators of macro- and microconidia. This pathogen needs very specific and preferential doses of the three amino acids, if these are used as a booster in addition to the already present nitrogen source. The response, both in terms of mycelial growth and sporulation of the three spore forms, was also conditioned by the age of the culture.

  4. Modified cyanobacteria

    Science.gov (United States)

    Vermaas, Willem F J.

    2014-06-17

    Disclosed is a modified photoautotrophic bacterium comprising genes of interest that are modified in terms of their expression and/or coding region sequence, wherein modification of the genes of interest increases production of a desired product in the bacterium relative to the amount of the desired product production in a photoautotrophic bacterium that is not modified with respect to the genes of interest.

  5. Separation medium containing thermally exfoliated graphite oxide

    Science.gov (United States)

    Prud'homme, Robert K. (Inventor); Aksay, Ilhan A. (Inventor); Herrera-Alonso, Margarita (Inventor)

    2012-01-01

    A separation medium, such as a chromatography filling or packing, containing a modified graphite oxide material, which is a thermally exfoliated graphite oxide with a surface area of from about 300 m.sup.2/g to 2600 m.sup.2/g, wherein the thermally exfoliated graphite oxide has a surface that has been at least partially functionalized.

  6. Kinetic modeling of sporulation and product formation in stationary phase by Bacillus coagulans RK-02 vis-à-vis other Bacilli.

    Science.gov (United States)

    Das, Subhasish; Sen, Ramkrishna

    2011-10-01

    A logistic kinetic model was derived and validated to characterize the dynamics of a sporogenous bacterium in stationary phase with respect to sporulation and product formation. The kinetic constants as determined using this model are particularly important for describing intrinsic properties of a sporogenous bacterial culture in stationary phase. Non-linear curve fitting of the experimental data into the mathematical model showed very good correlation with the predicted values for sporulation and lipase production by Bacillus coagulans RK-02 culture in minimal media. Model fitting of literature data of sporulation and product (protease and amylase) formation in the stationary phase by some other Bacilli and comparison of the results of model fitting with those of Bacillus coagulans helped validate the significance and robustness of the developed kinetic model. Copyright © 2011 Elsevier Ltd. All rights reserved.

  7. Immunizing potential of sporulated oocysts of Eimeria nieschulzi exposed to heat and 60Co gamma-radiation

    International Nuclear Information System (INIS)

    Conder, G.A.; Duszynski, D.W.

    1977-01-01

    Sporulated oocysts of Eimeria nieschulzi Dieben 1924, a rat coccidium, were exposed to radiation, heat, or both in an effort to attenuate the parasite. Moderate levels of each treatment or combination thereof attenuated the parasite, reduced pathogenesis (as judged by oocyst discharge during primary infection), and produced immunity to challenge when the oocysts were subsequently inoculated into rats. Thus, heat- and/or radiation-treated E. nieschulzi oocysts fed to rats could reduce pathogenesis during a primary infection and yet give good homologous protection

  8. The GCKIII Kinase Sps1 and the 14-3-3 Isoforms, Bmh1 and Bmh2, Cooperate to Ensure Proper Sporulation in Saccharomyces cerevisiae

    Science.gov (United States)

    Slubowski, Christian J.; Paulissen, Scott M.; Huang, Linda S.

    2014-01-01

    Sporulation in the budding yeast Saccharomyces cerevisiae is a developmental program initiated in response to nutritional deprivation. Sps1, a serine/threonine kinase, is required for sporulation, but relatively little is known about the molecular mechanisms through which it regulates this process. Here we show that SPS1 encodes a bona-fide member of the GCKIII subfamily of STE20 kinases, both through phylogenetic analysis of the kinase domain and examination of its C-terminal regulatory domain. Within the regulatory domain, we find Sps1 contains an invariant ExxxPG region conserved from plant to human GCKIIIs that we call the EPG motif; we show this EPG motif is important for SPS1 function. We also find that Sps1 is phosphorylated near its N-terminus on Threonine 12, and that this phosphorylation is required for the efficient production of spores. In Sps1, Threonine 12 lies within a 14-3-3 consensus binding sequence, and we show that the S. cerevisiae 14-3-3 proteins Bmh1 and Bmh2 bind Sps1 in a Threonine 12-dependent fashion. This interaction is significant, as BMH1 and BMH2 are required during sporulation and genetically interact with SPS1 in sporulating cells. Finally, we observe that Sps1, Bmh1 and Bmh2 are present in both the nucleus and cytoplasm during sporulation. We identify a nuclear localization sequence in Sps1 at amino acids 411–415, and show that this sequence is necessary and sufficient for nuclear localization. Taken together, these data identify regions within Sps1 critical for its function and indicate that SPS1 and 14-3-3s act together to promote proper sporulation in S. cerevisiae. PMID:25409301

  9. Studies on the control of development: isolation of Bacillus subtilis mutants blocked early in sporulation and defective in synthesis of highly phosphorylated nucleotides.

    Science.gov (United States)

    Rhaese, H J; Hoch, J A; Groscurth, R

    1977-03-01

    To test our model on the mechanism of initiation of differentiation in Bacillus subtilis, we tested early blocked (stage 0) sporulation mutants for their ability to synthesize highly phosphorylated nucleotides. We also isolated early blocked asporogenous mutants with the aid of the intercalating drug tilorone. Among all mutants tested we found that the spo0F-bearing strain was unable to synthesize adenosine 3'(2')-triphosphate 5'-triphosphate, pppAppp. A revertant of this mutant regained the ability to both sporulate and synthesize pppAppp. Ribosomes of the asporogenous mutant isolated at T2 (2 hr after the end of logarithmic growth) of sporulation, in contrast to the wild type, do not synthesize adenosine 3'(2')-diphosphate 5'-diphosphate, ppApp, or adenosine 3'(2')-diphosphate 5'-triphosphate, pppApp, but synthesize guanosine 3'(2')-diphosphate 5'-diphosphate, ppGpp, and guanosine 3'(2')-diphosphate 5'-triphosphate, pppGpp. This behavior is characteristic of ribosomes from vegetative, not sporulating, cells. Ribosomes from the sporogenous revertant behave like those of the wild type. The results suggest that the spo0F mutation may be a mutation in the structural gene for pppAppp synthetase. The inability to synthesize pppAppp in this strain also prevents the formation of "sporulation-specific ribosomes," i.e., ribosomes that synthetize ppApp and pppApp. The present experiments suggest that the nucleotide pppAppp participates in the initiation of sporulation by triggering a sequencies of events required for the production of heat-resistant spores.

  10. NMR studies of the sporulation protein SpoIIAA: Implications for the regulation of the transcription factor σF in Bacillus subtilis

    International Nuclear Information System (INIS)

    Kovacs, Helena; Comfort, David; Lord, Matthew; Yudkin, Michael; Campbell, Iain D.; Nilges, Michael

    2001-01-01

    SpoIIAA participates in a four-component mechanism for phosphorylation-dependent transcription control at the outset of sporulation. We report the refinement of the solution structure of SpoIIAA by using the automated iterative NOE assignment method ARIA. To complement the structural data, the protein dynamics were determined by measuring the T 1 , T 2 and NOE of the backbone 15 N-nuclei. The refined structure permits a discussion of the structural features that are important for the function of SpoIIAA in the regulation of the sporulation sigma factor σ F , and for homologous regulatory pathways present in B. subtilis and in other bacilli

  11. Alternative Sigma Factors SigF, SigE, and SigG Are Essential for Sporulation in Clostridium botulinum ATCC 3502

    OpenAIRE

    Kirk, David G.; Zhang, Zhen; Korkeala, Hannu; Lindström, Miia

    2014-01-01

    Clostridium botulinum produces heat-resistant endospores that may germinate and outgrow into neurotoxic cultures in foods. Sporulation is regulated by the transcription factor Spo0A and the alternative sigma factors SigF, SigE, SigG, and SigK in most spore formers studied to date. We constructed mutants of sigF, sigE, and sigG in C. botulinum ATCC 3502 and used quantitative reverse transcriptase PCR and electron microscopy to assess their expression of the sporulation pathway on transcription...

  12. Efeito de meios de cultura e fatores físicos no crescimento e esporulação de Alternaria dauci e A. solani Effect of culture media and physical factors on growth and sporulation of Alternaria dauci and A. solani

    Directory of Open Access Journals (Sweden)

    Pablo Pulz

    2009-06-01

    Full Text Available Alternaria dauci e Alternaria solani são espécies / 24 h. O método desenvolvido neste trabalho foi comparado ao reconhecidamente difíceis de esporular em meios de cultura. Este tradicionalmente utilizado (BDA, 25 ºC, 12 h luz branca / 12 h trabalho teve o objetivo de verificar a influência de alguns meios escuro e raspagem da colônia. O meio V8-ágar, temperatura de 25 de cultura e fatores fisicos sobre o crescimento micelial e a ºC, luz NUV e raspagem das colônias exerceram influência mais esporulação dessas espécies. Testaram-se os meios de cultura BDA, marcante no crescimento e esporulação. O fotoperíodo 12 h luz NUV Aveia e V8; temperaturas (15ºC, 20ºC, 25ºC, 30ºC e 35ºC / 12 h escuro foi o que mais estimulou a esporulação. Observou-se que, comprimentos de onda da luz durante a incubação (amarelo, azul, de modo geral, períodos de escuro maiores que os períodos de luz, branco, NUV, verde e vermelho; tipos de injúria aplicados à aplicados após injúria da colônia, favoreceram a esporulação. O colônia (raspagem, UV, irradiação de microondas, e temperatura método desenvolvido mostrou-se nitidamente superior ao de 100 ºC e fotoperíodos (luz / escuro, respectivamente, de 24 h tradicionalmente utilizado, para crescimento e esporulação de ambas / 0 h, 22 h / 2 h, 17 h / 7 h, 12 h / 12 h, 7 h / 17 h, 2 h / 22 e 0 h as espécies.Alternaria dauci and A. solani are fungal species known for h and 0 h / 24 h were tested. The method developed in this study was difficult sporulation in culture media. This study had the objective of compared to the traditional procedure (BDA, 25 ºC, 12 h white / 12 verifying the influence of some physical factors on mycelia growth h dark light and scratching of the colony. V8-agar medium, and sporulation of these two species. Culture media (BDA, oat and temperature of 25 ºC, NUV light and scratching of the colonies had a V8, temperature (15ºC, 20ºC, 25ºC, 30ºC and 35ºC, light

  13. Jet multiplicity distributions: medium dependence in MLLA

    International Nuclear Information System (INIS)

    Armesto, Nestor; Pajares, Carlos; Quiroga-Arias, Paloma

    2009-01-01

    We study the medium dependence of the multiplicity distributions in the modified leading logarithmic approximation. We focus in the enhancement in the number of branchings as the partons travel trough a dense medium created in a heavy-ion collision. We study the effect of a higher number of splittings in some jet observables by introducing the medium as a constant (f med ) in the splitting functions. Having as our ansatz for the quark and gluon jets mean multiplicities left angle n G right angle =e γy and left angle n Q right angle =r -1 e γy , we study in an analytic approach the dependence with the medium (f med ) of the anomalous dimension (γ), the multiplicity ratio (r), and so the mean multiplicities. We also obtain the higher-order moments of the multiplicity distribution, what allows us to study its dispersion. (orig.)

  14. Structure of the sporulation histidine kinase inhibitor Sda from Bacillus subtilis and insights into its solution state

    Energy Technology Data Exchange (ETDEWEB)

    Jacques, David A.; Streamer, Margaret [School of Molecular and Microbial Biosciences, University of Sydney (Australia); Rowland, Susan L.; King, Glenn F. [Institute of Molecular Biology, University of Queensland (Australia); Guss, J. Mitchell; Trewhella, Jill; Langley, David B., E-mail: d.langley@usyd.edu.au [School of Molecular and Microbial Biosciences, University of Sydney (Australia)

    2009-06-01

    The crystal structure of Sda, a DNA-replication/damage checkpoint inhibitor of sporulation in B. subtilis, has been solved via the MAD method. The subunit arrangement in the crystal has enabled a reappraisal of previous biophysical data, resulting in a new model for the behaviour of the protein in solution. The crystal structure of the DNA-damage checkpoint inhibitor of sporulation, Sda, from Bacillus subtilis, has been solved by the MAD technique using selenomethionine-substituted protein. The structure closely resembles that previously solved by NMR, as well as the structure of a homologue from Geobacillus stearothermophilus solved in complex with the histidine kinase KinB. The structure contains three molecules in the asymmetric unit. The unusual trimeric arrangement, which lacks simple internal symmetry, appears to be preserved in solution based on an essentially ideal fit to previously acquired scattering data for Sda in solution. This interpretation contradicts previous findings that Sda was monomeric or dimeric in solution. This study demonstrates the difficulties that can be associated with the characterization of small proteins and the value of combining multiple biophysical techniques. It also emphasizes the importance of understanding the physical principles behind these techniques and therefore their limitations.

  15. Chemical sporulation and germination: cytoprotective nanocoating of individual mammalian cells with a degradable tannic acid-FeIII complex

    Science.gov (United States)

    Lee, Juno; Cho, Hyeoncheol; Choi, Jinsu; Kim, Doyeon; Hong, Daewha; Park, Ji Hun; Yang, Sung Ho; Choi, Insung S.

    2015-11-01

    Individual mammalian cells were coated with cytoprotective and degradable films by cytocompatible processes maintaining the cell viability. Three types of mammalian cells (HeLa, NIH 3T3, and Jurkat cells) were coated with a metal-organic complex of tannic acid (TA) and ferric ion, and the TA-FeIII nanocoat effectively protected the coated mammalian cells against UV-C irradiation and a toxic compound. More importantly, the cell proliferation was controlled by programmed formation and degradation of the TA-FeIII nanocoat, mimicking the sporulation and germination processes found in nature.Individual mammalian cells were coated with cytoprotective and degradable films by cytocompatible processes maintaining the cell viability. Three types of mammalian cells (HeLa, NIH 3T3, and Jurkat cells) were coated with a metal-organic complex of tannic acid (TA) and ferric ion, and the TA-FeIII nanocoat effectively protected the coated mammalian cells against UV-C irradiation and a toxic compound. More importantly, the cell proliferation was controlled by programmed formation and degradation of the TA-FeIII nanocoat, mimicking the sporulation and germination processes found in nature. Electronic supplementary information (ESI) available: Experimental details, LSCM images, and SEM and TEM images. See DOI: 10.1039/c5nr05573c

  16. How the early sporulation sigma factor sigmaF delays the switch to late development in Bacillus subtilis.

    Science.gov (United States)

    Karmazyn-Campelli, Céline; Rhayat, Lamya; Carballido-López, Rut; Duperrier, Sandra; Frandsen, Niels; Stragier, Patrick

    2008-03-01

    Sporulation in Bacillus subtilis is a primitive differentiation process involving two cell types, the forespore and the mother cell. Each cell implements two successive transcription programmes controlled by specific sigma factors. We report that activity of sigma(G), the late forespore sigma factor, is kept in check by Gin, the product of csfB, a gene controlled by sigma(F), the early forespore sigma factor. Gin abolishes sigma(G) transcriptional activity when sigma(G) is artificially synthesized during growth, but has no effect on sigma(F). Gin interacts strongly with sigma(G) but not with sigma(F) in a yeast two-hybrid experiment. The absence of Gin allows sigma(G) to be active during sporulation independently of the mother-cell development to which it is normally coupled. Premature sigma(G) activity leads to the formation of slow-germinating spores, and complete deregulation of sigma(G) synthesis is lethal when combined with gin inactivation. Gin allows sigma(F) to delay the switch to the late forespore transcription programme by preventing sigma(G) to take over before the cell has reached a critical stage of development. A similar strategy, following a completely unrelated route, is used by the mother cell.

  17. ParA and ParB coordinate chromosome segregation with cell elongation and division during Streptomyces sporulation

    Science.gov (United States)

    Donczew, Magdalena; Mackiewicz, Paweł; Wróbel, Agnieszka; Flärdh, Klas; Zakrzewska-Czerwińska, Jolanta

    2016-01-01

    In unicellular bacteria, the ParA and ParB proteins segregate chromosomes and coordinate this process with cell division and chromosome replication. During sporulation of mycelial Streptomyces, ParA and ParB uniformly distribute multiple chromosomes along the filamentous sporogenic hyphal compartment, which then differentiates into a chain of unigenomic spores. However, chromosome segregation must be coordinated with cell elongation and multiple divisions. Here, we addressed the question of whether ParA and ParB are involved in the synchronization of cell-cycle processes during sporulation in Streptomyces. To answer this question, we used time-lapse microscopy, which allows the monitoring of growth and division of single sporogenic hyphae. We showed that sporogenic hyphae stop extending at the time of ParA accumulation and Z-ring formation. We demonstrated that both ParA and ParB affect the rate of hyphal extension. Additionally, we showed that ParA promotes the formation of massive nucleoprotein complexes by ParB. We also showed that FtsZ ring assembly is affected by the ParB protein and/or unsegregated DNA. Our results indicate the existence of a checkpoint between the extension and septation of sporogenic hyphae that involves the ParA and ParB proteins. PMID:27248800

  18. Saprophytic Activity and Sporulation of Cryphonectria parasitica on Dead Chestnut Wood in Forests with Naturally Established Hypovirulence.

    Science.gov (United States)

    Prospero, S; Conedera, M; Heiniger, U; Rigling, D

    2006-12-01

    ABSTRACT Sustainable biological control of the chestnut blight fungus Crypho-nectria parasitica with hypovirulence depends on the production and dissemination of hypovirus-infected propagules of the pathogen. We investigated the ability of C. parasitica to sporulate and produce hypo-virus-infected spores on recently dead chestnut wood in coppice stands in southern Switzerland where hypovirulence has been naturally established. The number and type (active, inactive, or none) of cankers was assessed on experimentally cut and stacked stems, firewood stacks, and natural dead wood. Hypovirus-free and hypovirus-infected strains readily survived for more than 1 year in the chestnut blight cankers of the stacked stems. Sporulation of C. parasitica was observed on the surface of preexisting inactive and active cankers, as well as on newly colonized bark areas and was significantly more abundant than on comparable cankers on living stems. On all types of dead wood, we observed more stromata with perithecia than with pycnidia; however, a large proportion of the stromata was not differentiated. All perithecia examined yielded only hypovirus-free ascospores. The incidence of pycnidia that produced hypovirus-infected conidia ranged from 5% on natural dead wood to 41% on the experimental stacks. The mean virus transmission rate into conidia was 69%. Our study demonstrates a considerable saprophytic activity of C. parasitica on recently dead chestnut wood and supports the hypothesis of a role of this saprophytic phase in the epidemiology of hypovirulence.

  19. Ras GTPases Modulate Morphogenesis, Sporulation and Cellulase Gene Expression in the Cellulolytic Fungus Trichoderma reesei

    Science.gov (United States)

    Zhang, Jiwei; Zhang, Yanmei; Zhong, Yaohua; Qu, Yinbo; Wang, Tianhong

    2012-01-01

    Background The model cellulolytic fungus Trichoderma reesei (teleomorph Hypocrea jecorina) is capable of responding to environmental cues to compete for nutrients in its natural saprophytic habitat despite its genome encodes fewer degradative enzymes. Efficient signalling pathways in perception and interpretation of environmental signals are indispensable in this process. Ras GTPases represent a kind of critical signal proteins involved in signal transduction and regulation of gene expression. In T. reesei the genome contains two Ras subfamily small GTPases TrRas1 and TrRas2 homologous to Ras1 and Ras2 from S. cerevisiae, but their functions remain unknown. Methodology/Principal Findings Here, we have investigated the roles of GTPases TrRas1 and TrRas2 during fungal morphogenesis and cellulase gene expression. We show that both TrRas1 and TrRas2 play important roles in some cellular processes such as polarized apical growth, hyphal branch formation, sporulation and cAMP level adjustment, while TrRas1 is more dominant in these processes. Strikingly, we find that TrRas2 is involved in modulation of cellulase gene expression. Deletion of TrRas2 results in considerably decreased transcription of cellulolytic genes upon growth on cellulose. Although the strain carrying a constitutively activated TrRas2G16V allele exhibits increased cellulase gene transcription, the cbh1 and cbh2 expression in this mutant still strictly depends on cellulose, indicating TrRas2 does not directly mediate the transmission of the cellulose signal. In addition, our data suggest that the effect of TrRas2 on cellulase gene is exerted through regulation of transcript abundance of cellulase transcription factors such as Xyr1, but the influence is independent of cAMP signalling pathway. Conclusions/Significance Together, these findings elucidate the functions for Ras signalling of T. reesei in cellular morphogenesis, especially in cellulase gene expression, which contribute to deciphering the

  20. Heavy quark energy loss in nuclear medium

    International Nuclear Information System (INIS)

    Zhang, Benr-Wei; Wang, Enke; Wang, Xin-Nian

    2003-01-01

    Multiple scattering, modified fragmentation functions and radiative energy loss of a heavy quark propagating in a nuclear medium are investigated in perturbative QCD. Because of the quark mass dependence of the gluon formation time, the medium size dependence of heavy quark energy loss is found to change from a linear to a quadratic form when the initial energy and momentum scale are increased relative to the quark mass. The radiative energy loss is also significantly suppressed relative to a light quark due to the suppression of collinear gluon emission by a heavy quark

  1. Sporulation-specific cell division defects in ylmE mutants of Streptomyces coelicolor are rescued by additional deletion of ylmD.

    Science.gov (United States)

    Zhang, Le; Willemse, Joost; Hoskisson, Paul A; van Wezel, Gilles P

    2018-05-09

    Cell division during the reproductive phase of the Streptomyces life-cycle requires tight coordination between synchronous formation of multiple septa and DNA segregation. One remarkable difference with most other bacterial systems is that cell division in Streptomyces is positively controlled by the recruitment of FtsZ by SsgB. Here we show that deletion of ylmD (SCO2081) or ylmE (SCO2080), which lie in operon with ftsZ in the dcw cluster of actinomycetes, has major consequences for sporulation-specific cell division in Streptomyces coelicolor. Electron and fluorescence microscopy demonstrated that ylmE mutants have a highly aberrant phenotype with defective septum synthesis, and produce very few spores with low viability and high heat sensitivity. FtsZ-ring formation was also highly disturbed in ylmE mutants. Deletion of ylmD had a far less severe effect on sporulation. Interestingly, the additional deletion of ylmD restored sporulation to the ylmE null mutant. YlmD and YlmE are not part of the divisome, but instead localize diffusely in aerial hyphae, with differential intensity throughout the sporogenic part of the hyphae. Taken together, our work reveals a function for YlmD and YlmE in the control of sporulation-specific cell division in S. coelicolor, whereby the presence of YlmD alone results in major developmental defects.

  2. Dynamic sporulation gene co-expression networks for Bacillus subtilis 168 and the food-borne isolate Bacillus amyloliquefaciens : a transcriptomic model

    NARCIS (Netherlands)

    Omony, Jimmy; de Jong, Anne; Krawczyk, Antonina O; Eijlander, Robyn T; Kuipers, Oscar P

    2018-01-01

    Sporulation is a survival strategy, adapted by bacterial cells in response to harsh environmental adversities. The adaptation potential differs between strains and the variations may arise from differences in gene regulation. Gene networks are a valuable way of studying such regulation processes and

  3. A novel non prophage(-like) gene-intervening element within gerE that is reconstituted during sporulation in Bacillus cereus ATCC10987.

    Science.gov (United States)

    Abe, Kimihiro; Shimizu, Shin-Ya; Tsuda, Shuhei; Sato, Tsutomu

    2017-09-12

    Gene rearrangement is a widely-shared phenomenon in spore forming bacteria, in which prophage(-like) elements interrupting sporulation-specific genes are excised from the host genome to reconstitute the intact gene. Here, we report a novel class of gene-intervening elements, named gin, inserted in the 225 bp gerE-coding region of the B. cereus ATCC10987 genome, which generates a sporulation-specific rearrangement. gin has no phage-related genes and possesses three site-specific recombinase genes; girA, girB, and girC. We demonstrated that the gerE rearrangement occurs at the middle stage of sporulation, in which site-specific DNA recombination took place within the 9 bp consensus sequence flanking the disrupted gerE segments. Deletion analysis of gin uncovered that GirC and an additional factor, GirX, are responsible for gerE reconstitution. Involvement of GirC and GirX in DNA recombination was confirmed by an in vitro recombination assay. These results broaden the definition of the sporulation-specific gene rearrangement phenomenon: gene-intervening elements are not limited to phage DNA but may include non-viral genetic elements that carry a developmentally-regulated site-specific recombination system.

  4. Single cell analysis of gene expression patterns of competence development and initiation of sporulation in Bacillus subtilis grown on chemically defined media

    NARCIS (Netherlands)

    Veening, J. -W.; Smits, W. K.; Hamoen, L. W.; Kuipers, O. P.

    Aim: Understanding the basis for the heterogeneous (or bistable) expression patterns of competence development and sporulation in Bacillus subtilis. Methods and Results: Using flow cytometric analyses of various promoter-GFP fusions, we have determined the single-cell gene expression patterns of

  5. Comparison of expression of key sporulation, solventogenic and acetogenic genes in C. beijerinckii NRRL B-598 and its mutant strain overexpressing spo0A

    NARCIS (Netherlands)

    Kolek, J.; Diallo, M.; Vasylkivska, M.; Branska, B.; Sedlar, K.; López-Contreras, A.M.; Patakova, P.

    2017-01-01

    The production of acetone, butanol and ethanol by fermentation of renewable biomass has potential to become a valuable industrial process. Mechanisms of solvent production and sporulation involve some common regulators in some ABE-producing clostridia, although details of the links between the

  6. Clonostachys rosea reduces spot blotch in barley by inhibiting pre-penetration growth and sporulation of Bipolaris sorokiniana without inducing resistance

    DEFF Research Database (Denmark)

    Jensen, Birgit; Lübeck, Peter S; Jørgensen, Hans Jørgen Lyngs

    2016-01-01

    as the pathogen, whereas application 24 h after the pathogen had no effect. IK726 also reduced the sporulation capacity of B. sorokiniana. Microscopy of B. sorokiniana infection revealed that IK726 primarily inhibited conidial germination and appressorium formation while further pathogen development and host...

  7. A Gene Expressed during Sexual and Asexual Sporulation in Phytophthora infestans is a Member of the Puf Family of Translational Regulators

    DEFF Research Database (Denmark)

    Cvitanich, Cristina; Judelson, Howard S.

    2003-01-01

    and persisted in mature oospores. Expression was also observed in hyphal tips just prior to asexual sporulation, in sporangiophores, in mature sporangia, and in zoospores. The signal quickly disappeared once spores made the transition to hyphae after germination. Nutrient limitation did not induce the gene...

  8. Concept medium programme

    DEFF Research Database (Denmark)

    Bjerrum, Peter

    2005-01-01

    The present essay is an attempt to determine the architectural project of the 21st century in relation to a modern conception of space as the medium of architecture, and of sociality as its program......The present essay is an attempt to determine the architectural project of the 21st century in relation to a modern conception of space as the medium of architecture, and of sociality as its program...

  9. A novel marine algal toxicity bioassay based on sporulation inhibition in the green macroalga Ulva pertusa (Chlorophyta)

    Energy Technology Data Exchange (ETDEWEB)

    Han, Taejun [Division of Biology and Chemistry, University of Incheon, Incheon 402-749 (Korea, Republic of)]. E-mail: hanalgae@incheon.ac.kr; Choi, Gye-Woon [Department of Civil and Environmental System Engineering, University of Incheon, Incheon 402-749 (Korea, Republic of)

    2005-11-10

    A 5-day aquatic toxicity test based on sporulation inhibition of the green macroalga Ulva pertusa Kjellman has been developed. Optimal test conditions determined for photon irradiance, salinity and temperature were 60-200 {mu}mol photons m{sup -2} s{sup -1}, 25-35%o and 15-20 deg C, respectively. Tests were conducted by exposing U. pertusa thallus disks to a reference toxicant (sodium dodecyl sulfate; SDS), metals (Cd{sup 2+}, Cu{sup 2+}, Zn{sup 2+}, Pb{sup 2+}) and elutriates of sludge collected from nine different locations. The EC{sub 50} values for SDS was 5.35 mg L{sup -1}. When four heavy metals were assayed, the NOECs were highest for lead (0.625 mg L{sup -1}) and lowest for copper (0.031 mg L{sup -1}). The EC{sub 50} values showed the following toxicity rankings: Cu{sup 2+} (0.061 mg L{sup -1}) > Cd{sup 2+} (0.326 mg L{sup -1}) > Zn{sup 2+} (0.738 mg L{sup -1}) > Pb{sup 2+} (0.877 mg L{sup -1}). The bioassay indicated also that the sporulation endpoint could be a sensitive indicator of toxicity effects of elutriates of sludge as reflected from the NOEC values equal to or lower than the lowest concentration employed (6.25%). Sporulation was significantly inhibitied in all elutriates with the greatest and least effects observed in elutriates of sludge from industrial waste (EC{sub 50} 6.78%) and filtration bed (EC{sub 50} 15.0%), respectively. The results of the Spearman rank correlation analysis for EC{sub 50} data versus the concentrations of toxicants in the sludge presented a significant correlation between toxicity and four heavy metals (Cd{sup 2+}, Cu{sup 2+}, Pb{sup 2+}, Zn{sup 2+}). Introduction of the concept of toxicity unit (TU) showed that these metals were the main cause of toxicity in elutriates of at least four out of nine sludge samples. Members of the order Ulvales show a wide geographic distribution and have similar reproductive characteristics, thus making it possible to apply the present test method to other algae of this taxa, elsewhere

  10. A novel marine algal toxicity bioassay based on sporulation inhibition in the green macroalga Ulva pertusa (Chlorophyta)

    International Nuclear Information System (INIS)

    Han, Taejun; Choi, Gye-Woon

    2005-01-01

    A 5-day aquatic toxicity test based on sporulation inhibition of the green macroalga Ulva pertusa Kjellman has been developed. Optimal test conditions determined for photon irradiance, salinity and temperature were 60-200 μmol photons m -2 s -1 , 25-35%o and 15-20 deg C, respectively. Tests were conducted by exposing U. pertusa thallus disks to a reference toxicant (sodium dodecyl sulfate; SDS), metals (Cd 2+ , Cu 2+ , Zn 2+ , Pb 2+ ) and elutriates of sludge collected from nine different locations. The EC 50 values for SDS was 5.35 mg L -1 . When four heavy metals were assayed, the NOECs were highest for lead (0.625 mg L -1 ) and lowest for copper (0.031 mg L -1 ). The EC 50 values showed the following toxicity rankings: Cu 2+ (0.061 mg L -1 ) > Cd 2+ (0.326 mg L -1 ) > Zn 2+ (0.738 mg L -1 ) > Pb 2+ (0.877 mg L -1 ). The bioassay indicated also that the sporulation endpoint could be a sensitive indicator of toxicity effects of elutriates of sludge as reflected from the NOEC values equal to or lower than the lowest concentration employed (6.25%). Sporulation was significantly inhibitied in all elutriates with the greatest and least effects observed in elutriates of sludge from industrial waste (EC 50 6.78%) and filtration bed (EC 50 15.0%), respectively. The results of the Spearman rank correlation analysis for EC 50 data versus the concentrations of toxicants in the sludge presented a significant correlation between toxicity and four heavy metals (Cd 2+ , Cu 2+ , Pb 2+ , Zn 2+ ). Introduction of the concept of toxicity unit (TU) showed that these metals were the main cause of toxicity in elutriates of at least four out of nine sludge samples. Members of the order Ulvales show a wide geographic distribution and have similar reproductive characteristics, thus making it possible to apply the present test method to other algae of this taxa, elsewhere. This novel method will be a useful tool for assessing the aquatic toxicity of a wide range of toxicants, once the

  11. A non-linear model for temperature-dependent sporulation and T-2 and HT-2 production of Fusarium langsethiae and Fusarium sporotrichioides.

