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Volume 31, Issue 3
Displaying 1-11 of 11 articles from this issue
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R. E. Redmann, D. S. Borgaonkar1966 Volume 31 Issue 3 Pages 213-219
Published: September 25, 1966
Released on J-STAGE: March 19, 2009
JOURNAL FREE ACCESSA total of eleven collections from North and South Dakota belonging to the grass tribe Hordeae were studied in detail to determine the extent of meiotic irregularity. Two collections of Agropyron trachycaulum and Hordeum jubatum were most regular with a high chiasma frequency and all the other nine collections of Agropyron spp., Elymus virginicus, and Hordeum jubatum had several irregularities in their meiotic behavior and varied chiasma frequency. A comparison of the present data with earlier studies shows some differing observations which are attributed to natural hybridization with related taxa.
Help rendered by Mr. Peter Bunde and Mrs. Manda Borgaonkar in this study is appreciated.View full abstractDownload PDF (945K) -
Seiji Takatori1966 Volume 31 Issue 3 Pages 220-236
Published: September 25, 1966
Released on J-STAGE: March 19, 2009
JOURNAL FREE ACCESS1. To analyze the energy requirements of the mitotic process of Vicia root meristematic cells, the relative frequency of each stage in the mitotic cycle was measured after 3 hour treatment with various respiratory inhibitors, and the relative durations of all the stages were estimated in the presence and absence of these inhibitors.
2. The inhibitors used were classified into two groups with regard to their effects on mitosis. One group retarded the mitotic process in Vicia roots, while the other group did not. The former group contained reagents which either did or did not inhibit the respiratory process, whereas the latter group consisted entirely of reagents which did not affect respiration.
3. Azide, 2, 4-dinitrophenol and, especially, cyanide, which are direct or indirect inhibitors of oxidative phosphorylation, greatly prolonged the durations of interphase, prophase and telophase, but only slightly prolonged that of metaphase. They also inhibited the respiratory process.
4. Diethyldithiocarbamate, 8-hydroxyquinoline, α, α'-dipyridyl and o-phenanthroline, which are all heavy metal chelating agents, greatly retarded the processes of interphase and prophase, considerably retarded that of telophase, and only slightly affected that of metaphase. They did not inhibit the respiratory process appreciably.
5. Monoiodoacetate and fluoride, both of which inhibit fermentation, did not prolong the duration of any of the stages of the mitotic cycle. Similarly, malonate, an inhibitor of the TCA cycle, had no appreciable effect. These three reagents only slightly affected the respiratory process.
6. From these results, it is tentatively concluded that in Vicia root meristematic cells energy requirement is high not only in interphase but also in prophase and telophase, whereas it is low in metaphase and anaphase, and that the processes of all the stages except metaphase and anaphase can be delayed by alteration of the cell conditions by elimination of heavy metals.
The author wishes to acknowledge the aid and criticism given him by Dr. N. Shinke, Professor of Kyoto University. The author's thanks are also due to Dr. K. Imahori, Professor of Osaka University, for his encouragement throughout these studies.View full abstractDownload PDF (1201K) -
II. MeiosisKeizo Maruyama1966 Volume 31 Issue 3 Pages 237-256
Published: September 25, 1966
Released on J-STAGE: March 19, 2009
JOURNAL FREE ACCESSBehavior of membrane system in meiotic mitosis was observed in the pollen mother cells of Tradescantia paludosa with electron microscopes. Unlike the cases of somatic mitosis such as premeiotic mitoses (Maruyama 1963) and postmeiotic mitoses in T. paludosa (Maruyama 1966), and somatic mitoses in root meristematic cells (Porter and Machado 1960), the cisternal form of membranes in the cell vesiculate extensively at diakinesis. That is, the nuclear envelope and the cisternae in the cytoplasm as well break down into small vesicles, some of which fuse and swell to form vacuoles. At anaphases and telophases of both the 1st and the 2nd divisions, these elements, including the vacuoles, take parts in the formations of the new nuclear envelopes and the plasma membranes. After completion of the meiosis, a huge vacuole is formed in the microspore by fusion and swelling of the smaller vacuoles. The Golgi body seem to originate from these vesicles in the cytoplasm of the microspore which are formed from the disintegrating nuclear envelope and the cisternae in the cytoplasm at diakinesis. The intracytoplasmic cisternae are formed later in the microspore by branching of the nuclear envelope. From these results of observation, the relationship of various membranes in the cell was discussed.View full abstractDownload PDF (8628K) -
III. Postmeiotic mitosisKeizo Maruyama1966 Volume 31 Issue 3 Pages 257-269
Published: September 25, 1966
Released on J-STAGE: March 19, 2009
JOURNAL FREE ACCESSThe behavior of membranes in the cell during the postmeiotic mitosis was observed with the aid of an electron microscope. The postmeiotic mitosis in microspores is essentially similar to the premeiotic one (Maruyama 1963) in behavior of the cellular membranes. In late prophase, the nuclear envelope breaks down into pieces of cisternae, which mix with the cytoplasmic cisternae. These cisternae, again, differentiate into the nuclear envelope, the plasma membrane and the cisternae in the cytoplasm in telophase.
