<p>&quot / The aim of the study was to use in vitro human whole blood cultures to screen the water samples collected from the Eerste/Plankenbrug river system for cytotoxicity and inflammatory activity and for the first time investigate the impact on the cell- mediated and humoral immune pathways. Water samples were collected fronm the sites during the dry summer season and rainy winter season. Blood was collected from the healthy male volunteers and diluted with RPMI 1640. For cytotoxicity and inflammatory activity 2.5ul of blood for 18-20 hrs at 37 C... This study shows that waster from the Plankenbrug River is heavily polluted by contaminants from both the agricultural area and informal settlement of Kayamandi. These contaminants can be potentially immunotoxic during the summer season and they can result in inflammatory diarrheal disease and immunosuppression in exposed individuals...&quot / </p>

The understanding of effects of chemical exposure in nature is lagging behind. Predictions of harmful effects of chemicals on aquatic organisms rely mainly on ecotoxicity tests. To improve the understanding of the biological linkage between the cellular and organismal responses to a chemical in an ecotoxicological test, the major aim of this doctoral thesis was to investigate the usefulness of two biochemical endpoints, contents of RNA and ecdysteroids, by incorporating them with life-history traits of copepods (Crustacea). To do so, the two methods needed to be established at our laboratory. Both biochemical methods are more commonly used in basic biological research, but I here present its usefulness in ecotoxicological testing. It was found that individual RNA content as a biochemical endpoint was significantly altered in the brackish water harpacticoid copepod Nitocra spinipes when exposed to the pesticide Lindane (paper IV) and low concentrations (0.16&lt;g . L-1) of the pharmaceutical Simvastatin (paper I) during partial life cycle tests. However, the RNA content was insensitive as endpoint in the fresh water harpacticoid Attheyella crassa during multigenerational exposure (2 – 3 generations) to naturally contaminated sediments (paper III). The second biochemical endpoint, ecdysteroid content (a crustacean growth-hormone), was shown to be a useful tool for ecotoxicological studies using N. spinipes (paper IV), as well as for increasing the understanding of lipid turnover and reproduction of the marine calanoid copepod Calanus finmarchicus (paper V). In paper I and IV, I present a balanced ecotoxicological test, useful for substances with suspected developmental disruptive effects. In this type of test, a balance between test adequacy, exposure time, and costs has been proven useful. Further, the reliability of tests (paper II) with N. spinipes was increased by optimizing its food regime. In paper II, 25 different combinations of micro-algae were tested during short- and long time exposure, and a suitable food source (Rhodomonas salina) was identified, whilst poorer development and reproduction, malformations, and even mortality was induced by other algae. In conclusion, my studies provide useful tools for ecotoxicological testing, as well as for basic understanding of developmental biology of different copepod species.

Petroleum hydrocarbons (PHCs) are a class of ubiquitous contaminants in the environment. PHCs impact to soil and water occur at well sites, refineries, service stations, and other facilities. Petroleum processing and consumption of petroleum products lead to the further release of other PHC pollutants such as Polycyclic Aromatic Hydrocarbons (PAHs) as well as metals. PHCs are causing serious environmental problems due to their widespread use. Hence, the central theme of this thesis addresses hydrocarbon pollutants and co-contaminating metals: their occurrence in environment, their mechanism of toxicity and their remediation via biological processes. This thesis is divided into two parts including seven chapters. The first part includes chapters 2, 3 and 4. Using bioluminescent bacterium Vibrio fischeri, a widely used bioindacator in environmental toxicology, the individual and mixture toxicities of phenanthrenequinone (PHQ), an oxyPAH, combined with copper and cadmium were assessed. PHQ is a main photoproduct of phenanthrene (PHE), a dominant PAH in the environment. Results showed that PHQ is much more toxic than its parent PAH. PHQ, alone or as mixtures with Cu and Cd, damages bacterial cells via enhancing production of reactive oxygen species (ROS). The mixture toxicity of Cu/PHQ was found to be dependent on the ratio of each chemical in the mixture. Two up-regulated genes, protein translocase subunit SecY gene and putative polysaccharide export protein YccZ precursor, were identified to be possibly response to PHQ exposure. Both genes are related to the detoxification of ROS. The second part of this thesis includes chapters 5, 6, and 7. Culture-dependent and -independent approaches were employed to evaluate the roles of bacteria as biodegraders or/and plant growth promoters during phytoremediation at a petroleum land farm (PLF) with a PHC concentration of ~130 g Kg-1. A plant growth promoting rhizobacteria (PGPR) enhanced phytoremediation system (PEP) was applied to remediate PLF soil. PEP promotes plant growth to establish dense vegetative cover. Results of both culturing and molecular methods showed that the enhanced populations and activities of soil microbes due to vigorous plant growth is a key factor in the success of PEP. Introduced PGPR could quickly establish significant populations by utilizing root exudates and dominate the PGPR population on seed coat and root surfaces at the early seedling stage of plant development, and thus modestly affected bacterial community structures at this time; thereafter, with plant growth, the effect of seed treatment on soil microbial community was masked by enhanced indigeneous microbial population. Therefore, the introduced PGPR did not exert significant influence on the indigenous microbial ecosystem. It does dramatically improve plant growth and PHC remediation. Thus, the PEP should be considered as an environmentally safe and effective approach for removing PHCs from impacted soils.

