No description available.

In the first experiment, sexually immature male and female coho salmon were exposed for 21 days to dietary DDT at a level of 10 or 100 parts per million (ppm), or to methoxychlor at a level of 100 ppm. Exposure to 100 ppm DDT was found to increase the level of liver microsomal Cytochrome P-450 from a control level of 1.32 ± .04 nmoles/1000 mg liver to a level of 1.98 ± .04 nmoles/1000 mg liver, a statistically significant difference (P<.001). None of the treatments were found to affect the hepato-somatic index. In the second experiment, liver slices from sexually maturing male and female coho salmon fed 100 ppm DDT for 21 days or a control diet were incubated with 4-C¹⁴-estradiol-17β in vitro. Metabolites produced were extracted with dichloromethane, separated by thin-layer chromatography and assayed using scintillation counting techniques. Produced in the incubation were estrone, estriol and one other unidentified polar metabolite. DDT treatment was found to significantly increase the amount of estriol and unidentified metabolite produced (P< .001). In the third experiment, sexually maturing male and female coho salmon fed 100 ppm DDT for 21 days or for 7 days or a control diet were injected with 625,500 dpm 4-C¹⁴-estradiol-17β and permitted to metabolize the hormone in vivo. Serial blood samples were extracted, chromatographed and subjected to scintillation counting techniques to obtain values for Metabolic Clearance Rate, Half-life Time and Volumes of Distribution of the injected steroid. It was found that ingestion of DDT had no significant effect upon any of these parameters (P<.001). The pattern of metabolites produced in vivo closely resembled that produced in vitro. The evidence presented in this study suggests that enhancement of the activity of the Mixed Function Oxidase system in coho salmon may occur upon ingestion of an organochlorine insecticide, but that the phenomenon may have little significance in vivo. / Science, Faculty of / Zoology, Department of / Graduate

The fate and transport of insoluble, hydrophobic organic pollutants in the aquatic environment constitutes a prominent area of concern. It is thought that pollutants of this nature may exist in association with organic carbon, which is predominantly aquatic humus. This type of association could significantly affect the kinetics of such transformation processes as volatilization or chemical and biological degradation of the pollutant. While dissolved organic matter (DOM) comprises the bulk of organic carbon (or aquatic humus) in natural waters, the interaction between naturally occurring DOM and insoluble organic pollutants has not been quantified. The work presented in this dissertation is an effort to quantify the effect of dissolved organic matter on the solubility in water and, hence, the transport of hydrophobic organic compounds (specifically, DDT) in the environment. Saturated aqueous solutions of DDT were generated by a method that is different from those used by other workers. Within a closed system, an excess of solid DDT was allowed to vaporize and enter an aqueous solution through the gas phase. The concentration of DDT in solution increased with time, leveling off when equilibrium and a saturated solution was established. The solubility of p,p'-DDT in distilled water was determined to be 1.87 (+OR-) .01 ppb. The solubility of the o,p'-DDT isomer in distilled water was determined to be 4.88 (+OR-) .03 ppb. The concentrations of p,p'-DDT and o,p'-DDT in distilled water solutions containing dissolved organic matter were definitely higher than the aqueous solubilities of these compounds. A minimum value for the DDT/DOM partition coefficient (K(,p)) in water was determined. This partition coefficient, when normalized to organic carbon, is referred to as K(,oc) (K(,oc) = K(,p)/fraction organic carbon). A minimum log K(,oc) for both p,p'-DDT and o,p'-DDT was determined to be 4.7 (+OR-) .2 log units. Under environmental conditions, this partition coefficient indicates that the majority of DDT present in aqueous systems will be associated with dissolved organic matter.

No description available.

No description available.

Three reaction paths (Charts II, III and IV) have been shown for the preparation of the following three compounds which are of interest because they are structurally related to DB2: 9â tri-chlormethylanthracene, 3-chloro-9-â ¢trichlomethylanthracene and 2,7-dichloro·10-trichlomethylanthracene. / Master of Science

published_or_final_version / Community Medicine / Master / Master of Public Health

No description available.

