Dynamic and differential expression of the gonadal aromatase during the process of sexual differentiation in a novel transgenic cyp19a1a-eGFP zebrafish line.

In zebrafish, there exists a clear need for new tools to study sex differentiation dynamic and its perturbation by endocrine disrupting chemicals. In this context, we developed and characterized a novel transgenic zebrafish line expressing green fluorescent protein (GFP) under the control of the zebrafish cyp19a1a (gonadal aromatase) promoter. In most gonochoristic fish species including zebrafish, cyp19a1a, the enzyme responsible for the synthesis of estrogens, has been shown to play a critical role in the processes of reproduction and sexual differentiation.

Natural anti-TNP antibodies from rainbow trout interfere with viral infection in vitro.

Normal and viral-infected rainbow trout (RT) were tested for serum antibody activity against self and nonself antigens. Particularly high titres of anti-trinitrophenyl (TNP) antibodies were noted, as in other fish species. To analyse this, the anti-TNP antibodies were isolated by affinity chromatography and their capacity to interfere with viral infection in vitro was studied.

Rainbow trout complement fixation used for titration of antibodies against several pathogens.

Since it is impossible to fix guinea pig complement (C) with Rainbow Trout (Salmo gairdneri) antibodies, whereas it is possible with Brown Trout (Salmo trutta) antibodies, a C fixation test has been designed which uses haemolysin and C from Rainbow Trout. Immunization of trout against lysed sheep red blood cells (SRBC) elicited production of haemolytic IgM. Normal trout serum (NTS) can be used as a source of C at a dilution at which its "natural" haemolytic activity (against various homeotherms RBC) has disappeared.

[Infectious pancreatic necrosis virus: acquired susceptibility to trout serum neutralizing factor after repeated passage in cell culture].

It has been shown previously that in normal sera from IPN free Rainbow Trout a "6 S molecule" neutralized Sp type IPN Viruses routinely used in European fish diseases laboratories. These viruses were unable to reproduce the disease under experimental conditions. After a survey of trout farms, a Sp type pathogenic virus was isolated (isolate 31/75).