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Sample records for exogenously induced biofilm

  1. The danger signal extracellular ATP is an inducer of Fusobacterium nucleatum biofilm dispersal

    Directory of Open Access Journals (Sweden)

    Qinfeng Ding

    2016-11-01

    Full Text Available Plaque biofilm is the primary etiological agent of periodontal disease. Biofilm formation progresses through multiple developmental stages beginning with bacterial attachment to a surface, followed by development of microcolonies and finally detachment and dispersal from a mature biofilm as free planktonic bacteria. Tissue damage arising from inflammatory response to biofilm is one of the hallmark features of periodontal disease. A consequence of tissue damage is the release of ATP from within the cell into the extracellular space. Extracellular ATP (eATP is an example of a danger associated molecular pattern (DAMP employed by mammalian cells to elicit inflammatory and damage healing responses. Although the roles of eATP as a signaling molecule in multi-cellular organisms have been relatively well studied, exogenous ATP also influences bacteria biofilm formation. Since plaque biofilms are continuously exposed to various stresses including exposure to the host damage factors eATP, we hypothesized that eATP, in addition to eliciting inflammation could potentially influence the biofilm lifecycle of periodontal associated bacteria. We found that eATP rather than nutritional factors or oxidative stress induced dispersal of Fusobacterium nucleatum, an organism associated with periodontal disease. eATP induced biofilm dispersal through chelating metal ions present in biofilm. Dispersed F. nucleatum biofilm, regardless of natural or induced dispersal by exogenous ATP, were significantly more adhesive and invasive compared to planktonic or biofilm counterparts, and correspondingly activated significantly more pro-inflammatory cytokine production in infected periodontal fibroblasts. Dispersed F. nucleatum also exhibited significantly higher expression of fadA, a virulence factor implicated in adhesion and invasion, compared to planktonic or biofilm bacteria. This study revealed for the first time that periodontal bacterium is capable of co-opting eATP, a

  2. Characterization of starvation-induced dispersion in Pseudomonas putida biofilms

    DEFF Research Database (Denmark)

    Gjermansen, Morten; Ragas, Paula Cornelia; Sternberg, Claus

    2005-01-01

    The biofilm lifestyle, where microbial cells are aggregated because of expression of cell-to-cell interconnecting compounds, is believed to be of paramount importance to microbes in the environment. Because microbes must be able to alternate between sessile and planktonic states, it is anticipated...... that they must be able to regulate their ability to form biofilm and to dissolve biofilm. We present an investigation of a biofilm dissolution process occurring in flow-chamber-grown Pseudomonas putida biofilms. Local starvation-induced biofilm dissolution appears to be an integrated part of P. putida biofilm...... development that causes characteristic structural rearrangements. Rapid global dissolution of entire P. putida biofilms was shown to occur in response to carbon starvation. Genetic analysis suggested that the adjacent P. putida genes PP0164 and PP0165 play a role in P. putida biofilm formation and dissolution...

  3. Co-operative effect of exogenous dextranase and sodium fluoride on multispecies biofilms

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    Yuan-xin Qiu

    2016-03-01

    Conclusion: Overall, these findings reveal that a combination of 1 U/mL Dex and 80 μg/mL NaF is a promising candidate for disrupting complex cariogenic multispecies biofilms. This feature may be in that Dex loses the structure of biofilms, thereby facilitating NaF penetration and enhancing its antibacterial effects.

  4. Induction of Biofilm Formation in the Betaproteobacterium Burkholderia unamae CK43B Exposed to Exogenous Indole and Gallic Acid

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    Kim, Dongyeop; Sitepu, Irnayuli R.

    2013-01-01

    Burkholderia unamae CK43B, a member of the Betaproteobacteria that was isolated from the rhizosphere of a Shorea balangeran sapling in a tropical peat swamp forest, produces neither indole nor extracellular polymeric substances associated with biofilm formation. When cultured in a modified Winogradsky's medium supplemented with up to 1.7 mM indole, B. unamae CK43B maintains its planktonic state by cell swelling and effectively degrades exogenous indole. However, in medium supplemented with 1.7 mM exogenous indole and 1.0 mM gallic acid, B. unamae CK43B produced extracellular polymeric substances and formed a biofilm. The concentration indicated above of gallic acid alone had no effect on either the growth or the differentiation of B. unamae CK43B cells above a certain concentration threshold, whereas it inhibited indole degradation by B. unamae CK43B to 3-hydroxyindoxyl. In addition, coculture of B. unamae CK43B with indole-producing Escherichia coli in nutrient-rich Luria-Bertani medium supplemented with 1.0 mM gallic acid led to the formation of mixed cell aggregates. The viability and active growth of B. unamae CK43B cells in a coculture system with Escherichia coli were evidenced by fluorescence in situ hybridization. Our data thus suggest that indole facilitates intergenus communication between indole-producing gammaproteobacteria and some indole-degrading bacteria, particularly in gallic acid-rich environments. PMID:23747701

  5. Biofilm Induced Tolerance Towards Antimicrobial Peptides

    DEFF Research Database (Denmark)

    Folkesson, Anders; Haagensen, Janus Anders Juul; Zampaloni, Claudia

    2008-01-01

    Increased tolerance to antimicrobial agents is thought to be an important feature of microbes growing in biofilms. We address the question of how biofilm organization affects antibiotic susceptibility. We established Escherichia coli biofilms with differential structural organization due...... to the presence of IncF plasmids expressing altered forms of the transfer pili in two different biofilm model systems. The mature biofilms were subsequently treated with two antibiotics with different molecular targets, the peptide antibiotic colistin and the fluoroquinolone ciprofloxacin. The dynamics...... of microbial killing were monitored by viable count determination, and confocal laser microscopy. Strains forming structurally organized biofilms show an increased bacterial survival when challenged with colistin, compared to strains forming unstructured biofilms. The increased survival is due to genetically...

  6. Exogenous insulin antibody syndrome (EIAS): a clinical syndrome associated with insulin antibodies induced by exogenous insulin in diabetic patients.

    Science.gov (United States)

    Hu, Xiaolei; Chen, Fengling

    2018-01-01

    Insulin has been used for diabetes therapy and has achieved significant therapeutic effect. In recent years, the use of purified and recombinant human insulin preparations has markedly reduced, but not completely suppressed, the incidence of insulin antibodies (IAs). IAs induced by exogenous insulin in diabetic patients is associated with clinical events, which is named exogenous insulin antibody syndrome (EIAS). The present review is based on our research and summarizes the characterization of IAs, the factors affecting IA development, the clinical significance of IAs and the treatments for EIAS. © 2018 The authors.

  7. DNase I and proteinase K impair Listeria monocytogenes biofilm formation and induce dispersal of pre-existing biofilms.

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    Nguyen, Uyen T; Burrows, Lori L

    2014-09-18

    Current sanitation methods in the food industry are not always sufficient for prevention or dispersal of Listeria monocytogenes biofilms. Here, we determined if prevention of adherence or dispersal of existing biofilms could occur if biofilm matrix components were disrupted enzymatically. Addition of DNase during biofilm formation reduced attachment (biofilms with 100μg/ml of DNase for 24h induced incomplete biofilm dispersal, with biofilm remaining compared to control. In contrast, addition of proteinase K completely inhibited biofilm formation, and 72h biofilms-including those grown under stimulatory conditions-were completely dispersed with 100μg/ml proteinase K. Generally-regarded-as-safe proteases bromelain and papain were less effective dispersants than proteinase K. In a time course assay, complete dispersal of L. monocytogenes biofilms from both polystyrene and type 304H food-grade stainless steel occurred within 5min at proteinase K concentrations above 25μg/ml. These data confirm that both DNA and proteins are required for L. monocytogenes biofilm development and maintenance, and that these components of the biofilm matrix can be targeted for effective prevention and removal of biofilms. Copyright © 2014 Elsevier B.V. All rights reserved.

  8. Anaerobic bacteria grow within Candida albicans biofilms and induce biofilm formation in suspension cultures.

    Science.gov (United States)

    Fox, Emily P; Cowley, Elise S; Nobile, Clarissa J; Hartooni, Nairi; Newman, Dianne K; Johnson, Alexander D

    2014-10-20

    The human microbiome contains diverse microorganisms, which share and compete for the same environmental niches. A major microbial growth form in the human body is the biofilm state, where tightly packed bacterial, archaeal, and fungal cells must cooperate and/or compete for resources in order to survive. We examined mixed biofilms composed of the major fungal species of the gut microbiome, Candida albicans, and each of five prevalent bacterial gastrointestinal inhabitants: Bacteroides fragilis, Clostridium perfringens, Escherichia coli, Klebsiella pneumoniae, and Enterococcus faecalis. We observed that biofilms formed by C. albicans provide a hypoxic microenvironment that supports the growth of two anaerobic bacteria, even when cultured in ambient oxic conditions that are normally toxic to the bacteria. We also found that coculture with bacteria in biofilms induces massive gene expression changes in C. albicans, including upregulation of WOR1, which encodes a transcription regulator that controls a phenotypic switch in C. albicans, from the "white" cell type to the "opaque" cell type. Finally, we observed that in suspension cultures, C. perfringens induces aggregation of C. albicans into "mini-biofilms," which allow C. perfringens cells to survive in a normally toxic environment. This work indicates that bacteria and C. albicans interactions modulate the local chemistry of their environment in multiple ways to create niches favorable to their growth and survival. Copyright © 2014 Elsevier Ltd. All rights reserved.

  9. Biofilms.

    Science.gov (United States)

    López, Daniel; Vlamakis, Hera; Kolter, Roberto

    2010-07-01

    The ability to form biofilms is a universal attribute of bacteria. Biofilms are multicellular communities held together by a self-produced extracellular matrix. The mechanisms that different bacteria employ to form biofilms vary, frequently depending on environmental conditions and specific strain attributes. In this review, we emphasize four well-studied model systems to give an overview of how several organisms form biofilms: Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, and Staphylococcus aureus. Using these bacteria as examples, we discuss the key features of biofilms as well as mechanisms by which extracellular signals trigger biofilm formation.

  10. Induced effect of irradiated exogenous DNA on wheat

    International Nuclear Information System (INIS)

    Li Zhongjie; Sun Guangzu; Wang Guangjin

    1996-01-01

    Irradiated exogenous DNA introduced into wheat can give rise to break of DNA-chain and damage of part of alkali radicals. Introducing exogenous DNA irradiated by γ rays could increase Do fructification rate and decrease seed size and plumpness. These tendencies became obvious with dose increase. In comparison with control DNA, introducing DNA irradiated could raise evidently mutagenic effect of pollen tube pathway technique

  11. Hemin offers neuroprotection through inducing exogenous neuroglobin in focal cerebral hypoxic-ischemia in rats

    Science.gov (United States)

    Song, Xue; Xu, Rui; Xie, Fei; Zhu, Haiyuan; Zhu, Ji; Wang, Xin

    2014-01-01

    Objective: To investigate the inducible effect of hemin on exogenous neuroglobin (Ngb) in focal cerebral hypoxic-ischemia in rats. Methods: 125 healthy SD rats were randomly divided into five groups: sham-operation control group, operation group, hemin treatment group, exogenous Ngb treatment group, and hemin and exogenous Ngb joint treatment group. Twenty-four hours after focal cerebral hypoxic-ischemia, Ngb expression was evaluated by immunocytochemistry, RT-PCR, and western blot analyses, while the brain water content and infarct volume were examined. Results: Immunocytochemistry, RT-PCR, and western blot analyses showed more pronounced Ngb expression in the hemin and exogenous Ngb joint operation group than in the hemin or exogenous Ngb individual treatment groups, thus producing significant differences in brain water content and infarct volume (p exogenous Ngb. PMID:24966924

  12. Biofilms

    OpenAIRE

    López, Daniel; Vlamakis, Hera; Kolter, Roberto

    2010-01-01

    The ability to form biofilms is a universal attribute of bacteria. Biofilms are multicellular communities held together by a self-produced extracellular matrix. The mechanisms that different bacteria employ to form biofilms vary, frequently depending on environmental conditions and specific strain attributes. In this review, we emphasize four well-studied model systems to give an overview of how several organisms form biofilms: Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, and ...

  13. Preventive effects of chronic exogenous growth hormone levels on diet-induced hepatic steatosis in rats

    Directory of Open Access Journals (Sweden)

    Tian Ya-ping

    2010-07-01

    Full Text Available Abstract Background Non-alcoholic fatty liver disease (NAFLD, which is characterized by hepatic steatosis, can be reversed by early treatment. Several case reports have indicated that the administration of recombinant growth hormone (GH could improve fatty liver in GH-deficient patients. Here, we investigated whether chronic exogenous GH levels could improve hepatic steatosis induced by a high-fat diet in rats, and explored the underlying mechanisms. Results High-fat diet-fed rats developed abdominal obesity, fatty liver and insulin resistance. Chronic exogenous GH improved fatty liver, by reversing dyslipidaemia, fat accumulation and insulin resistance. Exogenous GH also reduced serum tumour necrosis factor-alpha (TNF-alpha levels, and ameliorated hepatic lipid peroxidation and oxidative stress. Hepatic fat deposition was also reduced by exogenous GH levels, as was the expression of adipocyte-derived adipokines (adiponectin, leptin and resistin, which might improve lipid metabolism and hepatic steatosis. Exogenous GH seems to improve fatty liver by reducing fat weight, improving insulin sensitivity and correcting oxidative stress, which may be achieved through phosphorylation or dephosphorylation of a group of signal transducers and activators of hepatic signal transduction pathways. Conclusions Chronic exogenous GH has positive effects on fatty liver and may be a potential clinical application in the prevention or reversal of fatty liver. However, chronic secretion of exogenous GH, even at a low level, may increase serum glucose and insulin levels in rats fed a standard diet, and thus increase the risk of insulin resistance.

  14. Exogenous cathepsin V protein protects human cardiomyocytes HCM from angiotensin Ⅱ-Induced hypertrophy.

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    Huang, Kun; Gao, Lu; Yang, Ming; Wang, Jiliang; Wang, Zheng; Wang, Lin; Wang, Guobin; Li, Huili

    2017-08-01

    Angiotensin (Ang) Ⅱ-induced cardiac hypertrophy can deteriorate to heart failure, a leading cause of mortality. Endogenous Cathepsin V (CTSV) has been reported to be cardioprotective against hypertrophy. However, little is known about the effect of exogenous CTSV on cardiac hypertrophy. We used the human cardiomyocytes HCM as a cell model to investigate the effects of exogenous CTSV on Ang Ⅱ-induced cardiac cell hypertrophy. Cell surface area and expression of classical markers of hypertrophy were analyzed. We further explored the mechanism of CTSV cardioprotective by assessing the levels and activities of PI3K/Akt/mTOR and MAPK signaling pathway proteins. We found that pre-treating cardiomyocytes with CTSV could significantly inhibit Ang Ⅱ-induced hypertrophy. The mRNA expression of hypertrophy markers ANP, BNP and β-MHC was obviously elevated in Ang Ⅱ-treated cardiac cells. Whereas, exogenous CTSV effectively halted this elevation. Further study revealed that the protective effects of exogenous CTSV might be mediated by repressing the phosphorylation of proteins in the PI3K/Akt/mTOR and MAPK pathways. Based on our results, we concluded that exogenous CTSV inhibited Ang Ⅱ-induced hypertrophy in HCM cells by inhibiting PI3K/Akt/mTOR. This study provides experimental evidence for the application of CTSV protein for the treatment of cardiac hypertrophy. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Motility of Pseudomonas aeruginosa contributes to SOS-inducible biofilm formation.

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    Chellappa, Shakinah T; Maredia, Reshma; Phipps, Kara; Haskins, William E; Weitao, Tao

    2013-12-01

    DNA-damaging antibiotics such as ciprofloxacin induce biofilm formation and the SOS response through autocleavage of SOS-repressor LexA in Pseudomonas aeruginosa. However, the biofilm-SOS connection remains poorly understood. It was investigated with 96-well and lipid biofilm assays. The effects of ciprofloxacin were examined on biofilm stimulation of the SOS mutant and wild-type strains. The stimulation observed in the wild-type in which SOS was induced was reduced in the mutant in which LexA was made non-cleavable (LexAN) and thus SOS non-inducible. Therefore, the stimulation appeared to involve SOS. The possible mechanisms of inducible biofilm formation were explored by subproteomic analysis of outer membrane fractions extracted from biofilms. The data predicted an inhibitory role of LexA in flagellum function. This premise was tested first by functional and morphological analyses of flagellum-based motility. The flagellum swimming motility decreased in the LexAN strain treated with ciprofloxacin. Second, the motility-biofilm assay was performed, which tested cell migration and biofilm formation. The results showed that wild-type biofilm increased significantly over the LexAN. These results suggest that LexA repression of motility, which is the initial event in biofilm development, contributes to repression of SOS-inducible biofilm formation. Copyright © 2013 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

  16. Elongator Plays a Positive Role in Exogenous NAD-Induced Defense Responses in Arabidopsis.

    Science.gov (United States)

    An, Chuanfu; Ding, Yezhang; Zhang, Xudong; Wang, Chenggang; Mou, Zhonglin

    2016-05-01

    Extracellular NAD is emerging as an important signal molecule in animal cells, but its role in plants has not been well-established. Although it has been shown that exogenous NAD(+) activates defense responses in Arabidopsis, components in the exogenous NAD(+)-activated defense pathway remain to be fully discovered. In a genetic screen for mutants insensitive to exogenous NAD(+) (ien), we isolated a mutant named ien2. Map-based cloning revealed that IEN2 encodes ELONGATA3 (ELO3)/AtELP3, a subunit of the Arabidopsis Elongator complex, which functions in multiple biological processes, including histone modification, DNA (de)methylation, and transfer RNA modification. Mutations in the ELO3/AtELP3 gene compromise exogenous NAD(+)-induced expression of pathogenesis-related (PR) genes and resistance to the bacterial pathogen Pseudomonas syringae pv. maculicola ES4326, and transgenic expression of the coding region of ELO3/AtELP3 in elo3/Atelp3 restores NAD(+) responsiveness to the mutant plants, demonstrating that ELO3/AtELP3 is required for exogenous NAD(+)-induced defense responses. Furthermore, mutations in genes encoding the other five Arabidopsis Elongator subunits (ELO2/AtELP1, AtELP2, ELO1/AtELP4, AtELP5, and AtELP6) also compromise exogenous NAD(+)-induced PR gene expression and resistance to P. syringae pv. maculicola ES4326. These results indicate that the Elongator complex functions as a whole in exogenous NAD(+)-activated defense signaling in Arabidopsis.

  17. Influence of biofilm lubricity on shear-induced transmission of staphylococcal biofilms from stainless steel to silicone rubber.

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    Gusnaniar, Niar; Sjollema, Jelmer; Jong, Ed D; Woudstra, Willem; de Vries, Joop; Nuryastuti, Titik; van der Mei, Henny C; Busscher, Henk J

    2017-11-01

    In real-life situations, bacteria are often transmitted from biofilms growing on donor surfaces to receiver ones. Bacterial transmission is more complex than adhesion, involving bacterial detachment from donor and subsequent adhesion to receiver surfaces. Here, we describe a new device to study shear-induced bacterial transmission from a (stainless steel) pipe to a (silicone rubber) tube and compare transmission of EPS-producing and non-EPS-producing staphylococci. Transmission of an entire biofilm from the donor to the receiver tube did not occur, indicative of cohesive failure in the biofilm rather than of adhesive failure at the donor-biofilm interface. Biofilm was gradually transmitted over an increasing length of receiver tube, occurring mostly to the first 50 cm of the receiver tube. Under high-shearing velocity, transmission of non-EPS-producing bacteria to the second half decreased non-linearly, likely due to rapid thinning of the lowly lubricious biofilm. Oppositely, transmission of EPS-producing strains to the second tube half was not affected by higher shearing velocity due to the high lubricity and stress relaxation of the EPS-rich biofilms, ensuring continued contact with the receiver. The non-linear decrease of ongoing bacterial transmission under high-shearing velocity is new and of relevance in for instance, high-speed food slicers and food packaging. © 2017 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology.

  18. The formation of green rust induced by tropical river biofilm components

    International Nuclear Information System (INIS)

    Jorand, F.; Zegeye, A.; Ghanbaja, J.; Abdelmoula, M.

    2011-01-01

    In the Sinnamary Estuary (French Guiana), a dense red biofilm grows on flooded surfaces. In order to characterize the iron oxides in this biofilm and to establish the nature of secondary minerals formed after anaerobic incubation, we conducted solid analysis and performed batch incubations. Elemental analysis indicated a major amount of iron as inorganic compartment along with organic matter. Solid analysis showed the presence of two ferric oxides ferrihydrite and lepidocrocite. Bacteria were abundant and represented more than 10 11 cells g -1 of dry weight among which iron reducers were revealed. Optical and electronic microscopy analysis revealed than the bacteria were in close vicinity of the iron oxides. After anaerobic incubations with exogenous electron donors, the biofilm's ferric material was reduced into green rust, a Fe II -Fe III layered double hydroxide. This green rust remained stable for several years. From this study and previous reports, we suggest that ferruginous biofilms should be considered as a favorable location for GR biomineralization when redox conditions and electron donors availability are gathered. - Research highlights: → Characterization of ferruginous biofilm components by solid analysis methods. → Lepidocrocite and ferrihydrite were the main iron oxides. → Anaerobic incubation of biofilm with electron donors produced green rust. → Biofilm components promote the formation of the green rust. → Ferruginous biofilm could contribute to the natural mercury attenuation.

  19. The formation of green rust induced by tropical river biofilm components

    Energy Technology Data Exchange (ETDEWEB)

    Jorand, F., E-mail: jorand@pharma.uhp-nancy.fr [Laboratoire de Chimie Physique et Microbiologie pour l' Environnement (LCPME) UMR 7564, CNRS-Nancy-Universite, Institut Jean Barriol, 405 rue de Vandoeuvre, F-54600 Villers-les Nancy (France); Zegeye, A. [Laboratoire de Chimie Physique et Microbiologie pour l' Environnement (LCPME) UMR 7564, CNRS-Nancy-Universite, Institut Jean Barriol, 405 rue de Vandoeuvre, F-54600 Villers-les Nancy (France); Ghanbaja, J. [Service Commun de Microscopies Electroniques et Microanalyses X (SCMEM), Nancy-Universite, Bvd des Aiguillettes, BP 239, 54506, Vandoeuvre-les-Nancy (France); Abdelmoula, M. [Laboratoire de Chimie Physique et Microbiologie pour l' Environnement (LCPME) UMR 7564, CNRS-Nancy-Universite, Institut Jean Barriol, 405 rue de Vandoeuvre, F-54600 Villers-les Nancy (France)

    2011-06-01

    In the Sinnamary Estuary (French Guiana), a dense red biofilm grows on flooded surfaces. In order to characterize the iron oxides in this biofilm and to establish the nature of secondary minerals formed after anaerobic incubation, we conducted solid analysis and performed batch incubations. Elemental analysis indicated a major amount of iron as inorganic compartment along with organic matter. Solid analysis showed the presence of two ferric oxides ferrihydrite and lepidocrocite. Bacteria were abundant and represented more than 10{sup 11} cells g{sup -1} of dry weight among which iron reducers were revealed. Optical and electronic microscopy analysis revealed than the bacteria were in close vicinity of the iron oxides. After anaerobic incubations with exogenous electron donors, the biofilm's ferric material was reduced into green rust, a Fe{sup II}-Fe{sup III} layered double hydroxide. This green rust remained stable for several years. From this study and previous reports, we suggest that ferruginous biofilms should be considered as a favorable location for GR biomineralization when redox conditions and electron donors availability are gathered. - Research highlights: {yields} Characterization of ferruginous biofilm components by solid analysis methods. {yields} Lepidocrocite and ferrihydrite were the main iron oxides. {yields} Anaerobic incubation of biofilm with electron donors produced green rust. {yields} Biofilm components promote the formation of the green rust. {yields} Ferruginous biofilm could contribute to the natural mercury attenuation.

  20. Exogenous iron and γ-irradiation induce NO-synthase synthesis in mouse liver

    International Nuclear Information System (INIS)

    Mikoyan, V.D.; Voevodskaya, N.V.; Kubrina, L.N.; Malenkova, I.V.; Vanin, A.F.

    1994-01-01

    Protein synthesis inhibitor (cycloheximide, CHI) and exogenous antioxidant (phenazan) suppress the synthesis of NO in mouse liver in vivo which is induced by administration to the animals of γ-irradiation, bacterial lipopolysaccharide (LPS), or Fe 2+ -citrate together with LPS. Biosynthesis of NO was monitored by the ESR signal of paramagnetic mononitrosyl iron complexes with the exogenous ligand diethyldithiocarbamate (MNIC-DETC) 30 min after addition of the ligand. The complexes arise from NO binding to DETC complexes with exogenous and endogenous Fe 2+ , which act as selective NO traps. The enhancement of NO biosynthesis after γ-irradiation or LPS or LPS + Fe 2+ -citrate is apparently due to the induction of the synthesis of NO-synthase, which is inhibited by cycloheximide. This process is triggered by reactive oxygen species, presumably through the activation of the transcription factor protein NFkB. The accumulation of free radical oxygen species is inhibited by the antioxidant phenazan

  1. Study on character variation induced by introducing exogenous DNA into upland cotton with ion implantation

    International Nuclear Information System (INIS)

    Cheng Beijiu; Tian Qiuyuan; Li Zhan; Zhou Liren

    1996-01-01

    The exogenous DNAs of G. Bickll P. and H. Cannabinus were introduced into the upland cotton Si 2 by Ar + implantation and DNA solution trickling method. The results showed that the exogenous DNA introduction was promoted significantly and the types and frequencies of character variation in progeny were increased by Ar + implantation. Furthermore, most of the variation tend to be stable. Among the Ar + implantation doses tested, 2 x 10 15 Ar + /cm 2 was the best for introducing exogenous DNA and inducing character variation, the variation rate reached to 16.2%. Some new lines with character of resistance to wilt disease, early maturity, few gland in seed and fine fiber quality have been obtained

  2. Lysinibacillus fusiformis M5 induces increased complexity in Bacillus subtilis 168 colony biofilms via hypoxanthine

    DEFF Research Database (Denmark)

    Gallegos-Monterrosa, Ramses; Kankel, Stefanie; Götze, Sebastian

    2017-01-01

    to identify soil bacteria, which induce architectural changes in biofilm colonies when cocultured with B. subtilis. We identified the soil bacterium Lysinibacillus fusiformis M5 as inducer of wrinkle-formation in B. subtilis colonies mediated by a diffusible signaling molecule. This compound was isolated......O, but not PbuG, is necessary for hypoxanthine to induce an increase in wrinkle formation of B. subtilis biofilm colonies. Our results suggest that hypoxanthine-stimulated wrinkle development is not due to a direct induction of biofilm-related gene expression, but rather caused by the excess of hypoxanthine...... within B. subtilis cells, which may lead to cell stress and death. Importance Biofilms are a bacterial lifestyle with high relevance regarding diverse human activities. Biofilms can be favorable, for instance in crop protection. In nature, biofilms are commonly found as multispecies communities...

  3. Exogenous insulin antibody syndrome (EIAS: a clinical syndrome associated with insulin antibodies induced by exogenous insulin in diabetic patients

    Directory of Open Access Journals (Sweden)

    Xiaolei Hu

    2018-01-01

    Full Text Available Insulin has been used for diabetes therapy and has achieved significant therapeutic effect. In recent years, the use of purified and recombinant human insulin preparations has markedly reduced, but not completely suppressed, the incidence of insulin antibodies (IAs. IAs induced by exogenous insulin in diabetic patients is associated with clinical events, which is named exogenous insulin antibody syndrome (EIAS. The present review is based on our research and summarizes the characterization of IAs, the factors affecting IA development, the clinical significance of IAs and the treatments for EIAS.

  4. Exogenous glutamate induces short and long-term potentiation in the rat medial vestibular nuclei.

    Science.gov (United States)

    Grassi, S; Frondaroli, A; Pessia, M; Pettorossi, V E

    2001-08-08

    In rat brain stem slices, high concentrations of exogenous glutamate induce long-term potentiation (LTP) of the field potentials evoked in the medial vestibular nuclei (MVN) by vestibular afferent stimulation. At low concentrations, glutamate can also induce short-term potentiation (STP), indicating that LTP and STP are separate events depending on the level of glutamatergic synapse activation. LTP and STP are prevented by blocking NMDA receptors and nitric oxide (NO) synthesis. Conversely, blocking platelet-activating factor (PAF) and group I metabotropic glutamate receptors only prevents the full development of LTP. Moreover, in the presence of blocking agents, glutamate causes transient inhibition, suggesting that when potentiation is impeded, exogenous glutamate can activate presynaptic mechanisms that reduce glutamate release.

  5. The contribution of endogenous and exogenous effects to radiation-induced damage in the bacterial spore

    International Nuclear Information System (INIS)

    Jacobs, G.P.; Samuni, A.; Czapski, G.

    1985-01-01

    Radical scavengers such as polyethylene glycol 400 and 4000 and bovine albumin have been used to define the contribution of exogenous and endogenous effects to the gamma-radiation-induced damage in aqueous buffered suspensions of Bacillus pumilus spores. The results indicate that this damage in the bacterial spore is predominantly endogenous both in the presence of 1 atmosphere of oxygen, and in anoxia. (author)

  6. Specific plant induced biofilm formation in Methylobacterium species

    Science.gov (United States)

    Rossetto, Priscilla B.; Dourado, Manuella N.; Quecine, Maria C.; Andreote, Fernando D.; Araújo, Welington L.; Azevedo, João L.; Pizzirani-Kleiner, Aline A.

    2011-01-01

    Two endophytic strains of Methylobacterium spp. were used to evaluate biofilm formation on sugarcane roots and on inert wooden sticks. Results show that biofilm formation is variable and that plant surface and possibly root exudates have a role in Methylobacterium spp. host recognition, biofilm formation and successful colonization as endophytes. PMID:24031703

  7. Mitigation of waterlogging-induced damages to pepper by exogenous meja

    International Nuclear Information System (INIS)

    Jun, O.; Bin, L.; Zhi, Y.B.

    2017-01-01

    In this study, we studied the mitigation effects of exogenous Methyl jasmonate (MeJA) on waterlogging-induced damages to Xinyou No.5 wrinkled skin pepper cultivar by spraying MeJA on leave's surface at different waterlogging periods and investigated its underlying mechanisms. The results showed that administration of MeJA increased antioxidant enzymes' activities, proline and soluble sugar contents and alcohol dehydrogenase (ADH) activity, reduced relative conductivity, malondialdehyde (MDA) and hydroxyl free radical (.OH) accumulation, lactate dehydrogenase (LDH) activity and lactic acid and acetaldehyde accumulation, and maintained high root malate dehydrogenase (MDH) and succinate dehydrogenase (SDH) activities and certain aerobic respiratory metabolism. The study also found that there were significant differences among exogenous MeJA treatments at different waterlogging periods. Peppers treated with exogenous MeJA 1 day and 2 days prior to waterlogging had optimal agronomic traits, higher chlorophyll content, enzymatic activities and osmolytic substances, as well as lower relative conductivity, MDA and ·OH accumulation. Overall, the results suggest that MeJA mitigates waterlogging-induced damages to pepper by adjusting osmolytic substances contents, antioxidant enzymatic activities and root respiration and metabolism and achieves better alleviation effects by spraying prior to waterlogging. (author)

  8. Effect of exogenous IAA on radiation-induced seedling growth in rice

    International Nuclear Information System (INIS)

    Bhattacharya, Shakuntala; Shama Rao, H.K.

    1978-01-01

    Rice seeds of var. D-6-2-2 were used to ascertain the interaction between exogenous IAA and low and high dose of γ-rays on seedling growth. Low doses of radiation (1,2 kR) and low concentrations of IAA(5,10 ppm) stimulated growth when applied independently. However, they proved inhibitory in combination, indicating the possibility of native IAA involvement at optimum level in radiation-induced stimulation. At a higher dose (5 kR), higher concentrations of exogenous IAA (50,100 ppm) resulted in a significant growth recovery over control. These results suggest that low doses of ionizing radiations probably accelerate the IAA synthesizing system leading to stimulation. (author)

  9. The chemical cue tetrabromopyrrole from a biofilm bacterium induces settlement of multiple Caribbean corals.

    Science.gov (United States)

    Sneed, Jennifer M; Sharp, Koty H; Ritchie, Kimberly B; Paul, Valerie J

    2014-07-07

    Microbial biofilms induce larval settlement for some invertebrates, including corals; however, the chemical cues involved have rarely been identified. Here, we demonstrate the role of microbial biofilms in inducing larval settlement with the Caribbean coral Porites astreoides and report the first instance of a chemical cue isolated from a marine biofilm bacterium that induces complete settlement (attachment and metamorphosis) of Caribbean coral larvae. Larvae settled in response to natural biofilms, and the response was eliminated when biofilms were treated with antibiotics. A similar settlement response was elicited by monospecific biofilms of a single bacterial strain, Pseudoalteromonas sp. PS5, isolated from the surface biofilm of a crustose coralline alga. The activity of Pseudoalteromonas sp. PS5 was attributed to the production of a single compound, tetrabromopyrrole (TBP), which has been shown previously to induce metamorphosis without attachment in Pacific acroporid corals. In addition to inducing settlement of brooded larvae (P. astreoides), TBP also induced larval settlement for two broadcast-spawning species, Orbicella (formerly Montastraea) franksi and Acropora palmata, indicating that this compound may have widespread importance among Caribbean coral species. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

  10. Exogenous HIV-1 Nef upsets the IFN-γ-induced impairment of human intestinal epithelial integrity.

    Directory of Open Access Journals (Sweden)

    Maria Giovanna Quaranta

    Full Text Available The mucosal tissues play a central role in the transmission of HIV-1 infection as well as in the pathogenesis of AIDS. Despite several clinical studies reported intestinal dysfunction during HIV infection, the mechanisms underlying HIV-induced impairments of mucosal epithelial barrier are still unclear. It has been postulated that HIV-1 alters enterocytic function and HIV-1 proteins have been detected in several cell types of the intestinal mucosa. In the present study, we analyzed the effect of the accessory HIV-1 Nef protein on human epithelial cell line.We used unstimulated or IFN-γ-stimulated Caco-2 cells, as a model for homeostatic and inflamed gastrointestinal tracts, respectively. We investigated the effect of exogenous recombinant Nef on monolayer integrity analyzing its uptake, transepithelial electrical resistance, permeability to FITC-dextran and the expression of tight junction proteins. Moreover, we measured the induction of proinflammatory mediators. Exogenous Nef was taken up by Caco-2 cells, increased intestinal epithelial permeability and upset the IFN-γ-induced reduction of transepithelial resistance, interfering with tight junction protein expression. Moreover, Nef inhibited IFN-γ-induced apoptosis and up-regulated TNF-α, IL-6 and MIP-3α production by Caco-2 cells while down-regulated IL-10 production. The simultaneous exposure of Caco-2 cells to Nef and IFN-γ did not affect cytokine secretion respect to untreated cells. Finally, we found that Nef counteracted the IFN-γ induced arachidonic acid cascade.Our findings suggest that exogenous Nef, perturbing the IFN-γ-induced impairment of intestinal epithelial cells, could prolong cell survival, thus allowing for accumulation of viral particles. Our results may improve the understanding of AIDS pathogenesis, supporting the discovery of new therapeutic interventions.

  11. Exogenous agmatine has neuroprotective effects against restraint-induced structural changes in the rat brain

    Science.gov (United States)

    Zhu, Meng-Yang; Wang, Wei-Ping; Cai, Zheng-Wei; Regunathan, Soundar; Ordway, Gregory

    2009-01-01

    Agmatine is an endogenous amine derived from decarboxylation of arginine catalysed by arginine decarboxylase. Agmatine is considered a novel neuromodulator and possesses neuroprotective properties in the central nervous system. The present study examined whether agmatine has neuroprotective effects against repeated restraint stress-induced morphological changes in rat medial prefrontal cortex and hippocampus. Sprague-Dawley rats were subjected to 6 h of restraint stress daily for 21 days. Immunohistochemical staining with β-tubulin III showed that repeated restraint stress caused marked morphological alterations in the medial prefrontal cortex and hippocampus. Stress-induced alterations were prevented by simultaneous treatment with agmatine (50 mg/kg/day, i.p.). Interestingly, endogenous agmatine levels, as measured by high-performance liquid chromatography, in the prefrontal cortex and hippocampus as well as in the striatum and hypothalamus of repeated restraint rats were significantly reduced as compared with the controls. Reduced endogenous agmatine levels in repeated restraint animals were accompanied by a significant increase of arginine decarboxylase protein levels in the same regions. Moreover, administration of exogenous agmatine to restrained rats abolished increases of arginine decarboxylase protein levels. Taken together, these results demonstrate that exogenously administered agmatine has neuroprotective effects against repeated restraint-induced structural changes in the medial prefrontal cortex and hippocampus. These findings indicate that stress-induced reductions in endogenous agmatine levels in the rat brain may play a permissive role in neuronal pathology induced by repeated restraint stress. PMID:18364017

  12. Low concentration of exogenous carbon monoxide protects mammalian cells against proliferation induced by radiation-induced bystander effect

    International Nuclear Information System (INIS)

    Tong, Liping; Yu, K.N.; Bao, Lingzhi; Wu, Wenqing; Wang, Hongzhi; Han, Wei

    2014-01-01

    Highlights: • We show the possibility of modulate proliferation induced by radiation-induced bystander effect with low concentration carbon monoxide. • Carbon monoxide inhibited proliferation via modulating the transforming growth factor β1 (TGF-β1)/nitric oxide (NO) signaling pathway. • Exogenous carbon monoxide has potential application in clinical radiotherapy. - Abstract: Radiation-induced bystander effect (RIBE) has been proposed to have tight relationship with the irradiation-caused secondary cancers beyond the irradiation-treated area after radiotherapy. Our previous studies demonstrated a protective effect of low concentration carbon monoxide (CO) on the genotoxicity of RIBE after α-particle irradiation. In the present work, a significant inhibitory effect of low-dose exogenous CO, generated by tricarbonyldichlororuthenium (II) dimer [CO-releasing molecule (CORM-2)], on both RIBE-induced proliferation and chromosome aberration was observed. Further studies on the mechanism revealed that the transforming growth factor β1/nitric oxide (NO) signaling pathway, which mediated RIBE signaling transduction, could be modulated by CO involved in the protective effects. Considering the potential of exogenous CO in clinical applications and its protective effect on RIBE, the present work aims to provide a foundation for potential application of CO in radiotherapy

  13. Low concentration of exogenous carbon monoxide protects mammalian cells against proliferation induced by radiation-induced bystander effect

    Energy Technology Data Exchange (ETDEWEB)

    Tong, Liping [Center of Medical Physics and Technology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031 (China); Yu, K.N. [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong (Hong Kong); Center of Medical Physics and Technology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031 (China); Bao, Lingzhi; Wu, Wenqing; Wang, Hongzhi [Center of Medical Physics and Technology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031 (China); Han, Wei, E-mail: hanw@hfcas.cn [Center of Medical Physics and Technology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031 (China)

    2014-01-15

    Highlights: • We show the possibility of modulate proliferation induced by radiation-induced bystander effect with low concentration carbon monoxide. • Carbon monoxide inhibited proliferation via modulating the transforming growth factor β1 (TGF-β1)/nitric oxide (NO) signaling pathway. • Exogenous carbon monoxide has potential application in clinical radiotherapy. - Abstract: Radiation-induced bystander effect (RIBE) has been proposed to have tight relationship with the irradiation-caused secondary cancers beyond the irradiation-treated area after radiotherapy. Our previous studies demonstrated a protective effect of low concentration carbon monoxide (CO) on the genotoxicity of RIBE after α-particle irradiation. In the present work, a significant inhibitory effect of low-dose exogenous CO, generated by tricarbonyldichlororuthenium (II) dimer [CO-releasing molecule (CORM-2)], on both RIBE-induced proliferation and chromosome aberration was observed. Further studies on the mechanism revealed that the transforming growth factor β1/nitric oxide (NO) signaling pathway, which mediated RIBE signaling transduction, could be modulated by CO involved in the protective effects. Considering the potential of exogenous CO in clinical applications and its protective effect on RIBE, the present work aims to provide a foundation for potential application of CO in radiotherapy.

  14. Fibrinogen-Induced Streptococcus mutans Biofilm Formation and Adherence to Endothelial Cells

    Directory of Open Access Journals (Sweden)

    Telma Blanca Lombardo Bedran

    2013-01-01

    Full Text Available Streptococcus mutans, the predominant bacterial species associated with dental caries, can enter the bloodstream and cause infective endocarditis. The aim of this study was to investigate S. mutans biofilm formation and adherence to endothelial cells induced by human fibrinogen. The putative mechanism by which biofilm formation is induced as well as the impact of fibrinogen on S. mutans resistance to penicillin was also evaluated. Bovine plasma dose dependently induced biofilm formation by S. mutans. Of the various plasma proteins tested, only fibrinogen promoted the formation of biofilm in a dose-dependent manner. Scanning electron microscopy observations revealed the presence of complex aggregates of bacterial cells firmly attached to the polystyrene support. S. mutans in biofilms induced by the presence of fibrinogen was markedly resistant to the bactericidal effect of penicillin. Fibrinogen also significantly increased the adherence of S. mutans to endothelial cells. Neither S. mutans cells nor culture supernatants converted fibrinogen into fibrin. However, fibrinogen is specifically bound to the cell surface of S. mutans and may act as a bridging molecule to mediate biofilm formation. In conclusion, our study identified a new mechanism promoting S. mutans biofilm formation and adherence to endothelial cells which may contribute to infective endocarditis.

  15. Formation, Accumulation, and Hydrolysis of Endogenous and Exogenous Formaldehyde-Induced DNA Damage

    Science.gov (United States)

    Yu, Rui; Lai, Yongquan; Hartwell, Hadley J.; Moeller, Benjamin C.; Doyle-Eisele, Melanie; Kracko, Dean; Bodnar, Wanda M.; Starr, Thomas B.; Swenberg, James A.

    2015-01-01

    Formaldehyde is not only a widely used chemical with well-known carcinogenicity but is also a normal metabolite of living cells. It thus poses unique challenges for understanding risks associated with exposure. N2-hydroxymethyl-dG (N2-HOMe-dG) is the main formaldehyde-induced DNA mono-adduct, which together with DNA-protein crosslinks (DPCs) and toxicity-induced cell proliferation, play important roles in a mutagenic mode of action for cancer. In this study, N2-HOMe-dG was shown to be an excellent biomarker for direct adduction of formaldehyde to DNA and the hydrolysis of DPCs. The use of inhaled [13CD2]-formaldehyde exposures of rats and primates coupled with ultrasensitive nano ultra performance liquid chromatography-tandem mass spectrometry permitted accurate determinations of endogenous and exogenous formaldehyde DNA damage. The results show that inhaled formaldehyde only reached rat and monkey noses, but not tissues distant to the site of initial contact. The amounts of exogenous adducts were remarkably lower than those of endogenous adducts in exposed nasal epithelium. Moreover, exogenous adducts accumulated in rat nasal epithelium over the 28-days exposure to reach steady-state concentrations, followed by elimination with a half-life (t1/2) of 7.1 days. Additionally, we examined artifact formation during DNA preparation to ensure the accuracy of nonlabeled N2-HOMe-dG measurements. These novel findings provide critical new data for understanding major issues identified by the National Research Council Review of the 2010 Environmental Protection Agency’s Draft Integrated Risk Information System Formaldehyde Risk Assessment. They support a data-driven need for reflection on whether risks have been overestimated for inhaled formaldehyde, whereas underappreciating endogenous formaldehyde as the primary source of exposure that results in bone marrow toxicity and leukemia in susceptible humans and rodents deficient in DNA repair. PMID:25904104

  16. Nitric oxide from both exogenous and endogenous sources activates mitochondria-dependent events and induces insults to human chondrocytes.

    Science.gov (United States)

    Wu, Gong-Jhe; Chen, Tyng-Guey; Chang, Huai-Chia; Chiu, Wen-Ta; Chang, Chia-Chen; Chen, Ruei-Ming

    2007-08-15

    During inflammation, overproduction of nitric oxide (NO) can damage chondrocytes. In this study, we separately evaluated the toxic effects of exogenous and endogenous NO on human chondrocytes and their possible mechanisms. Human chondrocytes were exposed to sodium nitroprusside (SNP), an NO donor, or a combination of lipopolysaccharide (LPS) and interferon-gamma (IFN-gamma) as the exogenous and endogenous sources of NO, respectively. Administration of SNP or a combination of LPS and IFN-gamma in human chondrocytes increased cellular NO levels but decreased cell viability. Exposure to exogenous or endogenous NO significantly induced apoptosis of human chondrocytes. When treated with exogenous or endogenous NO, the mitochondrial membrane potential time-dependently decreased. Exposure to exogenous or endogenous NO significantly enhanced cellular reactive oxygen species (ROS) and cytochrome c (Cyt c) levels. Administration of exogenous or endogenous NO increased caspase-3 activity and consequently induced DNA fragmentation. Suppression of caspase-3 activation by Z-DEVD-FMK decreased NO-induced DNA fragmentation and cell apoptosis. Similar to SNP, exposure of human chondrocytes to S-nitrosoglutathione (GSNO), another NO donor, caused significant increases in Cyt c levels, caspase-3 activity, and DNA fragmentation, and induced cell apoptosis. Pretreatment with N-monomethyl arginine (NMMA), an inhibitor of NO synthase, significantly decreased cellular NO levels, and lowered endogenous NO-induced alterations in cellular Cyt c amounts, caspase-3 activity, DNA fragmentation, and cell apoptosis. Results of this study show that NO from exogenous and endogenous sources can induce apoptotic insults to human chondrocytes via a mitochondria-dependent mechanism.

  17. Effects of exogenous carbon monoxide on radiation-induced bystander effect in zebrafish embryos in vivo

    International Nuclear Information System (INIS)

    Choi, V.W.Y.; Wong, M.Y.P.; Cheng, S.H.; Yu, K.N.

    2012-01-01

    In the present work, the influence of a low concentration of exogenous carbon monoxide (CO) liberated from tricarbonylchloro(glycinato)ruthenium (II) (CORM-3) on the radiation induced bystander effect (RIBE) in vivo between embryos of the zebrafish was studied. RIBE was assessed through the number of apoptotic signals revealed on embryos at 25 h post fertilization (hpf). A significant attenuation of apoptosis on the bystander embryos induced by RIBE in a CO concentration dependent manner was observed. - Highlights: ► RIBE between zebrafish embryos in vivo was assessed by the level of apoptosis. ► CO from 10 and 20 μM CORM-3 entirely suppressed the RIBE. ► CO from 5 μM CORM-3 significantly attenuated the level of apoptosis. ► Inactive CORM-3 did not lead to suppression of RIBE. ► Suppression of RIBE by CO depended on the concentration of CORM-3.

  18. The effects of exogenous surfactant administration on ventilation-induced inflammation in mouse models of lung injury.

    Science.gov (United States)

    Puntorieri, Valeria; Hiansen, Josh Qua; McCaig, Lynda A; Yao, Li-Juan; Veldhuizen, Ruud A W; Lewis, James F

    2013-11-20

    Mechanical ventilation (MV) is an essential supportive therapy for acute lung injury (ALI); however it can also contribute to systemic inflammation. Since pulmonary surfactant has anti-inflammatory properties, the aim of the study was to investigate the effect of exogenous surfactant administration on ventilation-induced systemic inflammation. Mice were randomized to receive an intra-tracheal instillation of a natural exogenous surfactant preparation (bLES, 50 mg/kg) or no treatment as a control. MV was then performed using the isolated and perfused mouse lung (IPML) set up. This model allowed for lung perfusion during MV. In experiment 1, mice were exposed to mechanical ventilation only (tidal volume =20 mL/kg, 2 hours). In experiment 2, hydrochloric acid or air was instilled intra-tracheally four hours before applying exogenous surfactant and ventilation (tidal volume =5 mL/kg, 2 hours). For both experiments, exogenous surfactant administration led to increased total and functional surfactant in the treated groups compared to the controls. Exogenous surfactant administration in mice exposed to MV only did not affect peak inspiratory pressure (PIP), lung IL-6 levels and the development of perfusate inflammation compared to non-treated controls. Acid injured mice exposed to conventional MV showed elevated PIP, lung IL-6 and protein levels and greater perfusate inflammation compared to air instilled controls. Instillation of exogenous surfactant did not influence the development of lung injury. Moreover, exogenous surfactant was not effective in reducing the concentration of inflammatory cytokines in the perfusate. The data indicates that exogenous surfactant did not mitigate ventilation-induced systemic inflammation in our models. Future studies will focus on altering surfactant composition to improve its immuno-modulating activity.

  19. Induced Polarization Signature of Biofilms in Porous Media: From Laboratory Experiments to Theoretical Developments and Validation

    Energy Technology Data Exchange (ETDEWEB)

    Atekwana, Estella [Oklahoma State Univ., Stillwater, OK (United States); Patrauchan, Marianna [Oklahoma State Univ., Stillwater, OK (United States); Revil, Andre [Colorado School of Mines, Golden, CO (United States)

    2016-10-04

    Bioremediation strategies for mitigating the transport of heavy metals and radionuclides in subsurface sediments have largely targeted the use of dissimilatory metal and sulfate-reducing bacteria. Growth and metabolic activities from these organisms can significantly influence biogeochemical processes, including mineral dissolution/precipitation, fluctuating pH and redox potential (Eh) values, development of biofilms, and decreasing hydraulic conductivity. The Spectral Induced Polarization (SIP) technique has emerged as the technique most sensitive to the presence of microbial cells and biofilms in porous media; yet it is often difficult to unambiguously distinguish the impact of multiple and often competing processes that occur during in-situ biostimulation activities on the SIP signatures. The main goal of our project is to quantitatively characterize major components within bacterial biofilms (cells, DNA, metals, metabolites etc.) contributing to detectable SIP signatures. We specifically: (i) evaluated the contribution of biofilm components to SIP signatures, (ii) determined the contribution of biogenic minerals commonly found in biofilms to SIP signatures, (iii) determined if the SIP signatures can be used to quantify the rates of biofilm formation, (iv) developed models and a fundamental understanding of potential underlying polarization mechanisms at low frequencies (<40 kHz) resulting from the presence of microbial cells and biofilms

  20. Lysinibacillus fusiformis M5 Induces Increased Complexity in Bacillus subtilis 168 Colony Biofilms via Hypoxanthine.

    Science.gov (United States)

    Gallegos-Monterrosa, Ramses; Kankel, Stefanie; Götze, Sebastian; Barnett, Robert; Stallforth, Pierre; Kovács, Ákos T

    2017-11-15

    In recent years, biofilms have become a central subject of research in the fields of microbiology, medicine, agriculture, and systems biology, among others. The sociomicrobiology of multispecies biofilms, however, is still poorly understood. Here, we report a screening system that allowed us to identify soil bacteria which induce architectural changes in biofilm colonies when cocultured with Bacillus subtilis We identified the soil bacterium Lysinibacillus fusiformis M5 as an inducer of wrinkle formation in B. subtilis colonies mediated by a diffusible signaling molecule. This compound was isolated by bioassay-guided chromatographic fractionation. The elicitor was identified to be the purine hypoxanthine using mass spectrometry and nuclear magnetic resonance (NMR) spectroscopy. We show that the induction of wrinkle formation by hypoxanthine is not dependent on signal recognition by the histidine kinases KinA, KinB, KinC, and KinD, which are generally involved in phosphorylation of the master regulator Spo0A. Likewise, we show that hypoxanthine signaling does not induce the expression of biofilm matrix-related operons epsABCDEFGHIJKLMNO and tasA-sipW-tapA Finally, we demonstrate that the purine permease PbuO, but not PbuG, is necessary for hypoxanthine to induce an increase in wrinkle formation of B. subtilis biofilm colonies. Our results suggest that hypoxanthine-stimulated wrinkle development is not due to a direct induction of biofilm-related gene expression but rather is caused by the excess of hypoxanthine within B. subtilis cells, which may lead to cell stress and death. IMPORTANCE Biofilms are a bacterial lifestyle with high relevance regarding diverse human activities. Biofilms can be beneficial, for instance, in crop protection. In nature, biofilms are commonly found as multispecies communities displaying complex social behaviors and characteristics. The study of interspecies interactions will thus lead to a better understanding and use of biofilms as they

  1. Genetics of dwarfness in induced mutants of hexaploid triticale and its response to exogenous GA3

    International Nuclear Information System (INIS)

    Reddy, V.D.; Reddy, G.M.

    1991-01-01

    Genetics of dwarfism in two induced mutant (d 1 and d 2 ) of hexaploid triticale, DTS 330, revealed that this trait is governed by single recessive gene. Both d 1 and d 2 were allelic to each other and d 1 was dominant over d 2 . Both d 1 , d 2 and their F 1 showed no response to exogenous GA 3 , whereas, DTS 330, d 1 x DTS 330 and d 2 x DTS 330 were responsive. The endogenous levels of GA 3 were more in the dwarf mutants than control, suggesting that dwarfness in these may be due to a partial block in the GA utilizing mechanism, rather than a block in GA biosynthesis. (author). 5 refs., 2 tabs

  2. Formation, Accumulation, and Hydrolysis of Endogenous and Exogenous Formaldehyde-Induced DNA Damage.

    Science.gov (United States)

    Yu, Rui; Lai, Yongquan; Hartwell, Hadley J; Moeller, Benjamin C; Doyle-Eisele, Melanie; Kracko, Dean; Bodnar, Wanda M; Starr, Thomas B; Swenberg, James A

    2015-07-01

    Formaldehyde is not only a widely used chemical with well-known carcinogenicity but is also a normal metabolite of living cells. It thus poses unique challenges for understanding risks associated with exposure. N(2-)hydroxymethyl-dG (N(2)-HOMe-dG) is the main formaldehyde-induced DNA mono-adduct, which together with DNA-protein crosslinks (DPCs) and toxicity-induced cell proliferation, play important roles in a mutagenic mode of action for cancer. In this study, N(2)-HOMe-dG was shown to be an excellent biomarker for direct adduction of formaldehyde to DNA and the hydrolysis of DPCs. The use of inhaled [(13)CD2]-formaldehyde exposures of rats and primates coupled with ultrasensitive nano ultra performance liquid chromatography-tandem mass spectrometry permitted accurate determinations of endogenous and exogenous formaldehyde DNA damage. The results show that inhaled formaldehyde only reached rat and monkey noses, but not tissues distant to the site of initial contact. The amounts of exogenous adducts were remarkably lower than those of endogenous adducts in exposed nasal epithelium. Moreover, exogenous adducts accumulated in rat nasal epithelium over the 28-days exposure to reach steady-state concentrations, followed by elimination with a half-life (t1/2) of 7.1 days. Additionally, we examined artifact formation during DNA preparation to ensure the accuracy of nonlabeled N(2)-HOMe-dG measurements. These novel findings provide critical new data for understanding major issues identified by the National Research Council Review of the 2010 Environmental Protection Agency's Draft Integrated Risk Information System Formaldehyde Risk Assessment. They support a data-driven need for reflection on whether risks have been overestimated for inhaled formaldehyde, whereas underappreciating endogenous formaldehyde as the primary source of exposure that results in bone marrow toxicity and leukemia in susceptible humans and rodents deficient in DNA repair. © The Author 2015

  3. Type I interferons induced by endogenous or exogenous viral infections promote metastasis and relapse of leishmaniasis.

    Science.gov (United States)

    Rossi, Matteo; Castiglioni, Patrik; Hartley, Mary-Anne; Eren, Remzi Onur; Prével, Florence; Desponds, Chantal; Utzschneider, Daniel T; Zehn, Dietmar; Cusi, Maria G; Kuhlmann, F Matthew; Beverley, Stephen M; Ronet, Catherine; Fasel, Nicolas

    2017-05-09

    The presence of the endogenous Leishmania RNA virus 1 (LRV1) replicating stably within some parasite species has been associated with the development of more severe forms of leishmaniasis and relapses after drug treatment in humans. Here, we show that the disease-exacerbatory role of LRV1 relies on type I IFN (type I IFNs) production by macrophages and signaling in vivo. Moreover, infecting mice with the LRV1-cured Leishmania guyanensis ( LgyLRV1 - ) strain of parasites followed by type I IFN treatment increased lesion size and parasite burden, quantitatively reproducing the LRV1-bearing ( LgyLRV1 + ) infection phenotype. This finding suggested the possibility that exogenous viral infections could likewise increase pathogenicity, which was tested by coinfecting mice with L. guyanensis and lymphocytic choriomeningitis virus (LCMV), or the sand fly-transmitted arbovirus Toscana virus (TOSV). The type I IFN antiviral response increased the pathology of L. guyanensis infection, accompanied by down-regulation of the IFN-γ receptor normally required for antileishmanial control. Further, LCMV coinfection of IFN-γ-deficient mice promoted parasite dissemination to secondary sites, reproducing the LgyLRV1 + metastatic phenotype. Remarkably, LCMV coinfection of mice that had healed from L. guyanensis infection induced reactivation of disease pathology, overriding the protective adaptive immune response. Our findings establish that type I IFN-dependent responses, arising from endogenous viral elements (dsRNA/LRV1), or exogenous coinfection with IFN-inducing viruses, are able to synergize with New World Leishmania parasites in both primary and relapse infections. Thus, viral infections likely represent a significant risk factor along with parasite and host factors, thereby contributing to the pathological spectrum of human leishmaniasis.

  4. Exogenous nitrate induces root branching and inhibits primary root growth in Capsicum chinense Jacq.

    Science.gov (United States)

    Celis-Arámburo, Teresita de Jesús; Carrillo-Pech, Mildred; Castro-Concha, Lizbeth A; Miranda-Ham, María de Lourdes; Martínez-Estévez, Manuel; Echevarría-Machado, Ileana

    2011-12-01

    The effects of nitrate (NO₃⁻) on the root system are complex and depend on several factors, such as the concentration available to the plant, endogenous nitrogen status and the sensitivity of the species. Though these effects have been widely documented on Arabidopsis and cereals, no reports are available in the Capsicum genus. In this paper, we have determined the effect of an exogenous in vitro application of this nutrient on root growth in habanero pepper (Capsicum chinense Jacq.). Exposure to NO₃⁻ inhibited primary root growth in both, dose- and time-dependent manners. The highest inhibition was attained with 0.1 mM NO₃⁻ between the fourth and fifth days of treatment. Inhibition of primary root growth was observed by exposing the root to both homogeneous and heterogeneous conditions of the nutrient; in contrast, ammonium was not able to induce similar changes. NO₃⁻-induced inhibition of primary root growth was reversed by treating the roots with IAA or NPA, a polar auxin transport inhibitor. Heterogeneous NO₃⁻ application stimulated the formation and elongation of lateral roots in the segment where the nutrient was present, and this response was influenced by exogenous phytohormones. These results demonstrate that habanero pepper responds to NO₃⁻ in a similar fashion to other species with certain particular differences. Therefore, studies in this model could help to elucidate the mechanisms by which roots respond to NO₃⁻ in fluctuating soil environments. Copyright © 2011 Elsevier Masson SAS. All rights reserved.

  5. Characterization of a mycobacterial cellulase and its impact on biofilm- and drug-induced cellulose production.

    Science.gov (United States)

    Van Wyk, Niël; Navarro, David; Blaise, Mickaël; Berrin, Jean-Guy; Henrissat, Bernard; Drancourt, Michel; Kremer, Laurent

    2017-05-01

    It was recently shown that Mycobacterium tuberculosis produces cellulose which forms an integral part of its extracellular polymeric substances within a biofilm set-up. Using Mycobacterium smegmatis as a proxy model organism, we demonstrate that M. smegmatis biofilms treated with purified MSMEG_6752 releases the main cellulose degradation-product (cellobiose), detected by using ionic chromatography, suggesting that MSMEG_6752 encodes a cellulase. Its overexpression in M. smegmatis prevents spontaneous biofilm formation. Moreover, the method reported here allowed detecting cellobiose when M. smegmatis cultures were exposed to a subinhibitory dose of rifampicin. Overall, this study highlights the role of the MSMEG_6752 in managing cellulose production induced during biofilm formation and antibiotic stress response. © The Author 2017. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  6. Glycerol metabolism induces Listeria monocytogenes biofilm formation at the air-liquid interface.

    Science.gov (United States)

    Crespo Tapia, Natalia; den Besten, Heidy M W; Abee, Tjakko

    2018-05-20

    Listeria monocytogenes is a food-borne pathogen that can grow as a biofilm on surfaces. Biofilm formation in food-processing environments is a big concern for food safety, as it can cause product contamination through the food-processing line. Although motile aerobic bacteria have been described to form biofilms at the air-liquid interface of cell cultures, to our knowledge, this type of biofilm has not been described in L. monocytogenes before. In this study we report L. monocytogenes biofilm formation at the air-liquid interface of aerobically grown cultures, and that this phenotype is specifically induced when the media is supplemented with glycerol as a carbon and energy source. Planktonic growth, metabolic activity assays and HPLC measurements of glycerol consumption over time showed that glycerol utilization in L. monocytogenes is restricted to growth under aerobic conditions. Gene expression analysis showed that genes encoding the glycerol transporter GlpF, the glycerol kinase GlpK and the glycerol 3-phosphate dehydrogenase GlpD were upregulated in the presence of oxygen, and downregulated in absence of oxygen. Additionally, motility assays revealed the induction of aerotaxis in the presence of glycerol. Our results demonstrate that the formation of biofilms at the air-liquid interface is dependent on glycerol-induced aerotaxis towards the surface of the culture, where L. monocytogenes has access to higher concentrations of oxygen, and is therefore able to utilize this compound as a carbon source. Copyright © 2018 Elsevier B.V. All rights reserved.

  7. Contribution of endogenous and exogenous damage to the total radiation-induced damage in the bacterial spore

    International Nuclear Information System (INIS)

    Jacobs, G.P.; Samuni, A.; Czapski, G.

    1980-01-01

    Radical scavengers such as polyethylene glycol 4000 and bovine albumin have been used to define the contribution of exogenous and endogenous damage to the total radiation-induced damage in aqueous buffered suspensions of Bacillus pumilus spores. The results indicate that this damage in the bacterial spore is predominantly endogenous

  8. Electric current induced prevention of biofilms on stainless steel

    NARCIS (Netherlands)

    Borden, Arnout Johannes van der

    2005-01-01

    As antibiotic therapy usually has little impact on biomaterials-associated infections, since the biofilm mode of growth offers protection, it is the aim of this thesis to investigate the prevention of infection on percutaneous pins and screws as used in the external fixator, with the aid of an

  9. Effects of exogenous carbon monoxide on radiation-induced bystander effect in zebrafish embryos in vivo

    Energy Technology Data Exchange (ETDEWEB)

    Choi, V.W.Y.; Wong, M.Y.P. [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong (Hong Kong); Cheng, S.H. [Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong (Hong Kong); State Key Laboratory in Marine Pollution, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong (Hong Kong); Yu, K.N., E-mail: appetery@cityu.edu.hk [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong (Hong Kong); State Key Laboratory in Marine Pollution, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong (Hong Kong)

    2012-07-15

    In the present work, the influence of a low concentration of exogenous carbon monoxide (CO) liberated from tricarbonylchloro(glycinato)ruthenium (II) (CORM-3) on the radiation induced bystander effect (RIBE) in vivo between embryos of the zebrafish was studied. RIBE was assessed through the number of apoptotic signals revealed on embryos at 25 h post fertilization (hpf). A significant attenuation of apoptosis on the bystander embryos induced by RIBE in a CO concentration dependent manner was observed. - Highlights: Black-Right-Pointing-Pointer RIBE between zebrafish embryos in vivo was assessed by the level of apoptosis. Black-Right-Pointing-Pointer CO from 10 and 20 {mu}M CORM-3 entirely suppressed the RIBE. Black-Right-Pointing-Pointer CO from 5 {mu}M CORM-3 significantly attenuated the level of apoptosis. Black-Right-Pointing-Pointer Inactive CORM-3 did not lead to suppression of RIBE. Black-Right-Pointing-Pointer Suppression of RIBE by CO depended on the concentration of CORM-3.

  10. Exogenous FABP4 induces endoplasmic reticulum stress in HepG2 liver cells.

    Science.gov (United States)

    Bosquet, Alba; Guaita-Esteruelas, Sandra; Saavedra, Paula; Rodríguez-Calvo, Ricardo; Heras, Mercedes; Girona, Josefa; Masana, Lluís

    2016-06-01

    Fatty acid binding protein 4 (FABP4) is an intracellular fatty acid (FA) carrier protein that is, in part, secreted into circulation. Circulating FABP4 levels are increased in obesity, diabetes and other insulin resistance (IR) diseases. FAs contribute to IR by promoting endoplasmic reticulum stress (ER stress) and altering the insulin signaling pathway. The effect of FABP4 on ER stress in the liver is not known. The aim of this study was to investigate whether exogenous FABP4 (eFABP4) is involved in the lipid-induced ER stress in the liver. HepG2 cells were cultured with eFABP4 (40 ng/ml) with or without linoleic acid (LA, 200 μM) for 18 h. The expression of ER stress-related markers was determined by Western blotting (ATF6, EIF2α, IRE1 and ubiquitin) and real-time PCR (ATF6, CHOP, EIF2α and IRE1). Apoptosis was studied by flow cytometry using Annexin V-FITC and propidium iodide staining. eFABP4 increased the ER stress markers ATF6 and IRE1 in HepG2 cells. This effect led to insulin resistance mediated by changes in AKT and JNK phosphorylation. Furthermore, eFABP4 significantly induced both apoptosis, as assessed by flow cytometry, and CHOP expression, without affecting necrosis and ubiquitination. The presence of LA increased the ER stress response induced by eFABP4. eFABP4, per se, induces ER stress and potentiates the effect of LA in HepG2 cells, suggesting that FABP4 could be a link between obesity-associated metabolic abnormalities and hepatic IR mechanisms. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  11. Vacquinol-1 inducible cell death in glioblastoma multiforme is counter regulated by TRPM7 activity induced by exogenous ATP.

    Science.gov (United States)

    Sander, Philip; Mostafa, Haouraa; Soboh, Ayman; Schneider, Julian M; Pala, Andrej; Baron, Ann-Kathrin; Moepps, Barbara; Wirtz, C Rainer; Georgieff, Michael; Schneider, Marion

    2017-05-23

    Glioblastomas (GBM) are the most malignant brain tumors in humans and have a very poor prognosis. New therapeutic options are urgently needed. A novel drug, Vacquinol-1 (Vac), a quinolone derivative, displays promising properties by inducing rapid cell death in GBM but not in non-transformed tissues. Features of this type of cell death are compatible with a process termed methuosis. Here we tested Vac on a highly malignant glioma cell line observed by long-term video microscopy. Human dental-pulp stem cells (DPSCs) served as controls. A major finding was that an exogenous ATP concentration of as little as 1 μM counter regulated the Vac-induced cell death. Studies using carvacrol, an inhibitor of transient receptor potential cation channel, subfamily M, member 7 (TRPM7), demonstrated that the ATP-inducible inhibitory effect is likely to be via TRPM7. Exogenous ATP is of relevance in GBM with large necrotic areas. Our results support the use of GBM cultures with different grades of malignancy to address their sensitivity to methuosis. The video-microscopy approach presented here allows decoding of signaling pathways as well as mechanisms of chemotherapeutic resistance by long-term observation. Before implementing Vac as a novel therapeutic drug in GBM, cells from each individual patient need to be assessed for their ATP sensitivity. In summary, the current investigation supports the concept of methuosis, described as non-apoptotic cell death and a promising approach for GBM treatment. Tissue-resident ATP/necrosis may interfere with this cell-death pathway but can be overcome by a natural compound, carvacrol that even penetrates the blood-brain barrier.

  12. Raffinose Induces Biofilm Formation by Streptococcus mutans in Low Concentrations of Sucrose by Increasing Production of Extracellular DNA and Fructan.

    Science.gov (United States)

    Nagasawa, Ryo; Sato, Tsutomu; Senpuku, Hidenobu

    2017-08-01

    Streptococcus mutans is the primary etiological agent of dental caries and causes tooth decay by forming a firmly attached biofilm on tooth surfaces. Biofilm formation is induced by the presence of sucrose, which is a substrate for the synthesis of extracellular polysaccharides but not in the presence of oligosaccharides. Nonetheless, in this study, we found that raffinose, which is an oligosaccharide with an intestinal regulatory function and antiallergic effect, induced biofilm formation by S. mutans in a mixed culture with sucrose, which was at concentrations less than those required to induce biofilm formation directly. We analyzed the possible mechanism behind the small requirement for sucrose for biofilm formation in the presence of raffinose. Our results suggested that sucrose contributed to an increase in bacterial cell surface hydrophobicity and biofilm formation. Next, we examined how the effects of raffinose interacted with the effects of sucrose for biofilm formation. We showed that the presence of raffinose induced fructan synthesis by fructosyltransferase and aggregated extracellular DNA (eDNA, which is probably genomic DNA released from dead cells) into the biofilm. eDNA seemed to be important for biofilm formation, because the degradation of DNA by DNase I resulted in a significant reduction in biofilm formation. When assessing the role of fructan in biofilm formation, we found that fructan enhanced eDNA-dependent cell aggregation. Therefore, our results show that raffinose and sucrose have cooperative effects and that this induction of biofilm formation depends on supportive elements that mainly consist of eDNA and fructan. IMPORTANCE The sucrose-dependent mechanism of biofilm formation in Streptococcus mutans has been studied extensively. Nonetheless, the effects of carbohydrates other than sucrose are inadequately understood. Our findings concerning raffinose advance the understanding of the mechanism underlying the joint effects of sucrose and

  13. Exogenous normal lymph reduces liver injury induced by lipopolysaccharides in rats

    Directory of Open Access Journals (Sweden)

    Z.G. Zhao

    2014-02-01

    Full Text Available The liver is one of the target organs damaged by septic shock, wherein the spread of endotoxins begins. This study aimed to investigate the effects of exogenous normal lymph (ENL on lipopolysaccharide (LPS-induced liver injury in rats. Male Wistar rats were randomly divided into sham, LPS, and LPS+ENL groups. LPS (15 mg/kg was administered intravenously via the left jugular vein to the LPS and LPS+ENL groups. At 15 min after the LPS injection, saline or ENL without cell components (5 mL/kg was administered to the LPS and LPS+ENL groups, respectively, at a rate of 0.5 mL/min. Hepatocellular injury indices and hepatic histomorphology, as well as levels of P-selectin, intercellular adhesion molecule 1 (ICAM-1, myeloperoxidase (MPO, and Na+-K+-ATPase, were assessed in hepatic tissues. Liver tissue damage occurred after LPS injection. All levels of alanine aminotransferase (ALT and aspartate aminotransferase (AST in plasma as well as the wet/dry weight ratio of hepatic tissue in plasma increased. Similarly, P-selectin, ICAM-1, and MPO levels in hepatic tissues were elevated, whereas Na+-K+-ATPase activity in hepatocytes decreased. ENL treatment lessened hepatic tissue damage and decreased levels of AST, ALT, ICAM-1, and MPO. Meanwhile, the treatment increased the activity of Na+-K+-ATPase. These results indicated that ENL could alleviate LPS-induced liver injury, thereby suggesting an alternative therapeutic strategy for the treatment of liver injury accompanied by severe infection or sepsis.

  14. Exogenous normal lymph reduces liver injury induced by lipopolysaccharides in rats

    International Nuclear Information System (INIS)

    Zhao, Z.G.; Zhang, L.L.; Niu, C.Y.; Zhang, J.

    2014-01-01

    The liver is one of the target organs damaged by septic shock, wherein the spread of endotoxins begins. This study aimed to investigate the effects of exogenous normal lymph (ENL) on lipopolysaccharide (LPS)-induced liver injury in rats. Male Wistar rats were randomly divided into sham, LPS, and LPS+ENL groups. LPS (15 mg/kg) was administered intravenously via the left jugular vein to the LPS and LPS+ENL groups. At 15 min after the LPS injection, saline or ENL without cell components (5 mL/kg) was administered to the LPS and LPS+ENL groups, respectively, at a rate of 0.5 mL/min. Hepatocellular injury indices and hepatic histomorphology, as well as levels of P-selectin, intercellular adhesion molecule 1 (ICAM-1), myeloperoxidase (MPO), and Na + -K + -ATPase, were assessed in hepatic tissues. Liver tissue damage occurred after LPS injection. All levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in plasma as well as the wet/dry weight ratio of hepatic tissue in plasma increased. Similarly, P-selectin, ICAM-1, and MPO levels in hepatic tissues were elevated, whereas Na + -K + -ATPase activity in hepatocytes decreased. ENL treatment lessened hepatic tissue damage and decreased levels of AST, ALT, ICAM-1, and MPO. Meanwhile, the treatment increased the activity of Na + -K + -ATPase. These results indicated that ENL could alleviate LPS-induced liver injury, thereby suggesting an alternative therapeutic strategy for the treatment of liver injury accompanied by severe infection or sepsis

  15. Exogenous normal lymph reduces liver injury induced by lipopolysaccharides in rats

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Z.G.; Zhang, L.L.; Niu, C.Y.; Zhang, J. [Institute of Microcirculation, Hebei North University, Zhangjiakou, China, Institute of Microcirculation, Hebei North University, Zhangjiakou, Hebei (China)

    2014-02-17

    The liver is one of the target organs damaged by septic shock, wherein the spread of endotoxins begins. This study aimed to investigate the effects of exogenous normal lymph (ENL) on lipopolysaccharide (LPS)-induced liver injury in rats. Male Wistar rats were randomly divided into sham, LPS, and LPS+ENL groups. LPS (15 mg/kg) was administered intravenously via the left jugular vein to the LPS and LPS+ENL groups. At 15 min after the LPS injection, saline or ENL without cell components (5 mL/kg) was administered to the LPS and LPS+ENL groups, respectively, at a rate of 0.5 mL/min. Hepatocellular injury indices and hepatic histomorphology, as well as levels of P-selectin, intercellular adhesion molecule 1 (ICAM-1), myeloperoxidase (MPO), and Na{sup +}-K{sup +}-ATPase, were assessed in hepatic tissues. Liver tissue damage occurred after LPS injection. All levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in plasma as well as the wet/dry weight ratio of hepatic tissue in plasma increased. Similarly, P-selectin, ICAM-1, and MPO levels in hepatic tissues were elevated, whereas Na{sup +}-K{sup +}-ATPase activity in hepatocytes decreased. ENL treatment lessened hepatic tissue damage and decreased levels of AST, ALT, ICAM-1, and MPO. Meanwhile, the treatment increased the activity of Na{sup +}-K{sup +}-ATPase. These results indicated that ENL could alleviate LPS-induced liver injury, thereby suggesting an alternative therapeutic strategy for the treatment of liver injury accompanied by severe infection or sepsis.

  16. Exogenous hydrogen peroxide reversibly inhibits root gravitropism and induces horizontal curvature of primary root during grass pea germination.

    Science.gov (United States)

    Jiang, Jinglong; Su, Miao; Wang, Liyan; Jiao, Chengjin; Sun, Zhengxi; Cheng, Wei; Li, Fengmin; Wang, Chongying

    2012-04-01

    During germination in distilled water (dH(2)O) on a horizontally positioned Petri dish, emerging primary roots of grass pea (Lathyrus sativus L.) grew perpendicular to the bottom of the Petri dish, due to gravitropism. However, when germinated in exogenous hydrogen peroxide (H(2)O(2)), the primary roots grew parallel to the bottom of the Petri dish and asymmetrically, forming a horizontal curvature. Time-course experiments showed that the effect was strongest when H(2)O(2) was applied prior to the emergence of the primary root. H(2)O(2) failed to induce root curvature when applied post-germination. Dosage studies revealed that the frequency of primary root curvature was significantly enhanced with increased H(2)O(2) concentrations. This curvature could be directly counteracted by dimethylthiourea (DMTU), a scavenger of H(2)O(2), but not by diphenylene iodonium (DPI) and pyridine, inhibitors of H(2)O(2) production. Exogenous H(2)O(2) treatment caused both an increase in the activities of H(2)O(2)-scavenging enzymes [including ascorbate peroxidase (APX: EC 1.11.1.11), catalase (CAT: EC 1.11.1.6) and peroxidase (POD: EC 1.11.1.7)] and a reduction in endogenous H(2)O(2) levels and root vitality. Although grass pea seeds absorbed exogenous H(2)O(2) during seed germination, DAB staining of paraffin sections revealed that exogenous H(2)O(2) only entered the root epidermis and not inner tissues. These data indicated that exogenously applied H(2)O(2) could lead to a reversible loss of the root gravitropic response and a horizontal curvature in primary roots during radicle emergence of the seedling. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

  17. Exogenous ROS-induced cell sheet transfer based on hematoporphyrin-polyketone film via a one-step process.

    Science.gov (United States)

    Koo, Min-Ah; Lee, Mi Hee; Kwon, Byeong-Ju; Seon, Gyeung Mi; Kim, Min Sung; Kim, Dohyun; Nam, Ki Chang; Park, Jong-Chul

    2018-04-01

    To date, most of invasive cell sheet harvesting methods have used culture surface property variations, such as wettability, pH, electricity, and magnetism, to induce cell detachment. These methods that rely on surface property changes are effective when cell detachment prior to application is necessary, but of limited use when used for cell sheet transfer to target regions. The study reports a new reactive oxygen species (ROS)-induced strategy based on hematoporphyrin-incorporated polyketone film (Hp-PK film) to transfer cell sheets directly to target areas without an intermediate harvesting process. After green LED (510 nm) irradiation, production of exogenous ROS from the Hp-PK films induces cell sheet detachment and transfer. The study suggests that ROS-induced cell detachment property of the Hp-PK film is closely related to conformational changes of extracellular matrix (ECM) proteins. Also, this strategy with the Hp-PK film can be applied by regulating production rate of exogenous ROS in various types of cells, including fibroblasts, mesenchymal stem cells and keratinocytes. In conclusion, ROS-induced method using the Hp-PK film can be used for one-step cell sheet transplantation and has potential in biomedical applications. Copyright © 2018 Elsevier Ltd. All rights reserved.

