Lysosomal responses to environmental contaminants in bivalves /
These studies were conducted to investigate lysosomal destabilization, a biomarker of cellular damage, in bivalves exposed to environmental contaminants [e.g., polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), organochlorine pesticides, tributyltin (TBT), metals]. In order t...
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
2001.
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| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=726104331&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | These studies were conducted to investigate lysosomal destabilization, a biomarker of cellular damage, in bivalves exposed to environmental contaminants [e.g., polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), organochlorine pesticides, tributyltin (TBT), metals]. In order to test the usefulness of lysosomal destabilization, oysters (Crassostrea virginica) were collected along a contamination gradient in Galveston Bay, Texas. A strong positive correlation (r2 [] 0.78) was observed between lysosomal destabilization and body burden of organic contaminants (PAHs, PCBs, TBT, and chlorinated pesticides) in oysters. Lysosomal destabilization assay was further evaluated as part of the large scale biomonitoring, NOAA's NS&T "Mussel Watch" Project. Comparison of lysosomal destabilization and body burdens of contaminants indicated that lysosomal destabilization was greater than 50% (less healthy) at sites where organic contaminants or metals exceed the "high" concentration (mean + SD) obtained from the NS&T Year 14 Mussel Watch data. Lysosomal destabilization and chemical concentrations showed better correlation when multiple contaminants were considered together. To investigate recovery of destabilized lysosomal function, oysters from a contaminated site were placed in clean aquariums. After 23 days of depuration, lysosomal destabilization returned to background (healthy) levels (34%). The lysosomal recovery is likely related to the decrease of stress caused by PAHs, PCBs, DDTs, and chlordanes, or other contaminants (e.g., metals) in these oysters. The lysosomal destabilization and PAH concentrations in oysters fed PAH-contaminated food showed a positive relationship (r² = 0.89). The results from three aquariums, which were operated under the same condition, indicated good replicability (relative percentage difference < 30 %). Critical body residue of PAHs, in terms of lysosomal destabilization, was found at around 1,400 ng/g, which is 150 - 500 times lower than reported oyster chronic lethal body burdens. Bioconcentration factors had a better linear relationship with membrane-water partition coefficients than with octanol-water partition coefficients. Lysosomal destabilization in bivalves increased with body burdens of contaminants. This indicates that lysosomal membranes are damaged by contaminants and that this method can serve as an early warning tool to assess ecosystem health. When degraded areas are detected with lysosomal destabilization, more expensive chemical analysis can be used to determine possible causative agents. |
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| Item Description: | Vita. "Major Subject: Oceanography". |
| Physical Description: | xii, 179 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilm Inc. |
| Bibliography: | Includes bibliographical references (leaves 126-147). |