• Toxicological Research
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• v.28 no.1
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• pp.19-24
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• 2012

In the present study, toxicity of silver nanoparticles (AgNPs) was investigated in the nematode, Caenohabditis elegans focusing on the upstream signaling pathway responsible for regulating oxidative stress, such as mitogen-activated protein kinase (MAPK) cascades. Formation of reactive oxygen species (ROS) was observed in AgNPs exposed C.elegans, suggesting oxidative stress as an important mechanism in the toxicity of AgNPs towards C. elegans. Expression of genes in MAPK signaling pathways increased by AgNPs exposure in less than 2-fold compared to the control in wildtype C.elegans, however, those were increased dramatically in sod-3 (gk235) mutant after 48 h exposure of AgNPs (i.e. 4-fold for jnk-1 and mpk-2; 6-fold for nsy-1, sek-1, and pmk-1, and 10-fold for jkk-1). These results on the expression of oxidative stress response genes suggest that sod-3 gene expression appears to be dependent on p38 MAPK activation. The high expressions of the pmk-1 gene 48 h exposure to AgNPs in the sod-3 (gk235) mutant can also be interpreted as compensatory mechanisms in the absence of important stress response genes. Overall results suggest that MAPK-based integrated stress signaling network seems to be involved in defense to AgNPs exposure in C.elegans.

• Journal of Ginseng Research
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• v.31 no.4
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• pp.210-216
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• 2007

The backbone structure of ginsenosides, active ingredients of Panax ginseng, is similar with that of sterol, especially cholesterol. Caenorhabditis elegans (c. elegans) is one of free living nematodes and is well-established animal model for biochemical and genetic studies. C. elegans cannot synthesize de novo cholesterol, although cholesterol is essential requirement for its growth and development. In the present study, we investigated the effects of Korean red ginseng total extract (KRGE), ginseng total saponins (GTS) on life span of C. elegans in cholesterol-deprived and -fed medium. Cholesterol deprivation caused damages on life span of worms throughout F1 to F3 generations. KRGE or GTS supplement to cholesterol-deprived medium restored the life span of worms as much as cholesterol alone-fed medium. In study to identify which ginsenosides are responsible for life span restoring effects of KRGE, we found that ginsenoside Rc supplement not only restored life span of worms grown in cholesterol-deprived medium but also prolonged life span of worms grown in cholesterol-fed medium. These results show a possibility that ginsenosides could be utilized by C. elegans as a sterol substitute and further indicate that ginsenoside Rc is the effective component of Korean red ginseng that prolongs the life span of C. elegans.

• BMB Reports
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• v.44 no.2
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• pp.96-101
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• 2011

Calcineurin is a serine/threonine protein phosphatase controlled by $Ca^{2+}$ and calmodulin that has been implicated in various signaling pathways. Previously, we reported that calcineurin regulates coelomocyte endocytosis in Caenorhabditis elegans. So far, simple and powerful in vivo approaches have been developed to study various endocytic processes in C. elegans. Using these in vivo assays, we further analyzed the endocytic phenotypes of calcineurin mutants. We observed that the calcineurin mutants were defective in apical endocytosis in the intestine as well as synaptic vesicle recycling in the nerve cord. However, we found that calcineurin mutants displayed normal receptor-mediated endocytosis in oocytes. Therefore, our results suggest that calcineurin may regulate specific sets of endocytic processes in nematode.

• Journal of the Korean Society of Food Science and Nutrition
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• v.42 no.5
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• pp.670-674
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• 2013

The free radical theory of aging suggests that oxidative damage caused by free radicals plays a key role in normal aging. We measured the anti-oxidant activity of acorns and asked whether it can modulate the aging process in Caenorhabditis elegans. Different concentrations of acorn powder were added to culture medium, followed by the monitoring of fertility and survival under oxidative stress. The anti-oxidant activity of 500 mg/L of acorn powder exhibited significant increases in the resistance to oxidative stress in vivo. Acorn powder also significantly extended both the mean and maximum lifespan of C. elegans (the mean lifespan was increased up to 22.4%). The fertility assay indicates the lifespan extension from acorn does not accompany a reduced reproduction, which is common in long-lived mutants. These findings indicate that acorn has a strong antioxidant activity and can induce longevity without the trade-off of reduced reproduction in C. elegans.