  18. Low Concentration of Exogenous Carbon Monoxide Modulates Radiation-Induced Bystander Effect in Mammalian Cell Cluster Model

    Directory of Open Access Journals (Sweden)

    Wenqing Wu

    2016-12-01

    Full Text Available During radiotherapy procedures, radiation-induced bystander effect (RIBE can potentially lead to genetic hazards to normal tissues surrounding the targeted regions. Previous studies showed that RIBE intensities in cell cluster models were much higher than those in monolayer cultured cell models. On the other hand, low-concentration carbon monoxide (CO was previously shown to exert biological functions via binding to the heme domain of proteins and then modulating various signaling pathways. In relation, our previous studies showed that exogenous CO generated by the CO releasing molecule, tricarbonyldichlororuthenium (CORM-2, at a relatively low concentration (20 µM, effectively attenuated the formation of RIBE-induced DNA double-strand breaks (DSB and micronucleus (MN. In the present work, we further investigated the capability of a low concentration of exogenous CO (CORM-2 of attenuating or inhibiting RIBE in a mixed-cell cluster model. Our results showed that CO (CORM-2 with a low concentration of 30 µM could effectively suppress RIBE-induced DSB (p53 binding protein 1, p53BP1, MN formation and cell proliferation in bystander cells but not irradiated cells via modulating the inducible nitric oxide synthase (iNOS andcyclooxygenase-2 (COX-2. The results can help mitigate RIBE-induced hazards during radiotherapy procedures.

  19. Removal and sterilization of biofilms and planktonic bacteria by microwave-induced argon plasma at atmospheric pressure

    International Nuclear Information System (INIS)

    Lee, Mi Hee; Park, Bong Joo; Jin, Soo Chang; Kim, Dohyun; Kim, Jungsung; Park, Jong-Chul; Han, Inho; Hyun, Soon O; Chung, Kie-Hyung

    2009-01-01

    Microbial biofilms are a functional matrix of microbial cells, enveloped in polysaccharides, enzymes and virulence factors secreted by them that can develop on indwelling medical devices and biomaterials. Plasma sterilization has been widely studied in recent years for biological applications. In this study, we evaluated the possibility of removal and anti-recovery of biofilms by microwave-induced argon plasma at atmospheric pressure. We observed that all bacterial biofilms formatted by Gram-negative and Gram-positive bacteria are removed in less than 20 s, and the growth inhibitions of planktonic bacteria within biofilms are also confirmed by plasma exposure for 5 s. These results suggest that our plasma system can be applied to medical and biological fields where the removal of biofilms and their debris is required.

  20. Image-based Modeling of Biofilm-induced Calcium Carbonate Precipitation

    Science.gov (United States)

    Connolly, J. M.; Rothman, A.; Jackson, B.; Klapper, I.; Cunningham, A. B.; Gerlach, R.

    2013-12-01

    Pore scale biological processes in the subsurface environment are important to understand in relation to many engineering applications including environmental contaminant remediation, geologic carbon sequestration, and petroleum production. Specifically, biofilm induced calcium carbonate precipitation has been identified as an attractive option to reduce permeability in a lasting way in the subsurface. This technology may be able to replace typical cement-based grouting in some circumstances; however, pore-scale processes must be better understood for it to be applied in a controlled manor. The work presented will focus on efforts to observe biofilm growth and ureolysis-induced mineral precipitation in micro-fabricated flow cells combined with finite element modelling as a tool to predict local chemical gradients of interest (see figure). We have been able to observe this phenomenon over time using a novel model organism that is able to hydrolyse urea and express a fluorescent protein allowing for non-invasive observation over time with confocal microscopy. The results of this study show the likely existence of a wide range of local saturation indices even in a small (1 cm length scale) experimental system. Interestingly, the locations of high predicted index do not correspond to the locations of higher precipitation density, highlighting the need for further understanding. Figure 1 - A micro-fabricated flow cell containing biofilm-induced calcium carbonate precipitation. (A) Experimental results: Active biofilm is in green and dark circles are calcium carbonate crystals. Note the channeling behavior in the top of the image, leaving a large hydraulically inactive area in the biofilm mass. (B) Finite element model: The prediction of relative saturation of calcium carbonate (as calcite). Fluid enters the system at a low saturation state (blue) but areas of high supersaturation (red) are predicted within the hydraulically inactive area in the biofilm. If only effluent

  1. Exogenous deposits

    International Nuclear Information System (INIS)

    Khasanov, A.Kh.

    1988-01-01

    Exogenous deposits forming as a result of complex exogenous processes, passed under the influence of outside forces on the Earth surface. To them relate physical and chemical weathering, decomposition and decay of mineral masses, redistribution and transportation of material, forming and deposit of new minerals and ores steady on the earth surface conditions

  2. Anti-ghrelin Spiegelmer inhibits exogenous ghrelin-induced increases in food intake, hoarding, and neural activation, but not food deprivation-induced increases

    Science.gov (United States)

    Teubner, Brett J. W.

    2013-01-01

    Circulating concentrations of the stomach-derived “hunger-peptide” ghrelin increase in direct proportion to the time since the last meal. Exogenous ghrelin also increases food intake in rodents and humans, suggesting ghrelin may increase post-fast ingestive behaviors. Food intake after food deprivation is increased by laboratory rats and mice, but not by humans (despite dogma to the contrary) or by Siberian hamsters; instead, humans and Siberian hamsters increase food hoarding, suggesting the latter as a model of fasting-induced changes in human ingestive behavior. Exogenous ghrelin markedly increases food hoarding by ad libitum-fed Siberian hamsters similarly to that after food deprivation, indicating sufficiency. Here, we tested the necessity of ghrelin to increase food foraging, food hoarding, and food intake, and neural activation [c-Fos immunoreactivity (c-Fos-ir)] using anti-ghrelin Spiegelmer NOX-B11–2 (SPM), an l-oligonucleotide that specifically binds active ghrelin, inhibiting peptide-receptor interaction. SPM blocked exogenous ghrelin-induced increases in food hoarding the first 2 days after injection, and foraging and food intake at 1–2 h and 2–4 h, respectively, and inhibited hypothalamic c-Fos-ir. SPM given every 24 h across 48-h food deprivation inconsistently inhibited food hoarding after refeeding and c-Fos-ir, similarly to inabilities to do so in laboratory rats and mice. These results suggest that ghrelin may not be necessary for food deprivation-induced foraging and hoarding and neural activation. A possible compensatory response, however, may underlie these findings because SPM treatment led to marked increases in circulating ghrelin concentrations. Collectively, these results show that SPM can block exogenous ghrelin-induced ingestive behaviors, but the necessity of ghrelin for food deprivation-induced ingestive behaviors remains unclear. PMID:23804279

  3. Endogenous and exogenously-induced immunomodulation of tumour-host responsiveness

    Directory of Open Access Journals (Sweden)

    Richard J. Ablin

    1987-01-01

    Full Text Available In spite of the availability of multiple effector mechanisms of the immune system to combat tumour growth and metastases, their impairment frequently accompanies the appearance of cancer. Factors contributing to this impairment may be related to properties of the host and/or the tumour itself and may be with respect to their origin -endogenous or exogenour. Based on the unique biological behavior of prostate cancer (PCa, and its apparent escape from immune surveillance in the presence of tumour immuno genicity, continuing investigation of endogenous and exogenous factors thought to be relevant to its pathogenesis have been made. For this purpose further studies of the suggested role of human seminal plasma (SePl and the synthetic oestrogen, diethylstiboestrol (DES, as representative endogenous and exogenous immunomodulatory factors (IMF of tumour-host responsiveness, together with evaluation of human prostatic tissue extracts and leuprolide (the luteinizing-hormone-releasing-hormone proposed as an alternate to DES therapy have been made by evaluating their effect on the lytic activity of natural killer (NK cells. SePl and prostate extracts significantly suppressed NK cell lysis. Physicochemical studies suggest SePl and prostate IMF to be associated with high and low molecular weight macromolecules; and implicate the participation of transglutaminase and prostaglandins. Comparative study of therapeutic levels of DES vs. leuprolide on NK cell lysis demonstrated significant suppression by DES vs. a negligible effect of leuprolide. Metastases are highly prevalent in PCa, and contribute significantly to its morbidity and mortality. Further knowledge of the range of effects of endogenous and exogenous IMF on effector mechanisms of tumour-host responsiveness, to include suppression of NK cells, and elucidation of their nature, may contribute toward our understanding of the unique biological behavior of tumours of the prostate, in addition to

  4. Exogenous retinoic acid induces digit reduction in opossums (Monodelphis domestica) by disrupting cell death and proliferation, and apical ectodermal ridge and zone of polarizing activity function.

    Science.gov (United States)

    Molineaux, Anna C; Maier, Jennifer A; Schecker, Teresa; Sears, Karen E

    2015-03-01

    Retinoic acid (RA) is a vitamin A derivative. Exposure to exogenous RA generates congenital limb malformations (CLMs) in species from frogs to humans. These CLMs include but are not limited to oligodactyly and long-bone hypoplasia. The processes by which exogenous RA induces CLMs in mammals have been best studied in mouse, but as of yet remain unresolved. We investigated the impact of exogenous RA on the cellular and molecular development of the limbs of a nonrodent model mammal, the opossum Monodelphis domestica. Opossums exposed to exogenous retinoic acid display CLMs including oligodactly, and results are consistent with opossum development being more susceptible to RA-induced disruptions than mouse development. Exposure of developing opossums to exogenous RA leads to an increase in cell death in the limb mesenchyme that is most pronounced in the zone of polarizing activity, and a reduction in cell proliferation throughout the limb mesenchyme. Exogenous RA also disrupts the expression of Shh in the zone of polarizing activity, and Fgf8 in the apical ectodermal ridge, and other genes with roles in the regulation of limb development and cell death. Results are consistent with RA inducing CLMs in opossum limbs by disrupting the functions of the apical ectodermal ridge and zone of polarizing activity, and driving an increase in cell death and reduction of cell proliferation in the mesenchyme of the developing limb. © 2015 Wiley Periodicals, Inc.

  5. A Randomized Clinical Trial of Schinus terebinthifolius Mouthwash to Treat Biofilm-Induced Gingivitis

    Science.gov (United States)

    Freires, Irlan de Almeida; Alves, Livia Araújo; Ferreira, Gabriela Lacet Silva; Jovito, Vanessa de Carvalho; de Castro, Ricardo Dias; Cavalcanti, Alessandro Leite

    2013-01-01

    Objectives. This study aimed to investigate the efficacy of a Schinus terebinthifolius (ST) mouthwash in reducing gingival inflammation levels (GI) and biofilm accumulation (BA) in children with gingivitis. Methods. This was a randomized, controlled, triple blind, and phase II clinical trial, with children aged 9–13 years (n = 27) presenting with biofilm-induced gingivitis. The sample was randomized into experimental (0.3125% ST, n = 14) and control (0.12% chlorhexidine/CHX, n = 13) groups. Products were masked as regards color, flavor and aroma. Intervention protocol consisted in supervised rinsing of 10 mL/day for 01 minute for 10 days. Gingival bleeding and simplified oral hygiene indexes were used to assess the efficacy variables, measured at baseline and after intervention by calibrated examiners. Data were statistically treated with paired t-test, unpaired t-test, and Wilcoxon and Mann-Whitney tests (α = .05). Results. It was found that both ST and CHX were able to significantly reduce GI levels after 10 days (P 0.05). CHX was the only product able to significantly reduce BA after 10 days when compared to baseline (P < 0.05). Conclusion. ST mouthwash showed significant anti-inflammatory activity (equivalent to CHX), but it was not able to reduce biofilm accumulation. PMID:23843886

  6. Exogenous H2S facilitating ubiquitin aggregates clearance via autophagy attenuates type 2 diabetes-induced cardiomyopathy

    Science.gov (United States)

    Wu, Jichao; Tian, Zhiliang; Sun, Yu; Lu, Cuicui; Liu, Ning; Gao, Zhaopeng; Zhang, Linxue; Dong, Shiyun; Yang, Fan; Zhong, Xin; Xu, Changqing; Lu, Fanghao; Zhang, Weihua

    2017-01-01

    Diabetic cardiomyopathy (DCM) is a serious complication of diabetes. Hydrogen sulphide (H2S), a newly found gaseous signalling molecule, has an important role in many regulatory functions. The purpose of this study is to investigate the effects of exogenous H2S on autophagy and its possible mechanism in DCM induced by type II diabetes (T2DCM). In this study, we found that sodium hydrosulphide (NaHS) attenuated the augment in left ventricular (LV) mass and increased LV volume, decreased reactive oxygen species (ROS) production and ameliorated H2S production in the hearts of db/db mice. NaHS facilitated autophagosome content degradation, reduced the expression of P62 (a known substrate of autophagy) and increased the expression of microtubule-associated protein 1 light chain 3 II. It also increased the expression of autophagy-related protein 7 (ATG7) and Beclin1 in db/db mouse hearts. NaHS increased the expression of Kelch-like ECH-associated protein 1 (Keap-1) and reduced the ubiquitylation level in the hearts of db/db mice. 1,4-Dithiothreitol, an inhibitor of disulphide bonds, increased the ubiquitylation level of Keap-1, suppressed the expression of Keap-1 and abolished the effects of NaHS on ubiquitin aggregate clearance and ROS production in H9C2 cells treated with high glucose and palmitate. Overall, we concluded that exogenous H2S promoted ubiquitin aggregate clearance via autophagy, which might exert its antioxidative effect in db/db mouse myocardia. Moreover, exogenous H2S increased Keap-1 expression by suppressing its ubiquitylation, which might have an important role in ubiquitin aggregate clearance via autophagy. Our findings provide new insight into the mechanisms responsible for the antioxidative effects of H2S in the context of T2DCM. PMID:28796243

  7. Endogenous versus exogenous lithium clearance for evaluation of dopamine-induced changes in renal tubular function

    DEFF Research Database (Denmark)

    Olsen, Niels Vidiendal; Fogh-Andersen, N; Strandgaard, S

    1996-01-01

    1. The present randomized, double-blind cross-over study compared endogenous and exogenous lithium clearance (CLi) for estimation of the effect of dopamine on tubular sodium reabsorption. Twelve normal, salt-repleted male subjects were investigated on three different occasions with either placebo...... or 450 mg or 600 mg of lithium given in random order at 22.00 hours. After an overnight fast, renal clearance studies were performed during a 1 h baseline period and subsequently during the second hour of an infusion of 3 micrograms min-1 kg-1 of dopamine. 2. Baseline values of endogenous CLi.......3-31.0)% (P lithium increased the baseline sodium clearance (CNa), but glomerular filtration rate and urine flow rate remained unchanged. 3. Dopamine increased CNa to similar values on the three study days. CLi increased to 40.9 (35.5-46.5) ml/min (endogenous lithium, P

  8. Antibiotic treatment of biofilm infections

    DEFF Research Database (Denmark)

    Ciofu, Oana; Rojo-Molinero, Estrella; Macià, María D.

    2017-01-01

    Bacterial biofilms are associated with a wide range of infections, from those related to exogenous devices, such as catheters or prosthetic joints, to chronic tissue infections such as those occurring in the lungs of cystic fibrosis patients. Biofilms are recalcitrant to antibiotic treatment due ...

  9. Measurement of Endogenous versus Exogenous Formaldehyde-Induced DNA-Protein Crosslinks in Animal Tissues by Stable Isotope Labeling and Ultrasensitive Mass Spectrometry.

    Science.gov (United States)

    Lai, Yongquan; Yu, Rui; Hartwell, Hadley J; Moeller, Benjamin C; Bodnar, Wanda M; Swenberg, James A

    2016-05-01

    DNA-protein crosslinks (DPC) arise from a wide range of endogenous and exogenous chemicals, such as chemotherapeutic drugs and formaldehyde. Importantly, recent identification of aldehydes as endogenous genotoxins in Fanconi anemia has provided new insight into disease causation. Because of their bulky nature, DPCs pose severe threats to genome stability, but previous methods to measure formaldehyde-induced DPCs were incapable of discriminating between endogenous and exogenous sources of chemical. In this study, we developed methods that provide accurate and distinct measurements of both exogenous and endogenous DPCs in a structurally specific manner. We exposed experimental animals to stable isotope-labeled formaldehyde ([(13)CD2]-formaldehyde) by inhalation and performed ultrasensitive mass spectrometry to measure endogenous (unlabeled) and exogenous ((13)CD2-labeled) DPCs. We found that exogenous DPCs readily accumulated in nasal respiratory tissues but were absent in tissues distant to the site of contact. This observation, together with the finding that endogenous formaldehyde-induced DPCs were present in all tissues examined, suggests that endogenous DPCs may be responsible for increased risks of bone marrow toxicity and leukemia. Furthermore, the slow rate of DPC repair provided evidence for the persistence of DPCs. In conclusion, our method for measuring endogenous and exogenous DPCs presents a new perspective for the potential health risks inflicted by endogenous formaldehyde and may inform improved disease prevention and treatment strategies. Cancer Res; 76(9); 2652-61. ©2016 AACR. ©2016 American Association for Cancer Research.

  10. Exogenous Nitric Oxide Suppresses in Vivo X-ray-Induced Targeted and Non-Targeted Effects in Zebrafish Embryos

    Directory of Open Access Journals (Sweden)

    E.Y. Kong

    2016-08-01

    Full Text Available The present paper studied the X-ray-induced targeted effect in irradiated zebrafish embryos (Danio rerio, as well as a non-targeted effect in bystander naïve embryos partnered with irradiated embryos, and examined the influence of exogenous nitric oxide (NO on these targeted and non-targeted effects. The exogenous NO was generated using an NO donor, S-nitroso-N-acetylpenicillamine (SNAP. The targeted and non-targeted effects, as well as the toxicity of the SNAP, were assessed using the number of apoptotic events in the zebrafish embryos at 24 h post fertilization (hpf revealed through acridine orange (AO staining. SNAP with concentrations of 20 and 100 µM were first confirmed to have no significant toxicity on zebrafish embryos. The targeted effect was mitigated in zebrafish embryos if they were pretreated with 100 µM SNAP prior to irradiation with an X-ray dose of 75 mGy but was not alleviated in zebrafish embryos if they were pretreated with 20 µM SNAP. On the other hand, the non-targeted effect was eliminated in the bystander naïve zebrafish embryos if they were pretreated with 20 or 100 µM SNAP prior to partnering with zebrafish embryos having been subjected to irradiation with an X-ray dose of 75 mGy. These findings revealed the importance of NO in the protection against damages induced by ionizing radiations or by radiation-induced bystander signals, and could have important impacts on development of advanced cancer treatment strategies.

  11. Induced resistance to Helicoverpa armigera through exogenous application of jasmonic acid and salicylic acid in groundnut, Arachis hypogaea.

    Science.gov (United States)

    War, Abdul Rashid; Paulraj, Michael Gabriel; Ignacimuthu, Savarimuthu; Sharma, Hari Chand

    2015-01-01

    Induced resistance to Helicoverpa armigera through exogenous application of jasmonic acid (JA) and salicylic acid (SA) was studied in groundnut genotypes (ICGV 86699, ICGV 86031, ICG 2271 and ICG 1697) with different levels of resistance to insects and the susceptible check JL 24 under greenhouse conditions. Activities of oxidative enzymes and the amounts of secondary metabolites and proteins were quantified at 6 days after JA and SA application/insect infestation. Data were also recorded on plant damage and H. armigera larval weights and survival. Higher levels of enzymatic activities and amounts of secondary metabolites were observed in the insect-resistant genotypes pretreated with JA and then infested with H. armigera than in JL 24. The insect-resistant genotypes suffered lower insect damage and resulted in poor survival and lower weights of H. armigera larvae than JL 24. In some cases, JA and SA showed similar effects. JA and SA induced the activity of antioxidative enzymes in groundnut plants against H. armigera, and reduced its growth and development. However, induced response to application of JA was greater than to SA, and resulted in reduced plant damage, and larval weights and survival, suggesting that induced resistance can be used as a component of pest management in groundnut. © 2014 Society of Chemical Industry.

  12. Exogenous Application of GABA Improves PEG-Induced Drought Tolerance Positively Associated with GABA-Shunt, Polyamines, and Proline Metabolism in White Clover.

    Science.gov (United States)

    Yong, Bin; Xie, Huan; Li, Zhou; Li, Ya-Ping; Zhang, Yan; Nie, Gang; Zhang, Xin-Quan; Ma, Xiao; Huang, Lin-Kai; Yan, Yan-Hong; Peng, Yan

    2017-01-01

    In order to investigate the physiological effects of exogenous γ-aminobutyric acid (GABA) on drought tolerance in white clover (Trifolium repens), GABA shunt, polyamines (PAs), and proline (Pro) metabolism were examined after plants pretreated with or without GABA (8 mM) and then exposed to water or 15% PEG-induced drought stress in growth chamber. In this study, exogenous application of GABA effectively alleviated drought-induced damage in leaves, as reflected by significantly higher relative water content, lower electrolyte leakage, lipid peroxidation, and leaf wilt. Exogenous GABA further promoted drought-induced increases in GABA transaminase and alpha ketone glutarate dehydrogenase activities, but inhibited glutamate decarboxylase activity under both control and drought conditions, resulting in an increase in endogenous glutamate (Glu) and GABA content. Besides, exogenous GABA could well accelerated PAs synthesis and suppressed PAs catabolism, which lead to the extremely enhanced different types of PAs content (free Put and Spd, insoluble bound Spd and Spm, soluble conjugated Spd and Spm, and total Put, Spd and Spm) under drought stress. In addition, exogenous GABA application further activated drought-induced Δ 1 -pyrroline-5-carboxylate synthetase and proline dehydrogenase activities, but suppressed drought-facilitated ornithine -δ-amino transferase activities, leading to a higher Pro accumulation and metabolism in GABA-pretreated plants in the middle and last period of drought. The results suggested that increased endogenous GABA by exogenous GABA treatment could improve drought tolerance of white clover associated with a positive regulation in the GABA-shunt, PAs and Pro metabolism.

  13. A preclinical model for noninvasive imaging of hypoxia-induced gene expression; comparison with an exogenous marker of tumor hypoxia

    Energy Technology Data Exchange (ETDEWEB)

    Wen Bixiu; Burgman, Paul; Zanzonico, Pat; O' Donoghue, Joseph; Li, Gloria C.; Ling, C. Clifton [Memorial Sloan-Kettering Cancer Center, Department of Medical Physics, New York (United States); Cai Shangde; Finn, Ron [Memorial Sloan-Kettering Cancer Center, Department of Radiology, New York (United States); Serganova, Inna [Memorial Sloan-Kettering Cancer Center, Department of Neurology, New York (United States); Blasberg, Ronald; Gelovani, Juri [Memorial Sloan-Kettering Cancer Center, Department of Radiology, New York (United States); Memorial Sloan-Kettering Cancer Center, Department of Neurology, New York (United States)

    2004-11-01

    Hypoxia is associated with tumor aggressiveness and is an important cause of resistance to radiation therapy and chemotherapy. Assays of tumor hypoxia could provide selection tools for hypoxia-modifying treatments. The purpose of this study was to develop and characterize a rodent tumor model with a reporter gene construct that would be transactivated by the hypoxia-inducible molecular switch, i.e., the upregulation of HIF-1. The reporter gene construct is the herpes simplex virus 1-thymidine kinase (HSV1-tk) fused with the enhanced green fluorescent protein (eGFP) under the regulation of an artificial hypoxia-responsive enhancer/promoter. In this model, tumor hypoxia would up-regulate HIF-1, and through the hypoxia-responsive promoter transactivate the HSV1-tkeGFPfusion gene. The expression of this reporter gene can be assessed with the {sup 124}I-labeled reporter substrate 2'-fluoro-2'-deoxy-1-{beta}-d-arabinofuranosyl-5-iodouracil ({sup 124}I-FIAU), which is phosphorylated by the HSV1-tk enzyme and trapped in the hypoxic cells. Animal positron emission tomography (microPET) and phosphor plate imaging (PPI) were used in this study to visualize the trapped {sup 124}I-FIAU, providing a distribution of the hypoxia-induced molecular events. The distribution of {sup 124}I-FIAU was also compared with that of an exogenous hypoxic cell marker, {sup 18}F-fluoromisonidazole (FMISO). Our results showed that {sup 124}I-FIAU microPET imaging of the hypoxia-induced reporter gene expression is feasible, and that the intratumoral distributions of {sup 124}I-FIAU and {sup 18}F-FMISO are similar. In tumor sections, detailed radioactivity distributions were obtained with PPI which also showed similarity between {sup 124}I-FIAU and {sup 18}F-FMISO. This reporter system is sufficiently sensitive to detect hypoxia-induced transcriptional activation by noninvasive imaging and might provide a valuable tool in studying tumor hypoxia and in validating existing and future

  14. Role of exogenous folic acid in alleviation of morphological and anatomical inhibition on salinity-induced stress in barley

    Directory of Open Access Journals (Sweden)

    Semra Kilic

    2016-12-01

    Full Text Available Soil salinity is a serious threat to agricultural ecological environment and agriculture sustainability. Ever increasing salinity negatively affects processes such as plant growth and development, ultimately causing diminished economic yield and quality of production, and it might cause a worldwide famine in the future. Thus, helping plants adapt to saline soils and increasing their yield and quality is a must. Our study focused on the enhancing role of exogenously applied folic acid (FA in mitigation of toxicity caused by salt (NaCl. Barley seeds were pre-treated with 50 µM FA for 24 h and then exposed to salt. Morphological and anatomical changes in seed germination and seedling growth stages were compared between different treatments of salt in laboratory conditions. Adverse effects of salt in both germination and seedling growth stages depended on the concentration of salt treatment (0.0, 0.25, 0.275, 0.30, 0.325 and 0.35 M. It was shown that the application of FA effectively alleviated the salt-induced inhibition, and reduced the negative effects of salt on germination (germination index and vigour index, seedling growth (radicle and coleoptile lengths, fresh weight and leaf (stomata and epidermis number, stomatal index, stomata sizes of adaxial and abaxial surfaces parameters. Moreover, FA elevated all examined parameters of barley also under non-stress conditions. Especially, germination and vigour indices were significantly higher than the control. Our results suggest that exogenous FA is involved in the resistance of barley to salt-stress.

  15. ResDE Two-Component Regulatory System Mediates Oxygen Limitation-Induced Biofilm Formation by Bacillus amyloliquefaciens SQR9.

    Science.gov (United States)

    Zhou, Xuan; Zhang, Nan; Xia, Liming; Li, Qing; Shao, Jiahui; Shen, Qirong; Zhang, Ruifu

    2018-04-15

    Efficient biofilm formation and root colonization capabilities facilitate the ability of beneficial plant rhizobacteria to promote plant growth and antagonize soilborne pathogens. Biofilm formation by plant-beneficial Bacillus strains is triggered by environmental cues, including oxygen deficiency, but the pathways that sense these environmental signals and regulate biofilm formation have not been thoroughly elucidated. In this study, we showed that the ResDE two-component regulatory system in the plant growth-promoting rhizobacterium Bacillus amyloliquefaciens strain SQR9 senses the oxygen deficiency signal and regulates biofilm formation. ResE is activated by sensing the oxygen limitation-induced reduction of the NAD + /NADH pool through its PAS domain, stimulating its kinase activity, and resulting in the transfer of a phosphoryl group to ResD. The phosphorylated ResD directly binds to the promoter regions of the qoxABCD and ctaCDEF operons to improve the biosynthesis of terminal oxidases, which can interact with KinB to activate biofilm formation. These results not only revealed the novel regulatory function of the ResDE two-component system but also contributed to the understanding of the complicated regulatory network governing Bacillus biofilm formation. This research may help to enhance the root colonization and the plant-beneficial efficiency of SQR9 and other Bacillus rhizobacteria used in agriculture. IMPORTANCE Bacillus spp. are widely used as bioinoculants for plant growth promotion and disease suppression. The exertion of their plant-beneficial functions is largely dependent on their root colonization, which is closely related to their biofilm formation capabilities. On the other hand, Bacillus is the model bacterium for biofilm study, and the process and molecular network of biofilm formation are well characterized (B. Mielich-Süss and D. Lopez, Environ Microbiol 17:555-565, 2015, https://doi.org/10.1111/1462-2920.12527; L. S. Cairns, L. Hobley, and

  16. Use of the MicroRespTM method to assess pollution-induced community tolerance to metals for lotic biofilms

    International Nuclear Information System (INIS)

    Tlili, Ahmed; Marechal, Marjorie; Montuelle, Bernard; Volat, Bernadette; Dorigo, Ursula; Berard, Annette

    2011-01-01

    Understanding the ecological status of aquatic ecosystems and the impact of anthropogenic contamination requires correlating exposure to toxicants with impact on biological communities. Several tools exist for assessing the ecotoxicity of substances, but there is still a need for new tools that are ecologically relevant and easy to use. We have developed a protocol based on the substrate-induced respiration of a river biofilm community, using the MicroResp TM technique, in a pollution-induced community tolerance approach. The results show that MicroResp TM can be used in bioassays to assess the toxicity toward biofilm communities of a wide range of metals (Cu, Zn, Cd, Ag, Ni, Fe, Co, Al and As). Moreover, a community-level physiological profile based on the mineralization of different carbon substrates was established. Finally, the utility of MicroResp TM was confirmed in an in-situ study showing gradient of tolerance to copper correlated to a contamination gradient of this metal in a small river. - A modified MicroResp TM technique as a tool for measuring induced tolerance to heavy metals of a microbial biofilm community. - Research highlights: → MicroResp TM allows to plot dose-response curves with various tested metals. → Induced-tolerance to copper of heterotrophic biofilm community was successfully measured. → No co-tolerance detected between copper, silver and cadmium by using MicroResp TM . → MicroResp TM allows assessment of change in catabolic diversity in microbial community.

  17. Dynamic Dispersal of Surface Layer Biofilm Induced by Nanosized TiO2 Based on Surface Plasmon Resonance and Waveguide.

    Science.gov (United States)

    Zhang, Peng; Guo, Jin-Song; Yan, Peng; Chen, You-Peng; Wang, Wei; Dai, You-Zhi; Fang, Fang; Wang, Gui-Xue; Shen, Yu

    2018-05-01

    Pollutant degradation is present mainly in the surface layer of biofilms, and the surface layer is the most vulnerable to impairment by toxic pollutants. In this work, the effects of nanosized TiO 2 (n-TiO 2 ) on the average thicknesses of Bacillus subtilis biofilm and on bacterial attachment on different surfaces were investigated. The binding mechanism of n-TiO 2 to the cell surface was also probed. The results revealed that n-TiO 2 caused biofilm dispersal and the thicknesses decreased by 2.0 to 2.6 μm after several hours of exposure. The attachment abilities of bacteria with extracellular polymeric substances (EPS) on hydrophilic surfaces were significantly reduced by 31% and 81% under 10 and 100 mg/liter of n-TiO 2 , respectively, whereas those of bacteria without EPS were significantly reduced by 43% and 87%, respectively. The attachment abilities of bacteria with and without EPS on hydrophobic surfaces were significantly reduced by 50% and 56%, respectively, under 100 mg/liter of n-TiO 2 The results demonstrated that biofilm dispersal can be attributed to the changes in the cell surface structure and the reduction of microbial attachment ability. IMPORTANCE Nanoparticles can penetrate into the outer layer of biofilm in a relatively short period and can bind onto EPS and bacterial surfaces. The current work probed the effects of nanosized TiO 2 (n-TiO 2 ) on biofilm thickness, bacterial migration, and surface properties of the cell in the early stage using the surface plasmon resonance waveguide mode. The results demonstrated that n-TiO 2 decreased the adhesive ability of both cell and EPS and induced bacterial migration and biofilm detachment in several hours. The decreased adhesive ability of microbes and EPS worked against microbial aggregation, reducing the effluent quality in the biological wastewater treatment process. Copyright © 2018 American Society for Microbiology.

  18. Exogenous and Endogeneous Disialosyl Ganglioside GD1b Induces Apoptosis of MCF-7 Human Breast Cancer Cells

    Directory of Open Access Journals (Sweden)

    Sun-Hyung Ha

    2016-04-01

    Full Text Available Gangliosides have been known to play a role in the regulation of apoptosis in cancer cells. This study has employed disialyl-ganglioside GD1b to apoptosis in human breast cancer MCF-7 cells using exogenous treatment of the cells with GD1b and endogenous expression of GD1b in MCF-7 cells. First, apoptosis in MCF-7 cells was observed after treatment of GD1b. Treatment of MCF-7 cells with GD1b reduced cell growth rates in a dose and time dependent manner during GD1b treatment, as determined by XTT assay. Among the various gangliosides, GD1b specifically induced apoptosis of the MCF-7 cells. Flow cytometry and immunofluorescence assays showed that GD1b specifically induces apoptosis in the MCF-7 cells with Annexin V binding for apoptotic actions in early stage and propidium iodide (PI staining the nucleus of the MCF-7 cells. Treatment of MCF-7 cells with GD1b activated apoptotic molecules such as processed forms of caspase-8, -7 and PARP (Poly(ADP-ribose polymerase, without any change in the expression of mitochondria-mediated apoptosis molecules such as Bax and Bcl-2. Second, to investigate the effect of endogenously produced GD1b on the regulation of cell function, UDP-gal: β1,3-galactosyltransferase-2 (GD1b synthase, Gal-T2 gene has been transfected into the MCF-7 cells. Using the GD1b synthase-transfectants, apoptosis-related signal proteins linked to phenotype changes were examined. Similar to the exogenous GD1b treatment, the cell growth of the GD1b synthase gene-transfectants was significantly suppressed compared with the vector-transfectant cell lines and transfection activated the apoptotic molecules such as processed forms of caspase-8, -7 and PARP, but not the levels of expression of Bax and Bcl-2. GD1b-induced apoptosis was blocked by caspase inhibitor, Z-VAD. Therefore, taken together, it was concluded that GD1b could play an important role in the regulation of breast cancer apoptosis.

  19. Kinetics of apoptotic markers in exogeneously induced apoptosis of EL4 cells.

    Science.gov (United States)

    Jessel, Robert; Haertel, Steffen; Socaciu, Carmen; Tykhonova, Svetlana; Diehl, Horst A

    2002-01-01

    We investigated the time-dependence of apoptotic events in EL4 cells by monitoring plasma membrane changes in correlation to DNA fragmentation and cell shrinkage. We applied three apoptosis inducers (staurosporine, tubericidine and X-rays) and we looked at various markers to follow the early-to-late apoptotic events: phospholipid translocation (identified through annexin V-fluorescein assay and propidium iodide), lipid package (via merocyanine assay), membrane fluidity and anisotropy (via fluorescent measurements), DNA fragmentation by the fluorescence-labeling test and cell size measurements. The different apoptotic inducers caused different reactions of the cells: staurosporine induced apoptosis most rapidly in a high number of cells, tubercidine triggered apoptosis only in the S phase cells, while X-rays caused a G2/M arrest and subsequently apoptosis. Loss of lipid asymmetry is promptly detectable after one hour of incubation time. The phosphatidylserine translocation, decrease of lipid package and anisotropy, and the increase of membrane fluidity appeared to be based on the same process of lipid asymmetry loss. Therefore, the DNA fragmentation and the cell shrinkage appear to be parallel and independent processes running on different time scales but which are kinetically inter-related. The results indicate different signal steps to apoptosis dependent on inducer characteristics but the kinetics of "early-to-late" apoptosis appears to be a fixed program.

  20. A Candida biofilm-induced pathway for matrix glucan delivery: implications for drug resistance.

    Directory of Open Access Journals (Sweden)

    Heather T Taff

    Full Text Available Extracellular polysaccharides are key constituents of the biofilm matrix of many microorganisms. One critical carbohydrate component of Candida albicans biofilms, β-1,3 glucan, has been linked to biofilm protection from antifungal agents. In this study, we identify three glucan modification enzymes that function to deliver glucan from the cell to the extracellular matrix. These enzymes include two predicted glucan transferases and an exo-glucanase, encoded by BGL2, PHR1, and XOG1, respectively. We show that the enzymes are crucial for both delivery of β-1,3 glucan to the biofilm matrix and for accumulation of mature matrix biomass. The enzymes do not appear to impact cell wall glucan content of biofilm cells, nor are they necessary for filamentation or biofilm formation. We demonstrate that mutants lacking these genes exhibit enhanced susceptibility to the commonly used antifungal, fluconazole, during biofilm growth only. Transcriptional analysis and biofilm phenotypes of strains with multiple mutations suggest that these enzymes act in a complementary fashion to distribute matrix downstream of the primary β-1,3 glucan synthase encoded by FKS1. Furthermore, our observations suggest that this matrix delivery pathway works independently from the C. albicans ZAP1 matrix formation regulatory pathway. These glucan modification enzymes appear to play a biofilm-specific role in mediating the delivery and organization of mature biofilm matrix. We propose that the discovery of inhibitors for these enzymes would provide promising anti-biofilm therapeutics.

  1. Epac is required for exogenous and endogenous stimulation of adenosine A2B receptor for inhibition of angiotensin II-induced collagen synthesis and myofibroblast differentiation.

    Science.gov (United States)

    Phosri, Sarawuth; Bunrukchai, Kwanchai; Parichatikanond, Warisara; Sato, Vilasinee H; Mangmool, Supachoke

    2018-01-10

    Angiotensin II (Ang II) plays an important role on the pathogenesis of cardiac fibrosis. Prolong and overstimulation of angiotensin II type 1 receptor with Ang II-induced collagen synthesis and myofibroblast differentiation in cardiac fibroblasts, leading to cardiac fibrosis. Although adenosine and its analogues are known to have cardioprotective effects, the mechanistic by which adenosine A 2 receptors (A 2 Rs) inhibit Ang II-induced cardiac fibrosis is not clearly understood. In the present study, we examined the effects of exogenous adenosine and endogenous adenosine on Ang II-induced collagen and myofibroblast differentiation determined by α-smooth muscle action (α-SMA) overexpression and their underlying signal transduction. Elevation of endogenous adenosine levels resulted in the inhibition of Ang II-induced collagen type I and III and α-SMA synthesis in cardiac fibroblasts. Moreover, treatment with exogenous adenosine which selectively stimulated A 2 Rs also suppressed Ang II-induced collagen synthesis and α-SMA production. These antifibrotic effects of both endogenous and exogenous adenosines are mediated through the A 2B receptor (A 2B R) subtype. Stimulation of A 2B R exhibited antifibrotic effects via the cAMP-dependent and Epac-dependent pathways. Our results provide new mechanistic insights regarding the role for cAMP and Epac on A 2B R-mediated antifibrotic effects. Thus, A 2B R is one of the potential therapeutic targets against cardiac fibrosis.

  2. EXOGENOUS TESTOSTERONE DOES NOT INDUCE OR EXACERBATE THE METABOLIC FEATURES ASSOCIATED WITH PCOS AMONG TRANSGENDER MEN.

    Science.gov (United States)

    Chan, Kelly J; Liang, Jennifer J; Jolly, Divya; Weinand, Jamie D; Safer, Joshua D

    2018-04-06

    Polycystic ovarian syndrome (PCOS) is a complex condition which can include menstrual irregularity, metabolic derangement, and increased androgen levels. The mechanism of PCOS is unknown. Some suggest that excess production of androgens by the ovaries may cause or exacerbate the metabolic findings. The purpose of this study was to assess the role of increased testosterone on metabolic parameters on individuals presumed to be chromosomally female by examination of these parameters in hormone-treated transgender men. In 2015 and 2016, we asked all transgender men who visited the Endocrinology Clinic at Boston Medical Center treated with testosterone for consent for a retrospective anonymous chart review. Of the 36 men, 34 agreed (94%). Serum metabolic factors and body mass index levels for each patient were graphed over time, from initiation of therapy through 6 years of treatment. Bivariate analyses were conducted to analyze the impact of added testosterone. Regressions measuring the impact of testosterone demonstrated no significant change in levels of glycosylated hemoglobin, triglycerides, or low density lipoprotein cholesterol. There was a statistically significant decrease in BMI with increasing testosterone. There was also a statistically significant decrease in high density lipoprotein levels upon initiation of testosterone therapy. Testosterone therapy in transgender men across a wide range of doses and over many years did not result in the abnormalities in HbA1c or dyslipidemia seen with PCOS. Instead, treatment of transgender men with testosterone resulted only in a shift of metabolic biomarkers toward the average physiologic male body. This retrospective chart review of 34 transgender men found that testosterone therapy does not induce or exacerbate the metabolic features associated with PCOS.

  3. Exogenous Trehalose Largely Alleviates Ionic Unbalance, ROS Burst and PCD Occurrence Induced by High Salinity in Arabidopsis Seedlings

    Directory of Open Access Journals (Sweden)

    Lei eYang

    2014-10-01

    Full Text Available Trehalose (Tre has been reported to play a critical role in plant response to salinity and the involved mechanisms remain to be investigated in detail. Here, the putative roles of Tre in regulation of ionic balance, cellular redox state, cell death were studied in Arabidopsis under high salt condition. Our results found that the salt-induced restrictions on both vegetative and reproductive growth in salt-stressed plants were largely alleviated by exogenous supply with Tre. The microprobe analysis of ionic dynamics in the leaf and stem of florescence highlighted the Tre ability to retain K and K/Na ratio in plant tissues to improve salt tolerance. The flow cytometric (FCM assay of cellular levels of ROS (reactive oxygen species and PCD (programmed cell death displayed that Tre was able to antagonized salt-induced damages in redox state and cell death and sucrose did not play the same role with Tre. By comparing ionic distribution in leaf and IS (inflorescence stem, we found that Tre was able to restrict Na transportation to IS from leaves since that the ratio of Na accumulation in leaves relative to IS was largely improved due to Tre. The marked decrease of Na ion and improved sucrose level in IS might account for the promoted floral growth when Tre was included in the saline solution. At the same time, endogenous soluble sugars and antioxidant enzyme activities in the salt-stressed plants were also elevated by Tre to counteract high salt stress. We concluded that Tre could improve Arabidopsis salt resistance with respect to biomass accumulation and floral transition in the means of regulating plant redox state, cell death and ionic distribution.

  4. Glucose & sodium chloride induced biofilm production & ica operon in clinical isolates of staphylococci

    Directory of Open Access Journals (Sweden)

    Astha Agarwal

    2013-01-01

    Full Text Available Background & objectives: All colonizing and invasive staphylococcal isolates may not produce biofilm but may turn biofilm producers in certain situations due to change in environmental factors. This study was done to test the hypothesis that non biofilm producing clinical staphylococci isolates turn biofilm producers in presence of sodium chloride (isotonic and high concentration of glucose, irrespective of presence or absence of ica operon. Methods: Clinical isolates of 100 invasive, 50 colonizing and 50 commensal staphylococci were tested for biofilm production by microtiter plate method in different culture media (trypticase soy broth alone or supplemented with 0.9% NaCl/ 5 or 10% glucose. All isolates were tested for the presence of ica ADBC genes by PCR. Results: Biofilm production significantly increased in the presence of glucose and saline, most, when both glucose and saline were used together. All the ica positive staphylococcal isolates and some ica negative isolates turned biofilm producer in at least one of the tested culture conditions. Those remained biofilm negative in different culture conditions were all ica negative. Interpretation & conclusions: The present results showed that the use of glucose or NaCl or combination of both enhanced biofilm producing capacity of staphylococcal isolates irrespective of presence or absence of ica operon.

  5. Exogenous Ochronosis

    Directory of Open Access Journals (Sweden)

    Prachi A Bhattar

    2015-01-01

    Full Text Available Exogenous ochronosis (EO is a cutaneous disorder characterized by blue-black pigmentation resulting as a complication of long-term application of skin-lightening creams containing hydroquinone but may also occur due to topical contact with phenol or resorcinol in dark-skinned individuals. It can also occur following the use of systemic antimalarials such as quinine. EO is clinically and histologically similar to its endogenous counterpart viz., alkaptonuria, which, however, exhibits systemic effects and is an inherited disorder. Dermoscopy and in vivo skin reflectance confocal microscopy are noninvasive in vivo diagnostic tools. It is very difficult to treat EO, a cosmetically disfiguring and troubling disorder with disappointing treatment options.

  6. Phage-mediated dispersal of biofilm and distribution of bacterial virulence genes is induced by quorum sensing.

    Directory of Open Access Journals (Sweden)

    Friederike S Rossmann

    2015-02-01

    Full Text Available The microbiome and the phage meta-genome within the human gut are influenced by antibiotic treatments. Identifying a novel mechanism, here we demonstrate that bacteria use the universal communication molecule AI-2 to induce virulence genes and transfer them via phage release. High concentrations (i.e. 100 μM of AI-2 promote dispersal of bacteria from already established biofilms, and is associated with release of phages capable of infecting other bacteria. Enterococcus faecalis V583ΔABC harbours 7 prophages in its genome, and a mutant deficient in one of these prophages (i.e. prophage 5 showed a greatly reduced dispersal of biofilm. Infection of a probiotic E. faecalis strain without lytic prophages with prophage 5 resulted in increased biofilm formation and also in biofilm dispersal upon induction with AI-2. Infection of the probiotic E. faecalis strain with phage-containing supernatants released through AI-2 from E. faecalis V583ΔABC resulted in a strong increase in pathogenicity of this strain. The polylysogenic probiotic strain was also more virulent in a mouse sepsis model and a rat endocarditis model. Both AI-2 and ciprofloxacin lead to phage release, indicating that conditions in the gastrointestinal tract of hospitalized patients treated with antibiotics might lead to distribution of virulence genes to apathogenic enterococci and possibly also to other commensals or even to beneficial probiotic strains.

  7. Inhibition of Candida albicans Biofilm Formation by the Synthetic Lactoferricin Derived Peptide hLF1-11.

    Science.gov (United States)

    Morici, Paola; Fais, Roberta; Rizzato, Cosmeri; Tavanti, Arianna; Lupetti, Antonella

    2016-01-01

    The aim of this study was to evaluate the in vitro activity of the synthetic peptide hLF1-11 against biofilm produced by clinical isolates of Candida albicans with different fluconazole susceptibility. The antibiofilm activity of the peptide hLF1-11 was assessed in terms of reduction of biofilm cellular density, metabolic activity and sessile cell viability. The extent of morphogenesis in hLF1-11 treated and untreated biofilms was also investigated microscopically. Transcription levels of genes related to cell adhesion, hyphal development and extracellular matrix production were analysed by qRT-PCR in hLF1-11 treated and untreated biofilms. Exogenous dibutyryl-cAMP (db-cAMP) was used to rescue morphogenesis in cells exposed to the peptide. The results revealed that hLF1-11 exhibited an inhibitory effect on biofilm formation by all C. albicans isolates tested in a dose-dependent manner, regardless of their fluconazole susceptibility. Visual inspection of treated or untreated biofilm cells with an inverted microscope revealed a significant reduction in hyphal formation by hLF1-11 treated cells, as early as 3 hours of incubation. Moreover, hLF1-11 showed a reduced activity on preadherent cells. hLF1-11 induced the down-regulation of biofilm and hyphal-associated genes, which were predominantly regulated via the Ras1-cAMP-Efg1 pathway. Indeed, exogenous db-cAMP restored morphogenesis in hLF1-11 treated cells. The hLF1-11 peptide significantly inhibited biofilm formation by C. albicans mainly at early stages, interfering with biofilm cellular density and metabolic activity, and affected morphogenesis through the Ras1-cAMP-Efg1 pathway. Our findings provide the first evidence that hLF1-11 could represent a potential candidate for the prevention of biofilm formation by C. albicans.

  8. The cabABC Operon Essential for Biofilm and Rugose Colony Development in Vibrio vulnificus.

    Directory of Open Access Journals (Sweden)

    Jin Hwan Park

    2015-09-01

    Full Text Available A transcriptome analysis identified Vibrio vulnificus cabABC genes which were preferentially expressed in biofilms. The cabABC genes were transcribed as a single operon. The cabA gene was induced by elevated 3',5'-cyclic diguanylic acid (c-di-GMP and encoded a calcium-binding protein CabA. Comparison of the biofilms produced by the cabA mutant and its parent strain JN111 in microtiter plates using crystal-violet staining demonstrated that CabA contributed to biofilm formation in a calcium-dependent manner under elevated c-di-GMP conditions. Genetic and biochemical analyses revealed that CabA was secreted to the cell exterior through functional CabB and CabC, distributed throughout the biofilm matrix, and produced as the biofilm matured. These results, together with the observation that CabA also contributes to the development of rugose colony morphology, indicated that CabA is a matrix-associated protein required for maturation, rather than adhesion involved in the initial attachment, of biofilms. Microscopic comparison of the structure of biofilms produced by JN111 and the cabA mutant demonstrated that CabA is an extracellular matrix component essential for the development of the mature biofilm structures in flow cells and on oyster shells. Exogenously providing purified CabA restored the biofilm- and rugose colony-forming abilities of the cabA mutant when calcium was available. Circular dichroism and size exclusion analyses revealed that calcium binding induces CabA conformational changes which may lead to multimerization. Extracellular complementation experiments revealed that CabA can assemble a functional matrix only when exopolysaccharides coexist. Consequently, the combined results suggested that CabA is a structural protein of the extracellular matrix and multimerizes to a conformation functional in building robust biofilms, which may render V. vulnificus to survive in hostile environments and reach a concentrated infective dose.

  9. Vacquinol-1 inducible cell death in glioblastoma multiforme is counter regulated by TRPM7 activity induced by exogenous ATP

    OpenAIRE

    Sander, Philip; Mostafa, Haouraa; Soboh, Ayman; Schneider, Julian M.; Pala, Andrej; Baron, Ann-Kathrin; Moepps, Barbara; Wirtz, C. Rainer; Georgieff, Michael; Schneider, Marion

    2017-01-01

    Glioblastomas (GBM) are the most malignant brain tumors in humans and have a very poor prognosis. New therapeutic options are urgently needed. A novel drug, Vacquinol-1 (Vac), a quinolone derivative, displays promising properties by inducing rapid cell death in GBM but not in non-transformed tissues. Features of this type of cell death are compatible with a process termed methuosis. Here we tested Vac on a highly malignant glioma cell line observed by long-term video microscopy. Human dental-...

  10. Proteomics and transcriptomics of broccoli subjected to exogenously supplied and transgenic senescence-induced cytokinin for amelioration of postharvest yellowing.

    Science.gov (United States)

    Liu, Mao-Sen; Li, Hui-Chun; Lai, Ying-Mi; Lo, Hsiao-Feng; Chen, Long-Fang O

    2013-11-20

    Previously, we investigated transgenic broccoli harboring senescence-associated-gene (SAG) promoter-triggered isopentenyltransferase (ipt), which encodes the key enzyme for cytokinin (CK) synthesis and mimics the action of exogenous supplied CK in delaying postharvest senescence of broccoli. Here, we used proteomics and transcriptomics to compare the mechanisms of ipt-transgenic and N(6)-benzylaminopurine (BA) CK treatment of broccoli during postharvest storage. The 2 treatments conferred common and distinct mechanisms. BA treatment decreased the quantity of proteins involved in energy and carbohydrate metabolism and amino acid metabolism, and ipt-transgenic treatment increased that of stress-related proteins and molecular chaperones and slightly affected levels of carbohydrate metabolism proteins. Both treatments regulated genes involved in CK signaling, sugar transport, energy and carbohydrate metabolism, amino acid metabolism and lipid metabolism, although ipt-transgenic treatment to a lesser extent. BA treatment induced genes encoding molecular chaperones, whereas ipt-transgenic treatment induced stress-related genes for cellular protection during storage. Both BA and ipt-transgenic treatments acted antagonistically on ethylene functions. We propose a long-term acclimation of metabolism and protection systems with ipt-transgenic treatment of broccoli and short-term modulation of metabolism and establishment of a protection system with both BA and ipt-transgenic treatments in delaying senescence of broccoli florets. Transgenic broccoli harboring senescence-associated-gene (SAG) promoter-triggered isopentenyltransferase (ipt), which encodes the key enzyme for cytokinin (CK) synthesis and N(6)-benzylaminopurine (BA) CK treated broccoli both showed retardation of postharvest senescence during storage. The mechanisms underlying the two treatments were compared. The combination of proteomic and transcriptomic evidences revealed that the 2 treatments conferred common

  11. Characterization of starvation-induced dispersion in Pseudomonas putida biofilms: genetic elements and molecular mechanisms

    DEFF Research Database (Denmark)

    Gjermansen, M.; Nilsson, M.; Yang, Liang

    2010-01-01

    P>Pseudomonas putida OUS82 biofilm dispersal was previously shown to be dependent on the gene PP0164 (here designated lapG). Sequence and structural analysis has suggested that the LapG geneproduct belongs to a family of cysteine proteinases that function in the modification of bacterial surface...... proteins. We provide evidence that LapG is involved in P. putida OUS82 biofilm dispersal through modification of the outer membrane-associated protein LapA. While the P. putida lapG mutant formed more biofilm than the wild-type, P. putida lapA and P. putida lapAG mutants displayed decreased surface...

  12. Exogenous IFN-beta regulates the RANKL-c-Fos-IFN-beta signaling pathway in the collagen antibody-induced arthritis model.

    Science.gov (United States)

    Zhao, Rong; Chen, Ni-Nan; Zhou, Xiao-Wei; Miao, Ping; Hu, Chao-Ying; Qian, Liu; Yu, Qi-Wen; Zhang, Ji-Ying; Nie, Hong; Chen, Xue-hua; Li, Pu; Xu, Rong; Xiao, Lian-Bo; Zhang, Xin; Liu, Jian-Ren; Zhang, Dong-Qing

    2014-12-10

    Although a variety of drugs have been used to treat the symptoms of rheumatoid arthritis (RA), none of them are able to cure the disease. Interferon β (IFN-β) has pleiotropic effects on RA, but whether it can be used to treat RA remains globally controversial. Thus, in this study we tested the effects of IFN-β on RA patients and on collagen antibody-induced arthritis (CAIA) model mice. The cytokine and auto-antibody expression profiles in the serum and synovial fluid (SF) from RA patients were assessed using enzyme-linked immunosorbent assay (ELISA) and compared with the results from osteoarthritis (OA) patients. Exogenous IFN-β was administered to RA patients and CAIA model mice, and the therapeutic effects were evaluated. Endogenous IFN-β expression in the joint bones of CAIA model mice was evaluated by quantitative real-time PCR (qRT-PCR). The effects of exogenous IFN-β on CAIA model mice were assessed using a clinical scoring system, hematoxylin eosin and safranin-O with fast green counterstain histology, molybdenum target X-ray, and tartrate-resistant acid phosphatase (TRAP) staining. The RANKL-RANK signaling pathway was analyzed using qRT-PCR. The RAW 264.7 cell line was differentiated into osteoclasts with RANKL stimulation and then treated with exogenous IFN-β. The expression of inflammatory cytokines (IFN-γ, IL-17, MMP-3, and RANKL) and auto-antibodies (CII antibodies, RF-IgM, and anti-CCP/GPI) were significantly higher in RA compared with OA patients. After IFN-β intervention, some clinical symptoms in RA patients were partially alleviated, and the expression of IFN-γ, IL-17, MMP-3, and OPG) returned to normal levels. In the CAIA model, the expression of endogenous IFN-β in the joint bones was decreased. After IFN-β administration, the arthritis scores were decreased; synovial inflammation, cartilage, and bone destruction were clearly attenuated; and the expression of c-Fos and NFATc1 were reduced, while RANKL and TRAF6 expression was

  13. Metabolite responses to exogenous application of nitrogen, cytokinin, and ethylene inhibitors in relation to heat-induced senescence in creeping bentgrass.

    Directory of Open Access Journals (Sweden)

    David Jespersen

    Full Text Available The exogenous application of ethylene inhibitors, cytokinins, or nitrogen has previously been shown to suppress heat-induced senescence and improve heat tolerance in cool-season grasses. The objectives of this study were to examine metabolic profiles altered by exogenous treatment of creeping bentgrass with an ethylene inhibitor, cytokinin or nitrogen under heat stress and to determine metabolic pathways regulated by those compounds in association with their effectiveness for improving heat tolerance. Creeping bentgrass (Agostis stolonifera plants (cv. Penncross were foliar sprayed with 18 mM carbonyldiamide (N source, 25 μM aminoethoxyvinylglycine (AVG, ethylene inhibitor, 25 μM zeatin riboside (ZR, cytokinin, or a water control, and then exposed to 20/15°C (day/night or 35/30°C (heat stress in growth chambers. All three exogenous treatments suppressed leaf senescence, as manifested by increased turf quality and chlorophyll content, and reduced electrolyte leakage under heat stress. Polar metabolite profiling identified increases in the content of certain organic acids (i.e. citric and malic acid, sugar alcohols, disaccharides (sucrose, and decreased accumulations of monosaccharides (i.e. glucose and fructose with exogenous treatment of N, AVG, or ZR at the previously mentioned concentrations when compared to the untreated control under heat stress. Nitrogen stimulated amino acid accumulation whereas AVG and ZR reduced amino acid accumulation compared to the untreated control under heat stress. These results revealed that the alleviation of heat-induced leaf senescence by N, AVG, and ZR could be due to changes in the accumulation of metabolites involved in osmoregulation, antioxidant metabolism, carbon and nitrogen metabolism, as well as stress signaling molecules.

  14. Combination of exogenous cell transplantation and 5-HT{sub 4} receptor agonism induce endogenous enteric neural crest-derived cells in a rat hypoganglionosis model

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Hui [Department of Pediatric Surgery, the Second Affiliated Hospital, Xi’an Jiaotong University, No 157, Xi Wu Road, Xi’an 710004, Shaanxi (China); Institute of Neurobiology, Environment and Genes Related to Diseases Key Laboratory of Chinese Ministry of Education, Xi’an Jiaotong University, No 96, Yan Ta Xi Road, Xi’an 710061, Shaanxi (China); Zheng, Bai-Jun; Pan, Wei-Kang; Wang, Huai-Jie; Xie, Chong; Zhao, Yu-Ying [Department of Pediatric Surgery, the Second Affiliated Hospital, Xi’an Jiaotong University, No 157, Xi Wu Road, Xi’an 710004, Shaanxi (China); Chen, Xin-Lin; Liu, Yong [Institute of Neurobiology, Environment and Genes Related to Diseases Key Laboratory of Chinese Ministry of Education, Xi’an Jiaotong University, No 96, Yan Ta Xi Road, Xi’an 710061, Shaanxi (China); Gao, Ya, E-mail: ygao@mail.xjtu.edu.cn [Department of Pediatric Surgery, the Second Affiliated Hospital, Xi’an Jiaotong University, No 157, Xi Wu Road, Xi’an 710004, Shaanxi (China)

    2017-02-01

    Enteric neural crest-derived cells (ENCCs) can migrate into endogenous ganglia and differentiate into progeny cells, and have even partially rescued bowel function; however, poor reliability and limited functional recovery after ENCC transplantation have yet to be addressed. Here, we investigated the induction of endogenous ENCCs by combining exogenous ENCC transplantation with a 5-HT{sub 4} receptor agonist mosapride in a rat model of hypoganglionosis, established by benzalkonium chloride treatment. ENCCs, isolated from the gut of newborn rats, were labeled with a lentiviral eGFP reporter. ENCCs and rats were treated with the 5-HT{sub 4} receptor agonist/antagonist. The labeled ENCCs were then transplanted into the muscular layer of benzalkonium chloride-treated colons. At given days post-intervention, colonic tissue samples were removed for histological analysis. ENCCs and neurons were detected by eGFP expression and immunoreactivity to p75{sup NTR} and peripherin, respectively. eGFP-positive ENCCs and neurons could survive and maintain levels of fluorescence after transplantation. With longer times post-intervention, the number of peripherin-positive cells gradually increased in all groups. Significantly more peripherin-positive cells were found following ENCCs plus mosapride treatment, compared with the other groups. These results show that exogenous ENCCs combined with the 5-HT{sub 4} receptor agonist effectively induced endogenous ENCCs proliferation and differentiation in a rat hypoganglionosis model. - Highlights: • Survival and differentiation of exogenous ENCCs in treated colons. • With longer times post-intervention, the number of ENCCs and their progeny cells gradually increased. • Exogenous ENCCs combined with the 5-HT4 receptor agonist ffectively induced ENCCs proliferation and differentiation.

  15. Combination of exogenous cell transplantation and 5-HT4 receptor agonism induce endogenous enteric neural crest-derived cells in a rat hypoganglionosis model

    International Nuclear Information System (INIS)

    Yu, Hui; Zheng, Bai-Jun; Pan, Wei-Kang; Wang, Huai-Jie; Xie, Chong; Zhao, Yu-Ying; Chen, Xin-Lin; Liu, Yong; Gao, Ya

    2017-01-01

    Enteric neural crest-derived cells (ENCCs) can migrate into endogenous ganglia and differentiate into progeny cells, and have even partially rescued bowel function; however, poor reliability and limited functional recovery after ENCC transplantation have yet to be addressed. Here, we investigated the induction of endogenous ENCCs by combining exogenous ENCC transplantation with a 5-HT 4 receptor agonist mosapride in a rat model of hypoganglionosis, established by benzalkonium chloride treatment. ENCCs, isolated from the gut of newborn rats, were labeled with a lentiviral eGFP reporter. ENCCs and rats were treated with the 5-HT 4 receptor agonist/antagonist. The labeled ENCCs were then transplanted into the muscular layer of benzalkonium chloride-treated colons. At given days post-intervention, colonic tissue samples were removed for histological analysis. ENCCs and neurons were detected by eGFP expression and immunoreactivity to p75 NTR and peripherin, respectively. eGFP-positive ENCCs and neurons could survive and maintain levels of fluorescence after transplantation. With longer times post-intervention, the number of peripherin-positive cells gradually increased in all groups. Significantly more peripherin-positive cells were found following ENCCs plus mosapride treatment, compared with the other groups. These results show that exogenous ENCCs combined with the 5-HT 4 receptor agonist effectively induced endogenous ENCCs proliferation and differentiation in a rat hypoganglionosis model. - Highlights: • Survival and differentiation of exogenous ENCCs in treated colons. • With longer times post-intervention, the number of ENCCs and their progeny cells gradually increased. • Exogenous ENCCs combined with the 5-HT4 receptor agonist ffectively induced ENCCs proliferation and differentiation.

  16. Histomorphological changes in induced benign prostatic hyperplasia with exogenous testosterone and estradiol in adult male rats treated with aqueous ethanol extract of Secamone afzelii

    Directory of Open Access Journals (Sweden)

    Godwin Mbaka

    2017-03-01

    Full Text Available Secamone afzelii (S. afzelii used locally to manage benign prostatic hyperplasia (BPH was used to treat exogenously induced BPH in adult male Wister rats. Male rats weighing 200 ± 10 g kg−1 had exogenous administration of testosterone and estradiol in staggered doses (three times weekly for three weeks. The induced animals were in five groups (6 rats per group. Groups 1 and 2 received extract at 200 and 400 mg kg−1 body weight (bwt by gavages for thirty days; group 3, finasteride (0.1 mg kg−1; group 4, untreated for thirty days; group 5, negative control, which was sacrificed twenty-one days after induction. Group 6 received extract (400 mg kg−1 and steroid hormones simultaneously; group 7, normal control. The extract caused marked decrease in prostate weight of BPH induced rats with the photomicrograph of the prostate showing extensive shrinkage of glandular tissue whereas glandular hyperplasia occurred in the negative control. Prostate specific antigen (PSA level significantly (p < 0.05 decreased in the treated groups compared to negative control. Treatment with the extract/finasteride caused significant decrease in testosterone to a level comparable to normal. The BPH induced rats treated with S. afzelii/finasteride recorded marked increase in the levels of antioxidant enzymes compared to the negative control. S. afzelii effectively ameliorated prostatic hyperplasia exogenously induced by causing extensive shrinkage of glands and stroma. It also exhibited antioxidant properties and showed to be a good prophylaxis.

  17. Combating biofilms

    DEFF Research Database (Denmark)

    Yang, Liang; Liu, Yang; Wu, Hong

    2012-01-01

    Biofilms are complex microbial communities consisting of microcolonies embedded in a matrix of self-produced polymer substances. Biofilm cells show much greater resistance to environmental challenges including antimicrobial agents than their free-living counterparts. The biofilm mode of life...... is believed to significantly contribute to successful microbial survival in hostile environments. Conventional treatment, disinfection and cleaning strategies do not proficiently deal with biofilm-related problems, such as persistent infections and contamination of food production facilities. In this review......, strategies to control biofilms are discussed, including those of inhibition of microbial attachment, interference of biofilm structure development and differentiation, killing of biofilm cells and induction of biofilm dispersion....

  18. Electric current-induced detachment of Staphylococcus epidermidis biofilms from surgical stainless steel

    NARCIS (Netherlands)

    van der Borden, AJ; van der Mei, HC; Busscher, HJ

    2004-01-01

    Biomaterial-centered infections of orthopedic percutaneous implants are serious complications which can ultimately lead to osteomyelitis, with devastating effects on bone and surrounding tissues, especially since the biofilm mode of growth offers protection against antibiotics and since removal

  19. Impact of combined CO2 laser irradiation and fluoride on enamel and dentin biofilm-induced mineral loss.

    Science.gov (United States)

    Esteves-Oliveira, Marcella; El-Sayed, Karim Fawzy; Dörfer, Christof; Schwendicke, Falk

    2017-05-01

    The caries-protective effects of CO 2 laser irradiation on dental enamel have been demonstrated using chemical demineralization models. We compared the effect of CO 2 laser irradiation, sodium fluoride, or both on biofilm-induced mineral loss (∆Z) and Streptococcus mutans adhesion to enamel and dentin in vitro. Ground, polished bovine enamel, and dentin samples were allocated to four groups (n = 12/group): no treatment (C); single 22,600-ppm fluoride (F) varnish (5 % NaF) application; single CO 2 laser treatment (L) with short pulses (5 μs/λ = 10.6 μm); and laser and subsequent fluoride treatment (LF). Samples were sterilized and submitted to an automated mono-species S. mutans biofilm model. Brain heart infusion plus 5 % sucrose medium was provided eight times daily, followed by rinses with artificial saliva. After 10 days, bacterial numbers in biofilms were enumerated as colony-forming units/ml (CFU/ml) (n = 7/group). ∆Z was assessed using transversal microradiography (n = 12/group). Univariate ANOVA with post hoc Tukey honestly-significant-difference test was used for statistical analysis. Bacterial numbers were significantly higher on dentin than enamel (p  0.05). In dentin, only LF (163/227) significantly reduced ∆Z (p fluoride application was required to protect dentin.

  20. Anhydride-functional silane immobilized onto titanium surfaces induces osteoblast cell differentiation and reduces bacterial adhesion and biofilm formation

    Energy Technology Data Exchange (ETDEWEB)

    Godoy-Gallardo, Maria, E-mail: maria.godoy.gallardo@upc.edu [Biomaterials, Biomechanics and Tissue Engineering Group, Department of Materials Science and Metallurgy, Technical University of Catalonia (UPC), ETSEIB, Av. Diagonal 647, 08028 Barcelona (Spain); Centre for Research in NanoEngineering (CRNE) — UPC, C/ Pascual i Vila 15, 08028 Barcelona (Spain); Guillem-Marti, Jordi, E-mail: jordi.guillem.marti@upc.edu [Biomaterials, Biomechanics and Tissue Engineering Group, Department of Materials Science and Metallurgy, Technical University of Catalonia (UPC), ETSEIB, Av. Diagonal 647, 08028 Barcelona (Spain); Centre for Research in NanoEngineering (CRNE) — UPC, C/ Pascual i Vila 15, 08028 Barcelona (Spain); Sevilla, Pablo, E-mail: psevilla@euss.es [Department of Mechanics, Escola Universitària Salesiana de Sarrià (EUSS), C/ Passeig de Sant Bosco, 42, 08017 Barcelona (Spain); Manero, José M., E-mail: jose.maria.manero@upc.edu [Biomaterials, Biomechanics and Tissue Engineering Group, Department of Materials Science and Metallurgy, Technical University of Catalonia (UPC), ETSEIB, Av. Diagonal 647, 08028 Barcelona (Spain); Centre for Research in NanoEngineering (CRNE) — UPC, C/ Pascual i Vila 15, 08028 Barcelona (Spain); Gil, Francisco J., E-mail: francesc.xavier.gil@upc.edu [Biomaterials, Biomechanics and Tissue Engineering Group, Department of Materials Science and Metallurgy, Technical University of Catalonia (UPC), ETSEIB, Av. Diagonal 647, 08028 Barcelona (Spain); Centre for Research in NanoEngineering (CRNE) — UPC, C/ Pascual i Vila 15, 08028 Barcelona (Spain); and others

    2016-02-01

    Bacterial infection in dental implants along with osseointegration failure usually leads to loss of the device. Bioactive molecules with antibacterial properties can be attached to titanium surfaces with anchoring molecules such as silanes, preventing biofilm formation and improving osseointegration. Properties of silanes as molecular binders have been thoroughly studied, but research on the biological effects of these coatings is scarce. The aim of the present study was to determine the in vitro cell response and antibacterial effects of triethoxysilypropyl succinic anhydride (TESPSA) silane anchored on titanium surfaces. X-ray photoelectron spectroscopy confirmed a successful silanization. The silanized surfaces showed no cytotoxic effects. Gene expression analyses of Sarcoma Osteogenic (SaOS-2) osteoblast-like cells cultured on TESPSA silanized surfaces reported a remarkable increase of biochemical markers related to induction of osteoblastic cell differentiation. A manifest decrease of bacterial adhesion and biofilm formation at early stages was observed on treated substrates, while favoring cell adhesion and spreading in bacteria–cell co-cultures. Surfaces treated with TESPSA could enhance a biological sealing on implant surfaces against bacteria colonization of underlying tissues. Furthermore, it can be an effective anchoring platform of biomolecules on titanium surfaces with improved osteoblastic differentiation and antibacterial properties. - Highlights: • TESPSA silane induces osteoblast differentiation. • TESPSA reduces bacterial adhesion and biofilm formation. • TESPSA is a promising anchoring platform of biomolecules onto titanium.

  1. Anhydride-functional silane immobilized onto titanium surfaces induces osteoblast cell differentiation and reduces bacterial adhesion and biofilm formation

    International Nuclear Information System (INIS)

    Godoy-Gallardo, Maria; Guillem-Marti, Jordi; Sevilla, Pablo; Manero, José M.; Gil, Francisco J.

    2016-01-01

    Bacterial infection in dental implants along with osseointegration failure usually leads to loss of the device. Bioactive molecules with antibacterial properties can be attached to titanium surfaces with anchoring molecules such as silanes, preventing biofilm formation and improving osseointegration. Properties of silanes as molecular binders have been thoroughly studied, but research on the biological effects of these coatings is scarce. The aim of the present study was to determine the in vitro cell response and antibacterial effects of triethoxysilypropyl succinic anhydride (TESPSA) silane anchored on titanium surfaces. X-ray photoelectron spectroscopy confirmed a successful silanization. The silanized surfaces showed no cytotoxic effects. Gene expression analyses of Sarcoma Osteogenic (SaOS-2) osteoblast-like cells cultured on TESPSA silanized surfaces reported a remarkable increase of biochemical markers related to induction of osteoblastic cell differentiation. A manifest decrease of bacterial adhesion and biofilm formation at early stages was observed on treated substrates, while favoring cell adhesion and spreading in bacteria–cell co-cultures. Surfaces treated with TESPSA could enhance a biological sealing on implant surfaces against bacteria colonization of underlying tissues. Furthermore, it can be an effective anchoring platform of biomolecules on titanium surfaces with improved osteoblastic differentiation and antibacterial properties. - Highlights: • TESPSA silane induces osteoblast differentiation. • TESPSA reduces bacterial adhesion and biofilm formation. • TESPSA is a promising anchoring platform of biomolecules onto titanium.

  2. A case of exogenous corticosteroid-induced Kaposi's sarcoma that developed after a cure of endogenous hypercortisolism.

    Science.gov (United States)

    Yoo, Soyeon; Moon, Shinhang; Chin, Sang-Ouk; Lee, Sang-Ah; Hyun, Changlim; Koh, Gwanpyo

    2015-12-01

    Case Kaposi's sarcoma (KS) is a malignant vascular tumor that occurs commonly in patients with acquired immunodeficiency syndrome. KS associated with Cushing's syndrome (CS) is unusual, especially in endogenous CS. Here, we report a case of KS associated with glucocorticoid-replacement therapy after surgical treatment for adrenal CS. A 70-year-old man presented with symptoms and signs of CS with a left adrenal mass. Adrenal CS was confirmed by biochemical studies. After left adrenalectomy, he took oral prednisolone (15 mg/day) to prevent adrenal insufficiency. Ten weeks later, numerous raised purple plaques on the lower extremities were newly detected. The biopsy findings were compatible with KS, but anti-HIV antibodies were negative. After withdrawal of glucocorticoid therapy, the skin lesions regressed completely. In this case, KS developed after the use of exogenous corticosteroid but not during endogenous hypercortisolism. This finding suggests that endogenous and exogenous corticosteroid play different roles in the development of KS.

  3. Exogenous fatty acid metabolism in bacteria.

    Science.gov (United States)

    Yao, Jiangwei; Rock, Charles O

    2017-10-01

    Bacterial type II fatty acid synthesis (FASII) is a target for novel antibiotic development. All bacteria encode for mechanisms to incorporate exogenous fatty acids, and some bacteria can use exogenous fatty acids to bypass FASII inhibition. Bacteria encode three different mechanisms for activating exogenous fatty acids for incorporation into phospholipid synthesis. Exogenous fatty acids are converted into acyl-CoA in Gammaproteobacteria such as E. coli. Acyl-CoA molecules constitute a separate pool from endogenously synthesized acyl-ACP. Acyl-CoA can be used for phospholipid synthesis or broken down by β-oxidation, but cannot be used for lipopolysaccharide synthesis. Exogenous fatty acids are converted into acyl-ACP in some Gram-negative bacteria. The resulting acyl-ACP undergoes the same fates as endogenously synthesized acyl-ACP. Exogenous fatty acids are converted into acyl-phosphates in Gram-positive bacteria, and can be used for phospholipid synthesis or become acyl-ACP. Only the order Lactobacillales can use exogenous fatty acids to bypass FASII inhibition. FASII shuts down completely in presence of exogenous fatty acids in Lactobacillales, allowing Lactobacillales to synthesize phospholipids entirely from exogenous fatty acids. Inhibition of FASII cannot be bypassed in other bacteria because FASII is only partially down-regulated in presence of exogenous fatty acid or FASII is required to synthesize essential metabolites such as β-hydroxyacyl-ACP. Certain selective pressures such as FASII inhibition or growth in biofilms can select for naturally occurring one step mutations that attenuate endogenous fatty acid synthesis. Although attempts have been made to estimate the natural prevalence of these mutants, culture-independent metagenomic methods would provide a better estimate. Copyright © 2017 Elsevier B.V. and Société Française de Biochimie et Biologie Moléculaire (SFBBM). All rights reserved.

  4. Synthesis of phosphatidylcholine in rats with oleic acid-induced pulmonary edema and effect of exogenous pulmonary surfactant on its De Novo synthesis.

