Molecular characterization of two isoforms of piscidin 4 from the hybrid striped bass (Morone chrysops × Morone saxatilis)

HSP40 was an understudied protein family with co-chaperone activity. In the present study, a HSP40 homology was cloned from Venerupis philippinarum haemocytes (designated as VpHSP40) by EST analysis and RACE approaches. The expression profiles of VpHSP40 under Vibrio anguillarum challenge and heavy metal exposure were investigated by quantitative real-time RT-PCR. The bacterial challenge could significantly up-regulate the mRNA expression, and the highest expression level was detected at 24 h post-infection with 6.0-fold increase compared with that in the control group. During heavy metal exposure experiment, the expression of VpHSP40 could also be induced by Cu2+ and Cd2+ at different concentration, where Cu2+ displayed more toxic effect on clam than that of Cd2+. Concerning the same heavy metal, varied effect on VpHSP40 expression was detected at different concentration of heavy metal. Taking together, these results suggested that VpHSP40 was perhaps involved in mediating the immune responses and environmental stresses in V. philippinarum.