Nucleotide distribution in bacterial DNA's differing in G + C content

Abstract

Summary. The DNA's of Micrococcus lysodeikticus and Clostridium per/ringenswere fragmented to about 7 000 nucleotide pairs long by shear and fractionated with respect to buoyant density of mercury complexes in Cs2SO 4. The distribution of G + C content in both DNA's was characteristically asymmetric. In M. lysodeikticus DNA, low G + C fragments were more numerous than high G + C fragments, whereas in C. per/ringens DNA, high G + C fragments were more numerous than low G + C fragments. The G+ C content of fragments of M. lysodeikticus DNA varied from 70 to 77 %, with a mean and standard deviation of 73.7 ± 1.92 % G + C and that of C. per/ringens DNA varied from 27 to 34 %, with a mean and standard deviation of 29.8 i t .34 % G + C. Tile standard deviation was smaller than that of Escherichia coli DNA fragments of similar size. Biological meanings of relatively low heterogeneity in nucleotide composition in M. lysodeikticus and C. per/ringens are discussed. Key words: Micrococcus lysodeikticus --Clostridium per/ringens --DNA --Hg --Cs2SO 4 --Low Heterogeneity --Composition Bias at the Third Coding Positions --tRNA.It was recently reported (Yamagishi, t970; Yamagishi and Takahashi, 197t) that the bacterial DNA's of Escherichia coli and Bacillus subtilis contained segments of dissimilar nucleotide composition. In this communication, the result of a similar investigation carried out with bacterial DNA's having extreme G-k C composition is presented.Clostridium per/ringens strain PB6K and Micrococcus lysodeikticus strain 2665 used in the present investigation were obtained from Research Institute of Microbial Diseases, Osaka University, Japan. M. lysodeikticus was grown for 24 hrs in low P-k-broth (pH 7.2) containing per liter 10 g low P-polypeptone (Inorganic phosphorus content decreased to 0.008 % in our laboratory) and 2.5 g NaCI. C. per/ringens was

The Major Components of the Mouse and Human Genomes

“…The values for statistical DNA (points) were obtained by simulating a cleavage by restriction enzymes of a DNA having a random sequence built using the Monte Carlo method, with a Control Data 6600 computer; the solid line is the relationship predicted by Sueoka [33]. The values for E. coli DNA (0) arc from Miyazawd and Thomas [35] for the lowest-molecular-weight sample, from Yamagishi [38], or calculated according to Schmid and Hearst [22] for the other ones. The values for H. influenzae DNA were also calculated according to Schmid and Hearst [22].…”

Quantifying intrachromosomal GC heterogeneity in prokaryotic genomes

“…Already early ultracentrifugation results on bacterial GC heterogeneity (Sueoka, 1959;Guild, 1963;Yamagishi, 1974) had indicated that long regions of distinct base composition should exist within the genomes of some bacteria. We can now confirm the existence of such regions at the sequence level.…”