    Science.gov (United States)

    Gao, Xiwen; Qian, Peiyu; Cen, Dong; Hong, Weijun; Peng, Qing; Xue, Min

    2018-01-01

    In mammals, oleic acid (OA) induces pulmonary edema (PE), which can initiate acute lung injury (ALI) and lead to acute respiratory distress syndrome (ARDS). Pulmonary surfactant (PS) plays a key role in a broad range of treatments for ARDS. The aim of the present investigation was to assess changes in the synthesis of phosphatidylcholine (PC) from choline and determine the effect of exogenous PS on its de novo synthesis in rats with OA-induced PE. Experimental rats were randomized into three groups, including a control group, OA-induced PE group, and OA-induced group treated with exogenous PS (OA-PS). Twenty-four rats were sacrificed 4 h after induction of the OA model, and tissue was examined by light and electron microscopy to assess the severity of ALI using an established scoring system at the end of the experiment. After 15 μCi 3H-choline chloride was injected intravenously, eight rats in each group were sacrificed at 4, 8, and 16 h. The radioactivity of 3H incorporated into total phospholipid (TPL) and desaturated phosphatidylcholine (DSPC) was measured in bronchoalveolar lavage fluid (BALF) and lung tissue (LT) using a liquid scintillation counter and was expressed as counts per minute (CPM). Results showed that TPL, DSPC, and the ratio of DSPC/total protein (TP) in lung tissue decreased 4 h after challenge with OA, but the levels recovered after 8 and 16 h. At 8 h after injection, 3H-TPL and 3H-DSPC radioactivity in the lungs reached its peak. Importantly, 3H-DSPC CPM were significantly lower in the PS treatment group (LT: Control: 62327 ± 9108; OA-PE: 97315 ± 10083; OA-PS: 45127 ± 10034, P exogenous PS treatments may adversely affect endogenous de novo synthetic and secretory phospholipid pathways via feedback inhibition. This novel finding reveals the specific involvement of exogenous PS in endogenous synthetic and secretory phospholipid pathways during the treatment of ARDS. This information improves our understanding of how PS treatment is

  5. Calibration of a lactic-acid model for simulating biofilm-induced degradation of the dentin-composite interface.

    Science.gov (United States)

    Zhu, Laikuan; Li, Yuping; Carrera, Carola A; Chen, Yung-Chung; Li, Mingyu; Fok, Alex

    2017-11-01

    To verify and calibrate a chemical model for simulating the degradation of the dentin-composite interface induced by multi-species oral biofilms in vitro. Dentin-composite disks (5-mm dia.×2-mm thick) were made from bovine incisor roots and filled with either Z100™ (Z100) or Filtek™ LS (LS) composite. The disks, which were covered with nail varnish, but with one of the dentin-composite margins exposed, were immersed in lactic acid solution at pH 4.5 for up to 48h. Diametral compression was performed to measure the reduction in bond strength of the dentin-composite disks following acid challenge. Scanning electron microscopy (SEM) was used to examine decalcification of dentin and fracture modes of the disks. To better understand the degradation process, micro-computed tomography, in combination with a radiopaque dye (AgNO 3 ), was used to assess interfacial leakage in 3D longitudinally, while SEM was used to determine the path of leakage. One-way analysis of variance (ANOVA) was used to analyze the results, with the level of statistical significance set at pcomposite interface, instead. The degree of dentin demineralization, the reduction in debonding load and the modes of failure observed were very similar to those induced by multi-species oral biofilms found in the previous work. Leakage of AgNO 3 occurred mainly along the hybrid layer. The specimens filled with Z100 had a thicker hybrid layer (∼6.5μm), which exhibited more interfacial leakage than those filled with LS. The chemical model with lactic acid used in this study can induce degradation to the dentin-composite interface similar to those produced by multi-species biofilms. With appropriate calibration, this could provide an effective in vitro method for ageing composite restorations in assessing their potential clinical performance. Copyright © 2017 The Academy of Dental Materials. All rights reserved.

  6. UV-Induced prevention of biofilm formation inside medical tubes and catheters

    DEFF Research Database (Denmark)

    Pedersen, Jens Kristian Mølgaard; Nielsen, Kristian; Bang, Ole

    2014-01-01

    Biofilm formation inside medical tubes and catheters may often cause unwanted infections, illness andimpaired wound healing during medical treatment, resulting in extended hospitalization and - in worst case– life threatening conditions of the patients. In fact, it is estimated, that the infection...... of multi resistant bacteriacultures. Prevention of biofilm formation inside the tube or catheter, without risk of developing multiresistance, may be achieved by creating a UV-exposed environment in the interior. This may be realized bytransforming the tube itself into an optical waveguide supporting UV...... risk connected withthe use of medical tubes and catheters is the direct cause of more than 60% of all infections acquired inEuropean hospitals. Once formed, the biofilm is generally very tough to suppress by either the body’simmunity system or by use of antibiotics, which may even favor the population...

  7. Roles of xanthophylls and exogenous ABA in protection against NaCl-induced photodamage in rice (Oryza sativa L) and cabbage (Brassica campestris).

    Science.gov (United States)

    Zhu, Su-Qin; Chen, Ming-Wei; Ji, Ben-Hua; Jiao, De-Mao; Liang, Jian-Sheng

    2011-08-01

    Changes in actual efficiency of PS II photochemistry, non-photochemical quenching (NPQ), content of xanthophylls and kinetics of de-epoxidation were studied in ABA-fed and non-ABA-fed leaves of rice and cabbage under NaCl stress. Salt stress induced more progressive decrease in actual efficiency of PS II photochemistry (ФPS II), higher reduction state of PS II, and a small significant increase in NPQ in NaCl-sensitive rice plants as compared with NaCl-tolerant cabbage plants, whereas exogenously supplied ABA alleviated the decrease in actual efficiency of PS II photochemistry (ФPS II), induced a lower reduction state of PS II, and caused higher capacity of NPQ in ABA-fed plants than in non-ABA-fed plants. As a result, there were higher activities of photosynthetic electron transport, higher capacity of energy dissipation, and lower cumulation of excess light in cabbage than in rice plants, and in ABA-fed leaves than in non-ABA-fed leaves. The effect of ABA was more efficient in cabbage than in rice plants. Addition of exogenous ABA resulted in enhancement of the size of the xanthophyll cycle pool, promotion of de-epoxidation of the xanthophyll cycle components, and a rise in the level of NPQ by altering the kinetics of de-epoxidation of the xanthophyll cycle. Protection from photodamage appears to be achieved by coordinated contributions by exogenous ABA and xanthophyll cycle-mediated NPQ. This variety of photoprotective mechanisms may be essential for conferring photodamage tolerance under NaCl stress. © The Author [2011]. Published by Oxford University Press [on behalf of the Society for Experimental Biology]. All rights reserved.

  8. Sunlight-induced inactivation of human Wa and porcine OSU rotaviruses in the presence of exogenous photosensitizers

    KAUST Repository

    Romero-Maraccini, Ofelia C.

    2013-10-01

    Human rotavirus Wa and porcine rotavirus OSU solutions were irradiated with simulated solar UV and visible light in the presence of different photosensitizers dissolved in buffered solutions. For human rotavirus, the exogenous effects were greater than the endogenous effects under irradiation with full spectrum and UVA and visible light at 25 C. For porcine rotavirus, the exogenous effects with UVA and visible light irradiation were only observed at high temperatures, >40 C. The results from dark experiments conducted at different temperatures suggest that porcine rotavirus has higher thermostability than human rotavirus. Concentrations of 3′-MAP excited triplet states of 1.8 fM and above resulted in significant human rotavirus inactivation. The measured excited triplet state concentrations of ≤0.45 fM produced by UVA and visible light irradiation of natural dissolved organic matter solutions were likely not directly responsible for rotavirus inactivation. Instead, the linear correlation for human rotavirus inactivation rate constant (kobs) with the phenol degradation rate constant (kexp) found in both 1 mM NaHCO3 and 1 mM phosphate-buffered solutions suggested that OH radical was a major reactive species for the exogenous inactivation of rotaviruses. Linear correlations between rotavirus kobs and specific UV254 nm absorbance of two river-dissolved organic matter and two effluent organic matter isolates indicated that organic matter aromaticity may help predict formation of radicals responsible for rotavirus inactivation. The results from this study also suggested that the differences in rotavirus strains should be considered when predicting solar inactivation of rotavirus in sunlit surface waters. © 2013 American Chemical Society.

  9. Exogenous glucagon-like peptide-2 (GLP-2) prevents chemotherapy-induced mucositis in rat small intestine

    DEFF Research Database (Denmark)

    Kissow, Hannelouise; Viby, Niels-Erik; Hartmann, Bolette

    2012-01-01

    was analysed for weight loss, morphometric estimates and proliferation. Study 2 Rats were treated with GLP-2 or control vehicle 2 days before a single injection of 5-FU or saline. The treatments continued until kill 2 days after. The intestine was investigated for influx of myeloperoxidase (MPO)-positive cells...... and morphometric estimates, such as villus height, as a marker of mucositis. RESULTS STUDY 1: Two days after chemotherapy, there was a rise in endogenous GLP-2, followed by a marked increase in proliferation. Study 2 Exogenous GLP-2 was able to protect the intestine from severe weight loss and completely prevented...

  10. Magnesium limitation is an environmental trigger of the Pseudomonas aeruginosa biofilm lifestyle.

    Directory of Open Access Journals (Sweden)

    Heidi Mulcahy

    Full Text Available Biofilm formation is a conserved strategy for long-term bacterial survival in nature and during infections. Biofilms are multicellular aggregates of cells enmeshed in an extracellular matrix. The RetS, GacS and LadS sensors control the switch from a planktonic to a biofilm mode of growth in Pseudomonas aeruginosa. Here we detail our approach to identify environmental triggers of biofilm formation by investigating environmental conditions that repress expression of the biofilm repressor RetS. Mg(2+ limitation repressed the expression of retS leading to increased aggregation, exopolysaccharide (EPS production and biofilm formation. Repression of retS expression under Mg(2+ limitation corresponded with induced expression of the GacA-controlled small regulatory RNAs rsmZ and rsmY and the EPS biosynthesis operons pel and psl. We recently demonstrated that extracellular DNA sequesters Mg(2+ cations and activates the cation-sensing PhoPQ two-component system, which leads to increased antimicrobial peptide resistance in biofilms. Here we show that exogenous DNA and EDTA, through their ability to chelate Mg(2+, promoted biofilm formation. The repression of retS in low Mg(2+ was directly controlled by PhoPQ. PhoP also directly controlled expression of rsmZ but not rsmY suggesting that PhoPQ controls the equilibrium of the small regulatory RNAs and thus fine-tunes the expression of genes in the RetS pathway. In summary, Mg(2+ limitation is a biologically relevant environmental condition and the first bonafide environmental signal identified that results in transcriptional repression of retS and promotes P. aeruginosa biofilm formation.

  11. Biofilm Formation and Heat Stress Induce Pyomelanin Production in Deep-Sea Pseudoalteromonas sp. SM9913.

    Science.gov (United States)

    Zeng, Zhenshun; Cai, Xingsheng; Wang, Pengxia; Guo, Yunxue; Liu, Xiaoxiao; Li, Baiyuan; Wang, Xiaoxue

    2017-01-01

    Pseudoalteromonas is an important bacterial genus present in various marine habitats. Many strains of this genus are found to be surface colonizers on marine eukaryotes and produce a wide range of pigments. However, the exact physiological role and mechanism of pigmentation were less studied. Pseudoalteromonas sp. SM9913 (SM9913), an non-pigmented strain isolated from the deep-sea sediment, formed attached biofilm at the solid-liquid interface and pellicles at the liquid-air interface at a wide range of temperatures. Lower temperatures and lower nutrient levels promoted the formation of attached biofilm, while higher nutrient levels promoted pellicle formation of SM9913. Notably, after prolonged incubation at higher temperatures growing planktonically or at the later stage of the biofilm formation, we found that SM9913 released a brownish pigment. By comparing the protein profile at different temperatures followed by qRT-PCR, we found that the production of pigment at higher temperatures was due to the induction of melA gene which is responsible for the synthesis of homogentisic acid (HGA). The auto-oxidation of HGA can lead to the formation of pyomelanin, which has been shown in other bacteria. Fourier Transform Infrared Spectrometer analysis confirmed that the pigment produced in SM9913 was pyomelanin-like compound. Furthermore, we demonstrated that, during heat stress and during biofilm formation, the induction level of melA gene was significantly higher than that of the hmgA gene which is responsible for the degradation of HGA in the L-tyrosine catabolism pathway. Collectively, our results suggest that the production of pyomelanin of SM9913 at elevated temperatures or during biofilm formation might be one of the adaptive responses of marine bacteria to environmental cues.

  12. Biofilm Formation and Heat Stress Induce Pyomelanin Production in Deep-Sea Pseudoalteromonas sp. SM9913

    Directory of Open Access Journals (Sweden)

    Zhenshun Zeng

    2017-09-01

    Full Text Available Pseudoalteromonas is an important bacterial genus present in various marine habitats. Many strains of this genus are found to be surface colonizers on marine eukaryotes and produce a wide range of pigments. However, the exact physiological role and mechanism of pigmentation were less studied. Pseudoalteromonas sp. SM9913 (SM9913, an non-pigmented strain isolated from the deep-sea sediment, formed attached biofilm at the solid–liquid interface and pellicles at the liquid–air interface at a wide range of temperatures. Lower temperatures and lower nutrient levels promoted the formation of attached biofilm, while higher nutrient levels promoted pellicle formation of SM9913. Notably, after prolonged incubation at higher temperatures growing planktonically or at the later stage of the biofilm formation, we found that SM9913 released a brownish pigment. By comparing the protein profile at different temperatures followed by qRT-PCR, we found that the production of pigment at higher temperatures was due to the induction of melA gene which is responsible for the synthesis of homogentisic acid (HGA. The auto-oxidation of HGA can lead to the formation of pyomelanin, which has been shown in other bacteria. Fourier Transform Infrared Spectrometer analysis confirmed that the pigment produced in SM9913 was pyomelanin-like compound. Furthermore, we demonstrated that, during heat stress and during biofilm formation, the induction level of melA gene was significantly higher than that of the hmgA gene which is responsible for the degradation of HGA in the L-tyrosine catabolism pathway. Collectively, our results suggest that the production of pyomelanin of SM9913 at elevated temperatures or during biofilm formation might be one of the adaptive responses of marine bacteria to environmental cues.

  13. Visible-Light-Induced Nickel-Catalyzed Negishi Cross-Couplings by Exogenous-Photosensitizer-Free Photocatalysis.

    Science.gov (United States)

    Abdiaj, Irini; Fontana, Alberto; Gomez, M Victoria; de la Hoz, Antonio; Alcázar, Jesús

    2018-03-22

    The merging of photoredox and transition-metal catalysis has become one of the most attractive approaches for carbon-carbon bond formation. Such reactions require the use of two organo-transition-metal species, one of which acts as a photosensitizer and the other one as a cross-coupling catalyst. We report herein an exogenous-photosensitizer-free photocatalytic process for the formation of carbon-carbon bonds by direct acceleration of the well-known nickel-catalyzed Negishi cross-coupling that is based on the use of two naturally abundant metals. This finding will open new avenues in cross-coupling chemistry that involve the direct visible-light absorption of organometallic catalytic complexes. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Biofilm Risks

    DEFF Research Database (Denmark)

    Wirtanen, Gun Linnea; Salo, Satu

    2016-01-01

    This chapter on biofilm risks deals with biofilm formation of pathogenic microbes, sampling and detection methods, biofilm removal, and prevention of biofilm formation. Several common pathogens produce sticky and/or slimy structures in which the cells are embedded, that is, biofilms, on various...... surfaces in food processing. Biofilms of common foodborne pathogens are reviewed. The issue of persistent and nonpersistent microbial contamination in food processing is also discussed. It has been shown that biofilms can be difficult to remove and can thus cause severe disinfection and cleaning problems...... in food factories. In the prevention of biofilm formation microbial control in process lines should both limit the number of microbes on surfaces and reduce microbial activity in the process. Thus the hygienic design of process equipment and process lines is important in improving the process hygiene...

  15. Combination of exogenous cell transplantation and 5-HT4 receptor agonism induce endogenous enteric neural crest-derived cells in a rat hypoganglionosis model.

    Science.gov (United States)

    Yu, Hui; Zheng, Bai-Jun; Pan, Wei-Kang; Wang, Huai-Jie; Xie, Chong; Zhao, Yu-Ying; Chen, Xin-Lin; Liu, Yong; Gao, Ya

    2017-02-01

    Enteric neural crest-derived cells (ENCCs) can migrate into endogenous ganglia and differentiate into progeny cells, and have even partially rescued bowel function; however, poor reliability and limited functional recovery after ENCC transplantation have yet to be addressed. Here, we investigated the induction of endogenous ENCCs by combining exogenous ENCC transplantation with a 5-HT 4 receptor agonist mosapride in a rat model of hypoganglionosis, established by benzalkonium chloride treatment. ENCCs, isolated from the gut of newborn rats, were labeled with a lentiviral eGFP reporter. ENCCs and rats were treated with the 5-HT 4 receptor agonist/antagonist. The labeled ENCCs were then transplanted into the muscular layer of benzalkonium chloride-treated colons. At given days post-intervention, colonic tissue samples were removed for histological analysis. ENCCs and neurons were detected by eGFP expression and immunoreactivity to p75 NTR and peripherin, respectively. eGFP-positive ENCCs and neurons could survive and maintain levels of fluorescence after transplantation. With longer times post-intervention, the number of peripherin-positive cells gradually increased in all groups. Significantly more peripherin-positive cells were found following ENCCs plus mosapride treatment, compared with the other groups. These results show that exogenous ENCCs combined with the 5-HT 4 receptor agonist effectively induced endogenous ENCCs proliferation and differentiation in a rat hypoganglionosis model. Copyright © 2016 Elsevier Inc. All rights reserved.

  16. Probiotic Lactobacillus sp. inhibit growth, biofilm formation and gene expression of caries-inducing Streptococcus mutans.

    Science.gov (United States)

    Wasfi, Reham; Abd El-Rahman, Ola A; Zafer, Mai M; Ashour, Hossam M

    2018-03-01

    Streptococcus mutans contributes significantly to dental caries, which arises from homoeostasic imbalance between host and microbiota. We hypothesized that Lactobacillus sp. inhibits growth, biofilm formation and gene expression of Streptococcus mutans. Antibacterial (agar diffusion method) and antibiofilm (crystal violet assay) characteristics of probiotic Lactobacillus sp. against Streptococcus mutans (ATCC 25175) were evaluated. We investigated whether Lactobacillus casei (ATCC 393), Lactobacillus reuteri (ATCC 23272), Lactobacillus plantarum (ATCC 14917) or Lactobacillus salivarius (ATCC 11741) inhibit expression of Streptococcus mutans genes involved in biofilm formation, quorum sensing or stress survival using quantitative real-time polymerase chain reaction (qPCR). Growth changes (OD600) in the presence of pH-neutralized, catalase-treated or trypsin-treated Lactobacillus sp. supernatants were assessed to identify roles of organic acids, peroxides and bacteriocin. Susceptibility testing indicated antibacterial (pH-dependent) and antibiofilm activities of Lactobacillus sp. against Streptococcus mutans. Scanning electron microscopy revealed reduction in microcolony formation and exopolysaccharide structural changes. Of the oral normal flora, L. salivarius exhibited the highest antibiofilm and peroxide-dependent antimicrobial activities. All biofilm-forming cells treated with Lactobacillus sp. supernatants showed reduced expression of genes involved in exopolysaccharide production, acid tolerance and quorum sensing. Thus, Lactobacillus sp. can inhibit tooth decay by limiting growth and virulence properties of Streptococcus mutans. © 2018 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine.

  17. Salmonella biofilms

    NARCIS (Netherlands)

    Castelijn, G.A.A.

    2013-01-01

    Biofilm formation by Salmonellaspp. is a problem in the food industry, since biofilms may act as a persistent source of product contamination. Therefore the aim of this study was to obtain more insight in the processes involved and the factors contributing to Salmonellabiofilm

  18. Infusion of exogenous cholecystokinin-8, gastrin releasing peptide-29 and their combination reduce body weight in diet-induced obese male rats.

    Science.gov (United States)

    Mhalhal, Thaer R; Washington, Martha C; Newman, Kayla; Heath, John C; Sayegh, Ayman I

    2017-02-01

    We hypothesized that exogenous gastrin releasing peptide-29 (GRP-29), cholecystokinin-8 (CCK-8) and their combination reduce body weight (BW). To test this hypothesis, BW was measured in four groups of diet-induced obese (DIO) male rats infused in the aorta (close to the junctions of the celiac and cranial mesenteric arteries) with saline, CCK-8 (0.5 nmol/kg), GRP-29 (0.5 nmol/kg) and CCK-8+GRP-29 (0.5 nmol/kg each) once daily for a total of 23 days. We found that CCK-8, GRP-29 and CCK-8+GRP-29 reduce BW relative to saline control. In conclusion, CCK-8, GRP-29 and their combination reduce BW in the DIO rat model. If infused near their gastrointestinal sites of action CCK-8, GRP-29 and their combination may have a role in regulating BW. Published by Elsevier Ltd.

  19. Exploring the molecular mechanisms underlying the potentiation of exogenous growth hormone on alcohol-induced fatty liver diseases in mice

    Directory of Open Access Journals (Sweden)

    Tian Ya-ping

    2010-11-01

    Full Text Available Abstract Background Growth hormone (GH is an essential regulator of intrahepatic lipid metabolism by activating multiple complex hepatic signaling cascades. Here, we examined whether chronic exogenous GH administration (via gene therapy could ameliorate liver steatosis in animal models of alcoholic fatty liver disease (AFLD and explored the underlying molecular mechanisms. Methods Male C57BL/6J mice were fed either an alcohol or a control liquid diet with or without GH therapy for 6 weeks. Biochemical parameters, liver histology, oxidative stress markers, and serum high molecular weight (HMW adiponectin were measured. Quantitative real-time PCR and western blotting were also conducted to determine the underlying molecular mechanism. Results Serum HMW adiponectin levels were significantly higher in the GH1-treated control group than in the control group (3.98 ± 0.71 μg/mL vs. 3.07 ± 0.55 μg/mL; P P P P P Conclusions GH therapy had positive effects on AFLD and may offer a promising approach to prevent or treat AFLD. These beneficial effects of GH on AFLD were achieved through the activation of the hepatic adiponectin-SIRT1-AMPK and PPARα-AMPK signaling systems.

  20. The Icsbp locus is a common proviral insertion site in mature B-cell lymphomas/plasmacytomas induced by exogenous murine leukemia virus

    International Nuclear Information System (INIS)

    Ma Shiliang; Sorensen, Annette Balle; Kunder, Sandra; Sorensen, Karina Dalsgaard; Quintanilla-Martinez, Leticia; Morris, David W.; Schmidt, Joerg; Pedersen, Finn Skou

    2006-01-01

    ICSBP (interferon consensus sequence binding protein)/IRF8 (interferon regulatory factor 8) is an interferon gamma-inducible transcription factor expressed predominantly in hematopoietic cells, and down-regulation of this factor has been observed in chronic myelogenous leukemia and acute myeloid leukemia in man. By screening about 1200 murine leukemia virus (MLV)-induced lymphomas, we found proviral insertions at the Icsbp locus in 14 tumors, 13 of which were mature B-cell lymphomas or plasmacytomas. Only one was a T-cell lymphoma, although such tumors constituted about half of the samples screened. This indicates that the Icsbp locus can play a specific role in the development of mature B-lineage malignancies. Two proviral insertions in the last Icsbp exon were found to act by a poly(A)-insertion mechanism. The remaining insertions were found within or outside Icsbp. Since our results showed expression of Icsbp RNA and protein in all end-stage tumor samples, a simple tumor suppressor function of ICSBP is not likely. Interestingly, proviral insertions at Icsbp have not been reported from previous extensive screenings of mature B-cell lymphomas induced by endogenous MLVs. We propose that ICSBP might be involved in an early modulation of an immune response to exogenous MLVs that might also play a role in proliferation of the mature B-cell lymphomas

  1. Apolipoprotein CIII overexpression exacerbates diet-induced obesity due to adipose tissue higher exogenous lipid uptake and retention and lower lipolysis rates.

    Science.gov (United States)

    Raposo, Helena F; Paiva, Adriene A; Kato, Larissa S; de Oliveira, Helena C F

    2015-01-01

    Hypertriglyceridemia is a common type of dyslipidemia found in obesity. However, it is not established whether primary hyperlipidemia can predispose to obesity. Evidences have suggested that proteins primarily related to plasma lipoprotein transport, such as apolipoprotein (apo) CIII and E, may significantly affect the process of body fat accumulation. We have previously observed an increased adiposity in response to a high fat diet (HFD) in mice overexpressing apoCIII. Here, we examined the potential mechanisms involved in this exacerbated response of apoCIII mice to the HFD. We measured body energy balance, tissue capacity to store exogenous lipids, lipogenesis and lipolysis rates in non-transgenic and apoCIII overexpressing mice fed a HFD during two months. Food intake, fat excretion and whole body CO2 production were similar in both groups. However, the adipose tissue mass (45 %) and leptin plasma levels (2-fold) were significantly greater in apoCIII mice. Lipogenesis rates were similar, while exogenous lipid retention was increased in perigonadal (2-fold) and brown adipose tissues (40 %) of apoCIII mice. In addition, adipocyte basal lipolysis (55 %) and in vivo lipolysis index (30 %) were significantly decreased in apoCIII mice. A fat tolerance test evidenced delayed plasma triglyceride clearance and greater transient availability of non-esterified fatty acids (NEFA) during the post-prandial state in the apoCIII mice plasma. Thus, apoCIII overexpression resulted in increased NEFA availability to adipose uptake and decreased adipocyte lipolysis, favoring lipid enlargement of adipose depots. We propose that plasma apoCIII levels represent a new risk factor for diet-induced obesity.

  2. Plants as Biofactories: Postharvest Stress-Induced Accumulation of Phenolic Compounds and Glucosinolates in Broccoli Subjected to Wounding Stress and Exogenous Phytohormones

    Science.gov (United States)

    Villarreal-García, Daniel; Nair, Vimal; Cisneros-Zevallos, Luis; Jacobo-Velázquez, Daniel A.

    2016-01-01

    Broccoli contains high levels of bioactive molecules and is considered a functional food. In this study, postharvest treatments to enhance the concentration of glucosinolates and phenolic compounds were evaluated. Broccoli whole heads were wounded to obtain florets and wounded florets (florets cut into four even pieces) and stored for 24 h at 20 °C with or without exogenous ethylene (ET, 1000 ppm) or methyl jasmonate (MeJA, 250 ppm). Whole heads were used as a control for wounding treatments. Regarding glucosinolate accumulation, ET selectively induced the 4-hydroxylation of glucobrassicin in whole heads, resulting in ∼223% higher 4-hydroxyglucobrassicin than time 0 h samples. Additionally, glucoraphanin was increased by ∼53% in whole heads treated with ET, while neoglucobrassicin was greatly accumulated in wounded florets treated with ET or MeJA, showing increases of ∼193 and ∼286%, respectively. On the other hand, although only whole heads stored without phytohormones showed higher concentrations of phenolic compounds, which was reflected in ∼33, ∼30, and ∼46% higher levels of 1,2,2-trisinapoylgentiobose, 1,2-diferulolylgentiobiose, and 1,2-disinapoyl-2-ferulolylgentiobiose, respectively; broccoli florets stored under air control conditions showed enhanced concentrations of 3-O-caffeoylquinic acid, 1,2-disinapoylgentiobiose, and 1,2-disinapoyl-2-ferulolylgentiobiose (∼22, ∼185, and ∼65% more, respectively). Furthermore, exogenous ET and MeJA impeded individual phenolics accumulation. Results allowed the elucidation of simple and effective postharvest treatment to enhance the content of individual glucosinolates and phenolic compounds in broccoli. The stressed-broccoli tissue could be subjected to downstream processing in order to extract and purify bioactive molecules with applications in the dietary supplements, agrochemical and cosmetics markets. PMID:26904036

  3. Plants as biofactories: Postharvest Stress-Induced Accumulation of Phenolic Compounds and Glucosinolates in Broccoli Subjected to Wounding Stress and Exogenous Phytohormones

    Directory of Open Access Journals (Sweden)

    Daniel eVillarreal-García

    2016-02-01

    Full Text Available Broccoli contains high levels of bioactive molecules and is considered a functional food. In this study, postharvest treatments to enhance the concentration of glucosinolates and phenolic compounds were evaluated. Broccoli whole heads were wounded to obtain florets and wounded florets (florets cut into four even pieces and stored for 24 h at 20 ºC with or without exogenous ethylene (ET, 1000 ppm or methyl jasmonate (MeJA, 250 ppm. Whole heads were used as a control for wounding treatments. Regarding glucosinolate accumulation, ET selectively induced the 4-hydroxylation of glucobrassicin in whole heads, resulting in ~223% higher 4-hydroxyglucobrassicin than time 0 h samples. Additionally, glucoraphanin was increased by ~53% in whole heads treated with ET, while neoglucobrassicin was greatly accumulated in wounded florets treated with ET or MeJA, showing increases of ~193% and ~286%, respectively. On the other hand, although only whole heads stored without phytohormones showed higher concentrations of phenolic compounds, which was reflected in ~33%, ~30%, and 46% higher levels of 1,2,2-trisinapoylgentiobose, 1,2-diferulolylgentiobiose, and 1,2-disinapoyl-2-ferulolylgentiobiose, respectively; broccoli florets stored under air control conditions showed enhanced concentrations of 3-O-caffeoylquinic acid, 1,2-disinapoylgentiobiose, and 1,2-disinapoyl-2-ferulolylgentiobiose (~22%, ~185%, and ~65% more, respectively. However, exogenous ET and MeJA impeded individual phenolics accumulation. Results allowed the elucidation of simple and effective postharvest treatment to enhance the content of individual glucosinolates and phenolic compounds in broccoli. The stressed-broccoli tissue could be subjected to downstream processing in order to extract and purify bioactive molecules with applications in the dietary supplements, agrochemical and cosmetics markets.

  4. Effects of exogenous ATM gene on mRNA expression of human telomerase reverse transcriptase in AT cells induced by irradiation

    International Nuclear Information System (INIS)

    Sheng Fangjun; Cao Jianping; Luo Jialin; Zhu Wei; Liu Fenju; Feng Shuang; Song Jianyuan; Li Chong

    2005-01-01

    The study is to observe effects of exogenous ATM gene on mRNA expression of hTERT (human telomerase reverse transcriptase) in fibroblast cells (AT5BIVA cells) from skin of Ataxia-telangiectasia (AT) patients and to study the regulation of ATM to hTERT. Using reverse transcription polymerase chain reaction (RT-PCR), mRNA expression of hTERT in AT, PEBS7-AT, ATM + -AT and GM cells irradiated with 0 and 3 Gy of 60 Co γ-rays were examined respectively. The difference of the mRNA expression of hTERT among AT, PEBS7-AT, ATM + -AT and GM cells were analyzed. Difference of the mRNA expression of hTERT between 0 Gy and 3 Gy groups was analyzed, too. The results showed that the mRNA expression of hTERT in GM cells was negative, but positive mRNA expression of hTERT in AT cells. The mRNA expression of hTERT in ATM + -AT cells decreased significantly (p 60 Co γ-rays, the mRNA expression of hTERT in GM cells was positive, and that in AT, PEBS7-AT, ATM + -AT cells was increased (p + -AT cells was lower than that in AT and PEBS7-AT cells respectively (p<0.05). It is postulated that exogenous ATM is able to downregulate the mRNA expression of hTERT in AT cells, ionizing radiation can induce the mRNA expression of hTERT in cells and telomerase anticipates the repair of damaged DNA. (authors)

  5. Biofilm Infections

    DEFF Research Database (Denmark)

    Bjarnsholt, Thomas; Jensen, Peter Østrup; Moser, Claus Ernst

    A still increasing interest and emphasis on the sessile bacterial lifestyle biofilms has been seen since it was realized that the vast majority of the total microbial biomass exists as biofilms. Aggregation of bacteria was first described by Leeuwenhoek in 1677, but only recently recognized...... as being important in chronic infection. In 1993 the American Society for Microbiology (ASM) recognized that the biofilm mode of growth was relevant to microbiology. This book covers both the evidence for biofilms in many chronic bacterial infections as well as the problems facing these infections...... such as diagnostics, pathogenesis, treatment regimes and in vitro and in vivo models for studying biofilms. This is the first scientific book on biofilm infections, chapters written by the world leading scientist and clinicians. The intended audience of this book is scientists, teachers at university level as well...

  6. Microdose gonadotropin-releasing hormone agonist in the absence of exogenous gonadotropins is not sufficient to induce multiple follicle development.

    Science.gov (United States)

    Chung, Karine; Fogle, Robin; Bendikson, Kristin; Christenson, Kamilee; Paulson, Richard

    2011-01-01

    Because the effectiveness of the "microdose flare" stimulation protocol often is attributed to the dramatic endogenous gonadotropin release induced by the GnRH agonist, the aim of this study was to determine whether use of microdose GnRH agonist alone could induce multiple ovarian follicle development in normal responders. Based on these data, the duration of gonadotropin rise is approximately 24 to 48 hours and is too brief to sustain continued multiple follicle growth. Copyright © 2011 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

  7. Bacteriophages and Biofilms

    Directory of Open Access Journals (Sweden)

    David R. Harper

    2014-06-01

    Full Text Available Biofilms are an extremely common adaptation, allowing bacteria to colonize hostile environments. They present unique problems for antibiotics and biocides, both due to the nature of the extracellular matrix and to the presence within the biofilm of metabolically inactive persister cells. Such chemicals can be highly effective against planktonic bacterial cells, while being essentially ineffective against biofilms. By contrast, bacteriophages seem to have a greater ability to target this common form of bacterial growth. The high numbers of bacteria present within biofilms actually facilitate the action of bacteriophages by allowing rapid and efficient infection of the host and consequent amplification of the bacteriophage. Bacteriophages also have a number of properties that make biofilms susceptible to their action. They are known to produce (or to be able to induce enzymes that degrade the extracellular matrix. They are also able to infect persister cells, remaining dormant within them, but re-activating when they become metabolically active. Some cultured biofilms also seem better able to support the replication of bacteriophages than comparable planktonic systems. It is perhaps unsurprising that bacteriophages, as the natural predators of bacteria, have the ability to target this common form of bacterial life.

  8. Divergent effects of endogenous and exogenous glucocorticoid-induced leucine zipper in animal models of inflammation and arthritis

    NARCIS (Netherlands)

    Ngo, Devi; Beaulieu, Elaine; Gu, Ran; Leaney, Alexandra; Santos, Leilani; Fan, Huapeng; Yang, Yuanhang; Kao, Wenping; Xu, Jiake; Escriou, Virginie; Loiler, Scott; Vervoordeldonk, Margriet J.; Morand, Eric F.

    2013-01-01

    Glucocorticoid-induced leucine zipper (GILZ) has effects on inflammatory pathways that suggest it to be a key inhibitory regulator of the immune system, and its expression is exquisitely sensitive to induction by glucocorticoids. We undertook this study to test our hypothesis that GILZ deficiency

  9. Mechanism of protection of bystander cells by exogenous carbon monoxide: Impaired response to damage signal of radiation-induced bystander effect

    International Nuclear Information System (INIS)

    Han, W.; Yu, K.N.; Wu, L.J.; Wu, Y.C.; Wang, H.Z.

    2011-01-01

    A protective effect of exogenous carbon monoxide (CO), generated by CO releasing molecule ticarbonyldichlororuthenium (II) dimer (CORM-2), on the bystander cells from the toxicity of radiation-induced bystander effect (RIBE) was revealed in our previous study. In the present work, a possible mechanism of this CO effect was investigated. The results from medium transfer experiments showed that α-particle irradiated Chinese hamster ovary (CHO) cells would release nitric oxide (NO), which was detected with specific NO fluorescence probe, to induce p53 binding protein 1 (BP1) formation in the cell population receiving the medium, and the release peak was found to be at 1 h post irradiation. Treating the irradiated or bystander cells separately with CO (CORM-2) demonstrated that CO was effective in the bystander cells but not the irradiated cells. Measurements of NO production and release with a specific NO fluorescence probe also showed that CO treatment did not affect the production and release of NO by irradiated cells. Protection of CO on cells to peroxynitrite, an oxidizing free radical from NO, suggested that CO might protect bystander cells via impaired response of bystander cells to NO, a RIBE signal in our research system.

  10. Modulation of salt (NaCl)-induced effects on oil composition and fatty acid profile of sunflower (Helianthus annuus L.) by exogenous application of salicylic acid.

    Science.gov (United States)

    Noreen, Sibgha; Ashraf, Muhammad

    2010-12-01

    Salicylic acid (SA) is a potential endogenous plant hormone that plays an important role in plant growth and development. Since sunflower yield and its seed oil yield are adversely affected by salinity, in this study the role of SA in modulating salt (NaCl)-induced effects on various yield and oil characteristics of sunflower was investigated. For this purpose a greenhouse experiment comprising two sunflower hybrid lines (Hysun-33 and SF-187), two NaCl levels (0 and 120 mmol L(-1)) and four SA levels (0, 100, 200 and 300 mg L(-1)) was conducted. Salt stress markedly reduced yield, oil content, linoleic acid and δ-tocopherol in both sunflower lines, while it increased linolenic acid, palmitic acid, stearic acid and α- and γ-tocopherols. However, increasing levels of foliar-applied SA resulted in improved achene yield and hundred-achene weight in both lines. Foliar-applied SA caused a significant decrease in oil stearic acid and α- and γ-tocopherols in both lines under non-saline and saline conditions. Salt-induced harmful effects on achene yield and oil characteristics of sunflower could be alleviated by exogenous application of SA. High doses of SA caused a marked increase in sunflower achene oil content as well as some key fatty acids. Copyright © 2010 Society of Chemical Industry.

  11. Resistance to BmNPV via overexpression of an exogenous gene controlled by an inducible promoter and enhancer in transgenic silkworm, Bombyx mori.

    Directory of Open Access Journals (Sweden)

    Liang Jiang

    Full Text Available The hycu-ep32 gene of Hyphantria cunea NPV can inhibit Bombyx mori nucleopolyhedrovirus (BmNPV multiplication in co-infected cells, but it is not known whether the overexpression of the hycu-ep32 gene has an antiviral effect in the silkworm, Bombyx mori. Thus, we constructed four transgenic vectors, which were under the control of the 39 K promoter of BmNPV (39 KP, Bombyx mori A4 promoter (A4P, hr3 enhancer of BmNPV combined with 39 KP, and hr3 combined with A4P. Transgenic lines were created via embryo microinjection using practical diapause silkworm. qPCR revealed that the expression level of hycu-ep32 could be induced effectively after BmNPV infection in transgenic lines where hycu-ep32 was controlled by hr3 combined with 39 KP (i.e., HEKG. After oral inoculation of BmNPV with 3 × 10(5 occlusion bodies per third instar, the mortality with HEKG-B was approximately 30% lower compared with the non-transgenic line. The economic characteristics of the transgenic lines remained unchanged. These results suggest that overexpression of an exogenous antiviral gene controlled by an inducible promoter and enhancer is a feasible method for breeding silkworms with a high antiviral capacity.

  12. Mechanism of protection of bystander cells by exogenous carbon monoxide: Impaired response to damage signal of radiation-induced bystander effect

    Energy Technology Data Exchange (ETDEWEB)

    Han, W. [Department of Physics and Materials Science, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon Tong, Kowloon (Hong Kong); Center of Medical Physics and Technology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031 (China); Yu, K.N., E-mail: peter.yu@cityu.edu.hk [Department of Physics and Materials Science, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon Tong, Kowloon (Hong Kong); Wu, L.J. [Center of Medical Physics and Technology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031 (China); Wu, Y.C. [Center of Medical Physics and Technology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031 (China); School of Nuclear Science and Technology, University of Science and Technology of China, Hefei 230029 (China); Wang, H.Z. [Center of Medical Physics and Technology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031 (China)

    2011-05-10

    A protective effect of exogenous carbon monoxide (CO), generated by CO releasing molecule ticarbonyldichlororuthenium (II) dimer (CORM-2), on the bystander cells from the toxicity of radiation-induced bystander effect (RIBE) was revealed in our previous study. In the present work, a possible mechanism of this CO effect was investigated. The results from medium transfer experiments showed that {alpha}-particle irradiated Chinese hamster ovary (CHO) cells would release nitric oxide (NO), which was detected with specific NO fluorescence probe, to induce p53 binding protein 1 (BP1) formation in the cell population receiving the medium, and the release peak was found to be at 1 h post irradiation. Treating the irradiated or bystander cells separately with CO (CORM-2) demonstrated that CO was effective in the bystander cells but not the irradiated cells. Measurements of NO production and release with a specific NO fluorescence probe also showed that CO treatment did not affect the production and release of NO by irradiated cells. Protection of CO on cells to peroxynitrite, an oxidizing free radical from NO, suggested that CO might protect bystander cells via impaired response of bystander cells to NO, a RIBE signal in our research system.

  13. Pre-administration of safe exogenous substance minimizes radiation induced bone-marrow aplsia which may otherwise lead to hematopoietic disaster

    International Nuclear Information System (INIS)

    Gupta, Manju Lata; Verma, Savita; Ranjan, Rajiv

    2014-01-01

    Radiation induces injuries to biological system primarily by producing free radicals and also by directly interacting with cellular entities. In irradiated animals hematopoietic system gets severely affected leading to inactive microenvironment, damaged blood vessels and non functional endothelial cells of the marrow. Vascular damage inhibits the efficacy of stem cells to proliferate and differentiate. Release of pro-inflammatory cytokines and activation of fibroblast further contribute to the development of radiation-induced fibrosis. Various findings have revealed the occurrence of radiation induced aplasia and vascular damage cause large number of RBCs occupying the space and intrusion of fibrotic cells in the marrow of irradiated mice. Administration of effective radioprotective agents prior to irradiation has been amply reported for significant decline in the grade of vascular damage and inclusion of marrow fibrous tissues in these animals. In addition the formulations have also shown the presence stem cell population which is efficient to proliferate, differentiate and ultimately enrich bone marrow cellularity within 25-40 days depending on type of radiation and its dose and dose rate. Protection to bone marrow is multi-factorial phenomenon out of which inhibition of radiation induced free radical generation has been recognized as the key factor but essentially not the lone one. Protection to colony forming ability of bone marrow is also critically important which occurs mainly due to DNA protection and up-regulation of repair pathways. Preservation of microenvironment for providing stem cells to remain functional is lately reported as equally prominent factor. Our studies on a combination of two compounds of natural origin, administered to lethally irradiated animals have shown recovery in stem/precursor cells of all hematopoietic lineages. Major entities related to hematopoietic system were found nearly 90% recovered within 30 days. Current talk is focused

  14. Exogenous GA3 Application Enhances Xylem Development and Induces the Expression of Secondary Wall Biosynthesis Related Genes in Betula platyphylla

    Directory of Open Access Journals (Sweden)

    Huiyan Guo

    2015-09-01

    Full Text Available Gibberellin (GA is a key signal molecule inducing differentiation of tracheary elements, fibers, and xylogenesis. However the molecular mechanisms underlying the effect of GA on xylem elongation and secondary wall development in tree species remain to be determined. In this study, Betula platyphylla (birch seeds were treated with 300 ppm GA3 and/or 300 ppm paclobutrazol (PAC, seed germination was recorded, and transverse sections of hypocotyls were stained with toluidine blue; the two-month-old seedlings were treated with 50 μM GA3 and/or 50 μM PAC, transverse sections of seedling stems were stained using phloroglucinol–HCl, and secondary wall biosynthesis related genes expression was analyzed by real-time quantitative PCR. Results indicated that germination percentage, energy and time of seeds, hypocotyl height and seedling fresh weight were enhanced by GA3, and reduced by PAC; the xylem development was wider in GA3-treated plants than in the control; the expression of NAC and MYB transcription factors, CESA, PAL, and GA oxidase was up-regulated during GA3 treatment, suggesting their role in GA3-induced xylem development in the birch. Our results suggest that GA3 induces the expression of secondary wall biosynthesis related genes to trigger xylogenesis in the birch plants.

  15. Introduction of Exogenous HSV-TK Suicide Gene Increases Safety of Keratinocyte-Derived Induced Pluripotent Stem Cells by Providing Genetic “Emergency Exit” Switch

    Directory of Open Access Journals (Sweden)

    Maciej Sułkowski

    2018-01-01

    Full Text Available Since their invention in 2006, induced Pluripotent Stem (iPS cells remain a great promise for regenerative medicine circumventing the ethical issues linked to Embryonic Stem (ES cell research. iPS cells can be generated in a patient-specific manner as an unlimited source of various cell types for in vitro drug screening, developmental biology studies and regenerative use. Having the capacity of differentiating into the cells of all three primary germ layers, iPS cells have high potential to form teratoma tumors. This remains their main disadvantage and hazard which, until resolved, prevents utilization of iPS cells in clinic. Here, we present an approach for increasing iPS cells safety by introducing genetic modification—exogenous suicide gene Herpes Simplex Virus Thymidine Kinase (HSV-TK. Its expression results in specific vulnerability of genetically modified cells to prodrug—ganciclovir (GCV. We show that HSV-TK expressing cells can be eradicated both in vitro and in vivo with high specificity and efficiency with low doses of GCV. Described strategy increases iPS cells safety for future clinical applications by generating “emergency exit” switch allowing eradication of transplanted cells in case of their malfunction.

  16. Introduction of Exogenous HSV-TK Suicide Gene Increases Safety of Keratinocyte-Derived Induced Pluripotent Stem Cells by Providing Genetic "Emergency Exit" Switch.

    Science.gov (United States)

    Sułkowski, Maciej; Konieczny, Paweł; Chlebanowska, Paula; Majka, Marcin

    2018-01-09

    Since their invention in 2006, induced Pluripotent Stem (iPS) cells remain a great promise for regenerative medicine circumventing the ethical issues linked to Embryonic Stem (ES) cell research. iPS cells can be generated in a patient-specific manner as an unlimited source of various cell types for in vitro drug screening, developmental biology studies and regenerative use. Having the capacity of differentiating into the cells of all three primary germ layers, iPS cells have high potential to form teratoma tumors. This remains their main disadvantage and hazard which, until resolved, prevents utilization of iPS cells in clinic. Here, we present an approach for increasing iPS cells safety by introducing genetic modification-exogenous suicide gene Herpes Simplex Virus Thymidine Kinase ( HSV-TK ). Its expression results in specific vulnerability of genetically modified cells to prodrug-ganciclovir (GCV). We show that HSV-TK expressing cells can be eradicated both in vitro and in vivo with high specificity and efficiency with low doses of GCV. Described strategy increases iPS cells safety for future clinical applications by generating "emergency exit" switch allowing eradication of transplanted cells in case of their malfunction.

  17. Inhibition of Candida albicans Biofilm Formation by the Synthetic Lactoferricin Derived Peptide hLF1-11

    Science.gov (United States)

    Morici, Paola; Fais, Roberta; Rizzato, Cosmeri

    2016-01-01

    The aim of this study was to evaluate the in vitro activity of the synthetic peptide hLF1-11 against biofilm produced by clinical isolates of Candida albicans with different fluconazole susceptibility. The antibiofilm activity of the peptide hLF1-11 was assessed in terms of reduction of biofilm cellular density, metabolic activity and sessile cell viability. The extent of morphogenesis in hLF1-11 treated and untreated biofilms was also investigated microscopically. Transcription levels of genes related to cell adhesion, hyphal development and extracellular matrix production were analysed by qRT-PCR in hLF1-11 treated and untreated biofilms. Exogenous dibutyryl-cAMP (db-cAMP) was used to rescue morphogenesis in cells exposed to the peptide. The results revealed that hLF1-11 exhibited an inhibitory effect on biofilm formation by all C. albicans isolates tested in a dose-dependent manner, regardless of their fluconazole susceptibility. Visual inspection of treated or untreated biofilm cells with an inverted microscope revealed a significant reduction in hyphal formation by hLF1-11 treated cells, as early as 3 hours of incubation. Moreover, hLF1-11 showed a reduced activity on preadherent cells. hLF1-11 induced the down-regulation of biofilm and hyphal-associated genes, which were predominantly regulated via the Ras1-cAMP-Efg1 pathway. Indeed, exogenous db-cAMP restored morphogenesis in hLF1-11 treated cells. The hLF1-11 peptide significantly inhibited biofilm formation by C. albicans mainly at early stages, interfering with biofilm cellular density and metabolic activity, and affected morphogenesis through the Ras1-cAMP-Efg1 pathway. Our findings provide the first evidence that hLF1-11 could represent a potential candidate for the prevention of biofilm formation by C. albicans. PMID:27902776

  18. Inhibition of Candida albicans Biofilm Formation by the Synthetic Lactoferricin Derived Peptide hLF1-11.

    Directory of Open Access Journals (Sweden)

    Paola Morici

    Full Text Available The aim of this study was to evaluate the in vitro activity of the synthetic peptide hLF1-11 against biofilm produced by clinical isolates of Candida albicans with different fluconazole susceptibility. The antibiofilm activity of the peptide hLF1-11 was assessed in terms of reduction of biofilm cellular density, metabolic activity and sessile cell viability. The extent of morphogenesis in hLF1-11 treated and untreated biofilms was also investigated microscopically. Transcription levels of genes related to cell adhesion, hyphal development and extracellular matrix production were analysed by qRT-PCR in hLF1-11 treated and untreated biofilms. Exogenous dibutyryl-cAMP (db-cAMP was used to rescue morphogenesis in cells exposed to the peptide. The results revealed that hLF1-11 exhibited an inhibitory effect on biofilm formation by all C. albicans isolates tested in a dose-dependent manner, regardless of their fluconazole susceptibility. Visual inspection of treated or untreated biofilm cells with an inverted microscope revealed a significant reduction in hyphal formation by hLF1-11 treated cells, as early as 3 hours of incubation. Moreover, hLF1-11 showed a reduced activity on preadherent cells. hLF1-11 induced the down-regulation of biofilm and hyphal-associated genes, which were predominantly regulated via the Ras1-cAMP-Efg1 pathway. Indeed, exogenous db-cAMP restored morphogenesis in hLF1-11 treated cells. The hLF1-11 peptide significantly inhibited biofilm formation by C. albicans mainly at early stages, interfering with biofilm cellular density and metabolic activity, and affected morphogenesis through the Ras1-cAMP-Efg1 pathway. Our findings provide the first evidence that hLF1-11 could represent a potential candidate for the prevention of biofilm formation by C. albicans.

  19. Extracellular DNA Shields against Aminoglycosides in Pseudomonas aeruginosa Biofilms

    DEFF Research Database (Denmark)

    Chiang, Wen-Chi; Nilsson, Martin; Jensen, Peter Østrup

    2013-01-01

    Within recent years, it has been established that extracellular DNA is a key constituent of the matrix of microbial biofilms. In addition, it has recently been demonstrated that DNA binds positively charged antimicrobials such as aminoglycosides and antimicrobial peptides. In the present study, we...... provide evidence that extracellular DNA shields against aminoglycosides in Pseudomonas aeruginosa biofilms. We show that exogenously supplemented DNA integrates into P. aeruginosa biofilms and increases their tolerance toward aminoglycosides. We provide evidence that biofilms formed by a DNA release......-deficient P. aeruginosa quorum-sensing mutant are more susceptible to aminoglycoside treatment than wild-type biofilms but become rescued from the detrimental action of aminoglycosides upon supplementation with exogenous DNA. Furthermore, we demonstrate that exposure to lysed polymorphonuclear leukocytes...

  20. Exogenous hydrogen sulfide (H2S protects alveolar growth in experimental O2-induced neonatal lung injury.

    Directory of Open Access Journals (Sweden)

    Arul Vadivel

    Full Text Available Bronchopulmonary dysplasia (BPD, the chronic lung disease of prematurity, remains a major health problem. BPD is characterized by impaired alveolar development and complicated by pulmonary hypertension (PHT. Currently there is no specific treatment for BPD. Hydrogen sulfide (H2S, carbon monoxide and nitric oxide (NO, belong to a class of endogenously synthesized gaseous molecules referred to as gasotransmitters. While inhaled NO is already used for the treatment of neonatal PHT and currently tested for the prevention of BPD, H2S has until recently been regarded exclusively as a toxic gas. Recent evidence suggests that endogenous H2S exerts beneficial biological effects, including cytoprotection and vasodilatation. We hypothesized that H2S preserves normal alveolar development and prevents PHT in experimental BPD.We took advantage of a recently described slow-releasing H2S donor, GYY4137 (morpholin-4-ium-4-methoxyphenyl(morpholino phosphinodithioate to study its lung protective potential in vitro and in vivo.In vitro, GYY4137 promoted capillary-like network formation, viability and reduced reactive oxygen species in hyperoxia-exposed human pulmonary artery endothelial cells. GYY4137 also protected mitochondrial function in alveolar epithelial cells. In vivo, GYY4137 preserved and restored normal alveolar growth in rat pups exposed from birth for 2 weeks to hyperoxia. GYY4137 also attenuated PHT as determined by improved pulmonary arterial acceleration time on echo-Doppler, pulmonary artery remodeling and right ventricular hypertrophy. GYY4137 also prevented pulmonary artery smooth muscle cell proliferation.H2S protects from impaired alveolar growth and PHT in experimental O2-induced lung injury. H2S warrants further investigation as a new therapeutic target for alveolar damage and PHT.

  1. Exogenous 5-aminolevulenic acid promotes seed germination in Elymus nutans against oxidative damage induced by cold stress.

    Directory of Open Access Journals (Sweden)

    Juanjuan Fu

    Full Text Available The protective effects of 5-aminolevulenic acid (ALA on germination of Elymus nutans Griseb. seeds under cold stress were investigated. Seeds of E. nutans (Damxung, DX and Zhengdao, ZD were pre-soaked with various concentrations (0, 0.1, 0.5, 1, 5, 10 and 25 mg l(-1 of ALA for 24 h before germination under cold stress (5°C. Seeds of ZD were more susceptible to cold stress than DX seeds. Both seeds treated with ALA at low concentrations (0.1-1 mg l(-1 had higher final germination percentage (FGP and dry weight at 5°C than non-ALA-treated seeds, whereas exposure to higher ALA concentrations (5-25 mg l(-1 brought about a dose dependent decrease. The highest FGP and dry weight of germinating seeds were obtained from seeds pre-soaked with 1 mg l(-1 ALA. After 5 d of cold stress, pretreatment with ALA provided significant protection against cold stress in the germinating seeds, significantly enhancing seed respiration rate and ATP synthesis. ALA pre-treatment also increased reduced glutathione (GSH, ascorbic acid (AsA, total glutathione, and total ascorbate concentrations, and the activities of superoxide dismutase (SOD, catalase (CAT, ascorbate peroxidase (APX and glutathione reductase (GR, whereas decreased the contents of malondialdehyde (MDA and hydrogen peroxide (H2O2, and superoxide radical (O2•- release in both germinating seeds under cold stress. In addition, application of ALA increased H+-ATPase activity and endogenous ALA concentration compared with cold stress alone. Results indicate that ALA considered as an endogenous plant growth regulator could effectively protect E. nutans seeds from cold-induced oxidative damage during germination without any adverse effect.

  2. Exogenous Methyl Jasmonate and Salicylic Acid Induce Subspecies-Specific Patterns of Glucosinolate Accumulation and Gene Expression in Brassica oleracea L.

    Science.gov (United States)

    Yi, Go-Eun; Robin, Arif Hasan Khan; Yang, Kiwoung; Park, Jong-In; Hwang, Byung Ho; Nou, Ill-Sup

    2016-10-24

    Glucosinolates have anti-carcinogenic properties. In the recent decades, the genetics of glucosinolate biosynthesis has been widely studied, however, the expression of specific genes involved in glucosinolate biosynthesis under exogenous phytohormone treatment has not been explored at the subspecies level in Brassica oleracea . Such data are vital for strategies aimed at selective exploitation of glucosinolate profiles. This study quantified the expression of 38 glucosinolate biosynthesis-related genes in three B. oleracea subspecies, namely cabbage, broccoli and kale, and catalogued associations between gene expression and increased contents of individual glucosinolates under methyl jasmonate (MeJA) and salicylic acid (SA) treatments. Glucosinolate accumulation and gene expression in response to phytohormone elicitation was subspecies specific. For instance, cabbage leaves showed enhanced accumulation of the aliphatic glucoiberin, progoitrin, sinigrin and indolic neoglucobrassicin under both MeJA and SA treatment. MeJA treatment induced strikingly higher accumulation of glucobrassicin (GBS) in cabbage and kale and of neoglucobrassicin (NGBS) in broccoli compared to controls. Notably higher expression of ST5a (Bol026200), CYP81F1 (Bol028913, Bol028914) and CYP81F4 genes was associated with significantly higher GBS accumulation under MeJA treatment compared to controls in all three subspecies. CYP81F4 genes, trans-activated by MYB34 genes, were expressed at remarkably high levels in all three subspecies under MeJA treatment, which also induced in higher indolic NGBS accumulation in all three subspecies. Remarkably higher expression of MYB28 (Bol036286), ST5b , ST5c , AOP2 , FMOGS-OX5 (Bol031350) and GSL-OH (Bol033373) was associated with much higher contents of aliphatic glucosinolates in kale leaves compared to the other two subspecies. The genes expressed highly could be utilized in strategies to selectively increase glucosinolate compounds in B. oleracea

  3. Biofilm Development

    DEFF Research Database (Denmark)

    Tolker-Nielsen, Tim

    2015-01-01

    During the past decade we have gained much knowledge about the molecular mechanisms that are involved in initiation and termination of biofilm formation. In many bacteria, these processes appear to occur in response to specific environmental cues and result in, respectively, induction or terminat......During the past decade we have gained much knowledge about the molecular mechanisms that are involved in initiation and termination of biofilm formation. In many bacteria, these processes appear to occur in response to specific environmental cues and result in, respectively, induction...... or termination of biofilm matrix production via the second messenger molecule c-di-GMP. In between initiation and termination of biofilm formation we have defined specific biofilm stages, but the currently available evidence suggests that these transitions are mainly governed by adaptive responses......, and not by specific genetic programs. It appears that biofilm formation can occur through multiple pathways and that the spatial structure of the biofilms is species dependent as well as dependent on environmental conditions. Bacterial subpopulations, e.g., motile and nonmotile subpopulations, can develop...

  4. Artificial biofilms establish the role of matrix interactions in staphylococcal biofilm assembly and disassembly

    Science.gov (United States)

    Stewart, Elizabeth J.; Ganesan, Mahesh; Younger, John G.; Solomon, Michael J.

    2015-01-01

    We demonstrate that the microstructural and mechanical properties of bacterial biofilms can be created through colloidal self-assembly of cells and polymers, and thereby link the complex material properties of biofilms to well understood colloidal and polymeric behaviors. This finding is applied to soften and disassemble staphylococcal biofilms through pH changes. Bacterial biofilms are viscoelastic, structured communities of cells encapsulated in an extracellular polymeric substance (EPS) comprised of polysaccharides, proteins, and DNA. Although the identity and abundance of EPS macromolecules are known, how these matrix materials interact with themselves and bacterial cells to generate biofilm morphology and mechanics is not understood. Here, we find that the colloidal self-assembly of Staphylococcus epidermidis RP62A cells and polysaccharides into viscoelastic biofilms is driven by thermodynamic phase instability of EPS. pH conditions that induce phase instability of chitosan produce artificial S. epidermidis biofilms whose mechanics match natural S. epidermidis biofilms. Furthermore, pH-induced solubilization of the matrix triggers disassembly in both artificial and natural S. epidermidis biofilms. This pH-induced disassembly occurs in biofilms formed by five additional staphylococcal strains, including three clinical isolates. Our findings suggest that colloidal self-assembly of cells and matrix polymers produces biofilm viscoelasticity and that biofilm control strategies can exploit this mechanism. PMID:26272750

  5. Exogenous vs. Endogenous Separation

    OpenAIRE

    Ramey, Garey

    2008-01-01

    This paper assesses how various approaches to modelling the separation margin a¤ect the ability of the Mortensen-Pissarides job matching model to explain key facts about the aggregate labor market. Allowing for realistic time variation in the separation rate, whether exogenous or endogenous, greatly in- creases the unemployment variability generated by the model. Speci…cations with exogenous separation rates, whether constant or time-varying, fail to pro- duce realistic volatility and prod...

  6. Induction of beta-lactamase production in Pseudomonas aeruginosa biofilm

    DEFF Research Database (Denmark)

    Giwercman, B; Jensen, E T; Høiby, N

    1991-01-01

    Imipenem induced high levels of beta-lactamase production in Pseudomonas aeruginosa biofilms. Piperacillin also induced beta-lactamase production in these biofilms but to a lesser degree. The combination of beta-lactamase production with other protective properties of the biofilm mode of growth c...... could be a major reason for the persistence of this sessile bacterium in chronic infections....

  7. Role of cerium oxide nanoparticle-induced autophagy as a safeguard to exogenous H2O2-mediated DNA damage in tobacco BY-2 cells.

    Science.gov (United States)

    Sadhu, Abhishek; Ghosh, Ilika; Moriyasu, Yuji; Mukherjee, Anita; Bandyopadhyay, Maumita

    2018-04-13

    The effect of cerium oxide nanoparticle (CeNP) in plants has elicited substantial controversy. While some investigators have reported that CeNP possesses antioxidant properties, others observed CeNP to induce reactive oxygen species (ROS). In spite of considerable research carried out on the effects of CeNP in metazoans, fundamental studies that can unveil its intracellular consequences linking ROS production, autophagy and DNA damage are lacking in plants. To elucidate the impact of CeNP within plant cells, tobacco BY-2 cells were treated with 10, 50 and 250 µg ml-1 CeNP (Ce10, Ce50 and Ce250), for 24 h. Results demonstrated concentration-dependent accumulation of Ca2+ and ROS at all CeNP treatment sets. However, significant DNA damage and alteration in antioxidant defence systems were noted prominently at Ce50 and Ce250. Moreover, Ce50 and Ce250 induced DNA damage, analysed by comet assay and DNA diffusion experiments, complied with the concomitant increase in ROS. Furthermore, to evaluate the antioxidant property of CeNP, treated cells were washed after 24 h (to minimise CeNP interference) and challenged with H2O2 for 3 h. Ce10 did not induce genotoxicity and H2O2 exposure to Ce10-treated cells showed lesser DNA breakage than cells treated with H2O2 only. Interestingly, Ce10 provided better protection over N-acetyl-L-cysteine against exogenous H2O2 in BY-2 cells. CeNP exposure to transgenic BY-2 cells expressing GFP-Atg8 fusion protein exhibited formation of autophagosomes at Ce10. Application of vacuolar protease inhibitor E-64c and fluorescent basic dye acridine orange, further demonstrated accumulation of particulate matters in the vacuole and occurrence of acidic compartments, the autophagolysosomes, respectively. BY-2 cells co-treated with CeNP and autophagy inhibitor 3-methyladenine exhibited increased DNA damage in Ce10 and cell death at all assessed treatment sets. Thus, current results substantiate an alternative autophagy-mediated, antioxidant and

  8. Wound biofilms: lessons learned from oral biofilms

    OpenAIRE

    Mancl, Kimberly A.; Kirsner, Robert S.; Ajdic, Dragana

    2013-01-01

    Biofilms play an important role in the development and pathogenesis of many chronic infections. Oral biofilms, more commonly known as dental plaque,are a primary cause of oral diseases including caries, gingivitis and periodontitis. Oral biofilms are commonly studied as model biofilm systems as they are easily accessible, thus biofilm research in oral diseases is advanced with details of biofilm formation and bacterial interactions being well-elucidated. In contrast, wound research has relati...

  9. Independent effects of endogenous and exogenous attention in touch.

    Science.gov (United States)

    Jones, Alexander; Forster, Bettina

    2013-12-01

    Endogenous and exogenous attention in touch have typically been investigated separately. Here we use a double-cueing paradigm manipulating both types of orienting in each trial. Bilateral endogenous cues induced long-lasting facilitation of endogenous attention up to 2 s. However, the exogenous cue only elicited an effect at short intervals. Our results favour a supramodal account of attention and this study provides new insight into how endogenous and exogenous attention operates in the tactile modality.

  10. Exogenous melatonin suppresses dark-induced leaf senescence by activating the superoxide dismutase-catalase antioxidant pathway and down-regulating chlorophyll degradation in excised leaves of perennial ryegrass (Lolium perenne L.

    Directory of Open Access Journals (Sweden)

    Jing Zhang

    2016-10-01

    Full Text Available Leaf senescence is a typical symptom in plants exposed to dark and may be regulated by plant growth regulators. The objective of this study was to determine whether exogenous application of melatonin (N-acetyl-5-methoxytryptamine suppresses dark-induced leaf senescence and the effects of melatonin on reactive oxygen species (ROS scavenging system and chlorophyll degradation pathway in perennial grass species. Mature perennial ryegrass (Lolium perenne L. cv. ‘Pinnacle’ leaves were excised and incubated in 3 mM 2-(N-morpholino ethanesulfonic buffer (pH 5.8 supplemented with melatonin or water (control and exposed to dark treatment for 8 d. Leaves treated with melatonin maintained significantly higher endogenous melatonin level, chlorophyll content, photochemical efficiency, and cell membrane stability expressed by lower electrolyte leakage and malondialdehyde (MDA content compared to the control. Exogenous melatonin treatment also reduced the transcript level of chlorophyll degradation-associated genes and senescence marker genes (LpSAG12.1, Lph36, and Lpl69 during the dark treatment. The endogenous O2- production rate and H2O2 content were significantly lower in these excised leaves treated with melatonin compared to the water control. Exogenous melatonin treatment caused increases in enzymatic activity and transcript levels of superoxide dismutase and catalase but had no significant effects on ascorbate peroxidase, glutathione reductase, dehydroascorbate reductase, and monohydroascorbate reductase. The content of non-enzymatic antioxidants, such as ascorbate and dehydroascorbate, were decreased by melatonin treatment, while the content of glutathione and oxidized glutathione was not affected by melatonin. These results suggest that the suppression of dark-induced leaf senescence by exogenous melatonin may be associated with its roles in regulating ROS scavenging through activating the superoxide dismutase-catalase enzymatic antioxidant

  11. Spectral Induced Polarization Response of Biofilm Formation in Hanford Vadose Zone Sediment

    Science.gov (United States)

    Garcia, A.; Katsenovich, Y.; Lee, B.; Whitman, D.

    2017-12-01

    As a result of the U.S. Nuclear weapons program during the second world war and the cold war, there now exists a significant amount of uranium contamination at the U.S. Department of Energy Hanford site located in Washington state. In-situ immobilization of mobile uranium via injections of a soluble sodium tripolyphosphate amendment may prove effective in the formation of insoluble uranyl phosphate mineral, autunite. However, the injected polyphosphate undergoes hydrolysis in aqueous solutions to form orthophosphate, which serves as a readily available nutrient for the various microorganisms in the sediment. Sediment-filled column experiments conducted under saturated oxygen restricted conditions using geophysical Spectral Induced Polarization technique have shown the impact of microbes on the dissolution of autunite, a calcium uranyl phosphate mineral. Spectral Induced Polarization may be an effective way to track changes indicative of bacterial activities on the surrounding environment. This method can be a cost-effective alternative to the drilling of boreholes at a field scale.

  12. A Phytoanticipin Derivative, Sodium Houttuyfonate, Induces in Vitro Synergistic Effects with Levofloxacin against Biofilm Formation by Pseudomonas aeruginosa

    Directory of Open Access Journals (Sweden)

    Jing Shao

    2012-09-01

    Full Text Available Antibiotic resistance has become the main deadly factor in infections, as bacteria can protect themselves by hiding in a self-constructed biofilm. Consequently, more attention is being paid to the search for “non-antibiotic drugs” to solve this problem. Phytoanticipins, the natural antibiotics from plants, could be a suitable alternative, but few works on this aspect have been reported. In this study, a preliminary study on the synergy between sodium houttuyfonate (SH and levofloxacin (LFX against the biofilm formation of Pseudomonas aeruginosa was performed. The minimal inhibitory concentrations (MIC of LFX and SH, anti-biofilm formation and synergistic effect on Pseudomonas aeruginosa, and quantification of alginate were determined by the microdilution method, crystal violet (CV assay, checkerboard method, and hydroxybiphenyl colorimetry. The biofilm morphology of Pseudomonas aeruginosa was observed by fluorescence microscope and scanning electric microscope (SEM. The results showed that: (i LFX and SH had an obvious synergistic effect against Pseudomonas aeruginosa with MIC values of 0.25 μg/mL and 128 μg/mL, respectively; (ii ½ × MIC SH combined with 2 × MIC LFX could suppress the biofilm formation of Pseudomonas aeruginosa effectively, with up to 73% inhibition; (iii the concentration of alginate decreased dramatically by a maximum of 92% after treatment with the combination of antibiotics; and (iv more dead cells by fluorescence microscope and more removal of extracellular polymeric structure (EPS by SEM were observed after the combined treatment of LFX and SH. Our experiments demonstrate the promising future of this potent antimicrobial agent against biofilm-associated infections.

  13. Host Physiologic Changes Induced by Influenza A Virus Lead to Staphylococcus aureus Biofilm Dispersion and Transition from Asymptomatic Colonization to Invasive Disease

    Directory of Open Access Journals (Sweden)

    Ryan M. Reddinger

    2016-08-01

    Full Text Available Staphylococcus aureus is a ubiquitous opportunistic human pathogen and a major health concern worldwide, causing a wide variety of diseases from mild skin infections to systemic disease. S. aureus is a major source of severe secondary bacterial pneumonia after influenza A virus infection, which causes widespread morbidity and mortality. While the phenomenon of secondary bacterial pneumonia is well established, the mechanisms behind the transition from asymptomatic colonization to invasive staphylococcal disease following viral infection remains unknown. In this report, we have shown that S. aureus biofilms, grown on an upper respiratory epithelial substratum, disperse in response to host physiologic changes related to viral infection, such as febrile range temperatures, exogenous ATP, norepinephrine, and increased glucose. Mice that were colonized with S. aureus and subsequently exposed to these physiologic stimuli or influenza A virus coinfection developed pronounced pneumonia. This study provides novel insight into the transition from colonization to invasive disease, providing a better understanding of the events involved in the pathogenesis of secondary staphylococcal pneumonia.

  14. Epithelial cell detachment by Porphyromonas gingivalis biofilm and planktonic cultures

    NARCIS (Netherlands)

    Huang, L.; van Loveren, C.; Ling, J.; Wei, X.; Crielaard, W.; Deng, D.M.

    2016-01-01

    Porphyromonas gingivalis is present as a biofilm at the sites of periodontal infections. The detachment of gingival epithelial cells induced by P. gingivalis biofilms was examined using planktonic cultures as a comparison. Exponentially grown planktonic cultures or 40-h biofilms were co-incubated

  15. The symbiotic biofilm of Sinorhizobium fredii SMH12, necessary for successful colonization and symbiosis of Glycine max cv Osumi, is regulated by Quorum Sensing systems and inducing flavonoids via NodD1.

    Directory of Open Access Journals (Sweden)

    Francisco Pérez-Montaño

    Full Text Available Bacterial surface components, especially exopolysaccharides, in combination with bacterial Quorum Sensing signals are crucial for the formation of biofilms in most species studied so far. Biofilm formation allows soil bacteria to colonize their surrounding habitat and survive common environmental stresses such as desiccation and nutrient limitation. This mode of life is often essential for survival in bacteria of the genera Mesorhizobium, Sinorhizobium, Bradyrhizobium, and Rhizobium. The role of biofilm formation in symbiosis has been investigated in detail for Sinorhizobium meliloti and Bradyrhizobium japonicum. However, for S. fredii this process has not been studied. In this work we have demonstrated that biofilm formation is crucial for an optimal root colonization and symbiosis between S. fredii SMH12 and Glycine max cv Osumi. In this bacterium, nod-gene inducing flavonoids and the NodD1 protein are required for the transition of the biofilm structure from monolayer to microcolony. Quorum Sensing systems are also required for the full development of both types of biofilms. In fact, both the nodD1 mutant and the lactonase strain (the lactonase enzyme prevents AHL accumulation are defective in soybean root colonization. The impairment of the lactonase strain in its colonization ability leads to a decrease in the symbiotic parameters. Interestingly, NodD1 together with flavonoids activates certain quorum sensing systems implicit in the development of the symbiotic biofilm. Thus, S. fredii SMH12 by means of a unique key molecule, the flavonoid, efficiently forms biofilm, colonizes the legume roots and activates the synthesis of Nod factors, required for successfully symbiosis.

  16. Hydraulic resistance of biofilms

    KAUST Repository

    Dreszer, C.; Vrouwenvelder, Johannes S.; Paulitsch-Fuchs, Astrid H.; Zwijnenburg, Arie; Kruithof, Joop C.; Flemming, Hans Curt

    2013-01-01

    resistance is very low compared to the expected biofilm resistance and, thus, biofilm resistance can be determined accurately. Transmembrane pressure drop was monitored. As biofilm parameters, thickness, total cell number, TOC, and extracellular polymeric

  17. Exogenous lipid pneumonia

    International Nuclear Information System (INIS)

    Bernasconi, A.; Gavelli, G.; Zompatori, M.; Galleri, C.; Zanasi, A.; Fabbri, M.; Bazzocchi, F.

    1988-01-01

    Exogenous lipid pneumonia (ELP) is caused by the aspiration of animal, vegetal or, more often, mineral oils. Even though it may also be acute, ELP is most frequently a chronic disease, affecting people with predisposing factors, such as neuromuscular disorders, structural abnormalities and so on; very often exogenous lipid pneumonia is found in tracheotomized patients. The pathology of lipid pneumonia is a chronic inflammatory process evolving in foreign-body-like reaction, and eventually in ''end-stage lung'' condition. Clinically, most patients are asymptomatic; few cases only present with cough, dyspnea and chest pain. Eight cases of ELP, studied over the past 3 years, are described in this paper. All the patients were examined by chest radiographs and standard tomograms; 3 patients underwent CT. X-ray features were mono/bilateral consolidation of the lower zones, with air bronchogram and variable reduction in volume. CT density was not specific for fat tissue. In all cases the diagnosis was confirmed at biopsy. In 5 patients, followed for at least one year, clinical-radiological features showed no change. Thus, complications of ELP (especially malignant evolution) could be excluded. The authors conclude that lipid pneumonia must be considered in differential diagnosis of patients with history of usage of oils and compatible X-ray findings. The usefulness of an accurate follow-up is stressed

  18. Treatment of Oral Multispecies Biofilms by an Anti-Biofilm Peptide.

    Directory of Open Access Journals (Sweden)

    Zhejun Wang

    Full Text Available Human oral biofilms are multispecies microbial communities that exhibit high resistance to antimicrobial agents. Dental plaque gives rise to highly prevalent and costly biofilm-related oral infections, which lead to caries or other types of oral infections. We investigated the ability of the recently identified anti-biofilm peptide 1018 to induce killing of bacterial cells present within oral multispecies biofilms. At 10 μg/ml (6.5 μM, peptide 1018 was able to significantly (p50% of the biofilm being killed and >35% being dispersed in only 3 minutes. Peptide 1018 may potentially be used by itself or in combination with CHX as a non-toxic and effective anti-biofilm agent for plaque disinfection in clinical dentistry.

  19. Impaired postprandial releases/syntheses of ghrelin and PYY(3-36) and blunted responses to exogenous ghrelin and PYY(3-36) in a rodent model of diet-induced obesity.

    Science.gov (United States)

    Xu, Junying; McNearney, Terry A; Chen, J D Z

    2011-04-01

    This study investigated the effects of peripheral administration of ghrelin and PYY(3-36) on food intake and plasma and tissue fasting and postprandial ghrelin and PYY(3-36) levels in normal-weight (NW) and diet-induced-obese (DIO) rats. In experiment one, NW and DIO rats received a single intraperitoneal injection of saline, PYY(3-36) or ghrelin; food intake was measured for 4 h. In experiment two, total plasma ghrelin and PYY(3-36), gastric fundus ghrelin, and ascending colon PYY(3-36) were measured either after a 20-h fast or 2 h after refeeding in NW and DIO rats by radioimmunoassay. Compared to the NW rats, findings in the DIO rats revealed: (i) a reduced sensitivity to both the anorectic effect of exogenous PYY(3-36) and the orexigenic effect of exogenous ghrelin; (ii) the postprandial plasma ghrelin levels were significantly higher; and (iii) refeeding decreased endogenous plasma ghrelin levels by 53% in the NW rats and 39% in DIO rats. Refeeding increased the plasma PYY(3-36) level by 58% in the NW rats versus 9% in the DIO rats (P=0.003). Compared with regular rats, DIO rats exhibit blunted responses in food intake to exogenous ghrelin and PYY(3-36). Although endogenous ghrelin and PYY(3-36) in DIO rats are not altered in the fasting state, their responses to food ingestion are blunted in comparison with regular rats. © 2011 Journal of Gastroenterology and Hepatology Foundation and Blackwell Publishing Asia Pty Ltd.

