Extrachromosomal inheritance in bacteria.

INTRODUCTION............................................................ 211 Definitions.................................................................. 211 Overall Genetic Organization of aPlasmid. 212 RECOGNITION AND IDENTIFICATION OF EXTRACHROMOSOMAL ELEIMENTS............................................................. 212 Lack of Genetic Linkage to Chromosome....................................... 214 Lack of Genetic Homology with Chromosome................................... 214 Occurrence of Conjugal Transfer.............................................. 214 Demonstration of Physical Autonomy.......................................... 214 Demonstration of Replicative Autonomy........................................ 214 Ability to be established in a recombination-deficient host....................... 214 Isolation of replicationor segregation-defective mutants........................ 215 Radiation target size...................................................... 215 Kinetics of radiation inactivation in gene transfer experiments.................... 215 Incompatibility with a known plasmid........................................ 215 Plasmid loss and curing.................................................... 215 Conclusion................................................................. 217 GENERAL DESCRIPTION................................................... 217 Transmissible Plasmids....................................................... 218 Nontransmissible Plasmids.................................................... 219 Cryptic Plasmids............................................................ 219 Pi factors............................................................... 222 Cryptic plasmid DNA...................................................... 223 Controlling episomes....................................................... 223 Essential Plasmids........................................................... 224 Certain Phages ............................................................ 224 Extrachromosomal Inheritance in Other Organisms.............................. 225 CLASSIFICATION........................................................... 225 Transmissible Plasmids....................................................... 225 Nontransmissible Plasmids.................................................... 226 Staphylococcal Plasmids...................................................... 227 Autonomy and Infectivity..................................................... 227 PHYSICAL BASIS OF EXTRACHROMOSOMAL INHERITANCE.............. 229 SOMATIC FUNCTIONS: MECHANISMS AND CONTROL.................... 229 Fertility................................................................... 232 Recombination, Integration, and Immunity...................................... 232 Bacteriocins............................................................ 232 Resistance to Physical, Chemical, and Biological Agents.......................... 233 Epistatic Sensitivity ......................................................... 233 Phage and UV Resistance.................................................... 233 Converting and Hft Phages................................................... 234 Other Somatic Functions..................................................... 234 Structural Genes............................................................ 234 Control of Plasmid Somatic Functions.......................................... 234 INTERACTIONS BETWEEN REPLICONS.................................... 235 Entry Excluon............................................................ 235 Incompatibifty..... ... ........... . .. . .. ............................. 236 Basis of incompatibility.................................................... 237 Evidence for the maintenance site model...................................... 237 The segregation unit..................................................... 237 Host mutants........................................................... 238 Plasmid mer region...................................................... 238 Incompatibility sets...................................................... 238 Complicating factors....................................................... 238 F/Hfr incompatibility.................................................... 238 ColV plasmids.......................................................... 238