Variability in the diurnal stress protein (Hsp70) cycle in tropical chitons (Acanthopleura granulata) from the intertidal zone: the influence of temperature and photoperiod exposure

Daily variations in the heat shock proteins (Hsp70) level were studied in the tropical chiton, Acanthopleura granulata, in the field and laboratory. Experiments were designed to measure influence of temperature and light regimes on the production of Hsp70 in the foot muscle and intestines. The temporal rhythm of the water and air temperature cycles in the laboratory experiments referred to the field situation and defined the body (intestinal) temperatures of chitons. Light cycles were changed to alternating 8-hour periods of light and dark for duration of eight days. In our experiments, Hsp70 levels did not show any cyclic pattern in the intestines. This leads to the assumption that protein productions within the intestinal tract are influenced by many factors not following a specific temperature or light cycle. Hsp70 levels increased in the foot muscle with the onset of darkness under natural conditions as well as under an altered light regime situation. Hsp70 levels decreased again during the day. Protein and therefore also Hsp70 production seems to be linked to the activity pattern of the chitons.