  20. The in vivo biofilm

    DEFF Research Database (Denmark)

    Bjarnsholt, Thomas; Alhede, Maria; Alhede, Morten

    2013-01-01

    Bacteria can grow and proliferate either as single, independent cells or organized in aggregates commonly referred to as biofilms. When bacteria succeed in forming a biofilm within the human host, the infection often becomes very resistant to treatment and can develop into a chronic state. Biofilms...... have been studied for decades using various in vitro models, but it remains debatable whether such in vitro biofilms actually resemble in vivo biofilms in chronic infections. In vivo biofilms share several structural characteristics that differ from most in vitro biofilms. Additionally, the in vivo...... experimental time span and presence of host defenses differ from chronic infections and the chemical microenvironment of both in vivo and in vitro biofilms is seldom taken into account. In this review, we discuss why the current in vitro models of biofilms might be limited for describing infectious biofilms...

  1. Warming-induced changes in denitrifier community structure modulate the ability of phototrophic river biofilms to denitrify

    Energy Technology Data Exchange (ETDEWEB)

    Boulêtreau, Stéphanie, E-mail: stephanie.bouletreau@univ-tlse3.fr [Université de Toulouse, UPS, INP, EcoLab (Laboratoire Ecologie Fonctionnelle et Environnement), 118 route de Narbonne, F-31062 Toulouse (France); CNRS, EcoLab, F-31062 Toulouse (France); Lyautey, Emilie [Université de Toulouse, UPS, INP, EcoLab (Laboratoire Ecologie Fonctionnelle et Environnement), 118 route de Narbonne, F-31062 Toulouse (France); CNRS, EcoLab, F-31062 Toulouse (France); Dubois, Sophie [Université de Bordeaux, EPOC - OASU, UMR 5805, Station Marine d' Arcachon, 2 rue du Professeur Jolyet, 33120 Arcachon (France); Compin, Arthur [Université de Toulouse, UPS, INP, EcoLab (Laboratoire Ecologie Fonctionnelle et Environnement), 118 route de Narbonne, F-31062 Toulouse (France); CNRS, EcoLab, F-31062 Toulouse (France); Delattre, Cécile; Touron-Bodilis, Aurélie [EDF Recherche et Développement, LNHE (Laboratoire National d' Hydraulique et Environnement), 6 quai Watier, F-78401 Chatou (France); Mastrorillo, Sylvain [Université de Toulouse, UPS, INP, EcoLab (Laboratoire Ecologie Fonctionnelle et Environnement), 118 route de Narbonne, F-31062 Toulouse (France); CNRS, EcoLab, F-31062 Toulouse (France); Garabetian, Frédéric [Université de Bordeaux, EPOC - OASU, UMR 5805, Station Marine d' Arcachon, 2 rue du Professeur Jolyet, 33120 Arcachon (France)

    2014-01-01

    Microbial denitrification is the main nitrogen removing process in freshwater ecosystems. The aim of this study was to show whether and how water warming (+ 2.5 °C) drives bacterial diversity and structuring and how bacterial diversity affects denitrification enzymatic activity in phototrophic river biofilms (PRB). We used water warming associated to the immediate thermal release of a nuclear power plant cooling circuit to produce natural PRB assemblages on glass slides while testing 2 temperatures (mean temperature of 17 °C versus 19.5 °C). PRB were sampled at 2 sampling times during PRB accretion (6 and 21 days) in both temperatures. Bacterial community composition was assessed using ARISA. Denitrifier community abundance and denitrification gene mRNA levels were estimated by q-PCR and qRT-PCR, respectively, of 5 genes encoding catalytic subunits of the denitrification key enzymes. Denitrification enzyme activity (DEA) was measured by the acetylene-block assay at 20 °C. A mean water warming of 2.5 °C was sufficient to produce contrasted total bacterial and denitrifier communities and, therefore, to affect DEA. Indirect temperature effect on DEA may have varied between sampling time, increasing by up to 10 the denitrification rate of 6-day-old PRB and decreasing by up to 5 the denitrification rate of 21-day-old PRB. The present results suggest that indirect effects of warming through changes in bacterial community composition, coupled to the strong direct effect of temperature on DEA already demonstrated in PRB, could modulate dissolved nitrogen removal by denitrification in rivers and streams. - Highlights: •We produced river biofilms in 2 mean temperature conditions: 17 vs 19.5 °C. •We compared their denitrifiers' structuring and functioning in 6d- and 21d-old biofilms. •A difference of 2.5 °C produced contrasted denitrifier communities. •The indirect temperature effect on denitrification activity shifted between biofilm age.

  2. Biophysics of biofilm infection.

    Science.gov (United States)

    Stewart, Philip S

    2014-04-01

    This article examines a likely basis of the tenacity of biofilm infections that has received relatively little attention: the resistance of biofilms to mechanical clearance. One way that a biofilm infection persists is by withstanding the flow of fluid or other mechanical forces that work to wash or sweep microorganisms out of the body. The fundamental criterion for mechanical persistence is that the biofilm failure strength exceeds the external applied stress. Mechanical failure of the biofilm and release of planktonic microbial cells is also important in vivo because it can result in dissemination of infection. The fundamental criterion for detachment and dissemination is that the applied stress exceeds the biofilm failure strength. The apparent contradiction for a biofilm to both persist and disseminate is resolved by recognizing that biofilm material properties are inherently heterogeneous. There are also mechanical aspects to the ways that infectious biofilms evade leukocyte phagocytosis. The possibility of alternative therapies for treating biofilm infections that work by reducing biofilm cohesion could (1) allow prevailing hydrodynamic shear to remove biofilm, (2) increase the efficacy of designed interventions for removing biofilms, (3) enable phagocytic engulfment of softened biofilm aggregates, and (4) improve phagocyte mobility and access to biofilm. © 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

  3. Simvastatin inhibits Candida albicans biofilm in vitro.

    Science.gov (United States)

    Liu, Geoffrey; Vellucci, Vincent F; Kyc, Stephanie; Hostetter, Margaret K

    2009-12-01

    By inhibiting the conversion of 3-hydroxy-3-methylglutaryl CoA (HMG-CoA) to mevalonate, statins impair cholesterol metabolism in humans. We reasoned that statins might similarly interfere with the biosynthesis of ergosterol, the major sterol of the yeast cell membrane. As assessed by spectrophotometric and microscopic analysis, significant inhibition of biofilm production was noted after 16-h incubation with 1, 2.5, and 5 muM simvastatin, concentrations that did not affect growth, adhesion, or hyphal formation by C. albicans in vitro. Higher concentrations (10, 20, and 25 muM simvastatin) inhibited biofilm by >90% but also impaired growth. Addition of exogenous ergosterol (90 muM) overcame the effects of 1 and 2.5 muM simvastatin, suggesting that at least one mechanism of inhibition is interference with ergosterol biosynthesis. Clinical isolates from blood, skin, and mucosal surfaces produced biofilms; biofilms from bloodstream isolates were similarly inhibited by simvastatin. In the absence of fungicidal activity, simvastatin's interruption of a critical step in an essential metabolic pathway, highly conserved from yeast to man, has unexpected effects on biofilm production by a eukaryotic pathogen.

  4. Treatment of Candida albicans biofilms with low-temperature plasma induced by dielectric barrier discharge and atmospheric pressure plasma jet

    International Nuclear Information System (INIS)

    Koban, Ina; Welk, Alexander; Meisel, Peter; Holtfreter, Birte; Kocher, Thomas; Matthes, Rutger; Huebner, Nils-Olaf; Kramer, Axel; Sietmann, Rabea; Kindel, Eckhard; Weltmann, Klaus-Dieter

    2010-01-01

    Because of some disadvantages of chemical disinfection in dental practice (especially denture cleaning), we investigated the effects of physical methods on Candida albicans biofilms. For this purpose, the antifungal efficacy of three different low-temperature plasma devices (an atmospheric pressure plasma jet and two different dielectric barrier discharges (DBDs)) on Candida albicans biofilms grown on titanium discs in vitro was investigated. As positive treatment controls, we used 0.1% chlorhexidine digluconate (CHX) and 0.6% sodium hypochlorite (NaOCl). The corresponding gas streams without plasma ignition served as negative treatment controls. The efficacy of the plasma treatment was determined evaluating the number of colony-forming units (CFU) recovered from titanium discs. The plasma treatment reduced the CFU significantly compared to chemical disinfectants. While 10 min CHX or NaOCl exposure led to a CFU log 10 reduction factor of 1.5, the log 10 reduction factor of DBD plasma was up to 5. In conclusion, the use of low-temperature plasma is a promising physical alternative to chemical antiseptics for dental practice.

  5. Treatment of Candida albicans biofilms with low-temperature plasma induced by dielectric barrier discharge and atmospheric pressure plasma jet

    Energy Technology Data Exchange (ETDEWEB)

    Koban, Ina; Welk, Alexander; Meisel, Peter; Holtfreter, Birte; Kocher, Thomas [Unit of Periodontology, Dental School, University of Greifswald, Rotgerberstr. 8, 17475 Greifswald (Germany); Matthes, Rutger; Huebner, Nils-Olaf; Kramer, Axel [Institute for Hygiene and Environmental Medicine, University of Greifswald, Walther-Rathenau-Str. 49 a, 17487 Greifswald (Germany); Sietmann, Rabea [Institute of Microbiology, University of Greifswald, Friedrich-Ludwig-Jahn-Str. 15, 17487 Greifswald (Germany); Kindel, Eckhard; Weltmann, Klaus-Dieter, E-mail: ina.koban@uni-greifswald.d [Leibniz Institute for Plasma Science and Technology (INP), Felix-Hausdorff-Str. 2, 17489 Greifswald (Germany)

    2010-07-15

    Because of some disadvantages of chemical disinfection in dental practice (especially denture cleaning), we investigated the effects of physical methods on Candida albicans biofilms. For this purpose, the antifungal efficacy of three different low-temperature plasma devices (an atmospheric pressure plasma jet and two different dielectric barrier discharges (DBDs)) on Candida albicans biofilms grown on titanium discs in vitro was investigated. As positive treatment controls, we used 0.1% chlorhexidine digluconate (CHX) and 0.6% sodium hypochlorite (NaOCl). The corresponding gas streams without plasma ignition served as negative treatment controls. The efficacy of the plasma treatment was determined evaluating the number of colony-forming units (CFU) recovered from titanium discs. The plasma treatment reduced the CFU significantly compared to chemical disinfectants. While 10 min CHX or NaOCl exposure led to a CFU log{sub 10} reduction factor of 1.5, the log{sub 10} reduction factor of DBD plasma was up to 5. In conclusion, the use of low-temperature plasma is a promising physical alternative to chemical antiseptics for dental practice.

  6. Exogenous Cushing syndrome

    Science.gov (United States)

    Cushing syndrome - corticosteroid induced; Corticosteroid-induced Cushing syndrome; Iatrogenic Cushing syndrome ... Cushing syndrome is a disorder that occurs when your body has a higher than normal level of the hormone ...

  7. Anti-Biofilm and Immunomodulatory Activities of Peptides That Inhibit Biofilms Formed by Pathogens Isolated from Cystic Fibrosis Patients

    Directory of Open Access Journals (Sweden)

    César de la Fuente-Núñez

    2014-10-01

    Full Text Available Cystic fibrosis (CF patients often acquire chronic respiratory tract infections due to Pseudomonas aeruginosa and Burkholderia cepacia complex (Bcc species. In the CF lung, these bacteria grow as multicellular aggregates termed biofilms. Biofilms demonstrate increased (adaptive resistance to conventional antibiotics, and there are currently no available biofilm-specific therapies. Using plastic adherent, hydroxyapatite and flow cell biofilm models coupled with confocal and scanning electron microscopy, it was demonstrated that an anti-biofilm peptide 1018 prevented biofilm formation, eradicated mature biofilms and killed biofilms formed by a wide range of P. aeruginosa and B. cenocepacia clinical isolates. New peptide derivatives were designed that, compared to their parent peptide 1018, showed similar or decreased anti-biofilm activity against P. aeruginosa biofilms, but increased activity against biofilms formed by the Gram-positive bacterium methicillin resistant Staphylococcus aureus. In addition, some of these new peptide derivatives retained the immunomodulatory activity of 1018 since they induced the production of the chemokine monocyte chemotactic protein-1 (MCP-1 and suppressed lipopolysaccharide-mediated tumor necrosis factor-α (TNF-α production by human peripheral blood mononuclear cells (PBMC and were non-toxic towards these cells. Peptide 1018 and its derivatives provide promising leads for the treatment of chronic biofilm infections and hyperinflammatory lung disease in CF patients.

  8. Low Fluid Shear Culture of Staphylococcus Aureus Represses hfq Expression and Induces an Attachment-Independent Biofilm Phenotype

    Science.gov (United States)

    Ott, C. Mark; Castro, S. L.; Nickerson, C. A.; Nelman-Gonzalez, M.

    2011-01-01

    Background: The opportunistic pathogen, Staphylococcus aureus, experiences fluctuations in fluid shear during infection and colonization of a human host. Colonization frequently occurs at mucus membrane sites such as in the gastrointestinal tract where the bacterium may experience low levels of fluid shear. The response of S. aureus to low fluid shear remains unclear. Methods: S. aureus was cultured to stationary phase using Rotating-Wall Vessel (RWV) bioreactors which produce a physiologically relevant low fluid shear environment. The bacterial aggregates that developed in the RWV were evaluated by electron microscopy as well as for antibiotic resistance and other virulence-associated stressors. Genetic expression profiles for the low-shear cultured S. aureus were determined by microarray analysis and quantitative real-time PCR. Results: Planktonic S. aureus cultures in the low-shear environment formed aggregates completely encased in high amounts of extracellular polymeric substances. In addition, these aggregates demonstrated increased antibiotic resistance indicating attachment-independent biofilm formation. Carotenoid production in the low-shear cultured S. aureus was significantly decreased, and these cultures displayed an increased susceptibility to oxidative stress and killing by whole blood. The hfq gene, associated with low-shear growth in Gram negative organisms, was also found to be down-regulated in S. aureus. Conclusions: Collectively, this data suggests that S. aureus decreases virulence characteristics in favor of a biofilm-dwelling colonization phenotype in response to a low fluid shear environment. Furthermore, the identification of an Hfq response to low-shear culture in S. aureus, in addition to the previously reported responses in Gram negative organisms, strongly suggests an evolutionarily conserved response to mechanical stimuli among structurally diverse prokaryotes.

  9. Biofilm Fixed Film Systems

    Directory of Open Access Journals (Sweden)

    Dipesh Das

    2011-09-01

    Full Text Available The work reviewed here was published between 2008 and 2010 and describes research that involved aerobic and anoxic biofilm treatment of water pollutants. Biofilm denitrification systems are covered when appropriate. References catalogued here are divided on the basis of fundamental research area or reactor types. Fundamental research into biofilms is presented in two sections, Biofilm Measurement and Characterization and Growth and Modeling. The reactor types covered are: trickling filters, rotating biological contactors, fluidized bed bioreactors, submerged bed biofilm reactors, biological granular activated carbon, membrane bioreactors, and immobilized cell reactors. Innovative reactors, not easily classified, are then presented, followed by a section on biofilms on sand, soil and sediment.

  10. Treatment of Oral Multispecies Biofilms by an Anti-Biofilm Peptide.

    Science.gov (United States)

    Wang, Zhejun; de la Fuente-Núñez, Cesar; Shen, Ya; Haapasalo, Markus; Hancock, Robert E W

    2015-01-01

    Human oral biofilms are multispecies microbial communities that exhibit high resistance to antimicrobial agents. Dental plaque gives rise to highly prevalent and costly biofilm-related oral infections, which lead to caries or other types of oral infections. We investigated the ability of the recently identified anti-biofilm peptide 1018 to induce killing of bacterial cells present within oral multispecies biofilms. At 10 μg/ml (6.5 μM), peptide 1018 was able to significantly (pbiofilm formation over 3 days. The activity of the peptide on preformed biofilms was found to be concentration-dependent since more than 60% of the total plaque biofilm cell population was killed by 10 μg/ml of peptide 1018 in 3 days, while at 5 μg/ml 50% of cells were dead and at 1 μg/ml the peptide triggered cell death in around 30% of the total bacterial population, as revealed by confocal microscopy. The presence of saliva did not affect peptide activity, since no statistically significant difference was found in the ability of peptide 1018 to kill oral biofilms using either saliva coated and non-saliva coated hydroxyapatite surfaces. Scanning electron microscopy experiments indicated that peptide 1018 induced cell lysis in plaque biofilms. Furthermore, combined treatment using peptide 1018 and chlorhexidine (CHX) increased the anti-biofilm activity of each compound compared to when these were used alone, resulting in >50% of the biofilm being killed and >35% being dispersed in only 3 minutes. Peptide 1018 may potentially be used by itself or in combination with CHX as a non-toxic and effective anti-biofilm agent for plaque disinfection in clinical dentistry.

  11. Nutrient transitions are a source of persisters in Escherichia coli biofilms.

    Directory of Open Access Journals (Sweden)

    Stephanie M Amato

    Full Text Available Chronic and recurrent infections have been attributed to persisters in biofilms, and despite this importance, the mechanisms of persister formation in biofilms remain unclear. The plethora of biofilm characteristics that could give rise to persisters, including slower growth, quorum signaling, oxidative stress, and nutrient heterogeneity, have complicated efforts to delineate formation pathways that generate persisters during biofilm development. Here we sought to specifically determine whether nutrient transitions, which are a common metabolic stress encountered within surface-attached communities, stimulate persister formation in biofilms and if so, to then identify the pathway. To accomplish this, we established an experimental methodology where nutrient availability to biofilm cells could be controlled exogenously, and then used that method to discover that diauxic carbon source transitions stimulated persister formation in Escherichia coli biofilms. Previously, we found that carbon source transitions stimulate persister formation in planktonic E. coli cultures, through a pathway that involved ppGpp and nucleoid-associated proteins, and therefore, tested the functionality of that pathway in biofilms. Biofilm persister formation was also found to be dependent on ppGpp and nucleoid-associated proteins, but the importance of specific proteins and enzymes between biofilm and planktonic lifestyles was significantly different. Data presented here support the increasingly appreciated role of ppGpp as a central mediator of bacterial persistence and demonstrate that nutrient transitions can be a source of persisters in biofilms.

  12. Nutrient transitions are a source of persisters in Escherichia coli biofilms.

    Science.gov (United States)

    Amato, Stephanie M; Brynildsen, Mark P

    2014-01-01

    Chronic and recurrent infections have been attributed to persisters in biofilms, and despite this importance, the mechanisms of persister formation in biofilms remain unclear. The plethora of biofilm characteristics that could give rise to persisters, including slower growth, quorum signaling, oxidative stress, and nutrient heterogeneity, have complicated efforts to delineate formation pathways that generate persisters during biofilm development. Here we sought to specifically determine whether nutrient transitions, which are a common metabolic stress encountered within surface-attached communities, stimulate persister formation in biofilms and if so, to then identify the pathway. To accomplish this, we established an experimental methodology where nutrient availability to biofilm cells could be controlled exogenously, and then used that method to discover that diauxic carbon source transitions stimulated persister formation in Escherichia coli biofilms. Previously, we found that carbon source transitions stimulate persister formation in planktonic E. coli cultures, through a pathway that involved ppGpp and nucleoid-associated proteins, and therefore, tested the functionality of that pathway in biofilms. Biofilm persister formation was also found to be dependent on ppGpp and nucleoid-associated proteins, but the importance of specific proteins and enzymes between biofilm and planktonic lifestyles was significantly different. Data presented here support the increasingly appreciated role of ppGpp as a central mediator of bacterial persistence and demonstrate that nutrient transitions can be a source of persisters in biofilms.

  13. Activity of antimicrobial peptide mimetics in the oral cavity: II. Activity against periopathogenic biofilms and anti-inflammatory activity

    Science.gov (United States)

    Hua, J; Scott, R.W.; Diamond, G

    2011-01-01

    Whereas periodontal disease is ultimately of bacterial etiology, from multispecies biofilms of gram-negative anaerobic microorganisms, much of the deleterious effects are caused by the resultant epithelial inflammatory response. Hence, development of a treatment that combines anti-biofilm antibiotic activity with anti-inflammatory activity would be of great utility. Antimicrobial peptides (AMPs) such as defensins are naturally occurring peptides that exhibit broad-spectrum activity as well as a variety of immunomodulatory activities. Furthermore, bacteria do not readily develop resistance to these agents. However, clinical studies have suggested that they do not represent optimal candidates for exogenous therapeutic agents. Small-molecule mimetics of these AMPs exhibit similar activities to the parent peptides, in addition to having low toxicity, high stability and low cost. To determine whether AMP mimetics have the potential for treatment of periodontal disease, we examined the activity of one mimetic, mPE, against biofilm cultures of Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis. Metabolic assays as well as culture and biomass measurement assays demonstrated that mPE exhibits potent activity against biofilm cultures of both species. Furthermore, as little as 2 µg ml−1 mPE was sufficient to inhibit interleukin-1β-induced secretion of interleukin-8 in both gingival epithelial cells and THP-1 cells. This anti-inflammatory activity is associated with a reduction in activation of nuclear factor-κB, suggesting that mPE can act both as an anti-biofilm agent in an anaerobic environment and as an anti-inflammatory agent in infected tissues. PMID:21040516

  14. Pseudomonas aeruginosa Biofilm Infections

    DEFF Research Database (Denmark)

    Rybtke, Morten; Hultqvist, Louise Dahl; Givskov, Michael

    2015-01-01

    Studies of biopsies from infectious sites, explanted tissue and medical devises have provided evidence that biofilms are the underlying cause of a variety of tissue-associated and implant-associated recalcitrant human infections. With a need for novel anti-biofilm treatment strategies, research...... in biofilm infection microbiology, biofilm formation mechanisms and biofilm-associated antimicrobial tolerance has become an important area in microbiology. Substantial knowledge about biofilm formation mechanisms, biofilm-associated antimicrobial tolerance and immune evasion mechanisms has been obtained...... through work with biofilms grown in in vitro experimental setups, and the relevance of this information in the context of chronic infections is being investigated by the use of animal models of infection. Because our current in vitro experimental setups and animal models have limitations, new advanced...

  15. The Biofilm Challenge

    DEFF Research Database (Denmark)

    Alhede, Maria; Alhede, Morten

    2014-01-01

    The concept of biofilms has emerged in the clinical setting during the last decade. Infections involving biofilms have been documented in all parts of the human body, and it is currently believed that the presence of biofilm-forming bacteria is equivalent to chronic infection. A quick Pubmed search...

  16. Flagellar motility is critical for Listeria monocytogenes biofilm formation.

    Science.gov (United States)

    Lemon, Katherine P; Higgins, Darren E; Kolter, Roberto

    2007-06-01

    The food-borne pathogen Listeria monocytogenes attaches to environmental surfaces and forms biofilms that can be a source of food contamination, yet little is known about the molecular mechanisms of its biofilm development. We observed that nonmotile mutants were defective in biofilm formation. To investigate how flagella might function during biofilm formation, we compared the wild type with flagellum-minus and paralyzed-flagellum mutants. Both nonmotile mutants were defective in biofilm development, presumably at an early stage, as they were also defective in attachment to glass during the first few hours of surface exposure. This attachment defect could be significantly overcome by providing exogenous movement toward the surface via centrifugation. However, this centrifugation did not restore mature biofilm formation. Our results indicate that it is flagellum-mediated motility that is critical for both initial surface attachment and subsequent biofilm formation. Also, any role for L. monocytogenes flagella as adhesins on abiotic surfaces appears to be either minimal or motility dependent under the conditions we examined.

  17. Crenarchaeal biofilm formation under extreme conditions.

    Directory of Open Access Journals (Sweden)

    Andrea Koerdt

    Full Text Available BACKGROUND: Biofilm formation has been studied in much detail for a variety of bacterial species, as it plays a major role in the pathogenicity of bacteria. However, only limited information is available for the development of archaeal communities that are frequently found in many natural environments. METHODOLOGY: We have analyzed biofilm formation in three closely related hyperthermophilic crenarchaeotes: Sulfolobus acidocaldarius, S. solfataricus and S. tokodaii. We established a microtitre plate assay adapted to high temperatures to determine how pH and temperature influence biofilm formation in these organisms. Biofilm analysis by confocal laser scanning microscopy demonstrated that the three strains form very different communities ranging from simple carpet-like structures in S. solfataricus to high density tower-like structures in S. acidocaldarius in static systems. Lectin staining indicated that all three strains produced extracellular polysaccharides containing glucose, galactose, mannose and N-acetylglucosamine once biofilm formation was initiated. While flagella mutants had no phenotype in two days old static biofilms of S. solfataricus, a UV-induced pili deletion mutant showed decreased attachment of cells. CONCLUSION: The study gives first insights into formation and development of crenarchaeal biofilms in extreme environments.

  18. Spatial orienting around the fovea: exogenous and endogenous cueing effects.

    Science.gov (United States)

    Yang, Taoxi; Zhang, Jiyuan; Bao, Yan

    2015-09-01

    The effect of covert attention in perifoveal and peripheral locations has been studied extensively. However, it is less clear whether attention operates similarly in the foveal area itself. The present study aims to investigate whether the attentional orienting elicited by an exogenous or endogenous cue can operate within the foveal area and whether attentional orienting operates similarly between foveal and perifoveal regions. By manipulating exogenous orienting in Experiment 1 and endogenous orienting in Experiment 2, we observed both forms of cueing in the foveal area. Specifically, we observed a larger exogenous cue-induced inhibitory effect (i.e., inhibition of return effect) and a similar endogenous cue-elicited facilitatory effect for the perifoveal relative to the foveal targets. We conclude that exogenous and endogenous orienting subject to two independent attentional systems with distinct modulation patterns in the foveal area.

  19. Effect of exogenous leptin on serum levels of lipids, glucose, renal and hepatic variables in both genders of obese and streptozotocin-induced diabetic rats

    Directory of Open Access Journals (Sweden)

    Parichehr Hayatdavoudi

    2015-11-01

    Full Text Available Objective(s: Leptin exerts various effects on appetite and body weight. Disruption of the obesitygene is precedent to fatness. Insulin or glucose elevates leptin, but streptozotocin reduces it. However, controversial data exist for the effects of leptin on diabetes and leptin level in each gender. Leptin can damage the kidney function but little evidence exists for its hepatic effects. The aim of this study was to investigate the probable sex-dependent differences in blood sugar levels, lipid profile, and renal and hepatic biochemical factors in the obesity and streptozotocin-induced diabetic rats after leptin administration. Materials and Methods: Wistar rats of both sexes were randomly divided into two groups, namely obese and diabetic rats. Each group was further divided into male and female subgroups. Extra fat and carbohydrate was added to the diet to induce obesity. Furthermore, streptozotocin (55 mg/kg, IP was injected to induce diabetes. The treatment groups received leptin (0.1 mg/kg SC for 10 days, and then, blood samples were taken from the orbital sinus for laboratory evaluations. Results: Leptin resulted in a significant weight loss in both sexes (P

  20. Direct Comparison of Physical Properties of Bacillus subtilis NCIB 3610 and B-1 Biofilms

    Science.gov (United States)

    Kesel, Sara; Grumbein, Stefan; Gümperlein, Ina; Tallawi, Marwa; Marel, Anna-Kristina

    2016-01-01

    Many bacteria form surface-attached communities known as biofilms. Due to the extreme resistance of these bacterial biofilms to antibiotics and mechanical stresses, biofilms are of growing interest not only in microbiology but also in medicine and industry. Previous studies have determined the extracellular polymeric substances present in the matrix of biofilms formed by Bacillus subtilis NCIB 3610. However, studies on the physical properties of biofilms formed by this strain are just emerging. In particular, quantitative data on the contributions of biofilm matrix biopolymers to these physical properties are lacking. Here, we quantitatively investigated three physical properties of B. subtilis NCIB 3610 biofilms: the surface roughness and stiffness and the bulk viscoelasticity of these biofilms. We show how specific biomolecules constituting the biofilm matrix formed by this strain contribute to those biofilm properties. In particular, we demonstrate that the surface roughness and surface elasticity of 1-day-old NCIB 3610 biofilms are strongly affected by the surface layer protein BslA. For a second strain, B. subtilis B-1, which forms biofilms containing mainly γ-polyglutamate, we found significantly different physical biofilm properties that are also differently affected by the commonly used antibacterial agent ethanol. We show that B-1 biofilms are protected from ethanol-induced changes in the biofilm's stiffness and that this protective effect can be transferred to NCIB 3610 biofilms by the sole addition of γ-polyglutamate to growing NCIB 3610 biofilms. Together, our results demonstrate the importance of specific biofilm matrix components for the distinct physical properties of B. subtilis biofilms. PMID:26873313

  1. Sexual Biofilm Formation in Candida tropicalis Opaque Cells

    Science.gov (United States)

    Jones, Stephen K.; Hirakawa, Matthew P.; Bennett, Richard J.

    2014-01-01

    Summary Candida albicans and Candida tropicalis are opportunistic fungal pathogens that can transition between white and opaque phenotypic states. White and opaque cells differ both morphologically and in their responses to environmental signals. In C. albicans, opaque cells respond to sexual pheromones by undergoing conjugation, while white cells are induced by pheromones to form sexual biofilms. Here, we show that sexual biofilm formation also occurs in C. tropicalis but, unlike C. albicans, biofilms are formed exclusively by opaque cells. C. tropicalis biofilm formation was dependent on the pheromone receptors Ste2 and Ste3, confirming the role of pheromone signaling in sexual biofilm development. Structural analysis of C. tropicalis sexual biofilms revealed stratified communities consisting of a basal layer of yeast cells and an upper layer of filamentous cells, together with an extracellular matrix. Transcriptional profiling showed that genes involved in pheromone signaling and conjugation were upregulated in sexual biofilms. Furthermore, FGR23, which encodes an agglutinin-like protein, was found to enhance both mating and sexual biofilm formation. Together, these studies reveal that C. tropicalis opaque cells form sexual biofilms with a complex architecture, and suggest a conserved role for sexual agglutinins in mediating mating, cell cohesion and biofilm formation. PMID:24612417

  2. Increased radiation-induced transformation in C3H/10T1/2 cells after transfer of an exogenous c-myc gene

    International Nuclear Information System (INIS)

    Sorrentino, V.; Drozdoff, V.; Zeitz, L.; Fleissner, E.

    1987-01-01

    C3H/10T 1/2 cells were infected with a retroviral vector expressing a mouse c-myc oncogene and a drug-selection marker. The resulting cells, morphologically indistinguishable from C3H/10T l/1, displayed a greatly enhanced sensitivity to neoplastic transformation by ionizing radiation or by a chemical carcinogen. Constitutive expression of myc therefore appears to synergize with an initial carcinogenic event, providing a function analogous to a subsequent event that apparently is required for the neoplastic transformation of these cells. This cell system should prove useful in exploring early stages in radiation-induced transformation

  3. Insights into cadmium induced physiological and ultra-structural disorders in Juncus effusus L. and its remediation through exogenous citric acid

    International Nuclear Information System (INIS)

    Najeeb, Ullah; Jilani, Ghulam; Ali, Shafaqat; Sarwar, Muhammad; Xu Ling; Zhou, Weijun

    2011-01-01

    This study appraised cadmium (Cd) toxicity stress in wetland plant Juncus effusus, and explored its potential for Cd phytoextraction through chelators (citric acid and EDTA). Cadmium altered morphological and physiological attributes of J. effusus as reflected by growth retardation. Citric acid in the presence of 100 μM Cd significantly countered Cd toxicity by improving plant growth. Elevated Cd concentrations reduced translocation factor that was increased under application of both chelators. Citric acid enhanced Cd accumulation, while EDTA reduced its uptake. Cadmium induced oxidative stress modified the antioxidative enzyme activity. Both levels of citric acid (2.5 and 5.0 mM) and lower EDTA concentration (2.5 mM) helped plants to overcome oxidative stress by enhancing their antioxidative enzyme activities. Cadmium damaged the root cells through cytoplasmic shrinkage and metal deposition. Citric acid restored structure and shape of root cells and eliminated plasmolysis; whereas, EDTA exhibited no positive effect on it. Shoot cells remained unaffected under Cd treatment alone or with citric acid except for chloroplast swelling. Only EDTA promoted starch accumulation in chloroplast reflecting its negative impact on cellular structure. It concludes that Cd and EDTA induce structural and morphological damage in J. effusus; while, citric acid ameliorates Cd toxicity stress.

  4. Insights into cadmium induced physiological and ultra-structural disorders in Juncus effusus L. and its remediation through exogenous citric acid

    Energy Technology Data Exchange (ETDEWEB)

    Najeeb, Ullah [Institute of Crop Science, Zhejiang University, Hangzhou 310029 (China); Crop Sciences Institute, National Agriculture Research Centre, Islamabad 45500 (Pakistan); Jilani, Ghulam, E-mail: jilani@uaar.edu.pk [Department of Soil Science, PMAS Arid Agriculture University, Rawalpindi, Punjab 46300 (Pakistan); Ali, Shafaqat [Institute of Crop Science, Zhejiang University, Hangzhou 310029 (China); Sarwar, Muhammad [Land Resources Research Institute, National Agriculture Research Centre, Islamabad 45500 (Pakistan); Xu Ling [Institute of Crop Science, Zhejiang University, Hangzhou 310029 (China); Zhou, Weijun, E-mail: wjzhou@zju.edu.cn [Institute of Crop Science, Zhejiang University, Hangzhou 310029 (China)

    2011-02-15

    This study appraised cadmium (Cd) toxicity stress in wetland plant Juncus effusus, and explored its potential for Cd phytoextraction through chelators (citric acid and EDTA). Cadmium altered morphological and physiological attributes of J. effusus as reflected by growth retardation. Citric acid in the presence of 100 {mu}M Cd significantly countered Cd toxicity by improving plant growth. Elevated Cd concentrations reduced translocation factor that was increased under application of both chelators. Citric acid enhanced Cd accumulation, while EDTA reduced its uptake. Cadmium induced oxidative stress modified the antioxidative enzyme activity. Both levels of citric acid (2.5 and 5.0 mM) and lower EDTA concentration (2.5 mM) helped plants to overcome oxidative stress by enhancing their antioxidative enzyme activities. Cadmium damaged the root cells through cytoplasmic shrinkage and metal deposition. Citric acid restored structure and shape of root cells and eliminated plasmolysis; whereas, EDTA exhibited no positive effect on it. Shoot cells remained unaffected under Cd treatment alone or with citric acid except for chloroplast swelling. Only EDTA promoted starch accumulation in chloroplast reflecting its negative impact on cellular structure. It concludes that Cd and EDTA induce structural and morphological damage in J. effusus; while, citric acid ameliorates Cd toxicity stress.

  5. Development and maturation of Escherichia coli K-12 biofilms

    DEFF Research Database (Denmark)

    Reisner, A.; Haagensen, J.A.J.; Schembri, Mark

    2003-01-01

    The development and maturation of E. coli biofilms in flow-chambers was investigated. We found that the presence of transfer constitutive IncF plasmids induced biofilm development forming structures resembling those reported for Pseudomonas aeruginosa . The development occurred in a step...... occurred in conjugation pilus proficient plasmid-carrying strains. The final shapes of the expanding structures in the mature biofilm seem to be determined by the pilus configuration, as various mutants affected in the processing and activity of the transfer pili displayed differently structured biofilms....... We further provide evidence that flagella, type 1 fimbriae, curli and Ag43 are all dispensable for the observed biofilm maturation. In addition, our results indicate that cell-to-cell signalling mediated by autoinducer 2 (AI-2) is not required for differentiation of E. coli within a biofilm community...

  6. Human Tear Fluid Reduces Culturability of Contact Lens Associated Pseudomonas aeruginosa Biofilms but Induces Expression of the Virulence Associated Type III Secretion System

    Science.gov (United States)

    Wu, Yvonne T.; Tam, Connie; Zhu, Lucia S.; Evans, David J.; Fleiszig, Suzanne M. J.

    2017-01-01

    Purpose The type III secretion system (T3SS) is a significant virulence determinant for Pseudomonas aeruginosa. Using a rodent model, we found that contact lens (CL)-related corneal infections were associated with lens surface biofilms. Here, we studied the impact of human tear fluid on CL-associated biofilm growth and T3SS expression. Methods P. aeruginosa biofilms were formed on contact lenses for up to 7 days with or without human tear fluid, then exposed to tear fluid for 5 or 24 h. Biofilms were imaged using confocal microscopy. Bacterial culturability was quantified by viable counts, and T3SS gene expression measured by RT-qPCR. Controls included trypticase soy broth, PBS and planktonic bacteria. Results With or without tear fluid, biofilms grew to ~108 cfu viable bacteria by 24 h. Exposing biofilms to tear fluid after they had formed without it on lenses reduced bacterial culturability ~180-fold (pbacteria [5.46 ± 0.24-fold for T3SS transcriptional activitor exsA (p=.02), and 3.76 ± 0.36-fold for T3SS effector toxin exoS (p=.01)]. Tear fluid further enhanced exsA and exoS expression in CL-grown biofilms, but not planktonic bacteria, by 2.09 ± 0.38-fold (p = 0.04) and 1.89 ± 0.26-fold (p<.001), respectively. Conclusions Considering the pivitol role of the T3SS in P. aeruginosa infections, its induction in CL-grown P. aeruginosa biofilms by tear fluid might contribute to the pathogenesis of CL-related P. aeruginosa keratitis. PMID:27670247

  7. The impact of manganese on biofilm development of Bacillus subtilis

    NARCIS (Netherlands)

    Mhatre, Eisha; Troszok, Agnieszka; Gallegos-Monterrosa, Ramses; Lindstädt, Stefanie; Hölscher, Theresa; Kuipers, Oscar P.; Kovács, Ákos T.

    2016-01-01

    Bacterial biofilms are dynamic and structurally complex communities, involving cell-to-cell interactions. In recent years, various environmental signals were identified that induce the complex biofilm development of the Gram-positive bacterium Bacillus subtilis. These signaling molecules are often

  8. Genotype-Dependent Effect of Exogenous Nitric Oxide on Cd-induced Changes in Antioxidative Metabolism, Ultrastructure, and Photosynthetic Performance in Barley Seedlings (Hordeum vulgare)

    DEFF Research Database (Denmark)

    Chen, Fei; Wang, Fang; Sun, Hongyan

    2010-01-01

    M Cd increased the accumulation of O2•-, H2O2, and malondialdehyde (MDA) but reduced plant height, chlorophyll content, net photosynthetic rate (P n), and biomass, with a much more severe response in the Cd-sensitive genotype. Antioxidant enzyme activities increased significantly under Cd stress......A greenhouse hydroponic experiment was performed using Cd-sensitive (cv. Dong 17) and Cd-tolerant (Weisuobuzhi) barley seedlings to evaluate how different genotypes responded to cadmium (Cd) toxicity in the presence of sodium nitroprusside (SNP), a nitric oxide (NO) donor. Results showed that 5 μ...... in the roots of the tolerant genotype, whereas in leaves of the sensitive genotype, superoxide dismutase (SOD) and ascorbate peroxide (APX), especially cytosol ascorbate peroxidase (cAPX), decreased after 5-15 days Cd exposure. Moreover, Cd induces NO synthesis by stimulating nitrate reductase and nitric oxide...

  9. Evaluation of single and joint toxic effects of diuron and its main metabolites on natural phototrophic biofilms using a pollution-induced community tolerance (PICT) approach.

    Science.gov (United States)

    Pesce, Stéphane; Lissalde, Sophie; Lavieille, Delphine; Margoum, Christelle; Mazzella, Nicolas; Roubeix, Vincent; Montuelle, Bernard

    2010-09-15

    This study assessed the single and joint acute toxicity of diuron and two of its metabolites (DCPMU and 3,4-DCA) on natural phototrophic biofilms using a PICT approach with photosynthesis bioassays. River biofilm communities were collected at three sampling stations exhibiting increasing concentrations of diuron, DCPMU and 3,4-DCA from upstream to downstream. Applied individually, the parent compound was more toxic than its metabolites, with DCPMU being more toxic than 3,4-DCA which only inhibited photosynthesis at very high concentrations (EC25 at about 5 mg/l). Sensitivity of biofilm communities to diuron and DCPMU decreased from upstream to downstream, revealing tolerance induction in contaminated sections of the river, as expected from the PICT concept. Nevertheless, PICT was not applicable for 3,4-DCA, which similarly affected upstream, intermediate and downstream biofilm communities. Chemical mixtures of diuron and DCPMU demonstrated additive effects whereas combinations with 3,4-DCA enhanced the observed effects. Our results reveal that the individual and combined presence of diuron and DCPMU in lotic ecosystems can have both short-term effects (as shown with bioassays) and long-term effects (as shown through the PICT approach) on phototrophic biofilms, whereas environmental concentrations of 3,4-DCA may not affect biofilm photosynthetic activity. 2010 Elsevier B.V. All rights reserved.

  10. Effect of antibiotics on cellular stress generated in Shiga toxin-producing Escherichia coli O157:H7 and non-O157 biofilms.

    Science.gov (United States)

    Angel Villegas, Natalia; Baronetti, José; Albesa, Inés; Etcheverría, Analía; Becerra, M Cecilia; Padola, Nora L; Paraje, M Gabriela

    2015-10-01

    Shiga toxin-producing Escherichia coli (STEC) are important food-borne pathogens, with the main virulence factor of this bacterium being its capacity to secrete Shiga toxins (Stxs). Therefore, the use of certain antibiotics for the treatment of this infection, which induces the liberation of Stxs, is controversial. Reactive oxygen and nitrogen species are also involved in the pathogenesis of different diseases. The purpose of this study was to analyze the effects of antibiotics on biofilms of STEC and the relationships between cellular stress and the release of Stx. To this end, biofilms of reference and clinical strains were treated with antibiotics (ciprofloxacin, fosfomycin and rifaximin) and the production of oxidants, the antioxidant defense system and toxin release were evaluated. Ciprofloxacin altered the prooxidant-antioxidant balance, with a decrease of oxidant metabolites and an increase of superoxide dismutase and catalase activity, being associated with high-levels of Stx production. Furthermore, inhibition of oxidative stress by exogenous antioxidants was correlated with a reduction in the liberation of Stx, indicating the participation of this phenomenon in the release of this toxin. In contrast, fosfomycin and rifaximin produced less alteration with a minimal production of Stx. Our data show that treatment of biofilm-STEC with these antibiotics induces oxidative stress-mediated release of Stx. Copyright © 2015 Elsevier Ltd. All rights reserved.

  11. Neuronal Rat Brain Damage Caused by Endogenous and Exogenous Hyperthermia

    Directory of Open Access Journals (Sweden)

    Mustafa Aydın

    2012-03-01

    Full Text Available OBJECTIVE: Hyperthermia may induce pathologic alterations within body systems and organs including brain. In this study, neuronal effects of endogenous and exogenous hyperthermia (41°C were studied in rats. METHODS: The endogenous hyperthermia (41°C was induced by lipopolysaccharide and the exogenous by an (electric heater. Possible neuronal damage was evaluated by examining healthy, apoptotic and necrotic cells, and heat shock proteins (HSP 27, HSP 70 in the cerebral cortex, cerebellum and hypothalamus RESULTS: At cellular level, when all neuronal tissues are taken into account; (i a significant increase in the necrotic cells was observed in the both groups (p0.05. CONCLUSION: The neural tissue of brain can show different degree of response to hyperthermia. But we can conclude that endogenous hyperthermia is more harmful to central nervous system than exogenous hyperthermia

  12. Diet-induced obesity, exogenous leptin-, and MADB106 tumor cell challenge affect tissue leukocyte distribution and serum levels of cytokines in F344 rats.

    Science.gov (United States)

    Behrendt, Patrick; Buchenauer, Tobias; Horn, Rüdiger; Brabant, Georg; Jacobs, Roland; Bode, Felix; Stephan, Michael; Nave, Heike

    2010-08-01

    The adipocyte-derived catabolic protein leptin alters cell-mediated immunity and cytokine crosstalk. This may provide new insights into the altered immune response, seen in obese individuals. Therefore, we determined the tissue distribution of immune cells in diet-induced obese (dio) and normal weight F344 rats challenged with MADB106 tumor cells or leptin. Immune cell distribution in blood (by FACS analysis) and tissues (NK cells in spleen and liver, immunohistologically) as well as pro-inflammatory cytokines (IL-6, TNF-α; by flow cytometry) were investigated in 28 normal weight and 28 dio rats (n = 4-6/group). Pro-inflammatory cytokines were increased 3-fold for IL-6 and 7-fold for TNF-α in obese animals. Higher numbers of blood monocytes and NK cells were found in obese as compared to normal weight animals. In dio rats challenged with leptin and MADB106 tumor cells, monocyte numbers were decreased as compared to the obese control animals. Immunohistochemistry revealed an altered NK cell distribution in a compartment-, treatment-, and bodyweight-specific manner. In conclusion, our data reveal a distinct distribution pattern of monocytes and NK cells in dio rats as compared to normal weight littermates and an additional modulatory effect of a leptin- and MADB106 tumor cell challenge.

  13. Exogenous glucagon-like peptide-1 reduces body weight and cholecystokinin-8 enhances this reduction in diet-induced obese male rats.

    Science.gov (United States)

    Mhalhal, Thaer R; Washington, Martha C; Newman, Kayla; Heath, John C; Sayegh, Ayman I

    2017-10-01

    The sites of action regulating meal size (MS) and intermeal interval (IMI) length by glucagon like peptide-1 (7-36) (GLP-1 (7-36)) and cholecystokinin-8 (CCK-8) reside in the areas supplied by the two major branches of the abdominal aorta, celiac and cranial mesenteric arteries. We hypothesized that infusing GLP-1 near those sites reduces body weight (BW) and adding CCK-8 to this infusion enhances the reduction. Here, we measured BW in diet-induced obese (DIO) male rats maintained and tested on normal rat chow and infused with saline, GLP-1 (0.5nmol/kg) and GLP-1+CCK-8 (0.5nmol/kg each) in the aorta once daily for 21days. We found that GLP-1 and GLP-1+CCK-8 decrease BW relative to saline vehicle and GLP-1+CCK-8 reduced it more than GLP-1 alone. Reduction of BW by GLP-1 alone was accompanied by decreased 24-h food intake, first MS, duration of first meal and number of meals, and an increase in latency to first meal. Reduction of BW by the combination of the peptides was accompanied by decrease 24-h food intake, first MS, duration of first meal and number of meals, and increase in the IMI length, satiety ratio and latency to first meal. In conclusion, GLP-1 reduces BW and CCK-8 enhances this reduction if the peptides are given near their sites of action. Copyright © 2017 Elsevier Inc. All rights reserved.

  14. Exogenous application of the plant signalers methyl jasmonate and salicylic acid induces changes in volatile emissions from citrus foliage and influences the aggregation behavior of Asian citrus psyllid (Diaphorina citri, vector of Huanglongbing.

    Directory of Open Access Journals (Sweden)

    Joseph M Patt

    Full Text Available Huanglongbing, also known as citrus greening, is a destructive disease that threatens citrus production worldwide. It is putatively caused by the phloem-limited bacterium Candidatus Liberibacter asiaticus (Las. Currently, the disease is untreatable and efforts focus on intensive insecticide use to control the vector, Asian citrus psyllid (Diaphorina citri. Emerging psyllid resistance to multiple insecticides has generated investigations into the use of exogenously applied signaling compounds to enhance citrus resistance to D. citri and Las. In the present study, we examined whether foliar applications of methyl jasmonate (MJ, a volatile signaling compound associated with the induced systemic resistance pathway, and salicylic acid, a constituent of the systemic acquired resistance pathway, would elicit the emission of defense-related volatiles in citrus foliage, and what effect this might have on the host-plant searching behavior of D. citri. Comparisons were made of volatiles emitted from growing shoots of uninfected and Las-infected 'Valencia' sweet orange (Citrus sinensis trees over two consecutive sampling days. A settling behavioral assay was used to compare psyllid attraction to MJ-treated vs. Tween-treated citrus sprigs. All three main effects, Las infection status, plant signaler application, and sampling day, influenced the proportions of individual volatile compounds emitted in different treatment groups. MJ- and SA-treated trees had higher emission rates than Tween-treated trees. Methyl salicylate (MeSA and β-caryophyllene were present in higher proportions in the volatiles collected from Las-infected + trees. On the other hand, Las-infected + MJ-treated trees emitted lower proportions of MeSA than did Las-infected + Tween-treated trees. Because MeSA is a key D. citri attractant, this result suggests that MJ application could suppress MeSA emission from Las-infected trees, an approach that could be used to discourage psyllid

  15. Exogenous application of the plant signalers methyl jasmonate and salicylic acid induces changes in volatile emissions from citrus foliage and influences the aggregation behavior of Asian citrus psyllid (Diaphorina citri), vector of Huanglongbing.

    Science.gov (United States)

    Patt, Joseph M; Robbins, Paul S; Niedz, Randy; McCollum, Greg; Alessandro, Rocco

    2018-01-01

    Huanglongbing, also known as citrus greening, is a destructive disease that threatens citrus production worldwide. It is putatively caused by the phloem-limited bacterium Candidatus Liberibacter asiaticus (Las). Currently, the disease is untreatable and efforts focus on intensive insecticide use to control the vector, Asian citrus psyllid (Diaphorina citri). Emerging psyllid resistance to multiple insecticides has generated investigations into the use of exogenously applied signaling compounds to enhance citrus resistance to D. citri and Las. In the present study, we examined whether foliar applications of methyl jasmonate (MJ), a volatile signaling compound associated with the induced systemic resistance pathway, and salicylic acid, a constituent of the systemic acquired resistance pathway, would elicit the emission of defense-related volatiles in citrus foliage, and what effect this might have on the host-plant searching behavior of D. citri. Comparisons were made of volatiles emitted from growing shoots of uninfected and Las-infected 'Valencia' sweet orange (Citrus sinensis) trees over two consecutive sampling days. A settling behavioral assay was used to compare psyllid attraction to MJ-treated vs. Tween-treated citrus sprigs. All three main effects, Las infection status, plant signaler application, and sampling day, influenced the proportions of individual volatile compounds emitted in different treatment groups. MJ- and SA-treated trees had higher emission rates than Tween-treated trees. Methyl salicylate (MeSA) and β-caryophyllene were present in higher proportions in the volatiles collected from Las-infected + trees. On the other hand, Las-infected + MJ-treated trees emitted lower proportions of MeSA than did Las-infected + Tween-treated trees. Because MeSA is a key D. citri attractant, this result suggests that MJ application could suppress MeSA emission from Las-infected trees, an approach that could be used to discourage psyllid colonization during

  16. Exogenous application of the plant signalers methyl jasmonate and salicylic acid induces changes in volatile emissions from citrus foliage and influences the aggregation behavior of Asian citrus psyllid (Diaphorina citri), vector of Huanglongbing

    Science.gov (United States)

    Robbins, Paul S.; Niedz, Randy; McCollum, Greg; Alessandro, Rocco

    2018-01-01

    Huanglongbing, also known as citrus greening, is a destructive disease that threatens citrus production worldwide. It is putatively caused by the phloem-limited bacterium Candidatus Liberibacter asiaticus (Las). Currently, the disease is untreatable and efforts focus on intensive insecticide use to control the vector, Asian citrus psyllid (Diaphorina citri). Emerging psyllid resistance to multiple insecticides has generated investigations into the use of exogenously applied signaling compounds to enhance citrus resistance to D. citri and Las. In the present study, we examined whether foliar applications of methyl jasmonate (MJ), a volatile signaling compound associated with the induced systemic resistance pathway, and salicylic acid, a constituent of the systemic acquired resistance pathway, would elicit the emission of defense-related volatiles in citrus foliage, and what effect this might have on the host-plant searching behavior of D. citri. Comparisons were made of volatiles emitted from growing shoots of uninfected and Las-infected ‘Valencia’ sweet orange (Citrus sinensis) trees over two consecutive sampling days. A settling behavioral assay was used to compare psyllid attraction to MJ-treated vs. Tween-treated citrus sprigs. All three main effects, Las infection status, plant signaler application, and sampling day, influenced the proportions of individual volatile compounds emitted in different treatment groups. MJ- and SA-treated trees had higher emission rates than Tween-treated trees. Methyl salicylate (MeSA) and β-caryophyllene were present in higher proportions in the volatiles collected from Las-infected + trees. On the other hand, Las-infected + MJ-treated trees emitted lower proportions of MeSA than did Las-infected + Tween-treated trees. Because MeSA is a key D. citri attractant, this result suggests that MJ application could suppress MeSA emission from Las-infected trees, an approach that could be used to discourage psyllid colonization during

  17. Pseudomonas aeruginosa biofilm infections

    DEFF Research Database (Denmark)

    Tolker-Nielsen, Tim

    2014-01-01

    Bacteria in natural, industrial and clinical settings predominantly live in biofilms, i.e., sessile structured microbial communities encased in self-produced extracellular matrix material. One of the most important characteristics of microbial biofilms is that the resident bacteria display...... a remarkable increased tolerance toward antimicrobial attack. Biofilms formed by opportunistic pathogenic bacteria are involved in devastating persistent medical device-associated infections, and chronic infections in individuals who are immune-compromised or otherwise impaired in the host defense. Because...... the use of conventional antimicrobial compounds in many cases cannot eradicate biofilms, there is an urgent need to develop alternative measures to combat biofilm infections. The present review is focussed on the important opportunistic pathogen and biofilm model organism Pseudomonas aeruginosa. Initially...

  18. Lipopeptide biosurfactant viscosin enhances dispersal of Pseudomonas fluorescens SBW25 biofilms.

    Science.gov (United States)

    Bonnichsen, Lise; Bygvraa Svenningsen, Nanna; Rybtke, Morten; de Bruijn, Irene; Raaijmakers, Jos M; Tolker-Nielsen, Tim; Nybroe, Ole

    2015-12-01

    Pseudomonads produce several lipopeptide biosurfactants that have antimicrobial properties but that also facilitate surface motility and influence biofilm formation. Detailed studies addressing the significance of lipopeptides for biofilm formation and architecture are rare. Hence, the present study sets out to determine the specific role of the lipopeptide viscosin in Pseudomonas fluorescens SBW25 biofilm formation, architecture and dispersal, and to relate viscA gene expression to viscosin production and effect. Initially, we compared biofilm formation of SBW25 and the viscosin-deficient mutant strain SBW25ΔviscA in static microtitre assays. These experiments demonstrated that viscosin had little influence on the amount of biofilm formed by SBW25 during the early stages of biofilm development. Later, however, SBW25 formed significantly less biofilm than SBW25ΔviscA. The indication that viscosin is involved in biofilm dispersal was confirmed by chemical complementation of the mutant biofilm. Furthermore, a fluorescent bioreporter showed that viscA expression was induced in biofilms 4 h prior to dispersal. Subsequent detailed studies of biofilms formed in flow cells for up to 5 days revealed that SBW25 and SBW25ΔviscA developed comparable biofilms dominated by well-defined, mushroom-shaped structures. Carbon starvation was required to obtain biofilm dispersal in this system. Dispersal of SBW25 biofilms was significantly greater than of SBW25ΔviscA biofilms after 3 h and, importantly, carbon starvation strongly induced viscA expression, in particular for cells that were apparently leaving the biofilm. Thus, the present study points to a role for viscosin-facilitated motility in dispersal of SBW25 biofilms.

  19. The efficacy of sewage influent-isolated bacteriophages on Pseudomonas aeruginosa in a mixed-species biofilm

    KAUST Repository

    Yap, Scott

    2016-01-01

    The growth of environmentally persistent biofilms in cooling towers causes several associated problems, including microbiologically-induced corrosion (MIC) and biofouling. Current chemical control methods are not only ineffective against biofilms

  20. Spermidine promotes Bacillus subtilis biofilm formation by activating expression of the matrix regulator slrR.

    Science.gov (United States)

    Hobley, Laura; Li, Bin; Wood, Jennifer L; Kim, Sok Ho; Naidoo, Jacinth; Ferreira, Ana Sofia; Khomutov, Maxim; Khomutov, Alexey; Stanley-Wall, Nicola R; Michael, Anthony J

    2017-07-21

    Ubiquitous polyamine spermidine is not required for normal planktonic growth of Bacillus subtilis but is essential for robust biofilm formation. However, the structural features of spermidine required for B. subtilis biofilm formation are unknown and so are the molecular mechanisms of spermidine-stimulated biofilm development. We report here that in a spermidine-deficient B. subtilis mutant, the structural analogue norspermidine, but not homospermidine, restored biofilm formation. Intracellular biosynthesis of another spermidine analogue, aminopropylcadaverine, from exogenously supplied homoagmatine also restored biofilm formation. The differential ability of C-methylated spermidine analogues to functionally replace spermidine in biofilm formation indicated that the aminopropyl moiety of spermidine is more sensitive to C -methylation, which it is essential for biofilm formation, but that the length and symmetry of the molecule is not critical. Transcriptomic analysis of a spermidine-depleted B. subtilis speD mutant uncovered a nitrogen-, methionine-, and S -adenosylmethionine-sufficiency response, resulting in repression of gene expression related to purine catabolism, methionine and S -adenosylmethionine biosynthesis and methionine salvage, and signs of altered membrane status. Consistent with the spermidine requirement in biofilm formation, single-cell analysis of this mutant indicated reduced expression of the operons for production of the exopolysaccharide and TasA protein biofilm matrix components and SinR antagonist slrR Deletion of sinR or ectopic expression of slrR in the spermidine-deficient Δ speD background restored biofilm formation, indicating that spermidine is required for expression of the biofilm regulator slrR Our results indicate that spermidine functions in biofilm development by activating transcription of the biofilm matrix exopolysaccharide and TasA operons through the regulator slrR . © 2017 by The American Society for Biochemistry and

  1. Neutrophil extracellular trap formation in supragingival biofilms.

    Science.gov (United States)

    Hirschfeld, Josefine; Dommisch, Henrik; Skora, Philipp; Horvath, Gabor; Latz, Eicke; Hoerauf, Achim; Waller, Tobias; Kawai, Toshihisa; Jepsen, Søren; Deschner, James; Bekeredjian-Ding, Isabelle

    2015-01-01

    Oral biofilms are the causative agents of the highly prevalent oral diseases periodontitis and caries. Additionally, the host immune response is thought to play a critical role in disease onset. Neutrophils are known to be a key host response factor to bacterial challenge on host surfaces. Release of neutrophil extracellular traps (NETs) as a novel antimicrobial defense strategy has gained increasing attention in the past years. Here, we investigated the influx of neutrophils into the dental plaque and the ability of oral bacteria to trigger intra-biofilm release of NETs and intracellular proteins. Supragingival biofilms and whole saliva were sampled from systemically healthy subjects participating in an experimental gingivitis study. Biofilms were analysed by immunofluorescence followed by confocal and fluorescence microscopy. Moreover, concentrations of cytokines and immune-associated proteins in biofilm suspensions and saliva were assessed by ELISA. Neutrophils obtained from blood were stimulated with twelve bacterial species isolated from cultured biofilms or with lipopolysaccharide to monitor NET formation. Neutrophils, NETs, neutrophil-associated proteins (myeloperoxidase, elastase-2, cathepsin G, cathelicidin LL-37), interleukin-8, interleukin-1β and tumor necrosis factor were detected within plaque samples and saliva. All tested bacterial species as well as the polymicrobial samples isolated from the plaque of each donor induced release of NETs and interleukin-8. The degree of NET formation varied among different subjects and did not correlate with plaque scores or clinical signs of local inflammation. Our findings indicate that neutrophils are attracted towards dental biofilms, in which they become incorporated and where they are stimulated by microbes to release NETs and immunostimulatory proteins. Thus, neutrophils and NETs may be involved in host biofilm control, although their specific role needs to be further elucidated. Moreover, inter

  2. An optical microfluidic platform for spatiotemporal biofilm treatment monitoring

    International Nuclear Information System (INIS)

    Kim, Young Wook; Mosteller, Matthew P; Subramanian, Sowmya; Meyer, Mariana T; Ghodssi, Reza; Bentley, William E

    2016-01-01

    Bacterial biofilms constitute in excess of 65% of clinical microbial infections, with the antibiotic treatment of biofilm infections posing a unique challenge due to their high antibiotic tolerance. Recent studies performed in our group have demonstrated that a bioelectric effect featuring low-intensity electric signals combined with antibiotics can significantly improve the efficacy of biofilm treatment. In this work, we demonstrate the bioelectric effect using sub-micron thick planar electrodes in a microfluidic device. This is critical in efforts to develop microsystems for clinical biofilm infection management, including both in vivo and in vitro applications. Adaptation of the method to the microscale, for example, can enable the development of localized biofilm infection treatment using microfabricated medical devices, while augmenting existing capabilities to perform biofilm management beyond the clinical realm. Furthermore, due to scale-down of the system, the voltage requirement for inducing the electric field is reduced further below the media electrolysis threshold. Enhanced biofilm treatment using the bioelectric effect in the developed microfluidic device elicited a 56% greater reduction in viable cell density and 26% further decrease in biomass growth compared to traditional antibiotic therapy. This biofilm treatment efficacy, demonstrated in a micro-scale device and utilizing biocompatible voltage ranges, encourages the use of this method for future clinical biofilm treatment applications. (paper)

  3. Electro-active bio-films: formation, characterization and mechanisms

    International Nuclear Information System (INIS)

    Parot, Sandrine

    2007-01-01

    Some bacteria, which are able to exchange electrons with a conductive material without mediator form on conductive surfaces electro-active bio-films. This bacterial property has been recently discovered (2001). Objectives of this work are to develop electro-active bio-films in various natural environments from indigenous flora, then through complementary electrochemical techniques (chrono-amperometry and cyclic voltammetry), to evaluate electro-activity of isolates coming from so-formed bio-films and to characterize mechanisms of electron transfer between bacteria and materials. First, electro-active bio-films have been developed under chrono-amperometry in garden compost and in water coming from Guyana mangrove. These bio-films were respectively able to use an electrode as electron acceptor (oxidation) or as electron donor (reduction). In compost, results obtained in chrono-amperometry and cyclic voltammetry suggest a two-step electron transfer: slow substrate consumption, then rapid electron transfer between bacteria and the electrode. Thereafter, the ability to reduce oxygen was demonstrated with cyclic voltammetry for facultative aerobic isolates from compost bio-films (Enterobacter spp. and Pseudomonas spp.) and for aerobic isolates obtained from marine electro-active bio-films (Roseobacter spp. in majority). Finally, bio-films inducing current increase in chrono-amperometry were developed in bioreactor with synthetic medium from a pure culture of isolates. Hence, for the first time, electro-activity of several anaerobic strains of Geobacter bremensis isolated from compost bio-films was highlighted. (author) [fr

  4. Effects of substrates on biofilm formation observed by atomic force microscopy

    International Nuclear Information System (INIS)

    Oh, Y.J.; Lee, N.R.; Jo, W.; Jung, W.K.; Lim, J.S.

    2009-01-01

    Formation of biofilm is known to be strongly dependent on substrates including topography, materials, and chemical treatment. In this study, a variety of substrates are tested for understanding biofilm formation. Sheets of aluminum, steel, rubber, and polypropylene have been used to examine their effects on formation of Pseudomonas aeruginosa biofilm. In particular, the morphological variation, transition, and adhesiveness of biofilm were investigated through local measurement by atomic force microscopy (AFM). Mechanism of removing biofilm from adhering to substrate is also analyzed, thus the understanding of the mechanism can be potentially useful to prevent the biofilm formation. The results reveal that formation of biofilm can remain on rough surface regardless of substrates in hot water, which may easily induce extra-polymeric substances detachment from bacterial surface. By probing using AFM, local force-distance characterization of extra-cellular materials extracted from the bacteria can exhibit the progress of the biofilm formation and functional complexities.

  5. Streptococcus suis Serotype 2 Biofilms Inhibit the Formation of Neutrophil Extracellular Traps.

    Science.gov (United States)

    Ma, Fang; Yi, Li; Yu, Ningwei; Wang, Guangyu; Ma, Zhe; Lin, Huixing; Fan, Hongjie

    2017-01-01

    Invasive infections caused by Streptococcus suis serotype 2 (SS2) has emerged as a clinical problem in recent years. Neutrophil extracellular traps (NETs) are an important mechanism for the trapping and killing of pathogens that are resistant to phagocytosis. Biofilm formation can protect bacteria from being killed by phagocytes. Until now, there have only been a few studies that focused on the interactions between bacterial biofilms and NETs. SS2 in both a biofilm state and a planktonic cell state were incubated with phagocytes and NETs, and bacterial survival was assessed. DNase I and cytochalasin B were used to degrade NET DNA or suppress phagocytosis, respectively. Extracellular DNA was stained with impermeable fluorescent dye to quantify NET formation. Biofilm formation increased up to 6-fold in the presence of neutrophils, and biofilms were identified in murine tissue. Both planktonic and biofilm cells induced neutrophils chemotaxis to the infection site, with neutrophils increasing by 85.1 and 73.8%, respectively. The bacteria in biofilms were not phagocytized. The bactericidal efficacy of NETs on the biofilms and planktonic cells were equal; however, the biofilm extracellular matrix can inhibit NET release. Although biofilms inhibit NETs release, NETs appear to be an important mechanism to eliminate SS2 biofilms. This knowledge advances the understanding of biofilms and may aid in the development of treatments for persistent infections with a biofilm component.

  6. Consequences and detection of invalid exogeneity conditions

    NARCIS (Netherlands)

    Niemczyk, J.

    2009-01-01

    Estimators for econometric relationships require observations on at least as many exogenous variables as the model has unknown coefficients. This thesis examines techniques to classify variables as being either exogenous or endogenous, and investigates the consequences of invalid classifications.

  7. Hydraulic resistance of biofilms

    KAUST Repository

    Dreszer, C.

    2013-02-01

    Biofilms may interfere with membrane performance in at least three ways: (i) increase of the transmembrane pressure drop, (ii) increase of feed channel (feed-concentrate) pressure drop, and (iii) increase of transmembrane passage. Given the relevance of biofouling, it is surprising how few data exist about the hydraulic resistance of biofilms that may affect the transmembrane pressure drop and membrane passage. In this study, biofilms were generated in a lab scale cross flow microfiltration system at two fluxes (20 and 100Lm-2h-1) and constant cross flow (0.1ms-1). As a nutrient source, acetate was added (1.0mgL-1 acetate C) besides a control without nutrient supply. A microfiltration (MF) membrane was chosen because the MF membrane resistance is very low compared to the expected biofilm resistance and, thus, biofilm resistance can be determined accurately. Transmembrane pressure drop was monitored. As biofilm parameters, thickness, total cell number, TOC, and extracellular polymeric substances (EPS) were determined, it was demonstrated that no internal membrane fouling occurred and that the fouling layer actually consisted of a grown biofilm and was not a filter cake of accumulated bacterial cells. At 20Lm-2h-1 flux with a nutrient dosage of 1mgL-1 acetate C, the resistance after 4 days reached a value of 6×1012m-1. At 100Lm-2h-1 flux under the same conditions, the resistance was 5×1013m-1. No correlation of biofilm resistance to biofilm thickness was found; Biofilms with similar thickness could have different resistance depending on the applied flux. The cell number in biofilms was between 4×107 and 5×108 cellscm-2. At this number, bacterial cells make up less than a half percent of the overall biofilm volume and therefore did not hamper the water flow through the biofilm significantly. A flux of 100Lm-2h-1 with nutrient supply caused higher cell numbers, more biomass, and higher biofilm resistance than a flux of 20Lm-2h-1. However, the biofilm thickness

  8. Calcium transcriptionally regulates the biofilm machinery of Xylella fastidiosa to promote continued biofilm development in batch cultures.

    Science.gov (United States)

    Parker, Jennifer K; Chen, Hongyu; McCarty, Sara E; Liu, Lawrence Y; De La Fuente, Leonardo

    2016-05-01

    The functions of calcium (Ca) in bacteria are less characterized than in eukaryotes, where its role has been studied extensively. The plant-pathogenic bacterium Xylella fastidiosa has several virulence features that are enhanced by increased Ca concentrations, including biofilm formation. However, the specific mechanisms driving modulation of this feature are unclear. Characterization of biofilm formation over time showed that 4 mM Ca supplementation produced denser biofilms that were still developing at 96 h, while biofilm in non-supplemented media had reached the dispersal stage by 72 h. To identify changes in global gene expression in X. fastidiosa grown in supplemental Ca, RNA-Seq of batch culture biofilm cells was conducted at three 24-h time intervals. Results indicate that a variety of genes are differentially expressed in response to Ca, including genes related to attachment, motility, exopolysaccharide synthesis, biofilm formation, peptidoglycan synthesis, regulatory functions, iron homeostasis, and phages. Collectively, results demonstrate that Ca supplementation induces a transcriptional response that promotes continued biofilm development, while biofilm cells in nonsupplemented media are driven towards dispersion of cells from the biofilm structure. These results have important implications for disease progression in planta, where xylem sap is the source of Ca and other nutrients for X. fastidiosa. © 2016 Society for Applied Microbiology and John Wiley & Sons Ltd.

  9. Endogenous and Exogenous Attention Shifts are Mediated by the Same Large-Scale Neural Network.

    NARCIS (Netherlands)

    Peelen, M.V.; Heslenfeld, D.J.; Theeuwes, J.

    2004-01-01

    Event-related fMRI was used to examine the neural basis of endogenous (top-down) and exogenous (bottom-up) spatial orienting. Shifts of attention were induced by central (endogenous) or peripheral (exogenous) cues. Reaction times on subsequently presented targets showed the expected pattern of

  10. Exogenic and endogenic Europa minerals

    Science.gov (United States)

    Maynard-Casely, H. E.; Brand, H. E. A.; Wilson, S. A.

    2016-12-01

    The Galileo Near Infrared Mapping Spectrometer (NIMS) identified a significant `non-ice' component upon the surface of Jupiter's moon Europa. Current explanations invoke both endogenic and exogenic origins for this material. It has long been suggested that magnesium and sodium sulfate minerals could have leached from the rock below a putative ocean (endogenic) 1 and that sulfuric acid hydrate minerals could have been radiologically produced from ionised sulfur originally from Io's volcanoes (exogenic) 2. However, a more recent theory proposes that the `non-ice' component could be radiation damaged NaCl leached from Europa's speculative ocean 3. What if the minerals are actually from combination of both endogenic and exogenic sources? To investigate this possibility we have focused on discovering new minerals that might form in the combination of the latter two cases, that is a mixture of leached sulfates hydrates with radiologically produced sulfuric acid. To this end we have explored a number of solutions in the MgSO4-H2SO4-H2O and Na2SO4-H2SO4-H2O systems, between 80 and 280 K with synchrotron x-ray powder diffraction. We report a number of new materials formed in this these ternary systems. This suggests that it should be considered that the `non-ice' component of the Europa's surface could be a material derived from endogenic and exogenic components. 1 Kargel, J. S. Brine volcanism and the interior structures of asteroids and icy satellites. Icarus 94, 368-390 (1991). 2 Carlson, R. W., Anderson, M. S., Mehlman, R. & Johnson, R. E. Distribution of hydrate on Europa: Further evidence for sulfuric acid hydrate. Icarus 177, 461-471, doi:10.1016/j.icarus.2005.03.026 (2005). 3 Hand, K. P. & Carlson, R. W. Europa's surface color suggests an ocean rich with sodium chloride. Geophysical Research Letters, 2015GL063559, doi:10.1002/2015gl063559 (2015).

  11. Meningococcal biofilm formation

    DEFF Research Database (Denmark)

    Lappann, M.; Haagensen, Janus Anders Juul; Claus, H.

    2006-01-01

    We show that in a standardized in vitro flow system unencapsulated variants of genetically diverse lineages of Neisseria meningitidis formed biofilms, that could be maintained for more than 96 h. Biofilm cells were resistant to penicillin, but not to rifampin or ciprofloxacin. For some strains......, microcolony formation within biofilms was observed. Microcolony formation in strain MC58 depended on a functional copy of the pilE gene encoding the pilus subunit pilin, and was associated with twitching of cells. Nevertheless, unpiliated pilE mutants formed biofilms showing that attachment and accumulation......X alleles was identified among genetically diverse meningococcal strains. PilX alleles differed in their propensity to support autoaggregation of cells in suspension, but not in their ability to support microcolony formation within biofilms in the continuous flow system....

  12. Biofilms in wounds

    DEFF Research Database (Denmark)

    Cooper, R A; Bjarnsholt, Thomas; Alhede, M

    2014-01-01

    Following confirmation of the presence of biofilms in chronic wounds, the term biofilm became a buzzword within the wound healing community. For more than a century pathogens have been successfully isolated and identified from wound specimens using techniques that were devised in the nineteenth...... extracellular polymeric substances (EPS). Cells within such aggregations (or biofilms) display varying physiological and metabolic properties that are distinct from those of planktonic cells, and which contribute to their persistence. There are many factors that influence healing in wounds and the discovery...... of biofilms in chronic wounds has provided new insight into the reasons why. Increased tolerance of biofilms to antimicrobial agents explains the limited efficacy of antimicrobial agents in chronic wounds and illustrates the need to develop new management strategies. This review aims to explain the nature...

  13. Understanding the fundamental mechanisms of biofilms development and dispersal: BIAM (Biofilm Intensity and Architecture Measurement), a new tool for studying biofilms as a function of their architecture and fluorescence intensity.

    Science.gov (United States)

    Baudin, Marine; Cinquin, Bertrand; Sclavi, Bianca; Pareau, Dominique; Lopes, Filipa

    2017-09-01

    Confocal laser scanning microscopy (CLSM) is one of the most relevant technologies for studying biofilms in situ. Several tools have been developed to investigate and quantify the architecture of biofilms. However, an approach to quantify correctly the evolution of intensity of a fluorescent signal as a function of the structural parameters of a biofilm is still lacking. Here we present a tool developed in the ImageJ open source software that can be used to extract both structural and fluorescence intensity from CLSM data: BIAM (Biofilm Intensity and Architecture Measurement). This is of utmost significance when studying the fundamental mechanisms of biofilm growth, differentiation and development or when aiming to understand the effect of external molecules on biofilm phenotypes. In order to provide an example of the potential of such a tool in this study we focused on biofilm dispersion. cis-2-Decenoic acid (CDA) is a molecule known to induce biofilm dispersion of multiple bacterial species. The mechanisms by which CDA induces dispersion are still poorly understood. To investigate the effects of CDA on biofilms, we used a reporter strain of Escherichia coli (E. coli) that expresses the GFPmut2 protein under control of the rrnBP1 promoter. Experiments were done in flow cells and image acquisition was made with CLSM. Analysis carried out using the new tool, BIAM, indicates that CDA affects the fluorescence intensity of the biofilm structures as well as biofilm architectures. Indeed, our results demonstrate that CDA removes more than 35% of biofilm biovolume and suggest that it results in an increase of the biofilm's mean fluorescence intensity (MFI) by more than 26% compared to the control biofilm in the absence of CDA. Copyright © 2017. Published by Elsevier B.V.

