Fig. 3 Denaturing gradient gel electrophoresis (DGGE) gel of Archaea 16S rDNA polymerase chain reaction products (Bases 340 to 534 relative to the E. coli rRNA sequence) amplified from USA (Lanes 1–4) and Norwegian (Lanes 5–6) soil DNA extracts. Gel gradient ranging from 30 to 55% denaturant. Lane 1, no-till corn field; Lane 2, no-till soybean field; Lane 3, plowed corn field; Lane 4, plowed soybean field; Lane 5, fallow field; Lane 6, pastureland. Arrows mark each of the 11 different populations detected by DGGE, as determined by the distance the products migrated in the gel. Band A is present in all the soils. Bands B and C are common to all the Indiana soils (Lanes 1–4). Band E was unique to soils under no-till cultivation in Indiana (Lanes 1 and 2). Band D was present in some soils from Indiana and Norway, but its presence did not correlate with any agronomic treatments