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[
Biofouling,
2015]
The emergence of antibiotic resistant Staphylococcus aureus presents a worldwide problem that requires non-antibiotic strategies. This study investigated the anti-biofilm and anti-hemolytic activities of four red wines and two white wines against three S. aureus strains. All red wines at 0.5-2% significantly inhibited S. aureus biofilm formation and hemolysis by S. aureus, whereas the two white wines had no effect. Furthermore, at these concentrations, red wines did not affect bacterial growth. Analyses of hemolysis and active component identification in red wines revealed that the anti-biofilm compounds and anti-hemolytic compounds largely responsible were tannic acid, trans-resveratrol, and several flavonoids. In addition, red wines attenuated S. aureus virulence in vivo in the nematode Caenorhabditis elegans, which is killed by S. aureus. These findings show that red wines and their compounds warrant further attention in antivirulence strategies against persistent S. aureus infection.
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[
C.elegans Neuronal Development Meeting,
2008]
C. elegans hermaphrodites release pheromones that elicit sex-specific responses: males are attracted to the pheromones and hermaphrodites avoid them. Our goal is to purify these pheromones and determine their chemical structures. Here, we focus on the components that elicit male attraction behavior: hermaphrodite sex pheromones. Sex pheromones are released by adult hermaphrodites into liquid culture. The pheromone activities are worm-dependent and not bacterially derived, shown by media containing worms without food (active), and food without worms (inactive). Pheromones are specific to adult hermaphrodites, because media conditioned by males, early larvae, or dauers fail to elicit a wild-type behavioral response. Pheromones are stable at room temperature for more than two weeks, and are heat- and protease-resistant. Fractionation of hermaphrodite-conditioned media based on polar character from relatively small-scale cultures (500,000 to 1 million adult hermaphrodites) shows that attraction activity is consistently found in two sets of fractions, one broad set of more polar fractions (soluble in ~30-50% methanol) and another, narrower set of less polar fractions (soluble in 80% methanol; see previous abstracts White, Chen, and Jorgensen, 2004 SfN, Truong et. al. 2006 WBPaper00028252, White et. al. 2007 WBPaper00030248). These small-scale purifications did not yield amounts sufficient for extensive structural analysis. Fractionation of media from large-scale cultures (10 to 30 million hermaphrodites) shows the same general pattern of attraction activity: a set of more polar fractions, and a set of less polar fractions. Additionally, there is a set of fractions with weaker activity soluble in 50% methanol that may not have been resolved in small-scale purifications. The number and broadness of the attraction activity peaks suggest that hermaphrodite sex pheromones are comprised of multiple compounds. Mixing active fractions does not seem to synergistically increase potency; this and the fact that each set of fractions can separately elicit attraction behavior indicates that sex-pheromone components are at least partly redundant. Multiple, redundant sex pheromones may act to ensure robust behavior under a variety of conditions.