  14. Starvation, Together with the SOS Response, Mediates High Biofilm-Specific Tolerance to the Fluoroquinolone Ofloxacin

    Science.gov (United States)

    Bernier, Steve P.; Lebeaux, David; DeFrancesco, Alicia S.; Valomon, Amandine; Soubigou, Guillaume; Coppée, Jean-Yves; Ghigo, Jean-Marc; Beloin, Christophe

    2013-01-01

    High levels of antibiotic tolerance are a hallmark of bacterial biofilms. In contrast to well-characterized inherited antibiotic resistance, molecular mechanisms leading to reversible and transient antibiotic tolerance displayed by biofilm bacteria are still poorly understood. The physiological heterogeneity of biofilms influences the formation of transient specialized subpopulations that may be more tolerant to antibiotics. In this study, we used random transposon mutagenesis to identify biofilm-specific tolerant mutants normally exhibited by subpopulations located in specialized niches of heterogeneous biofilms. Using Escherichia coli as a model organism, we demonstrated, through identification of amino acid auxotroph mutants, that starved biofilms exhibited significantly greater tolerance towards fluoroquinolone ofloxacin than their planktonic counterparts. We demonstrated that the biofilm-associated tolerance to ofloxacin was fully dependent on a functional SOS response upon starvation to both amino acids and carbon source and partially dependent on the stringent response upon leucine starvation. However, the biofilm-specific ofloxacin increased tolerance did not involve any of the SOS-induced toxin–antitoxin systems previously associated with formation of highly tolerant persisters. We further demonstrated that ofloxacin tolerance was induced as a function of biofilm age, which was dependent on the SOS response. Our results therefore show that the SOS stress response induced in heterogeneous and nutrient-deprived biofilm microenvironments is a molecular mechanism leading to biofilm-specific high tolerance to the fluoroquinolone ofloxacin. PMID:23300476

  15. Shell biofilm-associated nitrous oxide production in marine molluscs

    DEFF Research Database (Denmark)

    Heisterkamp, I.M.; Schramm, Andreas; Larsen, Lone Heimann

    2013-01-01

    Emission of the greenhouse gas nitrous oxide (N2O) from freshwater and terrestrial invertebrates has exclusively been ascribed to N2O production by ingested denitrifying bacteria in the anoxic gut of the animals. Our study of marine molluscs now shows that also microbial biofilms on shell surfaces...... are important sites of N2O production. The shell biofilms of Mytilus edulis, Littorina littorea and Hinia reticulata contributed 18-94% to the total animal-associated N2O emission. Nitrification and denitrification were equally important sources of N2O in shell biofilms as revealed by 15N-stable isotope...... mollusc species. Ammonium excretion by the animals was found to be sufficient to sustain N2O production in the shell biofilm. Apparently, the animals provide a nutrient-enriched microenvironment that stimulates growth and N2O production of the shell biofilm. This animal-induced stimulation...

  16. Evidence for biofilm acid neutralization by baking soda.

    Science.gov (United States)

    Zero, Domenick T

    2017-11-01

    The generating of acids from the microbial metabolism of dietary sugars and the subsequent decrease in biofilm pH below the pH at which tooth mineral begins to demineralize (critical pH) are the key elements of the dental caries process. Caries preventive strategies that rapidly neutralize biofilm acids can prevent demineralization and favor remineralization and may help prevent the development of sugar-induced dysbiosis that shifts the biofilm toward increased cariogenic potential. Although the neutralizing ability of sodium bicarbonate (baking soda) has been known for many years, its anticaries potential as an additive to fluoride dentifrice has received only limited investigation. There is evidence that baking soda rapidly can reverse the biofilm pH decrease after a sugar challenge; however, the timing of when it is used in relation to a dietary sugar exposure is critical in that the sooner its used the greater the benefit in preventing a sustained biofilm pH decrease and subsequent demineralization. Furthermore, the effectiveness of baking soda in elevating biofilm pH appears to depend on concentration. Thus, the concentration of baking soda in marketed dentifrice products, which ranges from 10% to 65%, may affect their biofilm pH neutralizing performance. People with hyposalivation particularly may benefit from using fluoride dentifrice containing baking soda because of their diminished ability to clear dietary sugars and buffer biofilm acids. Although promising, there is the need for more evidence that strategies that modify the oral ecology, such as baking soda, can alter the cariogenic (acidogenic and aciduric) properties of biofilm microorganisms. The acid neutralization of dental biofilm by using fluoride dentifrice that contains baking soda has potential for helping counteract modern high-sugar diets by rapidly neutralizing biofilm-generated acid, especially in people with hyposalivation. Copyright © 2017 American Dental Association. Published by

  17. Resistance of biofilm-covered mortars to microbiologically influenced deterioration simulated by sulfuric acid exposure

    Energy Technology Data Exchange (ETDEWEB)

    Soleimani, Sahar, E-mail: ssoleima@connect.carleton.ca; Isgor, O. Burkan, E-mail: burkan_isgor@carleton.ca; Ormeci, Banu, E-mail: banu_ormeci@carleton.ca

    2013-11-15

    Following the reported success of biofilm applications on metal surfaces to inhibit microbiologically influenced corrosion, effectiveness and sustainability of E. coli DH5α biofilm on mortar surface to prevent microbiologically influenced concrete deterioration (MICD) are investigated. Experiments simulating microbial attack were carried out by exposing incrementally biofilm-covered mortar specimens to sulfuric acid solutions with pH ranging from 3 to 6. Results showed that calcium concentration in control reactors without biofilm was 23–47% higher than the reactors with biofilm-covered mortar. Formation of amorphous silica gel as an indication of early stages of acid attack was observed only on the control mortar specimens without biofilm. During acidification, the biofilm continued to grow and its thickness almost doubled from ∼ 30 μm before acidification to ∼ 60 μm after acidification. These results demonstrated that E. coli DH5α biofilm was able to provide a protective and sustainable barrier on mortar surfaces against medium to strong sulfuric acid attack. -- Highlights: •Effectiveness of E.coli DH5α biofilm to prevent MICD was studied. •Conditions that lead to MICD were simulated by chemical acidification. •Biofilm-covered mortar specimens were exposed to sulfuric acid solutions. •The presence of biofilm helped reduce the chemically-induced mortar deterioration. •Biofilm remained alive and continued to grow during the acidification process.

  18. Resistance of biofilm-covered mortars to microbiologically influenced deterioration simulated by sulfuric acid exposure

    International Nuclear Information System (INIS)

    Soleimani, Sahar; Isgor, O. Burkan; Ormeci, Banu

    2013-01-01

    Following the reported success of biofilm applications on metal surfaces to inhibit microbiologically influenced corrosion, effectiveness and sustainability of E. coli DH5α biofilm on mortar surface to prevent microbiologically influenced concrete deterioration (MICD) are investigated. Experiments simulating microbial attack were carried out by exposing incrementally biofilm-covered mortar specimens to sulfuric acid solutions with pH ranging from 3 to 6. Results showed that calcium concentration in control reactors without biofilm was 23–47% higher than the reactors with biofilm-covered mortar. Formation of amorphous silica gel as an indication of early stages of acid attack was observed only on the control mortar specimens without biofilm. During acidification, the biofilm continued to grow and its thickness almost doubled from ∼ 30 μm before acidification to ∼ 60 μm after acidification. These results demonstrated that E. coli DH5α biofilm was able to provide a protective and sustainable barrier on mortar surfaces against medium to strong sulfuric acid attack. -- Highlights: •Effectiveness of E.coli DH5α biofilm to prevent MICD was studied. •Conditions that lead to MICD were simulated by chemical acidification. •Biofilm-covered mortar specimens were exposed to sulfuric acid solutions. •The presence of biofilm helped reduce the chemically-induced mortar deterioration. •Biofilm remained alive and continued to grow during the acidification process

  19. Synergistic Interactions within a Multispecies Biofilm Enhance Individual Species Protection against Grazing by a Pelagic Protozoan

    Directory of Open Access Journals (Sweden)

    Prem K. Raghupathi

    2018-01-01

    Full Text Available Biofilm formation has been shown to confer protection against grazing, but little information is available on the effect of grazing on biofilm formation and protection in multispecies consortia. With most biofilms in nature being composed of multiple bacterial species, the interactions and dynamics of a multispecies bacterial biofilm subject to grazing by a pelagic protozoan predator were investigated. To this end, a mono and multispecies biofilms of four bacterial soil isolates, namely Xanthomonas retroflexus, Stenotrophomonas rhizophila, Microbacterium oxydans and Paenibacillus amylolyticus, were constructed and subjected to grazing by the ciliate Tetrahymena pyriformis. In monocultures, grazing strongly reduced planktonic cell numbers in P. amylolyticus and S. rhizophila and also X. retroflexus. At the same time, cell numbers in the underlying biofilms increased in S. rhizophila and X. retroflexus, but not in P. amylolyticus. This may be due to the fact that while grazing enhanced biofilm formation in the former two species, no biofilm was formed by P. amylolyticus in monoculture, either with or without grazing. In four-species biofilms, biofilm formation was higher than in the best monoculture, a strong biodiversity effect that was even more pronounced in the presence of grazing. While cell numbers of X. retroflexus, S. rhizophila, and P. amylolyticus in the planktonic fraction were greatly reduced in the presence of grazers, cell numbers of all three species strongly increased in the biofilm. Our results show that synergistic interactions between the four-species were important to induce biofilm formation, and suggest that bacterial members that produce more biofilm when exposed to the grazer not only protect themselves but also supported other members which are sensitive to grazing, thereby providing a “shared grazing protection” within the four-species biofilm model. Hence, complex interactions shape the dynamics of the biofilm and

  20. Interspecies interactions result in enhanced biofilm formation by co-cultures of bacteria isolated from a food processing environment

    DEFF Research Database (Denmark)

    Røder, Henriette Lyng; Raghupathi, Prem Krishnan; Herschend, Jakob

    2015-01-01

    Bacterial attachment and biofilm formation can lead to poor hygienic conditions in food processing environments. Furthermore, interactions between different bacteria may induce or promote biofilm formation. In this study, we isolated and identified a total of 687 bacterial strains from seven......-culture biofilm production with high relevance for food safety and food production facilities....

  1. Transcriptomic and proteomic analyses of Desulfovibrio vulgaris biofilms: carbon and energy flow contribute to the distinct biofilm growth state.

    Science.gov (United States)

    Clark, Melinda E; He, Zhili; Redding, Alyssa M; Joachimiak, Marcin P; Keasling, Jay D; Zhou, Jizhong Z; Arkin, Adam P; Mukhopadhyay, Aindrila; Fields, Matthew W

    2012-04-16

    . Even though both the planktonic and biofilm cells were oxidizing lactate and reducing sulfate, the biofilm cells were physiologically distinct compared to planktonic growth states due to altered abundances of genes/proteins involved in carbon/energy flow and extracellular structures. In addition, average expression values for multiple rRNA transcripts and respiratory activity measurements indicated that biofilm cells were metabolically more similar to exponential-phase cells although biofilm cells are structured differently. The characterization of physiological advantages and constraints of the biofilm growth state for sulfate-reducing bacteria will provide insight into bioremediation applications as well as microbially-induced metal corrosion.

  2. Studying bacterial multispecies biofilms

    DEFF Research Database (Denmark)

    Røder, Henriette Lyng; Sørensen, Søren Johannes; Burmølle, Mette

    2016-01-01

    The high prevalence and significance of multispecies biofilms have now been demonstrated in various bacterial habitats with medical, industrial, and ecological relevance. It is highly evident that several species of bacteria coexist and interact in biofilms, which highlights the need for evaluating...... the approaches used to study these complex communities. This review focuses on the establishment of multispecies biofilms in vitro, interspecies interactions in microhabitats, and how to select communities for evaluation. Studies have used different experimental approaches; here we evaluate the benefits...... and drawbacks of varying the degree of complexity. This review aims to facilitate multispecies biofilm research in order to expand the current limited knowledge on interspecies interactions. Recent technological advances have enabled total diversity analysis of highly complex and diverse microbial communities...

  3. Compaction and relaxation of biofilms

    KAUST Repository

    Valladares Linares, R.

    2015-06-18

    Operation of membrane systems for water treatment can be seriously hampered by biofouling. A better characterization of biofilms in membrane systems and their impact on membrane performance may help to develop effective biofouling control strategies. The objective of this study was to determine the occurrence, extent and timescale of biofilm compaction and relaxation (decompaction), caused by permeate flux variations. The impact of permeate flux changes on biofilm thickness, structure and stiffness was investigated in situ and non-destructively with optical coherence tomography using membrane fouling monitors operated at a constant crossflow velocity of 0.1 m s−1 with permeate production. The permeate flux was varied sequentially from 20 to 60 and back to 20 L m−2 h−1. The study showed that the average biofilm thickness on the membrane decreased after elevating the permeate flux from 20 to 60 L m−2 h−1 while the biofilm thickness increased again after restoring the original flux of 20 L m−2 h−1, indicating the occurrence of biofilm compaction and relaxation. Within a few seconds after the flux change, the biofilm thickness was changed and stabilized, biofilm compaction occurred faster than the relaxation after restoring the original permeate flux. The initial biofilm parameters were not fully reinstated: the biofilm thickness was reduced by 21%, biofilm stiffness had increased and the hydraulic biofilm resistance was elevated by 16%. Biofilm thickness was related to the hydraulic biofilm resistance. Membrane performance losses are related to the biofilm thickness, density and morphology, which are influenced by (variations in) hydraulic conditions. A (temporarily) permeate flux increase caused biofilm compaction, together with membrane performance losses. The impact of biofilms on membrane performance can be influenced (increased and reduced) by operational parameters. The article shows that a (temporary) pressure increase leads to more

  4. Interactions in multispecies biofilms

    DEFF Research Database (Denmark)

    Burmølle, Mette; Ren, Dawei; Bjarnsholt, Thomas

    2014-01-01

    The recent focus on complex bacterial communities has led to the recognition of interactions across species boundaries. This is particularly pronounced in multispecies biofilms, where synergistic interactions impact the bacterial distribution and overall biomass produced. Importantly, in a number...... of settings, the interactions in a multispecies biofilm affect its overall function, physiology, or surroundings, by resulting in enhanced resistance, virulence, or degradation of pollutants, which is of significant importance to human health and activities. The underlying mechanisms causing these synergistic...

  5. Glucocorticoid-related bone changes from endogenous or exogenous glucocorticoids.

    Science.gov (United States)

    Warriner, Amy H; Saag, Kenneth G

    2013-12-01

    Glucocorticoids have a negative impact on bone through direct effects on bone cells and indirect effects on calcium absorption. Here, recent findings regarding glucocorticoid-induced osteoporosis, bone changes in patients with endogenous glucocorticoid derangements, and treatment of steroid-induced bone disease are reviewed. Although the majority of our understanding arises from the outcomes of patients treated with exogenous steroids, endogenous overproduction appears to be similarly destructive to bone, but these effects are reversible with cure of the underlying disease process. Additionally, there are bone changes that occur in diseases that interrupt adrenal glucocorticoid production, both in response to our inability to perfectly match glucocorticoid replacement and also related to the underlying disease process. More investigation is required to understand which patients with endogenous overproduction or underproduction of glucocorticoid would benefit from osteoporosis treatment. Better understood is the benefit that can be achieved with currently approved treatments for glucocorticoid-induced osteoporosis from exogenous steroids. With growing concern of long-term use of bisphosphonates, however, further investigation into the duration of use and use in certain populations, such as children and premenopausal women, is essential. Glucocorticoid-induced osteoporosis is a complex disease that is becoming better understood through advances in the study of exogenous and endogenous glucocorticoid exposure. Further advancement of proper treatment and prevention is on the horizon.

  6. Biofilm Formation by Staphylococcus epidermidis on Foldable and Rigid Intraocular Lenses.

    Science.gov (United States)

    Fazly Bazzaz, Bibi Sedigheh; Jalalzadeh, Monireh; Sanati, Maryam; Zarei-Ghanavati, Syamak; Khameneh, Bahman

    2014-05-01

    Biofilm formation of Staphylococcus epidermidis is a major etiological factor of inducing device-related infections. The ability of biofilm formation by the S. epidermidis was assessed in vitro on two brands of foldable (hydrophilic) and two brands of rigid (hydrophobic) intraocular lens materials in order to investigate the role of lens material in postoperative endophthalmitis. To ensure reproducibility of biofilm formation on intraocular lenses, two strains of S. epidermidis and three quantification methods were performed. The S. epidermidis strains, DSMZ3270 (biofilm-producer) and ATCC12228 (non-biofilm-producer) were applied. Organisms were cultivated on disks of different brands of foldable hydrophilic Intra Ocular Lens (IOL) made of acrylic (Didar, Iran; (A) and Omni, India; (B)), and rigid hydrophobic IOL made of polymethyl methacrylate (PMMA; Didar, Iran; (C) and Hexavision, France; (D)). Biofilms were stained with crystal violet (CV) dye, which is an index of biofilm formation. The bacterial population was counted after biofilm homogenization. Scanning electron microscopy (SEM) was performed to examine the extent of biofilm formation. Adherence of DSMZ3270 strain on both types of foldable and rigid IOLs, was significantly more than ATCC12228 (P brands of foldable and PMMA IOLs. According to statistical analyses the incubation time influenced the biofilm formation on both types of IOLs which meant that by increasing incubation time, the biofilm formation increased. According to the SEM pictures, biofilm seems to be lysed at 72 hours. These data demonstrated that the attachment of bacteria to hydrophilic acrylic IOLs was more than hydrophobic PMMA ones independent of the brand. According to these results the bacterial strain might have more hydrophilic properties. Augmenting the biomass of biofilm by passing of time demonstrated the key role of time in biofilm formation on the IOL surfaces. The differences between IOL brands in the biofilm formation

  7. Genetic Control of Conventional and Pheromone-Stimulated Biofilm Formation in Candida albicans

    Science.gov (United States)

    Lin, Ching-Hsuan; Kabrawala, Shail; Fox, Emily P.; Nobile, Clarissa J.; Johnson, Alexander D.; Bennett, Richard J.

    2013-01-01

    Candida albicans can stochastically switch between two phenotypes, white and opaque. Opaque cells are the sexually competent form of C. albicans and therefore undergo efficient polarized growth and mating in the presence of pheromone. In contrast, white cells cannot mate, but are induced – under a specialized set of conditions – to form biofilms in response to pheromone. In this work, we compare the genetic regulation of such “pheromone-stimulated” biofilms with that of “conventional” C. albicans biofilms. In particular, we examined a network of six transcriptional regulators (Bcr1, Brg1, Efg1, Tec1, Ndt80, and Rob1) that mediate conventional biofilm formation for their potential roles in pheromone-stimulated biofilm formation. We show that four of the six transcription factors (Bcr1, Brg1, Rob1, and Tec1) promote formation of both conventional and pheromone-stimulated biofilms, indicating they play general roles in cell cohesion and biofilm development. In addition, we identify the master transcriptional regulator of pheromone-stimulated biofilms as C. albicans Cph1, ortholog of Saccharomyces cerevisiae Ste12. Cph1 regulates mating in C. albicans opaque cells, and here we show that Cph1 is also essential for pheromone-stimulated biofilm formation in white cells. In contrast, Cph1 is dispensable for the formation of conventional biofilms. The regulation of pheromone- stimulated biofilm formation was further investigated by transcriptional profiling and genetic analyses. These studies identified 196 genes that are induced by pheromone signaling during biofilm formation. One of these genes, HGC1, is shown to be required for both conventional and pheromone-stimulated biofilm formation. Taken together, these observations compare and contrast the regulation of conventional and pheromone-stimulated biofilm formation in C. albicans, and demonstrate that Cph1 is required for the latter, but not the former. PMID:23637598

  8. Effects of Low-Dose Amoxicillin on Staphylococcus aureus USA300 Biofilms.

    Science.gov (United States)

    Mlynek, Kevin D; Callahan, Mary T; Shimkevitch, Anton V; Farmer, Jackson T; Endres, Jennifer L; Marchand, Mélodie; Bayles, Kenneth W; Horswill, Alexander R; Kaplan, Jeffrey B

    2016-05-01

    Previous studies showed that sub-MIC levels of β-lactam antibiotics stimulate biofilm formation in most methicillin-resistant Staphylococcus aureus (MRSA) strains. Here, we investigated this process by measuring the effects of sub-MIC amoxicillin on biofilm formation by the epidemic community-associated MRSA strain USA300. We found that sub-MIC amoxicillin increased the ability of USA300 cells to attach to surfaces and form biofilms under both static and flow conditions. We also found that USA300 biofilms cultured in sub-MIC amoxicillin were thicker, contained more pillar and channel structures, and were less porous than biofilms cultured without antibiotic. Biofilm formation in sub-MIC amoxicillin correlated with the production of extracellular DNA (eDNA). However, eDNA released by amoxicillin-induced cell lysis alone was evidently not sufficient to stimulate biofilm. Sub-MIC levels of two other cell wall-active agents with different mechanisms of action-d-cycloserine and fosfomycin-also stimulated eDNA-dependent biofilm, suggesting that biofilm formation may be a mechanistic adaptation to cell wall stress. Screening a USA300 mariner transposon library for mutants deficient in biofilm formation in sub-MIC amoxicillin identified numerous known mediators of S. aureus β-lactam resistance and biofilm formation, as well as novel genes not previously associated with these phenotypes. Our results link cell wall stress and biofilm formation in MRSA and suggest that eDNA-dependent biofilm formation by strain USA300 in low-dose amoxicillin is an inducible phenotype that can be used to identify novel genes impacting MRSA β-lactam resistance and biofilm formation. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

  9. Fate of deposited cells in an aerobic binary bacterial biofilm

    International Nuclear Information System (INIS)

    Banks, M.K.

    1989-01-01

    A biofilm is a matrix of microbial cells and their extracellular products that is associated with a solid surface. Previous studies on biofilm development have employed only dissolved compounds as growth limiting substrates, without the influence of microbial species invading from the bulk liquid. The goal of this research project was to quantify the kinetics of processes governing suspended biomass turnover in biofilm systems, and the accompanying effects of suspended cell deposition on biofilm population dynamics. Experiments were conducted with two species of bacteria, Pseudomonas putida ATCC 11172 grown on glucose, and Hyphomicrobium ZV620 grown on methanol. Cryptic growth and particulate hydrolysis studies were evaluated, using combinations of these two bacteria, by measuring the uptake of radiolabelled cell lysis products, under batch conditions. Biofilms studies were performed to investigate bacterial deposition, continual biofilm removal by shear induced erosion, and biofilm ecology. Biofilms were developed in a flow cell reactor, under laminar flow conditions. Bacterial species were differentiated by radioactively labelling each species with their carbon substrate. A mathematical model was developed to predict the biofilm ecology of mixed cultures. The equations developed predict biofilm accumulation, as well as substrate and oxygen consumption. Results indicate that cryptic growth will occur for bacteria growing on their own species soluble lysis products and in some cases, bacteria growing on the soluble lysis products of other species. Particulate hydrolysis only occurred for Pseudomonas putida growing on Pseudomonas putida lysis products, but the lack of particulate hydrolysis occurring in the other studies may have been due to the short experimental period

  10. Silver colloidal nanoparticles: effect on matrix composition and structure of Candida albicans and Candida glabrata biofilms.

    Science.gov (United States)

    Monteiro, D R; Silva, S; Negri, M; Gorup, L F; de Camargo, E R; Oliveira, R; Barbosa, D B; Henriques, M

    2013-04-01

    The aim of this study was to assess the effect of different silver nanoparticles (SN) concentrations on the matrix composition and structure of Candida albicans and Candida glabrata biofilms. Candida biofilms were developed in 6-well microtiter plates during 48 h. After, these biofilms were exposed to 13.5 or 54 μg SN ml(-1) for 24 h. Then, extracellular matrices were extracted from biofilms and analysed chemically in terms of proteins, carbohydrates and DNA. To investigate the biofilm structure, scanning electron microscopy (SEM) and epifluorescence microscopy were used. SN interfered with the matrix composition of Candida biofilms tested in terms of protein, carbohydrate and DNA, except for the protein content of C. albicans biofilm. By SEM, Candida biofilms treated with SN revealed structural differences, when compared with the control groups. Further, SN showed a trend of agglomeration within the biofilms. Epifluorescence microscopy images suggest that SN induced damage on cell walls of the Candida isolates tested. In general, irrespective of concentration, SN affected the matrix composition and structure of Candida biofilms and these findings may be related to the mechanisms of biocide action of SN. This study reveals new insights about the behaviour of SN when in contact with Candida biofilms. SN may contribute to the development of therapies to prevent or control Candida infections. © 2012 The Society for Applied Microbiology.

  11. Sucrose substitutes affect the cariogenic potential of Streptococcus mutans biofilms.

    Science.gov (United States)

    Durso, S C; Vieira, L M; Cruz, J N S; Azevedo, C S; Rodrigues, P H; Simionato, M R L

    2014-01-01

    Streptococcus mutans is considered the primary etiologic agent of dental caries and contributes significantly to the virulence of dental plaque, especially in the presence of sucrose. To avoid the role of sucrose on the virulence factors of S. mutans, sugar substitutes are commonly consumed because they lead to lower or no production of acids and interfere with biofilm formation. This study aimed to investigate the contribution of sugar substitutes in the cariogenic potential of S. mutans biofilms. Thus, in the presence of sucrose, glucose, sucralose and sorbitol, the biofilm mass was quantified up to 96 h, the pH of the spent culture media was measured, the expression of biofilm-related genes was determined, and demineralization challenge experiments were conduct in enamel fragments. The presence of sugars or sugar substitutes profoundly affected the expression of spaP, gtfB, gtfC, gbpB, ftf, vicR and vicX in either biofilm or planktonic cells. The substitution of sucrose induced a down-regulation of most genes involved in sucrose-dependent colonization in biofilm cells. When the ratio between the expression of biofilm and planktonic cells was considered, most of those genes were down-regulated in biofilm cells in the presence of sugars and up-regulated in the presence of sugar substitutes. However, sucralose but not sorbitol fulfilled the purpose of reducing the cariogenic potential of the diet since it induced the biofilm formation with the lowest biomass, did not change the pH of the medium and led to the lowest lesion depth in the cariogenic challenge.

  12. Optimized candidal biofilm microtiter assay

    NARCIS (Netherlands)

    Krom, Bastiaan P.; Cohen, Jesse B.; Feser, Gail E. McElhaney; Cihlar, Ronald L.

    Microtiter based candidal biofilm formation is commonly being used. Here we describe the analysis of factors influencing the development of candidal biofilms such as the coating with serum, growth medium and pH. The data reported here show that optimal candidal biofilm formation is obtained when

  13. Biofilm formation on abiotic surfaces

    DEFF Research Database (Denmark)

    Tang, Lone

    2011-01-01

    Bacteria can attach to any surface in contact with water and proliferate into complex communities enclosed in an adhesive matrix, these communities are called biofilms. The matrix makes the biofilm difficult to remove by physical means, and bacteria in biofilm can survive treatment with many...

  14. Commensal Protection of Staphylococcus aureus against Antimicrobials by Candida albicans Biofilm Matrix

    Science.gov (United States)

    Kong, Eric F.; Tsui, Christina; Kucharíková, Sona; Andes, David

    2016-01-01

    ABSTRACT Biofilm-associated polymicrobial infections, particularly those involving fungi and bacteria, are responsible for significant morbidity and mortality and tend to be challenging to treat. Candida albicans and Staphylococcus aureus specifically are considered leading opportunistic fungal and bacterial pathogens, respectively, mainly due to their ability to form biofilms on catheters and indwelling medical devices. However, the impact of mixed-species biofilm growth on therapy remains largely understudied. In this study, we investigated the influence of C. albicans secreted cell wall polysaccharides on the response of S. aureus to antibacterial agents in biofilm. Results demonstrated significantly enhanced tolerance for S. aureus to drugs in the presence of C. albicans or its secreted cell wall polysaccharide material. Fluorescence confocal time-lapse microscopy revealed impairment of drug diffusion through the mixed biofilm matrix. Using C. albicans mutant strains with modulated cell wall polysaccharide expression, exogenous supplementation, and enzymatic degradation, the C. albicans-secreted β-1,3-glucan cell wall component was identified as the key matrix constituent providing the bacteria with enhanced drug tolerance. Further, antibody labeling demonstrated rapid coating of the bacteria by the C. albicans matrix material. Importantly, via its effect on the fungal biofilm matrix, the antifungal caspofungin sensitized the bacteria to the drugs. Understanding such symbiotic interactions with clinical relevance between microbial species in biofilms will greatly aid in overcoming the limitations of current therapies and in defining potential new targets for treating polymicrobial infections. PMID:27729510

  15. Exogenous melatonin administration is beneficial for male ...

    African Journals Online (AJOL)

    ABSTRACT. Background: A concern in the use of exogenous melatonin as a therapeutic intervention is that it may interfere with reproductive function. Herein, we report that chronic exogenous melatonin administration does not impair male reproductive function during ageing and at old age in male Sprague Dawley rats.

  16. Exogenous melatonin administration is beneficial for male ...

    African Journals Online (AJOL)

    Background: A concern in the use of exogenous melatonin as a therapeutic intervention is that it may interfere with reproductive function. Herein, we report that chronic exogenous melatonin administration does not impair male reproductive function during ageing and at old age in male Sprague Dawley rats. Methods: ...

  17. SEM Analysis of Surface Impact on Biofilm Antibiotic Treatment.

    Science.gov (United States)

    Gomes, Luciana Calheiros; Mergulhão, Filipe José

    2017-01-01

    The aim of this work was to use scanning electron microscopy (SEM) to investigate the effect of ampicillin treatment on Escherichia coli biofilms formed on two surface materials with different properties, silicone (SIL) and glass (GLA). Epifluorescence microscopy (EM) was initially used to assess biofilm formation and killing efficiency on both surfaces. This technique showed that higher bacterial colonization was obtained in the hydrophobic SIL than in the hydrophilic GLA. It has also shown that higher biofilm inactivation was attained for GLA after the antibiotic treatment (7-log reduction versus 1-log reduction for SIL). Due to its high resolution and magnification, SEM enabled a more detailed analysis of the antibiotic effect on biofilm cells, complementing the killing efficiency information obtained by EM. SEM micrographs revealed that ampicillin-treated cells have an elongated form when compared to untreated cells. Additionally, it has shown that different materials induced different levels of elongation on cells exposed to antibiotic. Biofilms formed on GLA showed a 37% higher elongation than those formed on SIL. Importantly, cell elongation was related to viability since ampicillin had a higher bactericidal effect on GLA-formed biofilms. These findings raise the possibility of using SEM for understanding the efficacy of antimicrobial treatments by observation of biofilm morphology.

  18. Global gene expression in Escherichia coli biofilms

    DEFF Research Database (Denmark)

    Schembri, Mark; Kjærgaard, K.; Klemm, Per

    2003-01-01

    It is now apparent that microorganisms undergo significant changes during the transition from planktonic to biofilm growth. These changes result in phenotypic adaptations that allow the formation of highly organized and structured sessile communities, which possess enhanced resistance to antimicr......It is now apparent that microorganisms undergo significant changes during the transition from planktonic to biofilm growth. These changes result in phenotypic adaptations that allow the formation of highly organized and structured sessile communities, which possess enhanced resistance...... the transition to biofilm growth, and these included genes expressed under oxygen-limiting conditions, genes encoding (putative) transport proteins, putative oxidoreductases and genes associated with enhanced heavy metal resistance. Of particular interest was the observation that many of the genes altered...... in expression have no current defined function. These genes, as well as those induced by stresses relevant to biofilm growth such as oxygen and nutrient limitation, may be important factors that trigger enhanced resistance mechanisms of sessile communities to antibiotics and hydrodynamic shear forces....

  19. Alginate production affects Pseudomonas aeruginosa biofilm development and architecture, but is not essential for biofilm formation

    DEFF Research Database (Denmark)

    Stapper, A.P.; Narasimhan, G.; Oman, D.E.

    2004-01-01

    of their biofilm formation using confocal laser scanning microscopy. Biofilm Image Processing (BIP) and Community Statistics (COMSTAT) software programs were used to provide quantitative measurements of the two-dimensional biofilm images. All three strains formed distinguishable biofilm architectures, indicating...

  20. Dental biofilm infections

    DEFF Research Database (Denmark)

    Larsen, Tove; Fiehn, Nils-Erik

    2017-01-01

    and cause gingival inflammation and breakdown of supporting periodontal fibers and bone and ultimately tooth loss, i.e., gingivitis, chronic or aggressive periodontitis, and around dental implants, peri-implantitis. Furthermore, bacteria from the dental biofilm may spread to other parts of the body......-fermenting bacteria causing demineralization of teeth, dental caries, which may further lead to inflammation and necrosis in the pulp and periapical region, i.e., pulpitis and periapical periodontitis. In supra- and subgingival biofilms, predominantly gram-negative, anaerobic proteolytic bacteria will colonize...

  1. Pseudomonas aeruginosa Biofilms

    DEFF Research Database (Denmark)

    Alhede, Maria; Bjarnsholt, Thomas; Givskov, Michael

    2014-01-01

    biofilms, which protect the aggregated, biopolymer-embedded bacteria from the detrimental actions of antibiotic treatments and host immunity. A key component in the protection against innate immunity is rhamnolipid, which is a quorum sensing (QS)-regulated virulence factor. QS is a cell-to-cell signaling...... mechanism used to coordinate expression of virulence and protection of aggregated biofilm cells. Rhamnolipids are known for their ability to cause hemolysis and have been shown to cause lysis of several cellular components of the human immune system, for example, macrophages and polymorphonuclear leukocytes...

  2. Exposure of E. coli to DNA-methylating agents impairs biofilm formation and invasion of eukaryotic cells via down regulation of the N-acetylneuraminate lyase NanA

    Directory of Open Access Journals (Sweden)

    Pamela eDi Pasquale

    2016-02-01

    Full Text Available DNA methylation damage can be induced by endogenous and exogenous chemical agents, which has led every living organism to develop suitable response strategies. We investigated protein expression profiles of Escherichia coli upon exposure to the alkylating agent methyl-methane sulfonate (MMS by differential proteomics. Quantitative proteomic data showed a massive downregulation of enzymes belonging to the glycolytic pathway and fatty acids degradation, strongly suggesting a decrease of energy production. A strong reduction in the expression of the N-acetylneuraminate lyases (NanA involved in the sialic acid metabolism was also observed. Using a null NanA mutant and DANA, a substrate analogue acting as competitive inhibitor, we demonstrated that down regulation of NanA affects biofilm formation and adhesion properties of E. coli MV1161. Exposure to alkylating agents also decreased biofilm formation and bacterial adhesion to Caco-2 eukaryotic cell line by the adherent invasive E. coli (AIEC strain LF82. Our data showed that methylation stress impairs E. coli adhesion properties and suggest a possible role of NanA in biofilm formation and bacteria host interactions.

  3. Manipulatiaon of Biofilm Microbial Ecology

    Energy Technology Data Exchange (ETDEWEB)

    Burkhalter, R.; Macnaughton, S.J.; Palmer, R.J.; Smith, C.A.; Whitaker, K.W.; White, D.C.; Zinn, M.; kirkegaard, R.

    1998-08-09

    The Biofilm mode of growth provides such significant advantages to the members of the consortium that most organisms in important habitats are found in biofilms. The study of factors that allow manipulation of biofilm microbes in the biofilm growth state requires that reproducible biofilms by generated. The most effective monitoring of biofilm formation, succession and desquamation is with on-line monitoring of microbial biofilms with flowcell for direct observation. The biofilm growth state incorporates a second important factor, the heterogeneity in the distribution in time and space of the component members of the biofilm consortium. This heterogeneity is reflected not only in the cellular distribution but in the metabolic activity within a population of cells. Activity and cellular distribution can be mapped in four dimensions with confocal microscopy, and function can be ascertained by genetically manipulated reporter functions for specific genes or by vital stains. The methodology for understanding the microbial ecology of biofilms is now much more readily available and the capacity to manipulate biofilms is becoming an important feature of biotechnology.

  4. Bacterial biofilm and associated infections

    Directory of Open Access Journals (Sweden)

    Muhsin Jamal

    2018-01-01

    Full Text Available Microscopic entities, microorganisms that drastically affect human health need to be thoroughly investigated. A biofilm is an architectural colony of microorganisms, within a matrix of extracellular polymeric substance that they produce. Biofilm contains microbial cells adherent to one-another and to a static surface (living or non-living. Bacterial biofilms are usually pathogenic in nature and can cause nosocomial infections. The National Institutes of Health (NIH revealed that among all microbial and chronic infections, 65% and 80%, respectively, are associated with biofilm formation. The process of biofilm formation consists of many steps, starting with attachment to a living or non-living surface that will lead to formation of micro-colony, giving rise to three-dimensional structures and ending up, after maturation, with detachment. During formation of biofilm several species of bacteria communicate with one another, employing quorum sensing. In general, bacterial biofilms show resistance against human immune system, as well as against antibiotics. Health related concerns speak loud due to the biofilm potential to cause diseases, utilizing both device-related and non-device-related infections. In summary, the understanding of bacterial biofilm is important to manage and/or to eradicate biofilm-related diseases. The current review is, therefore, an effort to encompass the current concepts in biofilm formation and its implications in human health and disease.

  5. Manipulation of Biofilm Microbial Ecology

    Energy Technology Data Exchange (ETDEWEB)

    White, D.C.; Palmer, R.J., Jr.; Zinn, M.; Smith, C.A.; Burkhalter, R.; Macnaughton, S.J.; Whitaker, K.W.; Kirkegaard, R.D.

    1998-08-15

    The biofilm mode of growth provides such significant advantages to the members of the consortium that most organisms in important habitats are found in biofilms. The study of factors that allow manipulation of biofilm microbes in the biofilm growth state requires that reproducible biofilms be generated. The most effective monitoring of biofilm formation, succession and desaturation is with on-line monitoring of microbial biofilms with flowcell for direct observation. The biofilm growth state incorporates a second important factor, the heterogeneity in distribution in time and space of the component members of the biofilm consortium. This heterogeneity is reflected not only in the cellular distribution but in the metabolic activity within a population of cells. Activity and cellular distribution can be mapped in four dimensions with confocal microscopy, and function can be ascertained by genetically manipulated reporter functions for specific genes or by vital stains. The methodology for understanding the microbial ecology of biofilms is now much more readily available and the capacity to manipulate biofilms is becoming an important feature of biotechnology.

  6. Morphomechanics of bacterial biofilms undergoing anisotropic differential growth

    Science.gov (United States)

    Zhang, Cheng; Li, Bo; Huang, Xiao; Ni, Yong; Feng, Xi-Qiao

    2016-10-01

    Growing bacterial biofilms exhibit a number of surface morphologies, e.g., concentric wrinkles, radial ridges, and labyrinthine networks, depending on their physiological status and nutrient access. We explore the mechanisms underlying the emergence of these greatly different morphologies. Ginzburg-Landau kinetic method and Fourier spectral method are integrated to simulate the morphological evolution of bacterial biofilms. It is shown that the morphological instability of biofilms is triggered by the stresses induced by anisotropic and heterogeneous bacterial expansion, and involves the competition between membrane energy and bending energy. Local interfacial delamination further enriches the morphologies of biofilms. Phase diagrams are established to reveal how the anisotropy and spatial heterogeneity of growth modulate the surface patterns. The mechanics of three-dimensional microbial morphogenesis may also underpin self-organization in other development systems and provide a potential strategy for engineering microscopic structures from bacterial aggregates.

  7. Biofilm in endodontics: A review

    Science.gov (United States)

    Jhajharia, Kapil; Parolia, Abhishek; Shetty, K Vikram; Mehta, Lata Kiran

    2015-01-01

    Endodontic disease is a biofilm-mediated infection, and primary aim in the management of endodontic disease is the elimination of bacterial biofilm from the root canal system. The most common endodontic infection is caused by the surface-associated growth of microorganisms. It is important to apply the biofilm concept to endodontic microbiology to understand the pathogenic potential of the root canal microbiota as well as to form the basis for new approaches for disinfection. It is foremost to understand how the biofilm formed by root canal bacteria resists endodontic treatment measures. Bacterial etiology has been confirmed for common oral diseases such as caries and periodontal and endodontic infections. Bacteria causing these diseases are organized in biofilm structures, which are complex microbial communities composed of a great variety of bacteria with different ecological requirements and pathogenic potential. The biofilm community not only gives bacteria effective protection against the host's defense system but also makes them more resistant to a variety of disinfecting agents used as oral hygiene products or in the treatment of infections. Successful treatment of these diseases depends on biofilm removal as well as effective killing of biofilm bacteria. So, the fundamental to maintain oral health and prevent dental caries, gingivitis, and periodontitis is to control the oral biofilms. From these aspects, the formation of biofilms carries particular clinical significance because not only host defense mechanisms but also therapeutic efforts including chemical and mechanical antimicrobial treatment measures have the most difficult task of dealing with organisms that are gathered in a biofilm. The aim of this article was to review the mechanisms of biofilms’ formation, their roles in pulpal and periapical pathosis, the different types of biofilms, the factors influencing biofilm formation, the mechanisms of their antimicrobial resistance, techniques to

  8. Exogenous and endogenous shifts of attention in perihand space.

    Science.gov (United States)

    Le Bigot, Nathalie; Grosjean, Marc

    2016-07-01

    While some studies have found that attentional orienting is altered in perihand space, most have not. One reason for such discrepancies may be related to the types of cues (uninformative and informative) that have been used, as they are known to induce different types of shifts of attention (exogenous and endogenous, respectively). To systematically address this question, two experiments were performed in which an uninformative peripheral cue (Experiment 1) or an informative central cue (Experiment 2) preceded a peripheral target with a short (100-150 ms) stimulus-onset asynchrony. Participants performed the task with their left hand, right hand, both hands, or no hands near the display. Cueing effects were obtained in both experiments, but they were only modulated by hand position in Experiment 1, with larger effects observed in the right- and both-hand conditions. These findings suggest that exogenous attention shifts are affected by hand proximity, while endogenous shifts are not.

  9. Biofilm roughness determines Cryptosporidium parvum retention in environmental biofilms.

    Science.gov (United States)

    DiCesare, E A Wolyniak; Hargreaves, B R; Jellison, K L

    2012-06-01

    The genus Cryptosporidium is a group of waterborne protozoan parasites that have been implicated in significant outbreaks of gastrointestinal infections throughout the world. Biofilms trap these pathogens and can contaminate water supplies through subsequent release. Biofilm microbial assemblages were collected seasonally from three streams in eastern Pennsylvania and used to grow biofilms in laboratory microcosms. Daily oocyst counts in the influx and efflux flow allowed the calculation of daily oocyst retention in the biofilm. Following the removal of oocysts from the influx water, oocyst attachment to the biofilm declined to an equilibrium state within 5 days that was sustained for at least 25 days. Varying the oocyst loading rate for the system showed that biofilm retention could be saturated, suggesting that discrete binding sites determined the maximum number of oocysts retained. Oocyst retention varied seasonally but was consistent across all three sites; however, seasonal oocyst retention was not consistent across years at the same site. No correlation between oocyst attachment and any measured water quality parameter was found. However, oocyst retention was strongly correlated with biofilm surface roughness and roughness varied among seasons and across years. We hypothesize that biofilm roughness and oocyst retention are dependent on environmentally driven changes in the biofilm community rather than directly on water quality conditions. It is important to understand oocyst transport dynamics to reduce risks of human infection. Better understanding of factors controlling biofilm retention of oocysts should improve our understanding of oocyst transport at different scales.

  10. The effect of PDT on H. influenzae biofilm in vivo

    Science.gov (United States)

    Rhee, Chung-Ku; Chang, So-Young; Hwang, Dong-Jo; Kim, Young Hoon; Ahn, Jin-Chul

    2010-02-01

    Biofilm formation has been demonstrated for many mucosal pathogens such as Haemophilus influenzae. The presence of mucosal biofilms with chronic otitis media with effusion (COME) suggests that bacteria do not clear by antibiotics. Aim: To test the effect of photodynamic therapy (PDT) on H. influenzae induced biofilm in vivo. Methods: Gerbils were divided into control (C), HI group, Laser (L), PS, PDT A, and PDT B groups. The C group received no treatment. HI group was injected with 20μl (108CFU/ml) of H. influenzae into the bullae and formation of biofilms in the bullae was obtained by 5 days. For L group, 120 J/cm2 (100 mw × 20 min) of 632 nm LD laser was irradiated by a fiber inserted into the bullae 5 days after the H. influenzaeinjection. For PS group, photofrin 40μl (1mg/ml) were injected into the bullae 5 days after the H. influenzae injection. PDT A group received photofrin 1 mg/ml and LD laser 120 J/cm2 that were administered into the bullae 5 days after the H. influenzae injection. PDT B group received photofrin 2 mg/ml and laser 150 J/cm2 5 days after the H. influenzae injection. The mucosal tissues in bullae were examined by H/E staining, and SEM. Results: The C group showed normal mucosa of bullae. The HI, L, and PS groups have shown well formed biofilm. Twenty five percent of the PDT A group and 50 % of the PDT B group have shown completely or partially resolved biofilm. Conclusion: The results of this study demonstrated that PDT appears to be effective to treat experimental H. influenzae induced biofilms in vivo. Clinical implication: PDT may be an alternative to antibiotic treatment on otitis media with biofilm formation.

  11. PATHOGENICITY OF BIOFILM BACTERIA

    Science.gov (United States)

    There is a paucity of information concerning any link between the microorganisms commonly found in biofilms of drinking water systems and their impacts on human health. For bacteria, culture-based techniques detect only a limited number of the total microorganisms associated wit...

  12. [Biofilms in otolaryngology].

    Science.gov (United States)

    Mena Viveros, Nicolás

    2014-01-01

    According to the National Institute of Health of the USA, «more than 60% of all microbial infections are caused by biofilms».'This can surprise us, but it is enough to consider that common infections like those of the genito-urinary tract, infections produced by catheters, middle ear infections in children, the formation of dental plaque and gingivitis are caused by biofilms, for this statement to seem more realistic. At present this is one of the subjects of great interest within medicine, particularly in otolaryngology. Bacteria have traditionally been considered to be in a free state without evident organization, partly perhaps by the ease of studying them in this form. Nevertheless, the reality is that, in nature, the great majority of these germs form complex colonies adhered to surfaces, colonies that have received the name of biofilms. These biofilms are more common than previously thought and almost all of the people have been in contact with them in the form of infections in the teeth or humid, slippery areas. New treatments that can eradicate them are currently being investigated. Copyright © 2012 Elsevier España, S.L. All rights reserved.

  13. Antimicrobial blue light inactivation of biofilms formed by clinical isolates of multidrug-resistant microorganisms

    Science.gov (United States)

    Ferrer-Espada, Raquel; Fang, Yanyan; Dai, Tianhong

    2018-02-01

    Antibiotic resistance is one of the most serious threats to public health. It is estimated that at least 23,000 people die each year in the USA as a direct result of antibiotic-resistant infections. In addition, many antibiotic-resistant microorganisms develop biofilms, surface-associated microbial communities that are extremely resistant to antibiotics and the immune system. A light-based approach, antimicrobial blue light (aBL), has attracted increasing attention due to its intrinsic antimicrobial effect without the involvement of exogenous photosensitizers. In this study, we investigated the effectiveness of this non-antibiotic approach against biofilms formed by multidrug-resistant (MDR) microorganisms. MDR Acinetobacter baumannii, Escherichia coli, Candida albicans, and Pseudomonas aeruginosa biofilms were grown either in 96-well microtiter plates for 24 h or in a CDC biofilm reactor for 48 h, and then exposed to aBL at 405 nm emitted from a light-emitting diode (LED). We demonstrated that, for the biofilms grown in the CDC biofilm reactor, approximately 1.88 log10 CFU reduction was achieved in A. baumannii, 2.78 log10 CFU in E. coli and 3.18 log10 CFU in P. aeruginosa after 162 J/cm2 , 576 J/cm2 and 500 J/cm2 aBL were delivered, respectively. For the biofilms formed in the 96-well microtiter plates, 5.67 and 2.46 log10 CFU reduction was observed in P. aeruginosa and C. albicans polymicrobial biofilm after an exposure of 216 J/cm2 . In conclusion, aBL is potentially an alternative non-antibiotic approach against MDR biofilm-related infections. Future studies are warranted to investigate other important MDR microorganisms, the mechanism of action of aBL, and aBL efficacy in vivo.

  14. Design of a dynamic biofilm imaging cell for white-light interferometric microscopy

    Science.gov (United States)

    Larimer, Curtis; Brann, Michelle; Suter, Jonathan D.; Addleman, R. Shane

    2017-11-01

    In microbiology research, there is a strong need for next-generation imaging and sensing instrumentation that will enable minimally invasive and label-free investigation of soft, hydrated structures, such as in bacterial biofilms. White-light interferometry (WLI) can provide high-resolution images of surface topology without the use of fluorescent labels but is not typically used to image biofilms because there is insufficient refractive index contrast to induce reflection from the biofilm's interface. The soft structure and water-like bulk properties of hydrated biofilms make them difficult to characterize in situ, especially in a nondestructive manner. We build on our prior description of static biofilm imaging and describe the design of a dynamic growth flow cell that enables monitoring of the thickness and topology of live biofilms over time using a WLI microscope. The microfluidic system is designed to grow biofilms in dynamic conditions and to create a reflective interface on the surface while minimizing disruption of fragile structures. The imaging cell was also designed to accommodate limitations imposed by the depth of focus of the microscope's objective lens. Example images of live biofilm samples are shown to illustrate the ability of the flow cell and WLI instrument to (1) support bacterial growth and biofilm development, (2) image biofilm structure that reflects growth in flow conditions, and (3) monitor biofilm development over time nondestructively. In future work, the apparatus described here will enable surface metrology measurements (roughness, surface area, etc.) of biofilms and may be used to observe changes in biofilm structure in response to changes in environmental conditions (e.g., flow velocity, availability of nutrients, and presence of biocides). This development will open opportunities for the use of WLI in bioimaging.

  15. Using synergistic exogenous phytohormones to enhance somatic ...

    African Journals Online (AJOL)

    Southern Forests: a Journal of Forest Science ... Eucalyptus spp. has been limited to germinated seeds, flowers, lignotubers or zygotic embryos. ... explants could be enhanced through pairing of synergistic exogenous plant growth regulators, ...

  16. Bacterial biofilm mechanical properties persist upon antibiotic treatment and survive cell death

    International Nuclear Information System (INIS)

    Zrelli, K; Galy, O; Henry, N; Latour-Lambert, P; Ghigo, J M; Beloin, C; Kirwan, L

    2013-01-01

    Bacteria living on surfaces form heterogeneous three-dimensional consortia known as biofilms, where they exhibit many specific properties one of which is an increased tolerance to antibiotics. Biofilms are maintained by a polymeric network and display physical properties similar to that of complex fluids. In this work, we address the question of the impact of antibiotic treatment on the physical properties of biofilms based on recently developed tools enabling the in situ mapping of biofilm local mechanical properties at the micron scale. This approach takes into account the material heterogeneity and reveals the spatial distribution of all the small changes that may occur in the structure. With an Escherichia coli biofilm, we demonstrate using in situ fluorescent labeling that the two antibiotics ofloxacin and ticarcillin—targeting DNA replication and membrane assembly, respectively—induced no detectable alteration of the biofilm mechanical properties while they killed the vast majority of the cells. In parallel, we show that a proteolytic enzyme that cleaves extracellular proteins into short peptides, but does not alter bacterial viability in the biofilm, clearly affects the mechanical properties of the biofilm structure, inducing a significant increase of the material compliance. We conclude that conventional biofilm control strategy relying on the use of biocides targeting cells is missing a key target since biofilm structural integrity is preserved. This is expected to efficiently promote biofilm resilience, especially in the presence of persister cells. In contrast, the targeting of polymer network cross-links—among which extracellular proteins emerge as major players—offers a promising route for the development of rational multi-target strategies to fight against biofilms. (paper)

  17. Bacterial biofilm mechanical properties persist upon antibiotic treatment and survive cell death

    Science.gov (United States)

    Zrelli, K.; Galy, O.; Latour-Lambert, P.; Kirwan, L.; Ghigo, J. M.; Beloin, C.; Henry, N.

    2013-12-01

    Bacteria living on surfaces form heterogeneous three-dimensional consortia known as biofilms, where they exhibit many specific properties one of which is an increased tolerance to antibiotics. Biofilms are maintained by a polymeric network and display physical properties similar to that of complex fluids. In this work, we address the question of the impact of antibiotic treatment on the physical properties of biofilms based on recently developed tools enabling the in situ mapping of biofilm local mechanical properties at the micron scale. This approach takes into account the material heterogeneity and reveals the spatial distribution of all the small changes that may occur in the structure. With an Escherichia coli biofilm, we demonstrate using in situ fluorescent labeling that the two antibiotics ofloxacin and ticarcillin—targeting DNA replication and membrane assembly, respectively—induced no detectable alteration of the biofilm mechanical properties while they killed the vast majority of the cells. In parallel, we show that a proteolytic enzyme that cleaves extracellular proteins into short peptides, but does not alter bacterial viability in the biofilm, clearly affects the mechanical properties of the biofilm structure, inducing a significant increase of the material compliance. We conclude that conventional biofilm control strategy relying on the use of biocides targeting cells is missing a key target since biofilm structural integrity is preserved. This is expected to efficiently promote biofilm resilience, especially in the presence of persister cells. In contrast, the targeting of polymer network cross-links—among which extracellular proteins emerge as major players—offers a promising route for the development of rational multi-target strategies to fight against biofilms.

  18. Visible propagation from invisible exogenous cueing.

    Science.gov (United States)

    Lin, Zhicheng; Murray, Scott O

    2013-09-20

    Perception and performance is affected not just by what we see but also by what we do not see-inputs that escape our awareness. While conscious processing and unconscious processing have been assumed to be separate and independent, here we report the propagation of unconscious exogenous cueing as determined by conscious motion perception. In a paradigm combining masked exogenous cueing and apparent motion, we show that, when an onset cue was rendered invisible, the unconscious exogenous cueing effect traveled, manifesting at uncued locations (4° apart) in accordance with conscious perception of visual motion; the effect diminished when the cue-to-target distance was 8° apart. In contrast, conscious exogenous cueing manifested in both distances. Further evidence reveals that the unconscious and conscious nonretinotopic effects could not be explained by an attentional gradient, nor by bottom-up, energy-based motion mechanisms, but rather they were subserved by top-down, tracking-based motion mechanisms. We thus term these effects mobile cueing. Taken together, unconscious mobile cueing effects (a) demonstrate a previously unknown degree of flexibility of unconscious exogenous attention; (b) embody a simultaneous dissociation and association of attention and consciousness, in which exogenous attention can occur without cue awareness ("dissociation"), yet at the same time its effect is contingent on conscious motion tracking ("association"); and (c) underscore the interaction of conscious and unconscious processing, providing evidence for an unconscious effect that is not automatic but controlled.

  19. Is Money Really Exogenous? Testing for Weak Exogeneity in Swiss Money Demand.

    OpenAIRE

    Fischer, Andreas M

    1993-01-01

    Although exogeneity is often associated with controllable policy variables, Engle, Hendry, and Richard (1983) show that the one condition is neither necessary nor sufficient for the other. Whether variables such as monetary aggregates are (weakly) exogenous depends on the conditioning properties of the data generating process. Testing exogeneity claims represents an important step in analyzing money demand functions. Although Switzerland adheres to fairly strict monetarist prescriptions, we r...

  20. New Technologies for Studying Biofilms

    Science.gov (United States)

    FRANKLIN, MICHAEL J.; CHANG, CONNIE; AKIYAMA, TATSUYA; BOTHNER, BRIAN

    2016-01-01

    Bacteria have traditionally been studied as single-cell organisms. In laboratory settings, aerobic bacteria are usually cultured in aerated flasks, where the cells are considered essentially homogenous. However, in many natural environments, bacteria and other microorganisms grow in mixed communities, often associated with surfaces. Biofilms are comprised of surface-associated microorganisms, their extracellular matrix material, and environmental chemicals that have adsorbed to the bacteria or their matrix material. While this definition of a biofilm is fairly simple, biofilms are complex and dynamic. Our understanding of the activities of individual biofilm cells and whole biofilm systems has developed rapidly, due in part to advances in molecular, analytical, and imaging tools and the miniaturization of tools designed to characterize biofilms at the enzyme level, cellular level, and systems level. PMID:26350329

  1. Silver against Pseudomonas aeruginosa biofilms

    DEFF Research Database (Denmark)

    Bjarnsholt, Thomas; Kirketerp-Møller, K.; Kristiansen, S.

    2007-01-01

    bacteria in both the planktonic and biofilm modes of growth. The action of silver on mature in vitro biofilms of Pseudomonas aeruginosa, a primary pathogen of chronic infected wounds, was investigated. The results show that silver is very effective against mature biofilms of P. aeruginosa......, but that the silver concentration is important. A concentration of 5-10 ig/mL silver sulfadiazine eradicated the biofilm whereas a lower concentration (1 ig/mL) had no effect. The bactericidal concentration of silver required to eradicate the bacterial biofilm was 10-100 times higher than that used to eradicate...... planktonic bacteria. These observations strongly indicate that the concentration of silver in currently available wound dressings is much too low for treatment of chronic biofilm wounds. It is suggested that clinicians and manufacturers of the said wound dressings consider whether they are treating wounds...

  2. The Effect of Reward on Orienting and Reorienting in Exogenous Cueing

    NARCIS (Netherlands)

    Bucker, B.; Theeuwes, J.

    2014-01-01

    It is thought that reward-induced motivation influences perceptual, attentional, and cognitive control processes to facilitate behavioral performance. In this study, we investigated the effect of reward-induced motivation on exogenous attention orienting and inhibition of return (IOR). Attention was

  3. Extracellular DNA Contributes to Dental Biofilm Stability

    DEFF Research Database (Denmark)

    Schlafer, Sebastian; Meyer, Rikke Louise; Dige, Irene

    2017-01-01

    dental biofilms. This study aimed to determine whether eDNA was part of the matrix in biofilms grown in situ in the absence of sucrose and whether treatment with DNase dispersed biofilms grown for 2.5, 5, 7.5, 16.5, or 24 h. Three hundred biofilms from 10 study participants were collected and treated...... the amount of biofilm in very early stages of growth (up to 7.5 h), but the treatment effect decreased with increasing biofilm age. This study proves the involvement of eDNA in dental biofilm formation and its importance for biofilm stability in the earliest stages. Further research is required to uncover...

  4. The streptococcal collagen-like protein-1 (Scl1 is a significant determinant for biofilm formation by group a Streptococcus

    Directory of Open Access Journals (Sweden)

    Oliver-Kozup Heaven A

    2011-12-01

    Full Text Available Abstract Background Group A Streptococcus (GAS is a human-specific pathogen responsible for a number of diseases characterized by a wide range of clinical manifestations. During host colonization GAS-cell aggregates or microcolonies are observed in tissues. GAS biofilm, which is an in vitro equivalent of tissue microcolony, has only recently been studied and little is known about the specific surface determinants that aid biofilm formation. In this study, we demonstrate that surface-associated streptococcal collagen-like protein-1 (Scl1 plays an important role in GAS biofilm formation. Results Biofilm formation by M1-, M3-, M28-, and M41-type GAS strains, representing an intraspecies breadth, were analyzed spectrophotometrically following crystal violet staining, and characterized using confocal and field emission scanning electron microscopy. The M41-type strain formed the most robust biofilm under static conditions, followed by M28- and M1-type strains, while the M3-type strains analyzed here did not form biofilm under the same experimental conditions. Differences in architecture and cell-surface morphology were observed in biofilms formed by the M1- and M41-wild-type strains, accompanied by varying amounts of deposited extracellular matrix and differences in cell-to-cell junctions within each biofilm. Importantly, all Scl1-negative mutants examined showed significantly decreased ability to form biofilm in vitro. Furthermore, the Scl1 protein expressed on the surface of a heterologous host, Lactococcus lactis, was sufficient to induce biofilm formation by this organism. Conclusions Overall, this work (i identifies variations in biofilm formation capacity among pathogenically different GAS strains, (ii identifies GAS surface properties that may aid in biofilm stability and, (iii establishes that the Scl1 surface protein is an important determinant of GAS biofilm, which is sufficient to enable biofilm formation in the heterologous host

  5. Biofilm and Dental Biomaterials

    Directory of Open Access Journals (Sweden)

    Marit Øilo

    2015-05-01

    Full Text Available All treatment involving the use of biomaterials in the body can affect the host in positive or negative ways. The microbiological environment in the oral cavity is affected by the composition and shape of the biomaterials used for oral restorations. This may impair the patients’ oral health and sometimes their general health as well. Many factors determine the composition of the microbiota and the formation of biofilm in relation to biomaterials such as, surface roughness, surface energy and chemical composition, This paper aims to give an overview of the scientific literature regarding the association between the chemical, mechanical and physical properties of dental biomaterials and oral biofilm formation, with emphasis on current research and future perspectives.

  6. Biofilms promote altruism.

    Science.gov (United States)

    Kreft, Jan-Ulrich

    2004-08-01

    The origin of altruism is a fundamental problem in evolution, and the maintenance of biodiversity is a fundamental problem in ecology. These two problems combine with the fundamental microbiological question of whether it is always advantageous for a unicellular organism to grow as fast as possible. The common basis for these three themes is a trade-off between growth rate and growth yield, which in turn is based on irreversible thermodynamics. The trade-off creates an evolutionary alternative between two strategies: high growth yield at low growth rate versus high growth rate at low growth yield. High growth yield at low growth rate is a case of an altruistic strategy because it increases the fitness of the group by using resources economically at the cost of decreased fitness, or growth rate, of the individual. The group-beneficial behaviour is advantageous in the long term, whereas the high growth rate strategy is advantageous in the short term. Coexistence of species requires differences between their niches, and niche space is typically divided into four 'axes' (time, space, resources, predators). This neglects survival strategies based on cooperation, which extend the possibilities of coexistence, arguing for the inclusion of cooperation as the fifth 'axis'. Here, individual-based model simulations show that spatial structure, as in, for example, biofilms, is necessary for the origin and maintenance of this 'primitive' altruistic strategy and that the common belief that growth rate but not yield decides the outcome of competition is based on chemostat models and experiments. This evolutionary perspective on life in biofilms can explain long-known biofilm characteristics, such as the structural organization into microcolonies, the often-observed lack of mixing among microcolonies, and the shedding of single cells, as promoting the origin and maintenance of the altruistic strategy. Whereas biofilms enrich altruists, enrichment cultures, microbiology's paradigm

  7. [Bacterial biofilms and infection].

    Science.gov (United States)

    Lasa, I; Del Pozo, J L; Penadés, J R; Leiva, J

    2005-01-01

    In developed countries we tend to think of heart disease and the numerous forms of cancer as the main causes of mortality, but on a global scale infectious diseases come close, or may even be ahead: 14.9 million deaths in 2002 compared to cardiovascular diseases (16.9 million deaths) and cancer (7.1 million deaths) (WHO report 2004). The infectious agents responsible for human mortality have evolved as medical techniques and hygienic measures have changed. Modern-day acute infectious diseases caused by specialized bacterial pathogens such as diphtheria, tetanus, cholera, plague, which represented the main causes of death at the beginning of XX century, have been effectively controlled with antibiotics and vaccines. In their place, more than half of the infectious diseases that affect mildly immunocompromised patients involve bacterial species that are commensal with the human body; these can produce chronic infections, are resistant to antimicrobial agents and there is no effective vaccine against them. Examples of these infections are the otitis media, native valve endocarditis, chronic urinary infections, bacterial prostatitis, osteomyelitis and all the infections related to medical devices. Direct analysis of the surface of medical devices or of tissues that have been foci of chronic infections shows the presence of large numbers of bacteria surrounded by an exopolysaccharide matrix, which has been named the "biofilm". Inside the biofilm, bacteria grow protected from the action of the antibodies, phagocytic cells and antimicrobial treatments. In this article, we describe the role of bacterial biofilms in human persistent infections.

  8. Sfp-type PPTase inactivation promotes bacterial biofilm formation and ability to enhance wheat drought tolerance

    Directory of Open Access Journals (Sweden)

    Salme eTimmusk

    2015-05-01

    Full Text Available Paenibacillus polymyxa is a common soil bacterium with broad range of practical applications. An important group of secondary metabolites in P. polymyxa are nonribosomal peptide and polyketide derived metabolites (NRP/PK. Modular nonribosomal peptide synthetases catalyse main steps in the biosynthesis of the complex secondary metabolites. Here we report on the inactivation of an A26 sfp-type phosphopantetheinyl transferase. The inactivation of the gene resulted in loss of NRP/PK production. In contrast to the former Bacillus spp. model the mutant strain compared to wild type showed greatly enhanced biofilm formation ability. Its biofilm promotion is directly mediated by NRP/PK, as exogenous addition of the wild type metabolite extracts restores its biofilm formation level. Wheat inoculation with bacteria that had lost their sfp-type PPTase gene resulted in two times higher plant survival and about three times increased biomass under severe drought stress compared to wild type.

  9. Identification of biofilm-associated cluster (bac in Pseudomonas aeruginosa involved in biofilm formation and virulence.

    Directory of Open Access Journals (Sweden)

    Camille Macé

    Full Text Available Biofilms are prevalent in diseases caused by Pseudomonas aeruginosa, an opportunistic and nosocomial pathogen. By a proteomic approach, we previously identified a hypothetical protein of P. aeruginosa (coded by the gene pA3731 that was accumulated by biofilm cells. We report here that a Delta pA3731 mutant is highly biofilm-defective as compared with the wild-type strain. Using a mouse model of lung infection, we show that the mutation also induces a defect in bacterial growth during the acute phase of infection and an attenuation of the virulence. The pA3731 gene is found to control positively the ability to swarm and to produce extracellular rhamnolipids, and belongs to a cluster of 4 genes (pA3729-pA3732 not previously described in P. aeruginosa. Though the protein PA3731 has a predicted secondary structure similar to that of the Phage Shock Protein, some obvious differences are observed compared to already described psp systems, e.g., this unknown cluster is monocistronic and no homology is found between the other proteins constituting this locus and psp proteins. As E. coli PspA, the amount of the protein PA3731 is enlarged by an osmotic shock, however, not affected by a heat shock. We consequently named this locus bac for biofilm-associated cluster.

  10. Filaments in curved streamlines: rapid formation of Staphylococcus aureus biofilm streamers

    International Nuclear Information System (INIS)

    Kevin Kim, Minyoung; Drescher, Knut; Shun Pak, On; Stone, Howard A; Bassler, Bonnie L

    2014-01-01

    Biofilms are surface-associated conglomerates of bacteria that are highly resistant to antibiotics. These bacterial communities can cause chronic infections in humans by colonizing, for example, medical implants, heart valves, or lungs. Staphylococcus aureus, a notorious human pathogen, causes some of the most common biofilm-related infections. Despite the clinical importance of S. aureus biofilms, it remains mostly unknown how physical effects, in particular flow, and surface structure influence biofilm dynamics. Here we use model microfluidic systems to investigate how environmental factors, such as surface geometry, surface chemistry, and fluid flow affect biofilm development of S. aureus. We discovered that S. aureus rapidly forms flow-induced, filamentous biofilm streamers, and furthermore if surfaces are coated with human blood plasma, streamers appear within minutes and clog the channels more rapidly than if the channels are uncoated. To understand how biofilm streamer filaments reorient in flows with curved streamlines to bridge the distances between corners, we developed a mathematical model based on resistive force theory of slender filaments. Understanding physical aspects of biofilm formation of S. aureus may lead to new approaches for interrupting biofilm formation of this pathogen. (paper)

  11. Biofilm architecture in a novel pressurized biofilm reactor.

    Science.gov (United States)

    Jiang, Wei; Xia, Siqing; Duan, Liang; Hermanowicz, Slawomir W

    2015-01-01

    A novel pure-oxygen pressurized biofilm reactor was operated at different organic loading, mechanical shear and hydrodynamic conditions to understand the relationships between biofilm architecture and its operation. The ultimate goal was to improve the performance of the biofilm reactor. The biofilm was labeled with seven stains and observed with confocal laser scanning microscopy. Unusual biofilm architecture of a ribbon embedded between two surfaces with very few points of attachment was observed. As organic loading increased, the biofilm morphology changed from a moderately rough layer into a locally smoother biomass with significant bulging protuberances, although the chemical oxygen demand (COD) removal efficiency remained unchanged at about 75%. At higher organic loadings, biofilms contained a larger fraction of active cells distributed uniformly within a proteinaceous matrix with decreasing polysaccharide content. Higher hydrodynamic shear in combination with high organic loading resulted in the collapse of biofilm structure and a substantial decrease in reactor performance (a COD removal of 16%). Moreover, the important role of proteins for the spatial distribution of active cells was demonstrated quantitatively.

  12. A Biofilm Matrix-Associated Protease Inhibitor Protects Pseudomonas aeruginosa from Proteolytic Attack.

    Science.gov (United States)

    Tseng, Boo Shan; Reichhardt, Courtney; Merrihew, Gennifer E; Araujo-Hernandez, Sophia A; Harrison, Joe J; MacCoss, Michael J; Parsek, Matthew R

    2018-04-10

    Pseudomonas aeruginosa produces an extracellular biofilm matrix that consists of nucleic acids, exopolysaccharides, lipid vesicles, and proteins. In general, the protein component of the biofilm matrix is poorly defined and understudied relative to the other major matrix constituents. While matrix proteins have been suggested to provide many functions to the biofilm, only proteins that play a structural role have been characterized thus far. Here we identify proteins enriched in the matrix of P. aeruginosa biofilms. We then focused on a candidate matrix protein, the serine protease inhibitor ecotin (PA2755). This protein is able to inhibit neutrophil elastase, a bactericidal enzyme produced by the host immune system during P. aeruginosa biofilm infections. We show that ecotin binds to the key biofilm matrix exopolysaccharide Psl and that it can inhibit neutrophil elastase when associated with Psl. Finally, we show that ecotin protects both planktonic and biofilm P. aeruginosa cells from neutrophil elastase-mediated killing. This may represent a novel mechanism of protection for biofilms to increase their tolerance against the innate immune response. IMPORTANCE Proteins associated with the extracellular matrix of bacterial aggregates called biofilms have long been suggested to provide many important functions to the community. To date, however, only proteins that provide structural roles have been described, and few matrix-associated proteins have been identified. We developed a method to identify matrix proteins and characterized one. We show that this protein, when associated with the biofilm matrix, can inhibit a bactericidal enzyme produced by the immune system during infection and protect biofilm cells from death induced by the enzyme. This may represent a novel mechanism of protection for biofilms, further increasing their tolerance against the immune response. Together, our results are the first to show a nonstructural function for a confirmed matrix

  13. Anti-biofilm activities from marine cold adapted bacteria against staphylococci and Pseudomonas aeruginosa

    Directory of Open Access Journals (Sweden)

    Rosanna ePapa

    2015-12-01

    Full Text Available Microbial biofilms have great negative impacts on the world’s economy and pose serious problems to industry, public health and medicine. The interest in the development of new approaches for the prevention and treatment of bacterial adhesion and biofilm formation has increased. Since, bacterial pathogens living in biofilm induce persistent chronic infections due to the resistance to antibiotics and host immune system. A viable approach should target adhesive properties without affecting bacterial vitality in order to avoid the appearance of resistant mutants. Many bacteria secrete anti-biofilm molecules that function in regulating biofilm architecture or mediating the release of cells from it during the dispersal stage of biofilm life cycle. Cold-adapted marine bacteria represent an untapped reservoir of biodiversity able to synthesize a broad range of bioactive compounds, including anti-biofilm molecules.The anti-biofilm activity of cell-free supernatants derived from sessile and planktonic cultures of cold-adapted bacteria belonging to Pseudoalteromonas, Psychrobacter and Psychromonas species were tested against Staphylococcus aureus, Staphylococcus epidermidis and Pseudomonas aeruginosa strains. Reported results demonstrate that we have selected supernatants, from cold-adapted marine bacteria, containing non-biocidal agents able to destabilize biofilm matrix of all tested pathogens without killing cells. A preliminary physico-chemical characterization of supernatants was also performed, and these analyses highlighted the presence of molecules of different nature that act by inhibiting biofilm formation. Some of them are also able to impair the initial attachment of the bacterial cells to the surface, thus likely containing molecules acting as anti-biofilm surfactant molecules.The described ability of cold-adapted bacteria to produce effective anti-biofilm molecules paves the way to further characterization of the most promising molecules

  14. The transcriptional programme of Salmonella enterica serovar Typhimurium reveals a key role for tryptophan metabolism in biofilms.

    LENUS (Irish Health Repository)

    Hamilton, Shea

    2009-12-11

    exogenous tryptophan or indole. Conclusions Biofilm growth of S. Typhimurium causes distinct changes in gene and protein expression. Our results show that aromatic amino acids make an important contribution to biofilm formation and reveal a link between SPI2 expression and surface-associated growth in S. Typhimurium.

  15. Staphylococcus aureus biofilms: recent developments in biofilm dispersal.

    Science.gov (United States)

    Lister, Jessica L; Horswill, Alexander R

    2014-01-01

    Staphylococcus aureus is a major cause of nosocomial and community-acquired infections and represents a significant burden on the healthcare system. S. aureus attachment to medical implants and host tissue, and the establishment of a mature biofilm, play an important role in the persistence of chronic infections. The formation of a biofilm, and encasement of cells in a polymer-based matrix, decreases the susceptibility to antimicrobials and immune defenses, making these infections difficult to eradicate. During infection, dispersal of cells from the biofilm can result in spread to secondary sites and worsening of the infection. In this review, we discuss the current understanding of the pathways behind biofilm dispersal in S. aureus, with a focus on enzymatic and newly described broad-spectrum dispersal mechanisms. Additionally, we explore potential applications of dispersal in the treatment of biofilm-mediated infections.

  16. Endogenous vs. exogenous regulations in the commons

    DEFF Research Database (Denmark)

    Abatayo, Anna Lou; Lynham, John

    2016-01-01

    It is widely believed that there is strong experimental evidence to support the idea that exogenously imposed regulations crowd out the intrinsic motivations of common pool resource (CPR) users to refrain from over-harvesting. We introduce a novel experimental design that attempts to disentangle...... potential confounds in previous experiments. A key feature of our experimental design is to have the exact same regulations chosen endogenously as those that are imposed exogenously. When we compare the same regulations chosen endogenously to those externally imposed, we observe no differences in extraction...... endogenous regulations with communication and exogenous regulations without communication. Our results suggest that externally imposed regulations do not crowd out intrinsic motivations in the lab and they confirm that communication facilitates cooperation to reduce extraction....

  17. Emergent pattern formation in an interstitial biofilm

    Science.gov (United States)

    Zachreson, Cameron; Wolff, Christian; Whitchurch, Cynthia B.; Toth, Milos

    2017-01-01

    Collective behavior of bacterial colonies plays critical roles in adaptability, survivability, biofilm expansion and infection. We employ an individual-based model of an interstitial biofilm to study emergent pattern formation based on the assumptions that rod-shaped bacteria furrow through a viscous environment and excrete extracellular polymeric substances which bias their rate of motion. Because the bacteria furrow through their environment, the substratum stiffness is a key control parameter behind the formation of distinct morphological patterns. By systematically varying this property (which we quantify with a stiffness coefficient γ ), we show that subtle changes in the substratum stiffness can give rise to a stable state characterized by a high degree of local order and long-range pattern formation. The ordered state exhibits characteristics typically associated with bacterial fitness advantages, even though it is induced by changes in environmental conditions rather than changes in biological parameters. Our findings are applicable to a broad range of biofilms and provide insights into the relationship between bacterial movement and their environment, and basic mechanisms behind self-organization of biophysical systems.

  18. Experimental evolution in biofilm populations

    Science.gov (United States)

    Steenackers, Hans P.; Parijs, Ilse; Foster, Kevin R.; Vanderleyden, Jozef

    2016-01-01

    Biofilms are a major form of microbial life in which cells form dense surface associated communities that can persist for many generations. The long-life of biofilm communities means that they can be strongly shaped by evolutionary processes. Here, we review the experimental study of evolution in biofilm communities. We first provide an overview of the different experimental models used to study biofilm evolution and their associated advantages and disadvantages. We then illustrate the vast amount of diversification observed during biofilm evolution, and we discuss (i) potential ecological and evolutionary processes behind the observed diversification, (ii) recent insights into the genetics of adaptive diversification, (iii) the striking degree of parallelism between evolution experiments and real-life biofilms and (iv) potential consequences of diversification. In the second part, we discuss the insights provided by evolution experiments in how biofilm growth and structure can promote cooperative phenotypes. Overall, our analysis points to an important role of biofilm diversification and cooperation in bacterial survival and productivity. Deeper understanding of both processes is of key importance to design improved antimicrobial strategies and diagnostic techniques. PMID:26895713

  19. Microalgal biofilms for wastewater treatment

    NARCIS (Netherlands)

    Boelee, N.C.

    2013-01-01

    The objective of this thesis was to explore the possibilities of using microalgal biofilms for the treatment of municipal wastewater, with a focus on the post-treatment of municipal wastewater effluent. The potential of microalgal biofilms for wastewater treatment was first investigated using a

  20. Microbial ecology of phototrophic biofilms

    NARCIS (Netherlands)

    Roeselers, G.

