DNA Base Composition in Mycoplasma, Bacteria and Yeast

Genome comparison in yeast systematics: delimitation of species within the genera Schwanniomyces, Saccharomyces, Debaryomyces, and Pichia.

“…Most of these efforts have used the thermal denaturation procedure of Marmur and Doty (73). The results obtained by this method can be markedly affected by both the purity of the DNA and the presence of minor DNA species (3). The buoyant density method of Schildkraut et al (106) is considerably less influenced by either of these problems and thus is considered the method of choice whenever the necessary equipment is available (3).…”

Polarity and topology of DNA segregation and septation in cells and sporangia of the bacilli

“…Although the range of the % GC values in the genus Brrcillrrs is wide being about 32-66% (Hill 1968), the range of the distribution of bases within the chromosome of a given species is narrower. There is evidence that the complementary strands of Brrcilllrs DNAs differ in average base composition (reviewed by Bak 1973). Fragmented complementary strands of the DNA of B .…”

“…1970). This would mean that promoters are relatively pyrimidine-rich (Bak 1973). Eleven out of the 16 opel-ons and genes of the Esclzerichia coli genetic map (Taylor and Trotter 1972) for which the transcriptional directions are known are transcribed in the anticlockwise direction of the map.…”

Advances in Penicillium and Aspergillus Systematics

“…Base composition may be determined from thermal denaturation profiles (melts), buoyant density in cesium salt gradients generated by ultracentrifugation, chemical analysis, absorbance ratios, or high-pressure liquid chromatography of nucleotides or free bases (Johnson 1981). Most investigators use thermal denaturation (Marmur and Doty 1962), but Bak (1973) showed that results obtained by this method can be greatly affected by sample impurities and/or minor DNA species, and must therefore be interpreted with caution. Cesium chloride buoyant density determinations (Schildkraut et al, 1962) generally show the greatest accuracy, since they are unb1ased by the presence of contaminating RNA, mitochondrial DNA, and other impurities, such as carbohydrates and proteins.…”