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Sample records for heat labile toxin

  1. Cistrons encoding Escherichia coli heat-labile toxin.

    PubMed Central

    Dallas, W S; Gill, D M; Falkow, S

    1979-01-01

    The structure and products of the two cistrons encoding the Escherichia coli heat-labile toxin (LT) were studied. The LT deoxyribonucleic acid (DNA) region had been isolated as part of a DNA fragment from the plasmid P307, and this fragment was joined to the cloning vector pBR313. Deletion mutations of various lengths were introduced into the LT DNA region and into the adjacent DNA sequences. Analysis of the deletions indicated that the maximum size of the LT DNA region was 1.2 x 10(6) daltons. Two proteins of 11,500 daltons and 25,500 daltons had been shown to be encoded by the LT DNA region. The functions of these LT gene products were investigated. The 11,500-dalton protein had an adsorption activity for Y-1 adrenal cells, and this protein was shown to form aggregates of four or five monomers. The 25,500-dalton protein was shown to have an adenylate cyclase-activating activity. The two cistrons encoding for each of the LT proteins have been located on a genetic map of the LT DNA region. Both cistrons are probably transcribed from the same promoter. Images PMID:383697

  2. Colorimetric detection of heat-labile toxin-encoding gene of enterotoxigenic Escherichia coli by PCR.

    PubMed

    O'Meara, D; O'Shaughnessy, E; Cryan, B; Fanning, S

    1995-07-01

    In the developing world, enterotoxigenic Escherichia coli (ETEC) strains which produce enterotoxins are a significant cause of morbidity and mortality. Heat-labile (LT) toxin PCR detection methods have been described, but they have limited applications in a routine laboratory setting. A colorimetric DNA method for the rapid amplification and detection of the LT toxin gene in ETEC strains is described. Target amplification together with colorimetric detection would overcome many of the limitations of conventional PCR. This paper describes a colorimetric PCR detection method specific for LT-gene-encoding ETEC strains. DNA was extracted from two representative colonies from each bacterial isolate and amplified by PCR. Digoxigenin was incorporated into the amplification product, permitting a one-step direct detection using anti-digoxigenin alkaline phosphatase-conjugated antibody. This technique was applied to the investigation of 70 E. coli isolates derived from clinical fecal samples obtained from an Irish population. Eleven percent of the samples were LT positive, confirming the applicability of this method. All LT-positive ETEC strains (controls and clinical isolates) were detected, and no false-positive results occurred. PMID:7665683

  3. Allele Variants of Enterotoxigenic Escherichia coli Heat-Labile Toxin Are Globally Transmitted and Associated with Colonization Factors

    PubMed Central

    Joffré, Enrique; von Mentzer, Astrid; Abd El Ghany, Moataz; Oezguen, Numan; Savidge, Tor; Dougan, Gordon; Svennerholm, Ann-Mari

    2014-01-01

    Enterotoxigenic Escherichia coli (ETEC) is a significant cause of morbidity and mortality in the developing world. ETEC-mediated diarrhea is orchestrated by heat-labile toxin (LT) and heat-stable toxins (STp and STh), acting in concert with a repertoire of more than 25 colonization factors (CFs). LT, the major virulence factor, induces fluid secretion after delivery of a monomeric ADP-ribosylase (LTA) and its pentameric carrier B subunit (LTB). A study of ETEC isolates from humans in Brazil reported the existence of natural LT variants. In the present study, analysis of predicted amino acid sequences showed that the LT amino acid polymorphisms are associated with a geographically and temporally diverse set of 192 clinical ETEC strains and identified 12 novel LT variants. Twenty distinct LT amino acid variants were observed in the globally distributed strains, and phylogenetic analysis showed these to be associated with different CF profiles. Notably, the most prevalent LT1 allele variants were correlated with major ETEC lineages expressing CS1 + CS3 or CS2 + CS3, and the most prevalent LT2 allele variants were correlated with major ETEC lineages expressing CS5 + CS6 or CFA/I. LTB allele variants generally exhibited more-stringent amino acid sequence conservation (2 substitutions identified) than LTA allele variants (22 substitutions identified). The functional impact of LT1 and LT2 polymorphisms on virulence was investigated by measuring total-toxin production, secretion, and stability using GM1–enzyme-linked immunosorbent assays (GM1-ELISA) and in silico protein modeling. Our data show that LT2 strains produce 5-fold more toxin than LT1 strains (P < 0.001), which may suggest greater virulence potential for this genetic variant. Our data suggest that functionally distinct LT-CF variants with increased fitness have persisted during the evolution of ETEC and have spread globally. PMID:25404692

  4. Epitope maps of the Escherichia coli heat-labile toxin B subunit for development of a synthetic oral vaccine.

    PubMed Central

    Takahashi, I; Kiyono, H; Jackson, R J; Fujihashi, K; Staats, H F; Hamada, S; Clements, J D; Bost, K L; McGhee, J R

    1996-01-01

    Linear B- and T-cell epitopes spanning all 103 amino acids of the Escherichia coli heat-labile toxin B subunit (LT-B) were assessed in mice orally immunized with native LT or with recombinant Salmonella enteritidis expressing LT-B. Oral administration of native LT induced mucosal immunoglobulin A (IgA) antibodies reactive with an epitope at residues 85 to 91, while IgA induced by recombinant Salmonella LT-B reacted with an epitope at residues 36 to 44. Serum IgG anti-LT-B antibodies from mice orally immunized with either LT or with recombinant Salmonella LT-B were directed to both epitopes. A single T-cell epitope spanning residues 34 to 42 was identified by T-cell proliferative and cytokine responses. When a 20-mer peptide (residues 26 to 45) with B- and T-cell epitopes was given orally to BALB/c (H-2(d)) and B10 congenic (I-A(d), I-A(b), and I-A(k)) mice, significant fecal IgA and serum IgG anti-LT-B antibodies were induced. The peptide also induced LT-B-specific T-cell proliferative responses in these mice. Orally administered LT-B peptide (residues 26 to 45) induced a cytokine profile indicative of both T helper 1- and 2-type cells. The remarkable immunogenicity of this 20-mer peptide makes it a candidate for a vaccine to protect against enterotoxigenic E. coli. PMID:8606092

  5. Biophysical characteristics of cholera toxin and Escherichia coli heat-labile enterotoxin structure and chemistry lead to differential toxicity.

    PubMed

    Craft, John W; Shen, Tsai-Wei; Brier, Lindsey M; Briggs, James M

    2015-01-22

    The biophysical chemistry of macromolecular complexes confer their functional characteristics. We investigate the mechanisms that make the AB5 holotoxin of Vibrio cholerae (CT) a significantly more pathogenic molecule than the enterotoxin of Escherichia coli (LT) with which it shares 88% similarity and whose structure is homologous with a backbone RMSD of 0.84 Å and imposes its deleterious effects though the same process to constitutively ADP-ribosylate adenylate cyclase. We present computational data that characterizes the impact of amino acid variations in the A2 tail, which helps to explain experimental data that demonstrate CT's higher toxicity. A hydrophobic patch on the B pentamer interface and its interactions with the A subdomain are partially disrupted by the substitution of an aspartic acid (LT) for glycine in CT. CT's holotoxin has less solvent accessible surface area (94 Å(2) vs 54 Å(2)) and higher contact area (280 Å(2) vs 241 Å(2)) with S228, which is a gatekeeper, partially controlling the diffusion of water into the pore. CT excludes water from the top of the central pore whereas LT allows much more water to interact. These biophysical properties of the toxins lead to their differential toxicity and resulting impact to human health. PMID:25322200

  6. Non-recombinant display of the B subunit of the heat labile toxin of Escherichia coli on wild type and mutant spores of Bacillus subtilis

    PubMed Central

    2013-01-01

    Background Mucosal infections are a major global health problem and it is generally accepted that mucosal vaccination strategies, able to block infection at their entry site, would be preferable with respect to other prevention approaches. However, there are still relatively few mucosal vaccines available, mainly because of the lack of efficient delivery systems and of mucosal adjuvants. Recombinant bacterial spores displaying a heterologous antigen have been shown to induce protective immune responses and, therefore, proposed as a mucosal delivery system. A non-recombinant approach has been recently developed and tested to display antigens and enzymes. Results We report that the binding subunit of the heat-labile toxin (LTB) of Escherichia coli efficiently adsorbed on the surface of Bacillus subtilis spores. When nasally administered to groups of mice, spore-adsorbed LTB was able to induce a specific immune response with the production of serum IgG, fecal sIgA and of IFN-? in spleen and mesenteric lymph nodes (MLN) of the immunized animals. Dot blotting experiments showed that the non-recombinant approach was more efficient than the recombinant system in displaying LTB and that the efficiency of display could be further increased by using mutant spores with an altered surface. In addition, immunofluorescence microscopy experiments showed that only when displayed on the spore surface by the non-recombinant approach LTB was found in its native, pentameric form. Conclusion Our results indicate that non-recombinant spores displaying LTB pentamers can be administered by the nasal route to induce a Th1-biased, specific immune response. Mutant spores with an altered coat are more efficient than wild type spores in adsorbing the antigen, allowing the use of a reduced number of spores in immunization procedures. Efficiency of display, ability to display the native form of the antigen and to induce a specific immune response propose this non-recombinant delivery system as a powerful mucosal vaccine delivery approach. PMID:24168229

  7. Parenteral adjuvant activities of Escherichia coli heat-labile toxin and its B subunit for immunization of mice against gastric Helicobacter pylori infection.

    PubMed

    Weltzin, R; Guy, B; Thomas, W D; Giannasca, P J; Monath, T P

    2000-05-01

    The heat-labile toxin (LT) of Escherichia coli is a potent mucosal adjuvant that has been used to induce protective immunity against Helicobacter felis and Helicobacter pylori infection in mice. We studied whether recombinant LT or its B subunit (LTB) has adjuvant activity in mice when delivered with H. pylori urease antigen via the parenteral route. Mice were immunized subcutaneously or intradermally with urease plus LT, recombinant LTB, or a combination of LT and LTB prior to intragastric challenge with H. pylori. Control mice were immunized orally with urease plus LT, a regimen shown previously to protect against H. pylori gastric infection. Parenteral immunization using either LT or LTB as adjuvant protected mice against H. pylori challenge as effectively as oral immunization and enhanced urease-specific immunoglobulin G (IgG) responses in serum as effectively as aluminum hydroxide adjuvant. LT and LTB had adjuvant activity at subtoxic doses and induced more consistent antibody responses than those observed with oral immunization. A mixture of a low dose of LT and a high dose of LTB stimulated the highest levels of protection and specific IgG in serum. Urease-specific IgG1 and IgG2a antibody subclass responses were stimulated by all immunization regimens tested, but relative levels were dependent on the adjuvant used. Compared to parenteral immunization with urease alone, LT preferentially enhanced IgG1, while LTB or the LT-LTB mixture preferentially enhanced IgG2a. Parenteral immunization using LT or LTB as adjuvant also induced IgA to urease in the saliva of some mice. These results show that LT and LTB stimulate qualitatively different humoral immune responses to urease but are both effective parenteral adjuvants for immunization of mice against H. pylori infection. PMID:10768972

  8. Evaluating the A-Subunit of the Heat-Labile Toxin (LT) As an Immunogen and a Protective Antigen Against Enterotoxigenic Escherichia coli (ETEC)

    PubMed Central

    Norton, Elizabeth B.; Branco, Luis M.; Clements, John D.

    2015-01-01

    Diarrheal illness contributes to malnutrition, stunted growth, impaired cognitive development, and high morbidity rates in children worldwide. Enterotoxigenic Escherichia coli (ETEC) is a major contributor to this diarrheal disease burden. ETEC cause disease in the small intestine by means of colonization factors and by production of a heat-labile enterotoxin (LT) and/or a small non-immunogenic heat-stable enterotoxin (ST). Overall, the majority of ETEC produce both ST and LT. LT induces secretion via an enzymatically active A-subunit (LT-A) and a pentameric, cell-binding B-subunit (LT-B). The importance of anti-LT antibodies has been demonstrated in multiple clinical and epidemiological studies, and a number of potential ETEC vaccine candidates have included LT-B as an important immunogen. However, there is limited information about the potential contribution of LT-A to development of protective immunity. In the current study, we evaluate the immune response against the A-subunit of LT as well as the A-subunit’s potential as a protective antigen when administered alone or in combination with the B-subunit of LT. We evaluated human sera from individuals challenged with a prototypic wild-type ETEC strain as well as sera from individuals living in an ETEC endemic area for the presence of anti-LT, anti-LT-A and anti-LT-B antibodies. In both cases, a significant number of individuals intentionally or endemically infected with ETEC developed antibodies against both LT subunits. In addition, animals immunized with the recombinant proteins developed robust antibody responses that were able to neutralize the enterotoxic and cytotoxic effects of native LT by blocking binding and entry into cells (anti-LT-B) or the intracellular enzymatic activity of the toxin (anti-LT-A). Moreover, antibodies to both LT subunits acted synergistically to neutralize the holotoxin when combined. Taken together, these data support the inclusion of both LT-A and LT-B in prospective vaccines against ETEC. PMID:26305793

  9. Characterization of a Mutant Escherichia coli Heat-Labile Toxin, LT(R192G/L211A), as a Safe and Effective Oral Adjuvant ?

    PubMed Central

    Norton, Elizabeth B.; Lawson, Louise B.; Freytag, Lucy C.; Clements, John D.

    2011-01-01

    Despite the fact that the adjuvant properties of the heat-labile enterotoxins of Escherichia coli (LT) and Vibrio cholerae (CT) have been known for more than 20 years, there are no available oral vaccines containing these molecules as adjuvants, primarily because they are both very potent enterotoxins. A number of attempts with various degrees of success have been made to reduce or eliminate the enterotoxicity of LT and CT so they can safely be used as oral adjuvants or immunogens. In this report we characterize the structural, enzymatic, enterotoxic, and adjuvant properties of a novel mutant of LT, designated LT(R192G/L211A), or dmLT. dmLT was not sensitive to trypsin activation, had reduced enzymatic activity for induction of cyclic AMP in Caco-2 cells, and exhibited no enterotoxicity in the patent mouse assay. Importantly, dmLT retained the ability to function as an oral adjuvant for a coadministered antigen (tetanus toxoid) and to elicit anti-LT antibodies. In vitro and in vivo data suggest that the reduced enterotoxicity of this molecule compared to native LT or the single mutant, LT(R192G), is a consequence of increased sensitivity to proteolysis and rapid intracellular degradation in mammalian cells. In conclusion, dmLT is a safe and powerful detoxified enterotoxin with the potential to function as a mucosal adjuvant for coadministered antigens and to elicit anti-LT antibodies without undesirable side effects. PMID:21288994

  10. The B subunit of Escherichia coli heat-labile toxin alters the development and antigen-presenting capacity of dendritic cells

    PubMed Central

    Ji, Jing; Griffiths, Kristin L; Milburn, Peter J; Hirst, Timothy R; O’Neill, Helen C

    2015-01-01

    Escherichia coli’s heat-labile enterotoxin (Etx) and its non-toxic B subunit (EtxB) have been characterized as adjuvants capable of enhancing T cell responses to co-administered antigen. Here, we investigate the direct effect of intravenously administered EtxB on the size of the dendritic and myeloid cell populations in spleen. EtxB treatment appears to enhance the development and turnover of dendritic and myeloid cells from precursors within the spleen. EtxB treatment also gives a dendritic cell (DC) population with higher viability and lower activation status based on the reduced expression of MHC-II, CD80 and CD86. In this respect, the in vivo effect of EtxB differs from that of the highly inflammatory mediator lipopolysaccharide. In in vitro bone marrow cultures, EtxB treatment was also found to enhance the development of DC from precursors dependent on Flt3L. In terms of the in vivo effect of EtxB on CD4 and CD8 T cell responses in mice, the interaction of EtxB directly with DC was demonstrated following conditional depletion of CD11c+ DC. In summary, all results are consistent with EtxB displaying adjuvant ability by enhancing the turnover of DC in spleen, leading to newly mature myeloid and DC in spleen, thereby increasing DC capacity to perform as antigen-presenting cells on encounter with T cells. PMID:26130503

  11. Safety and immunogenicity of bacterial and tobacco plant cell line derived recombinant native and mutant Escherichia coli heat-labile toxin in chickens.

    PubMed

    Miller, Tim; Fanton, Matthew; Nickelson, Stephanie; Mason, Hugh; Webb, Steven

    2012-10-01

    The safety and immunogenicity of the mammalian mucosal adjuvants, Escherichia coli wild-type heat-labile holotoxin (LT) and E. coli mutant LT (LTA-K63/LTB), were examined in 1-day-old chicks and 10-day-old to 21-day-old broilers. Biologically active, E. coli recombinant wild-type LT and recombinant LTA-K63/LTB produced in a transgenic Nicotiana tabacum (NT-1) tobacco cell line (SLT102) were tested for safety and antigenicity following various routes of administration. Safety was assessed by clinical signs, body weight gain, gross organ pathology and wet organ weight, and histopathology. Antigenicity was assessed using LT-B-specific serum IgG enzyme-linked immunosorbent assay. Parenteral administration of E. coli recombinant wild-type LT did not have any discernible effect on bird health and was well tolerated at levels up to 400 µg per dose. Recombinant, SLT102-derived mutant LT derived from SLT102 cells retained in vitro ganglioside binding and was safe and antigenic following repeated mucosal administration to birds. The highest systemic LT-B-specific IgG titres were detected in birds that received three on-feed doses of SLT102-derived mutant LT. Among the various SLT102-derived mutant LT preparations tested, whole, wet cells or whole cell lysates were the most antigenic. These results demonstrate for the first time that E. coli-derived recombinant, wild-type LT holotoxin is well tolerated following multiple administrations to young birds at body weight doses previously reported to be enteropathogenic and toxic in mammalian species. Moreover, these data also demonstrate the feasibility of using recombinant wild-type and mutant LT produced in transgenic NT-1 tobacco cells as safe and potent vaccine adjuvants in poultry. PMID:22928883

  12. Genetic Fusions of a CFA/I/II/IV MEFA (Multiepitope Fusion Antigen) and a Toxoid Fusion of Heat-Stable Toxin (STa) and Heat-Labile Toxin (LT) of Enterotoxigenic Escherichia coli (ETEC) Retain Broad Anti-CFA and Antitoxin Antigenicity

    PubMed Central

    Ruan, Xiaosai; Sack, David A.; Zhang, Weiping

    2015-01-01

    Immunological heterogeneity has long been the major challenge in developing broadly effective vaccines to protect humans and animals against bacterial and viral infections. Enterotoxigenic Escherichia coli (ETEC) strains, the leading bacterial cause of diarrhea in humans, express at least 23 immunologically different colonization factor antigens (CFAs) and two distinct enterotoxins [heat-labile toxin (LT) and heat-stable toxin type Ib (STa or hSTa)]. ETEC strains expressing any one or two CFAs and either toxin cause diarrhea, therefore vaccines inducing broad immunity against a majority of CFAs, if not all, and both toxins are expected to be effective against ETEC. In this study, we applied the multiepitope fusion antigen (MEFA) strategy to construct ETEC antigens and examined antigens for broad anti-CFA and antitoxin immunogenicity. CFA MEFA CFA/I/II/IV [CVI 2014, 21(2):243-9], which carried epitopes of seven CFAs [CFA/I, CFA/II (CS1, CS2, CS3), CFA/IV (CS4, CS5, CS6)] expressed by the most prevalent and virulent ETEC strains, was genetically fused to LT-STa toxoid fusion monomer 3xSTaA14Q-dmLT or 3xSTaN12S-dmLT [IAI 2014, 82(5):1823-32] for CFA/I/II/IV-STaA14Q-dmLT and CFA/I/II/IV-STaN12S-dmLT MEFAs. Mice intraperitoneally immunized with either CFA/I/II/IV-STa-toxoid-dmLT MEFA developed antibodies specific to seven CFAs and both toxins, at levels equivalent or comparable to those induced from co-administration of the CFA/I/II/IV MEFA and toxoid fusion 3xSTaN12S-dmLT. Moreover, induced antibodies showed in vitro adherence inhibition activities against ETEC or E. coli strains expressing these seven CFAs and neutralization activities against both toxins. These results indicated CFA/I/II/IV-STa-toxoid-dmLT MEFA or CFA/I/II/IV MEFA combined with 3xSTaN12S-dmLT induced broadly protective anti-CFA and antitoxin immunity, and suggested their potential application in broadly effective ETEC vaccine development. This MEFA strategy may be generally used in multivalent vaccine development. PMID:25803825

  13. Toward the development of a stable, freeze-dried formulation of Helicobacter pylori killed whole cell vaccine adjuvanted with a novel mutant of E. coli heat-labile toxin

    PubMed Central

    Summerton, Nancy A.; Welch, Richard W.; Bondoc, Laureano; Yang, Huei-Hsiung; Pleune, Brett; Ramachandran, Naryaswamy; Harris, Andrea M.; Bland, Desiree; Jackson, W. James; Park, Sukjoon; Clements, John D.; Nabors, Gary S.

    2009-01-01

    No vaccine exists for the prevention of infection with the ubiquitous gastric pathogen Helicobacter pylori, and drug therapy for the infection is complicated by poor patient compliance, the high cost of treatment, and ineffectiveness against drug resistant strains. A new medical advancement is required to reduce the incidence of peptic ulcer disease and stomach cancer, two conditions caused by infection with H. pylori. Clinical trials have been performed with a formalin-inactivated Helicobacter pylori Whole Cell (HWC) vaccine, given orally in combination with the mucosal adjuvant mLT(R192G), a mutant of E. coli heat-labile toxin. Following the initial dose of this vaccine, some subjects experienced gastrointestinal side effects. To reduce side effects and potentially further increase the amount of adjuvant that can safely be administered with the HWC vaccine, experiments were performed with a form of LT that carried two mutations in the A subunit, a substitution of G for R at position 192, and A for L at position 211. The double-mutant LT (dmLT) adjuvant stimulated immune responses as effectively as the single mutant LT in mice. Additionally, following a challenge infection, the dmLT-adjuvanted vaccine was as effective as single mutant LT in reducing gastric urease levels (diagnostic for H. pylori infection), and H. pylori colonization in the stomach as assessed by quantitative analysis of stomach homogenates. A lyophilized formulation of HWC was developed to improve stability and to potentially reduce reliance on cold chain maintenance. It was observed that a dmLT-adjuvanted lyophilized vaccine was equally as protective in the mouse model as the liquid formulation as assessed by gastric urease analysis and analysis of stomach homogenates for viable H. pylori. No readily detectable effect of tonicity or moisture content was observed for the lyophilized vaccine within the formulation limits evaluated. In an accelerated stability study performed at 37°C the lyophilized vaccine remained equally as protective as vaccine stored at 2–8°C. The formulation selected for clinical development consisted of 2.5×1010 formalin-inactivated cells per ml in 6.5% trehalose, 0.5% mannitol, and 10 mM citrate buffer at pH 6.8. PMID:19897067

  14. Toward the development of a stable, freeze-dried formulation of Helicobacter pylori killed whole cell vaccine adjuvanted with a novel mutant of Escherichia coli heat-labile toxin.

    PubMed

    Summerton, Nancy A; Welch, Richard W; Bondoc, Laureano; Yang, Huei-Hsiung; Pleune, Brett; Ramachandran, Naryaswamy; Harris, Andrea M; Bland, Desiree; Jackson, W James; Park, Sukjoon; Clements, John D; Nabors, Gary S

    2010-02-01

    No vaccine exists for the prevention of infection with the ubiquitous gastric pathogen Helicobacter pylori, and drug therapy for the infection is complicated by poor patient compliance, the high cost of treatment, and ineffectiveness against drug-resistant strains. A new medical advancement is required to reduce the incidence of peptic ulcer disease and stomach cancer, two conditions caused by infection with H. pylori. Clinical trials have been performed with a formalin-inactivated H. pylori whole cell (HWC) vaccine, given orally in combination with the mucosal adjuvant mLT(R192G), a mutant of Escherichia coli heat-labile toxin. Following the initial dose of this vaccine, some subjects experienced gastrointestinal side effects. To reduce side effects and potentially further increase the amount of adjuvant that can safely be administered with the HWC vaccine, experiments were performed with a form of LT that carried two mutations in the A subunit, a substitution of G for R at position 192, and A for L at position 211. The double mutant LT (dmLT) adjuvant stimulated immune responses as effectively as the single mutant LT in mice. Additionally, following a challenge infection, the dmLT-adjuvanted vaccine was as effective as single mutant LT in reducing gastric urease levels (diagnostic for H. pylori infection), and H. pylori colonization in the stomach as assessed by quantitative analysis of stomach homogenates. A lyophilized formulation of HWC was developed to improve stability and to potentially reduce reliance on cold chain maintenance. It was observed that a dmLT-adjuvanted lyophilized vaccine was equally as protective in the mouse model as the liquid formulation as assessed by gastric urease analysis and analysis of stomach homogenates for viable H. pylori. No readily detectable effect of tonicity or moisture content was observed for the lyophilized vaccine within the formulation limits evaluated. In an accelerated stability study performed at 37 degrees C the lyophilized vaccine remained equally as protective as vaccine stored at 2-8 degrees C. The formulation selected for clinical development consisted of 2.5 x 10(10) formalin-inactivated cells per ml in 6.5% trehalose, 0.5% mannitol, and 10mM citrate buffer at pH 6.8. PMID:19897067

  15. Heat-Labile Enterotoxin IIa, a Platform To Deliver Heterologous Proteins into Neurons

    PubMed Central

    Chen, Chen; Przedpelski, Amanda; Tepp, William H.; Pellett, Sabine; Johnson, Eric A.

    2015-01-01

    ABSTRACT Cholera toxin (CT) and the related heat-labile enterotoxins (LT) of Escherichia coli have been implicated as adjuvants in human therapies, but reactivity upon intranasal delivery dampened efforts to develop other clinical applications. However, each CT family member variant has unique biological properties that may warrant development as therapeutic platforms. In the current study, a nontoxic variant of the heat-labile enterotoxin IIa (LTIIa) was engineered to deliver heterologous, functional proteins into the cytosol of neurons. As proof of principle, the LTIIa variant delivered two cargos into neurons. LTIIa delivered ?-lactamase efficiently into cells containing complex gangliosides, such as GD1b, as host receptors. LTIIa delivery of ?-lactamase was sensitive to brefeldin A, an inhibitor that collapses the Golgi compartment into the endoplasmic reticulum, but not sensitive to treatment with botulinum neurotoxin D (BoNT/D), an inhibitor of synaptic vesicle cycling. LTIIa delivered a single-chain, anti-BoNT/A camelid antibody that inhibited SNAP25 cleavage during post-BoNT/A exposure of neurons. Delivery of functional, heterologous protein cargos into neurons demonstrates the potential of LTII variants as platforms to deliver therapies to inactivate toxins and microbial infections and to reverse the pathology of human neurodegenerative diseases. PMID:26265718

  16. A Combination Vaccine Consisting of Three Live Attenuated Enterotoxigenic Escherichia coli Strains Expressing a Range of Colonization Factors and Heat-Labile Toxin Subunit B Is Well Tolerated and Immunogenic in a Placebo-Controlled Double-Blind Phase I Trial in Healthy Adults ?

    PubMed Central

    Harro, Clayton; Sack, David; Bourgeois, A. Louis; Walker, R.; DeNearing, Barbara; Feller, Andrea; Chakraborty, Subhra; Buchwaldt, Charlotte; Darsley, Michael J.

    2011-01-01

    Immune responses against colonization factors (CFs) and the nontoxic B component of the enterotoxigenic Escherichia coli (ETEC) heat-labile toxin (LTB) are considered to be important for immunity against diarrhea caused by ETEC. Individual live attenuated ETEC derivatives that have had their toxin genes removed and whose aroC, ompC, and ompF genes are deleted have shown promise as vaccines against ETEC. The development of such strains has culminated in the testing of a three-strain-combination live attenuated vaccine known as ACE527, comprised of strains ACAM2025 expressing colonization factor antigen I (CFA/I) and LTB; ACAM2022, expressing CS5, CS6, and LTB; and ACAM2027, expressing CS1, CS2, CS3, and LTB. The recombinant CF and LTB genes expressed in the three strains were inserted into the bacterial chromosome to ensure their stable inheritance and expression without the requirement for any selection. ACE527 has been tested in a randomized placebo-controlled, double-blind, phase I safety and immunogenicity study in healthy adult volunteers and proved to be well tolerated and immunogenic at dose levels of 1010 and 1011 total CFU. There was no indication of strain interference on the basis of fecal shedding patterns, with all three being detected in the feces of 50% and 83% of low- and high-dose vaccine recipients, respectively. Similarly, strong immune responses to LTB and to CFs expressed on all three constituent strains were induced, with at least 50% of subjects in the high-dose group responding to LTB, CFA/I, CS3, and CS6. PMID:21994354

  17. Rapid diagnosis of "Escherichia coli" heat labile enterotoxin (LT) by a coagglutination test.

    PubMed

    Wadström, T; Rönnberg, B

    1983-01-01

    Protein A positive Staphylococcus aureus cells, strain Cowan 1, were coated with a high titer anti-LT serum produced in rabbits. Purified E. coli heat labile enterotoxin (LT) was detected in a slide coagglutination (coa-LT) test with anti-LT coated staphylococci at the nanogram level (0.1-1 ng) while cholera toxin (CT) was detected only at much higher concentrations (10-50 ng). This LT immunoassay was evaluated in different modifications on enterotoxigenic E. coli (ETEC) isolated from humans and animal stool cultures. Colonies from primary stool cultures on blood agar were suspended and lysed in saline containing polymyxin B and a detergent (Triton X100), centrifuged and assayed for LT. The coa-LT and CHO-cell tests regularly detected LT among human LT producing ETEC, while ETEC strains from piglets and calves usually gave only weak reactions in the standard coa-LT test. We conclude that this coa-LT test is accurate and sensitive enough to be used in routine diagnosis of LT producing ETEC strains in stools from human patients. This test requires no special laboratory equipment and is well suited for rapid diagnosis of ETEC in small hospital laboratories and in developing countries. Heat stable enterotoxin (ST) giving a positive suckling mouse test, has been purified by hydrophobic interaction chromatography (HIC) on Octyl Sepharose. Purified ST was covalently linked to different proteins and such carrier complexes used for immunization of rabbits. The ST antibody titers obtained by various ST-carriers were compared in a ST coagglutination test (ST-coa) and in a conventional ELISA microtiter assay. The results and detection limits for ST in polymyxin-detergent cell lysates in human ETEC strains producing LT-ST or ST only will be presented. PMID:6347757

  18. Dissociation of Escherichia coli heat-labile enterotoxin adjuvanticity from ADP-ribosyltransferase activity.

    PubMed Central

    Dickinson, B L; Clements, J D

    1995-01-01

    The heat-labile enterotoxin (LT) of Escherichia coli is immunologically and physiochemically related to cholera enterotoxin. A number of studies have been performed to determine the relationship of the ADP-ribosylating enzymatic activity of these enterotoxins to toxicity and adjuvanticity. These studies have generally examined the effect of abolishing the ADP-ribosyltransferase activity of A1 by a variety of chemical or genetic manipulations. In every case, loss of enzymatic activity was associated with loss of biological activity and also with the ability of the molecules to function as oral adjuvants. Consequently, we explored an alternate approach to detoxification of LT without altering its adjuvanticity. Specifically, we generated a novel mutant form of LT by genetic modification of the proteolytically sensitive residues that join the A1 and A2 components of the A subunit. This mutant contains a single amino acid substitution within the disulfide subtended region joining A1 and A2. This mutant toxin, designated LT(R192G), is not sensitive to proteolytic activation, has negligible activity on mouse Y-1 adrenal tumor cells, and is devoid of ADP-ribosyltransferase activity. Nonetheless, LT(R192G) retains the ability to function as a mucosal adjuvant, increasing the serum immunoglobulin G (IgG) and mucosal IgA responses to coadministered antigen (OVA) beyond that achieved with administration of that antigen alone. Further, LT(R192G) prevented the induction of tolerance to coadministered antigen and did not induce tolerance against itself, as demonstrated by the presence of significant serum anti-LT IgG and mucosal anti-LT IgA antibodies in immunized mice. PMID:7729864

  19. Solid-Phase Microtiter Radioimmunoassay Blocking Test for Detection of Antibodies to Escherichia coli Heat-Labile Enterotoxin

    PubMed Central

    Greenberg, Harry B.; Levine, Myron M.; Merson, Michael H.; Sack, R. Bradley; Sack, David A.; Valdesuso, Jose R.; Nalin, David; Hoover, David; Chanock, Robert M.; Kapikian, Albert Z.

    1979-01-01

    The development of a solid-phase microtiter radioimmunoassay blocking test to detect serum antibody to Escherichia coli heat-labile enterotoxin is described. The assay is easy to perform and quantitate, and it is sensitive and specific. PMID:372216

  20. Solid-phase microtiter radioimmunoassay blocking test for detection of antibodies to Escherichia coli heat-labile enterotoxin.

    PubMed

    Greenberg, H B; Levine, M M; Merson, M H; Sack, R B; Sack, D A; Valdesuso, J R; Nalin, D; Hoover, D; Chanock, R M; Kapikian, A Z

    1979-01-01

    The development of a solid-phase microtiter radioimmunoassay blocking test to detect serum antibody to Escherichia coli heat-labile enterotoxin is described. The assay is easy to perform and quantitate, and it is sensitive and specific. PMID:372216

  1. Heat-labile enterotoxin of Escherichia coli promotes intestinal colonization of Salmonella enterica.

    PubMed

    Verbrugghe, Elin; Van Parys, Alexander; Leyman, Bregje; Boyen, Filip; Arnouts, Sven; Lundberg, Urban; Ducatelle, Richard; Van den Broeck, Wim; Yekta, Maryam Atef; Cox, Eric; Haesebrouck, Freddy; Pasmans, Frank

    2015-12-01

    Enterotoxigenic Escherichia coli (ETEC) is an important cause of infantile and travellers' diarrhoea, which poses a serious health burden, especially in developing countries. In addition, ETEC bacteria are a major cause of illness and death in neonatal and recently weaned pigs. The production of a heat-labile enterotoxin (LT) promotes the colonization and pathogenicity of ETEC and may exacerbate co-infections with other enteric pathogens such as Salmonella enterica. We showed that the intraintestinal presence of LT dramatically increased the intestinal Salmonella Typhimurium load in experimentally inoculated pigs. This could not be explained by direct alteration of the invasion or survival capacity of Salmonella in enterocytes, in vitro. However, we demonstrated that LT affects the enteric mucus layer composition in a mucus-secreting goblet cell line by significantly decreasing the expression of mucin 4. The current results show that LT alters the intestinal mucus composition and aggravates a Salmonella Typhimurium infection, which may result in the exacerbation of the diarrhoeal illness. PMID:26616654

  2. Toxins

    MedlinePLUS

    Toxins are substances created by plants and animals that are poisonous to humans. Toxins also include medications that are helpful in small doses, but poisonous when used in large amounts. Most toxins that cause problems in ...

  3. Polymyxin B-Induced Release of Low-Molecular-Weight, Heat-Labile Enterotoxin from Escherichia coli

    PubMed Central

    Evans, Doyle J.; Evans, Dolores G.; Gorbach, Sherwood L.

    1974-01-01

    Polymyxin B-induced release of enterotoxin from Escherichia coli strain H-10407 was demonstrated. Incubation of E. coli cells derived from 6-h cultures with polymyxin caused the rapid release of enterotoxin with a molecular weight of approximately 20,000, as estimated by the gel filtration technique. The rapidity of the release of enterotoxin indicates that it probably resides in the periplasmic space of the cell. The low-molecular-weight enterotoxin possessed vascular permeability factor and diarrheagenic activities, both of which were found to be heat-labile. The permeability factor activity of this enterotoxin was neutralized by antisera prepared against crude E. coli enterotoxin, Vibrio cholerae enterotoxin (choleragen), and V. cholerae toxoid (choleragenoid), respectively. Supernatant fluids of 6-h E. coli cultures did not contain this molecular form of enterotoxin but did contain very high-molecular-weight, heat-labile enterotoxin. Incubation of cells derived from older (18 h) cultures with polymyxin caused the release of both low- (20,000) and high-molecular-weight forms of enterotoxin. We concluded that either the 20,000-dalton form of heat-labile enterotoxin is not released by E. coli under in vitro growth conditions or that enterotoxin released in this form is rapidly destroyed or inactivated. PMID:16558081

  4. Induction of heat-labile sites in DNA of mammalian cells by the antitumor alkylating drug CC-1065

    SciTech Connect

    Zsido, T.J.; Woynarowski, J.M.; Baker, R.M.; Gawron, L.S.; Beerman, T.A. )

    1991-04-16

    CC-1065 is a very potent antitumor antibiotic capable of covalent and noncovalent binding to the minor groove of naked DNA. Upon thermal treatment, covalent adducts formed between CC-1065 and DNA generate strand break. The authors have shown that this molecular damage can be detected following CC-1065 treatment of mammalian whole cells. Using alkaline sucrose gradient analysis, They observe thermally induced breakage of ({sup 14}C)thymidine-prelabeled DNA from drug-treated African green monkey kidney BSC-1 cells. Very little damage to cellular DNA by CC-1065 can be detected without first heating the drug-treated samples. CC-1065 can also generate heat-labile sites within DNA during cell lysis and heating, subsequent to the exposure of cells to drug, suggesting that a pool of free and noncovalently bound drug is available for posttreatment adduct formation. This effect was controlled for by mixing ({sup 3}H)thymidine-labeled untreated cells with the ({sup 14}C)thymidine-labeled drug-treated samples. The lowest drug dose at which heat-labile sites were detected was 3 nM CC-1065 (3 single-stranded breaks/10{sup 6} base pairs). This concentration reduced survival of BSC-1 cells to 0.1% in cytotoxicity assays. The generation of CC-1065-induced lesions in cellular DNA is time dependent (the frequency of lesions caused by a 60 nM treatment reaching a plateau at 2 h) and is not readily reversible. The results of this study demonstrate that CC-1065 does generate heat-labile sites with the cellular DNA of intact cells and suggest that a mechanism of cytotoxic action of CC-1065 involves formation of covalent adducts to DNA.

  5. Repair of radiation-induced heat-labile sites is independent of DNA-PKcs, XRCC1 or PARP

    SciTech Connect

    Stenerlöw, Bo; Karlsson, Karin H.; Radulescu, Irina; Rydberg, Bjorn; Stenerlow, Bo

    2008-04-29

    Ionizing radiation induces a variety of different DNA lesions: in addition to the most critical DNA damage, the DSB, numerous base alterations, SSBs and other modifications of the DNA double-helix are formed. When several non-DSB lesions are clustered within a short distance along DNA, or close to a DSB, they may interfere with the repair of DSBs and affect the measurement of DSB induction and repair. We have previously shown that a substantial fraction of DSBs measured by pulsed-field gel electrophoresis (PFGE) are in fact due to heat-labile sites (HLS) within clustered lesions, thus reflecting an artifact of preparation of genomic DNA at elevated temperature. To further characterize the influence of HLS on DSB induction and repair, four human cell lines (GM5758, GM7166, M059K, U-1810) with apparently normal DSB rejoining were tested for bi-phasic rejoining after gamma irradiation. When heat-released DSBs were excluded from the measurements the fraction of fast rejoining decreased to less than 50% of the total. However, neither the half-times of the fast (t{sub 1/2} = 7-8 min) or slow (t{sub 1/2} = 2.5 h) DSB rejoining were changed significantly. At t=0 the heat-released DSBs accounted for almost 40% of the DSBs, corresponding to 10 extra DSB/cell/Gy in the initial DSB yield. These heat-released DSBs were repaired within 60-90 min in all tested cells, including M059K cells treated with wortmannin or DNA-PKcs defect M059J cells. Furthermore, cells lacking XRCC1 or Poly(ADP-ribose) polymerase-1 (PARP-1) rejoined both total DSBs and heat-released DSBs similar to normal cells. In summary, the presence of heat-labile sites have a substantial impact on DSB induction yields and DSB rejoining rates measured by pulsed-field gel electrophoresis, and HLS repair is independent of DNA-PKcs, XRCC1 and PARP.

  6. Peracetic Acid: A Practical Agent for Sterilizing Heat-Labile Polymeric Tissue-Engineering Scaffolds

    PubMed Central

    Yoganarasimha, Suyog; Trahan, William R.; Best, Al M.; Bowlin, Gary L.; Kitten, Todd O.; Moon, Peter C.

    2014-01-01

    Advanced biomaterials and sophisticated processing technologies aim at fabricating tissue-engineering scaffolds that can predictably interact within a biological environment at the cellular level. Sterilization of such scaffolds is at the core of patient safety and is an important regulatory issue that needs to be addressed before clinical translation. In addition, it is crucial that meticulously engineered micro- and nano- structures are preserved after sterilization. Conventional sterilization methods involving heat, steam, and radiation are not compatible with engineered polymeric systems because of scaffold degradation and loss of architecture. Using electrospun scaffolds made from polycaprolactone, a low melting polymer, and employing spores of Bacillus atrophaeus as biological indicators, we compared ethylene oxide, autoclaving and 80% ethanol to a known chemical sterilant, peracetic acid (PAA), for their ability to sterilize as well as their effects on scaffold properties. PAA diluted in 20% ethanol to 1000?ppm or above sterilized electrospun scaffolds in 15?min at room temperature while maintaining nano-architecture and mechanical properties. Scaffolds treated with PAA at 5000?ppm were rendered hydrophilic, with contact angles reduced to 0°. Therefore, PAA can provide economical, rapid, and effective sterilization of heat-sensitive polymeric electrospun scaffolds that are used in tissue engineering. PMID:24341350

  7. Peracetic acid: a practical agent for sterilizing heat-labile polymeric tissue-engineering scaffolds.

    PubMed

    Yoganarasimha, Suyog; Trahan, William R; Best, Al M; Bowlin, Gary L; Kitten, Todd O; Moon, Peter C; Madurantakam, Parthasarathy A

    2014-09-01

    Advanced biomaterials and sophisticated processing technologies aim at fabricating tissue-engineering scaffolds that can predictably interact within a biological environment at the cellular level. Sterilization of such scaffolds is at the core of patient safety and is an important regulatory issue that needs to be addressed before clinical translation. In addition, it is crucial that meticulously engineered micro- and nano- structures are preserved after sterilization. Conventional sterilization methods involving heat, steam, and radiation are not compatible with engineered polymeric systems because of scaffold degradation and loss of architecture. Using electrospun scaffolds made from polycaprolactone, a low melting polymer, and employing spores of Bacillus atrophaeus as biological indicators, we compared ethylene oxide, autoclaving and 80% ethanol to a known chemical sterilant, peracetic acid (PAA), for their ability to sterilize as well as their effects on scaffold properties. PAA diluted in 20% ethanol to 1000 ppm or above sterilized electrospun scaffolds in 15 min at room temperature while maintaining nano-architecture and mechanical properties. Scaffolds treated with PAA at 5000 ppm were rendered hydrophilic, with contact angles reduced to 0°. Therefore, PAA can provide economical, rapid, and effective sterilization of heat-sensitive polymeric electrospun scaffolds that are used in tissue engineering. PMID:24341350

  8. The mucosal adjuvanticity of two nontoxic mutants of Escherichia coli heat-labile enterotoxin varies with immunization routes.

    PubMed

    Park, E J; Chang, J H; Kim, J S; Yum, J S; Chung, S I

    2000-06-30

    Escherichia coli heat-labile enterotoxin (LT), which causes a characteristic diarrhea in humans and animals, is a strong mucosal immunogen and has powerful mucosal adjuvant activity towards coadministered unrelated antigens. Here we report the different mucosal adjuvanticity of nontoxic LT derivatives, LTS63Y and LTdelta110/112, generated by immunizing through two different mucosal routes. Intragastric (IG) immunization with Helicobacter pylori urease alone resulted in poor systemic IgG and IgA responses and no detectable local secretory IgA, but IG co-immunization with urease and LTdelta110/112 induced high titers of urease-specific local secretory IgA and systemic IgG and IgA, comparable to those induced by wild-type LT. LTS63Y showed far lower adjuvant activity towards urease than LTdelta110/112 in IG immunization, but was more active than LTdelta110/112 in inducing immune responses to urease by intranasal (IN) immunization. LTdelta110/112 predominantly enhanced the induction of urease-specific IgG1 levels following IG immunization, whereas LTS63Y induced high levels of IgG1, IgG2a and IgG2b following IN immunization. In addition, quantitative H. pylori culture of stomach tissue following challenge with H. pylori demonstrated a 90-95% reduction (p < 0.0002) in bacterial burden in mice immunized intranasally with urease using either mutant LT as an adjuvant. These results indicate that the mechanism(s) underlying the adjuvant activities of mutant LTs towards coadmnistered H. pylori urease may differ between the IN and IG mucosal immunization routes. PMID:10926118

  9. Treatment of PCR products with exonuclease I and heat-labile alkaline phosphatase improves the visibility of combined bisulfite restriction analysis

    SciTech Connect

    Watanabe, Kousuke; Emoto, Noriko; Sunohara, Mitsuhiro; Kawakami, Masanori; Kage, Hidenori; Nagase, Takahide; Ohishi, Nobuya; Takai, Daiya

    2010-08-27

    Research highlights: {yields} Incubating PCR products at a high temperature causes smears in gel electrophoresis. {yields} Smears interfere with the interpretation of methylation analysis using COBRA. {yields} Treatment with exonuclease I and heat-labile alkaline phosphatase eliminates smears. {yields} The elimination of smears improves the visibility of COBRA. -- Abstract: DNA methylation plays a vital role in the regulation of gene expression. Abnormal promoter hypermethylation is an important mechanism of inactivating tumor suppressor genes in human cancers. Combined bisulfite restriction analysis (COBRA) is a widely used method for identifying the DNA methylation of specific CpG sites. Here, we report that exonuclease I and heat-labile alkaline phosphatase can be used for PCR purification for COBRA, improving the visibility of gel electrophoresis after restriction digestion. This improvement is observed when restriction digestion is performed at a high temperature, such as 60 {sup o}C or 65 {sup o}C, with BstUI and TaqI, respectively. This simple method can be applied instead of DNA purification using spin columns or phenol/chloroform extraction. It can also be applied to other situations when PCR products are digested by thermophile-derived restriction enzymes, such as PCR restriction fragment length polymorphism (RFLP) analysis.

  10. Further characterization of Mycobacterium ulcerans toxin.

    PubMed

    Hockmeyer, W T; Krieg, R E; Reich, M; Johnson, R D

    1978-07-01

    Mycobacterium ulcerans produces an exotoxin in culture which, when inoculated into guinea pig skin, causes inflammation, necrosis, edema, and other histopathological changes resembling those in infections of humans. The toxin was resistant to heat and to alkalies and was moderately acid labile. Toxic activity was destroyed by Pronase, phospholipase, lipase, amylase, and glucosidase but not by trypsin, collagenase, cellulase, lysozyme, hyaluronidase, or neuraminidase. Toxic activity was resistant to treatment with 2-mercaptoethanol, urea, guanidine hydrochloride, p-chloromercuribenzoate, ethylenediaminetetraacetate, and sodium deoxycholate but was destroyed by sodium m-periodate and sodium dodecyl sulfate. The toxin was precipitated by a wide range of ammonium sulfate concentrations. Extraction with chlorofrom-methanol or petroleum ether destroyed its activity. Isopycnic density gradient ultracentrifugation in KBr produced a high-density lipoprotein layer with a 24-fold increase in specific activity. The results indicate that this toxin is a high-molecular-weight phospholipoprotein-polysaccharide complex. PMID:30694

  11. A pain-inducing centipede toxin targets the heat activation machinery of nociceptor TRPV1

    NASA Astrophysics Data System (ADS)

    Yang, Shilong; Yang, Fan; Wei, Ningning; Hong, Jing; Li, Bowen; Luo, Lei; Rong, Mingqiang; Yarov-Yarovoy, Vladimir; Zheng, Jie; Wang, Kewei; Lai, Ren

    2015-09-01

    The capsaicin receptor TRPV1 ion channel is a polymodal nociceptor that responds to heat with exquisite sensitivity through an unknown mechanism. Here we report the identification of a novel toxin, RhTx, from the venom of the Chinese red-headed centipede that potently activates TRPV1 to produce excruciating pain. RhTx is a 27-amino-acid small peptide that forms a compact polarized molecule with very rapid binding kinetics and high affinity for TRPV1. We show that RhTx targets the channel's heat activation machinery to cause powerful heat activation at body temperature. The RhTx-TRPV1 interaction is mediated by the toxin's highly charged C terminus, which associates tightly to the charge-rich outer pore region of the channel where it can directly interact with the pore helix and turret. These findings demonstrate that RhTx binding to the outer pore can induce TRPV1 heat activation, therefore providing crucial new structural information on the heat activation machinery.

  12. A pain-inducing centipede toxin targets the heat activation machinery of nociceptor TRPV1.

    PubMed

    Yang, Shilong; Yang, Fan; Wei, Ningning; Hong, Jing; Li, Bowen; Luo, Lei; Rong, Mingqiang; Yarov-Yarovoy, Vladimir; Zheng, Jie; Wang, KeWei; Lai, Ren

    2015-01-01

    The capsaicin receptor TRPV1 ion channel is a polymodal nociceptor that responds to heat with exquisite sensitivity through an unknown mechanism. Here we report the identification of a novel toxin, RhTx, from the venom of the Chinese red-headed centipede that potently activates TRPV1 to produce excruciating pain. RhTx is a 27-amino-acid small peptide that forms a compact polarized molecule with very rapid binding kinetics and high affinity for TRPV1. We show that RhTx targets the channel's heat activation machinery to cause powerful heat activation at body temperature. The RhTx-TRPV1 interaction is mediated by the toxin's highly charged C terminus, which associates tightly to the charge-rich outer pore region of the channel where it can directly interact with the pore helix and turret. These findings demonstrate that RhTx binding to the outer pore can induce TRPV1 heat activation, therefore providing crucial new structural information on the heat activation machinery. PMID:26420335

  13. A pain-inducing centipede toxin targets the heat activation machinery of nociceptor TRPV1

    PubMed Central

    Yang, Shilong; Yang, Fan; Wei, Ningning; Hong, Jing; Li, Bowen; Luo, Lei; Rong, Mingqiang; Yarov-Yarovoy, Vladimir; Zheng, Jie; Wang, KeWei; Lai, Ren

    2015-01-01

    The capsaicin receptor TRPV1 ion channel is a polymodal nociceptor that responds to heat with exquisite sensitivity through an unknown mechanism. Here we report the identification of a novel toxin, RhTx, from the venom of the Chinese red-headed centipede that potently activates TRPV1 to produce excruciating pain. RhTx is a 27-amino-acid small peptide that forms a compact polarized molecule with very rapid binding kinetics and high affinity for TRPV1. We show that RhTx targets the channel's heat activation machinery to cause powerful heat activation at body temperature. The RhTx–TRPV1 interaction is mediated by the toxin's highly charged C terminus, which associates tightly to the charge-rich outer pore region of the channel where it can directly interact with the pore helix and turret. These findings demonstrate that RhTx binding to the outer pore can induce TRPV1 heat activation, therefore providing crucial new structural information on the heat activation machinery. PMID:26420335

  14. Incorporation of membrane-anchored flagellin or Escherichia coli heat-labile enterotoxin B subunit enhances the immunogenicity of rabies virus-like particles in mice and dogs

    PubMed Central

    Qi, Yinglin; Kang, Hongtao; Zheng, Xuexing; Wang, Hualei; Gao, Yuwei; Yang, Songtao; Xia, Xianzhu

    2015-01-01

    Rabies remains an important worldwide public health threat, so safe, effective, and affordable vaccines are still being sought. Virus-like particle-based vaccines targeting various viral pathogens have been successfully produced, licensed, and commercialized. Here, we designed and constructed two chimeric rabies virus-like particles (cRVLPs) containing rabies virus (RABV) glycoprotein (G), matrix (M) protein, and membrane-anchored flagellin (EVLP-F) or Escherichia coli heat-labile enterotoxin B subunit (EVLP-L) as molecular adjuvants to enhance the immune response against rabies. The immunogenicity and potential of cRVLPs as novel rabies vaccine were evaluated by intramuscular vaccination in mouse and dog models. Mouse studies demonstrated that both EVLP-F and EVLP-L induced faster and larger virus-neutralizing antibodies (VNAs) responses and elicited greater numbers of CD4+ and CD8+ T cells secreting IFN-? or IL-4 compared with a standard rabies VLP (sRVLP) containing only G and M. Moreover, cRVLPs recruited and/or activated more B cells and dendritic cells in inguinal lymph nodes. EVLP-F induced a strong, specific IgG2a response but not an IgG1 response, suggesting the activation of Th1 class immunity; in contrast, Th2 class immunity was observed with EVLP-L. The significantly enhanced humoral and cellular immune responses induced by cRVLPs provided complete protection against lethal challenge with RABV. Most importantly, dogs vaccinated with EVLP-F or EVLP-L exhibited increased VNA titers in sera and enhanced IFN-? and IL-4 secretion from peripheral blood mononuclear cells. Taken together, these results illustrate that when incorporated into sRVLP, membrane-anchored flagellin, and heat-labile enterotoxin B subunit possess strong adjuvant activity. EVLP-F and EVLP-L induce significantly enhanced RABV-specific humoral and cellular immune responses in both mouse and dog. Therefore, these cRVLPs may be developed as safe and more efficacious rabies vaccine candidate for animals. PMID:25784906

  15. Shiga toxin Stx2 is heat-stable and not inactivated by pasteurization

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Shiga toxins are expressed by Escherichia coli (STEC) and are associated with food-borne diseases. Pasteurization is used to retard microbial growth in milk, and an open question is whether milk pasteurization inactivates shiga toxins. To answer this question we measure shiga toxin’s inhibition effe...

  16. Immunization with a Double-Mutant (R192G/L211A) of the Heat-Labile Enterotoxin of Escherichia coli Offers Partial Protection against Campylobacter jejuni in an Adult Mouse Intestinal Colonization Model

    PubMed Central

    Albert, M. John; Haridas, Shilpa; Ebenezer, Mathew; Raghupathy, Raj; Khan, Islam

    2015-01-01

    We have previously shown that antibodies to cholera toxin (CT) reacted with the major outer membrane proteins (MOMPs) from Campylobacter jejuni strains on Western blot. Further, oral immunization with CT significantly protected against challenge with C. jejuni in an adult mouse colonization model of infection. CT and the heat-labile enterotoxin (LT) of enterotoxigenic Escherichia coli are structurally and functionally related. LT and its mutants including the double-mutant LT (R192G/L211A) (dmLT), are powerful mucosal adjuvants. Unlike LT which is reactogenic, dmLT has been shown to be safe for human use. In the current study, we determined whether rabbit anti-dmLT antibodies reacted with MOMPs from C. jejuni strains and whether immunization with dmLT would afford protection against C. jejuni. On Western blot, the MOMPs from C. jejuni 48 (Penner serotype O:19), C. jejuni 75 (O:3) and C. jejuni 111 (O:1,44) were probed with rabbit antibodies to dmLT or LT-E112K (a non-toxic LT mutant), which showed a lack of reaction. Adult BALB/c mice were orally immunized with dmLT and orally challenged with C. jejuni 48 or 111. Protection from colonization with the challenge bacteria was studied by enumerating Campylobacter colonies in feces daily for 9 days. Vaccination produced robust serum and stool antibody responses to dmLT and no antibody responses to C. jejuni MOMP. Vaccinated mice showed reduced colonization and excretion of both challenge strains compared to control mice. However, the differences were not statistically significant. The protective efficacy of the dmLT vaccine varied from 9.1% to 54.5%. The lack of cross-reaction between the MOMP and dmLT suggests that protection is not mediated by cross-reacting antibodies, but may be due to activation of innate immunity. As dmLT is safe for humans, it could be incorporated into a C. jejuni vaccine to enhance its efficacy. PMID:26540197

  17. Analysis of Heat-Labile Sites Generated by Reactions of Depleted Uranium and Ascorbate in Plasmid DNA

    PubMed Central

    Wilson, Janice; Young, Ashley; Civitello, Edgar R.

    2013-01-01

    The goal of this study was to characterize how depleted uranium (DU) causes DNA damage. Procedures were developed to assess the ability of organic and inorganic DNA adducts to convert to single strand breaks (SSB) in pBR322 plasmid DNA in the presence of heat or piperidine. DNA adducts formed by methyl methanesulfonate (MMS), cis-platin (cis-Pt), and chromic chloride were compared to those formed by reaction of uranyl acetate (UA) and ascorbate (Asc). Uranyl ion in the presence of Asc produced U-DNA adducts that converted to SSB upon heating. Piperidine, which acted on DNA methylated by MMS to convert methyl-DNA adducts to SSB, served in the opposite fashion with U-DNA adducts by decreasing SSB. The observation that piperidine also decreased the gel shift for metal-DNA adducts formed by monofunctional cis-Pt and chromic chloride was interpreted to suggest that piperidine served to remove U-DNA adducts. Radical scavengers did not affect formation of U-induced SSB, suggesting that SSB arose from the presence of U-DNA adducts and not from free radicals. A model is proposed to predict how U-DNA adducts may serve as initial lesions that convert to SSB or AP sites. Results suggest that DU can act as a chemical genotoxin that does not require radiation for its mode of action. Characterizing the DNA lesions formed by DU is necessary to assess the relative importance of different DNA lesions in the formation of DU-induced mutations. Understanding mechanisms of formation of DU-induced mutations may contribute to identification of biomarkers of DU exposures in humans. PMID:24218036

  18. Distinctive Immunomodulatory and Inflammatory Properties of the Escherichia coli Type II Heat-Labile Enterotoxin LT-IIa and Its B Pentamer following Intradermal Administration?

    PubMed Central

    Mathias-Santos, Camila; Rodrigues, Juliana F.; Sbrogio-Almeida, Maria Elisabete; Connell, Terry D.; Ferreira, Luís C. S.

    2011-01-01

    The type I and type II heat-labile enterotoxins (LT-I and LT-II) are strong mucosal adjuvants when they are coadministered with soluble antigens. Nonetheless, data on the parenteral adjuvant activities of LT-II are still limited. Particularly, no previous study has evaluated the adjuvant effects and induced inflammatory reactions of LT-II holotoxins or their B pentameric subunits after delivery via the intradermal (i.d.) route to mice. In the present report, the adjuvant and local skin inflammatory effects of LT-IIa and its B subunit pentamer (LT-IIaB5) were determined. When coadministered with ovalbumin (OVA), LT-IIa and, to a lesser extent, LT-IIaB5 exhibited serum IgG adjuvant effects. In addition, LT-IIa but not LT-IIaB5 induced T cell-specific anti-OVA responses, particularly in respect to induction of antigen-specific cytotoxic CD8+ T cell responses. LT-IIa and LT-IIaB5 induced differential tissue permeability and local inflammatory reactions after i.d. injection. Of particular interest was the reduced or complete lack of local reactions, such as edema and tissue induration, in mice i.d. inoculated with LT-IIa and LT-IIaB5, respectively, compared with mice immunized with LT-I. In conclusion, the present results show that LT-IIa and, to a lesser extent, LT-IIaB5 exert adjuvant effects when they are delivered via the i.d. route. In addition, the low inflammatory effects of LT-IIa and LT-IIaB5 in comparison to those of LT-I support the usefulness of LT-IIa and LT-IIaB5 as parenterally delivered vaccine adjuvants. PMID:21677110

  19. Decreased Heat-Labile Opsonic Activity and Complement Levels Associated with Evidence of C3 Breakdown Products in Infected Pleural Effusions

    PubMed Central

    Lew, Pablo D.; Zubler, Rudolf; Vaudaux, Pierre; Farquet, Jean J.; Waldvogel, Francis A.; Lambert, Paul-Henri

    1979-01-01

    Heat-labile opsonic activity was measured simultaneously in serum and pleural fluid of patients with transudates, infectious exudates (with positive or negative bacterial culture) and neoplastic exudates, using two different complement-dependent phagocytic tests: the killing of Staphylococcus aureus Wood 46 variant strain (K50 opsonic titers) and the assessment of ingestion rate of endotoxin-coated paraffin particles (Oil Red 0 uptake test). K50 opsonic titers were lower in culture-positive pleural effusions as compared to culture-negative (P < 0.002) or neoplastic effusions (P < 0.002). These results were corroborated by the Oil Red 0 uptake test. The data obtained with the two assays showed a significant correlation (P < 0.001). The hemolytic activity of complement (CH50) as well as the levels of C3 breakdown product, C3d, were measured in the same sera and pleural fluid samples and in an additional group of patients with pleural effusions of the same etiology. Effusions with positive cultures showed lower CH50 values (P < 0.01) and higher C3d values (P < 0.05) when compared to culture-negative pleural fluids. Finally, evidence for immune complexes in pleural effusions and sera was looked for by determination of Clq binding activity. Levels were higher in culture-positive effusions when compared to culture-negative fluids (P = 0.005). K50 opsonic titers showed a positive correlation with CH50 values (P < 0.001) for all fluids tested. Similarly Clq binding activity correlated with C3d levels in effusions of infectious origin (P = 0.05). Recovery experiments using the various bacterial species isolated from culture-positive pleural effusions showed evidence of complement inactivation upon incubation with pooled sera at concentrations of 107-108 microorganisms/ml. These results indicate that one important reason for bacterial persistence in empyema may be decreased opsonization secondary to local consumption of complement. Images PMID:429556

  20. Quantitative analysis of bacterial toxin affinity and specificity for glycolipid receptors by surface plasmon resonance.

    PubMed

    MacKenzie, C R; Hirama, T; Lee, K K; Altman, E; Young, N M

    1997-02-28

    The primary virulence factors of many pathogenic bacteria are secreted protein toxins which bind to glycolipid receptors on host cell surfaces. The binding specificities of three such toxins for different glycolipids, mainly from the ganglioside series, were determined by surface plasmon resonance (SPR) using a liposome capture method. Unlike microtiter plate and thin layer chromatography overlay assays, the SPR/liposome methodology allows for real time analysis of toxin binding under conditions that mimic the natural cell surface venue of these interactions and without any requirement for labeling of toxin or receptor. Compared to conventional assays, the liposome technique showed more restricted oligosaccharide specificities for toxin binding. Cholera toxin demonstrated an absolute requirement for terminal galactose and internal sialic acid residues (as in GM1) with tolerance for substitution with a second internal sialic acid (as in GD1b). Escherichia coli heat-labile enterotoxin bound to GM1 and tolerated removal or extension of the internal sialic acid residue (as in asialo-GM1 and GD1b, respectively) but not substitution of the terminal galactose of GM1. Tetanus toxin showed a requirement for two internal sialic acid residues as in GD1b. Extension of terminal galactose with a single sialic acid was tolerated to some extent. The SPR analyses also yielded rate and affinity constants which are not attainable by conventional assays. Complex binding profiles were observed in that the association and dissociation rate constants varied with toxin:receptor ratios. The sub-nanomolar affinities of cholera toxin and heat-labile enterotoxin for liposome-anchored gangliosides were attributable largely to very slow dissociation rate constants. The SPR/liposome technology should have general applicability in the study of glycolipid-protein interactions and in the evaluation of reagents designed to interfere with these interactions. PMID:9038159

  1. Marine Toxins

    MedlinePLUS

    ... Contact CDC-INFO Home > Disease Listing > Marine Toxins Marine Toxins Disease Listing | General Information | Technical Information | Additional ... this and other public health problems? What are marine toxins? Marine toxins are naturally occurring chemicals that ...

  2. Local and Systemic Neutralizing Antibody Responses Induced by Intranasal Immunization with the Nontoxic Binding Domain of Toxin A from Clostridium difficile

    PubMed Central

    Ward, Stephen J.; Douce, Gill; Dougan, Gordon; Wren, Brendan W.

    1999-01-01

    Fourteen of the 38 C-terminal repeats from Clostridium difficile toxin A (14CDTA) were cloned and expressed either with an N-terminal polyhistidine tag (14CDTA-HIS) or fused to the nontoxic binding domain from tetanus toxin (14CDTA-TETC). The recombinant proteins were successfully purified by bovine thyroglobulin affinity chromatography. Both C. difficile toxin A fusion proteins bound to known toxin A ligands present on the surface of rabbit erythrocytes. Intranasal immunization of BALB/c mice with three separate 10-?g doses of 14CDTA-HIS or -TETC generated significant levels of anti-toxin A serum antibodies compared to control animals. The coadministration of the mucosal adjuvant heat labile toxin (LT) from Escherichia coli (1 ?g) significantly increased the anti-toxin A response in the serum and at the mucosal surface. Importantly, the local and systemic antibodies generated neutralized toxin A cytotoxicity. Impressive systemic and mucosal anti-toxin A responses were also seen following coadministration of 14CDTA-TETC with LTR72, an LT derivative with reduced toxicity which shows potential as a mucosal adjuvant for humans. PMID:10496886

  3. Metal Complexes and Free Radical Toxins Produced by Pfiesteria piscicida

    SciTech Connect

    Moeller,P.; Beauchesne, K.; Huncik, K.; Davis, W.; Christopher, S.; Riggs-Gelasco, P.; Gelasco, A.

    2007-01-01

    Metal-containing organic toxins produced by Pfiesteria piscicida were characterized, for the first time, by corroborating data obtained from five distinct instrumental methods: nuclear magnetic resonance spectroscopy (NMR), inductively coupled plasma mass spectrometry (ICP-MS), liquid chromatography particle beam glow discharge mass spectrometry (LC/PB-GDMS), electron paramagnetic resonance spectroscopy (EPR), and X-ray absorption spectroscopy (XAS). The high toxicity of the metal-containing toxins is due to metal-mediated free radical production. This mode of activity explains the toxicity of Pfiesteria, as well as previously reported difficulty in observing the molecular target, due to the ephemeral nature of radical species. The toxins are highly labile in purified form, maintaining activity for only 2-5 days before all activity is lost. The multiple toxin congeners in active extracts are also susceptible to decomposition in the presence of white light, pH variations, and prolonged heat. These findings represent the first formal isolation and characterization of a radical forming toxic organic-ligated metal complex isolated from estuarine/marine dinoflagellates. These findings add to an increased understanding regarding the active role of metals interacting with biological systems in the estuarine environment, as well as their links and implications to human health.

  4. Metal Complexes And Free Radical Toxins Produced By Pfiesteria Piscicida

    SciTech Connect

    Moeller, P.D.R.; Beauchesne, K.R.; Huncik, K.M.; Davis, W.C.; Christopher, S.J.; Riggs-Gelasco, P.; Gelasco, A.K.

    2009-06-03

    Metal-containing organic toxins produced by Pfiesteria piscicida were characterized, for the first time, by corroborating data obtained from five distinct instrumental methods: nuclear magnetic resonance spectroscopy (NMR), inductively coupled plasma mass spectrometry (ICPMS), liquid chromatography particle beam glow discharge mass spectrometry (LC/PB-GDMS), electron paramagnetic resonance spectroscopy (EPR), and X-ray absorption spectroscopy (XAS). The high toxicity of the metal-containing toxins is due to metal-mediated free radical production. This mode of activity explains the toxicity of Pfiesteria, as well as previously reported difficulty in observing the molecular target, due to the ephemeral nature of radical species. The toxins are highly labile in purified form, maintaining activity for only 2-5 days before all activity is lost. The multiple toxin congeners in active extracts are also susceptible to decomposition in the presence of white light, pH variations, and prolonged heat. These findings represent the first formal isolation and characterization of a radical forming toxic organic-ligated metal complex isolated from estuarine/marine dinoflagellates. These findings add to an increased understanding regarding the active role of metals interacting with biological systems in the estuarine environment, as well as their links and implications to human health.

  5. Comparison of a live attenuated Salmonella Enteritidis vaccine candidate secreting Escherichia coli heat-labile enterotoxin B subunit with a commercial vaccine for efficacy of protection against internal egg contamination by Salmonella in hens.