    2007-01-01

    Biofilms are layered structures of microbial cells and an extracellular matrix of polymeric substances, associated with surfaces and interfaces. Biofilms trap nutrients for growth of the enclosed microbial community and help prevent detachment of cells from surfaces in flowing systems. Phototrophic

  1. Bacterial Biofilms in Jones Tubes.

    Science.gov (United States)

    Ahn, Eric S; Hauck, Matthew J; Kirk Harris, Jonathan; Robertson, Charles E; Dailey, Roger A

    To investigate the presence and microbiology of bacterial biofilms on Jones tubes (JTs) by direct visualization with scanning electron microscopy and polymerase chain reaction (PCR) of representative JTs, and to correlate these findings with inflammation and/or infection related to the JT. In this study, prospective case series were performed. JTs were recovered from consecutive patients presenting to clinic for routine cleaning or recurrent irritation/infection. Four tubes were processed for scanning electron microscopy alone to visualize evidence of biofilms. Two tubes underwent PCR alone for bacterial quantification. One tube was divided in half and sent for scanning electron microscopy and PCR. Symptoms related to the JTs were recorded at the time of recovery. Seven tubes were obtained. Five underwent SEM, and 3 out of 5 showed evidence of biofilms (60%). Two of the 3 biofilms demonstrated cocci and the third revealed rods. Three tubes underwent PCR. The predominant bacteria identified were Pseudomonadales (39%), Pseudomonas (16%), and Staphylococcus (14%). Three of the 7 patients (43%) reported irritation and discharge at presentation. Two symptomatic patients, whose tubes were imaged only, revealed biofilms. The third symptomatic patient's tube underwent PCR only, showing predominantly Staphylococcus (56%) and Haemophilus (36%) species. Two of the 4 asymptomatic patients also showed biofilms. All symptomatic patients improved rapidly after tube exchange and steroid antibiotic drops. Bacterial biofilms were variably present on JTs, and did not always correlate with patients' symptoms. Nevertheless, routine JT cleaning is recommended to treat and possibly prevent inflammation caused by biofilms.

  2. Interaction of Nanoparticles with Biofilms

    Science.gov (United States)

    In this work we have studied the interaction and adsorption of engineered nanoparticles such as TiO2, ZnO, CeO2 , and carbon nanotubes with biofilms. Biofilm is an extracellular polymeric substance coating comprised of living material and it is an aggregation of bacteria, algae, ...

  3. Physiological Function of Rac Prophage During Biofilm Formation and Regulation of Rac Excision in Escherichia coli K-12

    Science.gov (United States)

    including Escherichia coli, Salmonella spp. and Shigellaspp. Here, we found that rac excision is induced during biofilm formation, and the isogenic...stain without rac is more motile and forms more biofilms in nutrient-rich medium at early stages in E.coli K-12. Additionally, the presence of rac...genes increases cell lysis during biofilm development. In most E. coli strains, rac is integrated into the ttcA gene which encodes a tRNA-thioltransferase

  4. Characteristics of exogenous carbon monoxide deliveries

    Directory of Open Access Journals (Sweden)

    Hui-jun Hu

    2016-01-01

    Full Text Available Carbon monoxide (CO has long been considered an environmental pollutant and a poison. Exogenous exposure to amounts of CO beyond the physiologic level of the body can result in a protective or adaptive response. However, as a gasotransmitter, endogenous CO is important for multiple physiologic functions. To date, at least seven distinct methods of delivering CO have been utilized in animal and clinical studies. In this mini-review, we summarize the exogenous CO delivery methods and compare their advantages and disadvantages.

  5. Biofilm models of polymicrobial infection.

    Science.gov (United States)

    Gabrilska, Rebecca A; Rumbaugh, Kendra P

    2015-01-01

    Interactions between microbes are complex and play an important role in the pathogenesis of infections. These interactions can range from fierce competition for nutrients and niches to highly evolved cooperative mechanisms between different species that support their mutual growth. An increasing appreciation for these interactions, and desire to uncover the mechanisms that govern them, has resulted in a shift from monomicrobial to polymicrobial biofilm studies in different disease models. Here we provide an overview of biofilm models used to study select polymicrobial infections and highlight the impact that the interactions between microbes within these biofilms have on disease progression. Notable recent advances in the development of polymicrobial biofilm-associated infection models and challenges facing the study of polymicrobial biofilms are addressed.

  6. Antibiotic resistance of bacterial biofilms

    DEFF Research Database (Denmark)

    Hoiby, N.; Bjarnsholt, T.; Givskov, M.

    2010-01-01

    A biofilm is a structured consortium of bacteria embedded in a self-produced polymer matrix consisting of polysaccharide, protein and DNA. Bacterial biofilms cause chronic infections because they show increased tolerance to antibiotics and disinfectant chemicals as well as resisting phagocytosis...... and other components of the body's defence system. The persistence of, for example, staphylococcal infections related to foreign bodies is due to biofilm formation. Likewise, chronic Pseudomonas aeruginosa lung infection in cystic fibrosis patients is caused by biofilm-growing mucoid strains....... Characteristically, gradients of nutrients and oxygen exist from the top to the bottom of biofilms and these gradients are associated with decreased bacterial metabolic activity and increased doubling times of the bacterial cells; it is these more or less dormant cells that are responsible for some of the tolerance...

  7. Antibiotic tolerance and microbial biofilms

    DEFF Research Database (Denmark)

    Folkesson, Anders

    Increased tolerance to antimicrobial agents is thought to be an important feature of microbes growing in biofilms. We study the dynamics of antibiotic action within hydrodynamic flow chamber biofilms of Escherichia coli and Pseudomonas aeruginosa using isogenic mutants and fluorescent gene...... expression reporters and we address the question of how biofilm organization affects antibiotic susceptibility. The dynamics of microbial killing is monitored by viable count determination, and confocal laser microscopy. Our work shows that the apparent increased antibiotic tolerance is due to the formation...... of antibiotic tolerant subpopulations within the biofilm. The formation of these subpopulations is highly variable and dependent on the antibiotic used, the biofilm structural organization and the induction of specific tolerance mechanisms....

  8. Exopolysaccharides regulate calcium flow in cariogenic biofilms

    Science.gov (United States)

    Varenganayil, Muth M.; Decho, Alan W.

    2017-01-01

    Caries-associated biofilms induce loss of calcium from tooth surfaces in the presence of dietary carbohydrates. Exopolysaccharides (EPS) provide a matrix scaffold and an abundance of primary binding sites within biofilms. The role of EPS in binding calcium in cariogenic biofilms is only partially understood. Thus, the aim of the present study is to investigate the relationship between the calcium dissolution rates and calcium tolerance of caries-associated bacteria and yeast as well as to examine the properties of EPS to quantify its binding affinity for dissolved calcium. Calcium dissolution was measured by dissolution zones on Pikovskaya’s agar. Calcium tolerance was assessed by isothermal microcalorimetry (IMC) by adding CaCl2 to the bacterial cultures. Acid-base titration and Fourier transform infrared (FTIR) spectroscopy were used to identify possible functional groups responsible for calcium binding, which was assessed by isothermal titration calorimetry (ITC). Lactobacillus spp. and mutans streptococci demonstrated calcium dissolution in the presence of different carbohydrates. All strains that demonstrated high dissolution rates also revealed higher rates of calcium tolerance by IMC. In addition, acidic functional groups were predominantly identified as possible binding sites for calcium ions by acid-base titration and FTIR. Finally, ITC revealed EPS to have a higher binding affinity for calcium compared, for example, to lactic acid. In conclusion, this study illustrates the role of EPS in terms of the calcium tolerance of cariogenic microbiota by determining the ability of EPS to control free calcium concentrations within the biofilms as a self-regulating mode of action in the pathogenesis of dental caries. PMID:29023506

  9. Exopolysaccharides regulate calcium flow in cariogenic biofilms.

    Directory of Open Access Journals (Sweden)

    Monika Astasov-Frauenhoffer

    Full Text Available Caries-associated biofilms induce loss of calcium from tooth surfaces in the presence of dietary carbohydrates. Exopolysaccharides (EPS provide a matrix scaffold and an abundance of primary binding sites within biofilms. The role of EPS in binding calcium in cariogenic biofilms is only partially understood. Thus, the aim of the present study is to investigate the relationship between the calcium dissolution rates and calcium tolerance of caries-associated bacteria and yeast as well as to examine the properties of EPS to quantify its binding affinity for dissolved calcium. Calcium dissolution was measured by dissolution zones on Pikovskaya's agar. Calcium tolerance was assessed by isothermal microcalorimetry (IMC by adding CaCl2 to the bacterial cultures. Acid-base titration and Fourier transform infrared (FTIR spectroscopy were used to identify possible functional groups responsible for calcium binding, which was assessed by isothermal titration calorimetry (ITC. Lactobacillus spp. and mutans streptococci demonstrated calcium dissolution in the presence of different carbohydrates. All strains that demonstrated high dissolution rates also revealed higher rates of calcium tolerance by IMC. In addition, acidic functional groups were predominantly identified as possible binding sites for calcium ions by acid-base titration and FTIR. Finally, ITC revealed EPS to have a higher binding affinity for calcium compared, for example, to lactic acid. In conclusion, this study illustrates the role of EPS in terms of the calcium tolerance of cariogenic microbiota by determining the ability of EPS to control free calcium concentrations within the biofilms as a self-regulating mode of action in the pathogenesis of dental caries.

  10. Impact of Hydrodynamics on Oral Biofilm Strength

    NARCIS (Netherlands)

    Paramonova, E.; Kalmykowa, O. J.; van der Mei, H. C.; Busscher, H. J.; Sharma, P. K.

    2009-01-01

    Mechanical removal of oral biofilms is ubiquitously accepted as the best way to prevent caries and periodontal diseases. Removal effectiveness strongly depends on biofilm strength. To investigate the influence of hydrodynamics on oral biofilm strength, we grew single- and multi-species biofilms of

  11. Confocal microscopy imaging of the biofilm matrix

    DEFF Research Database (Denmark)

    Schlafer, Sebastian; Meyer, Rikke L

    2017-01-01

    The extracellular matrix is an integral part of microbial biofilms and an important field of research. Confocal laser scanning microscopy is a valuable tool for the study of biofilms, and in particular of the biofilm matrix, as it allows real-time visualization of fully hydrated, living specimens...... the concentration of solutes and the diffusive properties of the biofilm matrix....

  12. Oral Biofilm Architecture on Natural Teeth

    NARCIS (Netherlands)

    Zijnge, Vincent; van Leeuwen, M. Barbara M.; Degener, John E.; Abbas, Frank; Thurnheer, Thomas; Gmuer, Rudolf; Harmsen, Hermie J. M.

    2010-01-01

    Periodontitis and caries are infectious diseases of the oral cavity in which oral biofilms play a causative role. Moreover, oral biofilms are widely studied as model systems for bacterial adhesion, biofilm development, and biofilm resistance to antibiotics, due to their widespread presence and

  13. Bacterial biofilms: prokaryotic adventures in multicellularity

    DEFF Research Database (Denmark)

    Webb, J.S.; Givskov, Michael Christian; Kjelleberg, S.

    2003-01-01

    The development of bacterial biofilms includes both the initial social behavior of undifferentiated cells, as well as cell death and differentiation in the mature biofilm, and displays several striking similarities with higher organisms. Recent advances in the field provide new insight...... into differentiation and cell death events in bacterial biofilm development and propose that biofilms have an unexpected level of multicellularity....

  14. Shewanella putrefaciens adhesion and biofilm formation on food processing surfaces

    DEFF Research Database (Denmark)

    Bagge, Dorthe; Hjelm, M.; Johansen, C.

    2001-01-01

    Laboratory model systems were developed for studying Shewanella putrefaciens adhesion and biofilm formation under batch and flow conditions. S. putrefaciens plays a major role in food spoilage and may cause microbially induced corrosion on steel surfaces. S. putrefaciens bacteria suspended in buf...... from surfaces, and indirect conductometry and found this combination sufficient to quantify bacteria on surfaces...

  15. Biofilm attachment reduction on bioinspired, dynamic, micro-wrinkling surfaces

    International Nuclear Information System (INIS)

    Epstein, Alexander K; Hong, Donggyoon; Kim, Philseok; Aizenberg, Joanna

    2013-01-01

    Most bacteria live in multicellular communities known as biofilms that are adherent to surfaces in our environment, from sea beds to plumbing systems. Biofilms are often associated with clinical infections, nosocomial deaths and industrial damage such as bio-corrosion and clogging of pipes. As mature biofilms are extremely challenging to eradicate once formed, prevention is advantageous over treatment. However, conventional surface chemistry strategies are either generally transient, due to chemical masking, or toxic, as in the case of leaching marine antifouling paints. Inspired by the nonfouling skins of echinoderms and other marine organisms, which possess highly dynamic surface structures that mechanically frustrate bio-attachment, we have developed and tested a synthetic platform based on both uniaxial mechanical strain and buckling-induced elastomer microtopography. Bacterial biofilm attachment to the dynamic substrates was studied under an array of parameters, including strain amplitude and timescale (1–100 mm s −1 ), surface wrinkle length scale, bacterial species and cell geometry, and growth time. The optimal conditions for achieving up to ∼ 80% Pseudomonas aeruginosa biofilm reduction after 24 h growth and ∼ 60% reduction after 48 h were combinatorially elucidated to occur at 20% strain amplitude, a timescale of less than ∼ 5 min between strain cycles and a topography length scale corresponding to the cell dimension of ∼ 1 μm. Divergent effects on the attachment of P. aeruginosa, Staphylococcus aureus and Escherichia coli biofilms showed that the dynamic substrate also provides a new means of species-specific biofilm inhibition, or inversely, selection for a desired type of bacteria, without reliance on any toxic or transient surface chemical treatments. (paper)

  16. Biofilm attachment reduction on bioinspired, dynamic, micro-wrinkling surfaces

    Science.gov (United States)

    Epstein, Alexander K.; Hong, Donggyoon; Kim, Philseok; Aizenberg, Joanna

    2013-09-01

    Most bacteria live in multicellular communities known as biofilms that are adherent to surfaces in our environment, from sea beds to plumbing systems. Biofilms are often associated with clinical infections, nosocomial deaths and industrial damage such as bio-corrosion and clogging of pipes. As mature biofilms are extremely challenging to eradicate once formed, prevention is advantageous over treatment. However, conventional surface chemistry strategies are either generally transient, due to chemical masking, or toxic, as in the case of leaching marine antifouling paints. Inspired by the nonfouling skins of echinoderms and other marine organisms, which possess highly dynamic surface structures that mechanically frustrate bio-attachment, we have developed and tested a synthetic platform based on both uniaxial mechanical strain and buckling-induced elastomer microtopography. Bacterial biofilm attachment to the dynamic substrates was studied under an array of parameters, including strain amplitude and timescale (1-100 mm s-1), surface wrinkle length scale, bacterial species and cell geometry, and growth time. The optimal conditions for achieving up to ˜ 80% Pseudomonas aeruginosa biofilm reduction after 24 h growth and ˜ 60% reduction after 48 h were combinatorially elucidated to occur at 20% strain amplitude, a timescale of less than ˜ 5 min between strain cycles and a topography length scale corresponding to the cell dimension of ˜ 1 μm. Divergent effects on the attachment of P. aeruginosa, Staphylococcus aureus and Escherichia coli biofilms showed that the dynamic substrate also provides a new means of species-specific biofilm inhibition, or inversely, selection for a desired type of bacteria, without reliance on any toxic or transient surface chemical treatments.

  17. Effect of exogenous phytohormones and sucrose on ...

    African Journals Online (AJOL)

    The effect of exogenous phytohormones and sucrose on micropropagation and microtuberization from nodal cuttings of Manihot esculenta was studied. Direct and indirect organogeneses were established from these explants. When nodal cuttings were cultured in the presence of 0.01 to 0.1 mg.L-1 of BAP or NAA there was ...

  18. Exogenous fibrolytic enzymes to unlock nutrients: Histological ...

    African Journals Online (AJOL)

    There is a need for a better understanding of the mode-of-action of exogenous fibrolytic enzymes (EFE) used as additives in ruminant feeds. Four forages, treated with EFE, were evaluated in vitro and histologically, in an attempt to determine the effect of EFE on tissue degradation. Weeping love grass, kikuyu leaf material, ...

  19. Metabolic response to exogenous ethanol in yeast

    Indian Academy of Sciences (India)

    In this study, we applied this approach to evaluate the effects of increasing concentration of exogenous ethanol on the Saccharomyces cerevisiae fermentative metabolism. We show that the STOCSY analysis correctly identifies the different types of correlations among the enriched metabolites involved in the fermentation, ...

  20. Open Syllable Once Again. Endogenous or Exogenous?

    Directory of Open Access Journals (Sweden)

    Raffaele Caldarelli

    2013-02-01

    Full Text Available After a brief reply to some critical remarks raised by Mario Enrietti in a paper published in “Studi Slavistici”, VI (2009, the Author tries to explain why Enrietti’s theory of an exogenous, namely Romance origin of the Slavic open syllable structure should be rejected.

  1. Growing and analyzing biofilms in flow chambers

    DEFF Research Database (Denmark)

    Tolker-Nielsen, Tim; Sternberg, Claus

    2011-01-01

    This unit describes the setup of flow chamber systems for the study of microbial biofilms, and methods for the analysis of structural biofilm formation. Use of flow chambers allows direct microscopic investigation of biofilm formation. The biofilms in flow chambers develop under hydrodynamic......, and disassembly and cleaning of the system. In addition, embedding and fluorescent in situ hybridization of flow chamber-grown biofilms are addressed....

  2. Characterization of the effect of serum and chelating agents on Staphylococcus aureus biofilm formation; chelating agents augment biofilm formation through clumping factor B

    Science.gov (United States)

    Abraham, Nabil Mathew

    Staphylococcus aureus is the causative agent of a diverse array of acute and chronic infections, and some these infections, including infective endocarditis, joint infections, and medical device-associated bloodstream infections, depend upon its capacity to form tenacious biofilms on surfaces. Inserted medical devices such as intravenous catheters, pacemakers, and artificial heart valves save lives, but unfortunately, they can also serve as a substrate on which S. aureus can form a biofilm, attributing S. aureus as a leading cause of medical device-related infections. The major aim of this work was take compounds to which S. aureus would be exposed during infection and to investigate their effects on its capacity to form a biofilm. More specifically, the project investigated the effects of serum, and thereafter of catheter lock solutions on biofilm formation by S. aureus. Pre-coating polystyrene with serum is frequently used as a method to augment biofilm formation. The effect of pre-coating with serum is due to the deposition of extracellular matrix components onto the polystyrene, which are then recognized by MSCRAMMs. We therefore hypothesized that the major component of blood, serum, would induce biofilm formation. Surprisingly, serum actually inhibited biofilm formation. The inhibitory activity was due to a small molecular weight, heat-stable, non-proteinaceous component/s of serum. Serum-mediated inhibition of biofilm formation may represent a previously uncharacterized aspect of host innate immunity that targets the expression of a key bacterial virulence factor: the ability to establish a resistant biofilm. Metal ion chelators like sodium citrate are frequently chosen to lock intravenous catheters because they are regarded as potent inhibitors of bacterial biofilm formation and viability. We found that, while chelating compounds abolished biofilm formation in most strains of S. aureus, they actually augmented the phenotype in a subset of strains. We

  3. Conductive properties of methanogenic biofilms.

    Science.gov (United States)

    Li, Cheng; Lesnik, Keaton Larson; Liu, Hong

    2018-02-01

    Extracellular electron transfer between syntrophic partners needs to be efficiently maintained in methanogenic environments. Direct extracellular electron transfer via electrical current is an alternative to indirect hydrogen transfer but requires construction of conductive extracellular structures. Conductive mechanisms and relationship between conductivity and the community composition in mixed-species methanogenic biofilms are not well understood. The present study investigated conductive behaviors of methanogenic biofilms and examined the correlation between biofilm conductivity and community composition between different anaerobic biofilms enriched from the same inoculum. Highest conductivity observed in methanogenic biofilms was 71.8±4.0μS/cm. Peak-manner response of conductivity upon changes over a range of electrochemical potentials suggests that electron transfer in methanogenic biofilms occurs through redox driven super-exchange. The strong correlation observed between biofilm conductivity and Geobacter spp. in the metabolically diverse anaerobic communities suggests that the efficiency of DEET may provide pressure for microbial communities to select for species that can produce electrical conduits. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Rewards modulate saccade latency but not exogenous spatial attention.

    Directory of Open Access Journals (Sweden)

    Stephen eDunne

    2015-07-01

    Full Text Available The eye movement system is sensitive to reward. However, whilst the eye movement system is extremely flexible, the extent to which changes to oculomotor behaviour induced by reward paradigms persist beyond the training period or transfer to other oculomotor tasks is unclear. To address these issues we examined the effects of presenting feedback that represented small monetary rewards to spatial locations on the latency of saccadic eye movements, the time-course of learning and extinction of the effects of rewarding saccades on exogenous spatial attention and oculomotor IOR. Reward feedback produced a relative facilitation of saccadic latency in a stimulus driven saccade task which persisted for 3 blocks of extinction trials. However this hemifield-specific effect failed to transfer to peripheral cueing tasks. We conclude that rewarding specific spatial locations is unlikely to induce long-term, systemic changes to the human oculomotor or attention systems.

  5. Rewards modulate saccade latency but not exogenous spatial attention.

    Science.gov (United States)

    Dunne, Stephen; Ellison, Amanda; Smith, Daniel T

    2015-01-01

    The eye movement system is sensitive to reward. However, whilst the eye movement system is extremely flexible, the extent to which changes to oculomotor behavior induced by reward paradigms persist beyond the training period or transfer to other oculomotor tasks is unclear. To address these issues we examined the effects of presenting feedback that represented small monetary rewards to spatial locations on the latency of saccadic eye movements, the time-course of learning and extinction of the effects of rewarding saccades on exogenous spatial attention and oculomotor inhibition of return. Reward feedback produced a relative facilitation of saccadic latency in a stimulus driven saccade task which persisted for three blocks of extinction trials. However, this hemifield-specific effect failed to transfer to peripheral cueing tasks. We conclude that rewarding specific spatial locations is unlikely to induce long-term, systemic changes to the human oculomotor or attention systems.

  6. MECHANISMS IN ENDOCRINOLOGY: Exogenous insulin does not increase muscle protein synthesis rate when administered systemically: a systematic review.

    Science.gov (United States)

    Trommelen, Jorn; Groen, Bart B L; Hamer, Henrike M; de Groot, Lisette C P G M; van Loon, Luc J C

    2015-07-01

    Though it is well appreciated that insulin plays an important role in the regulation of muscle protein metabolism, there is much discrepancy in the literature on the capacity of exogenous insulin administration to increase muscle protein synthesis rates in vivo in humans. To assess whether exogenous insulin administration increases muscle protein synthesis rates in young and older adults. A systematic review of clinical trials was performed and the presence or absence of an increase in muscle protein synthesis rate was reported for each individual study arm. In a stepwise manner, multiple models were constructed that excluded study arms based on the following conditions: model 1, concurrent hyperaminoacidemia; model 2, insulin-induced hypoaminoacidemia; model 3, supraphysiological insulin concentrations; and model 4, older, more insulin resistant, subjects. From the presented data in the current systematic review, we conclude that: i) exogenous insulin and amino acid administration effectively increase muscle protein synthesis, but this effect is attributed to the hyperaminoacidemia; ii) exogenous insulin administered systemically induces hypoaminoacidemia which obviates any insulin-stimulatory effect on muscle protein synthesis; iii) exogenous insulin resulting in supraphysiological insulin levels exceeding 50, 000  pmol/l may effectively augment muscle protein synthesis; iv) exogenous insulin may have a diminished effect on muscle protein synthesis in older adults due to age-related anabolic resistance; and v) exogenous insulin administered systemically does not increase muscle protein synthesis in healthy, young adults. © 2015 European Society of Endocrinology.

  7. Uranium speciation in biofilms studies by laser fluorescence techniques

    International Nuclear Information System (INIS)

    Arnold, Thuro; Grossmann, Kay; Baumann, Nils

    2010-01-01

    Biofilms may immobilize toxic heavy metals in the environment and thereby influence their migration behaviour. The mechanisms of these processes are currently not understood, because the complexity of such biofilms creates many discrete geochemical microenvironments which may differ from the surrounding bulk solution in their bacterial diversity, their prevailing geochemical properties, e.g. pH and dissolved oxygen concentration, the presence of organic molecules, e.g. metabolites, and many more, all of which may affect metal speciation. To obtain such information, which is necessary for performance assessment studies or the development of new cost-effective strategies for cleaning waste waters, it is very important to develop new non-invasive methods applicable to study the interactions of metals within biofilm systems. Laser fluorescence techniques have some superior features, above all very high sensitivity for fluorescent heavy metals. An approach combining confocal laser scanning microscopy and laser-induced fluorescence spectroscopy for study of the interactions of biofilms with uranium is presented. It was found that coupling these techniques furnishes a promising tool for in-situ non-invasive study of fluorescent heavy metals within biofilm systems. Information on uranium speciation and uranium redox states can be obtained.

  8. Adaptation to copper stress influences biofilm formation in Alteromonas macleodii.

    Science.gov (United States)

    Cusick, Kathleen D; Dale, Jason R; Fitzgerald, Lisa A; Little, Brenda J; Biffinger, Justin C

    2017-07-01

    An Alteromonas macleodii strain was isolated from copper-containing coupons incubated in surface seawater (Key West, FL, USA). In addition to the original isolate, a copper-adapted mutant was created and maintained with 0.78 mM Cu 2+ . Biofilm formation was compared between the two strains under copper-amended and low-nutrient conditions. Biofilm formation was significantly increased in the original isolate under copper amendment, while biofilm formation was significantly higher in the mutant under low-nutrient conditions. Biofilm expression profiles of diguanylate cyclase (DGC) genes, as well as genes involved in secretion, differed between the strains. Comparative genomic analysis demonstrated that both strains possessed a large number of gene attachment harboring cyclic di-GMP synthesis and/or degradation domains. One of the DGC genes, induced at very high levels in the mutant, possessed a degradation domain in the original isolate that was lacking in the mutant. The genetic and transcriptional mechanisms contributing to biofilm formation are discussed.

  9. Marine biofilm bacteria evade eukaryotic predation by targeted chemical defense.

    Directory of Open Access Journals (Sweden)

    Carsten Matz

    Full Text Available Many plants and animals are defended from predation or herbivory by inhibitory secondary metabolites, which in the marine environment are very common among sessile organisms. Among bacteria, where there is the greatest metabolic potential, little is known about chemical defenses against bacterivorous consumers. An emerging hypothesis is that sessile bacterial communities organized as biofilms serve as bacterial refuge from predation. By testing growth and survival of two common bacterivorous nanoflagellates, we find evidence that chemically mediated resistance against protozoan predators is common among biofilm populations in a diverse set of marine bacteria. Using bioassay-guided chemical and genetic analysis, we identified one of the most effective antiprotozoal compounds as violacein, an alkaloid that we demonstrate is produced predominately within biofilm cells. Nanomolar concentrations of violacein inhibit protozoan feeding by inducing a conserved eukaryotic cell death program. Such biofilm-specific chemical defenses could contribute to the successful persistence of biofilm bacteria in various environments and provide the ecological and evolutionary context for a number of eukaryote-targeting bacterial metabolites.

  10. Biofilm models for the practitioner

    DEFF Research Database (Denmark)

    Morgenroth, Eberhard Friedrich; van Loosdrecht, M. C. M.; Wanner, O.

    2000-01-01

    Even though mathematical biofilm models are extensively used in biofilm research, there has been very little application of these models in the engineering practice so far. However, practitioners would be interested in models that can be used as tools to control plant operation under dynamic...... conditions or to help them handle complex interactions between particle removal, carbon oxidation, nitrification, denitrification and biological phosphorus removal. But even though there is a whole range of biofilm models available, it is difficult for the practitioner to select the appropriate modeling...

  11. Shell biofilm-associated nitrous oxide production in marine molluscs: processes, precursors and relative importance.

    Science.gov (United States)

    Heisterkamp, Ines M; Schramm, Andreas; Larsen, Lone H; Svenningsen, Nanna B; Lavik, Gaute; de Beer, Dirk; Stief, Peter

    2013-07-01

    Emission of the greenhouse gas nitrous oxide (N2 O) from freshwater and terrestrial invertebrates has exclusively been ascribed to N2 O production by ingested denitrifying bacteria in the anoxic gut of the animals. Our study of marine molluscs now shows that also microbial biofilms on shell surfaces are important sites of N2 O production. The shell biofilms of Mytilus edulis, Littorina littorea and Hinia reticulata contributed 18-94% to the total animal-associated N2 O emission. Nitrification and denitrification were equally important sources of N2 O in shell biofilms as revealed by (15) N-stable isotope experiments with dissected shells. Microsensor measurements confirmed that both nitrification and denitrification can occur in shell biofilms due to a heterogeneous oxygen distribution. Accordingly, ammonium, nitrite and nitrate were important drivers of N2 O production in the shell biofilm of the three mollusc species. Ammonium excretion by the animals was found to be sufficient to sustain N2 O production in the shell biofilm. Apparently, the animals provide a nutrient-enriched microenvironment that stimulates growth and N2 O production of the shell biofilm. This animal-induced stimulation was demonstrated in a long-term microcosm experiment with the snail H. reticulata, where shell biofilms exhibited the highest N2 O emission rates when the animal was still living inside the shell. © 2012 John Wiley & Sons Ltd and Society for Applied Microbiology.

  12. Inhibition and dispersal of Agrobacterium tumefaciens biofilms by a small diffusible Pseudomonas aeruginosa exoproduct(s).

    Science.gov (United States)

    Hibbing, Michael E; Fuqua, Clay

    2012-06-01

    Environmental biofilms often contain mixed populations of different species. In these dense communities, competition between biofilm residents for limited nutrients such as iron can be fierce, leading to the evolution of competitive factors that affect the ability of competitors to grow or form biofilms. We have discovered a compound(s) present in the conditioned culture fluids of Pseudomonas aeruginosa that disperses and inhibits the formation of biofilms produced by the facultative plant pathogen Agrobacterium tumefaciens. The inhibitory activity is strongly induced when P. aeruginosa is cultivated in iron-limited conditions, but it does not function through iron sequestration. In addition, the production of the biofilm inhibitory activity is not regulated by the global iron regulatory protein Fur, the iron-responsive extracytoplasmic function σ factor PvdS, or three of the recognized P. aeruginosa quorum-sensing systems. In addition, the compound(s) responsible for the inhibition and dispersal of A. tumefaciens biofilm formation is likely distinct from the recently identified P. aeruginosa dispersal factor, cis-2-decenoic acid (CDA), as dialysis of the culture fluids showed that the inhibitory compound was larger than CDA and culture fluids that dispersed and inhibited biofilm formation by A. tumefaciens had no effect on biofilm formation by P. aeruginosa.

  13. Stratified growth in Pseudomonas aeruginosa biofilms

    DEFF Research Database (Denmark)

    Werner, E.; Roe, F.; Bugnicourt, A.

    2004-01-01

    In this study, stratified patterns of protein synthesis and growth were demonstrated in Pseudomonas aeruginosa biofilms. Spatial patterns of protein synthetic activity inside biofilms were characterized by the use of two green fluorescent protein (GFP) reporter gene constructs. One construct...... synthesis was restricted to a narrow band in the part of the biofilm adjacent to the source of oxygen. The zone of active GFP expression was approximately 60 Am wide in colony biofilms and 30 Am wide in flow cell biofilms. The region of the biofilm in which cells were capable of elongation was mapped...... by treating colony biofilms with carbenicillin, which blocks cell division, and then measuring individual cell lengths by transmission electron microscopy. Cell elongation was localized at the air interface of the biofilm. The heterogeneous anabolic patterns measured inside these biofilms were likely a result...

  14. Novel method for quantitative estimation of biofilms

    DEFF Research Database (Denmark)

    Syal, Kirtimaan

    2017-01-01

    Biofilm protects bacteria from stress and hostile environment. Crystal violet (CV) assay is the most popular method for biofilm determination adopted by different laboratories so far. However, biofilm layer formed at the liquid-air interphase known as pellicle is extremely sensitive to its washing...... and staining steps. Early phase biofilms are also prone to damage by the latter steps. In bacteria like mycobacteria, biofilm formation occurs largely at the liquid-air interphase which is susceptible to loss. In the proposed protocol, loss of such biofilm layer was prevented. In place of inverting...... and discarding the media which can lead to the loss of the aerobic biofilm layer in CV assay, media was removed from the formed biofilm with the help of a syringe and biofilm layer was allowed to dry. The staining and washing steps were avoided, and an organic solvent-tetrahydrofuran (THF) was deployed...

  15. Initial transport and retention behaviors of ZnO nanoparticles in quartz sand porous media coated with Escherichia coli biofilm

    International Nuclear Information System (INIS)

    Jiang, Xujia; Wang, Xueting; Tong, Meiping; Kim, Hyunjung

    2013-01-01

    The significance of biofilm on the transport and deposition behaviors of ZnO nanoparticles were examined under a series of environmentally relevant ionic strength at two fluid velocities of 4 m-d −1 and 8 m-d −1 . Biofilm enhanced nanoparticles retention in porous media under all examined conditions. The greater deposition was also observed in extracellular polymeric substances (EPS) coated surfaces by employment of quartz microbalance with dissipation (QCM-D) system. Derjaguin–Landau–Verwey–Overbeek (DLVO) failed to interpret more ZnO nanoparticles deposition on biofilm (EPS) coated silica surfaces. Chemical interaction and physical morphology of biofilm contributed to this greater deposition (retention). Biofilm affected the spacial distribution of retained ZnO nanoparticles as well. Relatively steeper slope of retained profiles were observed in the presence of biofilm, corresponding to the greater deviation from colloid filtration theory (CFT). Pore space constriction via biofilm induced more nanoparticle trapped in the column inlet, leading to greater deviations (σln k f ) from the CFT. Highlights: ► Biofilm reduced the mobility of ZnO nanoparticles in column. ► DLVO and non-DLVO interactions contributed the more nanoparticles deposition. ► Biofilm also affected the spacial distribution of ZnO nanoparticles in column. ► Greater deviation from classic filtration theory was observed with biofilm. ► Physical structure of biofilm induced greater deviation from log-linear prediction. -- Biofilm enhanced ZnO nanoparticle deposition and altered spacial distribution in porous media

  16. Isolate-specific effects of patulin, penicillic Acid and EDTA on biofilm formation and growth of dental unit water line biofilm isolates.

    Science.gov (United States)

    Liaqat, Iram; Bachmann, Robert Thomas; Sabri, Anjum Nasim; Edyvean, Robert G J

    2010-08-01

    Dental unit water line (DUWL) contamination by opportunistic pathogens has its significance in nosocomial infection of patients, health care workers, and life-threatening infections to immunocompromized persons. Recently, the quorum sensing (QS) system of DUWL isolates has been found to affect their biofilm-forming ability, making it an attractive target for antimicrobial therapy. In this study, the effect of two quorum-sensing inhibitory compounds (patulin; PAT, penicillic acid; PA) and EDTA on planktonic growth, AI-2 signalling and in vitro biofilm formation of Pseudomonas aeruginosa, Achromobacter xylosoxidans and Achromobacter sp. was monitored. Vibrio harveyi BB170 bioassay and crystal violet staining methods were used to detect the AI-2 monitoring and biofilm formation in DUWL isolates, respectively. The V. harveyi BB170 bioassay failed to induce bioluminescence in A. xylosoxidans and Achromobacter sp., while P. aeruginosa showed AI-2 like activity suggesting the need of some pretreatments prior to bioassay. All strains were found to form biofilms within 72 h of incubation. The QSIs/EDTA combination have isolate-specific effects on biofilm formation and in some cases it stimulated biofilm formation as often as it was inhibited. However, detailed information about the anti-biofilm effect of these compounds is still lacking.

  17. Hydrodynamic dispersion within porous biofilms

    KAUST Repository

    Davit, Y.; Byrne, H.; Osborne, J.; Pitt-Francis, J.; Gavaghan, D.; Quintard, M.

    2013-01-01

    Many microorganisms live within surface-associated consortia, termed biofilms, that can form intricate porous structures interspersed with a network of fluid channels. In such systems, transport phenomena, including flow and advection, regulate

  18. Bacterial biofilms and antibiotic resistance

    Directory of Open Access Journals (Sweden)

    Liliana Caldas-Arias

    2015-04-01

    Full Text Available Biofilms give to bacteria micro-environmental benefits; confers protection against antimicrobials. Bacteria have antibiotic resistance by conventional and unusual mechanisms leading to delayed wound healing, to increase recurrent chronic infections and nosocomial contamination of medical devices. Objective: This narrative review aims to introduce the characteristics of Bacteria-biofilms, antimicrobial resistance mechanisms and potential alternatives for prevention and control of its formation. Methods: Search strategy was performed on records: PubMed / Medline, Lilacs, Redalyc; with suppliers such as EBSCO and thesaurus MeSH and DeCS. Conclusions: Knowledge and research performance of biofilm bacteria are relevant in the search of technology for detection and measuring sensitivity to antibiotics. The identification of Bacterial-biofilms needs no-traditional microbiological diagnosis.

  19. Exploiting social evolution in biofilms

    DEFF Research Database (Denmark)

    Boyle, Kerry E; Heilmann, Silja; van Ditmarsch, Dave

    2013-01-01

    Bacteria are highly social organisms that communicate via signaling molecules, move collectively over surfaces and make biofilm communities. Nonetheless, our main line of defense against pathogenic bacteria consists of antibiotics-drugs that target individual-level traits of bacterial cells...... and thus, regrettably, select for resistance against their own action. A possible solution lies in targeting the mechanisms by which bacteria interact with each other within biofilms. The emerging field of microbial social evolution combines molecular microbiology with evolutionary theory to dissect...... the molecular mechanisms and the evolutionary pressures underpinning bacterial sociality. This exciting new research can ultimately lead to new therapies against biofilm infections that exploit evolutionary cheating or the trade-off between biofilm formation and dispersal....

  20. Biofilms: Community Behavior by Bacteria

    Indian Academy of Sciences (India)

    IAS Admin

    United we stand, divided we fall. This is a ... controls biofilm development, swarming motility and the produc- ... thought that the absence of overt gut flora upsets the balance .... there are several risks of integration which makes this strategy.

  1. Compaction and relaxation of biofilms

    KAUST Repository

    Valladares Linares, R.; Wexler, A. D.; Bucs, Szilard; Dreszer, C.; Zwijnenburg, A.; Flemming, H. C.; Kruithof, J. C.; Vrouwenvelder, Johannes S.

    2015-01-01

    Operation of membrane systems for water treatment can be seriously hampered by biofouling. A better characterization of biofilms in membrane systems and their impact on membrane performance may help to develop effective biofouling control strategies

  2. Exogenous and endogenous landforms in the Mediterranean

    Science.gov (United States)

    Acar, Julia

    2017-04-01

    11th graders have already learned about endogenous forces and now we are having a closer look at the exogenous forces which act on the Earth's surface. The Po River-system, for example, is responsible for the formation of the alpine region. Students are asked to find out how this works with the help of the rock-cycle scheme, several suitable maps and information on weathering and the texture of rocks, erosion, etc. We will form groups that will look at different types of rock formations (including an example in the Mediterranean region each). Depending on the number of lessons available we will add the exogenous effect of flowing water and ice (glacial over forming) to the topic. At the end every group will present their findings explaining the scientific context by using topographic examples.

  3. Biofilm in endodontics: a review

    OpenAIRE

    Zambrano de la Peña, Sonia; Salcedo-Moncada, Doris; Petkova- Gueorguieva, Marieta; Ventocilla Huasupoma, María

    2017-01-01

    It is demonstrated the efforts made endodontic microbiology and science to get to decipher the secrets of this unique structure although every day new questions arise. We need the treatments we use to combat biofilm achieve oxygenate the periapical ecosystem and basically scrape and loosen the tightly adhering bacteria Knowing the process of biofilm formation, microbial metabolism and strategies that they use to resist and remain hidden but active , we know why we observe refractory periapica...

  4. Critical review on biofilm methods

    DEFF Research Database (Denmark)

    Azeredo, Joana; F. Azevedo, Nuno; Briandet, Romain

    2017-01-01

    Biofilms are widespread in nature and constitute an important strategy implemented by microorganisms to survive in sometimes harsh environmental conditions. They can be beneficial or have a negative impact particularly when formed in industrial settings or on medical devices. As such, research in...... and limitations of several methods. Accordingly, this review aims at helping scientists in finding the most appropriate and up-to-date methods to study their biofilms....

  5. Exogenous Testosterone Enhances the Reactivity to Social Provocation in Males

    Directory of Open Access Journals (Sweden)

    Lisa Wagels

    2018-03-01

    Full Text Available Testosterone affects human social behavior in various ways. While testosterone effects are generally associated with muscular strength and aggressiveness, human studies also point towards enhanced status–seeking motives after testosterone administration. The current study tested the causal influence of exogenous testosterone on male behavior during a competitive provocation paradigm. In this double blind, randomized, placebo (PL-controlled study, 103 males were assigned to a PL or testosterone group receiving a colorless PL or testosterone gel. To induce provocation, males played a rigged reaction time game against an ostensible opponent. When participants lost, the opponent subtracted money from the participant who in return could subtract money from the ostensible opponent. Participants subjectively indicated anger and self-estimated treatment affiliation (testosterone or PL administration. A trial-by-trial analysis demonstrated that provocation and success during the repeated games had a stronger influence on participants’ choice to reduce money from the opponent if they had received testosterone. Participants who believed to be in the testosterone group were angrier after the experiment and increased monetary reductions during the task course. In line with theories about mechanisms of testosterone in humans, provocation is shown to be necessary for the agency of exogenous testosterone. Thus, testosterone reinforces the conditional adjustment of aggressive behavior but not aggressive behavior per se. In contrast undirected frustration is not increased by testosterone but probably interferes with cognitive appraisals about biological mechanisms of testosterone.

  6. Exogenous Testosterone Enhances the Reactivity to Social Provocation in Males.

    Science.gov (United States)

    Wagels, Lisa; Votinov, Mikhail; Kellermann, Thilo; Eisert, Albrecht; Beyer, Cordian; Habel, Ute

    2018-01-01

    Testosterone affects human social behavior in various ways. While testosterone effects are generally associated with muscular strength and aggressiveness, human studies also point towards enhanced status-seeking motives after testosterone administration. The current study tested the causal influence of exogenous testosterone on male behavior during a competitive provocation paradigm. In this double blind, randomized, placebo (PL)-controlled study, 103 males were assigned to a PL or testosterone group receiving a colorless PL or testosterone gel. To induce provocation, males played a rigged reaction time game against an ostensible opponent. When participants lost, the opponent subtracted money from the participant who in return could subtract money from the ostensible opponent. Participants subjectively indicated anger and self-estimated treatment affiliation (testosterone or PL administration). A trial-by-trial analysis demonstrated that provocation and success during the repeated games had a stronger influence on participants' choice to reduce money from the opponent if they had received testosterone. Participants who believed to be in the testosterone group were angrier after the experiment and increased monetary reductions during the task course. In line with theories about mechanisms of testosterone in humans, provocation is shown to be necessary for the agency of exogenous testosterone. Thus, testosterone reinforces the conditional adjustment of aggressive behavior but not aggressive behavior per se . In contrast undirected frustration is not increased by testosterone but probably interferes with cognitive appraisals about biological mechanisms of testosterone.

  7. Exogenous shocks and governing energy security

    OpenAIRE

    Diriöz, Ali Oğuz

    2017-01-01

    Cataloged from PDF version of article. Thesis (Ph.D.): Bilkent University, Department of International Relations, İhsan Doğramacı Bilkent University, 2017. Includes bibliographical references (leaves 219-248). The research examines how governments maintain energy security when faced with exogenous shocks. The main focus of inquiry examines the relative influence of markets vs. geopolitics in the area of energy security using the comparative case studies of Turkey, France, and Netherl...

  8. Exogenous sample contamination. Sources and interference.

    Science.gov (United States)

    Cornes, Michael P

    2016-12-01

    Clinical laboratory medicine is involved in the vast majority of patient care pathways. It has been estimated that pathology results inform 60-70% of critical patient care decisions. The primary goal of the laboratory is to produce precise and accurate results which reflect the true situation in vivo. It is not surprising that interference occurs in laboratory analysis given the complexity of some of the assays used to perform them. Interference is defined as "the effect of a substance upon any step in the determination of the concentration or catalytic activity of the metabolite". Exogenous interferences are defined as those that derive from outside of the body and are therefore not normally found in a specimen and can cause either a positive or negative bias in analytical results. Interferences in analysis can come from various sources and can be classified as endogenous or exogenous. Exogenous substances could be introduced at any point in the sample journey. The laboratory must take responsibility for the quality of results produced. It has a responsibility to have processes in place to identify and minimise the occurrence and effect contamination and interference. To do this well the laboratory needs to work with clinicians and manufacturers. Failure to identify an erroneous result could have an impact on patient care, patient safety and also on hospital budgets. However it is not always easy to recognise interferences. This review summarises the types and sources of exogenous interference and some steps to minimise the impact they have. Crown Copyright © 2016. Published by Elsevier Inc. All rights reserved.

  9. Short communication: Effects of lactose and milk on the expression of biofilm-associated genes in Staphylococcus aureus strains isolated from a dairy cow with mastitis.

    Science.gov (United States)

    Xue, Ting; Chen, Xiaolin; Shang, Fei

    2014-10-01

    Staphylococcus aureus is the main etiological organism responsible for bovine mastitis. The ability of S. aureus to form biofilms plays an important role in the pathogenesis of mastitis. Biofilm formation in S. aureus is associated with the production of polysaccharide intercellular adhesin (PIA) protein and several other proteins. Several environmental factors, including glucose, osmolarity, oleic acid, temperature, and anaerobiosis, have been reported to affect biofilm formation in S. aureus. This study investigated the influence of lactose and milk on the biofilm formation capacity of 2 clinical bovine isolates of S. aureus. We found that lactose increased biofilm formation predominantly by inducing PIA production, whereas milk increased biofilm formation through PIA as well as by increasing the production of other biofilm-associated proteins, which might be mediated by the transcriptional regulators intercellular adhesion regulator (icaR) and repressor of biofilm (rbf). Copyright © 2014 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  10. Plasticity of Candida albicans Biofilms

    Science.gov (United States)

    Daniels, Karla J.

    2016-01-01

    SUMMARY Candida albicans, the most pervasive fungal pathogen that colonizes humans, forms biofilms that are architecturally complex. They consist of a basal yeast cell polylayer and an upper region of hyphae encapsulated in extracellular matrix. However, biofilms formed in vitro vary as a result of the different conditions employed in models, the methods used to assess biofilm formation, strain differences, and, in a most dramatic fashion, the configuration of the mating type locus (MTL). Therefore, integrating data from different studies can lead to problems of interpretation if such variability is not taken into account. Here we review the conditions and factors that cause biofilm variation, with the goal of engendering awareness that more attention must be paid to the strains employed, the methods used to assess biofilm development, every aspect of the model employed, and the configuration of the MTL locus. We end by posing a set of questions that may be asked in comparing the results of different studies and developing protocols for new ones. This review should engender the notion that not all biofilms are created equal. PMID:27250770

  11. The cellular receptors of exogenous RNA

    Directory of Open Access Journals (Sweden)

    Patryk Reniewicz

    2016-04-01

    Full Text Available One of the key determinants of survival for organisms is proper recognition of exogenous and endogenous nucleic acids. Therefore, high eukaryotes developed a number of receptors that allow for discrimination between friend or foe DNA and RNA. Appearance of exogenous RNA in cytoplasm provides a signal of danger and triggers cellular responses that facilitate eradication of a pathogen. Recognition of exogenous RNA is additionally complicated by fact that large amount of endogenous RNA is present in cytoplasm Thus, number of different receptors, found in eukaryotic cells, is able to recognize that nucleic acid. First group of those receptors consist endosomal Toll like receptors, namely TLR3, TLR7, TLR8 and TLR13. Those receptors recognize RNA released from pathogens that enter the cell by endocytosis. The second group includes cytoplasmic sensors like PKR and the family of RLRs comprised of RIG-I, MDA5 and LGP2. Cytoplasmic receptors recognize RNA from pathogens invading the cell by non-endocytic pathway. In both cases binding of RNA by its receptors results in activation of the signalling cascades that lead to the production of interferon and other cytokines.

  12. Enhancement of photodynamic inactivation of Staphylococcus aureus biofilms by disruptive strategies.

    Science.gov (United States)

    Gándara, Lautaro; Mamone, Leandro; Bohm, Gabriela Cervini; Buzzola, Fernanda; Casas, Adriana

    2017-11-01

    Photodynamic inactivation (PDI) has been used to inactivate microorganisms through the use of photosensitizers and visible light. On the one hand, near-infrared treatment (NIRT) has also bactericidal and dispersal effects on biofilms. In addition, dispersal biological tools such as enzymes have also been employed in antibiotic combination treatments. The aim of this work was to use alternative approaches to increase the PDI efficacy, employing combination therapies aimed at the partial disruption of the biofilms, thus potentially increasing photosensitizer or oxygen penetration and interaction with bacteria. To that end, we applied toluidine blue (TB)-PDI treatment to Staphylococcus aureus biofilms previously treated with NIRT or enzymes and investigated the outcome of the combined therapies. TB employed at 0.5 mM induced per se 2-log drop in S. aureus RN6390 biofilm viability. Each NIRT (980-nm laser) and PDI (635-nm laser) treatment induced a further reduction of 1-log of viable counts. The combination of successive 980- and 635-nm laser treatments on TB-treated biofilms induced additive effects, leading to a 4.5-log viable count decrease. Proteinase K treatment applied to S. aureus of the Newman strain induced an additive effect on PDI mortality, leading to an overall 4-log decrease in S. aureus viability. Confocal scanning laser microscopy after biofilm staining with a fluorescent viability test and scanning electron microscopy observations were correlated with colony counts. The NIRT dose employed (227 J/cm 2 ) led to an increase from 21 to 47 °C in the buffer temperature of the biofilm system, and this NIRT dose also induced 100% keratinocyte death. Further work is needed to establish conditions under which biofilm dispersal occurs at lower NIRT doses.

  13. Discrepancy of neural response between exogenous and endogenous task switching: an event-related potentials study.

    Science.gov (United States)

    Miyajima, Maki; Toyomaki, Atsuhito; Hashimoto, Naoki; Kusumi, Ichiro; Murohashi, Harumitsu; Koyama, Tsukasa

    2012-08-01

    Task switching is a well-known cognitive paradigm to explore task-set reconfiguration processes such as rule shifting. In particular, endogenous task switching is thought to differ qualitatively from stimulus-triggered exogenous task switching. However, no previous study has examined the neural substrate of endogenous task switching. The purpose of the present study is to explore the differences between event-related potential responses to exogenous and endogenous rule switching at cue stimulus. We modified two patterns of cued switching tasks: exogenous (bottom-up) rule switching and endogenous (top-down) rule switching. In each task cue stimulus was configured to induce switching or maintaining rule. In exogenous switching tasks, late positive deflection was larger in the switch rule condition than in the maintain rule condition. However, in endogenous switching tasks late positive deflection was unexpectedly larger in the maintain-rule condition than in the switch-rule condition. These results indicate that exogenous rule switching is explicit stimulus-driven processes, whereas endogenous rule switching is implicitly parallel processes independent of external stimulus.

  14. [Effects of exogenous spermidine on Cucumis sativus L. seedlings photosynthesis under root zone hypoxia stress].

    Science.gov (United States)

    Wang, Tian; Wang, Suping; Guo, Shirong; Sun, Yanjun

    2006-09-01

    With water culture, this paper studied the effects of exogenous spermidine (Spd) on the net photosynthetic rate (Pn), intercellular CO2 concentrations (Ci), stomatal conductance (Gs), transpiration rate (Tr), apparent quantum yield (phi c), and carboxylation efficiency (CE) of cucumber seedlings tinder hypoxia stress. The results showed that the Pn decreased gradually under hypoxia stress, and reached the minimum 10 days after by 63. 33% of the control. Compared with that of hypoxia-stressed plants, the Pn after 10 days application of exogenous Spd increased 1.25 times. A negative correlation (R2 = 0.4730 - 0.7118) was found between Pn and Ci. Gs and Tr changed in wider ranges, which decreased under hypoxia-stress, but increased under hypoxia-stress plus exogenous Spd application. There was a significant positive correlation between Gs and Tr (R2 = 0.7821 - 0.9458), but these two parameters had no significant correlation with Pn; Hypoxia stress induced a decrease of phi c and CE by 63.01% and 72.33%, respectively, while hypoxia stress plus exogenous Spd application made phi c and CE increase by 23% and 14%, respectively. The photo-inhibition of cucumber seedlings under hypoxia stress was mainly caused by non-stomatal limitation, while exogenous Spd alleviated the hypoxia stress by repairing photosynthesis system.

  15. A new route of bioaugmentation by allochthonous and autochthonous through biofilm bacteria for soluble chemical oxygen demand removal of old leachate.

    Science.gov (United States)

    Alijani Ardeshir, Rashid; Rastgar, Sara; Peyravi, Majid; Jahanshahi, Mohsen; Shokuhi Rad, Ali

    2017-10-01

    Landfill leachate contains environmental pollutants that are generally resistant to biodegradation. In this study, indigenous and exogenous bacteria in leachate were acclimated in both biofilm and suspension forms to increase the removal of soluble chemical oxygen demand (SCOD). The bacteria from the leachate and sewage were acclimated to gradually increasing leachate concentration prepared using a reverse osmosis membrane over 28 days. The SCOD removal was measured aerobically or nominally anaerobically. Biofilms were prepared using different carrier media (glass, rubber, and plastic). The maximum SCOD removal in suspensions was 32% (anaerobic) and in biofilms was 39% (aerobic). In the suspension form, SCOD removal using acclimated bacteria from leachate and sewage anaerobically increased in comparison with the control (P technology using biofilms and acclimations can be an effective, inexpensive, and simple way to decrease SCOD in old landfill leachate.

  16. Thiopeptide antibiotics stimulate biofilm formation in Bacillus subtilis.

    Science.gov (United States)

    Bleich, Rachel; Watrous, Jeramie D; Dorrestein, Pieter C; Bowers, Albert A; Shank, Elizabeth A

    2015-03-10

    Bacteria have evolved the ability to produce a wide range of structurally complex natural products historically called "secondary" metabolites. Although some of these compounds have been identified as bacterial communication cues, more frequently natural products are scrutinized for antibiotic activities that are relevant to human health. However, there has been little regard for how these compounds might otherwise impact the physiology of neighboring microbes present in complex communities. Bacillus cereus secretes molecules that activate expression of biofilm genes in Bacillus subtilis. Here, we use imaging mass spectrometry to identify the thiocillins, a group of thiazolyl peptide antibiotics, as biofilm matrix-inducing compounds produced by B. cereus. We found that thiocillin increased the population of matrix-producing B. subtilis cells and that this activity could be abolished by multiple structural alterations. Importantly, a mutation that eliminated thiocillin's antibiotic activity did not affect its ability to induce biofilm gene expression in B. subtilis. We go on to show that biofilm induction appears to be a general phenomenon of multiple structurally diverse thiazolyl peptides and use this activity to confirm the presence of thiazolyl peptide gene clusters in other bacterial species. Our results indicate that the roles of secondary metabolites initially identified as antibiotics may have more complex effects--acting not only as killing agents, but also as specific modulators of microbial cellular phenotypes.

  17. Short and long term biosorption of silica-coated iron oxide nanoparticles in heterotrophic biofilms

    International Nuclear Information System (INIS)

    Herrling, Maria P.; Lackner, Susanne; Tatti, Oleg; Guthausen, Gisela; Delay, Markus; Franzreb, Matthias; Horn, Harald

    2016-01-01

    The increased application of engineered nanoparticles (ENP) in industrial processes and consumer products has raised concerns about their impact on health and environmental safety. When ENP enter the global water cycle by e.g. wastewater streams, wastewater treatment plants (WWTP) represent potential sinks for ENP. During biological WWT, the attachment of ENP to biofilms is responsible for the desired removal of ENP from the water phase avoiding their release into the aquatic environment. However, the fundamental mechanisms guiding the interactions between ENP and biofilms are not yet fully understood. Therefore, this study investigates the behavior and biosorption of inorganic ENP, here magnetic iron oxide nanoparticles coated with silica (scFe_3O_4-NP), with heterotrophic biofilms at different time scales. Their magnetic properties enable to follow scFe_3O_4-NP in the biofilm system by a magnetic susceptibility balance and magnetic resonance imaging. Biofilms were exposed to scFe_3O_4-NP at short contact times (5 min) in flow cells and complementary, scFe_3O_4-NP were introduced into a moving bed biofilm reactor (MBBR) to be observed for 27 d. Mass balances revealed that scFe_3O_4-NP sorbed to the biofilm within a few minutes, but that the total biosorption was rather low (3.2 μg Fe/mg TSS). scFe_3O_4-NP mainly sorbed to the biofilm surface inducing the detachment of outer biofilm parts starting after an exposure time of 3 h in the MBBR. The biosorption depended on the exposure concentration of scFe_3O_4-NP, but less on the contact time. Most scFe_3O_4-NP exited the flow cell (up to 65%) and the MBBR (57%) via the effluent. This effect was favored by the stabilization of scFe_3O_4-NP in the bulk liquid by organic matter leading to a low retention capacity of the MBBR system. The results contribute to improve our understanding about the fate of ENP in environmental and in technical biofilm systems and give indications for future investigations needed

  18. Metabolic activity of Streptococcus mutans biofilms and gene expression during exposure to xylitol and sucrose.

    Science.gov (United States)

    Decker, Eva-Maria; Klein, Christian; Schwindt, Dimitri; von Ohle, Christiane

    2014-12-01

    The objective of the study was to analyse Streptococcus mutans biofilms grown under different dietary conditions by using multifaceted methodological approaches to gain deeper insight into the cariogenic impact of carbohydrates. S. mutans biofilms were generated during a period of 24 h in the following media: Schaedler broth as a control medium containing endogenous glucose, Schaedler broth with an additional 5% sucrose, and Schaedler broth supplemented with 1% xylitol. The confocal laser scanning microscopy (CLSM)-based analyses of the microbial vitality, respiratory activity (5-cyano-2,3-ditolyl tetrazolium chloride, CTC) and production of extracellular polysaccharides (EPS) were performed separately in the inner, middle and outer biofilm layers. In addition to the microbiological sample testing, the glucose/sucrose consumption of the biofilm bacteria was quantified, and the expression of glucosyltransferases and other biofilm-associated genes was investigated. Xylitol exposure did not inhibit the viability of S. mutans biofilms, as monitored by the following experimental parameters: culture growth, vitality, CTC activity and EPS production. However, xylitol exposure caused a difference in gene expression compared to the control. GtfC was upregulated only in the presence of xylitol. Under xylitol exposure, gtfB was upregulated by a factor of 6, while under sucrose exposure, it was upregulated by a factor of three. Compared with glucose and xylitol, sucrose increased cell vitality in all biofilm layers. In all nutrient media, the intrinsic glucose was almost completely consumed by the cells of the S. mutans biofilm within 24 h. After 24 h of biofilm formation, the multiparametric measurements showed that xylitol in the presence of glucose caused predominantly genotypic differences but did not induce metabolic differences compared to the control. Thus, the availability of dietary carbohydrates in either a pure or combined form seems to affect the

  19. Metabolic activity of Streptococcus mutans biofilms and gene expression during exposure to xylitol and sucrose

    Institute of Scientific and Technical Information of China (English)

    Eva-Maria Decker; Christian Klein; Dimitri Schwindt; Christiane von Ohle

    2014-01-01

    The objective of the study was to analyse Streptococcus mutans biofilms grown under different dietary conditions by using multifaceted methodological approaches to gain deeper insight into the cariogenic impact of carbohydrates. S. mutans biofilms were generated during a period of 24 h in the following media:Schaedler broth as a control medium containing endogenous glucose, Schaedler broth with an additional 5%sucrose, and Schaedler broth supplemented with 1%xylitol. The confocal laser scanning microscopy (CLSM)-based analyses of the microbial vitality, respiratory activity (5-cyano-2,3-ditolyl tetrazolium chloride, CTC) and production of extracellular polysaccharides (EPS) were performed separately in the inner, middle and outer biofilm layers. In addition to the microbiological sample testing, the glucose/sucrose consumption of the biofilm bacteria was quantified, and the expression of glucosyltransferases and other biofilm-associated genes was investigated. Xylitol exposure did not inhibit the viability of S. mutans biofilms, as monitored by the following experimental parameters:culture growth, vitality, CTC activity and EPS production. However, xylitol exposure caused a difference in gene expression compared to the control. GtfC was upregulated only in the presence of xylitol. Under xylitol exposure, gtfB was upregulated by a factor of 6, while under sucrose exposure, it was upregulated by a factor of three. Compared with glucose and xylitol, sucrose increased cell vitality in all biofilm layers. In all nutrient media, the intrinsic glucose was almost completely consumed by the cells of the S. mutans biofilm within 24 h. After 24 h of biofilm formation, the multiparametric measurements showed that xylitol in the presence of glucose caused predominantly genotypic differences but did not induce metabolic differences compared to the control. Thus, the availability of dietary carbohydrates in either a pure or combined form seems to affect the cariogenic potential

  20. Synergy of brushing mode and antibacterial use on in vivo biofilm formation.

    Science.gov (United States)

    Jongsma, Marije A; van de Lagemaat, Marieke; Busscher, Henk J; Geertsema-Doornbusch, Gesinda I; Atema-Smit, Jelly; van der Mei, Henny C; Ren, Yijin

    2015-12-01

    Orthodontic, multi-strand retention-wires are used as a generalized model for oral retention sites to investigate whether biofilm left-behind after powered toothbrushing in-vivo enabled better penetration of antibacterials as compared with manual brushing. 2-cm multi-strand, stainless-steel retention-wires were placed in brackets bonded bilaterally in the upper arches of 10-volunteers. Volunteers used NaF-sodium-lauryl-sulphate-containing toothpaste and antibacterial, triclosan-containing toothpaste supplemented or not with an essential-oils containing mouthrinse. Opposite sides of the dentition including the retention-wires, were brushed manually or with a powered toothbrush. Health-care-regimens were maintained for 1-week, after which wires were removed and oral biofilm was collected. When powered toothbrushing was applied, slightly less bacteria were collected than after manual brushing, regardless whether an antibacterial-regimen was used or not. Powered-toothbrushing combined with antibacterial-regimens yielded lower biofilm viability than manual brushing, indicating better antibacterial penetration into biofilm left-behind after powered brushing. Major shifts in biofilm composition, with a decrease in prevalence of both cariogenic species and periodontopathogens, were induced after powered brushing using an antibacterial-regimen. Oral biofilm left-behind after powered brushing in-vivo enabled better penetration of antibacterials than after manual brushing. Mechanical removal of oral biofilm is important for prevention of dental pathologies, but biofilm is always left-behind, such as in fissures, buccal pits, interproximal areas and gingival margins and around orthodontic appliances. Use of antibacterial toothpastes or mouthrinses can contribute to removal or killing of biofilm bacteria, but biofilm structure hampers antibacterial penetration. A synergy between brushing mode and antibacterial-regimen applied exists with clinically demonstrable effects

  1. Assessment and characterization of biofilm formation among human isolates of Streptococcus dysgalactiae subsp. equisimilis.

    Science.gov (United States)

    Genteluci, Gabrielle Limeira; Silva, Ligia Guedes; Souza, Maria Clara; Glatthardt, Thaís; de Mattos, Marcos Corrêa; Ejzemberg, Regina; Alviano, Celuta Sales; Figueiredo, Agnes Marie Sá; Ferreira-Carvalho, Bernadete Teixeira

    2015-12-01

    The capacity to form biofilm is considered a protective mechanism that allows the bacteria to survive and proliferate in hostile environments, facilitating the maintenance of the infectious process. Recently, biofilm has become a topic of interest in the study of the human pathogen group A Streptococcus (GAS). Although GAS has not been associated with infection on medical implants, the presence of microcolonies embedded in an extracellular matrix on infected tissues has been reported. Despite the similarity between GAS and Streptococcus dysgalactiae subspecies equisimilis (SDSE), there are no studies in the literature describing the production of biofilm by SDSE. In this work, we assessed and characterized biofilm development among SDSE human isolates of group C. The in vitro data showed that 59.3% of the 118 isolates tested were able to form acid-induced biofilm on glass, and 28% formed it on polystyrene surfaces. More importantly, biofilm was also formed in a foreign body model in mice. The biofilm structure was analyzed by confocal laser scanning microscopy, transmission electron microscopy, and scanning electron microscopy. Long fibrillar-like structures were observed by scanning electron microscopy. Additionally, the expression of a pilus associated gene of SDSE was increased for in vitro sessile cells compared with planktonics, and when sessile cells were collected from biofilms formed in the animal model compared with that of in vitro model. Results obtained from the immunofluorescence microscopy indicated the biofilm was immunogenic. Our data also suggested a role for proteins, exopolysaccharide and extracellular DNA in the formation and accumulation of biofilm by SDSE. Copyright © 2015 Elsevier GmbH. All rights reserved.

  2. SarA is a negative regulator of Staphylococcus epidermidis biofilm formation

    DEFF Research Database (Denmark)

    Martin, Christer; Heinze, C.; Busch, M.

    2012-01-01

    Biofilm formation is essential for Staphylococcus epidermidis pathogenicity in implant-associated infections. Nonetheless, large proportions of invasive S. epidermidis isolates fail to show accumulative biofilm growth in vitro. We here tested the hypothesis that this apparent paradox is related...... virulence. Genetic analysis revealed that inactivation of sarA induced biofilm formation via over-expression of the giant 1 MDa extracellular matrix binding protein (Embp), serving as an intercellular adhesin. In addition to Embp, increased extracellular DNA (eDNA) release significantly contributed...... to biofilm formation in mutant 1585ΔsarA. Increased eDNA amounts indirectly resulted from up-regulation of metalloprotease SepA, leading to boosted processing of major autolysin AtlE, in turn inducing augmented autolysis and release of chromosomal DNA. Hence, this study identifies sarA as a negative...

  3. Streptococcus mutans Protein Synthesis during Mixed-Species Biofilm Development by High-Throughput Quantitative Proteomics

    Science.gov (United States)

    Klein, Marlise I.; Xiao, Jin; Lu, Bingwen; Delahunty, Claire M.; Yates, John R.; Koo, Hyun

    2012-01-01

    Biofilms formed on tooth surfaces are comprised of mixed microbiota enmeshed in an extracellular matrix. Oral biofilms are constantly exposed to environmental changes, which influence the microbial composition, matrix formation and expression of virulence. Streptococcus mutans and sucrose are key modulators associated with the evolution of virulent-cariogenic biofilms. In this study, we used a high-throughput quantitative proteomics approach to examine how S. mutans produces relevant proteins that facilitate its establishment and optimal survival during mixed-species biofilms development induced by sucrose. Biofilms of S. mutans, alone or mixed with Actinomyces naeslundii and Streptococcus oralis, were initially formed onto saliva-coated hydroxyapatite surface under carbohydrate-limiting condition. Sucrose (1%, w/v) was then introduced to cause environmental changes, and to induce biofilm accumulation. Multidimensional protein identification technology (MudPIT) approach detected up to 60% of proteins encoded by S. mutans within biofilms. Specific proteins associated with exopolysaccharide matrix assembly, metabolic and stress adaptation processes were highly abundant as the biofilm transit from earlier to later developmental stages following sucrose introduction. Our results indicate that S. mutans within a mixed-species biofilm community increases the expression of specific genes associated with glucan synthesis and remodeling (gtfBC, dexA) and glucan-binding (gbpB) during this transition (Pmutans up-regulates specific adaptation mechanisms to cope with acidic environments (F1F0-ATPase system, fatty acid biosynthesis, branched chain amino acids metabolism), and molecular chaperones (GroEL). Interestingly, the protein levels and gene expression are in general augmented when S. mutans form mixed-species biofilms (vs. single-species biofilms) demonstrating fundamental differences in the matrix assembly, survival and biofilm maintenance in the presence of other

  4. Multiple pathways for SOS-induced mutagenesis in Escherichia coli: An overexpression of dinB/dinP results in strongly enhancing mutagenesis in the absence of any exogenous treatment to damage DNA

    Science.gov (United States)

    Kim, Su-Ryang; Maenhaut-Michel, Geneviéve; Yamada, Masami; Yamamoto, Yoshihiro; Matsui, Keiko; Sofuni, Toshio; Nohmi, Takehiko; Ohmori, Haruo

    1997-01-01

    dinP is an Escherichia coli gene recently identified at 5.5 min of the genetic map, whose product shows a similarity in amino acid sequence to the E. coli UmuC protein involved in DNA damage-induced mutagenesis. In this paper we show that the gene is identical to dinB, an SOS gene previously localized near the lac locus at 8 min, the function of which was shown to be required for mutagenesis of nonirradiated λ phage infecting UV-preirradiated bacterial cells (termed λUTM for λ untargeted mutagenesis). A newly constructed dinP null mutant exhibited the same defect for λUTM as observed previously with a dinB::Mu mutant, and the defect was complemented by plasmids carrying dinP as the only intact bacterial gene. Furthermore, merely increasing the dinP gene expression, without UV irradiation or any other DNA-damaging treatment, resulted in a strong enhancement of mutagenesis in F′lac plasmids; at most, 800-fold increase in the G6-to-G5 change. The enhanced mutagenesis did not depend on recA, uvrA, or umuDC. Thus, our results establish that E. coli has at least two distinct pathways for SOS-induced mutagenesis: one dependent on umuDC and the other on dinB/P. PMID:9391106

  5. Ciliates as engineers of phototrophic biofilms

    NARCIS (Netherlands)

    Weerman, Ellen J.; van der Geest, Harm G.; van der Meulen, Myra D.; Manders, Erik M. M.; van de Koppel, Johan; Herman, Peter M. J.; Admiraal, Wim

    1. Phototrophic biofilms consist of a matrix of phototrophs, non-photosynthetic bacteria and extracellular polymeric substances (EPS) which is spatially structured. Despite widespread exploitation of algae and bacteria within phototrophic biofilms, for example by protozoans, the 'engineering'

  6. Current understanding of multi-species biofilms

    DEFF Research Database (Denmark)

    Yang, Liang; Liu, Yang; Wu, Hong

    2011-01-01

    every year worldwide to deal with damage to equipment, contaminations of products, energy losses, and infections in human beings resulted from microbial biofilms. Microorganisms compete, cooperate, and communicate with each other in multi-species biofilms. Understanding the mechanisms of multi......Direct observation of a wide range of natural microorganisms has revealed the fact that the majority of microbes persist as surface-attached communities surrounded by matrix materials, called biofilms. Biofilms can be formed by a single bacterial strain. However, most natural biofilms are actually......-species biofilm formation will facilitate the development of methods for combating bacterial biofilms in clinical, environmental, industrial, and agricultural areas. The most recent advances in the understanding of multi-species biofilms are summarized and discussed in the review....

  7. Killing of Serratia marcescens biofilms with chloramphenicol.

    Science.gov (United States)

    Ray, Christopher; Shenoy, Anukul T; Orihuela, Carlos J; González-Juarbe, Norberto

    2017-03-29

    Serratia marcescens is a Gram-negative bacterium with proven resistance to multiple antibiotics and causative of catheter-associated infections. Bacterial colonization of catheters mainly involves the formation of biofilm. The objectives of this study were to explore the susceptibility of S. marcescens biofilms to high doses of common antibiotics and non-antimicrobial agents. Biofilms formed by a clinical isolate of S. marcescens were treated with ceftriaxone, kanamycin, gentamicin, and chloramphenicol at doses corresponding to 10, 100 and 1000 times their planktonic minimum inhibitory concentration. In addition, biofilms were also treated with chemical compounds such as polysorbate-80 and ursolic acid. S. marcescens demonstrated susceptibility to ceftriaxone, kanamycin, gentamicin, and chloramphenicol in its planktonic form, however, only chloramphenicol reduced both biofilm biomass and biofilm viability. Polysorbate-80 and ursolic acid had minimal to no effect on either planktonic and biofilm grown S. marcescens. Our results suggest that supratherapeutic doses of chloramphenicol can be used effectively against established S. marcescens biofilms.

  8. Candida Biofilms: Development, Architecture, and Resistance

    Science.gov (United States)

    CHANDRA, JYOTSNA; MUKHERJEE, PRANAB K.

    2015-01-01

    Intravascular device–related infections are often associated with biofilms (microbial communities encased within a polysaccharide-rich extracellular matrix) formed by pathogens on the surfaces of these devices. Candida species are the most common fungi isolated from catheter-, denture-, and voice prosthesis–associated infections and also are commonly isolated from contact lens–related infections (e.g., fungal keratitis). These biofilms exhibit decreased susceptibility to most antimicrobial agents, which contributes to the persistence of infection. Recent technological advances have facilitated the development of novel approaches to investigate the formation of biofilms and identify specific markers for biofilms. These studies have provided extensive knowledge of the effect of different variables, including growth time, nutrients, and physiological conditions, on biofilm formation, morphology, and architecture. In this article, we will focus on fungal biofilms (mainly Candida biofilms) and provide an update on the development, architecture, and resistance mechanisms of biofilms. PMID:26350306

  9. Printing of Patterned, Engineered E. coli Biofilms with a Low-Cost 3D Printer.

    Science.gov (United States)

    Schmieden, Dominik T; Basalo Vázquez, Samantha J; Sangüesa, Héctor; van der Does, Marit; Idema, Timon; Meyer, Anne S

    2018-05-18

    Biofilms can grow on virtually any surface available, with impacts ranging from endangering the lives of patients to degrading unwanted water contaminants. Biofilm research is challenging due to the high degree of biofilm heterogeneity. A method for the production of standardized, reproducible, and patterned biofilm-inspired materials could be a boon for biofilm research and allow for completely new engineering applications. Here, we present such a method, combining 3D printing with genetic engineering. We prototyped a low-cost 3D printer that prints bioink, a suspension of bacteria in a solution of alginate that solidifies on a calcium-containing substrate. We 3D-printed Escherichia coli in different shapes and in discrete layers, after which the cells survived in the printing matrix for at least 1 week. When printed bacteria were induced to form curli fibers, the major proteinaceous extracellular component of E. coli biofilms, they remained adherent to the printing substrate and stably spatially patterned even after treatment with a matrix-dissolving agent, indicating that a biofilm-mimicking structure had formed. This work is the first demonstration of patterned, biofilm-inspired living materials that are produced by genetic control over curli formation in combination with spatial control by 3D printing. These materials could be used as living, functional materials in applications such as water filtration, metal ion sequestration, or civil engineering, and potentially as standardizable models for certain curli-containing biofilms.

  10. Inhibiting effects of Streptococcus salivarius on competence-stimulating peptide-dependent biofilm formation by Streptococcus mutans.

    Science.gov (United States)

    Tamura, S; Yonezawa, H; Motegi, M; Nakao, R; Yoneda, S; Watanabe, H; Yamazaki, T; Senpuku, H

    2009-04-01

    The effects of Streptococcus salivarius on the competence-stimulating peptide (CSP)-dependent biofilm formation by Streptococcus mutans were investigated. Biofilms were grown on 96-well microtiter plates coated with salivary components in tryptic soy broth without dextrose supplemented with 0.25% sucrose. Biofilm formations were stained using safranin and quantification of stained biofilms was performed by measuring absorbance at 492 nm. S. mutans formed substantial biofilms, whereas biofilms of S. salivarius were formed poorly in the medium conditions used. Furthermore, in combination cultures, S. salivarius strongly inhibited biofilm formation when cultured with S. mutans. This inhibition occurred in the early phase of biofilm formation and was dependent on inactivation of the CSP of S. mutans, which is associated with competence, biofilm formation, and antimicrobial activity of the bacterium, and is induced by expression of the comC gene. Comparisons between the S. mutans clinical strains FSC-3 and FSC-3DeltaglrA in separate dual-species cultures with S. salivarius indicated that the presence of the bacitracin transport ATP-binding protein gene glrA caused susceptibility to inhibition of S. mutans biofilm formation by S. salivarius, and was also associated with the regulation of CSP production by com gene-dependent quorum sensing systems. It is considered that regulation of CSP by glrA in S. mutans and CSP inactivation by S. salivarius are important functions for cell-to-cell communication between biofilm bacteria and oral streptococci such as S. salivarius. Our results provide useful information for understanding the ecosystem of oral streptococcal biofilms, as well as the competition between and coexistence of multiple species in the oral cavity.

