1,721,032 research outputs found
Ionizing radiation-induced DNA damage response identified in marine mussels, Mytilus sp
No full textThere is growing concern over the potential detrimental impact of ionizing radiation on natural biota. The mechanistic cause-and-effect impact of ionizing radiation has yet to be characterized in any aquatic species. Adopting an integrated approach, including radiochemical analysis of environmental samples, we evaluate molecular responses to ionizing radiation in the marine mussel, Mytilus edulis. These responses included analyses of RAD51 mRNA expression, a gene involved in the repair of DNA double strand breaks, and induction of DNA strand breaks using the comet assay, in samples collected from a site impacted by low level ionizing radiation discharges. Based on activities of the radionuclides measured in sediment and mussel tissue at the discharge site, external and internal dose rates were low, at ca. 0.61 ?Gyh?1 and significantly lower than the generic (all species) “no effect” dose rate of 10 uGyh?1, yet DNA strand breakage and RAD51 mRNA expression were both altered
Emerging environmental contaminants and human health : risk assessment of dietary exposure to microplastics
Get PDFMicroplastics (MPs) are an emerging contaminant ubiquitous in the environment. There is growing concern regarding potential human health effects. A major human exposure route is hypothesised to be the dietary pathway via ingestion of contaminated food. A risk assessment perspective was employed, which is the standard approach for human health protection regarding food safety. It is comprised of the four interconnected evidence-based steps of hazard identification, hazard characterization, exposure assessment and risk characterization. Existing scientific data were collected via the execution of scoping, systematic and rapid reviews, using state of the art, robust methodology. Quantitative meta- analysis and meta-regression analyses were also employed. Two bespoke novel risk-of-bias tools were developed and implemented in the execution of the reviews for the standardized quality appraisal of the studies.Seventy-two studies were included in the systematic reviews on food contamination from three categories. The majority of the samples were contaminated in varying levels: 0-4889 MPs/L in drinking water, 0–10.5 MPs/g in seafood and 0–1674 MPs/kg in salt, thus establishing the dietary ingestion route for MP human exposures. According to the exposure assessment modelling, the estimated levels for MP dietary aggregate exposures could be as high as 3.6 million MPs per year.Seventeen studies were included in a rapid review focusing on human cell in vitro MP toxicological effects. Four biological endpoints displayed MP-associated effects: cytotoxicity, immune response, oxidative stress and barrier attributes. Irregular shape was found to be the only MP characteristic predicting cell death, along with the duration of exposure and MP concentration (μg/mL). Minimum concentrations of 10 μg/mL (5– 200 μm), had an adverse effect on cell viability, and 20 μg/mL (0.4 μm) on cytokine release, effectively constituting thresholds of adverse effects. The preliminary comparison of the levels of the thresholds and the exposures reveals that human health could be at risk due to MP dietary exposures.Further high-quality research using standardized methods is needed to cement the scientific evidence on MP contamination and human exposures. On the other hand, serious data gaps exist regarding toxicodynamics and toxicokinetics which are necessary for a complete toxicological profile
Emerging environmental contaminants and human health : risk assessment of dietary exposure to microplastics
Get PDFMicroplastics (MPs) are an emerging contaminant ubiquitous in the environment. There is growing concern regarding potential human health effects. A major human exposure route is hypothesised to be the dietary pathway via ingestion of contaminated food. A risk assessment perspective was employed, which is the standard approach for human health protection regarding food safety. It is comprised of the four interconnected evidence-based steps of hazard identification, hazard characterization, exposure assessment and risk characterization. Existing scientific data were collected via the execution of scoping, systematic and rapid reviews, using state of the art, robust methodology. Quantitative meta- analysis and meta-regression analyses were also employed. Two bespoke novel risk-of-bias tools were developed and implemented in the execution of the reviews for the standardized quality appraisal of the studies.Seventy-two studies were included in the systematic reviews on food contamination from three categories. The majority of the samples were contaminated in varying levels: 0-4889 MPs/L in drinking water, 0–10.5 MPs/g in seafood and 0–1674 MPs/kg in salt, thus establishing the dietary ingestion route for MP human exposures. According to the exposure assessment modelling, the estimated levels for MP dietary aggregate exposures could be as high as 3.6 million MPs per year.Seventeen studies were included in a rapid review focusing on human cell in vitro MP toxicological effects. Four biological endpoints displayed MP-associated effects: cytotoxicity, immune response, oxidative stress and barrier attributes. Irregular shape was found to be the only MP characteristic predicting cell death, along with the duration of exposure and MP concentration (μg/mL). Minimum concentrations of 10 μg/mL (5– 200 μm), had an adverse effect on cell viability, and 20 μg/mL (0.4 μm) on cytokine release, effectively constituting thresholds of adverse effects. The preliminary comparison of the levels of the thresholds and the exposures reveals that human health could be at risk due to MP dietary exposures.Further high-quality research using standardized methods is needed to cement the scientific evidence on MP contamination and human exposures. On the other hand, serious data gaps exist regarding toxicodynamics and toxicokinetics which are necessary for a complete toxicological profile
