The Japanese Journal of Genetics
Online ISSN : 1880-5787
Print ISSN : 0021-504X
ISSN-L : 0021-504X
Volume 33, Issue 9
Displaying 1-3 of 3 articles from this issue
  • Lepidoptera-Rhopalocera
    Kodo MAEKI
    1958 Volume 33 Issue 9 Pages 283-285
    Published: 1958
    Released on J-STAGE: November 30, 2007
    JOURNAL FREE ACCESS
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  • Naomasa KOBAYASHI
    1958 Volume 33 Issue 9 Pages 286-295
    Published: 1958
    Released on J-STAGE: November 30, 2007
    JOURNAL FREE ACCESS
    Morphological alterations of the mitotic apparatus and blocking of the cleavage caused by application of demecolcine to eggs of Mespilia globulus at various stages of the 1st nuclear division are described. By treating fertilized eggs with the poison at stages before anaphase, the development of the mitotic apparatus is prohibited or the apparatus already formed disintegrates. No sign of furrowing appears and the cleavage is completly blocked in these cases. Contrary to these, furrowing commences and advances quite normally in eggs which are exposed to demecolcine at any stages of nuclear division later than the early anaphase, notwithstanding that astral rays disappear within one or two minutes after the application of the poison. These facts would suggest that the critical period lies between the late metaphase and the early anaphase, and when the process of nuclear division proceeds beyond this stage the cleavage begins and accomplishes itself quite normally in the absence of the mitotic apparatus. The mechanism of cleavage is discussed in connection with the present finding.
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  • II. Analysis of karyotype and somatic pairing
    Chao-Hwa HU
    1958 Volume 33 Issue 9 Pages 296-301
    Published: 1958
    Released on J-STAGE: November 30, 2007
    JOURNAL FREE ACCESS
    In haploid plants derived from two Japanese varieties of rice, the morphology and behavior of chromosomes in somatic mitosis were observed. Low temperature treatment (4°-5°C. 20-24 hours) was applied for the root tips. Then, they were squashed and stained with 1% aceto-orcein. The results are briefly stated as follows:
    1. Among the twelve chromosomes of haploid rice, four were of median, and the remaining eight of sub-median or sub-terminal types. Among both latter types, one chromosome with a secondary constriction (Fig. 2c, no. 2), one with a satellite (no. 8), and one with a secondary constriction and a satellite (no. 7) could be identified. In addition, the largest (no. 1) and the smallest (no. 12) chromosomes could also be identified. Thus, seven types of chromosomes were distinguishable in good preparations.
    2. A tendency to somtic pairing was recognized at mitotic metaphase. The maximum pairing so far found consisted of four groups of two and one group of three chromosomes. The largest and the smallest chromosomes tended to pairing. The mode of somatic pairing was thus similar to that of secondary pairing in meiosis.
    3. From the results of these observations, it was assumed that the karyotype of rice could be written as Asm1<(1)>+Asm2<(12)>+csBst<(2)>+Csm1<(3)>+Csm2<(4)>+2Dm<(5, 6)>+tcsEst1<(7)>+tEst2<(8)>+Fsm<(9)>+2Gm<(10, 11)>.
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