Interpretatlen Of origin and be?lavior of the ccn:rolling systems.

I, Hevtiew of previcus discussion.

  1, Purpose was to show th-lt s7~.stGms present that control ;qenic action in
manner not quite like that of Ds - AC or that of a
alike)                                        1 - ijt,C>M.c'S a e much

2. These 0th~~ s~~stcms, hz.ve basic pattern however that is similar --
control of genie action; evidence suggesizs thai; segregations Of controlling
units occur.  "eiotic segregatT.ons obtained and linkages noted.   Results
of somatic segregations similar to those of meiotic se~regati::ns.

II. Controlling systems revealed by tne b.f.b. cycle.  'oncluded that they
do not arise denovo but are presc>nt in t'ne normal nucleus -- function in
some p:: .cise way du:-ing the develonment of the organism.

r a>. Somatic segregations occur, changing tile constitutions of the siseer
nuclei ~3 th respect to the control1ing unit.

b). These changes result in subseaucnt controls of the action of s~:ecif'ic
genes.

  c). For the genes to become active,  sosnc c%nge must occur at the locus of
the gene.

  d). Some mechanism must be present in the nucleus that init%$iates these
changes in nuclear orpani,ation and constitution,

  4. Believe tills mechanism a ssoci, ted witil the he$erochrGz?-Lit elements of
the chro;nosomes -- primary initiators of the changes that subsee.uently occur0
  ?? o The pattern controlling genes, the "switch" genes, etc., may be
expressions' of their action.

III.
series The recent studies of otrlers showing the mechanism outlined in this
    of discussions:

1. Work of Brink and students on the var. I? locus in mai?e:   iiave cGme
to same conclusions
exuressed,       regarding the controls of the pattorns of varie:z.tion
        l'ave found the transposing units.   i;ave found th.e twin
sectors of t'ne types described in t!lis series and ha::e investigated the
progeny derived from them,   Confirms the story here pres`nted,

2. Peterson, in mai=e, has found syst-,m cc-ntrolling vn3ecat?Gn t1:at also
a:-;ln ezrs  to Tallow
genie action;    the -;ain conditions here discussed i- the controls of
         transpositions of
respects to AC but not AC,    the ccntrolling unit cr m>arable, in Inany

3, 'iZle studies of the "Zi'
Rinton --             mutation factor in ~rosop3ila by Ives and
types    suggests controlled chances at certain gene loci and controlled
   of chro-Tosonal alterations that occur at speciefit loci,

4. Soma.tic crossing-ov r as observed by Stern,
suggest a controlled s;nL                   SO-~?:: cas?s strGn~elTT
            tiqJem in oporation here tG ,Tive pryecise t;.T;>es of`
exchan:res bet?:een certain cilrGmGso3e components.

  5.  Many s*eggeztive casts in literai;::re.  'ihe cyt&logical cases  are
I?lOst inscruct&ve in 'cl-is respect,  Review will be ~;iven of rGp:,escntative cases


IV, According to interpretation riven -- that the effects described rey--yes!-nt
those nor-wily occurring in develowxent -- rare must account fos: their
appearance in the stocks used h:ere,

  1. If t:l:e Drocesses described of ccn-trol of genie action occur in
standard strains, C>eir presence not readily revealed.  '-his is becalisc t2ley
are activ& at particclar times, crntrolled in 1;:i.s ::espect, and thercfo e
not observed as s~~ecific pits unless the?7 a-e called modifiers.

2. If the ccr?trols not regulated, a chaoitc situa.$!.on wu 2.d occur,
regardiq: e-cne acti::n, the regulaticn of develoxxnt,  the naintainence of
mecles, etc.


