Katsumi Ueda

Transformation of the Golgi apparatus in the cell cycle of a green alga,Micrasterias americana

SummaryTransformation of the Golgi apparatus in the stages of the cell cycle ofMicrasterias americana was investigated with an electron microscope. In the resting cell, dictyosomes consisted of eleven cisternae, the distal-most cisterna of which was partially network-shaped. During the developmental stages of the new half cell followed by nuclear division, dictyosomes produced “dark vesicles” and “large vesicles” at the peripheries of the distal cisternae, thus diminishing the diameter of the distal cisternae and their numbers. Finally, dictyosomes with six or seven cisternae of small diameter were found when the new half cell reached to full size as a mother half cell. At this stage, the small dictyosomes produced “flat vesicles”. Thereafter, dictyosomes recovered the size and number of their constituent cisternae, being supplied a membrane and substrate from the primary vesicles. Lysosomes divided the dictyosomes in two, and these divided dictyosomes seemed to regenerate in one case and to disorganize in another. The occurrence of large vesicles was also confirmed using the negative staining method in growing cells.

Die quantitative Bestimmung des DNS-Gehalts in den Zellen von Cyanophyceen durch Fluorochromierung mit Coriphosphin1

Summary The DNA content of cyanophyceae cells was determined by measuring the intensity of fluorescence in nuclear equivalent, stained by the fluorochrome coriphosphin. In the „interphase stage‟ cells of the Cyanophyceae under investigation (Microcystis marginata, Anabaena baltica, Oscillatoria chlorina, and Calothrix braunii) contain a constant amount of DNA, respectively. Prior to the division of nucleoids the content of DNA is doubled, and during nucleoid division the previously increased amount of DN A is exactly reduced to half its height. In comparison with vegetative cells, resting cells (akinetes) of Anabaena baltica contain a multiple of DNA, most probably they are „polyploid‟. As the quality of fluorescence in heterocysts differs from that in vegetative cells, a quantitative comparison is not allowed here.

Formation of the Nuclear Envelope during Mitotic Anaphase in Spirogyra

The formation of the nuclear envelope in the mitosis ofSpirogyra was studied with an electron microscope. The nuclear envelope was disrupted around the spindle equator in the metaphase. Many small vesicles were observed in the metaphase spindle. These vesicles surrounded the masses of chromosomes and nucleolar substance in the early anaphase, and they fused with each other to form daughter nuclear envelopes during the early anaphase. The formation of new envelopes from small vesicles at such an early mitotic anaphase is reported here for the first time. The possible origin of these vesicles is also discussed.

The Fluorescence Spectrum from DNA in the Centroplasm of a Blue Green Alga, Oscillatoria princeps, Treated with Coriphosphin

Summary Spectra of secondary fluorescences from centroplasms of a blue green alga, Oscillatoria princeps , treated with coriphosphin solution were investigated, and their spectra were compared with those of coriphosphin solution containing DNA. The maximum intensity of fluorescence in the centroplasm occurred at 530 nm. The maximum peak of the fluorescent light of coriphosphin solutions with DNA lay also near 530 nm. This fact suggests that the fluorescent light in the centroplasms is derived from DNA. The fluorescence intensity gradually decreased when cells were continuously irradiated with UV light. The chromatoplasm radiated native fluorescent light at 590 and 670 nm. This is probably derived from photosynthetic pigments.

Elektronenmikroskopische Struktur der Blaualge Oscillatoria minima Gicklhorn unter besonderer Berücksichtigung der Zellteilung1)1)Die Durchführung dieser Arbeit wurde mir durch ein Forschungsstipendium der Alexander-von-Humboldt-Stiftung ermöglicht.

Summary The inner layer of the longitudinal walls of Oscillatoria minima is continuous with the crosswalls. Before a crosswall develops, an electron-transparent plasmatic region is recognized where the transverse wall is expected to appear. The growth of the thylakoids seems to begin just before the crosswall-formation, and continues during and after cell-division. At the margin of the developing transverse wall, a electron dense zone, sickle-shaped in cross section is always revealed. It is assumed that this zone plays an important role in the crosswall-formation such as in the production of cellwall-material. Sometimes a body with coiled membranes similar to the mesosomes of bacteria, can be observed; polyphosphate bodies, polyhedral bodies, osmiophilic granules, ribosomes, DNA-fibrils and rarely small vesicles are also recognized.

Licht- und elektronenmikroskopische Untersuchungen über die Keritomie bei Oscillatoria Borneti Zukal und O. pseudogeminats G. Schmid1)

Summary Keritomic vacuoles in Oscillatoria Borneti are stained with neutralred but not with KJJ and sudan III, and neither react with Millons- and PAS-reagent, nor show the fluorescence with nileblue. The plasmolysis by glucose is reversible, if applied for less than five minutes. The osmotic pressure of the cells which border on the plasmolysis corresponds to that of a 0.25 mol glucose solution. The development of keritomy is accelerated by light. It is revealed by the electronmicroscope that the thylakoid-membranes of O. Borneti and O. pseudogeminata consist of three layers, outer two are strongly contrasted and the inner one are less contrasted. Each layer is 2.5 nm thick. The keritomic vacuole is surrounded by a membrane, the structure and the thickness of which correspond to those of the thylakoidmembrane. It is concluded from the electronmicroscopic figures that the keritomy in both Oscillatoria species results from the volume-increase of the thylakoid content. The phenomenon of keritomy is assumed as a normal process of the cell development. The content of the keritomic vacuoles could not be determined. There are polyphosphate- and polyhedral bodies, osmiophilic granules, ribosomes and DNS-fibrils in the protoplast of both Oscillatoria.