Vertical and horizontal DNA movement in water solution

Recent studies have shown that soils are characterized by high concentrations of extracellular DNA as the result of complex interactions, including autochthonous DNA production and degradation. Extracellular DNA diagenesis in soil is also influenced by DNA binding to complex organic and inorganic molecules, which might strongly reduce its enzymatic degradation. Consequently, the half-life of extracellular DNA in soil appears to be much longer than it was believed. Extracellular DNA is an important source of nitrogen and phosphorous which are recycled by bacteria for the synthesis of new DNA. Moreover, extracellular DNA might participate in gene transfer and, thus, in the evolution of microorganisms. This study addressed the possibility that DNA, could be transported in the water flow not only by gravimetry but also by vertical and horizontal advections. Using soil column systems, the vertical and horizontal movements of a target DNA sequence from bt- maize (MON810) were monitored and quantified via Real Time PCR for a period of 48 hours. The systems were incubated at 30°C and sampled after 1, 24 and 48 hours. The target fragment was only detected in the DNA spiked columns; therefore, it was useful as a marker for assessing movement. Samples were collected at various depth to monitor the movements. DNA free water was added at the top of the systems to maintain constant soil moisture. Results show that soil DNA drifts in vertical and horizontal directions in water solutions.