2 iy becture l. Vornell University. tuesday, November 16, 1965
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aspects of Gene Vontrol in Higher Orgunisms.

Li. Influence of bacterial and phage genetic and molecular studies on
genetic and biological concents.

1. Basic genetic manterial: DNA: its bases, its organization; its coding.
2. Mode of operation of the genetic system: DNA Replication-— DNA polymerase

DNA transcription; RNa polymerase, base sequence of mHRNA, mRNA
transcriptions through ribosomes; transfer RNa, #ssociated
enzymes. Proteins formed; specificities.

4. Types of genetic components in the bacterial an DINa:

Structural genes

Genes for transfer RNA

Genes for structural proteins

Genes for ribosomes: B. subtilis:

git

=<

 

5. Regulation of action of genes: Induces and Repressors.

Ihe Operator-- reading frume of structural gene
Regulator genes.

Urganization of structural genes: Operons

One Regulstor: Positions. Number of senes: thair relations
Operon plus others: one regulator. Arginine.
Regulators: adjacent to operator: khbac locus.

The activator component: Regulator: positive: Arabinose
ABDO + &§£ The C: Activator.
the feedback mechanisms.

6. Regulation at the gumekx gene level: not yet clear how this operates.

7. The forgotten type of regulation: the H mand Hy duplicate geres in
salmonella -- will return to this lat
4 NAL
the host range: Modification ef phage genome by host.

8. &ffects of episomes: +sol:ted episomes; the cortrolling episomes
(Austin) (Dawson).

9. IMPORTANT: The acceptance of differential regulation of gene action:
oneness
enormous Stimulws to reconsider mechanisms resconsible for control of gene
action during diffeientiation of higher organisms.

Although the basic components are the same: DNA etc, the mechanisms
controlling the action of the genes in higher orginisms are far more
complicsted,. This related to the very highly organized, com;iex bodies,
the chromosoves, and the highely organized nuclei.

the extraordinary com lex organization of the chrouosowes and nuclei

probably related “to mechanisms controliing the action of genes during
evelopment.
fhe various components of the chrovosoves and the organized nuclei
probably represent the components behaving like those of a computor:
higiuly organized set of eensequ tive events, each related to the previous
event:
ay Example of this: @One must consider the caterpillar and the moth:
¥' “oth are extraordinary complex individuals but utilize the same set of
genes.

«¢' One must consider polymorphism: mimicry patterns, etc.
fhe computer: the ‘Swithh Genes": One or Two mendelizing units switch the
“computer from one sequence of interplay of events to another sequence,
using the same compiement of genes for this.
* nd a aur cued Bia aid
10. We must consider that regulation of gene action in a higher organism

is a higniy programmed sequence of events from egg to mature individual.
The large number of different compsnents of the chrci.osome are probably the
component elements in this programed sequence. yuestion: Wht do we

know about these components of the chromosome and what do we know about
individual mechanisms in the system?

Il. The Chromosomes and their comyonent parts: Cowwon off aueultailid Ong Bui . Ly

1. Compared to bacterial chromosome, the breadth of the chromosome is
enormous: clearly visible in the light microsoope.

2. Number of DNa molecules within an individual chromosome: Very
recent investigations, taking DNA from the chro:ioso.es, suggest that

yd
each chromosome has relitively few DNA molecules. (8 to 107) (c )
3. The non-DNA components of the chromoso:es:
a). The Histons: Ten different types known. Fall into 4 general
classes:
Ia, Ib, MII, III, LV. sSased an lysine-arginine ratic

8:1 10:1 1.731 06732 07:1 (yo tryptophane) ( 0)

4 wh Same qualitative types of histones in all nucleated orgnisms.
. " " " " " in active and in inactive chromosones
with very few exceptions.

sy Some turn-over of histones in nuclei that do not replicite DNA
qyuantitative differences in h.stones but not qualitative differences.
Considerable amount of evidence that histones related to

repression of gene action. ‘ut, what substunces are related
to activation of gene?

b). RNA, new species, rdated to histones. One of these RNA molecules
for several of the histones. Heung Rene
c). The residual protein - acid type; Phosopho proteins.
RNA, new species, associzted with this protein. fmwht, <n,

meg,

d). khosopholipids.
4, The chro.:osome: an extraordinarly complex system: Related to
control of action of genes; to mechanisms producing mRNA etc. wud
mechanisms of reduplication of the @hromosomes, etc.

