JOURNAL OF PHYCOLOGY, Issue 5 2010
Cécile Jauzein
Alexandrium catenella (Whedon et Kof.) Balech has exhibited seasonal recurrent blooms in the Thau lagoon (South of France) since first reported in 1995. Its appearance followed a strong decrease (90%) in phosphate (PO43,) concentrations in this environment over the 1970,1995 period. To determine if this dinoflagellate species has a competitive advantage in PO43, -limited conditions in terms of nutrient acquisition, semicontinuous cultures were carried out to characterize phosphorus (P) uptake by A. catenella cells along a P-limitation gradient using different dilution rates (DRs). Use of both inorganic and organic P was investigated from measurements of 33PO43, uptake and alkaline phosphatase activity (APA), respectively. P status was estimated from cellular P and carbon contents (QP and QC). Shifts in trends of QP/QC and QP per cell (QP·cell,1) along the DR gradient allowed the definition of successive P-stress thresholds for A. catenella cells. The maximal uptake rate of 33PO43, increased strongly with the decrease in DR and the decrease in QP/QC, displaying physiological acclimations to PO43, limitation. Concerning maximal APA per cell, the observation of an all-or-nothing pattern along the dilution gradient suggests that synthesis of AP was induced and maximized at the cellular scale as soon as PO43, limitation set in. APA variations revealed that the synthesis of AP was repressed over a PO43, threshold between 0.4 and 1 ,M. As lower PO43, concentrations are regularly observed during A. catenella blooms in Thau lagoon, a significant portion of P uptake by A. catenella cells in the field may come from organic compounds. [source]

Road Salt Turns Streams Toxic

CONSERVATION, Issue 1 2006
Article first published online: 8 MAR 200
No abstract is available for this article. [source]

Cytochrome c oxidase isoform IV-2 is involved in 3-nitropropionic acid-induced toxicity in striatal astrocytes

GLIA, Issue 14 2009
Shilpee Singh
Abstract Astrocyte mitochondria play an important role for energy supply and neuronal survival in the brain. Toxic and degenerative processes are largely associated with mitochondrial dysfunction. We, therefore, investigated the effect of 3-nitropropionic acid (NPA), a mitochondrial toxin and in vitro model of Huntington's disease (HD), on mitochondrial function and viability of primary striatal astrocytes. Although NPA is known as an irreversible inhibitor of succinate dehydrogenase, we observed an increase of astrocyte ATP levels after NPA treatment. This effect could be explained by NPA-mediated alterations of cytochrome c oxidase subunit IV isoform (COX IV) expression. The up-regulation of COX isoform IV-2 caused an increased enzyme activity at the expense of elevated mitochondrial peroxide production causing increased cell death. The application of a small interfering RNA against COX IV-2 revealed the causal implication of COX isoform IV-2 in NPA-mediated elevation of oxidative stress and necrotic cell death. Thus, we propose a novel, additional mechanism of NPA-induced cell stress and death which is based on structural and functional changes of astrocyte COX and which could indirectly impair neuronal survival. © 2009 Wiley-Liss, Inc. [source]

Toxic and repellent effects of Baccharis salicifolia essential oil on Tribolium castaneum

PEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 6 2005
Matías García
Abstract Allelochemical effects were observed when Tribolium castaneum (Herbst) adults were treated with Baccharis salicifolia (Ruiz & Pavon) Pers essential oil. The main biological activities were toxicity and repellence. Terpenes present in the essential oil were identified by GC-MS, and some authentic samples were tested to assess their activity individually. The most acutely toxic compounds after 3 days were ,-pinene and pulegone. Most of the monoterpenes elicited symptoms indicative of neurotoxicity. The most repellent compound was ,-terpineol. Toxic and repellent effects of chemical derivatives of the major sesquiterpene present in B salicifolia essential oil, as well as a series of monoterpenes, were evaluated in order to investigate structure-activity relationships. The reduced derivatives of the monoterpenes and sesquiterpenes were more repellent that their carbonyl analogues. In addition, unsaturation in the germacrane skeleton enhanced repellent activity. Copyright © 2005 Society of Chemical Industry [source]

An Experiment in (Toxic) Indian Capitalism?: The Skull Valley Goshutes, New Capitalism, and Nuclear Waste

POLAR: POLITICAL AND LEGAL ANTHROPOLOGY REVIEW, Issue 2 2001
Randel D. Hanson
First page of article [source]

High Schools Can Be "Toxic"

AMERICAN JOURNAL OF ORTHOPSYCHIATRY, Issue 3 2002
Alice Sterling Honig PhD
Book reviewed in this article: And Words Can Hurt Forever. How to Protect Adolescents From Bullying, Harassment, and Emotional Violence, by J. Garbarino and E. DeLara. [source]

