No description available.

No description available.

published_or_final_version / Biological Sciences / Doctoral / Doctor of Philosophy

Thesis (M.S.)--University of Hawaii at Manoa, 2007. / Includes bibliographical references (leaves 110-136). / xvi, 177 leaves, bound ill., maps 29 cm

published_or_final_version / Biological Sciences / Doctoral / Doctor of Philosophy

M. Tech. Chemistry / Sutherlandia frutescens is a popular indigenous South African medicinal plant which has been identified to re-establish itself on acid rock mine dumps. Medicinal plants such as S. frutescens are harvested from the wild and widely used for primary health care. The primary objective of the study was to determine the effect of soil contamination on the secondary metabolites profile of the plant.

published_or_final_version / Ecology and Biodiversity / Doctoral / Doctor of Philosophy

published_or_final_version / Ecology and Biodiversity / Doctoral / Doctor of Philosophy

Birds are potentially vulnerable to the toxicity of certain environmental pollutants due to limited detoxification capabilities of their liver microsomal cytochrome P450 (CYP) enzymes. In wild birds, ethoxyresorufin O-deethylation (EROD) activity, a marker of CYP1A activity in mammals and domestic chickens, has been used as a biomarker of exposure to polychlorinated biphenyls (PCBs), dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs). The aim of the present study was to investigate hepatic CYP activity as an indication of detoxification capacity in New Zealand birds. In addition to the use of conventional in vitro CYP activity assays, the applicability of a noninvasive CYP activity assay was tested using caffeine as the in vivo substrate. The ontogeny of liver microsomal 3-hydroxylation of quinine, a marker of human CYP3A activity, was investigated in Adelie penguins (Pygoscelis adeliae) from Ross Island, Antarctica. The results indicate that chicks (2-4 weeks old) possess a CYP3A-like isoform(s) as active as but not identical to the CYP3A-like isoform(s) in adults. Total CYP content was low at 2 weeks of age and increased rapidly and linearly approaching adult levels by 4 weeks of age implying a rapid development of CYPs other than the CYP3A-like isoform(s). The main study was conducted on adult (and some post-fledging immature) birds of two native species, the herbivorous paradise shelduck (Tadorna variegata) and the omnivorous southern black-backed gull (Larus dominicanus). Birds were shot for liver collection at three sites in the South Island of New Zealand; West Coast, Lake Waipori and Dunedin landfill, in 2001-2002. The results indicate that shelducks posssess multiple CYP isoforms that independently catalyse EROD, p-nitrophenol hydroxylation (p-NP) and erythromycin demethylation (EMD), markers of mammalian CYP1A, CYP2E and CYP3A activity, respectively. In contrast, gulls appear to possess a single isoform catalysing both EROD and p-NP but possess no isoform capable of catalysing EMD. EROD activity was high in shelducks and gulls from the landfill site, although it was not significantly associated with liver concentrations of PCBs (0.079-6.2 and 8.2-310 ng/g in shelducks and gulls, respectively), PCDD/PCDFs, toxic equivalents (TEQs) and dichlorodiphenyldichloroethylene (DDE) (0.85-317 and 44-4800 ng/g in shelducks and gulls, respectively) in either species. In shelduck livers from the landfill site, EROD was positively associated with Pb concentration but negatively associated with Hg concentration. Assessment of PCB congener patterns based on concentration ratios of individual congeners to the reference congener, 2,2�,4,4�,5,5�-hexachlorobiphenyl (IUPAC #153), indicate that the metabolism of 2,4,4�-trichlorobiphenyl (PCB#28) and 2,4,4�,5-tetrachlorobiphenyl (PCB#74) is inducible in shelducks but not in gulls. Hepatic reduced glutathione (GSH) content was higher in gulls than in shelducks suggesting greater resistance to oxidative stress in gulls. The in vivo caffeine metabolism test as a noninvasive method to determine CYP1A activity in shelducks and gulls gave a positive outcome. The test was performed by administration of a single intraperitoneal dose of caffeine (1 mg/kg body weight) followed by blood collection at 2 and 4 h after caffeine administration for determination of the serum concentration ratio of the metabolite, paraxanthine, to caffeine (PX/CA) by HPLC. In both species, the PX/CA ratio was markedly increased by pretreatment with the model CYP1A inducer, β-naphthoflavone (BNF). BNF treatment also increased EROD activity determined after death (80-fold and 20-fold compared to controls in shelducks and gulls, respectively). However, sensitivity of the PX/CA ratio approach was lower in gulls than in shelducks due presumably to the formation of unidentified caffeine metabolites in gulls. Immunoblot analysis failed to reveal increased CYP protein levels caused by BNF treatment in shelducks and gulls due to poor cross-reactivity of avian proteins with polyclonal antibodies raised against mammalian CYPs. EROD activity was also determined in livers of the piscivorous yellow-eyed penguin (Megadyptes antipodes) (1 chick, 3 post-fledging immature, 1 adult) from Otago, South Island of New Zealand, and found to be below the limit of quantitation. The adult liver contained 18.5 ng/g of total PCBs suggesting that EROD in this species is insensitive to induction. Comparison of the PCB congener pattern based on [PCBx]/[PCB#153] between the penguin and its putative source of PCB exposure, New Zealand marine fish, indicates that CYPs in yellow-eyed penguins metabolise 2,2�,5,5�-tetrachlorobiphenyl (PCB#52) and 2,2�,4,5,5�-pentachlorobiphenyl (PCB#101) as in many other avian species. The findings of this study highlight substantial species differences in CYP activity in wild birds. Whether CYP expression in New Zealand birds is genetically distinct from birds in other parts of the world may warrant further investigation.

