An approach to genetic transformation in the Xiphophorine fish

The particular suitability of the Xiphophorine fish system for achieving genetic transformation is presented, and it was analyzed whether information carrying donor DNA might be available to the propigment cells of embryos of Xiphosphorus helleri, which are the target cells for the transformation. Heterologous 2H3H-labelled donor DNA from E. coli, which was taken for technical reasons instead of homologous fish DNA, undergoes degradation both after injection into the neural crest region and after injection into the yolk sac (molecular weight at O h: 50 X10(6); at 2 h: 1 X 10(6); at 5 h: less than 3 X 10(5); at 10 h: less than 1 X 10(4)). It is concluded therefore, that informative donor DNA is present for about 2 to 3 hours after injection. The DNA of the recipient embryo is labelled radioactively during that time at which informative DNA is present only, if the donor DNA is injected into the neural crest region. The probability that a foreign gene might become available to the propigment cells and might induce transformation is discussed.