Investigation of Direct Toxic and Teratogenic Effects of Anticoagulants on Rat Embryonic Development Using In Vitro Culture Method and Genotoxicity Assay

ANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 2 2006
I. I. Uysal
Summary Heparin and low molecular weight heparins (LMWHs) are used to reduce the incidence of venous thromboembolism in pregnancy. Although, these agents have been shown to be safe when used during pregnancy, the studies about direct toxic and teratogenic effects of these drugs on embryonic development are limited. In this study, the effects of heparin and LMWHs on rat embryonic development were investigated by using in vitro embryo culture and micronucleus (MN) assay methods. Rat embryos were cultured in vitro in the presence of different concentrations of heparin (5,40 IU/ml), dalteparin (2.5,20 IU/ml), enoxaparin (25,100 ,g/ml) and nadroparin (1,4 IU/ml). Effects of anticoagulants on embryonic developmental parameters were compared and embryos were evaluated for the presence of any malformations. After culturing the embryos, classic MN assay was performed. Anticoagulants significantly decreased all growth and developmental parameters dose-dependently. Dalteparin and enoxaparin were found to cause more developmental toxicity than heparin and nadroparin. Along with haematoma in general, heparin and nadroparin caused maxillary deformity, situs inversus and oedema most frequently, while neural tube defects were observed with dalteparin and enoxaparin. All agents also significantly induced MN formation in rat embryonic blood cells. These results indicate the possible genotoxic effects of anticoagulant agents on the developing rat embryo when applied directly. [source]

How to determine free Gd and free ligand in solution of Gd chelates.

CONTRAST MEDIA & MOLECULAR IMAGING, Issue 5 2006
A technical note
Abstract Gd(III) chelates are often used as reporting probes in magnetic resonance imaging applications. Their use relies on the assumption that their high stability ensures against the release of free ligand and free Gd3+ ions, which are both highly toxic to living systems. The presence of free Gd3+ ions may have a profound effect on the contrast in the MR image as they may form highly hydrated, macromolecular complexes endowed with very high relaxivity thus providing erroneous information on the extent of the contrast effect induced by the given reporting probe. Although the stability of a given complex may be high enough, the complexation step could not have been completed. Therefore any Gd complex preparation has to be carefully checked for the content of free ligand and free metal ions. Herein the currently used procedures that allow an assessment of the amounts of free metal ions and free ligand in a solution of a given Gd complex are described in detail. Copyright © 2006 John Wiley & Sons Ltd. [source]

Adaptation of GAL4 activators for GAL4 enhancer trapping in zebrafish

DEVELOPMENTAL DYNAMICS, Issue 3 2009
Eri Ogura
Abstract An enhancer trap-based GAL4-UAS system in zebrafish requires strong GAL4 activators with minimal adverse effects. However, the activity of yeast GAL4 is too low in zebrafish, while a fusion protein of the GAL4 DNA-binding domain and the VP16 activation domain is toxic to embryonic development, even when expressed at low levels. To alleviate this toxicity, we developed variant GAL4 activators by fusing either multimeric forms of the VP16 minimal activation domain or the NF-,B activation domain to the GAL4 DNA-binding domain. These variant GAL4 activators are sufficiently innocuous and yet highly effective transactivators in developing zebrafish. Enhancer-trap vectors containing these GAL4 activators downstream of an appropriate weak promoter were randomly inserted into the zebrafish genome using the Sleeping Beauty transposon system. By the combination of these genetic elements, we have successfully developed enhancer trap lines that activate UAS-dependent reporter genes in a tissue-specific fashion that reflects trapped enhancer activities. Developmental Dynamics 238:641,655, 2009. © 2009 Wiley-Liss, Inc. [source]

Development of learned flavor preferences

DEVELOPMENTAL PSYCHOBIOLOGY, Issue 5 2006
Kevin P. Myers
Abstract Rats, like humans, are born with only a few innate flavor preferences and aversions. Preferences retain great plasticity throughout the lifespan because they are sensitive to modification by experience. From an early age, rats can rapidly learn to prefer or avoid a flavor (conditioned stimulus, CS) that is associated with a positive or negative unconditioned stimulus (US). The US may be the mother's milk, social or thermotactile stimulation, or other food-related stimuli. Flavor-flavor learning occurs when the CS flavor is mixed with a naturally preferred (e.g., sweet) or avoided (e.g., bitter) US flavor. Flavor preferences and aversions are also produced by USs that have postoral positive (e.g., nutritious) or negative (e.g., toxic) actions. These types of learning appear to involve different behavioral and neural mechanisms as indicated by differences in conditioned responses, effective temporal parameters, resistance to extinction, and neurochemical mechanisms. New evidence indicates that flavor-nutrient preference learning can occur before weaning and influence food selection after weaning. Flavor conditioning not only affects food choice, but can also significantly increase food acceptance, that is, total consumption. Thus, from an early age, learning processes shape the feeding behavior of animals. While primarily serving an adaptive function, learning may play a role in biasing individuals towards excessive intake and weight gain. © 2006 Wiley Periodicals, Inc. Dev Psychobiol 48: 380,388, 2006. [source]