We should expect to find that new, previously unsuppected mechanisms of
protein formation, and replicati:ns may occur with these structures.

5. Bacterial systems: do not have all of these. A few exceptions indicated
and these may help in explaining some of the modes of regulation of

gene action in higher organisms. The one outstanding example is the
control mechanisms operating at the Hy and H, duplicate genes in
BSalmoneila.

III. The relation of the organizati n of the chr:wosoue parts in the
nuciteus(to gene action and repression. ) GHNtRAL CONSIDWRAPTONS.

1. The active chromatin: dispersed; the inictive chromatin contracted.
a). This realized by cytologists for many years: Example in the

Microspore of plants:

 

b). Condensed nuclei and chromatin in generative cell; size of
nucleolus.

2. The nucleélus organizer: Special region in one chromosoie.
function: to produce the nucleolus at telophase; The
nucleolus with the DNA of organizer: related to production of the

cytoplasmic ribosomes. Ubagr s TR rvkaebuddayh

axampie of the organizer: its position with respect to the
nucleus; the constance of this osition in the working nucleus.
Slide 1: Maize set of chromoso es at pachytene.

Slide 2: The nucleolus chromosome in muize.
3. The true heterochromatic regions within a chromosome.
a). The heterochromatin about centromeres in Drosophila. The

chronocenter in the working nucleus. Its position with reference to the
nuclear membrane, “aol”

b). The true heterochromatin in maize: the knobs: Sliaeg 3.
ce). The relation of the knobs to the nuclear membrane: Slide A
d). The relation of the centromeres to the nuclear membrane: slide 5

e). the heterochromatin at the ends of chro:osuues: Very visible in
many plants and animlas: Relation to nu iear membrane.

4, None of these types of "heterochromatin" he conventional genes in
them.

in . . . , ee
Lee. 5. She relation of curomat_n parts to the nuclear membrane is hAighl
a Significant as will be indic..ted. and
-4.

ders
: i Obici)
bavuyiy tonto wouoh TMM
IV. Condensation of chromatin: one form of control of action of genes.
fwo distinctiy different classes of this; each , however, is erfective
in repressing the action of structural genes.
Chass T:
1. Two nuclestea microspore: The active nucleus and the inactive nucieus.
orgunization of chromatin in euch.

2. types of condensation of chromatin in different nuciei of the same
tissue: rabbit retinal cells in embryo; Beermann photo. Slides 6, $%.

3. Calf thymus nucleus: Frenster, allfrey, itirsky Lab.
a). Appearance of nucleus in light microscope before and after swelling.
Slide 8. Position of condensed chromatin in condensed regions
—~ Slide 9.
b). Tests of parts of chromatin in such nuclei that produce mkNa: SlideLoO

ec). The relation of strands of DNA in association witn condensed regions:
“igure of Frenster: Draw.

ad). Components of chromatin in active and inactive chromatin:
Table 1, trenster May, 1965:

Rae, pabuy donc [aoe

huobowig Es4C
Win Kore U4 eld Yo obey Bi ve
tWaapla tered? ‘is
a ple prcteay painybircus 3.74

e). iffect of additions of polyanions to active and inuctive chromatin:

suggests that the special species of RNA ass ciated with the
residualx¥kx protein associated with activation of gene whereas
RNA species associ:ted with histones may regulate in some manner
repression of DNA,

4, the contracted chromatin: Specific types for each type of cell.

5.wUESTIUNS: (1) What type of mechanisms controls these highly svecific
types of contractions of chromatin?
(2) Why are the condensed parts bulked as they are with the
active pa ts extending from them in all parts of the coutruicted mass?

