Project description:In many species, males and females display differences in their physiology that are not limited to the gonads. Sex differences in adult insects can comprise body size and feeding behaviour, as only female, but not male mosquitoes are blood-feeding in order to produce eggs. This is relevant since the malaria-causing parasite Plasmodium is transmitted by a female mosquito through a previous blood meal from an infected individual. The initiation of sex-specific developmental programs can be often linked to heteromorphic sex chromosomes (XX/XY in Anopheles). In males, the X-linked genes are only present in a single copy. To counteract this hemizygosity, Anopheles, like other species, exhibits dosage compensation (DC). Anopheles DC manifests by upregulation of the single male X ensuring the equal expression of sex-chromosomal genes between males and females. To date, the sex-specific differences at the transcriptome level related to the X/Y chromosomes and DC have been characterized at post-embryonic stages. Their onset during embryogenesis, especially during the early stages where the embryo switches from the maternal to the zygotic transcriptome, is largely uncharacterized to date. Here, we generate a sex-specific transcriptome atlas across Anopheles embryogenesis ending at the first larval stage. Along with the transition from the maternal to the zygotic transcriptome, many transcripts switch isoform, where the 3’ untranslated regions (UTR) of zygotic transcripts are significantly extended compared to their maternal counterpart. We also identify stage- and sex-specific splicing events. Comparing male and female embryos, we identify 120 sexually dimorphic protein coding genes and non-coding RNAs, indicating that sexually dimorphic gene expression is not widespread during embryogenesis. Furthermore, the imbalance of X-linked genes between males and females after zygotic genome activation is corrected shortly after, where the majority of genes exhibit DC around 9 hours of embryogenesis with further fine-tuning later in development. Our atlas provides a framework to explore sex differences in development and evolution and thereby, enables future functional analyses of sex-specific expression patterns and isoform usage.
Project description:In the present study, we have investigated the effect of CpG Oligodeoxynucleotides (CpG-ODN) on the outcome of Plasmodium infection of the mosquito vectors Anopheles stephensi and Anopheles gambiae and on the modulation of mosquito immunity to Plasmodium. Anopheles mosquitoes inoculated with CpG-ODN showed significant reduction of Plasmodium infection rate and intensity. Microarrays were used to profile transcription of fat-body from CpG-ODN-treated mosquitoes. Mosquitoes were dissected 18h after ODN inoculation (immediately before feeding). Batches of 20 to 30 fat bodies (abdomen without midgut, ovaries and malpighian tubule]) were dissected in cold DEPC-treated phosphate-buffered saline (PBS) and processed for RNA preparation. Mosquitoes treated with CpG-ODNs are less susceptible to Plasmodium infection. Transcription profile of fat body indicates that protection was associated with coagulation/wound healing, while melanization appears to be depressed.
Project description:With their genome sequenced, Anopheles gambiae mosquitoes now serve as a powerful tool for basic research in comparative, evolutionary and developmental biology. The knowledge generated by these studies is expected to reveal molecular targets for novel vector control and pathogen transmission blocking strategies. Comparisons of gene-expression profiles between adult male and nonblood-fed female Anopheles gambiae mosquitoes revealed that roughly 22% of the genes showed sex-dependent regulation. Blood-fed females switch the majority of their metabolism to blood digestion and egg formation within 3 h after the meal is ingested, in detriment to other activities such as flight and response to environment stimuli. Changes in gene expression are most evident during the first, second and third days after a blood meal, when as many as 50% of all genes showed significant variation in transcript accumulation. After laying the first cluster of eggs (between 72 and 96 h after the blood meal), mosquitoes return to a nongonotrophic stage, similar but not identical to that of 3-dayold nonblood-fed females. Ageing and/or the nutritional state of mosquitoes at 15 days after a blood meal is reflected by the down-regulation of 5% of all genes. A full description of the large number of genes regulated at each analysed time point and each biochemical pathway or biological processes in which they are involved is not possible within the scope of this contribution. Therefore, we present descriptions of groups of genes displaying major differences in transcript accumulation during the adult mosquito life. However, a publicly available searchable database (Anopheles gambiae Gene Expression Database at UC Irvine) has been made available so that detailed analyses of specific groups of genes based on their descriptions, functions or levels of gene expression variation can be performed by interested investigators according to their needs. Keywords: response to bloodmeal
Project description:We profile transcriptome-wide m6A in female and male Anopheles sinensis and reveal that m6A is also a highly conserved modification of mRNA in mosquitoes were generated by deep sequencing, in triplicate, using illumina Novaseq™ 6000. Distinct from mammals and yeast, but similar to Arabidopsis thaliana, m6A in An. sinensis is enriched not only around the stop codon and within 3’-untranslated regions, but also around the start codon and 5’-UTR. Gene ontology analysis indicates that the unique distribution pattern of m6A in An. sinensis is associated with mosquito sex-specific pathways. In addition, the positive correlation between m6A deposition and mRNA abundance indicates that m6A can play roles in regulating gene expression in mosquitoes. Our study proposed a transcriptional regulatory network of m6A in An. sinensis, which may provide a new clue for the control of this disease-transmitting vector.