However, the distribution and movement of these cell components in postmeiotic mitosis is different from those in the premeiotic one. The cisternae concentrate only in one of the polar region of microspore at metaphase, where they take a polarized arrangement towards the ventral cell wall. Because of an uneven distribution of the cell components, the cell plate is laid down closely to the generative nucleus. This unequal cytokinesis seems to lead to a marked differential development of the two nuclei, generative and vegetative, in a pollen grain.View full abstractDownload PDF (6103K) -
A. A. Nethery, G. B. Wilson1966 Volume 31 Issue 3 Pages 270-275
Published: September 25, 1966
Released on J-STAGE: March 19, 2009
JOURNAL FREE ACCESSA wide range of both simple and complex derivatives of phenol produce the following characteristic antimitotic patterns: (1) a particular type of inhibition of onset of mitosis in which recovery is to supracontrol levels; (2) inhibition of the transition of late prophase to prometaphase and (3) a pattern of spindle disturbance qualitatively similar to that produced by colchicine. It is suggested that the nature and degree of the effect is largely determined by the electrochemical properties of the effective molecules.View full abstractDownload PDF (393K) -
II. DNA replication sequence of bone marrow chromosomes in vivoNéstor O. Bianchi1966 Volume 31 Issue 3 Pages 276-293
Published: September 25, 1966
Released on J-STAGE: March 19, 2009
JOURNAL FREE ACCESSThe duration of the cell cycle and the pattern of chromosome replication throughout the S period are studied in the bone marrow of the rat in vivo. From the analysis of 610 metaphases and 140 karyotypes with their corresponding autoradiographs it can be concluded:
1. The cell generation time is about 15 hours; the G1 period is about 4 hours; the S period lasts 7 hours and the G2 period comprises 2 to 3 hours.
2. The study of the labeling over the chromosomes allows the distinguishing of four different patterns corresponding to the initial, intermediate, late and final stages of the S phase.
3. The results obtained indicate that chromosomes start replication over partial areas. Later they extend DNA synthesis to their total length and at the final S stage only small replicating zones-not those at the starting point-can be detected over the chromosomes.
4. Observation about the chronology of chromosome replication point out that different pairs of chromosomes start and finish DNA synthesis at different moments. Homologue asynchrony was detected as much as at the beginning as at the end of the S phase.
5. The X chromosomes are among those which start replication the earliest; finishing DNA synthesis before several other pairs. In no case a late replicating X chromosome is observed.
