Structure and properties of the bacterial nucleoid

In recent yeats the amount of research investigating procaryotic chromosomal structure has been far exceeded by that directed at eukaryotic chromosomes, yet there has been significant advancement in the elucidation of details of the former structures. General understanding of the way genetic information is organized and packaged will be incomplete until the structures of both kinds of chromosomes are worked out. Although one distinction has emerged in the way DNA is packaged in the two kinds of chromosomes, not enough is known about either structure to be certain that the modes of packaging are fundamentally different. The author will review developments of the past few years with procaryotic nucleoids, and will briefly relate these to older studies. With only a few exceptions, all of the findings to be described were obtained with nucleoids of Escherichia coli , although studies of procaryotic chromosomes from other species have, in general, been confirmatory.