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Volume 39 (1964)
- Issue 6 Pages 393-
- Issue 5 Pages 289-
- Issue 4 Pages 199-
- Issue 2-3 Pages 83-
- Issue 1 Pages 1-
Volume 39, Issue 2-3
Displaying 1-13 of 13 articles from this issue
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SEIJI MATSUMURA1964 Volume 39 Issue 2-3 Pages 83-85
Published: 1964
Released on J-STAGE: May 21, 2007
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SEIJI MATSUMURA1964 Volume 39 Issue 2-3 Pages 86-90
Published: 1964
Released on J-STAGE: May 21, 2007
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COMPARATIVE EFFICIENCIES OF γ-RAYS, FISSION AND 14MeV NEUTRONS IN SOMATIC MUTATIONTARO FUJII1964 Volume 39 Issue 2-3 Pages 91-101
Published: 1964
Released on J-STAGE: May 21, 2007
JOURNAL FREE ACCESSRBE values of fission and 14MeV neutrons with respect to γ-rays in Arabidopsis were studied by specific locus method. F2 seeds from the cross between the single recessive hairless mutant and the wild hairy strain (race Landsberg) were used in this experiment, because of the difficulty to obtain many F1 seeds.
Dry seeds were subjected to 1.2, 2.1 and 2.9krad of fission neutrons and to 0.8, 1.9, 2.6 and 4.4krad of 14MeV neutrons. 23.6 to 47.3krad of γ-irradiations were also carried out in each neutron experiment. Experiments were carried out under continuous light in an air-conditioned room. Around 90 per cent of seeds germinated in the controls and in all γ-ray and neutron lots. Almost all seedlings survived.
During the growth of seedlings, segregation ratio of hairless homozygotes was examined. They segregated according to the ratio of 3:1 in all lots. Therefore, hairy plants must have consisted of 1/3 dominant homo- and 2/3 heterozygotes.
Should somatic mutation from dominant hairy to recessive hairless occur in heterozygotic seeds, it would appear on some part of the plant body. Some of hairy plants in the irradiated lot had some leaves or parts of leaf without hairs. The frequency of plants with hairless sectors increased with increasing dosage both in γ-ray and neutron lots. A non-linear relation taking rather the shape of an exponential curve, was observed for the γ-ray group, whereas the frequency versus neutron dosage was nearer to linear relationship. Hence RBE of neutrons depends on dosage or frequency. The very rough estimate of the RBE for somatic mutation at 1 per cent frequency is about 15 and 16 for 14MeV and fission neutrons, respectively. The possibility that the mutation is caused by chromosomal aberrations is disccussed.View full abstractDownload PDF (1057K) -
AKIO MURAKAMI, SOHEI KONDO1964 Volume 39 Issue 2-3 Pages 102-114
Published: 1964
Released on J-STAGE: May 21, 2007
JOURNAL FREE ACCESSComparative investigation of the effectiveness was carried out between 14MeV neutrons and 137Cs γ-rays in the induction of visible recessive mutations in early and in late gonial cells of the silkworm.
(1) Dose-frequency curve for each of these two radiation experiments was obtained. The curves are qualitatively similar, each showing an initial linear part followed by an exponential rise with increasing dose. This was explained by assuming that mutations scored at lower doses and constituting the linear part of the curves are due to single hits, whereas those recovered at higher doses and forming the exponential part of the curve are caused by multi-hit events.
(2) Dose-frequency curves for 14MeV neutrons showed that the drop in mutation appears at doses beyond about 2, 000rad for early and late spermatogonia and late oögonia. The data on the mutation drop fit to the selective killing hypothesis.
(3) Mutation frequencies recovered after exposure to 14MeV neutrons were more or less similar between the two, early and late groups, for both sexes in the dose range below 1, 000rad, but in the dose range above 1, 000rad they were much higher for the late than for the early group.
(4) The mutation frequencies in late gonia were higher for 14MeV neutrons than γ-rays, while in early gonia they were almost equal for both.
(5) The RBE of neutrons to γ-rays was found to depend sensitively on the germ cell stage; it was about 1 for early gonia and 2 to 3 for late gonia, when comparisons were made at the level of 10-3 mutation frequency. The variation in RBE is due to the variation with stage in frequencies of acute γ-ray-induced mutations.View full abstractDownload PDF (1310K) -
YATARO TAZIMA1964 Volume 39 Issue 2-3 Pages 115-119
Published: 1964
Released on J-STAGE: May 21, 2007
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SEIJI MATSUMURA, TOMOO MABUCHI1964 Volume 39 Issue 2-3 Pages 120-130
Published: 1964
Released on J-STAGE: May 21, 2007
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TOMOO MABUCHI, SEIJI MATSUMURA1964 Volume 39 Issue 2-3 Pages 131-135
Published: 1964
Released on J-STAGE: May 21, 2007
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TAKASHI ITO, T. YAMASAKI, M. DOMON, S. ISHIZAKA, Y. MATSUDAIRA1964 Volume 39 Issue 2-3 Pages 136-146
Published: 1964
Released on J-STAGE: May 21, 2007
JOURNAL FREE ACCESSThe nature of genetic changes inducible by UV in diploid yeast was studied through action spectrum for the induction and photoreversion experiments. The results may be summarized as follows.
