name of transduction. The next year Zinder and Lederberg (1952) have
established that the agent causing the transduction is indiscernible from the
particles of the moderate bacteriophage PLT-22. At the same time Hershey
and Chase (1952), by means of labelled atoms (³⁵S and ³²P) and using the
bacteriophage T2 as the object of study, have proven that only the DNA
molecule penetrates into the bacterial cells and its protein envelope is left
behind.
In a few years time Fraenkel-Conrat and co-authors (Fraenkel-Conrat,
Williams, 1955; Fraenkel-Conrat, 1956; Fraenkel-Conrat, Singer, 1957 a;
Fraenkel-Conrat, Singer, Williams, 1957 b) have established that not only
DNA but viral RNA can also play the role of genetic material. The studies of
Gierer and Schramm (1956, 1957) are directed into that trend. It has later
become clear that the viral DNA and RNA molecules can be both single
stranded and double stranded.
At that time a lot of researchers have made effort to prove that DNA
alone is the component responsible for transduction and conjugation. This
problem is very essential in biology and it therefore will not be left
uncommented.
In his book “The Genetics of Bacteria and their Viruses” W. Hayes
(1964) pointed out that “it turns out that about 3 per cent of the total phage
protein is infected along with the DNA. This protein, however is not part of
the phage envelope but comprises those polyamines and other constituents
which are contained within the phage head and are liberared by osmotic
chock (internal proteins)”.
With experiments in which transforming preparation with a more
thorough purification of DNA have been used, it has been shown that
transforming activity has increased and progressive release of proteins,
other serologically active substances and RNA has not reduced its potency
at all. According to Hayes “The transforming principe, if not DNA, must
therefore be a substance so bizarre that its nature is difficult to imagine””
Here, most properly the question arises: what are these
physicochemical forces and biological mechanisms which roughly for a
minute’s time (the time needed for the passing of the DNA molecule
through the channel thus formed into the recipient cell) could “purify”
thoroughly the DNA molecule from proteins and all sorts of other
components so, that it could in an absolutely pure state be incorporated
into the genome of the bacterial cell and quickly (for about 12 min) to
reproduce and yield the first numerous infections agents.
In my opinion the transforming factor would not have been of so
“bizarre” a nature if it was assumed that together with the DNA also other
components were passing into the recipient cell, which is natural for such a
biological process. The answer to this question is not only necessary but it
is obligatory as well, so that the doubts that this is possible be cleared up.