Table V.

Average GC levels and cesium chloride buoyant densities in maize, Arabidopsis, C. reinhardtii, and P. tricornutum

SpeciesCDS, GCsCDS, GC1CDS, GC2CDS, GC3Buoyant Density of DNATotal DNA, GC
% g cm−3 %
C. reinhardtii 64.36040901.7233-a, 1.72183-b 62.13-c, 63.13-d
Maize60.36040703-e 1.702147.0
P. tricornuum 53.75540651.707548.5
Arabidopsis46.45040451.69535.7

GC levels of total DNA were obtained by calculation of GC level at the peak of the cesium chloride profiles. In the case of maize, we used the value reported by Carels et al. (1995).

    • F3-a  Buoyant densities from C. reinhardtii were taken from Chiang and Sueoka (1967).

    • F3-b  Buoyant densities from C. reinhardtii were taken from our results.

    • F3-c  Corresponding GC levels were taken from Sager and Ishida (1963).

    • F3-d  Corresponding GC levels were calculated from our measurements of the DNA buoyant density using Schildkraut's formula (Schildkraut et al., 1962).

    • F3-e  The average GC3 level is inappropriate for comparison in maize because two classes of genes must be taken into consideration (Carels and Bernardi, 2000). The values previously reported are 68.6% for GC-poor genes and 89% for GC-rich genes. However, the value for GC-poor genes is biased by the small size of the sample and is more likely to be around 50% to 55% GC3 (see Fig. 3).