The mosquito transcriptome is shaped by the individual and interactive effects of warmer temperature and aging

In mosquitoes, warmer temperature accelerates the progression of senescence, weakening their ability to survive and respond to an infection. Thus, we hypothesized that this phenomenon is driven by changes in gene expression. To test this hypothesis, we employed an RNA-sequencing approach to investigate how warmer temperature and aging, individually and interactively, shape the transcriptome of the female African malaria mosquito, Anopheles gambiae. Warmer temperature increases the expression of genes involved in metabolism and cell signaling but decreases the expression of genes involved in replication, transcription, translation, and protein processing. Aging decreases the expression of metabolism-related genes but increases the expression of protein processing and transcriptional genes. However, early and late aging have opposing effects on many biological processes, with 1-day-old mosquitoes having a largely different transcriptomic profile than older mosquitoes. Importantly, warmer temperature and aging interactively shape gene expression patterns, where, for example, aging-dependent changes in immune gene expression accelerate at warmer temperatures. Altogether, warmer temperature and aging, individually and interactively, alter the mosquito’s transcriptomic profile, reflecting changes in their ability to survive and overcome an infection. We set out to investigate how warmer temperature and aging, individually and interactively, shape the transcriptome of naïve and immune-induced mosquitoes. To do so, we reared Anopheles gambiae (Giles sensu stricto) at 27°C, 30°C or 32°C, and allocated adult females that were 1, 5, 10, and 15 days post-eclosion to two immune treatment groups: (i) naïve and (ii) immune induced by intrathoracic injection of heat-killed Escherichia coli. At 6 h post immune treatment we isolated RNA from pools of 15 whole-body female mosquitoes for each temperature-age combination. We completed 5 independent biological trials, resulting in 120 samples derived from 1772 mosquitoes. We then conducted RNA-sequencing and analysis to identify how immune induction, warmer temperature, aging, and the interaction between warmer temperature and aging, alter gene expression profiles.