Chan Kam Che. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (leaves 199-219). / Abstracts in English and Chinese. / Acknowledgements --- p.i / Abstracts --- p.iii / 摘要 --- p.v / Contents --- p.vii / List of figures --- p.xiv / List of tables --- p.xix / Abbreviations --- p.xxii / Chapter Chapter I --- Introduction --- p.1 / Chapter 1.1 --- Persistent organic pollutants --- p.1 / Chapter 1.2 --- DDT and DDE --- p.2 / Chapter 1.2.1 --- Background --- p.2 / Chapter 1.2.2 --- Health effects --- p.4 / Chapter 1.2.3 --- Environmental exposure of DDE --- p.4 / Chapter 1.2.4 --- Level of DDE in human --- p.9 / Chapter 1.2.5 --- Biodegradation of DDE --- p.10 / Chapter 1.3 --- Remediation methods --- p.11 / Chapter 1.3.1 --- Physical/ chemical treatment --- p.11 / Chapter 1.3.2 --- Bioremediation --- p.13 / Chapter 1.4 --- Fungal Bioremediation --- p.14 / Chapter 1.5 --- Ligninolytic enzymes --- p.15 / Chapter 1.5.1 --- Laccase --- p.15 / Chapter 1.5.2 --- Peroxidases --- p.20 / Chapter 1.5.2.1 --- Manganese Peroxidase (MnP) --- p.20 / Chapter 1.5.2.1 --- Lignin Peroxidase (LiP) --- p.24 / Chapter 1.6 --- Cultivation of Pleurotus pulmonarius --- p.27 / Chapter 1.7 --- Enzyme technology on environmental cleanup and its limitation --- p.28 / Chapter 1.8 --- Aims and objectives of this study --- p.29 / Chapter Chapter II --- Materials and Methods --- p.30 / Chapter 2.1 --- Organism and growth conditions --- p.30 / Chapter 2.2 --- Cultivation and the expression of the ligninolytic enzyme-coding genes during solid-state-fermentation of edible mushroom Pleurotus pulmonarius --- p.30 / Chapter 2.3 --- Treatment of DDE by living P. pulmonarius --- p.31 / Chapter 2.3.1 --- Optimization of DDE removal in broth system --- p.31 / Chapter 2.3.1.1 --- Effects of initial DDE concentration on the removal of DDE --- p.32 / Chapter 2.3.1.2 --- Effects of inoculum size on the removal of DDE --- p.33 / Chapter 2.3.1.3 --- Effects of incubation time on the removal of DDE and transcriptional profiles of the ligninolytic enzyme-coding genes --- p.33 / Chapter 2.3.2 --- Optimization of DDE removal in soil system --- p.34 / Chapter 2.3.2.1 --- Effects of initial DDE concentration on the removal of DDE --- p.34 / Chapter 2.3.2.2 --- Effects of inoculum size on the removal of DDE --- p.35 / Chapter 2.3.2.3 --- Effects of incubation time on the removal of DDE --- p.35 / Chapter 2.3.2.4 --- Transcription of the ligninolytic enzyme-coding genes --- p.35 / Chapter 2.4 --- Treatment of DDE by 1st SMC of p. pulmonarius grown on straw-based compost --- p.36 / Chapter 2.4.1 --- Optimization of DDE removal in soil system --- p.36 / Chapter 2.5 --- Treatment of DDE by crude enzyme preparations of P. pulmonarius grown on straw-based compost --- p.36 / Chapter 2.5.1 --- Optimization of DDE removal in broth system --- p.36 / Chapter 2.5.1.1 --- Effects of initial DDE concentration on the removal of DDE --- p.37 / Chapter 2.5.1.2 --- Effects of amounts of crude enzyme preparations on the removal of DDE --- p.37 / Chapter 2.5.1.3 --- Effects of incubation time on the removal of DDE --- p.37 / Chapter 2.5.2 --- Optimization of DDE removal in soil system --- p.37 / Chapter 2.5.2.1 --- Effects of initial DDE concentration on the removal of DDE --- p.38 / Chapter 2.5.2.2 --- Effects of amount of crude enzyme preparations on the removal of DDE --- p.38 / Chapter 2.5.2.3 --- Effects of incubation time on the removal of DDE --- p.38 / Chapter 2.6 --- Soil characterization --- p.39 / Chapter 2.6.1 --- Identification of organic contaminants in soil sample from Gene Garden using Gas Chromatography/Mass Spectrometry (GC/MS) --- p.39 / Chapter 2.6.2 --- Determination of soil texture --- p.42 / Chapter 2.6.3 --- Fresh soil/air-dried sample moisture --- p.44 / Chapter 2.6.4 --- "Soil pH, electrical conductivity & salinity" --- p.44 / Chapter 2.6.5 --- Total organic carbon contents --- p.44 / Chapter 2.6.6 --- Total nitrogen and total phosphorus --- p.44 / Chapter 2.6.7 --- Available nitrogen --- p.45 / Chapter 2.6.8 --- Available phosphorus --- p.45 / Chapter 2.6.9 --- Potassium value --- p.46 / Chapter 2.7 --- Quantification of residual DDE level --- p.47 / Chapter 2.7.1 --- Preparation of DDE stock solution --- p.47 / Chapter 2.7.2 --- Extraction and quantification of DDE using Gas Chromatography with Electron Capture Detector (GC/μECD) --- p.47 / Chapter 2.7.3 --- Identification of DDE breakdown products