    Science.gov (United States)

    Nazari, Leyla; Manstretta, Valentina; Rossi, Vittorio

    2016-04-01

    This research has produced new quantitative data on the sporulation and T-2+HT-2 toxin production that could be further integrated to develop a comprehensive disease or toxin prediction model for Fusarium langsethiae and Fusarium sporotrichioides. Experiments were conducted to determine the effect of temperature or incubation time on sporulation and the effect of temperature on T-2+HT-2 toxin production of strains of the two species. F. sporotrichioides demonstrated a preference for higher temperatures than F. langsethiae during sporulation; the optimum temperature was 24.5 ± 0.7 °C for F. langsethiae and 32.3 ± 2.1 °C for F. sporotrichioides, according to the Beta equation fitted to the data. The dynamics of sporulation over different incubation times were fitted by a Gompertz function. The maximum spore production was estimated to be after 18 and 8 d incubation at optimum temperatures for F. langsethiae and F. sporotrichioides, respectively. F. sporotrichioides produced more T-2+HT-2 than F. langsethiae. The best fit of the effect of temperature on T-2+HT-2 production in wheat grains was obtained with a Beta equation showing an optimum temperature of 14.7 ± 0.8 °C for F. langsethiae and 12.1 ± 0.2 °C for F. sporotrichioides. The optimum temperature for mycotoxin production was lower than for sporulation. Copyright © 2016 The British Mycological Society. Published by Elsevier Ltd. All rights reserved.

  12. Morphological and genetic characterization of group I Clostridium botulinum type B strain 111 and the transcriptional regulator spoIIID gene knockout mutant in sporulation.

    Science.gov (United States)

    Hosomi, Koji; Kuwana, Ritsuko; Takamatsu, Hiromu; Kohda, Tomoko; Kozaki, Shunji; Mukamoto, Masafumi

    2015-06-01

    Clostridium botulinum is a heat-resistant spore-forming bacterium that causes the serious paralytic illness botulism. Heat-resistant spores may cause food sanitation hazards and sporulation plays a central role in the survival of C. botulinum. We observed morphological changes and investigated the role of the transcriptional regulator SpoIIID in the sporulation of C. botulinum type B strain 111 in order to elucidate the molecular mechanism in C. botulinum. C. botulinum type B formed heat-resistant spores through successive morphological changes corresponding to those of Bacillus subtilis, a spore-forming model organism. An analysis of the spoIIID gene knockout mutant revealed that the transcriptional regulator SpoIIID contributed to heat-resistant spore formation by C. botulinum type B and activated the transcription of the sigK gene later during sporulation. Transcription of the spoIIID gene, which differed from that in B. subtilis and Clostridium difficile, was observed in the sigE gene knockout mutant of C. botulinum type B. An analysis of the sigF gene knockout mutant showed that the sporulation-specific sigma factor SigF was essential for transcription of the spoIIID gene in C. botulinum type B. These results suggest that the regulation of sporulation in C. botulinum is not similar to that in B. subtilis and other clostridia. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. Nuclear medium effects on the nucleon properties

    International Nuclear Information System (INIS)

    Gerard, A.

    1986-06-01

    The idea that the nuclear medium may modify the properties of the nucleon is not really a new one. But until these last few years the intrinsic properties of the nucleon such as its mass, baryonic or electromagnetic size, magnetic moments, were hardly suspected to be substantially modified by the nuclear environment. The question raised essentially from two categories of experimental investigations, in quite different kinematical regimes and it remains at the present time a controversal subject. In this paper I try to review the present status of experimental investigations and some of the recent theoretical developments relevant to this topic

  14. The Influence of Sporulation Conditions on the Spore Coat Protein Composition of Bacillus subtilis Spores

    NARCIS (Netherlands)

    Abhyankar, Wishwas R.; Kamphorst, Kiki; Swarge, Bhagyashree N.; van Veen, Henk; van der Wel, Nicole N.; Brul, Stanley; de Koster, Chris G.; de Koning, Leo J.

    2016-01-01

    Spores are of high interest to the food and health sectors because of their extreme resistance to harsh conditions, especially against heat. Earlier research has shown that spores prepared on solid agar plates have a higher heat resistance than those prepared under a liquid medium condition. It has

  15. Air-liquid interface biofilms of Bacillus cereus: formation, sporulation, and dispersion

    NARCIS (Netherlands)

    Wijman, J.G.E.; Leeuw, de P.P.L.A.; Moezelaar, R.; Zwietering, M.H.; Abee, T.

    2007-01-01

    Biofilm formation by Bacillus cereus was assessed using 56 strains of B. cereus, including the two sequenced strains, ATCC 14579 and ATCC 10987. Biofilm production in microtiter plates was found to be strongly dependent on incubation time, temperature, and medium, as well as the strain used, with

  16. Growth and sporulation of Metarhizium flavoviride var. Flavoviride on culture media and lighting regimes Crescimento e esporulação de Metarhizium flavoviride var. Flavoviride em meios de cultura e regimes de luz

    Directory of Open Access Journals (Sweden)

    Sideney Becker Onofre

    2001-09-01

    Full Text Available Entomopathogenic fungi from the genus Metarhizium are largely used for the biological control of agricultural pests by conidia spreading on the field. Although conidia production is well studied in M. anisopliae, only few research studies were done in M. flavoviride. The present work was carried out alming to evaluate the Mycelial growth and sporulation of the entomopathogenic fungus Metarhizium flavoviride var. flavoviride growing at 27 ± 2°C on Potato-dextrose-agar (PDA, Czapek-agar (CZP and a complete agar medium (CM under three lighting regimes, (continuous illumination, light/dark cycle and an black light/dark cycle were investigated. A completely randomized 3 × 3 (culture media × lighting regime factorial design with four replicates was used. The best mycelial growth and sporulation occurred on the PDA and CM media under continuous illumination (P Fungos entomopatogênicos do genêro Metarhizium são empregados no controle biológico de pragas agrícolas por meio da dispersão de seus conídios no campo. Embora a produção de conídios em M. anisopliae esteja bem estudada, poucas pesquisas a respeito existem na espécie M. flavoviride. O presente trabalho foi realizado para avaliar o efeito de três meios de cultura, batata-dextrose-ágar (BDA, Czapek-ágar (CZP e meio completo (MC, e três regimes de luminosidade, claro contínuo, alternância com luz do dia/escuro e luz negra/escuro, sobre o crescimento miceliano e esporulação do fungo entomopatogênico Metarhizium flavoviride var. flavoviride. O experimento foi realizado em câmara de incubação à temperatura de 27 ± 2°C. Empregou-se um delineamento experimental inteiramente casualizado, em arranjo fatorial 3°C 3 (meios de cultura e regime de luminosidade com quatro repetições. As melhores condições para o crescimento miceliano e esporulação foram conseguidas tanto no meio de cultura BDA como no MC quando combinados com o regime claro contínuo (P <= 0,05.

  17. The Interstellar Medium

    CERN Document Server

    Lequeux, James

    2005-01-01

    Describing interstellar matter in our galaxy in all of its various forms, this book also considers the physical and chemical processes that are occurring within this matter. The first seven chapters present the various components making up the interstellar matter and detail the ways that we are able to study them. The following seven chapters are devoted to the physical, chemical and dynamical processes that control the behaviour of interstellar matter. These include the instabilities and cloud collapse processes that lead to the formation of stars. The last chapter summarizes the transformations that can occur between the different phases of the interstellar medium. Emphasizing methods over results, "The Interstellar Medium" is written for graduate students, for young astronomers, and also for any researchers who have developed an interest in the interstellar medium.

  18. Levels of small molecules and enzymes in the mother cell compartment and the forespore of sporulating Bacillus megaterium.

    Science.gov (United States)

    Singh, R P; Setlow, B; Setlow, P

    1977-06-01

    We have determined the amounts of a number of small molecules and enzymes in the mother cell compartment and the developing forespore during sporulation of Bacillus megaterium. Significant amounts of adenosine 5'-triphosphate and reduced nicotinamide adenine dinucleotide were present in the forespore compartment before accumulation of dipicolinic acid (DPA), but these compounds disappeared as DPA was accumulated. 3-Phosphoglyceric acid (3-PGA) accumulated only within the developing forespore, beginning 1 to 2 h before DPA accumulation. Throughout its development the forespore contained constant levels of enzymes of both 3-PGA synthesis (phosphoglycerate kinase and glyceraldehyde-3-phosphate dehydrogenase) and 3-PGA utilization (phosphoglycerate mutase, enolase, and pyruvate kinase) at levels similar to those in the mother cell and the dormant spore. Despite the presence of enzymes for 3-PGA utilization, this compound was stable within isolated forespores. Two acid-soluble proteins (A and B proteins) also accumulated only in the forespore, beginning 1 to 2 h before DPA accumulation. At this time the specific protease involved in degradation of the A and B proteins during germination also appeared, but only in the forespore compartment. Nevertheless, the A and B proteins were stable within isolated forespores. Arginine and glutamic acid accumulated within the forespore in parallel with DPA accumulation. The forespore also contained the enzyme arginase at a level similar to that in the mother cell and a level of glutamic acid decarboxylase 2- to 25-fold higher than that in the mother cell, depending on when in sporulation the forespores were isolated. The specific activities of several other enzymes (protease active on hemoglobin, ornithine transcarbamylase, malate dehydrogenase, aconitase, and isocitrate dehydrogenase) in forespores were about 10% or less of the values in the mother cell. Aminopeptidase was present at similar levels in both compartments; threonine

  19. Optical recording medium

    International Nuclear Information System (INIS)

    Andriech, A.; Bivol, V.; Tridukh, G.; Tsiuleanu, D.

    2002-01-01

    The invention relates of the micro- and optoelectronics, computer engineering ,in particular, to tjhe optical information media and may be used in hilography. Summary of the invention consists in that the optical image recording medium, containing a dielectric substrates, onto one surface of which there are placed in series a transparent electricity conducting layer, a photo sensitive recording layer of chalcogenic glass and a thin film electrode of aluminium, is provided with an optically transparent protective layer, applied into the thin film electrode. The result of the invention consists in excluding the dependence of chemical processes course into the medium upon environmental conditions

  20. Selection of optimum conditions of medium acidity and aeration for submerget cultivation of Bacillus thuringiensis and Beauveria bassiana

    Directory of Open Access Journals (Sweden)

    O. A. Dregval

    2010-06-01

    Full Text Available The paper deals with the influence of medium pH and aeration rate on growth and sporulation of Bacillus thuringiensis and Вeauveria bassiana, which are main constituents of the complex microbial insecticide. It was established optimal medium pH for B. thuringiensis – 6.0 and for В. bassiana – 6.0–7.0. The maximum productivity of the studied microorganisms was observed in the same range of aeration – 7– 14 mmol O2/l/h. The selected conditions of cultivation are necessary for the production of complex biological insecticide based on the association of B. thuringiensis and B. bassiana.

  1. Modified SEAGULL

    Science.gov (United States)

    Salas, M. D.; Kuehn, M. S.

    1994-01-01

    Original version of program incorporated into program SRGULL (LEW-15093) for use on National Aero-Space Plane project, its duty being to model forebody, inlet, and nozzle portions of vehicle. However, real-gas chemistry effects in hypersonic flow fields limited accuracy of that version, because it assumed perfect-gas properties. As a result, SEAGULL modified according to real-gas equilibrium-chemistry methodology. This program analyzes two-dimensional, hypersonic flows of real gases. Modified version of SEAGULL maintains as much of original program as possible, and retains ability to execute original perfect-gas version.

  2. Roentgen contrast medium

    International Nuclear Information System (INIS)

    Tamborski, C.

    1989-01-01

    The patent deals with a roentgen contrast medium containing a perfluorinebrominealkylether of the formula C m F 2m+1 OC n F 2n Br dispersed in water, preferentially in the presence of a non-ionic dispersing agent such as a fluorinated amidoaminoxide. 2 tabs

  3. Radon in geological medium

    Energy Technology Data Exchange (ETDEWEB)

    Hricko, J [GEOCOMPLEX, a.s., Bratislava (Slovakia)

    1996-12-31

    The paper presented deals with behavior of the radon in geological medium and with some results of the radon survey in Bratislava and Kosice regions. 1) The a{sub v} has been detected in the holes 0.80 m deep. The density of observations - 3 reference areas (one represents 20 stations) per 1 km{sup 2}. The radon risk maps in 1:25000 and 1:50000 scales have been compiled. The 56.8% of the project area lies in low radon risk, 37.6% in medium radon risk and 5.6% in high radon risk. Follow-up monitoring of the equivalent volume radon activity (EVRA) at the flats, located in the areas with high radon risk of the surface layer, has showed values several times higher than Slovak limits (Marianka, Raca, Vajnory). The evidence that neotectonic is excellent medium for rising up emanation to the subsurface layer, is shown on the map. The tectonic zone of Liscie udolie in Bratislava-Karlova Ves area has been clearly detected by profile radon survey (a{sub v} > 50 kBq/m{sup 3}). 2) At present, northern half of the area of Kosice in question was covered by radon survey. The low and medium radon risks have been observed here, while localities with high radon risk are small in extent. The part of radon risk and soil permeability map from northern Kosice area is shown. (J.K.) 3 figs., 2 refs.

  4. Radon in geological medium

    International Nuclear Information System (INIS)

    Hricko, J.

    1995-01-01

    The paper presented deals with behavior of the radon in geological medium and with some results of the radon survey in Bratislava and Kosice regions. 1) The a v has been detected in the holes 0.80 m deep. The density of observations - 3 reference areas (one represents 20 stations) per 1 km 2 . The radon risk maps in 1:25000 and 1:50000 scales have been compiled. The 56.8% of the project area lies in low radon risk, 37.6% in medium radon risk and 5.6% in high radon risk. Follow-up monitoring of the equivalent volume radon activity (EVRA) at the flats, located in the areas with high radon risk of the surface layer, has showed values several times higher than Slovak limits (Marianka, Raca, Vajnory). The evidence that neotectonic is excellent medium for rising up emanation to the subsurface layer, is shown on the map. The tectonic zone of Liscie udolie in Bratislava-Karlova Ves area has been clearly detected by profile radon survey (a v > 50 kBq/m 3 ). 2) At present, northern half of the area of Kosice in question was covered by radon survey. The low and medium radon risks have been observed here, while localities with high radon risk are small in extent. The part of radon risk and soil permeability map from northern Kosice area is shown. (J.K.) 3 figs., 2 refs

  5. The influence of sporulation conditions on the spore coat protein composition of Bacillus subtilis spores.

    OpenAIRE

    Wishwas R. Abhyankar; Wishwas R. Abhyankar; Kiki Kamphorst; Bhagyashree N. Swarge; Bhagyashree N. Swarge; Henk van Veen; Nicole N. van der Wel; Stanley Brul; Chris G. de Koster; Leo J. de Koning

    2016-01-01

    Spores are of high interest to the food and health sectors because of their extreme resistance to harsh conditions, especially against heat. Earlier research has shown that spores prepared on solid agar plates have a higher heat resistance than those prepared under a liquid medium condition. It has also been shown that the more mature a spore is, the higher is its heat resistance most likely mediated, at least in part, by the progressive cross-linking of coat proteins. The current study for t...

  6. The Influence of Sporulation Conditions on the Spore Coat Protein Composition of Bacillus subtilis Spores

    OpenAIRE

    Abhyankar, Wishwas R.; Kamphorst, Kiki; Swarge, Bhagyashree N.; van Veen, Henk; van der Wel, Nicole N.; Brul, Stanley; de Koster, Chris G.; de Koning, Leo J.

    2016-01-01

    Spores are of high interest to the food and health sectors because of their extreme resistance to harsh conditions, especially against heat. Earlier research has shown that spores prepared on solid agar plates have a higher heat resistance than those prepared under a liquid medium condition. It has also been shown that the more mature a spore is, the higher is its heat resistance most likely mediated, at least in part, by the progressive cross-linking of coat proteins. The current study for t...

  7. Concept medium program

    DEFF Research Database (Denmark)

    Bjerrum, Peter

    2003-01-01

    The present essays is an attempt to dertermine the architecural project of the 21st century in realation to a modern conception of space as the medium of architecture, and of society as its program. This attempt adopts the internal point of view of an architect in describing a modern architectural...... project within the framework: concept - program, these notions being concieved as spatial representations primarily and immediately "given" to architecture....

  8. NMR studies of the sporulation protein SpoIIAA: Implications for the regulation of the transcription factor {sigma}F in Bacillus subtilis

    Energy Technology Data Exchange (ETDEWEB)

    Kovacs, Helena; Comfort, David; Lord, Matthew; Yudkin, Michael; Campbell, Iain D.; Nilges, Michael

    2001-04-15

    SpoIIAA participates in a four-component mechanism for phosphorylation-dependent transcription control at the outset of sporulation. We report the refinement of the solution structure of SpoIIAA by using the automated iterative NOE assignment method ARIA. To complement the structural data, the protein dynamics were determined by measuring the T{sub 1}, T{sub 2} and NOE of the backbone {sup 15}N-nuclei. The refined structure permits a discussion of the structural features that are important for the function of SpoIIAA in the regulation of the sporulation sigma factor {sigma}{sup F}, and for homologous regulatory pathways present in B. subtilis and in other bacilli.

  9. Eukaryote-like Ser/Thr protein kinase PrkA modulates sporulation via regulating the transcriptional factor σ(K) in Bacillus subtilis.

    Science.gov (United States)

    Yan, Jinyuan; Zou, Wei; Fang, Juan; Huang, Xiaowei; Gao, Feng; He, Zeying; Zhang, Keqin; Zhao, Ninghui

    2015-01-01

    Protein kinase A (PrkA), also known as AMP-activated protein kinase, functions as a serine/threonine protein kinase (STPK), has been shown to be involved in a variety of important biologic processes, including pathogenesis of many important diseases in mammals. However, the biological functions of PrkA are less known in prokaryote cells. Here, we explored the function of PrkA as well as its underlying molecular mechanisms using the model bacterium Bacillus subtilis168. When PrkA is inhibited by 9-β-D-arabinofuranosyladenine (ara-A) in the wild type strain or deleted in the ΔprkA mutant strain, we observed sporulation defects in B. subtilis 168, suggesting that PrkA functions as a sporulation-related protein. Transcriptional analysis using the lacZ reporter gene demonstrated that deletion of prkA significantly reduced the expression of the transcriptional factor σ(K) and its downstream genes. Complementation of sigK gene in prkA knockout mutant partially rescued the phenotype of ΔprkA, further supporting the hypothesis that the decreased σ(K) expression should be one of the reasons for the sporulation defect resulting from prkA disruption. Finally, our data confirmed that Hpr (ScoC) negatively controlled the expression of transcriptional factor σ(K), and thus PrkA accelerated sporulation and the expression of σ(K) by suppression of Hpr (ScoC). Taken together, our study discovered a novel function of the eukaryotic-like STPK PrkA in spore development as well as its underlying molecular mechanism in B. subtilis.

  10. Optical activity via Kerr nonlinearity in a spinning chiral medium

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Anwar Ali, E-mail: anwarali@uom.edu.pk [Department of Physics, University of Malakand at Chakdara Dir(L) (Pakistan); Bacha, Bakht Amin, E-mail: aminoptics@gmail.com [Department of Physics, University of Malakand at Chakdara Dir(L) (Pakistan); Khan, Rahmat Ali, E-mail: rahmat_alipk@yahoo.com [Department of Mathematics, University of Malakand (Pakistan)

    2016-11-11

    Optical activity is investigated in a chiral medium by employing the four level cascade atomic model, in which the optical responses of the atomic medium are studied with Kerr nonlinearity. Light entering into a chiral medium splits into circular birefringent beams. The angle of divergence between the circular birefringent beams and the polarization states of the two light beams is manipulated with Kerr nonlinearity. In the stationary chiral medium the angle of divergence between the circular birefringent beams is calculated to be 1.3 radian. Furthermore, circular birefringence is optically controlled in a spinning chiral medium, where the maximum rotary photon drag angle for left (right) circularly polarized beam is ±1.1 (±1.5) microradian. The change in the angle of divergence between circular birefringent beams by rotary photon drag is calculated to be 0.4 microradian. The numerical results may help to understand image designing, image coding, discovery of photonic crystals and optical sensing technology. - Highlights: • Coherent control of a circular birefringence in a chiral medium is studied. • Angle of divergence between birefringent beams is modified with Kerr nonlinearity. • Rotary photon drag is controlled for birefringent beams and enhanced with Kerr nonlinearity in a spinning medium. • Rotation of the angle of divergence is observed with mechanical rotation of the medium about an axis and modified with Kerr effect. • A change in the angle of divergence is calculated by about a microradian with rotary photon drag.

  11. Activation of Rab GTPase Sec4 by its GEF Sec2 is required for prospore membrane formation during sporulation in yeast Saccharomyces cerevisiae.

    Science.gov (United States)

    Suda, Yasuyuki; Tachikawa, Hiroyuki; Inoue, Ichiro; Kurita, Tomokazu; Saito, Chieko; Kurokawa, Kazuo; Nakano, Akihiko; Irie, Kenji

    2018-02-01

    Sec2 activates Sec4 Rab GTPase as a guanine nucleotide exchange factor for the recruitment of downstream effectors to facilitate tethering and fusion of post-Golgi vesicles at the plasma membrane. During the meiosis and sporulation of budding yeast, post-Golgi vesicles are transported to and fused at the spindle pole body (SPB) to form a de novo membrane, called the prospore membrane. Previous studies have revealed the role of the SPB outer surface called the meiotic outer plaque (MOP) in docking and fusion of post-Golgi vesicles. However, the upstream molecular machinery for post-Golgi vesicular fusion that facilitates prospore membrane formation remains enigmatic. Here, we demonstrate that the GTP exchange factor for Sec4, Sec2, participates in the formation of the prospore membrane. A conditional mutant in which the SEC2 expression is shut off during sporulation showed sporulation defects. Inactivation of Sec2 caused Sec4 targeting defects along the prospore membranes, thereby causing insufficient targeting of downstream effectors and cargo proteins to the prospore membrane. These results suggest that the activation of Sec4 by Sec2 is required for the efficient supply of post-Golgi vesicles to the prospore membrane and thus for prospore membrane formation/extension and subsequent deposition of spore wall materials. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  12. The PAS domains of the major sporulation kinase in Bacillus subtilis play a role in tetramer formation that is essential for the autokinase activity.

    Science.gov (United States)

    Kiehler, Brittany; Haggett, Lindsey; Fujita, Masaya

    2017-08-01

    Sporulation in Bacillus subtilis is induced upon starvation. In a widely accepted model, an N-terminal "sensor" domain of the major sporulation kinase KinA recognizes a hypothetical starvation signal(s) and autophosphorylates a histidine residue to activate the master regulator Spo0A via a multicomponent phosphorelay. However, to date no confirmed signal has been found. Here, we demonstrated that PAS-A, the most N-terminal of the three PAS domains (PAS-ABC), is dispensable for the activity, contrary to a previous report. Our data indicated that the autokinase activity is dependent on the formation of a functional tetramer, which is mediated by, at least, PAS-B and PAS-C. Additionally, we ruled out the previously proposed notion that NAD + /NADH ratio controls KinA activity through the PAS-A domain by demonstrating that the cofactors show no effects on the kinase activity in vitro. In support of these data, we found that the cofactors exist in approximately 1000-fold excess of KinA in the cell and the cofactors' ratio does not change significantly during growth and sporulation, suggesting that changes in the cofactor ratio might not play a role in controlling KinA activity. These data may refute the widely-held belief that the activity of KinA is regulated in response to an unknown starvation signal(s). © 2017 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

  13. Predicted RNA Binding Proteins Pes4 and Mip6 Regulate mRNA Levels, Translation, and Localization during Sporulation in Budding Yeast.

    Science.gov (United States)

    Jin, Liang; Zhang, Kai; Sternglanz, Rolf; Neiman, Aaron M

    2017-05-01

    In response to starvation, diploid cells of Saccharomyces cerevisiae undergo meiosis and form haploid spores, a process collectively referred to as sporulation. The differentiation into spores requires extensive changes in gene expression. The transcriptional activator Ndt80 is a central regulator of this process, which controls many genes essential for sporulation. Ndt80 induces ∼300 genes coordinately during meiotic prophase, but different mRNAs within the NDT80 regulon are translated at different times during sporulation. The protein kinase Ime2 and RNA binding protein Rim4 are general regulators of meiotic translational delay, but how differential timing of individual transcripts is achieved was not known. This report describes the characterization of two related NDT80 -induced genes, PES4 and MIP6 , encoding predicted RNA binding proteins. These genes are necessary to regulate the steady-state expression, translational timing, and localization of a set of mRNAs that are transcribed by NDT80 but not translated until the end of meiosis II. Mutations in the predicted RNA binding domains within PES4 alter the stability of target mRNAs. PES4 and MIP6 affect only a small portion of the NDT80 regulon, indicating that they act as modulators of the general Ime2/Rim4 pathway for specific transcripts. Copyright © 2017 American Society for Microbiology.

  14. Growth and sporulation defects in Bacillus subtilis mutants with a single rrn operon can be suppressed by amplification of the rrn operon.

    Science.gov (United States)

    Yano, Koichi; Masuda, Kenta; Akanuma, Genki; Wada, Tetsuya; Matsumoto, Takashi; Shiwa, Yuh; Ishige, Taichiro; Yoshikawa, Hirofumi; Niki, Hironori; Inaoka, Takashi; Kawamura, Fujio

    2016-01-01

    The genome of Bacillus subtilis strain 168 encodes ten rRNA (rrn) operons. We previously reported that strains with only a single rrn operon had a decreased growth and sporulation frequency. We report here the isolation and characterization of suppressor mutants from seven strains that each have a single rrn operon (rrnO, A, J, I, E, D or B). The suppressor mutants for strain RIK656 with a single rrnO operon had a higher frequency of larger colonies. These suppressor mutants had not only increased growth rates, but also increased sporulation frequencies and ribosome levels compared to the parental mutant strain RIK656. Quantitative PCR analyses showed that all these suppressor mutants had an increased number of copies of the rrnO operon. Suppressor mutants were also isolated from the six other strains with single rrn operons (rrnA, J, I, E, D or B). Next generation and capillary sequencing showed that all of the suppressor mutants had tandem repeats of the chromosomal locus containing the remaining rrn operon (amplicon). These amplicons varied in size from approximately 9 to 179 kb. The amplifications were likely to be initiated by illegitimate recombination between non- or micro-homologous sequences, followed by unequal crossing-over during DNA replication. These results are consistent with our previous report that rrn operon copy number has a major role in cellular processes such as cell growth and sporulation.

  15. Modification of Einstein A Coefficient in Dissipative Gas Medium

    Science.gov (United States)

    Cao, Chang-Qi; Cao, Hui; Qin, Ke-Cheng

    1996-01-01

    Spontaneous radiation in dissipative gas medium such as plasmas is investigated by Langevin equations and the modified Weisskopf-Wigner approximation. Since the refractive index of gas medium is expected to be nearly unity, we shall first neglect the medium polarization effect. We show that absorption in plasmas may in certain case modify the Einstein A coefficient significantly and cause a pit in the A coefficient-density curves for relatively low temperature plasmas and also a pit in the A coefficient-temperature curves. In the next, the effect of medium polarization is taken into account in addition. To our surprise, its effect in certain case is quite significant. The dispersive curves show different behaviors in different region of parameters.

  16. Growth and sporulation of some pathogenic fungi in the presence of grapefruit extract.

    Science.gov (United States)

    Orlikowski, Leszek B; Skrzypczak, Cz; Jaworska-Marosz, A

    2002-01-01

    Development of Fusarium oxysporum f. sp. cyclaminis, F. oxysporum f. sp. dianthi, Botrytis cinerea and B. elliptica in the presence of grapefruit extract (GE) was evaluated. Amendment of potato-dextrose agar with 40 micrograms of GE/cm3 inhibited linear growth of tested species at least in 50%. Addition of 40 micrograms of GE/cm3 of medium inhibited spore germination of F. oxysporum f.sp. cyclaminis about 34% whereas germ tube growth was suppressed in 87%. In case of Botrytis species, B. cinerea spores were more susceptible on GE than B. elliptica. They did not germinate, however, at 200 micrograms of GE/cm3. Drenching of peat, artificially infested with F. oxysporum f. sp. dianthi, with GE at conc. 165 micrograms/cm3 resulted in drastical decrease of colony forming unit numbers and this suppressive effect was observed at least 35 days.