  11. Alpha-Toxin Promotes Mucosal Biofilm Formation by Staphylococcus aureus

    Directory of Open Access Journals (Sweden)

    Michele J Anderson

    2012-05-01

    Full Text Available Staphylococcus aureus causes numerous diseases in humans ranging from the mild skin infections to serious, life-threatening, superantigen-mediated Toxic Shock Syndrome (TSS. S. aureus may also be asymptomatically carried in the anterior nares, vagina or on the skin, which serve as reservoirs for infection. Pulsed-field gel electrophoresis clonal type USA200 is the most widely disseminated colonizer and a major cause of TSS. Our prior studies indicated that α-toxin was a major epithelial proinflammatory exotoxin produced by TSS S. aureus USA200 isolates. It also facilitated the penetration of TSS Toxin-1 (TSST-1 across vaginal mucosa. However, the majority of menstrual TSS isolates produce low α-toxin due to a nonsense point mutation at codon 113, designated hly, suggesting mucosal adaptation. The aim of this study was to characterize the differences between TSS USA200 strains [high (hla+ and low (hly+ α-toxin producers] in their abilities to infect and disrupt vaginal mucosal tissue. A mucosal model was developed using ex vivo porcine vaginal mucosa, LIVE/DEAD® staining and confocal microscropy to characterize biofilm formation and tissue viability of TSS USA 200 isolates CDC587 and MN8, which contain the α-toxin pseudogene (hly, MNPE (hla+ and MNPE isogenic hla knockout (hlaKO. All TSS strains grew to similar bacterial densities (1-5 x 108 CFU on the mucosa and were proinflammatory over 3 days. However, MNPE formed biofilms with significant reductions in the mucosal viability whereas neither CDC587, MN8 (hly+, or MNPE hlaKO, formed biofilms and were less cytotoxic. The addition of exogenous, purified α-toxin to MNPE hlaKO restored the biofilm phenotype. Our studies suggest α-toxin affects S. aureus phenotypic growth on vaginal mucosa, by promoting tissue disruption and biofilm formation; and α–toxin mutants (hly are not benign colonizers, but rather form a different type of infection, which we have termed high density pathogenic

  12. Cleaning and Disinfection of Bacillus cereus Biofilm.

    Science.gov (United States)

    Deal, Amanda; Klein, Dan; Lopolito, Paul; Schwarz, John Spencer

    2016-01-01

    Methodology has been evolving for the testing of disinfectants against bacterial single-species biofilms, as the difficulty of biofilm remediation continues to gain much-needed attention. Bacterial single-species biofilm contamination presents a real risk to good manufacturing practice-regulated industries. However, mixed-species biofilms and biofilms containing bacterial spores remain an even greater challenge for cleaning and disinfection. Among spore-forming microorganisms frequently encountered in pharmaceutical manufacturing areas, the spores of Bacillus cereus are often determined to be the hardest to disinfect and eradicate. One of the reasons for the low degree of susceptibility to disinfection is the ability of these spores to be encapsulated within an exopolysachharide biofilm matrix. In this series of experiments, we evaluated the disinfectant susceptibility of B. cereus biofilms relative to disassociated B. cereus spores and biofilm from a non-spore-forming species. Further, we assessed the impact that pre-cleaning has on increasing that susceptibility. Methodology has been evolving for the testing of disinfectants against bacterial single-species biofilms, as the difficulty of biofilm remediation continues to gain much-needed attention. Bacterial single-species biofilm contamination presents a real risk to good manufacturing practice-regulated industries. However, mixed-species biofilms and biofilms containing bacterial spores remain an even greater challenge for cleaning and disinfection. Among spore-forming microorganisms frequently encountered in pharmaceutical manufacturing areas, the spores of Bacillus cereus are often determined to be the hardest to disinfect and eradicate. One of the reasons for the low degree of susceptibility to disinfection is the ability of these spores to be encapsulated within an exopolysachharide biofilm matrix. In this series of experiments, we evaluated the disinfectant susceptibility of B. cereus biofilms relative to

  13. Maggot excretions inhibit biofilm formation on biomaterials.

    Science.gov (United States)

    Cazander, Gwendolyn; van de Veerdonk, Mariëlle C; Vandenbroucke-Grauls, Christina M J E; Schreurs, Marco W J; Jukema, Gerrolt N

    2010-10-01

    Biofilm-associated infections in trauma surgery are difficult to treat with conventional therapies. Therefore, it is important to develop new treatment modalities. Maggots in captured bags, which are permeable for larval excretions/secretions, aid in healing severe, infected wounds, suspect for biofilm formation. Therefore we presumed maggot excretions/secretions would reduce biofilm formation. We studied biofilm formation of Staphylococcus aureus, Staphylococcus epidermidis, Klebsiella oxytoca, Enterococcus faecalis, and Enterobacter cloacae on polyethylene, titanium, and stainless steel. We compared the quantities of biofilm formation between the bacterial species on the various biomaterials and the quantity of biofilm formation after various incubation times. Maggot excretions/secretions were added to existing biofilms to examine their effect. Comb-like models of the biomaterials, made to fit in a 96-well microtiter plate, were incubated with bacterial suspension. The formed biofilms were stained in crystal violet, which was eluted in ethanol. The optical density (at 595 nm) of the eluate was determined to quantify biofilm formation. Maggot excretions/secretions were pipetted in different concentrations to (nonstained) 7-day-old biofilms, incubated 24 hours, and finally measured. The strongest biofilms were formed by S. aureus and S. epidermidis on polyethylene and the weakest on titanium. The highest quantity of biofilm formation was reached within 7 days for both bacteria. The presence of excretions/secretions reduced biofilm formation on all biomaterials. A maximum of 92% of biofilm reduction was measured. Our observations suggest maggot excretions/secretions decrease biofilm formation and could provide a new treatment for biofilm formation on infected biomaterials.

  14. Ocularity Feature Contrast Attracts Attention Exogenously

    Directory of Open Access Journals (Sweden)

    Li Zhaoping

    2018-02-01

    Full Text Available An eye-of-origin singleton, e.g., a bar shown to the left eye among many other bars shown to the right eye, can capture attention and gaze exogenously or reflexively, even when it appears identical to other visual input items in the scene and when the eye-of-origin feature is irrelevant to the observer’s task. Defining saliency as the strength of exogenous attraction to attention, we say that this eye-of-origin singleton, or its visual location, is salient. Defining the ocularity of a visual input item as the relative difference between its left-eye input and its right-eye input, this paper shows the general case that an ocularity singleton is also salient. For example, a binocular input item among monocular input items is salient, so is a left-eye-dominant input item (e.g., a bar with a higher input contrast to the left eye than to the right eye among right-eye-dominant items. Saliency by unique input ocularity is analogous to saliency by unique input colour (e.g., a red item among green ones, as colour is determined by the relative difference(s between visual inputs to different photoreceptor cones. Just as a smaller colour difference between a colour singleton and background items makes this singleton less salient, so does a smaller ocularity difference between an ocularity singleton and background items. While a salient colour difference is highly visible, a salient ocularity difference is often perceptually invisible in some cases and discouraging gaze shifts towards it in other cases, making its behavioural manifestation not as apparent. Saliency by ocularity contrast provides another support to the idea that the primary visual cortex creates a bottom-up saliency map to guide attention exogenously.

  15. Microbiële biofilms in tandheelkunde

    NARCIS (Netherlands)

    Krom, B.P.

    2015-01-01

    Aangehechte gemeenschappen van micro-organismen, ook wel biofilms genoemd, zijn altijd en overal aanwezig. Hoewel biofilms een slechte naam hebben, zijn ze meestal natuurlijk, gezond en zelfs gewenst. In de tandartspraktijk komen zowel gezonde (orale biofilms) als ongezonde (bijv. in de waterleiding

  16. Microbiële biofilms in tandheelkunde

    NARCIS (Netherlands)

    Krom, B.P.

    2015-01-01

    Aangehechte gemeenschappen van micro-organismen, ook wel biofilms genoemd, zijn altijd en overal aanwezig. Hoewel biofilms een slechte naam hebben, zijn ze meestal natuurlijk, gezond en zelfs gewenst. In de mondzorgpraktijk komen zowel gezonde (orale biofilms) als ongezonde (bijv. in de waterleiding

  17. Differential growth of wrinkled biofilms

    Science.gov (United States)

    Espeso, D. R.; Carpio, A.; Einarsson, B.

    2015-02-01

    Biofilms are antibiotic-resistant bacterial aggregates that grow on moist surfaces and can trigger hospital-acquired infections. They provide a classical example in biology where the dynamics of cellular communities may be observed and studied. Gene expression regulates cell division and differentiation, which affect the biofilm architecture. Mechanical and chemical processes shape the resulting structure. We gain insight into the interplay between cellular and mechanical processes during biofilm development on air-agar interfaces by means of a hybrid model. Cellular behavior is governed by stochastic rules informed by a cascade of concentration fields for nutrients, waste, and autoinducers. Cellular differentiation and death alter the structure and the mechanical properties of the biofilm, which is deformed according to Föppl-Von Kármán equations informed by cellular processes and the interaction with the substratum. Stiffness gradients due to growth and swelling produce wrinkle branching. We are able to reproduce wrinkled structures often formed by biofilms on air-agar interfaces, as well as spatial distributions of differentiated cells commonly observed with B. subtilis.

  18. Exogenous Polyunsaturated Fatty Acids Impact Membrane Remodeling and Affect Virulence Phenotypes among Pathogenic Vibrio Species.

    Science.gov (United States)

    Moravec, Anna R; Siv, Andrew W; Hobby, Chelsea R; Lindsay, Emily N; Norbash, Layla V; Shults, Daniel J; Symes, Steven J K; Giles, David K

    2017-11-15

    The pathogenic Vibrio species ( V. cholerae , V. parahaemolyticus , and V. vulnificus ) represent a constant threat to human health, causing foodborne and skin wound infections as a result of ingestion of or exposure to contaminated water and seafood. Recent studies have highlighted Vibrio 's ability to acquire fatty acids from environmental sources and assimilate them into cell membranes. The possession and conservation of such machinery provokes consideration of fatty acids as important factors in the pathogenic lifestyle of Vibrio species. The findings here link exogenous fatty acid exposure to changes in bacterial membrane phospholipid structure, permeability, phenotypes associated with virulence, and consequent stress responses that may impact survival and persistence of pathogenic Vibrio species. Polyunsaturated fatty acids (PUFAs) (ranging in carbon length and unsaturation) supplied in growth medium were assimilated into bacterial phospholipids, as determined by thin-layer chromatography and liquid chromatography-mass spectrometry. The incorporation of fatty acids variably affected membrane permeability, as judged by uptake of the hydrophobic compound crystal violet. For each species, certain fatty acids were identified as affecting resistance to antimicrobial peptide treatment. Significant fluctuations were observed with regard to both motility and biofilm formation following growth in the presence of individual PUFAs. Our results illustrate the important and complex roles of exogenous fatty acids in the membrane physiology and virulence of a bacterial genus that inhabits aquatic and host environments containing an abundance of diverse fatty acids. IMPORTANCE Bacterial responses to fatty acids include, but are not limited to, degradation for metabolic gain, modification of membrane lipids, alteration of protein function, and regulation of gene expression. Vibrio species exhibit significant diversity with regard to the machinery known to participate in the

  19. Exogenous hydrogen sulfide promotes cell proliferation and differentiation by modulating autophagy in human keratinocytes

    International Nuclear Information System (INIS)

    Xie, Xin; Dai, Hui; Zhuang, Binyu; Chai, Li; Xie, Yanguang; Li, Yuzhen

    2016-01-01

    The effects and the underlying mechanisms of hydrogen sulfide (H 2 S) on keratinocyte proliferation and differentiation are still less known. In the current study, we investigated the effects and the underlying mechanisms of exogenous H 2 S on keratinocyte proliferation and differentiation. Human keratinocytes (HaCaT cells) were treated with various concentrations (0.05, 0.25, 0.5 and 1 mM) of sodium hydrosulfide (NaHS, a donor of H 2 S) for 24 h. A CCK-8 assay was used to assess cell viability. Western blot analysis was performed to determine the expression levels of proteins associated with differentiation and autophagy. Transmission electron microscopy was performed to observe autophagic vacuoles, and flow cytometry was applied to evaluate apoptosis. NaHS promoted the viability, induced the differentiation, and enhanced autophagic activity in a dose-dependent manner in HaCaT cells but had no effect on cell apoptosis. Blockage of autophagy by ATG5 siRNA inhibited NaHS-induced cell proliferation and differentiation. The current study demonstrated that autophagy in response to exogenous H 2 S treatment promoted keratinocyte proliferation and differentiation. Our results provide additional insights into the potential role of autophagy in keratinocyte proliferation and differentiation. - Highlights: • Exogenous H 2 S promotes keratinocyte proliferation and differentiation. • The effects of H 2 S on proliferation and differentiation is modulated by autophagy. • Exogenous H 2 S has no effect on keratinocyte apoptosis.

  20. Transcriptional Profiling of Biofilm Regulators Identified by an Overexpression Screen in Saccharomyces cerevisiae

    Science.gov (United States)

    Cromie, Gareth A.; Tan, Zhihao; Hays, Michelle; Sirr, Amy; Jeffery, Eric W.; Dudley, Aimée M.

    2017-01-01

    Biofilm formation by microorganisms is a major cause of recurring infections and removal of biofilms has proven to be extremely difficult given their inherent drug resistance . Understanding the biological processes that underlie biofilm formation is thus extremely important and could lead to the development of more effective drug therapies, resulting in better infection outcomes. Using the yeast Saccharomyces cerevisiae as a biofilm model, overexpression screens identified DIG1, SFL1, HEK2, TOS8, SAN1, and ROF1/YHR177W as regulators of biofilm formation. Subsequent RNA-seq analysis of biofilm and nonbiofilm-forming strains revealed that all of the overexpression strains, other than DIG1 and TOS8, were adopting a single differential expression profile, although induced to varying degrees. TOS8 adopted a separate profile, while the expression profile of DIG1 reflected the common pattern seen in most of the strains, plus substantial DIG1-specific expression changes. We interpret the existence of the common transcriptional pattern seen across multiple, unrelated overexpression strains as reflecting a transcriptional state, that the yeast cell can access through regulatory signaling mechanisms, allowing an adaptive morphological change between biofilm-forming and nonbiofilm states. PMID:28673928

  1. Levorotatory carbohydrates and xylitol subdue Streptococcus mutans and Candida albicans adhesion and biofilm formation.

    Science.gov (United States)

    Brambilla, Eugenio; Ionescu, Andrei C; Cazzaniga, Gloria; Ottobelli, Marco; Samaranayake, Lakshman P

    2016-05-01

    Dietary carbohydrates and polyols affect the microbial colonization of oral surfaces by modulating adhesion and biofilm formation. The aim of this study was to evaluate the influence of a select group of l-carbohydrates and polyols on either Streptococcus mutans or Candida albicans adhesion and biofilm formation in vitro. S. mutans or C. albicans suspensions were inoculated on polystyrene substrata in the presence of Tryptic soy broth containing 5% of the following compounds: d-glucose, d-mannose, l-glucose, l-mannose, d- and l-glucose (raceme), d- and l-mannose (raceme), l-glucose and l-mannose, sorbitol, mannitol, and xylitol. Microbial adhesion (2 h) and biofilm formation (24 h) were evaluated using MTT-test and Scanning Electron Microscopy (SEM). Xylitol and l-carbohydrates induced the lowest adhesion and biofilm formation in both the tested species, while sorbitol and mannitol did not promote C. albicans biofilm formation. Higher adhesion and biofilm formation was noted in both organisms in the presence of d-carbohydrates relative to their l-carbohydrate counterparts. These results elucidate, hitherto undescribed, interactions of the individually tested strains with l- and d-carbohydrates, and how they impact fungal and bacterial colonization. In translational terms, our data raise the possibility of using l-form of carbohydrates and xylitol for dietary control of oral plaque biofilms. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. The Extracellular Matrix of Candida albicans Biofilms Impairs Formation of Neutrophil Extracellular Traps.

    Science.gov (United States)

    Johnson, Chad J; Cabezas-Olcoz, Jonathan; Kernien, John F; Wang, Steven X; Beebe, David J; Huttenlocher, Anna; Ansari, Hamayail; Nett, Jeniel E

    2016-09-01

    Neutrophils release extracellular traps (NETs) in response to planktonic C. albicans. These complexes composed of DNA, histones, and proteins inhibit Candida growth and dissemination. Considering the resilience of Candida biofilms to host defenses, we examined the neutrophil response to C. albicans during biofilm growth. In contrast to planktonic C. albicans, biofilms triggered negligible release of NETs. Time lapse imaging confirmed the impairment in NET release and revealed neutrophils adhering to hyphae and migrating on the biofilm. NET inhibition depended on an intact extracellular biofilm matrix as physical or genetic disruption of this component resulted in NET release. Biofilm inhibition of NETosis could not be overcome by protein kinase C activation via phorbol myristate acetate (PMA) and was associated with suppression of neutrophil reactive oxygen species (ROS) production. The degree of impaired NET release correlated with resistance to neutrophil attack. The clinical relevance of the role for extracellular matrix in diminishing NET production was corroborated in vivo using a rat catheter model. The C. albicans pmr1Δ/Δ, defective in production of matrix mannan, appeared to elicit a greater abundance of NETs by scanning electron microscopy imaging, which correlated with a decreased fungal burden. Together, these findings show that C. albicans biofilms impair neutrophil response through an inhibitory pathway induced by the extracellular matrix.

  3. Exogenous fibroblast growth factor 9 attenuates cartilage degradation and aggravates osteophyte formation in post-traumatic osteoarthritis.

    Science.gov (United States)

    Zhou, S; Wang, Z; Tang, J; Li, W; Huang, J; Xu, W; Luo, F; Xu, M; Wang, J; Wen, X; Chen, L; Chen, H; Su, N; Shen, Y; Du, X; Xie, Y; Chen, L

    2016-12-01

    The aim of the present study is to investigate the effects of exogenous fibroblast growth factor (FGF)9 on the progression of post-traumatic osteoarthritis (OA). The expression of FGF9 in articular cartilage with OA is detected by immunohistochemistry (IHC). The effects of intra-articular exogenous FGF9 injection on post-traumatic OA induced by the destabilization of the medial meniscus (DMM) surgery are evaluated. Cartilage changes and osteophyte formation in knee joints are investigated by histological analysis. Changes in subchondral bone are evaluated by microcomputed tomography (micro-CT). The effect of exogenous FGF9 on an interleukin-1β (IL-1β)-induced ex vivo OA model of human articular cartilage tissues is also evaluated. FGF9 expression was down-regulated in articular chondrocytes of OA but ectopically induced at sites of osteophyte formation. Intra-articular injection of exogenous FGF9 attenuated articular cartilage degradation in mice after DMM surgery. Exogenous FGF9 suppressed collagen X and MMP13 expressions in OA cartilage, while promoted collagen II expression. Similar results were observed in IL-1β-induced ex vivo OA model. Intra-articular injection of FGF9 had no significant effect on the subchondral bone of knee joints after DMM surgery, but aggravated osteophyte formation. The expressions of SOX9 and collagen II, and cell proliferation were up-regulated at sites of initial osteophyte formation in mice with exogenous FGF9 treatment. Intra-articular injection of exogenous FGF9 delays articular cartilage degradation in post-traumatic OA, while aggravates osteophyte formation. Copyright © 2016. Published by Elsevier Ltd.

  4. Soluble factors from biofilm of Candida albicans and Staphylococcus aureus promote cell death and inflammatory response.

    Science.gov (United States)

    de Carvalho Dias, Kassia; Barbugli, Paula Aboud; de Patto, Fernanda; Lordello, Virginia Barreto; de Aquino Penteado, Letícia; Medeiros, Alexandra Ivo; Vergani, Carlos Eduardo

    2017-06-30

    The objective of this study was to better understand the effects of soluble factors from biofilm of single- and mixed-species Candida albicans (C. albicans) and methicillin-sensitive Staphylococcus aureus (MSSA) cultures after 36 h in culture on keratinocytes (NOK-si and HaCaT) and macrophages (J774A.1). Soluble factors from biofilms of C. albicans and MSSA were collected and incubated with keratinocytes and macrophages, which were subsequently evaluated by cell viability assays (MTT). Lactate dehydrogenase (LDH) enzyme release was measured to assess cell membrane damage to keratinocytes. Cells were analysed by brightfield microscopy after 2 and 24 h of exposure to the soluble factors from biofilm. Cell death was detected by labelling apoptotic cells with annexin V and necrotic cells with propidium iodide (PI) and was visualized via fluorescence microscopy. Soluble factors from biofilm were incubated with J774A.1 cells for 24 h; the subsequent production of NO and the cytokines IL-6 and TNF-α was measured by ELISA. The cell viability assays showed that the soluble factors of single-species C. albicans cultures were as toxic as the soluble factors from biofilm of mixed cultures, whereas the soluble factors of MSSA cultures were less toxic than those of C. albicans or mixed cultures. The soluble factors from biofilm of mixed cultures were the most toxic to the NOK-si and HaCaT cells, as confirmed by analyses of PI labelling and cell morphology. Soluble factors from biofilm of single-species MSSA and mixed-species cultures induced the production of IL-6, NO and TNF-α by J744A.1 macrophages. The production of IL-6 and NO induced by the soluble factors from biofilm of mixed cultures was lower than that induced by the soluble factors from biofilm of single-species MSSA cultures, whereas the soluble factors from biofilm of C. albicans cultures induced only low levels of NO. Soluble factors from 36-h-old biofilm of C. albicans and MSSA cultures promoted cell death and

  5. Role of biofilms in sorptive removal of steroidal hormones and 4-nonylphenol compounds from streams

    Science.gov (United States)

    Writer, Jeffrey H.; Ryan, Joseph N.; Barber, Larry B.

    2011-01-01

    Stream biofilms play an important role in geochemical processing of organic matter and nutrients, however, the significance of this matrix in sorbing trace organic contaminants is less understood. This study focused on the role of stream biofilms in sorbing steroidal hormones and 4-nonylphenol compounds from surface waters using biofilms colonized in situ on artificial substrata and subsequently transferred to the laboratory for controlled batch sorption experiments. Steroidal hormones and 4-nonylphenol compounds readily sorb to stream biofilms as indicated by organic matter partition coefficients (Kom, L kg–1) for 17β-estradiol (102.5–2.8 L kg–1), 17α-ethynylestradiol (102.5–2.9 L kg–1), 4-nonylphenol (103.4–4.6 L kg–1), 4-nonylphenolmonoethoxylate (103.5–4.0 L kg–1), and 4-nonylphenoldiethoxylate (103.9–4.3 L kg–1). Experiments using water quality differences to induce changes in the relative composition of periphyton and heterotrophic bacteria in the stream biofilm did not significantly affect the sorptive properties of the stream biofilm, providing additional evidence that stream biofilms will sorb trace organic compounds under of variety of environmental conditions. Because sorption of the target compounds to stream biofilms was linearly correlated with organic matter content, hydrophobic partition into organic matter appears to be the dominant mechanism. An analysis of 17β-estradiol and 4-nonylphenol hydrophobic partition into water, biofilm, sediment, and dissolved organic matter matrices at mass/volume ratios typical of smaller rivers showed that the relative importance of the stream biofilm as a sorptive matrix was comparable to bed sediments. Therefore, stream biofilms play a primary role in attenuating these compounds in surface waters. Because the stream biofilm represents the base of the stream ecosystem, accumulation of steroidal hormones and 4-nonylphenol compounds in the stream biofilm may be an exposure pathway for

  6. Potential coupling effects of ammonia-oxidizing and anaerobic ammonium-oxidizing bacteria on completely autotrophic nitrogen removal over nitrite biofilm formation induced by the second messenger cyclic diguanylate.

    Science.gov (United States)

    Wang, Chao; Liu, Sitong; Xu, Xiaochen; Zhao, Chuanqi; Yang, Fenglin; Wang, Dong

    2017-05-01

    The objective of this study was to investigate the influence of extracellular polymeric substance (EPS) on the coupling effects between ammonia-oxidizing bacteria (AOB) and anaerobic ammonium-oxidizing (anammox) bacteria for the completely autotrophic nitrogen removal over nitrite (CANON) biofilm formation in a moving bed biofilm reactor (MBBR). Analysis of the quantity of EPS and cyclic diguanylate (c-di-GMP) confirmed that the contents of polysaccharides and c-di-GMP were correlated in the AOB sludge, anammox sludge, and CANON biofilm. The anammox sludge secreted more EPS (especially polysaccharides) than AOB with a markedly higher c-di-GMP content, which could be used by the bacteria to regulate the synthesis of exopolysaccharides that are ultimately used as a fixation matrix, for the adhesion of biomass. Indeed, increased intracellular c-di-GMP concentrations in the anammox sludge enhanced the regulation of polysaccharides to promote the adhesion of AOB and formation of the CANON biofilm. Overall, the results of this study provide new comprehensive information regarding the coupling effects of AOB and anammox bacteria for the nitrogen removal process.

  7. Medical biofilms--nanotechnology approaches.

    Science.gov (United States)

    Neethirajan, Suresh; Clond, Morgan A; Vogt, Adam

    2014-10-01

    Biofilms are colonies of bacteria or fungi that adhere to a surface, protected by an extracellular polymer matrix composed of polysaccharides and extracellular DNA. They are highly complex and dynamic multicellular structures that resist traditional means of killing planktonic bacteria. Recent developments in nanotechnology provide novel approaches to preventing and dispersing biofilm infections, which are a leading cause of morbidity and mortality. Medical device infections are responsible for approximately 60% of hospital acquired infections. In the United States, the estimated cost of caring for healthcare-associated infections is approximately between $28 billion and $45 billion per year. In this review, we will discuss our current understanding of biofilm formation and degradation, its relevance to challenges in clinical practice, and new technological developments in nanotechnology that are designed to address these challenges.

  8. Synergistic Interactions in Multispecies Biofilms

    DEFF Research Database (Denmark)

    Ren, Dawei

    The coexistence of hugely diverse microbes in most environments highlights the intricate interactions in microbial communities, which are central to their properties, such as productivity, stability and the resilience to disturbance. Biofilm, in environmental habitats, is such a spatially...... multispecies biofilm models, oral microbial community, also known as “dental plaque” is thoroughly investigated as a focal point to describe the interspecies interactions [1]. However, owing to the lack of a reliable high throughput and quantitative approach for exploring the interplay between multiple...... bacterial species, the study to elucidate the impact of interaction networks on the multispecies biofilms in natural ecosystems, especially in soil, is still at an early stage. The diverse patterns of interactions within the mixed communities as well as the predatorprey relationship between protozoa...

  9. Biofilms in the Food Industry: Health Aspects and Control Methods

    Science.gov (United States)

    Galié, Serena; García-Gutiérrez, Coral; Miguélez, Elisa M.; Villar, Claudio J.; Lombó, Felipe

    2018-01-01

    Diverse microorganisms are able to grow on food matrixes and along food industry infrastructures. This growth may give rise to biofilms. This review summarizes, on the one hand, the current knowledge regarding the main bacterial species responsible for initial colonization, maturation and dispersal of food industry biofilms, as well as their associated health issues in dairy products, ready-to-eat foods and other food matrixes. These human pathogens include Bacillus cereus (which secretes toxins that can cause diarrhea and vomiting symptoms), Escherichia coli (which may include enterotoxigenic and even enterohemorrhagic strains), Listeria monocytogenes (a ubiquitous species in soil and water that can lead to abortion in pregnant women and other serious complications in children and the elderly), Salmonella enterica (which, when contaminating a food pipeline biofilm, may induce massive outbreaks and even death in children and elderly), and Staphylococcus aureus (known for its numerous enteric toxins). On the other hand, this review describes the currently available biofilm prevention and disruption methods in food factories, including steel surface modifications (such as nanoparticles with different metal oxides, nanocomposites, antimicrobial polymers, hydrogels or liposomes), cell-signaling inhibition strategies (such as lactic and citric acids), chemical treatments (such as ozone, quaternary ammonium compounds, NaOCl and other sanitizers), enzymatic disruption strategies (such as cellulases, proteases, glycosidases and DNAses), non-thermal plasma treatments, the use of bacteriophages (such as P100), bacteriocins (such us nisin), biosurfactants (such as lichenysin or surfactin) and plant essential oils (such as citral- or carvacrol-containing oils). PMID:29867809

  10. Biofilms in the Food Industry: Health Aspects and Control Methods

    Directory of Open Access Journals (Sweden)

    Serena Galié

    2018-05-01

    Full Text Available Diverse microorganisms are able to grow on food matrixes and along food industry infrastructures. This growth may give rise to biofilms. This review summarizes, on the one hand, the current knowledge regarding the main bacterial species responsible for initial colonization, maturation and dispersal of food industry biofilms, as well as their associated health issues in dairy products, ready-to-eat foods and other food matrixes. These human pathogens include Bacillus cereus (which secretes toxins that can cause diarrhea and vomiting symptoms, Escherichia coli (which may include enterotoxigenic and even enterohemorrhagic strains, Listeria monocytogenes (a ubiquitous species in soil and water that can lead to abortion in pregnant women and other serious complications in children and the elderly, Salmonella enterica (which, when contaminating a food pipeline biofilm, may induce massive outbreaks and even death in children and elderly, and Staphylococcus aureus (known for its numerous enteric toxins. On the other hand, this review describes the currently available biofilm prevention and disruption methods in food factories, including steel surface modifications (such as nanoparticles with different metal oxides, nanocomposites, antimicrobial polymers, hydrogels or liposomes, cell-signaling inhibition strategies (such as lactic and citric acids, chemical treatments (such as ozone, quaternary ammonium compounds, NaOCl and other sanitizers, enzymatic disruption strategies (such as cellulases, proteases, glycosidases and DNAses, non-thermal plasma treatments, the use of bacteriophages (such as P100, bacteriocins (such us nisin, biosurfactants (such as lichenysin or surfactin and plant essential oils (such as citral- or carvacrol-containing oils.

  11. Killing mediated spatial structure in V. Cholerae biofilms

    Science.gov (United States)

    Yanni, David

    Most bacteria live in biofilms, which are implicated in 60 - 80 % of microbial infections in the body. The spatial structure of a biofilm confers advantages to its member-cells, such as antibiotic resistance, and is strongly affected by competition between strains and taxa. However, A complete picture of how competition affects the self-organized structure of these complex, far-from-equilibrium systems, is yet to emerge. To that end, we investigate phase separation dynamics driven by T6SS-facilitated bacterial warfare in a system composed of two strains of mutually antagonistic V. cholerae. T6SS is a contact mediated killing mechanism present in 25 % of all gram negative bacteria, and has been shown by recent work to play a major role in the spatial assortment of biofilms. T6SS events induce lysis, causing variations in local mechanical pressure, and acting as thermalizing events. We study cells immobilized in biofilms at the air-solid interface, so our experimental system represents a different type active matter, wherein activity is due to cell death and reproduction, not mobility. Here, we show how that activity imposes a constraint of minimal curvature on strain-strain interfaces; an effective Laplace pressure is characterized which governs interfacial dynamics.

  12. Growing and Analyzing Biofilms in Flow Chambers

    DEFF Research Database (Denmark)

    Tolker-Nielsen, Tim; Sternberg, Claus

    2011-01-01

    This unit describes the setup of flow chamber systems for the study of microbial biofilms, and methods for the analysis of structural biofilm formation. Use of flow chambers allows direct microscopic investigation of biofilm formation. The biofilms in flow chambers develop under hydrodynamic......, and disassembly and cleaning of the system. In addition, embedding and fluorescent in situ hybridization of flow chamber–grown biofilms are addressed. Curr. Protoc. Microbiol. 21:1B.2.1-1B.2.17. © 2011 by John Wiley & Sons, Inc....

  13. Pattern formation in Pseudomonas aeruginosa biofilms

    DEFF Research Database (Denmark)

    Parsek, Matthew R.; Tolker-Nielsen, Tim

    2008-01-01

    Bacteria are capable of forming elaborate multicellular communities called biofilms. Pattern formation in biofilms depends on cell proliferation and cellular migration in response to the available nutrients and other external cues, as well as on self-generated intercellular signal molecules...... and the production of an extracellular matrix that serves as a structural 'scaffolding' for the biofilm cells. Pattern formation in biofilms allows cells to position themselves favorably within nutrient gradients and enables buildup and maintenance of physiologically distinct subpopulations, which facilitates...... survival of one or more subpopulations upon environmental insult, and therefore plays an important role in the innate tolerance displayed by biofilms toward adverse conditions....

  14. Biofilm reactors for ethanol production

    Energy Technology Data Exchange (ETDEWEB)

    Vega, J L; Clausen, E C; Gaddy, J L

    1988-07-01

    Whole cell immobilization has been studied in the laboratory during the last few years as a method to improve the performance and economics of most fermentation processes. Among the various techniques available for cell immobilization, methods that provide generation of a biofilm offer reduced diffusional resistance, high productivities, and simple operation. This paper reviews some of the important aspects of biofilm reactors for ethanol production, including reactor start-up, steady state behavior, process stability, and mathematical modeling. Special emphasis is placed on covalently bonded Saccharomyces cerevisiae in packed bed reactors.

  15. Symbiotic Relationship between Streptococcus mutans and Candida albicans Synergizes Virulence of Plaque Biofilms In Vivo

    Science.gov (United States)

    Falsetta, Megan L.; Klein, Marlise I.; Colonne, Punsiri M.; Scott-Anne, Kathleen; Gregoire, Stacy; Pai, Chia-Hua; Gonzalez-Begne, Mireya; Watson, Gene; Krysan, Damian J.; Bowen, William H.

    2014-01-01

    Streptococcus mutans is often cited as the main bacterial pathogen in dental caries, particularly in early-childhood caries (ECC). S. mutans may not act alone; Candida albicans cells are frequently detected along with heavy infection by S. mutans in plaque biofilms from ECC-affected children. It remains to be elucidated whether this association is involved in the enhancement of biofilm virulence. We showed that the ability of these organisms together to form biofilms is enhanced in vitro and in vivo. The presence of C. albicans augments the production of exopolysaccharides (EPS), such that cospecies biofilms accrue more biomass and harbor more viable S. mutans cells than single-species biofilms. The resulting 3-dimensional biofilm architecture displays sizeable S. mutans microcolonies surrounded by fungal cells, which are enmeshed in a dense EPS-rich matrix. Using a rodent model, we explored the implications of this cross-kingdom interaction for the pathogenesis of dental caries. Coinfected animals displayed higher levels of infection and microbial carriage within plaque biofilms than animals infected with either species alone. Furthermore, coinfection synergistically enhanced biofilm virulence, leading to aggressive onset of the disease with rampant carious lesions. Our in vitro data also revealed that glucosyltransferase-derived EPS is a key mediator of cospecies biofilm development and that coexistence with C. albicans induces the expression of virulence genes in S. mutans (e.g., gtfB, fabM). We also found that Candida-derived β1,3-glucans contribute to the EPS matrix structure, while fungal mannan and β-glucan provide sites for GtfB binding and activity. Altogether, we demonstrate a novel mutualistic bacterium-fungus relationship that occurs at a clinically relevant site to amplify the severity of a ubiquitous infectious disease. PMID:24566629

  16. Enzymatic degradation of in vitro Staphylococcus aureus biofilms supplemented with human plasma

    Directory of Open Access Journals (Sweden)

    Watters CM

    2016-04-01

    Full Text Available Chase M Watters,1,2 Tarea Burton,1 Dickson K Kirui,1 Nancy J Millenbaugh1 1Maxillofacial Injury and Disease Department, Naval Medical Research Unit San Antonio, Joint Base San Antonio-Fort Sam Houston, TX, USA; 2Wound Infections Department, Naval Medical Research Center, Silver Spring, MD, USA Abstract: Enzymatic debridement is a therapeutic strategy used clinically to remove necrotic tissue from wounds. Some of the enzymes utilized for debridement have been tested against bacterial pathogens, but the effectiveness of these agents in dispersing clinically relevant biofilms has not been fully characterized. Here, we developed an in vitro Staphylococcus aureus biofilm model that mimics wound-like conditions and employed this model to investigate the antibiofilm activity of four enzymatic compounds. Human plasma at concentrations of 0%–50% was supplemented into growth media and used to evaluate biofilm biomass accumulation over 24 hours and 48 hours in one methicillin-sensitive and five methicillin-resistant strains of S. aureus. Supplementation of media with 10% human plasma resulted in the most robust biofilms in all six strains. The enzymes α-amylase, bromelain, lysostaphin, and papain were then tested against S. aureus biofilms cultured in 10% human plasma. Quantification of biofilms after 2 hours and 24 hours of treatment using the crystal violet assay revealed that lysostaphin decreased biomass by up to 76%, whereas a-amylase, bromelain, and papain reduced biomass by up to 97%, 98%, and 98%, respectively. Scanning electron microscopy confirmed that the dispersal agents detached the biofilm exopolysaccharide matrix and bacteria from the growth surface. Lysostaphin caused less visible dispersal of the biofilms, but unlike the other enzymes, induced morphological changes indicative of bacterial cell damage. Overall, our results indicate that use of enzymes may be an effective means of eradicating biofilms and a promising strategy to improve

  17. A short history of microbial biofilms and biofilm infections

    DEFF Research Database (Denmark)

    Høiby, Niels

    2017-01-01

    The observation of aggregated microbes surrounded by a self-produced matrix adhering to surfaces or located in tissues or secretions is old since both Leeuwenhoek and Pasteur have described the phenomenon. In environmental and technical microbiology, biofilms, 80–90 years ago, were already shown ...

  18. Molecular Basis for Saccharomyces cerevisiae Biofilm Development

    DEFF Research Database (Denmark)

    Andersen, Kaj Scherz

    In this study, I sought to identify genes regulating the global molecular program for development of sessile multicellular communities, also known as biofilm, of the eukaryotic microorganism, Saccharomyces cerevisiae (yeast). Yeast biofilm has a clinical interest, as biofilms can cause chronic...... infections in humans. Biofilm is also interesting from an evolutionary standpoint, as an example of primitive multicellularity. By using a genome-wide screen of yeast deletion mutants, I show that 71 genes are essential for biofilm formation. Two-thirds of these genes are required for transcription of FLO11......, but only a small subset is previously described as regulators of FLO11. These results reveal that the regulation of biofilm formation and FLO11 is even more complex than what has previously been described. I find that the molecular program for biofilm formation shares many essential components with two...

  19. Cell death in Pseudomonas aeruginosa biofilm development

    DEFF Research Database (Denmark)

    Webb, J.S.; Thompson, L.S.; James, S.

    2003-01-01

    Bacteria growing in biofilms often develop multicellular, three-dimensional structures known as microcolonies. Complex differentiation within biofilms of Pseudomonas aeruginosa occurs, leading to the creation of voids inside microcolonies and to the dispersal of cells from within these voids....... However, key developmental processes regulating these events are poorly understood. A normal component of multicellular development is cell death. Here we report that a repeatable pattern of cell death and lysis occurs in biofilms of P. aeruginosa during the normal course of development. Cell death...... occurred with temporal and spatial organization within biofilms, inside microcolonies, when the biofilms were allowed to develop in continuous-culture flow cells. A subpopulation of viable cells was always observed in these regions. During the onset of biofilm killing and during biofilm development...

  20. Modelling the growth of a methanotrophic biofilm

    DEFF Research Database (Denmark)

    Arcangeli, J.-P.; Arvin, E.

    1999-01-01

    This article discusses the growth of methanotrophic biofilms. Several independent biofilm growths scenarios involving different inocula were examined. Biofilm growth, substrate removal and product formation were monitored throughout the experiments. Based on the oxygen consumption it was concluded...... that heterotrophs and nitrifiers co-existed with methanotrophs in the biofilm. Heterotrophic biomass grew on soluble polymers formed by the hydrolysis of dead biomass entrapped in the biofilm. Nitrifier populations developed because of the presence of ammonia in the mineral medium. Based on these experimental...... was performed on this model. It indicated that the most influential parameters were those related to the biofilm (i.e. density; solid-volume fraction; thickness). This suggests that in order to improve the model, further research regarding the biofilm structure and composition is needed....

  1. Biofilms of vaginal Lactobacillus in vitro test.

    Science.gov (United States)

    Wei, Xiao-Yu; Zhang, Rui; Xiao, Bing-Bing; Liao, Qin-Ping

    2017-01-01

    This paper focuses on biofilms of Lactobacillus spp. - a type of normal flora isolated from healthy human vaginas of women of childbearing age; thereupon, it broadens the research scope of investigation of vaginal normal flora. The static slide culture method was adopted to foster biofilms, marked by specific fluorescence staining. Laser scanning confocal and scanning electron microscopy were used to observe the microstructure of the biofilms. Photographs taken from the microstructure were analysed to calculate the density of the biofilms. The body of Lactobacillus spp., though red, turned yellow when interacting with the green extracellular polysaccharides. The structure of the biofilm and aquaporin within the biofilm were imaged. Lactobacillus density increases over time. This study provides convincing evidence that Lactobacillus can form biofilms and grow over time in vitro. This finding establishes an important and necessary condition for selecting proper strains for the pharmaceutics of vaginal ecology.

  2. The clinical impact of bacterial biofilms

    DEFF Research Database (Denmark)

    Høiby, Niels; Ciofu, Oana; Johansen, Helle Krogh

    2011-01-01

    Bacteria survive in nature by forming biofilms on surfaces and probably most, if not all, bacteria (and fungi) are capable of forming biofilms. A biofilm is a structured consortium of bacteria embedded in a self-produced polymer matrix consisting of polysaccharide, protein and extracellular DNA....... Bacterial biofilms are resistant to antibiotics, disinfectant chemicals and to phagocytosis and other components of the innate and adaptive inflammatory defense system of the body. It is known, for example, that persistence of staphylococcal infections related to foreign bodies is due to biofilm formation....... Likewise, chronic Pseudomonas aeruginosa lung infections in cystic fibrosis patients are caused by biofilm growing mucoid strains. Gradients of nutrients and oxygen exist from the top to the bottom of biofilms and the bacterial cells located in nutrient poor areas have decreased metabolic activity...

  3. Techniques for augmentation of exogenous DNA uptake by ovine spermatozoa

    Science.gov (United States)

    Hoseini Pajooh, K.; Tajik, P.; Karimipoor, M.; Behdani, M.

    2016-01-01

    Sperm mediated gene transfer can be an inexpensive and simple method in animal transgenesis; however its efficiency is poor, mainly due to the spermatozoa’s lesser uptake of exogenous DNA. In the present study, the effects of lipofection and other augmentation techniques, such as sperm freezing and spermatozoa treatment with triton X100 and DMSO, on exogenous DNA uptake by sheep spermatozoa and motility of sperms with plasmid uptake were evaluated. In the first experiment, ram sperms were incubated with a complex of rhodamine labeled plasmid (p-EGFP) and Lipofectamine 2000TM. In the second, spermatozoa were treated with Triton X-100TM or DMSO or were frozen without cryoprotectant. The results indicated that there was no significant difference (Plipofected sperms with 300 and 600 ng of plasmid in comparison with control group, i.e. transfected without lipofectamine. Furthermore, lipofection could not improve sperm motility during true plasmid uptake. Almost all of triton X100 treated and frozen-thawed spermatozoa had absorbed foreign DNA, though all were immotile. In spermatozoa treated with 0.1% DMSO, plasmid absorption rate (69.40%) was significantly higher (P<0.05) than untreated spermatozoa (57.80%), but sperm motility was not significantly different from control group. In conclusion, lipofectamine® 2000 could neither improve transfection rate, nor support motility in transfected sperms. The methods inducing membrane disruption like, freeze-thaw and triton X100 treatment, can be used in ICSI-sperm mediated gene transfer without the need for sperm selection, provided that they cause no damage to sperm nucleus. PMID:27656225

  4. Interplay between endogenous and exogenous fluctuations in financial markets

    OpenAIRE

    Gontis, Vygintas

    2016-01-01

    We address microscopic, agent based, and macroscopic, stochastic, modeling of the financial markets combining it with the exogenous noise. The interplay between the endogenous dynamics of agents and the exogenous noise is the primary mechanism responsible for the observed long-range dependence and statistical properties of high volatility return intervals. By exogenous noise we mean information flow or/and order flow fluctuations. Numerical results based on the proposed model reveal that the ...

  5. International Environmental Agreements with Endogenous or Exogenous Risk

    OpenAIRE

    Fuhai Hong; Larry Karp

    2014-01-01

    We examine the effect of endogenous and exogenous risk on the equilibrium (expected) membership of an International Environmental Agreement when countries are risk averse. Endogenous risk arises when countries use mixed rather than pure strategies at the participation game, and exogenous risk arises from the inherent uncertainty about the costs and benefits of increased abate- ment. Under endogenous risk, an increase in risk aversion increases expected participation. Under exogenous risk and ...

  6. Radiochemical method for evaluating the effect of antibiotics on Escherichia coli biofilms

    International Nuclear Information System (INIS)

    Dix, B.A.; Cohen, P.S.; Laux, D.C.; Cleeland, R.

    1988-01-01

    A simple radiochemical method for evaluating the action of antibiotics on Escherichia coli cells in biofilms is reported. After growth, biofilms of E. coli ATCC 25922 on disks of urinary catheter material were suspended in fresh medium containing or lacking an antibiotic, incubated for 4 h at 37 degrees C, and pulse-labeled with [ 3 H]leucine for 5 min. Radioactivity in trichloracetic acid-precipitable material in the biofilm and in the surrounding medium (planktonic E. coli) was then measured. Antibiotic-induced inhibition of incorporation of [ 3 H]leucine into the cells in the biofilm was far less pronounced than incorporation into planktonic cells and, furthermore, correlated well with loss in viable counts. The method is simple, inexpensive, and extremely timesaving

  7. Control of bacterial biofilm growth on surfaces by nanostructural mechanics and geometry

    International Nuclear Information System (INIS)

    Epstein, A K; Hochbaum, A I; Kim, Philseok; Aizenberg, J

    2011-01-01

    Surface-associated communities of bacteria, called biofilms, pervade natural and anthropogenic environments. Mature biofilms are resistant to a wide range of antimicrobial treatments and therefore pose persistent pathogenic threats. The use of surface chemistry to inhibit biofilm growth has been found to only transiently affect initial attachment. In this work, we investigate the tunable effects of physical surface properties, including high-aspect-ratio (HAR) surface nanostructure arrays recently reported to induce long-range spontaneous spatial patterning of bacteria on the surface. The functional parameters and length scale regimes that control such artificial patterning for the rod-shaped pathogenic species Pseudomonas aeruginosa are elucidated through a combinatorial approach. We further report a crossover regime of biofilm growth on a HAR nanostructured surface versus the nanostructure effective stiffness. When the 'softness' of the hair-like nanoarray is increased beyond a threshold value, biofilm growth is inhibited as compared to a flat control surface. This result is consistent with the mechanoselective adhesion of bacteria to surfaces. Therefore by combining nanoarray-induced bacterial patterning and modulating the effective stiffness of the nanoarray—thus mimicking an extremely compliant flat surface—bacterial mechanoselective adhesion can be exploited to control and inhibit biofilm growth.

  8. Current and future trends for biofilm reactors for fermentation processes.

    Science.gov (United States)

    Ercan, Duygu; Demirci, Ali

    2015-03-01

    Biofilms in the environment can both cause detrimental and beneficial effects. However, their use in bioreactors provides many advantages including lesser tendencies to develop membrane fouling and lower required capital costs, their higher biomass density and operation stability, contribution to resistance of microorganisms, etc. Biofilm formation occurs naturally by the attachment of microbial cells to the support without use of any chemicals agent in biofilm reactors. Biofilm reactors have been studied and commercially used for waste water treatment and bench and pilot-scale production of value-added products in the past decades. It is important to understand the fundamentals of biofilm formation, physical and chemical properties of a biofilm matrix to run the biofilm reactor at optimum conditions. This review includes the principles of biofilm formation; properties of a biofilm matrix and their roles in the biofilm formation; factors that improve the biofilm formation, such as support materials; advantages and disadvantages of biofilm reactors; and industrial applications of biofilm reactors.

  9. [Inhibitory effect of exogenous insulin-like growth factor binding protein 7 on proliferation of human breast cancer cell line MDA-MB-453 and its mechanism].

    Science.gov (United States)

    Yuan, Lei; Fan, Wen-Juan; Yang, Xu-Guang; Rao, Shu-Mei; Song, Jin-Ling; Song, Guo-Hua

    2013-10-25

    The present study was to investigate the effects of exogenous insulin-like growth factor binding protein 7 (IGFBP7) on the proliferation of human breast cancer cell line MDA-MB-453 and its possible mechanism. By means of MTT method in vitro, the results showed exogenous IGFBP7 inhibited the growth of MDA-MB-453 cells (IC50 of IGFBP7 = 8.49 μg/mL) in time- and concentration-dependent manner. SB203580, p38(MAPK) inhibitor, blocked the anti-proliferative effect of exogenous IGFBP7. The flow cytometry assay showed that exogenous IGFBP7 remarkably induced G0/G1 arrest in MDA-MB-453 cells. The Western blot showed that exogenous IGFBP7 promoted phosphorylation of p38(MAPK), up-regulated expression of p21(CIP1/WAF1), and inhibited phosphorylation of Rb. SB203580 restrained exogenous IGFBP7-induced regulation of p21(CIP1/WAF1) and p-Rb in MDA-MB-453 cells. In conclusion, the present study suggests that exogenous IGFBP7 could activate the p38(MAPK) signaling pathway, upregulate p21(CIP1/WAF1) expression, inhibit phosphorylation of Rb, and finally induce G0/G1 arrest in MDA-MB-453 cells.

  10. Exogenously triggered response inhibition in developmental stuttering.

    Science.gov (United States)

    Eggers, Kurt; De Nil, Luc F; Van den Bergh, Bea R H

    2018-06-01

    The purpose of the present study was to examine relations between children's exogenously triggered response inhibition and stuttering. Participants were 18 children who stutter (CWS; mean age = 9;01 years) and 18 children who not stutter (CWNS; mean age = 9;01 years). Participants were matched on age (±3 months) and gender. Response inhibition was assessed by a stop signal task (Verbruggen, Logan, & Stevens, 2008). Results suggest that CWS, compared to CWNS, perform comparable to CWNS in a task where response control is externally triggered. Our findings seem to indicate that previous questionnaire-based findings (Eggers, De Nil, & Van den Bergh, 2010) of a decreased efficiency of response inhibition cannot be generalized to all types of response inhibition. Copyright © 2018 Elsevier Inc. All rights reserved.

  11. Candida biofilms: is adhesion sexy?

    Science.gov (United States)

    Soll, David R

    2008-08-26

    The development of Candida albicans biofilms requires two types of adhesion molecule - the Als proteins and Hwp1. Mutational analyses have recently revealed that these molecules play complementary roles, and their characteristics suggest that they may have evolved from primitive mating agglutinins.

  12. Biofilm in drinking water networks

    International Nuclear Information System (INIS)

    Cristiani, Pietrangela

    2005-01-01

    Bacterial growth in drinking waters is today controlled adding small and non toxic quantities of sanitising products. An innovative electrochemical biofilm monitoring system, already successfully applied in industrial waters, could be confirmed as an effective diagnostic tool of water quality also for drinking distributions systems [it

  13. Regulation of mutagenesis by exogenous biological factors in the eukaryotic cell systems

    Directory of Open Access Journals (Sweden)

    Lukash L. L.

    2013-07-01

    Full Text Available The representations of the mutations and the nature of spontaneous mutation process and mutagenesis induced by exogenous oncoviruses, DNAs and proteins-mitogens are analysed. Exogenous biological factors induce DNA damages in regulatory-informational way, acting on the cellular systems for maintenance of genetical stability. Molecular mechanisms are the same as at spontaneous mutagenesis but they are realized with the participation of alien genetical material. Among biological mutagens, the oncoviruses and mobile genetic elements (MGEs are distinguished as the strongest destabilizing factors which direct tumor transformation of somatic mammalian cells. Genetical reprogramming or changing the programs of gene expression at the differentiation of stem and progenitor cells under growth factors and citokines is probably followed by mutations and recombinations as well.

  14. The effects of exogenous melatonin on the morphology of thyrocytes in pinealectomized and irradiated rats

    International Nuclear Information System (INIS)

    Kundurovic, Z.; Sofic, E.

    2006-01-01

    We investigated the effects of exogenous melatonin on the thyrocytes morphology in gamma-irradiated rats under condition where the pineal gland, as a main physiological source of endogenous melatonin, was removed. Three months after pinealectomy animals were divided into two groups: one group of animals was treated with 0.5 ml of vehicle (ethanol diluted in water) and other group was injected intraperitoneally 2 mg/kg of melatonin dissolved in 0.5 ml of vehicle daily during the period of fourteen days. After this treatment all the animals were irradiated with a single dose of 8 Gy gamma rays. Ionising radiation induced apoptosis, hydropic swelling or/and necrosis in both groups of animals, however these changes were less discerned in the thyrocytes of melatonin-treated animals. Our findings demonstrate that administration of exogenous melatonin prior to irradiation reduces radiation-induced thyrocytes damage. (author)

  15. Dynamics and spatial distribution of beta-lactamase expression in Pseudomonas aeruginosa biofilms

    DEFF Research Database (Denmark)

    Bagge, N.; Hentzer, Morten; Andersen, Jens Bo

    2004-01-01

    of increased imipenem concentrations. Ceftazidime induced the monitor system of the biofilm bacteria as well, but only bacteria in the peripheries of the microcolonies were induced in the presence of even very high concentrations. The experiments illustrate for the first time the dynamic and spatial...

  16. Susceptibility patterns and the role of extracellular DNA in Staphylococcus epidermidis biofilm resistance to physico-chemical stress exposure.

    Science.gov (United States)

    Olwal, Charles Ochieng'; Ang'ienda, Paul Oyieng'; Onyango, David Miruka; Ochiel, Daniel Otieno

    2018-05-02

    Over 65% of human infections are ascribed to bacterial biofilms that are often highly resistant to antibiotics and host immunity. Staphylococcus epidermidis is the predominant cause of recurrent nosocomial and biofilm-related infections. However, the susceptibility patterns of S. epidermidis biofilms to physico-chemical stress induced by commonly recommended disinfectants [(heat, sodium chloride (NaCl), sodium hypochlorite (NaOCl) and hydrogen peroxide (H 2 O 2 )] in domestic and human healthcare settings remains largely unknown. Further, the molecular mechanisms of bacterial biofilms resistance to the physico-chemical stresses remain unclear. Growing evidence demonstrates that extracellular DNA (eDNA) protects bacterial biofilms against antibiotics. However, the role of eDNA as a potential mechanism underlying S. epidermidis biofilms resistance to physico-chemical stress exposure is yet to be understood. Therefore, this study aimed to evaluate the susceptibility patterns of and eDNA release by S. epidermidis biofilm and planktonic cells to physico-chemical stress exposure. S. epidermidis biofilms exposed to physico-chemical stress conditions commonly recommended for disinfection [heat (60 °C), 1.72 M NaCl, solution containing 150 μL of waterguard (0.178 M NaOCl) in 1 L of water or 1.77 M H 2 O 2 ] for 30 and 60 min exhibited lower log reductions of CFU/mL than the corresponding planktonic cells (p chemical stress induced by the four commonly recommended disinfectants than the analogous planktonic cells. Further, S. epidermidis biofilms enhanced eDNA release in response to the sub-lethal heat and oxidative stress exposure than the corresponding planktonic cells suggesting a role of eDNA in biofilms resistance to the physico-chemical stresses.

  17. Shewanella putrefaciens Adhesion and Biofilm Formation on Food Processing Surfaces

    Science.gov (United States)

    Bagge, Dorthe; Hjelm, Mette; Johansen, Charlotte; Huber, Ingrid; Gram, Lone

    2001-01-01

    Laboratory model systems were developed for studying Shewanella putrefaciens adhesion and biofilm formation under batch and flow conditions. S. putrefaciens plays a major role in food spoilage and may cause microbially induced corrosion on steel surfaces. S. putrefaciens bacteria suspended in buffer adhered readily to stainless steel surfaces. Maximum numbers of adherent bacteria per square centimeter were reached in 8 h at 25°C and reflected the cell density in suspension. Numbers of adhering bacteria from a suspension containing 108 CFU/ml were much lower in a laminar flow system (modified Robbins device) (reaching 102 CFU/cm2) than in a batch system (reaching 107 CFU/cm2), and maximum numbers were reached after 24 h. When nutrients were supplied, S. putrefaciens grew in biofilms with layers of bacteria. The rate of biofilm formation and the thickness of the film were not dependent on the availability of carbohydrate (lactate or glucose) or on iron starvation. The number of S. putrefaciens bacteria on the surface was partly influenced by the presence of other bacteria (Pseudomonas fluorescens) which reduced the numbers of S. putrefaciens bacteria in the biofilm. Numbers of bacteria on the surface must be quantified to evaluate the influence of environmental factors on adhesion and biofilm formation. We used a combination of fluorescence microscopy (4′,6′-diamidino-2-phenylindole staining and in situ hybridization, for mixed-culture studies), ultrasonic removal of bacteria from surfaces, and indirect conductometry and found this combination sufficient to quantify bacteria on surfaces. PMID:11319118

  18. Hypoxia Potentiates Anabolic Effects of Exogenous Hyaluronic Acid in Rat Articular Cartilage

    Directory of Open Access Journals (Sweden)

    Shohei Ichimaru

    2016-06-01

    Full Text Available Hyaluronic acid (HA is used clinically to treat osteoarthritis (OA, but its pharmacological effects under hypoxic conditions remain unclear. Articular chondrocytes in patients with OA are exposed to a hypoxic environment. This study investigated whether hypoxia could potentiate the anabolic effects of exogenous HA in rat articular cartilage and whether these mechanisms involved HA receptors. HA under hypoxic conditions significantly enhanced the expression of extracellular matrix genes and proteins in explant culture, as shown by real-time reverse transcription-polymerase chain reaction (RT-PCR, Western blotting, and dimethylmethylene blue (DMMB assays. Staining with Safranin-O and immunohistochemical staining with antibody to type II collagen were also enhanced in pellet culture. The expression of CD44 was increased by hypoxia and significantly suppressed by transfection with siRNAs targeting hypoxia-inducible factor 1 alpha (siHIF-1α. These findings indicate that hypoxia potentiates the anabolic effects of exogenous HA by a mechanism in which HIF-1α positively regulates the expression of CD44, enhancing the binding affinity for exogenous HA. The anabolic effects of exogenous HA may increase as OA progresses.

  19. Hypoxia Potentiates Anabolic Effects of Exogenous Hyaluronic Acid in Rat Articular Cartilage.

    Science.gov (United States)

    Ichimaru, Shohei; Nakagawa, Shuji; Arai, Yuji; Kishida, Tsunao; Shin-Ya, Masaharu; Honjo, Kuniaki; Tsuchida, Shinji; Inoue, Hiroaki; Fujiwara, Hiroyoshi; Shimomura, Seiji; Mazda, Osam; Kubo, Toshikazu

    2016-06-25

    Hyaluronic acid (HA) is used clinically to treat osteoarthritis (OA), but its pharmacological effects under hypoxic conditions remain unclear. Articular chondrocytes in patients with OA are exposed to a hypoxic environment. This study investigated whether hypoxia could potentiate the anabolic effects of exogenous HA in rat articular cartilage and whether these mechanisms involved HA receptors. HA under hypoxic conditions significantly enhanced the expression of extracellular matrix genes and proteins in explant culture, as shown by real-time reverse transcription-polymerase chain reaction (RT-PCR), Western blotting, and dimethylmethylene blue (DMMB) assays. Staining with Safranin-O and immunohistochemical staining with antibody to type II collagen were also enhanced in pellet culture. The expression of CD44 was increased by hypoxia and significantly suppressed by transfection with siRNAs targeting hypoxia-inducible factor 1 alpha (siHIF-1α). These findings indicate that hypoxia potentiates the anabolic effects of exogenous HA by a mechanism in which HIF-1α positively regulates the expression of CD44, enhancing the binding affinity for exogenous HA. The anabolic effects of exogenous HA may increase as OA progresses.

  20. From Mouth to Model: Combining in vivo and in vitro oral biofilm growth

    Directory of Open Access Journals (Sweden)

    Barbara Klug

    2016-09-01

    demonstrate the in vitro survival of native primary oral biofilm in its natural complexity over 48 hours. Our results offer a baseline for cultivation studies of native oral biofilms in (phyto- pharmacological and dental materials research. Further investigations and validation of culturing conditions could also facilitate the study of biofilm-induced diseases.

  1. Regulation of biofilm formation in Shewanella oneidensis by BpfA, BpfG, and BpfD

    Directory of Open Access Journals (Sweden)

    Guangqi eZhou

    2015-08-01

    Full Text Available Bacteria switch between two distinct life styles -- planktonic (free living and biofilm forming -- in keeping with their ever-changing environment. Such switch involves sophisticated signaling and tight regulation, which provides a fascinating portal for studying gene function and orchestrated protein interactions. In this work, we investigated the molecular mechanism underlying biofilm formation in S. oneidensis MR-1, an environmentally important model bacterium renowned for respiratory diversities, and uncovered a gene cluster coding for seven proteins involved in this process. The three key proteins, BpfA, BpfG, and BpfD, were studied in detail for the first time. BpfA directly participates in biofilm formation as extracellular glue; BpfG is not only indispensable for BpfA export during biofilm forming but also functions to turn BpfA into active form for biofilm dispersing. BpfD regulates biofilm development by interacting with both BpfA and BpfG, likely in response to signal molecule c-di-GMP. In addition, we found that 1:1 stoichiometry between BpfD and BpfG is critical for biofilm formation. Furthermore, we demonstrated that a biofilm over-producing phenotype can be induced by C116S mutation but not loss of BpfG.

  2. Serrulatane Diterpenoid from Eremophila neglecta Exhibits Bacterial Biofilm Dispersion and Inhibits Release of Pro-inflammatory Cytokines from Activated Macrophages.

    Science.gov (United States)

    Mon, Htwe H; Christo, Susan N; Ndi, Chi P; Jasieniak, Marek; Rickard, Heather; Hayball, John D; Griesser, Hans J; Semple, Susan J

    2015-12-24

    The purpose of this study was to assess the biofilm-removing efficacy and inflammatory activity of a serrulatane diterpenoid, 8-hydroxyserrulat-14-en-19-oic acid (1), isolated from the Australian medicinal plant Eremophila neglecta. Biofilm breakup activity of compound 1 on established Staphylococcus epidermidis and Staphylococcus aureus biofilms was compared to the antiseptic chlorhexidine and antibiotic levofloxacin. In a time-course study, 1 was deposited onto polypropylene mesh to mimic a wound dressing and tested for biofilm removal. The ex-vivo cytotoxicity and effect on lipopolysaccharide-induced pro-inflammatory cytokine release were studied in mouse primary bone-marrow-derived macrophage (BMDM) cells. Compound 1 was effective in dispersing 12 h pre-established biofilms with a 7 log10 reduction of viable bacterial cell counts, but was less active against 24 h biofilms (approximately 2 log10 reduction). Compound-loaded mesh showed dosage-dependent biofilm-removing capability. In addition, compound 1 displayed a significant inhibitory effect on tumor necrosis factor alpha (TNF-α) and interleukin-6 (IL-6) secretion from BMDM cells, but interleukin-1 beta (IL-1β) secretion was not significant. The compound was not cytotoxic to BMDM cells at concentrations effective in removing biofilm and lowering cytokine release. These findings highlight the potential of this serrulatane diterpenoid to be further developed for applications in wound management.

  3. Listeria monocytogenes impact on mature or old Pseudomonas fluorescens biofilms during growth at 4 and 20ºC

    Directory of Open Access Journals (Sweden)

    Puga eCH

    2016-02-01

    Full Text Available Changes in spatial organization, as observed by confocal laser scanning microscopy (CLSM, viable cell content, biovolume and substratum surface coverage of the biofilms formed on glass by Pseudomonas fluorescens resulting from co-culture with Listeria monocytogenes, were examined. Two strains of L. monocytogenes, two culture temperatures and two biofilm developmental stages were investigated. Both L. monocytogenes strains, a persistently sampled isolate (collected repeatedly along 3 years from a meat factory and Scott A, induced shrinkage in matrix volume, both at 20ºC and 4ºC, in mature or old biofilms, without loss of P. fluorescens cell count per surface unit. The nearly homogeneous pattern of surface coverage shown by mono-species P. fluorescens biofilms, turned into more irregular layouts in co-culture with L. monocytogenes. The upper layer of both mono and dual-species biofilms turned to predominantly consist of matrix, with plenty of viable cells underneath, in old biofilms cultured at 20ºC, but not in those grown at 4ºC. Between 15 and 56% of the substratum area was covered by biofilm, the extent depending on temperature, time and L. monocytogenes strain. Real biofilms in food-related surfaces may thus be very heterogeneous regarding their superficial components, i.e. those more accessible to disinfectants. It is therefore a hygienic challenge to choose an adequate agent to disrupt them.

  4. Hydrodynamic dispersion within porous biofilms

    KAUST Repository

    Davit, Y.

    2013-01-23

    Many microorganisms live within surface-associated consortia, termed biofilms, that can form intricate porous structures interspersed with a network of fluid channels. In such systems, transport phenomena, including flow and advection, regulate various aspects of cell behavior by controlling nutrient supply, evacuation of waste products, and permeation of antimicrobial agents. This study presents multiscale analysis of solute transport in these porous biofilms. We start our analysis with a channel-scale description of mass transport and use the method of volume averaging to derive a set of homogenized equations at the biofilm-scale in the case where the width of the channels is significantly smaller than the thickness of the biofilm. We show that solute transport may be described via two coupled partial differential equations or telegrapher\\'s equations for the averaged concentrations. These models are particularly relevant for chemicals, such as some antimicrobial agents, that penetrate cell clusters very slowly. In most cases, especially for nutrients, solute penetration is faster, and transport can be described via an advection-dispersion equation. In this simpler case, the effective diffusion is characterized by a second-order tensor whose components depend on (1) the topology of the channels\\' network; (2) the solute\\'s diffusion coefficients in the fluid and the cell clusters; (3) hydrodynamic dispersion effects; and (4) an additional dispersion term intrinsic to the two-phase configuration. Although solute transport in biofilms is commonly thought to be diffusion dominated, this analysis shows that hydrodynamic dispersion effects may significantly contribute to transport. © 2013 American Physical Society.

  5. Reprogramming with Small Molecules instead of Exogenous Transcription Factors

    Directory of Open Access Journals (Sweden)

    Tongxiang Lin

    2015-01-01

    Full Text Available Induced pluripotent stem cells (iPSCs could be employed in the creation of patient-specific stem cells, which could subsequently be used in various basic and clinical applications. However, current iPSC methodologies present significant hidden risks with respect to genetic mutations and abnormal expression which are a barrier in realizing the full potential of iPSCs. A chemical approach is thought to be a promising strategy for safety and efficiency of iPSC generation. Many small molecules have been identified that can be used in place of exogenous transcription factors and significantly improve iPSC reprogramming efficiency and quality. Recent studies have shown that the use of small molecules results in the generation of chemically induced pluripotent stem cells from mouse embryonic fibroblast cells. These studies might lead to new areas of stem cell research and medical applications, not only human iPSC by chemicals alone, but also safe generation of somatic stem cells for cell based clinical trials and other researches. In this paper, we have reviewed the recent advances in small molecule approaches for the generation of iPSCs.

  6. Galactose metabolism plays a crucial role in biofilm formation by Bacillus subtilis.

    Science.gov (United States)

    Chai, Yunrong; Beauregard, Pascale B; Vlamakis, Hera; Losick, Richard; Kolter, Roberto

    2012-01-01

    Galactose is a common monosaccharide that can be utilized by all living organisms via the activities of three main enzymes that make up the Leloir pathway: GalK, GalT, and GalE. In Bacillus subtilis, the absence of GalE causes sensitivity to exogenous galactose, leading to rapid cell lysis. This effect can be attributed to the accumulation of toxic galactose metabolites, since the galE mutant is blocked in the final step of galactose catabolism. In a screen for suppressor mutants restoring viability to a galE null mutant in the presence of galactose, we identified mutations in sinR, which is the major biofilm repressor gene. These mutations caused an increase in the production of the exopolysaccharide (EPS) component of the biofilm matrix. We propose that UDP-galactose is the toxic galactose metabolite and that it is used in the synthesis of EPS. Thus, EPS production can function as a shunt mechanism for this toxic molecule. Additionally, we demonstrated that galactose metabolism genes play an essential role in B. subtilis biofilm formation and that the expressions of both the gal and eps genes are interrelated. Finally, we propose that B. subtilis and other members of the Bacillus genus may have evolved to utilize naturally occurring polymers of galactose, such as galactan, as carbon sources. Bacteria switch from unicellular to multicellular states by producing extracellular matrices that contain exopolysaccharides. In such aggregates, known as biofilms, bacteria are more resistant to antibiotics. This makes biofilms a serious problem in clinical settings. The resilience of biofilms makes them very useful in industrial settings. Thus, understanding the production of biofilm matrices is an important problem in microbiology. In studying the synthesis of the biofilm matrix of Bacillus subtilis, we provide further understanding of a long-standing microbiological observation that certain mutants defective in the utilization of galactose became sensitive to it. In this

  7. Dynamic interactions of neutrophils and biofilms

    Directory of Open Access Journals (Sweden)

    Josefine Hirschfeld

    2014-12-01

    Full Text Available Background: The majority of microbial infections in humans are biofilm-associated and difficult to treat, as biofilms are highly resistant to antimicrobial agents and protect themselves from external threats in various ways. Biofilms are tenaciously attached to surfaces and impede the ability of host defense molecules and cells to penetrate them. On the other hand, some biofilms are beneficial for the host and contain protective microorganisms. Microbes in biofilms express pathogen-associated molecular patterns and epitopes that can be recognized by innate immune cells and opsonins, leading to activation of neutrophils and other leukocytes. Neutrophils are part of the first line of defense and have multiple antimicrobial strategies allowing them to attack pathogenic biofilms. Objective/design: In this paper, interaction modes of neutrophils with biofilms are reviewed. Antimicrobial strategies of neutrophils and the counteractions of the biofilm communities, with special attention to oral biofilms, are presented. Moreover, possible adverse effects of neutrophil activity and their biofilm-promoting side effects are discussed. Results/conclusion: Biofilms are partially, but not entirely, protected against neutrophil assault, which include the processes of phagocytosis, degranulation, and formation of neutrophil extracellular traps. However, virulence factors of microorganisms, microbial composition, and properties of the extracellular matrix determine whether a biofilm and subsequent microbial spread can be controlled by neutrophils and other host defense factors. Besides, neutrophils may inadvertently contribute to the physical and ecological stability of biofilms by promoting selection of more resistant strains. Moreover, neutrophil enzymes can degrade collagen and other proteins and, as a result, cause harm to the host tissues. These parameters could be crucial factors in the onset of periodontal inflammation and the subsequent tissue breakdown.

  8. Enhancing tolerance of rice (Oryza sativa) to simulated acid rain by exogenous abscisic acid.

    Science.gov (United States)

    Wu, Xi; Liang, Chanjuan

    2017-02-01

    Abscisic acid (ABA) regulates much important plant physiological and biochemical processes and induces tolerance to different stresses. Here, we studied the regulation of exogenous ABA on adaptation of rice seedlings to simulated acid rain (SAR) stress by measuring biomass dry weight, stomatal conductance, net photosynthesis rate, nutrient elements, and endogenous hormones. The application of 10 μM ABA alleviated the SAR-induced inhibition on growth, stomatal conductance, net photosynthesis rate, and decreases in contents of nutrient (K, Mg, N, and P) and hormone (auxin, gibberellins, and zeatin). Moreover, 10 μM ABA could stimulate the Ca content as signaling molecules under SAR stress. Contrarily, the application of 100 μM ABA aggravated the SAR-induced inhibition on growth, stomatal conductance, net photosynthesis rate, and contents of nutrient and hormone. The results got after a 5-day recovery (without SAR) show that exogenous 10 μM ABA can promote self-restoration process in rice whereas 100 μM ABA hindered the restoration by increasing deficiency of nutrients and disturbing the balance of hormones. These results confirmed that exogenous ABA at proper concentration could enhance the tolerance of rice to SAR stress.

  9. Exogeneous brassinosteroids induce changes in ecdysteroid content in plants

    Czech Academy of Sciences Publication Activity Database

    Kamlar, M.; Salajková, Š.; Rezek, J.; Rothová, O.; Tarkowská, Danuše; Drašar, P.; Kočová, M.; Harmatha, Juraj; Holá, D.; Kohout, Ladislav; Macek, T.

    2014-01-01

    Roč. 108, S2 (2014), s132 ISSN 0009-2770. [Conference on Isoprenoids /22./. 07.09.2014-10.09.2014, Praha] Grant - others:GA ČR(CZ) GAP501/11/1650 Institutional support: RVO:61388963 ; RVO:61389030 Keywords : ecdysteroids * brassinosteroids Subject RIV: CC - Organic Chemistry

  10. Unsaturated Fatty Acid, cis-2-Decenoic Acid, in Combination with Disinfectants or Antibiotics Removes Pre-Established Biofilms Formed by Food-Related Bacteria

    Science.gov (United States)

    Sepehr, Shayesteh; Rahmani-Badi, Azadeh; Babaie-Naiej, Hamta; Soudi, Mohammad Reza

    2014-01-01

    Biofilm formation by food-related bacteria and food-related pathogenesis are significant problems in the food industry. Even though much disinfection and mechanical procedure exist for removal of biofilms, they may fail to eliminate pre-established biofilms. cis-2 decenoic acid (CDA), an unsaturated fatty acid messenger produced by Pseudomonas aeruginosa, is reportedly capable of inducing the dispersion of established biofilms by multiple types of microorganisms. However, whether CDA has potential to boost the actions of certain antimicrobials is unknown. Here, the activity of CDA as an inducer of pre-established biofilms dispersal, formed by four main food pathogens; Staphylococcus aureus, Bacillus cereus, Salmonella enterica and E. coli, was measured using both semi-batch and continuous cultures bioassays. To assess the ability of CDA combined biocides treatments to remove pre-established biofilms formed on stainless steel discs, CFU counts were performed for both treated and untreated cultures. Eradication of the biofilms by CDA combined antibiotics was evaluated using crystal violet staining. The effect of CDA combined treatments (antibiotics and disinfectants) on biofilm surface area and bacteria viability was evaluated using fluorescence microscopy, digital image analysis and LIVE/DEAD staining. MICs were also determined to assess the probable inhibitory effects of CDA combined treatments on the growth of tested microorganisms' planktonic cells. Treatment of pre-established biofilms with only 310 nM CDA resulted in at least two-fold increase in the number of planktonic cells in all cultures. While antibiotics or disinfectants alone exerted a trivial effect on CFU counts and percentage of surface area covered by the biofilms, combinational treatments with both 310 nM CDA and antibiotics or disinfectants led to approximate 80% reduction in biofilm biomass. These data suggests that combined treatments with CDA would pave the way toward developing new strategies

  11. Unsaturated fatty acid, cis-2-decenoic acid, in combination with disinfectants or antibiotics removes pre-established biofilms formed by food-related bacteria.

    Directory of Open Access Journals (Sweden)

    Shayesteh Sepehr

    Full Text Available Biofilm formation by food-related bacteria and food-related pathogenesis are significant problems in the food industry. Even though much disinfection and mechanical procedure exist for removal of biofilms, they may fail to eliminate pre-established biofilms. cis-2 decenoic acid (CDA, an unsaturated fatty acid messenger produced by Pseudomonas aeruginosa, is reportedly capable of inducing the dispersion of established biofilms by multiple types of microorganisms. However, whether CDA has potential to boost the actions of certain antimicrobials is unknown. Here, the activity of CDA as an inducer of pre-established biofilms dispersal, formed by four main food pathogens; Staphylococcus aureus, Bacillus cereus, Salmonella enterica and E. coli, was measured using both semi-batch and continuous cultures bioassays. To assess the ability of CDA combined biocides treatments to remove pre-established biofilms formed on stainless steel discs, CFU counts were performed for both treated and untreated cultures. Eradication of the biofilms by CDA combined antibiotics was evaluated using crystal violet staining. The effect of CDA combined treatments (antibiotics and disinfectants on biofilm surface area and bacteria viability was evaluated using fluorescence microscopy, digital image analysis and LIVE/DEAD staining. MICs were also determined to assess the probable inhibitory effects of CDA combined treatments on the growth of tested microorganisms' planktonic cells. Treatment of pre-established biofilms with only 310 nM CDA resulted in at least two-fold increase in the number of planktonic cells in all cultures. While antibiotics or disinfectants alone exerted a trivial effect on CFU counts and percentage of surface area covered by the biofilms, combinational treatments with both 310 nM CDA and antibiotics or disinfectants led to approximate 80% reduction in biofilm biomass. These data suggests that combined treatments with CDA would pave the way toward

  12. Mycobacterium biofilms: factors involved in development, dispersal, and therapeutic strategies against biofilm-relevant pathogens.

