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Volume 46 (1971)
- Issue 6 Pages 371-
- Issue 5 Pages 295-
- Issue 4 Pages 223-
- Issue 3 Pages 141-
- Issue 2 Pages 67-
- Issue 1 Pages 1-
Volume 46, Issue 2
Displaying 1-7 of 7 articles from this issue
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AKIO MURAKAMI1971 Volume 46 Issue 2 Pages 67-74
Published: 1971
Released on J-STAGE: May 21, 2007
JOURNAL FREE ACCESSComparisons of RBE values of 14MeV fast neutrons for the induction of dominant lethals and visible recessive mutations in mature sperm of the silkworm were studied. The main conclusions to be drawn from the results presented are that the RBE of fast neutrons for the dominant lethals (RBE: 10.2) is about 2.1 times that of the mosaics (RBE: 4.8), and the RBE for the mosaics is the same or less than that for the complete mutations (RBE: 6.0).
Considering these findings and others, it seems that the nature of radiation-induced complete and mosaic mutations at the pe and re loci of the mature sperm of the silkworm, at doses below about 5kR, could have occurred as a mixture of DNA strand change type mutations and chromosomal type such as deletion and small deficiency, whereas the dominant lethals may correspond to chromosomal changes.View full abstractDownload PDF (796K) -
I. ACTIVE STAGE OF THE SD-SUPPSESSOR AND THE RECONFIRMATION OF THE DYSFUNCTIONAL SPERM MODELYUKIKO K. HIHARA1971 Volume 46 Issue 2 Pages 75-82
Published: 1971
Released on J-STAGE: May 21, 2007
JOURNAL FREE ACCESSThe study of the temperature treatment revealed that the sensitive stage of SD was at early meiosis 1. This was in agreement with Mange (1968). While the sensitive stage of SD-suppressor was at early spermatid. And also it was found that St(SD) made the SD action less sensitive to the temperature treatment.
On the results of the progeny counts, the mechanism for Segregation-Distortion was examined. It was concluded that the “dysfunctional sperm” hypothesis was reasonable.View full abstractDownload PDF (699K) -
YOSHIOMI TAKAGI1971 Volume 46 Issue 2 Pages 83-91
Published: 1971
Released on J-STAGE: May 21, 2007
JOURNAL FREE ACCESSThe process of the transition from immaturity to maturity in the clonal development of Paramecium multimicronucleatum, syngen 2 was examined in detail. It was revealed that the three sex-traits, i.e., the abilities to undergo mating reaction, holdfast union and paroral union, were expressed sequentially with clonal age; first clones expressed none of the sex-traits (immature stage), secondly only the ability to undergo mating reaction (early transitional stage), then the ability to undergo holdfast union as well as mating reaction (late transitional stage), and then the ability to undergo paroral union as well as the abilities to undergo mating reaction and holdfast union (mature stage). It was also revealed that the intensity of the expression of each sex-trait increased with clonal age.View full abstractDownload PDF (824K) -
V. TRITICUM MACHA, T. SPELTA AND T. VAVILOVIIKOICHIRO TSUNEWAKI1971 Volume 46 Issue 2 Pages 93-101
Published: 1971
Released on J-STAGE: May 21, 2007
JOURNAL FREE ACCESSThirteen strains of Triticum macha, 105 cultivars of T. spelta and a single strain of T. vavilovii, all having the same genome constitution (AABBDD) as bread wheat, were studied to determine their necrosis and chlorosis genotypes by crossing them to appropriate testers.
Results of this and previous investigations indicate that common wheat has differentiated into two geographical populations, i.e. Asian and Western, irrespective of species. The Asian population was characterized by a high frequency of Ne1-carriers and the Western population by Ne2-carriers. A strong isolation barrier between T. macha and the rest of common wheat species due to the complementary chlorosis genes, Ch1 and Ch2 was found.
