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.

Inhalt

I. Introduction.- A. Definition.- B. Historical Perspective.- II. Fundamental Aspects.- A. General Characteristics.- B. Nuclear Plasmids.- 1. Saccharomyces cerevisiae-the 2µm Plasmid.- 2. Dictyostelium discoideum-a. Cobalt Resistance Plasmid.- 3. Drosophila melanogaster-the Transposable Element Copia.- C. Mitochondrial Plasmids.- 1. Podospora anserina-the Senescence Plasmid.- 2. Neurospora crassa-the Stopper and Poky Plasmids.- 3. Neurospora crassa-the Mauriceville Plasmid; Neurospora intermedia-the Labelle and Fiji Plasmids.- 4. Claviceps purpurea.- 5. Other Fungi.- 6. Higher Plants.- D. Unknown Association.- III. Practical Implications.- A. Fundamentals for Eukaryotic Gene Cloning.- 1. Generalized Vector.- 2. Choice of an Appropriate Host Cell.- B. Plasmids for Gene Cloning.- 1. The 2µm Plasmid of Saccharomyces cerevisiae.- 2. Ribosomal DNA Plasmids.- 3. The Senescence Plasmid of Podospora anserina.- 4. The Labelle Plasmid of Neurospora intermedia.- 5. The Mitochondrial Plasmid of Cochliobolus heterostrophus.- 6. The Transposable Elements of Drosophila melanogaster.- C. Organellar DNA for Gene Cloning.- 1. Vectors Based on Confirmed Replication Origins.- 2. Vectors Based on Random DNA Segments as Origin of Replication.- D. Maintenance of Vector Transferred Genes.- 1. Stabilization of Vectors in Host Cells.- 2. Efficient Expression of Cloned Genes.- E. Biotechnological Perspectives.- References.