DAO 76:251-260 (2007)  -  doi:10.3354/dao076251

Heat shock protein (hsp70) expression and thermal tolerance in sublethally heat-shocked eastern oysters Crassostrea virginica infected with the parasite Perkinsus marinus

V. G. Encomio1, F.-L. E. Chu2,*

1Florida Gulf Coast University, 10501 FGCU Blvd. South Fort Myers, Florida 33965, USA
2Virginia Institute of Marine Science, 1208 Greate Road Gloucester Point, Virginia 23062, USA
*Corresponding author. Email:

ABSTRACT: To investigate whether sublethal heat shock protects Perkinsus marinus (Dermo)-infected oysters Crassostrea virginica from lethal heat stress, and the effects of P. marinus infection on sublethal heat shock response, oysters were first experimentally challenged with P. marinus. Then, when infections in oysters progressed to moderate levels (parasite burden = 104 to 105 cells g-1 wet tissue weight), oysters were treated with a sublethal heat shock at 40°C for 1 h (heat shock + Dermo challenge). Other treatment groups included heat-shocked, unchallenged (non-P. marinus challenged) oysters and non-heat-shocked, P. marinus-challenged and -unchallenged oysters. Thermal tolerance was compared among these treatments by administering a lethal heat treatment at 44°C for 1 h, 7 d after sublethal heat shock. Sublethal heat shock enhanced survival to lethal heat treatment in both P. marinus-challenged and -unchallenged oysters. Although levels of hsp70 isoforms (hsp69 and hsp72) did not vary significantly by heat shock or infection with P. marinus, responses due to these treatments were apparent when comparing hsp70 levels within infected and uninfected oysters. Infection enhanced expression of hsp69, regardless of whether oysters were heat shocked or not. In uninfected oysters, hsp72 increased due to heat shock 2 and 7 d post heat shock. Overall, this study demonstrates that heat shock can improve survival in oysters, even in oysters infected with P. marinus. Expression of hsp70 varied among isoforms after sublethal and lethal heat shocks and in infected and uninfected oysters. The heat shock response was not negatively affected by P. marinus infection.

KEY WORDS: Crassostrea virginica · Heat shock protein · Hsp70 · Perkinsus marinus · Thermal tolerance

Full text in pdf format