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Identification of cellular and humoral defence mechanisms

- Carp.
Complement component C3, inducible nitrogen oxide synthetase (iNOS), interleukin-1 beta (IL-1beta), tumor necrosis alpha (TNF-alpha) were all present in the yolk sac embryo. This indicate that the carp embryo may have defence mechanisms that play important roles in eradication pathogens at a very early stage (2dpf). The expression of these genes could be modulated by microinjection of LPS in the eggs.

- Sea bass.
Two monoclonal antibodies against sea bass complement C3 have been obtained. These mAb immunostained in reducing and nonreducing western blot analysis C3 polypeptides in whole larval homogenates. No differences in C3 presence were observed between control and treated sea bass larvae.

The sea bass C3 cDNA was cloned from aminoterminal analysis of purified C3 molecule. The results that will be obtained by studying its expression in sea bass larvae will be released after the end of the project.

The use of molecular probes for complement factor C3 enables the R&D society to use complement expression system to monitor effects of e.g. vaccination and immunostimulation.

- Halibut.
Immune defence molecules such as complement component C3 and lysozyme was found in halibut eggs throughout the egg cycle. There may be a maternal transfer of these molecules and the antipathogenic significance of this presence is still not found. Cathepsin H and D was also found at low levels in halibut eggs.

- Atlantic cod.
Cod complement component C3 has been purified and characterised, anti cod C3 antiserum has been raised to be used in IH experiments. In addition, in-sity hybridisation probes, PCR primers have been made. With all these molecular probes it is possible for the R&D society to screen cod with respect to C3 contents, gene expression analysis that may be beneficial to study the cod immune system.

- Spotted wolffish complement factor C3 was isolated and characterised. Using rabbit anti-spotted wolffish C3 antiserum there was a strong indication that C3 is maternally transferred to its offspring since C3 was found in unfertilised eggs. The wolffish embryo starts to produce its own C3 as the liver generations starts. The C3 contents in wolffish larvae could be increased by use of immunostimulants such as LPS and alginate. The exact significance of the presence of C3 in the eggs and embryos remains to be elucidated. The eggs also contained cathepsins that are important in metabolic/catabolic activities such as antigen degradation as well as peptide antigen expression on MHC II molecules. The activities of cathepsin increased during development.

Reported by

University of Tromsø
Department of Marine Biotechnology, Norwegian College of Fishery Science
N-9037 Tromsoe
Norway