Zinc, a regulator of islet function and glucose homeostasis

DIABETES OBESITY & METABOLISM, Issue 2009
N. Wijesekara
It is well known that zinc is required in pancreatic ,-cells in the process of insulin biosynthesis and the maturation of insulin secretory granules. In fact, the zinc level in pancreatic islets is amongst the highest in the body and reduction in its levels in the pancreas has been associated with diabetes. High concentrations of zinc can also be toxic because of enhanced oxidative damage. The link between zinc, diabetes and islet dysfunction has recently been reiterated by genomewide association studies that identified an islet cell membrane zinc transporter, SLC30A8 (ZnT8), as one of the risk loci for type 2 diabetes. Here we explore the importance of both zinc and ZnT8 to islet biology and whole body glucose homeostasis. [source]

Insulin mimetic effects of macrocyclic binuclear oxovanadium complexes on streptozotocin-induced experimental diabetes in rats

DIABETES OBESITY & METABOLISM, Issue 6 2003
B. Ramachandran
Aim:, The vanadium complexes so far tested for their insulin mimetic effects are either mono- or binuclear and contain only acyclic ligands. The leaching or hydrolysis of vanadyl ions from these complexes is much easier, and hence they elicit side effects. In the present study, a new binuclear macrocyclic oxovanadium complex was synthesized, and its efficacy was studied on streptozotocin (STZ)-induced diabetic rats over a period of 30 days. Methods:, The insulin mimetic effect of the complex was tested on the blood sugar level in the STZ-diabetic rats and on the activities of the carbohydrate-metabolizing enzymes present in the liver. Results:, Administration of vanadium complex to STZ-induced diabetic rats decreased blood glucose levels from hyperglycaemic to normoglycaemic when compared to diabetic rats. The activity of carbohydrate-metabolizing enzymes such as hexokinase, glucose-6-phosphate dehydrogenase, glycogen synthase and glycogen content were increased to near normal in vanadium complex-administered diabetic rats. The biochemical studies such as assay of blood urea and glutamate oxaloacetate transaminases revealed that the complex is not toxic to the system. Conclusion:, The nontoxic nature of this complex may be due to the presence of the vanadyl ions in an intact macrocyclic form. Further, the vanadyl ions present in the macrocyclic binuclear oxovanadium complex are very close to each other, and this may enhance the insulin mimetic activity by synergic effect. [source]

Diversity of native and alien plant species on rubbish dumps: effects of dump age, environmental factors and toxicity

DIVERSITY AND DISTRIBUTIONS, Issue 3 2003
Antonín Py
Abstract. The flora of 96 rubbish dumps consisting of organic, inorganic and industrial wastes was studied in the Czech Republic. Some dumps contained toxic substances (heavy metals, chlorethylenes, phenols, polychlorinated biphenyls, oil hydrocarbons and biogas). Statistically significant factors explaining the number and proportional representation of native plant species, archaeophytes (introduced before 1500) and neophytes (introduced later) were determined. In total, 588 species of vascular plants were recorded, with archaeophytes (133 species) over-represented and native species (322 species) and neophytes (133 species) under-represented compared to their proportions in the national flora. Minimum adequate models were used to determine the effects of several factors on species numbers and proportions, independent of other factors. Dump area, human density in the region and altitude (non-significant only in archaeophytes) were correlated positively with species numbers. Dump age, expressed as time since dump establishment, interacted with the dump toxicity; species numbers increased with dump age on non-toxic dumps, whereas on toxic dumps no increase in numbers was noted. For neophytes, dump toxicity also interacted with human density; the increase in numbers of neophytes with human density is more pronounced on toxic than on non-toxic dumps. The variables measured failed to explain observed differences in proportional representation of native species, archaeophytes and neophytes. This suggests that the occurrence of species growing in such extreme habitats is driven overwhelmingly by factors such as anthropogenic disturbance. A possible explanation for the positive effect of altitude on species numbers on dumps is that the effect of heating of the deposited substrate by microbiological processes, documented by previous studies, overrides the effect of altitude which was shown repeatedly to have a negative effect on species richness. Neophyte distribution is driven by an interplay of factors distinct from those influencing the distribution of native species, namely toxicity and human density (the latter we interpret as a surrogate for propagule pressure). Their distribution on studied dumps is more restricted than that of native taxa and archaeophytes, and they are more limited by toxic substrata; more intensive propagule pressure is required for their establishment at dumps with higher toxicity levels. [source]