An investigation of the uptake of estradiol in the bivalve Mytilus spp. corresponding biological implications and the effect of the addition of Sporopollenin on bioavailability
Get PDFThere has been concern over the past two decades over estrogenic hormones such as 17 α-ethinylestradiol and 17 β-estradiol (E2) in fresh water and marine ecosystems and the risk to aquatic organisms even with low exposure levels. This study is to access whether there is any bioaccumulation in mantle tissue of Mytilus edulis exposed to a known concentration of E2 in a controlled experiment and whether the introduction of sporopollenin, exposed to the same concentration of E2, has a similar effect with bioaccumulation in regard to the use of sporopollenin exine capsules (SECs) as a sequestering agent to remove estrogens from water systems.This study involved an experiment using M. edulis exposed over a week with a regular dose of 200 ng/L E2, SECs treated with the 200 ng/L of E2 and with untreated SECs and untreated Mytilus as controls. At the end of the experiment, tissue was preserved for histology purposes to ascertain the sex and stage of gametogenesis and to detect any presence of SECs. Portions of the mantle and digestive tract and gills were frozen for chemical analysis to ascertain if either free or conjugated E2 had been bioaccumulated. A portion of the mantle was frozen in RNAlater™ for qPCR determination of mRNA ER expression in either of the exposure groups. In parallel, analytical chemistry and extraction methods were optimised to determine the levels of E2 in tissues.Histological preparations of gonad tissue from all Mytilus indicated the presence of SECs in the gonad tissues of the Mytilus exposed to SECs only. The water filtrates from the tanks of those animals also indicated the presence of SECs in the water throughout the exposure experiment. Chemical analysis of the water indicated that E2 dissolved in the water was present. The Mytilus in the exposure experiment were in the mid to late development stage of gametogenesis. The results of mRNA ER 2 gene expression indicated no significant difference in ER gene expression in the E2 exposed Mytilus compared to the controls but there was a significant difference in ER gene expression compared to mussels that were exposed to SECs and SECs plus E2. There was no statistical significance in the ER gene expression between the SECs and E2 treated SECs. The chemical analysis of the gonad tissue from the exposure experiment was not undertaken due to time constraints but free E2 was extracted from gonad tissue and from the E2 treated SECs, in a similar experiment. As there is such a notable difference in fold change between both of the SECs treatments and the control, there is an unknown biological influence on the mRNA ER gene expression.In terms of wider implications of this work, the data shows that the SECs are very efficient at adsorbing or absorbing E2 and this property could be applied as a method to remove E2 from WWTPs. But it is not known if the SECs could be applied for this purpose until there is sufficient evidence of bioavailability
Sporopollenin : applications in water purification
Get PDFWater pollution from emerging contaminants is increasingly in the spotlight, as research on the impacts on the environment is revealing more about the dangers to both animals in the aquatic environment and human health. Pharmaceuticals, personal care products, surfactants and pesticides have been proven to have endocrine-disrupting properties, affecting not only the aquatic life but human life as well. Conventional wastewater treatment plants need to updated in order to deal with this family of chemicals, since they are currently incapable of removing them using traditional methods. New methods need to be developed since the current ones leave behind around 60 - 90% of the initial contaminant concentration and re-introduce it to the water cycle. Adsorption procedures have been proven to be very effective on water treatment, targeting emerging contaminants, with research focusing on developing new materials, that apart from being effective should also be environmentally friendly.Sporopollenin is the name of a bio-polymer found in nature, constructing the outer shell (exine) of the capsule of a pollen grain or spore. The capsule itself - sporopollenin exine capsule (SpEC) - evolved to protect the genetic material contained in each grain/spore, hence sporopollenin has been proven to be chemically stable and very resistant to harsh environmental conditions. SpECs can be extracted from pollen grains or spores producing empty capsules (devoid of their genetic material), presenting a variety of differently sized microcapsules and shapes depending on the plant species. These capsules are monodispersed, presenting great mechanical strength as well as permeability. The material has a high surface area due to the porous nature with many multi-directional channels leading to the core of the capsule, giving them features and properties that