Leucine aminopeptidase1 controls egg deposition and hatchability in male Aedes aegypti mosquitoes

The AaFoxA factor regulates female reproduction through chromatin remodeling in the mosquito vector Aedes aegypti

Female mosquitoes are vectors of many devastating human diseases because they require blood feeding to initiate reproduction. Thus, elucidation of molecular mechanisms managing female mosquito reproduction is essential. Although the regulation of gene expression during the mosquito gonadotrophic cycle has been studied in detail, how this process is controlled at the chromatin level remains unclear. Chromatin must be accessible for transcription factors (TFs) governing gene expression. A specialized class of TFs, called pioneer factors (PFs), binds and remodels closed chromatin, permitting other TFs to bind DNA and activate the gene expression. Here, we identified a homolog of the vertebrate PF FoxA in the mosquito Aedes aegypti and used the CRISPR-Cas9 system to generate mosquitoes deficient in AaFoxA. We found that ovary development was severely retarded in mutant females. Multiomics and molecular biology analyses have shown that AaFoxA increased histone acetylation and decreased methylation of H3K27 by controlling the chromatin accessibility of histone modification enzymes and chromatin remodelers. AaFoxA is bound to the loci of chromatin remodelers, changing their chromatin accessibility and modulating their temporal expression patterns. AaFoxA increased the accessibility of the ecdysone receptor (EcR) and E74 loci, indicating the important role of AaFoxA in the hormonal regulation of mosquito reproductive events. Further, the CUT&RUN and ATAC-seq analyses revealed that AaFoxA temporarily bound closed chromatin, making it differentially accessible during the mosquito gonadotrophic cycle. Hence, this study demonstrates that AaFoxA modulates chromatin dynamics throughout female mosquito reproduction.

Mosquito Cell Atlas: A single-nucleus transcriptomic atlas of the adult Aedes aegypti mosquito

The female mosquito's remarkable ability to hunt humans and transmit pathogens relies on her unique biology. Here, we present the Mosquito Cell Atlas (MCA), a comprehensive single-nucleus RNA sequencing dataset of more than 367,000 nuclei from 19 dissected tissues of adult female and male Aedes aegypti, providing cellular-level resolution of mosquito biology. We identify novel cell types and expand our understanding of sensory neuron organization of chemoreceptors to all sensory tissues. Our analysis uncovers male-specific cells and sexually dimorphic gene expression in the antenna and brain. In female mosquitoes, we find that glial cells in the brain, rather than neurons, undergo the most extensive transcriptional changes following blood feeding. Our findings provide insights into the cellular basis of mosquito behavior and sexual dimorphism. The MCA aims to serve as a resource for the vector biology community, enabling systematic investigation of cell-type specific expression across all mosquito tissues.

CRISPR/Cas9-mediated knockout of Tektin 4-like gene (TEKT4L) causes male sterility of Cydia pomonella

The sterile insect technique (SIT) is a well-established and environmentally benign method for population control. Identifying genes that regulate insect fertility while preserving growth and development is crucial for implementing a novel SIT-based pest management approach utilizing CRISPR/Cas9 to target these genes for genetic manipulation. Tektin (TEKT), an essential alpha-helical protein pivotal in sperm formation due to its role in cilia and flagella assembly, has garnered attention. In this study, we identified 7 TEKT genes in the testis of Cydia pomonella, a globally invasive fruit pest. Notably, Tektin4-like (TEKT4L) displayed the highest expression level in male adult especially the testes, suggesting its significance in reproductive processes. By utilizing CRISPR/Cas9 technology to knockout TEKT4L, male sterility was induced, showcasing dominant inherited. When wild-type (WT) females mated with TEKT4L-/- males, eggs laying proceeded normally, but the hatching rate was dramatically reduced, with only 15.49% progressing to the eyespot stage and 68.86% failing to develop normally. The reproductive fitness of TEKT4L-/- males was robust enough to facilitate the transmission of genetic modifications efficiently within the C.pomonella population, yielding a small number of viable offspring. Subsequent cage trials demonstrated the effectiveness of this population in suppressing laboratory populations of C.pomonella, achieving notable results with a relatively low release ratio (TEKT4L-/-♂: WT♂: WT♀ = 5:1:5). Consequently, the targeted disruption of the TEKT4L gene holds promise as a fundamental element in a novel pest control strategy against C. pomonella.