    PubMed

    Nandre, Rahul M; Eo, Seong Kug; Park, Sang Youel; Lee, John Hwa

    2015-07-01

    This study compared a new live attenuated Salmonella Enteritidis vaccine candidate secreting Escherichia coli heat-labile enterotoxin B subunit (SE-LTB) with a commercial Salmonella Enteritidis (SE) vaccine for efficacy of protection against SE infection in laying hens. Chickens were divided into 3 groups of 20 each. Group A chickens were inoculated orally with phosphate-buffered saline and served as controls, group B chickens were inoculated orally with the vaccine candidate, and group C chickens were inoculated intramuscularly with a commercial vaccine, the primary inoculation in groups B and C being at 10 wk of age and the booster at 16 wk. Groups B and C showed significantly higher titers of plasma immunoglobulin G, intestinal secretory immunoglobulin A, and egg yolk immunoglobulin Y antibodies compared with the control group, and both vaccinated groups showed a significantly elevated cellular immune response. After virulent challenge, group B had significantly lower production of thin-shelled and/or malformed eggs and a significantly lower rate of SE contamination of eggs compared with the control group. Furthermore, the challenge strain was detected significantly less in all of the examined organs of group B compared with the control group. Group C had lower gross lesion scores only in the spleen and had lower bacterial counts only in the spleen, ceca, and ovary. These findings indicate that vaccination with the SE-LTB vaccine candidate can efficiently reduce internal egg and internal organ contamination by Salmonella and has advantages over the commercial vaccine. PMID:26130857

  6. Comparison of a live attenuated Salmonella Enteritidis vaccine candidate secreting Escherichia coli heat-labile enterotoxin B subunit with a commercial vaccine for efficacy of protection against internal egg contamination by Salmonella in hens

    PubMed Central

    Nandre, Rahul M.; Eo, Seong Kug; Park, Sang Youel; Lee, John Hwa

    2015-01-01

    This study compared a new live attenuated Salmonella Enteritidis vaccine candidate secreting Escherichia coli heat-labile enterotoxin B subunit (SE-LTB) with a commercial Salmonella Enteritidis (SE) vaccine for efficacy of protection against SE infection in laying hens. Chickens were divided into 3 groups of 20 each. Group A chickens were inoculated orally with phosphate-buffered saline and served as controls, group B chickens were inoculated orally with the vaccine candidate, and group C chickens were inoculated intramuscularly with a commercial vaccine, the primary inoculation in groups B and C being at 10 wk of age and the booster at 16 wk. Groups B and C showed significantly higher titers of plasma immunoglobulin G, intestinal secretory immunoglobulin A, and egg yolk immunoglobulin Y antibodies compared with the control group, and both vaccinated groups showed a significantly elevated cellular immune response. After virulent challenge, group B had significantly lower production of thin-shelled and/or malformed eggs and a significantly lower rate of SE contamination of eggs compared with the control group. Furthermore, the challenge strain was detected significantly less in all of the examined organs of group B compared with the control group. Group C had lower gross lesion scores only in the spleen and had lower bacterial counts only in the spleen, ceca, and ovary. These findings indicate that vaccination with the SE-LTB vaccine candidate can efficiently reduce internal egg and internal organ contamination by Salmonella and has advantages over the commercial vaccine. PMID:26130857

  7. Evaluation of the immunogenicity of a transgenic tobacco plant expressing the recombinant fusion protein of GP5 of porcine reproductive and respiratory syndrome virus and B subunit of Escherichia coli heat-labile enterotoxin in pigs.

    PubMed

    Chia, Min-Yuan; Hsiao, Shih-Hsuan; Chan, Hui-Ting; Do, Yi-Yin; Huang, Pung-Ling; Chang, Hui-Wen; Tsai, Yi-Chieh; Lin, Chun-Ming; Pang, Victor Fei; Jeng, Chian-Ren

    2011-04-15

    Escherichia coli heat-labile enterotoxin B subunit (LTB) can be used as an adjuvant for co-administered antigens. Our previous study showed that the expression of neutralizing epitope GP5 of porcine reproductive and respiratory syndrome virus (PRRSV) in transgenic tobacco plant (GP5-T) could induce PRRSV-specific immune responses in pigs. A transgenic tobacco plant co-expressing LTB and PRRSV GP5 as a fusion protein (LTB-GP5-T) was further constructed and its immunogenicity was evaluated. Pigs were given orally three consecutive doses of equal concentration of recombinant GP5 protein expressed in leaves of LTB-GP5-T or GP5-T at a 2-week interval and challenged with PRRSV at 7 weeks post-initial immunization. Pigs receiving LTB-GP5-T or GP5-T developed PRRSV-specific antibody- and cell-mediated immunity and showed significantly lower viremia and tissue viral load and milder lung lesions than wild type tobacco plant (W-T). The LTB-GP5-T-treated group had relatively higher immune responses than the GP5-T-treated group, although the differences were not statistically significant. PMID:21277027

  8. Protection against Helicobacter pylori infection in mice by intragastric vaccination with H. pylori antigens is achieved using a non-toxic mutant of E. coli heat-labile enterotoxin (LT) as adjuvant.

    PubMed

    Marchetti, M; Rossi, M; Giannelli, V; Giuliani, M M; Pizza, M; Censini, S; Covacci, A; Massari, P; Pagliaccia, C; Manetti, R; Telford, J L; Douce, G; Dougan, G; Rappuoli, R; Ghiara, P

    1998-01-01

    We have previously shown that infection of mice with H. pylori can be prevented by oral immunization with H. pylori antigens given together with E. coli heat-labile enterotoxin (LT) as adjuvant. Since LT cannot be used in humans because of its unacceptable toxicity, we investigated whether protection of mice could be achieved by co-administration of antigens with non-toxic LT mutants. Here we show that CD1/SPF mice are protected against infection after oral vaccination with either purified H. pylori antigens (native and recombinant VacA, urease and CagA), or whole-cell vaccine formulations, given together with the non-toxic mutant LTK63 as a mucosal adjuvant. Furthermore we show that such protection is antigen-specific since immunization with recombinant or native VacA plus LTK63 conferred protection against infection by an H. pylori Type I strain, which expresses VacA, but not against challenge with a Type II strain which is not able to express this antigen. These results show that: (1) protection against H. pylori can be achieved in the mouse model of infection using subunit recombinant constructs plus non-toxic mucosal adjuvants; and (2) this mouse model is an useful tool in testing H. pylori vaccine formulations for eventual use in humans. PMID:9607006

  9. Comparison of the mechanisms of action of cholera toxin and the heat-stable enterotoxins of Escherichia coli.

    PubMed Central

    Peterson, J W; Whipp, S C

    1995-01-01

    The mechanisms which enable cholera toxin (CT) and the Escherichia coli heat-stable enterotoxins (STa and STb) to stimulate intestinal secretion of water and electrolytes are only partially understood. CT evokes the synthesis of 3',5'-cyclic AMP (cAMP), and STa is known to elevate intestinal levels of 3',5'-cyclic GMP (cGMP). Neither of these recognized second messengers appears to mediate E. coli STb responses. We compared the secretory effects of CT, STa, and STb using the pig intestinal loop model and also measured the effects of toxin challenge on the synthesis of cAMP, cGMP, and prostaglandins (e.g., prostaglandin E2 [PGE2]), as well as on the release of 5-hydroxytryptamine (5-HT) from intestinal enterochromaffin cells. All three enterotoxins elicited fluid accumulation within a 2-h observation period. A combination of maximal doses of STa with STb yielded additive effects on fluid accumulation, which suggested different mechanisms of action for these toxins. Similarly, challenge of pig intestinal loops with a combination of CT and STb resulted in additive effects on fluid accumulation and luminal release of 5-HT. Unlike its effect on intestinal tissues from other animals, CT did not appear to elicit a dose-dependent cAMP response measurable in mucosal extracts from pig small intestine. In contrast, luminal fluid from CT-challenged pig intestinal loops contained dose-related amounts of cAMP and PGE2 that had been secreted from the mucosa. cAMP responses to STa or STb could not be demonstrated in either mucosal tissue or luminal fluid. In contrast, cGMP levels were increased in the intestinal fluid of loops challenged with STa but not in those challenged with STb. While the mechanisms of action of CT and STa are thought to involve impulse transmission via the enteric nervous system, we demonstrated significant stimulation of PGE2 synthesis and 5-HT release for CT and STb but very little for STa. We conclude from these data that the mechanisms of action of STa, STb, and CT are distinct, although the mode of action of STb may have some similarity to that of CT. Since STb stimulated the release of both PGE2 and 5-HT from the intestinal mucosa, the data suggested the potential for an effect of STb on the enteric nervous system. PMID:7890409

  10. Cholera toxin B subunits assemble into pentamers--proposition of a fly-casting mechanism.

    PubMed

    Zrimi, Jihad; Ng Ling, Alicia; Giri-Rachman Arifin, Ernawati; Feverati, Giovanni; Lesieur, Claire

    2010-01-01

    The cholera toxin B pentamer (CtxB(5)), which belongs to the AB(5) toxin family, is used as a model study for protein assembly. The effect of the pH on the reassembly of the toxin was investigated using immunochemical, electrophoretic and spectroscopic methods. Three pH-dependent steps were identified during the toxin reassembly: (i) acquisition of a fully assembly-competent fold by the CtxB monomer, (ii) association of CtxB monomer into oligomers, (iii) acquisition of the native fold by the CtxB pentamer. The results show that CtxB(5) and the related heat labile enterotoxin LTB(5) have distinct mechanisms of assembly despite sharing high sequence identity (84%) and almost identical atomic structures. The difference can be pinpointed to four histidines which are spread along the protein sequence and may act together. Thus, most of the toxin B amino acids appear negligible for the assembly, raising the possibility that assembly is driven by a small network of amino acids instead of involving all of them. PMID:21203571

  11. Treponema pallidum 3-phosphoglycerate mutase is a heat-labile enzyme that may limit the maximum growth temperature for the spirochete.

    PubMed

    Benoit, S; Posey, J E; Chenoweth, M R; Gherardini, F C

    2001-08-01

    In the causative agent of syphilis, Treponema pallidum, the gene encoding 3-phosphoglycerate mutase, gpm, is part of a six-gene operon (tro operon) that is regulated by the Mn-dependent repressor TroR. Since substrate-level phosphorylation via the Embden-Meyerhof pathway is the principal way to generate ATP in T. pallidum and Gpm is a key enzyme in this pathway, Mn could exert a regulatory effect on central metabolism in this bacterium. To study this, T. pallidum gpm was cloned, Gpm was purified from Escherichia coli, and antiserum against the recombinant protein was raised. Immunoblots indicated that Gpm was expressed in freshly extracted infective T. pallidum. Enzyme assays indicated that Gpm did not require Mn(2+) while 2,3-diphosphoglycerate (DPG) was required for maximum activity. Consistent with these observations, Mn did not copurify with Gpm. The purified Gpm was stable for more than 4 h at 25 degrees C, retained only 50% activity after incubation for 20 min at 34 degrees C or 10 min at 37 degrees C, and was completely inactive after 10 min at 42 degrees C. The temperature effect was attenuated when 1 mM DPG was added to the assay mixture. The recombinant Gpm from pSLB2 complemented E. coli strain PL225 (gpm) and restored growth on minimal glucose medium in a temperature-dependent manner. Increasing the temperature of cultures of E. coli PL225 harboring pSLB2 from 34 to 42 degrees C resulted in a 7- to 11-h period in which no growth occurred (compared to wild-type E. coli). These data suggest that biochemical properties of Gpm could be one contributing factor to the heat sensitivity of T. pallidum. PMID:11466272

  12. Labile neurotoxin in serum of calves with "nervous" coccidiosis.

    PubMed Central

    Isler, C M; Bellamy, J E; Wobeser, G A

    1987-01-01

    Mouse inoculation was used to test for the presence of a toxin in the serum, cerebrospinal fluid, and intestinal contents collected from cases of bovine enteric coccidiosis, with and without neurological signs, and from control calves. Intravenous inoculation of mice with 10 mL/kg of serum from calves showing nervous signs caused effects significantly different from those caused by the inoculation of serum from calves not showing nervous signs and from control calves. The effect was particularly evident in female mice. At this dosage severe neurological signs such as loss of righting reflex, seizures and death occurred only with serum from calves with "nervous coccidiosis". The results suggest that serum from the calves with neurological signs contains a neurotoxin. This toxin appears to be highly labile. It was not present in the cerebrospinal fluid at levels comparable to those in the serum. The significance of this labile neurotoxin with respect to the pathogenesis of the neurological signs associated with bovine enteric coccidiosis is unknown. PMID:2955865

  13. Structure of the cholera toxin secretion channel in its closed state

    PubMed Central

    Reichow, Steve L.; Korotkov, Konstantin V.; Hol, Wim G. J.; Gonen, Tamir

    2010-01-01

    The type II secretion system (T2SS) is a macromolecular complex spanning the inner and outer membranes of Gram-negative bacteria. Remarkably, the T2SS secretes folded proteins including multimeric assemblies like cholera toxin and heat-labile enterotoxin from Vibrio cholerae and enterotoxigenic Escherichia coli, respectively. The major outer membrane T2SS protein is the “secretin” GspD. Electron cryomicroscopy reconstruction of the V. cholerae secretin at 19 Å resolution reveals a dodecameric structure reminiscent of a barrel with a large channel at its center that appears to contain a closed periplasmic gate. The GspD periplasmic domain forms a vestibule with a conserved constriction, and binds to a pentameric exoprotein and to the trimeric tip of the T2SS pseudopilus. By combining our results with structures of the cholera toxin and T2SS pseudopilus, we provide a structural basis for a possible secretion mechanism of the T2SS. PMID:20852644

  14. Structure–activity correlations of variant forms of the B pentamer of Escherichia coli type II heat-labile enterotoxin LT-IIb with Toll-like receptor 2 binding

    SciTech Connect

    Cody, Vivian; Pace, Jim; Nawar, Hesham F.; King-Lyons, Natalie; Liang, Shuang; Connell, Terry D.; Hajishengallis, George

    2012-12-01

    Structural data for the S74D variant of the pentameric B subunit of type II heat-labile enterotoxin of Escherichia coli reveal a smaller pore opening that may explain its reduced Toll-like receptor binding affinity compared to that of the wild type enterotoxin. The explanation for the enhanced Toll-like receptor binding affinity of the S74A variant is more complex than simply being attributed to the pore opening. The pentameric B subunit of the type II heat-labile enterotoxin of Escherichia coli (LT-IIb-B{sub 5}) is a potent signaling molecule capable of modulating innate immune responses. It has previously been shown that LT-IIb-B{sub 5}, but not the LT-IIb-B{sub 5} Ser74Asp variant [LT-IIb-B{sub 5}(S74D)], activates Toll-like receptor (TLR2) signaling in macrophages. Consistent with this, the LT-IIb-B{sub 5}(S74D) variant failed to bind TLR2, in contrast to LT-IIb-B{sub 5} and the LT-IIb-B{sub 5} Thr13Ile [LT-IIb-B{sub 5}(T13I)] and LT-IIb-B{sub 5} Ser74Ala [LT-IIb-B{sub 5}(S74A)] variants, which displayed the highest binding activity to TLR2. Crystal structures of the Ser74Asp, Ser74Ala and Thr13Ile variants of LT-IIb-B{sub 5} have been determined to 1.90, 1.40 and 1.90 Å resolution, respectively. The structural data for the Ser74Asp variant reveal that the carboxylate side chain points into the pore, thereby reducing the pore size compared with that of the wild-type or the Ser74Ala variant B pentamer. On the basis of these crystallographic data, the reduced TLR2-binding affinity of the LT-IIb-B{sub 5}(S74D) variant may be the result of the pore of the pentamer being closed. On the other hand, the explanation for the enhanced TLR2-binding activity of the LT-IIb-B{sub 5}(S74A) variant is more complex as its activity is greater than that of the wild-type B pentamer, which also has an open pore as the Ser74 side chain points away from the pore opening. Data for the LT-IIb-B{sub 5}(T13I) variant show that four of the five variant side chains point to the outside surface of the pentamer and one residue points inside. These data are consistent with the lack of binding of the LT-IIb-B{sub 5}(T13I) variant to GD1a ganglioside.

  15. The Divergent CD8+ T Cell Adjuvant Properties of LT-IIb and LT-IIc, Two Type II Heat-Labile Enterotoxins, Are Conferred by Their Ganglioside-Binding B Subunits

    PubMed Central

    Hu, John C.; Greene, Christopher J.; King-Lyons, Natalie D.; Connell, Terry D.

    2015-01-01

    Poor immune responses elicited by vaccine antigens can be enhanced by the use of appropriate adjuvants. Type II heat-labile enterotoxins (HLT) produced by Escherichia coli are extremely potent adjuvants that augment both humoral and cellular immunity to co-administered antigens. Recent findings demonstrate that LT-IIb and LT-IIc, two type II HLT adjuvants, exhibit potent, yet distinguishable CD8+ T cell adjuvant properties. While LT-IIc elicits a robust and rapid response at one week after administration, LT-IIb engenders a more gradual and slower expansion of antigen-specific CD8+ T cells that correlates with improved immunity. The variations in immune effects elicited by the HLT adjuvants have been generally attributed to their highly divergent B subunits that mediate binding to various gangliosides on cell surfaces. Yet, HLT adjuvants with point mutations in the B subunit that significantly alter ganglioside binding retain similar adjuvant functions. Therefore, the contribution of the B subunits to adjuvanticity remains unclear. To investigate the influence of the B subunits on the enhancement of immune responses by LT-IIb and LT-IIc, chimeric HLT were engineered in which the B subunits of the two adjuvants were exchanged. Comparing the immune potentiating characteristics of both native and chimeric HLT adjuvants, it was found that not all the adjuvant characteristics of the HLT adjuvants were modulated by the respective B subunits. Specifically, the differences in the CD8+ T cell kinetics and protective responses elicited by LT-IIb and LT-IIc did indeed followed their respective B subunits. However, induction of IL-1 from macrophages and the capacity to intoxicate cells in a mouse Y1 adrenal cell bioassay did not correlate with the B subunits. Therefore, it is likely that additional factors other than the B subunits contribute to the effects elicited by the HLT adjuvants. PMID:26565800

  16. Millipede toxin

    MedlinePLUS

    ... Certain types of millipedes release a harmful substance (toxin) if they are threatened or if you handle ... are exceptionally well-endowed with defensive chemical secretions (toxins or poisons) that effectively deter most predators. Some ...

  17. Intranasal immunogenicity and adjuvanticity of site-directed mutant derivatives of cholera toxin.

    PubMed

    Douce, G; Fontana, M; Pizza, M; Rappuoli, R; Dougan, G

    1997-07-01

    Genetically modified derivatives of cholera toxin (CT), harboring a single amino acid substitution in and around the NAD binding cleft of the A subunit, were isolated following site-directed mutagenesis of the ctxA gene. Two mutants of CT, designated CTS106 (with a proline-to-serine change at position 106) and CTK63 (with a serine-to-lysine change at position 63), were found to have substantially reduced ADP-ribosyltransferase activity and toxicity; CTK63 was completely nontoxic in all assays, whereas CTS106 was 10(4) times less toxic than wild-type CT. The mucosal adjuvanticity and immunogenicity of derivatives of CT were assessed by intranasal immunization of mice, with either ovalbumin or fragment C of tetanus toxin as a bystander antigen. Mice immunized with wild-type CT produced both local (immunoglobulin A in mucosal washes) and systemic immune responses to both CT and bystander antigens. CTS106 showed good local and systemic responses to bystander proteins and to itself. Interestingly, mice immunized with the nontoxic derivative of CT, CTK63, generated weak immune responses to the bystander antigens which were similar to those achieved when CT B subunit was used as an adjuvant. In parallel experiments, an equivalent nontoxic mutant of the Escherichia coli heat-labile enterotoxin, LTK63 (with a serine-to-lysine change at position 63), was tested (9). In contrast to CTK63, LTK63 was found to be more immunogenic and a better intranasal adjuvant than recombinant heat-labile enterotoxin B subunit or CTK63. This information, together with data on immunoglobulin subclass responses, suggests that although highly homologous, CT and heat-labile enterotoxin should not be considered biologically identical in terms of their ability to act as intranasal adjuvants. PMID:9199455

  18. Characterization of Immunological Cross-Reactivity between Enterotoxigenic Escherichia coli Heat-Stable Toxin and Human Guanylin and Uroguanylin

    PubMed Central

    Taxt, Arne M.; Diaz, Yuleima; Bacle, Amélie; Grauffel, Cédric; Reuter, Nathalie; Aasland, Rein; Sommerfelt, Halvor

    2014-01-01

    Enterotoxigenic Escherichia coli (ETEC) expressing the heat-stable toxin (ST) (human-type [STh] and porcine-type [STp] variants) is among the five most important enteric pathogens in young children living in low- and middle-income countries. ST mediates diarrheal disease through activation of the guanylate cyclase C (GC-C) receptor and is an attractive vaccine target with the potential to confer protection against a wide range of ETEC strains. However, immunological cross-reactivity to the endogenous GC-C ligands guanylin and uroguanylin is a major concern because of the similarities to ST in amino acid sequence, structure, and function. We have investigated the presence of similar epitopes on STh, STp, guanylin, and uroguanylin by analyzing these peptides in eight distinct competitive enzyme-linked immunosorbent assays (ELISAs). A fraction (27%) of a polyclonal anti-STh antibody and an anti-STh monoclonal antibody (MAb) cross-reacted with uroguanylin, the latter with a 73-fold-lower affinity. In contrast, none of the antibodies raised against STp, one polyclonal antibody and three MAbs, cross-reacted with the endogenous peptides. Antibodies raised against guanylin and uroguanylin showed partial cross-reactivity with the ST peptides. Our results demonstrate, for the first time, that immunological cross-reactions between ST and the endogenous peptides can occur. However, the partial nature and low affinity of the observed cross-reactions suggest that the risk of adverse effects from a future ST vaccine may be low. Furthermore, our results suggest that this risk may be reduced or eliminated by basing an ST immunogen on STp or a selectively mutated variant of STh. PMID:24778111

  19. A toxin-antitoxin system encoded by the Xylella fastidiosa chromosome regulates growth

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bacteria encode toxin-antitoxin (TA) systems consisting of a stable toxin and a cognate labile antitoxin. When encoded by a plasmid, TA systems confer stable plasmid inheritance. When encoded by the chromosome, TA systems may confer advantageous responses to environmental stress. The chromosome of...

  20. Pertussis toxin

    SciTech Connect

    Sekura, R.D.; Moss, J.; Vaughan, M.

    1985-01-01

    This book contains 13 selections. Some of the titles are: Genetic and Functional Studies of Pertussis Toxin Substrates; Effect of Pertussis Toxin on the Hormonal Responsiveness of Different Tissues; Extracellular Adenylate Cyclase of Bordetella pertussis; and GTP-Regulatory Proteins are Introcellular Messagers: A Model for Hormone Action.

  1. Heat treatment and the use of additives to improve the stability of paralytic shellfish poisoning toxins in shellfish tissue reference materials for internal quality control and proficiency testing.

    PubMed

    Burrell, Stephen; Clion, Valentin; Auroy, Virginie; Foley, Barry; Turner, Andrew D

    2015-06-01

    The need for homogenous reference materials stable for paralytic shellfish toxins is vital for the monitoring and quality assurance of these potent neurotoxins in shellfish. Two stabilisation techniques were investigated, heat treatment through autoclaving and the addition of preserving additives into the tissue matrix. Short and long-term stability experiments as well as homogeneity determination were conducted on materials prepared by both techniques in comparison with an untreated control using two LC-FLD methods. Both techniques improved the stability of the matrix and the PSP toxins present compared to the controls. A material was prepared using the combined techniques of heat treatment followed by spiking with additives and data is presented from this optimised reference material as used over a two year period in the Irish national monitoring program and in a development exercise as part of a proficiency testing scheme operated by QUASIMEME (Quality Assurance of Information for Marine Environmental Monitoring in Europe) since 2011. The results were indicative of the long-term stability of the material as evidenced through consistent assigned values in the case of the proficiency testing scheme and a low relative standard deviation of 10.5% for total toxicity data generated over 24 months. PMID:25816999

  2. Botulinum Toxin Therapy

    MedlinePLUS

    ... Diseases and treatments A - D Botulinum toxin Botulinum toxin therapy Also called botulinum rejuvenation Brand names: Botox® ... what your policy covers. Learn more about botulinum toxin therapy: Is botulinum toxin therapy the right choice ...

  3. BOTULINUM TOXIN

    PubMed Central

    Nigam, P K; Nigam, Anjana

    2010-01-01

    Botulinum toxin, one of the most poisonous biological substances known, is a neurotoxin produced by the bacterium Clostridium botulinum. C. botulinum elaborates eight antigenically distinguishable exotoxins (A, B, C1, C2, D, E, F and G). All serotypes interfere with neural transmission by blocking the release of acetylcholine, the principal neurotransmitter at the neuromuscular junction, causing muscle paralysis. The weakness induced by injection with botulinum toxin A usually lasts about three months. Botulinum toxins now play a very significant role in the management of a wide variety of medical conditions, especially strabismus and focal dystonias, hemifacial spasm, and various spastic movement disorders, headaches, hypersalivation, hyperhidrosis, and some chronic conditions that respond only partially to medical treatment. The list of possible new indications is rapidly expanding. The cosmetological applications include correction of lines, creases and wrinkling all over the face, chin, neck, and chest to dermatological applications such as hyperhidrosis. Injections with botulinum toxin are generally well tolerated and side effects are few. A precise knowledge and understanding of the functional anatomy of the mimetic muscles is absolutely necessary to correctly use botulinum toxins in clinical practice. PMID:20418969

  4. [Marine toxins].

    PubMed

    Lueger, A; Scherr, D; Lang, B; Brodmann, M; Stark, G

    1999-01-01

    The consumption of seafood, which is contaminated by toxines of red tides, is a common cause of disease in tropic regions. The most important diseases, which are caused by red tides are Paralytic Shellfish Poisoning (PSP), Diarrhetic Shellfish Poisoning (DSP), Neurotoxic Shellfish Poisoning (NSP), Amnesic Shellfish Poisoning (ASP), Ciguatera Fish Poisoning (CFP). PMID:11315409

  5. Lability of Humic-Bound Phosphorus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Phosphorus (P) has long been known to be present in humic substances from various sources. However, information on the lability of humic-bound P is very limited although such information is critical for understanding the role of humic substances in P cycling and nutrition. In this presentation, we d...

  6. Biologically labile photoproducts from riverine non-labile dissolved organic carbon in the coastal waters

    NASA Astrophysics Data System (ADS)

    Kasurinen, V.; Aarnos, H.; Vähätalo, A.

    2015-06-01

    In order to assess the production of biologically labile photoproducts (BLPs) from non-labile riverine dissolved organic carbon (DOC), we collected water samples from ten major rivers, removed labile DOC and mixed the residual non-labile DOC with artificial seawater for microbial and photochemical experiments. Bacteria grew on non-labile DOC with a growth efficiency of 11.5% (mean; range from 3.6 to 15.3%). Simulated solar radiation transformed a part of non-labile DOC into BLPs, which stimulated bacterial respiration and production, but did not change bacterial growth efficiency (BGE) compared to the non-irradiated dark controls. In the irradiated water samples, the amount of BLPs stimulating bacterial production depended on the photochemical bleaching of chromophoric dissolved organic matter (CDOM). The apparent quantum yields for BLPs supporting bacterial production ranged from 9.5 to 76 (mean 39) (?mol C mol photons-1) at 330 nm. The corresponding values for BLPs supporting bacterial respiration ranged from 57 to 1204 (mean 320) (?mol C mol photons-1). According to the calculations based on spectral apparent quantum yields and local solar radiation, the annual production of BLPs ranged from 21 (St. Lawrence) to 584 (Yangtze) mmol C m-2 yr-1 in the plumes of the examined rivers. Complete photobleaching of riverine CDOM in the coastal ocean was estimated to produce 10.7 Mt C BLPs yr-1 from the rivers examined in this study and globally 38 Mt yr-1 (15% of riverine DOC flux from all rivers), which support 4.1 Mt yr-1 of bacterial production and 33.9 Mt yr-1 bacterial respiration.

  7. The 2.3 {angstrom} crystal structure of cholera toxin B subunit pentamer: Choleragenoid

    SciTech Connect

    Zhang, Rong-Guang; Westbrook, M.L.; Maulik, P.R.; Reed, R.A.; Shipley, G.; Westbrook, E.M.; Scott, D.L.; Otwinowski, Z.

    1996-02-01

    Cholera toxin, a heterohexameric AB{sub 5} enterotoxin released by Vibrio cholera, induces a profuse secretory diarrhea in susceptible hosts. Choleragenoid, the B subunit pentamer of cholera toxin, directs the enzymatic A subunit to its target by binding to GM{sub 1} gangliosides exposed on the luminal surface of intestinal epithelial cells. We have solved the crystal structure of choleragenoid at 2.3 {Angstrom} resolution by combining single isomorphous replacement with non-crystallographic symmetry averaging. The structure of the B subunits, and their pentameric arrangement, closely resembles that reported for the intact holotoxin (choleragen), the heat-labile enterotoxin from E. coli, and for a choleragenoid-GM{sub 1} pentasaccharide complex. In the absence of the A subunit the central cavity of the B pentamer is a highly solvated channel. The binding of the A subunit or the receptor pentasaccharide to choleragenoid has only a modest effect on the local stereochemistry and does not perceptibly alter the subunit interface.

  8. Mucosal immunization with helicobacter, CpG DNA, and cholera toxin is protective.

    PubMed

    Jiang, Weiwen; Baker, Henry J; Smith, Bruce F

    2003-01-01

    The mucosal delivery of antigens requires an effective adjuvant to induce mucosal immunity. Current mucosal adjuvants include cholera toxin (CT) and Escherichia coli heat-labile toxin. Unmethylated CpG immunostimulatory oligodeoxynucleotides (ODNs) have been proposed as novel mucosal adjuvants. In this study, mice were immunized with sonicated Helicobacter felis with CT and/or CpG ODN adjuvants. All groups receiving either adjuvant singly or in combination developed increased serum anti-H. felis immunoglobulin G (IgG). The addition of either CpG or CT, or both, produced a specific fecal anti-H. felis IgA response, with the highest IgA levels occurring in animals immunized intranasally with sonicated H. felis with CT and CpG. Following H. felis challenge, addition of the adjuvant CpG ODN provided no significant protection, while groups given CT showed a high degree of protection, although not complete. When CpG ODN was combined with CT and the vaccine combination was delivered intranasally, no bacterial colonization was detected by quantitative PCR, providing "sterile immunity" and demonstrating synergy between CpG ODN and CT. PMID:12496147

  9. Theta-toxin of Clostridium perfringens. I. Purification and some properties.

    PubMed

    Yamakawa, Y; Ito, A; Sato, H

    1977-10-26

    Theta-Toxin, an oxygen-labile hemolysin produced by Clostridium perfringens, was purified 3300 fold from culture filtrate by successive chromatography on DEAE-Sephadex A-50 and Sephadex G-150. The purified toxin gave two distinct bands in disc electrophoresis, while the same material, after mild reduction with dithiothreitol, yielded a single band, indicating that the purified theta-toxin contained, as well as a reduced, active form, an oxidized, inactive form of toxin. These two forms of the toxin had a similar, if not identical molecular size. The purified preparation gave a single band in a sodium dodecyl sulfate polyacrylamide gel electrophoresis and formed a single precipitin line with National Standard gas gangrene (C. perfringens) antitoxin. By sodium dodecyl sulfate polyacrylamide gel electrophoresis, the molecular weight of theta-toxin was estimated to be 51 000, the value being in exact accordance with that obtained by amino acid analysis. The amino acid composition of theta-toxin was very close to that of cereolysin, an oxygen-labile hemolysin produced by Bacillus cereus. The amino-terminal residue of theta-toxin was lysine as determined by the Dansyl method. PMID:199270

  10. Orotic aciduria fibroblasts express a labile form of UMP synthase.

    PubMed

    Perry, M E; Jones, M E

    1989-09-15

    Orotic aciduria (type 1) results from a mutation in the gene for UMP synthase, a bifunctional protein containing the two enzyme activities which convert orotic acid and 5-phosphoribosyl-1-pyrophosphate to UMP and CO2. In fibroblasts from individuals with orotic aciduria, these two enzymatic activities are about 1% of normal but increase dramatically when deficient cells are grown in the presence of 6-azauridine. Using a polyclonal antiserum to sodium dodecyl sulfate-denatured, pure human UMP synthase, we show that fibroblasts from a patient with orotic aciduria have a low level of immunoreactive UMP synthase protein. Pulse-chase analysis reveals that the UMP synthase is degraded rapidly in the deficient cells. Growth of deficient cells in 6-azauridine leads to an increase in UMP synthase protein and its two enzymatic activities via a decreased rate of proteolytic degradation of UMP synthase. UMP synthase in extracts from deficient cells is more readily denatured by heat and is stabilized after growth of cells in 6-azauridine. These data suggest that the detrimental deficiency of this one patient results from a structurally altered UMP synthase that is probably present in low steady-state amounts due to proteolysis and that this labile protein can be stabilized against heat denaturation and proteolytic degradation by 6-aza-UMP. PMID:2475503

  11. Fate and lability of silver in soils: Effect of ageing

    EPA Science Inventory

    The fate and lability of added soluble Ag in soils over time was examined by measurement of labile metal (E-value) by isotopic dilution using the 110mAg radioactive isotope and the solid-phase speciation of Ag by X-ray absorption near edge structure (XANES) spectrosco...

  12. Botox (Botulinum Toxin)

    MedlinePLUS

    ... people when there are many effective and safe cosmetic procedures that can temporarily reduce a very prominent ... form of botulinum toxin is Type A (Botox® Cosmetic, Allergan, Inc). Botulinum toxin, what we will now ...

  13. *CYANOBACTERIA AND THEIR TOXINS

    EPA Science Inventory

    Cyanobacteria, or blue-green algae, are naturally-occurring contaminants of surface waters worldwide. These photosynthesizing prokaryotes thrive in warm, shallow, nutrient-rich waters. Many produce potent toxins as secondary metabolites. Cyanobacteria toxins have been document...

  14. Detection of Protein Toxins

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We have focused on ricin, shiga-like toxin, botulinum neurotoxin (BoNT), and staphylococcal enterotoxin A (SEA), developing sensitive test methods for toxins and marker compounds in food matrices. Although animal models provide the best means for risk assessment, especially for crude toxins in compl...

  15. Bioterrorism: toxins as weapons.

    PubMed

    Anderson, Peter D

    2012-04-01

    The potential for biological weapons to be used in terrorism is a real possibility. Biological weapons include infectious agents and toxins. Toxins are poisons produced by living organisms. Toxins relevant to bioterrorism include ricin, botulinum, Clostridium perfrigens epsilson toxin, conotoxins, shigatoxins, saxitoxins, tetrodotoxins, mycotoxins, and nicotine. Toxins have properties of biological and chemical weapons. Unlike pathogens, toxins do not produce an infection. Ricin causes multiorgan toxicity by blocking protein synthesis. Botulinum blocks acetylcholine in the peripheral nervous system leading to muscle paralysis. Epsilon toxin damages cell membranes. Conotoxins block potassium and sodium channels in neurons. Shigatoxins inhibit protein synthesis and induce apoptosis. Saxitoxin and tetrodotoxin inhibit sodium channels in neurons. Mycotoxins include aflatoxins and trichothecenes. Aflatoxins are carcinogens. Trichothecenes inhibit protein and nucleic acid synthesis. Nicotine produces numerous nicotinic effects in the nervous system. PMID:22523138

  16. Characterization of mutant strains producing pertussis toxin cross reacting materials.

    PubMed

    Sato, Y; Sato, H; Chazono, M; Ginnaga, A; Tamura, C

    1991-01-01

    We have isolated 120 mutant strains producing pertussis toxin (PT) cross reacting materials (CRMs) from B. pertussis, strain Tohama, phase I by nitrosoguanidine treatment. Strains producing higher PT tend to show higher virulence in mice. No direct correlation between the virulence and other factors, such as filamentous hemagglutinin, adenylate cyclase or dermonecrotic heat labile toxin, was found. Most CRMs were less reactive to the anti-S1 monoclonal antibody, 1B7. When the PT CRMs produced by strains 69D, 74E or 79G, which were less or non-toxic, were mixed with A protomer purified from native PT, the PT activity assayed by clustering of CHO-cells increased significantly, but not when they were mixed with B oligomer. These CRMs may be composed of defective S1 and intact S2, S3, S4 and S5. Molecular sizes of PT CRMs outside and inside the cells were analysed by sucrose density gradient centrifugation. The sizes of the CRMs were in the range of 10K to 210K, but the biological activity of PT was detected at only the same molecular size, 106 K, as native PT. The majority of the CRM was released into culture medium if all five subunits were assembled; otherwise they accumulated inside the cell without completion of assembly to form the hexamer in the PT-form. One of the non-toxic mutants named 79G showed one point mutation from G to A at the 730th base from the Eco R1 site of the PT gene. Replacement of Cys-41 with Tyr-41 in S1 must have resulted from this mutation. 79G PT composed of S234 (5) was accumulated both inside and outside the cells because the mutant S1 could not form the disulfide bond in the molecule to form the hexamer with the B oligomer, and also S1 must be degraded because of its instability in the cells. Nevertheless 79 GPT showed high immunoprotectivity in mice by active or passive immunization against ic or aerosol challenge with B. pertussis, strain 18323, respectively. It may have a proper conformational structure for protective immunogenicity and could become a good candidate strain for production of a safer and effective pertussis vaccine in the future. PMID:1778339

  17. Nanoparticle-detained toxins for safe and effective vaccination

    NASA Astrophysics Data System (ADS)

    Hu, Che-Ming J.; Fang, Ronnie H.; Luk, Brian T.; Zhang, Liangfang

    2013-12-01

    Toxoid vaccines--vaccines based on inactivated bacterial toxins--are routinely used to promote antitoxin immunity for the treatment and prevention of bacterial infections. Following chemical or heat denaturation, inactivated toxins can be administered to mount toxin-specific immune responses. However, retaining faithful antigenic presentation while removing toxin virulence remains a major challenge and presents a trade-off between efficacy and safety in toxoid development. Here, we show a nanoparticle-based toxin-detainment strategy that safely delivers non-disrupted pore-forming toxins for immune processing. Using erythrocyte membrane-coated nanoparticles and staphylococcal ?-haemolysin, we demonstrate effective virulence neutralization via spontaneous particle entrapment. Compared with vaccination with heat-denatured toxin, mice vaccinated with the nanoparticle-detained toxin showed superior protective immunity against toxin-mediated adverse effects. We find that the non-disruptive detoxification approach benefited the immunogenicity and efficacy of toxoid vaccines. We anticipate that this study will open new possibilities in the preparation of antitoxin vaccines against the many virulence factors that threaten public health.

  18. [Intoxication of botulinum toxin].

    PubMed

    Chudzicka, Aleksandra

    2015-09-01

    Botulinum toxin is an egzotoxin produced by Gram positive bacteria Clostridium botulinum. It is among the most potent toxins known. The 3 main clinical presentations of botulism are as follows: foodborne botulism, infant botulism and wound botulism. The main symptom of intoxication is flat muscles paralysis. The treatment is supportive care and administration of antitoxin. In prevention the correct preparing of canned food is most important. Botulinum toxin is accepted as a biological weapon. PMID:26449577

  19. Botulinum toxin injection - larynx

    MedlinePLUS

    Injection laryngoplasty; Botox-larynx: spasmodic dysphonia-BTX; Essential voice tremor (EVT)-btx; Glottic insufficiency; Percutaneous electromyography-guided botulinum toxin treatment; Percutaneous indirect laryngoscopy- ...

  20. Cell Motility by Labile Association of Molecules

    PubMed Central

    Inoué, Shinya; Sato, Hidemi

    1967-01-01

    This article summarizes our current views on the dynamic structure of the mitotic spindle and its relation to mitotic chromosome movements. The following statements are based on measurements of birefringence of spindle fibers in living cells, normally developing or experimentally modified by various physical and chemical agents, including high and low temperatures, antimitotic drugs, heavy water, and ultraviolet microbeam irradiation. Data were also obtained concomitantly with electron microscopy employing a new fixative and through measurements of isolated spindle protein. Spindle fibers in living cells are labile dynamic structures whose constituent filaments (microtubules) undergo cyclic breakdown and reformation. The dynamic state is maintained by an equilibrium between a pool of protein molecules and their linearly aggregated polymers, which constitute the microtubules or filaments. In living cells under physiological conditions, the association of the molecules into polymers is very weak (absolute value of ?F25°C < 1 kcal), and the equilibrium is readily shifted to dissociation by low temperature or by high hydrostatic pressure. The equilibrium is shifted toward formation of polymer by increase in temperature (with a large increase in entropy: ?S25°C ? 100 eu) or by the addition of heavy water. The spindle proteins tend to polymerize with orienting centers as their geometrical foci. The centrioles, kinetochores, and cell plate act as orienting centers successively during mitosis. Filaments are more concentrated adjacent to an orienting center and yield higher birefringence. Astral rays, continuous fibers, chromosomal fibers, and phragmoplast fibers are thus formed by successive reorganization of the same protein molecules. During late prophase and metaphase, polymerization takes place predominantly at the kinetochores; in metaphase and anaphase, depolymerization is prevalent near the spindle poles. When the concentration of spindle protein is high, fusiform bundles of polymer are precipitated out even in the absence of obvious orienting centers. The shift of equilibrium from free protein molecules to polymer increases the length and number of the spindle microtubules or filaments. Slow depolymerization of the polymers, which can be brought about by low concentrations of colchicine or by gradual cooling, allows the filaments to shorten and perform work. The dynamic equilibrium controlled by orienting centers and other factors provides a plasusible mechanism by which chromosomes and other organelles, as well as the cell surface, are deformed or moved by temporarily organized arrays of microtubules or filaments. PMID:6058222

  1. Total Dissolved Cobalt and Labile Cobalt in the North Atlantic

    NASA Astrophysics Data System (ADS)

    Saito, M. A.; Noble, A.

    2012-12-01

    This study presents the total and labile dissolved cobalt distributions from the North Atlantic GEOTRACES Zonal Transect expeditions of the fall of 2010 and 2011. Labile cobalt was detected in much of the water column below the euphotic zone, suggesting that strong cobalt binding ligands were not present in excess of the total cobalt concentration. Near complete complexation of cobalt was observed in surface waters, and linear relationships were observed when both total and labile cobalt were compared to phosphate in surface waters, indicative of a strong biological influence on cobalt cycling. Decoupling of cobalt and macronutrients in the surface waters was observed approaching the North American coast, and a relationship between cobalt and salinity was observed, suggesting that coastal inputs may dominate the distributions of cobalt there. In deep waters, both total and labile cobalt were generally lower in concentration than at intermediate depths, which is evidence of scavenging processes removing cobalt from the water column. Elevated concentrations of labile and total cobalt were observed in samples taken within the TAG hydrothermal plume, and a reverse relationship between cobalt and oxygen was observed in the western basin OMZ.

  2. Dietary vitamin E reduces labile iron in rat tissues.

    PubMed

    Ibrahim, Wissam; Chow, Ching Kuang

    2005-01-01

    Previous studies have shown that dietary vitamin E reduced generation and/or levels of superoxide. As superoxide has potential to release iron from its transport and storage proteins, and labile or available form of iron is capable of catalyzing the formation of reactive hydroxyl radicals, the effect of dietary vitamin E on labile iron pool was studied in rats. One-month-old Sprague-Dawley male and female rats were fed a basal vitamin E-deficient diet supplemented with 0, 20, 200, or 2,000 IU vitamin E/kg diet for 90 days. The levels of labile iron were measured in the liver, kidney, spleen, heart and skeletal muscle. Additionally, the levels of lipid peroxidation products were measured. The results showed that, except for labile iron in the heart of male rats, dietary vitamin E dose dependently reduced the levels of labile iron and lipid peroxidation products in all tissues of male and female rats. The findings suggest that dietary vitamin E may protect against oxidative tissue damage by reducing the generation and/or level of superoxide, which in turn attenuates the release of iron from its protein complexes. PMID:16292753

  3. 40 CFR 725.421 - Introduced genetic material.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... perfringens Beta-toxin; Delta-toxin Escherichia coli & other Enterobacteriaceae spp. Heat-labile enterotoxins... difficile Cytotoxin (toxin B) Clostridium perfringens Beta-toxin; Epsilon-toxin; Kappa-toxin Escherichia coli & other Enterobacteriaceae spp. Cytotoxin (Shiga-like toxin, Vero cell toxin)...

  4. 40 CFR 725.421 - Introduced genetic material.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... perfringens Beta-toxin; Delta-toxin Escherichia coli & other Enterobacteriaceae spp. Heat-labile enterotoxins... difficile Cytotoxin (toxin B) Clostridium perfringens Beta-toxin; Epsilon-toxin; Kappa-toxin Escherichia coli & other Enterobacteriaceae spp. Cytotoxin (Shiga-like toxin, Vero cell toxin)...

  5. 40 CFR 725.421 - Introduced genetic material.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... perfringens Beta-toxin; Delta-toxin Escherichia coli & other Enterobacteriaceae spp. Heat-labile enterotoxins... difficile Cytotoxin (toxin B) Clostridium perfringens Beta-toxin; Epsilon-toxin; Kappa-toxin Escherichia coli & other Enterobacteriaceae spp. Cytotoxin (Shiga-like toxin, Vero cell toxin)...

  6. 40 CFR 725.421 - Introduced genetic material.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... perfringens Beta-toxin; Delta-toxin Escherichia coli & other Enterobacteriaceae spp. Heat-labile enterotoxins... difficile Cytotoxin (toxin B) Clostridium perfringens Beta-toxin; Epsilon-toxin; Kappa-toxin Escherichia coli & other Enterobacteriaceae spp. Cytotoxin (Shiga-like toxin, Vero cell toxin)...

  7. Defense against toxin weapons

    SciTech Connect

    Franz, D.R.

    1994-01-01

    The purpose of this manual is to provide basic information on biological toxins to military leaders and health-care providers at all levels to help them make informed decisions on protecting their troops from toxins. Much of the information contained herein will also be of interest to individuals charged with countering domestic and international terrorism. We typically fear what we do not understand.

  8. Using Stimulants to Treat ADHD-Related Emotional Lability

    PubMed Central

    Posner, Jonathan; Kass, Erica; Hulvershorn, Leslie

    2014-01-01

    Emotional lability, or sudden strong shifts in emotion, commonly occurs in youth with attention-deficit/hyperactivity disorder. Although these symptoms are impairing and disruptive, relatively little research has addressed their treatment, likely due to the difficulty of reliable and valid assessment. Promising signals for symptom improvement have come from recent studies using stimulants in adults, children and adolescents. Similarly, neuroimaging studies have begun to identify neurobiological mechanisms underlying stimulants’ impact on emotion regulation capacities. Here, we review these recent clinical and neuroimaging findings, as well as neurocognitive models for emotional lability in ADHD, issues of relevance to prescribers and the important role of psychiatric comorbidity with treatment choices. PMID:25135778

  9. Development/Plasticity/Repair Initiation, Labile, and Stabilization Phases of

    E-print Network

    Barth, Alison L.

    by an input-specific, NMDAR-dependent depression. This labile phase is transient, lasting only a few hours required for synaptic plasticity in this area have been of great interest. Of critical importance is iden- ker inputs at layer 4­2/3 synapses, but then mediate synaptic depression (Clem et al., 2008). NMDAR

  10. Memory expression is independent of memory labilization/reconsolidation.

    PubMed

    Barreiro, Karina A; Suárez, Luis D; Lynch, Victoria M; Molina, Víctor A; Delorenzi, Alejandro

    2013-11-01

    There is growing evidence that certain reactivation conditions restrict the onset of both the destabilization phase and the restabilization process or reconsolidation. However, it is not yet clear how changes in memory expression during the retrieval experience can influence the emergence of the labilization/reconsolidation process. To address this issue, we used the context-signal memory model of Chasmagnathus. In this paradigm a short reminder that does not include reinforcement allows us to evaluate memory labilization and reconsolidation, whereas a short but reinforced reminder restricts the onset of such a process. The current study investigated the effects of the glutamate antagonists, APV (0.6 or 1.5 ?g/g) and CNQX (1 ?g/g), prior to the reminder session on both behavioral expression and the reconsolidation process. Under conditions where the reminder does not initiate the labilization/reconsolidation process, APV prevented memory expression without affecting long-term memory retention. In contrast, APV induced amnesic effects in the long-term when administered before a reminder session that triggers reconsolidation. Under the present parametric conditions, the administration of CNQX prior to the reminder that allows memory to enter reconsolidation impairs this process without disrupting memory expression. Overall, the present findings suggest that memory reactivation--but not memory expression--is necessary for labilization and reconsolidation. Retrieval and memory expression therefore appear not to be interchangeable concepts. PMID:24149057

  11. Neuropsychological Correlates of Emotional Lability in Children with ADHD

    ERIC Educational Resources Information Center

    Banaschewski, Tobias; Jennen-Steinmetz, Christine; Brandeis, Daniel; Buitelaar, Jan K.; Kuntsi, Jonna; Poustka, Luise; Sergeant, Joseph A.; Sonuga-Barke, Edmund J.; Frazier-Wood, Alexis C.; Albrecht, Bjorn; Chen, Wai; Uebel, Henrik; Schlotz, Wolff; van der Meere, Jaap J.; Gill, Michael; Manor, Iris; Miranda, Ana; Mulas, Fernando; Oades, Robert D.; Roeyers, Herbert; Rothenberger, Aribert; Steinhausen, Hans-Christoph; Faraone, Stephen V.; Asherson, Philip

    2012-01-01

    Background: Emotional lability (EL) is commonly seen in patients with attention-deficit/hyperactivity disorder (ADHD). The reasons for this association remain currently unknown. To address this question, we examined the relationship between ADHD and EL symptoms, and performance on a range of neuropsychological tasks to clarify whether EL symptoms…

  12. Carbon Mineralization and Labile Organic Carbon Pools in the Sandy

    E-print Network

    Grunwald, Sabine

    Carbon Mineralization and Labile Organic Carbon Pools in the Sandy Soils of a North Florida mineralization were best explained by TOC (62%) and hot-water- extractable C (59%), whereas acid-hydrolyzable C mineralization and clay content were directly linearly correlated, indicating a possible stimulatory effect

  13. Botulinum Toxin Therapy

    MedlinePLUS

    ... Bumps and growths Color problems Contagious skin diseases Cosmetic treatments Dry / sweaty skin Eczema / dermatitis Hair and ... dermatologist Home Public and patients Diseases and treatments Cosmetic treatments Botulinum toxin therapy public SPOT Skin Cancer™ ...

  14. Valence Focus and Self-Esteem Lability: Reacting to Hedonic Cues in the Social Environment

    E-print Network

    Barrett, Lisa Feldman

    Valence Focus and Self-Esteem Lability: Reacting to Hedonic Cues in the Social Environment Paula R experience) demonstrated greater self-esteem lability (i.e., larger changes in self-esteem) to pleasant. Keywords: valence focus, emotion, self-esteem lability, experience sampling, social interactions Hedonic

  15. [Toxins of Clostridium perfringens as a natural and bioterroristic threats].

    PubMed

    Omernik, Andrzej; P?usa, Tadeusz

    2015-09-01

    Clostridium perfringens is absolutely anaerobic rod-shaped, sporeforming bacterium. The morbidity is connected with producing toxins. Depending on the type of toxin produced Clostridium perfringens can be divided into five serotypes:A-E. Under natural conditions, this bacterium is responsible for local outbreaks of food poisoning associated with eating contaminated food which which was improperly heat treated. Some countries with lower economic level are endemic foci of necrotizing enteritis caused by Clostridium perfringens. The bacterium is also a major cause of gas gangrene. It is a disease, associated with wound infection, with potentially fatal prognosis in the case of treatment's delays. In the absence of early radical surgery, antibiotic therapy and (if available) hyperbaric treatment leads to the spread of toxins in the body causing shock, coma and death. Due to the force of produced toxins is a pathogen that poses a substrate for the production of biological weapons. It could potentially be used to induce outbreaks of food poisoning and by missiles contamination by spore lead to increased morbidity of gas gangrene in injured soldiers. C. perfringens types B and D produce epsilon toxin considered to be the third most powerful bacterial toxin. Because of the ability to disperse the toxin as an aerosol and a lack of methods of treatment and prevention of poisoning possible factors it is a potential tool for bioterrorism It is advisable to continue research into vaccines and treatments for poisoning toxins of C. perfringens. PMID:26449576

  16. Targeted Silencing of Anthrax Toxin Receptors Protects against Anthrax Toxins*

    PubMed Central

    Arévalo, Maria T.; Navarro, Ashley; Arico, Chenoa D.; Li, Junwei; Alkhatib, Omar; Chen, Shan; Diaz-Arévalo, Diana; Zeng, Mingtao

    2014-01-01

    Anthrax spores can be aerosolized and dispersed as a bioweapon. Current postexposure treatments are inadequate at later stages of infection, when high levels of anthrax toxins are present. Anthrax toxins enter cells via two identified anthrax toxin receptors: tumor endothelial marker 8 (TEM8) and capillary morphogenesis protein 2 (CMG2). We hypothesized that host cells would be protected from anthrax toxins if anthrax toxin receptor expression was effectively silenced using RNA interference (RNAi) technology. Thus, anthrax toxin receptors in mouse and human macrophages were silenced using targeted siRNAs or blocked with specific antibody prior to challenge with anthrax lethal toxin. Viability assays were used to assess protection in macrophages treated with specific siRNA or antibody as compared with untreated cells. Silencing CMG2 using targeted siRNAs provided almost complete protection against anthrax lethal toxin-induced cytotoxicity and death in murine and human macrophages. The same results were obtained by prebinding cells with specific antibody prior to treatment with anthrax lethal toxin. In addition, TEM8-targeted siRNAs also offered significant protection against lethal toxin in human macrophage-like cells. Furthermore, silencing CMG2, TEM8, or both receptors in combination was also protective against MEK2 cleavage by lethal toxin or adenylyl cyclase activity by edema toxin in human kidney cells. Thus, anthrax toxin receptor-targeted RNAi has the potential to be developed as a life-saving, postexposure therapy against anthrax. PMID:24742682

  17. Targeted silencing of anthrax toxin receptors protects against anthrax toxins.

    PubMed

    Arévalo, Maria T; Navarro, Ashley; Arico, Chenoa D; Li, Junwei; Alkhatib, Omar; Chen, Shan; Diaz-Arévalo, Diana; Zeng, Mingtao

    2014-05-30

    Anthrax spores can be aerosolized and dispersed as a bioweapon. Current postexposure treatments are inadequate at later stages of infection, when high levels of anthrax toxins are present. Anthrax toxins enter cells via two identified anthrax toxin receptors: tumor endothelial marker 8 (TEM8) and capillary morphogenesis protein 2 (CMG2). We hypothesized that host cells would be protected from anthrax toxins if anthrax toxin receptor expression was effectively silenced using RNA interference (RNAi) technology. Thus, anthrax toxin receptors in mouse and human macrophages were silenced using targeted siRNAs or blocked with specific antibody prior to challenge with anthrax lethal toxin. Viability assays were used to assess protection in macrophages treated with specific siRNA or antibody as compared with untreated cells. Silencing CMG2 using targeted siRNAs provided almost complete protection against anthrax lethal toxin-induced cytotoxicity and death in murine and human macrophages. The same results were obtained by prebinding cells with specific antibody prior to treatment with anthrax lethal toxin. In addition, TEM8-targeted siRNAs also offered significant protection against lethal toxin in human macrophage-like cells. Furthermore, silencing CMG2, TEM8, or both receptors in combination was also protective against MEK2 cleavage by lethal toxin or adenylyl cyclase activity by edema toxin in human kidney cells. Thus, anthrax toxin receptor-targeted RNAi has the potential to be developed as a life-saving, postexposure therapy against anthrax. PMID:24742682

  18. Microwave heating inactivates Shiga Toxin (Stx2) in reconstituted fat-free Milk and adversely affects the nutritional value of cell culture medium

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Microwave exposure is a convenient and widely used method for defrosting, heating, and cooking numerous foods. Microwave cooking is also reported to kill pathogenic microorganisms that often contaminate food. Microwaves act by causing polar molecules in food, such as water, to rapidly rotate, thus...

  19. Naturally Occurring Food Toxins

    PubMed Central

    Dolan, Laurie C.; Matulka, Ray A.; Burdock, George A.

    2010-01-01

    Although many foods contain toxins as a naturally-occurring constituent or, are formed as the result of handling or processing, the incidence of adverse reactions to food is relatively low. The low incidence of adverse effects is the result of some pragmatic solutions by the US Food and Drug Administration (FDA) and other regulatory agencies through the creative use of specifications, action levels, tolerances, warning labels and prohibitions. Manufacturers have also played a role by setting limits on certain substances and developing mitigation procedures for process-induced toxins. Regardless of measures taken by regulators and food producers to protect consumers from natural food toxins, consumption of small levels of these materials is unavoidable. Although the risk for toxicity due to consumption of food toxins is fairly low, there is always the possibility of toxicity due to contamination, overconsumption, allergy or an unpredictable idiosyncratic response. The purpose of this review is to provide a toxicological and regulatory overview of some of the toxins present in some commonly consumed foods, and where possible, discuss the steps that have been taken to reduce consumer exposure, many of which are possible because of the unique process of food regulation in the United States. PMID:22069686

  20. [Toxins as a biological weapon].

    PubMed

    P?usa, Tadeusz

    2015-09-01

    The criteria for recognizing a chemical compound for the toxin are vague and gave it the possibility of inclusion in this group a number of biological agents. Toxins list is extensive, but the interest is focused on bacterial toxins, poisons derived from snake venoms, algae and plant proteins, and small molecules. Particular attention is focused on the so-called "sea" toxins, which include tetrodotoxin, brevetoxin and saxitoxin. This indicates the search for a new hitherto unknown potential bioterrorist threats. PMID:26449572

  1. Toxin Plasmids of Clostridium perfringens

    PubMed Central

    Li, Jihong; Adams, Vicki; Bannam, Trudi L.; Miyamoto, Kazuaki; Garcia, Jorge P.; Uzal, Francisco A.; Rood, Julian I.

    2013-01-01

    SUMMARY In both humans and animals, Clostridium perfringens is an important cause of histotoxic infections and diseases originating in the intestines, such as enteritis and enterotoxemia. The virulence of this Gram-positive, anaerobic bacterium is heavily dependent upon its prolific toxin-producing ability. Many of the ?16 toxins produced by C. perfringens are encoded by large plasmids that range in size from ?45 kb to ?140 kb. These plasmid-encoded toxins are often closely associated with mobile elements. A C. perfringens strain can carry up to three different toxin plasmids, with a single plasmid carrying up to three distinct toxin genes. Molecular Koch's postulate analyses have established the importance of several plasmid-encoded toxins when C. perfringens disease strains cause enteritis or enterotoxemias. Many toxin plasmids are closely related, suggesting a common evolutionary origin. In particular, most toxin plasmids and some antibiotic resistance plasmids of C. perfringens share an ?35-kb region containing a Tn916-related conjugation locus named tcp (transfer of clostridial plasmids). This tcp locus can mediate highly efficient conjugative transfer of these toxin or resistance plasmids. For example, conjugative transfer of a toxin plasmid from an infecting strain to C. perfringens normal intestinal flora strains may help to amplify and prolong an infection. Therefore, the presence of toxin genes on conjugative plasmids, particularly in association with insertion sequences that may mobilize these toxin genes, likely provides C. perfringens with considerable virulence plasticity and adaptability when it causes diseases originating in the gastrointestinal tract. PMID:23699255

  2. Toxins 2010, 2, 310-325; doi:10.3390/toxins2030310 ISSN 2072-6651

    E-print Network

    Higgins, Darren

    Toxins 2010, 2, 310-325; doi:10.3390/toxins2030310 toxins ISSN 2072-6651 www.mdpi.com/journal/toxins Review Cholera Toxin: An Intracellular Journey into the Cytosol by Way of the Endoplasmic Reticulum Naomi / Accepted: 2 March 2010 / Published: 5 March 2010 Abstract: Cholera toxin (CT), an AB5-subunit toxin, enters

  3. CYANOBACTERIA AND THEIR TOXINS

    EPA Science Inventory

    Science Questions

    Harmful algal blooms (HAB) of cyanobacteria, also known as blue-green algae, have recently become more spatially and temporally prevalent in the US and worldwide. Cyanobacteria and their highly potent toxins are a significant hazard for human health and ...

  4. CYANOBACTERIA AND THEIR TOXINS.

    EPA Science Inventory

    Science Questions

    Harmful algal blooms (HAB) of cyanobacteria, also known as blue-green algae, have recently become more spatially and temporally prevalent in the US and worldwide. Cyanobacteria and their highly potent toxins are a significant hazard for human health and ...

  5. The association of emotional lability and emotional and behavioral difficulties among children with and without ADHD.

    PubMed

    Rosen, Paul J; Walerius, Danielle M; Fogleman, Nicholas D; Factor, Perry I

    2015-12-01

    Children with ADHD often demonstrate a pattern of emotional lability characterized by sudden and intense shifts in affect. Emotional lability has been linked to emotional and behavioral problems in children with and without ADHD, but few studies have examined emotional lability over time. This study examined the effects of emotional lability over time on the behavioral and emotional difficulties of children with and without ADHD using an ecological momentary assessment (EMA) methodology. One hundred and two children aged 8-12 years (56 with ADHD and 46 without ADHD) and their parents completed baseline measures of the children's behavioral and emotional difficulties. Parents then completed a 28-day 3-times daily EMA assessment protocol to rate their child's emotional lability. Results suggested that emotional lability was associated with internalizing and/or externalizing diagnoses independent of ADHD diagnostic status, but was not directly associated with ADHD. Hierarchical regression analyses supported ADHD diagnostic status as a moderator of the association of greater EMA-derived emotional lability with children's behavioral difficulties, such that greater emotional lability was associated with greater behavioral difficulties among children with ADHD but not among children without ADHD. Results indicated that greater emotional lability was directly linked with greater emotional difficulties and that this relation was not moderated by ADHD diagnostic status. Overall, this study suggested that emotional lability is related to emotional difficulties independent of ADHD, but is differentially related to behavioral difficulties among children with and without ADHD. PMID:25957599

  6. Do Vermont's Floodplains Constitute an Important Source of Labile Carbon?

    NASA Astrophysics Data System (ADS)

    Perdrial, J. N.; Dolan, A.; Kemsley, M.

    2014-12-01

    Floodplains are extremely heterogeneous landscapes with respect to soil and sediment composition and can present an important source of carbon (C) during floods. For example, stream bank soils and sediments are zones of active erosion and deposition of sediment associated C. Due to the presence of plants, riparian soils contain high amounts of C that is exchanged between stream waters and banks. Abandoned channels and meander wetlands that remain hydrologically connected to the main channel contain high amounts of organic matter that can be flushed into the stream during high discharge. This heterogeneity, result of floodplain geomorphology, land cover and use, can profoundly impact the amount and type of dissolved organic matter (DOM) introduced into streams. In order to assess DOM characteristics leached from heterogeneous floodplain soils, aqueous soil extracts were performed on soil samples representative of different land covers (n=20) at four depths. Extracts were analyzed for dissolved organic C and total dissolved nitrogen with a Shimadzu C analyzer. Colored dissolved organic matter characteristics was measured with the Aqualog Fluorescence Spectrometer and quantified with parallel factor analysis (PARAFAC). Preliminary data from three floodplains in Vermont (Connecticut, Missisquoi and Mad River) show a 3D variability of longitudinal, lateral, and vertical extents on water-extractable, mobile C. Dissolved organic carbon concentrations in meander swamp samples were found up to 9 times higher than in those of soils from agricultural field indicative of an important C source. Although C concentrations in adjacent fields were low, high abundance of labile C (indicated by tryptophan-like fluorescence) in water extracts from fields indicates recent biological production of C. This labile C is easily processed by microbes and transformed to the greenhouse gas CO2. These results provide important information on the contribution and lability of different floodplain areas (banks, riparian areas and meander wetlands) to C export and can help to make predictions for their export during flooding.

  7. Diversity of bacterial type II toxin–antitoxin systems: a comprehensive search and functional analysis of novel families

    PubMed Central

    Leplae, Raphaël; Geeraerts, Damien; Hallez, Régis; Guglielmini, Julien; Drèze, Pierre; Van Melderen, Laurence

    2011-01-01

    Type II toxin–antitoxin (TA) systems are generally composed of two genes organized in an operon, encoding a labile antitoxin and a stable toxin. They were first discovered on plasmids where they contribute to plasmid stability by a phenomenon denoted as ‘addiction’, and subsequently in bacterial chromosomes. To discover novel families of antitoxins and toxins, we developed a bioinformatics approach based on the ‘guilt by association’ principle. Extensive experimental validation in Escherichia coli of predicted antitoxins and toxins increased significantly the number of validated systems and defined novel toxin and antitoxin families. Our data suggest that toxin families as well as antitoxin families originate from distinct ancestors that were assembled multiple times during evolution. Toxin and antitoxin families found on plasmids tend to be promiscuous and widespread, indicating that TA systems move through horizontal gene transfer. We propose that due to their addictive properties, TA systems are likely to be maintained in chromosomes even though they do not necessarily confer an advantage to their bacterial hosts. Therefore, addiction might play a major role in the evolutionary success of TA systems both on mobile genetic elements and in bacterial chromosomes. PMID:21422074

  8. An ultrahigh-resolution mass spectrometry index to estimate natural organic matter lability

    PubMed Central

    D'Andrilli, Juliana; Cooper, William T; Foreman, Christine M; Marshall, Alan G

    2015-01-01

    Rationale Determining the chemical constituents of natural organic matter (NOM) by Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FTICRMS) remains the ultimate measure for probing its source material, evolution, and transport; however, lability and the fate of organic matter (OM) in the environment remain controversial. FTICRMS-derived elemental compositions are presented in this study to validate a new interpretative method to determine the extent of NOM lability from various environments. Methods FTICRMS data collected over the last decade from the same 9.4 tesla instrument using negative electrospray ionization at the National High Magnetic Field Laboratory in Tallahassee, Florida, was used to validate the application of a NOM lability index. Solid-phase extraction cartridges were used to isolate the NOM prior to FTICRMS; mass spectral peaks were calibrated internally by commonly identified NOM homologous series, and molecular formulae were determined for NOM composition and lability analysis. Results A molecular lability boundary (MLB) was developed from the FTICRMS molecular data, visualized from van Krevelen diagrams, dividing the data into more and less labile constituents. NOM constituents above the MLB at H/C ?1.5 correspond to more labile material, whereas NOM constituents below the MLB, H/C <1.5, exhibit less labile, more recalcitrant character. Of all marine, freshwater, and glacial environments considered for this study, glacial ecosystems were calculated to contain the most labile OM. Conclusions The MLB extends our interpretation of FTICRMS NOM molecular data to include a metric of lability, and generally ranked the OM environments from most to least labile as glacial?>?marine?>?freshwater. Applying the MLB is useful not only for individual NOM FTICRMS studies, but also provides a lability threshold to compare and contrast molecular data with other FTICRMS instruments that survey NOM from around the world. Copyright © 2015 The Authors. Rapid Communications in Mass Spectrometry published by John Wiley & Sons Ltd. PMID:26563709

  9. Toxins of Amanita phalloides.

    PubMed

    Vetter, J

    1998-01-01

    The most poisonous mushroom toxins are produced by Amanita phalloides (death cap). The occurrence and chemistry of three groups of toxins (amatoxins, phallotoxins and virotoxins) are summarized. The concentration and distribution of toxins in certain species are variable, with the young fruit body containing lower, and the well-developed fungus higher concentrations, but there is a high variability among specimens collected in the same region. Regarding phallotoxins, the volva (the ring) is the most poisonous. The most important biochemical effect of amatoxins is the inhibition of RNA polymerases (especially polymerase II). This interaction leads to a tight complex and the inhibition is of a non-competitive type. Non-mammalian polymerases show little sensitivity to amanitins. The amatoxins cause necrosis of the liver, also partly in the kidney, with the cellular changes causing the fragmentation and segregation of all nuclear components. Various groups of somatic cells of emanation resistance have been isolated, including from a mutant of Drosophila melanogaster. The phallotoxins stimulate the polymerization of G-actin and stabilize the F-actin filaments. The interaction of phallotoxins occurs via the small, 15-membered ring, on the left side of the spatial formula. The symptoms of human poisoning and the changes in toxin concentrations in different organs are summarized. Conventional therapy includes: (1) stabilization of patient's condition with the correction of hypoglycaemia and electrolytes; (2) decontamination; and (3) chemotherapy with different compounds. Finally, certain antagonists and protective compounds are reviewed, bearing in mind that today these have more of a theoretical than a practical role. PMID:9604278

  10. Acid-Labile Polyvinylamine Micro- and Nanogel Capsules

    PubMed Central

    Shi, Lianjun; Berkland, Cory

    2008-01-01

    Hollow nanoparticles represent an emerging area of development for the encapsulation of active ingredients. Expanding the capabilities of these nanomaterials will require continued efforts to infill properties such as size control, biodegradability, and environmental responsiveness. Acid-labile poly(N-vinylformamide) (PNVF) nanocapsules were synthesized by free radical polymerization of N-vinylformamide on the surface of silica nanoparticles. Polymerization in the presence of a novel crosslinker that contains an acid-labile ketal facilitated stable etching of silica nanoparticle templates using sodium hydroxide and recovery of degradable PNVF nanocapsules. The formamido side group of PNVF was then hydrolyzed by extended exposure to sodium hydroxide to produce polyvinylamine (PVAm) micro- and nanocapsules. Both capsule types demonstrated an increasing dissolution rate as pH decreased. In addition, PVAm nanocapsules exhibited swelling in proportion to the relative charge density of the PVAm network (a function of the degree of formamide hydrolysis and pH), presumably due to the repulsion of positively charged amino groups within the elastic shell network. The synthetic approaches reported provide methods to endow nanocapsules with key attributes such as size control, pH sensitive degradation, swelling in response to pH, and amine functionality. PMID:18797513

  11. Toxins 2015, 7, 299-321; doi:10.3390/toxins7020299 ISSN 2072-6651

    E-print Network

    Wood, Thomas K.

