Genetically based resistance to summer mortality in the Pacific oyster (Crassostrea gigas) and its relationship with physiological, immunological characteristics and infection processes
|Author(s)||Samain Jean-Francois1, Degremont Lionel2, Soletchnik Patrick3, Haure Joel4, Bedier Edouard5, Ropert Michel6, Moal Jeanne1, Huvet Arnaud1, Bacca Helene1, Van Wormhoudt A10, Delaporte Maryse1, Costil K9, Pouvreau Stephane1, Lambert Christian11, Boulo Viviane7, Soudant Philippe11, Nicolas Jean-Louis1, Leroux Frederique2, Renault Tristan2, Gagnaire Beatrice2, Geret Florence8, Boutet Isabelle11, Burgeot Thierry8, Boudry Pierre2|
|Affiliation(s)||1 : IFREMER, UMR Physiol & Ecophysiol Mollusques Marins 100, Ctr Brest, F-29280 Plouzane, France.
2 : IFREMER, Lab Genet & Pathol, F-17390 La Tremblade, France.
3 : IFREMER, Lab Environm Ressources Pertuis Charentais, F-17390 La Tremblade, France.
4 : IFREMER, LER Pays Loire, F-85230 Bouin, France.
5 : IFREMER, LER Morbihan Pays Loire, F-56470 La Trinite, France.
6 : IFREMER, Lab Environm Ressources Normandie, F-14520 Port En Bessin, France.
7 : Univ Montpellier, Lab GPIA, F-34095 Montpellier 5, France.
8 : IFREMER, Lab Ecotoxicol, F-44311 Nantes 03, France.
9 : Univ Caen, UMR Physiol & Ecophysiol Mollusques Marins 100, F-14032 Caen, France.
10 : Museum Natl Hist Nat, Stn Biol Marine, UMR 5178, F-29900 Concarneau, France.
11 : Univ Bretagne Occidentale, LEMAR IHP, F-29280 Plouzane, France.
12 : Univ Bretagne Occidentale, RSA, Inst Univ Europeen Mer, F-29280 Plouzane, France.
|Source||Aquaculture (0044-8486) (Elsevier), 2007-08 , Vol. 268 , N. 1-4 , P. 227-243|
|WOS© Times Cited||116|
|Keyword(s)||ROS, Temperature, Stress, Hemocytes, Reproduction, Genetic selection, Resistant oyster, Crassostrea gigas, Pacific Oyster, Summer mortality|
|Abstract||Summer mortality of Pacific oysters is known in several countries. However no specific pathogen has been systematically associated with this phenomenon. A complex combination of environmental and biological parameters has been suggested as the cause and is now starting to be identified. A high genetic basis was found for survival in oysters when a first generation (G1) was tested in three sites during summer. This paper presents a synthesis on physiological characteristics of two selected groups ('R' and 'S', from families selected for resistance and susceptibility to summer mortality respectively), of the second and third generations. R and S showed improvement or reduction of survival compared with the control in both field and laboratory trials confirming the high heritability of survival of juveniles < 1 year old. Interestingly, no correlation was observed between growth and survival.Comparison between the two selected groups showed that S oysters invested more energy in reproduction and stayed a longer time without spawning than R oysters which had high synchronous spawning. This was mainly shown with high rather than low dietary rations (respectively 12% and 4% DW algae/DW oyster) in a controlled experiment. Moreover, early partial spawning was detected in S oysters and not R ones in the high dietary ration. S showed a higher respiration rate and an earlier decrease in absorption efficiency than R during gametogenesis, but they were not significantly different in glycogen or ATP utilisation. Two months before a mortality episode, hemocytes from S oysters had a higher adhesive capacity than R hemocytes and significantly higher reactive oxygen species production capacity. One month before mortality, S oysters had the highest hyalinocyte concentration and their expression of genes coding for glucose metabolism enzymes (Hexokinase, GS, PGM, PEPCK) was significantly lower in the labial palps. After a thermal increase from 13 °C to 19 °C, during 8 days in normoxia, S oysters showed a large HSP70 increase under hypoxia contrary to R oysters, suggesting their high susceptibility to stress. Their catalase activity was lower than in R oysters and showed no further change to subsequent hypoxia and pesticide stresses, in contrast to R oysters.These observations suggest possible links between higher reproductive effort in S oysters, their specific stress response to temperature and hypoxia, ROS production, partial spawning, hyalinocyte increase and the infection process. To compare R and S oysters in a more integrated way, a suppression subtractive hybridisation (SSH) library and a micro-array strategy are being undertaken.|