by GC/MS --- p.50 / Chapter 2.8 --- Extraction of protein and ligninolytic enzymes --- p.53 / Chapter 2.8.1 --- Protein assay --- p.53 / Chapter 2.8.2 --- Laccase assay --- p.53 / Chapter 2.8.3 --- Manganese peroxidase assay --- p.54 / Chapter 2.8.4 --- Calculation of activity and specific activity of laccase and manganese peroxidase --- p.54 / Chapter 2.9 --- Estimation of fungal biomass --- p.55 / Chapter 2.9.1 --- Preparation of ergosterol standard solution --- p.56 / Chapter 2.9.2 --- Analysis of ergosterol content --- p.56 / Chapter 2.10 --- Expression of the ligninolytic enzyme-coding genes --- p.58 / Chapter 2.10.1 --- Preparation of ribonuclease free reagents and apparatus --- p.58 / Chapter 2.10.2 --- RNA isolation and purification --- p.58 / Chapter 2.10.3 --- cDNA synthesis --- p.59 / Chapter 2.10.4 --- Semi-quantification of ligninolytic enzyme-coding gene expression by RT-PCR --- p.59 / Chapter 2.11 --- Preparation of crude enzyme preparations from P. pulmonarius compost --- p.63 / Chapter 2.12 --- "Assessment criteria: removal efficiency, RE, and removal capacity, RC" --- p.63 / Chapter 2.13 --- Statistical analysis “ --- p.64 / Chapter Chapter III --- Results --- p.65 / Chapter 3.1 --- Soil characterization --- p.65 / Chapter 3.2 --- Cultivation and the expression of the ligninolytic enzyme-coding genes during solid-state-fermentation of edible mushroom Pleurotus pulmonarius --- p.66 / Chapter 3.2.1 --- Mushroom yield --- p.66 / Chapter 3.2.2 --- Protein content --- p.66 / Chapter 3.2.3 --- Specific ligninolytic enzymes activities --- p.66 / Chapter 3.2.4 --- Ergosterol content --- p.69 / Chapter 3.2.5 --- Ligninolytic enzymes productivities --- p.69 / Chapter 3.2.6 --- Expression of the ligninolytic enzyme-coding genes during solid-state-fermentation --- p.72 / Chapter 3.3 --- Treatment of DDE by living P. pulmonaruis --- p.78 / Chapter 3.3.1 --- Optimization of DDE removal in broth system --- p.78 / Chapter 3.3.1.1 --- Effects of initial DDE concentration on the removal of DDE --- p.78 / Chapter 3.3.1.1.1 --- Effects of DDE on biomass development --- p.78 / Chapter 3.3.1.1.2 --- Protein content --- p.78 / Chapter 3.3.1.1.3 --- Specific ligninolytic enzyme activities --- p.78 / Chapter 3.3.1.1.4 --- Ligninolytic enzyme productivities --- p.79 / Chapter 3.3.1.1.5 --- DDE removal and removal capacity --- p.79 / Chapter 3.3.1.2 --- Effects of inoculum sizes on the removal of DDE --- p.84 / Chapter 3.3.1.2.1 --- Effects of DDE on biomass development --- p.84 / Chapter 3.3.1.2.2 --- Protein content --- p.84 / Chapter 3.3.1.2.3 --- Specific ligninolytic enzyme activities --- p.85 / Chapter 3.3.1.2.4 --- Ligninolytic enzyme productivities --- p.85 / Chapter 3.3.1.2.5 --- DDE removal and removal capacity --- p.85 / Chapter 3.3.1.3 --- Effects of incubation time on the removal of 4.0 mM DDE/g biomass --- p.89 / Chapter 3.3.1.3.1 --- Effects of DDE on biomass development --- p.89 / Chapter 3.3.1.3.2 --- Protein content --- p.89 / Chapter 3.3.1.3.3 --- Specific ligninolytic enzyme activities and ligninolytic enzyme productivities --- p.89 / Chapter 3.3.1.3.4 --- DDE removal and removal capacity --- p.90 / Chapter 3.3.1.3.5 --- Putative degradation derivatives --- p.90 / Chapter 3.3.1.3.6 --- Expression of the ligninolytic enzyme-coding genes during the removal of 4.0 mM DDE/g biomass --- p.94 / Chapter 3.3.1.4 --- Effects of incubation time on the removal of 10.0 mM DDE/g biomass --- p.100 / Chapter 3.3.1.4.1 --- Effects of DDE on biomass development --- p.100 / Chapter 3.3.1.4.2 --- Protein content --- p.100 / Chapter 3.3.1.4.3 --- Specific ligninolytic enzyme activities and ligninolytic enzyme productivities --- p.100 / Chapter 3.3.1.4.4 --- Expression of the ligninolytic enzyme-coding genes during the removal of 10.0 mM DDE/g biomass --- p.102 / Chapter 3.3.2 --- Optimization of DDE removal in soil system --- p.107 / Chapter 3.3.2.1 --- Effects of initial DDE concentration on the removal of DDE --- p.107 / Chapter 3.3.2.1.1 --- Ergosterol content --- p.107 / Chapter 3.3.2.1.2 --- Protein content --- p.107 / Chapter 3.3.2.1.3 --- Specific ligninolytic enzyme activities and ligninolytic enzyme productivities --- p.107 / Chapter 3.3.2.1.4 --- DDE removal and removal capacity --- p.108 / Chapter 3.3.2.2 --- Effects of inoculum sizes on the removal of DDE --- p.111 / Chapter 3.3.2.2.1 --- Ergosterol content --- p.111 / Chapter 3.3.2.2.2 --- Protein content --- p.111 / Chapter 3.3.2.2.3 --- Specific ligninolytic enzyme activities and ligninolytic enzyme productivities --- p.111 / Chapter 3.3.2.2.4 --- DDE removal and removal capacity --- p.112 / Chapter 3.3.2.3 --- Effects of incubation time on the removal of DDE --- p.115 / Chapter 3.3.2.3.1 --- Ergosterol content --- p.115 / Chapter 3.3.2.3.2 --- Protein content --- p.115 / Chapter 3.3.2.3.3 --- Specific ligninolytic enzyme activities and ligninolytic enzyme productivities --- p.115 / Chapter 3.3.2.3.4 --- DDE removal and removal capacity --- p.116 / Chapter 3.3.2.3.5 --- Putative degradation derivatives --- p.116 / Chapter 3.3.2.4 --- Transcription of the ligninolytic enzyme-coding genes --- p.121 / Chapter 3.4 --- Treatment of DDE by 1st SMC of p. pulmonarius grown on straw-based compost --- p.127 / Chapter 3.4.1 --- Optimization of DDE removal in soil system --- p.127 / Chapter 3.4.1.1 --- Effects of initial DDE concentration on the removal of DDE --- p.127 / Chapter 3.4.1.1.1 --- Ergosterol content --- p.127 / Chapter 3.4.1.1.2 --- Protein content --- p.127 / Chapter 3.4.1.1.3 --- Specific ligninolytic enzyme activities and ligninolytic enzyme productivities --- p.127 / Chapter 3.4.1.1.4 --- DDE removal and removal capacity --- p.128 / Chapter 3.4.1.2 --- Effects of inoculum sizes on the removal of DDE --- p.132 / Chapter 3.4.1.2.1 --- Ergosterol content --- p.132 / Chapter 3.4.1.2.2 --- Protein content --- p.132 / Chapter 3.4.1.2.3 --- Specific ligninolytic enzyme activities and ligninolytic enzyme productivities --- p.132 / Chapter 3.4.1.2.4 --- DDE removal and removal capacity --- p.133 / Chapter 3.4.1.3 --- Effects of incubation time on the removal of DDE --- p.136 / Chapter 3.4.1.3.1 --- Ergosterol content --- p.136 / Chapter 3.4.1.3.2 --- Protein content --- p.136 / Chapter 3.4.1.3.3 --- Specific ligninolytic enzyme activities and ligninolytic enzyme productivities --- p.136 / Chapter 3.4.1.3.4 --- DDE removal and removal capacity --- p.137 / Chapter 3.4.1.3.5 --- Putative degradation derivatives --- p.137 / Chapter 3.5 --- Treatment of DDE by crude enzyme preparations of P. pulmonarius grown on straw-based compost --- p.142 / Chapter 3.5.1 --- The crude enzyme preparations of P. pulmonarius grown on straw-based compost --- p.142 / Chapter 3.5.2 --- Optimization of DDE removal in broth system --- p.143 / Chapter 3.5.2.1 --- Effects of initial DDE concentration on the removal of DDE --- p.143 / Chapter 3.5.2.2 --- Effects of amounts of crude enzyme preparations on the removal of DDE --- p.145 / Chapter 3.5.2.3 --- Effects of incubation time on the removal of DDE --- p.147 / Chapter 3.5.2.4 --- Putative degradation derivatives --- p.147 / Chapter 3.5.3 --- Optimization of DDE removal in soil system --- p.151 / Chapter 3.5.3.1 --- Effects of initial DDE concentration on the removal of DDE --- p.151 / Chapter 3.5.3.2 --- Effects of amounts of crude enzyme preparations on the removal of DDE --- p.151 / Chapter 3.5.3.3 --- Effects of incubation time on the removal of DDE --- p.154 / Chapter 3.5.3.4 --- Putative degradation derivatives --- p.154 / Chapter Chapter IV --- Discussions --- p.158 / Chapter 4.1 --- Quantification of the expression of the ligninolytic enzyme-coding genes --- p.158 / Chapter 4.2 --- Artificial cultivation and the expression of the ligninolytic enzyme-coding genes during solid-state-fermentation of edible mushroom Pleurotus pulmonarius --- p.164 / Chapter 4.3 --- Treatment of DDE by living P. pulmonarius --- p.166 / Chapter 4.3.1 --- Optimization of DDE removal in broth system --- p.166 / Chapter 4.3.2 --- Optimization of DDE removal in soil system --- p.169 / Chapter 4.3.3 --- Phylogeny of the ligninolytic enzyme-coding genes --- p.170 / Chapter 4.3.3.1 --- Laccase coding genes --- p.170 / Chapter 4.3.3.2 --- MnP coding genes --- p.175 / Chapter 4.3.4 --- Transcription of the ligninolytic enzyme-coding genes --- p.178 / Chapter 4.4 --- Treatment of DDE by 1st SMC of P. pulmonarius grown on straw-based compost --- p.183 / Chapter 4.4.1 --- Optimization of DDE removal in soil system --- p.183 / Chapter 4.5 --- Treatment of DDE by crude enzyme preparations of P. pulmonarius grown on straw-based compost --- p.184 / Chapter 4.6 --- Cost-effectiveness of the bioremediation method --- p.185 / Chapter 4.7 --- Further investigations --- p.194 / Chapter Chapter V --- Conclusions --- p.197 / References --- p.199

