1. Att,xgted to pre::ent cvidcnce of' ,t!.>~! ori~5.n ~.nd be>r.v?or-- of insta2j.I-jvty
at a nuxbcr 01 '-nom gene loci in maize,

  2. I~luc~ of t`\?.s c:-~nfri2,ed to ~2,~;s whex Ac-ccnt:2oZled the ,yenic action,
This done to kecr, down the need for too nlucl~ ;xxo-my of  5ndivldi;z.l cases --
a unified theEe fo:? the Dreso2tation of cs.scs.
                                _.

  3. iiave  s 7-y. 0 52 $hat i;oth 3s and Ac are tranS~3Osible units 2nci tb2t the
tranS770siYons or,cur in  so---:2ti cells at certain tixes
of' a $issue, under co-ntrol o:P AC itsT\lf,            dv.ring tile develoxxent

L!., iiaV17 shoxn th.at rxutabllity arises wher_ Ds activity a :`cars at the locus
of tkzc !?noyrn :g:ene in c ::se of c-lrJ. and bz-xiL.
5. ir avc  s'Llown in t'::esc cay-,s 'i'llat 171Utation at the locus is a,ssociEted with
an eve.tit involvi~ll; Ds -- loss of 2s activit:- conici:!ent 5& 2: the mu%r,';l.:~n.

6, Eave sho;rr? 5hn-i; chzn~e-;3 in state 0c:cur at z3s, w&en at the clocus of
c-ml 013 bz-&. or at 9s in ot5cr locc"t~ons.

7. fiave indica5sd t1:e stabilit;;s of the states  of c-ml an.6 t?-:e s:rccessLon
of  stF&tes t1-g,t occup -- o,-,e fro2-1 tl:c ot?ier,

  8. ?de lfnc!~~ thzt events at iis and also at AC czn 1er.d to a physical clxmye
in the cZ1-0xa.Li.n at tile locus because of : diccnt:<*ic fox-a-L?'.on, i::v$ersioxx)
du;;lic:-Mans, ring chroxoso;::e, translocations etc, th.?'; have `Seen o'?Sc:'ved.
hidence ;loj.p:ts to scne chcnp that rr sul-ts in a p5::sica.l f#atleratlon o? ::he
chroxtin xate~icl:; a'; the locus,   :l;vidence sugCyests t-hat trancjY?os~.t?ons
a-rise from ti:is ??rocess,
                     .

II, The questiona:  ifhat do Ds and AC renresent?
CO::P~C) SCd Of3                           Xhat 3aterial.s are t:-ley
               .   Cow do such units arise in the nuclear co--:~l~:le~t?   Ihe: e do
they coxne l'ron?   Ax the:: always there 0~ arc they SO:-C tl2iTlc IlC?iil:7 CT t: ted?
Xhat can we find act about the3 that ~~-11 help answer th<!se questloxs?

III. The above qu~2~tfc:~s take us baryl; to the v:;z-y, firs-i; discussion in t:~li.s
series:  the sudden ap?et:Fance of a great I-nany newly arisen mutable Genes in
the ;-ro,gc:q derived from a set of m-lants, ep?c;.> ot ~J',ic`e'
breakage-f'usirn-bridge cyle,                   hzr! unde:-,yone the
                    Also,  tile &jffc~I;gces in t31e rw-Li",hle cc::ditZon:
exhibited bg two branches o:'i` the same -:lant -- one ;;;iy!.q a
not havfrig t- 3 s rmt~251e.                         i-;V.k able ,  the oele r
                  Some correlatlc:?s bet:*Jeen this cycle and the
origin of tile xt"ir3le loci sx?spected.

  1, Th5.s history -0 no n:-evious i7vcst 5.ga-t' ens mtrcle on plants that had
undergone ti?l:: cl:royosr:~e- ty---e or ~rcal~a2e-fu-sion-Sri~--e cycle.
  2.  Uhat is t2.e pnrticul2.r s$gti$igance aXwt t-:is cyle tha? cci 16. :-reduce
these new mu:.nble loci3   Why night it be r-s--o'r,SiSle Bo-_? initiating tne
mutable genes?



IV.  Zxarii~~tl~:ns q"*3e ot
                        _, c. L.    I-be c:?.r-----osorne constitut?c.ns in a number of Yne
plants tha-t had undergone the chm::?osone tpe of b,f.b, cycle -- between
250 and 300 dxamined,
components of        Revealed a striking alteration of perticular
        the chrc-zosore co:n-1ey.en.t and t=,? s quite unex?:ec!:ed.

