FIG. 1.

The DNA contents in different soil layers of an oak-hornbeam forest were extracted as described in Materials and Methods. The DNA extracted from 0.2 g (wet weight) of soil was blotted onto each lane. Samples were taken from 5-, 10-, and 25-cm depths. Parallels on these 0.7% agarose gels are for two independent DNA extractions from the same soil sample. The ∗ denotes the smear under the RNA band, due probably to humic acids and other interfering substances.