Dilts J A
J Bacteriol. 1977 Feb;129(2):888-94. doi: 10.1128/jb.129.2.888-894.1977.
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.
对51卡帕品系（四膜虫）的四个变异株系进行了共价闭合环状（CCC）脱氧核糖核酸（DNA）检测。51m43卡帕是一种对51品系杀伤作用具有抗性的非杀伤性品系，含有四类CCC DNA：2.9×10⁷、9.7×10⁷和11.8×10⁷道尔顿。51m43卡帕染色体DNA和CCC DNA的浮力密度分别为1.700和1.698克/立方厘米。51m43派是一个敏感的非杀伤性品系，含有两种CCC种类：0.3×10⁷和4.4×10⁷道尔顿。染色体DNA和CCC DNA的浮力密度均为1.694至1.695克/立方厘米。在51m1派中发现了三种大小的CCC DNA：0.3×10⁷、2.3×10⁷和4.5×10⁷道尔顿。染色体DNA和CC DNA的浮力密度均为1.694至1.695克/立方厘米。尚不清楚51m1卡帕（一种敏感的旋转杀伤性品系）是否含有CCC DNA。其染色体DNA的浮力密度为1.703克/立方厘米。在这四个变异株系中，只有51m43卡帕似乎是51卡帕的突变体。51m43卡帕的染色体DNA和CCC DNA的浮力密度与51卡帕相同；此外，51m43卡帕含有一个与51卡帕中发现的大小相同的CCC分子（2.8×10⁷道尔顿）。其他三个株系可能是与51卡帕不同的细菌物种，它们曾一度与51卡帕共同存在于51品系草履虫中。