DDT, an extremely widely used organochlorine pesticide, was banned in most developed countries more than 30 years ago. However, DDT residues, including 1,1-dichloro-2,2-bis(4-chlorophenyl)ethylene (DDE), still persist in the environment and have been identified as priority pollutants due to their toxicity and their ability to bioaccumulate and biomagnify in the food chain. In particular, DDE was long believed to be &quotenon-biodegradable&quote, however some microorganisms have now been isolated that are able to metabolise DDE in pure culture. Terrabacter sp. strain DDE-1 was enriched from a DDT-contaminated agricultural soil from the Canterbury plains and is able to metabolise DDE to 4-chlorobenzoic acid when induced with biphenyl. The primary objective of this study was to identify the gene(s) responsible for Terrabacter sp. strain DDE-1�s ability to metabolise DDE and, in particular, to investigate the hypothesis that DDE-1 degrades DDE cometabolically via a biphenyl degradation pathway. Catabolism of biphenyl by strain DDE-1 was demonstrated, and a biphenyl degradation (bph) gene cluster containing bphDA1A2A3A4BCST genes was identified. The bphDA1A2A3A4BC genes are predicted to encode a biphenyl degradation upper pathway for the degradation of biphenyl to benzoate and cis-2-hydroxypenta-2,4-dienoate and the bphST genes are predicted to encode a two-component signal transduction system involved in regulation of biphenyl catabolism. The bph gene cluster was found to be located on a linear plasmid, designated pBPH1. A plasmid-cured strain (MJ-2) was unable to catabolise both biphenyl and DDE, supporting the hypothesis that strain DDE-1 degrades DDE cometabolically via the biphenyl degradation pathway. Furthermore, preliminary evidence from DDE overlayer agar plate assays suggested that Pseudomonas aeruginosa carrying the strain DDE-1 bphA1A2A3A4BC genes is able to catabolise DDE when grown in the presence of biphenyl. A second objective of this study was to characterise pBPH1. The complete 84,054-bp sequence of the plasmid was determined. Annotation of the DNA sequence data revealed seventy-six ORFs predicted to encode proteins, four pseudogenes, and ten gene fragments. Putative functions were assigned to forty-two of the ORF and pseudogenes. Besides biphenyl catabolism, the major functional classes of the predicted proteins were transposition, regulation, heavy metal transport/resistance, and plasmid maintenance and replication. It was shown that pBPH1 has the terminal structural features of an actinomycete invertron, including terminal proteins and terminal inverted repeats (TIRs). This is the first report detailing the nucleotide sequence and characterisation of a (linear) plasmid from the genus Terrabacter.