Foreign DNA Absorption
The German geneticist Walter Doerfler has just published results of studies
in which he fed mice a diet to which foreign DNA was added. To his great
surprise the DNA not only survived the instestine without much degradation
but could be found in smaller fragments even in the blood, in white blood
cells, liver and spleen cells.
The study appeared only in German: Doerfler W, Schubbert R (1994), Aufnahme fremder DNA über den Gastro-Intestinaltrakt. Medizinisch-genetische Implikationen, in: Deutsches Aerzteblatt 91, C1166-C1169, but New Scientist 2063, Jan. 4, 97 has featured a short report on Doerflers findings that were presented at the International Congress on Cell Biology in San Francisco, December 1996.
Doerfler even speculates that this might be an evolutionary mechanism. So
it seems to me that
1. DNA is not degradated in the intestine as easily as anyone assumes (No wonder: most studies on DNA digestion have been done with artificial systems),
2. There is not a very efficient barrier between the gut and the blood.
3. Foreign DNA can enter not only blood but liver, spleen and white blood cells, too.
If recombination is possible no one knows. Doerfler thinks that this DNA uptake is very common and says he cannot believe this to be harmful - otherwise evolution would have provided us with much more effective shields against foreign DNA uptake. But this is only speculation.
Dr. Ludger Wess
freelance science writer
Bei der Neuen Muenze 11
Tel ++49-40-679 410 33
Fax ++49-40-679 410 34