Pdrt if a letter from Dr.0,T.Aver-y to his brother Roy O,Avery, dated Ray 13,1943,
just after hi8 retirement from the Rockefeller Institute, when he wae oonaide$ng
  moviiig to Naehtille, Tenneesee.                                                       I
                                                                         I
                                                     
   %oth Dr. Qae&r and Dr, RQere have been pery kind and have insisted on ti
staying onI protidfng me an &pls budget and technical a.e&tant to carry on the
problmx that I have .been studfing.  I have not &ublished mythIng about it indeed
bare diecuamd it only with a few because I aru not yet convimed that. we have      - -
  mffit+nt evidenue as yet,
  It ir the problea of ths'tr&fomation of pmMooooaX~&pe% You will meal1
that Orffflth in London, some fifteen year! ago daecribed a teohnique whereby br
oould uhango one specific type ink another epsoifls type $mugh the Intermediate
R iona, For sxamplsr Zypb U-7 R+ Zype III. Thlo he aowmpliahed by-itijao-
ting micro with a large mount of heat killed 2!ype -III cells together `with a small    -


. . iaocs~lunr of a liting-R culture derived from Zype II.. @e not& that not infrequently
the mice 90 treated died and from their heart blood he recovered liv%ng 18neapuulated
  Typo III pneuIBowO~i.  Thie he oould accomplish only by the uea of mioe,  89, failed
to obtain transformation when the same baoterial mixture rag imubated in broth;
Qzifflths original observatione dere repeated and wnfirmed both in our leberatory
  md <abroad by Neufeld and other&  Then you remember Daiaon,with UII reproduced the
phanomenon in vitro by adding a .dash of anti R eecum to the brqth. culture.  her
blloway used filtered extracts prepared froni`~ype III aella-in the abeence of formed
hnhnts RI& Ddllular debris Induced fhe R culture derived from Type II to. become
- a typical lnbc,ptilated IIIcpnsvrnococus.  ?j&s you m&y renember involved several `and
repeated trmeferrr in tkum broth &ten aa many ae five or a%x before the change.
  ofxurred.  But it did o.ccur and -once the rearrtion was induced thereafter ,wdthout.`.
further addition of the Inducing ex%rarf, the organhms csnfinued b produa'e the
Type III capsuts that ie to- say the change was hereditarygand tranamfaeabls in         '

  sex&m in plain broth thereafter.
  c For the past tire ,r* flrat vith -MauLeod and now ~4 Dr. H&arty I have
  been trying to find tput ,&&.ie the chemfcal nature of thr eub`stanae' in the baa-
tsrial axtract WM.& in&ca$&e speaifiu chmge. The crude extract Type IfI,.
is full of capsular pol$mcmlxarSde, 0' (amati;a) oaxbohydrate, nuoleoprotalns,frea
neculea.8. a&is of both the ;;east and thyme typs,,Ugidr and other dell conefltxlb
nts, Try to find in the complex mixturer the active pticiple!~ Try to. isolate
. and chsmlually identify the particular. wtbstance that will by Itself when brought
into contact with the R-cell' derived from Typ`e II causes it to elaborate Type III
.- oapisular pol@wmWrids and to ,acquire all the EtristoUXXtia diBtinCtibn0 Of the
6ima 8peciflo type of citlls a8 th     which the extraat was prepared2  Some
  job, full of headaches .and hearth     Rut at. last pefhape we have
                           The
                                                 it. /
-.aetire substances is not digested by-az$atalUae -tryprtio or chymotrypsin it doe@
not loue adtivitp when treated uith cryetaUim!i ~b0nuul~6a which 8pecifiUally~
  bree@ down yeast nucleic icrid.  The Type III polyao*ide can be r.aPa.vqd by
dig8tiOn ti# the spotif% ?'y'p8 111 enxyma WithOUt &a#!3 Of b'WSfOdX3g RUtiV-.
ity of a.pot&xt extra+. Lipidr can be extracted from iiich extracts by aloohol
and. ether at a ni.nus `Z" 0. wlthout im tiring b;lolo,g%cal aetftity. The extra&
-us& be de-protainized by Swag Method shaking with &MiEom-ond onnyl afdphol)
            4
unt,il proteb free and bittrut negntht~  when extraata, ti)eated and purified to
to thin extent, but'otill contaSting Wacee of pmfein# lots of 4 oarbohgdrrrte,
and nuulttia aoida of both the $eaet and thyms typeo are further fraationated by
i  the dropvise addition of absolute ethyl alcohol an fntereeting thing oumars~ j'     _
l&.mn sleohol remhss a ooneeritration of about P/lO,tralume. there laeperate8 out a
c fibraw sub&mcrs which on stirring the mixture mpu itself. about the gZa86 rod
like thread on a spool and the other .fmpurities 8% be+ad, a.I gcavwlar PreeiP-
ita+Ze.the fib&l8 materia1.i.s radismlvdd and .the prooess FOP-tad m~mal timea*  *


em 2-         AC:           I
                      . ii):;.    ' ( ,I ,
                                 .-

In bbti, Wi-8, eubatance, Is highly r%mtIv% and on $Pmonixqy analgerIa conform
s UlOfJeljr to the th'eorsfiual value8 of pure, deeoxyrSo%% -olgIo acid (+&me)
tspe (Idhb could have gtmeeed' it) thie type of neucleio aoId ha% not 4~&& q
fraowledge bea reC~gni~%d in ~~%WWBCOOCWI before though It has been fow@d, in
other baataria.

