Digital Gene Expression Profiling reveals transcriptional responses to acute cold stress in Chinese soft-shelled turtle Pelodiscus sinensis juveniles

Turtles are well known for their stress tolerance, including an ability to deal with temperature extremes or rapid thermal change. To know more about the comprehensive molecular basis of thermal stress responses in turtles, we assessed differentially expressed genes (DEGs) in the brain, liver and kidney of juvenile soft-shelled turtles, Pelodiscus sinensis, after acute cold stress (28 °C-8 °C acute transfer and held for 12 h) and following recovery (back to 28 °C and held for 24 h) by digital gene expression profiling. Selected DEGs were also validated via real-time PCR. We found the fewest DEGs in the brain, only one-tenth of the number seen in liver, indicating a tissue-specific gene expression pattern. The DEGs indicated the potential activation of several important functions in response to cold stress and recovery in P. sinensis. This included response to oxidative stress or regulation of reactive oxygen species metabolism in the brain and liver, cerebral inositol metabolism, hepatic monosaccharide metabolism, hepatic complement system, renal DNA repair mechanisms, and TNF and PI3K-Akt signaling pathways in the kidney. These functions likely responded to cold stress in different tissues of P. sinensis to help minimize or repair cell damage as well as enhance innate immunity. The outcomes of this study provide some fundamental insight into the tissue specific complex mechanisms underlining cold stress responses in the soft-shelled turtle P. sinensis.