PRODUCTION OF FISH CHIMERAS FROM EMBRYONIC-CELLS

The efficiency of two cell-transplantation methods were compared for t he production of embryonic cell derived fish chimeras. The classic mic roinjection technique (blastula stage donor cells are microinjected in to blastula embryos) was compared to a novel aggregation method for fi sh developed by our group. This method utilises the ability of dechori onated fish embryos to aggregate. Morula cells dissociated in Ca2+, Mg 2+ free medium were aggregated to recipient embryos of different devel opmental stage. Donor cells and recipient embryos of different develop mental stages were used for most efficient incorporation in the chimer a. The fate of donor cells derived from blastulae, was followed by lab elling them with FITC-dextrane (FD). The most efficient transplantatio ns were gained by using 16-32 cell stage recipients for aggregation (1 8% survival of chimeras at swim up stage). Labelled donor cells were c ontributing to the embryos in varying ratio. A comparison of the effic iency of aggregation was made between diploid-diploid, diploid-haploid and diploid-interspecific (diploid) hybrid chimeras. In all three cas es chimeras containing different proportion of donor cells were gained . After one day incubation the embryos were dissociated by trypsin dig estion and number of labelled and non-labelled cells were counted unde r fluorescent microscope. Experiments were performed on Rosy barb (Bar bus conchonius), Carp (Cyprinus carpio) and African catfish (Clarias g ariepinus).