The Japanese Journal of Genetics
Online ISSN : 1880-5787
Print ISSN : 0021-504X
ISSN-L : 0021-504X
Volume 33, Issue 5
Displaying 1-4 of 4 articles from this issue
  • V. The chromosomes of American Aster species
    Yukio HUZIWARA
    1958 Volume 33 Issue 5 Pages 129-137
    Published: 1958
    Released on J-STAGE: November 30, 2007
    JOURNAL FREE ACCESS
    1. The karyotypes of 15 species of American species of Aster are reported.
    2. The chromosome numbers of 9 species are reported here for the first time. These are: A. modestus 2=18; A. puniceus 2n=16; A. concinus 2n=46; A. pilosus 2n=48; A. simplex 2n=64; A. chilensis 2n=64; A. exilis 2n=10; A. occidentalis 2n=16; A. alpigenus 2n=18.
    3. The primitive basic chromosome number for the genus is considered to be 9.
    4. Judging from the chromosome numbers and the karyotypes the origin of this polyphyletic genus is probable in the American species of Aster.
    5. In strong contrast to the symmetrical karyotype of Asiatic species of asters, there is a marked increase in asymmetry in the karyotype of the American species.
    6. In general the chromosomes of the New World taxa are smaller than those of the Old World species.
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  • Kiyoshi ABE
    1958 Volume 33 Issue 5 Pages 138-145
    Published: 1958
    Released on J-STAGE: November 30, 2007
    JOURNAL FREE ACCESS
    1. Amylase activity in D. melanogaster varies according to strains; the activity of Hikone-AS (H) is always stronger than that of Oregon-R (iso) (O).
    2. Hybrids between the two strains show an intermediate activity of the parents. Judging from the result of H×O and of O×H, it is assumed that the amylase activity is not controlled by a sex-linked gene.
    3. In both H and O strains, the amylase activity in eggs is very weak, the activity in larval stage, especially in the third instar larvae shows the highest value, then it decreases suddenly just after the pupation, and maintains nearly a constant value till the adult stage.
    4. As far as experimental results show, amylase activities of the digestive and body fluids in larval and adult stages, seem to be controlled by the same gene.
    5. When starch is added to the medium which contains little starch, the amylase activity in the adult stage increases as compared with that of the control.
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  • IV. Meiosis in PMC's of F2 plants
    Goichi NAKAJIMA
    1958 Volume 33 Issue 5 Pages 146-154
    Published: 1958
    Released on J-STAGE: November 30, 2007
    JOURNAL FREE ACCESS
    1. The meiosis of PMC's of 35 individuals of F2 raised between two species of Triticum and Secale cereale is described.
    2. The number of bivalents observed in one PMC is 11-23 at the heterotypic metaphase of Triticum-Secale triple F2 plants, and the frequency of those bivalents is shown in Table 1. And the mode of the number of bivalents was 14II in the individuals having 2n=28-32 chromosomes, 15II in those of 2n=33-37, 15II-19II in those of 2n=38-44 and 17II-21II in those of 2n=45-50. Generally, the number of bivalents increases as the number of chromosomes increases; showing that the number of homologous chromosomes will also increase when the number of chromosomes increases.
    3. Trivalents or tetravalents, suggesting that the plants have 3 or 4 homologous chromosomes.
    4. Triticum-Secale triple hybrids employed in the present research are of the 2nd generation raised from the hybridization between two species of Triticum and Secale cereale each of which has quite different nature. Therefore, the meiosis in PMC's is very anomalous.
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  • Humihiko ONO, Sizue NAGAI
    1958 Volume 33 Issue 5 Pages 155-162
    Published: 1958
    Released on J-STAGE: November 30, 2007
    JOURNAL FREE ACCESS
    The hybrid between Paraixeris denticulata (n=5) and Lactuca squarrosa (n=9) is composed of cells with different numbers of chromosomes, which are smaller than the expected 14. In the hybrid hitherto reported, a single karyotype with 12 chromosomes was predominant.
    A further investigation was carried out with the parental plants of different origin. The results are somewhat different from the former hybrids.
    The mosaic condition with different karyotypes is also observed in the present hybrids. But karyotypes with 10 chromosomes seem to be predominant over the others in much less extent than in the former hybrids.
    Better mitotic plates are obtained when plants are germinated in a sterilized agar culture medium than on filter paper or in soil.
    Cold treatment of plants (0°C, 3-5 days) reveals some patterns of the chromosomes, which make the identification of an individual chromosome more easy.
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