Gene transfer and expression in mammalian cell lines and transgenic animals.

Manipulation of the eukaryotic genome not only has contributed to the progress in our knowledge of multicellular organisms but has also ameliorated our experimental strategies. Biological questions can now be addressed with more efficiency and reproducibility. There are new and varied strategies for gene transfer with improved methodologies that facilitate the acquisition of results. Cellular systems and transgenic animals have demonstrated their invaluable benefits. This chapter presents an overview of the methods of gene transfer, with particular attention to cultured cell lines. Alternative strategies of gene transfer are also shown and the applications of such methods are discussed. Finally, several comments are made about the influence of chromatin structure on gene expression. Recent experimental data have shown that for convenient stable transgene expression, the influence of chromatin structure should be seriously taken into account. Novel chromatin regulatory and structural elements are proposed as an alternative for proper and sustained gene expression. These chromatin elements are facing a new era in transgenesis and we are probably beginning a new generation of gene and cancer therapy vectors.