The study of bacterial plasmids has not always been as popular as it is today. For many years, the molecular biology of pro cary otes was focused heavily on bacteriophage and plasmid investigations which were carried out in only a few laboratories. Whatever inter est existed in plasmids concerned the role of these extrachromosomal elements in bacterial conjugation, genetic exchanges, and antibiotic resistance, as well as in the structure of plasmids themselves. Gradually, however, it became increasingly evident that many of the special characteristics displayed by bacteria of medical, agricul tural, industrial, and environmental importance are determined by genes carried by plasmids, and this interest in plasmid-encoded functions, such as bacterial virulence properties (exotoxin produc tion, serum resistance, adhesiveness), metabolism of organic com pounds, plant tumor formation, and biological nitrogen fixation, led to increasing study of. the plasmids that carry these genes. Inves tigations of other plasmid-related properties such as replication and recombination have yielded much information about fundamental biological processes; information having implications that extend far beyond the particular plasmids under study. Concurrently, plas mids were playing a key role in the discovery of bacterial transpos able elements and were proving to be increasingly useful in the elu cidation of mechanisms responsible for a variety of chromosomal rearrangement events in bacteria and plants. Their status as "mini chromosomes" that could be isolated easily from bacterial cells and then reintroduced into other cells by transformation is of fundamen tal importance in this regard.

Inhalt
Structure and Evolution.- Plasmids as Organisms.- Report on a Workshop: Structure and Function.- Evolutionary Relevance of Genetic Rearrangements Involving Plasmids.- Mechanisms of Transposition in Bacteria.- Insertion of Transcriptional Elements Outside the Replication Region Can Interfere with Replication, Maintenance, and Stability of ColE1-Derived Plasmids.- Studies on the Transposition of IS1.- On the Transposition and Evolution of Tn1721 and its Relatives.- Repeated DNA Sequences Recombine 1,000 Times More Frequently in a Plasmid Than in the Chromosome of BacillusSubtilis.- Mercury Resistance Transposon Tn813 Mediates Chromosome Transfer in Rhodopseudomonas sphaeroides and Intergeneric Transfer of pBR322.- Report on a Workshop: Plasmids in Unusual Systems.- Replication, Incompatibility, and Partition.- Chairman's Introduction: Replication, Incompatibility, and Partition.- Role of the ? Initiation Protein and Direct Nucleotide Sequence Repeats in the Regulation of Plasmid R6K Replication.- Initiation of Replication of the EscherichiaColi Chromosomal Origin Reconstituted with Purified Enzymes.- Origin and Initiation Sites of ?dv DNA Replication In Vitro.- Broad Host-Range Plasmid R1162: Replication, Incompatibility, and Copy-Number Control.- Control of Plasmid Replication: Theoretical Considerations and Practical Solutions.- The Partition Functions of PI, P7, and F Miniplasmids.- Genetic Interactions of Broad Host-Range Plasmid RK2: Evidence for a Complex Replication Regulon.- Replication Determinants of the Broad Host Range Plasmid RSF1010.- Regulation of Replication and Maintenance Functions of Broad Host-Range Plasmid RK2.- Control of Chromosome Replication in Bacteria.- Stable Maintenance of Plasmid CLO DF13: Structural and Functional Relationships BetweenReplication, Control, Partitioning, and Incompatibility.- Replication Control for PT181, An Indirectly Regulated Plasmid.- Construction of ColE1 RNA1 Mutants and Analysis of their Function In Vivo.- Incompatibility and INCFII Plasmid Replication Control.- P1 Plasmid Maintenance: A Paradigm of Precise Control.- Partitioning of the pSC101 Plasmid During Cell Division.- DNA-Protein Interaction at the Replication Origins of Plasmid Chromosomes.- Positive Regulation and Transcription Initiation of xy1 Operons on TOL Plasmid.- Plasmid Transfer.- Chairmen's Introduction: Plasmid Transfer.- Linear Plasmids with Terminal Inverted Repeats Obtained from Streptomycesrochei and Kluyveromyceslactis.- Conjugal Plasmid Transfer in BacillusThuringiensis.- Mechanisms Essential for Stable Inheritance of Mini-F Plasmid.- Sex Pheromones and Plasmid Transfer in StreptococcusFaecalis: A Pheromone, cAM373, Which is Also Excreted by StaphylococcusAureus.- General Genetic Recombination of Bacterial Plasmids.- The Origin of Plasmid DNA Transfer During Bacterial Conjugation.- Genes and Gene Products Involved in the Synthesis of F-PILI.- Genetics of Clindamycin Resistance in Bacteroides.- Effect of Chromosome Homology of Plasmid Transformation and Plasmid Conjugal Transfer in Haemophilus Influenzae.- Plasmid DNA Primases and Their Role in Bacterial Conjugation.- Promoters in the Transfer Region of Plasmid F.- Conjugative Sex Plasmids of Streptomyces.- Specialized Functions, Structure, and Evolution.- The Structure and Source of Plasmid DNA Determine the Cloning Properties of Vectors for BacillusSubtilis.- Shuttle Vector for EscherichiaColi, PseudomonasPutida, and PseudomonasAeruginosa.- Report on a Workshop: Plasmid Cloning Vehicles.- Plasmids in the Degradation of Chlorinated AromaticCompounds.- Notes on Metabolic Plasmid Organization and Expression.- The Structure of the mer Operon.- Analysis and Manipulation of Plasmid-Encoded Pathways for the Catabolism of Aromatic Compounds by Soil Bacteria.- The Plasmid-Specified Aerobactin Iron Uptake System of EscherichiaColi.- Plasmid-Mediated Iron Sequestering Systems in Pathogenic Strains of Vibrioanguillarum and EscherichiaColi.- Chairman's Introduction: Specialized Functions.- Cloning of an Enzymatically Active Segment of the Exotoxin-A Gene of PseudomonasAeruginosa Ill.- Structure, Function, and Regulation of the Plasmid-Encoded Hemolysin Determinant of EscherichiaColi.- pIAA, A Virulence Plasmid in PseudomonasSavastanoi.- The Molecular Basis of Plant Cell Transformation by AgrobacteriumTumefaciens.- Post-Transcriptional Regulation of Chloramphenicol Acetyl Transferase.- Plasmid and Larval Toxin of Bacilluslaterosporus.- Posters (Poster abstracts have been reproduced as submitted).- Replication, Incompatibility, Partition.- Specialized Functions.- Structure and Evolution.- Transfer.- Vectors.- Rosters.- Speakers.- Participants.- Index of Poster Authors.