  1.  Altsrati ns involved some kinds of
elements                         clw.cges in the heterochn:-r::tic
     Of th?e Ci'i;_"'~lG~:'!'lC COYX-le:TCEt , mnvcIvlng cIl?:'c~7iGsc-?es  other than IT:0 se
0-T chrox3so-::e 9 as well as &'T b-,~~e i.n cl:;-y..- ~:r_lc 9,

  2. r;l' LllC regr;.ci1-,,c,  involved:
chroxo SC zc s           The centromcres, the knobs, the ends of
              3 t?nd the nucleolus organizer on chr:,.,osoze 6,

cc.1 ap~~earance ol" these coqonents.

:->ost-L;' 0i.s tlicy occupy in the resting nucleus.               4       t
"V                                                                    - "

    f'o~s that occur betr:een the krmobs and between the centrone::,es,
in normal, TTT%!ng nuclef,

V. The expected typos oi' changes that shou!_d
type of b.f.b, cycle:   On board.        Se n 1'0 duced bg .Il:e chrc:-:!o c or;le

1. diagrams on board.

2. If' healing of broken ends OCCLITS in the snoroyenous cells or in their
ancestor cells, the conztitutlon of the chro:!os&es may be examined in the
resulting microsporoc ytes by analysis of' pachytene s.i.ages,   fhi s  col:ld
show what is 3rescnt in the chro-?oso-es 9 that had undergone t)iis cycle,
Would ezvect du~lT.c~tions
3. In a number of cascg deTiciencies, reduplic:ltlons, etc.
the diagrams, w:re fo\:nd, , -the exrected types of alterations, as shown in
4. In about 40 or 50 cases other tyes of aberatior!s owzs rved        '
                                                           :.~j-t l--z- n  t]
chro..:.osoze cc`i:l-- lezent,
shis cycle.      'hesg not COT&& in plants that have not unde-gone

VI. The classes of abnormal t>Tes 02 c?~~~o---~~s~i~.e alterations.
broken end or the knob at                             Involve the

0 tklcr re<q: nns,        the broken end of short arm of chrc~oso:~~ 9 with
        or t5e centromcres with other t~en'Lro7cres or knobs.
The types obs:::.ived:   Classes.

1.  Ccntroncre  to centromere abe,rrat'ors:
         ,q., z

le


b). -- Lnvel*sion in Ch~Oi7lOSO;~l~ 9 :

3. Knob to knob o F broken end to knob ee abcrrat 501;s :
4. 3ing Chi'O*YG s@ye q .                 67$
                                   A.        *--   .A;>
$1. iAlplic2tion: EL-

d). Translocation of end to short am:    `c <I 6
                                                      -  ---k ._ .-.-. id\

4. Knob to kr?ob and centrome:: c to cen.&romere:  `CT /

                                                                 . .
                                                                 ,    A -
                                                                     d--`:

5. Knob or broken end  of chr. 9 to knob on anotllcy ch`;`: oso;le

_,-. ,I
,f
/: 1


VIII.  Conclusions:

-.    0
    0

  1. Quite obvious that many otiler aberrations occurring as consequence of
the b,f'.b. cycl.e than that which co?Sd be eTxoect;ed.

  2.  ~Qrite obvious tl:at t`rre majority of these unexpected aberrations
occur to particular elements i:~ the c5w:T~o+~~*
knobs,                     vLj.....ie cnz-r~lcmert -- ceqtromL:es,
                                                                           LA
   nucleolus organizer and the end of chrc-::oso:r,e 8 short arm.

  3. Qucsti7n:  Is t:e:-e any relationship bet:;een the occurrences of these
aberrations and the origin of the muta'ble Genes?  Can we test this?
4. A single test made, which :&ll be described.

-----

The al - Dt relationship ancz the test for indUCtiOn Of Dt.

2, This  pececessi~7e v~-~-TT stable,
stocks not seen; " &x&mts by  Reversi?zs to Al in the usu::l ;e:retic
                Stadler to Get revcrs?.cns 57 r,adiaticn not

successful a7tliov:~-h many- tl?.onsar-ds of cells irradiated.
3. The origin of a mut~~hle a1 locus:

  a). Randolph stocks:  Black llexican sxeet corn. A1 Al
  b). Qne nlant -- on self-collin:ted e;r  Ice :-nel s  tl7-,?.$  vex cola;-les
arid those &at IJc:'e color1es-s v~i-ik dots of'color were se.~regatinr
                                                                           6*
c), lkoades took over the ,crenctic analysis.  Piorough analysis
period of a number of ye-rs (1936-1941 and lntcr).                   O~TC;-. a

