Biology subjects

Costa-da-Silva, A. L.

Publications and source records attributed to Costa-da-Silva, A. L..

4 recordsLinked to original sources

bioRxiv2024

Global genomics of Aedes aegypti unveils widespread and novel persistent infectious viruses capable of triggering a small RNA response

The mosquito Aedes aegypti is a prominent vector for arboviruses, but the breadth of mosquito viruses that infects this specie is not fully understood. In the broadest global survey to date of over 200 Ae. aegypti small RNA samples, we detected viral small interfering RNAs (siRNAs) and Piwi interacting RNAs (piRNAs) arising from mosquito viruses. We confirmed that most academic laboratory colonies of Ae. aegypti lack persisting viruses, yet two commercial strains were infected by a novel tombus-like virus. Ae. aegypti from North to South American locations were also teeming with multiple insect viruses, with Anphevirus and a bunyavirus displaying geographical boundaries from the viral small RNA patterns. Asian Ae. aegypti small RNA patterns indicate infections by similar mosquito viruses from the Americas and reveal the first wild example of dengue virus infection generating viral small RNAs. African Ae. aegypti also contained various viral small RNAs including novel viruses only found in these African substrains. Intriguingly, viral long RNA patterns can differ from small RNA patterns, indicative of viral transcripts evading the mosquitoes RNA interference (RNAi) machinery. To determine whether the viruses we discovered via small RNA sequencing were replicating and transmissible, we infected C6/36 and Aag2 cells with Ae. aegypti homogenates. Through blind passaging, we generated cell lines stably infected by these mosquito viruses which then generated abundant viral siRNAs and piRNAs that resemble the native mosquito viral small RNA patterns. This mosquito small RNA genomics approach augments surveillance approaches for emerging infectious diseases.

genomics↗

bioRxiv2023

Fertility decline in Aedes mosquitoes is associated with reduced maternal transcript deposition and does not depend on female age

Female mosquitoes undergo multiple rounds of reproduction known as gonotrophic cycles. A gonotrophic cycle spans the period from bloodmeal intake to egg laying. Nutrients from vertebrate host blood are necessary for completing egg development. During oogenesis, a female pre-packages mRNA into her oocytes, and these maternal transcripts drive the first two hours of embryonic development prior to zygotic genome activation. In this study, we profiled transcriptional changes in 1-2 hours old Aedes aegypti embryos across two gonotrophic cycles. We found that homeotic genes which are regulators of embryogenesis are downregulated in embryos from the second gonotrophic cycle. Interestingly, embryos produced by Ae. aegypti females progressively reduced their ability to hatch as the number of gonotrophic cycles increased. We show that this fertility decline is due to increased reproductive output and not the mosquitoes age. Moreover, we found a similar decline in fertility and fecundity across three gonotrophic cycles in Ae. albopictus. Our results are useful for predicting mosquito population dynamics to inform vector control efforts.

developmental biology↗

bioRxiv2023

Fertility decline in female mosquitoes is regulated by the orco olfactory co-receptor

Female Aedes aegypti mosquitoes undergo multiple rounds of reproduction, known as gonotrophic cycles. These cycles span the period from blood meal intake to oviposition. Understanding how reproductive success is maintained across gonotrophic cycles allows for the identification of molecular targets to reduce mosquito population growth. Odorant receptor co-receptor (orco) encodes a conserved insect-specific transmembrane ion channel that complexes with tuning odorant receptors (ORs) to form a functional olfactory receptor. orco expression has been identified in the male and female mosquito germline, but its role is unclear. We report an orco-dependent, maternal effect reduction in fertility after the first gonotrophic cycle. This decline was rescued by repairing the orco mutant locus. Eggs deposited by orco mutant females are fertilized but the embryos reveal developmental defects, reduced hatching, and changes in ion channel signaling gene transcription. We present an unexpected role for an olfactory receptor pathway in mosquito reproduction. HIGHLIGHTSO_LILoss of the orco olfactory co-receptor promotes female mosquito fertility decline. C_LIO_LIAfter their first reproductive cycle completes, Ae. aegypti orco mutant females produce embryos with disrupted development and reduced hatching. C_LIO_LICRISPR/Cas9-mediated repair of the orco mutation rescues the fertility defect. C_LIO_LIGene expression profiling of embryos from orco mutant females supports a role for ion channel signaling in mosquito development. C_LI

genetics↗

bioRxiv2022

Food recognition in a blood-feeding insect: characterization of the pharyngeal taste organ

BackgroundObligate blood-feeding insects obtain the nutrients and water necessary to ensure survival from the vertebrate blood. The internal taste sensilla, situated in the pharynx, evaluate the suitability of the ingested food. Here, through multiple approaches, we characterized the pharyngeal organ (PO) of the hematophagous kissing bug Rhodnius prolixus to determine its role in food assessment. The PO, located antero-dorsally in the pharynx, comprises 8 taste sensilla that become bathed with the incoming blood. ResultsWe showed that these taste sensilla house gustatory receptor neurons projecting their axons through the labral nerves to reach the subesophageal zone in the brain. We found that these neurons are electrically activated by relevant appetitive and aversive gustatory stimuli such as NaCl, ATP and caffeine. Using RNA-Seq, we examined the expression of sensory-related gene families in the PO. We identified gustatory receptors, ionotropic receptors, transient receptor potential channels, pickpocket channels, opsins, takeouts, neuropeptide precursors, neuropeptide receptors and biogenic amine receptors. RNA interference assays demonstrated that the pickpocket channel Rproppk014276 is necessary for salt detection during feeding. ConclusionWe provide evidence of the role of the pharyngeal organ in food evaluation. This work shows the first comprehensive characterization of a pharyngeal taste organ in a hematophagous insect.

neuroscience↗