title: Chromosomal and extrachromosomal deoxyribonucleic acid from four bacterial endosymbionts derived from stock 51 of Paramecium tetraurelia.
abstract: Four variant lines of stock 51 kappa (Paramecium tetraurelia) were screened for the presence of covalently closed circular (CCC) deoxyribonucleic acid (DNA). Stock 51m43 kappa, a nonkiller resistant to 51 killing, contained four classes of CCC DNA: 2.9 X 10(7), 9.7 X 10(7), and 11.8 X 10(7) daltons. The buoyant densities of 51m43 kappa chromosomal and CCC DNA were 1.700 and 1.698 g/cm3, respectively. Stock 51m43 pi, a sensitive nonkiller, contained two CCC species: 0.3 X 10(7) and 4.4 X 10(7) daltons. The buoyant densities of both the chromosomal and CCC DNA were 1.694 to 1.695 g/cm3. Three sizes of CCC DNA were found in 51m1 pi: 0.3 X 10(7), 2.3 X 10(7), and 4.5 X 10(7) daltons. The buoyant densities of both the chromosoaml DNA and the CC DNA were 1.694 to 1.695 g/cm3. It is not known whether 51m1 kappa, a sensitive spinner killer, contains CCC DNA. The buoyant density of its chromosomal DNA was 1.703 g/cm3. Of the four variant lines, only 51m43 kappa appears to be a mutant of 51 kappa. The chromosomal and CCC DNAs of 51m43 kappa have the same buoyant densities as those of 51 kappa; in addition 51m43 kappa contain a CCC molecule the same size as that found in 51 kappa (2.8 x 10(7) daltons). The three other lines are probably bacterial species that are distinct from 51 kappa and which, at one time, were co-inhabitants with 51 kappa in stock 51 paramecia.
mesh_terms: D000818:Animals; D001419:Bacteria / Q000032:analysis* / Q000254:growth & development / Q000648:ultrastructure; D002876:Chromosomes, Bacterial / Q000032:analysis*; D004269:DNA, Bacterial / Q000032:analysis*; D004270:DNA, Circular / Q000032:analysis*; D005111:Extrachromosomal Inheritance; D014644:Genetic Variation; D008970:Molecular Weight; D010247:Paramecium / Q000254:growth & development / Q000382:microbiology*; D010957:Plasmids; D013559:Symbiosis
chemical_list: D004269:DNA, Bacterial; D004270:DNA, Circular