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[
J Parasitol,
2000]
When eggs of the trichostrongylid nematode Haemonchus contortus were exposed to thiabendazole, the concentration required to prevent hatching in 90% of the eggs (MIC90) was found to be 0.1 mu g/ ml (using 1% dimethylsulfoxide [DMSO] as solvent). In contrast, eggs of the free-living rhabditid nematode Caenorhabditis elegans hatched at normal rates at a concentration 200 times higher, i.e., 20 mu g/ml, and showed only a partial inhibitory effect at a concentration 1,200 times higher, i.e., 120 mu g/ml (in 3% DMSO). Because solubility limitations precluded the testing of higher concentrations of thiabendazole, a more soluble derivative, 5-([1-methylethoxyl carbonylamino)-2-(4-thiazloyl)-1H-benzimidazolyliminoacetic acid N,N-diethylethanamine salt, was rested against C. elegans eggs. The MIC90 was found to be 400 mu g/ml, and although the derivative was not tested against H. contortus eggs, this finding further suggests that C. elegans eggs have an exceptionally low degree of benzimidazole sensitivity.
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[
Worm Breeder's Gazette,
2001]
In the routine propagation of C. elegans, steam sterilization of the culture medium is standard practice, but in some circumstances it is inconvenient, impractical, or prone to error. In preliminary experiments in this lab, thiabendazole (TBZ) was added to C. elegans cultures in the expectation that the life cycle would be interrupted because of the well-known efficacy of the compound in preventing the development and hatching of nematode eggs. Surprisingly, the propagation of C. elegans appeared to be unaffected. Subsequent investigation showed that TBZ is without ovicidal efficacy against C elegans at concentrations that are fully effective against the eggs of the parasitic nematode Haemonchus contortus (Fasiuddin and Campbell, 2000). The qualitative observations here reported suggest the possibility of exploiting this finding to achieve a useful degree of microbial control in laboratory cultures. TBZ was added to modified Nematode Growth Medium (Avery and Horowitz, 1990) at 20 microg/ml -- a concentration known to be ovicidal for nematodes (Egerton, 1969) and to have a broad spectrum of antifungal activity (Robinson et al., 1969). Methylene Blue, at 0.0002%, was added as a marker to prevent inadvertent mix-up in routine transfer operations (qualitative observations in this lab had indicated that such a concentration did not suppress the growth of the Escherichia coli seeded onto agar plates as food for C. elegans ). The medium was boiled briefly to dissolve and clarify the agar, but it was not autoclaved. TBZ and Methylene Blue were added while the medium was still hot. TBZ was prepared as a solution of 10 mg/ml in 100% dimethyl sulfoxide and added to the medium so as to give a 500 fold dilution. An aqueous solution of Methylene Blue, 0.1%, was similarly added to give a 500 fold dilution. After dispensing the medium into 90-mm petri dishes, a suspension of E. coli (OP 50) was spread on the solidified medium and allowed to form a bacterial lawn in the usual way. Three days after the initial (October 8, 1999) preparation of the plates, 2 plates were inoculated with C. elegans ; and single plates were inoculated with worms on day 28, 46, 55, 63 and 88. The plates were held in a humidity chamber at room temperature, without further addition of bacteria. Periodic microscopic examination of the dishes revealed prolific propagation of C. elegans , followed by the persistence of low numbers of motile worms (presumably dauer larvae) at intervals up to day 367 after inoculation of the first 2 plates. At that time, medium from each dish was transferred, without sterile technique, to conventional agar plates, resulting in abundant propagation of worms in all cases. Another batch of 17 culture plates was prepared in a similar non-aseptic way, but without the addition of Methylene Blue. This batch has remained in a refrigerator for 9 months, during which time small compact colonies (presumably bacterial) have appeared, but there has