VI, Diff'ezqcnces in nuclei of an orgCanism with rcga?d to the number of' sets
of Chrn-~-.QSC-".CS prescl?,t:

  1, Zygote -- starts out with two sets of ch:?c: :os"ms,  one Frol-i male and
one from f emde.   DUTPi?~ developzlent  changes occur in the number of sets
of chro ~oso:2es sSrit:lin the nuclei`,  6ese a;e ccntrolled changes:   ce:~ta.in
t:?.>es of cells having certajn                               Th e
set may inc?ense --       +ecific types of char-qes in sets.
nucle..        -001~: plaid nuclei; OT the set MB:* be reduced -- to hanloid
    These changes
organism,        occur at specific times during the develo:ment of the
      Also, different mentods of cheq;e in set nuzbera ocmr.

The i.ncreasi:s ii? nuiibors of sets:" By r7leans of endomitosis -- no mitntic .,,
division fip=res.
  a).       Various met!-!ods of accoq~lis~~irg this endomitosis,'J zusions
    'The degyees of incz-ease :  E'rom tetrep&oid to 2,000 plaid,

b). !&e ty-.e of a12uc:i:`sance of chrc;::~oso-.:ies:
                                        Polytene ty3>e - szlivaries
   or diffuse t:,rpe -- fF::quent; fir, cc~bi:aticn of both.

b). Increme of sets followed by deci~casc  of
examined case to show the mechanism involved.
metamorphosis period.

VII. iGfferences in nuclei with regard to certain chrc;"joscms of the
complexnent:  Loss of ch?romso;~?cs at
Non-disjunctions               specific divisions:
            of ce7taS.n chrc~~.oso:~c:s            ic!xnlx~xEgF~k~
of accorzqlis`3.ng tie same.         il:. cc?:.ain divisS.o::s;  C th c 1' iye -I;'-, 0 d s

1, Best workedcase that of Sciara:
     Loss of chm :osc:z~s at mitosis Outline on boa:.d,
    Non-disjunction of particular chp- :?osoze at cer&z:.i.i-, division
   Pasage of chi-0: IOSY:~~ tnrough nuclear m:!;llpme
     The exDeritrents                      -- 'ni;T.-;mlTr c cnt roll e d .
                  that skew l,Jh.iCh. aayt OP
       for the =.henonena.              C:~r~~Aoscy.yle is rcr::o:-sible

      When is this effect iq:>essed on centroncres3
   'Gfiat mcclzmism makes tl7e impression so precsse?
                                                              -.

2, The B-type chrc~~~oso~-~o s in ;m!lants.
of these chri- ;-jos!,7.e s.           Very h:'.ghlp ccntrolled non-disjunctio:
   a).          Occur at snecif'ic tines and with
     Examle of this be`:c.vior~               s- ecific corseSquences.
    Ji~&x~ on bop.Td.      -- the B c~~~~c~-~oso::~c in mize :
                .:

     Control exerted at centromere
X chromosomes in Sciara.         rogi~n of B-c~~r-oxso3e, as in the
             The trnnsloc;?.ti.::~n studios showing -S?is,


VIII, Differences in behavior of sets of chmmosc:n.es within same nucleus:
                         6,. pn, CcuBpc%4 r 2% +
       White .   P1onarthropalpus.   Spematogenesis:

IX. Piffcrences in a:>)nwrance of diff:>ren% chromso-:es of a set in diffemzlt
stages.

a). T'ne small clrr' cscrae in salivary: glar~ds of
      II      II         Ii            tf      ii

Yhite,
"elland

b). The alternation in condensation of particular C~TO :osoy?es:

X. Differences ex--ressed 7;;; individual pazts of chro:!osozles 111 diffc:-ent
     cells of an orcanisn:

Ai.  Pne chror.!ocenter regions -- he?,eroch??or?_atin in Drosophila -- too
     well kn0x-m to cozmmt on.

a.  Condensed versis diffuse condit?.cm of                                 .
                                se,qxent of ? ?????? ????? o
                                                            ._

