The toxicity of nickel to Phaeodactylum tricornutum has been estimated using 14C-fixation and growth curve techniques. The accumulation of nickel has been followed using 63N1. The binding of nickel was found to conform to saturation kinetics and binding constants have been determined. 10-3M EDIA was found to remove approximately 70% of the bound nickel. Experiments on the effect of temperature on nickel uptake, and the uptake of nickel by living and killed cells have supported the suggestion that nickel uptake is a passive process. A model for nickel binding, based on nickel efflux kinetics, has been proposed. The growth of Chlorella stigmatophora in medium containing nickel, cadmium or zinc has bean investigated. The accumulation of 63 Ni, 6'5Zn and 109Cd has been followed. Binding of these metals has been found to conform to saturation kinetics and binding constants have been estimated. EDTA was found to remove bound nickel and zinc from calls of C.stigmatophora, but to have no affect on bound cadmium. Zinc and cadmium were found to compete mutually for binding sites, but these metals did not compete with nickel and vice versa. No evidence has been presented for an active component of nickel, zinc or cadmium uptake. It has been suggested that the principal binding groups for zinc and cadmium in C.atigmatophora are sulphydryl.

No description available.

No description available.

The ability of acute tests to reflect damage induced from continuous exposure to low concentrations of xenobiotics for a prominent part of an animals life span is speculative. The assessment of human risk from exposure to genotoxic chemicals in drinking water, of both agricultural and industrial origin, and from water purification processes, is one such example. An <I>in vivo</I> micronucleus assay has been developed for this purpose. The assay involved the exposure of the amphibian <I>Xenopus laevis</I> from embryo to late tadpole stage. Micronuclei frequencies were estimated from the erythrocyte population and mortality, development, growth and behaviour as well as subtle changes in erythrocyte cell cycle kinetics were additionally assessed. For comparative purposes, an <I>in vitro</I> micronucleus assay for a <I>Xenopus </I>kidney epithelial cell line was developed. Both assays were validated with four CEC suspected aneuploidy inducing compounds, namely hydroquinone, benlate, cadmium, chloride and thimerosal. The results compared well to those observed in mammalian micronucleus assays but some discordance was observed between the <I>in vivo</I> and <I>in vitro</I> results; explanations for the variability are provided. Confirmation of the sensitivity of the <I>Xenopus </I>assays was achieved by the investigation of water sampled from a chlorination and ozone treatment plant, from within the Severn Trent Water Authority catchment area. The results were compared to the established <I>Salmonella </I>Plate Incorporation Mutation assay and were highly comparable. In contrast to most assays, the <I>in vivo</I> assay was sufficiently sensitive that concentration of the water samples was not required. The <I>in vivo</I> assay also proved suitable for the detection of teratogens, the application of which was investigated. The <I>in vivo</I> assay presented in this study, therefore, examines a variety of endpoints and is highly superior to the toxicity assays presently used to monitor water quality.

Chlorinated organic chemicals are widely used in industry and are present in the environment. Twelve chlorinated aliphatic hydrocarbons, namely carbon tetrachloride, 1,2-dichloroethane, 1,1,1-trichloroethane, 1,1,2-trichloroethane, hexachloroethane, 1,2-dichloroethylene, trichloroethylene, 1,3-dichloropropane, 1,2,3-trichloropropane, 2,3-dichlorobutane, 1-chlorohexane and 1,1,3-trichloropropene were investigated to determine their influence upon the fidelity of cell division in cultured mammalian cells. In order to determine the influence of these chemical compounds upon the fidelity of cell division, a technique known as differential staining of chromosomes and spindle was performed with two genetically engineered cell lines and their parental cell line. The genetically engineered cell lines used in this study expressed a human P450 enzyme, CYP2E1. Four chemicals, trichloroethylene, 1,2-dichloroethane, 2,3-dichlorobutane and 1-chlorohexane required bioactivation in order to induce spindle damage in cultured mammalian cells whereas all the other chemicals were direct-acting spindle poisons with the exception of 1,1,1-trichloroethane which hardly influenced the fidelity of cell division in all three cell lines. Micronucleus assays were performed to study at which one of the four phases in V79d-MZ cell cycle, the cells were most vulnerable to the effects of two selected chlorinated hydrocarbons. To carry out this assay the cells were synchronized using 1-2% of DMSO. The same assay was also used to investigate at which phase of the cell cycle, the enzyme CYP2E1 activates trichloroethylene. The phase at which the V79d-MZ cells were most vulnerable to the chemical effects was mitosis (M). Finally an apoptosis assay was used to investigate whether the chlorinated aliphatic hydrocarbons are inducing cell death: apoptosis or necrosis using annexin-V and from this it was found that 1,2-dichloroethylene induced apoptosis.

