Molecular characterization and expression of HSP70, HSF and HSBP genes in Octopus vulgaris during thermal stress

Temperature is an important environmental factor that affects the growth and survival of Octopus vulgaris, the common octopus. To understand the protective mechanism that O. vulgaris exhibits under heat stress, we used rapid amplification of cDNA ends (RACE) to obtain full-length sequences of three heat stress response related genes: (1) the heat shock protein 70 (OvHSP70), (2) the heat shock transcription factor (OvHSF), and (3) the heat shock factor-binding protein (OvHSBP) of O. vulgaris. The OvHSP70, OvHSF, and OvHSBP proteins contained 2 222 bp, 2 264 bp, 841 bp that encoded for 635, 458 and 90 amino acids, respectively. The results of multiple sequence alignment showed that the amino acid sequences of OvHSP70 were highly conserved with respect to other species. Similarly, the DNA binding domain, the trimerization domain of OvHSF, and the coiled coil region of OvHSBP also had highly conserved regions. The real-time polymerase chain reaction (PCR) results indicated that OvHSP70 was temperature-dependent and time-dependent, showing a positive response to heat stress. On exposure to 28A degrees C and to 30A degrees C, the mRNA expression levels of OvHSF and OvHSBP were higher than those in the control group at 24A degrees C. The mRNA expression of OvHSBP significantly increased with heat treatment at 26A degrees C, while the mRNA expression of OvHSF decreased. The experimental results indicated that the expression of OvHSP70, OvHSF and OvHSBP were all sensitive to heat stress, which suggests that these three genes may play an important role for O. vulgaris in responding to environmental stress. Thus, this study sets a theoretical foundation for further in-depth studies on the molecular protective mechanisms of the heat response in O. vulgaris.