In vitro studies on mechanisms of Organophosphate resistance in Boophilus microplus /
Organophosphate (OP) resistant Boophilus microplus VII-SCC cell lines were generated by exposing the cells to increasing concentration of Coumaphos. The cells were denominated C34, C44 and C54 with the number indicating the maximum dose of pesticide to which each was exposed. C44 and C54 presented...
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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=728908881&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | Organophosphate (OP) resistant Boophilus microplus VII-SCC cell lines were generated by exposing the cells to increasing concentration of Coumaphos. The cells were denominated C34, C44 and C54 with the number indicating the maximum dose of pesticide to which each was exposed. C44 and C54 presented a slower duplication rate and higher levels of esterase B, after exposure to the pesticide, than C34 and untreated and DMSO-treated cells used as controls. Alterations in cellular homeostasis were evaluated by fluorescent cytometric microplate assays. An increased in GSH content and esterases levels were found in the resistant cell lines when compared to controls. The differences found in glutathione S-transferase activity, intracellular Ca²⁺ and mitochondrial membrane potential were found to coincide with the levels of resistance of the cell line. Differential gene expression was evaluated in C34 OP resistant cell and nonresistant B. microplus cell lines. Different cDNA were differentially expressed between the cells and an A72 sequence was identified that is overexpressed in the resistant compared to the nonresistant cell line. However, its identification or its relationship to the development of Coumaphos resistance has yet to be determined. Cytochrome P450 and glutathione peroxidase genes were compared between OP resistant cell line C34 and nonresistant cells. The deduced amino acid sequence of the tick cell cytochrome P450 genes showed five differences compared to the reported CYP4W1 B. microplus sequence. Two of these differences may be important for the structure of the protein. An amino acid substitution was found in the Coumaphos resistant B. microplus cytochrome P450 CYP4W1 when compared to the nonresistant cells and the reported B. microplus cytochrome P450 CYP4W1. No differences were found in the glutathione peroxidase genes from the two tick cell lines. This study also documents the first report of a glutathione peroxidase gene identified in B. microplus. |
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| Item Description: | Vita. "Major Subject: Veterinary Microbiology". |
| Physical Description: | xi, 116 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilm Inc. |
| Bibliography: | Includes bibliographical references (leaves 105-115). |