The aim of this project was to develop predictive models for the impact of environmental pollution on marine invertebrate cellular immune function, through the analysis of the effects of season and selected organic chemicals on <I>Mytilus edulis </I>cellular immunity. In addition, the seasonal variation in <I>Arenicola marina </I>and <I>Asterias rubens </I>cellular immune function was studied to assess the suitability of these species as bioindicators of pollution. To achieve these aims, the blood cells of <I>M. edulis </I>and <I>A. marina </I>were initially classified into 3 and 5 subpopulations, respectively, based on the morphology and differential staining patterns of fixed cells, whereas the coelomocytes of <I>A. rubens </I>were classed as a single population. The phagocytic ability of <I>M. edulis </I>and <I>A. marina</I> blood cells was impaired during periods of spawning and the stability of lysosomal membranes decreased following these periods. Neutral red retention and phagocytosis assays were also employed to investigate the effects of organic chemicals, with known structural properties, on <I>M. edulis</I> cellular immune function, in order to identify structure-activity relationships. The chemicals studied were the amphiphilic cations, chlorpromazine (CP), clozapine (CZ) and chloroquine (CQ), the PAH, phenanthrene (PH) and the nitro-aromatic, methylene green (MG). Chlorpromazine and MG caused the greatest reductions in haemocyte lysosomal membrane integrity and phagocytic ability out of the 5 chemicals studied, which was believed to result, in part, from the inhibition of oxidative phosphorylation, thus limiting ATP available for the lysosomal retention of NR and phagocytosis, and the generation of radicals by CP and MG, which, in turn, may damage cell membranes. Finally, the NR retention and phagocytosis assays, developed in this project, were employed in field studies to compare the cellular immune function of <I>M. edulis</I> and <I>A. marina </I>sampled from 'polluted' and 'unpolluted' sites in South-West Wales. <I>A. marina </I>proved tolerant to oil pollution, presumably due to their ability, like other polychaetes, to metabolise oil hydrocarbons. In contrast, <I>M. edulis</I> cellular immunity was reduced at an industrialised, 'polluted' site compared with an 'unpolluted', rural site, and this trend correlates with tissue hydrocarbon burden.

The main object of this investigation was to study the occurrence and distribution of the phytoplankton off the Mumbles, Swansea Bay and record changes in the physical and chemical factors in this area during the period 1990-1992. The data obtained will serve as a basis of comparison with the situation after the planned modification of the sewage outfall in Swansea Bay. Changes in nutrients (N, P, Si), salinity, temperature and rainfall, together with numbers and species composition of the phytoplankton were monitored fortnightly. Measurements were made of pigment concentrations and primary productivity estimated as <SUP>14</SUP>C uptake. Counts were also made of zooplankton. An attempt has been made to correlate phytoplankton parameters and environmental factors. The study revealed a cyclic increase of neoplankton cell numbers, chlorophyll and <SUP>14</SUP>C fixation in the spring. Weather conditions appear to determine the timing of the bloom. Nitrate appears to be the most important nutrient controlling the onset and possible size of the bloom. However, ammonium was present throughout the year, presumably derived from the sewage outfall. Ammonium probably also served as a nitrogen source, since laboratory experiments on isolated nanoplanktonic flagellates indicated low levels of nitrate reductase and analyses for amino acids in phytoplankton samples did not indicate nitrogen starvation even when the nitrate content of the seawater was low. Chlorophyll levels in the water indicated that nanoplankton showed maximum development in the summer, together with dinoflagellates. The occurrence of a nanoplanktonic flora was confirmed by <SUP>14</SUP>C fixation studies. Diatoms were dominant in the net plankton with <i>Skeletonema costatum</i> usually dominating during the spring.