(3) What is the relation of the nucleuir membrane to all of
this? How does it come into the picture of repression?

(4) What types of determinants cortrol the particular
parts of a chrouosoue that will be in the cordensed stage at any one time or
in any one type of cell?

5) What components of the chromosoues a Nset" 4
advance so that they will become contracted pr certain ééfls? t What Sap:
mechanism serves to release these settings? are they particular elements
associited with the DNA-- the genes? and if so, what are these components?

(6) If (5) is in fact correct, do we have any evidence for such
settings and erasings of a setting?

These questions indicate the extent of our ignoraace of the cuntrol

mechanisms in nucl: ated organisms at the molecular level. We ave not
yet ready to consider in detail any control mechanism in higher organisms at
this level. We must know more about the specifics of chrorosonrie composition,

organization of parts, and chanzes in this that occur.

Chass II CONDENSaATIONS. This involves the completd contraction of an
entire chromosome or of a continuous segment of
an entire chromosome in contrast to Class I
which involves intermittent condensations
within a chromosome.

1. Our knowledge of the control mechanisms better with this class.
¢. The X chromosome in mammals as an example of this:
(a). XY : X chromosome is not contracted.

(bo). X X: One X contracted; other X not contracted,

(c). Position of the contruicted X in the nucleus: At the nuclear
membrane. Slide ll

(d). Contraction of X when more than two present:
AX, AKK, AKKX, XXXXKH

(e). Selection of which X to contract: XX female: Uccurs during
development: one X in one cell, ahé other X i.. another cell.

(f). Wawxisxthinxazemmpixeneaxx How is this selection accomplished? ‘

: Yenhainsact
KE EMMEXLHALXOMEL YX RMEXXXAKKXEXENERMAEMMER XEN FEREX why onely one,

Will consider this shortly after several other cases reviewed.

(g). The CONTROLLING Hun EN'T responsible for contraction allong the
chroriosowe.

(1). Translocations between X and autosomes in the mouse: Russel.

A region of co.trol in the X chromosome, . —
Contraction occurs to either side of it. Lopeusiny dfid }
Distance controlled by this region
fransloc.tions: autosome genes in line with this, they

become contracted and non-active:

. af wy ye you
Diagram: Fae ena peyanations IB
BR RO

o .
Contraction: Related to control df one region?

(2). Control of selection process in mammals: will consider
after discussion of other cases. wil] make discussion clearer,
3. the condensation of a whole set of chromosomes: the mealy bug. Coccid.

(a) Male germ line: One set from father: contracted set
Une set from mother: not contructed,.

(db) Sperms: Set from father discured during md@osis; only set from
mother is carried in the sverm.

(c). The female: regular meiosis:
Some females: produce eggs that develop into females.

Under some cunditions, produce some eggs that
develov into males.

(ad). the female embryos: both sets of chromosomes are functional and
euchromatic.

(e) The male embryos: One set--thset received irom father, carried in
the sperm-- becomes totally conden et: Slide 12. Contracted
chromosomes again up against the nucleir membrane. Setting
to do this occurred in germ line of male: then euchzomatic.

(f) Another group of coccids: same general conditions up to time of

condensation of male set in the male embryos. Instead of
condensation of set, all chromosoies are el@minated from
the nuclei at a certain cleavage division.

snys(g): Vonclude: some relationship between condensation and elimination
process as these are related in evolution, Sm iy pur bond mehicn ¢
BUR ME ithe
4, The HE for elimination chromssoiies in the cecidomyidae:

(a). Egg after fertilizati n:

(b). The pole plasm:

(c). Nucleus associ ted with pole plasm(germ line). Rescued from
elimination. Any nucleus placed here: no elimination will
occur. Slimination will occur if nucleus norma:ly here
replaced by one that would otherwise form soma and have
chromosomes eliminated,

in all nuclei
(d).€ Chromosomes ,set Yor elimination at particular division in cleavage.

