Cold-induced ependymin expression in zebrafish and carp brain: implications for cold acclimation

Cold acclimation has been suggested to be mediated by alternations in the g ene expression pattern in the cold-adapted fish. To investigate the mechani sm of cold acclimation in fish brain at the molecular level, relevant subse ts of differentially expressed genes of interest were identified and cloned by the PCR-based subtraction suppression hybridization, Characterization o f the selected cold-induced cDNA clones revealed one encoding ependymin, Th is gene was shown to be brain-specific. The expression of ependymin was ind uced by a temperature shift from 25 degrees C to 6 degrees C in Cyprinus ca rpio or 12 degrees C in Danio rerio. Activation of ependymin was detected 2 h after cold exposure and peaked at more than 10-fold at 12 h, This peak l evel remains unchanged until the temperature returns to 25 degrees C. Altho ugh the amount of soluble ependymin protein in brain was not changed by col d treatment, its level in the fibrous insoluble polymers increased 2-fold a fter exposure to low temperature, These findings indicate that the increase in ependymin expression is an early event that may play an important role in the cold acclimation of fish. (C) 1999 Federation of European Biochemica l Societies.