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[
Pestic Biochem Physiol,
2010]
Cypermethrin belongs to the class of synthetic pyrethroids, which are being widely used as an insecticides in agricultural practices. The toxicity of cypermethrin is well studied in Drosophila melanogaster, fish, rats, mice, and is reported to cause neurotoxicity and oxidative stress during its metabolism. In this study, we evaluated the biological consequences of 4 h exposure to cypermethrin at sublethal concentrations (1, 5 and 15 mM) in Caenorhabditis elegans on physiological parameters such as egg laying, brood size, feeding and lifespan and oxidative stress parameters such as ROS, hydrogen peroxide levels, protein carbonyl, enzymatic antioxidants and glutathione levels. There was a significant and dose-dependent decrease in brood size (1853%), egg laying (5467%), feeding (2958%) and marked decrease in lifespan (20%) at 15 mM of cypermethrin. Increase in levels of oxidative markers such as ROS (2156%), intracellular hydrogen peroxide (1762%), protein carbonyl (829%) and alteration in the activity of enzymatic antioxidants as well as depletion of glutathione (1338%) were also observed. Our study offers evidence to show that cypermethrin induces significant oxidative stress in C. elegans and alters several physiological parameters in these worms, which can lead to impaired functioning, and survival of these worms.
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[
Ecotoxicol Environ Saf,
2010]
Heat shock proteins (Hsp) are a family of stress proteins, which are elicited in response to a variety of stressors in organisms. The objective of this study was to explore the potential of cypermethrin, a synthetic pyrethroid insecticide, on induction of small heat shock proteins (Hsp16) and feeding response in transgenic Caenorhabditis elegans PC72 (Hsp16-LacZ). A concentration-dependent inhibition in feeding was evident in worms exposed to cypermethrin (31%, 46% and 56% at 5, 10, 15 mM, respectively) beyond 4h while marked induction of heat shock protein-16 expression was evident after 12h exposure (as evident from quantitative analysis). Maximum expression of Hsp16 was observed throughout the body of the worms 24h after exposure similar to that evident in the worms exposed to heat shock at 30 degrees C. These data suggest that cypermethrin possesses the potential to induce Hsp16 as well as inhibit feeding in C. elegans at non-lethal concentrations. C. elegans (PC72) thus could serve as a convenient model to study the early toxic effects of xenobiotics.
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[
Physiol Behav,
2015]
Parkinson's disease (PD) is the second most common neurodegenerative disorder characterized by the specific and massive loss of dopamine (DA) containing neurons in the substantia nigra pars compacta (SNpc) and aggregation of protein -synuclein. There are a few animal studies, which indirectly implicate the neuroprotective action of omega-3 polyunsaturated fatty acids in neurodegenerative diseases. In this study, we exposed Caenorhabditis elegans (both wild type N2, and transgenic strain, UA44) to 6-hydroxydopamine (6-OHDA, the model neurotoxicant) and evaluated the extent of protection offered by alpha-linolenic acid (ALA). Larval stage worms (L1/L2) of N2 and transgenic strains were exposed to 6-OHDA (25 mM) with or without ALA (10, 50 and 100 M) for 48 h at 20 C. After 48 h, while the N2 worms were assessed for their responses in terms of locomotion, pharyngeal pumping, lifespan and AChE activity, the transgenic worms were monitored for dopaminergic neuronal degeneration. Worms exposed to 6-OHDA exhibited a significant reduction (48%) in the locomotion rate. Interestingly, supplementation with ALA increased the locomotion rate in 6-OHDA treated worms. A marked decrease (45%) in thrashing was evident in worms exposed to 6-OHDA while thrashing was slightly improved in worms co-exposed to 6-OHDA and higher concentrations of ALA. Interestingly, worms co-exposed to 6-OHDA with ALA (100 M) exhibited a significant increase in thrashing (66 +/- 1.80 thrashes/30s). The pharyngeal pumping rate declined significantly in the case of worms exposed to 6-OHDA (35%). However, the worms co-treated with ALA exhibited significant recovery in pharyngeal pumping. The mean survival for the control worms was 26 days, while the worms exposed to 6-OHDA, showed a marked reduction in survival (21 days). Worms co-exposed to 6-OHDA and ALA showed a concentration-dependent increase in lifespan compared to those exposed to 6-OHDA alone (23, 25 and 26 days respectively). Transgenic worms treated with 6-OHDA showed significant loss of processes of CEP and ADE neurons as evident from visibly marked reduction in GFP expression. Worms co-exposed to 6-OHDA and ALA showed visibly significant reduction in neuronal degeneration in both CEP and ADE. However, worms exposed to 6-OHDA together with ALA showed increased GFP expression within processes of CEP and ADE neurons. Overall, our results demonstrate that ALA significantly suppresses the dopaminergic neurodegeneration and movement disorder induced by 6-OHDA in C. elegans.
