This is a somewhat belated reply to your letter of July 1st.
Things have been very hectic around here, the RNA problem having broken wide open and things are going along fantastically
Yank observed cross reactions amongst the bacteria from the very beginning. That is why we used viral and mammalian DNA to
check for specificity. Subsequently, we carried out a fairly extensive examination over the past few years of this cross
hybridization. This was started by Yankofsky and has been continued by David Gillespie in the bacteria and by Ritossa in
higher forms. The central issue is to check whether a heterologous hybrid with ribosomal RNA actually involves the "ribosomal
cistrons" of the challenging DNA. We have been using the Drosophila material as well as various strains of E. coli which
we have found contain different doses of the ribosomal RNA to control this. Without this sort of information, no certain
conclusions can be drawn. We will probably be writing much of this material in the near future. The trouble is we have so
much because we waited until we were certain. The amount of ribosomal homology is amazing (e.g. 30% between chicken and drosophila).
I am sending you a copy of a paper which is to appear in the JMB which describes our new method of hybrid detection which
is extremely accurate, sensitive, and convenient. I am also including a preprint on our RNA synthesizing system. I am just
in the process of finishing up three more papers on this system. The reason why this work has suddenly blossomed forth is
that we have finally been able to make infectious RNA in the test-tube in massive quantities. This gives us confidence that
we are really studying the right reaction. Also, under separate cover, you will receive some more reprints of a paper given
I do hope to be out on the West coast in late October since I will be attending a meeting of the Academy in Seattle. It is
more than likely that I will be in and around the Bay area the week of October l8.