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[
Worm Breeder's Gazette,
1993]
THE C. ELEGANS CLEAVAGE AND POLYADENYLATION SlGNAL Tom Blumenthal, Department of Biology, Indiana University. Bloomington, IN 47405; Owen White and Chris Fields, Institute For Genomic Research, Gaithersburg, MD, 20878
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[
Nematologica,
1976]
The growth promoting activity of protein-haemin co-precipitates from ferritin, apoferritin, transferrin, bovine serum albumin, conalbumin and egg white on maturation and reproduction of C. briggsae has been evaluated. Ferritin, apoferritin and transferrin were found to be biologically highly active in the presence of haemin. Bovine serum albumin, conalbumin and egg white were slightly active. Maturation and reproduction of C. briggsae on the coagulates from bovine serum albumin and egg white were nearly independent of the dose administered, probably because the limited availability of haemin from these coagulates permits but slow growth, even in the presence of abundant proteinaceous material. Bovine serum albumin, egg white and conalbumin failed to support continuous growth of C. briggsae. It is supposed that the limited availability of haemin from these coagulates inhibits normal maturation and reproduction of the F1 progeny. These experiments clearly demonstrate the requirement for particulate haem. The requirement for
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[
J Biol Chem,
2007]
The biological methyl donor, S adenosylmethionine (AdoMet), can exist in two diastereoisomeric states with respect to its sulfonium ion. The "S" configuration, (S,S)AdoMet, is the only form that is produced enzymatically as well as the only form used in almost all biological methylation reactions. Under physiological conditions, however, the sulfonium ion can spontaneously racemize to the "R" form, producing (R,S)AdoMet. As of yet, (R,S)AdoMet has no known physiological function and may inhibit cellular reactions. In this study, two enzymes have been found in Saccharomyces cerevisiae that are capable of recognizing (R,S)AdoMet and using it to methylate homocysteine to form methionine. These enzymes are the products of the SAM4 and MHT1 genes, previously identified as homocysteine methyltransferases dependent upon AdoMet and S-methylmethionine respectively. We find here that Sam4 recognizes both (S,S) and (R,S)AdoMet, but its activity is much higher with the R,S form. Mht1 reacts with only the R,S form of AdoMet while no activity is seen with the S,S form. R,S-specific homocysteine methyltransferase activity is also shown here to occur in extracts of Arabidopsis thaliana, Drosophila melanogaster, and Caenorhabditis elegans, but has not been detected in several tissue extracts of Mus musculus. Such activity may function to prevent the accumulation of (R,S)AdoMet in these organisms.
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[
Worm Breeder's Gazette,
1999]
For everyone who deals with the characterization of expression patterns in the nervous system, the truly impressive paper of White et al., 1986 ("Mind of the Worm") serves as the ultimate source of knowledge. While the largely invariant neural cell body positions described by Sulston et al. are an essential tool in the identification of neurons, the axon morphologies described by White et al. greatly facilitate the identification of a given neuron.
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[
Microsc Microanal,
2014]
A variety of specimens including bacteria, ciliates, choanoflagellates (Salpingoeca rosetta), zebrafish (Danio rerio) embryos, nematode worms (Caenorhabditis elegans), and leaves of white clover (Trifolium repens) plants were high pressure frozen, freeze-substituted, infiltrated with either Epon, Epon-Araldite, or LR White resins, and polymerized. Total processing time from freezing to blocks ready to section was about 6 h. For epoxy embedding the specimens were freeze-substituted in 1% osmium tetroxide plus 0.1% uranyl acetate in acetone. For embedding in LR White the freeze-substitution medium was 0.2% uranyl acetate in acetone. Rapid infiltration was achieved by centrifugation through increasing concentrations of resin followed by polymerization at 100C for 1.5-2 h. The preservation of ultrastructure was comparable to standard freeze substitution and resin embedding methods that take days to complete. On-section immunolabeling results for actin and tubulin molecules were positive with very low background labeling. The LR White methods offer a safer, quicker, and less-expensive alternative to Lowicryl embedding of specimens processed for on-section immunolabeling without traditional aldehyde fixatives.