• Journal of Life Science
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• v.29 no.10
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• pp.1120-1125
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• 2019

The short-lived nematode Caenorhabditis elegans has been used as a model organism for many studies, including lifespan extension. To screen common seaweeds for natural anti-aging agents, the lifespan of C. elegans (N2 wild-type strain) was measured by its hatch rate, growth rate, survival rate, chemotaxis, brood size, and egg-laying time after exposure to nematode growth medium (NGM) containing seaweed extracts. Approximately 30 animals synchronized at the first larval stage were incubated until they reached their adult stages before laying their eggs and were transferred to fresh NGM every 3 days. We also identified the major active compound from the seaweed by gas chromatography-mass spectrometry and tested its optimal dose for longevity. Of 13 common seaweed species, an ethanol extract of the brown seaweed Hizikia fusiformis showed the greatest effect on hatching, growth, and survival rates. The lifespan of C. elegans was significantly expanded 1.54-fold and 1.23-fold in the presence of the ethanol extract (0.05 mg/ml) and the main active component, fucosterol (0.05 mg/ml), respectively. Exposure to the ethanol extract also increased chemotaxis 1.13-fold, decreased brood size 0.74-fold, and shortened egg-laying time 0.96-fold. These results suggest that the aquaculturable H. fusiformis may be a promising source of a diet supplement to support health care.

• Journal of Microbiology and Biotechnology
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• v.24 no.9
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• pp.1269-1279
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• 2014

Xanthomonas oryzae pv. oryzae (Xoo) strains are plant pathogenic bacteria that can cause serious blight of rice, and their virulence towards plant host is complex, making it difficult to be elucidated. Caenorhabditis elegans has been used as a powerful model organism to simplify the host and pathogen system. However, whether the C. elegans is feasible for studying plant pathogens such as Xoo has not been explored. In the present work, we report that Xoo strains PXO99 and JXOIII reduce the lifespan of worms not through acute toxicity, but in an infectious manner; pathogens proliferate and persist in the intestinal lumen to cause marked anterior intestine distension. In addition, Xoo triggers (i) the p38 MAPK signal pathway to upregulate its downstream C17H12.8 expression, and (ii) the DAF-2/DAF-16 pathway to upregulate its downstream gene expressions of mtl-1 and sod-3 under the condition of daf-2 mutation. Our findings suggest that C. elegans can be used as a model to evaluate the virulence of Xoo phytopathogens to host.

• Environmental Analysis Health and Toxicology
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• v.30
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• pp.7.1-7.7
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• 2015

Objectives The widely promising applications of graphene nanomaterials raise considerable concerns regarding their environmental and human health risk assessment. The aim of the current study was to evaluate the toxicity profiling of graphene family nanano-materials (GFNs) in alternative in vitro and in vivo toxicity testing models. Methods The GFNs used in this study are graphene nanoplatelets ([GNPs]-pristine, carboxylate [COOH] and amide [$NH_2$]) and graphene oxides (single layer [SLGO] and few layers [FLGO]). The human bronchial epithelial cells (Beas2B cells) as in vitro system and the nematode Caenorhabditis elegans as in vivo system were used to profile the toxicity response of GFNs. Cytotoxicity assays, colony formation assay for cellular toxicity and reproduction potentiality in C. elegans were used as end points to evaluate the GFNs' toxicity. Results In general, GNPs exhibited higher toxicity than GOs in Beas2B cells, and among the GNPs the order of toxicity was pristine > $NH_2$ > COOH. Although the order of toxicity of the GNPs was maintained in C. elegans reproductive toxicity, but GOs were found to be more toxic in the worms than GNPs. In both systems, SLGO exhibited profoundly greater dose dependency than FLGO. The possible reason of their differential toxicity lay in their distinctive physicochemical characteristics and agglomeration behavior in the exposure media. Conclusions The present study revealed that the toxicity of GFNs is dependent on the graphene nanomaterial's physical forms, surface functionalizations, number of layers, dose, time of exposure and obviously, on the alternative model systems used for toxicity assessment.