are ideal for contaminant adsorption.The focus of this thesis was the investigation of SpECs deriving from Lycopodium clavatum by multiple extraction methodologies for applications on emerging contaminant adsorption. Different extraction procedures were developed, as well as surface modification protocols, in order to optimise the material for the different pollutants. The resulting SpECs were tested against four different contaminants; diclofenac, triclosan, oestradiol and phosphates, under different experimental settings, either lab based or closer to real world conditions. The results revealed that SpECs offer a very promising natural material, presenting high efficiency against the tested contaminants, with low-cost production, offering an environmentally friendly approach to the problem of water purification.For diclofenac, the most efficient SpECs type was SpECs(3)AM, with a maximum adsorption capacity value of 27.4 mg/g under a packed-bed setup. For triclosan, SpECs(3) was the most efficient type, presenting a maximum adsorption capacity of 37 mg/g under packed-bed setup or a KF value of 35.14 mg(1−1/n)/gL−1/n for adsorption from a solution. For oestradiol adsorption, SpECs(1) worked the best, presenting a maximum adsorption capacity of 42.5 mg/g. For phosphates, all tested SpECs presented similar adsorption capacities, with the water/Fe loaded SpECs(3) presenting the highest, 2.1 mg/g.SpECs presented adsorption capacity values far beyond what would be required for treating hospital effluent or surface waters and very good adsorption rates, especially for diclofenac and triclosan. Although the oestradiol experiments resulted in excellent maximum adsorption capacity, the rate of adsorption was below what would be required for treating large bodies of flowing water. However all other materials exhibited very promising rates of adsorption, particularly SpECs(3)AM for diclofenac and SpECs(3) for triclosan, warranting scale-up experiments for the treatment of such volumes as hospital effluents (55 - 530 L/min).SpECs(3) and their aminated form, SpECs(3)AM were proven to be the best candidates for contaminant adsorption, with SpECs(3) ticking all the boxes for a successful adsorbent; apart from their excellent adsorption behaviour, their production is fast and low-cost, they are environmentally friendly since they derive from plant spores, the chemicals used are not harsh to the environment nor were high temperature treatments or long reaction times required and they also presented good reusability
Sporopollenin : applications in water purification
Get PDFWater pollution from emerging contaminants is increasingly in the spotlight, as research on the impacts on the environment is revealing more about the dangers to both animals in the aquatic environment and human health. Pharmaceuticals, personal care products, surfactants and pesticides have been proven to have endocrine-disrupting properties, affecting not only the aquatic life but human life as well. Conventional wastewater treatment plants need to updated in order to deal with this family of chemicals, since they are currently incapable of removing them using traditional methods. New methods need to be developed since the current ones leave behind around 60 - 90% of the initial contaminant concentration and re-introduce it to the water cycle. Adsorption procedures have been proven to be very effective on water treatment, targeting emerging contaminants, with research focusing on developing new materials, that apart from being effective should also be environmentally friendly.Sporopollenin is the name of a bio-polymer found in nature, constructing the outer shell (exine) of the capsule of a pollen grain or spore. The capsule itself - sporopollenin exine capsule (SpEC) - evolved to protect the genetic material contained in each grain/spore, hence sporopollenin has been proven to be chemically stable and very resistant to harsh environmental conditions. SpECs can be extracted from pollen grains or spores producing empty capsules (devoid of their genetic material), presenting a variety of differently sized microcapsules and shapes depending on the plant species. These capsules are monodispersed, presenting great mechanical strength as well as permeability. The material has a high surface area due to the porous nature with many multi-directional channels leading to the core of the capsule, giving them features and properties that are ideal for contaminant adsorption.The focus of this thesis was the investigation of SpECs deriving from Lycopodium clavatum by multiple extraction methodologies for applications on emerging contaminant adsorption. Different extraction procedures were developed, as well as surface modification protocols, in order to optimise the material for the different pollutants. The resulting SpECs were tested against four different contaminants; diclofenac, triclosan, oestradiol and phosphates, under different experimental settings, either lab based or closer to real world conditions. The results revealed that SpECs offer a very promising natural material, presenting high efficiency against the tested contaminants, with low-cost production, offering an environmentally friendly approach to the problem of water purification.For diclofenac, the most efficient SpECs type was SpECs(3)AM, with a maximum adsorption capacity value of 27.4 mg/g under a packed-bed setup. For triclosan, SpECs(3) was the most efficient type, presenting a maximum adsorption capacity of 37 mg/g under packed-bed setup or a KF value of 35.14 mg(1−1/n)/gL−1/n