CYTOLOGIA
Online ISSN : 1348-7019
Print ISSN : 0011-4545
Volume 18 , Issue 2
Showing 1-10 articles out of 10 articles from the selected issue
  • Motoo Kimura
    1953 Volume 18 Issue 2 Pages 93-104
    Published: August 05, 1953
    Released: March 19, 2009
    JOURNAL FREE ACCESS
    1. In this paper the process of recombination of chromosome segments through continued self-fertilization has been studied mathematically by deriving formulae for the rate of attaining homozygosis, the frequency distribution of the length of heterozygous segments, the number of effective factors, and the distribution of segments to be finally attained in the population.
    2. Let AA' be the initial chromosome pair whose genetical length is 100x0 units, and let us designate the length of homozygous segments derived from A and A' as 100LA, and 100LA', units respectively and that of heterozygous segment as 100Ln, units, so that at any generation LA+LA'+Ln=x0.
    In the nth generation of a self-fertilizing jopulation, the relative frequency of AA' pair becomes
    (1-x0)2n/2n
    The frequency (fn(x)dx) in which Ln lies between x and x+dx(0<x<x0) may be given by the solution of the following equation, assuming the initial condition as f1(x)=2-x0,
    fn(x)=(1-x)2/2fn-1(x)+∫xx0(2-ξ)fn-1(ξ)dξ+(2-x0)(1-x0)2(n-1)/2n-1.
    The frequency of heterozygous pairs at the nth generation,
    Hn=∫0x0fn(ξ)dξ+(1-x0)2n/2n,
    may be approximately
    1+2nx0/2n,
    when x0 is small, and
    nx0/2n-1,
    when n is large.
    3. In Table 1 the values of Hn are given for the initial 20 generations assuming that the chromosome length is 100 units. From these values, the curves showing the decrease of heterozygosis for plants with m pairs of such chromosomes can be constructed (Fig. 2). If m=7, the relative frequency of heterozygous plants is less than 3/10000.
    4. After a sufficient number of generations and after all the chromosome segments have reached the state of fixation, the population consists of the following three types of chromosome pairs, namely AA, A'A' and recombined homozygotes. In such population the frequency of AA and A'A' are both equal to
    e-2x0
    In the recombined homozygotes the relative frequency in which LA/x0, lies between t and t+dt is
    φ(t)dt=x0e-2x0{2I0(4x0t(1-t)+I1(4x0t(1-t)/√t(1-t)}dt,
    where I0 and I1 are Bessel functions.
    In Fig. 4 the frequency distribution for the chromosome having 100 genetical length units is given by a histogram.
    5. As regards the quantitative inheritance, if infinitesimal segments with equal and plus genetic effect construct chromosome A, while such segments with minus effect construct chromosome A', the number of effective factors (cf. Mather 1949) will amount to
    1/(1-2/3x0), under the assumption that neither dominance nor epistasis is present, and only single crossing-over is possible. Thus if x0 is 0.5, which corresponds to the one chiasma length, the number of effective factors will be 1.5.
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  • Observations on the wounded epidermis in larvae
    Toshio Ito
    1953 Volume 18 Issue 2 Pages 105-112
    Published: August 05, 1953
    Released: March 19, 2009
    JOURNAL FREE ACCESS
    Wound healing processes of the integument of the silkworm, especially of the epidermis, were observed histo-cytologically on the larvae injured at the fourth day of the fourth instar. Epidermis at the wound is formed from blood cells gathered there. Mitotic cell multiplication is not observed.
    In the epidermis near the wound there are some vacuolated nuclei which may be blood cells entered in the epidermis.
    In the moulting period cuticle formation is delayed by several hours, as compared with the normal case. No nodule formation in the new cuticle is often observed at the wound.
    Many polynucleated cells are observed in the epidermis near the wound within a scores of hours.
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  • Mamoru Iijima
    1953 Volume 18 Issue 2 Pages 113-121
    Published: August 05, 1953
    Released: March 19, 2009
    JOURNAL FREE ACCESS
    1. The total reducing power in various tissues of Lilium anthers, especially of the sporogenous tissue (the sporogenous and the pollen mother cells), was determined by means of the indicator method during the development of the sporogenous tissue.
    2. The reducing power of the sporogenous and tapetal tissues increases from premeiosis to meiosis remarkably, while in other tissues no such remarkable increase is seen.
