Hemocyte morphological parameters and Heat Shock Protein 70 kDa (HSP 70) mantle expression as stress parameters in Mytilus galloprovincialis

The present study aim of investigating the role of the hemocyte morphological parameters (diameter and circularity) and the mantle heat shock protein 70 kDa (HSP 70) as stress parameters in the mussel Mytilus galloprovincialis. The mussel specimens were exposed to the heat stress (40° C) for different times and then placed to the control temperature (18° C); after the stress and during the recovery, the hemocyte parameters were measured using a cell viability analyzer and the results showed the significant increase of the diameter and circularity, demonstrating also the relation between the treatment duration and the mussels ability to recover their homeostasis. Moreover, hemocyte stimulation with Vibrio alginolyticus was conduced in vitro and a significant decrease of the diameter and circularity was observed, whereas the stressed hemocytes maintained their roundish shape, so confirming the inhibitory effect of the stress on the cellular immune system. A third mussel group was also maintained out of the water at cooling temperature (4° C for 24 hours), showing the significant increase of the parameters investigated in a time-dependent manner. The HSP 70 synthesis increase was observed in the heat stressed mussels, particularly after 24 hours of recovery, whereas the cooling temperature exposure induced a time-dependent decrease of the protein expression. In conclusion, the two parameters investigated could represent important stress markers both in field and in experimental study, so suggesting their use in the environmental monitoring, shellfish culture or natural beds management and seafood quality assessment.[...]