  17. QGP and Modified Jet Fragmentation

    International Nuclear Information System (INIS)

    Wang, Xin-Nian

    2005-01-01

    Recent progresses in the study of jet modification in hotmedium and their consequences in high-energy heavy-ion collisions are reviewed. In particular, I will discuss energy loss for propagating heavy quarks and the resulting modified fragmentation function. Medium modification of the parton fragmentation function due to quark recombination are formulated within finite temperature field theory and their implication on the search for deconfined quark-gluon plasma is also discussed

  18. In-medium pion valence distributions in a light-front model

    Energy Technology Data Exchange (ETDEWEB)

    Melo, J.P.B.C. de, E-mail: joao.mello@cruzeirodosul.edu.br [Laboratório de Física Teórica e Computacional – LFTC, Universidade Cruzeiro do Sul, 01506-000 São Paulo (Brazil); Tsushima, K. [Laboratório de Física Teórica e Computacional – LFTC, Universidade Cruzeiro do Sul, 01506-000 São Paulo (Brazil); Ahmed, I. [Laboratório de Física Teórica e Computacional – LFTC, Universidade Cruzeiro do Sul, 01506-000 São Paulo (Brazil); National Center for Physics, Quaidi-i-Azam University Campus, Islamabad 45320 (Pakistan)

    2017-03-10

    Pion valence distributions in nuclear medium and vacuum are studied in a light-front constituent quark model. The in-medium input for studying the pion properties is calculated by the quark-meson coupling model. We find that the in-medium pion valence distribution, as well as the in-medium pion valence wave function, are substantially modified at normal nuclear matter density, due to the reduction in the pion decay constant.

  19. Jet multiplicity distributions: medium dependence in MLLA

    Energy Technology Data Exchange (ETDEWEB)

    Armesto, Nestor; Pajares, Carlos; Quiroga-Arias, Paloma [Universidade de Santiago de Compostela, Departamento de Fisica de Particulas and IGFAE, Santiago de Compostela (Spain)

    2009-07-15

    We study the medium dependence of the multiplicity distributions in the modified leading logarithmic approximation. We focus in the enhancement in the number of branchings as the partons travel trough a dense medium created in a heavy-ion collision. We study the effect of a higher number of splittings in some jet observables by introducing the medium as a constant (f{sub med}) in the splitting functions. Having as our ansatz for the quark and gluon jets mean multiplicities left angle n{sub G} right angle =e{sup {gamma}}{sup y} and left angle n{sub Q} right angle =r{sup -1}e{sup {gamma}}{sup y}, we study in an analytic approach the dependence with the medium (f{sub med}) of the anomalous dimension ({gamma}), the multiplicity ratio (r), and so the mean multiplicities. We also obtain the higher-order moments of the multiplicity distribution, what allows us to study its dispersion. (orig.)

  20. DENSE MEDIUM CYCLONE OPTIMIZATON

    Energy Technology Data Exchange (ETDEWEB)

    Gerald H. Luttrell; Chris J. Barbee; Peter J. Bethell; Chris J. Wood

    2005-06-30

    Dense medium cyclones (DMCs) are known to be efficient, high-tonnage devices suitable for upgrading particles in the 50 to 0.5 mm size range. This versatile separator, which uses centrifugal forces to enhance the separation of fine particles that cannot be upgraded in static dense medium separators, can be found in most modern coal plants and in a variety of mineral plants treating iron ore, dolomite, diamonds, potash and lead-zinc ores. Due to the high tonnage, a small increase in DMC efficiency can have a large impact on plant profitability. Unfortunately, the knowledge base required to properly design and operate DMCs has been seriously eroded during the past several decades. In an attempt to correct this problem, a set of engineering tools have been developed to allow producers to improve the efficiency of their DMC circuits. These tools include (1) low-cost density tracers that can be used by plant operators to rapidly assess DMC performance, (2) mathematical process models that can be used to predict the influence of changes in operating and design variables on DMC performance, and (3) an expert advisor system that provides plant operators with a user-friendly interface for evaluating, optimizing and trouble-shooting DMC circuits. The field data required to develop these tools was collected by conducting detailed sampling and evaluation programs at several industrial plant sites. These data were used to demonstrate the technical, economic and environmental benefits that can be realized through the application of these engineering tools.

  1. Interfacial Modifiers

    Energy Technology Data Exchange (ETDEWEB)

    Martin, Ina; French, Roger H.

    2018-03-19

    Our project objective in the first and only Budget Period was to demonstrate the potential of nm-scale organofunctional silane coatings as a method of extending the lifetime of PV materials and devices. Specifically, the target was to double the lifetime performance of a laminated Cu(In,Ga)Se2 (CIGS) cell under real-world and accelerated aging exposure conditions. Key findings are that modification of aluminum-doped zinc oxide (AZO) films (materials used as transparent conductive oxide (TCO) top contacts) resulted in decreased degradation of optical and electrical properties under damp heat (DH) exposure compared to un-modified AZO. The most significant finding is that modification of the AZO top contact of full CIGS devices resulted in significantly improved properties under DH exposure compared to un-modified devices, by a factor of 4 after 1000 h. Results of this one-year project have demonstrated that surface functionalization is a viable pathway for extending the lifetime of state-of-the-art CIGS devices.

  2. Switch-like reprogramming of gene expression after fusion of multinucleate plasmodial cells of two Physarum polycephalum sporulation mutants

    Energy Technology Data Exchange (ETDEWEB)

    Walter, Pauline; Hoffmann, Xenia-Katharina; Ebeling, Britta; Haas, Markus; Marwan, Wolfgang, E-mail: wolfgang.marwan@ovgu.de

    2013-05-24

    Highlights: •We investigate reprogramming of gene expression in multinucleate single cells. •Cells of two differentiation control mutants are fused. •Fused cells proceed to alternative gene expression patterns. •The population of nuclei damps stochastic fluctuations in gene expression. •Dynamic processes of cellular reprogramming can be observed by repeated sampling of a cell. -- Abstract: Nonlinear dynamic processes involving the differential regulation of transcription factors are considered to impact the reprogramming of stem cells, germ cells, and somatic cells. Here, we fused two multinucleate plasmodial cells of Physarum polycephalum mutants defective in different sporulation control genes while being in different physiological states. The resulting heterokaryons established one of two significantly different expression patterns of marker genes while the plasmodial halves that were fused to each other synchronized spontaneously. Spontaneous synchronization suggests that switch-like control mechanisms spread over and finally control the entire plasmodium as a result of cytoplasmic mixing. Regulatory molecules due to the large volume of the vigorously streaming cytoplasm will define concentrations in acting on the population of nuclei and in the global setting of switches. Mixing of a large cytoplasmic volume is expected to damp stochasticity when individual nuclei deliver certain RNAs at low copy number into the cytoplasm. We conclude that spontaneous synchronization, the damping of molecular noise in gene expression by the large cytoplasmic volume, and the option to take multiple macroscopic samples from the same plasmodium provide unique options for studying the dynamics of cellular reprogramming at the single cell level.

  3. A versatile class of cell surface directional motors gives rise to gliding motility and sporulation in Myxococcus xanthus.

    Directory of Open Access Journals (Sweden)

    Morgane Wartel

    2013-12-01

    Full Text Available Eukaryotic cells utilize an arsenal of processive transport systems to deliver macromolecules to specific subcellular sites. In prokaryotes, such transport mechanisms have only been shown to mediate gliding motility, a form of microbial surface translocation. Here, we show that the motility function of the Myxococcus xanthus Agl-Glt machinery results from the recent specialization of a versatile class of bacterial transporters. Specifically, we demonstrate that the Agl motility motor is modular and dissociates from the rest of the gliding machinery (the Glt complex to bind the newly expressed Nfs complex, a close Glt paralogue, during sporulation. Following this association, the Agl system transports Nfs proteins directionally around the spore surface. Since the main spore coat polymer is secreted at discrete sites around the spore surface, its transport by Agl-Nfs ensures its distribution around the spore. Thus, the Agl-Glt/Nfs machineries may constitute a novel class of directional bacterial surface transporters that can be diversified to specific tasks depending on the cognate cargo and machinery-specific accessories.

  4. Switch-like reprogramming of gene expression after fusion of multinucleate plasmodial cells of two Physarum polycephalum sporulation mutants

    International Nuclear Information System (INIS)

    Walter, Pauline; Hoffmann, Xenia-Katharina; Ebeling, Britta; Haas, Markus; Marwan, Wolfgang

    2013-01-01

    Highlights: •We investigate reprogramming of gene expression in multinucleate single cells. •Cells of two differentiation control mutants are fused. •Fused cells proceed to alternative gene expression patterns. •The population of nuclei damps stochastic fluctuations in gene expression. •Dynamic processes of cellular reprogramming can be observed by repeated sampling of a cell. -- Abstract: Nonlinear dynamic processes involving the differential regulation of transcription factors are considered to impact the reprogramming of stem cells, germ cells, and somatic cells. Here, we fused two multinucleate plasmodial cells of Physarum polycephalum mutants defective in different sporulation control genes while being in different physiological states. The resulting heterokaryons established one of two significantly different expression patterns of marker genes while the plasmodial halves that were fused to each other synchronized spontaneously. Spontaneous synchronization suggests that switch-like control mechanisms spread over and finally control the entire plasmodium as a result of cytoplasmic mixing. Regulatory molecules due to the large volume of the vigorously streaming cytoplasm will define concentrations in acting on the population of nuclei and in the global setting of switches. Mixing of a large cytoplasmic volume is expected to damp stochasticity when individual nuclei deliver certain RNAs at low copy number into the cytoplasm. We conclude that spontaneous synchronization, the damping of molecular noise in gene expression by the large cytoplasmic volume, and the option to take multiple macroscopic samples from the same plasmodium provide unique options for studying the dynamics of cellular reprogramming at the single cell level

  5. Quaternary re-arrangement analysed by spectral enhancement: the interaction of a sporulation repressor with its antagonist.

    Science.gov (United States)

    Scott, D J; Leejeerajumnean, S; Brannigan, J A; Lewis, R J; Wilkinson, A J; Hoggett, J G

    1999-11-12

    The protein/protein interaction between SinI and SinR has been studied by analytical ultracentrifugation and gel electrophoresis in an attempt to understand how these proteins contribute to developmental control of sporulation in Bacillus subtilis. SinR was found to be tetrameric, while SinI was found to exist as monomers and dimers in a rapidly reversible equilibrium. Labelling of SinR by incorporating the tryptophan analogue 7-azatryptophan (7AW) into the protein in place of tryptophan shifts the UV absorbance spectrum, thus allowing selective monitoring of 7AWSinR at 315 nm using the UV absorption optics of the analytical ultracentrifuge. Selective monitoring of SinR in mixtures of SinR and SinI enables the binding and stoichiometry of the interaction to be investigated quantitatively and unambiguously. We demonstrate that the oligomeric forms of SinR and SinI re-arrange to form a tight 1:1 SinR:SinI complex, with no stable intermediate species. A fragment of SinR, SinR(1-69), which contains only the DNA-binding domain, was found to be monomeric, showing that the protein appears not to oligomerise in a similar manner to the Cro repressor, a protein with which it shares a marked structural similarity. Copyright 1999 Academic Press.

  6. Mutational analysis of the yeast TRAPP subunit Trs20p identifies roles in endocytic recycling and sporulation.

    Directory of Open Access Journals (Sweden)

    Hichem Mahfouz

    Full Text Available Trs20p is a subunit of the evolutionarily conserved TRAPP (TRAnsport Protein Particle complex that mediates various aspects of membrane trafficking. Three TRAPP complexes have been identified in yeast with roles in ER-to-Golgi trafficking, post-Golgi and endosomal-to-Golgi transport and in autophagy. The role of Trs20p, which is essential for viability and a component of all three complexes, and how it might function within each TRAPP complex, has not been clarified to date. To begin to address the role of Trs20p we generated different mutants by random mutagenesis but, surprisingly, no defects were observed in diverse anterograde transport pathways or general secretion in Trs20 temperature-sensitive mutants. Instead, mutation of Trs20 led to defects in endocytic recycling and a block in sporulation/meiosis. The phenotypes of different mutants appear to be separable suggesting that the mutations affect the function of Trs20 in different TRAPP complexes.

  7. Sporulation capability and amylosome conservation among diverse human colonic and rumen isolates of the keystone starch‐degrader Ruminococcus bromii

    Science.gov (United States)

    Mukhopadhya, Indrani; Moraïs, Sarah; Laverde‐Gomez, Jenny; Sheridan, Paul O.; Walker, Alan W.; Kelly, William; Klieve, Athol V.; Ouwerkerk, Diane; Duncan, Sylvia H.; Louis, Petra; Koropatkin, Nicole; Cockburn, Darrell; Kibler, Ryan; Cooper, Philip J.; Sandoval, Carlos; Crost, Emmanuelle; Juge, Nathalie; Bayer, Edward A.

    2017-01-01

    Summary Ruminococcus bromii is a dominant member of the human colonic microbiota that plays a ‘keystone’ role in degrading dietary resistant starch. Recent evidence from one strain has uncovered a unique cell surface ‘amylosome’ complex that organizes starch‐degrading enzymes. New genome analysis presented here reveals further features of this complex and shows remarkable conservation of amylosome components between human colonic strains from three different continents and a R. bromii strain from the rumen of Australian cattle. These R. bromii strains encode a narrow spectrum of carbohydrate active enzymes (CAZymes) that reflect extreme specialization in starch utilization. Starch hydrolysis products are taken up mainly as oligosaccharides, with only one strain able to grow on glucose. The human strains, but not the rumen strain, also possess transporters that allow growth on galactose and fructose. R. bromii strains possess a full complement of sporulation and spore germination genes and we demonstrate the ability to form spores that survive exposure to air. Spore formation is likely to be a critical factor in the ecology of this nutritionally highly specialized bacterium, which was previously regarded as ‘non‐sporing’, helping to explain its widespread occurrence in the gut microbiota through the ability to transmit between hosts. PMID:29159997

  8. Bitumen based modified substance

    International Nuclear Information System (INIS)

    Kostolanyi, P.

    1987-01-01

    The necessary amounts of tetrahydrosilicic acid and methyl phenyl silicon oil are added to molten bitumen heated to temperatures of 50 to 200 degC. The mixture is thoroughly mixed and let to cool. The structure of the product comes close to gel and its properties (penetration, softening point, workability time, penetration index) may be changed in dependence on the amount of additions and on the time and temperature of heating. The advantage of the thus prepared modified material is its shorter workability time, its ability to bind materials with a certain water content, and its relatively low price. It may be used for fixing and storing low-and medium-level radioactive organic and thickened waste waters. (E.S.)

  9. Computation as Medium

    DEFF Research Database (Denmark)

    Jochum, Elizabeth Ann; Putnam, Lance

    2017-01-01

    Artists increasingly utilize computational tools to generate art works. Computational approaches to art making open up new ways of thinking about agency in interactive art because they invite participation and allow for unpredictable outcomes. Computational art is closely linked...... to the participatory turn in visual art, wherein spectators physically participate in visual art works. Unlike purely physical methods of interaction, computer assisted interactivity affords artists and spectators more nuanced control of artistic outcomes. Interactive art brings together human bodies, computer code......, and nonliving objects to create emergent art works. Computation is more than just a tool for artists, it is a medium for investigating new aesthetic possibilities for choreography and composition. We illustrate this potential through two artistic projects: an improvisational dance performance between a human...

  10. Spiegel. Medium. Kunst

    DEFF Research Database (Denmark)

    Kacunko, Slavko

    of this kind as the marks of a meta-complex of method out of which new models of the image continually arise. The waxing intangibility of proliferating images be they of the mind, in dreams, through gestures, and the equally rampant growth of microstructuring in allocations of knowledge lay a challenge before...... to research. As a void in the apprehension of the world, the mirror obtained a scholarly perspective and the more so in areas beyond its own qualities as a medium, i.e. in images and metaphor, the paradigms of all research looking to image and text. This investigation sets out to comprehend paradoxes......, and space (albeit no expanse) is there to consider the methodological pros and cons of such a selective approach. Even in this synopsis, it has to be and can be stated that what makes for the affinities between psychological, literary and image-research approaches in research on the mirror is the shared...

  11. The diffuse interstellar medium

    Science.gov (United States)

    Cox, Donald P.

    1990-01-01

    The last 20 years of the efforts to understand the diffuse ISM are reviewed, with recent changes of fundamental aspects being highlighted. Attention is given to the interstellar pressure and its components, the weight of the ISM, the midplane pressure contributions, and pressure contributions at 1 kpc. What velocity dispersions, cosmic ray pressure, and magnetic field pressure that can be expected for a gas in a high magnetic field environment is addressed. The intercloud medium is described, with reference to the work of Cox and Slavin (1989). Various caveats are discussed and a number of areas for future investigation are identified. Steps that could be taken toward a successful phase segregation model are discussed.

  12. Optimization of nutritional requirements for mycelial growth and sporulation of entomogenous fungus Aschersonia aleyrodis Webber Otimização das exigências nutricionais para crescimento micelial e esporulação do fungo entomopatogênico Aschersonia aleyrodis Webber

    Directory of Open Access Journals (Sweden)

    Yanping Zhu

    2008-12-01

    Full Text Available The objective of the present study was to investigate the optimal nutritional requirements for mycelial growth and sporulation of entomopathogenic fungus Aschersonia aleyrodis Webber by orthogonal layout methods. Herein the order of effects of nutrient components on mycelial growth was tryptone > Ca2+ > soluble starch > folacin, corresponding to the following optimal concentrations: 1.58% Soluble Starch, 3.16% Tryptone, 0.2 mmol l-1 Ca2+ and 0.005% Folacin. The optimal concentration of each factors for sporulation was 1.16% lactose, 0.394% tryptone, 0.4 mmol l-1 Fe2+ and 0.00125% V B1, and the effects of medium components on sporulation were found to be in the order lactose > V B1 > Fe2+ > tryptone. Under the optimal culture conditions, the maximum production of mycelial growth achieved 20.05 g l-1 after 7 days of fermentation, while the maximum spore yield reached 5.23 ×10(10 spores l-1 after 22 days of cultivation. This is the first report on optimization of nutritional requirements and design of simplified semi-synthetic media for mycelial growth and sporulation of A. aleyrodis.O objetivo deste estudo foi investigar as exigências nutricionais ótimas para o crescimento micelial e esporulação do fungo entomopatogênico Aschersonia aleyrodis Webber. A ordem dos efeitos dos nutrientes na multiplicação micelial foi triptona>Ca2+>amido solúvel>folacina, com as seguintes concentrações ótimas: amido solúvel 1,58%, tritona 3,16%, Ca2+ 0,2mmol.l-1 e folacina 0,005%. Para a esporulação, a concentração ótima de cada fator foi: lactose 1,16%, triptona 0,394%, Fe2+ 0,4mmol.l-1 e V B1 0,00125%, na seguinte ordem: lactose> V B1> Fe2+>tritona. Em condições ótimas de cultura, a produção máxima de micélio foi 20,05g.l-1 após 7 dias de fermentação, enquanto o rendimento máximo de esporos foi 5,23 x 10(10 esporos.l-1 após 22 dias de cultivo. Esse é o primeiro relato sobre otimização das exigências nutricionais e desenvolvimento de

  13. Probing the nuclear medium with the K+ meson

    International Nuclear Information System (INIS)

    Chrien, R.E.

    1995-01-01

    Elastic differential cross sections for K + mesons scattered from targets of carbon and 6 Li have been measured at an incident momentum of 715 MeV/c. The ratios of scattering cross sections from these targets are not predicted by theory, and are consistent with earlier suggestions that the K + -nucleon interaction is modified in the nuclear medium

  14. Compost Addition Enhanced Hyphal Growth and Sporulation of Arbuscular Mycorrhizal Fungi without Affecting Their Community Composition in the Soil

    Directory of Open Access Journals (Sweden)

    Wei Yang

    2018-02-01

    Full Text Available Arbuscular mycorrhizal (AM fungi form symbiotic associations with most crop plant species in agricultural ecosystems, and are conspicuously influenced by various agricultural practices. To understand the impact of compost addition on AM fungi, we examined effect of four compost rates (0, 11.25, 22.5, and 45 Mg/ha on the abundance and community composition of AM fungi in seedling, flowering, and mature stage of soybean in a 1-year compost addition experiment system in Northeast China. Soybean [Glycine max (L. Merrill] was used as test plant. Moderate (22.5 Mg/ha and high (45 Mg/ha levels of compost addition significantly increased AM root colonization and extraradical hyphal (ERH density compared with control, whereas low (11.5 Mg/ha level of compost addition did not cause significant increase in AM root colonization and ERH density. AM fungal spore density was significantly enhanced by all the compost rates compared with control. The temporal variations analysis revealed that, AM root colonization in seedling stage was significantly lower than in flowering and mature stage. Although AM fungal operational taxonomic unit richness and community composition was unaffected by compost addition, some abundant AM fungal species showed significantly different response to compost addition. In mature stage, Rhizophagus fasciculatum showed increasing trend along with compost addition gradient, whereas the opposite was observed with Paraglomus sp. In addition, AM fungal community composition exhibited significant temporal variation during growing season. Further analysis indicated that the temporal variation in AM fungal community only occurred in control treatment, but not in low, moderate, and high level of compost addition treatments. Our findings highlighted the significant effects of compost addition on AM growth and sporulation, and emphasized that growth stage is a stronger determinant than 1-year compost addition in shaping AM fungal community in

  15. Compost Addition Enhanced Hyphal Growth and Sporulation of Arbuscular Mycorrhizal Fungi without Affecting Their Community Composition in the Soil.

    Science.gov (United States)

    Yang, Wei; Gu, Siyu; Xin, Ying; Bello, Ayodeji; Sun, Wenpeng; Xu, Xiuhong

    2018-01-01

    Arbuscular mycorrhizal (AM) fungi form symbiotic associations with most crop plant species in agricultural ecosystems, and are conspicuously influenced by various agricultural practices. To understand the impact of compost addition on AM fungi, we examined effect of four compost rates (0, 11.25, 22.5, and 45 Mg/ha) on the abundance and community composition of AM fungi in seedling, flowering, and mature stage of soybean in a 1-year compost addition experiment system in Northeast China. Soybean [ Glycine max (L.) Merrill] was used as test plant. Moderate (22.5 Mg/ha) and high (45 Mg/ha) levels of compost addition significantly increased AM root colonization and extraradical hyphal (ERH) density compared with control, whereas low (11.5 Mg/ha) level of compost addition did not cause significant increase in AM root colonization and ERH density. AM fungal spore density was significantly enhanced by all the compost rates compared with control. The temporal variations analysis revealed that, AM root colonization in seedling stage was significantly lower than in flowering and mature stage. Although AM fungal operational taxonomic unit richness and community composition was unaffected by compost addition, some abundant AM fungal species showed significantly different response to compost addition. In mature stage, Rhizophagus fasciculatum showed increasing trend along with compost addition gradient, whereas the opposite was observed with Paraglomus sp. In addition, AM fungal community composition exhibited significant temporal variation during growing season. Further analysis indicated that the temporal variation in AM fungal community only occurred in control treatment, but not in low, moderate, and high level of compost addition treatments. Our findings highlighted the significant effects of compost addition on AM growth and sporulation, and emphasized that growth stage is a stronger determinant than 1-year compost addition in shaping AM fungal community in black soil of

  16. Compost Addition Enhanced Hyphal Growth and Sporulation of Arbuscular Mycorrhizal Fungi without Affecting Their Community Composition in the Soil

    Science.gov (United States)

    Yang, Wei; Gu, Siyu; Xin, Ying; Bello, Ayodeji; Sun, Wenpeng; Xu, Xiuhong

    2018-01-01

    Arbuscular mycorrhizal (AM) fungi form symbiotic associations with most crop plant species in agricultural ecosystems, and are conspicuously influenced by various agricultural practices. To understand the impact of compost addition on AM fungi, we examined effect of four compost rates (0, 11.25, 22.5, and 45 Mg/ha) on the abundance and community composition of AM fungi in seedling, flowering, and mature stage of soybean in a 1-year compost addition experiment system in Northeast China. Soybean [Glycine max (L.) Merrill] was used as test plant. Moderate (22.5 Mg/ha) and high (45 Mg/ha) levels of compost addition significantly increased AM root colonization and extraradical hyphal (ERH) density compared with control, whereas low (11.5 Mg/ha) level of compost addition did not cause significant increase in AM root colonization and ERH density. AM fungal spore density was significantly enhanced by all the compost rates compared with control. The temporal variations analysis revealed that, AM root colonization in seedling stage was significantly lower than in flowering and mature stage. Although AM fungal operational taxonomic unit richness and community composition was unaffected by compost addition, some abundant AM fungal species showed significantly different response to compost addition. In mature stage, Rhizophagus fasciculatum showed increasing trend along with compost addition gradient, whereas the opposite was observed with Paraglomus sp. In addition, AM fungal community composition exhibited significant temporal variation during growing season. Further analysis indicated that the temporal variation in AM fungal community only occurred in control treatment, but not in low, moderate, and high level of compost addition treatments. Our findings highlighted the significant effects of compost addition on AM growth and sporulation, and emphasized that growth stage is a stronger determinant than 1-year compost addition in shaping AM fungal community in black soil of

  17. Heat shock and prolonged heat stress attenuate neurotoxin and sporulation gene expression in group I Clostridium botulinum strain ATCC 3502.

    Science.gov (United States)

    Selby, Katja; Mascher, Gerald; Somervuo, Panu; Lindström, Miia; Korkeala, Hannu

    2017-01-01

    Foodborne pathogenic bacteria are exposed to a number of environmental stresses during food processing, storage, and preparation, and in the human body. In order to improve the safety of food, the understanding of molecular stress response mechanisms foodborne pathogens employ is essential. Many response mechanisms that are activated during heat shock may cross-protect bacteria against other environmental stresses. To better understand the molecular mechanisms Clostridium botulinum, the causative agent of botulism, utilizes during acute heat stress and during adaptation to stressfully high temperature, the C. botulinum Group I strain ATCC 3502 was grown in continuous culture at 39°C and exposed to heat shock at 45°C, followed by prolonged heat stress at 45°C to allow adaptation of the culture to the high temperature. Growth in continuous culture was performed to exclude secondary growth phase effects or other environmental impacts on bacterial gene transcription. Changes in global gene expression profiles were studied using DNA microarray hybridization. During acute heat stress, Class I and III heat shock genes as well as members of the SOS regulon were activated. The neurotoxin gene botA and genes encoding the neurotoxin-associated proteins were suppressed throughout the study. Prolonged heat stress led to suppression of the sporulation machinery whereas genes related to chemotaxis and motility were activated. Induced expression of a large proportion of prophage genes was detected, suggesting an important role of acquired genes in the stress resistance of C. botulinum. Finally, changes in the expression of a large number of genes related to carbohydrate and amino acid metabolism indicated remodeling of the cellular metabolism.

  18. Effect of Temperature on Growth and Sporulation of US-22, US-23, and US-24 Clonal Lineages of Phytophthora infestans and Implications for Late Blight Epidemiology.

    Science.gov (United States)

    Seidl Johnson, Anna C; Frost, Kenneth E; Rouse, Douglas I; Gevens, Amanda J

    2015-04-01

    Epidemics of late blight, caused by Phytophthora infestans (Mont.) de Bary, have been studied by plant pathologists and regarded with great concern by potato and tomato growers since the Irish potato famine in the 1840s. P. infestans populations have continued to evolve, with unique clonal lineages arising which differ in pathogen fitness and pathogenicity, potentially impacting epidemiology. In 2012 and 2013, the US-23 clonal lineage predominated late blight epidemics in most U.S. potato and tomato production regions, including Wisconsin. This lineage was unknown prior to 2009. For isolates of three recently identified clonal lineages of P. infestans (US-22, US-23, and US-24), sporulation rates were experimentally determined on potato and tomato foliage and the effect of temperature on lesion growth rate on tomato was investigated. The US-22 and US-23 isolates had greater lesion growth rates on tomato than US-24 isolates. Sporulation rates for all isolates were greater on potato than tomato, and the US-23 isolates had greater sporulation rates on both tomato and potato than the US-22 and US-24 isolates. Experimentally determined correlates of fitness were input to the LATEBLIGHT model and epidemics were simulated using archived Wisconsin weather data from four growing seasons (2009 to 2012) to investigate the effect of isolates of these new lineages on late blight epidemiology. The fast lesion growth rates of US-22 and US-23 isolates resulted in severe epidemics in all years tested, particularly in 2011. The greater sporulation rates of P. infestans on potato resulted in simulated epidemics that progressed faster than epidemics simulated for tomato; the high sporulation rates of US-23 isolates resulted in simulated epidemics more severe than simulated epidemics of isolates of the US-22 and US-24 isolates and EC-1 clonal lineages on potato and tomato. Additionally, US-23 isolates consistently caused severe simulated epidemics when lesion growth rate and sporulation

  19. The Conserved Actinobacterial Two-Component System MtrAB Coordinates Chloramphenicol Production with Sporulation in Streptomyces venezuelae NRRL B-65442

    Directory of Open Access Journals (Sweden)

    Nicolle F. Som

    2017-06-01

    Full Text Available Streptomyces bacteria make numerous secondary metabolites, including half of all known antibiotics. Production of antibiotics is usually coordinated with the onset of sporulation but the cross regulation of these processes is not fully understood. This is important because most Streptomyces antibiotics are produced at low levels or not at all under laboratory conditions and this makes large scale production of these compounds very challenging. Here, we characterize the highly conserved actinobacterial two-component system MtrAB in the model organism Streptomyces venezuelae and provide evidence that it coordinates production of the antibiotic chloramphenicol with sporulation. MtrAB are known to coordinate DNA replication and cell division in Mycobacterium tuberculosis where TB-MtrA is essential for viability but MtrB is dispensable. We deleted mtrB in S. venezuelae and this resulted in a global shift in the metabolome, including constitutive, higher-level production of chloramphenicol. We found that chloramphenicol is detectable in the wild-type strain, but only at very low levels and only after it has sporulated. ChIP-seq showed that MtrA binds upstream of DNA replication and cell division genes and genes required for chloramphenicol production. dnaA, dnaN, oriC, and wblE (whiB1 are DNA binding targets for MtrA in both M. tuberculosis and S. venezuelae. Intriguingly, over-expression of TB-MtrA and gain of function TB- and Sv-MtrA proteins in S. venezuelae also switched on higher-level production of chloramphenicol. Given the conservation of MtrAB, these constructs might be useful tools for manipulating antibiotic production in other filamentous actinomycetes.