  (1) A new mutation to al fa~on Al
  (2) A dominant present, Dt for do-Lted
$Eep; dot;
  ,tt.crn of dots of color in the i:?rnel   Fry-, i c FL
                    &d fine made tXs al mutate to A
                                stp~al.:s i;y.--tey.e pIeant.   IL

           s of color k;ere dee-::
Ver~y gel.7 early mu-5s.ti.Tns; very-?ew mutations to the pale color.
                with the diffusion rims, previw~sl~ deccribed,

    (3) cccasicnal ant-er with rm%ant tissue or secto;*
Pollinatil-:ns from tl:em prod-c.ced the g er::iinal mu&t-~ ens for of mutant tls sue.
These nroved to hzve dominants %-la-t :.rcre no&          sr:br:ecyuent study,
                        or all exactly like tl?e ori~!nal --
all rcrcro hi.T!;_:r alleles of the Al normal locus,

ver7, (II) Tested Dt on the old krolrn recessive,   C,n,used it to mutate in the
    c T same i22pnO 1' '/ s
   ( 5)         the one vk~.ch occurred in
     The dosafre action of 3-t:
     - <--                .th.2 Black i-iecic,zn Srreet Corn,

mutation                Increased doses,
     -- more dots, ,geometirc in s~~-*ic ccs,cs,     inc~~i:ascd f:.~ -uency of
                                                 .I _.
    (6) Obtn5ne.d                                                              .
           so:.`;e al recessives tllrough tllis process of be,-r; :rltT-i Dt
that no longer mutr.t&dnin the pr;-i- sence of D-t;,                            ----j
  (7) Located t is dominant, Dt, adj::cent to or
the 7"ort arm ot chrc *os;`:ze 9,             in the knob te minating


II.  The reaccnini-;; t;--at lead to experiment to yrodu.cc 0-i; by the b.f.b. cycle,

1. a1 does not xutate in the absence of Dt,   It is vey stable,
2. If the b.f,b, cycle makes evident the controlling fccto-,-.E, s:?ch as AC 0"
Dt, and does so because it distibts tile heterocl:.r+o::z.tin OT its balance in soxe
manner, then we shou`r.d be ai-le to get evidence of the origin of such a Dt
factor if a7/al
              A_   plant s have chr~c~-- os :zes undergoiy2 the b.f,b. cyTcle*

  3. E-ds can be done xadily, as will be &own.
4. Xo~17d eqect to fLnd mttations. to color -- but in sectors and shoC6ng
dots of Al in these SCC~OFS.

   Also, we lmoxq have otl:erJ states of al_-- found by &ffer to h>ve
arisen in the Dt stocks.  These give t;mes 0:' :r?~'~atTons like t ose shorn
earl;; -- e'~-ply sectopials for> both full Al and for pales, and vtz~icus
in state arise fxq,uel:tl:j from them,                                c :t: I.2y-e s

III. nle test p,-ocedure:
1. vne cross:

Female

2.


5.
ii'110 se
dupli
full

6. The control test of ti?is functionizCg:

            Ferzle
    PFFI
          \ \  L I/c-

      '+lc r csults:   See e::.r.
                                   -....^--.
                          ---.zxz
IV. The results of tkis test:

315 ears obtained;  cor,ta?:~ed a total of 93078 kczmels,
117 k::xels with spots of color -- the Al
      All were dots.   No pales,     type wit': diffusion rims.
                   no la.rge Al colored a:.-es-s,

     yrle se 7;; ye sent on 86 diffe-ent enrs,
The rumbe;- of dots per kernel:

93  -- 1 Al dot orlly

9  mm  2A 1 dots

G , -- 3 Al dots     ;

6 -- 4 Al dots ),           *   &

1 -- 5 Al dots  (

2  -- 7 Al            i
         dots

1  -- 17 Al  dots i

1  -- 811. Al  dols  distributed  over'  thr:  whole aleu.iyne  a-aexg

The apT~e.a:~?.ncc of the dots  ;riien lore t-an OEC r7r.e :: nt ,
'ih?e rcsexblance to the dot: ~~~oduccd buy 3t,          in sectors.


VI. ~xpcrimnt positive,  S~hows tiir?,t ilt-like effect can 2p-2~27 in tissues
that are unde::goin~ the b.f'.b. cycle.

VII, The pt3"ose nce or" Dt factors i2 straizs of mize:   'I" ose fro3 S.%.
examined:

VIII.  T:?e indications so fnr, suggest th?-t
present 0~ cm Se a.-:dc evident in nuclei.
be discussed 1.;3.te~~