Nwember 19, 1971

Dr. T. Ando
Laboratory of Microbiology
Inrtitute of Physical and Chemical Rerearch
Saaato - Madri
Saitama - Ken
351, Japan

Dear Dr. Ando:

For the part year I have been using batch elution from hydroxyapatite to
analyze DNA rearnociation.
in the caclored manurcripte - have been to characterite the DHA made by
the RNA dependent DUA polymerase associated wtth the RNA t-r viruses
and to use thfa DaoA 88 a pmbe for detoction of tumor virus requencee in
call DNA.

The objectr of our experimentr - as indicated

Recently Dr. Michael Birhop and I have examined the activity of a ringle
strand-rpecific nuclease from Neuroapora crat~ra, uring the product of
reverse tranrcriptare ar 8ubrtr.te.
product further, to examine the DP?A after reasrociation with itself 8nd
with cell DNA, and to UBQ the eaiyae a8 a time-eaviag replacement for
hydrosyapatite analysis of kt curves.
obtained from our Neurorpora 4 conidia ham not been very great, although it
is htghly specific for aingle r~randad DNA.
renritive to high ralt concentrationr.  As a moult, it ir not proving very
valuable to us.

Our aims were to charactrite thio

Unfortunatilp the activity we have

In addition, it is extrrrely

Yesterday, I talked wtth Dr. Paul Berg of Stanford and he told me about
the beautiful rcssulto he has obtained uring your enspa to warure IHA
rearroctation.
current netbod of preparing the easyme.
work and, in fact, ordered Takadiastarc from Sankyo a few week8 ago.)
Would it be porrible for you to rend ur namm of your enqnm to iroric writh
until we are able to extract our om?  We vould naturally acknwledge the
debt in any publicationr and would keep you informed of our experience
with the entyerr - and of how it camparer fa our hands with our Neurospora
activity.  Can you rend ur, in addition, refemaces to your work vith thrs
enzyme rince the article in BBA 114: 158, 1966P

At his ruggestion, I am writing nov to ark for your

(We have been aware of your

Thanking you in advance,  I am.

Yours truly,

Barold E. Varmun, M.D.

Wpartment of Hicrobiology