[Show abstract][Hide abstract] ABSTRACT: Earthworms express, as most animals, metallothioneins (MTs)-small, cysteine-rich proteins that bind d(10) metal ions (Zn(II), Cd(II), or Cu(I)) in clusters. Three MT homologues are known for Lumbricus rubellus, the common red earthworm, one of which, wMT-2, is strongly induced by exposure of worms to cadmium. This study concerns composition, metal binding affinity and metal-dependent protein folding of wMT-2 expressed recombinantly and purified in the presence of Cd(II) and Zn(II). Crucially, whilst a single Cd₇wMT-2 species was isolated from wMT-2-expressing E. coli cultures supplemented with Cd(II), expressions in the presence of Zn(II) yielded mixtures. The average affinities of wMT-2 determined for either Cd(II) or Zn(II) are both within normal ranges for MTs; hence, differential behaviour cannot be explained on the basis of overall affinity. Therefore, the protein folding properties of Cd- and Zn-wMT-2 were compared by ¹H NMR spectroscopy. This comparison revealed that the protein fold is better defined in the presence of cadmium than in the presence of zinc. These differences in folding and dynamics may be at the root of the differential behaviour of the cadmium- and zinc-bound protein in vitro, and may ultimately also help in distinguishing zinc and cadmium in the earthworm in vivo.
Preview · Article · Jan 2016 · International Journal of Molecular Sciences
[Show abstract][Hide abstract] ABSTRACT: Ageing, a progressive structural and functional decline, is considered to be a major risk factor for virtually all ageing-associated pathologies and disabilities, including Alzheimer’s disease, Parkinson’s disease, stroke, diabetes, atherosclerosis and certain cancers. Biogerontology research has now been largely directed towards finding novel drug targets to decelerate the ageing process and attain healthy ageing in order to delay the onset of all ageing-related diseases. H2S has been reported to exert vasodilatory, antioxidant, anti-apoptotic and anti-inflammatory actions and has been shown to act as a signalling molecule, neuromodulator and cytoprotectant. Intriguingly, H2S has been reported to regulate cell cycle and survival in healthy cells which suggests that it may regulate cell fate and hence the ageing process. This chapter sets out to provide an overview of the current knowledge regarding the involvement of H2S in ageing, with a specific focus on the invertebrate model nematode C. elegans.
No preview · Article · Jul 2015 · Handbook of experimental pharmacology
[Show abstract][Hide abstract] ABSTRACT: Elevated levels of adsorbable organic bromine compounds (AOBr) have been detected in German lakes, and cyanobacteria like Microcystis, which are known for the synthesis of microcystins, are one of the main producers of natural organobromines. However, very little is known about how environmental realistic concentrations of organobromines impact invertebrates. Here, the nematode Caenorhabditis elegans was exposed to AOBr-containing surface water samples and to a Microcystis aeruginosa-enriched batch culture (MC-BA) and compared to single organobromines and microcystin-LR exposures. Stimulatory effects were observed in certain life trait variables, which were particularly pronounced in nematodes exposed to MC-BA. A whole genome DNA-microarray revealed that MC-BA led to the differential expression of more than 2000 genes, many of which are known to be involved in metabolic, neurologic, and morphologic processes. Moreover, the upregulation of cyp- and the downregulation of abu-genes suggested the presence of chronic stress. However, the nematodes were not marked by negative phenotypic responses. The observed difference in MC-BA and microcystin-LR (which impacted lifespan, growth, and reproduction) exposed nematodes was hypothesized to be likely due to other compounds within the batch culture. Most likely, the exposure to low concentrations of organobromines appears to buffer the effects of toxic substances, like microcystin-LR.
Full-text · Article · May 2015 · Environmental Science and Pollution Research
[Show abstract][Hide abstract] ABSTRACT: Cyanobacterial blooms in aquatic environments are frequently characterized by elevated levels of microcystins, a potent hepatotoxin. Here we exposed the nematode Caenorhabditis elegans with environmentally realistic concentrations of MC-LR to explore its non-hepatic toxicity. Lifespan, reproduction and growth assays confirmed the toxic potential of 100 μg/L MC-LR even in this liver-lacking invertebrate. Whole-genome microarray analysis revealed that a neuromodulating action was the dominant response in nematodes challenged with 100 μg/L MC-LR. Indeed, most of the 201 differentially expressed genes were associated with neurobehavior, neurogenesis, and signaling associated pathways. In addition, a whole-genome miRNA-microarray highlighted that, in particular, members of the let-7 family were differentially regulated. These miRNAs are involved in the developmental timing of cell fates, including neurons, and are probably also part of the stress response system. To conclude, neurological modulation is the main transcriptional stress response in C. elegans exposed to MC-LR.
