The Japanese Journal of Genetics
Online ISSN : 1880-5787
Print ISSN : 0021-504X
ISSN-L : 0021-504X
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Volume 31, Issue 7
Displaying 1-5 of 5 articles from this issue
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  • A PHASE MICROSCOPY STUDY ON THE EFFECT OF SARKOMYCIN UPON DIVIDING SPERMATOCYTES OF GRASSHOPPERS
    Yasushi OHNUKI
    1956 Volume 31 Issue 7 Pages 197-200
    Published: 1956
    Released on J-STAGE: May 21, 2007
    DOIhttps://doi.org/10.1266/jjg.31.197
    JOURNAL FREE ACCESS
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    The effect of sarkomycin upon the spermatocyte division of grasshoppers, Oxya yezoensis and Podisma sapporense, was observed by phase microscopy. The course of abnormal division was followed successively in a single cell from metaphase to telophase. Generally, sarkomycin damages the chromosomes at metaphase. The chromosomes show stickiness and coalescence under the iufluence and the cells are blocked at metaphase. When the effect is not very powerful, the behavior of the mitochondria remains unaffected, and the formation of an anuclear bud is induced.
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  • GENETIC ANALYSIS OF COVARIATION IN QUANTITATIVE CHARACTERS
    I. THE COMPONENTS OF COVARIANCE AND THE TEST OF CHANGE IN CORRELATION
    Masatoshi NEI, Katumi SYAKUDO
    1956 Volume 31 Issue 7 Pages 201-206
    Published: 1956
    Released on J-STAGE: May 21, 2007
    DOIhttps://doi.org/10.1266/jjg.31.201
    JOURNAL FREE ACCESS
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    (1) Methods of partitioning the covariance and of analyzing the correlation coefficient into the fixable genetic, unfixable genetic and nongenetic components were developed. The mating systems considered in this paper were self-fertilization, biparental cross and backcross.
    (2) The effects of linkage and pleiotropy on the covariance were theoretically studied and a technique for testing whether or not the correlation can be broken down was raised.
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  • Genetical and embryological studies of the E-allelic series in the silkworm
    The action of the two new genes, EMs and EMc
    Mitsuo TSUJITA, Bungo SAKAGUCHI
    1956 Volume 31 Issue 7 Pages 207-216
    Published: 1956
    Released on J-STAGE: May 21, 2007
    DOIhttps://doi.org/10.1266/jjg.31.207
    JOURNAL FREE ACCESS
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    This paper deals with the genetical and embryological studies on the relations of the action of the two genes, EMs and EMc, to that of other six E-allelic genes, ECa, ED, EEl. EH, EKp and EN.
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  • Cytogenetical studies on the intergeneric F1 hybrids between Triticum sphaerococcum and each of 3 species of Secale
    Goichi NAKAJIMA
    1956 Volume 31 Issue 7 Pages 217-223
    Published: 1956
    Released on J-STAGE: May 21, 2007
    DOIhttps://doi.org/10.1266/jjg.31.217
    JOURNAL FREE ACCESS
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    1. In the present paper cytogenetical researches on the F1 plants raised from Triticum sphaerococcum crossed with 3 species of Secale (Vavilovii, africanum and montanum) are dealt with.
    2. Among the 3 combinations, the percentage of the F1 obtained to the number of the pollinated flowers was highest in the hybridization between T. sphaerococcum and S. montanum, and lowest with S. Vavilovii (Table. 1)
    3. The external characters of F1 plants raised from the 3 combination resembled to the parents, although much more closely to mother plant than being the intermediate of the parents.
    4. The 3 F1 hybrids showed fertility in natural selfing though lower in percentage.
    5. The number of somatic chromosomes in root tip cells of the 3 F1 hybrids was 28 which corresponds exactly to the sum of the gametic number of chromosomes of the parents.
    6. The F1 hybrids of the 3 combinations showed differences in the number of bivalents according as the pollen parents are different though the mother plant was common.
    7. In the 3 F1 hybrids, the number of bivalents at heterotypic metaphase of PMC's was given in Tables 4, 5 and 6.
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  • Curing of chromosome fragmentation in Paraixeris denticulata×Crepidiastrum Keiskeanum (a preliminary report)
    Humihiko ONO, Sizue NAGAI
    1956 Volume 31 Issue 7 Pages 224-227
    Published: 1956
    Released on J-STAGE: May 21, 2007
    DOIhttps://doi.org/10.1266/jjg.31.224
    JOURNAL FREE ACCESS
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    In the F1 hybrids of Paraixeris denticulata×Crepidiastrum Keiskeanum, some of the paternal chromosomes undergo fragmentation and some fragments are eliminated; hence a difinite karyotype cannot be determined. This phenomenon is assumed to be caused by disturbance in the chromosomal duplication of the paternal chromosomes within the foreign cytoplasm of the maternal cell. To acertain the cause, in one experiment, an excess of RNA was given to just fertilized egg cell. The process is: after the fertilization, flower heads were wrapped with cotten pieces immersed in RNA solution and the cotten was left on the flower for 4 days with occasional addition of RNA solution. The mature achenes thus obtained were examined whether they yield plants somewhat different from the control. Three hybrids obtained from the treated flowers showed practically no fragmentation of chromosomes and no aberrant cells, while the hybrids from the flowers in which RNA application was delayed for 24 hours showed abnormalities which are common with the control. From these results it is assumed that the excess of RNA in the fertilized cell may act as a curing agent of the chromosome fragmentation.
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