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Lou Y, Haque A, Freyzon Y, Farese RV, Terry-Kantor E, Hofbauer HF, Termine D, Welte MA, Barrasa MI, Imberdis T, Noble T, Lindquist S, Clish CB, Jaenisch R, Pincus D, Nuber S, Sandoe J, Kohlwein SD, Kim TE, Ho GPH, Ramalingam N, Walther TC, Baru V, Selkoe D, Srinivasan S, Landgraf D, Soldner F, Dettmer U, Fanning S, Becuwe M, Newby G
[
Mol Cell,
2018]
In Parkinson's disease (PD), -synuclein (S) pathologically impacts the brain, a highly lipid-rich organ. We investigated how alterations in S or lipid/fattyacid homeostasis affect each other. Lipidomic profiling of human S-expressing yeast revealed increases in oleic acid (OA, 18:1), diglycerides, and triglycerides. These findings were recapitulated in rodent and human neuronal models of S dyshomeostasis (overexpression; patient-derived triplication or E46K mutation; E46K mice). Preventing lipid droplet formation or augmenting OA increased S yeast toxicity; suppressing the OA-generating enzyme stearoyl-CoA-desaturase (SCD) was protective. Genetic or pharmacological SCD inhibition ameliorated toxicity in S-overexpressing rat neurons. In a C.elegans model, SCD knockout prevented S-induced dopaminergic degeneration. Conversely, we observed detrimental effects of OA on S homeostasis: in human neural cells, excess OA caused S inclusion formation, which was reversed by SCD inhibition. Thus, monounsaturated fatty acid metabolism is pivotal for S-induced neurotoxicity, and inhibiting SCD represents a novel PD therapeutic approach.
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[
PLoS One,
2017]
In this paper, the metabolic activity in single and dual species biofilms of Staphylococcus epidermidis and Staphylococcus aureus isolates was investigated. Our results demonstrated that there was less metabolic activity in dual species biofilms compared to S. aureus biofilms. However, this was not observed if S. aureus and S. epidermidis were obtained from the same sample. The largest effect on metabolic activity was observed in biofilms of S. aureus Mu50 and S. epidermidis ET-024. A transcriptomic analysis of these dual species biofilms showed that urease genes and genes encoding proteins involved in metabolism were downregulated in comparison to monospecies biofilms. These results were subsequently confirmed by phenotypic assays. As metabolic activity is related to acid production, the pH in dual species biofilms was slightly higher compared to S. aureus Mu50 biofilms. Our results showed that S. epidermidis ET-024 in dual species biofilms inhibits metabolic activity of S. aureus Mu50, leading to less acid production. As a consequence, less urease activity is required to compensate for low pH. Importantly, this effect was biofilm-specific. Also S. aureus Mu50 genes encoding virulence-associated proteins (Spa, SplF and Dps) were upregulated in dual species biofilms compared to monospecies biofilms and using Caenorhabditis elegans infection assays, we demonstrated that more nematodes survived when co-infected with S. epidermidis ET-024 and S. aureus mutants lacking functional spa, splF or dps genes, compared to nematodes infected with S. epidermidis ET-024 and wild- type S. aureus. Finally, S. epidermidis ET-024 genes encoding resistance to oxacillin, erythromycin and tobramycin were upregulated in dual species biofilms and increased resistance was subsequently confirmed. Our data indicate that both species in dual species biofilms of S. epidermidis and S. aureus influence each other's behavior, but additional studies are required necessary to elucidate the exact mechanism(s) involved.
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[
Pathog Dis,
2014]
Due to the resistance of Staphylococcus aureus to several antibiotics, treatment of S. aureus infections is often difficult. As an alternative to conventional antibiotics, the field of bacterial interference is investigated. Staphylococcus epidermidis produces a serine protease (Esp) which inhibits S. aureus biofilm formation and which degrades S. aureus biofilms. In this study, we investigated the protease production of 114 S. epidermidis isolates, obtained from biofilms on endotracheal tubes (ET). Most of the S. epidermidis isolates secreted a mixture of serine, cysteine and metalloproteases. We found a link between high protease production by S. epidermidis and the absence of S. aureus in ET biofilms obtained from the same patient. Treating S. aureus biofilms with the supernatant (SN) of the most active protease producing S. epidermidis isolates resulted in a significant biomass decrease compared to untreated controls, while the number of metabolically active cells was not affected. The effect on the biofilm biomass was mainly due to serine proteases. Staphylococcus aureus biofilms treated with the SN of protease producing S. epidermidis were thinner with almost no extracellular matrix. An increased survival of Caenorhabditis elegans, infected with S. aureus Mu50, was observed when the SN of protease positive S. epidermidis was added.