Heat shock protein 70 (Hsp70) response to elevated temperatures in the endemic Baikal sponge Lubomirskia baicalensis

摘要

A mass bleaching event affecting an endemic Baikal sponge points out the need to study stress responses in these organisms. To get the first data about Hsp70 content changes in endemic Baikal sponge Lubomirskia baicalensis during exposure to elevated temperatures which can occur in its natural habitat, we investigated the effect of two elevated temperatures on Hsp70 levels in the L. baicalensis and its cell aggregates (primmorphs). After increasing the water temperature from ambient 4 to 9 degrees C Hsp70 levels increased to protect against temperature stress. Incubation at 13 degrees C for one month resulted in bleaching and death of the sponges. The decreased level of HSP70 was recorded both in the case of bleaching after exposure to 13 degrees C, and in diseased individuals from the Lake Baikal. The L. baicalensis primmorph temperature stress response was not consistent with that of the sponge. In primmorphs, the Hsp70 level initially decreased at 4 degrees C and at 13 degrees C it increased compared with the levels observed in the sponge. Thus, our results show that primmorphs are not a good model system for the study of expression of stress proteins in sponges. Since the temperatures 9-13 degrees C were observed at L. baicalensis habitats, climate warming may increase vulnerability of this sponge to bleaching.