Regulation of heat shock protein 70 (Hsp70) levels in the bdelloid rotifer Rotaria rotatoria under temperature stress

Abstract

The bdelloid rotifer is an important component of freshwater zooplankton, exhibiting the features of parthenogenesis and anhydrobiotic capability. Heat shock proteins (Hsps), acting as molecular chaperones, are a highly conserved, ubiquitously expressed family of stress response proteins. In this study, the thermal optimums for heat-shock response and the levels of Hsp70 in Rotaria rotatoria (bdelloid rotifer) under different stress conditions were evaluated using survival assays and western blotting with fluorescent detection. The results showed that: (1) The survivorship in R. rotatoria were 100% throughout the temperature range of 12°C to 40°C, and the population growth rate reached its culmination at 28°C, suggesting the retardation of growth and reproduction at the other temperatures; (2) While stressed under 40°C, the levels of Hsp70 in R. rotatoria increased significantly over time, correlating with the duration of the stress; (3) As responses to different temperatures, the synthesis of Hsp70 could be induced significantly in R. rotatoria under both of high (40°C) and low (16°C) temperatures; (4) After removal of the thermal stress and recovery at 28°C, the levels of Hsp70 continued to rise for a period of time, peaked at 12 h, and then slowly declined with the extension of recovery duration, until there is no significant difference of Hsp70 levels. Summarily, with the fluctuations of stress duration and temperature, the rotifers could adapt to the environments sensitively by regulating the synthesis of Hsp70.

Geographic origin shapes the adaptive divergences of Rotaria rotatoria (Rotifera, Bdelloidea) to thermal stress: Insights from ecology and transcriptomics

“…( 2013 ) found that the upregulation of CuZn‐SOD gene expression in a certain range plays an important role in maintaining the physiological equilibrium of Brachionus calyciflorus . In addition, stress proteins such as heat shock proteins and antioxidant enzymes also play an important role in protecting zooplankton species from thermal stress (Roberts et al., 2010 ), which has been extensively studied in many aquatic organisms (González et al., 2016 ; Xiang et al., 2017 ). Although numerous studies have examined the ecological and physiological responses of aquatic organisms to temperature stress, there is still a dearth of research on transcriptomics.…”