Fig. 3. Heat shock protein (hsp) accumulation in explanted shark lateral choroid plexus (CP) after thermal stress in the presence and absence of trimethylamine oxide (TMAO). Lateral CPs from individual sharks were each divided into three equal-sized segments, totaling six pieces; tissues were separated into three pairs and incubated, ± 72 mmol l^–1 TMAO, at 13.5°C for 7.5 h (), at 18.5°C for 6 h plus recovery at 13.5°C for 1.5 h (+5°C), or 23.5°C for 1 h plus recovery at 13.5°C for 1.5 h (+10°C). (A) Representative immunoblot for Hsp70 and actin accumulation in lysates of non-heated and heat-stressed lateral CP. (B) Graphical summation of Hsp70 accumulation (normalized to actin accumulation) in non-heated and heat-stressed lateral CP (means ± s.e.m., N=4). For each condition, fold-induction of heat shock protein was calculated by dividing the normalized Hsp70 accumulation in the absence of TMAO by the normalized Hsp70 accumulation in the presence of TMAO. ^*Significantly different from paired tissue treated in the presence of TMAO at P<0.05.