Resuce from this setting by contact of nucleus with particular
“Gy toplasmic component.

(Must keep the setting in advance for elimination and rescue of this
by cytoplasmic component in mind for later use with “ chromosomes in
Mammals: a rescue process.)

5. to get all of this in focus, will consider the case of Sciara: Vontrols
of the behavior of the X chromosome:

(a). The germ line of the male: 4 chrs. from mother, 4 from father at
late stage in spermatogenesis. =

(b). Spermitogenesis: Méiotic divisions:
-7-

(c). The two types of females: All with normal meiosis
X'X = produces eggs, all of wnich develop into females.

XX = produce eggs, all of wnich develop into males.

a

(ad). Lhe zygotes and early cleavage nuclei:
hégs from A'X individuals: Cleavage:
zygote: X A mother/ K X A father

Uleavage: 6 or 7th division, one A from father eliminated.
imoryo develops into a female.
Eggs from X X mothers:

kygote: X AJ KX a: Cleavage: both X chromosvies from male

le : . ; eliminated: develops into a male.

(e) Transloc&stions between autosomes and x. Various ores worked with.

Result: The X chromosone: Axx §,
Vt wy Doe gh MS
All the aberrant events controlled by xhEXHEXKRXKEXE
some element carried in the tiny short arm of X w..ch is heterocnromatin.
If translocition occurs in short arm between centromere and Keterocnr: atin,
the chromoso..e carrying this and all _of the autosome part: undergoes same
events as X chromosone. Fite oo. . moe OF
\ linet dat y
The Heterochromatin carries a controlling element
that accomplishes all of the events. How does it do this?

(f). fransloec tions with aberrant disjunctions:in the females:

female producing females:
x8 x" mothers: Few #ggs: No As; only autosomes.
Constitution of zygote: O« A/ KX sa
“limination: One chromosome 4 only : Exe plotn puritid 4 Ha ancl
act vow Ta ee
Translocati in from xx? mothers: Normaily male producers \

4
‘
4

nome eggs; We chronosomes with controlling element of X |

Constitution of zygote:

Hlimination: two xX chromosoiies in cleavage(from father).

iixceptional females: retain two & chrotss. e.

al ag one particle A
x (g). Suggests: he X (not the &') produces somes substance,in
% egg before meiosis that can rescuYe one X from eliminetion %x
With XA females; two such particles. Therefore 2 h
x
A chromosomes may be rescued by it. sy

A

ay

husk opnatade: BoTt x dum a7 act for dewalicy — Roar June aug apie olan Ss

cue Putin we lh BE His 3

 
6. The relation of Sciura evidence to X chro:osome condens:tions in
mammals.

a). All & chromoso.ies ave set in advance to become co: densed auri..g
development of embryo.

b). Uan be rescued from this by reaction with some component in the
cytoplasm.

ec). Only one such component produced.

d). This element reverses the setting for condens:tion.
e). Should be matter of chance which A, if more than one present,
wili be rescued during stage when rescue occurs.

f). &Y - the X always r scued as no other & present.

AR - Une A rescued in some ceils, other condenses; In other ceils,
the other is rescued.

XXX, XXKA, AAAX - only one X can be rescued; all others are
condensed.

7. Return to Sciura or the coccids: setting of elements must occur in
the germ line of the father.

Erasing of the setting must occur in
the germ lmne of the mother.

ilements
8. Vertain chromosomal components,are res onsible for the control of
of contraction and release from contraction; for repression and
release from repression.

These elements respond to cytoplasmic or intranuclear substances,
previously produced or introduced: as with hormones that
react with the chromosomes themselves-- special purts.

9. If we accept that there ar# chromosonal elements, distinct from the
genes, that control their action muk through vurious tynes of
res. onses of the chromatin m:teyials, we are a long way on the
road to understanding the mechanisms that operate in higher
organisms to control the action of genes.