Based on necrosis data, European T. spelta is assumed to have originated from Ne2-carrying T. aestivum and q-carrying T. dicoccum, while the origin of T. macha is ascribed to hybridization between T. aestivum and Ch1-carrying T. dicoccum. At least, two independent introgressions of genes from emmer wheat seem to have played important roles in species differentiation in common wheat.View full abstractDownload PDF (917K) -
K. TSUNEWAKI, F. KASAHARA, T. FUJITA1971 Volume 46 Issue 2 Pages 103-107
Published: 1971
Released on J-STAGE: May 21, 2007
JOURNAL FREE ACCESSOne hundred and eighty-nine Chinese cultivars of common wheat were crossed to three testers for necrosis and chlorosis genes, and their genotypes were determined.
Three genotypes, Ne1ne2, ne1Ne2 and ne1ne2 for necrosis were found in 39.3, 7.1 and 53.6% of the cultivars, respectively. As to chlorosis genes, the great majority of cultivars (93.4%) were of the genotype, ch1Ch2, the remainder (6.6%) were ch1ch2. It was evident that common wheat retained its characteristic population structure regarding necrosis and chlorosis during its eastward dispersion from Central Asia to Japan through China. No particular geographical inclination in the frequencies of various necrosis and chlorosis genotypes, nor their special association with the two characters, growth habit and awnedness, was detected.View full abstractDownload PDF (390K) -
KEN NOZAWA, KYOJI KONDO1971 Volume 46 Issue 2 Pages 109-123
Published: 1971
Released on J-STAGE: May 21, 2007
JOURNAL FREE ACCESSThe Japanese crooked-tail which frequently appeared sporadically in the Japanese laboratory mice named Kasukabe group was analysed genetically. Sporadic appearance of this abnormality, a clear selection response to increasing frequency of appearance, and an easy establishment of crooked stock in which the frequency was always beyond 90%, made us assume that this genetic abnormality was controlled by a number of polygene pairs none of which had major effect. This assumption was confirmed by the results of experiments comprised of outcrossing the crooked strain with other strains and successive backcrosses of normal segregants to the crooked individuals from the crooked strain; in this mating experiment the frequency of occurrence of crooked abnormality increased markedly from generation to generation. Furthermore, the result of “outcross, high selection and between-line cross” experiments showed that the expression of crooked phenotype did not necessitate a complete accumulation of the polygenes responsible and that the polygenes were in general of recessive nature. From these observations the authors considered that the Japanese crooked-tail was a kind of genetic variation similar in its genetic basis to LERNER's “phenotypic deviants (phenodeviants)” and GRÜNEBEG's “quasi-continuous variations.”.
From the analysis of results of successive backcross experiment and mathematical formulation, it could be considered that the number of crooked polygene loci being maintained in the crooked strain and so segregating in successive backcross lines was at least 3 larger than the minimum number of polygene loci fixed for expression of the tail abnormality. This meant that the existence of crooked polygenes had been of fairly ubiquitous nature in the Japanese Kasukabe group of mice.View full abstractDownload PDF (1314K) -
SHUNSAKU UTSUMI1971 Volume 46 Issue 2 Pages 125-134
Published: 1971
Released on J-STAGE: May 21, 2007
JOURNAL FREE ACCESS1. The pattern and distribution of chromosome aberrations induced by mitomycin C were compared between Vicia faba which possesses heterochromatic regions and Tradescantia paludosa lacking visible heterochromatin in all the chromosomes, using meristematic cells of their roots.
2. Mitomycin C produced chromatid-type aberrations in both Vicia and Tyadescantia. The frequency of aberrations was higher in Vicia than Tradescantia. The distribution of aberrations was found to be nonrandom with a marked excess of breaks in some heterochromatic regions of Sb-chromosomes in Vicia and at some segments of submetacentric chromosomes in Tradescantia.
3. The mechanism of action of mitomycin C and the possible reasons for these localized effects were discussed.View full abstractDownload PDF (1072K)
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