  20. The Bacillus subtilis yaaH Gene Is Transcribed by SigE RNA Polymerase during Sporulation, and Its Product Is Involved in Germination of Spores

    Science.gov (United States)

    Kodama, Takeko; Takamatsu, Hiromu; Asai, Kei; Kobayashi, Kazuo; Ogasawara, Naotake; Watabe, Kazuhito

    1999-01-01

    The expression of 21 novel genes located in the region from dnaA to abrB of the Bacillus subtilis chromosome was analyzed. One of the genes, yaaH, had a predicted promoter sequence conserved among SigE-dependent genes. Northern blot analysis revealed that yaaH mRNA was first detected from 2 h after the cessation of logarithmic growth (T2) of sporulation in wild-type cells and in spoIIIG (SigG−) and spoIVCB (SigK−) mutants but not in spoIIAC (SigF−) and spoIIGAB (SigE−) mutants. The transcription start point was determined by primer extension analysis; the −10 and −35 regions are very similar to the consensus sequences recognized by SigE-containing RNA polymerase. A YaaH-His tag fusion encoded by a plasmid with a predicted promoter for the yaaH gene was produced from T2 of sporulation in a B. subtilis transformant and extracted from mature spores, indicating that the yaaH gene product is a spore protein. Inactivation of the yaaH gene by insertion of an erythromycin resistance gene did not affect vegetative growth or spore resistance to heat, chloroform, and lysozyme. The germination of yaaH mutant spores in a mixture of l-asparagine, d-glucose, d-fructose, and potassium chloride was almost the same as that of wild-type spores, but the mutant spores were defective in l-alanine-stimulated germination. These results suggest that yaaH is a novel gene encoding a spore protein produced in the mother cell compartment from T2 of sporulation and that it is required for the l-alanine-stimulated germination pathway. PMID:10419957

  1. The Bacillus subtilis yaaH Gene Is Transcribed by SigE RNA Polymerase during Sporulation, and Its Product Is Involved in Germination of Spores

    OpenAIRE

    Kodama, Takeko; Takamatsu, Hiromu; Asai, Kei; Kobayashi, Kazuo; Ogasawara, Naotake; Watabe, Kazuhito

    1999-01-01

    The expression of 21 novel genes located in the region from dnaA to abrB of the Bacillus subtilis chromosome was analyzed. One of the genes, yaaH, had a predicted promoter sequence conserved among SigE-dependent genes. Northern blot analysis revealed that yaaH mRNA was first detected from 2 h after the cessation of logarithmic growth (T2) of sporulation in wild-type cells and in spoIIIG (SigG−) and spoIVCB (SigK−) mutants but not in spoIIAC (SigF−) and spoIIGAB (SigE−) mutants. The transcript...

  2. Mesons in the nuclear Medium

    CERN Document Server

    Kotulla, M

    2006-01-01

    We discuss recent experimental results on the modification of hadron properties in a nuclear medium. Particular emphasis is placed on an $\\omega$ production experiment performed by the CBELSA/TAPS collaboration at the ELSA accelerator. The data shows a smaller $\\omega$ meson mass together with a significant increase of its width in the nuclear medium.

  3. Microarray Analysis of Transposon Insertion Mutants in Bacillus Anthracis: Global Identification of Genes Required for Sporulation and Germination

    National Research Council Canada - National Science Library

    Day , Jr., William A; Rasmussen, Suzanne L; Carpenter, Beth M; Peterson, Scott N; Friedlander, Arthur M

    2007-01-01

    .... The system, used to identify genes required for generation of the infectious anthrax spore, spore germination and optimal growth on rich medium, was predictive of the contribution of two conserved...

  4. Phosphonium modified clay/polyimide nanocomposites

    International Nuclear Information System (INIS)

    Ceylan, Hatice; Çakmakçi, Emrah; Beyler-Çiǧil, Asli; Kahraman, Memet Vezir

    2014-01-01

    In this study, octyltriphenylphosphonium bromide [OTPP-Br] was prepared from the reaction of triphenylphosphine and 1 -bromooctane. The modification of clay was done by ion exchange reaction using OTPP-Br in water medium. Poly(amic acid) was prepared from the reaction of 3,3',4,4'-Benzophenonetetracarboxylic dianhydride (BTDA) and 4,4'-Oxydianiline (ODA). Polyimide(PI)/clay hybrids were prepared by blending of poly(amic acid) and organically modified clay as a type of layered clays. The morphology of the Polyimide/ phosphonium modified clay hybrids was characterized by scanning electron microscopy (SEM). Chemical structures of polyimide and Polyimide/ phosphonium modified clay hybrids were characterized by FTIR. SEM and FTIR results showed that the Polyimide/ phosphonium modified clay hybrids were successfully prepared. Thermal properties of the Polyimide/ phosphonium modified clay hybrids were characterized by thermogravimetric analysis (TGA)

  5. Pions in the nuclear medium

    International Nuclear Information System (INIS)

    Chanfray, G.

    1996-07-01

    We discuss various aspects of pion physics in the nuclear medium. We first study s-wave pion-nucleus interaction in connection with chiral symmetry restoration and quark condensate in the nuclear medium. We then address the question of p-wave pion-nucleus interaction and collective pionic modes in nuclei and draw the consequences for in medium ππ correlations especially in the scalar-isoscalar channel. We finally discuss the modification of the rho meson mass spectrum at finite density and/or temperature in connection with relativistic heavy ion collisions

  6. Medium modifications of vector mesons

    International Nuclear Information System (INIS)

    Pant, L.M.

    2004-01-01

    The omega photoproduction in nuclear medium with the ELSA facility at Bonn and the present status of the HADES collaboration to investigate the in-medium hadron properties in proton, heavy ions and hadron induced reactions at GSI, Darmstadt are presented. Efforts are under way to utilise the electron beam at Indore for experimental hadron physics in order to step into the intermediate energy nuclear physics regime. The skeletal outline of the high energy electron beam now available at CAT, Indore is discussed

  7. Medium effects in direct reactions

    International Nuclear Information System (INIS)

    Karakoc, M; Bertulani, C

    2013-01-01

    We discuss medium corrections of the nucleon-nucleon (NN) cross sections and their influence on direct reactions at intermediate energies ≳50 MeV/nucleon. The results obtained with free NN cross sections are compared with those obtained with a geometrical treatment of Pauli-blocking and Dirac-Bruecker methods. We show that medium corrections may lead to sizable modifications for collisions at intermediate energies and that they are more pronounced in reactions involving weakly bound nuclei.

  8. Medium-size power plants. Economic options

    International Nuclear Information System (INIS)

    Vogelweith, L.; Baujat, J.; Goutail, J.

    1978-01-01

    In this paper the authors describe a method for economic evaluation of a nuclear power plant project such as advocated by the IAEA but modified through the introduction of various parameters that may affect the evaluation, i.e. the weighted evaluation rate, the annual increase in the cost of fuel, and the discount rate. The method is applied to barge-based medium-size reactors (125 MW(e)). The authors calculate the investment cost, together with the costs of administration, operation and maintenance; use is made of current assumptions regarding the price of fuel for the case of a reference nuclear plant and an oil-fired plant of the same power and in the same programme. In this way the authors derive the discounted cost of the nuclear programme and concurrent conventional programme on the basis of the following assumptions: a weighted inflation rate varying between 0 and 6% per year; an annual increase in real fuel prices ranging from 0 to 3%; and a real discount rate, equal to the real interest rate, varying between 4 and 7% per year and corresponding to nominal discount rates of up to 13.4%. The conclusion reached is that, given the real interest rates actually prevailing on the financial market, a weighted inflation rate foreseen by the majority of experts, and a rise in real fuel prices of the order of 1% per year, the medium-size nuclear power plant is more economical than a conventional plant of the same output. (author)

  9. Dual Regulation of Bacillus subtilis kinB Gene Encoding a Sporulation Trigger by SinR through Transcription Repression and Positive Stringent Transcription Control.

    Science.gov (United States)

    Fujita, Yasutaro; Ogura, Mitsuo; Nii, Satomi; Hirooka, Kazutake

    2017-01-01

    It is known that transcription of kinB encoding a trigger for Bacillus subtilis sporulation is under repression by SinR, a master repressor of biofilm formation, and under positive stringent transcription control depending on the adenine species at the transcription initiation nucleotide (nt). Deletion and base substitution analyses of the kinB promoter (P kinB ) region using lacZ fusions indicated that either a 5-nt deletion (Δ5, nt -61/-57, +1 is the transcription initiation nt) or the substitution of G at nt -45 with A (G-45A) relieved kinB repression. Thus, we found a pair of SinR-binding consensus sequences (GTTCTYT; Y is T or C) in an inverted orientation (SinR-1) between nt -57/-42, which is most likely a SinR-binding site for kinB repression. This relief from SinR repression likely requires SinI, an antagonist of SinR. Surprisingly, we found that SinR is essential for positive stringent transcription control of P kinB . Electrophoretic mobility shift assay (EMSA) analysis indicated that SinR bound not only to SinR-1 but also to SinR-2 (nt -29/-8) consisting of another pair of SinR consensus sequences in a tandem repeat arrangement; the two sequences partially overlap the '-35' and '-10' regions of P kinB . Introduction of base substitutions (T-27C C-26T) in the upstream consensus sequence of SinR-2 affected positive stringent transcription control of P kinB , suggesting that SinR binding to SinR-2 likely causes this positive control. EMSA also implied that RNA polymerase and SinR are possibly bound together to SinR-2 to form a transcription initiation complex for kinB transcription. Thus, it was suggested in this work that derepression of kinB from SinR repression by SinI induced by Spo0A∼P and occurrence of SinR-dependent positive stringent transcription control of kinB might induce effective sporulation cooperatively, implying an intimate interplay by stringent response, sporulation, and biofilm formation.

  10. The local interstellar medium and gamma-ray astronomy

    International Nuclear Information System (INIS)

    Lebrun, F.; Paul, J.

    1985-08-01

    The recent improvement of the calibration of the galaxy counts used as an interstellar-absorption tracer modifies significantly the picture of the local interstellar medium (ISM). Consequently, previous analyses of the γ-ray emission from the local ISM involving galaxy counts have to be revised. In this paper, we consider the implications regarding the cosmic-ray (CR) density in the local ISM, and in particular within Loop I, a nearby supernova remnant (SNR)

  11. Interstellar dust within the life cycle of the interstellar medium

    OpenAIRE

    Demyk K.

    2012-01-01

    Cosmic dust is omnipresent in the Universe. Its presence influences the evolution of the astronomical objects which in turn modify its physical and chemical properties. The nature of cosmic dust, its intimate coupling with its environment, constitute a rich field of research based on observations, modelling and experimental work. This review presents the observations of the different components of interstellar dust and discusses their evolution during the life cycle of the interstellar medium.

  12. Induction of sporulation and the influence of time, temperature, and inoculum size on growth in two species of aquatic fungi (Saprolegniales)

    Science.gov (United States)

    Bailey, T.A.; Bradford, K.; Bland, C.E.

    1990-01-01

    Because the infective stage of most mycoses of aquatic organisms is the zoospore, we attempted to establish optimum conditions under which zoospores could be produced for use in antifungal testing. Optimum sporulation time, incubation time, inoculum size, and growth temperature were determined for each oftwo saprolegniaceous fungi, Achlya flagellata Coker and Saprolegnia hypogyna (Pringsheim) de Bary. Both species produced the largest number of zoospores after 18 hours (51.7 spores/ml for A. jlagellata and 848.0 spores/ml for S. hypogyna), and yielded maximum growth after 48 hours at 22 'C. The recommended test inoculum size for S. hypogyna (5,600 spores/ml was nearly three times that for A. flagellata (2,000 spores/ml),

  13. Comparative studies with regard to the influence of carbon and nitrogen ratio on sporulation in Fusarium oxysporum and Fusarium moniliforme v. subglutinans.

    Science.gov (United States)

    Prasad, M

    1979-01-01

    Carbon/nitrogen ratio as a factor for sporulation, expressed in terms of magnitude of population variation of macroconidia and microconidia in the cultures of Eusarium oxysporum Schlecht ex. Fr., Fusarium moniliforme v. subglutinans Wr. and Rg., and of chlamydospores (only in Fusarium oxysporum) was investigated. It has been found that the amount of carbon source shapes the course of macro- and micro. conidial production in a linear fashion, being enhanced parallel to the increase in its amount-Nitrogen level, limiting proliferation and effectively diminishing the macro- and micro-conidial population, varies for the two species, namely Fusarium oxysporum and Fusarium moniliforme v-subglutinans. For chlamydomspore production, higher carbon and still higher nitrogen concentration favours profuse proliferation in case of Fusarium oxysporum.

  14. Properties of the nuclear medium

    International Nuclear Information System (INIS)

    Baldo, M; Burgio, G F

    2012-01-01

    We review our knowledge on the properties of the nuclear medium that have been studied, over many years, on the basis of many-body theory, laboratory experiments and astrophysical observations. Throughout the presentation particular emphasis is placed on the possible relationship and links between the nuclear medium and the structure of nuclei, including the limitations of such an approach. First we consider the realm of phenomenological laboratory data and astrophysical observations and the hints they can give on the characteristics that the nuclear medium should possess. The analysis is based on phenomenological models, that however have a strong basis on physical intuition and an impressive success. More microscopic models are also considered, and it is shown that they are able to give invaluable information on the nuclear medium, in particular on its equation of state. The interplay between laboratory experiments and astrophysical observations is particularly stressed, and it is shown how their complementarity enormously enriches our insights into the structure of the nuclear medium. We then introduce the nucleon–nucleon interaction and the microscopic many-body theory of nuclear matter, with a critical discussion about the different approaches and their results. The Landau–Fermi liquid theory is introduced and briefly discussed, and it is shown how fruitful it can be in discussing the macroscopic and low-energy properties of the nuclear medium. As an illustrative example, we discuss neutron matter at very low density, and it is shown how it can be treated within the many-body theory. The general bulk properties of the nuclear medium are reviewed to indicate at which stage of our knowledge we stand, taking into account the most recent developments both in theory and experiments. A section is dedicated to the pairing problem. The connection with nuclear structure is then discussed, on the basis of the energy density functional method. The possibility of

  15. Repression of Middle Sporulation Genes in Saccharomyces cerevisiae by the Sum1-Rfm1-Hst1 Complex Is Maintained by Set1 and H3K4 Methylation

    Science.gov (United States)

    Jaiswal, Deepika; Jezek, Meagan; Quijote, Jeremiah; Lum, Joanna; Choi, Grace; Kulkarni, Rushmie; Park, DoHwan; Green, Erin M.

    2017-01-01

    The conserved yeast histone methyltransferase Set1 targets H3 lysine 4 (H3K4) for mono, di, and trimethylation and is linked to active transcription due to the euchromatic distribution of these methyl marks and the recruitment of Set1 during transcription. However, loss of Set1 results in increased expression of multiple classes of genes, including genes adjacent to telomeres and middle sporulation genes, which are repressed under normal growth conditions because they function in meiotic progression and spore formation. The mechanisms underlying Set1-mediated gene repression are varied, and still unclear in some cases, although repression has been linked to both direct and indirect action of Set1, associated with noncoding transcription, and is often dependent on the H3K4me2 mark. We show that Set1, and particularly the H3K4me2 mark, are implicated in repression of a subset of middle sporulation genes during vegetative growth. In the absence of Set1, there is loss of the DNA-binding transcriptional regulator Sum1 and the associated histone deacetylase Hst1 from chromatin in a locus-specific manner. This is linked to increased H4K5ac at these loci and aberrant middle gene expression. These data indicate that, in addition to DNA sequence, histone modification status also contributes to proper localization of Sum1. Our results also show that the role for Set1 in middle gene expression control diverges as cells receive signals to undergo meiosis. Overall, this work dissects an unexplored role for Set1 in gene-specific repression, and provides important insights into a new mechanism associated with the control of gene expression linked to meiotic differentiation. PMID:29066473

  16. Two COWP-like cysteine rich proteins from Eimeria nieschulzi (coccidia, apicomplexa) are expressed during sporulation and involved in the sporocyst wall formation.

    Science.gov (United States)

    Jonscher, Ernst; Erdbeer, Alexander; Günther, Marie; Kurth, Michael

    2015-07-25

    The family of cysteine rich proteins of the oocyst wall (COWPs) originally described in Cryptosporidium can also be found in Toxoplasma gondii (TgOWPs) localised to the oocyst wall as well. Genome sequence analysis of Eimeria suggests that these proteins may also exist in this genus and led us to the assumption that these proteins may also play a role in oocyst wall formation. In this study, COWP-like encoding sequences had been identified in Eimeria nieschulzi. The predicted gene sequences were subsequently utilized in reporter gene assays to observe time of expression and localisation of the reporter protein in vivo. Both investigated proteins, EnOWP2 and EnOWP6, were expressed during sporulation. The EnOWP2-promoter driven mCherry was found in the cytoplasm and the EnOWP2, respectively EnOWP6, fused to mCherry was initially observed in the extracytoplasmatic space between sporoblast and oocyst wall. This, so far unnamed compartment was designated as circumplasm. Later, the mCherry reporter co-localised with the sporocyst wall of the sporulated oocysts. This observation had been confirmed by confocal microscopy, excystation experiments and IFA. Transcript analysis revealed the intron-exon structure of these genes and confirmed the expression of EnOWP2 and EnOWP6 during sporogony. Our results allow us to assume a role, of both investigated EnOWP proteins, in the sporocyst wall formation of E. nieschulzi. Data mining and sequence comparisons to T. gondii and other Eimeria species allow us to hypothesise a conserved process within the coccidia. A role in oocyst wall formation had not been observed in E. nieschulzi.

  17. C. difficile 630Δerm Spo0A regulates sporulation, but does not contribute to toxin production, by direct high-affinity binding to target DNA.

    Directory of Open Access Journals (Sweden)

    Katharina E Rosenbusch

    Full Text Available Clostridium difficile is a Gram positive, anaerobic bacterium that can form highly resistant endospores. The bacterium is the causative agent of C. difficile infection (CDI, for which the symptoms can range from a mild diarrhea to potentially fatal pseudomembranous colitis and toxic megacolon. Endospore formation in Firmicutes, including C. difficile, is governed by the key regulator for sporulation, Spo0A. In Bacillus subtilis, this transcription factor is also directly or indirectly involved in various other cellular processes. Here, we report that C. difficile Spo0A shows a high degree of similarity to the well characterized B. subtilis protein and recognizes a similar binding sequence. We find that the laboratory strain C. difficile 630Δerm contains an 18bp-duplication near the DNA-binding domain compared to its ancestral strain 630. In vitro binding assays using purified C-terminal DNA binding domain of the C. difficile Spo0A protein demonstrate direct binding to DNA upstream of spo0A and sigH, early sporulation genes and several other putative targets. In vitro binding assays suggest that the gene encoding the major clostridial toxin TcdB may be a direct target of Spo0A, but supernatant derived from a spo0A negative strain was no less toxic towards Vero cells than that obtained from a wild type strain, in contrast to previous reports. These results identify for the first time direct (putative targets of the Spo0A protein in C. difficile and make a positive effect of Spo0A on production of the large clostridial toxins unlikely.

  18. Heavy Scalar, Vector, and Axial-Vector Mesons in Hot and Dense Nuclear Medium

    Directory of Open Access Journals (Sweden)

    Arvind Kumar

    2014-01-01

    Full Text Available In this work we shall investigate the mass modifications of scalar mesons (D0; B0, vector mesons (D*; B*, and axial-vector mesons (D1; B1 at finite density and temperature of the nuclear medium. The above mesons are modified in the nuclear medium through the modification of quark and gluon condensates. We will find the medium modification of quark and gluon condensates within chiral SU(3 model through the medium modification of scalar-isoscalar fields σ and ζ at finite density and temperature. These medium modified quark and gluon condensates will further be used through QCD sum rules for the evaluation of in-medium properties of the above mentioned scalar, vector, and axial vector mesons. We will also discuss the effects of density and temperature of the nuclear medium on the scattering lengths of the above scalar, vector, and axial-vector mesons. The study of the medium modifications of the above mesons may be helpful for understanding their production rates in heavy-ion collision experiments. The results of present investigations of medium modifications of scalar, vector, and axial-vector mesons at finite density and temperature can be verified in the compressed baryonic matter (CBM experiment of FAIR facility at GSI, Germany.

  19. 1 Medium Regiment, (SAHA), SAA

    African Journals Online (AJOL)

    Scientia Militaria: South African Journal of Military Studies. Journal Home · ABOUT THIS JOURNAL · Advanced Search · Current Issue · Archives · Journal Home > Vol 16, No 4 (1986) >. Log in or Register to get access to full text downloads. Username, Password, Remember me, or Register. 1 Medium Regiment, (S.A.H.A.), ...

  20. Hadron photoproduction at medium energy

    International Nuclear Information System (INIS)

    Dainton, J.B.

    1985-04-01

    Results from measurements of multibody photoproduction at medium incident photon energy (2.8 to 4.8 GeV) are presented and discussed. Particular emphasis is placed on topics which are not well understood and which therefore motivate experiments with the upgraded electron accelerator and storage ring ELSA at the University of Bonn, FR Germany. (author)

  1. Animal Locomotion in Different Mediums

    Indian Academy of Sciences (India)

    Wetlands are repositories of unique biodiversity. Wetlandorganisms are well adapted to their habitat, lying at theinterface of aquatic and terrestrial environments. In order tounderstand their adaptations in a better way, it is essential tograsp the basic properties of the medium in which variousorganisms live. This is attempted ...

  2. Estudos sobre a esporulação de uma amostra de bacillus: IV - Outras evidências sobre a atividade do íon Mn[2+] na esporulação endotrófica Studies on the sporulation of a Bacillus strain: IV - Further evidences of the Mn[2+] ion activity in the endotrophic sporulation

    Directory of Open Access Journals (Sweden)

    Leon Rabinovitch

    1973-01-01

    Full Text Available Foram feitas experimentações om o intuito de se buscar mais evidências sobre a participação do íon Mn[2+] no mecanismo esporogenético de uma amostra de Bacillus licheniformis. Quando as formas vegetativas desta bactéria eram depositadas em um meio mineral, carente de fonte de carbono utilizável, em conjunto com um agente seqüestrante de metais como EDTA, a esporulação endotrófica deixava de ocorrer. Entretanto, a esporulação pôde ser protegida quando as células eram previamente saturadas com um excesso de Mn[2+] exógeno. As formas esporuladas obtidas nas condições estudadas mostraram termorresistência a 85ºC durante 20 minutos.In the present paper the authors bring out more evidences concerning the influence of Mn[2+] ion on the endotrophic sporulation of Bacillus licheniformis-2390. Vegetative cells of this bacteria could not sporulate if they were submited to a sufficient concentration of EDTA. Otherwise, this sporulatio ocurred when the vegetative forms were first protected by an excess of exogenous Mn[2+] of Zn[2+], Fe[2+] and Mg[2+]. Those spores obtained shown thermoresistence to 85ºC during 20 minutes.

  3. Medium Modifications of Hadron Properties and Partonic Processes

    Energy Technology Data Exchange (ETDEWEB)

    Brooks, W. K.; Strauch, S.; Tsushima, K.

    2011-06-01

    Chiral symmetry is one of the most fundamental symmetries in QCD. It is closely connected to hadron properties in the nuclear medium via the reduction of the quark condensate , manifesting the partial restoration of chiral symmetry. To better understand this important issue, a number of Jefferson Lab experiments over the past decade have focused on understanding properties of mesons and nucleons in the nuclear medium, often benefiting from the high polarization and luminosity of the CEBAF accelerator. In particular, a novel, accurate, polarization transfer measurement technique revealed for the first time a strong indication that the bound proton electromagnetic form factors in 4He may be modified compared to those in the vacuum. Second, the photoproduction of vector mesons on various nuclei has been measured via their decay to e+e- to study possible in-medium effects on the properties of the rho meson. In this experiment, no significant mass shift and some broadening consistent with expected collisional broadening for the rho meson has been observed, providing tight constraints on model calculations. Finally, processes involving in-medium parton propagation have been studied. The medium modifications of the quark fragmentation functions have been extracted with much higher statistical accuracy than previously possible.

  4. Characterization of modified clinoptilolite

    International Nuclear Information System (INIS)

    Novosad, J.; Jandl, J.; Woollins, J.D.

    1992-01-01

    Samples of clinoptilolite were modified using insoluble hexacyanoferrate from aqueous solution. The modified samples were characterized by elemental analysis, powder X-ray diffraction, solid state NMR and vibrational spectroscopy. The sorption properties of modified clinoptilolite were studied, too. Higher affinity for 137 Cs sorption in comparison with the natural clinoptilolite has been proved. (author) 5 refs.; 3 figs.; 2 tabs

  5. Holographic Renormalization in Dense Medium

    International Nuclear Information System (INIS)

    Park, Chanyong

    2014-01-01

    The holographic renormalization of a charged black brane with or without a dilaton field, whose dual field theory describes a dense medium at finite temperature, is investigated in this paper. In a dense medium, two different thermodynamic descriptions are possible due to an additional conserved charge. These two different thermodynamic ensembles are classified by the asymptotic boundary condition of the bulk gauge field. It is also shown that in the holographic renormalization regularity of all bulk fields can reproduce consistent thermodynamic quantities and that the Bekenstein-Hawking entropy is nothing but the renormalized thermal entropy of the dual field theory. Furthermore, we find that the Reissner-Nordström AdS black brane is dual to a theory with conformal matter as expected, whereas a charged black brane with a nontrivial dilaton profile is mapped to a theory with nonconformal matter although its leading asymptotic geometry still remains as AdS space

  6. Medium modifications with recoil polarization

    Energy Technology Data Exchange (ETDEWEB)

    Brand, J.F.J. van den [Nationaal Instituut voor Kernfysica en Hoge Energiefysica, Amsterdam (Netherlands); Ent, R. [CEBAF, Newport News, VA (United States)

    1994-04-01

    The authors show that the virtual Compton scattering process allows for a precise study of the off-shell electron-nucleon vertex. In a separable model, they show the sensitivity to new unconstrained structure functions of the nucleon, beyond the usual Dirac and Pauli form factors. In addition, they show the sensitivity to bound nucleon form factors using the reaction 4He({rvec e},e{prime},{rvec p}){sup 3}H. A nucleon embedded in a nucleus represents a complex system. Firstly, the bound nucleon is necessarily off-shell and in principle a complete understanding of the dynamical structure of the nucleon is required in order to calculate its off-shell electromagnetic interaction. Secondly, one faces the possibility of genuine medium effects, such as for example quark-exchange contributions. Furthermore, the electromagnetic coupling to the bound nucleon is dependent on the nuclear dynamics through the self-energy of the nucleon in the nuclear medium.

  7. Medium modifications with recoil polarization

    International Nuclear Information System (INIS)

    Brand, J.F.J. van den; Ent, R.

    1994-01-01

    The authors show that the virtual Compton scattering process allows for a precise study of the off-shell electron-nucleon vertex. In a separable model, they show the sensitivity to new unconstrained structure functions of the nucleon, beyond the usual Dirac and Pauli form factors. In addition, they show the sensitivity to bound nucleon form factors using the reaction 4He(rvec e,e',rvec p) 3 H. A nucleon embedded in a nucleus represents a complex system. Firstly, the bound nucleon is necessarily off-shell and in principle a complete understanding of the dynamical structure of the nucleon is required in order to calculate its off-shell electromagnetic interaction. Secondly, one faces the possibility of genuine medium effects, such as for example quark-exchange contributions. Furthermore, the electromagnetic coupling to the bound nucleon is dependent on the nuclear dynamics through the self-energy of the nucleon in the nuclear medium

  8. Medium Theory and Social Systems

    DEFF Research Database (Denmark)

    Tække, Jesper

      the  possibility  for  observation both of a social micro and a social macro level from a medium perspective. In the next  section  the paper  frames  the macro  level by  a  tentative  synthesis of  the medium  theory  and  the  sociological systems theory briefly describing a socio......-evolutionary process where new media alter  the societal capacity to handle complexity  in  time and space.  In  this section it becomes probable  that  by  means  of  different  media,  social  systems  give  different  possibilities  for  actual  social  performance.  In a way,  social  systems  themselves can be......  seen as medium  for  formation. Finally  the  paper  takes  the micro  level  perspective  by  applying  the  theory  to  newsgroups,  interpreting  them as self-organizing interactive systems giving a differentiated and diversified scope for social  inclusion.  ...

  9. Medium energy ion scattering (MEIS)

    International Nuclear Information System (INIS)

    Dittmann, K.; Markwitz, A.