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[
Indian J Biochem Biophys,
2011]
Oxidative stress and other effects induced by cypermethrin (CYP, 15 mM) and their amelioration by alpha-tocopherol (400 microM) was studied in the nematode Caenorhabditis elegans. The worms exposed for 4 h to CYP showed increased levels of reactive oxygen species (46%), H2O2 (37%) and protein carbonyls (29%), accompanied by decreased lifespan and brood size. However, exposure to both CYP and alpha-tocopherol resulted in diminution of above alterations with the worms exhibiting relatively lower levels of ROS (30%), H2O2 (15%), protein carbonyls (14%), altered antioxidant enzyme activities and normal lifespan and brood size. The results suggest that CYP induces oxidative stress in C. elegans and the strategy of intervention with alpha-tocopherol could be exploited to offset this induced oxidative stress.
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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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Baru V, Newby G, Lou Y, Dettmer U, Lindquist S, Imberdis T, Walther TC, Soldner F, Termine D, Ho GPH, Kim TE, Fanning S, Terry-Kantor E, Farese RV, Srinivasan S, Landgraf D, Barrasa MI, Pincus D, Kohlwein SD, Welte MA, Haque A, Nuber S, Hofbauer HF, Jaenisch R, Clish CB, Sandoe J, Ramalingam N, Noble T, Freyzon Y, Selkoe D, Becuwe M
[
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.
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Exner N, Nuscher B, Beyer K, Eimer S, Kamp F, Giese A, Bartels T, Hegermann J, Haass C, Lutz AK, Brunner B, Winklhofer KF, Wender N
[
EMBO J,
2010]
Aggregation of -synuclein (S) is involved in the pathogenesis of Parkinson's disease (PD) and a variety of related neurodegenerative disorders. The physiological function of S is largely unknown. We demonstrate with in vitro vesicle fusion experiments that S has an inhibitory function on membrane fusion. Upon increased expression in cultured cells and in Caenorhabditis elegans, S binds to mitochondria and leads to mitochondrial fragmentation. In C. elegans age-dependent fragmentation of mitochondria is enhanced and shifted to an earlier time point upon expression of exogenous S. In contrast, siRNA-mediated downregulation of S results in elongated mitochondria in cell culture. S can act independently of mitochondrial fusion and fission proteins in shifting the dynamic morphologic equilibrium of mitochondria towards reduced fusion. Upon cellular fusion, S prevents fusion of differently labelled mitochondrial populations. Thus, S inhibits fusion due to its unique membrane interaction. Finally, mitochondrial fragmentation induced by expression of S is rescued by coexpression of PINK1, parkin or DJ-1 but not the PD-associated mutations PINK1 G309D and parkin 1-79 or by DJ-1 C106A.
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[
MicroPubl Biol,
2021]
For El Mouridi, S; AlHarbi, S; Frkjr-Jensen, C (2021). A histamine-gated channel is an efficient negative selection marker for C. elegans transgenesis. microPublication Biology. 10.17912/micropub.biology.000349.