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| Author(s): |
Caroline Louise Garcia Mendes
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Instituto de Medicina Tropical de São Paulo (IMT) |
| Defense date: | 2017-05-22 |
| Examining board members: |
Lincoln Suesdek Rocha;
Camila Malta Romano;
Aparecida Sadae Tanaka
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| Advisor: | Lincoln Suesdek Rocha |
| Abstract | |
Laccase 2 is a gene with major role in body cuticle tanning in insects and evidences suggest laccase 2 may play a role in egg chorion tanning in mosquitoes vectors of pathogens. When the expression of the gene is knocked down in adults of Aedes albopictus their females produce hyaline and inviable eggs. Theoretically, this gene would be a good candidate for manipulation in the context of biological control of vectors based on genetically modified organisms. In the present study, we characterized the expressional profile and enzymatic activity of laccase 2 during the development of Aedes aegypti. We also knocked down the gene in adult females hypothesizing that this could jeopardize egg chorion formation. The RT-PCR technique was not sensitive to detect laccase 2 amplification in larvae, however, we detected amplification in other life stages. Pupae and adults females after blood meal exhibited equivalent expressional profiles. Using the technique of enzymatic activity detection by fluorescence, it was possible to determine the laccase 2 enzymatic activity profile and the optimum pH in all stages of development. The highest activity peak was registered in adult females 32 hours after blood meal. The laccase 2 enzymatic activity was confirmed by chromatographic separation in the adults females 24 hours after blood meal sample. Both techniques (RT-PCR and enzymatic activity detection) point to a higher production of laccase 2 after blood meal in adult females, suggesting the importance of laccase 2 for egg development. For the knocking down experiments we synthesized double-stranded RNA of laccase 2 and protein MSP1 (negative control). Both double-stranded RNAs were injected at three concentrations, 20ng, 200ng and 1700ng, in three experimental groups of Ae. aegypti females. No significant morphological differences between eggs from females injected with laccase 2 and MSP1 double-stranded RNA were observed. Pigmentation of the eggs started 30 minutes after they were laid (experimental and control group). However, the pigmentation started slightly later in those eggs of experiment females injected with 200ng. This apparent developmental delay may be related to the silencing of laccase 2. The effect of insertion of double-stranded RNA of laccase 2 did not result in the same effect reported in the literature for Ae. albopictus. Even so, the results obtained in this study corroborate the hypothesis that laccase 2 plays a role in egg development in mosquitoes. (AU) | |
| FAPESP's process: | 13/26017-7 - Expressional characterization of laccase 2 in Aedes aegypti |
| Grantee: | Caroline Louise Garcia Mendes |
| Support Opportunities: | Scholarships in Brazil - Master |