    3. The redox-potentials of N. V. E. Grübler were determined by using Michaelis' vessel with the changes of its colours.
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  • V. External characters and meiosis of the F1 T. pyramidale×S. cereale
    Goichi Nakajima
    1953 Volume 18 Issue 2 Pages 122-127
    Published: August 05, 1953
    Released: March 19, 2009
    JOURNAL FREE ACCESS
    1. In 1951, 1064 flowers on 56 spikes of Triticum pyramidale (n=14) were pollinated with the pollen of Secale cereale (n=7). Only one F1 plant was obtained. The percentage of the raised F1 individual to the number of all the pollinated flowers was found to be 0.094 percent.
    2. Almost all the external characters of the F1 plant, excepting one or two, show intermediate characters between those of the parents (Table 1).
    3. The number of somatic chromosomes of F1 plant was counted to be 21, and it corresponds to the sum of the gametic numbers of the parents.
    4. In the heterotypic division in PMC's of the F1 plant, 04 bivalents and 2113 univalents were observed (Table 2). The frequency of bivalents in PMCs was shown in Table 2, and the case of zero in the number of bivalents appeared to be the mode. Those 04 bivalents may probably be derived from autosyndesis between the chromosomes of AB genomes of Triticum pyramidale used as the mother plant.
    5. At ana-telophase in the heterotypic division of PMCs, the chromosomes were distributed to the opposite poles in the ratios from 11:10 to 15:6, and the distribution of chromosomes of the case 11:10 appeared to be the mode.
    6. At meta-anaphase in the heterotypic division in PMCs, univalent chromosomes were usually scattered in the spindle, but in some cases the longitudinal splitting of all the univalent chromosomes were observed and consequently the formation of restitution nucleus were occasionally observed.
    7. The F1 plant shows fertility of low percentage and 7 grains of seed were obtained from 37 spikelets by natural selfing. These grains were sown in October of 1952, and 5 F2 plants were raised.
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  • Further observations on the living tumor cells with a new hanging-drop method
    Sajiro Makino, Hiroshi Nakahara
    1953 Volume 18 Issue 2 Pages 128-132
    Published: August 05, 1953
    Released: March 19, 2009
    JOURNAL FREE ACCESS
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  • S. L. Tandon, Adolph Hecht
    1953 Volume 18 Issue 2 Pages 133-145
    Published: August 05, 1953
    Released: March 19, 2009
    JOURNAL FREE ACCESS
    The cytogenetic behavior of six races of Oenothera affinis and their hybrids has been presented.
    The behavior of the hybrids with respect to pigmentation of the hypanthium has been explained on a unifactorial basis. Races Argentina and Palermo were found to be homozygous for R; Florida and Toledo were heterozygous and Buenos Aires and Santa Fe I were homozygous for r.
    Three of the races viz.-Palermo, Florida and Toledo were found to be isogamous complex-heterozygotes with θ14 whereas the other three viz.-Argentina, Buenos Aires and Santa Fe I were found to be homozygotes, with 7 pairs.
    The phylogenetic relationships between races within O. affinis have been pointed out. It has been concluded that complexes within O. affinis are, in general, closely related segmentally. Further, excepting one of the complexes of Palermo, all complexes of the affinis races were found to be related by a maximum of 3 interchanges with respect to the homozygote Buenos Aires.
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  • I. Mouvement rotatoire et le processus de son apparition
    Yoshio Yotsuyanagi
    1953 Volume 18 Issue 2 Pages 146-156
    Published: August 05, 1953
    Released: March 19, 2009
    JOURNAL FREE ACCESS
    Le présent travail a été entrepris pour constater si le mouvement protoplasmique est capable de se faire dans les fragments de protoplasme qui sont isolés de la structure cellulaire.
    Les fragments de protoplasme ont été obtenus par deux moyens de plasmolyse pour Elodea, et par la coupe de la cellule pour Nitella et Chara, et nous avons pu observer un mouvement rotatoire dans ces fragments.
    Notre attention a été attirée en particulier sur le processus par lequel le mouvement tout en désordre d'agitation devient ordonné graduellement jusqu'a former une rotation, et sur l'instabilité qui caractérise les mouvements dans le protoplasme isolé.
    Ces aspects des mouvements noes font imaginer le processus qui devrait avoir lieu dans 1'ordre submicroscopique, de l'organisation et de la désorganisation réversibles des éléments fibreux qui constituent le cytoplasme.
    Les expériences ont été commencées et faites en grande partié au Laboratoire Botanique, Faculté des Sciences, Université de Tokio. Leurs exécutions ont été bien facilitées grâce à l'aide généreuse de M. le professeur B. Wada, à qui nous exprimons toute notre gratitude. Nous remercions aussi bien cordialement M. le professeur N. Kamiya de l'Université d'Osaka, pour son guide et son encouragement continuels au cours de ce travail, ainsi que Madame M. Kamiya pour son aide aimable à la rédaction de ce manuscrit.