Project description:Anopheline mosquitoes frequently take multiple blood meals in a single gonotrophic cycle. In this study we determined patterns of gene expression in Anopheles gambiae females blood fed twice within the first gonotrophic cycle.
Project description:Plasmodium parasites within mosquitoes are exposed to various physiological processes, such as blood meal digestion activity, the gonotrophic cycle, and host responses preventing the entry of parasites into the midgut wall. However, when in vitro-cultured ookinetes are injected into the hemocoel of mosquitoes, Plasmodium parasites are not affected by the vertebrate host’s blood contents and do not pass through the midgut epithelial cells. This infection method might aid in identifying mosquito-derived factors affecting Plasmodium development within mosquitoes. This study investigated novel mosquito-derived molecules related to parasite development in Anopheles mosquitoes. We injected in vitro-cultured Plasmodium berghei (ANKA strain) ookinetes into female and male Anopheles stephensi (STE2 strain) mosquitoes and found that the oocyst number was significantly higher in males than in females, suggesting that male mosquitoes better support the development of parasites. Next, RNA-seq analysis was performed on the injected female and male mosquitoes to identify genes exhibiting changes in expression. Five genes with different expression patterns between sexes and greatest expression changes were identified as being potentially associated with Plasmodium infection. Two of the five genes also showed expression changes with infection by blood-feeding, indicating that these genes could affect the development of Plasmodium parasites in mosquitoes.
Project description:We report the use of RNA-seq data to assemble transcriptional units of adult Anopheles funestus female mosquitoes. We also analyzed expression levels and protein divergence and discovered SNPs.
Project description:Small RNAs of the Piwi-interacting RNA class (piRNA) play a key role in controlling the activity of transposable elements (TEs) in the animal germ line. In some arthropod species, including mosquitoes, the vectors of malaria and other pathogens, the piRNA pathway is active not only in the gonads, where it controls TE activity, but also in somatic tissues, where its targets and functions are less clear. It is thought that the piRNA pathway in somatic tissues is involved in the antiviral response and the modulation of TE activity. Here, we studied the features of small RNA production in head and thorax somatic tissues of Anopheles coluzzii focusing on the small RNAs processed from protein-coding gene mRNAs. We revealed tissue and sex specificity in the production of small RNAs derived from the genic transcripts. Genic small RNAs of 24-30 nt in length are atypical RNAs that lack the hallmarks of piRNAs. The majority of these short RNAs are derived from mitochondrial and nuclear genes involved in energy metabolism. We discuss the peculiarities of the piRNA biogenesis in Anopheles species which may result in the production of genic small RNAs in the somatic tissues.
Project description:The Anopheles mosquito is one of thousands of species in which sex differences play a central role in their biology, as only females need a blood meal in order to produce eggs. Sex differentiation is regulated by sex chromosomes, but their presence creates a dosage imbalance between males (XY) and females (XX). Dosage compensation (DC) can re-equilibrate the expression of sex-chromosomal genes, but because DC mechanisms have only been fully characterized in a few model organisms, key questions about its evolutionary diversity and functional necessity remain unresolved. Here we report the discovery of a previously uncharacterized gene (SOA) as a master regulator of DC in the malaria mosquito Anopheles gambiae. Sex-specific alternative splicing prevents functional SOA protein expression in females. The male isoform encodes a DNA-binding protein that binds the promoters of active X chromosomal genes. Expressing male SOA is sufficient to induce DC in female cells. Male mosquitoes lacking SOA or female mosquitos ectopically expressing the male isoform exhibit X chromosome misregulation, which is compatible with viability but causes developmental delay. Thus, our molecular analysis of the first DC master regulator in a non-model organism elucidates the evolutionary steps leading to the establishment of a chromosome-specific fine-tuning mechanism.