Progress in the development of new treatments for combined Alzheimer's and Parkinson's diseases

DRUG DEVELOPMENT RESEARCH, Issue 3 2002
Eliezer Masliah
Abstract Misfolding of synaptic molecules such as amyloid , peptide and ,-synuclein has been proposed to play a key role in the mechanisms of neurodegeneration in Alzheimer's and Parkinson's disease, respectively. Notably, the majority of patients with Alzheimer's disease also have ,-synuclein-immunoreactive Lewy bodies, and a substantial proportion of them develop a form of parkinsonism also known as Lewy body disease, that defies conventional therapies. Thus, factors involved in the pathogenesis of Alzheimer's disease might promote the development of particularly recalcitrant forms of Lewy body disease. We have shown that the amyloid , peptide 1-42, of Alzheimer's disease, promotes the toxic conversion of ,-synuclein and accelerates ,-synuclein-dependent deficits in transgenic mice. Understanding the mechanisms promoting the toxic conversion of ,-synuclein is of critical importance for the design of rationale treatments for Lewy body disease and transgenic models hold the promise for the development of such novel therapies. In this context therapies aimed at: (1) reducing amyloid , peptide 1-42 production, (2) blocking toxic ,-synuclein oligomerization (e.g., ,-synuclein, antioxidants), (3) promoting ,-synuclein protofibril degradation, and (4) protecting neurons (e.g., anti-oxidants, neurotrophic agents) against toxic ,-synuclein aggregates might prove to be significantly useful in the treatment of Lewy body disease. We characterized ,-synuclein, the non-amyloidogenic homologue of ,-synuclein, as an inhibitor of aggregation of ,-synuclein. Our results raise the intriguing possibility that ,-synuclein might be a natural negative regulator of ,-synuclein aggregation, and that a similar class of endogenous factors might modulate the toxic conversion of other molecules involved in neurodegeneration. Such an anti-amyloidogenic property of ,-synuclein in combination with other treatments might also provide a novel strategy for the treatment of neurodegenerative disorders. Drug Dev. Res. 56:282,292, 2002. © 2002 Wiley-Liss, Inc. [source]

Direct and indirect effects of the introduced toad Bufo marinus (Anura: Bufonidae) on populations of native anuran larvae in Australia

ECOGRAPHY, Issue 3 2000
Michael R. Crossland
Introduced species are frequently believed to have adverse effects on native biota and ecosystems. However, much of our knowledge of the ecological impacts of introduced species is anecdotal, and the mechanisms controlling these effects are often poorly understood. I used replicated artificial pond experiments to investigate the impact of eggs and hatchlings of the introduced toad Bufo marinus on populations of native anuran larvae (Limnodynastes ornatus and Litoria rubella) in Australia. Bufo marinus eggs and hatchlings are highly toxic to predatory native tadpoles. Under naturalistic conditions, populations of predatory L. ornatus tadpoles experienced significantly reduced survival when exposed to Bufo eggs and hatchlings. The impact of Bufo on L. ornatus survival was positively correlated with Bufo density. However, the toxic effects of Bufo on L. ornatus indirectly facilitated the survival of later-breeding L. rubella by altering predator-prey interactions between L. ornatus and L. rubella. Limnodynastes ornatus tadpoles are voracious predators of L. rubella eggs and hatchlings. Consequently, the negative impact of Bufo on populations of L. ornatus tadpoles reduced the intensity of predation by L. ornatus tadpoles on L. rubella eggs and hatchlings, thereby increasing L. rubella survival. The results demonstrate that B. marinus plays an important role in structuring native larval anuran communities via direct and indirect mechanisms, and that Bufo may have both negative and positive effects on populations of native anuran larvae. As far as I am aware, these are the first quantitative data to demonstrate that introduced fauna may affect populations of native biota via toxic effects. [source]

Post-ingestive effects of nectar alkaloids depend on dominance status of bumblebees

ECOLOGICAL ENTOMOLOGY, Issue 4 2009
JESSAMYN S. MANSON
Abstract 1.,Secondary metabolites have acute or chronic post-ingestive effects on animals, ranging from death to growth inhibition to reduced nutrient assimilation. 2.,Although characterised as toxic, the nectar of Gelsemium sempervirens is not lethal to pollinators, even when the concentration of the nectar alkaloid gelsemine is very high. However, little is known about the sublethal costs of nectar alkaloids. 3.,Using a microcolony assay and paired worker bumblebees, the present study measured the effects of artificial nectar containing gelsemine on oocyte development. Oocytes are a sensitive indicator of protein utilisation and general metabolic processes. We also calculated carbohydrate concentrations in the haemolymph to examine energetic costs of gelsemine consumption. 4.,High concentrations of gelsemine significantly reduced mean oocyte width in subordinate bees, while dominant bees showed only a trend towards oocyte inhibition. Gelsemine consumption did not reduce carbohydrate concentrations in haemolymph. 5.,The cost of ingesting gelsemine may be due to direct toxicity of alkaloids or may be an expense associated with detoxifying gelsemine. Detoxification of alkaloids can require reallocation of resources away from essential metabolic functions like reproduction. The risks associated with nectar alkaloid consumption are tied to both the social and nutritional status of the bee. [source]

Conserving the Richmond Birdwing Butterfly over two decades: Where to next?