    Toxins 2015, 7, 299-321; doi:10.3390/toxins7020299 toxins ISSN 2072-6651 www.mdpi.com/journal/toxins Article Orphan Toxin OrtT (YdcX) of Escherichia coli Reduces Growth during the Stringent Response Sabina / Published: 29 January 2015 Abstract: Toxin/antitoxin (TA) systems are nearly universal in prokaryotes

  12. Method for detecting biological toxins

    SciTech Connect

    Ligler, F.S.; Campbell, J.R.

    1992-01-01

    Biological toxins are indirectly detected by using polymerase chain reaction to amplify unique nucleic acid sequences coding for the toxins or enzymes unique to toxin synthesis. Buffer, primers coding for the unique nucleic acid sequences and an amplifying enzyme are added to a sample suspected of containing the toxin. The mixture is then cycled thermally to exponentially amplify any of these unique nucleic acid sequences present in the sample. The amplified sequences can be detected by various means, including fluorescence. Detection of the amplified sequences is indicative of the presence of toxin in the original sample. By using more than one set of labeled primers, the method can be used to simultaneously detect several toxins in a sample.

  13. Recombinant Toxins for Cancer Treatment

    NASA Astrophysics Data System (ADS)

    Pastan, Ira; Fitzgerald, David

    1991-11-01

    Recombinant toxins target cell surface receptors and antigens on tumor cells. They kill by mechanisms different from conventional chemotherapy, so that cross resistance to conventional chemotherapeutic agents should not be a problem. Furthermore, they are not mutagens and should not induce secondary malignancies or accelerate progression of benign malignancies. They can be mass-produced cheaply in bacteria as homogeneous proteins. Either growth factor-toxin fusions or antibody-toxin fusions can be chosen, depending on the cellular target.

  14. PATHOGEN SAFETY DATA SHEET Diphtheria Toxin (DT)

    E-print Network

    Dyer, Bill

    PATHOGEN SAFETY DATA SHEET Diphtheria Toxin (DT) CHARACTERISTICS Natural Source Strains of Corynebacterium diphtheria that have been lysogenized by bacteriaphage Laboratory Source Solid Lyophilized toxin of toxin mediated disease. Prophylaxis Booster dose of diphtheria toxoid Vaccines Immunization

  15. Novel Structure and Function of Typhoid Toxin

    MedlinePLUS

    ... 29, 2013 Novel Structure and Function of Typhoid Toxin Structure of typhoid toxin, showing the 2 A subunits (blue and red) ... 2013, in Nature . The researchers focused on typhoid toxin, a unique factor produced by S. typhi that was ...

  16. PATHOGEN SAFETY DATA SHEET Pertussis Toxin (PT)

    E-print Network

    Dyer, Bill

    PATHOGEN SAFETY DATA SHEET Pertussis Toxin (PT) CHARACTERISTICS Natural Source Produced by the Bordetella pertussis Laboratory Source Solid Lyophilized toxin Characteristics DT is an exotoxin PRECAUTIONS/TREATMENT Diagnosis Clinical symptoms of toxin mediated disease. Prophylaxis Booster dose

  17. Ratcheting up protein translocation with anthrax toxin

    PubMed Central

    Feld, Geoffrey K; Brown, Michael J; Krantz, Bryan A

    2012-01-01

    Energy-consuming nanomachines catalyze the directed movement of biopolymers in the cell. They are found both dissolved in the aqueous cytosol as well as embedded in lipid bilayers. Inquiries into the molecular mechanism of nanomachine-catalyzed biopolymer transport have revealed that these machines are equipped with molecular parts, including adjustable clamps, levers, and adaptors, which interact favorably with substrate polypeptides. Biological nanomachines that catalyze protein transport, known as translocases, often require that their substrate proteins unfold before translocation. An unstructured protein chain is likely entropically challenging to bind, push, or pull in a directional manner, especially in a way that produces an unfolding force. A number of ingenious solutions to this problem are now evident in the anthrax toxin system, a model used to study protein translocation. Here we highlight molecular ratchets and current research on anthrax toxin translocation. A picture is emerging of proton-gradient-driven anthrax toxin translocation, and its associated ratchet mechanism likely applies broadly to other systems. We suggest a cyclical thermodynamic order-to-disorder mechanism (akin to a heat-engine cycle) is central to underlying protein translocation: peptide substrates nonspecifically bind to molecular clamps, which possess adjustable affinities; polypeptide substrates compress into helical structures; these clamps undergo proton-gated switching; and the substrate subsequently expands regaining its unfolded state conformational entropy upon translocation. PMID:22374876

  18. A Solvent-Free Thermosponge Nanoparticle Platform for Efficient Delivery of Labile Proteins

    E-print Network

    von Andrian, Ulrich H.

    A Solvent-Free Thermosponge Nanoparticle Platform for Efficient Delivery of Labile Proteins Won Il the development of a novel polymeric thermosponge nanoparticle for efficient delivery of labile proteins using Supporting Information ABSTRACT: Protein therapeutics have gained attention recently for treatment

  19. Elemental composition and functional groups in soil labile organic matter fractions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Labile organic matter fractions are major components involved in nutrient cycle in soil. In this chapter, we examine three labile organic matter fraction: light fraction (LF), humic acid (HA) and fulvic acid (HA) in Alabama cotton soils (ultisol) amended with chemical fertilizer (NH4NO3) and poult...

  20. The role of labile sulfur compounds in thermochemical sulfate reduction

    NASA Astrophysics Data System (ADS)

    Amrani, Alon; Zhang, Tongwei; Ma, Qisheng; Ellis, Geoffrey S.; Tang, Yongchun

    2008-06-01

    The reduction of sulfate to sulfide coupled with the oxidation of hydrocarbons to carbon dioxide, commonly referred to as thermochemical sulfate reduction (TSR), is an important abiotic alteration process that most commonly occurs in hot carbonate petroleum reservoirs. In the present study we focus on the role that organic labile sulfur compounds play in increasing the rate of TSR. A series of gold-tube hydrous pyrolysis experiments were conducted with n-octane and CaSO4 in the presence of reduced sulfur (e.g. H2S, S°, organic S) at temperatures of 330 and 356 °C under a constant confining pressure. The in-situ pH was buffered to 3.5 (?6.3 at room temperature) with talc and silica. For comparison, three types of oil with different total S and labile S contents were reacted under similar conditions. The results show that the initial presence of organic or inorganic sulfur compounds increases the rate of TSR. However, organic sulfur compounds, such as 1-pentanethiol or diethyldisulfide, were significantly more effective in increasing the rate of TSR than H2S or elemental sulfur (on a mole S basis). The increase in rate is achieved at relatively low concentrations of 1-pentanethiol, less than 1 wt% of the total n-octane, which is comparable to the concentration of organic S that is common in many oils (?0.3 wt%). We examined several potential reaction mechanisms to explain the observed reactivity of organic LSC. First, the release of H2S from the thermal degradation of thiols was discounted as an important mechanism due to the significantly greater reactivity of thiol compared to an equivalent amount of H2S. Second, we considered the generation of olefines in association with the elimination of H2S during thermal degradation of thiols because olefines are much more reactive than n-alkanes during TSR. In our experiments, olefines increased the rate of TSR, but were less effective than 1-pentanethiol and other organic LSC. Third, the thermal decomposition of organic LSC creates free-radicals that in turn might initiate a radical chain-reaction that creates more reactive species. Experiments involving radical initiators, such as diethyldisulfide and benzyldisulfide, did not show an increase in reactivity compared to 1-pentanethiol. Therefore, we conclude that none of these can sufficiently explain our observations of the initial stages of TSR; they may, however, be important in the later stages. In order to gain greater insight into the potential mechanism for the observed reactivity of these organic sulfur compounds during TSR, we applied density functional theory-based molecular modeling techniques to our system. The results of these calculations indicate that 1-pentanethiol or its thermal degradation products may directly react with sulfate and reduce the activation energy required to rupture the first S-O bond through the formation of a sulfate ester. This study demonstrates the importance of labile sulfur compounds in reducing the onset timing and temperature of TSR. It is therefore essential that labile sulfur concentrations are taken into consideration when trying to make accurate predictions of TSR kinetics and the potential for H2S accumulation in petroleum reservoirs.

  1. The contractile lability of smooth muscle in asthmatic airway hyperresponsiveness.

    PubMed

    Auger, Laurence; Mailhot-Larouche, Samuel; Tremblay, Francis; Poirier, Mathilde; Farah, Claude; Bossé, Ynuk

    2016-01-01

    The contractile capacity of airway smooth muscle is not fixed but modulated by an impressive number of extracellular inflammatory mediators. Targeting the transient component of airway hyperresponsiveness ascribed to this contractile lability of ASM is a quest of great promises in order to alleviate asthma symptoms during inflammatory flares. However, owing to the plethora of mediators putatively involved and the molecular heterogeneity of asthma, it is more likely that many mediators conspire to increase the contractile capacity of ASM, each of which contributing to a various extent and in a time-varying fashion in individuals suffering from asthma. The task of identifying a common mend for a tissue rendered hypercontractile by imponderable assortments of inflammatory mediators is puzzling. PMID:26561333

  2. Labile dissolved organic carbon supply limits hyporheic denitrification

    NASA Astrophysics Data System (ADS)

    Zarnetske, Jay P.; Haggerty, Roy; Wondzell, Steven M.; Baker, Michelle A.

    2011-12-01

    We used an in situ steady state 15N-labeled nitrate (15NO3-) and acetate (AcO-) well-to-wells injection experiment to determine how the availability of labile dissolved organic carbon (DOC) as AcO-influences microbial denitrification in the hyporheic zone of an upland (third-order) agricultural stream. The experimental wells receiving conservative (Cl- and Br) and reactive (15NO3-) solute tracers had hyporheic median residence times of 7.0 to 13.1 h, nominal flowpath lengths of 0.7 to 3.7 m, and hypoxic conditions (<1.5 mg O2 L-1). All receiving wells demonstrated 15N2 production during ambient conditions, indicating that the hyporheic zone was an environment with active denitrification. The subsequent addition of AcO- stimulated more denitrification as evidenced by significant ?15N2 increases by factors of 2.7 to 26.1 in receiving wells and significant decreases of NO3- and DO in the two wells most hydrologically connected to the injection. The rate of nitrate removal in the hyporheic zone increased from 218 kg ha-1 yr-1 to 521 kg ha-1 yr-1 under elevated AcO- conditions. In all receiving wells, increases of bromide and 15N2 occurred without concurrent increases in AcO-, indicating that 100% of AcO- was retained or lost in the hyporheic zone. These results support the hypothesis that denitrification in anaerobic portions of the hyporheic zone is limited by labile DOC supply.

  3. TOXINS FROM CYANOBACTERIA IN WATER

    EPA Science Inventory

    This project is part of a larger U. S. Environmental Protection Agency (EPA) effort, which includes the Office of Water, to investigate algal toxins in surface water supplies and drinking water. Toxins produced by cyanobacteria (blue-green algae) are among the most potent known ...

  4. The assay of diphtheria toxin

    PubMed Central

    Gerwing, Julia; Long, D. A.; Mussett, Marjorie V.

    1957-01-01

    A precise assay of diphtheria toxin is described, based on the linear relationship between the diameter of the skin reaction to, and logarithm of the dose of, toxin. It eliminates the need for preliminary titrations, is economical, provides information about the slope of the log-dose response lines and, therefore, of the validity of the assay, and yields limits of error of potency from the internal evidence of the assay. A study has been made of the effects of avidity, combining power, toxicity and buffering on the assay of diphtheria toxins against the International Standards for both Diphtheria Antitoxin and Schick-Test Toxin. All the toxins assayed against the standard toxin, whatever their other properties might be, gave log-dose response lines of similar slope provided that they were diluted in buffered physiological saline. The assays were therefore valid. These experiments were repeated concurrently in non-immune and in actively immunized guinea-pigs, and comparable figures for potency obtained in both groups. The result was not significantly affected by the avidity or combining power of the toxin. However, non-avid toxins gave low values in Schick units when assayed, by the Römer & Sames technique, in terms of the International Standard for Diphtheria Antitoxin. The problem of the ultimate standard and the implications of these findings are discussed. PMID:13511133

  5. Lymphocyte receptors for pertussis toxin

    SciTech Connect

    Clark, C.G.; Armstrong, G.D. )

    1990-12-01

    We have investigated human T-lymphocyte receptors for pertussis toxin by affinity isolation and photoaffinity labeling procedures. T lymphocytes were obtained from peripheral human blood, surface iodinated, and solubilized in Triton X-100. The iodinated mixture was then passed through pertussis toxin-agarose, and the fractions were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Autoradiography of the fixed, dried gels revealed several bands in the pertussis toxin-bound fraction that were not observed in fractions obtained from histone or fetuin-agarose. Further investigations employed a photoaffinity labeling reagent, sulfosuccinimidyl 2-(p-azido-salicylamido)-1,3'-dithiopropionate, to identify pertussis toxin receptors in freshly isolated peripheral blood monocytic cells, T lymphocytes, and Jurkat cells. In all three cell systems, the pertussis toxin affinity probe specifically labeled a single protein species with an apparent molecular weight of 70,000 that was not observed when the procedure was performed in the presence of excess unmodified pertussis toxin. A protein comparable in molecular weight to the one detected by the photoaffinity labeling technique was also observed among the species that bound to pertussis toxin-agarose. The results suggest that pertussis toxin may bind to a 70,000-Da receptor in human T lymphocytes.

  6. Toxin-induced hepatic injury.

    PubMed

    Lopez, Annette M; Hendrickson, Robert G

    2014-02-01

    Toxins such as pharmaceuticals, herbals, foods, and supplements may lead to hepatic damage. This damage may range from nonspecific symptoms in the setting of liver test abnormalities to acute hepatic failure. The majority of severe cases of toxin-induced hepatic injury are caused by acetaminophen and ethanol. The most important step in the patient evaluation is to gather an extensive history that includes toxin exposure and exclude common causes of liver dysfunction. Patients whose hepatic dysfunction progresses to acute liver failure may benefit from transfer to a transplant service for further management. Currently, the mainstay in management for most exposures is discontinuing the offending agent. This manuscript will review the incidence, pathophysiology, diagnosis and management of the different forms of toxin-induced hepatic injury and exam in-depth the most common hepatic toxins. PMID:24275171

  7. Toxin-Based Therapeutic Approaches

    PubMed Central

    Shapira, Assaf; Benhar, Itai

    2010-01-01

    Protein toxins confer a defense against predation/grazing or a superior pathogenic competence upon the producing organism. Such toxins have been perfected through evolution in poisonous animals/plants and pathogenic bacteria. Over the past five decades, a lot of effort has been invested in studying their mechanism of action, the way they contribute to pathogenicity and in the development of antidotes that neutralize their action. In parallel, many research groups turned to explore the pharmaceutical potential of such toxins when they are used to efficiently impair essential cellular processes and/or damage the integrity of their target cells. The following review summarizes major advances in the field of toxin based therapeutics and offers a comprehensive description of the mode of action of each applied toxin. PMID:22069564

  8. Yeast killer plasmid mutations affecting toxin secretion and activity and toxin immunity function

    SciTech Connect

    Bussey, H.; Sacks, W.; Galley, D.; Saville, D.

    1982-04-01

    M double-stranded RNA (MdsRNA) plasmid mutants were obtained by mutagenesis and screening of a diploid killer culture partially heat cured of the plasmid, so that a high proportion of the cells could be expected to have only one M plasmid. Mutants with neutral (K/sup -/), immune (R/sup +/) or suicide (killer (K/sup +/), sensitive (R/sup -/)) phenotypes were examined. All mutants became K/sup -/ R/sup -/ sensitives on heat curing of the MdsRNA plasmid, and showed cytoplasmic inheritance by random spore analysis. In some cases, M plasmid mutations were indicated by altered mobility of the MdsRNA by agarose gel electrophoresis or by altered size of in vitro translation products from denatured dsRNA. Neutral mutants were of two types: nonsecretors of the toxin protein or secretors of an inactive toxin. Of three neutral nonsecretors examined, one (NLP-1), probably a nonsense mutation, made a smaller protoxin precursor in vitro and in vivo, and two made full-size protoxin molecules. The in vivo protoxin of 43,000 molecular weight was unstable in the wild type and kinetically showed a precursor product relationship to the processed, secreted 11,000-molecular-weight toxin. In one nonsecretor (N1), the protoxin appeared more stable in a pulse-chase experiment, and could be altered in a recognition site required for protein processing.

  9. Food toxin detection with atomic force microscope

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Externally introduced toxins or internal spoilage correlated pathogens and their metabolites are all potential sources of food toxins. To prevent and protect unsafe food, many food toxin detection techniques have been developed to detect various toxins for quality control. Although several routine m...

  10. Lability of trace metals in submerged soils: a column study

    NASA Astrophysics Data System (ADS)

    Nimirciag, Ramona; Ajmone-Marsan, Franco

    2013-04-01

    The reduction of Fe (III) and Mn (IV) and the decomposition of organic matter exert a great influence on the biogeochemical cycles of many trace metals and nutrients in the environment. In the particular case of intermittently submerged soils, metals associated with Fe and Mn oxides become readily available due to the reductive dissolution of Fe and Mn oxides. The effects of oxido-reductive conditions on the release of Cu and Zn from heavy metal contaminated soils and the changes in their chemical speciation were studied. Column experiments were performed, using Rhizon soil moisture samplers inserted at different heights to monitor the mobility and transport of metals in the submerged soil samples. Cu was released in solution immediately, in the first red-ox cycle, either due to the solubilization of Fe and Mn oxides, or to the oxidation of organic matter with which Cu is commonly complexed, or both. During the following reductive half-cycles, the amount of Cu extracted from the soil solution decreased. However, the concentration of Cu in the solution leached from the column, which was percolated in aerobic conditions, increased. Since in the successive red-ox cycles the Eh decreases faster and to lower values, it is possible that Cu might have been removed from pore water by sulfide precipitation during the anaerobic half-cycle and released during the aerobic half-cycle, due to the oxidation of sulfides to sulfates. The release of Zn was similar to the dissolution of Fe and Mn oxyhydroxydes, and the amount extracted by Rhizon and by leaching increased during the four red-ox cycles. The chemical fractionation of the soils was also studied and the results showed that the alternate oxidative-reductive conditions cause, in general, an increase in the lability of trace metals. While Zn speciation suffers little change, Cu showed a much higher exchangeable fraction in the submerged soils, as compared to the initial, not submerged ones. The results of this study indicate that intermittent submergence of contaminated soils not only causes the release of trace metals previously bound to Fe and Mn oxides and to organic matter, but also leads to an increase in their lability, rending them more readily available to be released into the environment.

  11. [Shiga toxin and tetanus toxin as a potential biologic weapon].

    PubMed

    Toczyska, Izabela; P?usa, Tadeusz

    2015-09-01

    Toxins produced by the bacteria are of particular interest as potential cargo combat possible for use in a terrorist attack or war. Shiga toxin is usually produced by shiga toxigenic strains of Escherichia coli (STEC - shigatoxigenic Escherichia coli). To infection occurs mostly after eating contaminated beef. Clinical syndromes associated with Shiga toxin diarrhea, hemorrhagic colitis, hemolytic uremic syndrome (HUS - hemolytic uremic syndrome) or thrombotic thrombocytopenic purpura. Treatment is symptomatic. In HUS, in which mortality during an epidemic reaches 20%, extending the kidney injury dialysis may be necessary. Exposure to tetanus toxin produced by Clostridium tetani, resulting in the most generalized tetanus, characterized by increased muscle tension and painful contractions of individual muscle groups. In the treatment beyond symptomatic behavior (among others spasticity medications, anticonvulsants, muscle relaxants) is used tetanus antitoxin and antibiotics (metronidazole choice). A common complication is acute respiratory failure - then it is necessary to implement mechanical ventilation. PMID:26449578

  12. The three-dimensional crystal structure of cholera toxin

    SciTech Connect

    Zhang, Rong-Guang; Westbrook, M.L.; Nance, S.; Spangler, B.D.; Scott, D.L.; Westbrook, E.M.

    1996-02-01

    The clinical manifestations of cholera are largely attributable to the actions of a secreted hexameric AB{sub 5} enterotoxin (choleragen). We have solved the three-dimensional structure of choleragen at 2.5 {Angstrom} resolution and compared the refined coordinates with those of choleragenoid (isolated B pentamer) and the heat-labile enterotoxin from Escherichia coli (LT). The crystalline coordinates provide a detailed view of the stereochemistry implicated in binding to GM1 gangliosides and in carrying out ADP-ribosylation. The A2 chain of choleragen, in contrast to that of LT, is a nearly continuous {alpha}-helix with an interpretable carboxyl tail.

  13. High Sensitivity Combined with Extended Structural Coverage of Labile Compounds via Nanoelectrospray Ionization at Subambient Pressures

    SciTech Connect

    Cox, Jonathan T.; Kronewitter, Scott R.; Shukla, Anil K.; Moore, Ronald J.; Smith, Richard D.; Tang, Keqi

    2014-10-07

    Subambient pressure ionization with nanoelectrospray (SPIN) has proven to be effective in producing ions with high efficiency and transmitting them to low pressures for high sensitivity mass spectrometry (MS) analysis. Here we present evidence that not only does the SPIN source improve MS sensitivity but also allows for gentler ionization conditions. The gentleness of a conventional heated capillary electrospray ionization (ESI) source and the SPIN source was compared by the liquid chromatography mass spectrometry (LC-MS) analysis of colominic acid. Colominic acid is a mixture of sialic acid polymers of different lengths containing labile glycosidic linkages between monomer units necessitating a gentle ion source. By coupling the SPIN source with high resolution mass spectrometry and using advanced data processing tools, we demonstrate much extended coverage of sialic acid polymer chains as compared to using the conventional ESI source. Additionally we show that SPIN-LC-MS is effective in elucidating polymer features with high efficiency and high sensitivity previously unattainable by the conventional ESI-LC-MS methods. ?

  14. Equilibrium phase behavior of labile cross inkers in semiflexible networks

    NASA Astrophysics Data System (ADS)

    Kachan, Devin; Levine, Alex; Bruinsma, Robijn

    2014-03-01

    The equilibrium phase behavior of cross linkers in a network of semiflexible filaments is complex. The binding of the cross linkers affects the transverse undulations of the filaments leading to a fluctuation-mediate attractive or Casimir interaction between them. If the cross linkers also provide constraint torques to enforce a preferred binding angle between filaments, the resulting networks can have complex spatial distributions of filaments and of cross linkers bound to those filaments. Simulations report both the formation lamellar network structures and the aggregation of cross-linkers in thermal equilibrium. In this talk, we explore the the Casimir interaction between cross linkers bound to a given filament. We report on the spatial correlations between cross linkers bound to a given filament due to their Casimir interactions, and compare these theoretical predictions to the results of Brownian dynamics based finite element simulations of the system. We conclude with a discussion of the implications of these results for the equilibrium structure of semiflexible filament networks with labile cross linkers.

  15. A Bivalent Tarantula Toxin Activates the Capsaicin Receptor, TRPV1, by Targeting the Outer Pore Domain

    PubMed Central

    Bohlen, Christopher J.; Priel, Avi; Zhou, Sharleen; King, David; Siemens, Jan; Julius, David

    2010-01-01

    SUMMARY Toxins have evolved to target regions of membrane ion channels that underlie ligand binding, gating, or ion permeation, and have thus served as invaluable tools for probing channel structure and function. Here we describe a peptide toxin from the Earth Tiger tarantula that selectively and irreversibly activates the capsaicin- and heat-sensitive channel, TRPV1. This high avidity interaction derives from a unique tandem repeat structure of the toxin that endows it with an antibody-like bivalency, illustrating a new paradigm in toxin structure and evolution. The ‘double-knot’ toxin traps TRPV1 in the open state by interacting with residues in the presumptive pore-forming region of the channel, highlighting the importance of conformational changes in the outer pore region of TRP channels during activation. PMID:20510930

  16. Lincomycin-induced over-expression of mature recombinant cholera toxin B subunit and the holotoxin in Escherichia coli.

    PubMed

    Arimitsu, Hideyuki; Tsukamoto, Kentaro; Ochi, Sadayuki; Sasaki, Keiko; Kato, Michio; Taniguchi, Koki; Oguma, Keiji; Tsuji, Takao

    2009-10-01

    Cholera toxin (CT) B subunit (CTB) was overproduced using a novel expression system in Escherichia coli. An expression plasmid was constructed by inserting the gene encoding the full-length CTB and the Shine-Dalgarno (SD) sequence derived from CTB or from the heat-labile enterotoxin B subunit (LTB) of enterotoxigenic E. coli into the lacZalpha gene fragment in the pBluescript SK(+) vector. The E. coli strain MV1184 was transformed with each plasmid and then cultured in CAYE broth containing lincomycin. Recombinant CTB (rCTB) was purified from each cell extract. rCTB was overproduced in both transformants without obvious toxicity and was structurally and biologically identical to that of CT purified from Vibrio cholerae, indicating that the original SD and CTB signal sequences were also sufficient to express rCTB in E. coli. Lincomycin-induced rCTB expression was inhibited by mutating the lac promoter, suggesting that lincomycin affects the lactose operon. Based on these findings, we constructed a plasmid that contained the wild-type CT operon and successfully overproduced CT (rCT) using the same procedure for rCTB. Although rCT had an intact A subunit, the amino-terminal modifications and biological properties of the A and B subunits of rCT were identical to those of CT. These results suggest that this novel rCTB over-expression system would also be useful to generate both wild-type and mutant CT proteins that will facilitate further studies on the characteristics of CT, such as mucosal adjuvant activity. PMID:19410003

  17. [Today's threat of ricin toxin].

    PubMed

    From, S?awomir; P?usa, Tadeusz

    2015-09-01

    Since the late 70s of the last century there were more than 700 incidents related to the use of the ricin toxin. For this reason, CDC (Center of Disease Control and Prevention) recognized toxin as a biological weapon category B. The lethal dose of ricin toxin after parenteral administration is 0.0001 mg/kg and after oral administration 0.2 mg. The first symptoms of poisoning occur within a few hours after application of toxin as a nausea, vomiting and abdominal pain. In the final stage there are observed: cardiac arrhythmia, collapse and symptoms suggestive of involvement of the central nervous system. Stage immediately preceding death is a state of coma. The ricin toxin is still the substance against which action has no optimal antidote. Developed a vaccine called RiVax is waiting for its registration. It should be pointed out that the availability of a ricin toxin makes it possible to use it for real bioterrorists. PMID:26449579

  18. DETERMINATION OF APPARENT QUANTUM YIELD SPECTRA FOR THE FORMATION OF BIOLOGICALLY LABILE PHOTOPRODUCTS

    EPA Science Inventory

    Quantum yield spectra for the photochemical formation of biologically labile photoproducts from dissolved organic matter (DOM) have not been available previously, although they would greatly facilitate attempts to model photoproduct formation rates across latitudinal, seasonal, a...

  19. Enzymatic Detoxification of HC-toxin, the Host-Selective Cyclic Peptide from Cochliobolus carbonum.

    PubMed

    Meeley, R B; Walton, J D

    1991-11-01

    Resistance to the fungal plant pathogen Cochliobolus carbonum race 1 and to its host-selective toxin, HC-toxin, is determined by Hm, a single dominant gene in the host plant maize, (Zea mays L). Radiolabeled HC-toxin of specific activity 70 milliCuries per millimole, prepared by feeding tritiated d,l-alanine to the fungus, was used to study its fate in maize leaf tissues. HC-toxin was converted by resistant leaf segments to a single compound, identified by mass spectrometry and nuclear magnetic resonance as the 8-hydroxy derivative of HC-toxin formed by reduction of the 8-keto group of 2-amino-9, 10-epoxy-8-oxo-decanoic acid, one of the amino acids in HC-toxin. Reduction of HC-toxin occurred in cell-free preparations from etiolated (Hm/hm) maize shoots, and the activity was sensitive to heat and proteolytic digestion, dependent on NADPH, and inhibited by p-hydroxymercuribenzoate and disulfiram. The enzyme (from the Hm/hm genotype) was partially purified by ammonium sulfate precipitation and diethylaminoethyl-ion exchange chromatography. By gel filtration chromatography, the enzyme had a molecular weight of 42,000. NADH was approximately 30% as effective as NADPH as a hydride donor, and flavin-containing cofactors had no effect on activity. When HC-toxin was introduced to maize leaf segments through the transpiration stream, leaf segments from both resistant and susceptible maize inactivated toxin equally well over a time-course of 9 hours. Although these data suggest no relationship between toxin metabolism and host selectivity, we discuss findings in apparent conflict with the current data and describe why the relationship between enzymatic reduction of HC-toxin and Hm remains unresolved. PMID:16668492

  20. Antibody-based biological toxin detection

    SciTech Connect

    Menking, D.E.; Goode, M.T.

    1995-12-01

    Fiber optic evanescent fluorosensors are under investigation in our laboratory for the study of drug-receptor interactions for detection of threat agents and antibody-antigen interactions for detection of biological toxins. In a direct competition assay, antibodies against Cholera toxin, Staphylococcus Enterotoxin B or ricin were noncovalently immobilized on quartz fibers and probed with fluorescein isothiocyanate (FITC) - labeled toxins. In the indirect competition assay, Cholera toxin or Botulinum toxoid A was immobilized onto the fiber, followed by incubation in an antiserum or partially purified anti-toxin IgG. These were then probed with FITC-anti-IgG antibodies. Unlabeled toxins competed with labeled toxins or anti-toxin IgG in a dose dependent manner and the detection of the toxins was in the nanomolar range.

  1. Influence of yogurt fermentation and refrigerated storage on the stability of protein toxin contaminants.

    PubMed

    Jackson, Lauren S; Triplett, Odbert A; Tolleson, William H

    2015-06-01

    Dairy products sold in a ready-to-eat form present the risk that adulterants persisting through manufacturing, storage, and distribution would reach consumers. Pathogenic microbes, including shigatoxigenic strains of Escherichia coli and the toxins they produce, are common food safety hazards associated with dairy products. Ricin and abrin are plant-derived ribosome-inactivating protein toxins related to the shiga-like toxins produced by E.?coli. Limited information exists on the effects of manufacturing processes on the stabilities of these heat-resistant ribosome-inactivating proteins in the presence of foods. The goal of this study was to determine how typical yogurt manufacturing and storage processes influence ribosome-inactivating protein toxins. Ricin and abrin were added to skim or whole milk and batch pasteurized. Complete inactivation of both toxins was observed after 30 minutes at 85?°C. If the toxins were added after pasteurization, the levels of ricin and abrin in yogurt and their cytotoxic activities did not change significantly during fermentation or refrigerated storage for 4 weeks. The activities of ricin and abrin were inhibited by skim milk, nonfat yogurt, whole milk, and whole milk yogurt. The results showed minimal effects of the toxins on yogurt pH and %titratable acidity but inhibitory effects of yogurt on toxin activity. PMID:25772284

  2. Scorpion toxins prefer salt solutions.

    PubMed

    Nikouee, Azadeh; Khabiri, Morteza; Cwiklik, Lukasz

    2015-11-01

    There is a wide variety of ion channel types with various types of blockers, making research in this field very complicated. To reduce this complexity, it is essential to study ion channels and their blockers independently. Scorpion toxins, a major class of blockers, are charged short peptides with high affinities for potassium channels. Their high selectivity and inhibitory properties make them an important pharmacological tool for treating autoimmune or nervous system disorders. Scorpion toxins typically have highly charged surfaces and-like other proteins-an intrinsic ability to bind ions (Friedman J Phys Chem B 115(29):9213-9223, 1996; Baldwin Biophys J 71(4):2056-2063, 1996; Vrbka et al. Proc Natl Acad Sci USA 103(42):15440-15444, 2006a; Vrbka et al. J Phys Chem B 110(13):7036-43, 2006b). Thus, their effects on potassium channels are usually investigated in various ionic solutions. In this work, computer simulations of protein structures were performed to analyze the structural properties of the key residues (i.e., those that are presumably involved in contact with the surfaces of the ion channels) of 12 scorpion toxins. The presence of the two most physiologically abundant cations, Na(+) and K(+), was considered. The results indicated that the ion-binding properties of the toxin residues vary. Overall, all of the investigated toxins had more stable structures in ionic solutions than in water. We found that both the number and length of elements in the secondary structure varied depending on the ionic solution used (i.e., in the presence of NaCl or KCl). This study revealed that the ionic solution should be chosen carefully before performing experiments on these toxins. Similarly, the influence of these ions should be taken into consideration in the design of toxin-based pharmaceuticals. PMID:26475740

  3. Thermally labile components of aqueous humor potently induce osteogenic potential in adipose-derived mesenchymal stem cells.

    PubMed

    Morgan, Joshua T; Kwon, Heung Sun; Wood, Joshua A; Borjesson, Dori L; Tomarev, Stanislav I; Murphy, Christopher J; Russell, Paul

    2015-06-01

    Adipose-derived mesenchymal stem cells (ASCs) hold promise for use in cell-based therapies. Their intrinsic anti-inflammatory properties are potentially useful for treatments of inflammatory conditions such as uveitis, while their ability to differentiate along multiple cell lineages suggests use in regenerating damaged or degenerated tissue. However, how ASCs will respond to the intraocular environment is poorly studied. We have recently reported that aqueous humor (AH), the fluid that nourishes the anterior segment of the eye, potently increases alkaline phosphatase (ALP) activity of ASCs, indicating osteogenic differentiation. Here, we expand on our previous findings to better define the nature of this response. To this end, we cultured ASCs in the presence of 0, 5, 10, and 20% AH and assayed them for ALP activity. We found ALP activity correlates with increasing AH concentrations from 5 to 20%, and that longer treatments result in increased ALP activity. By using serum free media and pretreating AH with dextran-coated charcoal, we found that serum and charcoal-adsorbable AH components augment but are not required for this response. Further, by heat-treating the AH, we established that thermally labile components are required for the osteogenic response. Finally, we showed myocilin, a protein present in AH, could induce ALP activity in ASCs. However, this was to a lesser extent than untreated 5% AH, and myocilin could only partially rescue the effect after heat treatment, documenting there were additional thermally labile constituents of AH involved in the osteogenic response. Our work adds to the understanding of the induction of ALP in ASCs following exposure to AH, providing important insight in how ASCs will be influenced by the ocular environment. In conclusion, increased osteogenic potential upon exposure to AH represents a potential challenge to developing ASC cell-based therapies directed at the eye. PMID:25720657

  4. Thermally-Labile Trace Elements in Enstatite Meteorites

    NASA Technical Reports Server (NTRS)

    Wang, M.-S.; Lipschutz, M. E.

    2000-01-01

    RNAA data for Bi, In and Tl in 30 E3-6 chondrites accord well with trends for heated Abee (EH4) suggesting that all EH and EL samples reflect open-system, post-accretionary heating, independent of siderophile content or recovery location.

  5. Whole-Ecosystem Labile Carbon Production in a North Temperate Deciduous Forest

    NASA Astrophysics Data System (ADS)

    Gough, C. M.; Flower, C. E.; Vogel, C. S.; Dragoni, D.; Curtis, P. S.

    2008-12-01

    Management for forest carbon (C) sequestration requires knowledge of the fate of photosynthetic C. Labile C is an essential intermediary between C assimilation and growth in deciduous forests, accumulating when photosynthetic C supply exceeds demand and later depleting when reallocated to growth during periods of depressed photosynthesis. We developed a new approach that combined meteorological and biometric C cycling data for a mixed deciduous forest in Michigan, USA, to provide novel estimates of whole-ecosystem labile C production (PLC) and reallocation to growth inferred from the temporal imbalance between carbon supply from canopy net C assimilation (Ac) and C demand for net primary production (NPP). We substantiated these estimates with measurements of Populus grandidentata and Quercus rubra wood non-structural carbohydrate (NSC) concentration and mass over two years. Our analysis showed that half of annual Ac was allocated to PLC rather than to immediate growth. Labile C produced during the latter half of summer later supported dormant-season growth and respiration, with 35% of NPP in a given year requiring labile C stored during previous years. Seasonal changes in wood NSC concentration and mass generally corroborated patterns of labile C production and reallocation to growth. We observed a negative relationship between current-year PLC and NPP, indicating that disparities between same-year meteorological and biometric net ecosystem production (NEP) estimates can arise when C assimilated via photosynthesis, a flux incorporated into meteorological NEP estimates, is diverted away from NPP, a flux included in biometric NEP estimates, and instead allocated to PLC. A large, annually recharging pool of labile C also may buffer growth from climate conditions that immediately affect Ac. We conclude that a broader understanding of labile C production and reallocation across ecosystems may be important to interpreting lagged canopy C cycling and growth processes.

  6. Clostridium difficile and C. difficile Toxin Testing

    MedlinePLUS

    ... Sites Search Help? Clostridium difficile and C. difficile Toxin Testing Share this page: Was this page helpful? ... GDH Formal name: Clostridium difficile Culture; C. difficile Toxin, A and B; C. difficile Cytotoxin Assay; Glutamate ...

  7. EVALUATION OF DEVELOPMENTAL TOXICITY OF ALGAL TOXINS

    EPA Science Inventory

    The Office of Water is responsible for regulating waterborne pathogens and chemicals in drinking water. Algal toxins are present in some water sources but their reproductive risks are undetermined. Therefore, Algal toxins are being examined for potential developmental toxicity ...

  8. Synergism of Bacillus thuringiensis toxins by a fragment of a toxin-binding cadherin

    E-print Network

    Jurat-Fuentes, Juan Luis

    Synergism of Bacillus thuringiensis toxins by a fragment of a toxin-binding cadherin Jiang Chen with agricultural importance. The cadherin Bt-R1 is a binding protein for Bt Cry1A toxins in midgut epithelia- binding epitope (1416GVLTLNIQ1423) within the peptide was altered. Because the mixtures of low Bt toxin

  9. The Myriad Uses of Botulinum Toxin Botulinum toxin (BTx) is an important therapeutic

    E-print Network

    Pullman, Seth L.

    The Myriad Uses of Botulinum Toxin Botulinum toxin (BTx) is an important therapeutic agent- pared meat in the early 19th century. The toxin is a 150- kDa protein produced by Clostridium botulinum and com- posed of a heavy and light chain linked by a disulfide bond. When activated, the toxin targets

  10. Differential priming of soil carbon driven by soil depth and root impacts on carbon lability

    NASA Astrophysics Data System (ADS)

    De Graaff, M.; Jastrow, J. D.; Gilette, S.; Johns, A.; Wullschleger, S. D.

    2012-12-01

    An increase in root-derived labile soil carbon (C) inputs (e.g. exudates) can stimulate decomposition of more recalcitrant soil organic carbon (SOC) by priming microbial activity, which can lead to a net loss of soil C storage. This priming effect can be small or large and negative or positive, but the mechanisms by which root-C controls the magnitude and direction of SOC decomposition remain poorly understood. With this study we evaluated how small versus large differences in labile soil C availability affect microbial processing of simulated root exudate inputs and decomposition of SOC. We conducted a laboratory incubation experiment (60 days) with soils collected from under six switchgrass (Panicum virgatum) cultivars to a depth of 60 cm. Differences in specific root length among cultivars were expected to result in small differences in labile soil C availability, whereas differences associated with soil depth were expected to result in large differences in labile soil C availability. Soil cores were divided into 0-10 cm, 20-30 cm and 40-60 cm depth increments, and soils of all cultivars (no roots) across all three depths were incubated with addition of either: (1) water (60% water holding capacity), or (2) labile C provided as a 13C-labeled synthetic root exudate cocktail. We measured CO2 respiration throughout the experiment. The switchgrass was grown for three years in soils that formerly supported C3 pasture grasses, and the natural difference in 13C signature between C3 and C4 plants enabled quantification of differences in the lability of root-derived C among cultivars. Moreover the 13C labeled synthetic root-exudate cocktail amendment to soils allowed us to assess impacts of exudates-C addition on priming in soil derived from the different cultivars and from different depths. Our experiment led to three main results: (1) different cultivars of switchgrass regulate labile C availability across the soil profile differently; (2) small differences in labile C among the soils derived from different cultivars did not significantly mediate the impact of exudates-C additions on priming; (3) but, large differences in labile soil C contents among depths led to differences in priming effects, where greater priming effects were observed for shallow relative to deep soils across all days of the experiment. These results suggest that increased root-derived C inputs will have marginal impacts on decomposition of more stable SOC at depth and that their impact on priming will be similar in soils with small differences in available soil C.

  11. Risk Assessment of Shellfish Toxins

    PubMed Central

    Munday, Rex; Reeve, John

    2013-01-01

    Complex secondary metabolites, some of which are highly toxic to mammals, are produced by many marine organisms. Some of these organisms are important food sources for marine animals and, when ingested, the toxins that they produce may be absorbed and stored in the tissues of the predators, which then become toxic to animals higher up the food chain. This is a particular problem with shellfish, and many cases of poisoning are reported in shellfish consumers each year. At present, there is no practicable means of preventing uptake of the toxins by shellfish or of removing them after harvesting. Assessment of the risk posed by such toxins is therefore required in order to determine levels that are unlikely to cause adverse effects in humans and to permit the establishment of regulatory limits in shellfish for human consumption. In the present review, the basic principles of risk assessment are described, and the progress made toward robust risk assessment of seafood toxins is discussed. While good progress has been made, it is clear that further toxicological studies are required before this goal is fully achieved. PMID:24226039

  12. MCEARD - CYANOBACTERIA AND THEIR TOXINS

    EPA Science Inventory

    Harmful algal blooms (HAB) of cyanobacteria, also known as blue-green algae, have recently become more spatially and temporally prevalent in the US and worldwide. Waterborne cyanobacteria and their highly potent toxins are a significant hazard for human health and the ecosystem....

  13. Cholera toxin notches epithelial junctions.

    PubMed

    Lemichez, Emmanuel; Stefani, Caroline

    2013-09-11

    Cholera toxin (CT) is the factor responsible for watery diarrhea associated with Vibrio cholerae infection. In this issue, Guichard et al. (2013) report that CT compromises intestinal epithelium barrier function via cyclic AMP (cAMP)-induced disruption of Rab11- and exocyst-dependent delivery of endocytic recycling cargo to cell-cell junctions. PMID:24034608

  14. The polychaete worm Nereis diversicolor increases mercury lability and methylation in intertidal mudflats.

    PubMed

    Sizmur, Tom; Canário, João; Edmonds, Samuel; Godfrey, Adam; O'Driscoll, Nelson J

    2013-08-01

    The polychaete worm Nereis diversicolor engineers its environment by creating oxygenated burrows in anoxic intertidal sediments. The authors carried out a laboratory microcosm experiment to test the impact of polychaete burrowing and feeding activity on the lability and methylation of mercury in sediments from the Bay of Fundy, Canada. The concentration of labile inorganic mercury and methylmercury in burrow walls was elevated compared to worm-free sediments. Mucus secretions and organic detritus in worm burrows increased labile mercury concentrations. Worms decreased sulfide concentrations, which increased Hg bioavailability to sulfate-reducing bacteria and increased methylmercury concentrations in burrow linings. Because the walls of polychaete burrows have a greater interaction with organisms, and the overlying water, the concentrations of mercury and methylmercury they contain is more toxicologically relevant to the base of a coastal food web than bulk samples. The authors recommend that researchers examining Hg in marine environments account for sediment dwelling invertebrate activity to more fully assess mercury bioavailability. PMID:23633443

  15. Nemertean toxin genes revealed through transcriptome sequencing.

    PubMed

    Whelan, Nathan V; Kocot, Kevin M; Santos, Scott R; Halanych, Kenneth M

    2014-12-01

    Nemerteans are one of few animal groups that have evolved the ability to utilize toxins for both defense and subduing prey, but little is known about specific nemertean toxins. In particular, no study has identified specific toxin genes even though peptide toxins are known from some nemertean species. Information about toxin genes is needed to better understand evolution of toxins across animals and possibly provide novel targets for pharmaceutical and industrial applications. We sequenced and annotated transcriptomes of two free-living and one commensal nemertean and annotated an additional six publicly available nemertean transcriptomes to identify putative toxin genes. Approximately 63-74% of predicted open reading frames in each transcriptome were annotated with gene names, and all species had similar percentages of transcripts annotated with each higher-level GO term. Every nemertean analyzed possessed genes with high sequence similarities to known animal toxins including those from stonefish, cephalopods, and sea anemones. One toxin-like gene found in all nemerteans analyzed had high sequence similarity to Plancitoxin-1, a DNase II hepatotoxin that may function well at low pH, which suggests that the acidic body walls of some nemerteans could work to enhance the efficacy of protein toxins. The highest number of toxin-like genes found in any one species was seven and the lowest was three. The diversity of toxin-like nemertean genes found here is greater than previously documented, and these animals are likely an ideal system for exploring toxin evolution and industrial applications of toxins. PMID:25432940

  16. Anti-muscarinic toxins from Dendroaspis angusticeps.

    PubMed

    Liang, J S; Carsi-Gabrenas, J; Krajewski, J L; McCafferty, J M; Purkerson, S L; Santiago, M P; Strauss, W L; Valentine, H H; Potter, L T

    1996-01-01

    Toxins from the venom of the African green mamba, Dendroaspis angusticeps, fulfill a major need for selective ligands for some of the five genetically defined subtypes of muscarinic acetylcholine receptors (m1-m5). Two toxins have been found that are highly selective antagonists for m1 and m4 receptors (m1-toxin and m4-toxin, respectively). Two other toxins (MT1 and MT2) bind with high affinity to both m1 and m4 receptors, and are agonists. Components of the venom also modify the binding of radiolabeled antagonists to m2 receptors, but an m2-selective toxin has not yet been isolated, m1-Toxin can bind to m1 receptors at the same time as typical competitive antagonists, suggesting that this toxin binds to the N-terminal and outer loops of m1 receptor molecules, rather than within the receptor pocket where typical agonists and antagonists bind. The binding of toxins to the outer parts of receptor molecules probably accounts for their much higher specificity for individual receptor subtypes than is seen with smaller ligands. Toxins are useful for identifying, counting, localizing, activating and blocking m1 and m4 receptors with high specificity. PMID:9027981

  17. A Longitudinal Study of Emotion Regulation, Emotion Lability/Negativity, and Internalizing Symptomatology in Maltreated and Nonmaltreated Children

    PubMed Central

    Kim-Spoon, Jungmeen; Cicchetti, Dante; Rogosch, Fred A.

    2013-01-01

    The longitudinal contributions of emotion regulation and emotion lability/negativity to internalizing symptomatology were examined in a low-income sample (171 maltreated and 151 nonmaltreated children, from age 7 to 10 years). Latent difference score models indicated that, for both maltreated and nonmaltreated children, emotion regulation was a mediator between emotion lability/negativity and internalizing symptomatology, whereas emotion lability/negativity was not a mediator between emotion regulation and internalizing symptomatology. Early maltreatment was associated with high emotion lability/negativity (age 7) that contributed to poor emotion regulation (age 8), which in turn was predictive of increases in internalizing symptomatology (from age 8 to 9). The results imply important roles of emotion regulation in the development of internalizing symptomatology, especially for children with high emotion lability/negativity. PMID:23034132

  18. Research paper The determination of labile Fe in ferrihydrite by ascorbic acid extraction

    E-print Network

    Benning, Liane G.

    Research paper The determination of labile Fe in ferrihydrite by ascorbic acid extraction August 2010 Accepted 1 September 2010 Editor: J.D. Blum Keywords: Ferrihydrite Ascorbic acid Dissolution kinetics Aggregation Aging An ascorbic acid extraction at pH 7.5 has been examined to assess the influence

  19. Non-labile silver species in biosolids remain stable throughout 50 years of weathering and ageing.

    EPA Science Inventory

    Increasing commercial use of nanosilver has focussed attention on the fate of silver (Ag) in the wastewater release pathway. This paper reports the speciation and lability of Ag in archived, stockpiled, and contemporary biosolids from the UK, USA and Australia, and indicates that...

  20. Dual selective iron chelating probes with a potential to monitor mitochondrial labile iron pools.

    PubMed

    Abbate, Vincenzo; Reelfs, Olivier; Kong, Xiaole; Pourzand, Charareh; Hider, Robert C

    2015-12-24

    Mitochondria-targeted peptides incorporating dual fluorescent and selective iron chelators have been designed as novel biosensors for the mitochondrial labile iron pool. The probes were demonstrated to specifically co-localize with mitochondria and their fluorescence emission was found to be sensitive to the presence of iron. PMID:26567874

  1. Forms and Lability of Phosphorus in Humic Acid Fractions of Hord Silt Loam Soil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Phosphorus (P) has long been known to be present in soil humic fractions, but little is known about specific P forms in humic fractions, or their lability. We extracted the mobile humic acid (MHA) and recalcitrant calcium humate (CaHA) fractions from a Nebraska Hord silt loam soil under continuous c...

  2. Enzymatically- and Ultraviolet-labile Phosphorus in Humic Acid Fractions From Rice Soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Humic acid is an important soil component which can improve nutrient availability and impact other important chemical, biological, and physical properties of soils. We investigated the lability of phosphorus (P) in the mobile humic acid (MHA) and calcium humate (CaHA) fractions of four rice soils as...

  3. Non-labile silver species in biosolids remain stable throughout 50 years of weathering and ageing.

    PubMed

    Donner, E; Scheckel, K; Sekine, R; Popelka-Filcoff, R S; Bennett, J W; Brunetti, G; Naidu, R; McGrath, S P; Lombi, E

    2015-10-01

    Increasing commercial use of nanosilver has focussed attention on the fate of silver (Ag) in the wastewater release pathway. This paper reports the speciation and lability of Ag in archived, stockpiled, and contemporary biosolids from the UK, USA and Australia, and indicates that biosolids Ag concentrations have decreased significantly over recent decades. XANES revealed the importance of reduced-sulfur binding environments for Ag speciation in materials ranging from freshly produced sludge to biosolids weathered under ambient environmental conditions for more than 50 years. Isotopic dilution with (110 m)Ag showed that Ag was predominantly non-labile in both fresh and aged biosolids (13.7% mean lability), with E-values ranging from 0.3 to 60 mg/kg and 5 mM CaNO3 extractable Ag from 1.2 to 609 ?g/kg (0.002-3.4% of the total Ag). This study indicates that at the time of soil application, biosolids Ag will be predominantly Ag-sulfides and characterised by low isotopic lability. PMID:26021819

  4. Novel Class of Spider Toxin

    PubMed Central

    Vassilevski, Alexander A.; Fedorova, Irina M.; Maleeva, Ekaterina E.; Korolkova, Yuliya V.; Efimova, Svetlana S.; Samsonova, Olga V.; Schagina, Ludmila V.; Feofanov, Alexei V.; Magazanik, Lev G.; Grishin, Eugene V.

    2010-01-01

    Venom of the yellow sac spider Cheiracanthium punctorium (Miturgidae) was found unique in terms of molecular composition. Its principal toxic component CpTx 1 (15.1 kDa) was purified, and its full amino acid sequence (134 residues) was established by protein chemistry and mass spectrometry techniques. CpTx 1 represents a novel class of spider toxin with modular architecture. It consists of two different yet homologous domains (modules) each containing a putative inhibitor cystine knot motif, characteristic of the widespread single domain spider neurotoxins. Venom gland cDNA sequencing provided precursor protein (prepropeptide) structures of three CpTx 1 isoforms (a–c) that differ by single residue substitutions. The toxin possesses potent insecticidal (paralytic and lethal), cytotoxic, and membrane-damaging activities. In both fly and frog neuromuscular preparations, it causes stable and irreversible depolarization of muscle fibers leading to contracture. This effect appears to be receptor-independent and is inhibited by high concentrations of divalent cations. CpTx 1 lyses cell membranes, as visualized by confocal microscopy, and destabilizes artificial membranes in a manner reminiscent of other membrane-active peptides by causing numerous defects of variable conductance and leading to bilayer rupture. The newly discovered class of modular polypeptides enhances our knowledge of the toxin universe. PMID:20657014

  5. Oxygen consumption and labile dissolved organic carbon uptake by benthic biofilms

    NASA Astrophysics Data System (ADS)

    de Falco, Natalie; Boano, Fulvio; Arnon, Shai

    2015-04-01

    Biogeochemical activity in streams is often magnified at interfaces, such as in the case of biofilm growth near the surface of the stream sediments. The objective of this study was to evaluate the relative importance of surficial biofilms versus the biofilm in the hyporheic zone to the processes of biodegradation of a labile dissolved organic carbon (DOC) and to oxygen consumption. Experiments were conducted in a recirculating flume, equipped with a drainage system that enables the control on losing and gaining fluxes. A surficial biofilm was developed over a sandy streambed with dune-shaped bed forms, by providing labile DOC (sodium benzoate) and nitrate. Homogeneously distributed biofilm was obtained by the same feeding strategy but with mixing the sediments manually on a daily basis. After the biofilm growth period, transformation of the labile DOC under different overlying velocities and losing or gaining fluxes was studied after spiking with sodium benzoate and by monitoring the decrease in DOC concentration in the bulk water over time using an online UV/Vis spectrophotometer. In addition, oxygen profiles across the water-streambed interface were measured at different locations along the bed form using oxygen microelectrodes. Preliminary results showed that the rate of labile DOC degradation increased exponentially with increasing overlying water velocity, regardless of the type of biofilm. Gaining and losing conditions did not play a critical role in the DOC degradation regardless of the type of biofilm, because the labile DOC was quickly utilized close to the surface. Under losing conditions, complete depletion of oxygen was observed within the top 5 millimeters, regardless of the biofilm type. In contrast, oxygen profiles under gaining condition showed an incomplete consumption of oxygen followed by an increase in the concentration of oxygen deeper in the sediments due to the upward flow of oxygenated groundwater. The results suggest that the transformation of labile DOC occurs in the upper millimeters of the streambed, and the size and shape of the hyporheic flow paths are less important for aerobic activity. In addition, the effect of overlying water velocity on labile DOC transformation was shown to be more influential than losing and gaining fluxes.

  6. YoeB toxin is activated during thermal stress

    PubMed Central

    Janssen, Brian D; Garza-Sánchez, Fernando; Hayes, Christopher S

    2015-01-01

    Type II toxin-antitoxin (TA) modules are thought to mediate stress-responses by temporarily suppressing protein synthesis while cells redirect transcription to adapt to environmental change. Here, we show that YoeB, a ribosome-dependent mRNase toxin, is activated in Escherichia coli cells grown at elevated temperatures. YoeB activation is dependent on Lon protease, suggesting that thermal stress promotes increased degradation of the YefM antitoxin. Though YefM is efficiently degraded in response to Lon overproduction, we find that Lon antigen levels do not increase during heat shock, indicating that another mechanism accounts for temperature-induced YefM proteolysis. These observations suggest that YefM/YoeB functions in adaptation to temperature stress. However, this response is distinct from previously described models of TA function. First, YoeB mRNase activity is maintained over several hours of culture at 42°C, indicating that thermal activation is not transient. Moreover, heat-activated YoeB does not induce growth arrest nor does it suppress global protein synthesis. In fact, E. coli cells proliferate more rapidly at elevated temperatures and instantaneously accelerate their growth rate in response to acute heat shock. We propose that heat-activated YoeB may serve a quality control function, facilitating the recycling of stalled translation complexes through ribosome rescue pathways. PMID:26147890

  7. Bacterial protein toxins in human cancers.

    PubMed

    Rosadi, Francesca; Fiorentini, Carla; Fabbri, Alessia

    2016-02-01

    Many bacteria causing persistent infections produce toxins whose mechanisms of action indicate that they could have a role in carcinogenesis. Some toxins, like CDT and colibactin, directly attack the genome by damaging DNA whereas others, as for example CNF1, CagA and BFT, impinge on key eukaryotic processes, such as cellular signalling and cell death. These bacterial toxins, together with other less known toxins, mimic carcinogens and tumour promoters. The aim of this review is to fulfil an up-to-date analysis of toxins with carcinogenic potential that have been already correlated to human cancers. Bacterial toxins-induced carcinogenesis represents an emerging aspect in bacteriology, and its significance is increasingly recognized. PMID:26534910

  8. Bt Toxin Modification for Enhanced Efficacy

    PubMed Central

    Deist, Benjamin R.; Rausch, Michael A.; Fernandez-Luna, Maria Teresa; Adang, Michael J.; Bonning, Bryony C.

    2014-01-01

    Insect-specific toxins derived from Bacillus thuringiensis (Bt) provide a valuable resource for pest suppression. Here we review the different strategies that have been employed to enhance toxicity against specific target species including those that have evolved resistance to Bt, or to modify the host range of Bt crystal (Cry) and cytolytic (Cyt) toxins. These strategies include toxin truncation, modification of protease cleavage sites, domain swapping, site-directed mutagenesis, peptide addition, and phage display screens for mutated toxins with enhanced activity. Toxin optimization provides a useful approach to extend the utility of these proteins for suppression of pests that exhibit low susceptibility to native Bt toxins, and to overcome field resistance. PMID:25340556

  9. Bt toxin modification for enhanced efficacy.

    PubMed

    Deist, Benjamin R; Rausch, Michael A; Fernandez-Luna, Maria Teresa; Adang, Michael J; Bonning, Bryony C

    2014-10-01

    Insect-specific toxins derived from Bacillus thuringiensis (Bt) provide a valuable resource for pest suppression. Here we review the different strategies that have been employed to enhance toxicity against specific target species including those that have evolved resistance to Bt, or to modify the host range of Bt crystal (Cry) and cytolytic (Cyt) toxins. These strategies include toxin truncation, modification of protease cleavage sites, domain swapping, site-directed mutagenesis, peptide addition, and phage display screens for mutated toxins with enhanced activity. Toxin optimization provides a useful approach to extend the utility of these proteins for suppression of pests that exhibit low susceptibility to native Bt toxins, and to overcome field resistance. PMID:25340556

  10. Glaciers as a source of ancient and labile organic matter to the marine environment.

    PubMed

    Hood, Eran; Fellman, Jason; Spencer, Robert G M; Hernes, Peter J; Edwards, Rick; D'Amore, David; Scott, Durelle

    2009-12-24

    Riverine organic matter supports of the order of one-fifth of estuarine metabolism. Coastal ecosystems are therefore sensitive to alteration of both the quantity and lability of terrigenous dissolved organic matter (DOM) delivered by rivers. The lability of DOM is thought to vary with age, with younger, relatively unaltered organic matter being more easily metabolized by aquatic heterotrophs than older, heavily modified material. This view is developed exclusively from work in watersheds where terrestrial plant and soil sources dominate streamwater DOM. Here we characterize streamwater DOM from 11 coastal watersheds on the Gulf of Alaska that vary widely in glacier coverage (0-64 per cent). In contrast to non-glacial rivers, we find that the bioavailability of DOM to marine microorganisms is significantly correlated with increasing (14)C age. Moreover, the most heavily glaciated watersheds are the source of the oldest ( approximately 4 kyr (14)C age) and most labile (66 per cent bioavailable) DOM. These glacial watersheds have extreme runoff rates, in part because they are subject to some of the highest rates of glacier volume loss on Earth. We estimate the cumulative flux of dissolved organic carbon derived from glaciers contributing runoff to the Gulf of Alaska at 0.13 +/- 0.01 Tg yr(-1) (1 Tg = 10(12) g), of which approximately 0.10 Tg is highly labile. This indicates that glacial runoff is a quantitatively important source of labile reduced carbon to marine ecosystems. Moreover, because glaciers and ice sheets represent the second largest reservoir of water in the global hydrologic system, our findings indicate that climatically driven changes in glacier volume could alter the age, quantity and reactivity of DOM entering coastal oceans. PMID:20033045

  11. Rho-modifying bacterial protein toxins.

    PubMed

    Aktories, Klaus

    2015-12-01

    Rho proteins are targets of numerous bacterial protein toxins, which manipulate the GTP-binding proteins by covalent modifications, including ADP ribosylation, glycosylation, adenylylation, proteolytic cleavage and deamidation. Bacterial toxins are important virulence factors but are also potent and efficient pharmacological tools to study the physiological functions of their eukaryotic targets. Recent studies indicate that amazing variations exist in the molecular mechanisms by which toxins attack Rho proteins, which are discussed here. PMID:26454272

  12. APPLICATION FOR REQUEST OF AN EXCLUDED SELECT TOXIN Montana State University Transfer of Excluded Select Toxins

    E-print Network

    Maxwell, Bruce D.

    APPLICATION FOR REQUEST OF AN EXCLUDED SELECT TOXIN Montana State University Transfer of Excluded Select Toxins is in accordance with 42 CFR §73. 1) Recipient (Name, organization, complete, address, telephone and fax number of individual who will receive and be responsible for the toxin) 2) Transferor

  13. Role of the disulfide bond in Shiga toxin A-chain for toxin entry into cells.

    PubMed

    Garred, O; Dubinina, E; Polesskaya, A; Olsnes, S; Kozlov, J; Sandvig, K

    1997-04-25

    Shiga toxin consists of an enzymatically active A-chain and a pentameric binding subunit. The A-chain has a trypsin-sensitive region, and upon cleavage two disulfide bonded fragments, A1 and A2, are generated. To study the role of the disulfide bond, it was eliminated by mutating cysteine 242 to serine. In T47D cells this mutated toxin was more toxic than wild type toxin after a short incubation, whereas after longer incubation times wild type toxin was most toxic. Cells cleaved not only wild type but also mutated A-chain into A1 and A2 fragments. The mutated A-chain was more sensitive than wild type toxin to Pronase, and it was degraded at a higher rate in T47D cells. Subcellular fractionation demonstrated transport of both wild type and mutated toxin to the Golgi apparatus. Brefeldin A, which disrupts the Golgi apparatus, protected not only against Shiga toxin but also against the mutated toxin, indicating involvement of the Golgi apparatus. After prebinding of Shiga(C242S) toxin to wells coated with the Shiga toxin receptor, Gb3, trypsin treatment induced dissociation of A1 from the toxin-receptor complex demonstrating that in addition to stabilizing the A-chain, the disulfide bond prevents dissociation of the A1 fragment from the toxin-receptor complex. PMID:9111051

  14. Geldanamycin Enhances Retrograde Transport of Shiga Toxin in HEp-2 Cells

    PubMed Central

    Simm, Roger; Torgersen, Maria Lyngaas; Sandvig, Kirsten

    2015-01-01

    The heat shock protein 90 (Hsp90) inhibitor geldanamycin (GA) has been shown to alter endosomal sorting, diverting cargo destined for the recycling pathway into the lysosomal pathway. Here we investigated whether GA also affects the sorting of cargo into the retrograde pathway from endosomes to the Golgi apparatus. As a model cargo we used the bacterial toxin Shiga toxin, which exploits the retrograde pathway as an entry route to the cytosol. Indeed, GA treatment of HEp-2 cells strongly increased the Shiga toxin transport to the Golgi apparatus. The enhanced Golgi transport was not due to increased endocytic uptake of the toxin or perturbed recycling, suggesting that GA selectively enhances endosomal sorting into the retrograde pathway. Moreover, GA activated p38 and both inhibitors of p38 or its substrate MK2 partially counteracted the GA-induced increase in Shiga toxin transport. Thus, our data suggest that GA-induced p38 and MK2 activation participate in the increased Shiga toxin transport to the Golgi apparatus. PMID:26017782

  15. Dissolved organic carbon lability increases with water residence time in the alluvial aquifer of a river floodplain ecosystem

    NASA Astrophysics Data System (ADS)

    Helton, Ashley M.; Wright, Meredith S.; Bernhardt, Emily S.; Poole, Geoffrey C.; Cory, Rose M.; Stanford, Jack A.

    2015-04-01

    We assessed spatial and temporal patterns of dissolved organic carbon (DOC) lability and composition throughout the alluvial aquifer of the 16 km2 Nyack Floodplain in northwest Montana, USA. Water influx to the aquifer derives almost exclusively from the Middle Fork of the Flathead River, and water residence times within the aquifer range from days to months. Across seasons and channel discharge conditions, we measured DOC concentration, lability, and optical properties of aquifer water sampled from 12 wells, both near and ~3 m below the water table. Concentrations of DOC were typically low (542 ± 22.7 µg L-1; mean ± se), and the percentage of labile DOC averaged 18 ± 12% during 3 day laboratory assays. Parallel factor analysis of fluorescence excitation-emission matrices revealed two humic-like and two amino acid-like fluorescence groups. Total DOC, humic-like components, and specific UV absorbance decreased with water residence time, consistent with sorption to aquifer sediments. However, labile DOC (both concentration and fraction) increased with water residence time, suggesting a concurrent influx or production of labile DOC. Thus, although the carbon-poor, oxygen-rich aquifer is a net sink for DOC, recalcitrant DOC appears to be replaced with more labile DOC along aquifer flow paths. Our observation of DOC production in long flow paths contrasts with studies of hyporheic DOC consumption along short (centimeters to meters) flow paths and highlights the importance of understanding the role of labile organic matter production and/or influx in alluvial aquifer carbon cycling.

  16. Target-Driven Evolution of Scorpion Toxins

    PubMed Central

    Zhang, Shangfei; Gao, Bin; Zhu, Shunyi

    2015-01-01

    It is long known that peptide neurotoxins derived from a diversity of venomous animals evolve by positive selection following gene duplication, yet a force that drives their adaptive evolution remains a mystery. By using maximum-likelihood models of codon substitution, we analyzed molecular adaptation in scorpion sodium channel toxins from a specific species and found ten positively selected sites, six of which are located at the core-domain of scorpion ?-toxins, a region known to interact with two adjacent loops in the voltage-sensor domain (DIV) of sodium channels, as validated by our newly constructed computational model of toxin-channel complex. Despite the lack of positive selection signals in these two loops, they accumulated extensive sequence variations by relaxed purifying selection in prey and predators of scorpions. The evolutionary variability in the toxin-bound regions of sodium channels indicates that accelerated substitutions in the multigene family of scorpion toxins is a consequence of dealing with the target diversity. This work presents an example of atypical co-evolution between animal toxins and their molecular targets, in which toxins suffered from more prominent selective pressure from the channels of their competitors. Our discovery helps explain the evolutionary rationality of gene duplication of toxins in a specific venomous species. PMID:26444071

  17. Strengthening the Biological and Toxin Weapons Convention

    E-print Network

    Sussex, University of

    Strengthening the Biological and Toxin Weapons Convention: Countering the Threat from Biological Weapons Presented to Parliament by the Secretary of State for Foreign and Commonwealth Affairs By Command of Her Majesty April 2002 Cm 5484 £5.00 #12;3 STRENGTHENING THE BIOLOGICAL AND TOXIN WEAPONS CONVENTION

  18. Plant Insecticidal Toxins in Ecological Networks

    PubMed Central

    Ibanez, Sébastien; Gallet, Christiane; Després, Laurence

    2012-01-01

    Plant secondary metabolites play a key role in plant-insect interactions, whether constitutive or induced, C- or N-based. Anti-herbivore defences against insects can act as repellents, deterrents, growth inhibitors or cause direct mortality. In turn, insects have evolved a variety of strategies to act against plant toxins, e.g., avoidance, excretion, sequestration and degradation of the toxin, eventually leading to a co-evolutionary arms race between insects and plants and to co-diversification. Anti-herbivore defences also negatively impact mutualistic partners, possibly leading to an ecological cost of toxin production. However, in other cases toxins can also be used by plants involved in mutualistic interactions to exclude inadequate partners and to modify the cost/benefit ratio of mutualism to their advantage. When considering the whole community, toxins have an effect at many trophic levels. Aposematic insects sequester toxins to defend themselves against predators. Depending on the ecological context, toxins can either increase insects’ vulnerability to parasitoids and entomopathogens or protect them, eventually leading to self-medication. We conclude that studying the community-level impacts of plant toxins can provide new insights into the synthesis between community and evolutionary ecology. PMID:22606374

  19. Botulinum Toxin and Gastrointestinal Tract Disorders

    PubMed Central

    Weiser, Kirsten; Kennedy, Abigail

    2008-01-01

    The history of botulinum toxin is fascinating. First recognized as the cause of botulism nearly 200 years ago, it was originally feared as a deadly poison. Over the last 30 years, however, botulinum toxin has been transformed into a readily available medication used to treat a variety of medical disorders. Interest in the use of botulinum toxin has been particularly strong for patients with spastic smooth muscle disorders of the gastrointestinal tract. Patients with achalasia, diffuse esophageal spasm, gastroparesis, sphincter of Oddi dysfunction, and anal fissures have all been treated with botulinum toxin injections, often with impressive results. However, not all patients respond to botulinum toxin therapy, and large randomized controlled trials are lacking for many conditions commonly treated with botulinum toxin. This paper reviews the history, microbiology, and pharmacology of botulinum toxin, discusses its mechanism of action, and then presents recent evidence from the literature regarding the use of botulinum toxin for the treatment of a variety of gastrointestinal tract disorders. PMID:21960915

  20. [Botulinum toxin: clinical uses and anesthetic implications].

