12 September 1972

Dr. Ian Xacpherson
Imperial Cancer Research Fund
Lincoln's Inn Fields
London, England

Dear Dr. Wacpherson:

I have enclosed copies of the first experirjler\t perfolenrad with the
DeJA's you have sent to us.  The protocols ore as described in the
      sent you earlier:    of slowly-rearsociating double-

preprint stranded 4 DNA made by Schmidt-Ruppin RSV polymerase is reassociated
in the presence of 4 mg/ml of cell DNA.
reannealing of the viral DNA are pcrfomd with hydroxyapatite (Fig. 1)
or single strand specific nuclease (Fig. 2) Some of the results
conform to expectation - namely, J2?A from salmon sperm and normal
BBK cella (data not shown here)  do not offect reanneallng, whereas
- SR-transfowed -- cells appear to have about 1 copy per diploid cell.
Hmwever, the other data is very perplexing - the H!3V transformed
cells appear to have clreecopy and the Bryan-transfo~d have none.
One obvious porsibllity is that the DNA's fclr;m these two lines were
confused at some poht in our lab or yours.  Since BHK it8elf ir
negative and we have seen no cross reaction between avian and awmmlian
tumor virus nucleotide sequences hetetofore, it seems very improbable
to me that the HSV/BHR is truly positive.
been dare twice with hydroxyapatite assay, with identical result.)
Of course, the BTan-transfonne4 liner could be negative, thus  $6'
accounting for its tendency to revert, and that would be very
interesting.
to rend another batbh of HSV/BHE[ DNA, ae well as revertant DNA.
It will obviourly be important to look at another preparation ofPQ4
from Bryan-tranrformed cella with 8 low percentage @f revertantr.

Assays for extent of

(The experiments have

But in view of the confusion, I asked you in my telegram

Needles. to say, I am unhappy about these difficulties.
repetition of tedious preparations and assays on both our parts will
be required to rectify matters.
ASV/BBK might be positive, please forward them.

Unfortunetely,

If you have any ideas abut why

Rega rds ,

Harold E. Vanmus
Ass is tan t Professor
Department Of Microbiology

HEV : crc
encl.