    Science.gov (United States)

    Xiang, Xiaohong; Deng, Wanyan; Liu, Minqiang; Xie, Jianping

    2014-01-01

    Many bacteria can develop biofilm (BF), a multicellular structure largely combining bacteria and their extracellular polymeric substances (EPS). The formation of biofilm results in an alternative existence in which microbes ensure their survival in adverse environments. Biofilm-relevant infections are more persistent, resistant to most antibiotics, and more recalcitrant to host immunity. Mycobacterium tuberculosis, the causative agent of tuberculosis, can develop biofilm, though whether M. tuberculosis can form biofilm within tuberculosis patients has yet to be determined. Here, we summarize the factors involved in the development and dispersal of mycobacterial biofilms, as well as underlying regulatory factors and inhibitors against biofilm to deepen our understanding of their development and to elucidate potential novel modes of action for future antibiotics. Key factors in biofilm formation identified as drug targets represent a novel and promising avenue for developing better antibiotics.

  13. Pseudomonas aeruginosa Biofilm, a Programmed Bacterial Life for Fitness.

    Science.gov (United States)

    Lee, Keehoon; Yoon, Sang Sun

    2017-06-28

    A biofilm is a community of microbes that typically inhabit on surfaces and are encased in an extracellular matrix. Biofilms display very dissimilar characteristics to their planktonic counterparts. Biofilms are ubiquitous in the environment and influence our lives tremendously in both positive and negative ways. Pseudomonas aeruginosa is a bacterium known to produce robust biofilms. P. aeruginosa biofilms cause severe problems in immunocompromised patients, including those with cystic fibrosis or wound infection. Moreover, the unique biofilm properties further complicate the eradication of the biofilm infection, leading to the development of chronic infections. In this review, we discuss the history of biofilm research and general characteristics of bacterial biofilms. Then, distinct features pertaining to each stage of P. aeruginosa biofilm development are highlighted. Furthermore, infections caused by biofilms on their own or in association with other bacterial species ( i.e. , multispecies biofilms) are discussed in detail.

  14. Novel metabolic activity indicator in Streptococcus mutans biofilms

    NARCIS (Netherlands)

    Deng, D.M.; Hoogenkamp, M.A.; ten Cate, J.M.; Crielaard, W.

    2009-01-01

    Antimicrobial resistance of micro-organisms in biofilms requires novel strategies to evaluate the efficacy of caries preventive agents in actual biofilms. Hence we investigated fluorescence intensity (FI) in Streptococcus mutans biofilms constitutively expressing green fluorescent protein (GFP).

  15. The effects of exogenous proline and osmotic stress on morpho ...

    African Journals Online (AJOL)

    USER

    2010-06-21

    Jun 21, 2010 ... For evaluation of growth parameters of strawberry callus under osmotic stress and exogenous proline, embryonic calli were transferred to Murashige and Skoog (MS) medium containing four sucrose. (osmotic stress) treatments including 3, 6, 9 and 12% and various concentrations of exogenous L- proline ...

  16. The effects of exogenous proline and osmotic stress on morpho ...

    African Journals Online (AJOL)

    For evaluation of growth parameters of strawberry callus under osmotic stress and exogenous proline, embryonic calli were transferred to Murashige and Skoog (MS) medium containing four sucrose (osmotic stress) treatments including 3, 6, 9 and 12% and various concentrations of exogenous Lproline (0, 2.5, 5 and 10 ...

  17. Explaining Cigarette Smoking: An Endogenous-Exogenous Analysis.

    Science.gov (United States)

    McKillip, Jack

    Kruglanski's endogenous-exogenous partition, when applied to reasons given by smokers for smoking cigarettes, distinguishes two types of actions: (1) endogenous reasons implying that the behavior of consuming the cigarette is the goal of the action and the actor is positive toward the behavior, and (2) exogenous reasons implying that the behavior…

  18. Effect Of Exogenous Progesterone On Blood Chemistry Of Large ...

    African Journals Online (AJOL)

    Exogenous hormones are major economic factors in swine production. This study evaluate the effects of exogenous administration of progesterone on the blood chemistry of pigs.Experiment involved weekly injections of progesterone to 24 pigs (12 males and 12 females)from day old to 24 weeks and only corn oil to another ...

  19. The Endogenous-Exogenous Partition in Attribution Theory

    Science.gov (United States)

    Kruglanski, Arie W.

    1975-01-01

    Within lay explanation of actions, several significant inferences are assumed to follow from the partition between endogenous and exogenous attributions. An endogenous action is judged to constitute an end in itself; an exogenous action is judged to serve as a means to some further end. (Editor/RK)

  20. Novel approaches to mitigating bacterial biofilm formation and intercellular communication

    Science.gov (United States)

    Kasper, Stephen H.

    Long thought of as solitary single-cell organisms, it is now widely accepted that bacteria can act and cooperate as social organisms. Phenomena such as biofilm formation and quorum sensing (QS) are two intimately intertwined cooperative behaviors that significantly contribute to the pathogenesis of many bacteria. Biofilms are surface associated communities of bacteria encased in a secreted extracellular matrix, which provides several advantages over an individualized lifestyle, such as increased protection from antimicrobial agents as well as enhanced opportunity for the exchange of genetic material. Bacterial QS is a system of population-based communication through the production, sensing, and response to chemical signals, often controlling the expression of diverse virulence factors (e.g. toxins, proteases). Biofilm formation and QS are cooperative processes that are often leveraged as bacteria coordinate infection processes, and can therefore be novel targets for anti-infective treatments that differ from conventional antibiotic treatment. Our lab has previously identified a novel class of small molecules that inhibit biofilm formation and disrupt QS by the pathogenic bacterium Pseudomonas aeruginosa. These organosulfur-based compounds are either natural products or related derivatives of the tropical plant Petiveria alliacea. Because oral biofilm (e.g. dental plaque) is a major conduit of oral and systemic disease, and is also a site for horizontal transfer for genes encoding antibiotic resistance, there exists a need for novel strategies for inhibiting oral biofilm development. Therefore, a small library (˜50 compounds) of structural derivatives was developed and screened for their ability to inhibit biofilm formation by multiple orally associated bacteria. The screening effort uncovered several related compounds that inhibited oral biofilm development. To determine how natural product-based organosulfur compounds could be inducing QS inhibitory effects, an

  1. Transcriptional and functional analysis of the effects of magnolol: inhibition of autolysis and biofilms in Staphylococcus aureus.

    Science.gov (United States)

    Wang, Dacheng; Jin, Qi; Xiang, Hua; Wang, Wei; Guo, Na; Zhang, Kaiyu; Tang, Xudong; Meng, Rizeng; Feng, Haihua; Liu, Lihui; Wang, Xiaohong; Liang, Junchao; Shen, Fengge; Xing, Mingxun; Deng, Xuming; Yu, Lu

    2011-01-01

    The targeting of Staphylococcus aureus biofilm structures are now gaining interest as an alternative strategy for developing new types of antimicrobial agents. Magnolol (MOL) shows inhibitory activity against S. aureus biofilms and Triton X-100-induced autolysis in vitro, although there are no data regarding the molecular mechanisms of MOL action in bacteria. The molecular basis of the markedly reduced autolytic phenotype and biofilm inhibition triggered by MOL were explored using transcriptomic analysis, and the transcription of important genes were verified by real-time RT-PCR. The inhibition of autolysis by MOL was evaluated using quantitative bacteriolytic assays and zymographic analysis, and antibiofilm activity assays and confocal laser scanning microscopy were used to elucidate the inhibition of biofilm formation caused by MOL in 20 clinical isolates or standard strains. The reduction in cidA, atl, sle1, and lytN transcript levels following MOL treatment was consistent with the induced expression of their autolytic repressors lrgA, lrgB, arlR, and sarA. MOL generally inhibited or reversed the expression of most of the genes involved in biofilm production. The growth of S. aureus strain ATCC 25923 in the presence of MOL dose-dependently led to decreases in Triton X-100-induced autolysis, extracellular murein hydrolase activity, and the amount of extracellular DNA (eDNA). MOL may impede biofilm formation by reducing the expression of cidA, a murein hydrolase regulator, to inhibit autolysis and eDNA release, or MOL may directly repress biofilm formation. MOL shows in vitro antimicrobial activity against clinical and standard S. aureus strains grown in planktonic and biofilm cultures, suggesting that the structure of MOL may potentially be used as a basis for the development of drugs targeting biofilms.

  2. Transcriptional and functional analysis of the effects of magnolol: inhibition of autolysis and biofilms in Staphylococcus aureus.

    Directory of Open Access Journals (Sweden)

    Dacheng Wang

    Full Text Available BACKGROUND: The targeting of Staphylococcus aureus biofilm structures are now gaining interest as an alternative strategy for developing new types of antimicrobial agents. Magnolol (MOL shows inhibitory activity against S. aureus biofilms and Triton X-100-induced autolysis in vitro, although there are no data regarding the molecular mechanisms of MOL action in bacteria. METHODOLOGY/PRINCIPAL FINDINGS: The molecular basis of the markedly reduced autolytic phenotype and biofilm inhibition triggered by MOL were explored using transcriptomic analysis, and the transcription of important genes were verified by real-time RT-PCR. The inhibition of autolysis by MOL was evaluated using quantitative bacteriolytic assays and zymographic analysis, and antibiofilm activity assays and confocal laser scanning microscopy were used to elucidate the inhibition of biofilm formation caused by MOL in 20 clinical isolates or standard strains. The reduction in cidA, atl, sle1, and lytN transcript levels following MOL treatment was consistent with the induced expression of their autolytic repressors lrgA, lrgB, arlR, and sarA. MOL generally inhibited or reversed the expression of most of the genes involved in biofilm production. The growth of S. aureus strain ATCC 25923 in the presence of MOL dose-dependently led to decreases in Triton X-100-induced autolysis, extracellular murein hydrolase activity, and the amount of extracellular DNA (eDNA. MOL may impede biofilm formation by reducing the expression of cidA, a murein hydrolase regulator, to inhibit autolysis and eDNA release, or MOL may directly repress biofilm formation. CONCLUSIONS/SIGNIFICANCE: MOL shows in vitro antimicrobial activity against clinical and standard S. aureus strains grown in planktonic and biofilm cultures, suggesting that the structure of MOL may potentially be used as a basis for the development of drugs targeting biofilms.

  3. Staphylococcus aureus biofilm removal by targeting biofilm-associated extracellular proteins

    Directory of Open Access Journals (Sweden)

    Sudhir K Shukla

    2017-01-01

    Methods: Biofilm assay was done in 96-well microtitre plate to evaluate the effect of proteinase K on biofilms of bovine mastitis S. Aureus isolates. Extracellular polymeric substances were extracted and evaluated for their composition (protein, polysaccharides and extracellular DNA, before and after the proteinase K treatment. Results: Biofilm assay showed that 2 μg/ml proteinase K significantly inhibited biofilm development in bap-positive S. aureus V329 as well as other S. aureus isolates (SA7, SA10, SA33, SA352, but not in bap-mutant M556 and SA392 (a weak biofilm-producing strain. Proteinase K treatment on S. aureus planktonic cells showed that there was no inhibition of planktonic growth up to 32 μg/ml of proteinase K. Proteinase K treatment on 24 h old preformed biofilms showed an enhanced dispersion of bap-positive V329 and SA7, SA10, SA33 and SA352 biofilms; however, proteinase K did not affect the bap-mutant S. aureus M556 and SA392 biofilms. Biofilm compositions study before and after proteinase K treatment indicated that Bap might also be involved in eDNA retention in the biofilm matrix that aids in biofilm stability. When proteinase K was used in combination with antibiotics, a synergistic effect in antibiotic efficacy was observed against all biofilm-forming S. aureus isolates. Interpretation & conclusions: Proteinase K inhibited biofilms growth in S. aureus bovine mastitis isolates but did not affect their planktonic growth. An enhanced dispersion of preformed S. aureus biofilms was observed on proteinase K treatment. Proteinase K treatment with antibiotics showed a synergistic effect against S. aureus biofilms. The study suggests that dispersing S. aureus by protease can be of use while devising strategies againstS. aureus biofilms.

  4. Fremmedlegemeinfektioner--nyt om biofilm og quorum sensing

    DEFF Research Database (Denmark)

    Høiby, Niels; Johansen, Helle Krogh; Ciofu, Oana

    2007-01-01

    Biofilms are structured consortia of bacteria embedded in self-produced polymer matrix. Biofilms are resistant to antibiotics, disinfectives and phagocytosis. The persistence of foreign body infections is due to biofilms. Chronic P. aeruginosa lung infection in cystic fibrosis patients is a biofilm....... Bacteria in biofilms communicate by means of quorum sensing which activates genes for virulence factors. Biofilms can be prevented by antibiotic prophylaxis or early therapy or by quorum sensing inhibitors which make them susceptible to antibiotics and phagocytosis....

  5. Silver-Palladium Surfaces Inhibit Biofilm Formation

    DEFF Research Database (Denmark)

    Chiang, Wen-Chi; Schroll, Casper; Hilbert, Lisbeth Rischel

    2009-01-01

    Undesired biofilm formation is a major concern in many areas. In the present study, we investigated biofilm-inhibiting properties of a silver-palladium surface that kills bacteria by generating microelectric fields and electrochemical redox processes. For evaluation of the biofilm inhibition...... efficacy and study of the biofilm inhibition mechanism, the silver-sensitive Escherichia coli J53 and the silver-resistant E. coli J53[pMG101] strains were used as model organisms, and batch and flow chamber setups were used as model systems. In the case of the silver-sensitive strain, the silver......-palladium surfaces killed the bacteria and prevented biofilm formation under conditions of low or high bacterial load. In the case of the silver-resistant strain, the silver-palladium surfaces killed surface-associated bacteria and prevented biofilm formation under conditions of low bacterial load, whereas under...

  6. Mucosal biofilm detection in chronic otitis media

    DEFF Research Database (Denmark)

    Wessman, Marcus; Bjarnsholt, Thomas; Eickhardt-Sørensen, Steffen Robert

    2015-01-01

    The objectives of this study were to examine middle ear biopsies from Greenlandic patients with chronic otitis media (COM) for the presence of mucosal biofilms and the bacteria within the biofilms. Thirty-five middle ear biopsies were obtained from 32 Greenlandic COM patients admitted to ear...... of the patients served as controls. PNA-FISH showed morphological signs of biofilms in 15 out of 35 (43 %) middle ear biopsies. In the control skin biopsies, there were signs of biofilms in eight out of 23 biopsies (30 %), probably representing skin flora. PCR and 16s sequencing detected bacteria in seven out...... of 20 (35 %) usable middle ear biopsies, and in two out of ten (20 %) usable control samples. There was no association between biofilm findings and PCR and 16s sequencing. Staphylococci were the most common bacteria in bacterial culture. We found evidence of bacterial biofilms in 43 % of middle ear...

  7. Microbial biofilms: biosurfactants as antibiofilm agents.

    Science.gov (United States)

    Banat, Ibrahim M; De Rienzo, Mayri A Díaz; Quinn, Gerry A

    2014-12-01

    Current microbial inhibition strategies based on planktonic bacterial physiology have been known to have limited efficacy on the growth of biofilm communities. This problem can be exacerbated by the emergence of increasingly resistant clinical strains. All aspects of biofilm measurement, monitoring, dispersal, control, and inhibition are becoming issues of increasing importance. Biosurfactants have merited renewed interest in both clinical and hygienic sectors due to their potential to disperse microbial biofilms in addition to many other advantages. The dispersal properties of biosurfactants have been shown to rival those of conventional inhibitory agents against bacterial and yeast biofilms. This makes them suitable candidates for use in new generations of microbial dispersal agents and for use as adjuvants for existing microbial suppression or eradication strategies. In this review, we explore aspects of biofilm characteristics and examine the contribution of biologically derived surface-active agents (biosurfactants) to the disruption or inhibition of microbial biofilms.

  8. Biofilm inhibitors that target amyloid proteins.

    Science.gov (United States)

    Romero, Diego; Sanabria-Valentín, Edgardo; Vlamakis, Hera; Kolter, Roberto

    2013-01-24

    Bacteria establish stable communities, known as biofilms, that are resistant to antimicrobials. Biofilm robustness is due to the presence of an extracellular matrix, which for several species-among them Bacillus subtilis-includes amyloid-like protein fibers. In this work, we show that B. subtilis biofilms can be a simple and reliable tool for screening of molecules with antiamyloid activity. We identified two molecules, AA-861 and parthenolide, which efficiently inhibited biofilms by preventing the formation of amyloid-like fibers. Parthenolide also disrupted pre-established biofilms. These molecules also impeded the formation of biofilms of other bacterial species that secrete amyloid proteins, such as Bacillus cereus and Escherichia coli. Furthermore, the identified molecules decreased the conversion of the yeast protein New1 to the prion state in a heterologous host, indicating the broad range of activity of the molecules. Copyright © 2013 Elsevier Ltd. All rights reserved.

  9. [Biofilms and their significance in medical microbiology].

    Science.gov (United States)

    Cernohorská, L; Votava, M

    2002-11-01

    Microorganisms are able to adhere to various surfaces and to form there a three-dimensional structure known as biofilm. In biofilms, microbial cells show characteristics and behaviours different from those of plankton cells. Intercellular signalizations of the quorum-sensing type regulate interaction between members of the biofilm. Bacteria embedded in the biofilm can escape and form well known planktonic forms, that are obviously only a part of the bacterial life cycle. Bacteria adhere also to medically important surfaces such as catheters, either urinary or intravenous ones, artificial heart valves, orthopedic implants and so on and contribute to device-related infections like cystitis, catheter-related sepsis, endocarditis etc. Once a biofilm has been established on a surface, the bacteria harboured inside are less exposed to the host's immune response and less susceptible to antibiotics. As an important cause of nosocomial infections the biofilm must remain in the centre of the microbiologist's attention.

  10. Material modeling of biofilm mechanical properties.

    Science.gov (United States)

    Laspidou, C S; Spyrou, L A; Aravas, N; Rittmann, B E

    2014-05-01

    A biofilm material model and a procedure for numerical integration are developed in this article. They enable calculation of a composite Young's modulus that varies in the biofilm and evolves with deformation. The biofilm-material model makes it possible to introduce a modeling example, produced by the Unified Multi-Component Cellular Automaton model, into the general-purpose finite-element code ABAQUS. Compressive, tensile, and shear loads are imposed, and the way the biofilm mechanical properties evolve is assessed. Results show that the local values of Young's modulus increase under compressive loading, since compression results in the voids "closing," thus making the material stiffer. For the opposite reason, biofilm stiffness decreases when tensile loads are imposed. Furthermore, the biofilm is more compliant in shear than in compression or tension due to the how the elastic shear modulus relates to Young's modulus. Copyright © 2014 Elsevier Inc. All rights reserved.

  11. Changes in the subgingival biofilm composition after coronally positioned flap

    Directory of Open Access Journals (Sweden)

    Jadson Almeida Lima

    2011-02-01

    Full Text Available OBJECTIVES: This study evaluated the effects of coronally positioned flap (CPF on the subgingival biofilm composition. MATERIAL AND METHODS: Twenty-two subjects with gingival recessions were treated with CPF. Clinical parameters were assessed before and at 6 months after surgery. Subgingival biofilms were analyzed by checkerboard DNA-DNA hybridization technique for 40 bacterial species. RESULTS: Recession height, clinical attachment level and bleeding on probing improved significantly (p<0.05 at 6 months post-CPF. The proportions of 10 periodontal pathogens and the proportions of red and orange complexes decreased at 6 months. CONCLUSION: In conclusion, CPF can induce beneficial effects on the composition of the subgingival microbiota after 6 months.

  12. Exogenous fatty acid binding protein 4 promotes human prostate cancer cell progression.

    Science.gov (United States)

    Uehara, Hisanori; Takahashi, Tetsuyuki; Oha, Mina; Ogawa, Hirohisa; Izumi, Keisuke

    2014-12-01

    Epidemiologic studies have found that obesity is associated with malignant grade and mortality in prostate cancer. Several adipokines have been implicated as putative mediating factors between obesity and prostate cancer. Fatty acid binding protein 4 (FABP4), a member of the cytoplasmic fatty acid binding protein multigene family, was recently identified as a novel adipokine. Although FABP4 is released from adipocytes and mean circulating concentrations of FABP4 are linked with obesity, effects of exogenous FABP4 on prostate cancer progression are unclear. In this study, we examined the effects of exogenous FABP4 on human prostate cancer cell progression. FABP4 treatment promoted serum-induced prostate cancer cell invasion in vitro. Furthermore, oleic acid promoted prostate cancer cell invasion only if FABP4 was present in the medium. These promoting effects were reduced by FABP4 inhibitor, which inhibits FABP4 binding to fatty acids. Immunostaining for FABP4 showed that exogenous FABP4 was taken up into DU145 cells in three-dimensional culture. In mice, treatment with FABP4 inhibitor reduced the subcutaneous growth and lung metastasis of prostate cancer cells. Immunohistochemical analysis showed that the number of apoptotic cells, positive for cleaved caspase-3 and cleaved PARP, was increased in subcutaneous tumors of FABP4 inhibitor-treated mice, as compared with control mice. These results suggest that exogenous FABP4 might promote human prostate cancer cell progression by binding with fatty acids. Additionally, exogenous FABP4 activated the PI3K/Akt pathway, independently of binding to fatty acids. Thus, FABP4 might be a key molecule to understand the mechanisms underlying the obesity-prostate cancer progression link. © 2014 UICC.

  13. Respiratory syncytial virus infection enhances Pseudomonas aeruginosa biofilm growth through dysregulation of nutritional immunity.

    Science.gov (United States)

    Hendricks, Matthew R; Lashua, Lauren P; Fischer, Douglas K; Flitter, Becca A; Eichinger, Katherine M; Durbin, Joan E; Sarkar, Saumendra N; Coyne, Carolyn B; Empey, Kerry M; Bomberger, Jennifer M

    2016-02-09

    Clinical observations link respiratory virus infection and Pseudomonas aeruginosa colonization in chronic lung disease, including cystic fibrosis (CF) and chronic obstructive pulmonary disease. The development of P. aeruginosa into highly antibiotic-resistant biofilm communities promotes airway colonization and accounts for disease progression in patients. Although clinical studies show a strong correlation between CF patients' acquisition of chronic P. aeruginosa infections and respiratory virus infection, little is known about the mechanism by which chronic P. aeruginosa infections are initiated in the host. Using a coculture model to study the formation of bacterial biofilm formation associated with the airway epithelium, we show that respiratory viral infections and the induction of antiviral interferons promote robust secondary P. aeruginosa biofilm formation. We report that the induction of antiviral IFN signaling in response to respiratory syncytial virus (RSV) infection induces bacterial biofilm formation through a mechanism of dysregulated iron homeostasis of the airway epithelium. Moreover, increased apical release of the host iron-binding protein transferrin during RSV infection promotes P. aeruginosa biofilm development in vitro and in vivo. Thus, nutritional immunity pathways that are disrupted during respiratory viral infection create an environment that favors secondary bacterial infection and may provide previously unidentified targets to combat bacterial biofilm formation.

  14. Biofilm and capsule formation of the diatom Achnanthidium minutissimum are affected by a bacterium.

    Science.gov (United States)

    Windler, Miriam; Leinweber, Katrin; Bartulos, Carolina Rio; Philipp, Bodo; Kroth, Peter G

    2015-04-01

    Photoautotrophic biofilms play an important role in various aquatic habitats and are composed of prokaryotic and/or eukaryotic organisms embedded in extracellular polymeric substances (EPS). We have isolated diatoms as well as bacteria from freshwater biofilms to study organismal interactions between representative isolates. We found that bacteria have a strong impact on the biofilm formation of the pennate diatom Achnanthidium minutissimum. This alga produces extracellular capsules of insoluble EPS, mostly carbohydrates (CHO), only in the presence of bacteria (xenic culture). The EPS themselves also have a strong impact on the aggregation and attachment of the algae. In the absence of bacteria (axenic culture), A. minutissimum did not form capsules and the cells grew completely suspended. Fractionation and quantification of CHO revealed that the diatom in axenic culture produces large amounts of soluble CHO, whereas in the xenic culture mainly insoluble CHO were detected. For investigation of biofilm formation by A. minutissimum, a bioassay was established using a diatom satellite Bacteroidetes bacterium that had been shown to induce capsule formation of A. minutissimum. Interestingly, capsule and biofilm induction can be achieved by addition of bacterial spent medium, indicating that soluble hydrophobic molecules produced by the bacterium may mediate the diatom/bacteria interaction. With the designed bioassay, a reliable tool is now available to study the chemical interactions between diatoms and bacteria with consequences for biofilm formation. © 2015 Phycological Society of America.

  15. Functional genomic profiling of Aspergillus fumigatus biofilm reveals enhanced production of the mycotoxin gliotoxin.

    Science.gov (United States)

    Bruns, Sandra; Seidler, Marc; Albrecht, Daniela; Salvenmoser, Stefanie; Remme, Nicole; Hertweck, Christian; Brakhage, Axel A; Kniemeyer, Olaf; Müller, Frank-Michael C

    2010-09-01

    The opportunistic pathogenic mold Aspergillus fumigatus is an increasing cause of morbidity and mortality in immunocompromised and in part immunocompetent patients. A. fumigatus can grow in multicellular communities by the formation of a hyphal network encased in an extracellular matrix. Here, we describe the proteome and transcriptome of planktonic- and biofilm-grown A. fumigatus mycelium after 24 and 48 h. A biofilm- and time-dependent regulation of many proteins and genes of the primary metabolism indicates a developmental stage of the young biofilm at 24 h, which demands energy. At a matured biofilm phase, metabolic activity seems to be reduced. However, genes, which code for hydrophobins, and proteins involved in the biosynthesis of secondary metabolites were significantly upregulated. In particular, proteins of the gliotoxin secondary metabolite gene cluster were induced in biofilm cultures. This was confirmed by real-time PCR and by detection of this immunologically active mycotoxin in culture supernatants using HPLC analysis. The enhanced production of gliotoxin by in vitro formed biofilms reported here may also play a significant role under in vivo conditions. It may confer A. fumigatus protection from the host immune system and also enable its survival and persistence in chronic lung infections such as aspergilloma.

  16. Biofilm characteristics of Staphylococcus epidermidis isolates associated with device-related meningitis.

    LENUS (Irish Health Repository)

    Stevens, Niall T

    2009-07-01

    Staphylococcus epidermidis biofilm causes device-related meningitis in neurosurgical patients. This study assessed the contribution of polysaccharide and protein to the development of a strong biofilm-positive phenotype in four S. epidermidis isolates associated with probable device-related meningitis, under varying environmental conditions. RT-PCR analysis of the intercellular adhesion operon (icaADBC) and assessment of polysaccharide intercellular adhesin (PIA) production indicated a correlation between increased icaA transcription and PIA production in ica(+) isolates grown in medium with 4 % ethanol and 4 % NaCl. Treatment of biofilm with sodium metaperiodate caused dispersion of adhered cells (P <0.0001), indicating involvement of PIA. Transcriptional levels of protein factors revealed that atlE transcription levels were similar in all isolates, whilst aap levels were variable, with induction being seen in two isolates following growth in the presence of alcohol or salt. Transcription of agr did not influence protein expression and RNAIII transcription varied among the strains. Although aap transcription was induced, the treatment of biofilm with proteinase K did not always disperse the biofilm. Our data suggest that, among the three ica(+) S. epidermidis isolates clinically associated with meningitis that were studied, PIA contributed to the strong biofilm-positive phenotype, whereas protein factors appeared to have a secondary role.

  17. Shape of the growing front of biofilms

    Science.gov (United States)

    Wang, Xin; Stone, Howard A.; Golestanian, Ramin

    2017-12-01

    The spatial organization of bacteria in dense biofilms is key to their collective behaviour, and understanding it will be important for medical and technological applications. Here we study the morphology of a compact biofilm that undergoes unidirectional growth, and determine the condition for the stability of the growing interface as a function of the nutrient concentration and mechanical tension. Our study suggests that transient behaviour may play an important role in shaping the structure of a biofilm.

  18. Strategies for combating bacterial biofilm infections

    DEFF Research Database (Denmark)

    Wu, Hong; Moser, Claus Ernst; Wang, Heng-Zhuang

    2015-01-01

    Formation of biofilm is a survival strategy for bacteria and fungi to adapt to their living environment, especially in the hostile environment. Under the protection of biofilm, microbial cells in biofilm become tolerant and resistant to antibiotics and the immune responses, which increases the di.......International Journal of Oral Science advance online publication, 12 December 2014; doi:10.1038/ijos.2014.65....

  19. Effect of Lactoferrin on Oral Biofilm Formation

    Science.gov (United States)

    2009-10-01

    effect of Lf on the early stages of single-species and multi- species oral biofilm development. Streptococcus gordonii (Sg), Streptococcus mutans ...and biofilm development by Pseudomonas aeruginosa and Streptococcus mutans have been demonstrated, limited studies have been conducted on its effect...the effect of Lf on the early stages of single- species and multi-species oral biofilm development. Streptococcus gordonii, Streptococcus mutans

  20. Red and Green Fluorescence from Oral Biofilms.

    Science.gov (United States)

    Volgenant, Catherine M C; Hoogenkamp, Michel A; Krom, Bastiaan P; Janus, Marleen M; Ten Cate, Jacob M; de Soet, Johannes J; Crielaard, Wim; van der Veen, Monique H

    2016-01-01

    Red and green autofluorescence have been observed from dental plaque after excitation by blue light. It has been suggested that this red fluorescence is related to caries and the cariogenic potential of dental plaque. Recently, it was suggested that red fluorescence may be related to gingivitis. Little is known about green fluorescence from biofilms. Therefore, we assessed the dynamics of red and green fluorescence in real-time during biofilm formation. In addition, the fluorescence patterns of biofilm formed from saliva of eight different donors are described under simulated gingivitis and caries conditions. Biofilm formation was analysed for 12 hours under flow conditions in a microfluidic BioFlux flow system with high performance microscopy using a camera to allow live cell imaging. For fluorescence images dedicated excitation and emission filters were used. Both green and red fluorescence were linearly related with the total biomass of the biofilms. All biofilms displayed to some extent green and red fluorescence, with higher red and green fluorescence intensities from biofilms grown in the presence of serum (gingivitis simulation) as compared to the sucrose grown biofilms (cariogenic simulation). Remarkably, cocci with long chain lengths, presumably streptococci, were observed in the biofilms. Green and red fluorescence were not found homogeneously distributed within the biofilms: highly fluorescent spots (both green and red) were visible throughout the biomass. An increase in red fluorescence from the in vitro biofilms appeared to be related to the clinical inflammatory response of the respective saliva donors, which was previously assessed during an in vivo period of performing no-oral hygiene. The BioFlux model proved to be a reliable model to assess biofilm fluorescence. With this model, a prediction can be made whether a patient will be prone to the development of gingivitis or caries.

  1. Antibiotic tolerance and resistance in biofilms

    DEFF Research Database (Denmark)

    Ciofu, Oana; Tolker-Nielsen, Tim

    2010-01-01

    One of the most important features of microbial biofilms is their tolerance to antimicrobial agents and components of the host immune system. The difficulty of treating biofilm infections with antibiotics is a major clinical problem. Although antibiotics may decrease the number of bacteria...... in biofilms, they will not completely eradicate the bacteria in vivo which may have important clinical consequences in form of relapses of the infection....

  2. Red and Green Fluorescence from Oral Biofilms.

    Directory of Open Access Journals (Sweden)

    Catherine M C Volgenant

    Full Text Available Red and green autofluorescence have been observed from dental plaque after excitation by blue light. It has been suggested that this red fluorescence is related to caries and the cariogenic potential of dental plaque. Recently, it was suggested that red fluorescence may be related to gingivitis. Little is known about green fluorescence from biofilms. Therefore, we assessed the dynamics of red and green fluorescence in real-time during biofilm formation. In addition, the fluorescence patterns of biofilm formed from saliva of eight different donors are described under simulated gingivitis and caries conditions. Biofilm formation was analysed for 12 hours under flow conditions in a microfluidic BioFlux flow system with high performance microscopy using a camera to allow live cell imaging. For fluorescence images dedicated excitation and emission filters were used. Both green and red fluorescence were linearly related with the total biomass of the biofilms. All biofilms displayed to some extent green and red fluorescence, with higher red and green fluorescence intensities from biofilms grown in the presence of serum (gingivitis simulation as compared to the sucrose grown biofilms (cariogenic simulation. Remarkably, cocci with long chain lengths, presumably streptococci, were observed in the biofilms. Green and red fluorescence were not found homogeneously distributed within the biofilms: highly fluorescent spots (both green and red were visible throughout the biomass. An increase in red fluorescence from the in vitro biofilms appeared to be related to the clinical inflammatory response of the respective saliva donors, which was previously assessed during an in vivo period of performing no-oral hygiene. The BioFlux model proved to be a reliable model to assess biofilm fluorescence. With this model, a prediction can be made whether a patient will be prone to the development of gingivitis or caries.

  3. Red fluorescence of dental biofilm as an indicator for assessing the efficacy of antimicrobials

    Science.gov (United States)

    Lee, Eun-Song; de Josselin de Jong, Elbert; Jung, Hoi-In; Kim, Baek-Il

    2018-01-01

    The study aimed to determine whether the red fluorescence (RF) of a dental microcosm biofilm as measured with quantitative light-induced fluorescence (QLF) technology is useful for assessing the efficacy of antimicrobials. Dental microcosm biofilms were formed on bovine enamel discs and grown under 0.3% sucrose challenge and treated with chlorhexidine (CHX) solutions at different concentrations (0.05%, 0.1%, and 0.5%) plus a negative control [sterile distilled water (DW)] twice daily for 7 days. The biofilms were photographed using a QLF-digital system to evaluate the RF by calculating the red/green ratio, and pH values of the medium were measured daily. After 7 days, the bacterial viability of the biofilm was assessed by measuring the counts of viable total bacteria and aciduric bacteria, and the percentage surface microhardness changes (%SHC) was evaluated. The RF and cariogenic properties were compared for the different concentrations of CHX, and their correlations were examined. The RF and its increase rate were much lower for CHX-treated biofilms than for DW-treated biofilms. The RF after 7 days of maturation decreased significantly with increasing CHX concentrations (pbiofilms and cariogenic properties, such as the number of total bacteria (r=0.93), number of aciduric bacteria (r=0.97), supernatant pH (r=0.43), and %SHC (r=0.98). In conclusion, the RF of dental biofilms as measured with QLF technology can be used to nondestructively assess and monitor the effect of antimicrobials against biofilm.

  4. In vivo biofilm formation on stainless steel bonded retainers during different oral health-care regimens.

    Science.gov (United States)

    Jongsma, Marije A; van der Mei, Henny C; Atema-Smit, Jelly; Busscher, Henk J; Ren, Yijin

    2015-03-23

    Retention wires permanently bonded to the anterior teeth are used after orthodontic treatment to prevent the teeth from relapsing to pre-treatment positions. A disadvantage of bonded retainers is biofilm accumulation on the wires, which produces a higher incidence of gingival recession, increased pocket depth and bleeding on probing. This study compares in vivo biofilm formation on single-strand and multi-strand retention wires with different oral health-care regimens. Two-centimetre wires were placed in brackets that were bonded to the buccal side of the first molars and second premolars in the upper arches of 22 volunteers. Volunteers used a selected toothpaste with or without the additional use of a mouthrinse containing essential oils. Brushing was performed manually. Regimens were maintained for 1 week, after which the wires were removed and the oral biofilm was collected to quantify the number of organisms and their viability, determine the microbial composition and visualize the bacteria by electron microscopy. A 6-week washout period was employed between regimens. Biofilm formation was reduced on single-strand wires compared with multi-strand wires; bacteria were observed to adhere between the strands. The use of antibacterial toothpastes marginally reduced the amount of biofilm on both wire types, but significantly reduced the viability of the biofilm organisms. Additional use of the mouthrinse did not result in significant changes in biofilm amount or viability. However, major shifts in biofilm composition were induced by combining a stannous fluoride- or triclosan-containing toothpaste with the mouthrinse. These shifts can be tentatively attributed to small changes in bacterial cell surface hydrophobicity after the adsorption of the toothpaste components, which stimulate bacterial adhesion to the hydrophobic oil, as illustrated for a Streptococcus mutans strain.

  5. Thiazolidinedione-8 alters symbiotic relationship in C. albicans-S. mutans dual species biofilm

    Directory of Open Access Journals (Sweden)

    Mark eFeldman

    2016-02-01

    Full Text Available The small molecule, thiazolidinedione-8 (S-8 was shown to impair biofilm formation of various microbial pathogens, including the fungus Candida albicans and Streptococcus mutans. Previously, we have evaluated the specific molecular mode of S-8 action against C. albicans biofilm-associated pathogenicity. In this study we investigated the influence of S-8 on dual species, C. albicans-S. mutans biofilm. We show that in the presence of S-8 a reduction of the co-species biofilm formation occurred with a major effect on C. albicans. Biofilm biomass and exopolysaccharide (EPS production were significantly reduced by S-8. Moreover, the agent caused oxidative stress associated with a strong induction of reactive oxygen species (ROS and hydrogen peroxide uptake inhibition by a mixed biofilm. In addition, S-8 altered symbiotic relationship between these species by a complex mechanism. Streptococcal genes associated with quorum sensing (comDE and luxS, EPS production (gtfBCD and gbpB, as well as genes related to protection against oxidative stress (nox and sodA were markedly upregulated by S-8. In contrast, fungal genes related to hyphae formation (hwp1, adhesion (als3, hydrophobicity (csh1 and oxidative stress response (sod1, sod2 and cat1 were downregulated in the presence of S-8. In addition, ywp1 gene associated with yeast form of C. albicans was induced by S-8, which is correlated with appearance of mostly yeast cells in S-8 treated dual species biofilms. We concluded that S-8 disturbs symbiotic balance between C. albicans and S. mutans in dual species biofilm.

  6. AFM Structural Characterization of Drinking Water Biofilm ...

    Science.gov (United States)

    Due to the complexity of mixed culture drinking water biofilm, direct visual observation under in situ conditions has been challenging. In this study, atomic force microscopy (AFM) revealed the three dimensional morphology and arrangement of drinking water relevant biofilm in air and aqueous solution. Operating parameters were optimized to improve imaging of structural details for a mature biofilm in liquid. By using a soft cantilever (0.03 N/m) and slow scan rate (0.5 Hz), biofilm and individual bacterial cell’s structural topography were resolved and continuously imaged in liquid without loss of spatial resolution or sample damage. The developed methodology will allow future in situ investigations to temporally monitor mixed culture drinking water biofilm structural changes during disinfection treatments. Due to the complexity of mixed culture drinking water biofilm, direct visual observation under in situ conditions has been challenging. In this study, atomic force microscopy (AFM) revealed the three dimensional morphology and arrangement of drinking water relevant biofilm in air and aqueous solution. Operating parameters were optimized to improve imaging of structural details for a mature biofilm in liquid. By using a soft cantilever (0.03 N/m) and slow scan rate (0.5 Hz), biofilm and individual bacterial cell’s structural topography were resolved and continuously imaged in liquid without loss of spatial resolution or sample damage. The developed methodo

  7. Biofilm responses to marine fish farm wastes

    International Nuclear Information System (INIS)

    Sanz-Lazaro, Carlos; Navarrete-Mier, Francisco; Marin, Arnaldo

    2011-01-01

    The changes in the biofilm community due to organic matter enrichment, eutrophication and metal contamination derived from fish farming were studied. The biofilm biomass, polysaccharide content, trophic niche and element accumulation were quantified along an environmental gradient of fish farm wastes in two seasons. Biofilm structure and trophic diversity was influenced by seasonality as well as by the fish farm waste load. Fish farming enhanced the accumulation of organic carbon, nutrients, selenium and metals by the biofilm community. The accumulation pattern of these elements was similar regardless of the structure and trophic niche of the community. This suggests that the biofilm communities can be considered a reliable tool for assessing dissolved aquaculture wastes. Due to the ubiquity of biofilms and its wide range of consumers, its role as a sink of dissolved wastes may have important implications for the transfer of aquaculture wastes to higher trophic levels in coastal systems. - Research highlights: → Biofilms can act as a trophic pathway of fish farm dissolved wastes. → Biofilms are reliable tools for monitoring fish farm dissolved wastes. → The influence of the fish farm dissolved wastes can be detected 120-350 m from farm. - Under the influence of fish farming biofilm accumulates organic carbon, nutrients, selenium and metals, regardless of the structure and trophic niche of the community.

  8. Focus on the physics of biofilms

    International Nuclear Information System (INIS)

    Lecuyer, Sigolene; Stocker, Roman; Rusconi, Roberto

    2015-01-01

    Bacteria are the smallest and most abundant form of life. They have traditionally been considered as primarily planktonic organisms, swimming or floating in a liquid medium, and this view has shaped many of the approaches to microbial processes, including for example the design of most antibiotics. However, over the last few decades it has become clear that many bacteria often adopt a sessile, surface-associated lifestyle, forming complex multicellular communities called biofilms. Bacterial biofilms are found in a vast range of environments and have major consequences on human health and industrial processes, from biofouling of surfaces to the spread of diseases. Although the study of biofilms has been biologists’ territory for a long time, a multitude of phenomena in the formation and development of biofilms hinges on physical processes. We are pleased to present a collection of research papers that discuss some of the latest developments in many of the areas to which physicists can contribute a deeper understanding of biofilms, both experimentally and theoretically. The topics covered range from the influence of physical environmental parameters on cell attachment and subsequent biofilm growth, to the use of local probes and imaging techniques to investigate biofilm structure, to the development of biofilms in complex environments and the modeling of colony morphogenesis. The results presented contribute to addressing some of the major challenges in microbiology today, including the prevention of surface contamination, the optimization of biofilm disruption methods and the effectiveness of antibiotic treatments. (editorial)

  9. Electroactive biofilms of sulphate reducing bacteria

    International Nuclear Information System (INIS)

    Cordas, Cristina M.; Guerra, L. Tiago; Xavier, Catarina; Moura, Jose J.G.

    2008-01-01

    Biofilms formed from a pure strain of Desulfovibrio desulfuricans 27774 on stainless steel and graphite polarised surfaces were studied. The polarisation conditions applied were -0.4 V vs. SCE for different times. A cathodic current related with the biofilms growth was observed with a maximum intensity of -270 mA m -2 that remained stable for several days using graphite electrodes. These sulphate reducing bacteria biofilms present electrocatalytic activity towards hydrogen and oxygen reduction reactions. Electrode polarisation has a selective effect on the catalytic activity. The biofilms were also observed by scanning electronic microscopy revealing the formation of homogeneous films on the surfaces

  10. Aspartate inhibits Staphylococcus aureus biofilm formation.

    Science.gov (United States)

    Yang, Hang; Wang, Mengyue; Yu, Junping; Wei, Hongping

    2015-04-01

    Biofilm formation renders Staphylococcus aureus highly resistant to conventional antibiotics and host defenses. Four D-amino acids (D-Leu, D-Met, D-Trp and D-Tyr) have been reported to be able to inhibit biofilm formation and disassemble established S. aureus biofilms. We report here for the first time that both D- and L-isoforms of aspartate (Asp) inhibited S. aureus biofilm formation on tissue culture plates. Similar biofilm inhibition effects were also observed against other staphylococcal strains, including S. saprophyticus, S. equorum, S. chromogenes and S. haemolyticus. It was found that Asp at high concentrations (>10 mM) inhibited the growth of planktonic N315 cells, but at subinhibitory concentrations decreased the cellular metabolic activity without influencing cell growth. The decreased cellular metabolic activity might be the reason for the production of less protein and DNA in the matrix of the biofilms formed in the presence of Asp. However, varied inhibition efficacies of Asp were observed for biofilms formed by clinical staphylococcal isolates. There might be mechanisms other than decreasing the metabolic activity, e.g. the biofilm phenotypes, affecting biofilm formation in the presence of Asp. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  11. Mechanisms of Candida biofilm drug resistance

    Science.gov (United States)

    Taff, Heather T; Mitchell, Kaitlin F; Edward, Jessica A; Andes, David R

    2013-01-01

    Candida commonly adheres to implanted medical devices, growing as a resilient biofilm capable of withstanding extraordinarily high antifungal concentrations. As currently available antifungals have minimal activity against biofilms, new drugs to treat these recalcitrant infections are urgently needed. Recent investigations have begun to shed light on the mechanisms behind the profound resistance associated with the biofilm mode of growth. This resistance appears to be multifactorial, involving both mechanisms similar to conventional, planktonic antifungal resistance, such as increased efflux pump activity, as well as mechanisms specific to the biofilm lifestyle. A unique biofilm property is the production of an extracellular matrix. Two components of this material, β-glucan and extracellular DNA, promote biofilm resistance to multiple antifungals. Biofilm formation also engages several stress response pathways that impair the activity of azole drugs. Resistance within a biofilm is often heterogeneous, with the development of a subpopulation of resistant persister cells. In this article we review the molecular mechanisms underlying Candida biofilm antifungal resistance and their relative contributions during various growth phases. PMID:24059922

  12. Candida Biofilms: Threats, Challenges, and Promising Strategies

    Science.gov (United States)

    Cavalheiro, Mafalda; Teixeira, Miguel Cacho

    2018-01-01

    Candida species are fungal pathogens known for their ability to cause superficial and systemic infections in the human host. These pathogens are able to persist inside the host due to the development of pathogenicity and multidrug resistance traits, often leading to the failure of therapeutic strategies. One specific feature of Candida species pathogenicity is their ability to form biofilms, which protects them from external factors such as host immune system defenses and antifungal drugs. This review focuses on the current threats and challenges when dealing with biofilms formed by Candida albicans, Candida glabrata, Candida tropicalis, and Candida parapsilosis, highlighting the differences between the four species. Biofilm characteristics depend on the ability of each species to produce extracellular polymeric substances (EPS) and display dimorphic growth, but also on the biofilm substratum, carbon source availability and other factors. Additionally, the transcriptional control over processes like adhesion, biofilm formation, filamentation, and EPS production displays great complexity and diversity within pathogenic yeasts of the Candida genus. These differences not only have implications in the persistence of colonization and infections but also on antifungal resistance typically found in Candida biofilm cells, potentiated by EPS, that functions as a barrier to drug diffusion, and by the overexpression of drug resistance transporters. The ability to interact with different species in in vivo Candida biofilms is also a key factor to consider when dealing with this problem. Despite many challenges, the most promising strategies that are currently available or under development to limit biofilm formation or to eradicate mature biofilms are discussed. PMID:29487851

  13. Biofilm responses to marine fish farm wastes

    Energy Technology Data Exchange (ETDEWEB)

    Sanz-Lazaro, Carlos, E-mail: carsanz@um.es [Departamento de Ecologia e Hidrologia, Facultad de Biologia, Universidad de Murcia, 30100 Murcia (Spain); Navarrete-Mier, Francisco; Marin, Arnaldo [Departamento de Ecologia e Hidrologia, Facultad de Biologia, Universidad de Murcia, 30100 Murcia (Spain)

    2011-03-15

    The changes in the biofilm community due to organic matter enrichment, eutrophication and metal contamination derived from fish farming were studied. The biofilm biomass, polysaccharide content, trophic niche and element accumulation were quantified along an environmental gradient of fish farm wastes in two seasons. Biofilm structure and trophic diversity was influenced by seasonality as well as by the fish farm waste load. Fish farming enhanced the accumulation of organic carbon, nutrients, selenium and metals by the biofilm community. The accumulation pattern of these elements was similar regardless of the structure and trophic niche of the community. This suggests that the biofilm communities can be considered a reliable tool for assessing dissolved aquaculture wastes. Due to the ubiquity of biofilms and its wide range of consumers, its role as a sink of dissolved wastes may have important implications for the transfer of aquaculture wastes to higher trophic levels in coastal systems. - Research highlights: > Biofilms can act as a trophic pathway of fish farm dissolved wastes. > Biofilms are reliable tools for monitoring fish farm dissolved wastes. > The influence of the fish farm dissolved wastes can be detected 120-350 m from farm. - Under the influence of fish farming biofilm accumulates organic carbon, nutrients, selenium and metals, regardless of the structure and trophic niche of the community.

  14. Electroactive biofilms of sulphate reducing bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Cordas, Cristina M.; Guerra, L. Tiago; Xavier, Catarina [Requimte-CQFB, Departamento de Quimica, Faculdade de Ciencias e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Moura, Jose J.G. [Requimte-CQFB, Departamento de Quimica, Faculdade de Ciencias e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal)], E-mail: jose.moura@dq.fct.unl.pt

    2008-12-01

    Biofilms formed from a pure strain of Desulfovibrio desulfuricans 27774 on stainless steel and graphite polarised surfaces were studied. The polarisation conditions applied were -0.4 V vs. SCE for different times. A cathodic current related with the biofilms growth was observed with a maximum intensity of -270 mA m{sup -2} that remained stable for several days using graphite electrodes. These sulphate reducing bacteria biofilms present electrocatalytic activity towards hydrogen and oxygen reduction reactions. Electrode polarisation has a selective effect on the catalytic activity. The biofilms were also observed by scanning electronic microscopy revealing the formation of homogeneous films on the surfaces.

  15. Candida Biofilms: Threats, Challenges, and Promising Strategies.

    Science.gov (United States)

    Cavalheiro, Mafalda; Teixeira, Miguel Cacho

    2018-01-01

    Candida species are fungal pathogens known for their ability to cause superficial and systemic infections in the human host. These pathogens are able to persist inside the host due to the development of pathogenicity and multidrug resistance traits, often leading to the failure of therapeutic strategies. One specific feature of Candida species pathogenicity is their ability to form biofilms, which protects them from external factors such as host immune system defenses and antifungal drugs. This review focuses on the current threats and challenges when dealing with biofilms formed by Candida albicans, Candida glabrata, Candida tropicalis , and Candida parapsilosis , highlighting the differences between the four species. Biofilm characteristics depend on the ability of each species to produce extracellular polymeric substances (EPS) and display dimorphic growth, but also on the biofilm substratum, carbon source availability and other factors. Additionally, the transcriptional control over processes like adhesion, biofilm formation, filamentation, and EPS production displays great complexity and diversity within pathogenic yeasts of the Candida genus. These differences not only have implications in the persistence of colonization and infections but also on antifungal resistance typically found in Candida biofilm cells, potentiated by EPS, that functions as a barrier to drug diffusion, and by the overexpression of drug resistance transporters. The ability to interact with different species in in vivo Candida biofilms is also a key factor to consider when dealing with this problem. Despite many challenges, the most promising strategies that are currently available or under development to limit biofilm formation or to eradicate mature biofilms are discussed.

  16. Targeting quorum sensing in Pseudomonas aeruginosa biofilms

    DEFF Research Database (Denmark)

    Jakobsen, Tim Holm; Bjarnsholt, Thomas; Jensen, Peter Østrup

    2013-01-01

    Bacterial resistance to conventional antibiotics combined with an increasing acknowledgement of the role of biofilms in chronic infections has led to a growing interest in new antimicrobial strategies that target the biofilm mode of growth. In the aggregated biofilm mode, cell-to-cell communication...... alternative antibacterial strategies. Here, we review state of the art research of quorum sensing inhibitors against the opportunistic human pathogen Pseudomonas aeruginosa, which is found in a number of biofilm-associated infections and identified as the predominant organism infecting the lungs of cystic...

  17. Inhibitory effects of ZnO nanoparticles on aerobic wastewater biofilms from oxygen concentration profiles determined by microelectrodes

    International Nuclear Information System (INIS)

    Hou, Jun; Miao, Lingzhan; Wang, Chao; Wang, Peifang; Ao, Yanhui; Qian, Jin; Dai, Shanshan

    2014-01-01

    Highlights: • Temporal and spatial inhibitory effects of ZnO NPs on biofilms were investigated. • 50 mg/L nano-ZnO inhibited the microbial activities only in biofilm outer layer. • Adsorbed ZnO NPs had no adverse effects on the cell membrane integrity of biofilms. • Dissolution of ZnO NPs to toxic zinc ions was the main mechanism of toxicity. - Abstract: The presence of ZnO NPs in waste streams can negatively affect the efficiency of biological nutrient removal from wastewater. However, details of the toxic effects of ZnO NPs on microbial activities of wastewater biofilms have not yet been reported. In this study, the temporal and spatial inhibitory effects of ZnO NPs on the O 2 respiration activities of aerobic wastewater biofilms were investigated using an O 2 microelectrode. The resulting time–course microelectrode measurements demonstrated that ZnO NPs inhibited O 2 respiration within 2 h. The spatial distributions of net specific O 2 respiration were determined in biofilms with and without treatment of 5 or 50 mg/L ZnO NPs. The results showed that 50 mg/L of nano-ZnO inhibited the microbial activities only in the outer layer (∼200 μm) of the biofilms, and bacteria present in the deeper parts of the biofilms became even more active. Scanning electron microscopy (SEM) analysis showed that the ZnO NPs were adsorbed onto the biofilm, but these NPs had no adverse effects on the cell membrane integrity of the biofilms. It was found that the inhibition of O 2 respiration induced by higher concentrations of ZnO NPs (50 mg/L) was mainly due to the release of zinc ions by dissolution of the ZnO NPs

  18. Inhibitory effects of ZnO nanoparticles on aerobic wastewater biofilms from oxygen concentration profiles determined by microelectrodes

    Energy Technology Data Exchange (ETDEWEB)

    Hou, Jun [Key Laboratory of Integrated Regulation and Resources Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing 210098 (China); College of Environment, Hohai University, Nanjing 210098 (China); Miao, Lingzhan, E-mail: mlz1988@126.com [Key Laboratory of Integrated Regulation and Resources Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing 210098 (China); College of Environment, Hohai University, Nanjing 210098 (China); Wang, Chao, E-mail: hhuhjy973@126.com [Key Laboratory of Integrated Regulation and Resources Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing 210098 (China); College of Environment, Hohai University, Nanjing 210098 (China); Wang, Peifang; Ao, Yanhui; Qian, Jin; Dai, Shanshan [Key Laboratory of Integrated Regulation and Resources Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing 210098 (China); College of Environment, Hohai University, Nanjing 210098 (China)

    2014-07-15

    Highlights: • Temporal and spatial inhibitory effects of ZnO NPs on biofilms were investigated. • 50 mg/L nano-ZnO inhibited the microbial activities only in biofilm outer layer. • Adsorbed ZnO NPs had no adverse effects on the cell membrane integrity of biofilms. • Dissolution of ZnO NPs to toxic zinc ions was the main mechanism of toxicity. - Abstract: The presence of ZnO NPs in waste streams can negatively affect the efficiency of biological nutrient removal from wastewater. However, details of the toxic effects of ZnO NPs on microbial activities of wastewater biofilms have not yet been reported. In this study, the temporal and spatial inhibitory effects of ZnO NPs on the O{sub 2} respiration activities of aerobic wastewater biofilms were investigated using an O{sub 2} microelectrode. The resulting time–course microelectrode measurements demonstrated that ZnO NPs inhibited O{sub 2} respiration within 2 h. The spatial distributions of net specific O{sub 2} respiration were determined in biofilms with and without treatment of 5 or 50 mg/L ZnO NPs. The results showed that 50 mg/L of nano-ZnO inhibited the microbial activities only in the outer layer (∼200 μm) of the biofilms, and bacteria present in the deeper parts of the biofilms became even more active. Scanning electron microscopy (SEM) analysis showed that the ZnO NPs were adsorbed onto the biofilm, but these NPs had no adverse effects on the cell membrane integrity of the biofilms. It was found that the inhibition of O{sub 2} respiration induced by higher concentrations of ZnO NPs (50 mg/L) was mainly due to the release of zinc ions by dissolution of the ZnO NPs.

  19. Microbial pathogenesis and biofilm development

    DEFF Research Database (Denmark)

    Reisner, A.; Høiby, N.; Tolker-Nielsen, Tim

    2004-01-01

    been termed 'maturation', which is thought to be mediated by a differentiation process. Maturation into late stages of biofilm development resulting in stable and robust structures may require the formation of a matrix of extracellular polymeric substances (EPS), which are most often assumed to consist...... a highly significant role in connection with chronic infections [1]. Bacterial growth on surfaces depends on several factors [2]. In nature, surfaces are probably often conditioned with a thin film of organic molecules, which may serve as attractants for bacterial chemotactic systems and which subsequently...... permit bacterial growth to occur. In laboratory model systems the growth of the surface-associated bacteria is supported by the nutrient supply in the moving or standing liquid. A benchmark of biofilm formation by several organisms in vitro is the development of three-dimensional structures that have...

  20. Effects of exogenous glucagon-like peptide-2 and distal bowel resection on intestinal and systemic adaptive responses in rats.

    Science.gov (United States)

    Lai, Sarah W; de Heuvel, Elaine; Wallace, Laurie E; Hartmann, Bolette; Holst, Jens J; Brindle, Mary E; Chelikani, Prasanth K; Sigalet, David L

    2017-01-01

    To determine the effects of exogenous glucagon-like peptide-2 (GLP-2), with or without massive distal bowel resection, on adaptation of jejunal mucosa, enteric neurons, gut hormones and tissue reserves in rats. GLP-2 is a gut hormone known to be trophic for small bowel mucosa, and to mimic intestinal adaptation in short bowel syndrome (SBS). However, the effects of exogenous GLP-2 and SBS on enteric neurons are unclear. Sprague Dawley rats were randomized to four treatments: Transected Bowel (TB) (n = 8), TB + GLP-2 (2.5 nmol/kg/h, n = 8), SBS (n = 5), or SBS + GLP-2 (2.5 nmol/kg/h, n = 9). SBS groups underwent a 60% jejunoileal resection with cecectomy and jejunocolic anastomosis. All rats were maintained on parenteral nutrition for 7 d. Parameters measured included gut morphometry, qPCR for hexose transporter (SGLT-1, GLUT-2, GLUT-5) and GLP-2 receptor mRNA, whole mount immunohistochemistry for neurons (HuC/D, VIP, nNOS), plasma glucose, gut hormones, and body composition. Resection increased the proportion of nNOS immunopositive myenteric neurons, intestinal muscularis propria thickness and crypt cell proliferation, which were not recapitulated by GLP-2 therapy. Exogenous GLP-2 increased jejunal mucosal surface area without affecting enteric VIP or nNOS neuronal immunopositivity, attenuated resection-induced reductions in jejunal hexose transporter abundance (SGLT-1, GLUT-2), increased plasma amylin and decreased peptide YY concentrations. Exogenous GLP-2 attenuated resection-induced increases in blood glucose and body fat loss. Exogenous GLP-2 stimulates jejunal adaptation independent of enteric neuronal VIP or nNOS changes, and has divergent effects on plasma amylin and peptide YY concentrations. The novel ability of exogenous GLP-2 to modulate resection-induced changes in peripheral glucose and lipid reserves may be important in understanding the whole-body response following intestinal resection, and is worthy of further study.

  1. Effects of exogenous glucagon-like peptide-2 and distal bowel resection on intestinal and systemic adaptive responses in rats.

    Directory of Open Access Journals (Sweden)

    Sarah W Lai

    Full Text Available To determine the effects of exogenous glucagon-like peptide-2 (GLP-2, with or without massive distal bowel resection, on adaptation of jejunal mucosa, enteric neurons, gut hormones and tissue reserves in rats.GLP-2 is a gut hormone known to be trophic for small bowel mucosa, and to mimic intestinal adaptation in short bowel syndrome (SBS. However, the effects of exogenous GLP-2 and SBS on enteric neurons are unclear.Sprague Dawley rats were randomized to four treatments: Transected Bowel (TB (n = 8, TB + GLP-2 (2.5 nmol/kg/h, n = 8, SBS (n = 5, or SBS + GLP-2 (2.5 nmol/kg/h, n = 9. SBS groups underwent a 60% jejunoileal resection with cecectomy and jejunocolic anastomosis. All rats were maintained on parenteral nutrition for 7 d. Parameters measured included gut morphometry, qPCR for hexose transporter (SGLT-1, GLUT-2, GLUT-5 and GLP-2 receptor mRNA, whole mount immunohistochemistry for neurons (HuC/D, VIP, nNOS, plasma glucose, gut hormones, and body composition.Resection increased the proportion of nNOS immunopositive myenteric neurons, intestinal muscularis propria thickness and crypt cell proliferation, which were not recapitulated by GLP-2 therapy. Exogenous GLP-2 increased jejunal mucosal surface area without affecting enteric VIP or nNOS neuronal immunopositivity, attenuated resection-induced reductions in jejunal hexose transporter abundance (SGLT-1, GLUT-2, increased plasma amylin and decreased peptide YY concentrations. Exogenous GLP-2 attenuated resection-induced increases in blood glucose and body fat loss.Exogenous GLP-2 stimulates jejunal adaptation independent of enteric neuronal VIP or nNOS changes, and has divergent effects on plasma amylin and peptide YY concentrations. The novel ability of exogenous GLP-2 to modulate resection-induced changes in peripheral glucose and lipid reserves may be important in understanding the whole-body response following intestinal resection, and is worthy of further study.

  2. Effects of exogenous glucagon-like peptide-2 and distal bowel resection on intestinal and systemic adaptive responses in rats

    Science.gov (United States)

    de Heuvel, Elaine; Wallace, Laurie E.; Hartmann, Bolette; Holst, Jens J.; Brindle, Mary E.; Chelikani, Prasanth K.; Sigalet, David L.

    2017-01-01

    Objective To determine the effects of exogenous glucagon-like peptide-2 (GLP-2), with or without massive distal bowel resection, on adaptation of jejunal mucosa, enteric neurons, gut hormones and tissue reserves in rats. Background GLP-2 is a gut hormone known to be trophic for small bowel mucosa, and to mimic intestinal adaptation in short bowel syndrome (SBS). However, the effects of exogenous GLP-2 and SBS on enteric neurons are unclear. Methods Sprague Dawley rats were randomized to four treatments: Transected Bowel (TB) (n = 8), TB + GLP-2 (2.5 nmol/kg/h, n = 8), SBS (n = 5), or SBS + GLP-2 (2.5 nmol/kg/h, n = 9). SBS groups underwent a 60% jejunoileal resection with cecectomy and jejunocolic anastomosis. All rats were maintained on parenteral nutrition for 7 d. Parameters measured included gut morphometry, qPCR for hexose transporter (SGLT-1, GLUT-2, GLUT-5) and GLP-2 receptor mRNA, whole mount immunohistochemistry for neurons (HuC/D, VIP, nNOS), plasma glucose, gut hormones, and body composition. Results Resection increased the proportion of nNOS immunopositive myenteric neurons, intestinal muscularis propria thickness and crypt cell proliferation, which were not recapitulated by GLP-2 therapy. Exogenous GLP-2 increased jejunal mucosal surface area without affecting enteric VIP or nNOS neuronal immunopositivity, attenuated resection-induced reductions in jejunal hexose transporter abundance (SGLT-1, GLUT-2), increased plasma amylin and decreased peptide YY concentrations. Exogenous GLP-2 attenuated resection-induced increases in blood glucose and body fat loss. Conclusions Exogenous GLP-2 stimulates jejunal adaptation independent of enteric neuronal VIP or nNOS changes, and has divergent effects on plasma amylin and peptide YY concentrations. The novel ability of exogenous GLP-2 to modulate resection-induced changes in peripheral glucose and lipid reserves may be important in understanding the whole-body response following intestinal resection, and is worthy

  3. The N-Terminus of Human Lactoferrin Displays Anti-biofilm Activity on Candida parapsilosis in Lumen Catheters.

    Science.gov (United States)

    Fais, Roberta; Di Luca, Mariagrazia; Rizzato, Cosmeri; Morici, Paola; Bottai, Daria; Tavanti, Arianna; Lupetti, Antonella

    2017-01-01

    Candida parapsilosis is a major cause of hospital-acquired infection, often related to parenteral nutrition administered via catheters and hand colonization of health care workers, and its peculiar biofilm formation ability on plastic surfaces. The mortality rate of 30% points to the pressing need for new antifungal drugs. The present study aimed at analyzing the inhibitory activity of the N-terminal lactoferrin-derived peptide, further referred to as hLF 1-11, against biofilms produced by clinical isolates of C. parapsilosis characterized for their biofilm forming ability and fluconazole susceptibility. hLF 1-11 anti-biofilm activity was assessed in terms of reduction of biofilm biomass, metabolic activity, and observation of sessile cell morphology on polystyrene microtiter plates and using an in vitro model of catheter-associated C. parapsilosis biofilm production. Moreover, fluctuation in transcription levels of genes related to cell adhesion, hyphal development and extracellular matrix production upon peptide exposure were evaluated by quantitative real time RT-PCR. The results revealed that hLF 1-11 exhibits an inhibitory effect on biofilm formation by all the C. parapsilosis isolates tested, in a dose-dependent manner, regardless of their fluconazole susceptibility. In addition, hLF 1-11 induced a statistically significant dose-dependent reduction of preformed-biofilm cellular density and metabolic activity at high peptide concentrations only. Interestingly, when assessed in a catheter lumen, hLF 1-11 was able to induce a 2-log reduction of sessile cell viability at both the peptide concentrations used in RPMI diluted in NaPB. A more pronounced anti-biofilm effect was observed (3.5-log reduction) when a 10% glucose solution was used as experimental condition on both early and preformed C. parapsilosis biofilm. Quantitative real time RT-PCR experiments confirmed that hLF 1-11 down-regulates key biofilm related genes. The overall findings suggest hLF 1-11 as a

  4. Imaging biofilm in porous media using X-ray computed microtomography.

    Science.gov (United States)

    Davit, Y; Iltis, G; Debenest, G; Veran-Tissoires, S; Wildenschild, D; Gerino, M; Quintard, M

    2011-04-01

    In this study, a new technique for three-dimensional imaging of biofilm within porous media using X-ray computed microtomography is presented. Due to the similarity in X-ray absorption coefficients for the porous media (plastic), biofilm and aqueous phase, an X-ray contrast agent is required to image biofilm within the experimental matrix using X-ray computed tomography. The presented technique utilizes a medical suspension of barium sulphate to differentiate between the aqueous phase and the biofilm. Potassium iodide is added to the suspension to aid in delineation between the biofilm and the experimental porous medium. The iodide readily diffuses into the biofilm while the barium sulphate suspension remains in the aqueous phase. This allows for effective differentiation of the three phases within the experimental systems utilized in this study. The behaviour of the two contrast agents, in particular of the barium sulphate, is addressed by comparing two-dimensional images of biofilm within a pore network obtained by (1) optical visualization and (2) X-ray absorption radiography. We show that the contrast mixture provides contrast between the biofilm, the aqueous-phase and the solid-phase (beads). The imaging method is then applied to two three-dimensional packed-bead columns within which biofilm was grown. Examples of reconstructed images are provided to illustrate the effectiveness of the method. Limitations and applications of the technique are discussed. A key benefit, associated with the presented method, is that it captures a substantial amount of information regarding the topology of the pore-scale transport processes. For example, the quantification of changes in porous media effective parameters, such as dispersion or permeability, induced by biofilm growth, is possible using specific upscaling techniques and numerical analysis. We emphasize that the results presented here serve as a first test of this novel approach; issues with accurate segmentation of

  5. Comprehensive RNA-Seq Analysis on the Regulation of Tomato Ripening by Exogenous Auxin.

    Directory of Open Access Journals (Sweden)

    Jiayin Li

    Full Text Available Auxin has been shown to modulate the fruit ripening process. However, the molecular mechanisms underlying auxin regulation of fruit ripening are still not clear. Illumina RNA sequencing was performed on mature green cherry tomato fruit 1 and 7 days after auxin treatment, with untreated fruit as a control. The results showed that exogenous auxin maintained system 1 ethylene synthesis and delayed the onset of system 2 ethylene synthesis and the ripening process. At the molecular level, genes associated with stress resistance were significantly up-regulated, but genes related to carotenoid metabolism, cell degradation and energy metabolism were strongly down-regulated by exogenous auxin. Furthermore, genes encoding DNA demethylases were inhibited by auxin, whereas genes encoding cytosine-5 DNA methyltransferases were induced, which contributed to the maintenance of high methylation levels in the nucleus and thus inhibited the ripening process. Additionally, exogenous auxin altered the expression patterns of ethylene and auxin signaling-related genes that were induced or repressed in the normal ripening process, suggesting significant crosstalk between these two hormones during tomato ripening. The present work is the first comprehensive transcriptome analysis of auxin-treated tomato fruit during ripening. Our results provide comprehensive insights into the effects of auxin on the tomato ripening process and the mechanism of crosstalk between auxin and ethylene.

  6. Molecular methods for biofilms

    KAUST Repository

    Ferrera, Isabel; Balagué , Vanessa; Voolstra, Christian R.; Aranda, Manuel; Bayer, Till; Abed, Raeid M.M.; Dobretsov, Sergey; Owens, Sarah M.; Wilkening, Jared; Fessler, Jennifer L.; Gilbert, Jack A.

    2014-01-01

    at the same time and to compare bacterial communities among different samples or in a single sample after certain treatments. DGGE, T-RFLP and ARISA share similar steps but require different materials and equipment. The three methods involve (i) sampling of the biofilms; (ii) DNA extraction and quantification; and (iii) PCR using specific primers. Metagenomics: This chapter focuses classical and next-generation metagenomics methods. These are limited to bacterial artificial chromosome (BAC) and Fosmid libraries and Sanger and next-generation 454 sequencing, as these methods are currently the most frequently used in research. The chapter discusses the special handling of deoxyribonucleic acid (DNA) needed to construct BAC and Fosmid libraries from marine water samples. It also briefly addresses the related topics of library archiving, databasing, and screening. The chapter provides a high-level overview of the special handling methods required to prepare DNA for BAC library construction. No special handling is needed for Fosmid library construction.

  7. Molecular methods for biofilms

    KAUST Repository

    Ferrera, Isabel

    2014-08-30

    at the same time and to compare bacterial communities among different samples or in a single sample after certain treatments. DGGE, T-RFLP and ARISA share similar steps but require different materials and equipment. The three methods involve (i) sampling of the biofilms; (ii) DNA extraction and quantification; and (iii) PCR using specific primers. Metagenomics: This chapter focuses classical and next-generation metagenomics methods. These are limited to bacterial artificial chromosome (BAC) and Fosmid libraries and Sanger and next-generation 454 sequencing, as these methods are currently the most frequently used in research. The chapter discusses the special handling of deoxyribonucleic acid (DNA) needed to construct BAC and Fosmid libraries from marine water samples. It also briefly addresses the related topics of library archiving, databasing, and screening. The chapter provides a high-level overview of the special handling methods required to prepare DNA for BAC library construction. No special handling is needed for Fosmid library construction.

  8. CENTRAL SEROUS CHORIORETINOPATHY IN POSTMENOPAUSAL WOMEN RECEIVING EXOGENOUS TESTOSTERONE.

    Science.gov (United States)

    Conway, Mandi D; Noble, Jason A; Peyman, Gholam A

    2017-01-01

    Central serous chorioretinopathy (CSR) is a serous detachment of the neurosensory retina commonly associated with male sex, Type-A personality and corticosteroid use. Exogenous administration of androgens and development of CSR in men has been reported. Only one case of CSR in a postmenopausal woman receiving exogenous androgen therapy has been reported. The authors describe three cases of chronic CSR in postmenopausal women receiving exogenous testosterone therapy. Diagnosis was based on characteristic clinical, fluorescein angiographic, and optical coherence tomography findings. The three women were being treated with exogenous testosterone and progesterone therapy for symptoms of menopause and libido loss. Average age at presentation was 54.7 years (53-56 years), average duration of exogenous androgen use was 61 months (36-87 months), with average 19.7-month follow-up. Resolution of symptoms seemed correlated with cessation of androgen use despite treatment with oscillatory photodynamic therapy and intravitreal pharmacotherapy with antivascular endothelial growth factor agents. Exogenous testosterone is increasingly prescribed for menopausal symptoms and libido loss. Treatment with oscillatory photodynamic therapy, supplemental bevacizumab intravitreal pharmacotherapy, and cessation of exogenous androgen therapy was successful in three cases of chronic, therapy-resistant CSR. Ophthalmologists should inquire about androgen usage in patients who present with CSR, especially in the setting of therapy resistance.

  9. Extracellular and Intracellular Mechanisms Mediating Metastatic Activity of Exogenous Osteopontin

    Science.gov (United States)

    Mandelin, Jami; Lin, Emme C. K.; Hu, Dana D.; Knowles, Susan K.; Do, Kim-Anh; Wang, Xuemei; Sage, E. Helene; Smith, Jeffrey W.; Arap, Wadih; Pasqualini, Renata

    2009-01-01

    BACKGROUND Osteopontin affects several steps of the metastatic cascade. Despite direct correlation with metastasis in experimental systems and in patient studies, the extracellular and intracellular basis for these observations remains unsolved. We used human melanoma and sarcoma cell lines to evaluate the effects of soluble osteopontin on metastasis. METHODS Exogenous osteopontin or negative controls, including a site-directed mutant osteopontin, were used in functional assays in vitro, ex vivo, and in vivo designed to test extracellular and intracellular mechanisms involved in experimental metastasis. RESULTS In the extracellular environment, we confirm that soluble osteopontin is required for its pro-metastatic effects; this phenomenon is specific, RGD-dependent, and evident in experimental models of metastasis. In the intracellular environment, osteopontin initially induces rapid Tyr-418 dephosphorylation of c-Src, with decreases in actin stress fibers and increased binding to the vascular endothelium. This heretofore undescribed Tyr dephosphorylation is followed by a tandem c-Src phosphorylation after tumor cell attachment to the metastatic site. CONCLUSION Our results reveal a complex molecular interaction as well as a dual role for osteopontin in metastasis that is dependent on whether tumor cells are in circulation or attached. Such context-dependent functional insights may contribute to anti-metastasis strategies. PMID:19224553

  10. Clinical Laboratory Tests in Some Acute Exogenous Poisonings.

    Science.gov (United States)

    Tufkova, Stoilka G; Yankov, Ivan V; Paskaleva, Diana A

    2017-09-01

    There is no specific toxicological screening of clinical laboratory parameters in clinical toxicology when it comes to acute exogenous poisoning. To determine routine clinical laboratory parameters and indicators for assessment of vital functions in patients with acute intoxications. One hundred and fifty-three patients were included in the present study. They were hospitalized in the Department of Clinical Toxicology at St. George University Hospital, Plovdiv for cerebral toxicity inducing medication (n = 45), alcohol (n = 40), heroin abuse (n = 33). The controls were 35. The laboratory tests were conducted in compliance with the standards of the clinical laboratory. We used the following statistical analyses: analysis of variance (the ucriterion of normal distribution, the Student's t-test, dispersion analysis based on ANOVA) and non-parametric analysis. Based on the routine hematological parameters with statistically significant changes in three groups of poisoning are: red blood cells, hematocrit, hemoglobin (except alcohol intoxication) and leukocytes. We found statistically significant changes in serum total protein, sodium and bilirubin. The highest statistical significance is the increased activity of AST and ALT. We present a model for selection of clinical laboratory tests for severe acute poisoning with modern equipment under standardized conditions. The results of the study suggest that the clinical laboratory constellation we used can be used as a mandatory element in the diagnosis of moderate and severe intoxication with the mentioned toxic substances.

  11. Lung Regeneration: Endogenous and Exogenous Stem Cell Mediated Therapeutic Approaches.

    Science.gov (United States)

    Akram, Khondoker M; Patel, Neil; Spiteri, Monica A; Forsyth, Nicholas R

    2016-01-19

    The tissue turnover of unperturbed adult lung is remarkably slow. However, after injury or insult, a specialised group of facultative lung progenitors become activated to replenish damaged tissue through a reparative process called regeneration. Disruption in this process results in healing by fibrosis causing aberrant lung remodelling and organ dysfunction. Post-insult failure of regeneration leads to various incurable lung diseases including chronic obstructive pulmonary disease (COPD) and idiopathic pulmonary fibrosis. Therefore, identification of true endogenous lung progenitors/stem cells, and their regenerative pathway are crucial for next-generation therapeutic development. Recent studies provide exciting and novel insights into postnatal lung development and post-injury lung regeneration by native lung progenitors. Furthermore, exogenous application of bone marrow stem cells, embryonic stem cells and inducible pluripotent stem cells (iPSC) show evidences of their regenerative capacity in the repair of injured and diseased lungs. With the advent of modern tissue engineering techniques, whole lung regeneration in the lab using de-cellularised tissue scaffold and stem cells is now becoming reality. In this review, we will highlight the advancement of our understanding in lung regeneration and development of stem cell mediated therapeutic strategies in combating incurable lung diseases.

  12. [Alleviation of salt stress during maize seed germination by presoaking with exogenous sugar].