    PubMed

    Vidal-Marcos, A; Sanz-García, M; Infante-Crespo, B; Ruiz-Castro, M; Rustarazo-Pérez, M T; Palma-Gámiz, M A

    1996-01-01

    Botulinum toxin, a neurotoxin responsible for botulism, is at present used to treat anomalous muscle contractions. Administration to children and relatively uncooperative patients requires general anesthesia, which should be selected taking into consideration the special characteristics of the surgical procedure and the possible interactions of anesthetic drugs and the toxin. PMID:8756235

  1. Formation and Control of Cyanobacterial Toxins

    EPA Science Inventory

    This presentation will cover the formation of harmful algal blooms and the control of their toxins. Data will be presented from current ORD projects on the treatment of cyanobacterial toxins through drinking water treatment facilities. The results will demonstrate that current c...

  2. Human genetic variation altering anthrax toxin sensitivity

    E-print Network

    Tang, Hua

    Human genetic variation altering anthrax toxin sensitivity Mikhail Martchenkoa , Sophie I affecting capillary morphogenesis gene 2 (CMG2), which encodes a host membrane protein exploited by anthrax in sensitivity me- diated by the protective antigen (PA) moiety of anthrax toxin by more than four orders

  3. Target-Driven Evolution of Scorpion Toxins.

    PubMed

    Zhang, Shangfei; Gao, Bin; Zhu, Shunyi

    2015-01-01

    It is long known that peptide neurotoxins derived from a diversity of venomous animals evolve by positive selection following gene duplication, yet a force that drives their adaptive evolution remains a mystery. By using maximum-likelihood models of codon substitution, we analyzed molecular adaptation in scorpion sodium channel toxins from a specific species and found ten positively selected sites, six of which are located at the core-domain of scorpion ?-toxins, a region known to interact with two adjacent loops in the voltage-sensor domain (DIV) of sodium channels, as validated by our newly constructed computational model of toxin-channel complex. Despite the lack of positive selection signals in these two loops, they accumulated extensive sequence variations by relaxed purifying selection in prey and predators of scorpions. The evolutionary variability in the toxin-bound regions of sodium channels indicates that accelerated substitutions in the multigene family of scorpion toxins is a consequence of dealing with the target diversity. This work presents an example of atypical co-evolution between animal toxins and their molecular targets, in which toxins suffered from more prominent selective pressure from the channels of their competitors. Our discovery helps explain the evolutionary rationality of gene duplication of toxins in a specific venomous species. PMID:26444071

  4. MARTX toxins as effector delivery platforms.

    PubMed

    Gavin, Hannah E; Satchell, Karla J F

    2015-12-01

    Bacteria frequently manipulate their host environment via delivery of microbial 'effector' proteins to the cytosol of eukaryotic cells. In the case of the multifunctional autoprocessing repeats-in-toxins (MARTX) toxin, this phenomenon is accomplished by a single, >3500 amino acid polypeptide that carries information for secretion, translocation, autoprocessing and effector activity. MARTX toxins are secreted from bacteria by dedicated Type I secretion systems. The released MARTX toxins form pores in target eukaryotic cell membranes for the delivery of up to five cytopathic effectors, each of which disrupts a key cellular process. Targeted cellular processes include modulation or modification of small GTPases, manipulation of host cell signaling and disruption of cytoskeletal integrity. More recently, MARTX toxins have been shown to be capable of heterologous protein translocation. Found across multiple bacterial species and genera-frequently in pathogens lacking Type 3 or Type 4 secretion systems-MARTX toxins in multiple cases function as virulence factors. Innovative research at the intersection of toxin biology and bacterial genetics continues to elucidate the intricacies of the toxin as well as the cytotoxic mechanisms of its diverse effector collection. PMID:26472741

  5. Brown spider dermonecrotic toxin directly induces nephrotoxicity

    SciTech Connect

    Chaim, Olga Meiri; Sade, Youssef Bacila; Bertoni da Silveira, Rafael; Toma, Leny; Kalapothakis, Evanguedes; Chavez-Olortegui, Carlos; Mangili, Oldemir Carlos; Gremski, Waldemiro; Dietrich, Carl Peter von; Nader, Helena B.; Sanches Veiga, Silvio . E-mail: veigass@ufpr.br

    2006-02-15

    Brown spider (Loxosceles genus) venom can induce dermonecrotic lesions at the bite site and systemic manifestations including fever, vomiting, convulsions, disseminated intravascular coagulation, hemolytic anemia and acute renal failure. The venom is composed of a mixture of proteins with several molecules biochemically and biologically well characterized. The mechanism by which the venom induces renal damage is unknown. By using mice exposed to Loxosceles intermedia recombinant dermonecrotic toxin (LiRecDT), we showed direct induction of renal injuries. Microscopic analysis of renal biopsies from dermonecrotic toxin-treated mice showed histological alterations including glomerular edema and tubular necrosis. Hyalinization of tubules with deposition of proteinaceous material in the tubule lumen, tubule epithelial cell vacuoles, tubular edema and epithelial cell lysis was also observed. Leukocytic infiltration was neither observed in the glomerulus nor the tubules. Renal vessels showed no sign of inflammatory response. Additionally, biochemical analyses showed such toxin-induced changes in renal function as urine alkalinization, hematuria and azotemia with elevation of blood urea nitrogen levels. Immunofluorescence with dermonecrotic toxin antibodies and confocal microscopy analysis showed deposition and direct binding of this toxin to renal intrinsic structures. By immunoblotting with a hyperimmune dermonecrotic toxin antiserum on renal lysates from toxin-treated mice, we detected a positive signal at the region of 33-35 kDa, which strengthens the idea that renal failure is directly induced by dermonecrotic toxin. Immunofluorescence reaction with dermonecrotic toxin antibodies revealed deposition and binding of this toxin directly in MDCK epithelial cells in culture. Similarly, dermonecrotic toxin treatment caused morphological alterations of MDCK cells including cytoplasmic vacuoles, blebs, evoked impaired spreading and detached cells from each other and from culture substratum. In addition, dermonecrotic toxin treatment of MDCK cells changed their viability evaluated by XTT and Neutral-Red Uptake methodologies. The present results point to brown spider dermonecrotic toxin cytotoxicity upon renal structures in vivo and renal cells in vitro and provide experimental evidence that this brown spider toxin is directly involved in nephrotoxicity evoked during Loxosceles spider venom accidents.

  6. The toxin component of targeted anti-tumor toxins determines their efficacy increase by saponins.

    PubMed

    Weng, Alexander; Thakur, Mayank; Beceren-Braun, Figen; Bachran, Diana; Bachran, Christopher; Riese, Sebastian B; Jenett-Siems, Kristina; Gilabert-Oriol, Roger; Melzig, Matthias F; Fuchs, Hendrik

    2012-06-01

    Tumor-targeting protein toxins are composed of a toxic enzyme coupled to a specific cell binding domain that targets cancer-associated antigens. The anti-tumor treatment by targeted toxins is accompanied by dose-limiting side effects. The future prospects of targeted toxins for therapeutic use in humans will be determined by reduce side effects. Certain plant secondary metabolites (saponins) were shown to increase the efficacy of a particular epidermal growth factor receptor (EGFR)-targeted toxin, paralleled by a tremendous decrease of side effects. This study was conducted in order to investigate the effects of substituting different toxin moieties fused to an EGF ligand binding domain on the augmentative ability of saponins for each against therapeutic potential of the saponin-mediated efficacy increase for different anti-tumor toxins targeting the EGFR. We designed several EGFR-targeted toxins varying in the toxic moiety. Each targeted toxin was used in combination with a purified saponin (SA1641), isolated from the ornamental plant Gypsophila paniculata L. SA1641 was characterized and the SA1641-mediated efficacy increase was investigated on EGFR-transfected NIH-3T3 cells. We observed a high dependency of the SA1641-mediated efficacy increase on the nature of toxin used for the construction of the targeted toxin, indicating high specificity. Structural alignments revealed a high homology between saporin and dianthin-30, the two toxic moieties that benefit most from the combination with SA1641. We further demonstrate that SA1641 did not influence the plasma membrane permeability, indicating an intracellular interaction of SA1641 and the toxin components of targeted toxins. Surface plasmon resonance measurements point to a transient binding of SA1641 to the toxin components of targeted toxins. PMID:22309811

  7. Identification and purification of target protein using affinity resin bearing a photo-labile linker.

    PubMed

    Mabuchi, Miyuki; Shimizu, Tadashi; Haramura, Masayuki; Tanaka, Akito

    2015-08-15

    This Letter presents an effective method for the identification of target proteins of bioactive compounds such as drugs, natural products, and intrinsic ligands, using an affinity resin. The application of a photo-labile linker to an affinity resin enabled the selective elution of a target protein by irradiation for a short duration at 4 °C while leaving a large amount of non-specific binding protein on the resin. We have named this method the 'STEAP' method (selective target elution from affinity resins with photo-labile linker). Only a target protein that can bind the bioactive compound, the so-called 'active' protein, is eluted by the selective cleavage of the linker between the solid matrix and the target compound, and therefore, it is worth considering the potential of this method for the hyper-purification of proteins. PMID:26099537

  8. Relationship between the lability of sediment-bound Cd and its bioaccumulation in edible oyster.

    PubMed

    Chakraborty, Parthasarathi; Ramteke, Darwin; Chakraborty, Sucharita; Chennuri, Kartheek; Bardhan, Pratirupa

    2015-11-15

    A linkage between Cd speciation in sediments and its bioaccumulation in edible oyster (Crassostrea sp.) from a tropical estuarine system was established. Bioaccumulation of Cd in edible oyster increased with the increasing lability and dissociation rate constants of Cd-sediment complexes in the bottom sediments. Total Cd concentration in sediment was not a good indicator of Cd-bioavailability. Increasing trace metal competition in sediments increased lability and bioavailability of Cd in the tropical estuarine sediment. Low thermodynamic stability and high bioavailability of Cd in the estuarine sediment were responsible for high bioaccumulation of Cd in edible oysters (3.2-12.2mgkg(-1)) even though the total concentration of Cd in the bottom sediment was low (0.17-0.49mgkg(-1)). PMID:26359116

  9. Toxins and Secretion Systems of Photorhabdus luminescens

    PubMed Central

    Rodou, Athina; Ankrah, Dennis O.; Stathopoulos, Christos

    2010-01-01

    Photorhabdus luminescens is a nematode-symbiotic, gram negative, bioluminescent bacterium, belonging to the family of Enterobacteriaceae. Recent studies show the importance of this bacterium as an alternative source of insecticides, as well as an emerging human pathogen. Various toxins have been identified and characterized in this bacterium. These toxins are classified into four major groups: the toxin complexes (Tcs), the Photorhabdus insect related (Pir) proteins, the “makes caterpillars floppy” (Mcf) toxins and the Photorhabdus virulence cassettes (PVC); the mechanisms however of toxin secretion are not fully elucidated. Using bioinformatics analysis and comparison against the components of known secretion systems, multiple copies of components of all known secretion systems, except the ones composing a type IV secretion system, were identified throughout the entire genome of the bacterium. This indicates that Photorhabdus luminescens has all the necessary means for the secretion of virulence factors, thus it is capable of establishing a microbial infection. PMID:22069636

  10. Protein degradation by ubiquitin–proteasome system in formation and labilization of contextual conditioning memory

    PubMed Central

    Sol Fustiñana, María; de la Fuente, Verónica; Federman, Noel; Freudenthal, Ramiro

    2014-01-01

    The ubiquitin–proteasome system (UPS) of protein degradation has been evaluated in different forms of neural plasticity and memory. The role of UPS in such processes is controversial. Several results support the idea that the activation of this system in memory consolidation is necessary to overcome negative constrains for plasticity. In this case, the inhibition of the UPS during consolidation impairs memory. Similar results were reported for memory reconsolidation. However, in other cases, the inhibition of UPS had no effect on memory consolidation and reconsolidation but impedes the amnesic action of protein synthesis inhibition after retrieval. The last finding suggests a specific action of the UPS inhibitor on memory labilization. However, another interpretation is possible in terms of the synthesis/degradation balance of positive and negative elements in neural plasticity, as was found in the case of long-term potentiation. To evaluate these alternative interpretations, other reconsolidation-interfering drugs than translation inhibitors should be tested. Here we analyzed initially the UPS inhibitor effect in contextual conditioning in crabs. We found that UPS inhibition during consolidation impaired long-term memory. In contrast, UPS inhibition did not affect memory reconsolidation after contextual retrieval but, in fact, impeded memory labilization, blocking the action of drugs that does not affect directly the protein synthesis. To extend these finding to vertebrates, we performed similar experiments in contextual fear memory in mice. We found that the UPS inhibitor in hippocampus affected memory consolidation and blocked memory labilization after retrieval. These findings exclude alternative interpretations to the requirement of UPS in memory labilization and give evidence of this mechanism in both vertebrates and invertebrates. PMID:25135196

  11. Protein degradation by ubiquitin-proteasome system in formation and labilization of contextual conditioning memory.

    PubMed

    Sol Fustiñana, María; de la Fuente, Verónica; Federman, Noel; Freudenthal, Ramiro; Romano, Arturo

    2014-09-01

    The ubiquitin-proteasome system (UPS) of protein degradation has been evaluated in different forms of neural plasticity and memory. The role of UPS in such processes is controversial. Several results support the idea that the activation of this system in memory consolidation is necessary to overcome negative constrains for plasticity. In this case, the inhibition of the UPS during consolidation impairs memory. Similar results were reported for memory reconsolidation. However, in other cases, the inhibition of UPS had no effect on memory consolidation and reconsolidation but impedes the amnesic action of protein synthesis inhibition after retrieval. The last finding suggests a specific action of the UPS inhibitor on memory labilization. However, another interpretation is possible in terms of the synthesis/degradation balance of positive and negative elements in neural plasticity, as was found in the case of long-term potentiation. To evaluate these alternative interpretations, other reconsolidation-interfering drugs than translation inhibitors should be tested. Here we analyzed initially the UPS inhibitor effect in contextual conditioning in crabs. We found that UPS inhibition during consolidation impaired long-term memory. In contrast, UPS inhibition did not affect memory reconsolidation after contextual retrieval but, in fact, impeded memory labilization, blocking the action of drugs that does not affect directly the protein synthesis. To extend these finding to vertebrates, we performed similar experiments in contextual fear memory in mice. We found that the UPS inhibitor in hippocampus affected memory consolidation and blocked memory labilization after retrieval. These findings exclude alternative interpretations to the requirement of UPS in memory labilization and give evidence of this mechanism in both vertebrates and invertebrates. PMID:25135196

  12. Functional RelBE-Family Toxin-Antitoxin Pairs Affect Biofilm Maturation and Intestine Colonization in Vibrio cholerae

    PubMed Central

    Hay, Amanda J.; Zhong, Zengtao; Zhu, Jun; Kan, Biao

    2015-01-01

    Toxin–antitoxin (TA) systems are small genetic elements that typically encode a stable toxin and its labile antitoxin. These cognate pairs are abundant in prokaryotes and have been shown to regulate various cellular functions. Vibrio cholerae, a human pathogen that is the causative agent of cholera, harbors at least thirteen TA loci. While functional HigBA, ParDE have been shown to stabilize plasmids and Phd/Doc to mediate cell death in V. cholerae, the function of seven RelBE-family TA systems is not understood. In this study we investigated the function of the RelBE TA systems in V. cholerae physiology and found that six of the seven relBE loci encoded functional toxins in E. coli. Deletion analyses of each relBE locus indicate that RelBE systems are involved in biofilm formation and reactive oxygen species (ROS) resistance. Interestingly, all seven relBE loci are induced under the standard virulence induction conditions and two of the relBE mutants displayed a colonization defect, which was not due to an effect on virulence gene expression. Although further studies are needed to characterize the mechanism of action, our study reveals that RelBE systems are important for V. cholerae physiology. PMID:26275048

  13. Substrate lability and plant activity controls greenhouse gas release from Neotropical peatland

    NASA Astrophysics Data System (ADS)

    Sjogersten, Sofie; Hoyos, Jorge; Lomax, Barry; Turner, Ben; Wright, Emma

    2014-05-01

    Almost one third of global CO2 emissions resulting from land use change and substantial CH4 emissions originate from tropical peatlands. However, our understanding of the controls of CO2 and CH4 release from tropical peatlands are limited. The aim of this study was to investigate the role of peat lability and the activity of the vegetation on gas release using a combination of field and laboratory experiments. We demonstrated that peat lability constrained CH4 production to the surface peat under anaerobic conditions. The presence of plants shifted the C balance from a C source to a C sink with respect to CO2 while the activity of the root system strongly influenced CH4 emissions through its impact on soil O2 inputs. Both field and laboratory data suggest a coupling between the photosynthetic activity of the vegetation and the release of both CO2 and CH4 following the circadian rhythm of the dominant plant functional types. Forest clearance for agriculture resulted in elevated CH4 release, which we attribute in part to the cessation of root O2 inputs to the peat. We conclude that high emissions of CO2 and CH4 from forested tropical peatlands are likely driven by labile C inputs from the vegetation but that root O2 release may limit CH4 emissions.

  14. Life history lability underlies rapid climate niche evolution in the angiosperm clade Montiaceae.

    PubMed

    Matthew Ogburn, R; Edwards, Erika J

    2015-11-01

    Despite the recent focus on phylogenetic niche conservatism in macroevolutionary studies, many clades have diversified widely along multiple niche dimensions. The factors underlying lineage-specific niche lability are still not well understood. We examined morphological and climate niche evolution in Montiaceae (Caryophyllales), an ecologically variable plant lineage distributed primarily along the mountain chains of the western Americas. Montiaceae inhabit a broader range of temperatures than their relatives, with an increase in the evolutionary rate of temperature niche diversification at the node subtending this clade. Within Montiaceae, life history is highly labile and significantly correlated with temperature, with perennials consistently occurring in cooler environments. This elevated evolutionary lability facilitated repeated shifts between habitats as new environments were created by post-Eocene orogenic events and aridification in the western Americas. The shifts between annual and perennial forms are elaborations of an underlying rosette body plan in most cases, and may involve simple alterations in biomass allocation. Montiaceae stand as another clear counterexample to phylogenetic niche conservatism, and demonstrate a mechanism by which pronounced ecological shifts may occur frequently and rapidly among closely related species. PMID:26143714

  15. Affect Intensity and Lability: The Role of Posttraumatic Stress Disorder Symptoms in Borderline Personality Disorder

    PubMed Central

    Marshall-Berenz, Erin C.; Morrison, Jay A.; Schumacher, Julie A.; Coffey, Scott F.

    2011-01-01

    Background Emotion dysregulation is likely a core psychological process underlying the heterogeneity of presentations in borderline personality disorder (BPD) and is associated with BPD symptom severity. Emotion dysregulation has also been independently associated with posttraumatic stress disorder (PTSD), a disorder that has been found to co-occur with BPD in 30.2% of cases in a nationally representative sample. However, relatively little is known about the specific relationships between emotion dysregulation and PTSD among those diagnosed with BPD. The purpose of the current study was to evaluate relations between PTSD symptom severity and negative affect intensity and affective lability among individuals with BPD. Method Participants were 67 individuals diagnosed with BPD (79% women; Mage = 38, SD = 10), who reported one or more DSM-IV PTSD Criterion A events. Results Hierarchical multiple regression analyses indicated that when examined concurrently with BPD symptom severity, PTSD symptom severity, but not BPD symptom severity, was related to negative affect intensity and affective lability. Reexperiencing symptoms uniquely predicted affective lability, and hyperarousal symptoms uniquely predicted negative affect intensity, lending additional support to emerging literature linking reexperiencing and hyperarousal symptoms with emotion dysregulation. Conclusions PTSD symptom severity among individuals with a BPD diagnosis is related to elevations in emotion dysregulation. It is important to evaluate whether early treatment of PTSD symptoms provided concurrently with BPD treatment leads to enhanced improvements in emotion regulation among individuals with co-occurring PTSD and BPD. PMID:21538723

  16. Labile soil carbon inputs mediate the soil microbial community composition and plant residue decomposition rates

    SciTech Connect

    De Graaff, Marie-Anne; Classen, Aimee T; Castro Gonzalez, Hector F; Schadt, Christopher Warren

    2010-01-01

    Root carbon (C) inputs may regulate decomposition rates in soil, and in this study we ask: how do labile C inputs regulate decomposition of plant residues, and soil microbial communities? In a 14 d laboratory incubation, we added C compounds often found in root exudates in seven different concentrations (0, 0.7, 1.4, 3.6, 7.2, 14.4 and 21.7 mg C g{sup -1} soil) to soils amended with and without {sup 13}C-labeled plant residue. We measured CO{sub 2} respiration and shifts in relative fungal and bacterial rRNA gene copy numbers using quantitative polymerase chain reaction (qPCR). Increased labile C input enhanced total C respiration, but only addition of C at low concentrations (0.7 mg C g{sup -1}) stimulated plant residue decomposition (+2%). Intermediate concentrations (1.4, 3.6 mg C g{sup -1}) had no impact on plant residue decomposition, while greater concentrations of C (> 7.2 mg C g{sup -1}) reduced decomposition (-50%). Concurrently, high exudate concentrations (> 3.6 mg C g{sup -1}) increased fungal and bacterial gene copy numbers, whereas low exudate concentrations (< 3.6 mg C g{sup -1}) increased metabolic activity rather than gene copy numbers. These results underscore that labile soil C inputs can regulate decomposition of more recalcitrant soil C by controlling the activity and relative abundance of fungi and bacteria.

  17. Bacillithiol is a major buffer of the labile zinc pool in Bacillus subtilis

    PubMed Central

    Ma, Zhen; Chandrangsu, Pete; Helmann, Tyler C.; Romsang, Adisak; Gaballa, Ahmed; Helmann, John D.

    2014-01-01

    Intracellular zinc levels are tightly regulated since zinc is an essential cofactor for numerous enzymes, yet can be toxic when present in excess. The majority of intracellular zinc is tightly associated with proteins and is incorporated during synthesis from a poorly defined pool of kinetically labile zinc. In Bacillus subtilis, this labile pool is sensed by equilibration with the metalloregulator Zur, as an indication of zinc sufficiency, and by CzrA, as an indication of zinc excess. Here, we demonstrate that the low molecular weight thiol bacillithiol (BSH) serves as a major buffer of the labile zinc pool. Upon shift to conditions of zinc excess, cells transiently accumulate zinc in a low molecular weight pool, and this accumulation is largely dependent on BSH. Cells lacking BSH are more sensitive to zinc stress, and they induce zinc efflux at lower external zinc concentrations. Thiol reactive agents such as diamide and cadmium induce zinc efflux by interfering with the Zn-buffering function of BSH. Our data provide new insights into intracellular zinc buffering and may have broad relevance given the presence of BSH in pathogens and the proposed role of zinc sequestration in innate immunity. PMID:25213752

  18. Assessing the Selectivity of Extractant Solutions for Recovering Labile Arsenic Associated with Iron (Hydr)oxides and Sulfides in Sediments

    EPA Science Inventory

    Sequential extractions can provide analytical constraints on the identification of mineral phases that control arsenic speciation in sediments. Model solids were used in this study to evaluate different solutions designed to extract arsenic from relatively labile solid phases. ...

  19. Effect of purified staphylococcal alpha toxin on active sodium transport and aerobic respiration in the isolated toad bladder

    PubMed Central

    Rahal, James J.; Plaut, Martin E.; Weinstein, Louis

    1968-01-01

    Purified staphylococcal alpha toxin was found to inhibit the active transport of sodium across the isolated toad bladder when applied to the serosal but not to mucosal surface. Heating or the addition of specific antitoxin abolished this effect. Low temperatures reduced this activity significantly. Application of vasopressin to the bladder serosa shortly after toxin resulted in only weak and transient stimulation of sodium transport; once maximal toxin activity had been established, exposure to the hormone was without effect. Transport in bladders previously stimulated by vasopressin was rapidly inhibited by alpha toxin. Concentrations that suppressed active sodium transport completely within 30-45 min produced a significant increase in oxygen consumption by minced bladder tissue within the same period; antitoxin neutralized this activity. 2,4-dinitrophenol also inhibited sodium transport and stimulated oxygen consumption by the toad bladder. The addition of 2,4 dinitrophenol to bladder tissue in which respiration was maximally stimulated by alpha toxin resulted in a further increase in respiratory rate. The addition of toxin to bladder tissue after its exposure to a concentration of 2,4 dinitrophenol known to uncouple oxidative phosphorylation produced a significant stabilization but no increment in respiratory rate. The data are consistent with the previously suggested action of staphylococcal alpha toxin on cell membranes and suggest that energy-dependent transport processes are inhibited. The stimulation of oxygen consumption may be due to an additional effect on oxidative phosphorylation. PMID:5658591

  20. Molecular insights into the microbial formation of marine dissolved organic matter: recalcitrant or labile?

    NASA Astrophysics Data System (ADS)

    Koch, B. P.; Kattner, G.; Witt, M.; Passow, U.

    2014-08-01

    The degradation of marine dissolved organic matter (DOM) is an important control variable in the global carbon cycle. For our understanding of the kinetics of organic matter cycling in the ocean, it is crucial to achieve a mechanistic and molecular understanding of its transformation processes. A long-term microbial experiment was performed to follow the production of non-labile DOM by marine bacteria. Two different glucose concentrations and dissolved algal exudates were used as substrates. We monitored the bacterial abundance, concentrations of dissolved and particulate organic carbon (DOC, POC), nutrients, amino acids and transparent exopolymer particles (TEP) for 2 years. The molecular characterization of extracted DOM was performed by ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) after 70 days and after ∼2 years of incubation. Although glucose quickly degraded, a non-labile DOC background (5-9% of the initial DOC) was generated in the glucose incubations. Only 20% of the organic carbon from the algal exudate degraded within the 2 years of incubation. The degradation rates for the non-labile DOC background in the different treatments varied between 1 and 11 ?mol DOC L-1 year-1. Transparent exopolymer particles, which are released by microorganisms, were produced during glucose degradation but decreased back to half of the maximum concentration within less than 3 weeks (degradation rate: 25 ?g xanthan gum equivalents L-1 d-1) and were below detection in all treatments after 2 years. Additional glucose was added after 2 years to test whether labile substrate can promote the degradation of background DOC (co-metabolism; priming effect). A priming effect was not observed but the glucose addition led to a slight increase of background DOC. The molecular analysis demonstrated that DOM generated during glucose degradation differed appreciably from DOM transformed during the degradation of the algal exudates. Our results led to several conclusions: (i) based on our experimental setup, higher substrate concentration resulted in a higher concentration of non-labile DOC; (ii) TEP, generated by bacteria, degrade rapidly, thus limiting their potential contribution to carbon sequestration; (iii) the molecular signatures of DOM derived from algal exudates and glucose after 70 days of incubation differed strongly from refractory DOM. After 2 years, however, the molecular patterns of DOM in glucose incubations were more similar to deep ocean DOM whereas the degraded exudate was still different.

  1. Clostridium difficile: its disease and toxins.

    PubMed Central

    Lyerly, D M; Krivan, H C; Wilkins, T D

    1988-01-01

    Clostridium difficile is the etiologic agent of pseudomembranous colitis, a severe, sometimes fatal disease that occurs in adults undergoing antimicrobial therapy. The disease, ironically, has been most effectively treated with antibiotics, although some of the newer methods of treatment such as the replacement of the bowel flora may prove more beneficial for patients who continue to relapse with pseudomembranous colitis. The organism produces two potent exotoxins designated toxin A and toxin B. Toxin A is an enterotoxin believed to be responsible for the diarrhea and mucosal tissue damage which occur during the disease. Toxin B is an extremely potent cytotoxin, but its role in the disease has not been as well studied. There appears to be a cascade of events which result in the expression of the activity of these toxins, and these events, ranging from the recognition of a trisaccharide receptor by toxin A to the synergistic action of the toxins and their possible dissemination in the body, are discussed in this review. The advantages and disadvantages of the various assays, including tissue culture assay, enzyme immunoassay, and latex agglutination, currently used in the clinical diagnosis of the disease also are discussed. PMID:3144429

  2. Fungi and fungal toxins as weapons.

    PubMed

    Paterson, R Russell M

    2006-09-01

    Recent aggressive attacks on innocent citizens have resulted in governments increasing security. However, there is a good case for prevention rather than reaction. Bioweapons, mycotoxins, fungal biocontrol agents (FBCA), and even pharmaceuticals contain, or are, toxins and need to be considered in the context of the new paradigm. Is it desirable to discuss such issues? None of the fungi are (a) as toxic as botulinum toxin from Clostridium botulinum, and (b) as dangerous as nuclear weapons. One toxin may be defined as a pharmaceutical and vice versa simply by a small change in concentration or a moiety. Mycotoxins are defined as naturally occurring toxic compounds obtained from fungi. They are the biggest chronic health risk when incorporated into the diet. The current list of fungal toxins as biochemical weapons is small, although awareness is growing of the threats they may pose. T-2 toxin is perhaps the biggest concern. A clear distinction is required between the biological (fungus) and chemical (toxin) aspects of the issue. There is an obvious requirement to be able to trace these fungi and compounds in the environment and to know when concentrations are abnormal. Many FBCA, produce toxins. This paper indicates how to treat mycotoxicosis and decontaminate mycotoxins. There is considerable confusion and inconsistency surrounding this topic which requires assessment in an impartial and scientific manner. PMID:16908123

  3. Cyanobacterial toxins: risk management for health protection

    SciTech Connect

    Codd, Geoffrey A.; Morrison, Louise F.; Metcalf, James S

    2005-03-15

    This paper reviews the occurrence and properties of cyanobacterial toxins, with reference to the recognition and management of the human health risks which they may present. Mass populations of toxin-producing cyanobacteria in natural and controlled waterbodies include blooms and scums of planktonic species, and mats and biofilms of benthic species. Toxic cyanobacterial populations have been reported in freshwaters in over 45 countries, and in numerous brackish, coastal, and marine environments. The principal toxigenic genera are listed. Known sources of the families of cyanobacterial toxins (hepato-, neuro-, and cytotoxins, irritants, and gastrointestinal toxins) are briefly discussed. Key procedures in the risk management of cyanobacterial toxins and cells are reviewed, including derivations (where sufficient data are available) of tolerable daily intakes (TDIs) and guideline values (GVs) with reference to the toxins in drinking water, and guideline levels for toxigenic cyanobacteria in bathing waters. Uncertainties and some gaps in knowledge are also discussed, including the importance of exposure media (animal and plant foods), in addition to potable and recreational waters. Finally, we present an outline of steps to develop and implement risk management strategies for cyanobacterial cells and toxins in waterbodies, with recent applications and the integration of Hazard Assessment Critical Control Point (HACCP) principles.

  4. MATERIALS FOR BINDING MYCOTOXINS AND THEIR USE IN TOXIN DETECTION

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Materials capable of binding mycotoxins find numerous uses. These include components of test kits for toxin detection, as agents for isolation of toxins from foods or toxin purification, and as binding agents to prevent toxin uptake and thereby protect domestic animals. There is no shortage of mat...

  5. Using Modified Bacterial Toxins To Deliver Vaccine Antigens

    E-print Network

    Starnbach, Michael

    Using Modified Bacterial Toxins To Deliver Vaccine Antigens Researchers are using toxins to deliver have taken a cue from the microbial world, harnessing the inherent ability of bacterial toxins to enter mammalian cells and using modified versions of these toxins as vac- cines. Presentation of MHC Class I

  6. Gangliosides as Receptors for Biological Toxins: Development of Sensitive Fluoroimmunoassays

    E-print Network

    Singh, Anup

    Gangliosides as Receptors for Biological Toxins: Development of Sensitive Fluoroimmunoassays Using of bacterial toxins and viruses whose sensitive detection is of interest in clinical medicine as well by bacterial toxins and can be used as sensitive probes for detecting these toxins. We discuss detection

  7. The Stable and Radio- Carbon Isotopic Content of Labile and Refractory Carbon in Atmospheric Particulate Matter

    NASA Astrophysics Data System (ADS)

    McNichol, A. P.; Rosenheim, B. E.; Gerlach, D. S.; Hayes, J. M.

    2006-12-01

    Studies of the isotopic content of atmospheric particulate matter are hampered by difficulties in chemically defining the pools of carbon and analytically isolating the different pools. We are conducting studies on reference materials and atmospheric aerosol samples to develop a method to measure stable and radio- carbon isotopes on the labile and refractory carbon. We are using a flow-through combustion system that allows us to combust, collect and measure the isotopic content of the gases produced at all stages of heating/oxidizing. We compare our results to those measured using a chemothermal oxidation method (CTO) (Gustafsson et al., 2001). In this method, refractory carbon is defined as the material remaining after pre- combusting a sample at 375°C in the presence of oxygen for 24 hours. The reference materials are diesel soot, apple leaves and a hybrid of the two (DiesApple), all from NIST. These provide carbon with two well-defined fractions -- the soot provides refractory carbon that is radiocarbon dead and the apple leaves provide organic carbon that is radiocarbon modern. Radiocarbon results from DiesApple indicate that the "refractory" carbon defined by the CTO method is actually a mixture of old and modern carbon that contains over 25% modern carbon. This suggests that charred material formed from the apples leaves during the pre-combustion step is contributing to the fraction we identify as refractory carbon. We are studying this by analyzing the individual materials and the mixture using our flow-through system. First results with this system indicate that the refractory fraction trapped from the DiesApple contains much less modern carbon than the CTO method, less than 7%. We will present detailed concentration and isotopic results of the generation of carbon dioxide during programmed combustion of each of the reference materials. We studied the radiocarbon content of both the total carbon (TC) and refractory carbon in the fine particulate matter (PM2.5) collected on quartz fiber filters as part of the Southeastern Aerosol Research and Characterization (SEARCH) program. The five samples were collected at two sites (Birmingham, AL and Atlanta, GA) with very different sources of atmospheric particulate matter. In all instances, the refractory carbon contained significantly less radiocarbon than the TC suggesting, not unexpectedly, a source of particulate carbon from the combustion of fossil material. We will present results from the analysis of the same filters in the flow-through system. The implication of our results for the use of radiocarbon in the quantitative apportionment of atmospheric particulate matter sources will be discussed. Gustafsson O., T. Bucheli, Z. Kukulska, M. Andersson, C. Largeau, J-N. Rouzaud, C. Reddy and T. Eglinton (2001) Evaluation of a protocol for the quantification of black carbon in sediments. GBD 15, 881-890.

  8. Botulinum toxin therapy of laryngeal muscle hyperactivity syndromes: comparing different botulinum toxin preparations.

    PubMed

    Truong, D D; Bhidayasiri, R

    2006-02-01

    Spasmodic dysphonia (SD) is a focal dystonia characterized by a strained, strangled voice. Botulinum toxin is a symptomatic treatment for SD and has become the mainstay of therapy over the last two decades. In this manuscript, we briefly review different laryngeal muscle hyperactivity syndromes, their injection techniques and toxins currently available. Adductor SD is the most common indication for botulinum toxin treatment in the larynx. All studies report similar results with regard to improvement, patient satisfaction and side effects. We describe different injection techniques to treat this disorder such as the percutaneous, transoral, transnasal, point-touch techniques. In abductor SD, a subtype of SD, the treatment is aimed at the posterior cricoarytenoid muscle. Other applications of botulinum toxin in the larynx include spasmodic laryngeal dyspnea and voice tremors. We also review injection techniques, the different toxin types used, and toxin doses. PMID:16417596

  9. Investigating the role of solanapyrone toxins in Ascochyta blight using toxin-deficient mutants of Asochyta rabiei

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ascochyta rabiei, the causal agent of Ascochyta blight of chickpea, produces solanapyrone toxins (solanapyrone A, B and C). However, very little is known about the genetics of toxin production and the role of the toxins in pathogenesis. Generating mutants deficient in the toxin biosynthesis would p...

  10. CELLBIOLOGY -prom.Y-toxin(k1ORF4)

    E-print Network

    #12;CELLBIOLOGY kDa 1 7 0 1 3 0 9 0 5 2 4 9 3 0 1 4 -prom.Y-toxin(k1ORF4) Glucose Galactose Y-toxin]. lsolofionof Toxin-Resistont (toxRltulonls Intriguingly,toxicity resides solelywithin the y toxin sub- unit the moturey generesultsin biolog- icolly octivey toxin whereos exogenouslyoppliedy is not oble to inhibit cell

  11. Inhibition of Shiga toxin 2 (Stx2) in apple juices and its resistance to pasteurization.

    PubMed

    Rasooly, Reuven; Do, Paula M; Levin, Carol E; Friedman, Mendel

    2010-06-01

    In the present study, we evaluated Shiga toxin (Stx2) activity in apple juices by measuring a decrease in dehydrogenase activity of Vero cells with the microculture tetrazolium (MTT) assay. Freshly prepared juice from Red Delicious apples and Golden Delicious apples inhibited the biological activity of the bacterial toxin Stx2 produced by E. coli O157:H7 strains. Studies with immunomagnetic beads bearing specific antibodies against the toxin revealed that Stx2 activity was restored when removed from the apple juice. SDS gel electrophoresis revealed no difference (P < 0.05) in the densities or molecular weights between Stx2 in either PBS or apple juices. These results suggest that Stx2 may be reversibly bound to small molecular weight constituents in the juice. The Stx2 toxin was not inactivated on exposure to heat programs (63 degrees C for 30 min, 72 degrees C for 15 s, 89 degrees C for 1 s) commonly used to pasteurize apple juice, but lost all activity when exposed to 100 degrees C for 5 min. The results suggest that pasteurization of apple juice used to inactivate E. coli O157:H7 has no effect on Stx2, and that food-compatible and safe antitoxin compounds can be used to inhibit the biological activity of the Shiga toxin. PMID:20629887

  12. Nanoanalysis of the arthropod neuro-toxins

    PubMed Central

    Nakajima, Terumi

    2006-01-01

    Many kinds of venomous principles modulate physiological responses of mammalian signal transduction systems, on which they act selectively as enhancers, inhibitors or some other kind of effectors. These toxins become useful tools for physiological research. We have employed and characterized paralyzing toxins from the venom of spiders, insects and scorpions with a limited supply. We have developed rapid and sensitive mass spectrometric technology and applied for the identification of these toxins. Venom profiles are screened by MALDI-TOF fingerprinting analysis prior to purification of venomous components, then marked target toxins of small molecular mass (1000–5000) are characterized directly by means of mass spectrometric techniques such as Frit-FAB MS/MS, CID/PSD-TOF MS, Capil.-HPLC/Q-TOF MS/MS etc. PMID:25792792

  13. INVESTIGATOIN OF CYANOBACTERIA TOXINS IN WATER

    EPA Science Inventory

    Introduction:

    Approximately 80 alkaloid and cyclic peptide toxins produced by various freshwater and marine cyanobacteria (blue-green algae) have been identified and their structures determined. The U. S. Environmental Protection Agency has identified two neurotoxin alkalo...

  14. Dermatitis from purified sea algae toxin (debromoaplysiatoxin).

    PubMed

    Solomon, A E; Stoughton, R B

    1978-09-01

    Cutaneous inflammation was induced by debromoaplysiatoxin, a purified toxin extracted from Lyngbya majuscula Gomont. This alga causes a seaweed dermatitis that occurs in persons who have swum off the coast of Oahu in Hawaii. By topical application, the toxin was found to produce an irritant pustular folliculitis in humans and to cause a severe cutaneous inflammatory reaction in the rabbit and in hairless mice. PMID:686747

  15. The Chromosomal mazEF Locus of Streptococcus mutans Encodes a Functional Type II Toxin-Antitoxin Addiction System? †

    PubMed Central

    Syed, Mohammad Adnan; Koyanagi, Stephanie; Sharma, Eesha; Jobin, Marie-Claude; Yakunin, Alexander F.; Lévesque, Céline M.

    2011-01-01

    Type II chromosomal toxin-antitoxin (TA) modules consist of a pair of genes that encode two components: a stable toxin and a labile antitoxin interfering with the lethal action of the toxin through protein complex formation. Bioinformatic analysis of Streptococcus mutans UA159 genome identified a pair of linked genes encoding a MazEF-like TA. Our results show that S. mutans mazEF genes form a bicistronic operon that is cotranscribed from a ?70-like promoter. Overproduction of S. mutans MazF toxin had a toxic effect on S. mutans which can be neutralized by coexpression of its cognate antitoxin, S. mutans MazE. Although mazF expression inhibited cell growth, no cell lysis of S. mutans cultures was observed under the conditions tested. The MazEF TA is also functional in E. coli, where S. mutans MazF did not kill the cells but rather caused reversible cell growth arrest. Recombinant S. mutans MazE and MazF proteins were purified and were shown to interact with each other in vivo, confirming the nature of this TA as a type II addiction system. Our data indicate that MazF is a toxic nuclease arresting cell growth through the mechanism of RNA cleavage and that MazE inhibits the RNase activity of MazF by forming a complex. Our results suggest that the MazEF TA module might represent a cell growth modulator facilitating the persistence of S. mutans under the harsh conditions of the oral cavity. PMID:21183668

  16. DOM composition and lability during the Arctic spring freshet on the River Kolyma, Northeast Siberia

    NASA Astrophysics Data System (ADS)

    Mann, P. J.; Davydova, A. I.; Zimov, N.; Bulygina, E. B.; Davydov, S.; Russell-Roy, L.; Zimov, S. A.; Holmes, R. M.

    2010-12-01

    The concentration, composition, age and lability of dissolved organic matter (DOM) exported by Arctic Rivers is known to vary significantly across the hydrograph, affecting the biogeochemical cycling of carbon within high latitude systems. Despite the fact that the majority of the dissolved organic carbon (DOC) flux occurs during the spring freshet, surprisingly little is known about concurrent changes in DOM composition and how this may affect DOC removal processes. In this study, we collected a range of samples throughout the 2010 spring freshet in the Kolyma River and its nearby tributaries, Northeast Siberia. DOM quantity and quality was measured using absorbance and fluorescence spectrophotometry alongside bulk carbon (DOC) and nitrogen (TDN) measurements. Parallel factor analysis (PARAFAC) was employed to decompose fluorescence excitation-emission matrices (EEMs) into distinct fractions. In conjunction with DOM characterization, we investigated the photochemical and bacterial lability of the DOC pool using natural incubation experiments. Kolyma river DOC concentrations ranged from 0.6 mgL-1 under-ice to 14.2 mgL-1 at the peak of the spring flush. Up to 20% DOC loss was observed during 28 d-1 bacterial incubations and 13% loss during 4 d-1 natural sunlight incubations respectively. These percentage losses were greatest in association with maximum riverine DOC concentrations. Furthermore, prior sunlight exposure increased DOM availability for biological remineralization suggesting synergistic pathways in DOC degradation. Absorbance spectral slopes, SUVA254 and PARAFAC modeling results confirm significant changes in DOM composition during the flush and provide useful proxies for DOC lability. With predicted future changes in land-to-ocean carbon fluxes, understanding the link between DOM compositional changes and DOC photo and biolability has clear implications for the overall fate and export of carbon in high-latitude systems.

  17. Peat carbon stocks and potential microbial lability of boreal peatlands with varying permafrost histories

    NASA Astrophysics Data System (ADS)

    Olefeldt, D.; Pelletier, N.; Talbot, J.; Blodau, C.; Turetsky, M. R.

    2014-12-01

    Large stores of C in the form of peat are stored in permafrost, particularly in the boreal discontinuous permafrost zone. Ongoing climate change is causing widespread permafrost thaw in boreal peatlands, a trend which is expected to continue this century and thus make large stores of soil C available for microbial processes and mineralization. Permafrost thaw in boreal peatlands is often associated with an ecosystem shift from dry peat plateau to wet bog surfaces, and the net C balance following thaw is determined by the balance between the mineralization of plateau peat and the new accumulation of bog peat on top. In this study we collected soil cores (~3 m deep) from one peat plateaus and four bogs that differed in time since thaw (approximately 10, 50 and 500 years since thaw). In order to assess the potential microbial lability, we incubated 25 soil samples from each core under aerobic conditions at 17.5 deg C. Mineralization rates were 1-2 order of magnitude higher near the surface than at depth, but near surface samples also had high variability among cores. Variability in peat microbial lability near the surface was related to thaw history and to differences in characteristics between plateau and bog peat. Mineralization rates of peat samples from below 1 m depth and down to the interface with mineral soil at 3 m were consistently low and had no difference among cores. Mineralization rates during the first 3 months of incubation for deep plateau peat samples were equivalent to 1% soil C losses per year. Relatively low microbial lability of deep peat in combination with high rates of new peat accumulation during the initial stages of bog development suggests that there is net C accumulation immediately following thaw but that the sink strength weakens or reverses during later stages when new accumulation rates diminish.

  18. Tetra- versus Pentavalent Inhibitors of Cholera Toxin**

    PubMed Central

    Fu, Ou; Pukin, Aliaksei V; van?Ufford, H C Quarles; Branson, Thomas R; Thies-Weesie, Dominique M E; Turnbull, W Bruce; Visser, Gerben M; Pieters, Roland J

    2015-01-01

    The five B-subunits (CTB5) of the Vibrio cholerae (cholera) toxin can bind to the intestinal cell surface so the entire AB5 toxin can enter the cell. Simultaneous binding can occur on more than one of the monosialotetrahexosylganglioside (GM1) units present on the cell surface. Such simultaneous binding arising from the toxins multivalency is believed to enhance its affinity. Thus, blocking the initial attachment of the toxin to the cell surface using inhibitors with GM1 subunits has the potential to stop the disease. Previously we showed that tetravalent GM1 molecules were sub-nanomolar inhibitors of CTB5. In this study, we synthesized a pentavalent version and compared the binding and potency of penta- and tetravalent cholera toxin inhibitors, based on the same scaffold, for the first time. The pentavalent geometry did not yield major benefits over the tetravalent species, but it was still a strong inhibitor, and no major steric clashes occurred when binding the toxin. Thus, systems which can adopt more geometries, such as those described here, can be equally potent, and this may possibly be due to their ability to form higher-order structures or simply due to more statistical options for binding. PMID:26478842

  19. Inhibition of maize histone deacetylases by HC toxin, the host-selective toxin of Cochliobolus carbonum.

    PubMed Central

    Brosch, G; Ransom, R; Lechner, T; Walton, J D; Loidl, P

    1995-01-01

    HC toxin, the host-selective toxin of the maize pathogen Cochliobolus carbonum, inhibited maize histone deacetylase (HD) at 2 microM. Chlamydocin, a related cyclic tetrapeptide, also inhibited HD activity. The toxins did not affect histone acetyltransferases. After partial purification of histone deacetylases HD1-A, HD1-B, and HD2 from germinating maize embryos, we demonstrated that the different enzymes were similarly inhibited by the toxins. Inhibitory activities were reversibly eliminated by treating toxins with 2-mercaptoethanol, presumably by modifying the carbonyl group of the epoxide-containing amino acid Aeo (2-amino-9,10-epoxy-8-oxodecanoic acid). Kinetic studies revealed that inhibition of HD was of the uncompetitive type and reversible. HC toxin, in which the epoxide group had been hydrolyzed, completely lost its inhibitory activity; when the carbonyl group of Aeo had been reduced to the corresponding alcohol, the modified toxin was less active than native toxin. In vivo treatment of embryos with HC toxin caused the accumulation of highly acetylated histone H4 subspecies and elevated acetate incorporation into H4 in susceptible-genotype embryos but not in the resistant genotype. HDs from chicken and the myxomycete Physarum polycephalum were also inhibited, indicating that the host selectivity of HC toxin is not determined by its inhibitory effect on HD. Consistent with these results, we propose a model in which HC toxin promotes the establishment of pathogenic compatibility between C. carbonum and maize by interfering with reversible histone acetylation, which is implicated in the control of fundamental cellular processes, such as chromatin structure, cell cycle progression, and gene expression. PMID:8535144

  20. Labile Compounds in Plant Litter Reduce the Sensitivity of Decomposition to Warming and Altered Precipitation

    NASA Astrophysics Data System (ADS)

    Suseela, V.; Tharayil, N.; Xing, B.; Dukes, J. S.

    2013-12-01

    Together, climate and litter quality strongly regulate decomposition rates. While these two factors and their interaction have been studied across species in continent-scale experiments, few researchers have studied how labile and recalcitrant compounds interact to influence decomposition, or the climate sensitivity of decomposition, within a litter type. Over a period of three years, we studied the effects climate change on mass loss and compound-specific decomposition using two litter types that differed in the relative proportions of labile and recalcitrant compounds, but that had heteropolymers with similar molecular structure. We examined how warming and altered precipitation affected the decomposition of two types of Polygonum cuspidatum (Japanese knotweed) litter (stem litter that was either newly senesced or one year old), at the Boston-Area Climate Experiment (BACE), in Massachusetts, USA. We placed litter bags in an old-field ecosystem exposed to four levels of warming (up to 4oC) and three levels of precipitation (ambient, drought (-50%) and wet (+50%) treatments. The compound-specific degradation of litter was assessed using Diffuse Reflectance Infrared Fourier Transform Spectroscopy and 13C Nuclear Magnetic Resonance Spectroscopy. Climate treatments immediately affected mass loss of the more recalcitrant litter, but affected the more labile litter only after two years. After three years, although both litter types had lost similar amounts of mass, warming (~4oC) and supplemental precipitation (150% of ambient) together accelerated degradation of alkyl-carbon and lignin only in the more recalcitrant litter, highlighting the role of initial litter quality in determining whether the chemistry of litter residues converges or diverges under different climates. The results from this study indicate that the effect of climate on litter decomposition depends on the quality of litter; litter with a greater initial proportion of labile compounds was less sensitive to warming and altered precipitation. The significant effects of precipitation on mass loss and chemical composition, even in the late stages of litter decomposition, reveal the potential of climate to alter the amount and quality of carbon in plant litter available for sequestration. These results emphasize that litter chemical composition has an overriding effect on the climate sensitivity of decomposition; thus, litter quality may regulate litter-derived carbon sequestration under future climates.

  1. Enantiomeric Excesses of Acid Labile Amino Acid Precursors of the Murchison Meteorite

    NASA Technical Reports Server (NTRS)

    Pizzarello, Sandra

    1998-01-01

    Amino acids present in carbonaceous chondrite are extracted in water in part as free compounds and in approximately equal part as acid labile precursors. On the assumption that they would be free of contamination, the precursors of two Murchison amino acids that have terrestrial occurrence, alanine and glutamic acid, have been targeted for analysis of their enantiomeric ratios. Pyroglutamic acid, the precursor of glutamic acid, was found with an L-enantiomeric excess comparable to that of the free acid, while alanine's precursor, N-acetyl alanine, appears approximately racemic. Also alpha-imino propioacetic acid, a proposed end product of alanine synthesis in the meteorite, was analyzed and found racemic.

  2. Constraints on Transport and Emplacement Mechanisms of Labile Fractions in Lunar Cold Traps

    NASA Technical Reports Server (NTRS)

    Rickman, D.; Gertsch, L.

    2014-01-01

    Sustaining the scientific exploration of the Solar System will require a significant proportion of the necessary fuels and propellants, as well as other bulk commodities, to be produced from local raw materials [1]. The viability of mineral production depends on the ability to locate and characterize mineable deposits of the necessary feedstocks. This requires, among other things, a workable understanding of the mechanisms by which such deposits form, which is the subject of Economic Geology. Multiple deposition scenarios are possible for labile materials on the Moon. This paper suggests labile fractions moved diffusely through space; deposits may grow richer with depth until low porosity rock; lateral transport is likely to have occurred with the regolith, at least for short distances; crystalline ice may not exist; the constituent phases could be extremely complex. At present we can constrain the sources only mildly; once on the Moon, the transport mechanisms inherently mix and therefore obscure the origins. However, the importance of expanding our understanding of ore-forming processes on the Moon behooves us to make the attempt. Thus begins a time of new inquiry for Economic Geology.

  3. Rhizosphere Environment and Labile Phosphorus Release from Organic Waste-Amended Soils.

    NASA Astrophysics Data System (ADS)

    Dao, Thanh H.

    2015-04-01

    Crop residues and biofertilizers are primary sources of nutrients for organic crop production. However, soils treated with large amounts of nutrient-enriched manure have elevated phosphorus (P) levels in regions of intensive animal agriculture. Surpluses occurred in these amended soils, resulting in large pools of exchangeable inorganic P (Pi) and enzyme-labile organic P (Po) that averaging 30.9 and 68.2 mg kg-1, respectively. Organic acids produced during crop residue decomposition can promote the complexation of counter-ions and decouple and release unbound Pi from metal and alkali metal phosphates. Animal manure and cover crop residues also contain large amounts of soluble organic matter, and likely generate similar ligands. However, a high degree of heterogeneity in P spatial distribution in such amended fields, arising from variances in substrate physical forms ranging from slurries to dried solids, composition, and diverse application methods and equipment. Distinct clusters of Pi and Po were observed, where accumulation of the latter forms was associated with high soil microbial biomass C and reduced phosphomonoesterases' activity. Accurate estimates of plant requirements and lability of soil P pools, and real-time plant and soil P sensing systems are critical considerations to optimally manage manure-derived nutrients in crop production systems. An in situ X-ray fluorescence-based approach to sensing canopy and soil XRFS-P was developed to improve the yield-soil P relationship for optimal nutrient recommendations in addition to allowing in-the-field verification of foliar P status.

  4. Lack of correlation between non-labile iron parameters, total carbonyl and malondialdehyde in major thalassemia

    PubMed Central

    Al-Hakeim, Hussein Kadhem; Auda, Furqan Muein; Ali, Basim Muhammed

    2014-01-01

    Thalassemia patients are at high risk of iron-induced toxicity and oxidative stress consequences. The present cross-sectional study is conducted to determine whether or not lipid peroxidation or protein oxidation is correlated with iron parameters in patients with thalassemia major. To prove this hypothesis, malondialdehyde and total carbonyl were correlated with the degree of excess iron concentration in the patients. A total of 118 Arabic Iraqi patients and 30 healthy children were participated in the present study. Results showed a significant increase (p<0.05) in serum total carbonyls, malondialdehyde and the iron indices of patients as compared with the control group. Total iron binding capacity and transferrin concentrations decreased significantly (p<0.05) in patients with thalassemia compared with the control group. The results also showed a lack of a significant correlation between each serum malondialdehyde and total carbonyl with each component of iron status. In conclusion, total carbonyls and malondialdehyde were increased in thalassemia patients indicating the vulnerability of these patients to tissue injury caused by oxidative stress. The formation of total carbonyl and malondialdehyde are independent of excess non-labile iron concentration, indicating that different mechanisms are involved in injury caused by the labile iron and in the formation of oxidation end products. PMID:25411527

  5. Localization of alkali-labile sites in donkey (Equus asinus) and stallion (Equus caballus) spermatozoa.

    PubMed

    Cortés-Gutiérrez, Elva I; Dávila-Rodríguez, Martha I; López-Fernández, Carmen; Fernández, José Luis; Crespo, Francisco; Gosálvez, Jaime

    2014-01-15

    The presence of constitutive alkali-labile sites (ALS) has been investigated using a protocol of DNA breakage detection-fluorescence in situ hybridization and comet assay in spermatozoa of donkey (Equus asinus) and stallion (Equus caballus). These results were compared with those obtained using a similar experimental approach using somatic cells. The relative abundance of ALS was of the order of four times more in spermatozoa than in somatic cells. Alkali-labile sites showed a tendency to cluster localized at the equatorial-distal regions of the sperm. The amount of hybridized signal in the ALS in the sperm of donkey (Equus asinus) was 1.3 times greater than in stallion (Equus caballus), and the length of the comet tail obtained in donkey sperm was 1.6 times longer than that observed in stallion (P < 0.05); however, these differences were not appreciated in somatic cells. In conclusion, ALS localization in sperm is not a randomized event and a different pattern of ALS distribution occurs for each species. These results suggest that ALS represents a species-specific issue related to chromatin organization in sperm and somatic cells in mammalian species, and they might diverge even with very short phylogenetic distances. PMID:24182740

  6. Interaction of macrophage migration inhibitory factor with ceruloplasmin: role of labile copper ions.

    PubMed

    Kostevich, Valeria A; Sokolov, Alexey V; Grudinina, Natalia A; Zakharova, Elena T; Samygina, Valeria R; Vasilyev, Vadim B

    2015-10-01

    Macrophage migration inhibitory factor (MIF), a pro-inflammatory cytokine, is a target for pharmacological treatment of sepsis and malignant tumors. Inhibition of tautomerase activity of MIF in reaction with p-hydroxyphenylpyruvate (HPP) was observed in the presence of ceruloplasmin (CP), a copper-containing plasma protein. Binding labile copper ions to CP (CP+Cu(II)) is a prerequisite for MIF inhibiting. CP+Cu(II) is shown to be an uncompetitive inhibitor of MIF (Ki ~ 37 nM), which suggests formation of a complex 'MIF-HPP-CP-Cu(II)'. Filtration of CP+Cu(II) on a column with Chelex-100, otherwise the presence of high concentrations of histidine, cysteine or methionine abrogated the inhibitory effect of CP. Adding salts of Co(II) and Ni(II) that replace copper ions in the labile sites prevented the inhibitory effect of CP+Cu(II). Limited proteolysis of CP by thrombin diminished its oxidase activity in reaction with p-phenylenediamine, but endowed it with the capacity of inhibiting MIF. Covalent modification of MIF by phenylmethylsulfonyl fluoride (PMSF) resulted in binding of MIF-PMSF to CP immobilized on CM5 chip, the dissociation constant being 4.2 ?M. In D-galactosamine-sensitized mice CP+Cu(II) increased the LPS-induced lethality from 54 to 100%, while administration of antibodies against MIF prevented the lethal effect. The enhancement by CP+Cu(II) of the pro-inflammatory signal of MIF is discussed. PMID:26091949

  7. A labile hydride strategy for the synthesis of heavily nitridized BaTiO3.

    PubMed

    Yajima, Takeshi; Takeiri, Fumitaka; Aidzu, Kohei; Akamatsu, Hirofumi; Fujita, Koji; Yoshimune, Wataru; Ohkura, Masatoshi; Lei, Shiming; Gopalan, Venkatraman; Tanaka, Katsuhisa; Brown, Craig M; Green, Mark A; Yamamoto, Takafumi; Kobayashi, Yoji; Kageyama, Hiroshi

    2015-12-01

    Oxynitrides have been explored extensively in the past decade because of their interesting properties, such as visible-light absorption, photocatalytic activity and high dielectric permittivity. Their synthesis typically requires high-temperature NH3 treatment (800-1,300?°C) of precursors, such as oxides, but the highly reducing conditions and the low mobility of N(3-) species in the lattice place significant constraints on the composition and structure-and hence the properties-of the resulting oxynitrides. Here we show a topochemical route that enables the preparation of an oxynitride at low temperatures (<500?°C), using a perovskite oxyhydride as a host. The lability of H(-) in BaTiO3-xHx (x ? 0.6) allows H(-)/N(3-) exchange to occur, and yields a room-temperature ferroelectric BaTiO3-xN2x/3. This anion exchange is accompanied by a metal-to-insulator crossover via mixed O-H-N intermediates. These findings suggest that this 'labile hydride' strategy can be used to explore various oxynitrides, and perhaps other mixed anionic compounds. PMID:26587718

  8. Chemical trapping of labile aldehyde intermediates in the metabolism of propranolol and oxprenolol.

    PubMed

    Goldszer, F; Tindell, G L; Walle, U K; Walle, T

    1981-11-01

    Propranolol is N-dealkylated to N-desisopropylpropranolol (DIP) by microsomal enzymes. DIP was shown in this study to be rapidly deaminated by monoamine oxidase (MAO). Thus, incubation of DIP (10(-4) M) with rat liver mitochondria for 90 min demonstrated 74.8 +/- 4.1% metabolism which was almost completely blocked by the MAO inhibitor pargyline (10(-5) M). The end products of this deamination were 3-(alpha-naphthoxy)-1,2-propylene glycol (Glycol) and 3-(alpha-naphthoxy)lactic acid (NLA). In the presence of excess NADH the Glycol was the major product whereas NLA was the major product in the presence of excess NAD+. The intermediate aldehyde in this deamination reaction, 3-(alpha-naphthoxy)-2-hydroxypropanal (Ald), was extremely labile and decomposed quantitatively to alpha-naphthol when removed from the incubates. However, the addition of methoxyamine hydrochloride directly to the incubates made it possible to chemically trap the intact Ald as an O-methyloxime and prove its structure by gas chromatography-mass spectrometry. The deamination of the primary amine of oxprenolol also gave rise to a labile aldehyde which could be trapped and identified as its O-methyloxime. PMID:7335950

  9. Constrained lability in floral evolution: counting convergent origins of hummingbird pollination in Penstemon and Keckiella.

    PubMed

    Wilson, Paul; Wolfe, Andrea D; Armbruster, W Scott; Thomson, James D

    2007-01-01

    In the clade of Penstemon and segregate genera, pollination syndromes are well defined among the 284 species. Most display combinations of floral characters associated with pollination by Hymenoptera, the ancestral mode of pollination for this clade. Forty-one species present characters associated with hummingbird pollination, although some of these ornithophiles are also visited by insects. The ornithophiles are scattered throughout the traditional taxonomy and across phylogenies estimated from nuclear (internal transcribed spacer (ITS)) and chloroplast DNA (trnCD/TL) sequence data. Here, the number of separate origins of ornithophily is estimated, using bootstrap phylogenies and constrained parsimony searches. Analyses suggest 21 separate origins, with overwhelming support for 10 of these. Because species sampling was incomplete, this is probably an underestimate. Penstemons therefore show great evolutionary lability with respect to acquiring hummingbird pollination; this syndrome acts as an attractor to which species with large sympetalous nectar-rich flowers have frequently been drawn. By contrast, penstemons have not undergone evolutionary shifts backwards or to other pollination syndromes. Thus, they are an example of both striking evolutionary lability and constrained evolution. PMID:17897322

  10. Multivariate Statistical Analysis of Labile Trace Elements in H Chondrites: Evidence for Meteoroid Streams

    NASA Astrophysics Data System (ADS)

    Wolf, S. F.; Lipschutz, M. E.

    1992-07-01

    Differences have been observed between meteorite populations with vastly different terrestrial ages, i.e. Antarctic and non-Antarctic meteorite populations (Koeberl and Cassidy, 1991 and references therein). Comparisons of labile trace element contents (Wolf and Lipschutz, 1992) and induced TL parameters (Benoit and Sears, 1992) in samples from Victoria Land and Queen Maud Land, populations which also differ in mean terrestrial age (Nishiizumi et al, 1989), show significant differences consistent with different average thermal histories. These differences are consistent with the proposition that the flux of meteoritic material to Earth varied temporally. Variations in the flux of meteoritic material over time scales of 10^5 10^6 y require the existence of undispersed streams of meteoroids of asteroidal origin which were initially disputed by Wetherill ( 1986) but have since been observed (Olsson-Steele, 1988; Oberst, 1989; Halliday et al. 1990). Orbital evidence for meteoroid and asteroid streams has been independently obtained by others, particularly Halliday et al.(1990) and Drummond (1991). A group of H chondrites of various petrographic types and diverse CRE ages that yielded 16 falls from 1855 until 1895 in the month of May has been proposed to be two co-orbital meteoroid streams with a common source (R. T. Dodd, personal communication). Compositional evidence of a preterrestrial association of the proposed stream members, if it exists, might be observed in the most sensitive indicators of genetic thermal history, the labile trace elements. We report RNAA data for the concentrations of 14 trace elements, mostly labile ones, (Ag, Au, Bi, Cd, Cs, Co, Ga, In, Rb, Sb, Se, Te, Tl, and Zn) in H4-6 ordinary chondrites. Variance of elemental concentrations within a subpopulation, the members of a proposed co-orbital meteorite stream for example, could be expected to be smaller than the variance for the entire population. We utilize multivariate linear regression and logistic regression statistical techniques as tools for discriminant analysis. A randomization-simulation technique can also be used to make distribution-independent comparisons and to verify that any observed differences are not due to insufficient samples or too many independent variables (Lipschutz and Samuels, 1991). These methods allow us to test for the existence of distinct compositional subpopulations in what is supposedly a single meteorite population. At the time of writing this abstract our database consists of 55 H4-6 chondrites (Lingner et al, 1987 and this work). Nine of these meteorites are members of the proposed "cluster 1" co-orbital meteoroid stream. For these 9 samples, linear discriminant analysis based on the concentrations of 10 labile trace elements reveals a difference between the "cluster 1" subpopulation of H chondrite falls and all other H chondrite falls at the <0.03 significance level. Logistic regression reveals a difference at the <0.0001 significance level. Normalization of data to Allende standard meteorite reference standard to eliminate bias conceivably due to different analysts yields results comparable to results from the non-normalized data. Additional evidence for the absence of interanalyst bias is provided by data of samples from Victoria Land, Antarctica: random populations analyzed by the present authors (Wolf and Lipschutz, 1992) are statistically indistinguishable from populations analyzed previously (Dennison and Lipschutz, 1987). A logistic regression validation run also supports the lack of interanalyst bias. Results from linear discriminant analysis, and logistic regression randomization-simulations will be presented in Copenhagen. These results on a limited population, which may be expanded by meeting time demonstrate that the "cluster 1" subpopulation of H chondrite falls are distinguishable from all other H chondrite falls on the basis of their labile trace elements, a result that is consistent with the idea that these meteorites had a common thermal history and were assoc

  11. Metal contents of phytoplankton and labile particulate material in the North Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Twining, Benjamin S.; Rauschenberg, Sara; Morton, Peter L.; Vogt, Stefan

    2015-09-01

    Phytoplankton contribute significantly to global C cycling and serve as the base of ocean food webs. Phytoplankton require trace metals for growth and also mediate the vertical distributions of many metals in the ocean. We collected bulk particulate material and individual phytoplankton cells from the upper water column (<150 m) of the North Atlantic Ocean as part of the US GEOTRACES North Atlantic Zonal Transect cruise (GEOTRACES GA03). Particulate material was first leached to extract biogenic and potentially-bioavailable elements, and the remaining refractory material was digested in strong acids. The cruise track spanned several ocean biomes and geochemical regions. Particulate concentrations of metals associated primarily with lithogenic phases (Fe, Al, Ti) were elevated in surface waters nearest North America, Africa and Europe, and elements associated primarily with biogenic material (P, Cd, Zn, Ni) were also found at higher concentrations near the coasts. However metal/P ratios of labile particulate material were also elevated in the middle of the transect for Fe, Ni, Co, Cu, and V. P-normalized cellular metal quotas measured with synchrotron X-ray fluorescence (SXRF) were generally comparable to ratios in bulk labile particles but did not show mid-basin increases. Manganese and Fe ratios and cell quotas were higher in the western part of the section, nearest North America, and both elements were more enriched in bulk particles, relative to P, than in cells, suggesting the presence of labile oxyhydroxide particulate phases. Cellular Fe quotas thus did not increase in step with aeolian dust inputs, which are highest near Africa; these data suggest that the dust inputs have low bioavailability. Copper and Ni cell quotas were notably higher nearest the continental margins. Overall mean cellular metal quotas were similar to those measured in the Pacific and Southern Oceans except for Fe, which was approximately 3-fold higher in North Atlantic cells. Cellular Fe quotas are in-line with those measured in laboratory cultures at comparable Fe concentrations. Particulate Zn, Cu, Ni, and Co are primarily associated with cellular material, but less than 30% of labile particulate Fe and Mn are biogenic. Particulate Al was primarily associated with lithogenic material, but the labile fraction was highly correlated with P, as well as with biogenic silica, suggesting that some particulate Al (perhaps around 20%) may occur adsorbed to biogenic material. Cellular element maps indicate that externally scavenged Fe was not a significant fraction of the metal associated with live phytoplankton, but adsorbed or precipitated phases are likely to be important in particulate detrital material. Such abiotic scavenging, along with differential remineralization of cellular nutrients in the water column, results in estimates of cellular metal/nutrient ratios from dissolved concentrations that significantly underestimate the ratios in phytoplankton. These data demonstrate the response of phytoplankton to the unique metal inputs to the North Atlantic Ocean.

  12. 11 Photoactivated Perylenequinone Toxins in Plant Pathogenesis MARGARET E. DAUB1

    E-print Network

    Daub, Margaret

    11 Photoactivated Perylenequinone Toxins in Plant Pathogenesis MARGARET E. DAUB1 , KUANG-REN CHUNG2 Toxins. . . . . . . . . . . . . . . . . . . 201 A. Fungal Perylenequinone Toxins . . . . . . . . . 201 B. Mode of Action of Perylenequinone Toxins . . . . . . . . . . . . . . . . 203 III. Cercosporin

  13. Cyanobacterial Toxin Degrading Bacteria: Who Are They?

    PubMed Central

    Kormas, Konstantinos Ar.; Lymperopoulou, Despoina S.