    2009-01-01

    This report gives an overview about the technique and experimental study of medium energy ion scattering (MEIS) as a quantitative technique to determine and analyse the composition and geometrical structure of crystalline surfaces and near surface-layers by measuring the energy and yield of the backscattered ions. The use of a lower energy range of 50 to 500 keV accelerated ions impinging onto the target surface and the application of a high-resolution electrostatic energy analyser (ESA) makes medium energy ion scattering spectroscopy into a high depth resolution and surface-sensitive version of RBS with less resulting damage effects. This report details the first steps of research in that field of measurement technology using medium energetic backscattered ions detected by means of a semiconductor radiation detector instead of an ESA. The study of medium energy ion scattering (MEIS) has been performed using the 40 keV industrial ion implanter established at GNS Sciences remodelled with supplementary high voltage insulation for the ion source in order to apply voltages up to 45 kV, extra apertures installed in the beamline and sample chamber in order to set the beam diameter accurately, and a semiconductor radiation detector. For measurement purposes a beam of positive charged helium ions accelerated to an energy of about 80 keV has been used impinging onto target surfaces of lead implanted into silicon (PbSi), scandium implanted into aluminium (ScAl), aluminium foil (Al) and glassy carbon (C). First results show that it is possible to use the upgraded industrial implanter for medium energy ion scattering. The beam of 4 He 2+ with an energy up to 88 keV has been focussed to 1 mm in diameter. The 5 nA ion beam hit the samples under 2 x 10 -8 mbar. The results using the surface barrier detector show scattering events from the samples. Cooling of the detector to liquid nitrogen temperatures reduced the electronic noise in the backscattering spectrum close to zero. A

  10. Micropropagação de duas espécies frutíferas, em meio de cultura DSD1, modificado com fontes de boro e zinco Micropropagation of two fruit tree species on dsd1 culture medium modified with boric acid and zinc sulfate

    Directory of Open Access Journals (Sweden)

    Fabíola Villa

    2009-04-01

    Full Text Available A micropropagação de frutíferas de clima temperado pode gerar plantas livres de vírus e num curto espaço de tempo. Objetivando-se aprimorar técnicas de propagação in vitro de amoreira-preta e videira, foram testadas diferentes concentrações de boro e zinco, adicionados ao meio de cultivo. O meio foi constituído de sais DSD1, acrescido de 30 g L-1 de sacarose e 7 g L-1 de ágar, e o pH ajustado para 6,4 antes da autoclavagem a 121ºC e 1 atm por 20 minutos. Os tratamentos consistiram de segmentos nodais de amoreira-preta cv. Tupy, do porta-enxerto de videira 'Kobber' e de concentrações de ácido bórico (0; 1,0; 2,0 e 4,0 mg L-1 e sulfato de zinco hidratado (0; 1,0; 2,0 e 4,0 mg L-1, em todas as combinações possíveis. Segmentos nodais de plantas preestabelecidas in vitro foram excisados e inoculados em tubo de ensaio, contendo 15 mL do meio de cultura. Posteriormente, os tubos de ensaio foram transferidos para sala de crescimento a 27 ± 1ºC, irradiância de 35 mmol.m-2.s-1 e fotoperíodo de 16 horas. O delineamento experimental utilizado foi inteiramente casualisado, utilizando-se 4 repetições com 12 explantes cada. Após 70 dias de cultivo in vitro verificou-se que, melhores resultados na micropropagação de amoreira-preta cv. Tupy (Rubus sp. foram obtidos na ausência de ácido bórico e sulfato de zinco hidratado em meio de cultura DSD1. Com 4,0 mg L-1 de ácido bórico adicionado ao meio, verificou-se maior número de folhas e comprimento de raízes do porta-enxerto de videira 'Kobber' (Vitis sp..The micropropagation of temperate fruit trees may generate virus-free plants with the additional advantage of a shorter period of time compared to the traditional culture. Aiming to improve the in vitro propagation of blackberry and grapevine, different boron and zinc concentrations added to the culture medium were tested. The culture medium was constituted of DSD1 salts, added of 30 g L-1 sucrose and 7 g L-1 agar, and the p

  11. Aag Hypoxanthine-DNA Glycosylase Is Synthesized in the Forespore Compartment and Involved in Counteracting the Genotoxic and Mutagenic Effects of Hypoxanthine and Alkylated Bases in DNA during Bacillus subtilis Sporulation.

    Science.gov (United States)

    Ayala-García, Víctor M; Valenzuela-García, Luz I; Setlow, Peter; Pedraza-Reyes, Mario

    2016-12-15

    Aag from Bacillus subtilis has been implicated in in vitro removal of hypoxanthine and alkylated bases from DNA. The regulation of expression of aag in B. subtilis and the resistance to genotoxic agents and mutagenic properties of an Aag-deficient strain were studied here. A strain with a transcriptional aag-lacZ fusion expressed low levels of β-galactosidase during growth and early sporulation but exhibited increased transcription during late stages of this developmental process. Notably, aag-lacZ expression was higher inside the forespore than in the mother cell compartment, and this expression was abolished in a sigG-deficient background, suggesting a forespore-specific mechanism of aag transcription. Two additional findings supported this suggestion: (i) expression of an aag-yfp fusion was observed in the forespore, and (ii) in vivo mapping of the aag transcription start site revealed the existence of upstream regulatory sequences possessing homology to σ G -dependent promoters. In comparison with the wild-type strain, disruption of aag significantly reduced survival of sporulating B. subtilis cells following nitrous acid or methyl methanesulfonate treatments, and the Rif r mutation frequency was significantly increased in an aag strain. These results suggest that Aag protects the genome of developing B. subtilis sporangia from the cytotoxic and genotoxic effects of base deamination and alkylation. In this study, evidence is presented revealing that aag, encoding a DNA glycosylase implicated in processing of hypoxanthine and alkylated DNA bases, exhibits a forespore-specific pattern of gene expression during B. subtilis sporulation. Consistent with this spatiotemporal mode of expression, Aag was found to protect the sporulating cells of this microorganism from the noxious and mutagenic effects of base deamination and alkylation. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

  12. Modified bitumen for embedding of radioactive wastes

    International Nuclear Information System (INIS)

    Bozkurt, C.

    1984-11-01

    This work describes new possibilities of using polymer modified bitumen as matrix material for embedding of low- and medium level radioactive wastes. Epoxy resins, polyurethane resins and styrene-butadiene-copolymers with 20-40 weight per cent are used as modifying agents. Penetration and softening point (ring and ball) of modified samples have been measured. Further the resistance to toluene and leaching rate in n-heptane have been determined. Within these polymer bitumen combinations investigated, the epoxy resins having a high epoxid equivalent weight with dicarbooxylic acid anhydrid hardeners and tertiary amin accelerators give the most dense network, highest thermodimensional stability and lowest leaching rate in organic solvents. 71 refs., 9 figs., 6 tabs

  13. Factors affecting the sporulation capacity during long-term storage of the aphid-pathogenic fungus Pandora neoaphidis grown on broomcorn millet.

    Science.gov (United States)

    Feng, Ming-Guang; Hua, Li

    2005-04-15

    Aphid-pathogenic fungus, Pandora neoaphidis, grown on broomcorn millet possesses greater sporulation capacity (C(s)) than aphid cadavers. The most sporulating cultures (32.0x10(4) spores millet(-1) grain) with water content (C(w)) of 48.7% were prepared by incubation at 20 degrees C for 15 days and used to study the effect of temperature and humidity on C(s) during long-term storage. Cultures were sealed with paper to retain ambient humidity, with parafilm for saturated humidity, or kept in 85% and 98% RH chambers. The C(w) and C(s) were monitored during 200-day storage at 5-20 degrees C. The paper-sealed cultures at 5 degrees C, associated with 21-25% of C(w), were best preserved and their 120-day C(s) was similar to that of the fresh cadavers. Consistently or variably high RH at 5 degrees C resulted in significantly higher C(w) and lower C(s) despite longer viability. The regimes at 10 degrees C preserved the cultures for 40 days. The observations fit well to the logistic model C(s)=35.28/{1+exp[-2.36+(-0.003C(w)+0.001C(w)T)t]} (r(2)=0.95) for all regimes of temperature (T) or C(s)=35.55/[1+exp(-2.33+0.001C(w)t)] (r(2)=0.93) at 5 degrees C only. The rate of decline of C(s) of -0.003C(w)+0.001C(w)T or 0.001 C(w) over days (t) highlights the primary effect of C(w). The daily C(s)-decline rates obtained for the best-stored cultures and air-dried cadavers stored at 5 degrees C were surprisingly identical. The results suggest a possible cheap method for preparing and storing large quantities of P. neoaphiodis inocula.

  14. Does methyl salicylate, a component of herbivore-induced plant odour, promote sporulation of the mite-pathogenic fungus Neozygites tanajoae?

    Science.gov (United States)

    Hountondji, Fabien C C; Hanna, Rachid; Sabelis, Maurice W

    2006-01-01

    Blends of volatile chemicals emanating from cassava leaves infested by the cassava green mite were found to promote conidiation of Neozygites tanajoae, an entomopathogenic fungus specific to this mite. Methyl salicylate (MeSA) is one compound frequently present in blends of herbivore-induced plant volatiles (HIPV) as well as that of mite-infested cassava. Here, we investigated the effect of methyl salicylate in its pure form on the production of pre-infective spores (conidia), and the germination of these spores into infective spores (capilliconidia), by a Brazilian isolate and a Beninese isolate of N. tanajoae. Mummified mites previously infected by the fungal isolates were screened under optimal abiotic conditions for sporulation inside tightly closed boxes with or without methyl salicylate diffusing from a capillary tube. Production of conidia was consistently higher (37%) when the Beninese isolate was exposed to MeSA than when not exposed to it (305.5 +/- 52.62 and 223.2 +/- 38.13 conidia per mummy with and without MeSA, respectively). MeSA, however, did not promote conidia production by the Brazilian isolate (387.4 +/- 44.74 and 415.8 +/- 57.95 conidia per mummy with and without MeSA, respectively). Germination of the conidia into capilliconidia was not affected by MeSA for either isolate (0.2%, 252.6 +/- 31.80 vs. 253.0 +/- 36.65 for the Beninese isolate and 4.2%, 268.5 +/- 37.90 vs. 280.2 +/- 29.43 for the Brazilian isolate). The effects of MeSA on the production of conidia were similar to those obtained under exposure to the complete blends of HIPV for the case of the Beninese isolate, but dissimilar (no promoting effect of MeSA) for the case of the Brazilian isolate. This shows that MeSA, being one compound out of many HIPV, can be a factor promoting sporulation of N. tanajoae, but it may not be the only factor as its effect varies with the fungal isolate under study.

  15. Accretion from an inhomogeneous medium

    International Nuclear Information System (INIS)

    Livio, M.; Soker, N.; Koo, M. de; Savonije, G.J.

    1986-01-01

    The problem of accretion by a compact object from an inhomogeneous medium is studied in the general γnot=1 case. The mass accretion rate is found to decrease with increasing γ. The rate of accretion of angular momentum is found to be significantly lower than the rate at which angular momentum is deposited into the Bondi-Hoyle, symmetrical, accretion cylinder. The consequences of the results are studied for the cases of neutron stars accreting from the winds of early-type companions and white dwarfs and main-sequence stars accreting from winds of cool giants. (author)

  16. A Heterogeneous Medium Analytical Benchmark

    International Nuclear Information System (INIS)

    Ganapol, B.D.

    1999-01-01

    A benchmark, called benchmark BLUE, has been developed for one-group neutral particle (neutron or photon) transport in a one-dimensional sub-critical heterogeneous plane parallel medium with surface illumination. General anisotropic scattering is accommodated through the Green's Function Method (GFM). Numerical Fourier transform inversion is used to generate the required Green's functions which are kernels to coupled integral equations that give the exiting angular fluxes. The interior scalar flux is then obtained through quadrature. A compound iterative procedure for quadrature order and slab surface source convergence provides highly accurate benchmark qualities (4- to 5- places of accuracy) results

  17. Charmed hadrons in nuclear medium

    International Nuclear Information System (INIS)

    Tolos, L.; Gamermann, D.; Molina, R.; Nieves, J.; Oset, E.; Garcia-Recio, C.; Ramos, A.

    2010-01-01

    We study the properties of charmed hadrons in dense matter within a coupled-channel approach which accounts for Pauli blocking effects and meson self-energies in a self-consistent manner. We analyze the behaviour in this dense environment of dynamically-generated baryonic resonances as well as the open-charm meson spectral functions. We discuss the implications of the in-medium properties of open-charm mesons on the D s0 (2317) and the predicted X(3700) scalar resonances. (authors)

  18. Development of brachytherapy medium doserate

    International Nuclear Information System (INIS)

    Atang Susila; Ari Satmoko; Ahmad Rifai; Kristiyanti

    2010-01-01

    Brachytherapy has proven to be an effective treatment for different types of cancers and it become a common treatment modality in most radiotherapy clinics. PRPN has had experience in development of Low Dose Rate Brachytherapy for cervix cancer treatment. However the treatment process using LDR device needs 5 hours in time that the patient feel uncomfort. Therefore PRPN develops Medium Dose Rate Brachytherapy with radiation activity not more than 5 Currie. The project is divided into two stages. Purchasing of TPS software and TDS design are held in 2010, and the construction will be in 2011. (author)

  19. On Modified Bar recursion

    DEFF Research Database (Denmark)

    Oliva, Paulo Borges

    2002-01-01

    Modified bar recursion is a variant of Spector's bar recursion which can be used to give a realizability interpretation of the classical axiom of dependent choice. This realizability allows for the extraction of witnesses from proofs of forall-exists-formulas in classical analysis. In this talk I...... shall report on results regarding the relationship between modified and Spector's bar recursion. I shall also show that a seemingly weak form of modified bar recursion is as strong as "full" modified bar recursion in higher types....

  20. Medium modification of fragmentation functions

    International Nuclear Information System (INIS)

    Nezza, Pasquale Di

    2007-01-01

    Deep Inelastic Scattering is the cleanest process to investigate the space-time evolution of the hadronization. This was studied by the influence of the nuclear medium on lepto-production of hadrons at the Hermes experiment at DESY in semi-inclusive DIS of 27.6 GeV positrons off deuterium, nitrogen, krypton and xenon targets. The differential multiplicity for heavy targets relative to that of deuterium has been measured for the first time for various identified hadrons (φ + , φ - , φ 0 , k + , k - , p and anti-p) as a function of the virtual photon energy ?, the fraction z of this energy transferred to the hadron, and the hadron transverse momentum squared p 2 t . The distribution of the hadron transverse momentum is broadened towards high p 2 t in the nuclear medium, in a manner resembling the Cronin effect observed in collisions of heavy ions and protons with nuclei. The pt -broadening results give also important information about the pre-hadron formation time. Moreover, by studying the hadron attenuation of the leading and sub-leading hadrons, we report, for the first time, the possibility to better understand the hadron absorption and the energy loss contributions to the attenuation mechanism. (Author)

  1. Gravitational lensing in plasmic medium

    Energy Technology Data Exchange (ETDEWEB)

    Bisnovatyi-Kogan, G. S., E-mail: gkogan@iki.rssi.ru; Tsupko, O. Yu., E-mail: tsupko@iki.rssi.ru [Russian Academy of Sciences, Space Research Institute (Russian Federation)

    2015-07-15

    The influence of plasma on different effects of gravitational lensing is reviewed. Using the Hamiltonian approach for geometrical optics in a medium in the presence of gravity, an exact formula for the photon deflection angle by a black hole (or another body with a Schwarzschild metric) embedded in plasma with a spherically symmetric density distribution is derived. The deflection angle in this case is determined by the mutual combination of different factors: gravity, dispersion, and refraction. While the effects of deflection by the gravity in vacuum and the refractive deflection in a nonhomogeneous medium are well known, the new effect is that, in the case of a homogeneous plasma, in the absence of refractive deflection, the gravitational deflection differs from the vacuum deflection and depends on the photon frequency. In the presence of a plasma nonhomogeneity, the chromatic refractive deflection also occurs, so the presence of plasma always makes gravitational lensing chromatic. In particular, the presence of plasma leads to different angular positions of the same image if it is observed at different wavelengths. It is discussed in detail how to apply the presented formulas for the calculation of the deflection angle in different situations. Gravitational lensing in plasma beyond the weak deflection approximation is also considered.

  2. Unsaturated medium hydrocarbons pollution evaluation

    International Nuclear Information System (INIS)

    Di Luise, G.

    1991-01-01

    When the so called porous unsaturated medium, that's the vertical subsoil section between both the ground and water-table level, is interested by a hydrocarbons spill, the problem to evaluate the pollution becomes difficult: considering, essentially, the natural coexistence in it of two fluids, air and water, and the interactions between them. This paper reports that the problems tend to increase when a third fluid, the pollutant, immiscible with water, is introduced into the medium: a three-phases flow, which presents several analogies with the flow conditions present in an oil-reservoir, will be established. In such a situation, it would be very useful to handle the matter by the commonly used parameters in the oil reservoirs studies such as: residual saturation, relative permeability, phases mobility, to derive a first semiquantitative estimation of the pollution. The subsoil pollution form hydrocarbons agents is one of the worldwide more diffused causes of contamination: such events are generally referable to two main effects: accidental (oil pipeline breakdowns, e.g.), and continuous (underground tanks breaks, industrial plants leakages, e.g.)

  3. Is the intercloud medium pervasive

    International Nuclear Information System (INIS)

    Heiles, C.

    1980-01-01

    We consider the pervasiveness of the ''not strongly absorbing'' (NSA) H I gas, which is the intercloud medium in steady state theories of the interstellar medium. We study the question by analyzing wide emission components in nearby gas, and the absence of absorption components in distant gas. We conclude that the NSA material is deficient in the immediately local solar vicinity. In nearby regions it contains 38% of the interstellar H I; it is generally pervasive and often has internal motions which greatly increase its velocity dispersion above the 5 km s -1 minimum value. It contains large holes, perhaps ranging up to 400 pc diameter, which probably occupy 10--20% of the volume. In distant regions the NSA material seems to be pervasive outside 8 kpc galactic radius. For galactic radii between 8 and 10 kpc its thickness agrees with previous determinations of 370 pc for nearby regions. Outside 10 kpc the thickness increases dramatically. Inside 8 kpc there are no data

  4. How Does the Medium Affect the Message?

    Science.gov (United States)

    Dommermuth, William P.

    1974-01-01

    This experimental comparison of the advertising effectiveness of television, movies, radio, and print finds no support for McLuhan's idea that television is a "cool" medium and movies are a "hot" medium. (RB)

  5. Decontamination of radioactive liquid systems by modified clay minerals

    OpenAIRE

    Petrushka, Ihor; Moroz, Olexandr

    2016-01-01

    The process mechanism for sorption of strontium and cesium from liquid radioactive waste using modified bentonites from Yaziv sulfur deposit was investigated. The technique for predicting the intensity of the sorption process based on the comparison of experimental and calculated values of mass transfer coefficients was proposed. It was detected that the process of sorption extraction of strontium and cesium from liquid medium using modified clay minerals may be bes...

  6. Homogeneous-heterogeneous reactions in curved channel with porous medium

    Science.gov (United States)

    Hayat, T.; Ayub, Sadia; Alsaedi, A.

    2018-06-01

    Purpose of the present investigation is to examine the peristaltic flow through porous medium in a curved conduit. Problem is modeled for incompressible electrically conducting Ellis fluid. Influence of porous medium is tackled via modified Darcy's law. The considered model utilizes homogeneous-heterogeneous reactions with equal diffusivities for reactant and autocatalysis. Constitutive equations are formulated in the presence of viscous dissipation. Channel walls are compliant in nature. Governing equations are modeled and simplified under the assumptions of small Reynolds number and large wavelength. Graphical results for velocity, temperature, heat transfer coefficient and homogeneous-heterogeneous reaction parameters are examined for the emerging parameters entering into the problem. Results reveal an activation in both homogenous-heterogenous reaction effect and heat transfer rate with increasing curvature of the channel.

  7. DNA polymerase I is required for premeiotic DNA replication and sporulation but not for X-ray repair in Saccharomyces cerevisiae

    International Nuclear Information System (INIS)

    Budd, M.E.; Wittrup, K.D.; Bailey, J.E.; Campbell, J.L.

    1989-01-01

    We have used a set of seven temperature-sensitive mutants in the DNA polymerase I gene of Saccharomyces cerevisiae to investigate the role of DNA polymerase I in various aspects of DNA synthesis in vivo. Previously, we showed that DNA polymerase I is required for mitotic DNA replication. Here we extend our studies to several stages of meiosis and repair of X-ray-induced damage. We find that sporulation is blocked in all of the DNA polymerase temperature-sensitive mutants and that premeiotic DNA replication does not occur. Commitment to meiotic recombination is only 2% of wild-type levels. Thus, DNA polymerase I is essential for these steps. However, repair of X-ray-induced single-strand breaks is not defective in the DNA polymerase temperature-sensitive mutants, and DNA polymerase I is therefore not essential for repair of such lesions. These results suggest that DNA polymerase II or III or both, the two other nuclear yeast DNA polymerases for which roles have not yet been established, carry out repair in the absence of DNA polymerase I, but that DNA polymerase II and III cannot compensate for loss of DNA polymerase I in meiotic replication and recombination. These results do not, however, rule out essential roles for DNA polymerase II or III or both in addition to that for DNA polymerase I

  8. 27 CFR 19.914 - Medium plants.

    Science.gov (United States)

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Medium plants. 19.914... OF THE TREASURY LIQUORS DISTILLED SPIRITS PLANTS Distilled Spirits For Fuel Use Permits § 19.914 Medium plants. Any person wishing to establish a medium plant shall make application for and obtain in...

  9. Mapping of moveout in a TTI medium

    KAUST Repository

    Stovas, A.; Alkhalifah, Tariq Ali

    2012-01-01

    To compute moveout in a transversely isotropic medium with tilted symmetry axis is a very complicated problem. We propose to split this problem into two parts. First, to compute the moveout in a corresponding VTI medium. Second, to map the computed moveout to a TTI medium.

  10. Magnetogravitational stability of resistive plasma through porous medium with thermal conduction and FLR corrections

    International Nuclear Information System (INIS)

    Vaghela, D.S.; Chhajlani, R.K.

    1989-01-01

    The problem of stability of self gravitating magnetized plasma in porous medium is studied incorporating electrical resistivity, thermal conduction and FLR corrections. Normal mode analysis is applied to derive the dispersion relation. Wave propagation is discussed for parallel and perpendicular directions to the magnetic field. Applying Routh Hurwitz Criterion the stability of the medium is discussed and it is found that Jeans' criterion determines the stability of the medium. Magnetic field, porosity and resistivity of the medium have no effect on Jeans' Criterion in longitudinal direction. For perpendicular direction, in case of resistive medium Jeans' expression remains unaffected by magnetic field but for perfectly conducting medium magnetic field modifies the Jeans' expression to show the stabilizing effect. Thermal conductivity affects the sonic mode by making the process isothermal instead of adiabatic. Porosity of the medium is effective only in case of perpendicular direction to magnetic field for perfectly conducting plasma as it reduces the stabilizing effect of magnetic field. For longitudinal wave propagation, though Finite Larmor Radius (FLR) corrections have no effect on sonic mode but it changes the growth rate for Alfven mode. For transverse wave propagation FLR corrections and porosity affect the Jeans' expression in case of non-viscous medium but viscosity of the medium removes the effect of FLR and porosity on Jeans' condition. (author)

  11. Modified Allergens for Immunotherapy.

    Science.gov (United States)

    Satitsuksanoa, Pattraporn; Głobińska, Anna; Jansen, Kirstin; van de Veen, Willem; Akdis, Mübeccel

    2018-02-16

    During the past few decades, modified allergens have been developed for use in allergen-specific immunotherapy (AIT) with the aim to improve efficacy and reduce adverse effects. This review aims to provide an overview of the different types of modified allergens, their mechanism of action and their potential for improving AIT. In-depth research in the field of allergen modifications as well as the advance of recombinant DNA technology have paved the way for improved diagnosis and research on human allergic diseases. A wide range of structurally modified allergens has been generated including allergen peptides, chemically altered allergoids, adjuvant-coupled allergens, and nanoparticle-based allergy vaccines. These modified allergens show promise for the development of AIT regimens with improved safety and long-term efficacy. Certain modifications ensure reduced IgE reactivity and retained T cell reactivity, which facilities induction of immune tolerance to the allergen. To date, multiple clinical trials have been performed using modified allergens. Promising results were obtained for the modified cat, grass and birch pollen, and house dust mite allergens. The use of modified allergens holds promise for improving AIT efficacy and safety. There is however a need for larger clinical studies to reliably assess the added benefit for the patient of using modified allergens for AIT.

  12. Synthesis and characterization of acrylated Parkia biglobosa medium oil alkyds

    Directory of Open Access Journals (Sweden)

    E.T. Akintayo

    2004-12-01

    Full Text Available Acrylated Parkia biglobosa medium oil alkyd prepared by the reaction between an acid containing acrylic copolymer and a monoglyceride followed by the addition of polyol and dibasic acid has been investigated for improved properties. The results revealed that acid functional acrylic copolymers containing maleic anhydride as a functional co-monomer can successfully be used to modify alkyd resins yielding acrylated resins with better drying, flexibility, scratch hardness, impact resistance and chemical resistance properties. However there exist optimum levels for modification of alkyds with such copolymers beyond which certain film properties are adversely affected.

  13. Medium-size nuclear plants

    International Nuclear Information System (INIS)

    Vogelweith, L.; Lavergne, J.C.; Martinot, G.; Weiss, A.

    1977-01-01

    CEA (TECHNICATOME) has developed a range of pressurized water reactors of the type ''CAS compact'' which are adapted to civil ship propulsion, or to electric power production, combined possibly with heat production, up to outputs equivalent to 125 MWe. Nuclear plants equipped with these reactors are suitable to medium-size electric networks. Among the possible realizations, two types of plants are mentioned as examples: 1) Floating electron-nuclear plants; and 2) Combined electric power and desalting plants. The report describes the design characteristics of the different parts of a 125 MWe unit floating electro-nuclear plant: nuclear steam system CAS 3 G, power generating plant, floating platform for the whole plant. The report gives attention to the different possibilities according to site conditions (the plant can be kept floating, in a natural or artificial basin, it can be put aground, ...) and to safety and environment factors. Such unit can be used in places where there is a growing demand in electric power and fresh water. The report describes how the reactor, the power generating plant and multiflash distillation units of an electric power-desalting plant can be combined: choice of the ratio water output/electric power output, thermal cycle combination, choice of the gain ratio, according to economic considerations, and to desired goal of water output. The report analyses also some technical options, such as: choice of the extraction point of steam used as heat supply of the desalting station (bleeding a condensation turbine, or recovering steam at the exhaust of a backpressure turbine), design making the system safe. Lastly, economic considerations are dealt with: combining the production of fresh water and electric power provides usually a much better energy balance and a lower cost for both products. Examples are given of some types of installations which combine medium-size reactors with fresh water stations yielding from 10000 to 120000 m 3 per day

  14. Magnetically modified biocells in constant magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Abramov, E.G.; Panina, L.K. [Saint Petersburg State University, St. Petersburg (Russian Federation); Kolikov, V.A., E-mail: kolikov1@yandex.ru [Institute for Electrophysics and Electric Power of the RAS, St. Petersburg (Russian Federation); Bogomolova, E.V. [Botanical Institute of the RAS after V.L.Komarov, St. Petersburg (Russian Federation); Snetov, V.N. [Institute for Electrophysics and Electric Power of the RAS, St. Petersburg (Russian Federation); Cherepkova, I.A. [Saint Petersburg State Institute of Technology, St. Petersburg (Russian Federation); Kiselev, A.A. [Institute for Electrophysics and Electric Power of the RAS, St. Petersburg (Russian Federation)

    2017-02-01

    Paper addresses the inverse problem in determining the area, where the external constant magnetic field captures the biological cells modified by the magnetic nanoparticles. Zero velocity isolines, in area where the modified cells are captured by the magnetic field were determined by numerical method for two locations of the magnet. The problem was solved taking into account the gravitational field, magnetic induction, density of medium, concentration and size of cells, and size and magnetization of nanoparticles attached to the cell. Increase in the number of the nanoparticles attached to the cell and decrease in the cell’ size, enlarges the area, where the modified cells are captured and concentrated by the magnet. Solution is confirmed by the visible pattern formation of the modified cells Saccharomyces cerevisiae. - Highlights: • The inverse problem was solved for finding zero velocity isolines of magnetically modified biological cells. • Solution of the inverse problem depends on the size of cells and the number of nanoparticles attached to the single cell. • The experimental data are in agreement with theoretical solution.

  15. Tattoo: a multifaceted medium of communication

    Directory of Open Access Journals (Sweden)

    Christian Wymann

    2010-11-01

    Full Text Available This article suggests the systems theoretical distinction of form/medium as a useful tool for distinguishing social phenomena that might look as if they stem from the same process. This is shown to be the case for the tattoo and tattooing. The tattoo is conceived as a medium of communication through which different forms of communication emerge. Tattooing is one of these forms of communication that shapes the medium in a particular way. The current article sheds a special light on its intricate, communicational constellation, for which the concept of parallax is suggested. Law, medicine and cosmetics as other forms of communication use the medium of tattoo in their own way as well. The form/medium distinction allows us to grasp these different forms of communication, while it shows that they share the tattoo as medium. The article’s ultimate goal is to illustrate that the tattoo figures as a multifaceted medium of communication.

  16. Medium-Based Design: Extending a Medium to Create an Exploratory Learning Environment

    Science.gov (United States)

    Rick, Jochen; Lamberty, K. K.

