MOLECULAR MECHANISMS FOR CONTENDING WITH OSMOTIC STRESS

• Main Authors: Terence M. Bradley, Todd Smith, Feng Pan, Jacques Zarate
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Atlantic salmon; Salmo salar
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.490.2398; http://www-heb.pac.dfo-mpo.gc.ca/congress/2000/papers/stresspdf/bradley.pdf

Atlantic salmon (Salmo salar) must contend with hyperosmotic stress as juveniles on a seaward migration from their natal freshwater stream. This osmotic stress is more acute in routine aq aculture practice, in which juveniles are directly transferred from freshwater hatcheries to netpens in full salinity seawater ( @ 1100 mOsm). Plasma chloride can rise from 110 to>20 mMol/L in 12 hours (Handeland et al., 1996). Individuals incapable of regaining osmotic/ionic homeostasis die, or grow at a reduced rate (Björnsson t al., 1988; Duston, 1994; Koch and Evans, 1959). In this report, we present investigations of the molecular mechanisms by which salmon adapt to hyperosmotic stress. At least 6 genes have been found to be upregulated in tissues of salmon exposed to osmotic stress in vitro or in vivo. Accumulation of mRNA for heat shock protein (hsp) 70, the major stress protein of fish, increased as much as 500 % in branchial lamellae, hepatic tissues and erythrocytes. Incubation of branchial lamellae in medium containing the membrane permeable solute, glycerol, also caused a prominent increase in the