Differences in heat shock protein 70 expression during larval and early spat development in the Eastern oyster, Crassostrea virginica (Gmelin, 1791).

For a variety of species, changes in the expression of heat shock proteins (HSP) have been linked to key developmental changes, i.e., gametogenesis, embryogenesis, and metamorphosis. Many marine invertebrates are known to have a biphasic life cycle where pelagic larvae go through settlement and metamorphosis as they transition to the benthic life stage. A series of experiments were run to examine the expression of heat shock protein 70 (HSP 70) during larval and early spat (initial benthic phase) development in the Eastern oyster, Crassostrea virginica. In addition, the impact of thermal stress on HSP 70 expression during these early stages was studied. C. virginica larvae and spat expressed three HSP 70 isoforms, two constitutive, HSC 77 and HSC 72, and one inducible, HSP 69. We found differences in the expression of both the constitutive and inducible forms of HSP 70 among larval and early juvenile stages and in response to thermal stress. Low expression of HSP 69 during early larval and spat development may be associated with the susceptibility of these stages to environmental stress. Although developmental regulation of HSP 70 expression has been widely recognized, changes in its expression during settlement and metamorphosis of marine invertebrates are still unknown. The results of the current study demonstrated a reduction of HSP 70 expression during settlement and metamorphosis in the Eastern oyster, C. virginica.