    2005-01-01

    This article introduces "medium-based" design -- an approach to creating "exploratory learning environments" using the method of "extending a medium". First, the characteristics of exploratory learning environments and medium-based design are described and grounded in related work. Particular attention is given to "extending a medium" --…

  17. Dreams of a New Medium

    Directory of Open Access Journals (Sweden)

    Aden Evens

    2009-01-01

    Full Text Available Problematic at best, the desire for a transparent interface nevertheless drives much of digital culture and technology. But not the Web; or at least, not Web 1.0. Thoroughly commercialized, comfortably parsed into genres, serving billions of pages of predigested content to passive consumers, the World Wide Web as developed in the '90s unabashedly embraces its role as medium. While so many digital technologies work to hide their mediacy--drawing in the user with a total simulated sensorium, dematerializing the resistances of size and weight, untangling the knots of cables tying user to machine and machine to cubicle, minimizing the interface--Web 1.0 proudly clings to the browser as a glaring reminder of its medial character. While Web 2.0 has not forsaken the browser altogether, it nevertheless seems to offer a different sort of mediation. Arising alongside the atomization of browser functions, the ubiquitization of connectivity, and the coincidence of producer and user, Web 2.0 retains the form of a medium while reaching for the experiential logic of immediacy. This is not the immediacy of the transparent interface; rather, Web 2.0 effects an immediate relationship between the individual and culture. The interface does not disappear, but its mediacy is subsumed under the general form of cultural participation. Focusing on the "version upgrade" from Web 1.0 to 2.0, this essay will explore the implications for mediacy of this transition, noting that the fantasy of immediacy which drives Web 2.0 is layered and complex. The typical account of immediacy proposes to eliminate the interface and so construct a virtual reality (VR. But Web 2.0 mostly sidesteps the virtual, propelled instead by a fantasy of intuition in which the Web already knows what you want because it is you. Crucially, fantasies about the digital are effective: the computer's futurity inhabits our world, finding its expression in politics, advertising, budgeting, strategic planning

  18. Selection of culture medium and conditions for the production of ...

    African Journals Online (AJOL)

    defined medium–A, defined medium-B, synthetic medium, rich medium and industrial medium) showed that the synthetic medium yielded maximum yeast biomass (12.8 g/LDCW) followed by rich medium (11.7 g/L DCW) and defined medium B ...

  19. Modified Nance palatal button

    Directory of Open Access Journals (Sweden)

    Nitin Arora

    2015-01-01

    Full Text Available This paper describes modified Nance palatal button by which problems encountered in the palatal region around the acrylic button during space closure and molar distalization can be minimized.

  20. Modified microdissection electrocautery needle

    OpenAIRE

    Singh, Virendra; Kumar, Pramod

    2014-01-01

    Electrocautery is routinely used in surgical procedures. The commercially available microdissection electrocautery needles are costly. To overcome this disadvantage, we have modified monopolar electrocautery tip to function as well as commercially available systems.

  1. The interstellar medium in galaxies

    CERN Document Server

    1997-01-01

    It has been more than five decades ago that Henk van de Hulst predicted the observability of the 21-cm line of neutral hydrogen (HI ). Since then use of the 21-cm line has greatly improved our knowledge in many fields and has been used for galactic structure studies, studies of the interstellar medium (ISM) in the Milky Way and other galaxies, studies of the mass distribution of the Milky Way and other galaxies, studies of spiral struc­ ture, studies of high velocity gas in the Milky Way and other galaxies, for measuring distances using the Tully-Fisher relation etc. Regarding studies of the ISM, there have been a number of instrumen­ tal developments over the past decade: large CCD's became available on optical telescopes, radio synthesis offered sensitive imaging capabilities, not only in the classical 21-cm HI line but also in the mm-transitions of CO and other molecules, and X-ray imaging capabilities became available to measure the hot component of the ISM. These developments meant that Milky Way was n...

  2. Studies in medium energy physics

    International Nuclear Information System (INIS)

    Green, A.; Hoffmann, G.W.; McDonough, J.; Purcell, M.J.; Ray, R.L.; Read, D.E.; Worn, S.D.

    1991-12-01

    This document constitutes the (1991--1992) technical progress report and continuation proposal for the ongoing medium energy nuclear physics research program supported by the US Department of Energy through special Research Grant DE-FG05-88ER40444. The experiments discussed are conducted at the Los Alamos National Laboratory's (LANL) Clinton P. Anderson Meson Physics Facility (LAMPF) and the Alternating Gradient Synchrotron (AGS) facility of the Brookhaven National Laboratory (BNL). The overall motivation for the work discussed in this document is driven by three main objectives: (1) provide hadron-nucleon and hadron-nucleus scattering data which serve to facilitate the study of effective two-body interactions, test (and possibly determine) nuclear structure, and help study reaction mechanisms and dynamics; (2) provide unique, first-of-a-kind ''exploratory'' hadron-nucleus scattering data in the hope that such data will lead to discovery of new phenomena and new physics; and (3) perform precision tests of fundamental interactions, such as rare decay searches, whose observation would imply fundamental new physics

  3. Evaluation of rubber modified asphalt demonstration projects

    Energy Technology Data Exchange (ETDEWEB)

    1994-01-01

    As part of the Ontario Government's medium-term scrap tire management strategy, 11 rubber modified asphalt demonstration projects were funded or completed, with 13 additional projects from small to large (1,500-65,000 passenger tire equivalents) approved for the 1993 paving season. This report presents the results of an August to November 1993 study of the 11 demonstration projects. The evaluation included a description of the technology; technical review of the projects; economic analysis; review of the environmental literature; environmental review of the projects; comparison of the projects with similar ones in other jurisdictions; and recommendations. Detailed information on asphalt technology is included in an appendix.

  4. Biological response modifiers

    Energy Technology Data Exchange (ETDEWEB)

    Weller, R.E.

    1991-10-01

    Much of what used to be called immunotherapy is now included in the term biological response modifiers. Biological response modifiers (BRMs) are defined as those agents or approaches that modify the relationship between the tumor and host by modifying the host's biological response to tumor cells with resultant therapeutic effects.'' Most of the early work with BRMs centered around observations of spontaneous tumor regression and the association of tumor regression with concurrent bacterial infections. The BRM can modify the host response in the following ways: Increase the host's antitumor responses through augmentation and/or restoration of effector mechanisms or mediators of the host's defense or decrease the deleterious component by the host's reaction; Increase the host's defenses by the administration of natural biologics (or the synthetic derivatives thereof) as effectors or mediators of an antitumor response; Augment the host's response to modified tumor cells or vaccines, which might stimulate a greater response by the host or increase tumor-cell sensitivity to an existing response; Decrease the transformation and/or increase differentiation (maturation) of tumor cells; or Increase the ability of the host to tolerate damage by cytotoxic modalities of cancer treatment.

  5. Geranylgeranyl diphosphate synthase in fission yeast is a heteromer of farnesyl diphosphate synthase (FPS), Fps1, and an FPS-like protein, Spo9, essential for sporulation.

    Science.gov (United States)

    Ye, Yanfang; Fujii, Makoto; Hirata, Aiko; Kawamukai, Makoto; Shimoda, Chikashi; Nakamura, Taro

    2007-09-01

    Both farnesyl diphosphate synthase (FPS) and geranylgeranyl diphosphate synthase (GGPS) are key enzymes in the synthesis of various isoprenoid-containing compounds and proteins. Here, we describe two novel Schizosaccharomyces pombe genes, fps1(+) and spo9(+), whose products are similar to FPS in primary structure, but whose functions differ from one another. Fps1 is essential for vegetative growth, whereas, a spo9 null mutant exhibits temperature-sensitive growth. Expression of fps1(+), but not spo9(+), suppresses the lethality of a Saccharomyces cerevisiae FPS-deficient mutant and also restores ubiquinone synthesis in an Escherichia coli ispA mutant, which lacks FPS activity, indicating that S. pombe Fps1 in fact functions as an FPS. In contrast to a typical FPS gene, no apparent GGPS homologues have been found in the S. pombe genome. Interestingly, although neither fps1(+) nor spo9(+) expression alone in E. coli confers clear GGPS activity, coexpression of both genes induces such activity. Moreover, the GGPS activity is significantly reduced in the spo9 mutant. In addition, the spo9 mutation perturbs the membrane association of a geranylgeranylated protein, but not that of a farnesylated protein. Yeast two-hybrid and coimmunoprecipitation analyses indicate that Fps1 and Spo9 physically interact. Thus, neither Fps1 nor Spo9 alone functions as a GGPS, but the two proteins together form a complex with GGPS activity. Because spo9 was originally identified as a sporulation-deficient mutant, we show here that expansion of the forespore membrane is severely inhibited in spo9Delta cells. Electron microscopy revealed significant accumulation membrane vesicles in spo9Delta cells. We suggest that lack of GGPS activity in a spo9 mutant results in impaired protein prenylation in certain proteins responsible for secretory function, thereby inhibiting forespore membrane formation.

  6. Optimization of culture conditions and medium composition for the production of micrococcin GO5 by Micrococcus sp. GO5.

    Science.gov (United States)

    Kim, Mi-Hee; Kong, Yoon-Jung; Baek, Hong; Hyun, Hyung-Hwan

    2006-01-02

    To enhance the production of micrococcin GO5, a bacteriocin produced by Micrococcus sp. GO5, cultivation conditions and medium composition were optimized. The optimal initial pH and temperature for bacteriocin production were 7.0-9.0 and 37 degrees C, respectively. Micrococcus sp. GO5 displayed the highest micrococcin GO5 activity when grown in modified MRS medium that contained lactose or sucrose, rather than glucose, as a carbon source. The maximum bacteriocin activity was obtained in modified MRS medium containing 0.5% tryptone and 1.0% yeast extract as nitrogen sources instead of the other nitrogen sources present in MRS medium. Bacteriocin production was greatly affected by the concentration of K(2)HPO(4); strain GO5 produced eight-fold more bacteriocin in medium containing 2.0-2.5% K(2)HPO(4) than in medium containing 0.2% K(2)HPO(4). The optimal concentration of MgSO(4).7H(2)O for bacteriocin production was 0.5%. The production of micrococcin GO5 was increased 32-fold in shake flask culture and 16-fold in a bioreactor using the optimized medium (TY medium), compared with culturing in MRS medium.

  7. The strong anti-glioblastoma capacity of the plasma-stimulated lysine-rich medium

    International Nuclear Information System (INIS)

    Yan, Dayun; Keidar, Michael; Nourmohammadi, Niki; Talbot, Annie; Sherman, Jonathan H

    2016-01-01

    Plasma-stimulated medium (PSM) shows a remarkable anti-cancer capacity as strong as the direct cold atmospheric plasma (CAP) treatment of cancer cells. PSM is able to effectively resist the growth of several cancer cell lines. To date, the sole approach to strengthen the anti-cancer capacity of PSM is extending the plasma treatment time. In this study, we demonstrated that the anti-glioblastoma capacity of PSM could be significantly increased by adding 20 mM lysine in Dulbecco’s modified Eagle’s medium (DMEM). This study provides clear evidence that the anti-glioblastoma capacity of PSM could be noticeably enhanced by modifying the composition of medium without increasing the CAP treatment time. (paper)

  8. Optical illusions induced by rotating medium

    Science.gov (United States)

    Zang, XiaoFei; Huang, PengCheng; Zhu, YiMing

    2018-03-01

    Different from the traditional single-function electromagnetic wave rotators (rotate the electromagnetic wavefronts), we propose that rotating medium can be extended to optical illusions such as breaking the diffraction limit and overlapping illusion. Furthermore, the homogeneous but anisotropic rotating medium is simplified by homogeneous and isotropic positive-index materials according to the effective medium theory, which is helpful for future device fabrication. Finite element simulations for the two-dimensional case are performed to demonstrate these properties.

  9. Jet formation and interference in a thin QCD medium

    CERN Document Server

    Casalderrey-Solana, Jorge; Tywoniuk, Konrad

    2016-11-29

    In heavy-ion collisions, an abundant production of high-energy QCD jets allows to study how these multiparticle sprays are modified as they pass through the quark-gluon plasma. In order to shed new light on this process, we compute the inclusive two-gluon rate off a hard quark propagating through a color deconfined medium at first order in medium opacity. We explicitly impose an energy ordering of the two emitted gluons, such that the "hard" gluon can be thought of as belonging to the jet substructure while the other is a "soft" emission (which can be collinear or medium-induced). Our analysis focusses on two specific limits that clarify the modification of the additional angle- and formation time-ordering of splittings. In one limit, the formation time of the "hard" gluon is short compared to the "soft" gluon formation time, leading to a probabilistic formula for production of and subsequent radiation off a quark-gluon antenna. In the other limit, the ordering of formation is reverted, which automatically le...

  10. Modified blank ammunition injuries.

    Science.gov (United States)

    Ogunc, Gokhan I; Ozer, M Tahir; Coskun, Kagan; Uzar, Ali Ihsan

    2009-12-15

    Blank firing weapons are designed only for discharging blank ammunition cartridges. Because they are cost-effective, are easily accessible and can be modified to live firearms plus their unclear legal situation in Turkish Law makes them very popular in Turkey. 2004 through 2008, a total of 1115 modified blank weapons were seized in Turkey. Blank firing weapons are easily modified by owners, making them suitable for discharging live firearm ammunition or modified blank ammunitions. Two common methods are used for modification of blank weapons. After the modification, these weapons can discharge the live ammunition. However, due to compositional durability problems with these types of weapons; the main trend is to use the modified blank ammunitions rather than live firearm ammunition fired from modified blank firing weapons. In this study, two types of modified blank weapons and two types of modified blank cartridges were tested on three different target models. Each of the models' shooting side was coated with 1.3+/-2 mm thickness chrome tanned cowhide as a skin simulant. The first model was only coated with skin simulant. The second model was coated with skin simulant and 100% cotton police shirt. The third model was coated with skin simulant and jean denim. After the literature evaluation four high risky anatomic locations (the neck area; the eyes; the thorax area and inguinal area) were pointed out for the steel and lead projectiles are discharged from the modified blank weapons especially in close range (0-50 cm). The target models were designed for these anatomic locations. For the target models six Transparent Ballistic Candle blocks (TCB) were prepared and divided into two test groups. The first group tests were performed with lead projectiles and second group with steel projectile. The shortest penetration depth (lead projectile: 4.358 cm; steel projectile 8.032 cm) was recorded in the skin simulant and jean denim coated block for both groups. In both groups

  11. Adsorptive properties and thermal stability of carbon fibers modified by boron and phosphorus compounds

    International Nuclear Information System (INIS)

    Malygin, A.A.; Postnova, A.M.; Shevchenko, G.K.

    1996-01-01

    Sorptional characteristics as regards water vapors and thermal stability of carbon fibers modified by method of molecular superposition of borohydroxide groupings have been studied. Sorptional activity in the range of low and medium relative pressures of water vapors in modified samples increases several times, while thermal stability of carbon fiber increases, as well. 14 refs.; 1 fig.; 1 tab

  12. 46 CFR 56.97-30 - Hydrostatic tests (modifies 137.4).

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Hydrostatic tests (modifies 137.4). 56.97-30 Section 56... SYSTEMS AND APPURTENANCES Pressure Tests § 56.97-30 Hydrostatic tests (modifies 137.4). (a) Provision of... system is filling. (b) Test medium and test temperature. (1) Water will be used for a hydrostatic leak...

  13. Interference between initial and final state radiation in a QCD medium

    CERN Document Server

    Armesto, Nestor; Martinez, Mauricio; Mehtar-Tani, Yacine; Salgado, Carlos A.

    2012-01-01

    We investigate the color coherence pattern between initial and final state radiation in the presence of a QCD medium. We derive the medium-induced gluon spectrum of an "asymptotic" parton which suffers a hard scattering and subsequently crosses the medium. The angular distribution of the induced gluon spectrum is modified when one includes interference terms between the incoming and the outgoing parton at finite angle between them. The coherent, incoherent and soft limits of the medium-induced gluon spectrum are studied. In the soft limit, we provide a simple and intuitive probabilistic picture which could be of interest for Monte Carlo implementations. The configuration studied here may have phenomenological consequences in high energy nuclear collisions.

  14. Modified nasolacrimal duct stenting

    International Nuclear Information System (INIS)

    Tian Min; Jin Mei; Chen Huanjun; Li Yi

    2008-01-01

    Objective: Traditional nasolacrimal duct stenting possesses some shortcoming including difficulty of pulling ball head guide wire from the nasal cavity with turbinate hypertrophy and nasal septal deviation. The new method of nose-oral tube track establishment can overcome the forementioned and increase the successful rate. Methods: 5 F catheter and arterial sheath were modified to be nasolacrimal duct stent delivery device respectively. Antegrade dacryocystography was taken firstly to display the obstructed site and followed by the modified protocol of inserting the guide wire through nasolacrimal duct and nasal cavity, and establishing the stent delivery track for retrograde stent placement. Results: 5 epiphora patients with failure implantation by traditional method were all succeeded through the modified stenting (100%). During 6-mouth follow-up, no serious complications and reocclusion occurred. Conclusion: The establishment of eye-nose-mouth-nose of external nasal guide wire track can improve the successful rate of nasolacrimal duct stenting. (authors)

  15. Recordable storage medium with protected data area

    NARCIS (Netherlands)

    2005-01-01

    The invention relates to a method of storing data on a rewritable data storage medium, to a corresponding storage medium, to a corresponding recording apparatus and to a corresponding playback apparatus. Copy-protective measures require that on rewritable storage media some data must be stored which

  16. Electromagnetic Sources in a Moving Conducting Medium

    DEFF Research Database (Denmark)

    Johannsen, Günther

    1971-01-01

    The problem of an arbitrary source distribution in a uniformly moving, homogeneous, isotropic, nondispersive, conducting medium is solved. The technique used is to solve the problem in the rest system of the medium and then write the result in an appropriate four-dimensional, covariant form which...

  17. Kultivasi Scenedesmus SP. Pada Medium Air Limbah

    OpenAIRE

    Kawaroe, Mujizat

    2011-01-01

    Proses fotosintesis pada mikroalga membutuhkan CO2 dan cahaya matahari serta nutrien untuk pertumbuhannya. Kultivasi Scenedesmus sp. pada medium air limbah bertujuan guna mencukupi kebutuhan mikroalga akan nutrien dan mengurangi masukan dari bahan kimia yang terkandung dalam air limbah tersebut ke lingkungan. Kultivasi Scenedesmus sp. dilakukan selama tujuh hari pada medium air limbah industri tanpa penambahan nutri...

  18. Effective medium theory for anisotropic metamaterials

    KAUST Repository

    Zhang, Xiujuan; Wu, Ying

    2015-01-01

    -dimensional metamaterial composed of a rectangular array of elliptic cylinders and derive an effective medium theory for such a metamaterial. We find that it is possible to obtain a closed-form analytical solution for the anisotropic effective medium parameters, provided

  19. Selective medium for aerobic incubation of Campylobacter

    Science.gov (United States)

    Studies were conducted on the formulation of a selective medium that could be used to isolate Campylobacter from mixed bacterial cultures using aerobic incubation. A non-selective, basal broth medium was prepared and supplemented with Bolton, Cefex, or Skirrow antibiotic mixtures. The ability of pur...

  20. Effective medium theory for anisotropic metamaterials

    KAUST Repository

    Zhang, Xiujuan

    2015-01-20

    Materials with anisotropic material parameters can be utilized to fabricate many fascinating devices, such as hyperlenses, metasolids, and one-way waveguides. In this study, we analyze the effects of geometric anisotropy on a two-dimensional metamaterial composed of a rectangular array of elliptic cylinders and derive an effective medium theory for such a metamaterial. We find that it is possible to obtain a closed-form analytical solution for the anisotropic effective medium parameters, provided the aspect ratio of the lattice and the eccentricity of the elliptic cylinder satisfy certain conditions. The derived effective medium theory not only recovers the well-known Maxwell-Garnett results in the quasi-static regime, but is also valid beyond the long-wavelength limit, where the wavelength in the host medium is comparable to the size of the lattice so that previous anisotropic effective medium theories fail. Such an advance greatly broadens the applicable realm of the effective medium theory and introduces many possibilities in the design of structures with desired anisotropic material characteristics. A real sample of a recently theoretically proposed anisotropic medium, with a near-zero index to control the flux, is achieved using the derived effective medium theory, and control of the electromagnetic waves in the sample is clearly demonstrated.

  1. Normal modified stable processes

    DEFF Research Database (Denmark)

    Barndorff-Nielsen, Ole Eiler; Shephard, N.

    2002-01-01

    Gaussian (NGIG) laws. The wider framework thus established provides, in particular, for added flexibility in the modelling of the dynamics of financial time series, of importance especially as regards OU based stochastic volatility models for equities. In the special case of the tempered stable OU process......This paper discusses two classes of distributions, and stochastic processes derived from them: modified stable (MS) laws and normal modified stable (NMS) laws. This extends corresponding results for the generalised inverse Gaussian (GIG) and generalised hyperbolic (GH) or normal generalised inverse...

  2. Micropropagation of Alstroemeria in liquid medium using slow release of medium components

    NARCIS (Netherlands)

    Klerk, de G.J.M.; Brugge, ter J.

    2010-01-01

    Alstroemeria rhizomes were micropropagated on semi-solid medium (AM) and in liquid medium (LM). In LM, growth was much enhanced (ca. 70%). Adequate gas exchange was crucial. This was obtained by agitation and in static medium by a sufficient large contact area of the explant and the gaseous

  3. Development of selective medium for IMP-type carbapenemase-producing Enterobacteriaceae in stool specimens.

    Science.gov (United States)

    Yamamoto, Norihisa; Kawahara, Ryuji; Akeda, Yukihiro; Shanmugakani, Rathina Kumar; Yoshida, Hisao; Hagiya, Hideharu; Hara, Naohiro; Nishi, Isao; Yukawa, Satomi; Asada, Rumiko; Sasaki, Yumi; Maeda, Kazuhiro; Sakamoto, Noriko; Hamada, Shigeyuki; Tomono, Kazunori

    2017-03-24

    Identification of carbapenemase-producing Enterobacteriaceae (CPE) in faecal specimens is challenging. This fact is particularly critical because low-level carbapenem-resistant organisms such as IMP-producing CPE are most prevalent in Japan. We developed a modified selective medium more suitable for IMP-type CPE. Fifteen reference CPE strains producing different types of β-lactamases were used to evaluate the commercially available CHROMagar KPC and chromID CARBA as well as the newly prepared MC-ECC medium (CHROMagar ECC supplemented with meropenem, cloxacillin, and ZnSO 4 ) and M-ECC medium (CHROMagar ECC supplemented with meropenem and ZnSO 4 ). A total of 1035 clinical samples were then examined to detect CPE using chromID CARBA and M-ECC medium. All tested strains producing NDM-, KPC-, and OXA-48-carbapenemases were successfully cultured in the media employed. Although most of the IMP-positive strains did not grow in CHROMagar KPC, chromID CARBA, or MC-ECC, all tested strains grew on M-ECC. When faecal samples were applied to the media, M-ECC medium allowed the best growth of IMP-type CPE with a significantly higher sensitivity (99.3%) than that of chromID CARBA (13.9%). M-ECC medium was determined as the most favourable selective medium for the detection of IMP-type CPE as well as other types of CPE.

  4. EAMJ Modifiable 10.indd

    African Journals Online (AJOL)

    2010-02-02

    Feb 2, 2010 ... MODIFIABLE FACTORS ASSOCIATED WITH ACTIVE PULMONARY TUBERCULOSIS IN A KENYAN PRISON. A. S. Amwayi, MBChB, MSc., ... University of Agriculture and Technology, P.O. Box 62000- 0200, Nairobi, Kenya and E. M. Muchiri, MSc, PhD., Division ..... Diabetes and low BMI. 223452.81.

  5. Isotopically modified compounds

    International Nuclear Information System (INIS)

    Kuruc, J.

    2009-01-01

    In this chapter the nomenclature of isotopically modified compounds in Slovak language is described. This chapter consists of following parts: (1) Isotopically substituted compounds; (2) Specifically isotopically labelled compounds; (3) Selectively isotopically labelled compounds; (4) Non-selectively isotopically labelled compounds; (5) Isotopically deficient compounds.

  6. Modifiable Combining Functions

    OpenAIRE

    Cohen, Paul; Shafer, Glenn; Shenoy, Prakash P.

    2013-01-01

    Modifiable combining functions are a synthesis of two common approaches to combining evidence. They offer many of the advantages of these approaches and avoid some disadvantages. Because they facilitate the acquisition, representation, explanation, and modification of knowledge about combinations of evidence, they are proposed as a tool for knowledge engineers who build systems that reason under uncertainty, not as a normative theory of evidence.

  7. Modifying Cookbook Labs.

    Science.gov (United States)

    Clark, Robert, L.; Clough, Michael P.; Berg, Craig A.

    2000-01-01

    Modifies an extended lab activity from a cookbook approach for determining the percent mass of water in copper sulfate pentahydrate crystals to one which incorporates students' prior knowledge, engenders active mental struggling with prior knowledge and new experiences, and encourages metacognition. (Contains 12 references.) (ASK)

  8. Optimization of Culture Medium Enhances Viable Biomass Production and Biocontrol Efficacy of the Antagonistic Yeast, Candida diversa

    Directory of Open Access Journals (Sweden)

    Jia Liu

    2017-10-01

    Full Text Available Viable biomass production is a key determinant of suitability of antagonistic yeasts as potential biocontrol agents. This study investigated the effects of three metal ions (magnesium, ferrous, and zinc on biomass production and viability of the antagonistic yeast, Candida diversa. Using response surface methodology to optimize medium components, a maximum biomass was obtained, when the collective Mg2+, Fe2+, and Zn2+ concentrations were adjusted in a minimal mineral (MM medium. Compared with the unmodified MM, and three ion-deficient MM media, yeast cells cultured in the three ion-modified MM medium exhibited a lower level of cellular oxidative damage, and a higher level of antioxidant enzyme activity. A biocontrol assay indicated that C. diversa grown in the ion-modified MM exhibited the greatest level of control of gray mold on apple fruit. These results provide new information on culture medium optimization to grow yeast antagonists in order to improve biomass production and biocontrol efficacy.

  9. A method for the determination of bacterial spore DNA content based on isotopic labelling, spore germination and diphenylamine assay; ploidy of spores of several Bacillus species

    International Nuclear Information System (INIS)

    Hauser, P.M.; Karamata, D.

    1992-01-01

    A reliable method for measuring the spore DNA content, based on radioactive DNA labelling, spore germination in absence of DNA replication and diphenylamine assay, was developed. The accuracy of the method, within 10 - 15%, is adequate for determining the number of chromosomes per spore, provided that the genome size is known. B subtilis spores were shown to be invariably monogenomic, while those of larger bacilli Bacillus megaterium, Bacillus cereus and Bacillus thuringiensis, often, if not invariably, contain two genomes. Attempts to modify the spore DNA content of B subtilis by altering the richness of the sporulation medium, the sporulation conditions (liquid or solid medium), or by mutation, were apparently unsuccessful. An increase of spore size with medium richness, not accompanied by an increase in DNA content, was observed. The implication of the apparently species-specific spore ploidy and the influence of the sporulation conditions on spore size and shape are discussed

  10. Collaborative Manufacturing for Small-Medium Enterprises

    Science.gov (United States)

    Irianto, D.

    2016-02-01

    Manufacturing systems involve decisions concerning production processes, capacity, planning, and control. In a MTO manufacturing systems, strategic decisions concerning fulfilment of customer requirement, manufacturing cost, and due date of delivery are the most important. In order to accelerate the decision making process, research on decision making structure when receiving order and sequencing activities under limited capacity is required. An effective decision making process is typically required by small-medium components and tools maker as supporting industries to large industries. On one side, metal small-medium enterprises are expected to produce parts, components or tools (i.e. jigs, fixture, mold, and dies) with high precision, low cost, and exact delivery time. On the other side, a metal small- medium enterprise may have weak bargaining position due to aspects such as low production capacity, limited budget for material procurement, and limited high precision machine and equipment. Instead of receiving order exclusively, a small-medium enterprise can collaborate with other small-medium enterprise in order to fulfill requirements high quality, low manufacturing cost, and just in time delivery. Small-medium enterprises can share their best capabilities to form effective supporting industries. Independent body such as community service at university can take a role as a collaboration manager. The Laboratory of Production Systems at Bandung Institute of Technology has implemented shared manufacturing systems for small-medium enterprise collaboration.

  11. KULTUR SEL BABY HAMSTER KIDNEY (BHK MENGGUNAKAN MEDIA DULBECCO’S MODIFIED EAGLE MEDIUM (DMEM

    Directory of Open Access Journals (Sweden)

    Mashita Andiana

    2018-01-01

    Full Text Available Kultur sel merupakan suatu proses saat sel hidup ditempatkan ke dalam suatu media yang dapat membuat sel tersebut berkembang biak atau tumbuh secara in vitro, Kultur sel dapat berupa kultur sel primer maupun cell line, Metode dalam kultur sel terdiri atas kultur monolayer dan kultur suspensi. Pembuatan media kultur untuk pertumbuhan sel diusahakan memenuhi kriteria. Konstituen dasar dari media kultur yang paling banyak digunakan adalah BSS (Balanced Sald Solution. Untuk mendapatkan pertumbuhan sel yang optimal, media kultur ditambahkan serum. Serum yang biasa digunakan dalam kultur adalah serum anak sapi (calf serum, serum fetus sapi (foetal bovine serum, serum kuda dan serum manusia. Perhitungan sel menggunakan counting chamber. Metode yang digunakan adalah revival kemudian split sel, stor sel dan menghitung sel. Hasil revival  jumlah sel tertinggi didapat dari botol nomer 3 dengan jumlah sel 310 yaitu botol dengan sel BHK label tahun 2016, dan hasil split sel yang paling tinggi juga didapat dari botol kultur nomer 3 dengan jumlah sel 345 dan 311.

