CHARACTERIZATION OF THE HEAT-SHOCK RESPONSE IN THE GILLS OF SEA LAMPREYS AND A BROOK LAMPREY AT DIFFERENT INTERVALS OF THEIR LIFE-CYCLES

The heat shock response (HSR) was characterized in the gills of two la mprey species that differ with respect to their adult life history. In vivo labelling with [S-35]methionine revealed an enhanced synthesis o f heat shock proteins (HSPs) having approximate molecular weights of 7 0 kDa (HSP70) and 90 kDa (HSP90) following heal treatment. Induction o f the HSR occurred in larval lampreys (ammocoetes) following temperatu re elevations of 13-16 degrees C for the parasitic species, the sea la mprey (Petromyzon marinus) and 16-20 degrees C for the nonparasitic sp ecies, the brook lamprey (Lampetra appendix). The case in L. appendix represents the greatest increase in temperature required to induce the HSR in gill tissue among aquatic poikilotherms studied to date and in duction occurs within a temperature range (25-29 degrees C) not normal ly experienced by these animals. Western blotting detected the presenc e of 70 and 90 kDa HSPs and HSP70 levels were greater in post-metamorp hic L. appendix than in ammocoetes both before and after heat shock. T he HSR of lampreys appears to be induced during times of emergency whe n large, rapid temperature increases are experienced. The high set-poi nt temperature for induction of the response may be a consequence of b oth the environments they presently inhabit and their experiences duri ng evolution. (C) 1998 Elsevier Science Inc. All rights reserved.