Evaluation of polyploidy in the fat body of the adult female mosquito
In order to verify polyploidization of the abdominal fat body tissues in the adult female mosquito, studies were conducted to detect DNA synthesis in this organ. Tissue culture incorporation of tritiated-thymidine showed that labeling of nascent DNA occurred during the first 20 hours post blood meal...
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| Format: | Dissertation |
| Language: | English |
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ProQuest Dissertations & Theses
01-01-2007
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| Online Access: | Get full text |
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| Summary: | In order to verify polyploidization of the abdominal fat body tissues in the adult female mosquito, studies were conducted to detect DNA synthesis in this organ. Tissue culture incorporation of tritiated-thymidine showed that labeling of nascent DNA occurred during the first 20 hours post blood meal, but not between two to three days post blood meal when ploidy levels were expected to increase. Whether in this system the radioactive signal from tritiated-thymidine can become associated with RNA was investigated. This was done by isolating nucleic acids and measuring the effects of RNase or DNase on the recovery of counts per minute (CPM). Because fluctuations of endogenous pools can affect the accuracy of tritiated-thymidine incorporation, two molecular indicators of DNA synthesis were developed. In mammalian systems histone H3 mRNA and ribonucleotide reductase R2 subunit mRNA are known to accumulate to high levels during the S phase of the cell cycle. This study showed that these messages are also S phase specific in synchronized Aedes albopictus C7-10 cells. A probe based on the histone H3 cDNA sequence was hybridized to northern blots of fat body and ovarian tissues. Ovarian nurse cells become polyploid during oogenesis. Histone H3 message was detected in the six to twenty hours post blood meal fat body samples, consistent with the results from tritiated-thymidine incorporation. However the overall level of histone H3 message was much less than what was found in the ovary, suggesting that although some level of DNA synthesis occurs in the vitellogenic fat body, the level is not great enough to support polyploidization of the tissue. Literature on the responses of a number of metabolic indicators to ploidy increases in systems functionally analogous to the mosquito fat body revealed that in the mosquito fat body these metabolic indicators do not respond to ploidy changes. This suggests that ploidy levels in this tissue remain unchanged. |
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| ISBN: | 9780549018711 0549018719 |