been no trace of the mycelial fungal contaminants so commonly observed when sterilization and handling procedures have been imperfect. The preparation of these two batches of non-sterilized culture plates was not accompanied by the simultaneous preparation of autoclaved plates, or plates with dimethyl sulfoxide or Methylene Blue as the only additive; but throughout the test period conventional plates, without additives, were being routinely made and used. Nor was any attempt made to expose the plates to known air-borne contaminants or to inoculate them with bacteria or fungi. Nevertheless, the absence of visible mycelial growth was in marked contrast to the degree of contamination customarily seen when sterility measures have been less than rigorous, and the year-long persistence of C. elegans was also striking. If these findings can be confirmed in quantitative trials, supplementation of a medium with TBZ in a dimethyl sulfoxide vehicle (with an antibacterial adjunct) may provide a convenient 'limited contamination' medium for the routine maintenance of C. elegans . Other antimycotic agents are available for use in culture systems. In the present context, the most useful characteristics of TBZ are its very long shelf life at room temperature, its stability in media when boiled or even autoclaved, and the degree to which this otherwise antinematodal agent is tolerated by the nematode C. elegans . Methylene Blue has some degree of antibacterial efficacy and, at the concentration used here, was tolerated by both the worm and the bacterium on which it feeds. Other compounds with selective antibacterial activity may be more effectively combined with TBZ to suppress unwanted bacteria in C. elegans cultures. References. Avery, L and H. R. Horvitz. 1990. Effects of starvation and neuroactive drugs of feeding in Caenorhabditis elegans . J. Experimental Zoology 253: 263- 270. Egerton, J. R. 1969. The ovicidal and larvicidal effect of thibendazole on various helminth species. Texas Reports on Biology and Medicine (Suppl. 2) 27: 561 - 580. Fasiuddin, A. and W. C. Campbell. 2000. Haemonchus contortus (Nematoda: Trichostrongylidae) is much more sensitive than Caenorhabditis elegans to the ovicidal action of thiabendazole. Journal of Parasitology 86: 628-630. Robinson, H. J., R. H. Silber and O. E. Graessle. 1967. Thiabendazole: toxicological, pharmacological and antifungal properties. Texas Reports on Biology and Medicine (Suppl. 2) 27: 537-560.
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Pennington PR, Heistad RM, Nyarko JNK, Barnes JR, Bolanos MAC, Parsons MP, Knudsen KJ, De Carvalho CE, Leary SC, Mousseau DD, Buttigieg J, Maley JM, Quartey MO
[
Sci Rep,
2021]
The pool of -Amyloid (A) length variants detected in preclinical and clinical Alzheimer disease (AD) samples suggests a diversity of roles for A peptides. We examined how a naturally occurring variant, e.g. A(1-38), interacts with the AD-related variant, A(1-42), and the predominant physiological variant, A(1-40). Atomic force microscopy, Thioflavin T fluorescence, circular dichroism, dynamic light scattering, and surface plasmon resonance reveal that A(1-38) interacts differently with A(1-40) and A(1-42) and, in general, A(1-38) interferes with the conversion of A(1-42) to a -sheet-rich aggregate. Functionally, A(1-38) reverses the negative impact of A(1-42) on long-term potentiation in acute hippocampal slices and on membrane conductance in primary neurons, and mitigates an A(1-42) phenotype in Caenorhabditis elegans. A(1-38) also reverses any loss of MTT conversion induced by A(1-40) and A(1-42) in HT-22 hippocampal neurons and APOE 4-positive human fibroblasts, although the combination of A(1-38) and A(1-42) inhibits MTT conversion in APOE 4-negative fibroblasts. A greater ratio of soluble A(1-42)/A(1-38) [and A(1-42)/A(1-40)] in autopsied brain extracts correlates with an earlier age-at-death in males (but not females) with a diagnosis of AD. These results suggest that A(1-38) is capable of physically counteracting, potentially in a sex-dependent manner, the neuropathological effects of the AD-relevant A(1-42).
