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Following de novo triglyceride dynamics in ovaries of Aedes aegypti during the previtellogenic stage.

ABSTRACT: Understanding the molecular and biochemical basis of egg development is a central topic in mosquito reproductive biology. Lipids are a major source of energy and building blocks for the developing ovarian follicles. Ultra-High Resolution Mass Spectrometry (UHRMS) combined with in vivo metabolic labeling of follicle lipids with deuterated water (²H₂O) can provide unequivocal identification of de novo lipid species during ovarian development. In the present study, we followed de novo triglyceride (TG) dynamics during the ovarian previtellogenic (PVG) stage (2-7 days post-eclosion) of female adult Aedes aegypti. The incorporation of stable isotopes from the diet was evaluated using liquid chromatography (LC) in tandem with the high accuracy (< 0.3 ppm) and high mass resolution (over 1 M) of a 14.5 T Fourier Transform Ion Cyclotron Resonance Mass Spectrometer (14.5 T FT-ICR MS) equipped with hexapolar detection. LC-UHRMS provides effective lipid class separation and chemical formula identification based on the isotopic fine structure. The monitoring of stable isotope incorporation into de novo incorporated TGs suggests that ovarian lipids are consumed or recycled during the PVG stage, with variable time dynamics. These results provide further evidence of the complexity of the molecular mechanism of follicular lipid dynamics during oogenesis in mosquitoes.

SUBMITTER: Tose LV

PROVIDER: S-EPMC8099868 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Juvenile hormone (JH) mediates the relationship between fecundity and nutrition during the gonotrophic cycle of the mosquito in three ways: (1) by regulating initial previtellogenic development, (2) by mediating previtellogenic resorption of follicles and (3) by altering intrinsic previtellogenic follicle "quality", physiology, and competitiveness thereby predetermining the fate of follicles after a blood meal. To support a role for JH in mediating the response of ovarian follicles after a blood meal, we explored three main questions: (1) Do changes in nutrition during the previtellogenic resting stage lead to relevant biochemical and molecular changes in the previtellogenic ovary? (2) Do hormonal manipulations during the previtellogenic resting stage lead to the same biochemical and molecular changes? (3) Does nutrition and hormones during the previtellogenic resting stage affect vitellogenic resorption and reproductive output? We examined the accumulation of neutral lipids in the previtellogenic ovary as well as the previtellogenic expression of genes integral to endocytosis and oocyte development such as the: vitellogenin receptor (AaVgR), lipophorin receptor (AaLpRov), heavy-chain clathrin (AaCHC), and ribosomal protein L32 (rpL32) under various previtellogenic nutritional and hormonal conditions. mRNA abundance and neutral lipid content increased within the previtellogenic ovary as previtellogenic mosquitoes were offered increasing sucrose concentrations. Methoprene application mimicked the effect of offering the highest sucrose concentrations on mRNA abundance and lipid accumulation in the previtellogenic ovary. These same nutritional and hormonal manipulations altered the extent of vitellogenic resorption. Mosquitoes offered 20% sucrose during the previtellogenic resting stage had nearly 3 times less vitellogenic resorption than mosquitoes offered 3% sucrose despite taking smaller blood meals and developed ∼10% more eggs during the first gonotrophic cycle. Mosquitoes treated with JH III during the previtellogenic resting stage and then offered a blood meal had a ∼40% reduction in the amount of vitellogenic resorption and developed ∼12% more eggs. Taken together, these results suggest that previtellogenic nutrition alters the extent and pattern of resorption after a blood meal through the effect of JH on mRNA abundance and lipid accumulation in previtellogenic follicles.

Project description:BackgroundAedes aegypti is the most important global vector of dengue virus infection in humans. Availability of the draft genome sequence of this mosquito provides unique opportunities to study different aspects of its biology, including identification of genes and pathways relevant to the developmental processes associated with transition across individual life stages. However, detailed knowledge of gene expression patterns pertaining to developmental stages of A. aegypti is largely lacking.ResultsWe performed custom cDNA microarray analyses to examine the expression patterns among six developmental stages: early larvae, late larvae, early pupae, late pupae, and adult male and female mosquitoes. Results revealed 1,551 differentially expressed transcripts (DETs) showing significant differences in levels of expression between these life stages. The data suggests that most of the differential expression occurs in a stage specific manner in A. aegypti. Based on hierarchical clustering of expression levels, correlated expression patterns of DETs were also observed among developmental stages. Weighted gene correlation network analysis revealed modular patterns of expression among the DETs. We observed that hydrolase activity, membrane, integral to membrane, DNA binding, translation, ribosome, nucleoside-triphosphatase activity, structural constituent of ribosome, ribonucleoprotein complex and receptor activity were among the top ten ranked GO (Gene Ontology) terms associated with DETs. Significant associations of DETs were also observed with specific KEGG (Kyoto Encyclopedia of Genes and Genomes) pathway modules. Finally, comparisons with the previously reported developmental transcriptome of the malaria vector, Anopheles gambiae, indicated that gene expression patterns during developmental processes reflect both species-specific as well as common components of the two mosquito species.ConclusionsOur study shows that genes involved in the developmental life cycle of A. aegypti are expressed in a highly stage-specific manner. This suggests that transcriptional events associated with transition through larval, pupal and adult stages are largely discrete.

Project description:BackgroundTransmission of pathogens by vector mosquitoes is intrinsically linked with mosquito's reproductive strategy because anautogenous mosquitoes require vertebrate blood to develop a batch of eggs. Each cycle of egg maturation is tightly linked with the intake of a fresh blood meal for most species. Mosquitoes that acquire pathogens during the first blood feeding can transmit the pathogens to susceptible hosts during subsequent blood feeding and also vertically to the next generation via infected eggs. Large-scale gene-expression changes occur following each blood meal in various tissues, including ovaries. Here we analyzed mosquito ovary transcriptome following a blood meal at three different time points to investigate blood-meal induced changes in gene expression in mosquito ovaries.ResultsWe collected ovaries from Aedes aegypti that received a sugar meal or a blood meal on days 3, 10 and 20 post blood meal for transcriptome analysis. Over 4000 genes responded differentially following ingestion of a blood meal on day 3, and 660 and 780 genes on days 10 and 20, respectively. Proteins encoded by differentially expressed genes (DEGs) on day 3 include odorant binding proteins (OBPs), defense-specific proteins, and cytochrome P450 detoxification enzymes. In addition, we identified 580 long non-coding RNAs that are differentially expressed at three time points. Gene ontology analysis indicated that genes involved in peptidase activity, oxidoreductase activity, extracellular space, and hydrolase activity, among others were enriched on day 3. Although most of the DEGs returned to the nonsignificant level compared to the sugar-fed mosquito ovaries following oviposition on days 10 and 20, there remained differences in the gene expression pattern in sugar-fed and blood-fed mosquitoes.ConclusionsEnrichment of OBPs following blood meal ingestion suggests that these genes may have other functions besides being part of the olfactory system. The enrichment of immune-specific genes and cytochrome P450 genes indicates that ovaries become well prepared to protect their germ line from any pathogens that may accompany the blood meal or from environmental contamination during oviposition, and to deal with the detrimental effects of toxic metabolites.

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Following de novo triglyceride dynamics in ovaries of Aedes aegypti during the previtellogenic stage.

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