The possession of plasmids was for a long time recognized only in the
bacteria. It is now evident that plasmids, or replicative forms of DNA
structurally and experimentally comparable to bacterial plasmids, exist
in eukaryotic organisms as well. Such plasmids are in fact common among
fungi and higher plants. The present review is undertaken to provide a
comprehensive account of the data available on plasmids found in
eukaryotic organisms. This review will not consider plasmids of
prokaryotic origin, even though certain bacterial plasmids, such as the
tumor-inducing (Ti) plasmids of Agrobacterium tumefaciens, may be
intimately associated with transformation of the eukaryotic host. This
book, moreover, does not consider transformation experiments in
eukaryotic hosts involving viral DNA as vectors, although indeed such
vectors have been developed for use in plant and animal systems. After a
general introduction, providing historical perspective on the nature and
role of plasmids, a list of eukaryotic plasmids will be presented
according to their origin. This is followed by a detailed discussion of
known structure and function. In subsequent chapters the practical
implications of eukaryotic plasmids for molecular cloning and
biotechnology will be discussed. This latter part traces the development
of interest'in biotechnical genetics and gives special consideration to
the use of eukaryotic systems for gene cloning. The terminology
biotechni- cal genetics is introduced to the reader and is used in a
general sense as equivalent to genetic engineering. Biotechnical
genetics includes, but is not limited to, gene cloning through
recombinant DNA technology.
