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FEMS Yeast Res,
2018]
Candida albicans, one most prevalent fungal pathogen, causes severe mucosal and invasive infections in predisposed individuals. The rise of fungal infection and drug-resistance demands the development of novel antifungal agents. In this study, we observed that floricolin C (FC), a p-terphenyl pigment from an endolichenic fungus, killed C. albicans cells at planktonic state or within biofilms through reactive oxygen species (ROS) accumulation. Further test revealed that FC could directly damage the mitochondria to cause ROS accumulation. In addition, FC can quench thiol-based agents through a Michael reaction involving the ,-unsaturated carbonyl group, whose effect may chelate intracellular thiol-based molecules or proteins in C. albicans, resulting in imbalance of redox homeostasis. Increased ROS generation led to mitochondria dysfunction, nuclear dispersion, and consequently cell death. We further demonstrated that FC could prevent biofilm formation of other Candida species and eradicate their pre-formed biofilms. In vivo study demonstrated that FC prolonged the survival of C. albicans-infected Caenorhabditis elegans. Taken together, our study provides a basis for the application of FC to combat Candida infections.
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Am J Trop Med Hyg,
2007]
The pathologic manifestations of Onchocerca volvulus infection depend on the interplay between the host and the parasite. A genetic single nucleotide polymorphism in the Fc gamma RIIa gene, resulting in arginine (R) or histidine (H) at position 131, affects the binding to the different IgG subclasses and may influence the clinical variations seen in onchocerciasis. This study investigated the relationship between this polymorphism and disease outcome. Fc gamma RIIa genotyping was performed on clinically characterized onchocerciasis patients (N = 100) and healthy controls (N = 74). Fc gamma RIIa genotype R/R131 frequencies were significantly higher among patients with severe dermatopathology (P < 0.001). Increased risk of developing this form was mostly associated with one tribe (Masalit) (OR = 3.2, 95% CI 1-9.9, P = 0.042). The H131 allele was found to be significantly associated with a reduced risk of having the severe form of the disease (adjusted OR = 0.26, 95% CI = 0.13-0.46, P < 0.001). Our findings suggest that the polymorphism influences the clinical outcome of onchocerciasis.
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Chemistry,
2011]
A simple, sensitive, and highly specific lipid targeting Raman probe (Nile red coated silver nanoparticles) has been developed to image living nematode Caenorhabditis elegans (C. elegans). Our idea of imaging lipids in C. elegans is to combine the specificity of the fluorescent dye, Nile red, and the highly enhanced Raman scattering on the silver nanoparticles. Our strategy involves the fabrication of a lipid targeting probe, which is incorporated into the intracellular intestinal granules of C. elegans by incubating these worms in the solution containing Raman probes, resulting in an uptake and subsequent incorporation of these Raman probes into the intestinal granule, thus allowing fast visualization of lipid droplets through a conventional confocal imaging technique.
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Bioorg Med Chem,
2011]
A series of 30 organic chlacones and 33 ferrocenyl (Fc) chalcones were synthesized and characterized by melting point, elemental analysis, spectroscopy ((1)H NMR and FTIR) and, in two cases, by X-ray crystallography. The biological activity of each compound (10(-4)M in DMSO) against the model nematode Caenorhabditis elegans was examined in terms of % mortality (percent nematodes that died) and % fecundity (percent nematodes that reproduced) and compared to that obtained for the control medium (1% DMSO) over a 14-day period. Detailed conformational analyses for two Fc-chalcones (studied also by X-ray crystallography) were performed via molecular modeling studies. In general, the organic chalcones were found to be less polar than their Fc analogs. Some structure-activity relationships (SARs) were determined: (a) The nematocidal activities of the organic chalcones in this series were found to be much greater than those of their ferrocenyl analogs. (b) The position of the carbonyl group played a central role in the biological activity of both classes of chalcones studied. (c) For both classes of chalcones, lipophilicity of a compound seemed to play a significant role in its nematocidal activity. (d) The planarity of a ferrocenyl-chlacone seems to play a role in its activity.
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J Biol Chem,
2006]
Hemicentins are conserved extracellular matrix proteins characterized by a single von Willebrand A (VWA) domain at the amino-terminus, a long stretch (>40) of tandem immunoglobulin domains, multiple tandem EGFs and a single fibulin-like carboxy-terminal (FC) module. In C. elegans, hemicentin is secreted from muscle and gonadal leader cells and assembles at multiple locations into discrete tracks that constrict broad regions of cell contact into adhesive and flexible line-shaped junctions. To determine hemicentin domains critical for function and assembly, we have expressed fragments of hemicentin as GFP tagged fusion proteins in C. elegans. We find that a hemicentin fragment containing the VWA domain can target to multiple assembly sites when expressed under the control of either endogenous hemicentin regulatory sequences or the muscle specific
unc-54 promoter. A hemicentin fragment containing the EGF and FC modules can co-assemble with existing hemicentin polymers in wild-type animals but has no detectable function in the absence of endogenous hemicentin. The data suggest that the VWA domain is a cell binding domain whose function is to target hemicentin to sites of assembly and the EGF/FC modules constitute an assembly domain that mediates direct interactions between hemicentin monomers during the hemicentin assembly process.