6. The Y chromosome is the last chromosome to start replication and also the last one to finish it.
7. The semi-conservative fashion of chromosome replication and the existence of sister chromatids exchanges were detected by studying metaphases at the second division after labeling.View full abstractDownload PDF (3955K) -
B. N. Chowdaiah1966 Volume 31 Issue 3 Pages 294-301
Published: September 25, 1966
Released on J-STAGE: March 19, 2009
JOURNAL FREE ACCESSA comparative study of the chromosomes during spermatogenesis of four species of Diplopoda (Myriapoda) belonging to two families has been made. The diploid chromosome numbers of the described species vary from 12 to 24. In addition to the variation in numbers, the cytology of diplopods offers many points of interest. In all the species studied all the chromosomes are acrocentric. The male is the heterogametic sex and the sex-chromosome mechanism is of the XY type. The sex-chromosomes are characterized by their heteropycnosis and also by their differential behaviour, exhibiting prereductional division and lagging during meiotic divisions.View full abstractDownload PDF (491K) -
T. S. S. Dikshith1966 Volume 31 Issue 3 Pages 302-308
Published: September 25, 1966
Released on J-STAGE: March 19, 2009
JOURNAL FREE ACCESSSpermatids of Laccifer lacca are binucleate to start with, but become quadrinucleate due to the fusion of sister cells.
Of the four nuclei two are euchromatic and the other two are heterochromatic in nature. In the course of development each euchromatic nuclei develops a nuclear outgrowth by the elongation while the heterochromatic pair disintegrates taking no part in sperm formation. This results in the suppression of sperm formation in half of the gametic nuclei.
The elongated euchromatic nucleus eventually transforms itself into the core of the sperm without rejecting any nuclear part. Thus each cyst carries within it 32 sperms in the form of a bundle which at a subsequent stage of development splits into two subunits carrying 16 sperms each. The sperms are thin and thread-like ard are compactly arranged inside the bundle.View full abstractDownload PDF (1736K) -
Sajiro Makino1966 Volume 31 Issue 3 Pages 309-323
Published: September 25, 1966
Released on J-STAGE: March 19, 2009
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Y. C. Ting1966 Volume 31 Issue 3 Pages 324-329
Published: September 25, 1966
Released on J-STAGE: March 19, 2009
JOURNAL FREE ACCESSAt meiotic prophase of haploid maize, the number of microsporocytes forming 10 univalents or no bivalents, was found to be about 50 percent of the total 942 randomly selected cells. It was postulated that most of the duplicate factor inheritance, and perhaps also the triplicated and the quadruplicate factor inheritance in maize, are intrachromosomal.
The frequent appearance of 10 univalents and the persistent chainconfigurations of the infrequently formed bivalents at diakinesis constitute a convincing evidence that modern maize is an alloploid with perhaps a basic chromosome number of five.
The origin of spindle is discussed. The evidence that one or two strayed chromosomes were associated, at the centromeres, with an independent spindle at second meiotic metaphase, led to a conclusion that the spindle is of nuclear origin, probably in the centromeres of the chromosomes.View full abstractDownload PDF (1398K) -
D. S. Loyal, R. K. Grewal1966 Volume 31 Issue 3 Pages 330-338
Published: September 25, 1966
Released on J-STAGE: March 19, 2009
JOURNAL FREE ACCESSSalvinia auriculata Aublet under cultivation in several places in India and Rhodesia, S. Africa is pentaploid and show 2n=45 in leaf tip squashes.
Analysis of mega- and microsporocarps reveals respectively 62 per cent and 45 per cent abortive sporangia in which meiosis fails to occur and archesporium degenerates. In the functional mega- and microsporangia the course of meiosis is typical of the pentaploids. A high percentage of spore mother cells show failure of cytokinesis both at the close of first and second division resulting in monads which lack well organized nucleus. The above alongwith other irregularities of meiosis offset normal spore formation, completely.
The presence of multivalents indicates homology between the parental genomes to a fair degree. On this basis intraspecific origin of the present taxon is surmised.
The archesporium is eight-celled in both the types of sporangia. A reference to previous literature especially Mahabale and D'Mello (1952) shows that on this criterion apogamous reproduction was inferred. It is discussed that the eight-celled archesporium is not indicative of apogamy since other features of apogamy that follow eight-celled archesporium are totally lacking. Finally the role of vegetative apomixis in preserving sterile races of heterosporous ferns is discussed.View full abstractDownload PDF (1573K)
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