Production of fish chimeras from embryonic cells

The efficiency of two cell-transplantation methods were compared for the production of embryonic cell derived fish chimeras. The classic microinjection technique (blastula stage donor cells are microinjected into blastula embryos) was compared to a novel aggregation method for fish developed by our group. This method utilises the ability of dechorionated fish embryos to aggregate. Morula cells dissociated in Ca2+, Mg2+ free medium were aggregated to recipient embryos of different developmental stage. Donor cells and recipient embryos of different developmental stages were used for most efficient incorporation in the chimeras. THe fate of donor cells derived from blastulae, was followed by labelling them with FITC-dextrane (FD). The most efficient transplantations were gained by using 16-32 cell stage recipients for aggregation (18% survival of chimeras at swim up stage). Labelled donor cells were contributing to the embryos in varying ratio. A comparison of the efficiency of aggregation was made between diploid-diploid, diploid-haploid and diploid-interspecfic (diploid) hybrid chimeras. In all three cases chimeras containing different proportion of donor cells were gained. After one day incubation the embryos were dissociated by trypsin digestion and number of labelled and non-labelled cells were counted under fluorescent microscope. Experiments were performed on Rosy barb (Barbus conchonius), Carp (Cyprinus carpio) and African catfish (Clarias gariepinus).