Environmental contamination along roadways with lead from processed petroleum and automotive residues has been reported. Toxicity to the herbivores grazing these areas has not been well studied. Comparison of lead concentrations adjacent to roads in Kuwait and in Oregon, USA was studied. Soil samples were taken from three sites at three different distances from the highway (0, 3 and 10 meters) adjacent to King Fahad Highway in Kuwait and Interstate 5 (I-5), Highway 34 (H-34) and Highway 20 (H-20) in Oregon. Soil was analyzed for lead concentrations. The mean lead concentrations in soil samples along King Fahad Highway were significantly higher (p<0.05) than those along 1-5, H-34 and 14-20 in Oregon [4943.6 ppm (mg/kg) vs 129 ppm, 94.9 and 81.67 ppm respectively]. In a field trial animal toxicity studies were conducted on sheep grazing near roadway in Kuwait and also in a controlled barn studies. Fifty lambs ranging in age from 4 to 9 months and grazing on Kuwait pasture adjacent to the King Fahad Highway were tested for blood lead. Levels were determined by Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES). Blood lead levels of these lambs ranged from 0.05-1.00 ppm. Only 12% of the tested population exceeded the blood lead above 0.1 ppm (the high normal value). None demonstrated any clinical signs of lead toxicosis. In addition, a controlled feeding trial was conducted with sheep ingesting similar concentrations of lead as were found along the roadways. These sheep were observed for clinical, gross and histopathological changes. Using the intensive lamb production system common in Kuwait, twenty five lambs ranging in age from 2-10 months were orally fed 0, 2, 4, 8 and 16 mg lead acetate/kg body weight/day in a controlled study. Blood lead levels were tested in these lambs at time zero, week two, and then at monthly intervals until the 14th week. All lambs were slaughtered and necropsied with select tissues analyzed for lead concentrations. Levels of lead in the blood were directly related to the daily administrated lead acetate (P<0.05). Neither gender, age nor breed of the sire had any affect on blood lead levels except for the 14th week where blood lead levels of the young lambs significantly exceeded (P<0.05) those in the older lambs with mean values of 0.54 and 0.34 ppm respectively. In general, lead levels in all the tested tissues were directly related to the amount of the daily oral administration of lead acetate. Differences between the tissue levels of lead in the experimental and control lambs (N=25) were statistically significant (P<0.05) in liver, bone and kidney but were not significant in trachea, testis, brain, diaphragm, ovary, lung, muscle, rumen, aorta, spleen, tongue, eye, intestine, heart and esophagus. Lead accumulation was the highest in bone at the lower ingested lead concentrations, but was the highest in the kidney at higher lead dosages. Lead values were significantly greater (P<0.05) in the livers of female lambs compared to those of the male. Bone, liver and kidney of the young lambs had significantly higher (P<0.05) levels of lead than older lambs with means of 19.24, 7.31 and 54.54 compared to 6.34, 3.59 and 21.31 ppm respectively. Gross lesions were not found in any of the 25 necropsied lambs. Histopathological changes of intranuclear inclusion bodies were found in 100% of the kidneys in lambs administered 8 mg/Kg/day and above and in 50% of the livers of the lambs administered the same dosages. Thirty three per cent of lambs administered 2 and 4 mg/kg/day had intranuclear inclusion bodies in their kidney but not in the liver. The controls had no inclusion bodies in any of these matching tissues. No clinical signs of lead toxicosis were observed in any lambs during the 14 weeks of the experiment. The same lamb population was used to compare blood lead levels and the growth performance of lambs (feed intake, weight gain and feed conversion) in relation to different dosages of lead acetate. Although there was a tendency for lambs ingesting the two higher lead doses to eat less feed, gain less weight; and have a lower feed conversion ratio, these differences were not statistically significant (P>0.05). The conclusion of these studies reveal some concern. Levels of lead as found near the highways of Kuwait were high enough to cause elevated tissue lead concentrations, particularly in liver and kidney, of lambs grazing adjacent to these highways. These levels cause tissue abnormalities in lambs and could be hazardous to human health eating the internal organs of these lambs. / Graduation date: 2000