     Of @ nu&ef Og OX'U~S ~~IZ~WS preparationo from rabbit bone, swine tddney,     ,.
  dog Inf~~fbz&amwe-end pneumoaoacci end Praeh blood serum of htman,dod and
  mbbit, Only #ose cent!&nirxg active depolymeraee capable of breaking down knowa
  authemfiu emp>ea of dboxyrlher nuclafu ahi hnve been found to deetmy the
  aativlty of o~&mabet&cel - Indirect epidence but suggmtivq.thrat the trensJro"nning
  prino&pla a6 keoleted may belong tq this alaee of chemical eubet$noe. We hare.    _.

-. - ii5olatxi~ighly purified. esbetmoe of which ae little aaS&.:~erf 8 mie
  active la bduosag tr8nsformat10a,  In the r6aotioa mixture !,$ulture, nod
  rwreeente I' d$lution ,df one part ia a hundred tillion - poteqt et&f ?Ji
  hi@la epsciflu.  Thfe bes not leave much room for fmpuritiee but the &.dencre 1%
---not good fBxJu& pet,                                                                    _
                                `.
    Zn~dilutions`of on% to a thousand the eubetanae ie hi&ly'vIemuo ae are-
  au42mntIa preparatione of deeoxyrIboee neuolelc-aoid derived from fish epem.
~- Prel~ utudiee wI# the ultm~ti&ftige Indicate a molecular w'eight of appz-
  oxi.rfmtttly fjoo,ooo- - a &$lp pwlymerieed eub@anue.
     We ure nor `planting to prepare new bktches end get hdhsr evidence of purity
and bmo&m$ity by me of th~ultriOent#`ttge and electrbph@@.e.  Thie. will keep
  me here for awhile longer If'things go well I hope to 'go up to Deer Iele rest
  awhile WW~-Q-.C~~PC) beck refreehed and try to pick up loosti.ende in the problem
  ~d.writeupthenork. " .                              
                                                                           . .

..-
   .   If we 433 rightcend of aourefi that Is not.+ *ro?m, t&xi it metie that       :.
WneucleIc:acIde ate not rn%r%ly etmctially Important bet @nctIonally aotive-
eubefsncee In detctining the bi~chem$cal aotititiee and epepific chafaccferI&ue
  of oslle end that by ~eene of-a &WTX ch&ical aubstezme It i%,poseIble ta induce
  predictable end heredit&q changes in cells,  Thie la somethJ.ng that has long been
  the dream of genetic,ietq.  The mutotione they induced by ex&ay and ultra-violet
  are alwnye unpredictable, &n&m, mid chance changee If we prore to bi righ+and
                ?a big ti - then it mane that both the chemical natire of the
         us i's known end the ahezlical. structure of the; mbetanoe produced
          the form be3mg thyxuze rnmlecic acid, the latter Fgp% III @lyeac~-
  charideo and both are-~urzk5~lIa&tti In the daughter celle and after

,     Innumetible tr&efere d&out Azrther addition of the Inducfpg agent the We
   active end epecIfIc baneforming sub~.ance can be r&cdoered far In-exoees of the
      mount origInally ueed to, Induce th'e reaction.  Soundo like + *Irue - may be a
    gene*.  &at with mechanism I 801 not now COncerned. One step .at a time and the
    flret. stap is what is the chmtical ?S&W% of the jWan%formin~ prInci$le 7 &m%
   one else can work--out--thereef$f coaxrae the problem bflstl6ti tit?--implIaation%r ft
   touche~A~Iochceni%try of the th)mnte type of mu&lecIc acids a&ich are `known to
   condtitute the major part of chromouxnes but have been thought to be alike regard-
    less of brigin end epeciea.
   .Imn end uarboh@rete Bgn  It touches genetics, enqm%)hamfat~,'cell metiB!ol-
                          8010.  But to-day it takee a lot of vellTdo~~e&d
     evidence to convince anyo e that the sodIm ealt.of deao~~~oa%.-~c2e~~c~I~~
    protein free, could poeeibly be endowed with m.mh biological3.y active'and eP%cifio
    propotiee end that in the widenco we %r% now' trying to get. It ie ldte of fun to
  T blow bubblee but it is wiser IXJ prick than your%& before aone one elee trI%e ho'
       :<:;

*           .

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