    2013-01-01

    Cyanobacteria are ubiquitous in nature and are both beneficial and detrimental to humans. Benefits include being food supplements and producing bioactive compounds, like antimicrobial and anticancer substances, while their detrimental effects are evident by toxin production, causing major ecological problems at the ecosystem level. To date, there are several ways to degrade or transform these toxins by chemical methods, while the biodegradation of these compounds is understudied. In this paper, we present a meta-analysis of the currently available 16S rRNA and mlrA (microcystinase) genes diversity of isolates known to degrade cyanobacterial toxins. The available data revealed that these bacteria belong primarily to the Proteobacteria, with several strains from the sphingomonads, and one from each of the Methylobacillus and Paucibacter genera. Other strains belonged to the genera Arthrobacter, Bacillus, and Lactobacillus. By combining the ecological knowledge on the distribution, abundance, and ecophysiology of the bacteria that cooccur with toxic cyanobacterial blooms and newly developed molecular approaches, it is possible not only to discover more strains with cyanobacterial toxin degradation abilities, but also to reveal the genes associated with the degradation of these toxins. PMID:23841072

  14. Therapy and prophylaxis of inhaled biological toxins.

    PubMed

    Paddle, Brian M

    2003-01-01

    This review highlights the current lack of therapeutic and prophylactic treatments for use against inhaled biological toxins, especially those considered as potential biological warfare (BW) or terrorist threats. Although vaccine development remains a priority, the use of rapidly deployable adjunctive therapeutic or prophylactic drugs could be life-saving in severe cases of intoxication or where vaccination has not been possible or immunity not established. The current lack of such drugs is due to many factors. Thus, methods involving molecular modelling are limited by the extent to which the cellular receptor sites and mode of action and structure of a toxin need to be known. There is also our general lack of knowledge of what effect individual toxins will have when inhaled into the lungs - whether and to what extent the action will be cell specific and cytotoxic or rather an acute inflammatory response requiring the use of immunomodulators. Possible sources of specific high-affinity toxin antagonists being investigated include monoclonal antibodies, selected oligonucleotides (aptamers) and derivatized dendritic polymers (dendrimers). The initial selection of suitable agents of these kinds can be made using cytotoxicity assays involving cultured normal human lung cells and a range of suitable indicators. The possibility that a mixture of selected antibody, aptamer or dendrimer-based materials for one or more toxins could be delivered simultaneously as injections or as inhaled aerosol sprays should be investigated. PMID:12794937

  15. Array biosensor for detection of toxins

    NASA Technical Reports Server (NTRS)

    Ligler, Frances S.; Taitt, Chris Rowe; Shriver-Lake, Lisa C.; Sapsford, Kim E.; Shubin, Yura; Golden, Joel P.

    2003-01-01

    The array biosensor is capable of detecting multiple targets rapidly and simultaneously on the surface of a single waveguide. Sandwich and competitive fluoroimmunoassays have been developed to detect high and low molecular weight toxins, respectively, in complex samples. Recognition molecules (usually antibodies) were first immobilized in specific locations on the waveguide and the resultant patterned array was used to interrogate up to 12 different samples for the presence of multiple different analytes. Upon binding of a fluorescent analyte or fluorescent immunocomplex, the pattern of fluorescent spots was detected using a CCD camera. Automated image analysis was used to determine a mean fluorescence value for each assay spot and to subtract the local background signal. The location of the spot and its mean fluorescence value were used to determine the toxin identity and concentration. Toxins were measured in clinical fluids, environmental samples and foods, with minimal sample preparation. Results are shown for rapid analyses of staphylococcal enterotoxin B, ricin, cholera toxin, botulinum toxoids, trinitrotoluene, and the mycotoxin fumonisin. Toxins were detected at levels as low as 0.5 ng mL(-1).

  16. In situ high-resolution evaluation of labile arsenic and mercury in sediment of a large shallow lake.

    PubMed

    Wang, Chao; Yao, Yu; Wang, Peifang; Hou, Jun; Qian, Jin; Yuan, Ye; Fan, Xiulei

    2016-01-15

    The precise evaluation of arsenic (As) and mercury (Hg) bioavailability in sediment is crucial to controlling As and Hg contamination, but traditional ex situ measurements hamper comprehensive analysis of labile As and Hg in sediment. In this study, we characterized in situ labile As and Hg in sediment of Lake Hongze using the zirconium (Zr) oxide diffusive gradients in thin films (DGT) technique and 3-mercaptopropyl functionalized silica gel DGT, respectively. The concentrations of DGT-labile As and Hg in the sediment profiles were found to exhibit considerable variation, ranging from 0.15 to 4.15?gL(-1) for As and from 0.04 to 1.35?gL(-1) for Hg. As and Hg flux values, calculated based on the concentration gradients measured from the DGT profiles for both the overlying water and sediment close to the sediment-water interface, were used to determine the contamination status of As and Hg. Flux values of As and Hg were between -0.066 and 0.067ngcm(-2)d(-1) and between -0.0187 and 0.0181ngcm(-2)d(-1), respectively. The GNU's Not Unix R (GNU R) programming language was used to identify outliers of As and Hg at various depths at the sampling sites. The results indicate that the sites with the most outliers were all located in the regions that were seriously affected by contaminants from the Huai River. The DGT-labile As and Hg concentrations in the 0-30mm layer were found to be significantly correlated with concentrations of labile As and Hg, total dissolved As and Hg, and total As and Hg in the overlying water, as indicated by ex situ measurements. Results show that DGT is a reliable and high-resolution technique that can be used for in situ monitoring of the labile fractions of As and Hg in sediment in fresh water bodies. PMID:26398454

  17. A Truncated Diphtheria Toxin Based Recombinant Porcine CTLA-4 Fusion Toxin

    PubMed Central

    Peraino, Jaclyn Stromp; Schenk, Marian; Zhang, Huiping; Li, Guoying; Hermanrud, Christina E.; Neville, David M.; Sachs, David H.; Huang, Christene A.; Duran-Struuck, Raimon; Wang, Zhirui

    2013-01-01

    Targeted cell therapies are possible through the generation of recombinant fusion proteins that combine a toxin, such as diphtheria toxin (DT), with an antibody or other molecule that confers specificity. Upon binding of the fusion protein to the cell of interest, the diphtheria toxin is internalized which results in protein synthesis inhibition and subsequent cell death. We have recently expressed and purified the recombinant soluble porcine CTLA-4 both with and without N-glycosylation in yeast Pichia Pastoris for in vivo use in our preclinical swine model. The glycosylated and non-N-glycosylated versions of this recombinant protein each bind to a porcine CD80 expressing B-cell lymphoma line (LCL13271) with equal affinity (KD = 13 nM). In this study we have linked each of the glycosylated and non-N-glycosylated soluble porcine CTLA-4 proteins to the truncated diphtheria toxin DT390 through genetic engineering yielding three versions of the porcine CTLA-4 fusion toxins: 1) monovalent glycosylated soluble porcine CTLA-4 fusion toxin; 2) monovalent non-N-glycosylated soluble porcine CTLA-4 fusion toxin and 3) bivalent non-N-glycosylated soluble porcine CTLA-4 fusion toxin. Protein synthesis inhibition analysis demonstrated that while all three fusion toxins are capable of inhibiting protein synthesis in vitro, the non-N-glycosylated porcine CTLA-4 isoforms function most efficiently. Binding analysis using flow cytometry of the porcine CTLA-4 fusion toxins to LCL13271 cells also demonstrated that the non-N-glycosylated porcine CTLA-4 isoforms bind to theses cells with higher affinity compared to the glycosylated fusion toxin. The monovalent non-N-glycosylated porcine CTLA-4 fusion toxin was tested in vivo. NSG (NOD/SCID IL-2 receptor ??/?) mice were injected with porcine CD80+ LCL13271 tumor cells. All animals succumbed to tumors and those treated with the monovalent non-N-glycosylated porcine CTLA-4 fusion toxin survived longer based on a symptomatic scoring system compared to the untreated controls. This recombinant protein may therefore provide a novel approach for in vivo depletion of porcine antigen presenting cells (APCs) for studies investigating the induction of transplantation tolerance, autoimmune disease and cancer treatment. PMID:23470981

  18. 42 CFR 73.4 - Overlap select agents and toxins.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...Recombinant and/or Synthetic Organisms: (1) Nucleic...section that have been genetically modified. (d) Overlap...or a select toxin modified to be less potent...attenuated strain or modified toxin does not...

  19. Resistance to Cry toxins and epithelial healing Anas Castagnola, Juan Luis Jurat-Fuentes

    E-print Network

    Jurat-Fuentes, Juan Luis

    Resistance to Cry toxins and epithelial healing Anaïs Castagnola, Juan Luis Jurat: Resistance to Cry toxins can develop by alterations in any of the steps in the Cry toxin mode of action. Most characterized mechanisms of resistance to Cry toxins involve alterations in enzymatic toxin processing or toxin

  20. Bacterial Toxins and the Nervous System: Neurotoxins and Multipotential Toxins Interacting with Neuronal Cells

    PubMed Central

    Popoff, Michel R.; Poulain, Bernard

    2010-01-01

    Toxins are potent molecules used by various bacteria to interact with a host organism. Some of them specifically act on neuronal cells (clostridial neurotoxins) leading to characteristics neurological affections. But many other toxins are multifunctional and recognize a wider range of cell types including neuronal cells. Various enterotoxins interact with the enteric nervous system, for example by stimulating afferent neurons or inducing neurotransmitter release from enterochromaffin cells which result either in vomiting, in amplification of the diarrhea, or in intestinal inflammation process. Other toxins can pass the blood brain barrier and directly act on specific neurons. PMID:22069606

  1. Streptococcal toxins: role in pathogenesis and disease.

    PubMed

    Barnett, Timothy C; Cole, Jason N; Rivera-Hernandez, Tania; Henningham, Anna; Paton, James C; Nizet, Victor; Walker, Mark J

    2015-12-01

    Group A Streptococcus (Streptococcus pyogenes), group B Streptococcus (Streptococcus agalactiae) and Streptococcus pneumoniae (pneumococcus) are host-adapted bacterial pathogens among the leading infectious causes of human morbidity and mortality. These microbes and related members of the genus Streptococcus produce an array of toxins that act against human cells or tissues, resulting in impaired immune responses and subversion of host physiological processes to benefit the invading microorganism. This toxin repertoire includes haemolysins, proteases, superantigens and other agents that ultimately enhance colonization and survival within the host and promote dissemination of the pathogen. PMID:26433203

  2. Natural Toxins for Use in Pest Management

    PubMed Central

    Duke, Stephen O.; Cantrell, Charles L.; Meepagala, Kumudini M.; Wedge, David E.; Tabanca, Nurhayat; Schrader, Kevin K.

    2010-01-01

    Natural toxins are a source of new chemical classes of pesticides, as well as environmentally and toxicologically safer molecules than many of the currently used pesticides. Furthermore, they often have molecular target sites that are not exploited by currently marketed pesticides. There are highly successful products based on natural compounds in the major pesticide classes. These include the herbicide glufosinate (synthetic phosphinothricin), the spinosad insecticides, and the strobilurin fungicides. These and other examples of currently marketed natural product-based pesticides, as well as natural toxins that show promise as pesticides from our own research are discussed. PMID:22069667

  3. Marine Toxins Targeting Ion Channels

    PubMed Central

    Arias, Hugo R.

    2006-01-01

    This introductory minireview points out the importance of ion channels for cell communication. The basic concepts on the structure and function of ion channels triggered by membrane voltage changes, the so-called voltage-gated ion channels (VGICs), as well as those activated by neurotransmitters, the so-called ligand-gated ion channel (LGICs), are introduced. Among the most important VGIC superfamiles, we can name the voltage-gated Na+ (NaV), Ca2+ (CaV), and K+ (KV) channels. Among the most important LGIC super families, we can include the Cys-loop or nicotinicoid, the glutamate-activated (GluR), and the ATP-activated (P2XnR) receptor superfamilies. Ion channels are transmembrane proteins that allow the passage of different ions in a specific or unspecific manner. For instance, the activation of NaV, CaV, or KV channels opens a pore that is specific for Na+, Ca2+, or K+, respectively. On the other hand, the activation of certain LGICs such as nicotinic acetylcholine receptors, GluRs, and P2XnRs allows the passage of cations (e.g., Na+, K+, and/or Ca2+), whereas the activation of other LGICs such as type A ?-butyric acid and glycine receptors allows the passage of anions (e.g., Cl? and/or HCO3?). In this regard, the activation of NaV and CaV as well as ligand-gated cation channels produce membrane depolarization, which finally leads to stimulatory effects in the cell, whereas the activation of KV as well as ligand-gated anion channels induce membrane hyperpolarization that finally leads to inhibitory effects in the cell. The importance of these ion channel superfamilies is emphasized by considering their physiological functions throughout the body as well as their pathophysiological implicance in several neuronal diseases. In this regard, natural molecules, and especially marine toxins, can be potentially used as modulators (e.g., inhibitors or prolongers) of ion channel functions to treat or to alleviate a specific ion channel-linked disease (e.g., channelopaties).

  4. EFFECTS OF MARINE ALGAL TOXINS ON THERMOREGULATION IN MICE.

    EPA Science Inventory

    Hypothermia is often seen in mice and rats exposed acutely to marine algal toxins, but the mechanism of action of these toxins on thermoregulation is not well understood. Our laboratory has assessed the thermoregulatory mechanisms of two marine algal toxins, maitotoxin and brevet...

  5. 9 CFR 121.3 - VS select agents and toxins.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 9 Animals and Animal Products 1 2013-01-01 2013-01-01 false VS select agents and toxins. 121.3 Section 121.3 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE VIRUSES, SERUMS, TOXINS, AND ANALOGOUS PRODUCTS; ORGANISMS AND VECTORS POSSESSION, USE, AND TRANSFER OF SELECT AGENTS AND TOXINS § 121.3...

  6. 77 FR 9888 - Shiga Toxin-Producing Escherichia coli

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-21

    ... Safety and Inspection Service Shiga Toxin-Producing Escherichia coli in Certain Raw Beef Products AGENCY... manufacturing trimmings for six non-O157 Shiga toxin-producing Escherichia coli (STEC) serogroups (O26, O45..., non-intact product, that are contaminated with Shiga toxin-producing Escherichia coli (STEC) O26,...

  7. Pasteurella multocida toxin activation of heterotrimeric G proteins by deamidation

    E-print Network

    Just, Armin

    Pasteurella multocida toxin activation of heterotrimeric G proteins by deamidation Joachim H. C multocida toxin is a major virulence factor of Pasteu- rella multocida, which causes pasteurellosis in men and animals and atrophic rhinitis in rabbits and pigs. The 145 kDa protein toxin stimulates various signal

  8. HAZARDOUS MARINE ALGAL TOXINS: TRAINING, OVERVIEW, AND EXPERIMENTAL WORK

    E-print Network

    Qiu, Bo

    HAZARDOUS MARINE ALGAL TOXINS: TRAINING, OVERVIEW, AND EXPERIMENTAL WORK A THESIS SUBMITTED assembling a summary of nine naturally-occurring marine toxins of algal origin. Ciguatoxin, one of a number of natural marine toxins produced by dinoflagellates and poorly understood generally, is a principle focus

  9. Toxin Production by Gambierdiscus toxicus Isolated from the Florida Keys

    E-print Network

    Toxin Production by Gambierdiscus toxicus Isolated from the Florida Keys JOHN A. BABINCHAK, DAVID J-borne disease in which the lipid-soluble neuro- toxin, ciguatoxin, is believed to be trans- ferred through, and extracted for toxins that have been analyzed principally by mouse bioassay. Evidence that G. toxicus

  10. Microreview Streptococcal toxins: role in pathogenesis and disease

    E-print Network

    Nizet, Victor

    Microreview Streptococcal toxins: role in pathogenesis and disease Timothy C. Barnett,1 Jason N an array of toxins that act against human cells or tissues, resulting in impaired immune responses and subversion of host physiological processes to benefit the invading microorganism. This toxin repertoire

  11. Many roads to resistance: how invertebrates adapt to Bt toxins

    E-print Network

    Aroian, Raffi V.

    Many roads to resistance: how invertebrates adapt to Bt toxins Joel S. Griffitts and Raffi V agents. An understanding of Cry toxin resistance at a molecular level will be critical to the long-term utility of this technology; it may also shed light on basic mechanisms used by other bacterial toxins

  12. Photoactivated perylenequinone toxins in fungal pathogenesis of plants

    E-print Network

    Burns, Jacqueline K.

    MiniReview Photoactivated perylenequinone toxins in fungal pathogenesis of plants Margaret E. Daub.C. Staples Abstract Several genera of plant pathogenic fungi produce photoactivated perylenequinone toxins involved in pathogenesis of their hosts. These toxins are photosensitizers, absorbing light energy

  13. 77 FR 9888 - Shiga Toxin-Producing Escherichia coli

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-21

    ...FSIS-2010-0023] Shiga Toxin-Producing Escherichia coli in Certain Raw Beef Products AGENCY: Food...non-O157 Shiga toxin-producing Escherichia coli (STEC) serogroups (O26, O45, O103...with Shiga toxin-producing Escherichia coli (STEC) O26, O45, O103, O111,...

  14. Effects of dynamin inactivation on pathways of anthrax toxin uptake

    E-print Network

    Kirchhausen, Tomas

    2/18/04 1 Effects of dynamin inactivation on pathways of anthrax toxin uptake Werner Boll1: anthrax toxin, endocytosis, clathrin, dynamin Running title: Pathways of anthrax toxin uptake #12;Internalization and traffic to acidic endosomes of anthrax lethal factor (LF) and protective antigen (PA), bound

  15. Anthrax toxin-induced rupture of artificial lipid bilayer membranes

    NASA Astrophysics Data System (ADS)

    Nablo, Brian J.; Panchal, Rekha G.; Bavari, Sina; Nguyen, Tam L.; Gussio, Rick; Ribot, Wil; Friedlander, Art; Chabot, Donald; Reiner, Joseph E.; Robertson, Joseph W. F.; Balijepalli, Arvind; Halverson, Kelly M.; Kasianowicz, John J.

    2013-08-01

    We demonstrate experimentally that anthrax toxin complexes rupture artificial lipid bilayer membranes when isolated from the blood of infected animals. When the solution pH is temporally acidified to mimic that process in endosomes, recombinant anthrax toxin forms an irreversibly bound complex, which also destabilizes membranes. The results suggest an alternative mechanism for the translocation of anthrax toxin into the cytoplasm.

  16. A superior drug carrier – aponeocarzinostatin in partially unfolded state fully protects the labile antitumor enediyne

    PubMed Central

    Shanmuganathan, Aranganathan; Kumar, Thallapuranam Krishnaswamy Suresh; Huang, Chiy-Mey; Yu, Chin; Chin, Der-Hang

    2009-01-01

    Background Neocarzinostatin is a potent antitumor drug consisting of an enediyne chromophore and a protein carrier. Methods We characterized an intermediate in the equilibrium unfolding pathway of aponeocarzinostatin, using a variety of biophysical techniques including 1-anilino-8-napthalene sulfonate binding studies, size-exclusion fast protein liquid chromatography, intrinsic tryptophan fluorescence, circular dichroism, and 1H-15N heteronuclear single quantum coherence spectroscopy. Results The partially unfolded protein is in molten globule-like state, in which ~60% and ~20% tertiary and secondary structure is disrupted respectively. Despite lacking a fully coordinated tertiary structure for assembling a functional binding cleft, the protein in molten globule-like state is still able to fully protect the labile chromophore. Titration of chromophore leads the partially denatured apoprotein to fold into its native state. Conclusion These findings bring insight into conserving mechanism of neocarzinostatin under harsh environment, where even the partially denatured apoprotein exhibits protective effect, confirming the superiority of the drug carrier. PMID:19463188

  17. Significance of Isotopically Labile Organic Hydrogen in Thermal Maturation of Organic Matter

    SciTech Connect

    Arndt Schimmelmann; Maria Mastalerz

    2010-03-30

    Isotopically labile organic hydrogen in fossil fuels occupies chemical positions that participate in isotopic exchange and in chemical reactions during thermal maturation from kerogen to bitumen, oil and gas. Carbon-bound organic hydrogen is isotopically far less exchangeable than hydrogen bound to nitrogen, oxygen, or sulfur. We explore why organic hydrogen isotope ratios express a relationship with organic nitrogen isotope ratios in kerogen at low to moderate maturity. We develop and apply new techniques to utilize organic D/H ratios in organic matter fractions and on a molecular level as tools for exploration for fossil fuels and for paleoenvironmental research. The scope of our samples includes naturally and artificially matured substrates, such as coal, shale, oil and gas.

  18. Following The Money: Characterizing the Dynamics of Microbial Ecosystems and Labile Organic Matter in Grassland Soils

    NASA Astrophysics Data System (ADS)

    Herbert, B. E.; McNeal, K. S.

    2006-12-01

    The dynamics of soil microbial ecosystems and labile fractions of soil organic matter in grasslands have important implications for the response of these critical ecosystems to perturbations. Organic, inorganic and genetic biomarkers in the solid (e.g. lipids, microbial DNA), liquid (e.g. porewater ions) or gaseous phases (e.g. carbon dioxide) have been used to characterize carbon cycling and soil microbial ecology. These proxies are generally limited in the amount of temporal information that they can provide (i.e., solid-phase proxies) or the amount of specific information they can provide about carbon sources or microbial community processes (e.g. inorganic gases). It is the aim of this research to validate the use of soil volatile organic carbon emissions (VOCs) as useful indicators of subsurface microbial community shifts and processes as a function of ecosystem perturbations. We present results of method validation using laboratory microcosm, where VOC metabolites as characterized by gas chromatography and mass spectrometry (GC-MS), were related to other proxies including carbon dioxide (CO2) via infra-red technology, and microbial community shifts as measured by Biolog© and fatty acid methyl ester (FAME) techniques. Experiments with soil collected from grasslands along the coastal margin region in southern Texas were preformed where environmental factors such as soil water content, soil type, and charcoal content are manipulated. Results indicate that over fifty identifiable VOC metabolites are produced from the soils, where many (~15) can be direct indicators of microbial ecology. Principle component analysis (PCA) evidences these trends through similar cluster patterns for the VOC results, the Biolog© results, and FAME. Regression analysis further shows that VOCs are significant (p < 0.05) indicators of microbial stress. Our results are encouraging that characterizing VOCs production in grassland soils are easy to measure, relatively inexpensive method, and useful proxies of subsurface microbial ecosystems and the dynamics of labile carbon in these systems.

  19. High lability of sexual system over 250 million years of evolution in morphologically conservative tadpole shrimps

    PubMed Central

    2013-01-01

    Background Sexual system is a key factor affecting the genetic diversity, population structure, genome structure and the evolutionary potential of species. The sexual system androdioecy – where males and hermaphrodites coexist in populations – is extremely rare, yet is found in three crustacean groups, barnacles, a genus of clam shrimps Eulimnadia, and in the order Notostraca, the tadpole shrimps. In the ancient crustacean order Notostraca, high morphological conservatism contrasts with a wide diversity of sexual systems, including androdioecy. An understanding of the evolution of sexual systems in this group has been hampered by poor phylogenetic resolution and confounded by the widespread occurrence of cryptic species. Here we use a multigene supermatrix for 30 taxa to produce a comprehensive phylogenetic reconstruction of Notostraca. Based on this phylogenetic reconstruction we use character mapping techniques to investigate the evolution of sexual systems. We also tested the hypothesis that reproductive assurance has driven the evolution of androdioecy in Notostraca. Results Character mapping analysis showed that sexual system is an extremely flexible trait within Notostraca, with repeated shifts between gonochorism and androdioecy, the latter having evolved a minimum of five times. In agreement with the reproductive assurance hypothesis androdioecious notostracans are found at significantly higher latitudes than gonochoric ones indicating that post glacial re-colonisation may have selected for the higher colonisation ability conferred by androdioecy. Conclusions In contrast to their conserved morphology, sexual system in Notostraca is highly labile and the rare reproductive mode androdioecy has evolved repeatedly within the order. Furthermore, we conclude that this lability of sexual system has been maintained for at least 250 million years and may have contributed to the long term evolutionary persistence of Notostraca. Our results further our understanding of the evolution of androdioecy and indicate that reproductive assurance is a recurrent theme involved in the evolution of this sexual system. PMID:23384124

  20. Oxidative stress and labile plasmatic iron in anemic patients following blood therapy

    PubMed Central

    Fernandes, Marília Sabo; Rissi, Tatiana Tamborena; Zuravski, Luisa; Mezzomo, Juliana; Vargas, Carmen Regla; Folmer, Vanderlei; Soares, Félix Alexandre Antunes; Manfredini, Vanusa; Ahmed, Mushtaq; Puntel, Robson Luiz

    2014-01-01

    AIM: To determine the plasmatic iron content and evaluate the oxidative stress (OS) markers in subjects receiving blood therapy. METHODS: Thirty-nine individuals with unspecified anemia receiving blood transfusions and 15 healthy subjects were included in the study. Anemic subjects were divided into three subgrouP: (1) those that received up to five blood transfusions (n = 14); (2) those that received from five to ten transfusions (n = 11); and (3) those that received more than ten transfusions (n = 14). Blood samples were collected by venous arm puncture and stored in tubes containing heparin. The plasma and cells were separated by centrifugation and subsequently used for analyses. Statistical analyses were performed using Kruskal-Wallis analysis of variance followed by Dunn’s multiple comparison tests when appropriate. RESULTS: The eletrophoretic hemoglobin profiles of the subjects included in this study indicated that no patients presented with hemoglobinopathy. Labile plasmatic iron, ferritin, protein carbonyl, thiobarbituric acid-reactive substances (TBARS) and dichlorofluorescein diacetate oxidation were significantly higher (P < 0.05), whereas total thiol levels were significantly lower (P < 0.05) in transfused subjects compared to controls. Additionally, the activity of catalase, superoxide dismutase and glutathione peroxidase were significantly lower in the transfused subjects (P < 0.05). Antioxidant enzyme activities and total thiol levels were positively correlated (P < 0.05), and negatively correlated with the levels of protein carbonyl and TBARS (P < 0.05). In contrast, protein carbonyl and TBARS were positively correlated (P < 0.05). Altogether, these data confirm the involvement of OS in patients following therapy with repeated blood transfusions. CONCLUSION: Our data reveal that changes in OS markers are correlated with levels of labile plasmatic iron and ferritin and the number of transfusions. PMID:25254188

  1. In vivo lability of glucose-6-phosphate dehydrogenase in GdA- and Gdmediterranean deficiency

    PubMed Central

    Piomelli, Sergio; Corash, Laurence M.; Davenport, Deatra D.; Miraglia, Janet; Amorosi, Edward L.

    1968-01-01

    A decreased level of glucose-6-phosphate dehydrogenase might result from decreased rate of synthesis, synthesis of an enzyme of lower catalytic efficiency, increased lability, or a combined mechanism. To test the hypothesis of increased lability, the rate of decline of the enzyme in vivo was measured in three groups of individuals, controls, Gd(—),A-males, and Gd(—), Mediterranean males, by the slope of decline of activity in fractions containing erythrocytes of progressively increasing mean age. These fractions were obtained by ultracentrifugation on a discontinuous density gradient of erythrocyte suspensions free of contaminating platelets and leukocytes. The rate of in vivo decline of pyruvate kinase (another age-dependent enzyme) was also measured and found very similar in the three groups. The in vivo decline of glucose-6-phosphate dehydrogenase was found to follow an exponential rate, with a half-life of 62 days for controls and 13 days for Gd(—),A- erythrocytes. The activity in normal reticulocytes was estimated at 9.7 U and in Gd(—),A- reticulocytes at 8.8 U. These estimates were confirmed by direct measurements in reticulocytes isolated from patients with extreme reticulocytosis. In Gd(—),Mediterranean erythrocytes activity could be demonstrated only in reticulocytes, which were estimated to average 1.4 U. The rate of decline is so extreme that no activity could be detected in mature erythrocytes. These data suggest that the glucose-6-phosphate dehydrogenase deficiency of both the GdA- and the GdMediterranean variant results from different degrees of in vivo instability of the abnormal enzyme. PMID:5641629

  2. Molecular insights into the microbial formation of marine dissolved organic matter: recalcitrant or labile?

    NASA Astrophysics Data System (ADS)

    Koch, B. P.; Kattner, G.; Witt, M.; Passow, U.

    2014-02-01

    The degradation of marine dissolved organic matter (DOM) is an important control variable in the global carbon cycle and dependent on the DOM composition. For our understanding of the kinetics of organic matter cycling in the ocean, it is therefore crucial to achieve a mechanistic and molecular understanding of its transformation processes. A long-term microbial experiment was performed to follow the production of non-labile DOM by marine bacteria. Two different glucose concentrations and dissolved algal exudates were used as substrates. We monitored the bacterial abundance, concentrations of dissolved and particulate organic carbon (DOC, POC), nutrients, amino acids, and transparent exopolymer particles (TEP) for two years. Ultrahigh resolution Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR-MS) allowed the molecular characterization of extracted DOM after 70 days and after ∼2 years of incubation. Although glucose was quickly degraded, a DOC background was generated in glucose incubations. Only 20% of the organic carbon from algal exudate was degraded within the 2 years of incubation. TEP, which are released by micro-organisms, were produced during glucose degradation but decreased within less than three weeks back to half of the maximum concentration and were below detection in all treatments after 2 years. The molecular analysis demonstrated that DOM generated during glucose degradation differed appreciably from DOM produced during the degradation of the algal exudates. Our results led to several conclusions: (i) Higher substrate levels result in a higher level of non-labile DOC which is an important prerequisite for carbon sequestration in the ocean; (ii) TEP are generated by bacteria but are also degraded rapidly, thus limiting their potential contribution to carbon sequestration; (iii) The molecular signatures of DOM derived from algal exudates or glucose after 70 days of incubation differed strongly from refractory DOM. After 2 years, however, the molecular patterns of DOM in glucose incubations were more similar to deep ocean DOM whereas the degraded exudate was still different.

  3. Clostridium difficile toxin B is more potent than toxin A in damaging human colonic epithelium in vitro.

    PubMed Central

    Riegler, M; Sedivy, R; Pothoulakis, C; Hamilton, G; Zacherl, J; Bischof, G; Cosentini, E; Feil, W; Schiessel, R; LaMont, J T

    1995-01-01

    Toxin A but not toxin B, appears to mediate intestinal damage in animal models of Clostridium difficile enteritis. The purpose of this study was to investigate the electrophysiologic and morphologic effects of purified C. difficile toxins A and B on human colonic mucosa in Ussing chambers. Luminal exposure of tissues to 16-65 nM of toxin A and 0.2-29 nM of toxin B for 5 h caused dose-dependent epithelial damage. Potential difference, short-circuit current and resistance decreased by 76, 58, and 46%, respectively, with 32 nM of toxin A and by 76, 55, and 47%, respectively, with 3 nM of toxin B, when compared with baseline (P < 0.05). 3 nM of toxin A did not cause electrophysiologic changes. Permeability to [3H]mannitol increased 16-fold after exposure to 32 nM of toxin A and to 3 nM of toxin B when compared with controls (P < 0.05). Light and scanning electron microscopy after exposure to either toxin revealed patchy damage and exfoliation of superficial epithelial cells, while crypt epithelium remained intact. Fluorescent microscopy of phalloidin-stained sections showed that both toxins caused disruption and condensation of cellular F-actin. Our results demonstrate that the human colon is approximately 10 times more sensitive to the damaging effects of toxin B than toxin A, suggesting that toxin B may be more important than toxin A in the pathogenesis of C. difficile colitis in man. Images PMID:7738167

  4. Escherichia coli toxin/antitoxin pair MqsR/MqsA regulate toxin CspDemi_2147 1105..1121

    E-print Network

    Wood, Thomas K.

    Escherichia coli toxin/antitoxin pair MqsR/MqsA regulate toxin CspDemi_2147 1105..1121 Younghoon identified that the Escherichia coli protein MqsR (YgiU) functions as a toxin and that it is involved that MqsR and MqsA (YgiT) are a toxin/antitoxin (TA) pair, which, in significant dif- ference to other TA

  5. Emotional Lability in Children and Adolescents with Attention Deficit/Hyperactivity Disorder (ADHD): Clinical Correlates and Familial Prevalence

    ERIC Educational Resources Information Center

    Sobanski, Esther; Banaschewski, Tobias; Asherson, Philip; Buitelaar, Jan; Chen, Wai; Franke, Barbara; Holtmann, Martin; Krumm, Bertram; Sergeant, Joseph; Sonuga-Barke, Edmund; Stringaris, Argyris; Taylor, Eric; Anney, Richard; Ebstein, Richard P.; Gill, Michael; Miranda, Ana; Mulas, Fernando; Oades, Robert D.; Roeyers, Herbert; Rothenberger, Aribert; Steinhausen, Hans-Christoph; Faraone, Stephen V.

    2010-01-01

    Background: The goal of this study was to investigate the occurrence, severity and clinical correlates of emotional lability (EL) in children with attention deficit/hyperactivity disorder (ADHD), and to examine factors contributing to EL and familiality of EL in youth with ADHD. Methods: One thousand, one hundred and eighty-six children with ADHD…

  6. On the Labile Memory Buffer in the Attentional Blink: Masking the T2 Representation by Onset Transients Mediates the AB

    ERIC Educational Resources Information Center

    Jannati, Ali; Spalek, Thomas M.; Di Lollo, Vincent

    2011-01-01

    Report of a second target (T2) is impaired when presented within 500 ms of the first (T1). This attentional blink (AB) is known to cause a delay in T2 processing during which T2 must be stored in a labile memory buffer. We explored the buffer's characteristics using different types of masks after T2. These characteristics were inferred by…

  7. A Longitudinal Study of Emotion Regulation, Emotion Lability-Negativity, and Internalizing Symptomatology in Maltreated and Nonmaltreated Children

    ERIC Educational Resources Information Center

    Kim-Spoon, Jungmeen; Cicchetti, Dante; Rogosch, Fred A.

    2013-01-01

    The longitudinal contributions of emotion regulation and emotion lability-negativity to internalizing symptomatology were examined in a low-income sample (171 maltreated and 151 nonmaltreated children, from age 7 to 10 years). Latent difference score models indicated that for both maltreated and nonmaltreated children, emotion regulation was a…

  8. Thermal Analysis of Labile Trace Elements in CM and CV Carbonaceous Chondrites Using Inductively Coupled Plasma-Mass Spectrometry

    NASA Technical Reports Server (NTRS)

    Lauretta, D. S.; Klaue, B.; Blum, J. D.; Buseck, P. R.

    2001-01-01

    We developed a technique to measure the thermal release profiles of a suite of labile elements (Zn, As, Se, Cd, In, Sn, Sb, Te, Pt, Hg, Au, Tl, Pb, Bi). Conclusions are reached about the behavior of each element during parent-body alteration. Additional information is contained in the original extended abstract.

  9. Toxins and antimicrobial peptides: Interactions with membranes

    PubMed Central

    Schlamadinger, Diana E.; Gable, Jonathan E.; Kim, Judy E.

    2014-01-01

    The innate immunity to pathogenic invasion of organisms in the plant and animal kingdoms relies upon cationic antimicrobial peptides (AMPs) as the first line of defense. In addition to these natural peptide antibiotics, similar cationic peptides, such as the bee venom toxin melittin, act as nonspecific toxins. Molecular details of AMP and peptide toxin action are not known, but the universal function of these peptides to disrupt cell membranes of pathogenic bacteria (AMPs) or a diverse set of eukaryotes and prokaryotes (melittin) is widely accepted. Here, we have utilized spectroscopic techniques to elucidate peptide-membrane interactions of alpha-helical human and mouse AMPs of the cathelicidin family as well as the peptide toxin melittin. The activity of these natural peptides and their engineered analogs was studied on eukaryotic and prokaryotic membrane mimics consisting of <200-nm bilayer vesicles composed of anionic and neutral lipids as well as cholesterol. Vesicle disruption, or peptide potency, was monitored with a sensitive fluorescence leakage assay. Detailed molecular information on peptide-membrane interactions and peptide structure was further gained through vibrational spectroscopy combined with circular dichroism. Finally, steady-state fluorescence experiments yielded insight into the local environment of native or engineered tryptophan residues in melittin and human cathelicidin embedded in bilayer vesicles. Collectively, our results provide clues to the functional structures of the engineered and toxic peptides and may impact the design of synthetic antibiotic peptides that can be used against the growing number of antibiotic-resistant pathogens. PMID:25593677

  10. Okadaic Acid: More than a Diarrheic Toxin

    PubMed Central

    Valdiglesias, Vanessa; Prego-Faraldo, María Verónica; Pásaro, Eduardo; Méndez, Josefina; Laffon, Blanca

    2013-01-01

    Okadaic acid (OA) is one of the most frequent and worldwide distributed marine toxins. It is easily accumulated by shellfish, mainly bivalve mollusks and fish, and, subsequently, can be consumed by humans causing alimentary intoxications. OA is the main representative diarrheic shellfish poisoning (DSP) toxin and its ingestion induces gastrointestinal symptoms, although it is not considered lethal. At the molecular level, OA is a specific inhibitor of several types of serine/threonine protein phosphatases and a tumor promoter in animal carcinogenesis experiments. In the last few decades, the potential toxic effects of OA, beyond its role as a DSP toxin, have been investigated in a number of studies. Alterations in DNA and cellular components, as well as effects on immune and nervous system, and even on embryonic development, have been increasingly reported. In this manuscript, results from all these studies are compiled and reviewed to clarify the role of this toxin not only as a DSP inductor but also as cause of alterations at the cellular and molecular levels, and to highlight the relevance of biomonitoring its effects on human health. Despite further investigations are required to elucidate OA mechanisms of action, toxicokinetics, and harmful effects, there are enough evidences illustrating its toxicity, not related to DSP induction, and, consequently, supporting a revision of the current regulation on OA levels in food. PMID:24184795

  11. Insecticidal toxins from black widow spider venom

    PubMed Central

    Rohou, A.; Nield, J.; Ushkaryov, Y.A.

    2007-01-01

    The biological effects of Latrodectus spider venom are similar in animals from different phyla, but these symptoms are caused by distinct phylum-specific neurotoxins (collectively called latrotoxins) with molecular masses ranging from 110 to 140 kDa. To date, the venom has been found to contain five insecticidal toxins, termed ?, ?, ?, ? and ?-latroinsectotoxins (LITs). There is also a vertebrate-specific neurotoxin, ?-latrotoxin (?-LTX), and one toxin affecting crustaceans, ?-latrocrustatoxin (?-LCT). These toxins stimulate massive release of neurotransmitters from nerve terminals and act (1) by binding to specific receptors, some of which mediate an exocytotic signal, and (2) by inserting themselves into the membrane and forming ion-permeable pores. Specific receptors for LITs have yet to be identified, but all three classes of vertebrate receptors known to bind ?-LTX are also present in insects. All LTXs whose structures have been elucidated (?-LIT, ?-LIT, ?-LTX and ?-LCT) are highly homologous and have a similar domain architecture, which consists of a unique N-terminal sequence and a large domain composed of 13–22 ankyrin repeats. Three-dimensional (3D) structure analysis, so far done for ?-LTX only, has revealed its dimeric nature and an ability to form symmetrical tetramers, a feature probably common to all LTXs. Only tetramers have been observed to insert into membranes and form pores. A preliminary 3D reconstruction of a ?-LIT monomer demonstrates the spatial similarity of this toxin to the monomer of ?-LTX. PMID:17210168

  12. THE TRICHOTHECENE TRIANGLE: TOXINS, GENES AND POPULATIONS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fusarium trichothecenes have been classified based on structural properties. Type A and Type B trichothecenes differ in their A ring oxygenation pattern. Type A trichothecenes have a C-8 hydroxyl (neosolaniol), C-8 ester (T-2 toxin) or no C-8 substitution (diacetoxyscirpenol) and Type B trichothec...

  13. Toxins and antimicrobial peptides: interactions with membranes

    NASA Astrophysics Data System (ADS)

    Schlamadinger, Diana E.; Gable, Jonathan E.; Kim, Judy E.

    2009-08-01

    The innate immunity to pathogenic invasion of organisms in the plant and animal kingdoms relies upon cationic antimicrobial peptides (AMPs) as the first line of defense. In addition to these natural peptide antibiotics, similar cationic peptides, such as the bee venom toxin melittin, act as nonspecific toxins. Molecular details of AMP and peptide toxin action are not known, but the universal function of these peptides to disrupt cell membranes of pathogenic bacteria (AMPs) or a diverse set of eukaryotes and prokaryotes (melittin) is widely accepted. Here, we have utilized spectroscopic techniques to elucidate peptide-membrane interactions of alpha-helical human and mouse AMPs of the cathelicidin family as well as the peptide toxin melittin. The activity of these natural peptides and their engineered analogs was studied on eukaryotic and prokaryotic membrane mimics consisting of <200-nm bilayer vesicles composed of anionic and neutral lipids as well as cholesterol. Vesicle disruption, or peptide potency, was monitored with a sensitive fluorescence leakage assay. Detailed molecular information on peptidemembrane interactions and peptide structure was further gained through vibrational spectroscopy combined with circular dichroism. Finally, steady-state fluorescence experiments yielded insight into the local environment of native or engineered tryptophan residues in melittin and human cathelicidin embedded in bilayer vesicles. Collectively, our results provide clues to the functional structures of the engineered and toxic peptides and may impact the design of synthetic antibiotic peptides that can be used against the growing number of antibiotic-resistant pathogens.

  14. Toxins of molds from decaying tomato fruit.

    PubMed Central

    Harwig, J; Scott, P M; Stoltz, D R; Blanchfield, B J

    1979-01-01

    Among 27 mold isolates from decaying tomatoes, culture filtrates or ethyl acetate extracts of 8 isolates grown in yeast extract-sucrose medium were markedly toxic (mortality, greater than 50%) to brine shrimp larvae. The toxicity of six of these isolates could be attributed to the presence of citrinin, tenuazonic acid, or T-2 toxin. Ethyl acetate extracts of five Alternaria isolates and one Fusarium isolate were mutagenic for Salmonella typhimurium strains. In ripe tomatoes inoculated with toxin-producing isolates and incubated at 25 degrees C, one Alternaria alternata isolate produced tenuazonic acid in seven of seven tomatoes at levels of up to 106 micrograms/g and alternariol methyl ether in one of the seven tomatoes at 0.8 microgram/g. Another A. alternata isolate produced tenuazonic acid or alternariol methyl ether at much lower levels in only three of seven tomatoes. Patulin and citrinin were produced by a Penicillium expansum isolate at levels of up to 8.4 and 0.76 microgram/g, respectively. In tomatoes incubated at 15 degrees C, a Fusarium sulphureum isolate produced T-2 toxin, HT-2 toxin, and neosolaniol at levels of up to 37.5, 37.8 and 5.6 micrograms/g, respectively. If these mycotoxins are thermostable, they may occur at detectable levels in tomato products whenever partially moldy tomatoes are used as raw material. PMID:391152

  15. Pasteurella multocida Toxin Manipulates T Cell Differentiation

    PubMed Central

    Hildebrand, Dagmar; Heeg, Klaus; Kubatzky, Katharina F.

    2015-01-01

    Pasteurella multocida causes various diseases in a broad range of wild and domestic animals. Toxigenic strains of the serotypes A and D produce an AB protein toxin named Pasteurella multocida toxin (PMT). PMT constitutively activates the heterotrimeric G protein subunits G?q, G?13, and G?i through deamidation of a glutamine residue, which results in cytoskeletal rearrangements as well as increased proliferation and survival of the host cell. In human monocytes, PMT alters the lipopolysaccharide (LPS)-induced activation toward a phenotype that suppresses T cell activation. Here we describe that the toxin also modulates CD4-positive T helper (Th) cells directly. PMT amplifies the expansion of Th cells through enhanced cell cycle progression and suppression of apoptosis and manipulates the differentiation of Th subclasses through activation of Signal Transducers and Activators of Transcription (STAT) family members and induction of subtype-specific master transcription factors. A large population of toxin-treated T cells is double-positive for Foxp3 and ROR?t, the transcription factors expressed by Treg and Th17 cells, respectively. This suggests that these cells could have the potential to turn into Th17 cells or suppressive Treg cells. However, in terms of function, the PMT-differentiated cells behave as inflammatory Th17 cells that produce IL-17 and trigger T cell proliferation. PMID:26635744

  16. Host specific toxins; effectors of necrotrophic pathogenicity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Host-specific toxins are defined as pathogen effectors that induce toxicity and promote disease only in the host species and only in cultivars of that host, and with few exceptions, expressing a specific dominant susceptibility gene. They are a feature of a small but well studied group of fungal pl...

  17. (-)-Botryodiplodin, A Unique Ribose Analog Toxin

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Many toxins owe their mechanisms of action to being structural analogs of essential metabolites, messengers or structural components. Examples range from tubo-curare to penicillin. Ribose plays a unique role in the metabolism of living organisms, whether prokaryotes or eukaryotes. It and its deri...

  18. Mutant with diphtheria toxin receptor and acidification function but defective in entry of toxin

    SciTech Connect

    Kohno, Kenji ); Hayes, H.; Mekada, Eisuke ); Uchida, Tsuyoshi Osaka Univ. )

    1987-09-01

    A mutant of Chinese hamster ovary cells, GE1, that is highly resistant to diphtheria toxin was isolated. The mutant contains 50% ADP-ribosylatable elongation factor 2, but its protein synthesis was not inhibited by the toxin even at concentrations above 100 {mu}g/ml. {sup 125}I-labeled diphtheria toxin was associated with GE1 cells as well as with the parent cells but did not block protein synthesis of GE1 cells even when the cells were exposed to low pH in the presence or absence of NH{sub 4}Cl. The infections of GE1 cells and the parent cells by vesicular stomatitis virus were similar. GE1 cells were cross-resistant to Pseudomonas aeruginosa exotoxin A and so were about 1,000 times more resistant to this toxin than the parent cells. Hybrids of GE1 cells and the parent cells or mutant cells lacking a functional receptor were more sensitive to diphtheria toxin than GE1 cells. These results suggest that entry of diphtheria toxin into cells requires a cellular factor(s) in addition to those involved in receptor function and acidification of endosomes and that GE1 cells do not express this cellular factor. This character is recessive in GE1 cells.

  19. Higher cytotoxicity of divalent antibody-toxins than monovalent antibody-toxins

    SciTech Connect

    Won, JaeSeon; Nam, PilWon; Lee, YongChan; Choe, MuHyeon

    2009-04-24

    Recombinant antibody-toxins are constructed via the fusion of a 'carcinoma-specific' antibody fragment to a toxin. Due to the high affinity and high selectivity of the antibody fragments, antibody-toxins can bind to surface antigens on cancer cells and kill them without harming normal cells [L.H. Pai, J.K. Batra, D.J. FitzGerald, M.C. Willingham, I. Pastan, Anti-tumor activities of immunotoxins made of monoclonal antibody B3 and various forms of Pseudomonas exotoxin, Proc. Natl. Acad. Sci. USA 88 (1991) 3358-3362]. In this study, we constructed the antibody-toxin, Fab-SWn-PE38, with SWn (n = 3, 6, 9) sequences containing n-time repeated (G{sub 4}S) between the Fab fragment and PE38 (38 kDa truncated form of Pseudomonas exotoxin A). The SWn sequence also harbored one cysteine residue that could form a disulfide bridge between two Fab-SWn-PE38 monomers. We assessed the cytotoxicity of the monovalent (Fab-SWn-PE38), and divalent ([Fab-SWn-PE38]{sub 2}) antibody-toxins. The cytotoxicity of the dimer against the CRL1739 cell line was approximately 18.8-fold higher than that of the monomer on the ng/ml scale, which was approximately 37.6-fold higher on the pM scale. These results strongly indicate that divalency provides higher cytotoxicity for an antibody-toxin.

  20. Bacillus anthracis Lethal Toxin Reduces Human Alveolar Epithelial Barrier Function

    PubMed Central

    Langer, Marybeth; Duggan, Elizabeth Stewart; Booth, John Leland; Patel, Vineet Indrajit; Zander, Ryan A.; Silasi-Mansat, Robert; Ramani, Vijay; Veres, Tibor Zoltan; Prenzler, Frauke; Sewald, Katherina; Williams, Daniel M.; Coggeshall, Kenneth Mark; Awasthi, Shanjana; Lupu, Florea; Burian, Dennis; Ballard, Jimmy Dale; Braun, Armin

    2012-01-01

    The lung is the site of entry for Bacillus anthracis in inhalation anthrax, the deadliest form of the disease. Bacillus anthracis produces virulence toxins required for disease. Alveolar macrophages were considered the primary target of the Bacillus anthracis virulence factor lethal toxin because lethal toxin inhibits mouse macrophages through cleavage of MEK signaling pathway components, but we have reported that human alveolar macrophages are not a target of lethal toxin. Our current results suggest that, unlike human alveolar macrophages, the cells lining the respiratory units of the lung, alveolar epithelial cells, are a target of lethal toxin in humans. Alveolar epithelial cells expressed lethal toxin receptor protein, bound the protective antigen component of lethal toxin, and were subject to lethal-toxin-induced cleavage of multiple MEKs. These findings suggest that human alveolar epithelial cells are a target of Bacillus anthracis lethal toxin. Further, no reduction in alveolar epithelial cell viability was observed, but lethal toxin caused actin rearrangement and impaired desmosome formation, consistent with impaired barrier function as well as reduced surfactant production. Therefore, by compromising epithelial barrier function, lethal toxin may play a role in the pathogenesis of inhalation anthrax by facilitating the dissemination of Bacillus anthracis from the lung in early disease and promoting edema in late stages of the illness. PMID:23027535

  1. Acid-labile sulfides in shallow marine bottom sediments: A review of the impact on ecosystems in the Azov Sea, the NE Black Sea shelf and NW Adriatic lagoons

    NASA Astrophysics Data System (ADS)

    Sorokin, Yu. I.; Zakuskina, O. Yu

    2012-02-01

    Acid-labile sulfides (LS) increase in bottom sediments at sites in the Azov Sea, at the NE Black Sea shelf and in the coastal lagoons of NW Adriatic Sea experiencing direct impacts of anthropogenic pollution. Fresh anthropogenic organic matter stimulates the bacterial sulfate reduction and here the rate of the LS production overcomes their loss during the oxidation and pyritization. This results in the expansion of reduced sediment layer up to the bottom surface. The LS concentration in the reduced sediments varies between 300 and 2000 mg S l -1 of wet silt depending on the size of pollution loading and on the rate of sedimentation. In the oxidized sediments away from the direct pollution impact, the LS concentration did not exceed 100-150 mg S l -1. Being a strong cytochrome toxin, the LS adversely affect the coastal ecosystems. The concentrations over 600 mg S l -1 result in quasi total benthic mortality whereas >300-400 mg S l -1 depletes the benthic faunal abundance and taxonomic diversity. Accumulation of the LS in sediments also induces nocturnal hypoxia and stimulates domination of toxic cyanobacteria in the pelagic phytocenoses.

  2. Type II toxin/antitoxin MqsR/MqsA controls type V toxin/antitoxin GhoT/GhoS

    E-print Network

    Wood, Thomas K.

    Type II toxin/antitoxin MqsR/MqsA controls type V toxin/antitoxin GhoT/GhoS Xiaoxue Wang,1 ** Dana, University Park, PA, USA. Summary Toxin endoribonucleases of toxin/antitoxin (TA) systems regulate protein demonstrate that toxin MqsR of the MqsR/MqsA system enriches toxin ghoT mRNA in vivo and in vitro, since

  3. Bacterial RTX Toxins Allow Acute ATP Release from Human Erythrocytes Directly through the Toxin Pore*

    PubMed Central

    Skals, Marianne; Bjaelde, Randi G.; Reinholdt, Jesper; Poulsen, Knud; Vad, Brian S.; Otzen, Daniel E.; Leipziger, Jens; Praetorius, Helle A.

    2014-01-01

    ATP is as an extracellular signaling molecule able to amplify the cell lysis inflicted by certain bacterial toxins including the two RTX toxins ?-hemolysin (HlyA) from Escherichia coli and leukotoxin A (LtxA) from Aggregatibacter actinomycetemcomitans. Inhibition of P2X receptors completely blocks the RTX toxin-induced hemolysis over a larger concentration range. It is, however, at present not known how the ATP that provides the amplification is released from the attacked cells. Here we show that both HlyA and LtxA trigger acute release of ATP from human erythrocytes that preceded and were not caused by cell lysis. This early ATP release did not occur via previously described ATP-release pathways in the erythrocyte. Both HlyA and LtxA were capable of triggering ATP release in the presence of the pannexin 1 blockers carbenoxolone and probenecid, and the HlyA-induced ATP release was found to be similar in erythrocytes from pannexin 1 wild type and knock-out mice. Moreover, the voltage-dependent anion channel antagonist TRO19622 had no effect on ATP release by either of the toxins. Finally, we showed that both HlyA and LtxA were able to release ATP from ATP-loaded lipid (1-palmitoyl-2-oleoyl-phosphatidylcholine) vesicles devoid of any erythrocyte channels or transporters. Again we were able to show that this happened in a non-lytic fashion, using calcein-containing vesicles as controls. These data show that both toxins incorporate into lipid vesicles and allow ATP to be released. We suggest that both toxins cause acute ATP release by letting ATP pass the toxin pores in both human erythrocytes and artificial membranes. PMID:24860098

  4. Ultrafast photochemistry of polyatomic molecules containing labile halogen atoms in solution

    NASA Astrophysics Data System (ADS)

    Mereshchenko, Andrey S.

    Because breaking and making of chemical bonds lies at the heart of chemistry, this thesis focuses on dynamic studies of labile molecules in solutions using ultrafast transient absorption spectroscopy. Specifically, my interest is two-fold: (i) novel reaction intermediates of polyhalogenated carbon, boron and phosphorus compounds; (ii) photophysics and photochemistry of labile copper(II) halide complexes. Excitation of CH2Br2, CHBr3, BBr 3, and PBr3 into n(Br)sigma*(X-Br) states, where X=C, B, or P, leads to direct photoisomerization with formation of isomers having Br-Br bonds as well as rupture of one of X-Br bonds with the formation of a Br atom and a polyatomic radical fragment, which subsequently recombine to form similar isomer products. Nonpolar solvation stabilizes the isomers, consistent with intrinsic reaction coordinate calculations of the isomer ground state potential energy surfaces at the density functional level of theory, and consequently, the involvement of these highly energetic species on chemically-relevant time scales needs to be taken into account. Monochlorocomplexes in methanol solutions promoted to the ligand-to-metal charge transfer (LMCT) excited state predominantly undergo internal conversion via back electron transfer, giving rise to vibrationally hot ground-state parent complexes. Copper-chloride homolitical bond dissociation yielding the solvated copper(I) and Cl- atom/solvent CT complexes constitutes a minor pathway. Insights into ligand substitution mechanisms were acquired by monitoring the recovery of monochloro complexes at the expense of two unexcited dichloro- and unsubstituted forms of Cu(II) complexes also present in the solution. Detailed description of ultrafast excited-state dynamics of CuCl 42- complexes in acetonitrile upon excitation into all possible Ligand Field (LF) excited states and two most intense LMCT transitions is reported. The LF states were found to be nonreactive with lifetimes remarkably longer than those for copper(II) complexes studied so far, in particular, copper blue proteins. The highest 2A1 and lowest 2E LF states relax directly to the ground electronic state whereas the intermediate 2B1 LF state relaxes stepwise through the 2E state. The LMCT excited states are short-lived undergoing either ionic dissociation (CuCl3- + Cl-) or cascading relaxation through the manifold of vibrationally hot LF states to the ground state.

  5. Development and fabrication of heat-sterilizable inhalation therapy equipment

    NASA Technical Reports Server (NTRS)

    Irons, A. S.

    1974-01-01

    The development of a completely heat sterilizable intermittent positive pressure breathing (IPPB) ventilator in an effort to reduce the number of hospital acquired infections is reported. After appropriate changes in materials and design were made, six prototype units were fabricated and were successfully field tested in local hospitals. Most components of the modified ventilators are compatible with existing machines. In all but a few instances, such as installation of bacteria-retentive filters and a modified venturi, the change over from non-heat-sterilizable to sterilizable units was accomplished by replacement of heat labile materials with heat stable materials.

  6. Sea Anemone (Cnidaria, Anthozoa, Actiniaria) Toxins: An Overview

    PubMed Central

    Frazão, Bárbara; Vasconcelos, Vitor; Antunes, Agostinho

    2012-01-01

    The Cnidaria phylum includes organisms that are among the most venomous animals. The Anthozoa class includes sea anemones, hard corals, soft corals and sea pens. The composition of cnidarian venoms is not known in detail, but they appear to contain a variety of compounds. Currently around 250 of those compounds have been identified (peptides, proteins, enzymes and proteinase inhibitors) and non-proteinaceous substances (purines, quaternary ammonium compounds, biogenic amines and betaines), but very few genes encoding toxins were described and only a few related protein three-dimensional structures are available. Toxins are used for prey acquisition, but also to deter potential predators (with neurotoxicity and cardiotoxicity effects) and even to fight territorial disputes. Cnidaria toxins have been identified on the nematocysts located on the tentacles, acrorhagi and acontia, and in the mucous coat that covers the animal body. Sea anemone toxins comprise mainly proteins and peptides that are cytolytic or neurotoxic with its potency varying with the structure and site of action and are efficient in targeting different animals, such as insects, crustaceans and vertebrates. Sea anemones toxins include voltage-gated Na+ and K+ channels toxins, acid-sensing ion channel toxins, Cytolysins, toxins with Kunitz-type protease inhibitors activity and toxins with Phospholipase A2 activity. In this review we assessed the phylogentic relationships of sea anemone toxins, characterized such toxins, the genes encoding them and the toxins three-dimensional structures, further providing a state-of-the-art description of the procedures involved in the isolation and purification of bioactive toxins. PMID:23015776

  7. Autopsy findings in botulinum toxin poisoning.

    PubMed

    Devers, Kelly G; Nine, Jeffrey S

    2010-11-01

    In the United States, foodborne botulism is most commonly associated with home-canned food products. Between 1950 and 2005, 405 separate outbreaks of botulism were reported to the Centers for Disease Control and Prevention (CDC). Approximately 8% of these outbreaks were attributed to commercially produced canned food products. Overall, 5-10% of persons ingesting botulinum toxin die. Few reports exist pertaining to autopsy findings in cases of foodborne botulism. Here, we report the autopsy findings of a man who died after a prolonged illness caused by botulinum toxin exposure likely attributable to a commercially prepared food source. Despite extensive testing, our histopathologic findings were nonspecific. We therefore conclude that the forensic pathologist must become familiar with the neurotoxicity syndrome associated with this illness. Maintaining vigilance for botulism by carefully reviewing the decedent's clinical history will aid in the early identification and control of outbreaks, either foodborne or terrorism-related. PMID:20533981

  8. Toxins for transgenic resistance to hemipteran pests.

    PubMed

    Chougule, Nanasaheb P; Bonning, Bryony C

    2012-06-01

    The sap sucking insects (Hemiptera), which include aphids, whiteflies, plant bugs and stink bugs, have emerged as major agricultural pests. The Hemiptera cause direct damage by feeding on crops, and in some cases indirect damage by transmission of plant viruses. Current management relies almost exclusively on application of classical chemical insecticides. While the development of transgenic crops expressing toxins derived from the bacterium Bacillus thuringiensis (Bt) has provided effective plant protection against some insect pests, Bt toxins exhibit little toxicity against sap sucking insects. Indeed, the pest status of some Hemiptera on Bt-transgenic plants has increased in the absence of pesticide application. The increased pest status of numerous hemipteran species, combined with increased prevalence of resistance to chemical insecticides, provides impetus for the development of biologically based, alternative management strategies. Here, we provide an overview of approaches toward transgenic resistance to hemipteran pests. PMID:22822455

  9. DGT measurement in low flow conditions: diffusive boundary layer and lability considerations.

    PubMed

    Uher, Emmanuelle; Tusseau-Vuillemin, Marie-Hélène; Gourlay-France, Catherine

    2013-07-01

    Recent papers have alerted the scientific community that a diffusive boundary layer (DBL) forming in front of diffusive gradients in thin film (DGT) devices when they are immersed in water might have a significant impact on the results and have suggested a method to assess the DBL. This paper aims at evaluating to what extent the DBL impacts the results of metal measurement in water by DGT and providing new information on the dissociation kinetics of metal complexes in wastewater by using DBL calculation. A careful study of the influence of the water velocity on the measurement with DGTs equipped with restricted gels is presented. Deployments took place in the laboratory with a range of stirring speeds (0-400 rpm) and in a canal receiving treated wastewater with increasing controlled water velocity (0.07-3 cm s(-1)). Even under extreme low flow conditions, the error made in using the equation that does not take into account that the DBL was lower than the analytical error. Nevertheless, the DBL is the seat of dissociation of complexes and increases the lability window beyond the steric constraints of the hydrogel. The capacity of restricted gels to only sample inorganic species under these conditions is questioned. This study also is an opportunity to provide information on metal-ligand interactions in wastewater by creating the kinetic signature of the wastewater. Unlike previous studies which used different types of water, Pb was the more limited metal and interacted strongly with the ligands. PMID:23722876

  10. ADHD Symptom Rebound and Emotional Lability With Lisdexamfetamine Dimesylate in Children Aged 6 to 12 Years.

    PubMed

    López, Frank A; Childress, Ann; Adeyi, Ben; Dirks, Bryan; Babcock, Thomas; Scheckner, Brian; Lasser, Robert; Shepski, John; Arnold, Valerie

    2013-02-13

    Objective: To describe symptom rebound in children with ADHD treated with lisdexamfetamine dimesylate (LDX) or placebo. Method: During a 4-week, randomized, double-blind, placebo-controlled trial of LDX, parents/caregivers completed the Conners' Parent Rating Scale-Revised: Short Form symptom rating scale throughout the day. Response, rebound, and emotional lability (EL) were assessed post hoc based on predefined criteria. Results: Most participants given LDX (n = 207) were responders throughout the day (50.7%-55.6%) versus placebo (n = 72; 11.1%-22.2%). A total of seven (3.4%) LDX participants showed rebound in the afternoon and/or evening versus seven (9.7%) with placebo. In both groups, most incidences of rebound occurred in the evening. EL (mean) was higher in LDX rebounders and nonresponders (range = 4.2-9.0) versus LDX responders (range = 1.3-1.6) and versus placebo rebounders (range = 0.7-1.9). Conclusion: ADHD symptom rebound occurred in few participants (3.3%) given LDX (accompanied by clinically significant EL). Overall, more participants given LDX versus placebo responded throughout the day. (J. of Att. Dis. 2012; XX(X) 1-XX). PMID:23407278

  11. Stabilized liquid membrane device (SLMD) for the passive, integrative sampling of labile metals in water

    USGS Publications Warehouse

    Brumbaugh, W.G.; Petty, J.D.; Huckins, J.N.; Manahan, S.E.

    2002-01-01

    A stabilized liquid membrane device (SLMD) is described for potential use as an in situ, passive, integrative sampler for cadmium (Cd), cobalt (Co), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn) in natural waters. The SLMD (patent pending) consists of a 2.5-cm-wide by 15-cm-long strip of low-density polyethylene (LDPE) layflat tubing containing 1 mL of an equal mixture (v/v) of oleic acid (cis-9-octadecenoic acid) and EMO-8Q (7-[4-ethyl-1-methyloctyl]-8-quinolinol). The reagent mixture continuously diffuses to the exterior surface of the LDPE membrane, and provides for sequestration of several divalent metals for up to several weeks. Depending on sampler configuration, concentration factors of several thousand can be realized for these metal ions after just a few days. In addition to in situ deployment, the SLMD may be useful for laboratory determination of labile metal species in grab samples. Methods for minimizing the effects of water flow on the sampling rate are currently under investigation.

  12. Utilizing the lability of lead selenide to produce heterostructured nanocrystals with bright, stable infrared emission.

    PubMed

    Pietryga, Jeffrey M; Werder, Donald J; Williams, Darrick J; Casson, Joanna L; Schaller, Richard D; Klimov, Victor I; Hollingsworth, Jennifer A

    2008-04-01

    Infrared-emitting nanocrystal quantum dots (NQDs) have enormous potential as an enabling technology for applications ranging from tunable infrared lasers to biological labels. Notably, lead chalcogenide NQDs, especially PbSe NQDs, provide efficient emission over a large spectral range in the infrared, but their application has been limited by instability in emission quantum yield and peak position on exposure to ambient conditions. Conventional methods for improving NQD stability by applying a shell of a more stable, wider band gap semiconductor material are frustrated by the tendency of lead chalcogenide NQDs toward Ostwald ripening at even moderate reaction temperatures. Here, we describe a partial cation-exchange method in which we take advantage of this lability to controllably synthesize PbSe/CdSe core/shell NQDs. Critically, these NQDs are stable against fading and spectral shifting. Further, these NQDs can undergo additional shell growth to produce PbSe/CdSe/ZnS core/shell/shell NQDs that represent initial steps toward bright, biocompatible near-infrared optical labels. PMID:18341344

  13. Dissolved organic carbon lability and stable isotope shifts during microbial decomposition in a tropical river system

    NASA Astrophysics Data System (ADS)

    Geeraert, N.; Omengo, F. O.; Govers, G.; Bouillon, S.

    2015-08-01

    A significant amount of carbon is transported to the ocean as dissolved organic carbon (DOC) in rivers. During transport, it can be transformed through microbial consumption and photochemical oxidation. In dark incubation experiments with water from the Tana River, Kenya, we examined the consumption of DOC through microbial decomposition and the associated change in its carbon stable isotope composition (?13C). In 15 of the 18 incubations, DOC concentrations decreased significantly by 10 to 60 %, with most of the decomposition taking place within the first 24-48 h. After 8 days, the remaining DOC was up to 3 ‰ more depleted in 13C compared with the initial pool, and the change in ?13C correlated strongly with the fraction of DOC remaining. We propose that the shift in ?13C is consistent with greater microbial lability of DOC originating from herbaceous C4 vegetation than DOC derived from woody C3 vegetation in the semi-arid lower Tana. The findings complement earlier data that riverine C sources do not necessarily reflect their proportion in the catchment: besides spatial distribution, also processing within the river can further influence the riverine ?13C.

  14. Nitric oxide is necessary for labilization of a consolidated context memory during reconsolidation in terrestrial snails.

    PubMed

    Balaban, Pavel M; Roshchin, Matvey; Timoshenko, Alia K; Gainutdinov, Khalil L; Bogodvid, Tatiana K; Muranova, Lyudmila N; Zuzina, Alena B; Korshunova, Tatiana A

    2014-09-01

    Nitric oxide (NO) is known to be involved in associative memory formation. We investigated the influence of blocking NO function on the reconsolidation of context memory in terrestrial snails (Helix lucorum L.). After a 10 day session of electric shocks in one context only, context memory in snails was observed in test sessions as the significant difference of amplitudes of withdrawal responses to tactile stimuli in two different contexts. After a 1 day rest, a session of 'reminding' was performed, preceded by injection in different groups of the snails with either vehicle or combination of the protein synthesis blocker anisomycin (ANI) with one of the following drugs: the NO scavenger carboxy-PTIO, the NO-synthase inhibitors N-omega-nitro-L-arginin, nitroindazole and NG-nitro-L-arginine methyl ester hydrochloride, or the NO donor S-nitroso-N-acetyl-DL-penicillamine. Testing the context memory at different time intervals after the reminder under ANI injection showed that the context memory was impaired at 24 h and later, whereas the reminder under combined injection of ANI and each of the NO-synthase inhibitors used or the NO scavenger showed no impairment of long-term context memory. Injection of the NO donor S-nitroso-N-acetyl-DL-penicillamine with or without reminder had no effect on context memory. The results obtained demonstrated that NO is necessary for labilization of a consolidated context memory. PMID:24910164

  15. Membrane Transport Behavior and the Lability of Chloride on Polyphosphazenes Bearing Bulky Substituents

    SciTech Connect

    Frederick F. Stewart; John R. Klaehn; Christopher J. Orme

    2007-08-01

    Polyphosphazenes are an intriguing class of inorganic polymers where much of their functionality is derived from pendant groups attached to phosphorus. The backbone of the polymer consists of alternating phosphorus and nitrogen atoms where the bonding is conventionally drawn as alternating double and single bonds. Orbital nodes are located at each phosphorus atom resulting in electron delocalization between phosphorus atoms, but not through them. Thus, the polymer backbone has a high degree of flexibility where halogens or other leaving groups can be effectively displaced with nucleophiles. In this paper, the first known example of a polyphosphazene with large quantities of non-labile chloride substituents induced by neighboring group steric effects will be discussed. This example is the result of the substitution of poly[bis-chlorophosphazene] with the sodium salt of 3,5-di-tert-butylphenol where only 60% of the chlorines were displaced. This contrasts with the 100% substitution observed with other phenols (phenol, 4-tert-butylphenol, 3-methylphenol, etc.).

  16. Sample storage-induced changes in the quantity and quality of soil labile organic carbon

    PubMed Central

    Sun, Shou-Qin; Cai, Hui-Ying; Chang, Scott X.; Bhatti, Jagtar S.