V. Uther evidence of the manner by which the action of genes are controlled:

1. lactic dehydrogenase genes: H and M. Tetrameres:
HHHH, HHHM, HHMM, HMMM, MiuMM, Young and older individuals.
(Uhick; rabbit)

é. intra-allelic repression: Tetrahymena and Faramoecium
x

3. Multiple genes - verotypes in raramoecium: Unliy one active at a tine;
others inactive. mo rn

4, wusteriuse alleles in maize: Vo: trol of action of one or the other
allele: Differences in different tissues.

ays Genetic analysis: Control mechanism associuted with something at
Y the locus of the gene.
., De Setting of a gene locus at one specific time in one tyoe of cell to
aw} be expressed in cells some cell generations later:
m

Position effect: Becker w” locus. Adjacent to heteroenroriztin

by trensiloe. tion.
Gene set in sone celis at this time. £
No effect on the time of setting. ietects frequency of
cells that nave their locus set at this time.

Reflects tyve of setting mecnansims that occur during
development.

es 6. Alleles thit control the pattern of distrivution in a tissue of the
¥ end oroduct of sequence of gene actions: Pigment as exampie.
bady Beetle: Pigment patterns in the “lytra.
lypes of patterns observed in nanute.
Genetic analysis: Une locus associated with control of

this vatterm. tach allele of this locus res.consible for one
particular pattern: for control of production of end product of

genes in sequence to pigment formation. element
Vouibination of two alleles of t is "regulator", ganex
Slide 13 Uverlaoping patterns.
fuch expresses itself inde endentiy of tine other. Thus, cytoslasm

in t is case is not a determining factor directly. Time of gene
action of an allele, number of cells in w..ch action will occur
controlled by some comovonent at tis sere Locus.

7. bady 3eetle patterns: Can duviicite come:etely with maize where we
know the element at the gene locus and how it operates to
accom lish these vatterns. This will be considered in next
lecture.

Vi. Conclusions: Yhere are psrticular chrewosomal components, car :osoal
eienents, that are res: onsible for the c:ntrol of sene action and
they accumpiish this in var ous manners: contr -etions and relense
from cortractions; repression iocsiiy and release from this
reoression.

The Urgunization of the components ov the chronus.e, their numerous

Components, are all involved in the orderly ecu: trol of thiss WM way Coie. cies
Oye inh ire eI 2A. tM a uA,

aJUistllivuN: what are the elemen that are loc-lized at the different
structural gene loci? what are tne elerients composing the true hetero-
chromatin?’ what is tne nature of the setting and release from setting of
such elements? fvese are some of the busic questions that must be solved in
considering mechansisms in oreinisms with true nuclei that control th
action of Tne genes.

  
QUaSTIUN: How many kinds of elements are there that do these
controls?

My conviction: Relatively few such elenents. Like a
computor -- not so many different types of elements, but how these are
integrated into a programming system. “ome basic simplicity, as with
structure of DNA.

Tllustrations: The Mmknexx Caterpillar and the Moth:
Same genome but different programing of “ene action.

The Switch genes: Polymorphism; Mimicry.
Unly one or two meridelizing units responsible for altering the programming.

VII. Subject of next lecture: Nature of elements that control the action
of specific genes, their independence of the structural genes,
the variety of modes of control of gene action thatone element can
produce, the extraordinary economy of such elements -- many different
genes may be controlled quite differentially by one system of
elements. the indication that such elements reflect some basic
symplicity in pattern of action just as DNA has a basic simplicity
of component parts that can lead to tremedous diversity of effect.

1. The elements in maize initially discovered because they could
(but n-ed not) trans,ose from one location to another in the chr msome
complement.

2. Literature: many examples of phenotypes that resemble those produced
by the controlling elements in maize but no instances that are supported
of the elements that are responsible for this.