ECOLOGICAL MANAGEMENT & RESTORATION, Issue 1 2008
Don Sands
Summary The Richmond Birdwing Butterfly, restricted to subtropical areas of Australia, is threatened with extinction in the Queensland part of its range because of clearing and fragmenting rainforests containing its larval food vines. Habitat fragmentation and drought have exacerbated risks of inbreeding depression and a range of other threats exist, including invasions of the exotic Dutchmans Pipe Vine which is toxic to Richmond Birdwing larvae. This article outlines the Richmond Birdwing Butterfly project from its beginnings in the Double Helix Club project and recently the Richmond Birdwing Recovery Network. It provides details of the biology of the butterfy and its food vines, as well as discussing elements for consideration in a future recovery plan including (i) protecting the remaining breeding sites; and, for the shorter term (ii) continuing to propagate and plant food plants at appropriate localities that previously supported the butterfly. [source]

Viability study of HL60 cells in contact with commonly used microchip materials

ELECTROPHORESIS, Issue 24 2006
Floor Wolbers
Abstract This paper presents a study in which different commonly used microchip materials (silicon oxide, borosilicate glass, and PDMS) were analyzed for their effect on human promyelocytic leukemic (HL60) cells. Copper-coated silicon was analyzed for its toxicity and therefore served as a positive control. With quantitative PCR, the expression of the proliferation marker Cyclin D1 and the apoptosis marker tissue transglutaminase were measured. Flow cytometry was used to analyze the distribution through the different phases of the cell cycle (propidium iodide, PI) and the apoptotic cascade (Annexin V in combination with PI). All microchip materials, with the exception of Cu, appeared to be suitable for HL60 cells, showing a ratio apoptosis/proliferation (Rap) comparable to materials used in conventional cell culture (polystyrene). These results were confirmed with cell cycle analysis and apoptosis studies. Precoating the microchip material surfaces with serum favor the proliferation, as demonstrated by a lower Rap as compared to uncoated surfaces. The Cu-coated surface appeared to be toxic for HL60 cells, showing over 90% decreased viability within 24,h. From these results, it can be concluded that the chosen protocol is suitable for selection of the cell culture material, and that the most commonly used microchip materials are compatible with HL60 culturing. [source]

Process Development in Biotechnology , A Re-Evaluation

ENGINEERING IN LIFE SCIENCES (ELECTRONIC), Issue 1 2005
K. Schügerl
Abstract This review considers some process development problems in biotechnology and presents examples of solutions, which were developed in cooperation with industrial partners. These processes include the production of restriction endonuclease EcoRI by recombinant Escherichia coli, which is toxic to the cell, penicillin V by Penicillium chrysogenum, xylanase by Aspergillus awamori, cephalosporin C by Acremonium chrysogenum, erythritol by Moniliella tomentosa var pollinis, and alkaline serine protease by Bacillus licheniformis. Special attention is given to the practical aspects of product development. [source]

The sublethal effects of tebufenozide on the precopulatory and copulatory activities of Choristoneura fumiferana and C. rosaceana

ENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 3 2004
Renée Dallaire
Abstract The sublethal effects of tebufenozide, an ecdysone agonist, on the reproductive biology of Choristoneura fumiferana (Clem) and of Choristoneura rosaceana (Harris) (Lepidoptera: Tortricidae), treated during the larval stage, were evaluated using two treatment methods: the force-feeding method and the diet method. The percentage of mortality and the developmental time of survivors increased linearly with the concentration of tebufenozide used. This ecdysone analogue proved to be more toxic to C. fumiferana than to C. rosaceana. In C. rosaceana, the weight of males and females decreased proportionally with the dose ingested, but females were affected to a greater extent. This difference might be due to a greater consumption of the treated diet, or to a differential vulnerability to tebufenozide. Tebufenozide did not modify the pre-copulatory activities associated with chemical communication in the females. However, the consumption of tebufenozide delayed ovarian maturation, causing a reduction in the fecundity of females. Treated males had smaller spermatophores and fewer eupyrene sperms in their bursa copulatrix and spermatheca, along with lower mating success. In C. fumiferana, tebufenozide delayed the females' onset time of calling the first night after emergence, but did not affect the mean time spent calling or the production of the main component of the sex pheromone. The males showed significantly greater difficulty in executing oriented flight in a wind tunnel, although their mating success was not affected. We concluded that tebufenozide interferes with various aspects of the reproductive biology of males and females of C. fumiferana and C. rosaceana, including some pre-copulatory behaviors associated with sex pheromone communication. [source]