    2015-01-01

    Effects of sample storage methods on the quantity and quality of labile soil organic carbon are not fully understood even though their effects on basic soil properties have been extensively studied. We studied the effects of air-drying and frozen storage on cold and hot water soluble organic carbon (WSOC). Cold- and hot-WSOC in air-dried and frozen-stored soils were linearly correlated with those in fresh soils, indicating that storage proportionally altered the extractability of soil organic carbon. Air-drying but not frozen storage increased the concentrations of cold-WSOC and carbohydrate in cold-WSOC, while both increased polyphenol concentrations. In contrast, only polyphenol concentration in hot-WSOC was increased by air-drying and frozen storage, suggesting that hot-WSOC was less affected by sample storage. The biodegradability of cold- but not hot-WSOC was increased by air-drying, while both air-drying and frozen storage increased humification index and changed specific UV absorbance of both cold- and hot-WSOC, indicating shifts in the quality of soil WSOC. Our results suggest that storage methods affect the quantity and quality of WSOC but not comparisons between samples, frozen storage is better than air-drying if samples have to be stored, and storage should be avoided whenever possible when studying the quantity and quality of both cold- and hot-WSOC. PMID:26617054

  17. Conformational Switching and Nanoscale Assembly of Human Prion Protein into Polymorphic Amyloids via Structurally Labile Oligomers.

    PubMed

    Dalal, Vijit; Arya, Shruti; Bhattacharya, Mily; Mukhopadhyay, Samrat

    2015-12-29

    Conformational switching of the prion protein (PrP) from an ?-helical normal cellular form (PrP(C)) to an aggregation-prone and self-propagating ?-rich scrapie form (PrP(Sc)) underlies the molecular basis of pathogenesis in prion diseases. Anionic lipids play a critical role in the misfolding and conformational conversion of the membrane-anchored PrP into the amyloidogenic pathological form. In this work, we have used a diverse array of techniques to interrogate the early intermediates during amyloid formation from recombinant human PrP in the presence of a membrane mimetic anionic detergent such as sodium dodecyl sulfate. We have been able to detect and characterize two distinct types of interconvertible oligomers. Our results demonstrate that highly ordered large ?-oligomers represent benign off-pathway intermediates that lack the ability to mature into amyloid fibrils. On the contrary, structurally labile small oligomers are capable of switching to an ordered amyloid-state that exhibits profound toxicity to mammalian cells. Our fluorescence resonance energy transfer measurements revealed that the partially disordered PrP serves as precursors to small amyloid-competent oligomers. These on-pathway oligomers are eventually sequestered into higher order supramolecular assemblies that conformationally mature into polymorphic amyloids possessing varied nanoscale morphology as evident by the atomic force microscopy imaging. The nanoscale diversity of fibril architecture is attributed to the heterogeneous ensemble of early obligatory oligomers and offers a plausible explanation for the existence of multiple prion strains in vivo. PMID:26645611

  18. An intermetallic Au24Ag20 superatom nanocluster stabilized by labile ligands.

    PubMed

    Wang, Yu; Su, Haifeng; Xu, Chaofa; Li, Gang; Gell, Lars; Lin, Shuichao; Tang, Zichao; Häkkinen, Hannu; Zheng, Nanfeng

    2015-04-01

    An intermetallic nanocluster containing 44 metal atoms, Au24Ag20(2-SPy)4(PhC?C)20Cl2, was successfully synthesized and structurally characterized by single-crystal analysis and density funtional theory computations. The 44 metal atoms in the cluster are arranged as a concentric three-shell Au12@Ag20@Au12 Keplerate structure having a high symmetry. For the first time, the co-presence of three different types of anionic ligands (i.e., phenylalkynyl, 2-pyridylthiolate, and chloride) was revealed on the surface of metal nanoclusters. Similar to thiolates, alkynyls bind linearly to surface Au atoms using their ?-bonds, leading to the formation of two types of surface staple units (PhC?C-Au-L, L = PhC?C(-) or 2-pyridylthiolate) on the cluster. The co-presence of three different surface ligands allows the site-specific surface and functional modification of the cluster. The lability of PhC?C(-) ligands on the cluster was demonstrated, making it possible to keep the metal core intact while removing partial surface capping. Moreover, it was found that ligand exchange on the cluster occurs easily to offer various derivatives with the same metal core but different surface functionality and thus different solubility. PMID:25803406

  19. Labile Zn ions on octacalcium phosphate-derived Zn-containing hydroxyapatite surfaces

    NASA Astrophysics Data System (ADS)

    Honda, Yoshitomo; Anada, Takahisa; Morimoto, Shinji; Suzuki, Osamu

    2013-05-01

    We previously synthesized and characterized zinc-containing octacalcium phosphate (OCP) and its hydrolyzed Ca-deficient hydroxyapatite (HA). In the present report, we attempted to define the state of Zn in the OCP-derived Zn-calcium phosphates (CaPs) in relation to the presence of specific amino acids. Zn-containing OCPs were prepared in solutions that included Zn ions up to a concentration of 3.5 mM, and their hydrolyzates [hydrolyzed (hy)-Zn-CaP] were obtained in hot water. The materials were characterized by x-ray diffraction and scanning electron microscopy. The concentration of Ca and Zn ions at room temperature was determined by analyzing the supernatant after incubating the materials in ?-minimal essential medium (?-MEM) and HEPES buffer including cysteine, histidine, lysine, aspartic acid, and glutamic acid. Zn ions were more dissolved in ?-MEM than HEPES buffer in the absence of amino acids. The inclusion of the amino acids enhanced Zn dissolution by several hundred fold, even in HEPES buffer. Among the amino acids, both cysteine and histidine enhanced the release of Zn. The effect was particularly remarkable with cysteine even in the presence of the other amino acids tested. These results indicate that Zn ions are present as a surface labile pool, which tends to be preferentially desorbed by cysteine, a ubiquitous molecule present in serum.

  20. Assessing the labile arsenic pool in contaminated paddy soils by isotopic dilution techniques and simple extractions.

    PubMed

    Stroud, Jacqueline L; Khan, M Asaduzzman; Norton, Gareth J; Islam, M Rafiqul; Dasgupta, Tapash; Zhu, Yong-Guan; Price, Adam H; Meharg, Andrew A; McGrath, Steve P; Zhao, Fang-Jie

    2011-05-15

    Arsenic (As) contamination of paddy soils threatens rice cultivation and the health of populations relying on rice as a staple crop. In the present study, isotopic dilution techniques were used to determine the chemically labile (E value) and phytoavailable (L value) pools of As in a range of paddy soils from Bangladesh, India, and China and two arable soils from the UK varying in the degree and sources of As contamination. The E value accounted for 6.2-21.4% of the total As, suggesting that a large proportion of soil As is chemically nonlabile. L values measured with rice grown under anaerobic conditions were generally larger than those under aerobic conditions, indicating increased potentially phytoavailable pool of As in flooded soils. In an incubation study, As was mobilized into soil pore water mainly as arsenite under flooded conditions, with Bangladeshi soils contaminated by irrigation of groundwater showing a greater potential of As mobilization than other soils. Arsenic mobilization was best predicted by phosphate-extractable As in the soils. PMID:21504212

  1. Shiga toxin-producing Escherichia coli

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In United States, it is estimated that non-O157 Shiga toxin-producing Escherichia coli (STEC) cause more illnesses than STEC O157:H7, and the majority of cases of non-O157 STEC infections is due to serogroups O26, O45, O103, O111, O121, and O145, referred to as the top six non-O157 STEC. The diseas...

  2. 7 CFR 331.10 - Restricting access to select agents and toxins; security risk assessments.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 5 2013-01-01 2013-01-01 false Restricting access to select agents and toxins... TRANSFER OF SELECT AGENTS AND TOXINS § 331.10 Restricting access to select agents and toxins; security risk... access to a select agent or toxin, and an individual may not access a select agent or toxin, unless...

  3. 7 CFR 331.10 - Restricting access to select agents and toxins; security risk assessments.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 5 2010-01-01 2010-01-01 false Restricting access to select agents and toxins... TRANSFER OF SELECT AGENTS AND TOXINS § 331.10 Restricting access to select agents and toxins; security risk... access to a select agent or toxin, and an individual may not access a select agent or toxin, unless...

  4. 7 CFR 331.10 - Restricting access to select agents and toxins; security risk assessments.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 5 2012-01-01 2012-01-01 false Restricting access to select agents and toxins... TRANSFER OF SELECT AGENTS AND TOXINS § 331.10 Restricting access to select agents and toxins; security risk... access to a select agent or toxin, and an individual may not access a select agent or toxin, unless...

  5. 7 CFR 331.10 - Restricting access to select agents and toxins; security risk assessments.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 5 2014-01-01 2014-01-01 false Restricting access to select agents and toxins... TRANSFER OF SELECT AGENTS AND TOXINS § 331.10 Restricting access to select agents and toxins; security risk... access to a select agent or toxin, and an individual may not access a select agent or toxin, unless...

  6. 7 CFR 331.10 - Restricting access to select agents and toxins; security risk assessments.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 5 2011-01-01 2011-01-01 false Restricting access to select agents and toxins... TRANSFER OF SELECT AGENTS AND TOXINS § 331.10 Restricting access to select agents and toxins; security risk... access to a select agent or toxin, and an individual may not access a select agent or toxin, unless...

  7. Three controversial issues in extracorporeal toxin removal.

    PubMed

    Feinfeld, Donald A; Rosenberg, Jeffrey W; Winchester, James F

    2006-01-01

    The optimal method of extracorporeal removal of many toxic compounds is often a matter of debate. Due to the lack of well-designed studies, we are often left with circumstantial evidence, and we must exercise our best clinical judgment as to whether extracorporeal drug removal is beneficial and if so, by what method. It is clear, however, that rapidity in toxin removal is beneficial. We present three issues dealing with extracorporeal removal of toxins for which there is no definitive answer but which may arise in clinical practice. The first is whether continuous renal replacement therapy (CRRT) is better at removing dialyzable toxins than classic hemodialysis. The second is whether charcoal hemoperfusion is at all useful in treating paraquat poisoning. Finally, is any modality of extracorporeal treatment useful in the treatment of amatoxin poisoning? After a thorough literature review, it is evident that definitive answers are not strikingly apparent. However, extracorporeal treatment in the latter two instances may have potential benefit and may be the only hope for patient survival. Due to the urgent nature of treatment for poisoning, as well as the somewhat obscure nature of these issues, there may never be well-designed evidence-based studies to help guide us. In the meantime, we must continue to use less than ideal evidence and our own experience in dealing with these controversial issues to guide our decision-making process. PMID:16970731

  8. Perfringolysin O: The Underrated Clostridium perfringens Toxin?

    PubMed

    Verherstraeten, Stefanie; Goossens, Evy; Valgaeren, Bonnie; Pardon, Bart; Timbermont, Leen; Haesebrouck, Freddy; Ducatelle, Richard; Deprez, Piet; Wade, Kristin R; Tweten, Rodney; Van Immerseel, Filip

    2015-05-01

    The anaerobic bacterium Clostridium perfringens expresses multiple toxins that promote disease development in both humans and animals. One such toxin is perfringolysin O (PFO, classically referred to as ? toxin), a pore-forming cholesterol-dependent cytolysin (CDC). PFO is secreted as a water-soluble monomer that recognizes and binds membranes via cholesterol. Membrane-bound monomers undergo structural changes that culminate in the formation of an oligomerized prepore complex on the membrane surface. The prepore then undergoes conversion into the bilayer-spanning pore measuring approximately 250-300 Å in diameter. PFO is expressed in nearly all identified C. perfringens strains and harbors interesting traits that suggest a potential undefined role for PFO in disease development. Research has demonstrated a role for PFO in gas gangrene progression and bovine necrohemorrhagic enteritis, but there is limited data available to determine if PFO also functions in additional disease presentations caused by C. perfringens. This review summarizes the known structural and functional characteristics of PFO, while highlighting recent insights into the potential contributions of PFO to disease pathogenesis. PMID:26008232

  9. Perfringolysin O: The Underrated Clostridium perfringens Toxin?

    PubMed Central

    Verherstraeten, Stefanie; Goossens, Evy; Valgaeren, Bonnie; Pardon, Bart; Timbermont, Leen; Haesebrouck, Freddy; Ducatelle, Richard; Deprez, Piet; Wade, Kristin R.; Tweten, Rodney; Van Immerseel, Filip

    2015-01-01

    The anaerobic bacterium Clostridium perfringens expresses multiple toxins that promote disease development in both humans and animals. One such toxin is perfringolysin O (PFO, classically referred to as ? toxin), a pore-forming cholesterol-dependent cytolysin (CDC). PFO is secreted as a water-soluble monomer that recognizes and binds membranes via cholesterol. Membrane-bound monomers undergo structural changes that culminate in the formation of an oligomerized prepore complex on the membrane surface. The prepore then undergoes conversion into the bilayer-spanning pore measuring approximately 250–300 Å in diameter. PFO is expressed in nearly all identified C. perfringens strains and harbors interesting traits that suggest a potential undefined role for PFO in disease development. Research has demonstrated a role for PFO in gas gangrene progression and bovine necrohemorrhagic enteritis, but there is limited data available to determine if PFO also functions in additional disease presentations caused by C. perfringens. This review summarizes the known structural and functional characteristics of PFO, while highlighting recent insights into the potential contributions of PFO to disease pathogenesis. PMID:26008232

  10. Toxin content, phallotoxin and amatoxin composition of Amanita phalloides tissues.

    PubMed

    Enjalbert, F; Gallion, C; Jehl, F; Monteil, H

    1993-06-01

    The toxin content and composition of Amanita phalloides tissues were determined in three specimens at two carpophore development stages. The carpophore was subdivided into six parts, namely, the cap, gills, ring, stipe, volva and bulb. To our knowledge, this is the first report of such an investigation on the ring and the bulb. Substantial differences in the tissue toxin content were revealed. The ring displayed a very high amount of toxins, whereas the bulb had the lowest toxin content. Compositional differences in relation to the nature of the tissue were also noted. The highest amatoxin content was found in the ring, gills and cap, whereas the bulb and volva were the richest in phallotoxins. Furthermore, variability in the toxin composition was observed. The differences in the distribution of individual toxins in the tissues might be related to the carpophore developmental stage. PMID:8342178

  11. Fold modulating function: bacterial toxins to functional amyloids

    PubMed Central

    Syed, Adnan K.; Boles, Blaise R.

    2014-01-01

    Many bacteria produce cytolytic toxins that target host cells or other competing microbes. It is well known that environmental factors control toxin expression, however, recent work suggests that some bacteria manipulate the fold of these protein toxins to control their function. The ?-sheet rich amyloid fold is a highly stable ordered aggregate that many toxins form in response to specific environmental conditions. When in the amyloid state, toxins become inert, losing the cytolytic activity they display in the soluble form. Emerging evidence suggest that some amyloids function as toxin storage systems until they are again needed, while other bacteria utilize amyloids as a structural matrix component of biofilms. This amyloid matrix component facilitates resistance to biofilm disruptive challenges. The bacterial amyloids discussed in this review reveal an elegant system where changes in protein fold and solubility dictate the function of proteins in response to the environment. PMID:25136340

  12. Simplified purification method for Clostridium botulinum type E toxin.

    PubMed Central

    Giménez, J A; Sugiyama, H

    1987-01-01

    Clostridium botulinum type E toxin was purified in three chromatography steps. Toxin extracted from cells was concentrated by precipitation and dissolving in a small volume of citrate buffer. When the extract was chromatographed on DEAE-Sephadex without RNase or protamine treatment, the first protein peak had most of the toxin but little nucleic acid. When the toxic pool was applied to a carboxymethyl Sepharose column, toxin was recovered in the first protein peak in its bimolecular complex form. The final chromatography step at 4 degrees C on a DEAE-Sephacel column at a slightly alkaline pH purified the toxin (Mr, 145,000) by separating the nontoxic protein from the complex. At least 1.5 mg of pure toxin was obtained from each liter of culture, and the toxicity was 6 X 10(7) 50% lethal doses per mg of protein. These values are significantly higher than those previously reported. Images PMID:3435146

  13. Shiga Toxin: Expression, Distribution, and Its Role in the Environment

    PubMed Central

    Mauro, Steven A.; Koudelka, Gerald B.

    2011-01-01

    In this review, we highlight recent work that has increased our understanding of the production and distribution of Shiga toxin in the environment. Specifically, we review studies that offer an expanded view of environmental reservoirs for Shiga toxin producing microbes in terrestrial and aquatic ecosystems. We then relate the abundance of Shiga toxin in the environment to work that demonstrates that the genetic mechanisms underlying the production of Shiga toxin genes are modified and embellished beyond the classical microbial gene regulatory paradigms in a manner that apparently “fine tunes” the trigger to modulate the amount of toxin produced. Last, we highlight several recent studies examining microbe/protist interactions that postulate an answer to the outstanding question of why microbes might harbor and express Shiga toxin genes in the environment. PMID:22069728

  14. On-demand combinational delivery of curcumin and doxorubicin via a pH-labile micellar nanocarrier.

    PubMed

    Li, Haoyu; Li, Man; Chen, Chao; Fan, Aiping; Kong, Deling; Wang, Zheng; Zhao, Yanjun

    2015-11-10

    The combinational delivery of doxorubicin and curcumin in a physically loaded nanocarrier offers the benefits of enhanced therapeutic efficacy and reduced adverse effects, but this strategy often suffers from the slow drug release followed by delayed onset of pharmacological action. This work reported the hydrazone-linked polymer-curcumin conjugate micelles containing physically loaded doxorubicin to address this problem; the ester-linked conjugate micelles were produced as the control. The pH-labile spherical micelles were less than 100 nm with a loading at 9.3±0.5% (w/w, Curcumin) and 2.5±0.1(w/w, Doxorubicin). Both agents were released at a faster rate in the pH-labile micelles compared to the control. The confocal laser scanning microscopy revealed a time-dependent co-localization of both agents in HepG2 cells. The IC50 of pH-labile conjugate micelles without doxorubicin in HepG2 cells was 27.7±5.3 (?M), whereas the co-loaded micelles was lowered to 10.8±3.4 (?M) (Cur-equivalent dose). The combination index calculation demonstrated a synergistic action of both agents in the co-loading nanocarrier. The current work provided an efficient nanocarrier system to achieve rapid on-demand drug release without onset delay of therapeutic action, which might add value to the clinical translation of the combinational delivery systems. PMID:26387617

  15. Microwave-assisted extraction performed in low temperature and in vacuo for the extraction of labile compounds in food samples.

    PubMed

    Xiao, Xiaohua; Song, Wei; Wang, Jiayue; Li, Gongke

    2012-01-27

    In this study, low temperature vacuum microwave-assisted extraction, which simultaneous performed microwave-assisted extraction (MAE) in low temperature and in vacuo environment, was proposed. The influencing parameters including solid/liquid ratio, extraction temperature, extraction time, degree of vacuum and microwave power were discussed. The predominance of low temperature vacuum microwave-assisted extraction was investigated by comparing the extraction yields of vitamin C, ?-carotene, aloin A and astaxanthin in different foods with that in MAE and solvent extraction, and 5.2-243% increments were obtained. On the other hand, the chemical kinetics of vitamin C and aloin A, which composed two different steps including the extraction step of analyte transferred from matrix into solvent and the decomposition step of analyte degraded in the extraction solvent, were proposed. All of the decomposition rates (K(2)) for the selected analyte in low temperature, in vacuo and in nitrogen atmosphere decreased significantly comparing with that in conventional MAE, which are in agreement with that obtained from experiments. Consequently, the present method was successfully applied to extract labile compound from different food samples. These results showed that low temperature and/or in vacuo environment in microwave-assisted extraction system was especially important to prevent the degradation of labile components and have good potential on the extraction of labile compound in foods, pharmaceutical and natural products. PMID:22177069

  16. Visualization of peroxynitrite-induced changes of labile Zn2+ in the endoplasmic reticulum with benzoresorufin-based fluorescent probes.

    PubMed

    Lin, Wei; Buccella, Daniela; Lippard, Stephen J

    2013-09-11

    Zn(2+) plays essential roles in biology, and the homeostasis of Zn(2+) is tightly regulated in all cells. Subcellular distribution and trafficking of labile Zn(2+), and its inter-relation with reactive nitrogen species, are poorly understood due to the scarcity of appropriate imaging tools. We report a new family of red-emitting fluorescent sensors for labile Zn(2+), ZBR1-3, based on a benzoresorufin platform functionalized with dipicolylamine or picolylamine-derived metal binding groups. In combination, the pendant amines and fluorophore afford an [N3O] binding motif that resembles that of previously reported fluorescein-based sensors of the Zinpyr family, reproducing well their binding capabilities and yielding comparable Kd values in the sub-nanomolar and picomolar ranges. The ZBR sensors display up to 8.4-fold emission fluorescence enhancement upon Zn(2+) binding in the cuvette, with similar responses obtained in live cells using standard wide-field fluorescence microscopy imaging. The new sensors localize spontaneously in the endoplasmic reticulum (ER) of various tested cell lines, allowing for organelle-specific monitoring of zinc levels in live cells. Study of ER zinc levels in neural stem cells treated with a peroxynitrite generator, Sin-1, revealed an immediate decrease in labile Zn(2+) thus providing evidence for a direct connection between ER stress and ER Zn(2+) homeostasis. PMID:23902285

  17. CD44 Binding to Hyaluronic Acid Is Redox Regulated by a Labile Disulfide Bond in the Hyaluronic Acid Binding Site

    PubMed Central

    Kellett-Clarke, Helena; Stegmann, Monika; Barclay, A. Neil; Metcalfe, Clive

    2015-01-01

    CD44 is the primary leukocyte cell surface receptor for hyaluronic acid (HA), a component of the extracellular matrix. Enzymatic post translational cleavage of labile disulfide bonds is a mechanism by which proteins are structurally regulated by imparting an allosteric change and altering activity. We have identified one such disulfide bond in CD44 formed by Cys77 and Cys97 that stabilises the HA binding groove. This bond is labile on the surface of leukocytes treated with chemical and enzymatic reducing agents. Analysis of CD44 crystal structures reveal the disulfide bond to be solvent accessible and in the–LH hook configuration characteristic of labile disulfide bonds. Kinetic trapping and binding experiments on CD44-Fc chimeric proteins show the bond is preferentially reduced over the other disulfide bonds in CD44 and reduction inhibits the CD44-HA interaction. Furthermore cells transfected with CD44 no longer adhere to HA coated surfaces after pre-treatment with reducing agents. The implications of CD44 redox regulation are discussed in the context of immune function, disease and therapeutic strategies. PMID:26379032

  18. Hydride in BaTiO2.5H0.5: A Labile Ligand in Solid State Chemistry.

    PubMed

    Masuda, Naoya; Kobayashi, Yoji; Hernandez, Olivier; Bataille, Thierry; Paofai, Serge; Suzuki, Hajime; Ritter, Clemens; Ichijo, Naoki; Noda, Yasuto; Takegoshi, Kiyonori; Tassel, Cédric; Yamamoto, Takafumi; Kageyama, Hiroshi

    2015-12-01

    In synthesizing mixed anion oxides, direct syntheses have often been employed, usually involving high temperature and occasionally high pressure. Compared with these methods, here we show how the use of a titanium perovskite oxyhydride (BaTiO2.5H0.5) as a starting material enables new multistep low temperature topochemical routes to access mixed anion compounds. Similar to labile ligands in inorganic complexes, the lability of H(-) provides the necessary reactivity for syntheses, leading to reactions and products previously difficult to obtain. For example, BaTiO2.5N0.2 can be prepared with the otherwise inert N2 gas at 400-600 °C, in marked contrast with currently available oxynitride synthetic routes. F(-)/H(-) exchange can also be accomplished at 150 °C, yielding the oxyhydride-fluoride BaTi(O, H, F)3. For BaTiO2.4D0.3F0.3, we find evidence that further anionic exchange with OD(-) yields BaTiO2.4(D(-))0.26(OD(-))0.34, which implies stable coexistence of H(+) and H(-) at ambient conditions. Such an arrangement is thermodynamically unstable and would be difficult to realize otherwise. These results show that the labile nature of hydride imparts reactivity to oxide hosts, enabling it to participate in new multistep reactions and form new materials. PMID:26575595

  19. Survey in Vanuatu on enterotoxigenic Escherichia coli in children and infants with and without acute diarrhea.

    PubMed Central

    Germani, Y; Montaville, B; Fauran, C; Brethes, B

    1985-01-01

    We have studied the incidence of enterotoxigenic Escherichia coli (ETEC) strains isolated from infants with and without diarrheal diseases in Vanuatu, South Pacific. Over a period of 5 months we have isolated enterotoxigenic E. coli strains from 29 (26.6%) of 109 children with acute diarrhea and from 13 (21.6%) of 60 children of the control group. In the group with diarrhea, 7 (6.4%) strains released heat-labile toxin, 7 (6.4%) released heat-stable toxin, and 15 (13.7%) produced both heat-labile and heat-stable toxin. In the control group, only one strain (1.6%) produced heat-stable toxin, 12 (20%) produced heat-labile toxin, and none produced both. Association of strains releasing heat-stable toxin or both heat-labile and heat-stable toxin with diarrhea was highly significant as shown by statistical analysis. The O serogroups and colonization factors CFA/I and CFA/II are presented. PMID:3886696

  20. Fusarial toxins: secondary metabolites of Fusarium fungi.

    PubMed

    Nesic, Ksenija; Ivanovic, Snezana; Nesic, Vladimir

    2014-01-01

    Exposure to mycotoxins occurs worldwide, even though there are geographic and climatic differences in the amounts produced and occurrence of these substances.Mycotoxins are secondary chemical metabolites of different fungi. They are natural contaminants of cereals, so their presence is often inevitable. Among many genera that produce mycotoxins, Fusarium fungi are the most widespread in cereal-growing areas of the planet. Fusarium fungi produce a diversity of mycotoxin types, whose distributions are also diverse. What is produced and where it is produced is influenced primarily by environmental conditions, and crop production and storage methods. The amount of toxin produced depends on physical (viz., moisture, relative humidity, temperature, and mechanical damage), chemical (viz., carbon dioxide,oxygen, composition of substrate, insecticides and fungicides), and biological factors (viz., plant variety, stress, insects, spore load, etc.). Moisture and temperature have a major influence on mold growth rate and mycotoxin production.Among the most toxic and prevalent fusaria) toxins are the following: zearalenone,fumonisins, moniliformin and trichothecenes (T-2/HT-2 toxin, deoxynivalenol,diacetoxyscirpenol, nivalenol). Zearalenone (ZEA; ZON, F-2 toxin) isaphy to estrogenic compound, primarily a field contaminant, which exhibits estrogenic activity and has been implicated in numerous mycotoxicoses of farm animals,especially pigs. Recently, evidence suggests that ZEA has potential to stimulate the growth of human breast cancer cells. Fumonisins are also cancer-promoting metabolites,of which Fumonisin 8 I (FBI) is the most important. Moniliformin (MON) isalso highly toxic to both animals and humans. Trichothecenes are classified as gastrointestinal toxins, dermatotoxins, immunotoxins, hematotoxins, and gene toxins.T-2 and HT-2 toxin, and diacetoxyscirpenol (DAS, anguidine) are the most toxic mycotoxins among the trichothecene group. Deoxynivalenol (DON, vomitoxin) and nivalenol although less toxic are important because they frequently occur at levels high enough to cause adverse effects.The presence of mycotoxins in the animal diet can produce significant production losses. Any considerable presence of mycotoxins, in major dietary components,confirms the need to adopt a continuous prevention and control program. Such programs are usually based on several common approaches to minimize mycotoxin contamination in the food chain. Major strategies include preventing fungal growth and therefore mycotoxin formation, reducing or eliminating mycotoxins from contaminated feedstuffs, or diverting contaminated products to low risk uses. Because of the complexity of their chemical structures, mycotoxins also present a major analytical challenge. They are also found in a vast array of feed matrices. Analysis is essential for determining the extent of mycotoxin contamination, for risk analysis, confirming the diagnosis of a mycotoxicosis and for monitoring mycotoxin mitigation strategies.For the future, adequately controlling the mycotoxin problem in the livestock economy will depend on implementing appropriate agricultural management policies,as well as augmenting production and storage systems and analysis methods.Only such policies offer the opportunity to bring solid and long-lasting economical results to the livestock industry that is afflicted with the mycotoxin problem. PMID:24162094

  1. Visualization of Peroxynitrite-Induced Changes of Labile Zn[superscript 2+] in the Endoplasmic Reticulum with Benzoresorufin-based Fluorescent Probes

    E-print Network

    Lin, Wei

    Zn[superscript 2+] plays essential roles in biology, and the homeostasis of Zn[superscript 2+] is tightly regulated in all cells. Subcellular distribution and trafficking of labile Zn[superscript 2+], and its inter-relation ...

  2. 42 CFR 73.4 - Overlap select agents and toxins.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...*; Hendra virus; Nipah virus; Rift Valley fever virus; Venezuelan equine encephalitis virus (c) Genetic... select agents or nonfunctional overlap toxins. (3) Any subtypes of Venezuelan equine encephalitis...

  3. 42 CFR 73.4 - Overlap select agents and toxins.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...*; Hendra virus; Nipah virus; Rift Valley fever virus; Venezuelan equine encephalitis virus (c) Genetic... select agents or nonfunctional overlap toxins. (3) Any subtypes of Venezuelan equine encephalitis...

  4. Mtx toxins from Lysinibacillus sphaericus enhance mosquitocidal cry-toxin activity and suppress cry-resistance in Culex quinquefasciatus.

    PubMed

    Wirth, Margaret C; Berry, Colin; Walton, William E; Federici, Brian A

    2014-01-01

    The interaction of Mtx toxins from Lysinibacillus sphaericus (formerly Bacillus sphaericus) with Bacillus thuringiensis subsp. israelensis Cry toxins and the influence of such interactions on Cry-resistance were evaluated in susceptible and Cry-resistant Culex quinquefasciatus larvae. Mtx-1 and Mtx-2 were observed to be active against both susceptible and resistant mosquitoes; however varying levels of cross-resistance toward Mtx toxins were observed in the resistant mosquitoes. A 1:1 mixture of either Mtx-1 or Mtx-2 with different Cry toxins generally showed moderate synergism, but some combinations were highly toxic to resistant larvae and suppressed resistance. Toxin synergy has been demonstrated to be a powerful tool for enhancing activity and managing Cry-resistance in mosquitoes, thus Mtx toxins may be useful as components of engineered bacterial larvicides. PMID:24144574

  5. Clostridium perfringens Epsilon Toxin Causes Selective Death of Mature Oligodendrocytes and Central Nervous System Demyelination

    PubMed Central

    Linden, Jennifer R.; Ma, Yinghua; Zhao, Baohua; Harris, Jason Michael; Rumah, Kareem Rashid; Schaeren-Wiemers, Nicole

    2015-01-01

    ABSTRACT Clostridium perfringens epsilon toxin (?-toxin) is responsible for a devastating multifocal central nervous system (CNS) white matter disease in ruminant animals. The mechanism by which ?-toxin causes white matter damage is poorly understood. In this study, we sought to determine the molecular and cellular mechanisms by which ?-toxin causes pathological changes to white matter. In primary CNS cultures, ?-toxin binds to and kills oligodendrocytes but not astrocytes, microglia, or neurons. In cerebellar organotypic culture, ?-toxin induces demyelination, which occurs in a time- and dose-dependent manner, while preserving neurons, astrocytes, and microglia. ?-Toxin specificity for oligodendrocytes was confirmed using enriched glial culture. Sensitivity to ?-toxin is developmentally regulated, as only mature oligodendrocytes are susceptible to ?-toxin; oligodendrocyte progenitor cells are not. ?-Toxin sensitivity is also dependent on oligodendrocyte expression of the proteolipid myelin and lymphocyte protein (MAL), as MAL-deficient oligodendrocytes are insensitive to ?-toxin. In addition, ?-toxin binding to white matter follows the spatial and temporal pattern of MAL expression. A neutralizing antibody against ?-toxin inhibits oligodendrocyte death and demyelination. This study provides several novel insights into the action of ?-toxin in the CNS. (i) ?-Toxin causes selective oligodendrocyte death while preserving all other neural elements. (ii) ?-Toxin-mediated oligodendrocyte death is a cell autonomous effect. (iii) The effects of ?-toxin on the oligodendrocyte lineage are restricted to mature oligodendrocytes. (iv) Expression of the developmentally regulated proteolipid MAL is required for the cytotoxic effects. (v) The cytotoxic effects of ?-toxin can be abrogated by an ?-toxin neutralizing antibody. PMID:26081637

  6. Acute Toxin Registration All biological toxins with a mammalian LD50 of 100g/kg body weight, as well as the organisms (both natural and

    E-print Network

    Slatton, Clint

    Acute Toxin Registration All biological toxins with a mammalian LD50 of 100µg/kg body weight, as well as the organisms (both natural and recombinant) which produce these toxins must be registered with the Biosafety Office. Examples of some biological toxins which require registration can be found on our website

  7. Toxin GhoT of the GhoT/GhoS toxin/antitoxin system damages the cell membrane to reduce adenosine

    E-print Network

    Wood, Thomas K.

    Toxin GhoT of the GhoT/GhoS toxin/antitoxin system damages the cell membrane to reduce adenosine of Biology, Texas A & M University, College Station, TX 77843, USA. Summary Toxin/antitoxin (TA) systems there is little evidence to support this hypothesis. Escherichia coli GhoT/GhoS is a TA system in which toxin Gho

  8. 1 OHSU IBC Toxin Fact Sheet 3/11/2014 Biological toxins are toxic substances that can be produced by bacteria, fungi, protozoa, insects,

    E-print Network

    Chapman, Michael S.

    1 OHSU IBC Toxin Fact Sheet 3/11/2014 i Biological toxins are toxic substances that can be produced by bacteria, fungi, protozoa, insects, animals, or plants and are classified separately from chemical toxins provides guidance safety precautions for work with biological toxins and policies and regulations that may

  9. 77 FR 42195 - Viruses, Serums, Toxins, and Analogous Products; Exemptions From Preparation Pursuant to an...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-18

    ...establishments in violation of the Virus-Serum-Toxin Act. The effect...provisions implementing the Virus-Serum-Toxin Act (the Act...manufacturing facility (unlicensed vaccine manufacturing establishment...barter, exchange, or ship any virus, serum, toxin, or...

  10. 75 FR 39437 - Optimizing the Security of Biological Select Agents and Toxins in the United States

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-08

    ...Optimizing the Security of Biological Select Agents and Toxins in the United States...Optimizing the Security of Biological Select Agents and Toxins in the United States...scientific enterprise that utilizes biological select agents and toxins (BSAT) is...

  11. The Father, Son and Cholix Toxin: The Third Member of the DT Group Mono-ADP-Ribosyltransferase Toxin Family

    PubMed Central

    Lugo, Miguel R.; Merrill, A. Rod

    2015-01-01

    The cholix toxin gene (chxA) was first identified in V. cholerae strains in 2007, and the protein was identified by bioinformatics analysis in 2008. It was identified as the third member of the diphtheria toxin group of mono-ADP-ribosyltransferase toxins along with P. aeruginosa exotoxin A and C. diphtheriae diphtheria toxin. Our group determined the structure of the full-length, three-domain cholix toxin at 2.1 Å and its C-terminal catalytic domain (cholixc) at 1.25 Å resolution. We showed that cholix toxin is specific for elongation factor 2 (diphthamide residue), similar to exotoxin A and diphtheria toxin. Cholix toxin possesses molecular features required for infection of eukaryotes by receptor-mediated endocytosis, translocation to the host cytoplasm and inhibition of protein synthesis. More recently, we also solved the structure of full-length cholix toxin in complex with NAD+ and proposed a new kinetic model for cholix enzyme activity. In addition, we have taken a computational approach that revealed some important properties of the NAD+-binding pocket at the residue level, including the role of crystallographic water molecules in the NAD+ substrate interaction. We developed a pharmacophore model of cholix toxin, which revealed a cationic feature in the side chain of cholix toxin active-site inhibitors that may determine the active pose. Notably, several recent reports have been published on the role of cholix toxin as a major virulence factor in V. cholerae (non-O1/O139 strains). Additionally, FitzGerald and coworkers prepared an immunotoxin constructed from domains II and III as a cancer treatment strategy to complement successful immunotoxins derived from P. aeruginosa exotoxin A. PMID:26213968

  12. Labile sleep promotes awareness of abstract knowledge in a serial reaction time task

    PubMed Central

    Kirov, Roumen; Kolev, Vasil; Verleger, Rolf; Yordanova, Juliana

    2015-01-01

    Sleep has been identified as a critical brain state enhancing the probability of gaining insight into covert task regularities. Both non-rapid eye movement (NREM) and rapid eye movement (REM) sleep have been implicated with o?ine re-activation and reorganization of memories supporting explicit knowledge generation. According to two-stage models of sleep function, o?ine processing of information during sleep is sequential requiring multiple cycles of NREM and REM sleep stages. However, the role of overnight dynamic sleep macrostructure for insightfulness has not been studied so far. In the present study, we test the hypothesis that the frequency of interactions between NREM and REM sleep stages might be critical for awareness after sleep. For that aim, the rate of sleep stage transitions was evaluated in 53 participants who learned implicitly a serial reaction time task (SRTT) in which a determined sequence was inserted. The amount of explicit knowledge about the sequence was established by verbal recall after a night of sleep following SRTT learning. Polysomnography was recorded in this night and in a control night before and was analyzed to compare the rate of sleep-stage transitions between participants who did or did not gain awareness of task regularity after sleep. Indeed, individual ability of explicit knowledge generation was strongly associated with increased rate of transitions between NREM and REM sleep stages and between light sleep stages and slow wave sleep. However, the rate of NREM–REM transitions specifically predicted the amount of explicit knowledge after sleep in a trait-dependent way. These results demonstrate that enhanced lability of sleep goes along with individual ability of knowledge awareness. Observations suggest that facilitated dynamic interactions between sleep stages, particularly between NREM and REM sleep stages play a role for o?ine processing which promotes rule extraction and awareness. PMID:26441730

  13. [Effects of understory removal on soil labile organic carbon pool in a Cinnamomum camphora plantation].

    PubMed

    Wu, Ya-Cong; Li, Zheng-Cai; Cheng, Cai-Fang; Liu, Rong-Jie; Wang, Bin; Geri, Le-Tu

    2013-12-01

    Taking a 48-year-old Cinnamomum camphora plantation in the eastern area of our subtropics as test object, this paper studied the labile organic carbon contents and their ratios to the total organic carbon (TOC) in 0-60 cm soil layer under effects of understory removal (UR). As compared with no understory removal (CK), the soil TOC and easily-oxidized carbon (EOC) contents under UR decreased, with a decrement of 4.8% - 34.1% and 27.1% - 36.2%, respectively, and the TOC and EOC contents had a significant difference in 0-10 cm and 0-20 cm layers, respectively. The water-soluble organic carbon (WSOC) (except in 0-10 cm and 10-20 cm layers) and light fraction organic matter (LFOM) under UR increaesd, but the difference was not significant. The ratio of soil WSOC to soil TOC in UR stand was higher than that in CK stand, while the ratio of soil EOC to soil TOC showed an opposite trend. In the two stands, soil WSOC, EOC, and LFOM had significant or extremely significant correlations with soil TOC, and the correlation coefficients of soil EOC and LFOM with soil TOC were higher in UR stand than in CK, but the correlation coefficient between soil WSOC and TOC was in opposite. The soil EOC, LFOM, and TOC in the two stands were significantly or extremely significantly correlated with soil nutrients, but the soil WSOC in UR stand had no significant correlations with soil hydrolyzable N, available P, exchangeable Ca, and exchangeable Mg. PMID:24697049

  14. Kinetics characterization of c-Src binding to lipid membranes: Switching from labile to persistent binding.

    PubMed

    Le Roux, Anabel-Lise; Busquets, Maria Antònia; Sagués, Francesc; Pons, Miquel

    2016-02-01

    Cell signaling by the c-Src proto-oncogen requires the attachment of the protein to the inner side of the plasma membrane through the myristoylated N-terminal region, known as the SH4 domain. Additional binding regions of lower affinity are located in the neighbor intrinsically disordered Unique domain and the structured SH3 domain. Here we present a surface plasmon resonance study of the binding of a myristoylated protein including the SH4, Unique and SH3 domains of c-Src to immobilized liposomes. Two distinct binding processes were observed: a fast and a slow one. The second process lead to a persistently bound form (PB) with a slower binding and a much slower dissociation rate than the first one. The association and dissociation of the PB form could be detected using an anti-SH4 antibody. The kinetic analysis revealed that binding of the PB form follows a second order rate law suggesting that it involves the formation of c-Src dimers on the membrane surface. A kinetically equivalent PB form is observed in a myristoylated peptide containing only the SH4 domain but not in a construct including the three domains but with a 12-carbon lauroyl substituent instead of the 14-carbon myristoyl group. The PB form is observed with neutral lipids but its population increases when the immobilized liposomes contain negatively charged lipids. We suggest that the PB form may represent the active signaling form of c-Src while the labile form provides the capacity for fast 2D search of the target signaling site on the membrane surface. PMID:26638178

  15. [Impact of Land Utilization Pattern on Distributing Characters of Labile Organic Carbon in Soil Aggregates in Jinyun Mountain].

    PubMed

    Li, Rui; Jiang, Chang-sheng; Hao, Qing-ju

    2015-09-01

    Four land utilization patterns were selected for this study in Jinyun mountain, including subtropical evergreen broad-leaved forest (abbreviation: forest), sloping farmland, orchard and abandoned land. Soil samples were taken every 10 cm in the depth of 60 cm soil and proportions of large macroaggregates (> 2 mm), small macroaggregates (0. 25-2 mm), microaggregates (0. 053 - 0. 25 mm) and silt + clay (<0. 053 mm) were obtained by wet sieving method to measure the content of organic carbon and labile organic carbon in each aggregate fraction and analyze impacts of land uses on organic carbon and labile organic carbon of soil aggregates. LOC content of four soil aggregates were significantly reduced with the increase of soil depth; in layers of 0-60 cm soil depth, our results showed that LOC contents of forest and abandoned land were higher than orchard and sloping farmland. Reserves of labile organic carbon were estimated by the same soil quality, it revealed that forest (3. 68 Mg.hm-2) > abandoned land (1. 73 Mg.hm-2) > orchard (1. 43 Mg.hm-2) >sloping farmland (0.54 Mg.hm-2) in large macroaggregates, abandoned land (7.77, 5. 01 Mg.hm-2) > forest (4. 96, 2.71 Mg.hm-2) > orchard (3. 33, 21. 10 Mg.hm-2) > sloping farmland (1. 68, 1. 35 Mg.hm-2) in small macroaggregates and microaggregates, and abandoned land(4. 32 Mg.hm-2) > orchard(4. 00 Mg.hm-2) > forest(3. 22 Mg.hm-2) > sloping farmland (2.37 Mg.hm-2) in silt + clay, forest and abandoned land were higher than orchard and sloping farmland in other three soil aggregates except silt + clay. It was observed that the level of organic carbon and labile organic carbon were decreased when bringing forest under cultivation to orchard or farmland, and augments on organic carbon and labile organic carbon were found after exchanging farmland to abandoned land. The most reverses of forest and abandoned land emerged in small macroaggregates, orchard and sloping farmland were in microaggregates. That was, during the transformations of land utilization pattern, soil aggregates with bigger size were easier to accumulate or lose labile organic carbon. Allocation ratios of labile organic carbon to soil organic carbon under four land uses were decreased as the soil depth added. Allocation ratios of orchard and sloping farmland were a bit higher than forest and abandoned land, which indicated that organic carbon of forest and abandoned land were more steady and available for soil as a carbon sink, meanwhile, the forest and abandoned land would avoid more CO2 diffusing to the atmosphere from the decomposition of soil organic carbon. PMID:26717707

  16. toxin-mediated insect resistance in plants.

    PubMed

    de Maagd RA; Bosch; Stiekema

    1999-01-01

    We are currently in an interesting phase of plant biotechnology releases, both for the scientists responsible for these innovations who are beginning to see their ideas realized, and for the biotechnology companies that are starting to see a return on their investment. One of the most notable examples, is the introduction of transgenic crops that are engineered to express a Bacillus thuringiensis toxin that confers resistance to insect predation. However, the picture is not altogether positive - there is concern that the introduction of this technology was premature or should not have happened at all, and that the valuable insecticidal properties of Bacillus thuringiensis will be lost. PMID:10234264

  17. Diarrhetic Shellfish Toxins and Other Lipophilic Toxins of Human Health Concern in Washington State

    PubMed Central

    Trainer, Vera L.; Moore, Leslie; Bill, Brian D.; Adams, Nicolaus G.; Harrington, Neil; Borchert, Jerry; da Silva, Denis A. M.; Eberhart, Bich-Thuy L.

    2013-01-01

    The illness of three people in 2011 after their ingestion of mussels collected from Sequim Bay State Park, Washington State, USA, demonstrated the need to monitor diarrhetic shellfish toxins (DSTs) in Washington State for the protection of human health. Following these cases of diarrhetic shellfish poisoning, monitoring for DSTs in Washington State became formalized in 2012, guided by routine monitoring of Dinophysis species by the SoundToxins program in Puget Sound and the Olympic Region Harmful Algal Bloom (ORHAB) partnership on the outer Washington State coast. Here we show that the DSTs at concentrations above the guidance level of 16 ?g okadaic acid (OA) + dinophysistoxins (DTXs)/100 g shellfish tissue were widespread in sentinel mussels throughout Puget Sound in summer 2012 and included harvest closures of California mussel, varnish clam, manila clam and Pacific oyster. Concentrations of toxins in Pacific oyster and manila clam were often at least half those measured in blue mussels at the same site. The primary toxin isomer in shellfish and plankton samples was dinophysistoxin-1 (DTX-1) with D. acuminata as the primary Dinophysis species. Other lipophilic toxins in shellfish were pectenotoxin-2 (PTX-2) and yessotoxin (YTX) with azaspiracid-2 (AZA-2) also measured in phytoplankton samples. Okadaic acid, azaspiracid-1 (AZA-1) and azaspiracid-3 (AZA-3) were all below the levels of detection by liquid chromatography tandem mass spectrometry (LC-MS/MS). A shellfish closure at Ruby Beach, Washington, was the first ever noted on the Washington State Pacific coast due to DSTs. The greater than average Fraser River flow during the summers of 2011 and 2012 may have provided an environment conducive to dinoflagellates and played a role in the prevalence of toxigenic Dinophysis in Puget Sound. PMID:23760013

  18. Effects of heating procedures on deoxynivalenol, nivalenol and zearalenone levels in naturally contaminated barley and wheat.

    PubMed

    Yumbe-Guevara, B E; Imoto, T; Yoshizawa, T

    2003-12-01

    The influence of heating temperature and time on deoxynivalenol (DON), nivalenol (NIV) and zearalenone (ZEA) contents in naturally co-contaminated barley and wheat was investigated intending to establish the basis for a decontamination model of Fusarium mycotoxins in cereals. The standard toxins and whole barley powder samples were heated in a convection oven at 140, 160, 180, 200, or 220 degrees C, and kernel subsamples (200 g each) were roasted in an experimental rotary gas-fired roaster at 150, 180 or 220 degrees C. All treatments resulted in a time-temperature-dependent decomposition of the toxins; the logarithm of the toxin remaining % presented a linear relationship with heating time. The lines equations were used to estimate the half (H) and decimal (D) decomposition times (time required to destroy 50 or 90% of the toxin, respectively). DON and NIV H and D decomposition times were similar and 50% shorter for heated standards than for whole barley powder. ZEA standard values were considerably longer, while whole barley powder values were comparable with those of DON and NIV. At 220 degrees C, D decomposition times of DON, NIV and ZEA heated standards were 11, 10 and 85 min, respectively, while the values obtained in whole barley powder were the same for the three toxins (25 min). The determination of H and D decomposition values constitutes a basis to understand the heating stability nature of each toxin. PMID:14726277

  19. EFFECTS OF SHIGA TOXIN ON ISOLATED PORCINE GRANULOCYTES

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Background: Shiga toxin (Stx) binding to polymorphonuclear leukocytes (PMN) is hypothesized to play a role in the pathogenesis of Shiga toxin-producing Escherichia coli (STEC) disease in humans. Pigs are an excellent model for studying the role of PMN in STEC disease because, like humans, they are ...

  20. IDENTIFICATION OF MICROCYSTIN TOXINS FROM A STRAIN OF MICROCYSTIS AERUGINOSA

    EPA Science Inventory

    Microcystin toxins are cyclic heptapeptides produced by several genera and species of cyanobacteria that are responsible for the "green scum" frequently observed on eutrophic surface waters. These toxins, which are a million times more toxic than cyanide ion, have caused deaths o...

  1. Regulation of toxin gene expression in Clostridium perfringens.

    PubMed

    Ohtani, Kaori; Shimizu, Tohru

    2015-05-01

    The Gram-positive, anaerobic, spore-forming, rod-shaped Clostridium perfringens is widely distributed in nature, especially in soil and the gastrointestinal tract of humans and animals. C. perfringens causes clostridial myonecrosis (or gas gangrene), enteritis and enterotoxemia in humans and livestock by producing numerous extracellular toxins and enzymes. The toxin gene expression is regulated by a two-component regulatory system and regulatory RNA VirR/VirS-VR-RNA cascade. The VirR/VirS system was originally found in a type A strain, but a recent report showed that it is also important for the toxin gene regulation in other types of strains. Two types of cell-cell signaling, i.e., agr-system and AI-2 signaling, are also important for the regulation of toxin genes. Several regulatory systems independent from the VirR/VirS system, including virX, the orphan histidine kinase ReeS and orphan response regulator RevR, are also involved in the regulation of toxin genes. In addition, the expression of toxin genes is upregulated after contact with Caco-2 cells. C. perfringens has a complex regulatory network for toxin gene expression and thus the coordination of toxin gene expression is important for the process of infection. PMID:25303832

  2. ClanTox: a classifier of short animal toxins

    PubMed Central

    Naamati, Guy; Askenazi, Manor; Linial, Michal

    2009-01-01

    Toxins are detected in sporadic species along the evolutionary tree of the animal kingdom. Venomous animals include scorpions, snakes, bees, wasps, frogs and numerous animals living in the sea such as the stonefish, snail, jellyfish, hydra and more. Interestingly, proteins that share a common scaffold with animal toxins also exist in non-venomous species. However, due to their short length and primary sequence diversity, these, toxin-like proteins remain undetected by classical search engines and genome annotation tools. We construct a toxin classification machine and web server called ClanTox (Classifier of Animal Toxins) that is based on the extraction of sequence-driven features from the primary protein sequence followed by the application of a classification system trained on known animal toxins. For a given input list of sequences, from venomous or non-venomous settings, the ClanTox system predicts whether each sequence is toxin-like. ClanTox provides a ranked list of positively predicted candidates according to statistical confidence. For each protein, additional information is presented including the presence of a signal peptide, the number of cysteine residues and the associated functional annotations. ClanTox is a discovery-prediction tool for a relatively overlooked niche of toxin-like cell modulators, many of which are therapeutic agent candidates. The ClanTox web server is freely accessible at http://www.clantox.cs.huji.ac.il. PMID:19429697

  3. Membrane-Binding Mechanism of Clostridium perfringens Alpha-Toxin

    PubMed Central

    Oda, Masataka; Terao, Yutaka; Sakurai, Jun; Nagahama, Masahiro

    2015-01-01

    Clostridium perfringens alpha-toxin is a key mediator of gas gangrene, which is a life-threatening infection that manifests as fever, pain, edema, myonecrosis, and gas production. Alpha-toxin possesses phospholipase C and sphingomyelinase activities. The toxin is composed of an N-terminal domain (1–250 aa, N-domain), which is the catalytic site, and a C-terminal domain (251–370 aa, C-domain), which is the membrane-binding site. Immunization of mice with the C-domain of alpha-toxin prevents the gas gangrene caused by C. perfringens, whereas immunization with the N-domain has no effect. The central loop domain (55–93 aa), especially H….SW84Y85….G, plays an important role in the interaction with ganglioside GM1a. The toxin binds to lipid rafts in the presence of a GM1a/TrkA complex, and metabolites from phosphatidylcholine to diacylglycerol through the enzymatic activity of alpha-toxin itself. These membrane dynamics leads to the activation of endogenous PLC?-1 via TrkA. In addition, treatment with alpha-toxin leads to the formation of diacylglycerol at membrane rafts in ganglioside-deficient DonQ cells; this in turn triggers endocytosis and cell death. This article summarizes the current the membrane-binding mechanism of alpha-toxin in detail. PMID:26633512

  4. T-2 toxin Analysis in Poultry and Cattle Feedstuff

    PubMed Central

    Gholampour Azizi, Issa; Azarmi, Masumeh; Danesh Pouya, Naser; Rouhi, Samaneh

    2014-01-01

    Background: T-2 toxin is a mycotoxin that is produced by the Fusarium fungi. Consumption of food and feed contaminated with T-2 toxin causes diseases in humans and animals. Objectives: In this study T-2 toxin was analyzed in poultry and cattle feedstuff in cities of Mazandaran province (Babol, Sari, Chalus), Northern Iran. Materials and Methods: In this study, 90 samples were analyzed for T-2 toxin contamination by the ELISA method. Results: Out of 60 concentrate and bagasse samples collected from various cities of Mazandaran province, 11.7% and 3.3% were contaminated with T-2 toxin at concentrations > 25 and 50 µg/kg, respectively. For mixed poultry diets, while 10% of the 30 analyzed samples were contaminated with > 25 µg/kg, none of the tested samples contained T-2 toxin at levels > 50 µg/kg. Conclusions: The results obtained from this study show that poultry and cattle feedstuff can be contaminated with different amounts of T-2 toxin in different conditions and locations. Feedstuff that are contaminated by this toxin cause different diseases in animals; thus, potential transfer of mycotoxins to edible by-products from animals fed mycotoxin-contaminated feeds drives the need to routinely monitor mycotoxins in animal feeds and their components. This is the basis on which effective management of mycotoxins and their effects can be implemented. PMID:24872939

  5. Botulinum Toxin in the Treatment of Facial Paralysis.

    PubMed

    Mehdizadeh, Omid B; Diels, Jacqueline; White, William Matthew

    2016-02-01

    This article reviews the current literature supporting the use of botulinum toxin in producing symmetric facial features and reducing unwanted, involuntary movements. Methods, protocols, and adverse events are discussed. Additionally, the authors suggest that using botulinum toxin A therapy in postparalytic facial synkinesis can provide long-term results when used in conjunction with other treatment modalities. PMID:26611697

  6. EFFECT OF MARINE TOXINS ON THERMOREGULATION IN MICE.

    EPA Science Inventory

    Marine algal toxins are extremely toxic and can represent a major health problem to humans and animals. Temperature regulation is one of many processes to be affected by exposure to these toxins. Mice and rats become markedly hypothermic when subjected to acute exposure to the ma...

  7. 9 CFR 121.3 - VS select agents and toxins.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... genetically modified. (d) VS select agents or toxins that meet any of the following criteria are excluded from... AGRICULTURE VIRUSES, SERUMS, TOXINS, AND ANALOGOUS PRODUCTS; ORGANISMS AND VECTORS POSSESSION, USE, AND... recombinant organisms: (1) Nucleic acids that can produce infectious forms of any of the select agent...

  8. 9 CFR 121.3 - VS select agents and toxins.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... and toxins listed in paragraph (b) of this section that have been genetically modified. (d) VS select... AGRICULTURE VIRUSES, SERUMS, TOXINS, AND ANALOGOUS PRODUCTS; ORGANISMS AND VECTORS POSSESSION, USE, AND... synthetic nucleic acids, and recombinant and/or synthetic organisms: (1) Nucleic acids that can...

  9. Short Toxin-like Proteins Abound in Cnidaria Genomes

    PubMed Central

    Tirosh, Yitshak; Linial, Itai; Askenazi, Manor; Linial, Michal

    2012-01-01

    Cnidaria is a rich phylum that includes thousands of marine species. In this study, we focused on Anthozoa and Hydrozoa that are represented by the Nematostella vectensis (Sea anemone) and Hydra magnipapillata genomes. We present a method for ranking the toxin-like candidates from complete proteomes of Cnidaria. Toxin-like functions were revealed using ClanTox, a statistical machine-learning predictor trained on ion channel inhibitors from venomous animals. Fundamental features that were emphasized in training ClanTox include cysteines and their spacing along the sequences. Among the 83,000 proteins derived from Cnidaria representatives, we found 170 candidates that fulfill the properties of toxin-like-proteins, the vast majority of which were previously unrecognized as toxins. An additional 394 short proteins exhibit characteristics of toxin-like proteins at a moderate degree of confidence. Remarkably, only 11% of the predicted toxin-like proteins were previously classified as toxins. Based on our prediction methodology and manual annotation, we inferred functions for over 400 of these proteins. Such functions include protease inhibitors, membrane pore formation, ion channel blockers and metal binding proteins. Many of the proteins belong to small families of paralogs. We conclude that the evolutionary expansion of toxin-like proteins in Cnidaria contributes to their fitness in the complex environment of the aquatic ecosystem. PMID:23202321

  10. Structural interactions of a voltage sensor toxin with lipid membranes

    PubMed Central

    Mihailescu, Mihaela; Krepkiy, Dmitriy; Milescu, Mirela; Gawrisch, Klaus; Swartz, Kenton J.; White, Stephen

    2014-01-01

    Protein toxins from tarantula venom alter the activity of diverse ion channel proteins, including voltage, stretch, and ligand-activated cation channels. Although tarantula toxins have been shown to partition into membranes, and the membrane is thought to play an important role in their activity, the structural interactions between these toxins and lipid membranes are poorly understood. Here, we use solid-state NMR and neutron diffraction to investigate the interactions between a voltage sensor toxin (VSTx1) and lipid membranes, with the goal of localizing the toxin in the membrane and determining its influence on membrane structure. Our results demonstrate that VSTx1 localizes to the headgroup region of lipid membranes and produces a thinning of the bilayer. The toxin orients such that many basic residues are in the aqueous phase, all three Trp residues adopt interfacial positions, and several hydrophobic residues are within the membrane interior. One remarkable feature of this preferred orientation is that the surface of the toxin that mediates binding to voltage sensors is ideally positioned within the lipid bilayer to favor complex formation between the toxin and the voltage sensor. PMID:25453087

  11. Detection of shiga toxins by lateral flow assay

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Shiga toxin-producing Escherichia coli (STEC) produce Shiga toxins (Stxs) that can cause human disease and death. The contamination of food products with STEC represents a food safety problem that necessitates rapid and effective detection strategies to mitigate risk. In this manuscript we report ...

  12. Nano Aptasensor for Protective Antigen Toxin of Lakshmi N. Cella,,,|

    E-print Network

    Chen, Wilfred

    Nano Aptasensor for Protective Antigen Toxin of Anthrax Lakshmi N. Cella,,,| Pablo Sanchez of California, Riverside, California 92521 We demonstrate a highly sensitive nano aptasensor for anthrax toxin, demonstrating it as a potential tool for rapid and point-of-care diagnosis for anthrax. Anthrax is a disease

  13. Membrane-Binding Mechanism of Clostridium perfringens Alpha-Toxin.

    PubMed

    Oda, Masataka; Terao, Yutaka; Sakurai, Jun; Nagahama, Masahiro

    2015-01-01

    Clostridium perfringens alpha-toxin is a key mediator of gas gangrene, which is a life-threatening infection that manifests as fever, pain, edema, myonecrosis, and gas production. Alpha-toxin possesses phospholipase C and sphingomyelinase activities. The toxin is composed of an N-terminal domain (1-250 aa, N-domain), which is the catalytic site, and a C-terminal domain (251-370 aa, C-domain), which is the membrane-binding site. Immunization of mice with the C-domain of alpha-toxin prevents the gas gangrene caused by C. perfringens, whereas immunization with the N-domain has no effect. The central loop domain (55-93 aa), especially H….SW(84)Y(85)….G, plays an important role in the interaction with ganglioside GM1a. The toxin binds to lipid rafts in the presence of a GM1a/TrkA complex, and metabolites from phosphatidylcholine to diacylglycerol through the enzymatic activity of alpha-toxin itself. These membrane dynamics leads to the activation of endogenous PLC?-1 via TrkA. In addition, treatment with alpha-toxin leads to the formation of diacylglycerol at membrane rafts in ganglioside-deficient DonQ cells; this in turn triggers endocytosis and cell death. This article summarizes the current the membrane-binding mechanism of alpha-toxin in detail. PMID:26633512

  14. Structure and Biological Activities of Beta Toxin from Staphylococcus aureus? †

    PubMed Central

    Huseby, Medora; Shi, Ke; Brown, C. Kent; Digre, Jeff; Mengistu, Fikre; Seo, Keun Seok; Bohach, Gregory A.; Schlievert, Patrick M.; Ohlendorf, Douglas H.; Earhart, Cathleen A.

    2007-01-01

    Beta toxin is a neutral sphingomyelinase secreted by certain strains of Staphylococcus aureus. This virulence factor lyses erythrocytes in order to evade the host immune system as well as scavenge nutrients. The structure of beta toxin was determined at 2.4-Å resolution using crystals that were merohedrally twinned. This structure is similar to that of the sphingomyelinases of Listeria ivanovii and Bacillus cereus. Beta toxin belongs to the DNase I folding superfamily; in addition to sphingomyelinases, the proteins most structurally related to beta toxin include human endonuclease HAP1, Escherichia coli endonuclease III, bovine pancreatic DNase I, and the endonuclease domain of TRAS1 from Bombyx mori. Our biological assays demonstrated for the first time that beta toxin kills proliferating human lymphocytes. Structure-directed active site mutations show that biological activities, including hemolysis and lymphotoxicity, are due to the sphingomyelinase activity of the enzyme. PMID:17873030

  15. Activation of botulinum toxins in the absence of nicking.

    PubMed Central

    Ohishi, I; Sakaguchi, G

    1977-01-01

    The derivative toxins purified from cultures of proteolytic strains of Clostridium botulinum types A and F were found to have been only partially nicked but were fully activated. Trypsinization of C. botulinum type B derivative toxin at pH 6.0 resulted in simultaneous activation and nicking, whereas at pH 4.5, activation preceded nicking. The toxin was split by trypsin at pH 6.0 into two fragments with molecular weights of 112, ooo and 57,000. The toxin contained at least three trypsin-sensitive peptide bonds, one of which was more sensitive than the others at pH 6.0. These results indicate that activation of botulinum toxins by trypsin or endogenous protease (s) is not a direct result of nicking. Images PMID:19360

  16. Removal of Cholera Toxin from Aqueous Solution by Probiotic Bacteria

    PubMed Central

    Heikkilä, Jari E.; Nybom, Sonja M. K.; Salminen, Seppo J.; Meriluoto, Jussi A. O.

    2012-01-01

    Cholera remains a serious health problem, especially in developing countries where basic hygiene standards are not met. The symptoms of cholera are caused by cholera toxin, an enterotoxin, which is produced by the bacterium Vibrio cholerae. We have recently shown that human probiotic bacteria are capable of removing cyanobacterial toxins from aqueous solutions. In the present study we investigate the ability of the human probiotic bacteria, Lactobacillus rhamnosus strain GG (ATCC 53103) and Bifidobacteriumlongum 46 (DSM 14583), to remove cholera toxin from solution in vitro. Lactobacillus rhamnosus strain GG and Bifidobacteriumlongum 46 were able to remove 68% and 59% of cholera toxin from aqueous solutions during 18 h of incubation at 37 °C, respectively. The effect was dependent on bacterial concentration and L. rhamnosus GG was more effective at lower bacterial concentrations. No significant effect on cholera toxin concentration was observed when nonviable bacteria or bacterial supernatant was used. PMID:24281668

  17. Prokaryotic adenylate cyclase toxin stimulates anterior pituitary cells in culture

    SciTech Connect

    Cronin, M.J.; Evans, W.S.; Rogol, A.D.; Weiss, A.A.; Thorner, M.O.; Orth, D.N.; Nicholson, W.E.; Yasumoto, T.; Hewlett, E.L.

    1986-08-01

    Bordetella pertussis synthesis a variety of virulence factors including a calmodulin-dependent adenylate cyclase (AC) toxin. Treatment of anterior pituitary cells with this AC toxin resulted in an increase in cellular cAMP levels that was associated with accelerated exocytosis of growth hormone (GH), prolactin, adrenocorticotropic hormone (ACTH), and luteinizing hormone (LH). The kinetics of release of these hormones, however, were markedly different; GH and prolactin were rapidly released, while LH and ACTH secretion was more gradually elevated. Neither dopamine agonists nor somatostatin changes the ability of AC toxin to generate cAMP (up to 2 h). Low concentrations of AC toxin amplified the secretory response to hypophysiotrophic hormones. The authors conclude that bacterial AC toxin can rapidly elevate cAMP levels in anterior pituitary cells and that it is the response that explains the subsequent acceleration of hormone release.

  18. Use of lactose against the deadly biological toxin ricin.

    PubMed

    Nagatsuka, Takehiro; Uzawa, Hirotaka; Ohsawa, Isaac; Seto, Yasuo; Nishida, Yoshihiro

    2010-04-01

    Developing a technology for detecting and decontaminating biological toxins is needed. Ricin from Ricinus communis is a highly poisonous toxin; it was formerly used for an assassination in London and in postal attacks in the United States. Ricin is readily available from castor beans and could be used as a biological agent. We propose using glycotechnology against the illegal use of ricin. Lactose (a natural ligand of this toxin) was incorporated into polyacrylamide-based glycopolymers at variable sugar densities (18-100%) and evaluated with surface plasmon resonance (SPR) spectroscopy and the real agent, ricin. Glycopolymers (18-65% lactose densities) effectively interfered with the toxin-lactoside adhesion event (>99% efficiency within 20 min). This supported the notion of using the mammary sugar lactose against a deadly biological toxin. PMID:20369893

  19. Treatment of Gastrointestinal Sphincters Spasms with Botulinum Toxin A

    PubMed Central

    Brisinda, Giuseppe; Sivestrini, Nicola; Bianco, Giuseppe; Maria, Giorgio

    2015-01-01

    Botulinum toxin A inhibits neuromuscular transmission. It has become a drug with many indications. The range of clinical applications has grown to encompass several neurological and non-neurological conditions. One of the most recent achievements in the field is the observation that botulinum toxin A provides benefit in diseases of the gastrointestinal tract. Although toxin blocks cholinergic nerve endings in the autonomic nervous system, it has also been shown that it does not block non-adrenergic non-cholinergic responses mediated by nitric oxide. This has promoted further interest in using botulinum toxin A as a treatment for overactive smooth muscles and sphincters. The introduction of this therapy has made the treatment of several clinical conditions easier, in the outpatient setting, at a lower cost and without permanent complications. This review presents current data on the use of botulinum toxin A in the treatment of pathological conditions of the gastrointestinal tract. PMID:26035487

  20. Shiga toxin-producing Escherichia coli

    PubMed Central

    Etcheverría, Analía Inés; Padola, Nora Lía

    2013-01-01

    Shiga toxin-producing Escherichia coli (STEC) cause hemorrhagic colitis (HC) and hemolytic uremic syndrome (HUS) in humans. Outbreaks are linked to bovine food sources. STEC O157:H7 has been responsible for the most severe outbreaks worldwide. However, non-O157 serotypes have emerged as important enteric pathogens in several countries. The main virulence factor of STEC is the production of Shiga toxins 1 and 2. Additional virulence markers are a plasmid-encoded enterohemolysin (ehxA), an autoagglutinating adhesin (Saa), a catalase-peroxidase (katP), an extracellular serine protease (espP), a zinc metalloprotease (stcE), a subtilase cytotoxin (subAB), among others. Other virulence factors are intimin and adhesins that had a roll in the adherence of STEC to bovine colon. This review focuses on the virulence traits of STEC and especially on those related to the adhesion to bovine colon. The known of the interaction between STEC and the bovine host is crucial to develop strategies to control cattle colonization. PMID:23624795

  1. Spectroscopic study of food and food toxins

    NASA Astrophysics Data System (ADS)

    King, Gavin; Walsh, James E.; Martin, Suzanne

    2003-03-01

    Fungal infection of food causes billions of dollars of lost revenue per annum as well as health problems, to animals and humans, if consumed in sufficient quantities. Modern food sorting techniques rely on colour or other physical characteristics to filter diseased or otherwise unsuitable foodstuffs from healthy foodstuffs. Their speeds are such that up to 40,000 objects per second can be moved at 4 metres per second, through 1 m wide chutes that offer a wide view for colour and shape sorting. Grain type foods such as coffee or peanuts are often vulnerable to toxic infection from invading fungi. If this happens, then their texture, taste and colour can change. Up to now, only visible wavelengths and colour identification have been used to bulk-sort food, but there has been little research in the ultra violet regions of the spectrum to help identify fungus or toxin infection. This research specifically concentrated on the ultra violet (UV) spectral characteristics of food in an attempt to identify possible spectral changes that occur when healthy food items like peanuts become infected with toxin-producing fungi. Ultimately, the goal is to design, build and construct an optical detection system that can use these 'spectral fingerprints' to more quickly and efficiently detect toxically infected food items.

  2. Gene Therapy and Targeted Toxins for Glioma

    PubMed Central

    King, Gwendalyn D.; Curtin, James F.; Candolfi, Marianela; Kroeger, Kurt; Lowenstein, Pedro R.; Castro, Maria G.

