CsCl banding

The main conclusions of Thiery et al. (1976) were the following (i) all eleven mammalian DNAs analyzed exhibited the three major components 1.697, 1.704 and 1.709 g/cm, first observed in the bovine genome similar components appeared in avian genomes and were, likewise, responsible for the trailing of the CsCl bands on the heavy, GC-rich, side (ii) the DNAs of reptiles, amphibians and fishes showed a much lower skewness to the heavy side of their CsCl bands (iii) essentially symmetrical bands in CsCl, neglecting satellite bands, were displayed by DNAs from three invertebrates (two echinoderms and Dro.sophila) and from three unicellular eukaryotes, S. cerevisiae, E. gracilis, T. pyriformis (see Table 3.2). 

Figure 4.1. CsCl band profiles of fish DNAs. See Table 3 of the original paper for the numbering of samples. Interestingly, even the very low molecular weight samples (see Table 4.2) yielded acceptable profiles, because of the presence of large-size molecules in DNA preparations and of the compositional homogeneity of fish DNAs. (From Bernardi and Bernardi 1990a).

Figure 4.2. The number of fish species is plotted against A modal buoyant densities (only species characterized by different modal buoyant densities within a genus were used), B CsCl band asymmetry and C intermolecular compositional heterogeneity of DNAs. D. Plot of CsCl band asymmetry against compositional heterogeneity of DNAs from fishes (four outliers, numbered according to Table 4.2, were not taken into consideration because the anomalous asymmetries were due to satellite DNAs). The correlation coefficient, R, is given. (From Bucciarelli et al., 2002).

Figure 4.7. CsCl band profiles of DNAs from amphibians. See Table 4.3 for the numbering of samples.

As far as the older results are concerned, DNAs from reptiles exhibited modal buoyant densities that were in the range 1.6992-1.7047 g/cm (Table 4.4A and Fig. 4.8A). Shoulders on the CsCl bands can be seen in at least three DNAs, those from Tarentola mauretanica, Natrix maura and Bothrops neuwiedi (samples 5, 9, 13 of Table 4.4A). Moreover, cryptic satellites might be responsible for the GC-rich tails exhibited by the CsCl band profiles of most DNAs. 

Figure 4.8B. CsCl band profiles from reptiles of Table 4.4B. The profiles from 5 other vertebrates are given on the bottom row. Vertical broken lines correspond to 1.700 and 1.710 g/cm, respectively. (From Hughes et al., 2002).

A, CsCl band asymmetry,

-po BAC(s), Bacterial Artificial Chromosome(s)... 

S.V. 40, minicol nick-close enzyme, gel el, CsCl banding... 

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