Establishing a cell line from Atlantic cod as a novel tool for in vitro studies.

The present work describes the generation of a cell line from newly hatched Atlantic cod (Gadus morhua) larvae (ACL cells). Primary cultures were initiated by explant outgrowth from partially minced tissues and subcultured cells were exposed to UV radiation. After a substantial period of growth lag, cells started to proliferate and different growth conditions were tested to establish the cell line. At present, the ACL cell line has been subcultured for more than 100 passages. ACL cells had a polygonal shape and the morphology appeared homogenous with epithelial-like cells. Cell growth was dependent on the presence of foetal bovine serum and cells proliferated in a wide temperature range with optimal growth at 15 °C. By exposure to a viral dsRNA mimic (poly I:C) the cells expressed high levels of a repertoire of genes comprising both inflammatory mediators and interferon stimulated genes. Infection studies with two different viruses showed that infectious pancreatic necrosis virus (IPNV) propagated efficiently, and induced low level expression of genes of both pathways before the cells rapidly died. No productive infection was obtained with nervous necrosis virus (NNV), but a transient increase in the viral RNA level, followed by a high increase in expression of selected ISGs, suggests that the virus enters the cells but is unable to complete its replication cycle. To our knowledge, ACL cells are at the moment the only existing cell line from Atlantic cod. Our results demonstrate that ACL cells can be a useful research tool for further exploration of host-pathogen interactions and it is believed that this cell line will serve as a valuable tool also for studies within other research areas.

Chitooligosaccharides stimulate Atlantic salmon, Salmo salar L., head kidney leukocytes to enhanced superoxide anion production in vitro.

Chitosans and chitooligosaccharides stimulated Atlantic salmon, Salmo salar L., head kidney leukocytes in vitro to produce elevated levels of superoxide anion. Both soluble and insoluble chitooligosaccharides were stimulatory 2 and 7 days after addition. Protein-chitooligosaccharide conjugates were also stimulatory in vitro both at 2 and 7 days after addition. Deacetylation seemed to be of little importance for the stimulatory capacity. High concentrations of the 80% deacetylated chitosan/chitooligosaccharides were toxic to the leukocytes as judged by reduced reduction of nitroblue tetrazolium and morphology.