    2006-01-01

    The most common primary brain tumor in adults is glioblastoma. These tumors are highly invasive and aggressive with a mean survival time of nine to twelve months from diagnosis to death. Current treatment modalities are unable to significantly prolong survival in patients diagnosed with glioblastoma. As such, glioma is an attractive target for developing novel therapeutic approaches utilizing gene therapy. This review will examine the available preclinical models for glioma including xenographs, syngeneic and genetic models. Several promising therapeutic targets are currently being pursued in pre-clinical investigations. These targets will be reviewed by mechanism of action, i.e., conditional cytotoxic, targeted toxins, oncolytic viruses, tumor suppressors/oncogenes, and immune stimulatory approaches. Preclinical gene therapy paradigms aim to determine which strategies will provide rapid tumor regression and long-term protection from recurrence. While a wide range of potential targets are being investigated preclinically, only the most efficacious are further transitioned into clinical trial paradigms. Clinical trials reported to date are summarized including results from conditionally cytotoxic, targeted toxins, oncolytic viruses and oncogene targeting approaches. Clinical trial results have not been as robust as preclinical models predicted, this could be due to the limitations of the GBM models employed. Once this is addressed, and we develop effective gene therapies in models that better replicate the clinical scenario, gene therapy will provide a powerful approach to treat and manage brain tumors. PMID:16457645

  3. Gene Therapy and Targeted Toxins for Glioma

    PubMed Central

    Castro, Maria G.; Candolfi, Marianela; Kroeger, Kurt; King, Gwendalyn D.; Curtin, James F.; Yagiz, Kader; Mineharu, Yohei; Assi, Hikmat; Wibowo, Mia; Muhammad, AKM Ghulam; Foulad, David; Puntel, Mariana; Lowenstein, Pedro R.

    2011-01-01

    The most common primary brain tumor in adults is glioblastoma. These tumors are highly invasive and aggressive with a mean survival time of nine to twelve months from diagnosis to death. Current treatment modalities are unable to significantly prolong survival in patients diagnosed with glioblastoma. As such, glioma is an attractive target for developing novel therapeutic approaches utilizing gene therapy. This review will examine the available preclinical models for glioma including xenographs, syngeneic and genetic models. Several promising therapeutic targets are currently being pursued in pre-clinical investigations. These targets will be reviewed by mechanism of action, i.e., conditional cytotoxic, targeted toxins, oncolytic viruses, tumor suppressors/oncogenes, and immune stimulatory approaches. Preclinical gene therapy paradigms aim to determine which strategies will provide rapid tumor regression and long-term protection from recurrence. While a wide range of potential targets are being investigated preclinically, only the most efficacious are further transitioned into clinical trial paradigms. Clinical trials reported to date are summarized including results from conditionally cytotoxic, targeted toxins, oncolytic viruses and oncogene targeting approaches. Clinical trial results have not been as robust as preclinical models predicted; this could be due to the limitations of the GBM models employed. Once this is addressed, and we develop effective gene therapies in models that better replicate the clinical scenario, gene therapy will provide a powerful approach to treat and manage brain tumors. PMID:21453286

  4. Towards an understanding of the role of Clostridium perfringens toxins in human and animal disease.

    PubMed

    Uzal, Francisco A; Freedman, John C; Shrestha, Archana; Theoret, James R; Garcia, Jorge; Awad, Milena M; Adams, Vicki; Moore, Robert J; Rood, Julian I; McClane, Bruce A

    2014-01-01

    Clostridium perfringens uses its arsenal of >16 toxins to cause histotoxic and intestinal infections in humans and animals. It has been unclear why this bacterium produces so many different toxins, especially since many target the plasma membrane of host cells. However, it is now established that C. perfringens uses chromosomally encoded alpha toxin (a phospholipase C) and perfringolysin O (a pore-forming toxin) during histotoxic infections. In contrast, this bacterium causes intestinal disease by employing toxins encoded by mobile genetic elements, including C. perfringens enterotoxin, necrotic enteritis toxin B-like, epsilon toxin and beta toxin. Like perfringolysin O, the toxins with established roles in intestinal disease form membrane pores. However, the intestinal disease-associated toxins vary in their target specificity, when they are produced (sporulation vs vegetative growth), and in their sensitivity to intestinal proteases. Producing many toxins with diverse characteristics likely imparts virulence flexibility to C. perfringens so it can cause an array of diseases. PMID:24762309

  5. Stabilization of labile organic C along a chronosequence of soil development: mineralogical vs. biological controls

    NASA Astrophysics Data System (ADS)

    McFarland, J. W.; Waldrop, M. P.; Strawn, D.; Harden, J. W.

    2010-12-01

    Soil organic matter (SOM) represents an important reservoir for carbon (C), nitrogen (N), and other essential nutrients. Consequently, variation in SOM turnover rates regulates resource availability for soil microbial activity and plant growth. Long-term SOM stabilization generally involves restricted microbial access to SOM through a variety of processes including complexation with soil minerals. These organo-mineral interactions are influenced by mineral composition and texture, often related to soil age. Soil microorganisms also influence the stabilization of C inputs to the pedosphere through the production of refractory residues controlled in part by C allocation patterns during metabolism. In this study we examined, simultaneously, the contribution of these two C stabilizing mechanisms by ‘tracing’ the fate of two 13C-labeled substrates (glucose and p-hydroxybenzoic acid) along a 1600Kya chronosequence of soil development along the Cowlitz River in southwest Washington. Our objective was to evaluate the relationship between mineralogical and biological controls over C sequestration in soils. Mineralogical analyses were done using the selective dissolutions ammonium oxalate (AOD), and dithionite-citrate extraction (CBD). In this cool, humid environment, intermediate aged soils derived from the late Wisconsin Evans Creek drift (24ka) had the highest AOD extractable Al, Fe, and Si, indicating a higher concentration of poorly crystalline minerals relative to other terraces. Correspondingly, CBD extractable Fe increases with soil age, further supporting the idea that crystalline iron oxides are also more prevalent with weathering. Turnover of both 13C-labeled substrates was rapid (< 12.5 hrs) However, the proportion of substrate mineralized to CO2 varied among terraces. Mineralization to CO2 was significantly lower at 24ka than that for the other three age classes (0.25k, 220k, and 1,600k years bp), corresponding to higher recovery of 13C in bulk soil for this age class. In similar studies, soils containing a higher proportion of poorly crystalline minerals typically have a higher degree of hydration, surface area, and variable charge, which can increase microbial yield, reducing the amount of CO2 produced per unit biomass and increasing potential for soil C sequestration. Additionally, total flux of 13CO2 was significantly higher and recovery of 13C in microbial pools trended lower for the phenolic than for glucose for all soils types excluding the 24ka terrace. The broader implication, which may warrant consideration in models of terrestrial C flux, is that altering the constituency of labile C inputs to these soil environments could similarly influence the degree to which C is stabilized in soil mineral assemblages.

  6. Labile carbon regulates protease activity and nitrogen acquisition in boreal forest topsoil.

    NASA Astrophysics Data System (ADS)

    Lindén, A.; Heinonsalo, J.; Oinonen, M.; Sonninen, E.; Hilasvuori, E.; Pumpanen, J.

    2012-04-01

    In boreal zone, soil organic matter (SOM) contains a substantial amount of recalcitrant material and forms a large nitrogen pool. However, this pool is to a great extent inaccessible to plants, due to its low decomposability. Although, the nitrogen supply is the most limiting factor of net ecosystem production (NEP) in boreal forests, it has been speculated that as a result of the accelerated decomposition of SOM induced by climate warming, part of this nitrogen pool could be released. It has also been shown that a substantial proportion of gross primary production (GPP) is allocated below ground and acts as an energy source for decomposing rhizomicrobial organisms, and that changes in the GPP rate could therefore increase the belowground turn over rate of otherwise recalcitrant nitrogen-rich SOM. We were studying the effects of increasing labile carbon input on the symbiotic microbial N acquisition and protease activities in a controlled microcosm experiment. We compared the natural abundance of isotope ratios of 13C and 14C in soil CO2efflux, protease enzyme activity, natural abundance of 15N in the needles, and microbial biomass in microcosms containing bare soil and tree seedlings. In addition, we had treatments were additional energy was given to the bare soil and seedling microcosms in the form of glucose. The age of the CO2 originating from the decomposition process of SOM was older in all treatments where easily decomposable carbon (energy) was available for soil microorganisms. The increased natural abundance of 15N in the needles of the seedlings treated with glucose, suggests a shift in nitrogen acquisition to different SOM pool, which was reflected strongly to the total N content of the SOM and evolving 13C signature in soil CO2 efflux. The protease activity was highest in treatments with artificial glucose addition. Our results suggest that the increased input of easily available carbon from aboveground enables the decomposition of recalcitrant nitrogen rich compounds in SOM and could therefore increase the nitrogen supply to plants.

  7. Associations between heat shock protein 70 genetic polymorphisms and calving traits in crossbred Brahman cows

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Stressors such as heat, cold, toxins, and oxygen deprivation are known to induce heat shock proteins. Genetic polymorphisms associated with heat shock protein genes have been associated with decreased male and female fertility. Our objectives were to 1) confirm single nucleotide polymorphisms (SNP) ...

  8. Seasonal hydrological cycle control on age, abundance and lability of carbon exported from the Greenland ice sheet

    NASA Astrophysics Data System (ADS)

    Bhatia, M. P.; Das, S. B.; Charette, M. A.; Xu, L.; Kujawinski, E. B.

    2010-12-01

    Glacial environments possess a more dynamic organic carbon system than previously thought. The discovery of abundant, active microbial communities at the base of glaciers and ice sheets provides a mechanism for both (a) extensive subglacial organic carbon metabolism (e.g. respiration, fermentation) on various timescales, and (b) the present-day export of labile carbon to downstream ecosystems. Prior studies are limited but point towards the importance of both of these processes in modulating carbon cycling. In order to develop predictive understanding of these processes, elucidation of the dominant molecular-level and bulk carbon dynamics is critical. Here we build on earlier results that described changes in molecular-level composition of dissolved organic matter associated with the Greenland ice sheet (GrIS), by describing for the first time the bulk-level carbon composition of glacial meltwater from the GrIS. Our study focuses on several outlet glaciers and a large proglacial lake along the western margin of the GrIS. We investigate the organic carbon abundance (dissolved and particulate concentrations), age (dissolved and particulate radiocarbon content), and lability (dissolved organic carbon to nitrogen ratios) in the subglacial discharge throughout the summer melt season. The early season (May) glacier discharge contains significantly higher dissolved organic carbon concentrations (23 - 342 ?M), and exports younger carbon (~ 2 kyr 14C age) compared to the peak season (July) glacier discharge, where the concentrations are lower (11 - 51 ?M) and the age is older (~ 4 kyr 14C age). These results illustrate (1) that chemically-distinct organic carbon pools are accessed by seasonally-evolving hydrological flow-paths and (2) that the GrIS can deliver labile, old carbon to the North Atlantic and Arctic Oceans.

  9. Impacts of Labile Organic Carbon Concentration on Organic and Inorganic Nitrogen Utilization by a Stream Biofilm Bacterial Community

    PubMed Central

    Leff, Laura G.

    2013-01-01

    In aquatic ecosystems, carbon (C) availability strongly influences nitrogen (N) dynamics. One manifestation of this linkage is the importance in the dissolved organic matter (DOM) pool of dissolved organic nitrogen (DON), which can serve as both a C and an N source, yet our knowledge of how specific properties of DOM influence N dynamics are limited. To empirically examine the impact of labile DOM on the responses of bacteria to DON and dissolved inorganic nitrogen (DIN), bacterial abundance and community composition were examined in controlled laboratory microcosms subjected to various combinations of dissolved organic carbon (DOC), DON, and DIN treatments. Bacterial communities that had colonized glass beads incubated in a stream were treated with various glucose concentrations and combinations of inorganic and organic N (derived from algal exudate, bacterial protein, and humic matter). The results revealed a strong influence of C availability on bacterial utilization of DON and DIN, with preferential uptake of DON under low C concentrations. Bacterial DON uptake was affected by the concentration and by its chemical nature (labile versus recalcitrant). Labile organic N sources (algal exudate and bacterial protein) were utilized equally well as DIN as an N source, but this was not the case for the recalcitrant humic matter DON treatment. Clear differences in bacterial community composition among treatments were observed based on terminal restriction fragment length polymorphisms (T-RFLP) of 16S rRNA genes. C, DIN, and DON treatments likely drove changes in bacterial community composition that in turn affected the rates of DON and DIN utilization under various C concentrations. PMID:24038688

  10. Infection with Toxin A-Negative, Toxin B-Negative, Binary Toxin-Positive Clostridium difficile in a Young Patient with Ulcerative Colitis.

    PubMed

    Androga, Grace O; Hart, Julie; Foster, Niki F; Charles, Adrian; Forbes, David; Riley, Thomas V

    2015-11-01

    Large clostridial toxin-negative, binary toxin-positive (A(-) B(-) CDT(+)) strains of Clostridium difficile are almost never associated with clinically significant C. difficile infection (CDI), possibly because such strains are not detected by most diagnostic methods. We report the isolation of an A(-) B(-) CDT(+) ribotype 033 (RT033) strain of C. difficile from a young patient with ulcerative colitis and severe diarrhea. PMID:26354812

  11. Synthesis of Acid-Labile PEG and PEG-Doxorubicin-Conjugate Nanoparticles via Brush-First ROMP

    PubMed Central

    2015-01-01

    A panel of acid-labile bis-norbornene cross-linkers was synthesized and evaluated for the formation of acid-degradable brush-arm star polymers (BASPs) via the brush-first ring-opening metathesis polymerization (ROMP) method. An acetal-based cross-linker was identified that, when employed in conjunction with a poly(ethylene glycol) (PEG) macromonomer, provided highly controlled BASP formation reactions. A combination of this new cross-linker with a novel doxorubicin (DOX)-branch-PEG macromonomer provided BASPs that simultaneously degrade and release cytotoxic DOX in vitro. PMID:25243099

  12. Relative Lability and Chemoselective Transmetallation of NHC in Hybrid Phosphine-NHC Ligands: Access to Heterometallic Complexes.

    PubMed

    Simler, Thomas; Braunstein, Pierre; Danopoulos, Andreas A

    2015-11-01

    The relative lability and transmetallation aptitude of trialkylphosphine and NHC donors, integrated in semi-rigid hybrid ligands attached to [Ag4 Br4 ] pseudo-cubanes, lies in favor of the NHC and is used to selectively access unprecedented NHC complexes with heterobimetallic cores, such as Ag-Cu (4(Cy) ) and Ag-Ir (5(tBu) ). These can be viewed as an arrested state before the full transmetallation of both donors, which gives the homodinuclear Cu (3(Cy) ) and Ir (6(Cy) ) complexes. The observed NHC transmetallation aptitude and reactivity urges caution in the common notion that views the NHC as a universal spectator. PMID:26463419

  13. The stress-related emotional lability syndrome. 1. Definition, psychophysiological mechanisms and a pilot experience with Orap.

    PubMed

    Wetzels, M H

    1977-01-01

    Patients suffering from stress-related emotional lability are in our modern life a common phenomenon. The diagnosis is difficult by the atypical symptoms (body complaints who are suggestive for a neurosis and becomes apparent on careful questioning revealing fear of failing, rigidity and similar character traits. Also, certain tests indicate increased fear of failing and the MMPI reveals high scores for psychiasthenia. Those patients starts from a high "baseline (endogenous) stress level. Our experience with pimozide indicates that this drug reduces the latter baseline stress level and therefore adds a valuable contribution to the treatment of such patients. PMID:906886

  14. ACTIN-DIRECTED TOXIN. ACD toxin-produced actin oligomers poison formin-controlled actin polymerization.

    PubMed

    Heisler, David B; Kudryashova, Elena; Grinevich, Dmitry O; Suarez, Cristian; Winkelman, Jonathan D; Birukov, Konstantin G; Kotha, Sainath R; Parinandi, Narasimham L; Vavylonis, Dimitrios; Kovar, David R; Kudryashov, Dmitri S

    2015-07-31

    The actin cross-linking domain (ACD) is an actin-specific toxin produced by several pathogens, including life-threatening spp. of Vibrio cholerae, Vibrio vulnificus, and Aeromonas hydrophila. Actin cross-linking by ACD is thought to lead to slow cytoskeleton failure owing to a gradual sequestration of actin in the form of nonfunctional oligomers. Here, we found that ACD converted cytoplasmic actin into highly toxic oligomers that potently "poisoned" the ability of major actin assembly proteins, formins, to sustain actin polymerization. Thus, ACD can target the most abundant cellular protein by using actin oligomers as secondary toxins to efficiently subvert cellular functions of actin while functioning at very low doses. PMID:26228148

  15. Factors Affecting Interaction of Staphylococcal Alpha Toxin with Membranes

    PubMed Central

    Bernheimer, Alan W.; Kim, Kwang Shin; Remsen, Charles C.; Antanavage, Joanne; Watson, Stanley W.

    1972-01-01

    Staphylococcal alpha toxin interacts not only with membranes of erythrocytes but also with membranes of other kinds of mammalian cells (platelets, hepatocytes, and lysosomes from polymorphonuclear leukocytes) with the formation of characteristic ring-like structures that can be seen by electron microscopy. Such structures are not observed when alpha toxin is added to membranes derived from various bacteria. The rings seen on mammalian cell membranes tend to be either randomly disposed or in square array. The frequency with which square arrays are seen is influenced by the presence of staphylococcal delta toxin, by the negative staining agent, and by the kind of cell from which the membrane is derived. Synthetic membranes in the form of liposomes, prepared individually from phosphatidyl choline, phosphatidyl serine, phosphatidyl inositol, and cardiolipin, produced randomly disposed rings upon addition of alpha toxin. Liposomes made from phosphatidyl ethanolamine did not yield rings. Alpha toxin-treated liposomes prepared from chloroform-methanol extracts of brain white matter consistently showed rings that were rectangularly ordered. Ordered rings on membranes derived from toxin-treated platelets and those on toxin-treated brain extract liposomes were seen in freeze-etched as well as in negatively stained preparations. Images PMID:4117802

  16. Toxin-Antitoxin Systems as Multilevel Interaction Systems

    PubMed Central

    Goeders, Nathalie; Van Melderen, Laurence

    2014-01-01

    Toxin-antitoxin (TA) systems are small genetic modules usually composed of a toxin and an antitoxin counteracting the activity of the toxic protein. These systems are widely spread in bacterial and archaeal genomes. TA systems have been assigned many functions, ranging from persistence to DNA stabilization or protection against mobile genetic elements. They are classified in five types, depending on the nature and mode of action of the antitoxin. In type I and III, antitoxins are RNAs that either inhibit the synthesis of the toxin or sequester it. In type II, IV and V, antitoxins are proteins that either sequester, counterbalance toxin activity or inhibit toxin synthesis. In addition to these interactions between the antitoxin and toxin components (RNA-RNA, protein-protein, RNA-protein), TA systems interact with a variety of cellular factors, e.g., toxins target essential cellular components, antitoxins are degraded by RNAses or ATP-dependent proteases. Hence, TA systems have the capacity to interact with each other at different levels. In this review, we will discuss the different interactions in which TA systems are involved and their implications in TA system functions and evolution. PMID:24434905

  17. Mycoplasma pneumoniae CARDS Toxin Induces Pulmonary Eosinophilic and Lymphocytic Inflammation

    PubMed Central

    Medina, Jorge L.; Coalson, Jacqueline J.; Brooks, Edward G.; Winter, Vicki T.; Chaparro, Adriana; Principe, Molly F. R.; Kannan, Thirumalai R.; Baseman, Joel B.

    2012-01-01

    Mycoplasma pneumoniae causes acute and chronic lung infections in humans, leading to a variety of pulmonary and extrapulmonary sequelae. Of the airway complications of M. pneumoniae infection, M. pneumoniae–associated exacerbation of asthma and pediatric wheezing are emerging as significant sources of human morbidity. However, M. pneumoniae products capable of promoting allergic inflammation are unknown. Recently, we reported that M. pneumoniae produces an ADP-ribosylating and vacuolating toxin termed the community-acquired respiratory distress syndrome (CARDS) toxin. Here we report that naive mice exposed to a single dose of recombinant CARDS (rCARDS) toxin respond with a robust inflammatory response consistent with allergic disease. rCARDS toxin induced 30-fold increased expression of the Th-2 cytokines IL-4 and IL-13 and 70- to 80-fold increased expression of the Th-2 chemokines CCL17 and CCL22, corresponding to a mixed cellular inflammatory response comprised of a robust eosinophilia, accumulation of T cells and B cells, and mucus metaplasia. The inflammatory responses correlate temporally with toxin-dependent increases in airway hyperreactivity characterized by increases in airway restriction and decreases in lung compliance. Furthermore, CARDS toxin–mediated changes in lung function and histopathology are dependent on CD4+ T cells. Altogether, the data suggest that rCARDS toxin is capable of inducing allergic-type inflammation in naive animals and may represent a causal factor in M. pneumoniae–associated asthma. PMID:22281984

  18. Structural Basis of Clostridium perfringens Toxin Complex Formation

    SciTech Connect

    Adams,J.; Gregg, K.; Bayer, E.; Boraston, A.; Smith, S.

    2008-01-01

    The virulent properties of the common human and livestock pathogen Clostridium perfringens are attributable to a formidable battery of toxins. Among these are a number of large and highly modular carbohydrate-active enzymes, including the {mu}-toxin and sialidases, whose catalytic properties are consistent with degradation of the mucosal layer of the human gut, glycosaminoglycans, and other cellular glycans found throughout the body. The conservation of noncatalytic ancillary modules among these enzymes suggests they make significant contributions to the overall functionality of the toxins. Here, we describe the structural basis of an ultra-tight interaction (Ka = 1.44 x 1011 M-1) between the X82 and dockerin modules, which are found throughout numerous C. perfringens carbohydrate-active enzymes. Extensive hydrogen-bonding and van der Waals contacts between the X82 and dockerin modules give rise to the observed high affinity. The {mu}-toxin dockerin module in this complex is positioned {approx}180 relative to the orientation of the dockerin modules on the cohesin module surface within cellulolytic complexes. These observations represent a unique property of these clostridial toxins whereby they can associate into large, noncovalent multitoxin complexes that allow potentiation of the activities of the individual toxins by combining complementary toxin specificities.

  19. Dinophysis Toxins: Causative Organisms, Distribution and Fate in Shellfish

    PubMed Central

    Reguera, Beatriz; Riobó, Pilar; Rodríguez, Francisco; Díaz, Patricio A.; Pizarro, Gemita; Paz, Beatriz; Franco, José M.; Blanco, Juan

    2014-01-01

    Several Dinophysis species produce diarrhoetic toxins (okadaic acid and dinophysistoxins) and pectenotoxins, and cause gastointestinal illness, Diarrhetic Shellfish Poisoning (DSP), even at low cell densities (<103 cells·L?1). They are the main threat, in terms of days of harvesting bans, to aquaculture in Northern Japan, Chile, and Europe. Toxicity and toxin profiles are very variable, more between strains than species. The distribution of DSP events mirrors that of shellfish production areas that have implemented toxin regulations, otherwise misinterpreted as bacterial or viral contamination. Field observations and laboratory experiments have shown that most of the toxins produced by Dinophysis are released into the medium, raising questions about the ecological role of extracelular toxins and their potential uptake by shellfish. Shellfish contamination results from a complex balance between food selection, adsorption, species-specific enzymatic transformations, and allometric processes. Highest risk areas are those combining Dinophysis strains with high cell content of okadaates, aquaculture with predominance of mytilids (good accumulators of toxins), and consumers who frequently include mussels in their diet. Regions including pectenotoxins in their regulated phycotoxins will suffer from much longer harvesting bans and from disloyal competition with production areas where these toxins have been deregulated. PMID:24447996

  20. Dinophysis toxins: causative organisms, distribution and fate in shellfish.

    PubMed

    Reguera, Beatriz; Riobó, Pilar; Rodríguez, Francisco; Díaz, Patricio A; Pizarro, Gemita; Paz, Beatriz; Franco, José M; Blanco, Juan

    2014-01-01

    Several Dinophysis species produce diarrhoetic toxins (okadaic acid and dinophysistoxins) and pectenotoxins, and cause gastointestinal illness, Diarrhetic Shellfish Poisoning (DSP), even at low cell densities (<103 cells·L?¹). They are the main threat, in terms of days of harvesting bans, to aquaculture in Northern Japan, Chile, and Europe. Toxicity and toxin profiles are very variable, more between strains than species. The distribution of DSP events mirrors that of shellfish production areas that have implemented toxin regulations, otherwise misinterpreted as bacterial or viral contamination. Field observations and laboratory experiments have shown that most of the toxins produced by Dinophysis are released into the medium, raising questions about the ecological role of extracelular toxins and their potential uptake by shellfish. Shellfish contamination results from a complex balance between food selection, adsorption, species-specific enzymatic transformations, and allometric processes. Highest risk areas are those combining Dinophysis strains with high cell content of okadaates, aquaculture with predominance of mytilids (good accumulators of toxins), and consumers who frequently include mussels in their diet. Regions including pectenotoxins in their regulated phycotoxins will suffer from much longer harvesting bans and from disloyal competition with production areas where these toxins have been deregulated. PMID:24447996

  1. Structural insights into Bacillus thuringiensis Cry, Cyt and parasporin toxins.

    PubMed

    Xu, Chengchen; Wang, Bi-Cheng; Yu, Ziniu; Sun, Ming

    2014-09-01

    Since the first X-ray structure of Cry3Aa was revealed in 1991, numerous structures of B. thuringiensis toxins have been determined and published. In recent years, functional studies on the mode of action and resistance mechanism have been proposed, which notably promoted the developments of biological insecticides and insect-resistant transgenic crops. With the exploration of known pore-forming toxins (PFTs) structures, similarities between PFTs and B. thuringiensis toxins have provided great insights into receptor binding interactions and conformational changes from water-soluble to membrane pore-forming state of B. thuringiensis toxins. This review mainly focuses on the latest discoveries of the toxin working mechanism, with the emphasis on structural related progress. Based on the structural features, B. thuringiensis Cry, Cyt and parasporin toxins could be divided into three categories: three-domain type ?-PFTs, Cyt toxin type ?-PFTs and aerolysin type ?-PFTs. Structures from each group are elucidated and discussed in relation to the latest data, respectively. PMID:25229189

  2. Genetically modified anthrax lethal toxin safely delivers whole HIV protein antigens into the

    E-print Network

    Starnbach, Michael

    . anthracis consists of two bipartite protein exotoxins, lethal toxin (LT) and edema toxin. LT is composed of protective antigen (PA) and lethal factor (LF), whereas edema toxin consists of PA and edema factor (EF). None of these three components, PA, LF, and EF, alone is toxic. Once combined, however, edema toxin

  3. Electrochemical and PM-IRRAS Characterization of Cholera Toxin Binding at a Model Biological Membrane

    E-print Network

    Dutcher, John

    in the outer leaflet of the plasma membrane. Once bound, the toxin is translocated across the plasma membrane, the mechanism by which the toxin is able to cross the plasma membrane remains elusive, as does the extent to which the toxin is transported. It is known that membrane transport of the toxin is dependent

  4. 42 CFR 73.5 - Exemptions for HHS select agents and toxins.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 42 Public Health 1 2013-10-01 2013-10-01 false Exemptions for HHS select agents and toxins. 73.5..., INSPECTION, LICENSING SELECT AGENTS AND TOXINS § 73.5 Exemptions for HHS select agents and toxins. (a... toxin that is contained in a specimen presented for diagnosis or verification will be exempt from...

  5. Mesoporous silica nanoparticlesupported lipid bilayers, or `protocells', are loaded with ricin toxin A

    E-print Network

    Brinker, C. Jeffrey

    toxin A chain (RTA) and targeted to hepatocellular carcinoma (HCC) with a peptide (SP94) that binds Peabody, Walker Wharton, C. Jeffrey Brinker, Carlee Ashley,* and Eric Carnes* Delivery of Ricin Toxin A a significant effort to utilize protein toxins, including diphtheria, cholera, and ricin toxins, as anti

  6. Pore-forming toxins and cellular non-immune defenses (CNIDs) Raffi Aroian1

    E-print Network

    Aroian, Raffi V.

    Pore-forming toxins and cellular non-immune defenses (CNIDs) Raffi Aroian1 and F G van der Goot2 Pore-forming toxins (PFTs) are the most common class of bacterial protein toxin and are important in response to these toxins and have no defenses against these pores is oversimplified. Rather, it appears

  7. Toxin YafQ increases persister cell formation by reducing indole signalling

    E-print Network

    Wood, Thomas K.

    Toxin YafQ increases persister cell formation by reducing indole signalling Ying Hu,1 Brian W. Kwan survive antibiotic and other environ- mental stresses by slowing metabolism. Since toxins of toxin the influence of toxin YafQ of the YafQ/ DinJ Escherichia coli TA system on persister cell for- mation. Under

  8. 42 CFR 73.5 - Exemptions for HHS select agents and toxins.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 42 Public Health 1 2012-10-01 2012-10-01 false Exemptions for HHS select agents and toxins. 73.5..., INSPECTION, LICENSING SELECT AGENTS AND TOXINS § 73.5 Exemptions for HHS select agents and toxins. (a... toxin that is contained in a specimen presented for diagnosis or verification will be exempt from...

  9. 77 FR 71702 - Possession, Use, and Transfer of Select Agents and Toxins; Biennial Review

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-04

    ...0920-AA34 Possession, Use, and Transfer of Select Agents and Toxins; Biennial Review AGENCY...agents and toxins and designated certain select agents and toxins as Tier 1 agents. DATES...Robbin Weyant, Director, Division of Select Agents and Toxins, Centers for...

  10. Anthrax Toxins in Context of Bacillus anthracis Spores and Spore Germination.

    PubMed

    Cote, Christopher K; Welkos, Susan L

    2015-08-01

    The interaction of anthrax toxin or toxin components with B. anthracis spores has been demonstrated. Germinating spores can produce significant amounts of toxin components very soon after the initiation of germination. In this review, we will summarize the work performed that has led to our understanding of toxin and spore interactions and discuss the complexities associated with these interactions. PMID:26287244

  11. Developing a method to scale up production of solanapyrone toxins by Ascochyta rabiei

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ascochyta rabiei, the causal agent of Ascochyta blight of chickpea, produces solanapyrone toxins. The toxins may play a role in pathogenesis. In order to develop toxin assays for screening chickpea genotypes and to investigate the role of the toxins in developing the disease Ascochyta blight, a me...

  12. Anthrax Toxins in Context of Bacillus anthracis Spores and Spore Germination

    PubMed Central

    Cote, Christopher K.; Welkos, Susan L.

    2015-01-01

    The interaction of anthrax toxin or toxin components with B. anthracis spores has been demonstrated. Germinating spores can produce significant amounts of toxin components very soon after the initiation of germination. In this review, we will summarize the work performed that has led to our understanding of toxin and spore interactions and discuss the complexities associated with these interactions. PMID:26287244

  13. Metabolism of the Fusarium Mycotoxins T-2 Toxin and HT-2 Toxin in Wheat

    PubMed Central

    2015-01-01

    To investigate the metabolic fate of HT-2 toxin (HT2) and T-2 toxin (T2) in wheat (Triticum aestivum L.), an untargeted metabolomics study utilizing stable isotopic labeling and liquid chromatography–high resolution mass spectrometry was performed. In total, 11 HT2 and 12 T2 derived in planta biotransformation products were annotated putatively. In addition to previously reported mono- and diglucosylated forms of HT2, evidence for the formation of HT2-malonyl-glucoside and feruloyl-T2, as well as acetylation and deacetylation products in wheat was obtained for the first time. To monitor the kinetics of metabolite formation, a time course experiment was conducted involving the Fusarium head blight susceptible variety Remus and the resistant cultivar CM-82036. Biotransformation reactions were observed already at the earliest tested time point (6 h after treatment), and formed metabolites showed different kinetic profiles. After ripening, less than 15% of the toxins added to the plants were determined to be unmetabolized. PMID:26278508

  14. Metabolism of the Fusarium Mycotoxins T-2 Toxin and HT-2 Toxin in Wheat.

    PubMed

    Nathanail, Alexis V; Varga, Elisabeth; Meng-Reiterer, Jacqueline; Bueschl, Christoph; Michlmayr, Herbert; Malachova, Alexandra; Fruhmann, Philipp; Jestoi, Marika; Peltonen, Kimmo; Adam, Gerhard; Lemmens, Marc; Schuhmacher, Rainer; Berthiller, Franz

    2015-09-01

    To investigate the metabolic fate of HT-2 toxin (HT2) and T-2 toxin (T2) in wheat (Triticum aestivum L.), an untargeted metabolomics study utilizing stable isotopic labeling and liquid chromatography-high resolution mass spectrometry was performed. In total, 11 HT2 and 12 T2 derived in planta biotransformation products were annotated putatively. In addition to previously reported mono- and diglucosylated forms of HT2, evidence for the formation of HT2-malonyl-glucoside and feruloyl-T2, as well as acetylation and deacetylation products in wheat was obtained for the first time. To monitor the kinetics of metabolite formation, a time course experiment was conducted involving the Fusarium head blight susceptible variety Remus and the resistant cultivar CM-82036. Biotransformation reactions were observed already at the earliest tested time point (6 h after treatment), and formed metabolites showed different kinetic profiles. After ripening, less than 15% of the toxins added to the plants were determined to be unmetabolized. PMID:26278508

  15. Herbal Compounds and Toxins Modulating TRP Channels

    PubMed Central

    Vriens, Joris; Nilius, Bernd; Vennekens, Rudi

    2008-01-01

    Although the benefits are sometimes obvious, traditional or herbal medicine is regarded with skepticism, because the mechanism through which plant compounds exert their powers are largely elusive. Recent studies have shown however that many of these plant compounds interact with specific ion channels and thereby modulate the sensing mechanism of the human body. Especially members of the Transient Receptor Potential (TRP) channels have drawn large attention lately as the receptors for plant-derived compounds such as capsaicin and menthol. TRP channels constitute a large and diverse family of channel proteins that can serve as versatile sensors that allow individual cells and entire organisms to detect changes in their environment. For this family, a striking number of empirical views have turned into mechanism-based actions of natural compounds. In this review we will give an overview of herbal compounds and toxins, which modulate TRP channels. PMID:19305789

  16. Import and export of bacterial protein toxins.

    PubMed

    Braun, Volkmar; Helbig, Stephanie; Patzer, Silke I; Pramanik, Avijit; Römer, Christin

    2015-02-01

    The paper provides a short overview of three investigated bacterial protein toxins, colicin M (Cma) of Escherichia coli, pesticin (Pst) of Yersinia pestis and hemolysin (ShlAB) of Serratia marcescens. Cma and Pst are exceptional among colicins in that they kill bacteria by degrading the murein (peptidoglycan). Both are released into the medium and bind to specific receptor proteins in the outer membrane of sensitive E. coli cells. Subsequently they are translocated into the periplasm by an energy-consuming process using the proton motive force. For transmembrane translocation the colicins unfold and refold in the periplasm. In the case of Cma the FkpA peptidyl prolyl cis-trans isomerase/chaperone is required. ShlA is secreted and activated through ShlB in the outer membrane by a type Vb secretion mechanism. PMID:25620353

  17. Unifying soil respiration pulses, inhibition, and temperature hysteresis through dynamics of labile soil carbon and O2

    NASA Astrophysics Data System (ADS)

    Oikawa, P. Y.; Grantz, D. A.; Chatterjee, A.; Eberwein, J. E.; Allsman, L. A.; Jenerette, G. D.

    2014-04-01

    Event-driven and diel dynamics of soil respiration (Rs) strongly influence terrestrial carbon (C) emissions and are difficult to predict. Wetting events may cause a large pulse or strong inhibition of Rs. Complex diel dynamics include hysteresis in the relationship between Rs and soil temperature. The mechanistic basis for these dynamics is not well understood, resulting in large discrepancies between predicted and observed Rs. We present a unifying approach for interpreting these phenomena in a hot arid agricultural environment. We performed a whole ecosystem wetting experiment with continuous measurement of Rs to study pulse responses to wetting in a heterotrophic system. We also investigated Rs during cultivation of Sorghum bicolor to evaluate the role of photosynthetic C in the regulation of diel variation in Rs. Finally, we adapted a Rs model with sensitivity to soil O2 and water content by incorporating two soil C pools differing in lability. We observed a large wetting-induced pulse of Rs from the fallow field and were able to accurately simulate the pulse via release of labile soil C. During the exponential phase of plant growth, Rs was inhibited in response to wetting, which was accurately simulated through depletion of soil O2. Without plants, hysteresis was not observed; however, with growing plants, an increasingly significant counterclockwise hysteresis developed. Hysteresis was simulated via a dynamic photosynthetic C pool and was not likely controlled by physical processes. These results help characterize the complex regulation of Rs and improve understanding of these phenomena under warmer and more variable conditions.

  18. Size, speciation and lability of NOM-metal complexes in hyperalkaline cave dripwater

    NASA Astrophysics Data System (ADS)

    Hartland, Adam; Fairchild, Ian J.; Lead, Jamie R.; Zhang, Hao; Baalousha, Mohammed

    2011-12-01

    Transport of trace metals by natural organic matter (NOM) is potentially an important vector for trace metal incorporation in secondary cave precipitates [speleothems], yet little is known about the size distribution, speciation and metal binding properties of NOM in cave dripwaters. A hyperalkaline cave environment (ca. pH 11) was selected to provide information on colloid-metal interactions in cave waters, and to address the lack of high-pH data in natural systems in general. Colloidal (1 nm-1 ?m) NOM in hyperalkaline cave dripwater from Poole's Cavern, UK, was characterised by flow field-flow fractionation (FlFFF) coupled to UV and fluorescence detectors and transmission electron microscopy (TEM) coupled to X-ray energy-dispersive spectroscopy (X-EDS); trace-metal lability was examined by diffusive gradients in thin films (DGT). Colloidal aggregates and small particulates (>1 ?m) imaged by TEM were morphologically heterogeneous with qualitative elemental compositions (X-EDS spectra; n = 41) consistent with NOM aggregates containing aluminosilicates, and iron and titanium oxides. Globular organic colloids, with diameters between ca. 1 and 10 nm were the most numerous colloidal class and exhibited high UV-absorbance (254 nm) and fluorescence intensity (320:400 nm excitation: emission) in optical regions characteristic of humic-like compounds. Metal binding with humic substances was modelled using the WHAM 6.1 (model VI) and visual MINTEQ 3.0 (NICA-Donnan) speciation codes. At pH 11, both models predicted dominant humic binding of Cu (ca. 100%) and minimal binding of Ni and Co (ca. <1-7%). A DGT depletion experiment (7 days duration) with the hyperalkaline dripwater showed that the available proportion of each metal was much lower than its total concentration. Metal availability for DGT in the initial stages (24 h) was consistent with weaker binding of alkaline earth metals by humic substances (Ba > Sr > V > Cu > Ni > Co), compared to the transition metals. Integrated over the entire experiment, the DGT-available proportion of transition metals (Ni > Cu & V >> Co) differed greatly from the expected hierarchy from WHAM and MINTEQ, indicating unusually strong complexation of Co. Total metal concentrations of Cu, Ni, and Co in raw and filtered PE1 dripwater samples ( n = 53) were well correlated (Cu vs. Ni, R2 = 0.8; Cu vs. Co, R2 = 0.5) and were strongly reduced (> ca. 50%) by filtration at ca. 100 and 1 nm, indicating a common colloidal association. Our results demonstrate that soil-derived colloids reach speleothems, despite transport through a karst zone with potential for adsorption, and that NOM is a dominant complexant of trace metals in high pH speleothem-forming groundwaters.

  19. Algal toxins alter copepod feeding behavior.

    PubMed

    Hong, Jiarong; Talapatra, Siddharth; Katz, Joseph; Tester, Patricia A; Waggett, Rebecca J; Place, Allen R

    2012-01-01

    Using digital holographic cinematography, we quantify and compare the feeding behavior of free-swimming copepods, Acartia tonsa, on nutritional prey (Storeatula major) to that occurring during exposure to toxic and non-toxic strains of Karenia brevis and Karlodinium veneficum. These two harmful algal species produce polyketide toxins with different modes of action and potency. We distinguish between two different beating modes of the copepod's feeding appendages-a "sampling beating" that has short durations (<100 ms) and involves little fluid entrainment and a longer duration "grazing beating" that persists up to 1200 ms and generates feeding currents. The durations of both beating modes have log-normal distributions. Without prey, A. tonsa only samples the environment at low frequency. Upon introduction of non-toxic food, it increases its sampling time moderately and the grazing period substantially. On mono algal diets for either of the toxic dinoflagellates, sampling time fraction is high but the grazing is very limited. A. tonsa demonstrates aversion to both toxic algal species. In mixtures of S. major and the neurotoxin producing K. brevis, sampling and grazing diminish rapidly, presumably due to neurological effects of consuming brevetoxins while trying to feed on S. major. In contrast, on mixtures of cytotoxin producing K. veneficum, both behavioral modes persist, indicating that intake of karlotoxins does not immediately inhibit the copepod's grazing behavior. These findings add critical insight into how these algal toxins may influence the copepod's feeding behavior, and suggest how some harmful algal species may alter top-down control exerted by grazers like copepods. PMID:22629336

  20. Algal Toxins Alter Copepod Feeding Behavior

    PubMed Central

    Hong, Jiarong; Talapatra, Siddharth; Katz, Joseph; Tester, Patricia A.; Waggett, Rebecca J.; Place, Allen R.

    2012-01-01

    Using digital holographic cinematography, we quantify and compare the feeding behavior of free-swimming copepods, Acartia tonsa, on nutritional prey (Storeatula major) to that occurring during exposure to toxic and non-toxic strains of Karenia brevis and Karlodinium veneficum. These two harmful algal species produce polyketide toxins with different modes of action and potency. We distinguish between two different beating modes of the copepod’s feeding appendages–a “sampling beating” that has short durations (<100 ms) and involves little fluid entrainment and a longer duration “grazing beating” that persists up to 1200 ms and generates feeding currents. The durations of both beating modes have log-normal distributions. Without prey, A. tonsa only samples the environment at low frequency. Upon introduction of non-toxic food, it increases its sampling time moderately and the grazing period substantially. On mono algal diets for either of the toxic dinoflagellates, sampling time fraction is high but the grazing is very limited. A. tonsa demonstrates aversion to both toxic algal species. In mixtures of S. major and the neurotoxin producing K. brevis, sampling and grazing diminish rapidly, presumably due to neurological effects of consuming brevetoxins while trying to feed on S. major. In contrast, on mixtures of cytotoxin producing K. veneficum, both behavioral modes persist, indicating that intake of karlotoxins does not immediately inhibit the copepod’s grazing behavior. These findings add critical insight into how these algal toxins may influence the copepod’s feeding behavior, and suggest how some harmful algal species may alter top-down control exerted by grazers like copepods. PMID:22629336

  1. Botulinum Toxin Physiology in Focal Hand and Cranial Dystonia

    PubMed Central

    Karp, Barbara Illowsky

    2012-01-01

    The safety and efficacy of botulinum toxin for the treatment of focal hand and cranial dystonias are well-established. Studies of these adult-onset focal dystonias reveal both shared features, such as the dystonic phenotype of muscle hyperactivity and overflow muscle contraction and divergent features, such as task specificity in focal hand dystonia which is not a common feature of cranial dystonia. The physiologic effects of botulinum toxin in these 2 disorders also show both similarities and differences. This paper compares and contrasts the physiology of focal hand and cranial dystonias and of botulinum toxin in the management of these disorders. PMID:23202323

  2. Biosecurity reference : CFR-listed agent and toxin summaries.

    SciTech Connect

    Barnett, Natalie Beth

    2003-09-01

    This reference document provides summary information on the animal, plant, zoonotic, and human pathogens and toxins regulated and categorized by 9 CFR 331 and 7 CFR 121, 'Agricultural Bioterrorism Protection Act of 2002; Possession, Use and Transfer of Biological Agents and Toxins,' and 42 CFR 73, 'Possession, Use, and Transfer of Select Agents and Toxins.' Summary information includes, at a minimum, a description of the agent and its associated symptoms; often additional information is provided on the diagnosis, treatment, geographic distribution, transmission, control and eradication, and impacts on public health.

  3. Heat pipe array heat exchanger

    DOEpatents

    Reimann, Robert C. (Lafayette, NY)

    1987-08-25

    A heat pipe arrangement for exchanging heat between two different temperature fluids. The heat pipe arrangement is in a ounterflow relationship to increase the efficiency of the coupling of the heat from a heat source to a heat sink.

  4. Improved PE-based Targeted Toxins: A Therapeutic with Increased Effectiveness

    Cancer.gov

    A particular toxin that has been used in targeted toxins is Pseudomonas exotoxin A (PE). The effectiveness of PE-containing targeted toxins has been demonstrated against various forms of cancer, including hairy cell leukemia (HCL) and pediatric acute lymphocytic leukemia (pALL). Although early variations these targeted toxins have demonstrated efficacy upon first administration, the continued administration of a targeted toxin often leads to a reduced patient response.

  5. Anomericity of T-2 toxin-glucoside: masked mycotoxin in cereal crops.

    PubMed

    McCormick, Susan P; Kato, Takayuki; Maragos, Chris M; Busman, Mark; Lattanzio, Veronica M T; Galaverna, Gianni; Dall-Asta, Chiara; Crich, David; Price, Neil P J; Kurtzman, Cletus P

    2015-01-21

    T-2 toxin is a trichothecene mycotoxin produced when Fusarium fungi infect grains, especially oats and wheat. Ingestion of T-2 toxin contaminated grain can cause diarrhea, hemorrhaging, and feed refusal in livestock. Cereal crops infected with mycotoxin-producing fungi form toxin glycosides, sometimes called masked mycotoxins, which are a potential food safety concern because they are not detectable by standard approaches and may be converted back to the parent toxin during digestion or food processing. The work reported here addresses four aspects of T-2 toxin-glucosides: phytotoxicity, stability after ingestion, antibody detection, and the anomericity of the naturally occurring T-2 toxin-glucoside found in cereal plants. T-2 toxin-?-glucoside was chemically synthesized and compared to T-2 toxin-?-glucoside prepared with Blastobotrys muscicola cultures and the T-2 toxin-glucoside found in naturally contaminated oats and wheat. The anomeric forms were separated chromatographically and differ in both NMR and mass spectrometry. Both anomers were significantly degraded to T-2 toxin and HT-2 toxin under conditions that mimic human digestion, but with different kinetics and metabolic end products. The naturally occurring T-2 toxin-glucoside from plants was found to be identical to T-2 toxin-?-glucoside prepared with B. muscicola. An antibody test for the detection of T-2 toxin was not effective for the detection of T-2 toxin-?-glucoside. This anomer was produced in sufficient quantity to assess its animal toxicity. PMID:25520274

  6. DEVELOPMENT OF A HUMAN BIOMARKER FOR CYANOBACTERIAL TOXINS- MICROCYSTINS

    EPA Science Inventory

    Increasingly, cyanobacterial blooms are being reported worldwide due to several factors: eutrophication, climate change, and potentially greater scientific awareness and detection. During 1996, an outbreak of fatal cyanobacterial toxin intoxications occurred among a group of dia...

  7. 7 CFR 331.3 - PPQ select agents and toxins.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...elements, recombinant nucleic acids, and recombinant organisms: (1) Nucleic acids that can produce infectious...in paragraph (b) of this section that have been genetically modified. (d) Select agents or toxins that meet...

  8. 7 CFR 331.3 - PPQ select agents and toxins.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...elements, recombinant nucleic acids, and recombinant organisms: (1) Nucleic acids that can produce infectious...in paragraph (b) of this section that have been genetically modified. (d) Select agents or toxins that meet...

  9. 42 CFR 73.4 - Overlap select agents and toxins.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...Elements, Recombinant Nucleic Acids, and Recombinant Organisms: (1) Nucleic acids that can produce infectious...in paragraph (b) of this section that have been genetically modified. (d) Overlap select agents or toxins that...

  10. 9 CFR 121.4 - Overlap select agents and toxins.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...TOXINS, AND ANALOGOUS PRODUCTS; ORGANISMS AND VECTORS POSSESSION, USE...nucleic acids, and recombinant organisms: (1) Nucleic acids that...of this section that have been genetically modified. (d) Overlap select...

  11. 42 CFR 73.4 - Overlap select agents and toxins.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...Elements, Recombinant Nucleic Acids, and Recombinant Organisms: (1) Nucleic acids that can produce infectious...in paragraph (b) of this section that have been genetically modified. (d) Overlap select agents or toxins that...

  12. 9 CFR 121.4 - Overlap select agents and toxins.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...TOXINS, AND ANALOGOUS PRODUCTS; ORGANISMS AND VECTORS POSSESSION, USE...nucleic acids, and recombinant organisms: (1) Nucleic acids that...of this section that have been genetically modified. (d) Overlap select...

  13. Interactions between Autophagy and Bacterial Toxins: Targets for Therapy?

    PubMed Central

    Mathieu, Jacques

    2015-01-01

    Autophagy is a physiological process involved in defense mechanisms for clearing intracellular bacteria. The autophagic pathway is finely regulated and bacterial toxins interact with this process in a complex manner. Bacterial toxins also interact significantly with many biochemical processes. Evaluations of the effects of bacterial toxins, such as endotoxins, pore-forming toxins and adenylate cyclases, on autophagy could support the development of new strategies for counteracting bacterial pathogenicity. Treatment strategies could focus on drugs that enhance autophagic processes to improve the clearance of intracellular bacteria. However, further in vivo studies are required to decipher the upregulation of autophagy and potential side effects limiting such approaches. The capacity of autophagy activation strategies to improve the outcome of antibiotic treatment should be investigated in the future. PMID:26248079

  14. Botulinum Toxin Injection for Spastic Scapular Dyskinesia After Stroke

    PubMed Central

    Hou, Saiyun; Ivanhoe, Cindy; Li, Sheng

    2015-01-01

    Abstract Spastic scapular dyskinesia after stroke is rare, which causes impaired shoulder active range of motion (ROM). To date, there has been no report about botulinum toxin injection to spastic periscapular muscles. This study presents botulinum toxin A injection for management of spastic periscapular muscles after stroke in 2 cases. This is a retrospective study of 2 cases of spastic scapular dyskinesia after stroke. Spasticity of periscapular muscles including rhomboid and lower trapezius was diagnosed by physical examination and needle electromyographic study. Botulinum toxin was injected into the spastic periscapular muscles under ultrasound imaging guidance. During the 3-week follow-up visit after injection, both patients showed increased shoulder active ROM, without any sign of scapular destabilization. The results suggest that botulinum toxin injection to spastic periscapular muscles can increase shoulder active ROM without causing scapular destabilization in patients with poststroke spastic scapular dyskinesia. PMID:26266368

  15. Shellfish Toxins Targeting Voltage-Gated Sodium Channels

    PubMed Central

    Zhang, Fan; Xu, Xunxun; Li, Tingting; Liu, Zhonghua

    2013-01-01

    Voltage-gated sodium channels (VGSCs) play a central role in the generation and propagation of action potentials in excitable neurons and other cells and are targeted by commonly used local anesthetics, antiarrhythmics, and anticonvulsants. They are also common targets of neurotoxins including shellfish toxins. Shellfish toxins are a variety of toxic secondary metabolites produced by prokaryotic cyanobacteria and eukaryotic dinoflagellates in both marine and fresh water systems, which can accumulate in marine animals via the food chain. Consumption of shellfish toxin-contaminated seafood may result in potentially fatal human shellfish poisoning. This article provides an overview of the structure, bioactivity, and pharmacology of shellfish toxins that act on VGSCs, along with a brief discussion on their pharmaceutical potential for pain management. PMID:24287955

  16. Identification of the cellular receptor for anthrax toxin

    NASA Astrophysics Data System (ADS)

    Bradley, Kenneth A.; Mogridge, Jeremy; Mourez, Michael; Collier, R. John; Young, John A. T.

    2001-11-01

    The tripartite toxin secreted by Bacillus anthracis, the causative agent of anthrax, helps the bacterium evade the immune system and can kill the host during a systemic infection. Two components of the toxin enzymatically modify substrates within the cytosol of mammalian cells: oedema factor (OF) is an adenylate cyclase that impairs host defences through a variety of mechanisms including inhibiting phagocytosis; lethal factor (LF) is a zinc-dependent protease that cleaves mitogen-activated protein kinase kinase and causes lysis of macrophages. Protective antigen (PA), the third component, binds to a cellular receptor and mediates delivery of the enzymatic components to the cytosol. Here we describe the cloning of the human PA receptor using a genetic complementation approach. The receptor, termed ATR (anthrax toxin receptor), is a type I membrane protein with an extracellular von Willebrand factor A domain that binds directly to PA. In addition, a soluble version of this domain can protect cells from the action of the toxin.

  17. 7 CFR 331.3 - PPQ select agents and toxins.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...) Select agents and toxins listed in paragraph (b) of this section that have been genetically modified. (d... variegated chlorosis strain). (c) Genetic elements, recombinant nucleic acids, and recombinant organisms:...

  18. 7 CFR 331.3 - PPQ select agents and toxins.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...) Select agents and toxins listed in paragraph (b) of this section that have been genetically modified. (d... variegated chlorosis strain). (c) Genetic elements, recombinant nucleic acids, and recombinant organisms:...

  19. 7 CFR 331.3 - PPQ select agents and toxins.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... (b) of this section that have been genetically modified. (d) Select agents or toxins that meet any of..., and recombinant and/or synthetic organisms: (1) Nucleic acids that can produce infectious forms of...

  20. 7 CFR 331.3 - PPQ select agents and toxins.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...) Select agents and toxins listed in paragraph (b) of this section that have been genetically modified. (d... variegated chlorosis strain). (c) Genetic elements, recombinant nucleic acids, and recombinant organisms:...

  1. 7 CFR 331.3 - PPQ select agents and toxins.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... (b) of this section that have been genetically modified. (d) Select agents or toxins that meet any of..., and recombinant and/or synthetic organisms: (1) Nucleic acids that can produce infectious forms of...

  2. 7 CFR 331.3 - PPQ select agents and toxins.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...elements, recombinant nucleic acids, and recombinant organisms: (1) Nucleic acids that can produce infectious...in paragraph (b) of this section that have been genetically modified. (d) Select agents or toxins that meet...

  3. 42 CFR 73.4 - Overlap select agents and toxins.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...Nucleic Acids, and Recombinant and/or Synthetic Organisms: (1) Nucleic acids that can produce infectious...in paragraph (b) of this section that have been genetically modified. (d) Overlap select agents or toxins that...

  4. 9 CFR 121.4 - Overlap select agents and toxins.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...TOXINS, AND ANALOGOUS PRODUCTS; ORGANISMS AND VECTORS POSSESSION, USE...recombinant and/or synthetic organisms: (1) Nucleic acids that...of this section that have been genetically modified. (d) Overlap select...

  5. 7 CFR 331.3 - PPQ select agents and toxins.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...nucleic acids, and recombinant and/or synthetic organisms: (1) Nucleic acids that can produce infectious...in paragraph (b) of this section that have been genetically modified. (d) Select agents or toxins that meet...

  6. 9 CFR 121.4 - Overlap select agents and toxins.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...TOXINS, AND ANALOGOUS PRODUCTS; ORGANISMS AND VECTORS POSSESSION, USE...recombinant and/or synthetic organisms: (1) Nucleic acids that...of this section that have been genetically modified. (d) Overlap select...

  7. 9 CFR 121.4 - Overlap select agents and toxins.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...TOXINS, AND ANALOGOUS PRODUCTS; ORGANISMS AND VECTORS POSSESSION, USE...nucleic acids, and recombinant organisms: (1) Nucleic acids that...of this section that have been genetically modified. (d) Overlap select...

  8. 42 CFR 73.4 - Overlap select agents and toxins.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...Elements, Recombinant Nucleic Acids, and Recombinant Organisms: (1) Nucleic acids that can produce infectious...in paragraph (b) of this section that have been genetically modified. (d) Overlap select agents or toxins that...

  9. 7 CFR 331.3 - PPQ select agents and toxins.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...nucleic acids, and recombinant and/or synthetic organisms: (1) Nucleic acids that can produce infectious...in paragraph (b) of this section that have been genetically modified. (d) Select agents or toxins that meet...

  10. Comparison of enrichment procedures for shiga toxin-producing Escherichia coli in wastes from commercial swine farms.

    PubMed

    Grant, Michael A; Mogler, Mark A; Harris, Delbert L

    2009-09-01

    Three methods for enrichment of Shiga toxin-producing Escherichia coli (STEC) were compared using waste pit samples from swine production facilities housing 50 to 3,000 animals. The STEC gene stx2 was detected in 5 of 17 pooled samples using a U.S. Department of Agriculture (USDA) enrichment procedure, 6 of 17 samples using a U.S. Food and Drug Administration (FDA) enrichment procedure, and 8 of 17 samples using an experimental acid enrichment. All isolates were non-O157 and 5 of 6 were positive for enterotoxigenic E. coli-associated heat stable toxins a and b. The three enrichment procedures were also tested for their ability to support growth of 31 strains of STEC. The acid enrichment media supported growth of 100% of the strains, the FDA medium supported 77% of the strains, and the USDA medium supported 16% of the strains. PMID:19777903

  11. A New Type of Toxin A-Negative, Toxin B-Positive Clostridium difficile Strain Lacking a Complete tcdA Gene

    PubMed Central

    Marín, Mercedes; Martín, Adoración; Rupnik, Maja

    2014-01-01

    Toxins A and B are the main virulence factors of Clostridium difficile and are the targets for molecular diagnostic tests. Here, we describe a new toxin A-negative, toxin B-positive, binary toxin CDT (Clostridium difficile transferase)-negative (A? B+ CDT?) toxinotype (XXXII) characterized by a variant type of pathogenicity locus (PaLoc) without tcdA and with atypical organization of the PaLoc integration site. PMID:25428159

  12. [Effects of the different land use on soil labile organic matter and carbon management index in Junyun Mountain].

    PubMed

    Xu, Peng; Jiang, Chang-Sheng; Hao, Qing-Ju; Zhu, Tao

    2013-10-01

    The impacts of different land use on soil organic matter (SOM), soil labile organic matter (SLOM) and their efficiency ratios (ER), and soil carbon management index (CMI) were studied in this study. Subtropical evergreen broad-leaved forest (abbreviation: forest) , sloping farmland, orchard and abandoned land were selected and soils at the depths of 0-10, 10-20, 20-30, 30-40, 40-50 and 50-60 cm were sampled in the spring of 2011 to determine the contents of soil organic matter and labile organic matter. The results showed that the contents of soil organic matter and soil labile organic matter both decreased with the increase of soil depth under all four land use types; however, forest and orchard enriched SOM and SLOM contents in the 0-10 cm and 0-20 cm soil layers, respectively, while the contents of SOM and SLOM decreased evenly in sloping farmland and abandoned land. In the whole soil layer (0-60 cm) , the order of SOM and SLOM contents was abandoned land > forest > orchard > sloping farmland, indicating that at the conversion from forest into orchard or sloping farmland, SOM was reduced by 21.56% (P >0.05) and 55.90% (P <0.05), respectively, and at the conversion from sloping farmland into abandoned land, the low SLOM, middle SLOM and high SLOM increased by 144.2% (P<0.05) , 153.3% (P <0.05) and 242.7% (P <0.05), respectively. There was no significant difference in low ER, middle ER and high ER among the four land uses as suggested by ANOVA which showed that SRs were not sensible to the change of land use. All three CMis were in the order of abandoned land > forest > orchard > sloping farmland, revealing that forest reclamation resulted in the reduction of soil organic carbon storage and the decline of soil quality, and the abandonment of sloping farmland would increase soil carbon sink and improve soil quality. Three kinds of SLOM were all positively correlated with soil total nitrogen, available phosphorus and available potassium, while negatively correlated with soil density bulk, indicating that SLOM had close relationships with soil physical and chemical characters and could be used as an important index to reflect soil nutrient status and judge soil quality. PMID:24364324

  13. Identification and Characterization of a Novel Staphylococcal Emetic Toxin.

    PubMed

    Ono, Hisaya K; Sato'o, Yusuke; Narita, Kouji; Naito, Ikunori; Hirose, Shouhei; Hisatsune, Junzo; Asano, Krisana; Hu, Dong-Liang; Omoe, Katsuhiko; Sugai, Motoyuki; Nakane, Akio

    2015-10-01

    Staphylococcal enterotoxins (SEs) produced by Staphylococcus aureus have superantigenic and emetic activities, which cause toxic shock syndrome and staphylococcal food poisoning, respectively. Our previous study demonstrated that the sequence of SET has a low level of similarity to the sequences of other SEs and exhibits atypical bioactivities. Hence, we further explored whether there is an additional SET-related gene in S. aureus strains. One SET-like gene was found in the genome of S. aureus isolates that originated from a case of food poisoning, a human nasal swab, and a case of bovine mastitis. The deduced amino acid sequence of the SET-like gene showed 32% identity with the amino acid sequence of SET. The SET-like gene product was designated SElY. In the food poisoning and nasal swab isolates, mRNA encoding SElY was highly expressed in the early log phase of cultivation, whereas a high level of expression of this mRNA was found in the bovine mastitis isolate at the early stationary phase. To estimate whether SElY has both superantigenic and emetic activities, recombinant SElY was prepared. Cell proliferation and cytokine production were examined to assess the superantigenic activity of SElY. SElY exhibited superantigenic activity in human peripheral blood mononuclear cells but not in mouse splenocytes. In addition, SElY exhibited emetic activity in house musk shrews after intraperitoneal and oral administration. However, the stability of SElY against heating and pepsin and trypsin digestion was different from that of SET and SEA. From these results, we identified SElY to be a novel staphylococcal emetic toxin. PMID:26231643

  14. Uptake and bioaccumulation of Cry toxins by an aphidophagous predator.

    PubMed

    Paula, Débora P; Andow, David A

    2016-02-01

    Uptake of Cry toxins by insect natural enemies has rarely been considered and bioaccumulation has not yet been demonstrated. Uptake can be demonstrated by the continued presence of Cry toxin after exposure has stopped and gut contents eliminated. Bioaccumulation can be demonstrated by showing uptake and that the concentration of Cry toxin in the natural enemy exceeds that in its food. We exposed larvae of the aphidophagous predator, Harmonia axyridis, to Cry1Ac and Cry1F through uniform and constant tritrophic exposure via an aphid, Myzus persicae, and looked for toxin presence in the pupae. We repeated the experiment using only Cry1F and tested newly emerged adults. Both Cry toxins were detected in pupae, and Cry1F was detected in recently emerged, unfed adults. Cry1Ac was present 2.05 times and Cry1F 3.09 times higher in predator pupae than in the aphid prey. Uptake and bioaccumulation in the third trophic level might increase the persistence of Cry toxins in the food web and mediate new exposure routes to natural enemies. PMID:26686057

  15. Binary Toxin and Death after Clostridium difficile Infection

    PubMed Central

    Mølbak, Kåre; Kjeldsen, Marianne K.; Olsen, Katharina E.P.

    2011-01-01

    We compared 30-day case-fatality rates for patients infected with Clostridium difficile possessing genes for toxins A and B without binary toxin (n = 212) with rates for patients infected with C. difficile possessing genes for A, B, and binary toxin. The latter group comprised patients infected with strains of PCR ribotype 027 (CD027, n = 193) or non-027 (CD non-027, n = 72). Patients with binary toxin had higher case-fatality rates than patients without binary toxin, in univariate analysis (relative risk [RR] 1.8, 95% confidence interval [CI] 1.2–2.7) and multivariate analysis after adjustment for age, sex, and geographic region (RR 1.6, 95% CI 1.0–2.4). Similar case-fatality rates (27.8%, 28.0%) were observed for patients infected with CD027 or CD non-027. Binary toxin either is a marker for more virulent C. difficile strains or contributes directly to strain virulence. Efforts to control C. difficile infection should target all virulent strains irrespective of PCR ribotype. PMID:21749757

  16. Cloning and expression of functional fragment C of tetanus toxin.

    PubMed Central

    Halpern, J L; Habig, W H; Neale, E A; Stibitz, S

    1990-01-01

    A segment of Clostridium tetani DNA corresponding to fragment C of tetanus toxin was amplified by using the polymerase chain reaction. This fragment was cloned into expression vector pTTQ8, under the control of the tac promoter. Expression of this plasmid in Escherichia coli resulted in the production of a protein consisting of 8 amino acids of the vector fused to the C-terminal 460 amino acids of tetanus toxin. This protein (rFragment C) was recognized by an antipeptide antibody specific for fragment C in an enzyme-linked immunosorbent assay and on immunoblots. rFragment C could be purified significantly in one step by immunoaffinity chromatography. Immunization of mice with rFragment C resulted in the production of antibodies that were able to protect the mice against a challenge with tetanus toxin. rFragment C bound to ganglioside GT1b and to neuronal cells in a manner indistinguishable from that of fragment C obtained by papain cleavage of tetanus toxin. For many applications, rFragment C appears to be a suitable alternative to tetanus toxin or toxin-derived fragment C. Images PMID:2318526

  17. Toxin gene determination and evolution in scorpaenoid fish.

    PubMed

    Chuang, Po-Shun; Shiao, Jen-Chieh

    2014-09-01

    In this study, we determine the toxin genes from both cDNA and genomic DNA of four scorpaenoid fish and reconstruct their evolutionary relationship. The deduced protein sequences of the two toxin subunits in Sebastapistes strongia, Scorpaenopsis oxycephala, and Sebastiscus marmoratus are about 700 amino acid, similar to the sizes of the stonefish (Synanceia horrida, and Synanceia verrucosa) and lionfish (Pterois antennata and Pterois volitans) toxins previously published. The intron positions are highly conserved among these species, which indicate the applicability of gene finding by using genomic DNA template. The phylogenetic analysis shows that the two toxin subunits were duplicated prior to the speciation of Scorpaenoidei. The precedence of the gene duplication over speciation indicates that the toxin genes may be common to the whole family of Scorpaeniform. Furthermore, one additional toxin gene has been determined in the genomic DNA of Dendrochirus zebra. The phylogenetic analysis suggests that an additional gene duplication occurred before the speciation of the lionfish (Pteroinae) and a pseudogene may be generally present in the lineage of lionfish. PMID:24950049

  18. A new family of secreted toxins in pathogenic Neisseria species.

    PubMed

    Jamet, Anne; Jousset, Agnès B; Euphrasie, Daniel; Mukorako, Paulette; Boucharlat, Alix; Ducousso, Alexia; Charbit, Alain; Nassif, Xavier

    2015-01-01

    The genus Neisseria includes both commensal and pathogenic species which are genetically closely related. However, only meningococcus and gonococcus are important human pathogens. Very few toxins are known to be secreted by pathogenic Neisseria species. Recently, toxins secreted via type V secretion system and belonging to the widespread family of contact-dependent inhibition (CDI) toxins have been described in numerous species including meningococcus. In this study, we analyzed loci containing the maf genes in N. meningitidis and N. gonorrhoeae and proposed a novel uniform nomenclature for maf genomic islands (MGIs). We demonstrated that mafB genes encode secreted polymorphic toxins and that genes immediately downstream of mafB encode a specific immunity protein (MafI). We focused on a MafB toxin found in meningococcal strain NEM8013 and characterized its EndoU ribonuclease activity. maf genes represent 2% of the genome of pathogenic Neisseria, and are virtually absent from non-pathogenic species, thus arguing for an important biological role. Indeed, we showed that overexpression of one of the four MafB toxins of strain NEM8013 provides an advantage in competition assays, suggesting a role of maf loci in niche adaptation. PMID:25569427

  19. Toxin studies using an integrated biophysical and structural biology approach.

    SciTech Connect

    Last, Julie A.; Schroeder, Anne E.; Slade, Andrea Lynn; Sasaki, Darryl Yoshio; Yip, Christopher M.; Schoeniger, Joseph S.

    2005-03-01

    Clostridial neurotoxins, such as botulinum and tetanus, are generally thought to invade neural cells through a process of high affinity binding mediated by gangliosides, internalization via endosome formation, and subsequent membrane penetration of the catalytic domain activated by a pH drop in the endosome. This surface recognition and internalization process is still not well understood with regard to what specific membrane features the toxins target, the intermolecular interactions between bound toxins, and the molecular conformational changes that occur as a result of pH lowering. In an effort to elucidate the mechanism of tetanus toxin binding and permeation through the membrane a simple yet representative model was developed that consisted of the ganglioside G{sub tlb} incorporated in a bilayer of cholesterol and DPPC (dipalmitoylphosphatidyl choline). The bilayers were stable over time yet sensitive towards the binding and activity of whole toxin. A liposome leakage study at constant pH as well as with a pH gradient, to mimic the processes of the endosome, was used to elucidate the effect of pH on the toxin's membrane binding and permeation capability. Topographic imaging of the membrane surface, via in situ tapping mode AFM, provided nanoscale characterization of the toxin's binding location and pore formation activity.