The present study has been carried out using three decapod crustaceans, which were chosen as indicators assay organisms for pollution by heavy metals (copper, lead and chromium) and hydrocarbons (benzene, crude oil and hexane). LT5 and LT0 values were determined for these heavy metals during summer and winter seas. Winter treatments showed an increase in survival rate by comparison with those in summer treatments. IT and LT values were also determined for males and females of shore crabs 50Carcinus"D maenas treated with these metals. Accumulation of copper ions by gills, hepatopancreas and gonads of C. vulgaris and P. serratus collected from Swansea Bay and Mumbles Head and of C. maenas collected from Swansea Bay, Mumbles Head, Oxwich and Rhossili was determined after exposure to this metal. In C. maenas the accumulation values for the four stations could be placed in the following order: for gills, Mumbles Head > Oxwich > Rhossili > Swansea Bay: for gonads, Mumbles Head > Oxwich > Swansea Bay > Rhossili and for hepatopancreas, Mumbles Head > Oxwich > Swansea Bay > Rhossili. It seems that Mumbles Head is the most polluted and Rhossili is the least polluted of these stations. The effects of these metals at three temperatures (8, 15 and 22°C) on oxygen consumption rates of C. maenas were determined using a Gilson respirometer. A reduction in oxygen consumption rates was generally noted. The toxicity of benzene, crude oil and hexane on these specimens was determined during 96 hrs. C. vulgaris is more sensitive than C. maenas and this species is more sensitive than P. serratus. Synergistic effects of temperature and salinity on the survival of C. maenas were recorded, using six temperatures and fifteen salinities. The effect of various temperatures on total lipid content has also been studied. Thin layer chromatography was used to separate the lipid fractions. LC values for these three species, treated with three heavy metals and hydrocarbons, were determined. Deficiencies in studies of Swansea Bay are discussed, together with general aspects of pollution by hydrocarbons and heavy metals. The importance of devising an efficient and easy method to remove oil from the environment is also mentioned. Data on production of petroleum and seaborne oil pollution are introduced, especially for the Middle East. The Arabian Gulf needs more study in order to determine the sources of pollution. I intend to contribute to this on my return. Shrimp fisheries in the Gulf are particularly at risk from pollution arising from activities related to this industry.

The effects of some heavy metals at different stages of food chains are examined. The uptake of Zn or Cd by Australian white wheat, <i>Triticum aestivum</i>, was investigated and this wheat fed to the herbivore, <i>Schistocerca gregaris</i>. The organs of these insects were then examined for accumulation. Accumulation occurred in all organs examined but was higher in the epidermis and mid-gut. <i>Nasonia vitripennis</i> (Hymenoptera) was used as a carnivore. The effects of Zn, Cd, Cu and Hg on the longevity and survival of this insect were examined together with total accumulation at three different temperatures. Metals were more toxic at higher temperatures and the effects of different metals varied. The effects on the ultrastructure of flight muscles were examined, the main effect being a disruption of the mitochondria.

The effect of hydrocarbons, in the form of WSF (water soluble fraction) of North Sea crude oil and naphthalene, upon the respiratory rate and survival of the freshwater isopod, <i>Asellus aquaticus</i> (L.), was examined at different temperatures (10°C and 17°C). The influence of pH and water hardness on the toxicity of the WSF was investigated; it was found to be less toxic in pH 7 and in hard water. <i>Asellus</i> was found to accumulate naphthalene (labelled with <SUP>14</SUP>C) rapidly. The effects of these hydrocarbons on postfertilization development in the Atlantic herring <i>Clupea harengus</i> (L.) were also studied. Artificially fertilized eggs were exposed to different concentrations, the volume of egg, yolk and perivitelline space were measured and the development of the embryos was observed. Exposure to hydrocarbons altered the rates of development, heart beat and embryonic movement; the hatching point was retarded and deformities were observed amongst the resulting larvae. The influeace of naphthalene on the ultra-structure of brain and muscle in <i>C. harengus</i> larvae, hatched from eggs previously exposed to naphthalene, was examined. Electron microscopy revealed cellular changes: many mitochrondria were swollen, their cristae disrupted. The accumulation and distribution of crude oil and naphthalene introduced into adult rainbow trout <i>Salmo gairdneri</i> (Richardson) in their diet, were followed. High concentrations of these hydrocarbons were accumulated in both the gut and the liver of the trout; smaller quantities were found in their gills, kidneys, muscle, heart and brain.