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  • Harold W. Beams, Theodore N. Tahmisian
    1953 Volume 18 Issue 2 Pages 157-166
    Published: August 05, 1953
    Released: March 19, 2009
    JOURNAL FREE ACCESS
    1. The Golgi bodies of the male germ cells of Helix aspersa have been observed in the living cells by aid of the phase-contrast microscope. Their form and distribution are exactly like those seen in fixed material. Accordingly, they cannot be artifacts induced by the methods used to demonstrate them.
    2. In electron micrographs the Golgi bodies have the same form and distribution as those seen in the living cell under the phase-contrast microscope. In addition, they (osmiophilic portion of fixed and impregnated material) are relatively opaque to the electrons, yet display a fine fibrous internal structure. On the inner side, i.e., that of the lesser curvature of the crescent and ring-like Golgi bodies, is seen a highly vacuolated region which probably corresponds to the osmiophobic region of the classical description. However, here this vacuolated region does not seem to be a morphological part of the Golgi bodies, but appears more like a region of active synthesis probably associated with the function of the Golgi material.
    3. In ultracentrifuged cells the mitochondria are displaced to the centrifugal end and the Golgi bodies to the centripetal end of the cell. This demonstrates that the Golgi bodies differ sharply in relative specific gravity from the mitochondria.
    4. Mitochondria in electron micrographs were observed composed of longitudinal striations which may in reality, be lamellae. Mitochondria are distinct from the Golgi bodies.
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  • I. Appearance of male-sterile durum in substitution crosses
    Hirosuke Fukasawa
    1953 Volume 18 Issue 2 Pages 167-175
    Published: August 05, 1953
    Released: March 19, 2009
    JOURNAL FREE ACCESS
    Exchange of nucleus by means of successive backcrosses to both parents has been carried out in an experiment with Tschermak's amphidiploid hybrid _??_ Aegilops ovata×Triticubr durum, known under the name of Aegilotricum.
    In the restoration backcrosses to Ae. ovata the process of restoring the ovata genomes to the ovata plasma has been accomplished in the course of three successive crosses. The final offspring were morphologically similar to Ae. ovata, had 14 bivalents at first metaphase and normal anthers filled with functional, good pollen.
    In the substitution backcrosses of Aegilotricum to T. durum, the three successive crosses resulted in durum plants with ovata plasma. They had at first metaphase 14 completely paired bivalents; the tetrad formation was normal but later all pollen was degenerating, and the small dry anthers contained empty pollen. However, the female organs were fully functional and seed setting by artificial pollination with durum or dicoccum pollen was normal. The male sterility was transmitted to the next generation by the mother.
    Similar pollen degeneration was observed in normal T. durum which have matured in winter after vernalization and long-day treatments.
    It is further to be noticed that durum plants with ovata plasma having extra chromosomes of Ae. ovata as univalents in addition to the 14 duram bivalents were only partially male-sterile. Especially, a 29-chromosome plant showed a very high pollen fertility of 92%.
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  • Masataka Kurabayashi, Junichiro Samejima
    1953 Volume 18 Issue 2 Pages 176-182
    Published: August 05, 1953
    Released: March 19, 2009
    JOURNAL FREE ACCESS
    Mitotic chromosomes of Paris tetraphylla (2n=10) in chilled condition were observed in metaphase of the plants belonging to seventeen groups gathered from six localities. The differential segments which manifest undercharging of nucleic acid in low temperature condition were found restrictedly at the distal region of the short arm of chromosome C. According to the patterns of this region, six different types were distin-guished as for this chromosome. Chromosome D was the only satellited chromosome among the complements of the genom of this plant. As for this chromosome two different types were distinguished according to the size of this satellite.
    The chromosome composition of the plants of each of the seventeen groups was analyzed with respect to the types of chromosomes C and D. The results obtained are as follows; 1) In ten groups out of seventeen, the plants had chromosome C or D in heterozygous condition, and in the remaining six they have them in homozygous condition. 2) The chromosomal constitution differs not only from locality to locality but also, with four exceptions, from group to group. 3) All the individuals belonging to one and the same group have the identical chromosomal constitution.
    Based on these results it was assumed that in the natural population of P. tetraphylla, vegetative apomixis takes place far more conspicuously than in that of Trillium kamtschaticum, which propagates almost exclusively by sexual reproduction.
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