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Dev Comp Immunol,
2014]
Caenorhabditis elegans exhibits protective immunity against a variety of fungal and bacterial pathogens. Since C. elegans lacks an adaptive immune system, pathogen recognition is mediated entirely by innate immunity. To date, little is known about the involvement of pattern recognition receptors (PRRs) in pathogen sensing as part of the C. elegans immunity. C-type lectin-like domain (CTLD) containing proteins represent a superfamily of PRRs. A large number of genes encoding for CTLD proteins are present in the C. elegans genome, however the role of CTLD proteins in bacterial recognition and antibacterial immunity has not yet been determined. In this study, we investigated the function of selected C. elegans CTLD proteins during infection with the Gram-negative bacterium Serratia marcescens. Wild-type and CTLD gene-deficient C. elegans strains were compared in their susceptibility to S. marcescens infection. Interestingly, survival and egg laying were significantly reduced in strains deficient for
clec-39 and
clec-49 indicating a role for both CTLD proteins in C. elegans immune defense against bacteria as evidenced by using S. marcescens infection. Binding studies with recombinantly expressed Clec-39-Fc and Clec-49-Fc fusion proteins revealed that both CTLD proteins recognized live bacteria in a Ca(2+)-independent manner. This study provides insight into the role of CTLD proteins in C. elegans immunity and demonstrates their function during bacterial infection.
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J Biol Chem,
2012]
Proper N- and O-glycosylation of recombinant proteins is important for their biological function. Although the N-glycan processing pathway of different expression hosts has been successfully modified in the past, comparatively little attention has been paid to the generation of customized O-linked glycans. Plants are attractive hosts for engineering of O-glycosylation steps, as they contain no endogenous glycosyltransferases that perform mammalian-type Ser/Thr glycosylation and could interfere with the production of defined O-glycans. Here, we produced mucin-type O-GalNAc and core 1 O-linked glycan structures on recombinant human erythropoietin fused to an IgG heavy chain fragment (EPO-Fc) by transient expression in Nicotiana benthamiana plants. Furthermore, for the generation of sialylated core 1 structures constructs encoding human polypeptide:N-acetylgalactosaminyltransferase 2, Drosophila melanogaster core 1 1,3-galactosyltransferase, human 2,3-sialyltransferase, and Mus musculus 2,6-sialyltransferase were transiently co-expressed in N. benthamiana together with EPO-Fc and the machinery for sialylation of N-glycans. The formation of significant amounts of mono- and disialylated O-linked glycans was confirmed by liquid chromatography-electrospray ionization-mass spectrometry. Analysis of the three EPO glycopeptides carrying N-glycans revealed the presence of biantennary structures with terminal sialic acid residues. Our data demonstrate that N. benthamiana plants are amenable to engineering of the O-glycosylation pathway and can produce well defined human-type O- and N-linked glycans on recombinant therapeutics.
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Biophys J,
2014]
Brief heat shocks delivered to cells by pulsed laser light can evoke action potentials in neurons and contraction in cardiomyocytes, but the primary biophysical mechanism has been elusive. In this report we show in the neuromuscular junction of Caenorhabditis elegans that application of a 500C/s heat shock for 500 s evoked ~35 pA of excitatory current and injected ~23 fC(femtocoulomb) of charge into the cell while raising the temperature only 0.25C. The key variable driving the current was the rate of change of temperature (dT/dt heat shock), not temperature itself. The photothermal heat shock current was voltage-dependent and was from thermally driven displacement of ions near the plasma membrane. The charge movement was rapid during the heat shock and slow during thermal relaxation, thus leading to an asymmetrical capacitive current that briefly depolarized the cell. A simple quantitative model is introduced to describe modulation of the membrane potential and facilitate practical application of optical heat shock stimuli.
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International Worm Meeting,
2017]
The nematode-trapping fungus A. oligospora produces odors that mimic sex and food cues to attract many nematode species (Hsueh et al. 2017). One of the compounds (MMB) that likely mimics male pheromone in Canerhbiditis nematodes is highly attractive to two lab strains of C. elegans (N2 and Hawaiian). To investigate whether this attraction is highly conserved among the wild-isolates, we analyzed the MMB chemotaxis behavior among the C. elegans wild isolates from the CeNDR collection. We found that MMB-attraction is highly polymorphic trait. Six out of forty wild-isolates tested exhibited weak attraction to MMB. Genetic analysis showed that this trait is controlled by QTL in some strains but a single locus in others. The high incidence of MMB-insensitive strains among the wild-isolates suggests that lost of MMB attraction might offer benefit to C. elegans in the natural environments. Hsueh YP, Gronquist MR, Schwarz EM, Nath RD, Lee CH, Gharib S, Schroeder FC, Sternberg PW. 2017. Nematophagous fungus Arthrobotrys oligospora mimics olfactory cues of sex and food to lure its nematode prey. eLife 6.
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International Worm Meeting,
2017]
Nematodes and nematode-trapping fungi are both ubiquitously present in the environment. However, little is known about how these predatory fungi interact with their nematode-prey in nature. Our previous findings showed that the nematode-trapping fungi of the Arthrobotrys species eavesdrop on the nematode pheromone ascarosides as an indication of the presence of the nematode prey (Hsueh et al. 2013). We observed that different Arthrobotrys species exhibit different ascaroside-specificity and hypothesized that this might result from the co-evolution between the different species of nematodes and nematode-trapping fungi. To understand what species of nematodes and nematode-trapping fungi co-exist in the natural environment and to acquire material to test our hypothesis, we collected wild-isolates of nematodes and nematode-trapping fungi from different locations in Taiwan and determine the identity of the fungi and nematodes at the species or genus level based on their ITS or 18S rDNA sequences. In total, we successfully isolated both nematodes and nematode-trapping fungi from 13 of the 22 locations sampled. Seven species of Arthrobotrys have been identified to share the same niches with nematodes of the genera Oscheius, Cervidellus, Rhabditis, Caenorhabditis, Pelodera, Diploscapter, Meyerozyma, Acrobeloides, and Mesorhabditis, suggesting that Arthrobotrys species are likely to prey on a broad range of nematode species in nature. Hsueh YP, Mahanti P, Schroeder FC, Sternberg PW. 2013. Nematode-trapping fungi eavesdrop on nematode pheromones. Curr Biol 23: 83-86.