  12. KULTUR SEL BABY HAMSTER KIDNEY (BHK MENGGUNAKAN MEDIA DULBECCO’S MODIFIED EAGLE MEDIUM (DMEM

    Directory of Open Access Journals (Sweden)

    Mashita Andiana

    2017-02-01

    Full Text Available Kultur sel merupakan suatu proses saat sel hidup ditempatkan ke dalam suatu media yang dapat membuat sel tersebut berkembang biak atau tumbuh secara in vitro, Kultur sel dapat berupa kultur sel primer maupun cell line, Metode dalam kultur sel terdiri atas kultur monolayer dan kultur suspensi. Pembuatan media kultur untuk pertumbuhan sel diusahakan memenuhi kriteria. Konstituen dasar dari media kultur yang paling banyak digunakan adalah BSS (Balanced Sald Solution. Untuk mendapatkan pertumbuhan sel yang optimal, media kultur ditambahkan serum. Serum yang biasa digunakan dalam kultur adalah serum anak sapi (calf serum, serum fetus sapi (foetal bovine serum, serum kuda dan serum manusia. Perhitungan sel menggunakan counting chamber. Metode yang digunakan adalah revival kemudian split sel, stor sel dan menghitung sel. Hasil revival  jumlah sel tertinggi didapat dari botol nomer 3 dengan jumlah sel 310 yaitu botol dengan sel BHK label tahun 2016, dan hasil split sel yang paling tinggi juga didapat dari botol kultur nomer 3 dengan jumlah sel 345 dan 311.

  13. VALIDATION OF EPA METHOD 1682: SALMONELLA IN BIOSOLIDS BY MODIFIED, SEMISOLID RAPPAPORT-VASSILIADIS (MSRV) MEDIUM

    Science.gov (United States)

    Treated biosolids may be applied to land as a crop nutrient and soil conditioner. However, land application of biosolids may pose the risk of releasing pathogens into the environment if disinfection and use criteria established by EPA at 40 CFR part 503 are not met. Among these c...

  14. Development of in vivo derived diploid and tetraploid pig embryos in a modified medium NCSU 37

    Czech Academy of Sciences Publication Activity Database

    Procházka, Radek; Vodička, Petr; Zudová, D.; Rybář, R.; Motlík, Jan

    2004-01-01

    Roč. 62, - (2004), s. 155-164 ISSN 0093-691X R&D Projects: GA MŠk LN00A065; GA ČR GA524/01/0903 Institutional research plan: CEZ:AV0Z5045916 Keywords : pig * embryo * ploidy Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 1.640, year: 2004

  15. Photonic-resonant left-handed medium

    International Nuclear Information System (INIS)

    Shen Jianqi

    2006-01-01

    A new scheme to realize simultaneously negative permittivity and permeability in a coherent atomic vapor medium (photonic-resonant material) via a coherent driving mechanism is suggested. It is verified that the atomic system coherently driven by a strong optical field will give rise to a negative refractive index in certain probe frequency ranges. One of the most remarkable features of the present scheme is such that a slab fabricated by the left-handed vapor medium is an ideal candidate for designing perfect lenses since the photonic-resonant atomic vapor cannot only exhibit an isotropic negative refractive index, but also provide a good impedance match at the air-medium interfaces

  16. Physical processes in the interstellar medium

    CERN Document Server

    Spitzer, Lyman

    2008-01-01

    Physical Processes in the Interstellar Medium discusses the nature of interstellar matter, with a strong emphasis on basic physical principles, and summarizes the present state of knowledge about the interstellar medium by providing the latest observational data. Physics and chemistry of the interstellar medium are treated, with frequent references to observational results. The overall equilibrium and dynamical state of the interstellar gas are described, with discussions of explosions produced by star birth and star death and the initial phases of cloud collapse leading to star formation.

  17. Modified Faraday cup

    Science.gov (United States)

    Elmer, John W.; Teruya, Alan T.; O'Brien, Dennis W.

    1996-01-01

    A tomographic technique for measuring the current density distribution in electron beams using electron beam profile data acquired from a modified Faraday cup to create an image of the current density in high and low power beams. The modified Faraday cup includes a narrow slit and is rotated by a stepper motor and can be moved in the x, y and z directions. The beam is swept across the slit perpendicular thereto and controlled by deflection coils, and the slit rotated such that waveforms are taken every few degrees form 0.degree. to 360.degree. and the waveforms are recorded by a digitizing storage oscilloscope. Two-din-tensional and three-dimensional images of the current density distribution in the beam can be reconstructed by computer tomography from this information, providing quantitative information about the beam focus and alignment.

  18. Tip-modified Propellers

    DEFF Research Database (Denmark)

    Andersen, Poul

    1999-01-01

    The paper deals with tip-modified propellers and the methods which, over a period of two decades, have been applied to develop such propellers. The development is driven by the urge to increase the efficiency of propellers and can be seen as analogous to fitting end plates and winglets to aircraft...... propeller, have efficiency increases of a reasonable magnitude in both open-water and behind-ship conditions....

  19. Optimization of medium composition for apple rootstocks

    African Journals Online (AJOL)

    User

    2011-05-02

    May 2, 2011 ... Key words: Apple rootstocks, medium composition, multiplication rate, plant growth regulators (PGRs). ... be extrapolated with the same success for another .... Analysis System (SAS) software program (SAS Institute Inc. 1999).

  20. Optimization of medium composition for thermostable protease ...

    African Journals Online (AJOL)

    SERVER

    2008-04-17

    Apr 17, 2008 ... Optimization of the fermentation medium for maximization of thermostable neutral protease production by Bacillus sp. ..... Each contour curve represented an infinite number of combinations of two ..... Production in sea-water of.

  1. Fractional diffusion equation for heterogeneous medium

    International Nuclear Information System (INIS)

    Polo L, M. A.; Espinosa M, E. G.; Espinosa P, G.; Del Valle G, E.

    2011-11-01

    The asymptotic diffusion approximation for the Boltzmann (transport) equation was developed in 1950 decade in order to describe the diffusion of a particle in an isotropic medium, considers that the particles have a diffusion infinite velocity. In this work is developed a new approximation where is considered that the particles have a finite velocity, with this model is possible to describe the behavior in an anomalous medium. According with these ideas the model was obtained from the Fick law, where is considered that the temporal term of the current vector is not negligible. As a result the diffusion equation of fractional order which describes the dispersion of particles in a highly heterogeneous or disturbed medium is obtained, i.e., in a general medium. (Author)

  2. Small and medium power reactors 1987

    International Nuclear Information System (INIS)

    1987-12-01

    This TECDOC follows the publication of TECDOC-347 Small and Medium Power Reactors Project Initiation Study - Phase I published in 1985 and TECDOC-376 Small and Medium Power Reactors 1985 published in 1986. It is mainly intended for decision makers in Developing Member States interested in embarking on a nuclear power programme. It consists of two parts: 1) Guidelines for the Introduction of Small and Medium Power Reactors in Developing Countries. These Guidelines were established during the Advisory Group Meeting held in Vienna from 11 to 15 May 1987. Their purpose is to review key aspects relating to the introduction of Small and Medium Power Reactors in developing countries; 2) Up-dated Information on SMPR Concepts Contributed by Supplier Industries. According to the recommendations of the Second Technical Committee Meeting on SMPRs held in Vienna in March 1985, this part contains the up-dated information formerly published in Annex I of the above mentioned TECDOC-347. Figs

  3. Incompatibility of Contrast Medium and Trisodium Citrate

    International Nuclear Information System (INIS)

    Delcour, Christian; Bruninx, Guy

    2013-01-01

    To test the compatibility of trisodium citrate, a catheter lock solution, with iodinated contrast medium. Iohexol, iobitridol, iodixanol, ioxaglate, ioxithalamate, iomeprol, and iopromide were tested. In all tests, 2 ml of contrast medium were mixed with 2 ml of trisodium citrate solution. Iodixanol and ioxaglate provoked a highly viscous gluelike precipitation when mixed with trisodium citrate. A brief transient precipitate was observed with iohexol, iomeprol, and ioxithalamate. Permanent precipitation occurred with iobitridol and iopromide. One must be aware of the potential for precipitation when contrast medium is mixed with trisodium citrate solution. Before trisodium citrate solution is injected, the catheter should be thoroughly flushed with saline if a contrast medium has previously been injected through it.

  4. Study of niobium corrosion in alkaline medium

    International Nuclear Information System (INIS)

    Almeida, S.H. de.

    1987-01-01

    A comparative study of niobium electrochemical behaviour in NaOH and KOH solution, with concentrations between 0,5 and 6,1M is presented. The studies were done through electrochemicals assays, consisting in the corrosion potential and anodic and cathodic polarization curves, complemented by loss of mass experiments. The niobium anodic behaviour in alkaline medium is characterized by passivation occurrence, with a stable film formation. The Na oH solution in alkaline medium are more corrosible to niobium than the KOH solution. The loss of mass assays showed that the corrosion velocit is more dependente of hydroxide concentration in KOH medium than the NaOH medium. (C.G.C.) [pt

  5. Small and Medium Enterprises and Biopharmaceutical Innovations ...

    African Journals Online (AJOL)

    Erah

    Benin City, 300001 Nigeria. All rights ... are challenges facing African Small and Medium Enterprises (SMEs) in biopharmaceutical industry, the ... Network for Drug and Diagnostics recognizes .... functionality is in place, integration into the.

  6. Sharing perspectives on English-medium instruction

    CERN Document Server

    Ackerley, Katherine; Helm, Francesca

    2017-01-01

    This volume gives voice to the views and experiences of researchers, lecturers, administrative staff, teacher trainers and students with regard to the implementation of English-medium instruction in a public university based in the north-east of Italy.

  7. Medium Effects in Reactions with Rare Isotopes

    International Nuclear Information System (INIS)

    Bertulani, C A; Karakoç, M

    2012-01-01

    We discuss medium effects in knockout reactions with rare isotopes of weakly-bound nuclei at intermediate energies. We show that the poorly known corrections may lead to sizable modifications of knockout cross sections and momentum dsitributions.

  8. Effective medium theory principles and applications

    CERN Document Server

    Choy, Tuck C

    2015-01-01

    Effective medium theory dates back to the early days of the theory of electricity. Faraday in 1837 proposed one of the earliest models for a composite metal-insulator dielectric and around 1870 Maxwell and later Garnett (1904) developed models to describe a composite or mixed material medium. The subject has been developed considerably since and while the results are useful for predicting materials performance, the theory can also be used in a wide range of problems in physics and materials engineering. This book develops the topic of effective medium theory by bringing together the essentials of both the static and the dynamical theory. Electromagnetic systems are thoroughly dealt with, as well as related areas such as the CPA theory of alloys, liquids, the density functional theory etc., with applications to ultrasonics, hydrodynamics, superconductors, porous media and others, where the unifying aspects of the effective medium concept are emphasized. In this new second edition two further chapters have been...

  9. Small and medium power reactors 1987

    Science.gov (United States)

    1987-12-01

    This TECDOC follows the publication of TECDOC-347: Small and Medium Power Reactors (SMPR) Project Initiation Study, Phase 1, published in 1985 and TECDOC-376: Small and Medium Power Reactors 1985 published in 1986. It is mainly intended for decision makers in Developing Member States interested in embarking on a nuclear power program. It consists of two parts: (1) guidelines for the introduction of small and medium power reactors in developing countries. These Guidelines were established during the Advisory Group Meeting held in Vienna from 11 to 15 May 1987. Their purpose is to review key aspects relating to the introduction of small and medium power reactors in developing countries; (2) up-dated information on SMPR Concepts Contributed by Supplier Industries. According to the recommendations of the Second Technical Committee Meeting on SMPRs held in Vienna in March 1985, this part contains the up-dated information formerly published in Annex 1 of the above mentioned TECDOC-347.

  10. Modified Firefly Algorithm

    Directory of Open Access Journals (Sweden)

    Surafel Luleseged Tilahun

    2012-01-01

    Full Text Available Firefly algorithm is one of the new metaheuristic algorithms for optimization problems. The algorithm is inspired by the flashing behavior of fireflies. In the algorithm, randomly generated solutions will be considered as fireflies, and brightness is assigned depending on their performance on the objective function. One of the rules used to construct the algorithm is, a firefly will be attracted to a brighter firefly, and if there is no brighter firefly, it will move randomly. In this paper we modify this random movement of the brighter firefly by generating random directions in order to determine the best direction in which the brightness increases. If such a direction is not generated, it will remain in its current position. Furthermore the assignment of attractiveness is modified in such a way that the effect of the objective function is magnified. From the simulation result it is shown that the modified firefly algorithm performs better than the standard one in finding the best solution with smaller CPU time.

  11. Genetically Modified Organisms

    Directory of Open Access Journals (Sweden)

    Claro Llaguno

    2001-06-01

    Full Text Available Recent reports have brought to public attention concerns about Bt corn and genetically modified organisms (GMO in general. The timing, it seems, is most appropriate considering two related developments early this year: the final approval of the Cartagena Protocol on Biosafety in Montreal on January 29, 2001, and the OECD Edinburgh Conference on GM food safety last February 28- March 1, 2001. The protocol makes clear that GMOs include all living modified organisms (LMO defined as "any living organism that possesses a novel combination of genetic material obtained through the use of modern biotechnology". This includes seeds, live fish, and other organisms intentionally obtained for release to the environment. It would seem that the common understanding about GMOs as referring to farm-to-table products is perforce expanded to embrace genetically modified farm animals and aquatic resources. Being a trade agreement, the Montreal accord primarily deals with the safety issues related to the transboundary movement of LMOs around the globe. The OECD conference on the other hand, called for an international body "to address all sides of the GM debate" in response to the public outcry, particularly in Western Europe, regarding the risks the new products pose to human health and the environment. Some points of contention, which remain unresolved, include issues such as whether countries should be allowed to develop their own GM food based on their needs, and whether a global moratorium on GMOs and mandatory labeling should be enforced worldwide.

  12. Organic Chemistry: From the Interstellar Medium to the Solar System

    Science.gov (United States)

    Sandford, Scott; Witteborn, Fred C. (Technical Monitor)

    1997-01-01

    This talk will review the various types of organic materials observed in different environments in the interstellar medium, discuss the processes by which these materials may have formed and been modified, and present the evidence supporting the contention that at least a fraction of this material survived incorporation, substantially unaltered, into our Solar System during its formation. The nature of this organic material is of direct interest to issues associated with the origin of life, both because this material represents a large fraction of the Solar System inventory of the biogenically-important elements, and because many of the compounds in this inventory have biogenic implications. Several specific examples of such molecules will be briefly discussed.

  13. Switching power converters medium and high power

    CERN Document Server

    Neacsu, Dorin O

    2013-01-01

    An examination of all of the multidisciplinary aspects of medium- and high-power converter systems, including basic power electronics, digital control and hardware, sensors, analog preprocessing of signals, protection devices and fault management, and pulse-width-modulation (PWM) algorithms, Switching Power Converters: Medium and High Power, Second Edition discusses the actual use of industrial technology and its related subassemblies and components, covering facets of implementation otherwise overlooked by theoretical textbooks. The updated Second Edition contains many new figures, as well as

  14. DYNAMIC DEFORMATION THE VISCOELASTIC TWOCOMPONENT MEDIUM

    Directory of Open Access Journals (Sweden)

    V. S. Polenov

    2015-01-01

    Full Text Available Summary. In the article are scope harmonious warping of the two-component medium, one component which are represent viscoelastic medium, hereditary properties which are described by the kernel aftereffect Abel integral-differential ratio BoltzmannVolterr, while second – compressible liquid. Do a study one-dimensional case. Use motion equation of two-component medium at movement. Look determination system these equalization in the form of damped wave. Introduce dimensionless coefficient. Combined equations happen to homogeneous system with complex factor relatively waves amplitude in viscoelastic component and in fluid. As a result opening system determinant receive biquadratic equation. Elastic operator express through kernel aftereffect Abel for space Fourier. With the help transformation and symbol series biquadratic equation reduce to quadratic equation. Come to the conclusion that in two-component viscoelastic medium exist two mode sonic waves. As a result solution of quadratic equation be found description advance of waves sonic in viscoelastic two-component medium, which physical-mechanical properties represent complex parameter. Velocity determination advance of sonic waves, attenuation coefficient, mechanical loss tangent, depending on characteristic porous medium and circular frequency formulas receive. Graph dependences of description advance of waves sonic from the temperature logarithm and with the fractional parameter γ are constructed.

  15. Selective medium for culture of Mycoplasma hyopneumoniae.

    Science.gov (United States)

    Cook, Beth S; Beddow, Jessica G; Manso-Silván, Lucía; Maglennon, Gareth A; Rycroft, Andrew N

    2016-11-15

    The fastidious porcine respiratory pathogen Mycoplasma hyopneumoniae has proven difficult to culture since it was first isolated in 1965. A reliable solid medium has been particularly challenging. Moreover, clinical and pathological samples often contain the fast-growing M. hyorhinis which contaminates and overgrows M. hyopneumoniae in primary culture. The aim of this study was to optimise the culture medium for recovery of M. hyopneumoniae and to devise a medium for selection of M. hyopneumoniae from clinical samples also containing M. hyorhinis. The solid medium devised by Niels Friis was improved by use of Purified agar and incorporation of DEAE-dextran. Addition of glucose or neutralization of acidity in liquid medium with NaOH did not improve the final yield of viable organisms or alter the timing of peak viability. Analysis of the relative susceptibility of M. hyopneumoniae and M. hyorhinis strains to four antimicrobials showed that M. hyopneumoniae is less susceptible than M. hyorhinis to kanamycin. This was consistent in all UK and Danish strains tested. A concentration of 2μg/ml of kanamycin selectively inhibited the growth of all M. hyorhinis tested, while M. hyopneumoniae was able to grow. This forms the basis of an effective selective culture medium for M. hyopneumoniae. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

  16. Parton fragmentation in the vacuum and in the medium

    CERN Document Server

    Albino, S.; Arleo, F.; Besson, Dave Z.; Brooks, William K.; Buschbeck, B.; Cacciari, M.; Christova, E.; Corcella, G.; D'Enterria, David G.; Dolejsi, Jiri; Domdey, S.; Estienne, M.; Hamacher, Klaus; Heinz, M.; Hicks, K.; Kettler, D.; Kumano, S.; Moch, S.O.; Muccifora, V.; Pacetti, S.; Perez-Ramos, R.; Pirner, H.J.; Pronko, Alexandre Pavlovich; Radici, M.; Rak, J.; Roland, C.; Rudolph, Gerald; Rurikova, Z.; Salgado, C.A.; Sapeta, S.; Saxon, David H.; Seidl, Ralf-Christian; Seuster, R.; Stratmann, M.; Tannenbaum, Michael J.; Tasevsky, M.; Trainor, T.; Traynor, D.; Werlen, M.; Zhou, C.

    2008-01-01

    We present the mini-proceedings of the workshop on ``Parton fragmentation in the vacuum and in the medium'' held at the European Centre for Theoretical Studies in Nuclear Physics and Related Areas (ECT*, Trento) in February 2008. The workshop gathered both theorists and experimentalists to discuss the current status of investigations of quark and gluon fragmentation into hadrons at different accelerator facilities (LEP, B-factories, JLab, HERA, RHIC, and Tevatron) as well as preparations for extension of these studies at the LHC. The main physics topics covered were: (i) light-quark and gluon fragmentation in the vacuum including theoretical (global fits analyses and MLLA) and experimental (data from e+e-, p-p, e-p collisions) aspects, (ii) strange and heavy-quark fragmentation, (iii) parton fragmentation in cold QCD matter (nuclear DIS), and (iv) medium-modified fragmentation in hot and dense QCD matter (high-energy nucleus-nucleus collisions). These mini-proceedings consist of an introduction and short summ...

  17. Meson-exchange forces and medium polarization in finite nuclei

    International Nuclear Information System (INIS)

    Hengeveld, W.

    1986-01-01

    A G-matrix, derived from a meson-exchange potential in nuclear matter, is applied to finite, semi-magic nuclei. For the open shell the broken-pair model, which can accomodate many particle levels, is used. The excitations of the closed shell are treated as particle-hole states. Energy spectra and electromagnetic transition densities are calculated for 88 Sr and 58 Ni. The standard random-phase approximation for finite systems is extended by including the effects of the exchange of the RPA phonons in the residual interaction selfconsistently. It is shown that this particle-hole interaction is strongly energy dependent due to the presence of poles corresponding to 2p-2h (and more complex) excitations. The RPA eigenvalue problem with this energy-dependent residual interaction also provides solutions for these predominantly 2p2h-like states. In addition a modified normalization condition is obtained. This scheme is applied to 56 Ni( 56 Co) in a large configuration space using a residual interaction of the G-matrix type. The effect of dynamic medium polarization on the properties of giant resonances is illustrated for the case of A=48 nuclei. A large fragmentation of the monopole strength is calculated, which is in accordance with the non-observation of the GMR in light nuclei. Properties of A=48 nuclei are computed with an interaction deduced from the NN scattering data without introduction of additional parameters. The role of medium polarization is illustrated for spectra and (e,e') form factors. It is shown how medium polarization induces a coupling between excitations in even-even and in the adjacent odd-odd nuclei. (Auth.)

  18. Process and equipment development for the preparation of UO2 microspheres using trichloroethylene as gelation medium (Paper No. AL-23)

    International Nuclear Information System (INIS)

    Suryanarayana, S.; Kumar, N.; Bamankar, Y.R.; Vaidya, V.N.; Sood, D.D.

    1990-02-01

    Uranium dioxide microspheres have been prepared by internal gelation process, one of the sol-gel routes for fuel fabrication. The process flow sheet for internal gelation has been modified by employing trichloroethylene(TCE) as an alternate gelation medium. Based on the modified flow sheet, a 5Kg/day assembly for the production of UO 2 microspheres has been developed and installed. (author). 1 fig

  19. Numerical artifacts in the Generalized Porous Medium Equation: Why harmonic averaging itself is not to blame

    Science.gov (United States)

    Maddix, Danielle C.; Sampaio, Luiz; Gerritsen, Margot

    2018-05-01

    The degenerate parabolic Generalized Porous Medium Equation (GPME) poses numerical challenges due to self-sharpening and its sharp corner solutions. For these problems, we show results for two subclasses of the GPME with differentiable k (p) with respect to p, namely the Porous Medium Equation (PME) and the superslow diffusion equation. Spurious temporal oscillations, and nonphysical locking and lagging have been reported in the literature. These issues have been attributed to harmonic averaging of the coefficient k (p) for small p, and arithmetic averaging has been suggested as an alternative. We show that harmonic averaging is not solely responsible and that an improved discretization can mitigate these issues. Here, we investigate the causes of these numerical artifacts using modified equation analysis. The modified equation framework can be used for any type of discretization. We show results for the second order finite volume method. The observed problems with harmonic averaging can be traced to two leading error terms in its modified equation. This is also illustrated numerically through a Modified Harmonic Method (MHM) that can locally modify the critical terms to remove the aforementioned numerical artifacts.

  20. In-medium pseudoscalar D/B mesons and charmonium decay width

    Energy Technology Data Exchange (ETDEWEB)

    Chhabra, Rahul; Kumar, Arvind [Dr. B.R. Ambedkar National Institute of Technology Jalandhar, Department of Physics, Jalandhar, Punjab (India)

    2017-05-15

    Using QCD sum rules and the chiral SU(3) model, we investigate the effect of temperature, density, strangeness fraction and isospin asymmetric parameter on the shift in masses and decay constants of the pseudoscalar D and B meson in the hadronic medium, which consist of nucleons and hyperons. The in-medium properties of D and B mesons within the QCD sum rule approach depend upon the quark and gluon condensates. In the chiral SU(3) model, quark and gluon condensates are introduced through the explicit symmetry breaking term and the trace anomaly property of the QCD, respectively and are written in terms of the scalar fields σ, ζ, δ and χ. Hence, through medium modification of σ, ζ, δ and χ fields, we obtain the medium-modified masses and decay constants of D and B mesons. As an application, using {sup 3}P{sub 0} model, we calculate the in-medium decay width of the higher charmonium states ψ(3686), ψ(3770) and χ(3556) to the D anti D pairs, considering the in-medium mass of D mesons. These results may be important to understand the possible outcomes of the high-energy physics experiments, e.g., CBM and PANDA at GSI, Germany. (orig.)

  1. In-medium pseudoscalar D/B mesons and charmonium decay width

    Science.gov (United States)

    Chhabra, Rahul; Kumar, Arvind

    2017-05-01

    Using QCD sum rules and the chiral SU(3) model, we investigate the effect of temperature, density, strangeness fraction and isospin asymmetric parameter on the shift in masses and decay constants of the pseudoscalar D and B meson in the hadronic medium, which consist of nucleons and hyperons. The in-medium properties of D and B mesons within the QCD sum rule approach depend upon the quark and gluon condensates. In the chiral SU(3) model, quark and gluon condensates are introduced through the explicit symmetry breaking term and the trace anomaly property of the QCD, respectively and are written in terms of the scalar fields σ, ζ, δ and χ. Hence, through medium modification of σ, ζ, δ and χ fields, we obtain the medium-modified masses and decay constants of D and B mesons. As an application, using {}3P0 model, we calculate the in-medium decay width of the higher charmonium states ψ(3686), ψ(3770) and χ(3556) to the D\\bar{D} pairs, considering the in-medium mass of D mesons. These results may be important to understand the possible outcomes of the high-energy physics experiments, e.g., CBM and PANDA at GSI, Germany.

  2. Overview of medium heterogeneity and transport processes

    International Nuclear Information System (INIS)

    Tsang, Y.; Tsang, C.F.

    1993-11-01

    Medium heterogeneity can have significant impact on the behavior of solute transport. Tracer breakthrough curves from transport in a heterogeneous medium are distinctly different from that in a homogeneous porous medium. Usually the shape of the breakthrough curves are highly non-symmetrical with a fast rise at early times and very long tail at late times, and often, they consist of multiple peaks. Moreover, unlike transport in a homogeneous medium where the same transport parameters describe the entire medium, transport through heterogeneous media gives rise to breakthrough curves which have strong spatial dependence. These inherent characteristics of transport in heterogeneous medium present special challenge to the performance assessment of a potential high level nuclear waste repository with respect to the possible release of radio nuclides to the accessible environment. Since an inherently desirable site characteristic for a waste repository is that flow and transport should be slow, then transport measurements in site characterization efforts will necessarily be spatially small and temporally short compare to the scales which are of relevance to performance assessment predictions. In this paper we discuss the role of medium heterogeneity in site characterization and performance assessment. Our discussion will be based on a specific example of a 3D heterogeneous stochastic model of a site generally similar to, the Aespoe Island, the site of the Hard Rock Laboratory in Southern Sweden. For our study, alternative 3D stochastic fields of hydraulic conductivities conditioned on ''point'' measurements shall be generated. Results of stochastic flow and transport simulations would be used to address the issues of (1) the relationship of tracer breakthrough with the structure of heterogeneity, and (2) the inference from small scale testing results to large scale and long term predictions

  3. Evaluation of Insulin Medium or Chondrogenic Medium on Proliferation and Chondrogenesis of ATDC5 Cells

    OpenAIRE

    Yao, Yongchang; Zhai, Zhichen; Wang, Yingjun

    2014-01-01

    Background. The ATDC5 cell line is regarded as an excellent cell model for chondrogenesis. In most studies with ATDC5 cells, insulin medium (IM) was used to induce chondrogenesis while chondrogenic medium (CM), which was usually applied in chondrogenesis of mesenchymal stem cells (MSCs), was rarely used for ATDC5 cells. This study was mainly designed to investigate the effect of IM, CM, and growth medium (GM) on chondrogenesis of ATDC5 cells. Methods. ATDC5 cells were, respectively, cultured ...

  4. Modified harmony search

    Science.gov (United States)

    Mohamed, Najihah; Lutfi Amri Ramli, Ahmad; Majid, Ahmad Abd; Piah, Abd Rahni Mt

    2017-09-01

    A metaheuristic algorithm, called Harmony Search is quite highly applied in optimizing parameters in many areas. HS is a derivative-free real parameter optimization algorithm, and draws an inspiration from the musical improvisation process of searching for a perfect state of harmony. Propose in this paper Modified Harmony Search for solving optimization problems, which employs a concept from genetic algorithm method and particle swarm optimization for generating new solution vectors that enhances the performance of HS algorithm. The performances of MHS and HS are investigated on ten benchmark optimization problems in order to make a comparison to reflect the efficiency of the MHS in terms of final accuracy, convergence speed and robustness.

  5. Modified puestow lateral pancreaticojejunostomy.

    Science.gov (United States)

    Ceppa, Eugene P; Pappas, Theodore N

    2009-05-01

    There are various surgical options for the treatment of pain associated with chronic pancreatitis. The modified Puestow lateral pancreaticojejunostomy has been proven to be effective in ameliorating symptoms and expediting return to normal lifestyle while maintaining a low rate of morbidity and mortality. However, the debate regarding which surgical treatment provides the best outcomes is controversial. The aims of this manuscript are to identify the patient population for which the Puestow benefits the most and discuss the pertinent technical aspects of the surgical procedure.

  6. Effect of powdered spice treatments on mycelial growth, sporulation and production of aflatoxins by toxigenic fungi Efeito de tratamentos com condimentos em pó sobre o crescimento micelial, esporulação e produção de aflatoxinas por fungos toxigênicos

    Directory of Open Access Journals (Sweden)

    Sára Maria Chalfoun

    2004-08-01

    Full Text Available The effect of ten powdered spice plants was evaluated at the concentration of 1, 2, 3 and 4% to observe the mycelial growth and sporulation of Aspergillus niger and Eurotium repens. The spices were added to the culture media PDA and CYA20S. Clove completely inhibited the mycelial growth of the tested fungi. The other spices: cinnamon, garlic, thyme, mint, anis, oregano and onion were, in a decreasing order, promising antifungals. Bay leaf and basil did not show a pronounced fungistatic effect. The antitoxigenic potential of the spices was tested against one aflatoxin-producing strain of AspergiIIus flavus. The spices were tested at the same concentrations previously mentioned and were added to the culture medium YES, appropriate for the production of those metabolites. Clove completely inhibited the mycelial growth of Aspergillus flavus. Cinnamon and anis totally inhibited the production of Bl and B2 aflatoxin. Both bay leaf and basil inhibited the synthesis of aflatoxin starting from the concentration of 2%. The other spices did not have a pronounced antiaflatoxigenic effect.O efeito de dez plantas condimentares em pó foi avaliado nas concentrações de 1, 2, 3 e 4%, para observar o desenvolvimento micelial e esporulação de Aspergillus niger e Eurotium repens. Os condimentos foram adicionados aos meios de cultura BDA e CYA 20S. O cravo inibiu completamente o desenvolvimento micelial dos fungos testados. Os outros condimentos: canela, alho, tomilho, menta, erva-doce, orégano e cebola foram, em ordem decrescente, antifúngicos promissores. Louro e manjericão não apresentaram um efeito fungistático pronunciado. O potencial antitoxigênico dos condimentos foi testado contra uma cepa de Aspergillus flavus, produtora de aflatoxina. Os condimentos foram testados nas mesmas concentrações previamente mencionadas e foram adicionados ao meio de cultura YES, apropriado para a produção daqueles metabólitos. O cravo inibiu completamente o

  7. 'That proves my point': How mediums reconstrue disconfirmation in medium-sitter interactions.