[Show abstract][Hide abstract] ABSTRACT: The risk posed by complex chemical mixtures in the environment to wildlife and humans is increasingly debated, but has been
rarely tested under environmentally relevant scenarios. To address this issue, two mixtures of 14 or 19 substances of concern
(pesticides, pharmaceuticals, heavy metals, polyaromatic hydrocarbons, a surfactant, and a plasticizer), each present at its
safety limit concentration imposed by the European legislation, were prepared and tested for their toxic effects. The effects
of the mixtures were assessed in 35 bioassays, based on 11 organisms representing different trophic levels. A consortium of
16 laboratories was involved in performing the bioassays. The mixtures elicited quantifiable toxic effects on some of the
test systems employed, including i) changes in marine microbial composition, ii) microalgae toxicity, iii) immobilization
in the crustacean Daphnia magna, iv) fish embryo toxicity, v) impaired frog embryo development, and vi) increased expression on oxidative stress-linked reporter
genes. Estrogenic activity close to regulatory safety limit concentrations was uncovered by receptor-binding assays. The results
highlight the need of precautionary actions on the assessment of chemical mixtures even in cases where individual toxicants
are present at seemingly harmless concentrations.
Full-text · Article · Jun 2014 · Toxicological Sciences
[Show abstract][Hide abstract] ABSTRACT: Organobromines of natural and artificial origin are omnipresent in aquatic and terrestrial environments. Although it is well established that exposure to high concentrations of organobromines are harmful to vertebrates, few studies have investigated the effect of environmentally realistic concentrations on invertebrates. Here, the nematode Caenorhabditis elegans was challenged with two organobromines, namely dibromoacetic acid (DBAA) and tetrabromobisphenol-A (TBBP), and monitored for changes in different life trait variables and global gene expression patterns. Fifty micromolar DBAA stimulated the growth and lifespan of the nematodes; however, the onset of reproduction was delayed. In contrast, TBBP changed the lifespan in a hormetic fashion, namely it was stimulated at 0.1 μM but impaired at 50 μM. The reproductive performance was even impaired at 2 μM TBBP. Moreover, DBAA could not reduce the toxic effect of TBBP when applied as a mixture. A whole-genome DNA microarray revealed that both organobromines curtailed signalling and neurological processes. Furthermore on the transcription level, 50 μM TBBP induced proteolysis and DBAA up-regulated biosynthesis and metabolism. To conclude, even naturally occurring concentrations of organobromines can influence the biomolecular responses and life cycle traits in C. elegans. The life extension is accompanied by negative changes in the reproductive behaviour, which is crucial for the stability of populations. Thus, this paper highlights that the effects of exposure to moderate, environmentally realistic concentrations of organobromines should not be ignored.
No preview · Article · May 2014 · Environmental Science and Pollution Research
[Show abstract][Hide abstract] ABSTRACT: Stem cell research is a major focus of regenerative medicine, which amalgamates diverse disciplines ranging from developmental cell biology to chemical and genetic therapy. Although embryonic stem cells have provided the foundation of stem cell therapy, they offer an in vitro study system that might not provide the best insight into mechanisms and behaviour of cells within living organisms. Caenorhabditis elegans is a well defined model organism with highly conserved cell development and signalling processes that specify cell fate. Its genetic amenability coupled with its chemical screening applicability make the nematode well suited as an in vivo system in which regenerative therapy and stem cell processes can be explored. Here, we describe some of the major advances in stem cell research from the worm's perspective.
No preview · Article · Feb 2014 · Drug discovery today
[Show abstract][Hide abstract] ABSTRACT: Exogenous hydrogen sulfide (H2S) administration and endogenous H2S metabolism were explored in the nematode C. elegans. Chronic treatment with a slow-releasing H2S donor, GYY4137, extended median survival by 17-23% and increased tolerance towards oxidative and endoplasmic reticulum (ER) stress. Also, cysl-2, a sulfhydrylase/cysteine synthase in C. elegans, was transcriptionally upregulated by GYY4137 treatment and the deletion of cysl-2 resulted in a significant reduction in lifespan which was partially recovered by the supplementation of GYY4137. Likewise, a mammalian cell culture system, GYY4137 was able to protect bovine aortic endothelial cells (BAECs) from oxidative stress and (H2O2)-induced cell death. Taken together, this provides further support that H2S exerts a protective function which is consistent with the longevity dividend theory. Overall, this study underlines the therapeutic potential of a slow-releasing H2S donor as regulators of the aging and cellular stress pathways.
