The heat shock response of an antarctic alga is evident at 5 degrees C.

A subtidal seaweed collected in antarctic waters, Plocamium cartilagineum (L. Dix.), displayed induction of mRNAs encoding the 70 kDa heat shock protein (HSP70) and the ubiquitin polyprotein (UBI) when incubated at 5 degrees C. Maximal induction of HSP70 mRNA was observed when the alga was incubated at 10 degrees C for 1 h. Incubations at higher temperatures or for longer periods reduced the amount of HSP70 mRNA detected. Incubations at 20 degrees C or greater resulted in cell death. These data indicate that dispite the unusually low temperature of induction, this macrophyte exhibits a heat shock response similar to that of other organisms at temperatures 5 to 10 degrees C above usual growth conditions.