3. The transposition of elements to divferent sites in the genome:

Bacteria: the episomes. uct

Higher organisms: Only one ecxse of "transposition" of some
component and this one that contrlls sex. [ Peaidl) otwuilas vin Hystetosd

Sex control mechanism in Megaselia - a fly:

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Slides. Lecture 1

1. vhromosome set at pachytene: maize

2. Nucleolus chromosome at pachytene:maize

3. Nucieoius chromosome, knobs, pachytene, maize

4. Knobs at nuclear membrane; endosperm of maize, polyploid.

5. FYeulgen stain, puchytene maize; B-tyyve chronosove centromere.
6. Kitten, 10 day old retina cells: Beerman

7. Same

8. Lymphocyte nuclei: non-swollen; swollen

9. " " swollen

10. " Active and inactive chromatin: autoradiegraph tesis.
ll. Sex chromosome in embryo tissue of rabbit.

12. VYondensed set of chromosomes in spermatogenesis Cerococcus (mealy bug).

13. “lytra patterns: mexk Lady Beetle. ‘Tan, 1946
Cornell University, +ecture 1. +tyesday, Nov. 16, 1965
ADSPrHOTS OF GENE CULLTROL IN HiGHuR ORGANISMS.

I. The influence of bacterial and phage genetic and molecular studies on
genetic and biological concepts.
1. DNA - mRNA (ryypolymerase) ~ transfer BNA, rigosones etc. DAA oivealion
2. lypes of genes: structural, sRNA, rRNa, regulators, suppressors,
Uperator- operon. Regubation.

3. Regulatory mechanisms: not yet clarified.
4, The odd types of control in bacteria:
H)-H, duplicate genes: Phase variation
ipisome control of gene action: Taylor; Dawson.

Host modification of phage: Modification of phaze genome -
restriction of host.

5. Imporvance of the "odd" types: particularly the H,-H, duplic.ute genes.
1 2

II. Types of gene control that have been e. amined: ixamples.
1. At the molecular level: “gemdblobin in young and older individuals.

lactic dehydrogenase: Two genes, M,H, the tetrameres. ‘oung
vers older embryos.

Esterases in maize: liming of action of different alleles:
coiustancy for an allele: Control: genetic methods,

resides at the locus of the gene. Te penal 04 yale ¢ ayy

2. Yaramoecium and Tetramymena: Intcrallelic repression. timing of
event.
Series of genes for serotype: 14; only
one active at a time; other Afluplic te" genes turned off.

Other genes: behave similarly. timing
of events: controlled. Chages through environmental chan:es:
the serotypes.

3. The position effect in Drosophila: Becker: white locus next to
heterochromatin: timing and frequency of this. sf-ect of Y.
Yoes not alter time of event; alters frequency among celis in
which event occurs.

4, The progeins of the 75 comp nent of antibodies: amino acid differences
in one segment of this component.

5. Vontrolling elements: maize. Vomponents that may be identified and
characterized; serve to moaify gere action and at particular times
and in particular manners,

6. the effects of hormones: act at gene level. wuffects only in certain
cells. Vombine with chromosome —- some evidence of this
iil. The components of the chromoso.es in nucleated organisms:

1. Hnormous difference in associated components of DNA between
bacteria and organisms with chromosomes and nuclei.

é. This difference: undoubtedly associated with mechanisms of
reproduction of the chromosoue and with control of gene action
during differentiation and in individual cells, already differentiat

3. Number of DNa molecules per chronoso:e: few. Number of replicons:
a number of them per chromosome.

4, The components of the chronmosu:ie:
Histones: bLycfne rich and arginine rich:
Residual protein: acidic
the new RNA species: with histones; with basic protein.
“he phosphoproteins; the phospholipids.

5. the Histones: have been the candidate for repression of gene action:

a). Histones in active and inactive chromosome parts: not divferent.
eome turn-~over of histones without replicstion of Dila,

b). What histones might ce doing: ‘escribe shortly;
6. The organization of parts of chromusoxes in the light microscope:

(1). @he nucleolus organizer: “unction; cytoplasmic ribosomes. .
Slides 1, 2. Raion baba? dy 22—— oe B oushlr

(2). the true heterochromatin in the chrososo es: psotions.