for adsorption from a solution. For oestradiol adsorption, SpECs(1) worked the best, presenting a maximum adsorption capacity of 42.5 mg/g. For phosphates, all tested SpECs presented similar adsorption capacities, with the water/Fe loaded SpECs(3) presenting the highest, 2.1 mg/g.SpECs presented adsorption capacity values far beyond what would be required for treating hospital effluent or surface waters and very good adsorption rates, especially for diclofenac and triclosan. Although the oestradiol experiments resulted in excellent maximum adsorption capacity, the rate of adsorption was below what would be required for treating large bodies of flowing water. However all other materials exhibited very promising rates of adsorption, particularly SpECs(3)AM for diclofenac and SpECs(3) for triclosan, warranting scale-up experiments for the treatment of such volumes as hospital effluents (55 - 530 L/min).SpECs(3) and their aminated form, SpECs(3)AM were proven to be the best candidates for contaminant adsorption, with SpECs(3) ticking all the boxes for a successful adsorbent; apart from their excellent adsorption behaviour, their production is fast and low-cost, they are environmentally friendly since they derive from plant spores, the chemicals used are not harsh to the environment nor were high temperature treatments or long reaction times required and they also presented good reusability
An investigation of the uptake of estradiol in the bivalve Mytilus spp. corresponding biological implications and the effect of the addition of Sporopollenin on bioavailability
No full textThere has been concern over the past two decades over estrogenic hormones such as 17 α-ethinylestradiol and 17 β-estradiol (E2) in fresh water and marine ecosystems and the risk to aquatic organisms even with low exposure levels. This study is to access whether there is any bioaccumulation in mantle tissue of Mytilus edulis exposed to a known concentration of E2 in a controlled experiment and whether the introduction of sporopollenin, exposed to the same concentration of E2, has a similar effect with bioaccumulation in regard to the use of sporopollenin exine capsules (SECs) as a sequestering agent to remove estrogens from water systems.This study involved an experiment using M. edulis exposed over a week with a regular dose of 200 ng/L E2, SECs treated with the 200 ng/L of E2 and with untreated SECs and untreated Mytilus as controls. At the end of the experiment, tissue was preserved for histology purposes to ascertain the sex and stage of gametogenesis and to detect any presence of SECs. Portions of the mantle and digestive tract and gills were frozen for chemical analysis to ascertain if either free or conjugated E2 had been bioaccumulated. A portion of the mantle was frozen in RNAlater™ for qPCR determination of mRNA ER expression in either of the exposure groups. In parallel, analytical chemistry and extraction methods were optimised to determine the levels of E2 in tissues.Histological preparations of gonad tissue from all Mytilus indicated the presence of SECs in the gonad tissues of the Mytilus exposed to SECs only. The water filtrates from the tanks of those animals also indicated the presence of SECs in the water throughout the exposure experiment. Chemical analysis of the water indicated that E2 dissolved in the water was present. The Mytilus in the exposure experiment were in the mid to late development stage of gametogenesis. The results of mRNA ER 2 gene expression indicated no significant difference in ER gene expression in the E2 exposed Mytilus compared to the controls but there was a significant difference in ER gene expression compared to mussels that were exposed to SECs and SECs plus E2. There was no statistical significance in the ER gene expression between the SECs and E2 treated SECs. The chemical analysis of the gonad tissue from the exposure experiment was not undertaken due to time constraints but free E2 was extracted from gonad tissue and from the E2 treated SECs, in a similar experiment. As there is such a notable difference in fold change between both of the SECs treatments and the control, there is an unknown biological influence on the mRNA ER gene expression.In terms of wider implications of this work, the data shows that the SECs are very efficient at adsorbing or absorbing E2 and this property could be applied as a method to remove E2 from WWTPs. But it is not known if the SECs could be applied for this purpose until there is sufficient evidence of bioavailability
The molecular basis of circadian and seasonal rhythms in the blue mussel Mytilus edulis
No full textExposure to regular environmental oscillations such as day/night have allowed organisms to evolve biological mechanisms to adaptively anticipate and prepare for rhythmic environmental change. A network of gene-protein interactions between clock genes and their proteins comprise the molecular clock mechanism at the heart of regulating biological rhythms. Though this is an endogenous and self-regulating system, elements of this network can be entrained by exogenous biotic and abiotic factors. This synchronisation process between environmental cycles and endogenous rhythms is facilitated by cues like light and temperature, which influence clock gene expression patterns.Marine bivalves often inhabit intertidal habitats under the influence of numerous oscillating environmental conditions, though little is known about how they regulate their biological timekeeping. In this thesis, we investigate the molecular regulation of biological rhythms