-
[
Science,
1965]
When taken directly from a strain kept for several years at 18C in the laboratory, Caenorhabditis elegans cannot reproduce indefinetely at temperatures higher than 22C. By progressive and very slow increments of the breeding temperature, a strain fecund at 24.5C was obtained.
-
[
Trop Med Parasitol,
1985]
Adult Onchocerca volvulus were transplanted into chimpanzees with or without complete or partial digestion of associated nodule tissue. Survival of adults worms was limited, but low level microfilarial densities remained detectable in skin over partially digested nodule transplants for 12 months. Human nodule tissue transplanted with adult worms showed enhanced survival as compared to subcutaneous tissue transplanted without worms. It is postulated that this reflects the action of an immunosuppressive factor utilized by the parasite to permit its own survival.
-
[
Curr Biol,
2020]
Although cholesterol is considered a vital lipid for animals, not all animals can make cholesterol. A new study employing that celebrated elegant worm, Caenorhabditis elegans, investigates mechanisms that evolved in a sterol auxotroph to enable survival without sterol synthesis.
-
[
PLoS Genet,
2013]
Different interoceptive systems must be integrated to ensure that multiple homeostatic insults evoke appropriate behavioral and physiological responses. Little is known about how this is achieved. Using C. elegans, we dissect cross-modulation between systems that monitor temperature, O and CO. CO is less aversive to animals acclimated to 15C than those grown at 22C. This difference requires the AFD neurons, which respond to both temperature and CO changes. CO evokes distinct AFD Ca responses in animals acclimated at 15C or 22C. Mutants defective in synaptic transmission can reprogram AFD CO responses according to temperature experience, suggesting reprogramming occurs cell autonomously. AFD is exquisitely sensitive to CO. Surprisingly, gradients of 0.01% CO/second evoke very different Ca responses from gradients of 0.04% CO/second. Ambient O provides further contextual modulation of CO avoidance. At 21% O tonic signalling from the O-sensing neuron URX inhibits CO avoidance. This inhibition can be graded according to O levels. In a natural wild isolate, a switch from 21% to 19% O is sufficient to convert CO from a neutral to an aversive cue. This sharp tuning is conferred partly by the neuroglobin GLB-5. The modulatory effects of O on CO avoidance involve the RIA interneurons, which are post-synaptic to URX and exhibit CO-evoked Ca responses. Ambient O and acclimation temperature act combinatorially to modulate CO responsiveness. Our work highlights the integrated architecture of homeostatic responses in C. elegans.
-
[
Z Parasitenkd,
1984]
The surface ultrastructure of male and female adult worms of Onchocerca volvulus obtained from human nodules by the technique of collagenase digestion has been compared with that of worms excised manually without the aid of enzyme treatment. No topographical differences have been identified.
-
[
Biomaterials,
2013]
Carbon nanotubes (CNTs) are one of widely used nanomaterials in industry and biomedicine. The potential impact of single-walled carbon nanotubes (SWCNTs) was evaluated using Caenorhabditis elegans (C. elegans) as a toxicological animal model. SWCNTs are extremely hydrophobic to form large agglomerates in aqueous solutions. Highly soluble amide-modified SWCNTs (a-SWCNTs) were therefore used in the present study so that the exact impact of SWCNTs could be studied. No significant toxicity was observed in C. elegans due to the amide modification. a-SWCNTs were efficiently taken up by worms and caused acute toxicity, including retarded growth, shortened lifespan and defective embryogenesis. The resulting toxicity was reversible since C. elegans could recover from a-SWCNT-induced toxicity once the exposure terminates. Chronic exposure to low doses of a-SWCNTs during all development stages could also cause a toxic accumulation in C. elegans. Genome-wide gene expression analysis was performed to investigate the toxic molecular mechanisms. Functional genomic analysis and molecular biology validation suggest that defective endocytosis, the decreased activity of the citrate cycle and the reduced nuclear translocation of DAF-16 transcription factor play key roles in inducing the observed a-SWCNT toxicity in worms. The present study presents an integrated approach to evaluating the toxicity of nanomaterials at the organism and molecular level for human and environmental health and demonstrates that traditional toxicological endpoints associated with functional genomic analysis can provide global and thorough insight into toxicity.
-
[
Neuron,
2021]
How do organisms without specialized auditory systems perceive and transduce sound? In this issue of Neuron, Iliff etal. (2021) investigate the functional mechanism of airborne sound sensation in Caenorhabditis elegans and highlight the crucial role of alpha-7 nicotinic acetylcholine receptor subunits in mechanotransduction.
-
[
Parasitol Int,
2016]
A method for purifying active liquid-cultured Caenorhabditis elegans using a modified Baermann apparatus is described. This method consists of two parts: 1) large-scale cultivation of C. elegans in liquid medium and 2) preparation of active nematodes without contamination using the Baermann apparatus.
-
[
Freshw Biol,
2005]
1. Biotic interaction between the ciliate Cyclidium glaucoma and the nematode Caenorhabditis elegans was investigated by manipulating the densities of the organisms in microcosms with and without sediment. 2. After 11 days the abundance of ciliates, nematodes and bacteria as well as extracellular enzyme activity were determined. Ciliates had a negative effect on nematode abundance in microcosms without sediment and in microcosms with sandy sediment, whereas in muddy sediment the effect was less distinctive. An effect of nematodes on ciliates was not observed. 3. The common resource bacteria were not affected negatively by the activity of the grazers. Overall grazer biomass increased with the addition of sediment to the microcosms, suggesting a rise of the carrying capacity in the experimental system. Especially in muddy sediment the abundance of bacteria and extracellular enzyme activity was higher compared to the microcosms without sediment. 4. The results of the experiment suggest a strong interspecific competition between nematodes and ciliates, where nematodes are, at least temporary, strongly affected.
-
[
Biosci Biotechnol Biochem,
2007]
New nematicides named fumiquinones A (1) and B (2), together with spinulosin (3), LL-S490beta (4), and pseurotin A (5), were isolated from Aspergillus fumigatus and their structures were established by spectroscopic methods including 2D-NMR. Compound 1 showed effective nematicidal activities against Bursaphelenchus xylophilus and Pratylenchus penetrans without inhibiting plant growth except for lettuce seedlings. Compound 2 showed effective nematicidal activity against B. xylophilus, but had no inhibitory activity against P. penetrans. Compounds 3-5 showed effective nematicidal activities against B. xylophilus without any plant growth inhibition. Compounds 1-5 had no nematicidal activity against Caenorhabditis elegans. This is the first report of the nematicidal activities of compounds 3-5.