MONDAY 30 MARCH
POSTERS RELATED TO S1
Mon-S1-34
Mon-S1-35
THE LEVELS OF PROTEIN BOUND POLY ADP-RIBOSE IN
DIFFERENT HEPATIC TISSUES.
INF'LUENCE OF CHROMOSOMAL PR3IEINS ON RNA SYNJYESIS
IN BovhIE THYROID. R. Voets, H.J. Hilderson, A.
K. Wielckens, P. Adamietz, R. Bredehorst and
H. Hilz
Lagrcu, G. Van Dessel anl W. Dierick. RUCA-Lakxr
ratory for Human Biochemistry and UIA-Laboratory
for Patblogical Biochemistry, University of Antwerp, B2020 Antwerp, Belgium.
Incubation of bovine thyroid nuclei with increasing amounts of histones resulted in a progressive
decrease in DNA dependent RNA synthesis. The activity with purified hcrrplogous enzymes arid calf
thymus DNA as tenplate was also inhibited. A progressive reraoval of histones concamitant with an
activation of DNA transcription was fourd when
chamtin was extracted with increasing salt wncentrations. These data suggest that histones
function as negative modulators. A non-histone
subfraction [J. Biol. Chen. 250(1975)15481 stimulated RNA synthesis with chramtin as template and
reversed the inhibition of RNA synthesis by histones. Another non-histone subfraction [J. Biol.
Chen. 250(1975)89381 did not affect the trmription with chranatin as template, but blocked the
RNA synthesis using native DNA by preventing chain
initiation.
Institute for Physiological Chemistry, University
of Hamburg, GFR
We developed a method for the quantitation of
poly ADP-ribose protein conjugates from intact
tissues: the acid insoluble fraction is prepared
by extraction with TCA, ethanol and ether, from
which the poly ADP-ribose is isolated by affinity
chromatography on BioRex 70-Aminophenylboronate
beads. The poly ADP-ribose is eluted with sorbitol
and degraded with PDE I. The phosphorybosyl-AMP
units are quantitated with the aid of a sensitive
RIA (range: 0.1 - 20 pmoles). Using this method
the levels of poly ADP-ribose in different hepatic
tissues (tumor and non-tumor) were determined.
Mon-S1-36
Mon-S1-37
CHROMATIN ORGANISATION IN THE HYPOTHAL4MUS
DURING DEXELOF'MENT.
THE LOCATION OF BENZO(A)PYRENE-DNA ADDUCTS
WITHIN CHROMATIN FROM MAMMALIAN CELLS.
S.A. Whatley, C. Hall, D.E. Menzies and L. Lim
Department of Neurochemistry, Institute of Neurology, &ueen Square, LONDON WClN 3BG (U.K.)
Peter Jack and Peter Brookes. Institute of
Cancer Research, Chalfont St. Giles, Bucks.,
Eng 1and.
We have used micrococcal nuclease to study
the organisation of chromatin in neuronal and
glial nuclei isolated from the hypothalamus of
rats during early development (2 days before
birth - 25 days old). Hypothalamic neurones exhibited a short chromatin repeat length (ca. 176
b.p.) compared with that of glial nuclei from the
This
hypothalamus and cortex (ca. 200 b.p.).
short repeat length was similar to that of cortical neurones from 7d and 25d animals (ca. 174 b.p).
Whereas in cortical neurons the chromatin repeat
length shortened from ca. 200 b . p . to ca. 174 b.p.
in the first postnatal week, the short chromatin
repeat length of hypothalamic neurons was already
present two days before birth, indicating that
hypothalamic neurons differentiate earlier than
cortical neurons during development.
The location of Benzo(a)pyrene (BPI-DNA adducts
within chromatin was determined by treating
Friend erythroleukemia cel Is with Benzo(a)pyrene7,8 diol-9,IO-oxide (BPDE). Micrococcal nuclease
digestion of nuclei, harvested immediately
following treatment, demonstrated a four-fold
enrichment o f adducts on the nucleosomal linker
region, Agarose gel electrophoresis of DNA from
briefly digested nuclei indicated that mononucleosomes released early during digestion
contained 40% more adducts than total DNA.
Similar BPDE treatment of primary mouse embryo
cells again showed preferential linker binding,
however cells grown for a further 72 hours showed
no such preferential binding
.
Mon-S 1-38
Mon-S1-39
IN VIVO ADP-RIBOSYLATION OF NUCLEAR PROTEINS.
-M.R.Faraone Mennella,B .Farina,R.Jones* ,E.Leone,
P.Quesada.
Istituto di Chimica Organica e Biologica,Facoltldi
Scienze,Via Mezzocannone 16,80134 Napoli(Ita1y)and
*A.R.C. Institute of Animal Physiology,Animal Research Station,Cambridge,England.
ADP-ribosylation of nuclear proteins is thought
to play an important role in regulating gene activity in cells. We have investigated in vivo the
ADP-ribosylation of nuclear proteins in mouse testis, a tissue which is the target for many hormones and which contains a very active poly(ADPR)polymerase system. Following an intratesticular inject ion of 14C-ribose and 3H-adenine,approximative
ly 85% of the radioactivity in nuclear proteins
was found in a non-histonic fraction.These labelled proteins have been characterized by conventional chromatographic and electrophoretic techniques.
128P
PROPERTIES OF A SINGLE-STRAND DNA BINDING
PROTEIN FROM RAT LIVER.
BONNE,C.,DUGUET,M. and de RECOND0,A-M.
IRSC, Villejuif
(FRANCE)
Althought it is a single-strand DNA binding protein,the 525 protein(25000 daltons)
isolated from normal rat liver don't exhibit the usual main properties of a Helix
Destabilizing protein.Besides,the S25 protein is found to interact preferentially
with supercoiled DNA compared to relaxed
DNA duplexes.It binds to SV40 DNA I in a
characteristic manner:S25-SV40 DNA complex
appears indeed as beaded structures that
resemble minichromosomes.Moreover this
protein affects the DNA helical structure:
Superhelical forms are generated by the
association of S25 with SV40 DNA in the
presence of Nicking-Closing enzyme.
Its possible relationships with non histone proteins,in particular the proteins
HMG 1 and HMG 2 will be discussed.