Summary
A bioRxiv preprint reanalysed 115 whole-body RNA-sequencing libraries from female Anopheles gambiae kept at 27, 30 or 32°C. A gene-expression clock estimated warmer mosquitoes as older, but its age offset stopped widening after day five.
A bioRxiv preprint reports that warmer conditions shifted the gene-expression profile of female Anopheles gambiae mosquitoes towards an older state, without making that molecular age gap keep growing faster over time. The researchers reanalysed 115 whole-body RNA-sequencing libraries from mosquitoes kept at 27, 30 or 32°C and sampled between 1 and 15 days after emergence.
The result distinguishes two ways temperature could affect an ageing clock: by making it run faster, or by moving its reading forward while leaving its pace broadly unchanged. The study measures transcriptomic age—a molecular estimate based on gene activity—not lifespan or malaria transmission.
A clock trained on mosquitoes at 27°C
The researchers trained a transcriptomic clock using mosquitoes kept at 27°C. Its reported prediction error was ±0.9 days. When applied to mosquitoes kept at warmer temperatures, the clock read those at 30°C as 1.1 days older and those at 32°C as 2.4 days older than their chronological age. For the 32°C group, the reported 95% confidence interval was 1.9 to 2.9 days.
If warmth had accelerated the clock, the difference between its reading and chronological age would be expected to keep widening. Instead, the gap opened by day five and then largely levelled off. Between days 5 and 15, the estimated additional increase was 0.01 days per day, with a 95% confidence interval from -0.16 to 0.19. The researchers contrasted this with 0.29 to 0.45 days per day expected under a faster-running clock.
Different gene groups shifted in different ways
The temperature response was not a uniform change across genes. Genes whose activity normally changes late in life—including genes associated with melanisation and digestion—shifted towards an older profile. Genes associated with early maturation moved in the opposite direction. Many responses changed course around 30°C; immune-related genes, for example, held until that temperature before falling.
Together, the clock and gene-level results suggest that warmth changes the age-like state captured by whole-body gene expression, rather than steadily accelerating its progression across the measured period. Because this is a preprint analysing transcriptomic data, its reported outcome is a molecular age profile; the source does not report mosquito lifespan or malaria-transmission outcomes.