Temperature-dependent enhancement of cell proliferation and mRNA expression for type I collagen and HSP70 in primary cultured goldfish cells

Goldfish (Carasius auratus) primary culture cells derived from caudal fin were incubated over a temperature range of 20-35 degrees C. The population doubling time of cells cultured at 20, 25, 30 and 35 degrees C were 34, 29, 17 and 14 h, respectively. Interestingly, cDNA-representational difference analysis revealed type I collagen alpha chain (colalpha(I)) as a candidate for a warm temperature-specific gene. mRNA levels of colalpha(I) increased with an increase of incubation temperature and days of culture. Furthermore, the cell growth rate and colalpha(I) mRNA levels were rapidly changed following temperature shifts. To examine the effects of culture temperature shift on the cellular physiological states, mRNA levels of HSP70 were additionally investigated. HSP70 mRNA levels in the cells cultured at 30 and 35 degrees C were again 2-3 times higher than those at 20 and 25 degrees C. When the culture temperature was shifted from 20 to 35 degrees C, HSP70 mRNA levels were rapidly increased within 1 h. Subsequently, mRNA levels of the 35 degrees C-treated cells decreased, but remained doubled compared with those of the 20 degrees C-treated cells, even 4 h following the temperature shift. When the culture temperature was lowered from 35 to 20 degrees C, HSP70 mRNA levels decreased to about 70% of the original levels in 4 h. These results indicate that goldfish cells cultured at different temperatures easily develop temperature-associated steady physiological states within 4 h of temperature shifts.