(1) UV action spectrum for the induction is similar to the absorption spectrum of thymidine in shape.
(2) Eighty per cent of the effect by 2, 800Å radiation is photoreversed.
(3) Therefore, the primary events for both the induction and the photoreversion process may be explained by the double-strandedness of the gene DNA, although the kinetics of the photoreversion of whole- and fractional-type of change is not sufficiently clear.View full abstractDownload PDF (1031K) -
TERUTOSHI YAMASAKI, TAKASHI ITO, YORIAKI MATSUDAIRA1964 Volume 39 Issue 2-3 Pages 147-150
Published: 1964
Released on J-STAGE: May 21, 2007
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TAKASHI ITO1964 Volume 39 Issue 2-3 Pages 151-154
Published: 1964
Released on J-STAGE: May 21, 2007
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YOSHIO NAKAO, EIKO YAMAGUCHI, ISAMU MACHIDA1964 Volume 39 Issue 2-3 Pages 155-163
Published: 1964
Released on J-STAGE: May 21, 2007
JOURNAL FREE ACCESSThe frequencies of sex-linked lethals and translocations were determined in the progeny of Drosophila _??__??_ injected with either ethylene imine or TEM [2:4:6-tri (ethyleneimino)-1:3:5-triazine]. The ratio of translocations to lethals was the smallest in the case of TEM treatment. The results agree very closely with the data obtained with ethylene oxide and diepoxybutane as expected in the previous paper (Nakao and Auerbach 1961). This, again, lends no support to the idea that the difference in carcinostatic activity between monofunctional and polyfunctional alkylating agents is due to cross-linking action of the latter type of compound on the chromosome. TEM did in fact induce fewer translocations that expected from the number of functional arms. Possible cause for this result and related problems were discussed.View full abstractDownload PDF (779K) -
KAZUO MORIWAKI1964 Volume 39 Issue 2-3 Pages 164-175
Published: 1964
Released on J-STAGE: May 21, 2007
JOURNAL FREE ACCESS(1) Incorporation of 14C-leucine into myeloma protein fraction of X5563 plasma cell tumor in C3H mouse was partially inhibited by, actinomycin D. This result suggests the existence of a stable messenger RNA in the tumor cells.
(2) The actinomycin-depressed myeloma protein synthesis could be restored following extracellular treatment with X5563 tumor RNA for 15 hours at 2°C.
(3) Treatment with X5563 tumor RNA for 15 hours at 2°C could induce myeloma protein synthesis in Ehrlich ascites tumor cells. Neither RNase treated RNA of X5563 tumor nor RNA of Ehrlich tumor itself was capable of inducing the myeloma protein.
(4) In present experiments RNA treatments caused the inhibition of protein synthesis in the recipient cells in proportion of the concentration, although it had no inhibitory effect on the oxygen consumption of the cells. So, the ability of RNA restoring or inducing myeloma protein synthesis was expressed by a ratio of myeloma protein fraction to total soluble protein fraction in 14C-leucine incorporation. 14C-leucine incorporated into myeloma protein fraction was determined by the radioactivity in the precipitate with anti-myeloma rabbit serum.View full abstractDownload PDF (1190K) -
SOHEI KONDO1964 Volume 39 Issue 2-3 Pages 176-198
Published: 1964
Released on J-STAGE: May 21, 2007
JOURNAL FREE ACCESS(1) The work done by the research unit (representative: S. Matsumura, National Institute of Genetics, Misima, Japan) on mutagenic studies with higher and lower organisms is summarized.
(2) RBE for mutations is discussed and compared with RBE for somatic damages. It is pointed out that the apparent RBE for mutagenicity reflects not only the efficiency of premutation induction, but also that of the depression of repair mechanisms.
(3) Combining the above mentioned considerations with the results of other authors, it is concluded that there are mutagenic factors differing with genome complexity in addition to those common to all living things.
(4) The increase in resistance to radiation-induced DNA damages with genome complexity is more remarkable for UV than for 32P or X-rays.
(5) Models based on the evolutionary standpoints are proposed for the origin of the UV resistance.
(6) Based on the evolutionary viewpoints, a repair-tolerance model is proposed for mutagenesis to account for the differential factors in mutagenesis mentioned; the differential factors are the reflection of the difference in the mechanisms of repairing and tolerating premutational DNA damages among different organisms.View full abstractDownload PDF (2470K)
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