In vitro evaluation of the clastogenicity of fumagillin

ENVIRONMENTAL AND MOLECULAR MUTAGENESIS, Issue 8 2008
Jevrosima Stevanovic
Abstract Fumagillin, an antibiotic compound produced by Aspergillus fumigatus, is effective against microsporidia and various Amoeba species, but is also toxic when administered systemically to mammals. Furthermore, a recent in vivo study by Stanimirovic Z et al. 2007: (Mutat Res 628:1,10) indicated genotoxic effects of fumagillin. The aim of the present study was to investigate and explain the clastogenic effects of fumagillin (in the form of fumagillin dicyclohexylamine salt) on human peripheral blood lymphocytes in vitro by sister-chromatid exchanges (SCE), chromosome aberrations (CA), and micronucleus (MN) tests. The mitotic index (MI), proliferation index (PI), and nuclear division index (NDI) were calculated to evaluate the cytotoxic potential of fumagillin. Five concentrations of fumagillin (0.34, 0.68, 1.02, 3.07, and 9.20 ,g/ml) were applied to lymphocyte cultures. All the tested concentrations of fumagillin increased the frequency of SCE per cell significantly (P < 0.001 or P < 0.01) compared with the negative control. A significant (P < 0.001) increase in frequency of structural CA was observed at the three highest concentrations in comparison with the negative control. In addition, the three highest test concentrations increased MN formation and decreased MI, PI, and NDI significantly compared with the negative control. The present results indicate that fumagillin is clastogenic and cytotoxic to cultured human lymphocytes. Environ. Mol. Mutagen., 2008. © 2008 Wiley-Liss, Inc. [source]

Water soluble fraction of solar-simulated light-exposed crude oil generates phosphorylation of histone H2AX in human skin cells under UVA exposure

ENVIRONMENTAL AND MOLECULAR MUTAGENESIS, Issue 6 2007
Yuko Ibuki
Abstract Crude oil contains compounds, which have toxic and cancer-causing properties to humans. The oil spilled in environments is usually exposed to sunlight; however, the toxicity of sunlight-exposed oil is poorly understood. In this study, we found that the water soluble fraction (WSF) of crude oil irradiated with solar-simulated light (SSL) generated phosphorylation of histone H2AX (,-H2AX) in human skin cells under UVA irradiation, which was due to the formation of DNA double strand breaks (DSBs). Crude oil was exposed to SSL for ,7 days. The WSF obtained from unexposed crude oil showed no toxicity, whereas the WSF obtained from crude oil pre-exposed to SSL induced acute cell death on exposure to UVA irradiation (induction of phototoxicity), which was more remarkable in human skin fibroblasts than human skin keratinocytes. ,-H2AX was detected in both cell lines immediately after treatment with the WSF plus UVA. Interestingly, ,-H2AX was detectable even at low SSL- and UVA-doses, which induced no cytotoxicity. The WSF of crude oil irradiated with SSL, generated DSBs under UVA irradiation, which were detected by biased sinusoidal field gel electrophoresis. This was confirmed using xrs-5 cells isolated from CHO-K1 cells, which are deficient in a repair enzyme for DSBs; the WSF plus UVA induced a more dramatic decrease in survival in xrs-5 cells than CHO-K1 cells. These findings demonstrate that exposure of crude oil to sunlight makes the WSF phototoxic, generating DSBs accompanying the appearance of ,-H2AX in human skin cells. Environ. Mol. Mutagen., 2007. © 2007 Wiley-Liss, Inc. [source]

Stable implantation of orthogonal sensor circuits in Gram-negative bacteria for environmental release

ENVIRONMENTAL MICROBIOLOGY, Issue 12 2008
Aitor De Las Heras
Summary A broad host range, orthogonal genetic platform has been developed to format sensor circuits in the chromosome of Gram-negative microorganisms destined for environmental release as bioindicators of toxic or perilous compounds (e.g. explosives) in soil. The genetic scheme includes the generation of a genomic landing pad for the sensor module with a Tn5 -mini-transposon bearing an optimal attTn7 sequence and a choice of reporter systems with optical and enzymatic outputs. The array of functional elements thereby inserted in the chromosome match that of a cognate plasmid vector which delivers the transcription factors and the promoters to a frame that places the regulatory parts in front of the reporters. Site-specific recombination sites allow the deletion of antibiotic resistances and enables reporter output prior to deliberate release. The system thus allows the production and maintenance of cells in a pre-release state and its intentional conversion in deliverable strains that fulfil all safety, stability and performance criteria. The combination of such a genetic platform with a variant of the transcriptional regulator XylR of Pseudomonas putida that responds to 2,4-dinitrotoluene has been the basis for the production of strains that emit light upon exposure to residues of explosives in a soil microcosm. [source]

