xxxx 94143

September 3, 1974

Dr. Luir M. de la Ma-
Dep8rtment of Laboratory Medicine and Pa thology
Unfversity of Minnesota
Box 198, Way0 Memorial Building
Minneapolis, Minnesota 554S5

Dear Dr. de la mza,

I have just received and read your (our) manuscript and in general I think
it makes 8 nice story.
a note to Virology, or, as you suggert, ar a rhort paper to al.
could alm be a letter to Nature.

I have three criticisms of the paper. (1) I think slightly more experimental
detail should be provided in places I have noted in the manuscript.
information about the fractionation fa required.  A Table along the lines of
the one I have suggested (see ms.) would help ruimwrise the data available;
in addition, it would be helpful to the reader to know how much of th DNA

What wae the composition of the intermediate fractions? Was the fractionation
done several times? Was the extent of fractionation reproducible? I am
troubled by the rather poor fractionation of the heterochromatin in the
trrnrformed and revertant M. agrestir.
fractions are (presumably, unless you have evidence to the contrary)
euchranatin, I don't see why come viral sequencer are not detectable in those
fractions.     I think the conclusions you draw (a) about a "preferential"
integration oita and (b) about the likelihood of "post- transcriptional"
control are completely unwarranted.
in the cells descended franr only hso infected cells - l.e.,  the 3T3 cells
originally infected with 877 and the M. agreotis cell originally transformed
by B77 (the revertant cells baing daughters of this cell).  Hence wa have
looked only at two integration wants (unless one prerunes that viral DNA
can be excised end reintegrated, a hgpotheais for which there ia no evidencd
and it happens that both events occurred in euchroraetifj fractions.  That does
not cncludhathe pos sibility that the event is randam.
could come from looking at many clonee, or at DM from mass cultures of
acutely-infected cells in which a €erg@ fraction of the cells have acquired
viral INA. (b) There ir no evidence here to aubetantiate the assumption
that the eite of integration determines transcription and that therefore
virus exprersion must be regulated et a post-transcriptional level.

It would seem appropriate to me to submit it as

It

(2) Wore

ended up in each of the fractions (incbding the intermediate fractio s

Since a nrbountial portion of these

(3)

(a) Viral DNA ha6 been found in euchromatin

An aarwer to that

On the

contrary, in our studies of the revertants derived from RSV- tranaformed
hater cella (aee the enclored preprint, In pram In Viroloap), the
reverted cells have lower concentrations of viral RNA.
be true that In the hamrter or the Wlcrotua cells that post-transcriptional
factors may be operative.  But I don't want to rign my nsme to the proposal
without rome evidence for it.

It may of course

Thanks for sending thi8 to me, and plea- let uta roe the final version before
it io submitted for publication.

Yours,

Harold E. V8rmu8, H.D.
Aarociate Professor of Microbiology

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