176
J. KIEFER
50. WEISS, B., T. R. LIVE and C. C. RICHARDSON: Feder. Proc. 26, 395 (1967).
51. WINKLER, U.: In: Radiation Research, (G. SILINI, Ed.) p. 796. Amsterdam
1967.
52. WITKIN, E.: In: Repair from genetic radiation damage, (F. SOBELS, Ed.)
p. 151. Oxford-London-New York-Paris 1963.
53. WHITMORE, G. F.: Paper at the 3rd. Congress of Radiation Research Cortina
(Italy) 1966.
54. ZIMMER, K. G.: Quantitative Radiobiology. Edinburgh: Oliver and Boyd
1961.
Discussion
KLAMERTH:
(1) Is DNA synthesis essential for fixation?-(2) What happens when DNA
synthesis inhibited (a) before (b) after irradiation?
KIEFER:
(1) Yes, I think it is (see ref. WITKINS).-(2) The usual technique for inhibiting DNA synthesis is to block a step in the chain of precursor syntheses.
I doubt whether these techniques represent a reasonable approach to the
problem.
ARLEY:
Am I right that, so far, you have not worked out the curves of your model in
such detail that you are able to compare them with experimental points and
if not, why not?
KIEFER:
No, I did not, but work is in progress. I think it is necessary with any model,
if it is going to help one to obtain new knowledge about nature, that its predictions and conclusions can be brought to a state in which they can directly be
compared with experimental data, otherwise we shall not be able to conclude
backwards as to the plausibility and correctnes of the basic assumptions made
in the model.
KLAMERTH:
During the symposion about repair of radiation damage in Vienna (IAEA
Panel Proceedings Series, April 18-22, 1966), the question arose whether or
not polymerases are involved in the repair mechanism. I was informed that
inhibition of protein synthesis (by puromycin or other inhibitors) did not
change the repair process.
KIEFER:
The recovery from potentially lethal damage is sometimes enhanced by
treatment with protein synthesis blockers. The enzymes necessary for repair
are probably present in the cell and need not be induced. As far as I know
nobody has measured synthetase activities after irradiation, although this would
be desirable. - Note added at proof: After completion of this paper, HILLOVA
and DRASIL (Int. J. Radiat BioI. 12, 201, 1967) reported that recovery from
sublethal damage is inhibited by iodoacetamide. In the meantime our experiments on recovery from sublethal UV damage were completed and partly
published (KIEFER, J., Int. Radiat BioI., 13, 399, 1968).
J. KIEFER
50. WEISS, B., T. R. LIVE and C. C. RICHARDSON: Feder. Proc. 26, 395 (1967).
51. WINKLER, U.: In: Radiation Research, (G. SILINI, Ed.) p. 796. Amsterdam
1967.
52. WITKIN, E.: In: Repair from genetic radiation damage, (F. SOBELS, Ed.)
p. 151. Oxford-London-New York-Paris 1963.
53. WHITMORE, G. F.: Paper at the 3rd. Congress of Radiation Research Cortina
(Italy) 1966.
54. ZIMMER, K. G.: Quantitative Radiobiology. Edinburgh: Oliver and Boyd
1961.
Discussion
KLAMERTH:
(1) Is DNA synthesis essential for fixation?-(2) What happens when DNA
synthesis inhibited (a) before (b) after irradiation?
KIEFER:
(1) Yes, I think it is (see ref. WITKINS).-(2) The usual technique for inhibiting DNA synthesis is to block a step in the chain of precursor syntheses.
I doubt whether these techniques represent a reasonable approach to the
problem.
ARLEY:
Am I right that, so far, you have not worked out the curves of your model in
such detail that you are able to compare them with experimental points and
if not, why not?
KIEFER:
No, I did not, but work is in progress. I think it is necessary with any model,
if it is going to help one to obtain new knowledge about nature, that its predictions and conclusions can be brought to a state in which they can directly be
compared with experimental data, otherwise we shall not be able to conclude
backwards as to the plausibility and correctnes of the basic assumptions made
in the model.
KLAMERTH:
During the symposion about repair of radiation damage in Vienna (IAEA
Panel Proceedings Series, April 18-22, 1966), the question arose whether or
not polymerases are involved in the repair mechanism. I was informed that
inhibition of protein synthesis (by puromycin or other inhibitors) did not
change the repair process.
KIEFER:
The recovery from potentially lethal damage is sometimes enhanced by
treatment with protein synthesis blockers. The enzymes necessary for repair
are probably present in the cell and need not be induced. As far as I know
nobody has measured synthetase activities after irradiation, although this would
be desirable. - Note added at proof: After completion of this paper, HILLOVA
and DRASIL (Int. J. Radiat BioI. 12, 201, 1967) reported that recovery from
sublethal damage is inhibited by iodoacetamide. In the meantime our experiments on recovery from sublethal UV damage were completed and partly
published (KIEFER, J., Int. Radiat BioI., 13, 399, 1968).