Loss-of-function in testis-specific serine/threonine protein kinase triggers male infertility in an invasive moth

Genetic biocontrol technologies present promising and eco-friendly strategies for the management of pest and insect-transmitted diseases. Although considerable advancements achieve in gene drive applications targeting mosquitoes, endeavors to combat agricultural pests have been somewhat restricted. Here, we identify that the testis-specific serine/threonine kinases (TSSKs) family is uniquely expressed in the testes of Cydia pomonella, a prominent global invasive species. We further generated male moths with disrupted the expression of TSSKs and those with TSSKs disrupted using RNA interference and CRISPR/Cas9 genetic editing techniques, resulting in significant disruptions in spermiogenesis, decreased sperm motility, and hindered development of eggs. Further explorations into the underlying post-transcriptional regulatory mechanisms reveales the involvement of lnc117962 as a competing endogenous RNA (ceRNA) for miR-3960, thereby regulating TSSKs. Notably, orchard trials demonstrates that the release of male strains can effectively suppress population growth. Our findings indicate that targeting TSSKs could serve as a feasible avenue for managing C. pomonella populations, offering significant insights and potential strategies for controlling invasive pests through genetic sterile insect technique (gSIT) technology.

Gut symbiont-derived sphingosine modulates vector competence in Aedes mosquitoes

The main vectors of Zika virus (ZIKV) and dengue virus (DENV) are Aedes aegypti and Ae. albopictus, with Ae. aegypti being more competent. However, the underlying mechanisms remain unclear. Here, we find Ae. albopictus shows comparable vector competence to ZIKV/DENV with Ae. aegypti by blood-feeding after antibiotic treatment or intrathoracic injection. This suggests that midgut microbiota can influence vector competence. Enterobacter hormaechei_B17 (Eh_B17) is isolated from field-collected Ae. albopictus and conferred resistance to ZIKV/DENV infection in Ae. aegypti after gut-transplantation. Sphingosine, a metabolite secreted by Eh_B17, effectively suppresses ZIKV infection in both Ae. aegypti and cell cultures by blocking viral entry during the fusion step, with an IC50 of approximately 10 μM. A field survey reveals that Eh_B17 preferentially colonizes Ae. albopictus compared to Ae. aegypti. And field Ae. albopictus positive for Eh_B17 are more resistant to ZIKV infection. These findings underscore the potential of gut symbiotic bacteria, such as Eh_B17, to modulate the arbovirus vector competence of Aedes mosquitoes. As a natural antiviral agent, Eh_B17 holds promise as a potential candidate for blocking ZIKV/DENV transmission.

Ecdysone-controlled nuclear receptor ERR regulates metabolic homeostasis in the disease vector mosquito Aedes aegypti

Hematophagous mosquitoes require vertebrate blood for their reproductive cycles, making them effective vectors for transmitting dangerous human diseases. Thus, high-intensity metabolism is needed to support reproductive events of female mosquitoes. However, the regulatory mechanism linking metabolism and reproduction in mosquitoes remains largely unclear. In this study, we found that the expression of estrogen-related receptor (ERR), a nuclear receptor, is activated by the direct binding of 20-hydroxyecdysone (20E) and ecdysone receptor (EcR) to the ecdysone response element (EcRE) in the ERR promoter region during the gonadotropic cycle of Aedes aegypti (named AaERR). RNA interference (RNAi) of AaERR in female mosquitoes led to delayed development of ovaries. mRNA abundance of genes encoding key enzymes involved in carbohydrate metabolism (CM)-glucose-6-phosphate isomerase (GPI) and pyruvate kinase (PYK)-was significantly decreased in AaERR knockdown mosquitoes, while the levels of metabolites, such as glycogen, glucose, and trehalose, were elevated. The expression of fatty acid synthase (FAS) was notably downregulated, and lipid accumulation was reduced in response to AaERR depletion. Dual luciferase reporter assays and electrophoretic mobility shift assays (EMSA) determined that AaERR directly activated the expression of metabolic genes, such as GPI, PYK, and FAS, by binding to the corresponding AaERR-responsive motif in the promoter region of these genes. Our results have revealed an important role of AaERR in the regulation of metabolism during mosquito reproduction and offer a novel target for mosquito control.