About centromeres in Drosophila and other organisms.
appearance in the nucleus.

at ends of chromosomes; At special regi.ns: knobs in maize.
(3). the position of the difte ent parts in the working nucleus:
oliuges 3, 4, and 5.
(4). CHE TrirORvanGe Us The xan tlUN Of racTos Of Gakuswusu.is PU PHS
NUCubaAR MEMBRANE!
and repression

iv. The factivation, of genes through differential condensations:

TWO CLass#s OP Diris sallau CONDENSaLIUN: avn APSHOTS RerunsSIuN OF
Gana ACTIUN.

L Chr.

wu.

i. OD

 

iy

(1). Kelation of condensation to gene action: long known by “a>
cytologist: txample in two nucleited pollen grain.

  

(2). bxamples of differential co:dens:tion in nuclei of ceils of
Same tissue: Slides 6 and 7.
(3). The extensi e studies of Ualf thymus lymphocytes in Mirsky
laboratory, Rockefeller Institute.

a). The appe:rrance of the nuclei: Before and after welling.
olide 8. Slide 9,

b). the position of the cordensed purts with respect to the
nuclear membrane.

c). “he tests of the active and the inactive chromatin:
Hadioactive uracil - positions of formation of RNa
autoradiograph: Slide LO. (position of ce wensed parts).

a). “he mode of connections o: the parts in the coudensed regiunt

vross linkages betw-en strands produced by lycine rich
histones: associ.ted with phosphoric acid group of DNa

This histone associ:.ted with the repression process through
maintaining the clumps.

Arginine rich histones: also associ: ted with the phosphoric
acid group of DNA but combine along side of Dia.
ww mel & tel .
(4). Each nucleus,has its”own type of contraction of chromatin, .
involving diffe.ent parts of the chromosones-- diffe -ent BONES o hp reared wir Mew
“HL
soarg (5) The major question: how does the differential control, take place?
What’ genetic components are involved in this?
° J yp awe edatc
(6). A schédule*of differential seyuences of coudensations must be
present from zygote stage on, if co:.densation is one of the mechanisms
of control of gene action. Dace agiwk aimdt coe aed

(7). are there special elements in the chro:osmes that are -ssoci..ted
with this? Return to case of control of esterase alleles in maize:
control of time of action is different for each allele. +he control
of tris for these alleles is associuted with some conmvonent at the Locus
of the gene itself.

Controlling elements in maize: these are candidates for such
elements that serve as co.trols of gene action: the, Orgnalino Ue commer gb youl Loca -
ab p oudirs
(8). Do we h:ve other evidence of controlling elements or crtrol
regions within the chromos one Athen am madyyg?

(a). the behavior of the B-type chronosowe in maize at
pollen division. Vontrol of non-disjunction:

the locition of the signaler for this: at heterochr m tic

Lhe location of the nog. G6 the signals: near the

centromere end of the chro ‘osorie.
OES
. : . : yo
Both must be present for non-disjunctivon to occur. ot Fee
a ee
ividence from rye chromosome: B-tye here: similar to maize

Iwo element system of coir.trol of non-disjunctions, at
specific stage in development.
(b) the relationship of stage to the effectiveness of wntrolling

elements. . is brings us to the Class II type of
condensation.
-~4.

CLAS& II CONDENSATIONS: Condensation of consequtive regions:
farts of a chrouosome; whole chrorioso:..e; whole set of chrs.
Known to be inactive for genes. IMPORDuT
1. Example: X chromosome in mammals:
non~-contracted
XY, XX, AXX, XXXX, XXXX: Selection of A to be muxkymuked, if more
than one present. athottin wo eoitteted:

Yosition of X in nucleus: Slide 11]

nypothes@s: All & chromosomes donaitioned for contraction; one only
is rescued from thes.

2. the control region for the contraction: the responder to some
signal, In one region of X chrorosome.

the tests in mause: X Autosome transloc:tions.

