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