Biomaterials for Bone Regeneration

Gene transfer vectors and their incorporation into biomaterials 379

was actually caused by deoxyribonucleic acid (DNA), revealing that the

genetic information is carried by DNA and not protein, as was still believed

at that time (Avery et al ., 1944). Furthermore, Joshua Lederberg discovered

that certain bacteria may transfer genetic material by mating (i.e. conju-

gation) (Tatum and Lederberg, 1947), as well as via transduction (Zinder

and Lederberg, 1952). Zinder and Lederberg observed that recombination

of nutritional and drug-resistant mutants of Salmonella with the wild-type

form took place even when separated by a  ne glass  lter. They argued

that an active ‘ ltrate’ was responsible for the transfer of hereditary traits

between ...