Petroleum hydrocarbons (PHCs) are a class of ubiquitous contaminants in the environment. PHCs impact to soil and water occur at well sites, refineries, service stations, and other facilities. Petroleum processing and consumption of petroleum products lead to the further release of other PHC pollutants such as Polycyclic Aromatic Hydrocarbons (PAHs) as well as metals. PHCs are causing serious environmental problems due to their widespread use. Hence, the central theme of this thesis addresses hydrocarbon pollutants and co-contaminating metals: their occurrence in environment, their mechanism of toxicity and their remediation via biological processes. This thesis is divided into two parts including seven chapters. The first part includes chapters 2, 3 and 4. Using bioluminescent bacterium Vibrio fischeri, a widely used bioindacator in environmental toxicology, the individual and mixture toxicities of phenanthrenequinone (PHQ), an oxyPAH, combined with copper and cadmium were assessed. PHQ is a main photoproduct of phenanthrene (PHE), a dominant PAH in the environment. Results showed that PHQ is much more toxic than its parent PAH. PHQ, alone or as mixtures with Cu and Cd, damages bacterial cells via enhancing production of reactive oxygen species (ROS). The mixture toxicity of Cu/PHQ was found to be dependent on the ratio of each chemical in the mixture. Two up-regulated genes, protein translocase subunit SecY gene and putative polysaccharide export protein YccZ precursor, were identified to be possibly response to PHQ exposure. Both genes are related to the detoxification of ROS. The second part of this thesis includes chapters 5, 6, and 7. Culture-dependent and -independent approaches were employed to evaluate the roles of bacteria as biodegraders or/and plant growth promoters during phytoremediation at a petroleum land farm (PLF) with a PHC concentration of ~130 g Kg-1. A plant growth promoting rhizobacteria (PGPR) enhanced phytoremediation system (PEP) was applied to remediate PLF soil. PEP promotes plant growth to establish dense vegetative cover. Results of both culturing and molecular methods showed that the enhanced populations and activities of soil microbes due to vigorous plant growth is a key factor in the success of PEP. Introduced PGPR could quickly establish significant populations by utilizing root exudates and dominate the PGPR population on seed coat and root surfaces at the early seedling stage of plant development, and thus modestly affected bacterial community structures at this time; thereafter, with plant growth, the effect of seed treatment on soil microbial community was masked by enhanced indigeneous microbial population. Therefore, the introduced PGPR did not exert significant influence on the indigenous microbial ecosystem. It does dramatically improve plant growth and PHC remediation. Thus, the PEP should be considered as an environmentally safe and effective approach for removing PHCs from impacted soils.

Thesis (Ph. D.)--West Virginia University, 2002. / Title from document title page. Document formatted into pages; contains x, 140 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 120-131).

Engineered nanomaterials (NMs), defined as artificially made particles possessing at least one dimension within 1 – 100 nm range, have different physical and biological properties from bulk materials of the same chemistry due to their increased surface areas. Their novel properties have facilitated the prolific growth of commercial NM-incorporating products. NMs may be leached into the aquatic environment during the product life-cycle, but their ecological impacts on marine ecosystems are currently largely unknown. Therefore, this study primarily aimed to investigate the physicochemical characteristics (particle and aggregate sizes, dissolution rate) and in vivo toxicities of commonly-used metallic NMs to marine organisms under various environmental scenarios. First, in vivo ecotoxicity screening tests, using the marine diatom Skeletonema costatum and the rotifer Brachionus sp., were conducted for nine common nano metal oxides which had been applied in various commercial products. Among them, nano zinc oxide (nZnO) and nano magnesia (nMgO) were found to be the most toxic NMs to both organisms, as they induced oxidative stress by increasing reactive oxygen species (ROS) production in the organism. The endocrine disrupting potential of nZnO was revealed by its modulation of transcriptions of the genes for retinoid X receptor (RXR) in the rotifer. Conversely, nano alumina (nAl2O3) and nano indium oxide (nIn2O3) were the least toxic NMs. Due to its high potency, toxicity of nZnO was further evaluated using five marine organisms (i.e., microalgae Thalassiosira pseudonana and S. costatum, copepod Tigriopus japonicus, amphipod Elasmopus rapax, and medaka Oryzias melastigma). Crustaceans were generally more sensitive to nZnO. Toxicity of nZnO was mainly attributed to metal ion dissolution, although nanoparticulate effects such as aggregation and adhesion of nZnO onto the animal’s exoskeleton as well as physical disruption of cell structures could not be discounted. Due to the fact that the dissolution of nZnO decreased from 16 mg Zn L-1 at 4°C to 1.4 mg Zn L-1 at 35°C, and Zn ion was the main contributing factor for nZnO toxicity at 25°C, it was postulated that nZnO toxicity would increase with decreasing temperature. This hypothesis was tested with S. costatum, O. melastigma and the amphipod Melita longidactyla through a factorial design experiment (i.e., 2 concentrations x 4 temperatures). In agreement with the hypothesis, the growth of S. costatum was significantly inhibited by nZnO at the lowest test temperature (15°C). However, contradictive results were observed in the two animal species. For instance, the amphipod could reduce the nZnO uptake and its toxicity by undergoing metabolic depression and dormancy at lower temperatures. As the morphology and coating of NMs utilized in commercial products may differ from those employed in toxicity studies, T. japonicus was exposed to nZnO-containing sunscreens to assess the effects of nZnO and Zn2+ released in seawater during epidermal applications. Based on their genetic biomarker responses, the results suggested that other components in sunscreens could react synergistically or antagonistically on nZnO toxicity. Clearly, there is a need for further study of the combined effects of NMs and other common chemical contaminants to marine organisms. / published_or_final_version / Biological Sciences / Doctoral / Doctor of Philosophy

abstract / Biological Sciences / Doctoral / Doctor of Philosophy

No description available.

published_or_final_version / Medical Sciences / Master / Master of Medical Sciences

published_or_final_version / Medical Sciences / Master / Master of Medical Sciences