Results: contraction to both sides of the control region dnwéws
males ions ply
3. Condensation of whole set of chromosomes: measly bugs:, the set
received from the father: Slide 12, Position in nucleus.

this set represents the set previously received from the grand-
mother.

Butline: Females: #emale producing;

same female, eggs luid later: “ale producing.
peeligh™
Set from father in females: euchromatic
4

adie

set from father in males: heterochromatic.

IMPORTANT: Set from father: cond@tioned to condense; rescue from this
occurs in e€@@s destined to produce females; no rescue
from this if it is to produce a male.

sostTLNT PROULSS: Setting occurs in the germline of the father in the
chromosome set it had received from its mother.

Heterochromatic set it received from its father is
discarded; does not get into sperm.

4, the relation between setting for heterochromatization and for
elimination: uses the same mechanism: FryeaShoa ag oPpuaeiee.

some mealy bugs: Set from father is eliminated in early cleavage of
cells destined to become soma celis{* This important for my
thesis,

V. The control of the elimination process: reaction of chrouosomes destined

for elimination during cleavage to cytoplasmic substance which
rescues this: Cecidomyid.
1. the hgg: Pole plasm. Yhe reticulate substance in pole plasm.
the pole plasm and the germ line.

a). Normal behavior:

&). To show tne rescue from elimination related to reticulate substance
(but not the pole plasm. ixample of one type of test:

Lbigature:

ec). Centrifugation studies: Any nucleus that comes adjacent to
reticulate substance will have its E chroiosomes rescued
from elimination process.

VI. The tests of the ressonder and the signaler for the elimination process
in Sciara and the rescue mechanism. Its relation to control
of Exkxmxnatxun condensation of only one X in mammals: the
rescue from condensution of only one A,

1. Sciara germ line of male: later stages; heiosis; constitution of
sperm.

2. The Females: Two types:

X' X: +#roduces only females, normally
x

X: Produces males only. “4
og git

% {
lo show that the signaler is,in the X and not the X* chromosome
and that the reé@f@r is in the heterochomatin, at one location
in the X received fromthe—father, This alba tees. component

was set in male germ line: to effect elimination of both
& chromosomes during 7th or 8th division.

dees

- The eliminations of X in gmxemxkimex soma of eggs produced by <
bggs of X” K females: only one of two sister X chromosomes from father

no" xX xX Females: gnuxy both K chromosomes from father elimin ted.
3. Relation of control of elimination in the soma cells to product
of the X' chromosome:

Females: X!' x== normall female produces: one A from male elimin=ted.

Non-disjunctions:at meiosis: No X chrumosone in ef@ nucleus
4ygote: LA +2X1A4
Soma elimination: One X only eliminated.
female: XX= normal zygote 1X + 1a eX + 1A,
Soma: elimination of both & from father.
Nondis junctions: 2 X chromosomes in e8@ from mother.
aygote: 2X+1A/2X+1A4,
“oth X chromosomes from male elimin:ted.
Hypothesis: Roth X chromosomes from father destined for elimination
in the soma. X chromosome produces some "particle"
that is able to rescue only one & chromosvrie. iiust be

in cytoplasm as in non-disjunction case, no X from female
in the zygotes.

Setting: Occurs to element locuted in het-rochrow:tin of X:

AAKX

cy.
vy
A- Autosome transloc=tions:

Any part of chromosome complement th:t carries this
element will follow elimination path, non-disjunction
path at meiosis of male.

Best trunsloc tion: KKK. cece ee Qecccncvcccevvceaco
wee ee Q x

Setting occurs during germ line of male to this eleuent.
Rescue occurs in soma of females to one element

No settings occur to this element, leading to elimination in serm line
of female. Unce rescued, remaines rescuéd until it a..in
passes through germ line of male.

4, The relation of the Sciara cause to X chromosones in mammals: Lhe
setting region:for condensation.

Unly one & rescued. signaler not in A chrosiosome probably. “hould
be in one of the autosomnes.

VII. The setting of the controlling elements in maize and the resetting
process. Will discuss later.