• Molecules and Cells
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• v.38 no.3
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• pp.236-242
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• 2015

Intake of caffeine during pregnancy can cause retardation of fetal development. Although the significant influence of caffeine on animal development is widely recognized, much remains unknown about its mode of action because of its pleiotropic effects on living organisms. In the present study, by using Caenorhabditis elegans as a model organism, the effects of caffeine on development were examined. Brood size, embryonic lethality, and percent larval development were investigated, and caffeine was found to inhibit the development of C. elegans at most of the stages in a dosage-dependent fashion. Upon treatment with 30 mM caffeine, the majority ($86.1{\pm}3.4%$) of the L1 larvae were irreversibly arrested without further development. In contrast, many of the late-stage larvae survived and grew to adults when exposed to the same 30 mM caffeine. These results suggest that early-stage larvae are more susceptible to caffeine than later-stage larvae. To understand the metabolic responses to caffeine treatment, the levels of expression of cytochrome P450 (cyp) genes were examined with or without caffeine treatment using comparative microarray, and it was found that the expression of 24 cyp genes was increased by more than 2-fold (p < 0.05). Among them, induction of the cyp-35A gene family was the most prominent. Interestingly, depletion of the cyp-35A family genes one-by-one or in combination through RNA interference resulted in partial rescue from early larval developmental arrest caused by caffeine treatment, suggesting that the high-level induction of cyp-35A family genes can be fatal to the development of early-stage larvae.

• Animal cells and systems
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• v.16 no.4
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• pp.280-288
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• 2012

Targeted degradation of proteins through ubiquitin-mediated proteolysis is an important control mechanism in various cellular processes. The process of ubiquitin conjugation is achieved by three enzyme complexes, among which the ubiquitin ligase complex (E3) is in charge of substrate specificity. The SCF (SKP1-CUL1-F-box) family portrays the largest and the most characterized member of the E3 ligases. For each SCF complex, the ubiquitination target is recognized by the F-box protein subunit, which interacts with the substrate through a unique C-terminal domain. We have characterized a novel F-box protein CFL-1 that represents a single LRR-type F-box (FBXL) in the Caenorhabditis elegans genome. CFL-1 is highly homologous to FBXL20 and FBXL2 of mammals, which are known to regulate synaptic vesicle release and cell cycle, respectively. A green fluorescence protein (GFP)-reporter gene fused to the cfl-1 promoter showed restricted expression around the amphid and the anus. Modulation of CFL-1 activity by RNAi affected the time interval between defecations. RNAi-treated worms also exhibited reduced tendency to form dauer when exposed to daumone. The potential involvement of CFL-1 in the control of defecation and pheromone response adds to the ever expanding list of cellular processes controlled by ubiquitin-mediated proteolysis in C. elegans. We suggest that CFL-1, as a single LRR-type F-box protein in C. elegans, may portray a prototype gene exerting diverse functions that are allocated among multiple FBXLs in higher organisms.

• Molecules and Cells
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• v.28 no.3
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• pp.209-213
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• 2009

Caenorhabditis elegans is a free living soil nematode and thus in its natural habitat, C. elegans encounters many different species of soil bacteria. Although some soil bacteria may be excellent sources of nutrition for the worm, others may be pathogenic. Thus, we undertook a study to understand how C. elegans can identify their preferred food using a simple behavioral assay. We found that there are various species of soil bacteria that C. elegans prefers in comparison to the standard laboratory E. coli strain OP50. In particular, two bacterial strains, Bacillus mycoides and Bacillus soli, were preferred strains. Interestingly, the sole feeding of these bacteria to wild type animals results in extended lifespan through the activation of the autophagic process. Further studies will be required to understand the precise mechanism controlling the behavior of identification and selection of food in C. elegans.