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[
Worm Breeder's Gazette,
2003]
Wormgenes is a new resource for C.elegans offering a detailed summary about each gene and a powerful query system.
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[
Front Pharmacol,
2020]
Oligomeric assembly of Amyloid- (A) is the main toxic species that contribute to early cognitive impairment in Alzheimer's patients. Therefore, drugs that reduce the formation of A oligomers could halt the disease progression. In this study, by using transgenic <i>Caenorhabditis elegans</i> model of Alzheimer's disease, we investigated the effects of frondoside A, a well-known sea cucumber <i>Cucumaria frondosa</i> saponin with anti-cancer activity, on A aggregation and proteotoxicity. The results showed that frondoside A at a low concentration of 1 M significantly delayed the worm paralysis caused by A aggregation as compared with control group. In addition, the number of A plaque deposits in transgenic worm tissues was significantly decreased. Frondoside A was more effective in these activities than ginsenoside-Rg3, a comparable ginseng saponin. Immunoblot analysis revealed that the level of small oligomers as well as various high molecular weights of A species in the transgenic <i>C. elegans</i> were significantly reduced upon treatment with frondoside A, whereas the level of A monomers was not altered. This suggested that frondoside A may primarily reduce the level of small oligomeric forms, the most toxic species of A. Frondoside A also protected the worms from oxidative stress and rescued chemotaxis dysfunction in a transgenic strain whose neurons express A. Taken together, these data suggested that low dose of frondoside A could protect against A-induced toxicity by primarily suppressing the formation of A oligomers. Thus, the molecular mechanism of how frondoside A exerts its anti-A aggregation should be studied and elucidated in the future.
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[
International Journal of Developmental Biology,
1998]
Pleiotropy , a situation in which a single gene influences multiple phenotypic tra its, can arise in a variety of ways. This paper discusses possible underlying mechanisms and proposes a classification of the various phenomena involved.
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[
Curr Biol,
2011]
Recent work on a Caenorhabditis elegans transmembrane ATPase reveals a central role for the aminophospholipid phosphatidylethanolamine in the production of a class of extracellular vesicles.
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[
Naturwissenschaften,
2004]
Animals respond to signals and cues in their environment. The difference between a signal (e.g. a pheromone) and a cue (e.g. a waste product) is that the information content of a signal is subject to natural selection, whereas that of a cue is not. The model free-living nematode Caenorhabditis elegans forms an alternative developmental morph (the dauer larva) in response to a so-called 'dauer pheromone', produced by all worms. We suggest that the production of 'dauer pheromone' has no fitness advantage for an individual worm and therefore we propose that 'dauer pheromone' is not a signal, but a cue. Thus, it should not be called a pheromone.
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[
J Antibiot (Tokyo),
1990]
Cochlioquinone A, isolated from the fungus Helminthosporium sativum, was found to have nematocidal activity. Cochlioquinone A is a competitive inhibitor of specific [3H]ivermectin binding suggesting that cochlioquinone A and ivermectin interact with the same membrane receptor.
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[
J Lab Autom,
2016]
Microfluidic devices offer new technical possibilities for a precise manipulation of Caenorhabditis elegans due to the comparable length scale. C. elegans is a small, free-living nematode worm that is a popular model system for genetic, genomic, and high-throughput experimental studies of animal development and neurobiology. In this paper, we demonstrate a microfluidic system in polydimethylsiloxane (PDMS) for dispensing of a single C. elegans worm into a 96-well plate. It consists of two PDMS layers, a flow and a control layer. Using five microfluidic pneumatic valves in the control layer, a single worm is trapped upon optical detection with a pair of optical fibers integrated perpendicular to the constriction channel and then dispensed into a microplate well with a dispensing tip attached to a robotic handling system. Due to its simple design and facile fabrication, we expect that our microfluidic chip can be expanded to a multiplexed dispensation system of C. elegans worms for high-throughput drug screening.