RNA-Seq reveals early distinctions and late convergence of gene expression between diapause and quiescence in the Asian tiger mosquito,Aedes albopictus

Abstract

SUMMARYDormancy is a crucial adaptation allowing insects to withstand harsh environmental conditions. The pre-programmed developmental arrest of diapause is a form of dormancy that is distinct from quiescence, in which development arrests in immediate response to hardship. Much progress has been made in understanding the environmental and hormonal controls of diapause. However, studies identifying transcriptional changes unique to diapause, rather than quiescence, are lacking, making it difficult to disentangle the transcriptional profiles of diapause from dormancy in general. The Asian tiger mosquito, Aedes albopictus, presents an ideal model for such a study, as diapausing and quiescent eggs can be staged and collected for global gene expression profiling using a newly developed transcriptome. Here, we use RNA-Seq to contrast gene expression during diapause with quiescence to identify transcriptional changes specific to the diapause response. We identify global trends in gene expression that show gradual convergence of diapause gene expression upon gene expression during quiescence. Functionally, early diapause A. albopictus show strong expression differences of genes involved in metabolism, which diminish over time. Of these, only expression of lipid metabolism genes remained distinct in late diapause. We identify several genes putatively related to hormonal control of development that are persistently differentially expressed throughout diapause, suggesting these might be involved in the maintenance of diapause. Our results identify key biological differences between diapausing and quiescent pharate larvae, and suggest candidate pathways for studying metabolism and the hormonal control of development during diapause in other species. Supplementary material available online at

Genome sequence of the Asian Tiger mosquito,Aedes albopictus, reveals insights into its biology, genetics, and evolution

“…The Foshan strain was not tested for a diapause response. However, our analysis addresses regions of the genome that have been demonstrated to be expressed differentially as part of the diapause program in temperate, fully diapause-capable populations based on extensive previously published RNA-seq studies (27)(28)(29)(30). A total of 71 genes with a putative diapause function were annotated based on these previous studies (Dataset S9).…”

“…Lipid metabolism also was implicated previously as an important transcriptional component of the diapause program in Ae. albopictus, and gene expression regulation is implicated as an important component of diapause-based extensive differential transcript accumulation (>5,000 genes represented) under diapause and nondiapause conditions (27)(28)(29)(30). The role of contrasting differential transcript accumulation for serine protease genes across the life cycle remains unclear.…”

“…Finally, the RNA transcripts were integrated with the GLEAN gene set to form the final nonredundant gene set. Manual annotation of putative diapause-related genes was performed by using Web Apollo (80) to integrate the original GLEAN/Cuff annotations on the scaffolds with Maker annotations (81) based on a comprehensive diapause transcriptome (27)(28)(29)(30). Annotated genes included those involved in chromatin remodeling, lipid metabolism, hormonal regulation, circadian rhythms, and other functions.…”

Photoperiodic Diapause and the Establishment ofAedes albopictus(Diptera: Culicidae) in North America

“…Experimental design of RNAseq studies to identify the transcriptional basis of diapause in Ae. albopictus during the stages of diapause induction, preparation, and developmental arrest (Huang et al 2015;Poelchau et al 2011Poelchau et al , 2013aPoelchau et al , 2013b. The transcriptomes of mosquitoes reared under diapause-inducing and nondiapause inducing photoperiods are compared at different developmental stages (adult females, stage V oocytes, embryos 72-78 h post oviposition, embryos 135-141 h post oviposition, and eggs 11, 21, and 40 d post oviposition).…”

“…However, this differential expression dissipates over time so that by 40 d pov, when many eggs are susceptible to a hatching stimulus, relatively few genes are differentially expressed (Poelchau et al 2013b). Thus, at the transcriptional level, diapause appears to dissipate over time, gradually converging on the nondiapause (quiescent) state.…”