Temporal patterns of cold‐induced membrane restructuring in fish cells.

The cells of many animals compensate for altered environmental temperature by changing the phospholipid composition of their membranes. We monitored in fish cells the amounts of mRNA coding for some of the enzymes responsible for making these changes while the cells were exposed to reduced temperature. Chinook salmon embryo cells cultured at 20ºC were transferred to 10ºC for different times before total mRNA was extracted. Primers of our design were used to probe cDNA copies of the mRNA using PCR. PCR products were separated by agarose gel electrophoresis and digitally recorded. We found that mRNAs for the delta‐6 and delta‐9 desaturases were detectable at 20ºC and their quantities increased after 24 h, and again after 48 h, of cold exposure. The amount of message for glycerol‐3‐phosphate acyltransterase was low at 20ºC and remained low until it dramatically increased after 10 days at 10ºC. mRNAs for other enzymes showed other patterns of expression. Overall our data suggest that the metabolic adjustments that restructure membrane phospholipids in response to cold are activated at different times and persist for different intervals. It is likely they occur with a well defined temporal hierarchy. This work was supported by Undergraduate Research Grants from the Henson School of Science and Technology at Salisbury University and by a Guerrieri Summer Research Award.