Thesis (M.S.)--University of Hawaii at Manoa, 2005. / Includes bibliographical references (leaves 48-50). Also available via World Wide Web.

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.

Thesis (Ph.D.)--University of Adelaide, Dept. of Soil and Water, 2001. / Bibliography: leaves 177-191.

Thesis (M.P.H.)--University of Michigan, 1947.

Thesis (M.P.H.)--University of Michigan, 1947.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1967. / Typescript. Vita. Description based on print version record. Includes bibliographical references (leaves 208-226).

Ph.D. / This study consisted of a two-tiered approach to assessment of the effects of EDCs on aquatic organisms, and heavy metal accumulation in the aquatic environment, by integrating field work and laboratory-based experiments. In the last three decades a considerable portion of research in aquatic health and aquatic toxicology has been largely focused on endocrine disruptors, aiming to establish how certain chemicals discharged into the environment, especially organochlorine pesticides (OCs), polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), surfactants and plasticisers, can mimic endogenous hormones and thereby induce reproductive abnormalities. The rationale behind the present study was the growing interest in the study of endocrine disrupting chemicals (EDCs) internationally and the aspects of this field of research that are relevant to South Africa’s aquatic environment and its endemic aquatic organisms. The field work was carried out in the Rietvlei Wetland System and consisted of a combination of plant root analysis and application of the South African Scoring System 5 (SASS5) macroinvertebrate index. Three characteristic wetland macrophytes used in the study were Typha capensis, Phragmites australis and Persicaria lapathifolia. Samples of plants, sediment and water were taken from predetermined locations along the wetland system in the Rietvlei Nature Reserve and analyzed for heavy metals by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The heavy metals analyzed in this study; lead, arsenic and cadmium, have also been implicated as endocrine disruptors. The results of heavy metal accumulation in the plant roots reflected a pollution trend along the wetland, suggesting that plant roots are useful bioindicators of contamination in freshwater systems.

No description available.

Present sampling techniques are not capable of assessing both contamination with an organochlorine chemical and reproductive success without the need for removing individuals from that population. Experiments were performed to evaluate vitellogenin, vitamin A, and vitamin E as biomarkers of contamination with DDT, an organochlorine pesticide, and reproductive success in Japanese quail (Coturnix coturnix japonica) or northern bobwhites (Colinus virginianus). The utility of vitellogenin as a biomarker in northern bobwhites was investigated. Female northern bobwhites were dosed with 0, 1, 10, or 100 μg DDT/g body weight via corn oil intubation. The females were induced to lay eggs by providing the proper daylength, and number of eggs laid was monitored. No differences were found for number of eggs laid, egg morphology, or plasma concentration of vitellogenin among dose groups. Dietary supplementation and corn oil intubation were evaluated as alternative dosing techniques because handling involved with intubation may have caused decreased egg production in all treatment groups in the first experiment. Nonlaying female bobwhites were dosed with 0 μg DDT, 25 μg DDT/g food, or 25 μg/g body weight (intubation). Bobwhites receiving DDT via intubation accumulated more DDT in brains and livers than did bobwhites receiving DDT via their diet. The two techniques were found not to be equivalent. Vitamins A and E were investigated as biomarkers of DDT contamination and reproductive success in Japanese quail. Female Japanese quail were given 0, 1, 10, or 25 μg dietary DDT. Significant differences were found among dose groups for reproductive success (number of eggs showing embryonic development), and for plasma concentrations of vitamin A. Concentrations of vitamin E were not measurable. Correlation and regression analyses failed to show a relationship between reproduction and vitamin A concentrations. Vitamins A and E also were investigated as biomarkers in northern bobwhites. Female bobwhites were given 0, 1, 10, or 25 ppm dietary DDT. No significant differences were found among dose groups for reproductive success or for concentrations of either vitamin A or vitamin E. Correlation and regression analyses again failed to show any relationship between reproduction and plasma concentrations of vitamins A or E. During each experiment, concentrations of DDT and its metabolites were measured. DDE/DDT ratios in livers, a means of estimating liver enzyme induction, were calculated. The DDE/DDT ratios in livers of Japanese quail and northern bobwhites were found to be markedly different. More work needs to be done to better evaluate the relationship between differences in enzyme induction and reproductive success among different species. / Ph. D.

1. Reciprocal crosses were made between a DDT-resistant and a nonresistant strain of the German cockroach. 2. The techniques employed in rearing the roaches and obtaining toxicological data on the different strains, as well as the genetical and statistical procedures, are described. 3. The toxicological data are presented in the form of regression lines with appropriate statistical analyses. 4. A table showing the relative resistance to DDT of the various strains involved in this study is included. 5. Several conclusions are drawn relative to the inheritance of resistance to DDF in the German cockroach. / Master of Science