  3). Host exciting recent case
diff'cl-ent species studied,     -- that of Pgvan on Zhyndhisciara -- two

  a). All eggs laid at one tine -- C t2in LL~ mins,
   b). "e8rly all lrrlse of one sex
  c).All develop at same rate - 4.2 days to pupation.
   d) .                            Conmon pupayius fomied
    The changes occurring to snecific bands at ce--tain ti-zes in
development in the different tissues;
$0~ the tissue involved,          change at particular bagd mecific
   4. One ty?e:
particula- band;   at certain tine, increase in D.13.A. and swellfing of
z          Separation of corn-onents of the polytene bands --
ayge Puff regicn i'ozmed.
Return to dense band,     At certain stage, shrinkage of puff re,Tion,

started,         but now bad very much wider than bef'o--e the 3::oces.s
    Increase in D.N.A. relxalns?   Intem~~etzlon:
genes of t?>is band, specifically.             Nultiplicrti~m of
                   3i?fc:-ential beh-vior,


XI, Conclus'ons on nuclear composit:ons i..l organisms:   ?iide diSfc:Tences
among the cells of an orc"anism with regard to the nuclcxr coq>csit: on.
Differs with ros-3ect to sets, parts of set, p--,rts of c~lr~?~,I~~::c:~es,ewsn73a~~ts of
so small a:: a band in the salivary ty>e chrczosnme.

  P1echan3sms :  differential behavior at certain mitoses:   Lo::ses of
certain chrc:xo,noi.:es ;  Non-disjunctions of controlled tye at certain
divisions,   Pas sn,T:c of chrc~c some t3rou~h nuclear membrane.

XII,  Differential nuclei resulting fro::! specific divis'cns:
                                             ._                    on ge_n,ic
level.

  2. Tetrahymena -- mating tyx-ze reactlcn:   Sam5 as w.mmoeciux except the
division is not as pl'ecise -- fir2.i; or second divis?on of macronu&leus o
                                                ?

3. Case in Glomerella where matin,? type "mutation" occurs at specific
time in develo-nent of ascogenous hy-phae,

XIII, The effects of species crosses:   Often quite bizaar,

  3, Changes in the chroxosc-Fe co:xlcz:~ent:
reductions, occur in tissues that do not shoa
individual srecies involved.

Varl.ous pol:qloid condit.; 3x3,
suc3 rca.ct~'ons in the

2. Case of i"ietz in Scinra:   Cross of s.       x s.

The m0 saic salivary gland:

3. Species cross in Nicotiana. A. x B.   Backcrossed to A

A.A B com:3lexent:  g chroxoscxes eliminated ? ???? ? ? ?? ? ?? ? ? o

3. Altorzd ,q?nZc action often noted;   Variegation a?-.crrs.

XIV. The constitution of differentiated nuclei -- as shown w&n tnese
cells forced to divide.

  a>. Treatment of root -- chemical (indol-acetic ac%fd&.  `-oes not affect
behr-vior of chro:~oso:~~cs                              Porces
nuclei that are fully  in the nuclei that regularly divide:
               diffcrcntisted to divide,
chrc.osomal aberrations,                 Theh show a vrrietg of

endomitotic division:    Cne type observed inc e2.1 that had undergone


The effects observed are very much like those produced by Ds.

XV. Ds tme behavior in otll:.r organisms than maize:

  1, "etZ - Scinra,  Certain chrc-:osome, certain band reg$on -- bretlk
seen in all salivary gland cells,
controlled,            %C;;red that t--is WCS genetica11:-

2. Hyacinthus - Darlington,
development of the s;3orocgtes,  Break in a particular chrcmosoze late in
                     Genetic control

3. Vicia - Levan  With certrin treatment, break occurs at the
nucleolus organizer*quite predictably.

4. Dreyfus -- break in arm of particular chromosome at certe9n dj.vfsion
in the spermatogenesis of                  .

5. Gatchcside - oenot:--..ra. Xis
translocztion: 7            case of pos4.t:i:;n
       -lvidence much like that found for Ds effect following
                                       Chro.:,:o .w ,le
ckwwso;ne dup_?.fcat! ens nilc? deficiencies of certr.in rdg<on of     by 2 1~s ;
in the tr3nsloc-.tion co:yTex,                        a chr0::~ SCTI~

XVI.  Conclusions:

1.


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