Interspecific transfer of mammalian artificial chromosomes between farm animals.

It is often desirable to transfer a mammalian artificial chromosome (MAC) from the cells of one species to those of another. Attempts to carry out such transfer have been successful in some cases and have failed in others. In this study we have tested the hypothesis that centromeric DNA sequence similarity could be a useful criterion for determining MAC host range. Homology studies indicated that the sheep should give positive transfer results. The prediction was tested by introducing into sheep cells a yeast artificial chromosome that contained swine centromeric sequences and that had previously been used to produce a de novo MAC in swine cells. The experiments resulted in the formation of a functional de novo MAC in sheep cells, as attested by FISH analysis. The newly formed MAC remained structurally and functionally stable in ovine up to 52 generations. The centromeric sequences present on the newly formed MAC are probably swine sequences, although it cannot be ruled out that some sheep sequences may also have migrated to the MAC. The size of the sheep MAC was determined by atomic force microscopy. Thus, centromeric sequence similarity appears to be a useful criterion for predicting the animal species between which MACs can shuttle.