Project description:In spite of the many recent developments in the field of vector sialomics, the salivary glands of larvalmosquitoes have been largely unexplored. We used whole-transcriptome microarray analysis to create a gene-expression profile of the salivary gland tissue of fourth-instar Anopheles gambiae larvae, and compare it to the gene-expression profile of a matching group of whole larvae. We identified a total of 221 probes with expression values that were (a) significantly enriched in the salivary glands, and (b)sufficiently annotated as to allow the prediction of the presence/absence of signal peptides in their corresponding gene products. Based on available annotation of the protein sequences associated with these probes, we propose that the main roles of larval salivary secretions include: (a) immune response, (b) mouthpart lubrication, (c) nutrient metabolism, and (d) xenobiotic detoxification. Other highlights of the study include the cloning of a transcript encoding a previously unknown salivary defensin (AgDef5), the confirmation of mucus secretion by the larval salivary glands, and the first report of salivary lipocalins in the Culicidae. Keywords: Anopheles gambiae, salivary gland, Diptera, gene expression, salivary defensin, transcriptome, salivary lipocalin
Project description:In Sub-Saharan Africa, Anopheles gambiae Giles (Diptera: Culicidae) largely contributes to malaria transmission, in direct relation to environmental conditions influencing the vector ecology. Therefore, our study aimed to compare the proteomes of An. gambiae according to varying insecticide pressures associated to cotton crops also integrating different population origins from two climatic regions of Burkina Faso.
Project description:Although the salivary transcriptome of adult mosquitoes has been thoroughly described in several recent papers, very little information exists regarding the biological role of larval salivary glands in the Culicidae. We used whole-transcriptome Affymetrix® chips to compare the transcriptional profiles of Anopheles gambiae larval (L4) salivary glands and whole larvae. We identified a total of 277 transcripts as being significantly enriched in the salivary glands. Based on available annotation for the known or predicted protein sequences encoded by these transcripts, 41 were identified as corresponding to secreted proteins, 233 as corresponding to non-secreted (housekeeping) proteins, and 3 as encoding proteins of unknown function. Based on functional annotation of the putatively secreted gene products, we propose that larval salivary secretions have roles in nutrient digestion, detoxification, immunity, and mouthpart lubrication. Interestingly, several components of the larval saliva (e.g. apyrase and serine proteases) have also been reported to exist in adult female saliva, where they are though to help regulate a vertebrate hostâs immune response to bloodfeeding. In conclusion, our results suggest that the salivary glands are important components of both the digestive and immune systems of larval mosquitoes, and that their study might provide clues about the evolution of adaptations to bloodfeeding observed in adults. Experiment Overall Design: We attempted to identify transcripts that are both present and significantly enriched in the salivary glands (SG) of the 4th instar Anopheles gambiae larva. Transcripts were considered as present in the SG if the built-in Affymetrix detection call scored them as such in all three biological replicates of the experiment. Expression values (i.e. signal intensities) of transcripts from the salivary glands were compared to those of a matching group of whole 4th instar larvae using a t-test. Transcripts showing an expression value two-fold or higher (p < 0.01; false discovery rate=1%) in the SG as compared to whole larvae were considered to be significantly enriched.
Project description:Proteomic analysis of Anopheles gambiae brain tissue after in-gel trypsin digestion. To gain insights into neurobiology of the Anopheles gambiae mosquito, we carried out a proteomic analysis of its brain using a comprehensive proteomic approach.
Project description:Although the basic anatomical sub-divisions of the larval mosquito gut were established several decades ago, information regarding their exact physiological roles is rather scarce. Several studies have reported differences between larval gut compartments in various morphological and physiological aspects. Unfortunately, the fragmentary and incomplete nature of this information makes it hard to establish clear links to the specific and/or unique physiological roles of each gut region. In this study, we attempted to identify transcripts significantly enriched in each gut section of the 4th instar Anopheles gambiae larva. We took advantage of a commercially-available microarray platform containing ~14,000 different An. gambiae transcripts (Affymetrix GeneChip® Plasmodium/Anopheles array, Affymetrix Inc., Santa Clara, CA). Based on the information obtained, we discuss the putative physiological roles of each major compartment of the larval gut, and identify potential new targets for larval control strategies. Experiment Overall Design: We attempted to identify transcripts significantly enriched in each gut section of the 4th instar Anopheles gambiae larva. Signal intensities of transcripts from each gut section were compared to those of a matching group of whole 4th instar larvae using t-tests. Transcripts showing an intensity value two-fold or higher (p < 0.05) in each gut section as compared to whole larvae were considered to be significantly enriched.
Project description:we report the RNA-seq based analyses of the transcriptional changes in the Anopheles gambiae mosquitoes from East Africa classified as deltamethrin-resistant or -suscpetible accordign the WHO test
Project description:We custom-built a bioinformatics pipeline to search for 20E-modifying enzymes in the accessory glands of Anopheles gambiae males, searching for ecdysteroid kinases (EcK), ecdysone oxidases (EO), and ecdysteroid-phosphate phosphatases (EPP). To this end, we generated RNAseq datasets of different An. gambiae tissues dissected from virgin and mated females and males, and produced similar datasets for Anopheles albimanus, a South American species that does not synthetize and transfer ecdysteroids during mating. These analyses led to the identification of one candidate EPP and two potential EcKs (EcK1 and EcK2), which we demonstrated are involved in the activity of a male-specific oxidized ecdysteroid (3D20E). We further determined that 3D20E is specifically produced by the An. gambiae male accessory glands and is transferred to females during copulation, where it triggers a series of post-mating responses.
Project description:Background: The Anopheles gambiae salivary glands play a major role in malaria transmission and express a variety of bioactive components that facilitate blood-feeding by preventing platelet aggregation, blood clotting, vasodilatation, and inflammatory and other reactions at the probing site on the vertebrate host. Results: We have performed a global transcriptome analysis of the A. gambiae salivary gland response to blood-feeding, to identify candidate genes that are involved in hematophagy. A total of 4,978 genes were found to be transcribed in this tissue. A comparison of salivary gland transcriptomes prior to and after blood-feeding identified 52 and 41 transcripts that were significantly up-regulated and down-regulated, respectively. Ten genes were further selected to assess their role in the blood-feeding process using RNAi-mediated gene silencing methodology. Depletion of the salivary gland genes encoding D7L2, anophelin, peroxidase, the SG2 precursor, and a 5'nucleotidase gene significantly increased probing time of A. gambiae mosquitoes and thereby their capacity to blood-feed. Conclusions: The salivary gland transcriptome comprises approximately 38% of the total mosquito transcriptome and a small proportion of it is dynamically changing already at two hours in response to blood feeding. A better understanding of the salivary gland transcriptome and its function can contribute to the development of pathogen transmission control strategies and the identification of medically relevant bioactive compounds.