Pseudomonas fluorescens' view of the periodic table

ENVIRONMENTAL MICROBIOLOGY, Issue 1 2008
Matthew L. Workentine
Summary Growth in a biofilm modulates microbial metal susceptibility, sometimes increasing the ability of microorganisms to withstand toxic metal species by several orders of magnitude. In this study, a high-throughput metal toxicity screen was initiated with the aim of correlating biological toxicity data in planktonic and biofilm cells to the physiochemical properties of metal ions. To this end, Pseudomonas fluorescens ATCC 13525 was grown in the Calgary Biofilm Device (CBD) and biofilms and planktonic cells of this microorganism were exposed to gradient arrays of different metal ions. These arrays included 44 different metals with representative compounds that spanned every group of the periodic table (except for the halogens and noble gases). The minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and minimum biofilm eradication concentration (MBEC) values were obtained after exposing the biofilms to metal ions for 4 h. Using these values, metal ion toxicity was correlated to the following ion-specific physicochemical parameters: standard reduction-oxidation potential, electronegativity, the solubility product of the corresponding metal,sulfide complex, the Pearson softness index, electron density and the covalent index. When the ions were grouped according to outer shell electron structure, we found that heavy metal ions gave the strongest correlations to these parameters and were more toxic on average than the other classes of the ions. Correlations were different for biofilms than for planktonic cells, indicating that chemical mechanisms of metal ion toxicity differ between the two modes of growth. We suggest that biofilms can specifically counter the toxic effects of certain physicochemical parameters, which may contribute to the increased ability of biofilms to withstand metal toxicity. [source]

Effect of thorium on the growth and capsule morphology of Bradyrhizobium

ENVIRONMENTAL MICROBIOLOGY, Issue 10 2003
Mónica Santamaría
Summary The thorium effect on Bradyrhizobium growth was assayed in liquid media. Th4+ inhibited the growth of Bradyrhizobium (Chamaecytisus) BGA-1, but this effect decreased in the presence of suspensions of live or dead bacterial cells. Th4+ induced the formation of a gel-like precipitate when added to a dense suspension of B. (Chamaecytisus) BGA-1 cells. Viable Bradyrhizobium cells remained in suspension after precipitate formation. Thorium was recovered in the precipitate, in which polysaccharide, lipopolysaccharide and proteins were also found. After Th4+ addition, the morphology of B. (Chamaecytisus) BGA-1 or Bradyrhizobium japonicum USDA 110 sedimented cells studied by scanning electron microscopy changed from an entangled network of capsulated bacteria to uncapsulated individual cells and an amorphous precipitate. Energy-dispersive X-ray spectroscopy showed that thorium was mainly in the amorphous fraction. Precipitate was also formed between B. (Chamaecytisus) BGA-1 and Al3+, which was also toxic to this bacterium. Precipitate induced by Th4+ or Al3+ was found in all Bradyrhizobium and Sinorhizobium strains tested, but not in Rhizobium, Salmonella typhimurium, Aerobacter aerogenes or Escherichia coli. These results suggest a specific defence mechanism based on metal precipitation by extracellular polymers. [source]

Catastrophic incident prevention and proactive risk management in the new biofuels industry,

ENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 1 2009
Judy A. Perry
Abstract This article is directed at assisting bioethanol manufacturers with preventing catastrophic incidents which could impact the entire Biofuels Industry. The biofuels industry has common hazards and potential consequences like other industries, related to the handling of flammables, dust explosion hazards and toxic or corrosive materials handling. This article ensures the reader understands these specific bioethanol manufacturer's process hazards are very real as demonstrated by past incidents and their catastrophic results. Regulatory obligations are discussed, as well as key engineering resources and design practices to ensure adequate safeguards are incorporated into the design of a new bioethanol manufacturing facility. The industry is fairly new, however, the hazards and safeguards to reduce the risk level with the common hazards are not new. Preliminary indications are this industry has yet to establish the proactive risk management efforts that are required to reduce the risks to a tolerable level. This article is to provide the supporting data and direction to the Biofuels Industry to ensure each are headed down a path of preventing a future catastrophe. © 2009 American Institute of Chemical Engineers Environ Prog, 2009 [source]