in the ecologically and commercially important blue mussel, M. edulis, over different timeframes. For the first time in this species, we isolate and characterise a number of clock genes (Clk, Cry1, ROR/HR3, Per and Rev-erb) and clock-associated genes (ARNT, Timeout-like and aaNAT). Rhythmic clock gene expression is demonstrated in the absence of light cues, indicative of endogenous clock control. Differential expression of Cry1 expression between males and females under the same conditions indicates sex-specific regulation and/or function. In addition, diurnal temperature cycles modulated the otherwise rhythmic expression of Rev-erb to constant levels demonstrating an interaction of temperature with clock function. Instances of seasonal clock mRNA expression differences were found, in addition to a number of other putative seasonal genes, indicating a possible mechanism by which seasonal cues can inform rhythmic biological processes.Understanding the influence of environmental cues on the molecular clock is essential in predicting the outcomes of future environmental change on fundamental rhythmic processes, in particular the impacts of decoupled environmental cues on the already highly dynamic and stressful intertidal zone
The molecular basis of circadian and seasonal rhythms in the blue mussel Mytilus edulis
Get PDFExposure to regular environmental oscillations such as day/night have allowed organisms to evolve biological mechanisms to adaptively anticipate and prepare for rhythmic environmental change. A network of gene-protein interactions between clock genes and their proteins comprise the molecular clock mechanism at the heart of regulating biological rhythms. Though this is an endogenous and self-regulating system, elements of this network can be entrained by exogenous biotic and abiotic factors. This synchronisation process between environmental cycles and endogenous rhythms is facilitated by cues like light and temperature, which influence clock gene expression patterns.Marine bivalves often inhabit intertidal habitats under the influence of numerous oscillating environmental conditions, though little is known about how they regulate their biological timekeeping. In this thesis, we investigate the molecular regulation of biological rhythms in the ecologically and commercially important blue mussel, M. edulis, over different timeframes. For the first time in this species, we isolate and characterise a number of clock genes (Clk, Cry1, ROR/HR3, Per and Rev-erb) and clock-associated genes (ARNT, Timeout-like and aaNAT). Rhythmic clock gene expression is demonstrated in the absence of light cues, indicative of endogenous clock control. Differential expression of Cry1 expression between males and females under the same conditions indicates sex-specific regulation and/or function. In addition, diurnal temperature cycles modulated the otherwise rhythmic expression of Rev-erb to constant levels demonstrating an interaction of temperature with clock function. Instances of seasonal clock mRNA expression differences were found, in addition to a number of other putative seasonal genes, indicating a possible mechanism by which seasonal cues can inform rhythmic biological processes.Understanding the influence of environmental cues on the molecular clock is essential in predicting the outcomes of future environmental change on fundamental rhythmic processes, in particular the impacts of decoupled environmental cues on the already highly dynamic and stressful intertidal zone
Molecular level effects of low seawater pH on the marine polychaete Platynereis dumerilii
No full textGlobal changes lead to a measurable reduction of ocean pH. These rapid water chemistry changes are expected to have negative effects on ecosystems and keystone sensitive species. It is predicted that many different physiological processes will be altered under low pH conditions. To date, most studies focus on calcifying organisms however there is a need for further investigations into the precise molecular level changes that occur in other marine organisms.This work investigates the molecular level changes taking place in a non-calcifying, polychaete species P. dumerilii after exposure to acidified seawater, induced by HCl and CO₂. Using laboratory-cultured worms, a targeted approach was employed to examine key genes involved in acid-base regulation and metabolism, as well as a global approach to find other potential mechanisms involved in low pH response. Genes involved in general metabolism and defence processes were down-regulated after exposure with HCl, indicating impacts following exposure. However, the up-regulation of the acid-base transporter NHE and an additional expression of NHE in the anus area of P. dumerilii larvae, may suggest possible compensation mechanisms.Gene expression profiles were also obtained from P. dumerilii, collected from inside and outside natural CO₂ vents (Ischia, Italy), as well as following a pH translocation experiment. Expression analysis of target genes showed significant differences between the worms from vent sites in comparison to non-vent sites, suggesting that worms in the natural low pH areas are adapted to the different seawater conditions. Collectively this work shows that low seawater pH, induced by both HCl and CO₂, alters the gene expression in P. dumerilii. This provides new knowledge regarding the acid-base regulation mechanisms in a marine polychaete and will help to predict how P. dumerilii may respond to ocean acidification
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