In temperate zones, dynamic temperature changes occur with seasonal changes. For ectotherms, including fish, temperature is an environmental factor that strongly influences basic life functions, so it is important for them to adapt to seasonal temperature changes. However, much of the molecular basis of seasonal temperature adaptation in fish remains a mystery.
To understand the mechanism of seasonal temperature adaptation in fish, we performed genome-wide expression analysis using medaka (Oryzias latipes) as a model. Medaka kept under 26°C were transferred to 8°C, and RNA-seq analysis was performed using time-series samples of five tissues: brain, liver, heart, gill, and muscle. Using these time-series data, genes responsive to low temperature were extracted, and found that the expression of several thousand genes varied in each tissue (referred to as “cold-responsive genes”). Next, a network analysis was conducted to identify transcription factors that are important in regulating the expression of cold -responsive genes, and candidates for hub transcription factors, which are central to the network, were extracted in each tissue. These results suggest that these transcription factors may be involved in low-temperature adaptation through the regulation of cold-responsive gene expression. We are currently conducting functional analysis of these transcription factors using genome editing technology.