[Show abstract][Hide abstract] ABSTRACT: The animal model Caenorhabditis elegans was employed to study polyphenol- and humic substances-induced hormetic changes in lifespan. A detailed insight into the underlying mechanism of hormesis was uncovered by applying whole genome DNA microarray experimentation over a range of quercetin (Q), tannic acid (TA), and humic substances (HuminFeed(®), HF) concentrations. The transcriptional response to all exposures followed a non-linear mode which highlighted differential signaling and metabolic pathways. While low Q concentrations regulated processes improving the health of the nematodes, higher concentrations extended lifespan and modulated substantially the global transcriptional response. Over-represented transcripts were notably part of the biotransformation process: enhanced catabolism of toxic intermediates possibly contributes to the lifespan extension. The regulation of transcription, Dauer entry, and nucleosome suggests the presence of distinct exposure dependent differences in transcription and signaling pathways. TA- and HF-mediated transcript expression patterns were overall similar to each other, but changed across the concentration range indicating that their transcriptional dynamics are complex and cannot be attributed to a simple adaptive response. In contrast, Q-mediated hormesis was well aligned to fit the definition of an adaptive response. Simple molecules are more likely to induce an adaptive response than more complex molecules.
[Show abstract][Hide abstract] ABSTRACT: Although the extraction of an impacted third molar (3M) is a routine procedure, postoperative morbidities typically include swelling, pain, and trismus. The aim of the present study was to investigate whether the application of kinesiologic tape can improve the postoperative morbidities associated with 3M surgery, thereby improving the postoperative well-being of patients.
Forty patients assigned for prospective 3M removal were randomized into two treatment groups (with/without kinesiologic tape). Facial swelling was quantified using a five-line measurement at six specific time points. Pain scores were assessed using a visual analog scale, and mouth opening range was assessed by means of standard calipers. In addition, all patients were asked to evaluate overall satisfaction and swelling (both groups) and the effect of the tape on movement and comfort (taped group only).
The postoperational application of kinesiologic tape reduced significantly all investigated parameters: swelling, pain, and trismus. Furthermore, patients with kinesiologic tape reported a significantly lower morbidity rate.
The application of kinesiologic tape following a 3M surgery is a simple and economical, yet medically relevant approach.
Kinesiologic tape offers patients a less traumatic postoperational experience and therefore holds promise to enhance the quality of life of a large cohort of the population.
No preview · Article · Aug 2013 · Clinical Oral Investigations
[Show abstract][Hide abstract] ABSTRACT: Hormetic lifespan extension is, for obvious reasons, beneficial to an individual. But is this effect really cost-neutral? To answer this question, four tannic polyphenols were tested on the nematode Caenorhabditis elegans. All were able to extend the lifespan, but only some in a hormetic fashion. Additional life trait variables including stress resistance, reproductive behavior, growth, and physical fitness were observed during the exposure to the most life extending concentrations. These traits represent the quality of life and the population fitness, being the most important parameters of a hormetic treatment besides lifespan. Indeed, it emerged that each life-extension is accompanied by a constraining effect in at least one other endpoint, for example growth, mobility, stress resistance, or reproduction. Thus, in this context, longevity could not be considered to be attained for free and therefore it is likely that other hormetic benefits may also incur cost-intensive and unpredictable side-effects.
[Show abstract][Hide abstract] ABSTRACT: Obesity is an ever increasing health concern of global importance. The treatment options for this condition are limited and until recently there was only one FDA approved anti-obesity drug available. The approval of two anti-obesity drugs which have both undergone post-marketing withdrawal undermines consumer confidence and highlights the need for more robust pre-clinical toxicity testing. The nematode Caenorhabditis elegans is an established toxicological model and while it is still in its infancy with regards to the study of obesity, the ease of maintenance and high-throughput assays makes C. elegans an appealing choice. Here, we explore the suitability of C. elegans as an in vivo toxicity model for the mechanistic screening of two anti-obesity drugs. Toxicity profiles identified that a Sibutramine containing drug induced pronounced effects on pharyngeal pumping, defecation, locomotion and reproduction, in concert indicative of a possible neuronal mode of action. Resultant from a drug resistance screen we demonstrate that Sibutramine has non-serotonergic targets, a notion that suggests that serotonin-specific reuptake inhibitors (SSRIs) are less specific than first assumed. These results stress that the interplay between serotonin, dopamine and norepinephrine is not easily dissected. Overall, the data highlight the value of C. elegans as an in vivo toxicity tool in anti-obesity drug research.
