Skin transcriptome profiling reveals the distinctive molecular effects of temperature changes on Antarctic bullhead notothen

Backgrounds: Temperature is an important abiotic factor that directly influences the physiology of marine fish. The Antarctic bullhead notothen Notothenia coriiceps inhabits water with temperatures ranging from -1.9 to 2 degrees C at circumpolar regions. Thus, N. coriiceps is useful as a model animal for understanding the effects of temperature stress. Methods: To assess the transcriptional response of skin tissue to temperature changes, Antarctic bullhead notothen were exposed to two temperature stresses, 4 degrees C and -2 degrees C, following acclimatization at 2 degrees C. Twenty-four hours after the temperature change, skin transcriptomes were sequenced using the Illumina Hiseq 2000 platform and analyzed using a series of bioinformatics tools. Functional gene annotations through pathway analyses of the Gene Ontology and Kyoto Encyclopedia of Genes and Genomes databases revealed commonly or distinctively modulated transcriptional changes in skin. Results: Both temperature stressors significantly upregulated the actin cytoskeleton regulation pathway and the skin's water barrier function, while the stressors downregulated the metabolism involved in muscle contraction, choline receptor regulation, collagen regulation, and immunity. Cold stress caused significant downregulation of the mRNA expression of genes involved in vasopressin-regulated water reabsorption. Neither the heat- nor cold-stressed skin transcriptomes exhibited significant heat shock protein expression. Conclusion: Our results suggest that, as a first barrier for fish, the skin has complex metabolisms with high transcriptional sensitivity against environmental temperature stress. These results will be useful for understanding the skin-specific molecular mechanisms that Antarctic fish use to adapt to temperature fluctuations.