Nutrient limitations during the biofiltration of methyl isoamyl ketone

ENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 1 2005
Hyun-Keun Son
With biofiltration, both organic and inorganic compounds that are toxic to humans and volatile organic compounds from a variety of industrial and public sector sources have been effectively removed. During the initial stage of the acclimation period, the removal capacity of the biofilter is primarily attributed to the adsorption capacity of the media. The adsorption capacity of different types of biofilter media was studied. MIAK (methyl isoamyl ketone), which is one of the major air pollutants in painting operations, was used as the target air pollutant for the biofiltration experiments. All the materials tested exhibited very poor adsorption capacity for MIAK. The effect of nutrient limitation was also evaluated. A gradual decrease of removal capacity was observed under the nutrient-limited environment. When nutrient was provided to the biofilter, the removal capacity increased from 55 to 93% in 3 days. A nutrient ratio of chemical oxygen demand (COD):N:P = 200:4:1 was sufficient for the removal of volatile organic compounds from the polluted air stream. © 2004 American Institute of Chemical Engineers Environ Prog, 2004 [source]

Computer and Electronics Product Stewardship: Are We Ready for the Challenge?

ENVIRONMENTAL QUALITY MANAGEMENT, Issue 1 2001
Cate Gable
The PC revolution continues to produce faster and smarter machines at a stunning pace. Almost forgotten in the rush are the millions of nearly new, but suddenly outdated, computers that are abandoned every year. Can product stewardship offer life-after-end-of-life for this growing mountain of "attic-ware," while averting a costly,and potentially toxic,waste disposal crisis? © 2001 by Cate Gable, Axioun Books. Used with permission. [source]

In vivo and in vitro toxicity of decabromodiphenyl ethane, a flame retardant

ENVIRONMENTAL TOXICOLOGY, Issue 4 2010
Tarja Nakari
Abstract Toxicity of a relative new flame retardant, namely decabromodiphenyl ethane (DBDPE), marketed as an alternative to decabromodiphenyl ether (BDE-209) was assessed both in vivo and in vitro using the freshly separated fish hepatocyte assay and standardized water flea and zebrafish egg-larvae tests. The fish hepatocyte assay, based on the synthesis and secretion of vitellogenin from isolated male liver cells produced a clear dose-response curve in the presence of DBDPE. DBDPE induced the induction of hepatic ethoxyresorufin-O-deethylase (EROD) activity at low test concentrations, but started to inhibit the activity at higher concentrations. Also, the induction of the hepatocyte conjugation activity, uridinediphosphoglucuronosyltransferase (UDPGT), was induced with no signs of inhibition even at the highest test concentration. The reduced EROD activity resulted in a drop in the production of vitellogenin by the cells. In vivo tests showed that DBDPE was acutely toxic to water fleas, the 48 h EC-50 value being 19 ,g/L. Moreover, DBDPE reduced the hatching rates of exposed zebra-fish eggs and raised significantly the mortality of hatched larvae. Because there is hardly any information available on the effects of DBDPE on the aquatic environments, it is crucial to obtain more data on the effects and effective concentrations of DBDPE along with its occurrence in the environment. Such data would enable reliable assessments of the risks posed by this flame retardant. © 2009 Wiley Periodicals, Inc. Environ Toxicol 25: 333,338, 2010. [source]

Microcystin extracts induce ultrastructural damage and biochemical disturbance in male rabbit testis

ENVIRONMENTAL TOXICOLOGY, Issue 1 2010
Ying Liu
Abstract In the present research, the changes of ultrastructures and biochemical index in rabbit testis were examined after i.p. injection with 12.5 ,g/kg microcystin (MC) extracts. Ultrastructural observation showed widened intercellular junction, distention of mitochondria, endoplasmic reticulum, and Golgi apparatus. All these changes appeared at 1, 3, and 12 h, but recovered finally. In biochemical analyses, the levels of lipid peroxidation (MDA) and H2O2 increased significantly at 1 h, indicating MC-caused oxidative stress. Finally, H2O2 decreased to the normal levels, while MDA remained at high levels. The antioxidative enzymes (CAT, SOD, GPx, GST) and antioxidants (GSH) also increased rapidly at 1 h, demonstrating a quick response of the defense systems to the oxidative stress. Finally, the activity of CAT, SOD, and GPX recovered to the normal level, while the activity of GST and the concentration of GSH remained at a high level. This suggests that the importance of MCs detoxification by GST via GSH, and the testis of rabbit contained abundant GSH. The final recovery of ultrastructure and some biochemical indexes indicates that the defense systems finally succeeded in protecting the testis against oxidative damage. In conclusion, these results indicate that the MCs are toxic to the male rabbit reproductive system and the mechanism underlying this toxicity might to be the oxidative stress caused by MCs. Although the negative effects of MCs can be overcome by the antioxidant system of testis in this study, the potential reproductive risks of MCs should not be neglected because of their wide occurrence. © 2009 Wiley Periodicals, Inc. Environ Toxicol 2010. [source]