(full paper is archived in the Miller Library)
Title: Bleaching and the Presence of Hsp 70 Isoforms in Thermally Stressed Anthopleura elegantissima
Student Author(s): Lawhon, Price H.
Faculty Advisor(s): Weis, Dr. R. Paul Levine and Dr. Virginia M.
Location: Final Papers Biology 175H
Date: June 1995
Keywords: Anthopleura elegantissima, Heat shock protein, bleaching, thermal stress, heat shock, Hsp 70, hsp70
Abstract: The symbiotic sea anemone Anthopleura elegantissima has been shown to exhibit a salient physiological response to elevated temperature stress that entails the expulsion of its endosymbiotic algae, Symbiodinium californium. A. elegantissima clones were subjected to a 48 h thermal stress at 24 °C and 31 °C. The kinetics of the bleaching event was quantified in the latter treatment such that more than 50% (232000/551000; units in number of alga cells/mg animal protein) of the algae were expelled at the end of the 48 h, and complete loss of algae was noted 13 days after the stress. Two anti-Hsp 70 monoclonal antibodies 3A3 and N27F3-4 (N27), were utilized to probe for constitutive and inducible Hsp 70 family proteins by immunoblotting using anemone samples taken from experimental groups at six time points during and after thermal stress. The 3A3 anti-Hsp 70 mAb recognized a constitutive 70 kD protein in stressed and unstressed anemones at both 24 °C and 31 °C treatments. In the 31 °C group, the N27 mAb revealed rapid induction (seen at six hours) of a 70kD protein under all experimental condidions, but not in the control anemones. Also, the N27 mAb revealed a low molecular weight 30kD cross-reactive protein present in both control and experimental anemone lanes. In the 24 °C elevated temperature group, the N27 mAb revealed no sign of the 70kD protein at all sample times, nor was it present in the control. However, the constitutive 30kD protein was present in all samples including the unstressed anemone. Qualitative changes in soluble proteins in response to both treatments were visualized by [35S]methionine labeling during and after the elevated temperature stresses. An aposymbiotic anemone subjected to the 31 °C heat stress regime showed induction of the 70kD protein; constitutive 70kD protein was also seen with the 3A3 mAb. Identification and temporal correlation of physiological and biochemical responses to elevated temperature stress in cnidarians is novel and instructive for further study of the stress response in invertebrates.