Regulation of the antennal transcriptome of the dengue vector, Aedes aegypti, during the first gonotrophic cycle

Abstract

Background: In the light of dengue being the fastest growing transmissible disease, there is a dire need to identify the mechanisms regulating the behaviour of the main vector Aedes aegypti. Disease transmission requires the female mosquito to acquire the pathogen from a blood meal during one gonotrophic cycle, and to pass it on in the next, and the capacity of the vector to maintain the disease relies on a sustained mosquito population.

Results: Using a comprehensive transcriptomic approach, we provide insight into the regulation of the odour-mediated host- and oviposition-seeking behaviours throughout the first gonotrophic cycle. We provide clear evidence that the age and state of the female affects antennal transcription differentially. Notably, the temporal- and state-dependent patterns of differential transcript abundance of chemosensory and neuromodulatory genes extends across families, and appears to be linked to concerted differential modulation by subsets of transcription factors.

Conclusions: By identifying these regulatory pathways, we provide a substrate for future studies targeting subsets of genes across disparate families involved in generating key vector behaviours, with the goal to develop novel vector control tools.

Keywords: Chemosensory-related genes; Mosquito, Olfaction; Neuromodulatory genes; Ontogeny; Transcription factors.

Fig. 1

Schematic representation of the gonotrophic cycle of Aedes aegypti females. After adult maturation, non-blood fed mosquitoes share their time amongst floral seeking [6, 7], host seeking [–10] and resting ([6] and refs therein) (top panel). Following a complete blood meal at 5 days post-emergence (dpe), the host seeking behaviour is inhibited until egg-laying [–13], while floral seeking is inhibited for up to 48 h [7, 13], when pre-oviposition behaviours commence [14] (bottom panel). Most females have oviposited within 100 h post-blood meal (pbm) [15]

Fig. 2

Age-dependent antennal transcript abundance. a Principal component analysis of the antennal transcriptomes of 5 to 10 days post-emergence (dpe) female Aedes aegypti. Ages are denoted by a gradient of green hues, with the lightest being 5 dpe and the darkest being 10 dpe. The total number of genes with differentially abundant transcripts from comparisons between b each age group and 5 dpe, and c adjacent ages of host-seeking adult female Ae. aegypti can be determined by the sum of those with gene ontology (GO) annotation (white) and those without (green). d-e Proportions of genes with differentially abundant transcripts in the antennae of 5 to 10 dpe host-seeking adult female Ae. aegypti classified by a level 3 molecular function gene ontology. Comparisons are made between each age group and 5 dpe (d), and adjacent age groups (e). The legend indicates the GO terms representing ≥2% of the total differentially abundant transcripts in at least one pairwise comparison

Fig. 3

Age- and state-dependent antennal transcript abundance. a Principal component analysis of the antennal transcriptomes of non-blood fed (nbf; circles) and blood fed (bf; squares) female Aedes aegypti, 5 to 10 days post-emergence (dpe). Females were blood fed 5 dpe and the time is represented as hours post-blood meal (pbm). Ages are denoted by a gradient of green hues, with the lightest being 5 dpe and the darkest being 10 dpe. Inset: The area bordered by dotted grey lines is expanded for disambiguation. Three replicates of each antennal transcriptome for nbf and bf are depicted for each age. b Total number of genes with differentially abundant transcripts between the antennal transcriptomes of nbf and bf from 5 to 10 dpe adult female Ae. aegypti can be determined by the sum of those with gene ontology (GO) annotation (white) and those without (green). c Proportions of genes with differentially abundant transcripts in the antennae of age-matched host-seeking (nbf) and blood-fed (h pbm) adult female Ae. aegypti between 5 to 10 days post-emergence (dpe) were classified by a level 3 molecular function GO. The legend indicates the GO terms representing ≥2% of the total differentially abundant transcripts in at least one pairwise comparison

Fig. 4

Concerted age- and state-dependent antennal gene regulation spanning gene families. Two regulation motifs (a and b) are demonstrated by the transcript abundance in 5 to 10 days post-emergence (dpe) non-blood fed (nbf; green; left) and age-matched blood fed (bf; brown; middle) Aedes aegypti female antennae. Comparisons between nbf (black) and age-matched bf (blue) antennal transcript abundance are described by fold change (right). Permanent gene identifiers along with the common gene names are to the left. Ball and stick diagrams represent the general trend in abundance demonstrated by this gene family (a motif 1, top right; b motif 2, top right). Asterisks between two age groups denote stringent significant difference (> 2-fold change; FDR P < 0.05). Asterisks to the far right of each table indicate significant differences between 5 and 10 dpe.  a These genes demonstrate a motif 1 pattern of transcript regulation, while b are those that demonstrate motif 2