    Science.gov (United States)

    Enoksen, Anette Einan; Dickerson, Paul

    2018-04-01

    Previous research has examined how the talk of mediums attends to the epistemological status of their readings. Such work has identified that mediums frequently use question-framed propositions that are typically confirmed by the sitter, thereby conferring epistemological status on the medium. This study seeks to investigate what happens when the sitter disconfirms the propositions of the medium. The study focuses on the ways in which such disconfirmation can be responded to such that it is reconstrued as evidence of the psychic nature of the medium's reading. Televised demonstrations of psychic readings involving British and US mediums and their sitters are analysed. The results suggest that mediums rework disconfirmation as proof in several ways: first, by emphasizing the different access that sitter and medium have to knowledge (e.g., about the future); second, as evidence that the medium has access to the actual voice of the deceased (and may therefore mishear what the deceased has said to them); and third, as revealing an important truth that has hitherto been concealed from the sitter. The implications of these findings are considered for cases where speakers bring different and potentially competing, epistemological resources to an interaction. © 2018 The British Psychological Society.

  8. CHROMagar Orientation Medium Reduces Urine Culture Workload

    Science.gov (United States)

    Manickam, Kanchana; Karlowsky, James A.; Adam, Heather; Lagacé-Wiens, Philippe R. S.; Rendina, Assunta; Pang, Paulette; Murray, Brenda-Lee

    2013-01-01

    Microbiology laboratories continually strive to streamline and improve their urine culture algorithms because of the high volumes of urine specimens they receive and the modest numbers of those specimens that are ultimately considered clinically significant. In the current study, we quantitatively measured the impact of the introduction of CHROMagar Orientation (CO) medium into routine use in two hospital laboratories and compared it to conventional culture on blood and MacConkey agars. Based on data extracted from our Laboratory Information System from 2006 to 2011, the use of CO medium resulted in a 28% reduction in workload for additional procedures such as Gram stains, subcultures, identification panels, agglutination tests, and biochemical tests. The average number of workload units (one workload unit equals 1 min of hands-on labor) per urine specimen was significantly reduced (P < 0.0001; 95% confidence interval [CI], 0.5326 to 1.047) from 2.67 in 2006 (preimplementation of CO medium) to 1.88 in 2011 (postimplementation of CO medium). We conclude that the use of CO medium streamlined the urine culture process and increased bench throughput by reducing both workload and turnaround time in our laboratories. PMID:23363839

  9. Stop Band Gap in Periodic Layers of Confined Atomic Vapor/Dielectric Medium

    International Nuclear Information System (INIS)

    Li Yuan-Yuan; Li Li; Lu Yi-Xin; Zhang Yan-Peng; Xu Ke-Wei

    2013-01-01

    A stop band gap is predicted in periodic layers of a confined atomic vapor/dielectric medium. Reflection and transmission profile of the layers over the band gap can be dramatically modified by the confined atoms and the number of layer periods. These gap and line features can be ascribed to the enhanced contribution of slow atoms induced by atom-wall collision, transient behavior of atom-light interaction and Fabry—Pérot effects in a thermal confined atomic system

  10. Modified Einstein and Navier–Stokes Equations

    Science.gov (United States)

    Bulyzhenkov, I. É.

    2018-05-01

    The appearance of inertial rest mass-energy is associated with the kinematic slowing-down of time and with the vortex state of the elementary massive space with zero integral of its kinetic and potential energies. An analog of the Einstein equation is found for moving densities of a non-empty metric space in the concept of the Einstein-Infeld material field. The vector consequences of this tensor equation for a metric medium of overlapping elementary carriers of continuous mass-energies allow us to modify the Navier-Stokes equation under inertial motion of the matter of the nonlocal field in the nonrelativistic limit. The nonlocality of massenergy generates kinematic accelerations of feedback to Newtonian acceleration, which impedes asymptotic divergence of energy fluxes. Stabilization of inertial media by dynamic Bernoulli pressure corresponds to nonlocal self-organization of Einstein-Infeld non-empty space and invalidates Newtonian localization of masses in empty space.

  11. Modified Einstein and Navier-Stokes Equations

    Science.gov (United States)

    Bulyzhenkov, I. É.

    2018-05-01

    The appearance of inertial rest mass-energy is associated with the kinematic slowing-down of time and with the vortex state of the elementary massive space with zero integral of its kinetic and potential energies. An analog of the Einstein equation is found for moving densities of a non-empty metric space in the concept of the Einstein-Infeld material field. The vector consequences of this tensor equation for a metric medium of overlapping elementary carriers of continuous mass-energies allow us to modify the Navier-Stokes equation under inertial motion of the matter of the nonlocal field in the nonrelativistic limit. The nonlocality of massenergy generates kinematic accelerations of feedback to Newtonian acceleration, which impedes asymptotic divergence of energy fluxes. Stabilization of inertial media by dynamic Bernoulli pressure corresponds to nonlocal self-organization of Einstein-Infeld non-empty space and invalidates Newtonian localization of masses in empty space.

  12. Notes on Narrative as Medium and a Media Ecology Approach to the Study of Storytelling

    Directory of Open Access Journals (Sweden)

    Lance Strate

    2014-11-01

    Full Text Available Storytelling, as a distinctively human characteristic, is a product of our capacity for language and symbolic communication. Just as language is considered a medium within the field of media ecology, so too can narrative be understood as a medium of communication, as well as a kind of language, and as a fundamentally social phenomenon. As a medium, narrative interacts with and is modified by other media, undergoing significant change as it is expressed through oral tradition, dramatic performance, written documents, and audiovisual media. In particular, major changes in the nature of character and plot accompany the shift from orality to literacy, and writing and especially printing make possible new forms of tragedy as opposed to comedy, prose as opposed to poetry, and fiction as opposed to nonfiction. Storytelling continues to mutate through the introduction of new media, with increasingly greater emphasis on narrative as an environment, especially one associated with social interaction and gaming.

  13. In-medium jet evolution: interplay between broadening and decoherence effects

    CERN Document Server

    Apolinário, Liliana; Milhano, Guilherme; Salgado, Carlos A.

    2016-01-01

    The description of the modifications of the coherence pattern in a parton shower, in the presence of a QGP, has been actively addressed in recent studies. Among the several achievements, finite energy corrections, transverse momentum broadening due to medium interactions and interference effects between successive emissions have been extensively improved as they seem to be essential features for a correct description of the results obtained in heavy-ion collisions. In this work, based on the insights of our previous work [1], we explore the physical interplay between broadening and decoherence, by generalising previous studies of medium-modifications of the antenna spectrum [2, 3, 4] - so far restricted to the case where transverse motion is neglected. The result allow us to identify two quantities controlling the decoherence of a medium modified shower that can be used as building blocks for a successful future generation of jet quenching Monte Carlo simulators: a generalisation of the $\\Delta_{med}$ paramet...

  14. Numerical investigation of degas performance on impeller of medium-consistency pump

    Directory of Open Access Journals (Sweden)

    Hong Li

    2015-12-01

    Full Text Available Medium-consistency technology is known as the process with high efficiency and low pollution. The gas distribution was simulated in the medium-consistency pump with different degas hole positions. Rheological behaviors of pulp suspension were obtained by experimental test. A modified Herschel–Bulkley model and the Eulerian gas–liquid two-phase flow model were utilized to approximately represent the behaviors of the medium-consistency pulp suspension. The results show that when the relative position is 0.53, the gas volume ratio is less than 0.1% at the pump outlet and 9.8% at the vacuum inlet, and the pump head is at the maximum. Because of the different numbers of the impeller blades and turbulence blades and the asymmetric volute structure, the gas is distributed unevenly in the impeller. In addition, the pump performance was tested in experiment and the results are used to validate computational fluid dynamics outcomes.

  15. Medium-induced gluon radiation and colour decoherence beyond the soft approximation

    CERN Document Server

    Apolinário, Liliana; Milhano, José Guilherme; Salgado, Carlos A

    2015-01-01

    We derive the in-medium gluon radiation spectrum off a quark within the path integral formalism at finite energies, including all next-to-eikonal corrections in the propagators of quarks and gluons. Results are computed for finite formation times, including interference with vacuum amplitudes. Rewriting the medium averages in a convenient manner we present the spectrum in terms of dipole cross sections and a colour decoherence parameter with the same physical origin as that found in previous studies of the antenna radiation. This factorisation allows us to present a simple physical picture of the medium-induced radiation for any value of the formation time, of interest for a probabilistic implementation of the modified parton shower. Interestingly -- and unexpectedly -- we also find a modification of the contribution from the hard vertex which cannot be factorized, at finite formation time, as the vacuum Altarelli-Parisi splitting function. Known results are recovered for the particular cases of soft radiatio...

  16. Hadrons in hot and dense medium

    International Nuclear Information System (INIS)

    Mallik, S.

    2004-01-01

    We review chiral perturbation theory in some detail and construct interaction terms involving the Goldstone and the different non-Goldstone fields, in presence of external (classical) fields coupled to currents. The ensemble average of the two-point functions of the currents can now be expanded in terms of Feynman diagrams. We evaluate the one-loop diagrams in the neighbourhood of the respective poles to find the effective couplings and masses of the particles in medium. We also describe the virial formula for the self-energy of a particle in medium, giving its pole position. It proves useful if the scattering amplitude of the particle with particles in medium is known experimentally. (author)

  17. Charmonium propagation through a dense medium

    Directory of Open Access Journals (Sweden)

    Kopeliovich B.Z.

    2015-01-01

    Full Text Available Attenuation of a colourless c̄c dipole propagating with a large momentum through a hot medium originates from two sources, Debye screening (melting, and inelastic collisions with surrounding scattering centres (absorption. The former never terminates completely production of a bound charmonium in heavy ion collisions, even at very high temperatures. The latter, is controlled my the magnitude of the dipole cross section, related to the transport coefficient, which is the rate of transverse momentum broadening in the medium. A novel procedure of Lorentz boosting of the Schrödinger equation is developed, which allows to calculate the charmonium survival probability employing the path-integral technique, incorporating both melting and absorption. A novel mechanism of charmonium regeneration in a dense medium is proposed.

  18. Coherent neutrino interactions in a dense medium

    International Nuclear Information System (INIS)

    Kiers, K.; Weiss, N.

    1997-01-01

    Motivated by the effect of matter on neutrino oscillations (the MSW effect) we study in more detail the propagation of neutrinos in a dense medium. The dispersion relation for massive neutrinos in a medium is known to have a minimum at nonzero momentum p∼G F ρ/√(2). We study in detail the origin and consequences of this dispersion relation for both Dirac and Majorana neutrinos both in a toy model with only neutral currents and a single neutrino flavor and in a realistic open-quotes standard modelclose quotes with two neutrino flavors. We find that for a range of neutrino momenta near the minimum of the dispersion relation, Dirac neutrinos are trapped by their coherent interactions with the medium. This effect does not lead to the trapping of Majorana neutrinos. copyright 1997 The American Physical Society

  19. Temperature distribution in a uniformly moving medium

    International Nuclear Information System (INIS)

    Mitchell, Joseph D; Petrov, Nikola P

    2009-01-01

    We apply several physical ideas to determine the steady temperature distribution in a medium moving with uniform velocity between two infinite parallel plates. We compute it in the coordinate frame moving with the medium by integration over the 'past' to account for the influence of an infinite set of instantaneous point sources of heat in past moments as seen by an observer moving with the medium. The boundary heat flux is simulated by appropriately distributed point heat sources on the inner side of an adiabatically insulating boundary. We make an extensive use of the Green functions with an emphasis on their physical meaning. The methodology used in this paper is of great pedagogical value as it offers an opportunity for students to see the connection between powerful mathematical techniques and their physical interpretation in an intuitively clear physical problem. We suggest several problems and a challenging project that can be easily incorporated in undergraduate or graduate courses

  20. Graphene wire medium: Homogenization and application

    DEFF Research Database (Denmark)

    Andryieuski, Andrei; Chigrin, Dmitry N.; Lavrinenko, Andrei

    2012-01-01

    In this contribution we analyze numerically the optical properties of the graphene wire medium, which unit cell consists of a stripe of graphene embedded into dielectric. We propose a simple method for retrieval of the isofrequency contour and effective permittivity tensor. As an example of the g......In this contribution we analyze numerically the optical properties of the graphene wire medium, which unit cell consists of a stripe of graphene embedded into dielectric. We propose a simple method for retrieval of the isofrequency contour and effective permittivity tensor. As an example...... of the graphene wire medium application we demonstrate a reconfigurable hyperlens for the terahertz subwavelength imaging capable of resolving two sources with separation λ0/5 in the far-field....

  1. Small and medium size nuclear reactors

    International Nuclear Information System (INIS)

    Al-Mugrabi, M.A.

    1996-01-01

    The purpose of this appendix is to provide up-to-date technical information relevant to the deployment of small and medium reactors (SMRs). It summarizes the status of SMRs and discusses areas of relevance to their utilization, including seawater desalination; and in particular their simplicity, their flexibility for a variety of applications and the use of passive safety features as fundamental to most of these designs. In response to important commercial developments, the energy range of small and medium reactors is now taken as being up to around 700 MW(e). Detailed information on SMR designs can be found in the IAEA report on The Design and Development Status of Small and Medium Reactor Systems 1995. 5 refs, 2 figs, 1 tab

  2. Avaliação de diferentes meios de cultura na esporulação de Scytalidium lignicola Evaluation of different culture media on the sporulation of Scytalidium lignicola

    Directory of Open Access Journals (Sweden)

    Juliana Paiva Carnaúba

    2007-06-01

    Full Text Available Scytalidium lignicola é um fungo que causa podridão negra em raízes e caules de mandioca. A esporulação de S. lignicola foi avaliada em 8 meios de cultura - BDA, SA, AvA, BSA, LCA, suco V-8, Mandioca-agar (MAND-A e MA - sob regime de alternância de luz (12h claro/12h escuro e 3 temperaturas (25 28 e 30ºC. Discos de 5mm de diâmetro retirados da borda da colônia cultivada em meio BDA, após 5 dias de incubação a 28ºC, foram transferidos para o centro de placas de Petri contendo 15mL de cada meio com inibidores seletivos. Após 5 dias de incubação, os esporos foram quantificados em contagens realizadas em câmara de Neubauer. O experimento seguiu delineamento inteiramente casualizado em esquema fatorial 8 x 3 (Meios x Temperaturas. Observou-se que houve diferença significativa apenas para os meios de cultura, não havendo diferença entre as temperaturas testadas. A esporulação de S. lignicola foi superior nos meios suco V-8, BDA, MAND-A, AvA, BSA e SA, não diferindo entre si estatisticamente. Enquanto nos meios MA e LCA ocorreram as menores esporulações, também não havendo diferença entre si.Scytalidium lignicola causes black root rot and stem rot on cassava plants. The sporulation of S. lignicola was evaluated in 8 different culture media as following: potato-dextrose-agar (PDA, soybean-agar, oat-extract-agar, potato-sucrose-agar (PSA, coconutextract-agar, V-8 juice-agar, cassava-agar and corn meal-agar, under light alternation (12h light/12h dark at three different temperatures 25, 28 and 30ºC. Discs measuring 5mm were removed from the border of a 5-days old fungus culture in PDA. These discs were transferred to the center of Petri dishes containing 15mL of each media with selective inhibitors. After 5 days of incubation, the spores were counted in a Neubauer chamber. The experiment was installed using a randomized block design in a factorial 8 media x 3 temperatures scheme. It was observed that the only significant

  3. Metodologia para produção de Metarhizium anisopliae (METSCH. sorokin em cultivo submerso: esporulação da biomassa, efeito da concentração de açúcar e custo do inoculant Methodology for production of Metarhizium anisopliae (METSCH. sorokin in submerged cultivation: biomass sporulation, sugar concentration effect and inoculant cost

    Directory of Open Access Journals (Sweden)

    Sonia Regina de Mello Pereira

    1999-09-01

    Full Text Available Desenvolveram-se um método de cultivo e um meio de cultura para produção massal do fungo Metarhizium anisopliae (Metsch. Sorokin, 1883, com maior pureza e concentração de conídios. Este método envolveu o cultivo submerso da linhagem M-61 do entomopatógeno em meio líquido de arroz parboilizado, extrato de levedura, extrato do percevejo da soja (Nezara viridula (L., 1758 Hemiptera, Pentatomidae, sob seis diferentes níveis de concentração de açúcar (0, 2, 4, 6, 8, 10g l-1, além do meio convencional sólido de arroz em grão. As biomassas obtidas foram separadas através de tela de nylon (63 mesh e dispostas em estufa para a esporulação. Os efeitos dos tratamentos foram avaliados pelos parâmetros pesos fresco e seco do micélio, número de conídios por grama de substrato, viabilidade e patogenicidade dos conídios sobre o percevejo. Observou-se que 2.0g l-1 de açúcar em meio de cultura de extrato de N. viridula produziu o dobro do número de conídios por grama de substrato em relação à concentração de 10.0g l-1, a um custo 51 vezes inferior ao obtido no processo convencional de produção do fungo. A viabilidade não foi afetada nos diferentes meios utilizados. Não ocorreram diferenças significativas na patogenicidade em função dos meios de cultura e métodos de cultivo.A method of cultivation and a culture medium were developed aiming at the mass production of fungus Metarhizium anisopliae (Metsch. Sorokin, 1883, with great concentration and purity of conidia. This method involved the M-61 strain of entomopathogenic fungus in liquid medium of rice, yeast extract, soybean bug extract (Nezara viridula (L., 1758 Hemiptera, Pentatomidae, under six differents concentrations of sugar (0, 2, 4, 6, 8, 10g l-1, and the solid conventional medium of rice grains. The biomasses obtained were filtered and put in an incubator to promote sporulation. The treatments were evaluated through the parameters wet and dry-weight of micelium

  4. H2 molecules and the intercloud medium

    International Nuclear Information System (INIS)

    Hill, J.K.; Hollenbach, D.J.

    1976-01-01

    We discuss expected column of densities of H 2 in the intercloud medium and the possible use of molecules as indicators of intercloud physical conditions. We treat molecule formation by the H - process and on graphite grains and show that the Barlow-Silk hypothesis of a 1 eV semichemical hydrogen-graphite bond leads to a large enhancement of the intercloud molecule formation rate. Rotational excitation calculations are presented for both cloud and intercloud conditions which show, in agreement with Jura, that the presently observed optically thin H 2 absorption components are more likely to originate in cold clouds than in the intercloud medium

  5. Medium for Children’s Creativity

    DEFF Research Database (Denmark)

    Borum, Nanna; Kristensen, Kasper; Petersson, Eva

    2014-01-01

    This paper reports on an exploratory study that investigates 16 elementary school children’s interaction with two different mediums for creativity, LEGO® bricks and paper collages, drawing on the previous creativity assessment test carried out by Amabile [1]. The study is based in a playful...... on labor when working with LEGO bricks. It was also evident that the children assigned preconceived affordances to the two mediums. The results from this study should feed into to a technology enhanced playful learning environment and these are the initial steps in the design process....

  6. Power converters for medium voltage networks

    CERN Document Server

    Islam, Md Rabiul; Zhu, Jianguo

    2014-01-01

    This book examines a number of topics, mainly in connection with advances in semiconductor devices and magnetic materials and developments in medium and large-scale renewable power plant technologies, grid integration techniques and new converter topologies, including advanced digital control systems for medium-voltage networks. The book's individual chapters provide an extensive compilation of fundamental theories and in-depth information on current research and development trends, while also exploring new approaches to overcoming some critical limitations of conventional grid integration te

  7. Structure and evolution of the interstellar medium

    International Nuclear Information System (INIS)

    Chieze, J.P.

    1985-10-01

    We give a two dimensional hydrodynamical analysis of HI clouds collisions in order to determine the mass spectrum of diffuse interstellar clouds. We have taken into account evaporation and abrasion by supernovae blast waves. The conditions for cloud merging or fragmentation are precised. Applications to the model of the interstellar medium of Mc Kee and Ostriker are also discussed. On the other hand, we show that molecular clouds belong to a one parameter family which can be identified to the sequence of the gravitationally unstable states of clouds bounded by the uniform pressure of the coronal phase of the interstellar medium. Hierarchical fragmentation of molecular clouds is analysed in this context [fr

  8. Biodegradable modified Phba systems

    International Nuclear Information System (INIS)

    Aniscenko, L.; Dzenis, M.; Erkske, D.; Tupureina, V.; Savenkova, L.; Muizniece - Braslava, S.

    2004-01-01

    Compositions as well as production technology of ecologically sound biodegradable multicomponent polymer systems were developed. Our objective was to design some bio plastic based composites with required mechanical properties and biodegradability intended for use as biodegradable packaging. Significant characteristics required for food packaging such as barrier properties (water and oxygen permeability) and influence of γ-radiation on the structure and changes of main characteristics of some modified PHB matrices was evaluated. It was found that barrier properties were plasticizers chemical nature and sterilization with γ-radiation dependent and were comparable with corresponding values of typical polymeric packaging films. Low γ-radiation levels (25 kGy) can be recommended as an effective sterilization method of PHB based packaging materials. Purposely designed bio plastic packaging may provide an alternative to traditional synthetic packaging materials without reducing the comfort of the end-user due to specific qualities of PHB - biodegradability, Biocompatibility and hydrophobic nature

  9. Modified Clipped LMS Algorithm

    Directory of Open Access Journals (Sweden)

    Lotfizad Mojtaba

    2005-01-01

    Full Text Available Abstract A new algorithm is proposed for updating the weights of an adaptive filter. The proposed algorithm is a modification of an existing method, namely, the clipped LMS, and uses a three-level quantization ( scheme that involves the threshold clipping of the input signals in the filter weight update formula. Mathematical analysis shows the convergence of the filter weights to the optimum Wiener filter weights. Also, it can be proved that the proposed modified clipped LMS (MCLMS algorithm has better tracking than the LMS algorithm. In addition, this algorithm has reduced computational complexity relative to the unmodified one. By using a suitable threshold, it is possible to increase the tracking capability of the MCLMS algorithm compared to the LMS algorithm, but this causes slower convergence. Computer simulations confirm the mathematical analysis presented.

  10. Modified arthroscopic Brostrom procedure.

    Science.gov (United States)

    Lui, Tun Hing

    2015-09-01

    The open modified Brostrom anatomic repair technique is widely accepted as the reference standard for lateral ankle stabilization. However, there is high incidence of intra-articular pathologies associated with chronic lateral ankle instability which may not be addressed by an isolated open Brostrom procedure. Arthroscopic Brostrom procedure with suture anchor has been described for anatomic repair of chronic lateral ankle instability and management of intra-articular lesions. However, the complication rates seemed to be higher than open Brostrom procedure. Modification of the arthroscopic Brostrom procedure with the use of bone tunnel may reduce the risk of certain complications. Copyright © 2015 European Foot and Ankle Society. Published by Elsevier Ltd. All rights reserved.

  11. Modified circular velocity law

    Science.gov (United States)

    Djeghloul, Nazim

    2018-05-01

    A modified circular velocity law is presented for a test body orbiting around a spherically symmetric mass. This law exhibits a distance scale parameter and allows to recover both usual Newtonian behaviour for lower distances and a constant velocity limit at large scale. Application to the Galaxy predicts the known behaviour and also leads to a galactic mass in accordance with the measured visible stellar mass so that additional dark matter inside the Galaxy can be avoided. It is also shown that this circular velocity law can be embedded in a geometrical description of spacetime within the standard general relativity framework upon relaxing the usual asymptotic flatness condition. This formulation allows to redefine the introduced Newtonian scale limit in term of the central mass exclusively. Moreover, a satisfactory answer to the galactic escape speed problem can be provided indicating the possibility that one can also get rid of dark matter halo outside the Galaxy.

  12. Carbon materials modified by plasma treatment as electrodes for supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Lota, Grzegorz; Frackowiak, Elzbieta [Institute of Chemistry and Technical Electrochemistry, Poznan University of Technology, Piotrowo 3, 60-965 Poznan (Poland); Tyczkowski, Jacek; Kapica, Ryszard [Technical University of Lodz, Faculty of Process and Environmental Engineering, Division of Molecular Engineering, Wolczanska 213, 90-924 Lodz (Poland); Lota, Katarzyna [Institute of Non-Ferrous Metals Branch in Poznan, Central Laboratory of Batteries and Cells, Forteczna 12, 61-362 Poznan (Poland)

    2010-11-15

    The carbon material was modified by RF plasma with various reactive gases: O{sub 2}, Ar and CO{sub 2}. Physicochemical properties of the final carbon products were characterized using different techniques such as gas adsorption method and XPS. Plasma modified materials enriched in oxygen functionalities were investigated as electrodes for supercapacitors in acidic medium. The electrochemical measurements have been carried out using cyclic voltammetry, galvanostatic charge/discharge and impedance spectroscopy. The electrochemical measurements have confirmed that capacity characteristics are closely connected with a type of plasma exposition. Modification processes have an influence on the kind and amount of surface functional groups in the carbon matrix. The moderate increase of capacity of carbon materials modified by plasma has been observed using symmetric two-electrode systems. Whereas investigations made in three-electrode system proved that the suitable selection of plasma modification parameters allows to obtain promising negative and positive electrode materials for supercapacitor application. (author)

  13. Modified quark-meson coupling model for nuclear matter

    International Nuclear Information System (INIS)

    Jin, X.; Jennings, B.K.

    1996-01-01

    The quark-meson coupling model for nuclear matter, which describes nuclear matter as nonoverlapping MIT bags bound by the self-consistent exchange of scalar and vector mesons, is modified by introducing medium modification of the bag constant. We model the density dependence of the bag constant in two different ways: One invokes a direct coupling of the bag constant to the scalar meson field, and the other relates the bag constant to the in-medium nucleon mass. Both models feature a decreasing bag constant with increasing density. We find that when the bag constant is significantly reduced in nuclear medium with respect to its free-space value, large canceling isoscalar Lorentz scalar and vector potentials for the nucleon in nuclear matter emerge naturally. Such potentials are comparable to those suggested by relativistic nuclear phenomenology and finite-density QCD sum rules. This suggests that the reduction of bag constant in nuclear medium may play an important role in low- and medium-energy nuclear physics. copyright 1996 The American Physical Society

  14. Optimizing culture medium for debittering constitutive enzyme ...

    African Journals Online (AJOL)

    STORAGESEVER

    2010-08-02

    Aug 2, 2010 ... naringinase on different matrices has been studied by many researchers (Busto et ... 10 g/L in the base medium compared to naringin control. Nitrogen ... Fermentation experiments were carried out in shaking flask for 5 days at 28°C with initial pH 6.0. † Values ..... fujikuroi mycelium in fluidized bioreactors.

  15. Wave propagation in thermoelastic saturated porous medium

    Indian Academy of Sciences (India)

    the existence and propagation of four waves in the medium. Three of the waves are ... predicted infinite speed for propagation of ther- mal signals. Lord and ..... saturated reservoir rock (North-sea Sandstone) is chosen for the numerical model ...

  16. Innovation in Small and Medium Firms.

    Science.gov (United States)

    Organisation for Economic Cooperation and Development, Paris (France). Committee for Scientific and Technical Personnel.

    A study analyzed the policies of 20 Organisation for Economic Cooperation and Development (OECD) member countries pertaining to small and medium enterprises (SMEs). Aims of the study were to assess the current role of SMEs as generators and users of innovations, to analyze the components of a favorable climate for innovation in SMEs, and to…

  17. The MIRI Medium Resolution Spectrometer calibration pipeline

    NARCIS (Netherlands)

    Labiano, A.; Azzollini, R.; Bailey, J.; Beard, S.; Dicken, D.; García-Marín, M.; Geers, V.; Glasse, A.; Glauser, A.; Gordon, K.; Justtanont, K.; Klaassen, P.; Lahuis, F.; Law, D.; Morrison, J.; Müller, M.; Rieke, G.; Vandenbussche, B.; Wright, G.

    2016-01-01

    The Mid-Infrared Instrument (MIRI) Medium Resolution Spectrometer (MRS) is the only mid-IR Integral Field Spectrometer on board James Webb Space Telescope. The complexity of the MRS requires a very specialized pipeline, with some specific steps not present in other pipelines of JWST instruments,

  18. Radiculography with water-soluble contraste medium

    International Nuclear Information System (INIS)

    Araujo Pinheiro, R.S. de

    1987-01-01

    The etiologic diagnosis of the lumbar pain is discussed. The radiculography with water-soluble contrast medium is used and 250 cases are studied. Some practical criteria of indication executation and interpretation of the examination are reported. (M.A.C.) [pt

  19. The Digital Medium Meets the Advertising Message.

    Science.gov (United States)

    Nisenholtz, Martin

    1994-01-01

    Discusses the likelihood that companies will use online services as an advertising medium. Topics addressed include the art of interactive marketing; advertising in the digital age; early experiments with interactive marketing, including the use of videotex and videodisc; and recent trends that set the stage for interactive marketing to personal…

  20. Influence of small and medium building engineering ...

    African Journals Online (AJOL)

    This study investigated the influence of small and medium building engineering entrepreneurship for the actualization of vision 20:2020 in Kebbi State, Nigeria. The study was conducted in Birnin Kebbi, Zuru and Argungu Local Government Areas of Kebbi State. The data were obtained from both primary and secondary ...