[Show abstract][Hide abstract] ABSTRACT: Evidence is emerging that earthworms can evolve tolerance to trace element enriched soils. However, few studies have sought to establish whether such tolerance is determined through adaption or plasticity. Here we report results from a combined analysis of mitochondrial (cytochrome oxidase II, COII), nuclear (amplified fragment length polymorphism, AFLP) variation and DNA methylation in populations of the earthworm Lumbricus rubellus from sites across an abandoned arsenic and copper mine. Earthworms from the mine site population demonstrated clear arsenic tolerance in comparison to a naïve strain. COII and AFLP results suggest that L. rubellus from the unexposed and the adapted populations comprises two cryptic lineages (Linages A and B) each of which was present across all of the sites. AFLP analysis by lineage highlighted variations associated with soil metal/metalloid concentrations (most clearly for Lineage A) suggesting a genetic component to the observed tolerance. The methylation sensitive AFLP (Me-AFLP) identified a high genome methylation content (average 13.5%) in both lineages. For Lineage A, Me-AFLP analysis did not identify a strong association with soil arsenic levels. For Lineage B, however, a clear association of methylation patterns with soil arsenic concentrations was found. This suggests that Lineage B earthworms utilise epigenetic mechanisms to adapt to the presence of contamination. These fundamentally different genetic adjustments in the two clades indicate that the two lineages employ distinct adaptive strategies (genetic or epigenetic) in response to arsenic exposure. Mechanisms driving this variation may be founded within the colonisation histories of the lineages.
Full-text · Article · Feb 2013 · Soil Biology and Biochemistry
[Show abstract][Hide abstract] ABSTRACT: The synthesis of designer solid-state materials by living organisms is an emerging field in bio-nanotechnology. Key examples include the use of engineered viruses as templates for cobalt oxide (Co(3)O(4)) particles, superparamagnetic cobalt-platinum alloy nanowires and gold-cobalt oxide nanowires for photovoltaic and battery-related applications. Here, we show that the earthworm's metal detoxification pathway can be exploited to produce luminescent, water-soluble semiconductor cadmium telluride (CdTe) quantum dots that emit in the green region of the visible spectrum when excited in the ultraviolet region. Standard wild-type Lumbricus rubellus earthworms were exposed to soil spiked with CdCl(2) and Na(2)TeO(3) salts for 11 days. Luminescent quantum dots were isolated from chloragogenous tissues surrounding the gut of the worm, and were successfully used in live-cell imaging. The addition of polyethylene glycol on the surface of the quantum dots allowed for non-targeted, fluid-phase uptake by macrophage cells.
Full-text · Article · Dec 2012 · Nature Nanotechnology
[Show abstract][Hide abstract] ABSTRACT: Bisphosphonate related osteonecrosis of the jaw (BRONJ) is rare but potentially severe, and the etiopathology and risk factors are poorly defined. To date, it has not been possible to induce BRONJ in a large animal model, a shortfall this study aims to redress. Ten two-year-old adult Göttingen minipigs were split into two groups. Five pigs (group 1) were administered intravenously a weekly dose of a bisphosphonate (zoledonate 0.05mg/kg body weight, approximating the oncologic dose in humans) and five pigs (group 2) served as controls. After 6 weeks, tooth extractions were performed in the upper and lower jaw (both groups) and the bisphosphonate administration continued for a further 10 weeks (group 1 only). Clinical and blood parameters were monitored throughout the entire experiment; thereafter, the jaw-bones were subjected to macroscopic, radiological (CT) and histological investigations. Whilst the extraction sites in the control group healed within two weeks, all animals in the bisphosphonate group exhibited exposed bone and impaired wound healing, indicators that are synonymous of macroscopically advanced osteonecrosis. Radiological and in particular histological investigations confirmed the presence of BRONJ in the animals from group 1. This paper demonstrates that the administration of bisphosphonates, in combination with tooth extractions, induces BRONJ in a minipig model. The ability to study BRONJ in miniature pigs, animals with a bone structure not dissimilar to humans, may improve our knowledgebase regarding the etiopathology, the prophylaxis and potentially uncover new therapies of BRONJ.