  20. Toxins induce 'malaise' behaviour in the honeybee (Apis mellifera).

    PubMed

    Hurst, Victoria; Stevenson, Philip C; Wright, Geraldine A

    2014-10-01

    To avoid poisoning and death when toxins are ingested, the body responds with a suite of physiological detoxification mechanisms accompanied by behaviours that in mammals often include vomiting, nausea, and lethargy. Few studies have characterised whether insects exhibit characteristic 'malaise-like' behaviours in response to intoxication. Here, we used the honeybee to investigate how intoxication produced by injection or ingestion with three toxins with different pharmacological modes of action quinine, amygdalin, and lithium chloride affected behaviour. We found that toxin-induced changes in behaviour were best characterised by more time spent grooming. Bees also had difficulty performing the righting reflex and exhibited specific toxin-induced behaviours such as abdomen dragging and curling up. The expression of these behaviours also depended on whether a toxin had been injected or ingested. When toxins were ingested, they were least 10 times less concentrated in the haemolymph than in the ingested food, suggesting that their absorption through the gut is strongly regulated. Our data show that bees exhibit changes in behaviour that are characteristic of 'malaise' and suggest that physiological signalling of toxicosis is accomplished by multiple post-ingestive pathways in animals. PMID:25149875

  1. Tracing the metabolism of HT-2 toxin and T-2 toxin in barley by isotope-assisted untargeted screening and quantitative LC-HRMS analysis.

    PubMed

    Meng-Reiterer, Jacqueline; Varga, Elisabeth; Nathanail, Alexis V; Bueschl, Christoph; Rechthaler, Justyna; McCormick, Susan P; Michlmayr, Herbert; Malachová, Alexandra; Fruhmann, Philipp; Adam, Gerhard; Berthiller, Franz; Lemmens, Marc; Schuhmacher, Rainer

    2015-10-01

    An extensive study of the metabolism of the type A trichothecene mycotoxins HT-2 toxin and T-2 toxin in barley using liquid chromatography coupled to high-resolution mass spectrometry (LC-HRMS) is reported. A recently developed untargeted approach based on stable isotopic labelling, LC-Orbitrap-MS analysis with fast polarity switching and data processing by MetExtract software was combined with targeted LC-Q-TOF-MS(/MS) analysis for metabolite structure elucidation and quantification. In total, 9 HT-2 toxin and 13 T-2 toxin metabolites plus tentative isomers were detected, which were successfully annotated by calculation of elemental formulas and further LC-HRMS/MS measurements as well as partly identified with authentic standards. As a result, glucosylated forms of the toxins, malonylglucosides, and acetyl and feruloyl conjugates were elucidated. Additionally, time courses of metabolite formation and mass balances were established. For absolute quantification of those compounds for which standards were available, the method was validated by determining apparent recovery, signal suppression, or enhancement and extraction recovery. Most importantly, T-2 toxin was rapidly metabolised to HT-2 toxin and for both parent toxins HT-2 toxin-3-O-?-glucoside was identified (confirmed by authentic standard) as the main metabolite, which reached its maximum already 1 day after toxin treatment. Graphical Abstract Isotope-assisted untargeted screening of HT-2 toxin and T-2 toxin metabolites in barley. PMID:26335000

  2. INVITED REVIEW ABSTRACT: Botulinum toxins are among the most potent neurotoxins known to humans. In the past 25 years, botulinum toxin has emerged as

    E-print Network

    Pullman, Seth L.

    INVITED REVIEW ABSTRACT: Botulinum toxins are among the most potent neurotoxins known to humans. In the past 25 years, botulinum toxin has emerged as both a potential weapon of bioterrorism and as a powerful therapeutic agent, with growing applications in neurological and non-neurological disease. Botulinum toxin

  3. Cyanobacteria toxins in the Salton Sea

    PubMed Central

    Carmichael, Wayne W; Li, RenHui

    2006-01-01

    Background The Salton Sea (SS) is the largest inland body of water in California: surface area 980 km2, volume 7.3 million acre-feet, 58 km long, 14–22 km wide, maximum depth 15 m. Located in the southeastern Sonoran desert of California, it is 85 m below sea level at its lowest point. It was formed between 1905 and 1907 from heavy river flows of the Colorado River. Since its formation, it has attracted both people and wildlife, including flocks of migratory birds that have made the Salton Sea a critical stopover on the Pacific flyway. Over the past 15 years wintering populations of eared grebe (Podiceps nigricollis) at the Salton Sea, have experienced over 200,000 mortalities. The cause of these large die-offs remains unknown. The unique environmental conditions of the Salton Sea, including salinities from brackish freshwater at river inlets to hypersaline conditions, extreme daily summer temperatures (>38°C), and high nutrient loading from rivers and agricultural drainage favor eutrophic conditions that encourage algal blooms throughout the year. A significant component of these algal blooms are the prokaryotic group – the Cyanophyta or blue-green algae (also called Cyanobacteria). Since many Cyanobacteria produce toxins (the cyanotoxins) it became important to evaluate their presence and to determine if they are a contributing factor in eared-grebe mortalities at the Salton Sea. Results From November 1999 to April 2001, 247 water and sediment samples were received for phytoplankton identification and cyanotoxin analyses. Immunoassay (ELISA) screening of these samples found that eighty five percent of all water samples contained low but detectable levels of the potent cyclic peptide liver toxin called microcystins. Isolation and identification of cyanobacteria isolates showed that the picoplanktonic Synechococcus and the benthic filamentous Oscillatoria were dominant. Both organisms were found to produce microcystins dominated by microcystin-LR and YR. A laboratory strain of Synechococcus was identified by PCR as being closest to known marine forms of this genus. Analyses of affected grebe livers found microcystins at levels that may account for some of the acute mortalities. Conclusion The production of microcystins by a marine Synechococcus indicates that microcystins may be a more common occurrence in marine environments – a finding not recognized before this work. Further research should be done to define the distribution of microcystin producing marine cyanobacteria and to determine exposure/response effects of microcystins and possibly other cyanotoxins in the Salton Sea. Future efforts to reduce avian mortalities and remediate the Salton Sea should evaluate vectors by which microcystins enter avian species and ways to control and mitigate toxic cyanobacteria waterblooms at the Salton Sea. PMID:16623944

  4. Bacterial toxin modulation of the eukaryotic cell cycle: are all cytolethal distending toxins created equally?

    PubMed Central

    Gargi, Amandeep; Reno, Michael; Blanke, Steven R.

    2012-01-01

    The cytolethal distending toxins (CDTs) comprise a family of intracellular-acting bacterial protein toxins whose actions upon eukaryotic cells result in several consequences, the most characteristic of which is the induction of G2/M cell cycle arrest. Most CDTs are hetero-tripartite assemblies of CdtA, CdtB, and CdtC, with CdtB required for CDT-mediated cell cycle arrest. Several lines of evidence indicate that CdtA and CdtC are required for the optimal intracellular activity of CdtB, although the exact functional roles of CdtA and CdtC remain poorly understood. The genes encoding the CDTs have been identified in a diverse array of Gram-negative pathogenic bacteria. More recently, the genes encoding several CdtB subunits have been associated with alternatively linked subunits resembling the B-subunits of pertussis toxin. Although the CDTs are generally considered to all function as bacterial genotoxins, the extent to which individual members of the CDTs employ similar mechanisms of cell surface binding, uptake, and trafficking within sensitive cells is poorly understood. Recently, data have begun to emerge suggesting differences in the molecular basis by which individual CDTs interact with and enter host cells, suggesting the possibility that CDTs possess properties reflecting the specific niches idiosyncratic to those CDT bacterial pathogens that produce them. The extent to which functional differences between individual CDTs reflect the specific requirements for intoxicating cells and tissues within the diverse range of host microenvironments colonized by CDT-producing pathogenic bacteria remains to be experimentally explored. PMID:23061054

  5. Inactivation of the pore-forming toxin Sticholysin I by peroxynitrite: protection by cys groups incorporated in the toxin.

    PubMed

    León, L; Lissi, E A; Celedón, G; Gonzalez, G; Pazos, F; Alvarez, C; Lanio, M E

    2014-10-01

    Sea anemones synthesize a variety of toxic peptides and proteins of biological interest. The Caribbean Sea anemone Stichodactyla helianthus, produces two pore-forming toxins, Sticholysin I (St I) and Stichloysin II (St II), with the ability to form oligomeric pores in cell and lipid bilayers characteristically lacking cysteine in their amino acid sequences. Recently, two mutants of a recombinant variant of Sticholysin I (rSt I) have been obtained with a Cys residue in functionally relevant regions for the pore-forming activity of the toxin: r St I F15C (in the amino terminal sequence) and r St I R52C (in the binding site). Aiming at characterizing the effects of oxidants in toxins devoid (r St I) or containing -SH moieties (r St I F15C and r St I R52C), we measured their hemolytic activity and pore forming capacity prior and after their incubation with peroxynitrite (ONOO(-)). At low ONOO(-)/Toxin ratios, nearly 0.8 Trp groups are modified by each added peroxynitrite molecule, and the toxin activity is reduced in ca. 20 %. On the other hand, in -SH bearing mutants only 0.5 Trp groups are modified by each peroxynitrite molecule and the toxin activity is only reduced in 10 %. The results indicated that Cys is the initial target of the oxidative damage and that Trp residues in Cys-containing toxins were less damaged than those in r St I. This relative protection of Trp groups correlates with a smaller loss of hemolytic activity and permeabilization ability in liposomes and emphasizes the relevance of Trp groups in the pore forming capacity of the toxins. PMID:25218252

  6. Heat stress stimulates high affinity GTPase in cervical carcinoma cells.

    PubMed

    Ralhan, R; Kaur, J; Chelvi, T; Singh, S P; Zeba, H

    1995-03-01

    A primary cellular site involved in heat shock response of eukaryotic cells is located in plasma membranes. The mechanism by which heat shock is sensed and the signals that trigger heat shock response remain an enigma. We aim to determine the role of guanine-nucleotide binding proteins (G)-proteins in mediating heat shock response in eukaryotic cells. The effect of heat shock on high affinity GTPase activity in presence or absence of modulators of G-proteins, such as pertussis toxin was studied by measuring GTPase catalyzed release of 32[Pi] from gamma-32[P]GTP. The effect of pertussis toxin on induction of heat shock proteins in cells subjected to thermal stress was studied by SDS-PAGE analysis of 35[S]-methionine labelled cellular proteins. Exposure of cultured human malignant cells to thermal stress (43 degrees C) resulted in a significant increase in activity of high affinity GTPase in the membranes (P < 0.001). This response to heat shock was inhibited by prior exposure of the cells to nanogram concentrations of pertussis toxin, suggesting the involvement of G-proteins in mediating heat shock response. To characterize this G-protein dependence further, we assayed thermal stress stimulated high affinity GTPase activity in cells pretreated with antisera (AS/7) raised against a synthetic peptide corresponding to the last 10 amino acids of alpha-subunit of inhibitory G-protein (Gi). A partial reduction in heat shock induced stimulation of GTPase activity was observed in the presence of this antisera. The pertussis toxin treated cells did not show induction of heat shock proteins in response to thermal stress.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7780830

  7. A toxin-binding alkaline phosphatase fragment synergizes Bt toxin Cry1Ac against susceptible and resistant Helicoverpa armigera.

    PubMed

    Chen, Wenbo; Liu, Chenxi; Xiao, Yutao; Zhang, Dandan; Zhang, Yongdong; Li, Xianchun; Tabashnik, Bruce E; Wu, Kongming

    2015-01-01

    Evolution of resistance by insects threatens the continued success of pest control using insecticidal crystal (Cry) proteins from the bacterium Bacillus thuringiensis (Bt) in sprays and transgenic plants. In this study, laboratory selection with Cry1Ac yielded five strains of cotton bollworm, Helicoverpa armigera, with resistance ratios at the median lethal concentration (LC50) of activated Cry1Ac ranging from 22 to 1700. Reduced activity and reduced transcription of an alkaline phosphatase protein that binds Cry1Ac was associated with resistance to Cry1Ac in the four most resistant strains. A Cry1Ac-binding fragment of alkaline phosphatase from H. armigera (HaALP1f) was not toxic by itself, but it increased mortality caused by Cry1Ac in a susceptible strain and in all five resistant strains. Although synergism of Bt toxins against susceptible insects by toxin-binding fragments of cadherin and aminopeptidase N has been reported previously, the results here provide the first evidence of synergism of a Bt toxin by a toxin-binding fragment of alkaline phosphatase. The results here also provide the first evidence of synergism of a Bt toxin by any toxin-binding peptide against resistant insects. PMID:25885820

  8. A Toxin-Binding Alkaline Phosphatase Fragment Synergizes Bt Toxin Cry1Ac against Susceptible and Resistant Helicoverpa armigera

    PubMed Central

    Xiao, Yutao; Zhang, Dandan; Zhang, Yongdong; Li, Xianchun; Tabashnik, Bruce E.; Wu, Kongming

    2015-01-01

    Evolution of resistance by insects threatens the continued success of pest control using insecticidal crystal (Cry) proteins from the bacterium Bacillus thuringiensis (Bt) in sprays and transgenic plants. In this study, laboratory selection with Cry1Ac yielded five strains of cotton bollworm, Helicoverpa armigera, with resistance ratios at the median lethal concentration (LC50) of activated Cry1Ac ranging from 22 to 1700. Reduced activity and reduced transcription of an alkaline phosphatase protein that binds Cry1Ac was associated with resistance to Cry1Ac in the four most resistant strains. A Cry1Ac-binding fragment of alkaline phosphatase from H. armigera (HaALP1f) was not toxic by itself, but it increased mortality caused by Cry1Ac in a susceptible strain and in all five resistant strains. Although synergism of Bt toxins against susceptible insects by toxin-binding fragments of cadherin and aminopeptidase N has been reported previously, the results here provide the first evidence of synergism of a Bt toxin by a toxin-binding fragment of alkaline phosphatase. The results here also provide the first evidence of synergism of a Bt toxin by any toxin-binding peptide against resistant insects. PMID:25885820

  9. Association of Clostridium difficile ribotype 078 with detectable toxin in human stool specimens.

    PubMed

    Fairley, Derek J; McKenna, James P; Stevenson, Mike; Weaver, Jeremy; Gilliland, Carol; Watt, Alison; Coyle, Peter V

    2015-11-01

    Using a Clostridium difficile glutamate dehydrogenase (GDH) immunoassay and a sensitive C. difficile toxin A/B immunoassay, human stool specimens from patients with diarrhoea (n?=?1085) were classified as either GDH positive/toxin negative, or GDH positive/toxin positive. Overall, 528/725 (73%) of the GDH-positive/toxin-negative specimens contained viable C. difficile, and 433/528 (82%) of these C. difficile isolates were PCR positive for the toxin gene pathogenicity locus. Overall, 867/1078 (80%) of the GDH-positive specimens contained viable C. difficile, and 433/725 (60%) of the GDH-positive/toxin-negative specimens contained a toxigenic C. difficile strain. The diversity of toxigenic C. difficile ribotypes isolated from toxin-negative specimens (n?=?433) and toxin-positive specimens (n?=?339) was significantly different (P?toxin in clinical specimens using a sensitive toxin immunoassay. Specimens positive for ribotype 078 were almost twice as likely to be toxin positive as opposed to toxin negative (risk ratio?=?1.90, 95% confidence interval 1.64-2.19). In contrast, other circulating ribotypes were seen with similar frequency in specimens with and without detectable toxin. This supports the view that ribotype 078 strains may be more virulent than other common ribotypes in terms of toxin production. PMID:26354090

  10. Using High Performance Computing to Understand Roles of Labile and Nonlabile U(VI) on Hanford 300 Area Plume Longevity

    SciTech Connect

    Lichtner, Peter C.; Hammond, Glenn E.

    2012-07-28

    Evolution of a hexavalent uranium [U(VI)] plume at the Hanford 300 Area bordering the Columbia River is investigated to evaluate the roles of labile and nonlabile forms of U(VI) on the longevity of the plume. A high fidelity, three-dimensional, field-scale, reactive flow and transport model is used to represent the system. Richards equation coupled to multicomponent reactive transport equations are solved for times up to 100 years taking into account rapid fluctuations in the Columbia River stage resulting in pulse releases of U(VI) into the river. The peta-scale computer code PFLOTRAN developed under a DOE SciDAC-2 project is employed in the simulations and executed on ORNL's Cray XT5 supercomputer Jaguar. Labile U(VI) is represented in the model through surface complexation reactions and its nonlabile form through dissolution of metatorbernite used as a surrogate mineral. Initial conditions are constructed corresponding to the U(VI) plume already in place to avoid uncertainties associated with the lack of historical data for the waste stream. The cumulative U(VI) flux into the river is compared for cases of equilibrium and multirate sorption models and for no sorption. The sensitivity of the U(VI) flux into the river on the initial plume configuration is investigated. The presence of nonlabile U(VI) was found to be essential in explaining the longevity of the U(VI) plume and the prolonged high U(VI) concentrations at the site exceeding the EPA MCL for uranium.

  11. The enhanced catalytic performance of cobalt catalysts towards butadiene polymerization by introducing a labile donor in a salen ligand.

    PubMed

    Gong, Dirong; Wang, Baolin; Jia, Xiaoyu; Zhang, Xuequan

    2014-03-14

    A family of cobalt complexes supported by a tridentate Schiff base ligand with a labile donor (O, S, N) as a pendant arm (Co1-Co12, formulated as CoL2) were synthesized by the treatment of the corresponding ligands with cobalt acetate tetrahydrate. The resultant complexes were well characterized by elemental analysis, FT-IR, magnetic moment as well as EI-MS. The solid-state structures of Co7 and Co12 were determined by X-ray diffraction and both established a distorted octahedron geometry around the cobalt center. The butadiene polymerization capabilities of the 12 complexes were evaluated and compared in representative cases. Diethylaluminum chloride (AlEt2Cl) was found to be the compatible activator resulting in highly active catalysts for producing polybutadiene of 93.8-98.2% cis-1,4 enchainment with negligible 1,2-structure and trans-1,4 units. It appears that a certain degree of lability of the donor is beneficial for high catalytic activity, generally following the order of O > S > N, and the high cis-1,4 selectivity. Moreover, the remarkable thermal stability of these systems has been achieved: the catalytic systems have the ability of conducting a high level of active and selective polymerization, reaching an upper limit of polymerization temperature of about 70 °C. The enhanced catalytic performances were further rationalized by the established diene polymerization mechanism, which could shed light on developing highly selective and reactive industrially applicable catalysts with an enhanced thermal stability. PMID:24468706

  12. Persistent Long-Term Facilitation at an Identified Synapse Becomes Labile with Activation of Short-Term Heterosynaptic Plasticity

    PubMed Central

    Schacher, Samuel

    2014-01-01

    Short-term and long-term synaptic plasticity are cellular correlates of learning and memory of different durations. Little is known, however, how these two forms of plasticity interact at the same synaptic connection. We examined the reciprocal impact of short-term heterosynaptic or homosynaptic plasticity at sensorimotor synapses of Aplysia in cell culture when expressing persistent long-term facilitation (P-LTF) evoked by serotonin [5-hydroxytryptamine (5-HT)]. Short-term heterosynaptic plasticity induced by 5-HT (facilitation) or the neuropeptide FMRFa (depression) and short-term homosynaptic plasticity induced by tetanus [post-tetanic potentiation (PTP)] or low-frequency stimulation [homosynaptic depression (HSD)] of the sensory neuron were expressed in both control synapses and synapses expressing P-LTF in the absence or presence of protein synthesis inhibitors. All forms of short-term plasticity failed to significantly affect ongoing P-LTF in the absence of protein synthesis inhibitors. However, P-LTF reversed to control levels when either 5-HT or FMRFa was applied in the presence of rapamycin. In contrast, P-LTF was unaffected when either PTP or HSD was evoked in the presence of either rapamycin or anisomycin. These results indicate that synapses expressing persistent plasticity acquire a “new” baseline and functionally express short-term changes as naive synapses, but the new baseline becomes labile following selective activations—heterosynaptic stimuli that evoke opposite forms of plasticity—such that when presented in the presence of protein synthesis inhibitors produce a rapid reversal of the persistent plasticity. Activity-selective induction of a labile state at synapses expressing persistent plasticity may facilitate the development of therapies for reversing inappropriate memories. PMID:24695698

  13. Treatment of camptocormia with botulinum toxin.

    PubMed

    Bertram, Kelly L; Stirpe, Paola; Colosimo, Carlo

    2015-12-01

    Camptocormia is defined as an involuntary axial postural distortion of >45° flexion which occurs in the upright position, increases whilst walking and resolves when supine (Ashour and Jankovic, 2006). Unlike orthopaedic or age related kyphosis it is not a fixed structural deformity and produces kyphosis at predominantly lumbar and thoracic rather than cervical regions. Camptocormia has been reported due to a wide range of neurologic, psychiatric, muscular and orthopaedic conditions as well as rare reports of its emergence following the initiation of a number of medications (Finsterer and Strobl, 2010). Parkinson's disease (PD) includes prominent motor features of bradykinesia, rigidity and reduced postural balance responses in all those affected with this disease, but can also cause a range of other motor and non-motor features. Camptocormia is reported in a minority of patients with PD, and it is usually associated with longer disease duration and greater disease burden (Tiple et al., 2009). The aetiology of camptocormia in PD is debated, and responses to treatment have been generally poor and variable between studies. Recent studies have suggested the use of botulinum toxin may improve posture in some affected individuals. PMID:26079953

  14. Hemolytic Uremic Syndrome: Toxins, Vessels, and Inflammation

    PubMed Central

    Cheung, Victoria; Trachtman, Howard

    2014-01-01

    Hemolytic uremic syndrome (HUS) is characterized by thrombotic microangiopathy of the glomerular microcirculation and other vascular beds. Its defining clinical phenotype is acute kidney injury (AKI), microangiopathic anemia, and thrombocytopenia. There are many etiologies of HUS including infection by Shiga toxin-producing bacterial strains, medications, viral infections, malignancy, and mutations of genes coding for proteins involved in the alternative pathway of complement. In the aggregate, although HUS is a rare disease, it is one of the most common causes of AKI in previously healthy children and accounts for a sizable number of pediatric and adult patients who progress to end stage kidney disease. There has been great progress over the past 20?years in understanding the pathophysiology of HUS and its related disorders. There has been intense focus on vascular injury in HUS as the major mechanism of disease and target for effective therapies for this acute illness. In all forms of HUS, there is evidence of both systemic and intra-glomerular inflammation and perturbations in the immune system. Renewed investigation into these aspects of HUS may prove helpful in developing new interventions that can attenuate glomerular and tubular injury and improve clinical outcomes in patients with HUS. PMID:25593915

  15. EFFECTS OF CLIMATE CHANGE ON LABILE AND STRUCTURAL CARBON IN DOUGLAS-FIR NEEDLES AS ESTIMATED BY DELTA 13C AND C AREA MEASUREMENTS

    EPA Science Inventory

    Isotopic measurements may provide new insights into levels in leaves of labile and structural carbon (C) under climate change. In a 4-year climate change experiment using Pseudotsuga menziesii (Douglas-fir) seedlings and a 2x2 factorial design in enclosed chambers (n=3), atmosph...

  16. Evolutionary stasis and lability in thermal physiology in a group of tropical lizards

    PubMed Central

    Muñoz, Martha M.; Stimola, Maureen A.; Algar, Adam C.; Conover, Asa; Rodriguez, Anthony J.; Landestoy, Miguel A.; Bakken, George S.; Losos, Jonathan B.

    2014-01-01

    Understanding how quickly physiological traits evolve is a topic of great interest, particularly in the context of how organisms can adapt in response to climate warming. Adjustment to novel thermal habitats may occur either through behavioural adjustments, physiological adaptation or both. Here, we test whether rates of evolution differ among physiological traits in the cybotoids, a clade of tropical Anolis lizards distributed in markedly different thermal environments on the Caribbean island of Hispaniola. We find that cold tolerance evolves considerably faster than heat tolerance, a difference that results because behavioural thermoregulation more effectively shields these organisms from selection on upper than lower temperature tolerances. Specifically, because lizards in very different environments behaviourally thermoregulate during the day to similar body temperatures, divergent selection on body temperature and heat tolerance is precluded, whereas night-time temperatures can only be partially buffered by behaviour, thereby exposing organisms to selection on cold tolerance. We discuss how exposure to selection on physiology influences divergence among tropical organisms and its implications for adaptive evolutionary response to climate warming. PMID:24430845

  17. Evolutionary stasis and lability in thermal physiology in a group of tropical lizards.

    PubMed

    Muñoz, Martha M; Stimola, Maureen A; Algar, Adam C; Conover, Asa; Rodriguez, Anthony J; Landestoy, Miguel A; Bakken, George S; Losos, Jonathan B

    2014-03-01

    Understanding how quickly physiological traits evolve is a topic of great interest, particularly in the context of how organisms can adapt in response to climate warming. Adjustment to novel thermal habitats may occur either through behavioural adjustments, physiological adaptation or both. Here, we test whether rates of evolution differ among physiological traits in the cybotoids, a clade of tropical Anolis lizards distributed in markedly different thermal environments on the Caribbean island of Hispaniola. We find that cold tolerance evolves considerably faster than heat tolerance, a difference that results because behavioural thermoregulation more effectively shields these organisms from selection on upper than lower temperature tolerances. Specifically, because lizards in very different environments behaviourally thermoregulate during the day to similar body temperatures, divergent selection on body temperature and heat tolerance is precluded, whereas night-time temperatures can only be partially buffered by behaviour, thereby exposing organisms to selection on cold tolerance. We discuss how exposure to selection on physiology influences divergence among tropical organisms and its implications for adaptive evolutionary response to climate warming. PMID:24430845

  18. Diversification of ?-Augmentation Interactions between CDI Toxin/Immunity Proteins.

    PubMed

    Morse, Robert P; Willett, Julia L E; Johnson, Parker M; Zheng, Jing; Credali, Alfredo; Iniguez, Angelina; Nowick, James S; Hayes, Christopher S; Goulding, Celia W

    2015-11-20

    Contact-dependent growth inhibition (CDI) is a widespread mechanism of inter-bacterial competition mediated by the CdiB/CdiA family of two-partner secretion proteins. CdiA effectors carry diverse C-terminal toxin domains (CdiA-CT), which are delivered into neighboring target cells to inhibit growth. CDI(+) bacteria also produce CdiI immunity proteins that bind specifically to cognate CdiA-CT toxins and protect the cell from auto-inhibition. Here, we compare the structures of homologous CdiA-CT/CdiI complexes from Escherichia coli EC869 and Yersinia pseudotuberculosis YPIII to explore the evolution of CDI toxin/immunity protein interactions. Both complexes share an unusual ?-augmentation interaction, in which the toxin domain extends a ?-hairpin into the immunity protein to complete a six-stranded anti-parallel sheet. However, the specific contacts differ substantially between the two complexes. The EC869 ?-hairpin interacts mainly through direct H-bond and ion-pair interactions, whereas the YPIII ?-hairpin pocket contains more hydrophobic contacts and a network of bridging water molecules. In accord with these differences, we find that each CdiI protein only protects target bacteria from its cognate CdiA-CT toxin. The compact ?-hairpin binding pocket within the immunity protein represents a tractable system for the rationale design of small molecules to block CdiA-CT/CdiI complex formation. We synthesized a macrocyclic peptide mimic of the ?-hairpin from EC869 toxin and solved its structure in complex with cognate immunity protein. These latter studies suggest that small molecules could potentially be used to disrupt CDI toxin/immunity complexes. PMID:26449640

  19. Functional validation of putative toxin-antitoxin genes from the Gram-positive pathogen Streptococcus pneumoniae: phd-doc is the fourth bona-fide operon

    PubMed Central

    Chan, Wai Ting; Yeo, Chew Chieng; Sadowy, Ewa; Espinosa, Manuel

    2014-01-01

    Bacterial toxin-antitoxin (TAs) loci usually consist of two genes organized as an operon, where their products are bound together and inert under normal conditions. However, under stressful circumstances the antitoxin, which is more labile, will be degraded more rapidly, thereby unleashing its cognate toxin to act on the cell. This, in turn, causes cell stasis or cell death, depending on the type of TAs and/or time of toxin exposure. Previously based on in silico analyses, we proposed that Streptococcus pneumoniae, a pathogenic Gram-positive bacterium, may harbor between 4 and 10 putative TA loci depending on the strains. Here we have chosen the pneumococcal strain Hungary19A-6 which contains all possible 10 TA loci. In addition to the three well-characterized operons, namely relBE2, yefM-yoeB, and pezAT, we show here the functionality of a fourth operon that encodes the pneumococcal equivalent of the phd-doc TA. Transcriptional fusions with gene encoding Green Fluorescent Protein showed that the promoter was slightly repressed by the Phd antitoxin, and exhibited almost background values when both Phd-Doc were expressed together. These findings demonstrate that phd-doc shows the negative self-regulatory features typical for an authentic TA. Further, we also show that the previously proposed TAs XreA-Ant and Bro-XreB, although they exhibit a genetic organization resembling those of typical TAs, did not appear to confer a functional behavior corresponding to bona fide TAs. In addition, we have also discovered new interesting bioinformatics results for the known pneumococcal TAs RelBE2 and PezAT. A global analysis of the four identified toxins-antitoxins in the pneumococcal genomes (PezAT, RelBE2, YefM-YoeB, and Phd-Doc) showed that RelBE2 and Phd-Doc are the most conserved ones. Further, there was good correlation among TA types, clonal complexes and sequence types in the 48 pneumococcal strains analyzed. PMID:25538695

  20. Production of Clostridium difficile toxin in a medium totally free of both animal and dairy proteins or digests

    E-print Network

    Demain, Arnold L.

    In the hope of developing a vaccine against Clostridium difficile based on its toxin(s), we have developed a fermentation medium for the bacterium that results in the formation of Toxin A and contains no meat or dairy ...

  1. Supporting Information for: Light Activation of Staphylococcus aureus Toxin YoeBSa1 Reveals Guanosine-Specific

    E-print Network

    Hergenrother, Paul J.

    1 Supporting Information for: Light Activation of Staphylococcus aureus Toxin YoeBSa1 Reveals on Antimicrobial Resistance in Staphylococcus aureus. Toxin-Antitoxin System Toxin-Antitoxin System Isolate yef

  2. Speciation Analysis of Labile and Total Silver(I) in Nanosilver Dispersions and Environmental Waters by Hollow Fiber Supported Liquid Membrane Extraction.

    PubMed

    Chao, Jing-Bo; Zhou, Xiao-Xia; Shen, Mo-Hai; Tan, Zhi-Qiang; Liu, Rui; Yu, Su-Juan; Wang, Xiao-Wei; Liu, Jing-Fu

    2015-12-15

    Hollow fiber supported liquid membrane (HFSLM) extraction was coupled with ICP-MS for speciation analysis of labile Ag(I) and total Ag(I) in dispersions of silver nanoparticles (AgNPs) and environmental waters. Ag(I) in aqueous samples was extracted into the HFSLM of 5%(m/v) tri-n-octylphosphine oxide in n-undecane, and stripped in the acceptor of 10 mM Na2S2O3 and 1 mM Cu(NO3)2 prepared in 5 mM NaH2PO4-Na2HPO4 buffer (pH 7.5). Negligible depletion and exhaustive extraction were conducted under static and 250 rpm shaking to extract the labile Ag(I) and total Ag(I), respectively. The extraction equilibration was reached in 8 h for both extraction modes. The extraction efficiency and detection limit were (2.97 ± 0.25)% and 0.1 ?g/L for labile Ag(I), and (82.3 ± 2.0)% and 0.5 ?g/L for total Ag(I) detection, respectively. The proposed method was applied to determine labile Ag(I) and total Ag(I) in different sized AgNP dispersions and real environmental waters, with spiked recoveries of total Ag(I) in the range of 74.0-98.1%. With the capability of distinguishing labile and total Ag(I), our method offers a new approach for evaluating the bioavailability and understanding the fate and toxicity of AgNPs in aquatic systems. PMID:26580982

  3. Crystal structure of Staphylococcus aureus exfoliative toxin D-like protein: Structural basis for the high specificity of exfoliative toxins.

    PubMed

    Mariutti, Ricardo B; Souza, Tatiana A C B; Ullah, Anwar; Caruso, Icaro P; de Moraes, Fábio R; Zanphorlin, Leticia M; Tartaglia, Natayme R; Seyffert, Nubia; Azevedo, Vasco A; Le Loir, Yves; Murakami, Mário T; Arni, Raghuvir K

    2015-11-01

    Exfoliative toxins are serine proteases secreted by Staphylococcus aureus that are associated with toxin-mediated staphylococcal syndromes. To date, four different serotypes of exfoliative toxins have been identified and 3 of them (ETA, ETB, and ETD) are linked to human infection. Among these toxins, only the ETD structure remained unknown, limiting our understanding of the structural determinants for the functional differentiation between these toxins. We recently identified an ETD-like protein associated to S. aureus strains involved in mild mastitis in sheep. The crystal structure of this ETD-like protein was determined at 1.95 Å resolution and the structural analysis provide insights into the oligomerization, stability and specificity and enabled a comprehensive structural comparison with ETA and ETB. Despite the highly conserved molecular architecture, significant differences in the composition of the loops and in both the N- and C-terminal ?-helices seem to define ETD-like specificity. Molecular dynamics simulations indicate that these regions defining ET specificity present different degrees of flexibility and may undergo conformational changes upon substrate recognition and binding. DLS and AUC experiments indicated that the ETD-like is monomeric in solution whereas it is present as a dimer in the asymmetric unit indicating that oligomerization is not related to functional differentiation among these toxins. Differential scanning calorimetry and circular dichroism assays demonstrated an endothermic transition centered at 52 °C, and an exothermic aggregation in temperatures up to 64 °C. All these together provide insights about the mode of action of a toxin often secreted in syndromes that are not associated with either ETA or ETB. PMID:26299923

  4. Toxins not neutralized by brown snake antivenom

    SciTech Connect

    Judge, Roopwant K.; Henry, Peter J.; Mirtschin, Peter; Jelinek, George; Wilce, Jacqueline A. . E-mail: Jackie.Wilce@med.monash.edu.au

    2006-06-01

    The Australian snakes of the genus Pseudonaja (dugite, gwardar and common brown) account for the majority of snake bite related deaths in Australia. Without antivenom treatment, the risk of mortality is significant. There is an accumulating body of evidence to suggest that the efficacy of the antivenom is limited. The current study investigates the protein constituents recognized by the antivenom using 2-DE, immuno-blot techniques and rat tracheal organ bath assays. The 2-DE profiles for all three snake venoms were similar, with major species visualized at 78-132 kDa, 32-45 kDa and 6-15 kDa. Proteins characterized by LC-MS/MS revealed a coagulant toxin ({approx}42 kDa) and coagulant peptide ({approx}6 kDa), as well as two PLA{sub 2} ({approx}14 kDa). Peptides isolated from {approx}78 kDa and 15-32 kDa protein components showed no similarity to known protein sequences. Protein recognition by the antivenom occurred predominantly for the higher molecular weight components with little recognition of 6-32 kDa MW species. The ability of antivenom to neutralize venom activity was also investigated using rat tracheal organ bath assays. The venoms of Pseudonaja affinis affinis and Pseudonaja nuchalis incited a sustained, significant contraction of the trachea. These contractions were attributed to PLA{sub 2} enzymatic activity as pre-treatment with the PLA{sub 2} inhibitor 4-BPB attenuated the venom-induced contractions. The venom of Pseudonaja textilis incited tracheal contractility through a non-PLA{sub 2} enzymatic activity. Neither activity was attenuated by the antivenom treatment. These results represent the first proteomic investigation of the venoms from the snakes of the genus Pseudonaja, revealing a possible limitation of the brown snake antivenom in binding to the low MW protein components.

  5. Environmental heat stress modulates thyroid status and its response to repeated endotoxin (LPS) challenge in steers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Thyroid hormones are important in the adaptation to heat stress, allowing the adjustment of metabolic rates in favor of decreased energy utilization and heat production. Thyroid status is compromised in a variety of acute and chronic infections and toxin-mediated disease states. Our objective was to...

  6. Isolation of isoelectrically pure cholera toxin for crystallization

    SciTech Connect

    Spangler, B.D.; Westbrook, E.M.

    1989-01-01

    We have determined that the failure of cholera toxin to crystallize well results from its isoelectric heterogeneity, which is probably due to a post-translational process such as deamidation of its B subunit. Every sample of cholera toxin we have examined from commercial or academic suppliers has been heterogeneous; heterogeneous cholera toxin does not crystallize satisfactorily. We have overcome this problem by using ion-exchange fast protein liquid chromatography (FPLC) to obtain an isoelectrically homogeneous species of cholera toxin. Homogeneous cholera toxin crystallizes readily, forming single, nonmosaic crystals suitable for x-ray diffraction studies. For this process, protein was applied to a MonoQ ion-exchange column, then eluted with an isocratic low salt buffer followed by a linear salt gradient (0-100 mM NaCl). Column fractions were analyzed on isoelectric focusing gels, and those fractions containing the desired homogeneous species were pooled and concentrated. Crystals formed within 24 to 48 hours in a MOPS/PEG buffer, which made use of slow isoelectric precipitation to induce crystallization. 23 refs., 6 figs.

  7. Recent Advances in Research on Widow Spider Venoms and Toxins

    PubMed Central

    Yan, Shuai; Wang, Xianchun

    2015-01-01

    Widow spiders have received much attention due to the frequently reported human and animal injures caused by them. Elucidation of the molecular composition and action mechanism of the venoms and toxins has vast implications in the treatment of latrodectism and in the neurobiology and pharmaceutical research. In recent years, the studies of the widow spider venoms and the venom toxins, particularly the ?-latrotoxin, have achieved many new advances; however, the mechanism of action of the venom toxins has not been completely clear. The widow spider is different from many other venomous animals in that it has toxic components not only in the venom glands but also in other parts of the adult spider body, newborn spiderlings, and even the eggs. More recently, the molecular basis for the toxicity outside the venom glands has been systematically investigated, with four proteinaceous toxic components being purified and preliminarily characterized, which has expanded our understanding of the widow spider toxins. This review presents a glance at the recent advances in the study on the venoms and toxins from the Latrodectus species. PMID:26633495

  8. Modification of opiate agonist binding by pertussis toxin

    SciTech Connect

    Abood, M.E.; Lee, N.M.; Loh, H.H.

    1986-03-05

    Opiate agonist binding is decreased by GTP, suggesting the possible involvement of GTP binding proteins in regulation of opiate receptor binding. This possibility was addressed by asking whether pertussis toxin treatment, which results in ADP-ribosylation and modification of G proteins, would alter opiate agonist binding. The striatum was chosen for the initial brain area to be studied, since regulation of opiate action in this area had been shown to be modified by pertussis toxin. Treatment of striatal membranes with pertussis toxin results in up to a 55% decrease in /sup 3/(H)-DADLE binding as compared with membranes treated identically without toxin. This corresponds to a near complete ADP-ribosylation of both G proteins in the striatal membrane. The decrease in agonist binding appears to be due to an altered affinity of the receptor for agonist as opposed to a decrease in the number of sites. This effect of pertussis toxin on opiate agonist binding demonstrates the actual involvement of G proteins in regulation of opiate receptor binding.

  9. Evolution of Bacillus thuringiensis Cry toxins insecticidal activity

    PubMed Central

    Bravo, Alejandra; Gómez, Isabel; Porta, Helena; García-Gómez, Blanca Ines; Rodriguez-Almazan, Claudia; Pardo, Liliana; Soberón, Mario

    2013-01-01

    Insecticidal Cry proteins produced by Bacillus thuringiensis are use worldwide in transgenic crops for efficient pest control. Among the family of Cry toxins, the three domain Cry family is the better characterized regarding their natural evolution leading to a large number of Cry proteins with similar structure, mode of action but different insect specificity. Also, this group is the better characterized regarding the study of their mode of action and the molecular basis of insect specificity. In this review we discuss how Cry toxins have evolved insect specificity in nature and analyse several cases of improvement of Cry toxin action by genetic engineering, some of these examples are currently used in transgenic crops. We believe that the success in the improvement of insecticidal activity by genetic evolution of Cry toxins will depend on the knowledge of the rate-limiting steps of Cry toxicity in different insect pests, the mapping of the specificity binding regions in the Cry toxins, as well as the improvement of mutagenesis strategies and selection procedures. PMID:22463726

  10. Channel-Forming Bacterial Toxins in Biosensing and Macromolecule Delivery

    PubMed Central

    Gurnev, Philip A.; Nestorovich, Ekaterina M.

    2014-01-01

    To intoxicate cells, pore-forming bacterial toxins are evolved to allow for the transmembrane traffic of different substrates, ranging from small inorganic ions to cell-specific polypeptides. Recent developments in single-channel electrical recordings, X-ray crystallography, protein engineering, and computational methods have generated a large body of knowledge about the basic principles of channel-mediated molecular transport. These discoveries provide a robust framework for expansion of the described principles and methods toward use of biological nanopores in the growing field of nanobiotechnology. This article, written for a special volume on “Intracellular Traffic and Transport of Bacterial Protein Toxins”, reviews the current state of applications of pore-forming bacterial toxins in small- and macromolecule-sensing, targeted cancer therapy, and drug delivery. We discuss the electrophysiological studies that explore molecular details of channel-facilitated protein and polymer transport across cellular membranes using both natural and foreign substrates. The review focuses on the structurally and functionally different bacterial toxins: gramicidin A of Bacillus brevis, ?-hemolysin of Staphylococcus aureus, and binary toxin of Bacillus anthracis, which have found their “second life” in a variety of developing medical and technological applications. PMID:25153255

  11. Heat emergencies

    MedlinePLUS

    Heatstroke; Heat illness ... who is in good shape can suffer heat illness if warning signs are ignored) The following make ... Heat cramps are the first stage of heat illness. If these symptoms are not treated, it can ...

  12. FDA Approves First Botulism Antitoxin for Use in Neutralizing All Seven Known Botulinum Nerve Toxin Serotypes

    MedlinePLUS

    ... approves first Botulism Antitoxin for use in neutralizing all seven known botulinum nerve toxin serotypes Product to ... contains a mixture of antibody fragments that neutralize all of the seven botulinum nerve toxin serotypes known ...

  13. Occurrence and Distribution of Cyanobacteria and their Toxins in Silver Lake, New Hampshire

    E-print Network

    New Hampshire, University of

    Occurrence and Distribution of Cyanobacteria and their Toxins in Silver Lake, New Hampshire review. Introduction The production of toxins by cyanobacteria (Chorus et al., 2000) has magnified, 2006). Thorough assessments of the prevalence and spatial distribution of cyanobacteria within bodies

  14. RESEARCH FACILITY AND LABORATORY SECURITY Hazardous chemicals, radioactive materials, biological agents and toxins must be stored

    E-print Network

    Kienzle, Stefan W.

    agents and toxins must be stored securely to prevent unauthorized access and removal as well chemicals, radioactive materials, biological agents or toxins are present must be kept secured at all times

  15. Acute angle-closure glaucoma following botulinum toxin injection for blepharospasm.

    PubMed Central

    Corridan, P.; Nightingale, S.; Mashoudi, N.; Williams, A. C.

    1990-01-01

    Botulinum toxin inhibits acetylcholine release and therefore could cause mydriasis. We report a case of acute angle-closure glaucoma which occurred shortly after a series of injections of botulinum toxin round the eyelids for blepharospasm. PMID:2354140

  16. Separation of the toxin of Bacillus cereus into two components and nonidentity of the toxin with phospholipase.

    PubMed

    MOLNAR, D M

    1962-07-01

    Molnar, Dorothy M. (U.S. Army Chemical Corps, Fort Detrick, Frederick, Md.). Separation of the toxin of Bacillus cereus into two components and nonidentity of the toxin with phospholipase. J. Bacteriol. 84:147-153. 1962-Bacillus cereus produced toxin in a Casamino acids medium without added serum or other protein. The toxin was separated into two components by adsorption on columns of calcium phosphate gel followed by elution with phosphate buffer (pH 7.5). The component eluted first has been called factor I and the component eluted later factor II. When tested alone each component was relatively nontoxic, but when combined they formed a toxic mixture as evidenced by skin reactions in guinea pigs and tests for lethal effects in mice. The phospholipase activity, determined by the egg-yolk reaction, was found in the fraction containing factor I. However, using columns of alumina-C(gamma) gel the phospholipase activity was found in the fraction containing factor II. This suggests that the phospholipase is not the same chemical entity as either factor I or II. The following are further evidence for the non-identity of the toxin and phospholipase: (i) differential precipitation of the two activities by (NH(4))(2)SO(4); (ii) differential neutralization by various antisera; and (iii) differential inhibition with ethanol. PMID:14475243

  17. Prevalence and pathogenicity of binary toxin–positive Clostridium difficile strains that do not produce toxins A and B

    PubMed Central

    Eckert, C.; Emirian, A.; Le Monnier, A.; Cathala, L.; De Montclos, H.; Goret, J.; Berger, P.; Petit, A.; De Chevigny, A.; Jean-Pierre, H.; Nebbad, B.; Camiade, S.; Meckenstock, R.; Lalande, V.; Marchandin, H.; Barbut, F.

    2014-01-01

    Clostridium difficile causes antibiotic-associated diarrhoea and pseudomembranous colitis. The main virulence factors of C. difficile are the toxins A (TcdA) and B (TcdB). A third toxin, called binary toxin (CDT), can be detected in 17% to 23% of strains, but its role in human disease has not been clearly defined. We report six independent cases of patients with diarrhoea suspected of having C. difficile infection due to strains from toxinotype XI/PCR ribotype 033 or 033-like, an unusual toxinotype/PCR ribotype positive for CDT but negative for TcdA and TcdB. Four patients were considered truly infected by clinicians and were specifically treated with oral metronidazole. One of the cases was identified during a prevalence study of A?B?CDT+ strains. In this study, we screened a French collection of 220 nontoxigenic strains and found only one (0.5%) toxinotype XI/PCR ribotype 033 or 033-like strain. The description of such strains raises the question of the role of binary toxin as a virulence factor and could have implications for laboratory diagnostics that currently rarely include testing for binary toxin. PMID:25755885

  18. Uremic toxins, oxidative stress, and renal fibrosis: an interwined complex.

    PubMed

    Chao, Chia-Ter; Chiang, Chih-Kang

    2015-03-01

    The prevalence of end-stage renal diseases is currently on the rise globally, and finding the way to curb this tide is urgently needed. Tubulointerstitial fibrosis is a common pathway for essentially all the nephropathy categories known to date, and the manifestations of renal fibrosis include excessive deposition of extracellular matrix with distortion of renal microstructures and functional deterioration. Uremic toxins have been gradually found to play an important role in the development of progressive renal fibrosis, with protein-bound indoxyl sulfate, p-cresol, and p-cresyl sulfate receiving the most attention. However, the contribution of oxidative stress among the pathogenesis of uremic toxins and renal fibrosis has not been evaluated much until recently. In this review, we will discuss about the nature and sources of oxidative stress in the kidney and how uremic toxins use oxidative stress to orchestrate the processes of renal fibrosis. PMID:25511523

  19. Depression - An emerging indication for botulinum toxin treatment.

    PubMed

    Kruger, Tillmann H C; Wollmer, M Axel

    2015-12-01

    The treatment of glabellar frown lines with botulinum toxin injection is one of the most prevalent procedures in esthetic medicine. It is possible that the popularity of this intervention is not only owing to its cosmetic effect but also to modulatory effects on mood and affectivity. Recently, a series of studies including three randomized controlled trials have consistently shown that such effects can be used in the treatment of depression. Predominantly female patients suffering from partly chronic and treatment resistant unipolar depression experienced a quick, strong and sustained improvement in depressive symptoms after a single glabellar treatment with botulinum toxin A as a sole or adjunctive therapy. If these findings are further corroborated in additional studies, the ever-growing spectrum of applications for botulinum toxin may spread into the field of psychiatry, showing that the superficial paralysis of facial muscles may, probably via proprioceptive feedback mechanisms, have profound effects on the emotional brain. PMID:26415901

  20. Effectiveness of Botulinum Toxin Administered to Abolish Acquired Nystagmus

    NASA Technical Reports Server (NTRS)

    Leigh, R. John; Tomsak, Robert L.; Grant, Michael P.; Remler, Bernd F.; Yaniglos, Stacy S.; Lystad, Lisa; Dell'Osso, Louis F.

    1992-01-01

    We injected botulinum toxin into the horizontal rectus muscles of the right eyes of two patients who had acquired pendular nystagmus with horizontal, vertical, and torsional components. This treatment successfully abolished the horizontal component of the nystagmus in the injected eye in both patients for approximately 2 months. Both patients showed a small but measurable improvement of vision in the injected eye that may have been limited by coexistent disease of the visual pathways. The vertical and torsional components of the nystagmus persisted in both patients. In one patient, the horizontal component of nystagmus in the noninjected eye increased; we ascribe this finding to plastic-adaptive changes in response to paresis caused by the botulinum toxin. Such plastic-adaptive changes and direct side effects of the injections - such as diplopia and ptosis - may limit the effectiveness of botulinum toxin in the treatment of acquired nystagmus. Neither patient elected to repeat the botulinum treatment.

  1. Cigarette Smoke, Bacteria, Mold, Microbial Toxins, and Chronic Lung Inflammation

    PubMed Central

    Pauly, John L.; Paszkiewicz, Geraldine

    2011-01-01

    Chronic inflammation associated with cigarette smoke fosters malignant transformation and tumor cell proliferation and promotes certain nonneoplastic pulmonary diseases. The question arises as to whether chronic inflammation and/or colonization of the airway can be attributed, at least in part, to tobacco-associated microbes (bacteria, fungi, and spores) and/or microbial toxins (endotoxins and mycotoxins) in tobacco. To address this question, a literature search of documents in various databases was performed. The databases included PubMed, Legacy Tobacco Documents Library, and US Patents. This investigation documents that tobacco companies have identified and quantified bacteria, fungi, and microbial toxins at harvest, throughout fermentation, and during storage. Also characterized was the microbial flora of diverse smoking and smokeless tobacco articles. Evidence-based health concerns expressed in investigations of microbes and microbial toxins in cigarettes, cigarette smoke, and smokeless tobacco products are reasonable; they warrant review by regulatory authorities and, if necessary, additional investigation to address scientific gaps. PMID:21772847

  2. Emerging treatments for overactive bladder: clinical potential of botulinum toxins

    PubMed Central

    Tincello, Douglas G; Rashid, Tina; Revicky, Vladimir

    2014-01-01

    Overactive bladder (OAB) is a symptom syndrome including urgency, frequency, and nocturia – with or without incontinence. It is a common manifestation of detrusor overactivity (DO). DO is a urodynamic observation of spontaneous or provoked contractions of the detrusor muscle is seen during the filling phase of the micturition cycle. OAB is, therefore, both a motor and sensory disorder. Botulinum toxin is a purified form of the neurotoxin from Clostridium botulinum and has been used in medicine for many years. Over the last 10 years, it has been used for the treatment of DO and OAB when standard treatments, such as bladder training and oral anticholinergic medication, have failed to provide symptom relief. Botulinum toxin acts by irreversibly preventing neurotransmitter release from the neurons in the motor end plate and also at sensory synapses, although the clinical effect is not permanent due to the growth of new connections within treated tissues. It is known that botulinum toxin modulates vanillioid, purinergic, capsaicin, and muscarinic receptor expression within the lamina propria, returning them to levels seen in normal bladders. Clinically, the effect of botulinum toxin on symptoms of OAB and DO is profound, with large effects upon the symptom of urgency, and also large effects on frequency, nocturia, leakage episodes, and continence rates. These effects have been seen consistently within eight randomized trials and numerous case series. Botulinum toxin appears safe, with the only common side effect being that of voiding difficulty, occurring in up to 10% of treated patients. Dosing regimens are variable, depending on which preparation is used, but it is clear that dose recommendations have fallen over the last 5 years. There is limited evidence about the efficacy of repeat treatments. Botulinum toxin is an effective and safe second-line treatment for patients with OAB and DO. PMID:24892033

  3. Brown Spider (Loxosceles genus) Venom Toxins: Tools for Biological Purposes

    PubMed Central

    Chaim, Olga Meiri; Trevisan-Silva, Dilza; Chaves-Moreira, Daniele; Wille, Ana Carolina M.; Ferrer, Valéria Pereira; Matsubara, Fernando Hitomi; Mangili, Oldemir Carlos; da Silveira, Rafael Bertoni; Gremski, Luiza Helena; Gremski, Waldemiro; Senff-Ribeiro, Andrea; Veiga, Silvio Sanches

    2011-01-01

    Venomous animals use their venoms as tools for defense or predation. These venoms are complex mixtures, mainly enriched of proteic toxins or peptides with several, and different, biological activities. In general, spider venom is rich in biologically active molecules that are useful in experimental protocols for pharmacology, biochemistry, cell biology and immunology, as well as putative tools for biotechnology and industries. Spider venoms have recently garnered much attention from several research groups worldwide. Brown spider (Loxosceles genus) venom is enriched in low molecular mass proteins (5–40 kDa). Although their venom is produced in minute volumes (a few microliters), and contain only tens of micrograms of protein, the use of techniques based on molecular biology and proteomic analysis has afforded rational projects in the area and permitted the discovery and identification of a great number of novel toxins. The brown spider phospholipase-D family is undoubtedly the most investigated and characterized, although other important toxins, such as low molecular mass insecticidal peptides, metalloproteases and hyaluronidases have also been identified and featured in literature. The molecular pathways of the action of these toxins have been reported and brought new insights in the field of biotechnology. Herein, we shall see how recent reports describing discoveries in the area of brown spider venom have expanded biotechnological uses of molecules identified in these venoms, with special emphasis on the construction of a cDNA library for venom glands, transcriptome analysis, proteomic projects, recombinant expression of different proteic toxins, and finally structural descriptions based on crystallography of toxins. PMID:22069711

  4. Emerging treatments for overactive bladder: clinical potential of botulinum toxins.

    PubMed

    Tincello, Douglas G; Rashid, Tina; Revicky, Vladimir

    2014-01-01

    Overactive bladder (OAB) is a symptom syndrome including urgency, frequency, and nocturia - with or without incontinence. It is a common manifestation of detrusor overactivity (DO). DO is a urodynamic observation of spontaneous or provoked contractions of the detrusor muscle is seen during the filling phase of the micturition cycle. OAB is, therefore, both a motor and sensory disorder. Botulinum toxin is a purified form of the neurotoxin from Clostridium botulinum and has been used in medicine for many years. Over the last 10 years, it has been used for the treatment of DO and OAB when standard treatments, such as bladder training and oral anticholinergic medication, have failed to provide symptom relief. Botulinum toxin acts by irreversibly preventing neurotransmitter release from the neurons in the motor end plate and also at sensory synapses, although the clinical effect is not permanent due to the growth of new connections within treated tissues. It is known that botulinum toxin modulates vanillioid, purinergic, capsaicin, and muscarinic receptor expression within the lamina propria, returning them to levels seen in normal bladders. Clinically, the effect of botulinum toxin on symptoms of OAB and DO is profound, with large effects upon the symptom of urgency, and also large effects on frequency, nocturia, leakage episodes, and continence rates. These effects have been seen consistently within eight randomized trials and numerous case series. Botulinum toxin appears safe, with the only common side effect being that of voiding difficulty, occurring in up to 10% of treated patients. Dosing regimens are variable, depending on which preparation is used, but it is clear that dose recommendations have fallen over the last 5 years. There is limited evidence about the efficacy of repeat treatments. Botulinum toxin is an effective and safe second-line treatment for patients with OAB and DO. PMID:24892033

  5. Production of Recombinant Cholera Toxin B Subunit in Nicotiana benthamiana Using GENEWARE(®) Tobacco Mosaic Virus Vector.

    PubMed

    Moore, Lauren; Hamorsky, Krystal; Matoba, Nobuyuki

    2016-01-01

    Here, we describe a method to produce a recombinant cholera toxin B subunit in Nicotiana benthamiana plants (CTBp) using the GENEWARE(®) tobacco mosaic virus vector system. Infectious transcripts of the vector RNA are generated in vitro and inoculated on N. benthamiana seedlings. After 11 days, CTBp is extracted in a simple tris buffer at room temperature. No protease inhibitor is required. The leaf homogenate is treated with mild heat and a pH shift to selectively precipitate host-derived proteins. CTBp is purified to >95 % homogeneity by two-step chromatography using immobilized metal affinity and ceramic hydroxyapatite resins. This procedure yields on average 400 mg of low-endotoxin CTBp from 1 kg of fresh leaf material. PMID:26614286

  6. Spider, bacterial and fungal phospholipase D toxins make cyclic phosphate products.

    PubMed

    Lajoie, Daniel M; Cordes, Matthew H J

    2015-12-15

    Phospholipase D (PLD) toxins from sicariid spiders, which cause disease in mammals, were recently found to convert their primary substrates, sphingomyelin and lysophosphatidylcholine, to cyclic phospholipids. Here we show that two PLD toxins from pathogenic actinobacteria and ascomycete fungi, which share distant homology with the spider toxins, also generate cyclic phospholipids. This shared function supports divergent evolution of the PLD toxins from a common ancestor and suggests the importance of cyclic phospholipids in pathogenicity. PMID:26482933

  7. Is litter decomposition 'primed' by primary producer-release of labile carbon in terrestrial and aquatic experimental systems?

    NASA Astrophysics Data System (ADS)

    Soares, A. Margarida P. M.; Kritzberg, Emma S.; Rousk, Johannes

    2015-04-01

    It is possible that recalcitrant organic matter (ROM) can be 'activated' by inputs of labile organic matter (LOM) through the priming effect (PE). Investigating the PE is of major importance to fully understand the microbial use of ROM and its role on carbon (C) and nutrient cycling in both aquatic and terrestrial ecosystems. In aquatic ecosystems it is thought that the PE is triggered by periphytic algae release of LOM. Analogously, in terrestrial systems it is hypothesized that the LOM released in plant rhizospheres, or from the green crusts on the surface of agricultural soils, stimulate the activity and growth of ROM decomposers. Most previous studies on PE have utilised pulse additions of single substrates at high concentrations. However, to achieve an assessment of the true importance of the PE, it is important to simulate a realistic delivery of LOM. We investigated, in a series of 2-week laboratory experiments, how primary producer (PP)-release of LOM influence litter degradation in terrestrial and aquatic experimental systems. We used soil (terrestrial) and pond water (aquatic) microbial communities to which litter was added under light and dark conditions. In addition, glucose was added at PP delivery rates in dark treatments to test if the putative PE in light systems could be reproduced. We observed an initial peak of bacterial growth rate followed by an overall decrease over time with no treatment differences. In light treatments, periphytic algae growth and increased fungal production was stimulated when bacterial growth declined. In contrast, both fungal growth and algal production were negligible in dark treatments. This reveals a direct positive influence of photosynthesis on fungal growth. To investigate if PP LOM supplements, and the associated fungal growth, translate into a modulated litter decomposition, we are using stable isotopes to track the use of litter and algal-derived carbon by determining the ?13C in produced CO2. Fungi and bacteria are the fundamental microbial decomposers and thus the main agents involved in respiration, ROM mobilisation and carbon cycling. By describing if and how litter decomposition is primed by primary producer-release of labile carbon we gain a better understanding of how microbial communities degrade OM in terrestrial and aquatic systems.

  8. Toxins produced in cyanobacterial water blooms – toxicity and risks

    PubMed Central

    Bláha, Lud?k; Babica, Pavel; Maršálek, Blahoslav

    2009-01-01

    Cyanobacterial blooms in freshwaters represent a major ecological and human health problem worldwide. This paper briefly summarizes information on major cyanobacterial toxins (hepatotoxins, neurotoxins etc.) with special attention to microcystins-cyclic heptapeptides with high acute and chronic toxicities. Besides discussion of human health risks, microcystin ecotoxicology and consequent ecological risks are also highlighted. Although significant research attention has been paid to microcystins, cyanobacteria produce a wide range of currently unknown toxins, which will require research attention. Further research should also address possible additive, synergistic or antagonistic effects among different classes of cyanobacterial metabolites, as well as interactions with other toxic stressors such as metals or persistent organic pollutants. PMID:21217843

  9. Signaling Cascades of Pasteurella multocida Toxin in Immune Evasion

    PubMed Central

    Kubatzky, Katharina F.; Kloos, Bianca; Hildebrand, Dagmar

    2013-01-01

    Pasteurella multocida toxin (PMT) is a protein toxin found in toxigenic strains of Pasteurella multocida. PMT is the causative agent for atrophic rhinitis in pigs, a disease characterized by loss of nasal turbinate bones due to an inhibition of osteoblast function and an increase in osteoclast activity and numbers. Apart from this, PMT acts as a strong mitogen, protects from apoptosis and has an impact on the differentiation and function of immune cells. Many signaling pathways have been elucidated, however, the effect of these signaling cascades as a means to subvert the host’s immune system are just beginning to unravel. PMID:24064721

  10. Antimicrobial Peptides: New Recognition Molecules for Detecting Botulinum Toxins

    PubMed Central

    Kulagina, Nadezhda V.; Anderson, George P.; Ligler, Frances S.; Shaffer, Kara M.; Taitt, Chris Rowe

    2007-01-01

    Many organisms secrete antimicrobial peptides (AMPs) for protection against harmful microbes. The present study describes detection of botulinum neurotoxoids A, B and E using AMPs as recognition elements in an array biosensor. While AMP affinities were similar to those for anti-botulinum antibodies, differences in binding patterns were observed and can potentially be used for identification of toxoid serotype. Furthermore, some AMPs also demonstrated superior detection sensitivity compared to antibodies: toxoid A could be detected at 3.5 LD50 of the active toxin in a 75-min assay, whereas toxoids B and E were detected at 14 and 80 LD50 for their respective toxins.

  11. Unrelated toxin–antitoxin systems cooperate to induce persistence

    PubMed Central

    Fasani, Rick A.; Savageau, Michael A.

    2015-01-01

    Persisters are drug-tolerant bacteria that account for the majority of bacterial infections. They are not mutants, rather, they are slow-growing cells in an otherwise normally growing population. It is known that the frequency of persisters in a population is correlated with the number of toxin–antitoxin systems in the organism. Our previous work provided a mechanistic link between the two by showing how multiple toxin–antitoxin systems, which are present in nearly all bacteria, can cooperate to induce bistable toxin concentrations that result in a heterogeneous population of slow- and fast-growing cells. As such, the slow-growing persisters are a bet-hedging subpopulation maintained under normal conditions. For technical reasons, the model assumed that the kinetic parameters of the various toxin–antitoxin systems in the cell are identical, but experimental data indicate that they differ, sometimes dramatically. Thus, a critical question remains: whether toxin–antitoxin systems from the diverse families, often found together in a cell, with significantly different kinetics, can cooperate in a similar manner. Here, we characterize the interaction of toxin–antitoxin systems from many families that are unrelated and kinetically diverse, and identify the essential determinant for their cooperation. The generic architecture of toxin–antitoxin systems provides the potential for bistability, and our results show that even when they do not exhibit bistability alone, unrelated systems can be coupled by the growth rate to create a strongly bistable, hysteretic switch between normal (fast-growing) and persistent (slow-growing) states. Different combinations of kinetic parameters can produce similar toxic switching thresholds, and the proximity of the thresholds is the primary determinant of bistability. Stochastic fluctuations can spontaneously switch all of the toxin–antitoxin systems in a cell at once. The spontaneous switch creates a heterogeneous population of growing and non-growing cells, typical of persisters, that exist under normal conditions, rather than only as an induced response. The frequency of persisters in the population can be tuned for a particular environmental niche by mixing and matching unrelated systems via mutation, horizontal gene transfer and selection. PMID:26063817

  12. FACTORS INVOLVED IN PRODUCTION OF CLOSTRIDIUM WELCHII ALPHA TOXIN

    PubMed Central

    Adams, Mark H.; Hendee, Edelmira D.; Pappenheimer, A. M.

    1947-01-01

    Maximum production of the alpha toxin by Cl. welchii is dependent on the inclusion in the medium of several substances in addition to those required for growth. These factors include: 1. Some substance present in enzymatic digests of certain proteins such as casein and gelatine. 2. Glycerylphosphorylcholine and other substances that are present in extracts of pancreas. 3. The use of starch or dextrin as a carbohydrate source in the absence of other fermentable carbohydrates. The omission of any one of these factors from the medium results in a very low yield of alpha toxin. PMID:19871644

  13. Fate of benzoate paralytic shellfish poisoning toxins from Gymnodinium catenatum in shellfish and fish detected by pre-column oxidation and liquid chromatography with fluorescence detection.

    PubMed

    Vale, Paulo

    2008-05-01

    Several cultured strains of Gymnodinium catenatum isolated worldwide have been shown to produce important proportions of the recently discovered benzoate paralytic shellfish poisoning (PSP) toxins GC1 through GC3. These toxins pose a new challenge for the HPLC analysis of shellfish predating during blooms of this microalga because due to their hydrophobicity are retained along the C18 solid-phase extraction step employed to eliminate interferences. The production of GC toxins was confirmed in a clone of G.catenatum isolated from the Portuguese Northwest coast during the winter bloom of 2005, in addition to a clone from 1989 reported previously by other authors. The major peroxide oxidation products of GC1+2 and GC3 were, respectively, dcGTX2+3 and dcSTX. The search of benzoate analogues in bivalves contaminated during the winter 2005 bloom showed these analogues constituted a minor component of the N(1)-H containing toxins, as selectively detected by peroxide oxidation. While in G.catenatum GC1-3 were the major components after C1+2 and B1, in bivalves dcGTX2+3 and dcSTX were the major components after C1+2 and B1. Similar conclusions were later extended to more shellfish species naturally contaminated during the autumn bloom of 2007. In the gut content of sardines GC toxins were present, while in crabs predating upon shellfish, these were absent. A generalised conversion of GC toxins into decarbamoyl analogues was confirmed by in vitro incubations of bivalve's digestive glands with semi-purified GC toxins. This is the first report of widespread carbamoylase activity in shellfish, exclusively targeted at benzoate PSP analogues and that is heat-inactivated. Despite the high proportion of benzoate analogues produced by G.catenatum, analyses of bivalves contaminated with PSP toxins seem to be simplified due to the important conversion of benzoate into decarbamoyl analogues that occurs in bivalves. These last analogues are detected by common HPLC methods used for food protection. PMID:18371975

  14. Development of a quail embryo model for the detection of botulinum toxin type A activity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Clostridium botulinum is a ubiquitous microorganism which under certain anaerobic conditions can produce botulinum toxins. Due to concerns in regards to both food-borne illness and the potential use of botulinum toxin as a biological weapon, the capability to assess the amount of toxin in a food or...

  15. T-2 toxin, a trichothecene mycotoxin: Review of toxicity, metabolism, and analytical methods

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This review focuses on the toxicity and metabolism of T-2 toxin and the analytical methods used for the determination of T-2 toxin. Among the naturally occurring trichothecenes in food and feed, T-2 toxin is a cytotoxic fungal secondary metabolite produced by various species of Fusarium. Following...

  16. 9 CFR 121.6 - Exemptions for overlap select agents and toxins.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... after identification, the agent or toxin is transferred in accordance with § 121.16 or 42 CFR 73.16 or destroyed on-site by a recognized sterilization or inactivation process; (2) The agent or toxin is secured... or toxin is transferred in accordance with § 121.16 or 42 CFR 73.16 or destroyed on-site by...

  17. 9 CFR 121.6 - Exemptions for overlap select agents and toxins.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... after identification, the agent or toxin is transferred in accordance with § 121.16 or 42 CFR 73.16 or destroyed on-site by a recognized sterilization or inactivation process; (2) The agent or toxin is secured... or toxin is transferred in accordance with § 121.16 or 42 CFR 73.16 or destroyed on-site by...

  18. Xylella fastidiosa plasmid-encoded PemK toxin is an endoribonuclease.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Stable inheritance of pXF-RIV11 in Xylella fastidiosa is conferred by the pemI/pemK plasmid addiction system. PemK serves as a toxin inhibiting bacterial growth; PemI is the corresponding antitoxin that blocks activity of PemK toxin by direct binding. PemK toxin and PemI antitoxin were over-expre...

  19. 77 FR 31975 - Shiga Toxin-Producing Escherichia coli in Certain Raw Beef Products

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-31

    ... Service 9 CFR Parts 416, 417, and 430 Shiga Toxin-Producing Escherichia coli in Certain Raw Beef Products... toxin-producing Escherichia coli (STEC), in addition to E. coli O157:H7, in raw beef manufacturing... toxin-producing Escherichia coli (STEC) O26, O45, O103, O111, O121, and O145 are adulterated within...

  20. 9 CFR 121.10 - Restricting access to select agents and toxins; security risk assessments.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... and toxins; security risk assessments. 121.10 Section 121.10 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE VIRUSES, SERUMS, TOXINS, AND ANALOGOUS PRODUCTS; ORGANISMS AND VECTORS POSSESSION, USE, AND TRANSFER OF SELECT AGENTS AND TOXINS §...