Cell Structure and Function

Cup-shaped Mitochondria in the Posterior Silk Gland of Bombyx mori in the Prepupal Stadium

Shiro Matsuura, Yutaka Tashiro

1976 Volume 1 Issue 2 Pages 137-145
Published: 1976
Released on J-STAGE: April 18, 2008

DOIhttps://doi.org/10.1247/csf.1.137

JOURNAL FREE ACCESS

Show abstractHide abstract

Mitochondria of the posterior silk gland cells show a series of characteristic morphological changes in the later pupal and in the prepupal stadium. In the fourth instar and in the very beginning of the fifth instar round or oval mitochondria predominate which are distributed rather uniformly in cytoplasm while in the fifth instar, elongated mitochondria predominate which are arranged radially along the canal system. In the prepupal stadium a number of cup-shaped mitochondria appear which engulf a small portion of cytoplasm. It was suggested that the formation of such cup-shaped mito- chondria in the cells is induced by a rapid increase in the ecdysone titer in the prepupal stadium and that these mitochondria probably play some role for the catabolic processes in the same stadium.

View full abstract

Download PDF (13382K)
Parasexual Hybridization in Cellular Slime Molds.II. The Appearance and Characterization of Interspecific Hybrids between Dictyostelium discoideum and D. mucoroides

Yasuko Miyake, Yoshio Fukui

1976 Volume 1 Issue 2 Pages 147-154
Published: 1976
Released on J-STAGE: April 18, 2008

DOIhttps://doi.org/10.1247/csf.1.147

JOURNAL FREE ACCESS

Show abstractHide abstract

Three drug resistant mutants of Dictyostelium discoideum andD. mucoroides were employed to demonstrate the occurrence of interspecifichybridization. Interspecific hybrids appeared at a frequency of 4 x 10^-5, whereas intraspecific hybrids appeared at a frequency of 1 x 10^-3. Nineteen interspecific hybrids were serially subcultured to investigate their genetic traits. The results showed that the progenies of the interspecific hybrids retained the genetic markers of both parents in a manner similar to intraspecific hybrids. The characterization of the interspecific hybrids demonstrated that parasexual hybridization occurred even between two different species. The present study showed that genetic analysis between different species of cellular slime molds could be performed by applying this interspecific parasexual system.

View full abstract

Download PDF (2799K)
Functional Asymmetry in Excitable Surface Membrane of Protoplasmic Droplet Isolated from Nitella by Photosensitized Oxidation

Tetsuo Ueda, Makoto Muratsugu, Yonosuke Kobatake

1976 Volume 1 Issue 2 Pages 155-164
Published: 1976
Released on J-STAGE: April 18, 2008

DOIhttps://doi.org/10.1247/csf.1.155

JOURNAL FREE ACCESS

Show abstractHide abstract

Photooxidations of protoplasmic droplets of Nitella were performed by crystal violet (C.V.), rose bengal (R.B.) and methylene blue (M.B.) from the inside or outside of the membrane. Various physical prop-erties of the droplet were examined. External treatment of the membrane by C.V. induced a temporary increase of resistance and a gradual depolarization of the membrane potential. Excitability disappeared after the depolarization, but the surface tension remained constant. Both membrane potential and resistance remained constant when the droplet was modified by C.V. from the inside, and the excitability was retained. Tension at the surface, however, decreased sharply by a factor of 100. Internal application of R.B. decreased resistance and depolarized the membrane potential by a maximum 20 mV. External treatment with R.B. caused a temporary decrease of resistance with depolarization by about 100 mV. Adsorption of M.B. on the surface membrane led to a decrease in resistance without changing the membrane potential under light illumination, and this was followed by abrupt depolarization. These results indicate that membrane potential and excitability of the protoplasmic droplet are governed largely by the structure at the outermost surface between the protoplasm and external solution and that the tension at the surface is maintained by the internal structure of the protoplasm.

View full abstract

Download PDF (841K)
Electric Characteristics and Cytoplasmic Streaming of Characeae Cells Lacking Tonoplast

Masashi Tazawa, Munehiro Kikuyama, Teruo Shimmen

1976 Volume 1 Issue 2 Pages 165-176
Published: 1976
Released on J-STAGE: April 18, 2008

DOIhttps://doi.org/10.1247/csf.1.165

JOURNAL FREE ACCESS

Show abstractHide abstract

The tonoplast of Characeae internode was removed by replacing the cell sap with solution containing a Ca²⁺-chelating agent EGTA [Cethyleneglycol-bis-(β-aminoethyl ether) N, N'-tetraacetic acid]. After replacement, small endoplasmic granules and endoplasmic drops without clear outline were observed in the vacuole. These observations confirmed the disappearance of the tonoplast. Chloroplasts in the endoplasmic drop were often observed to rotate. The endoplasm remaining on the cortical gel flowed actively at nearly the same rate as endoplasm in cytoplasmic streaming of normal cells for at least several hours. ATP and Mg²⁺ were indispensable for cytoplasmic streaming in tonoplast-free cells. The tonoplast-free cells had very high membrane resistance. The current-voltage relationship showed that the membrane rectifying action was strengthened by removing the tonoplast. The cells elicited prolonged action potentials of rectangular shape. Cessation of cytoplasmic streaming accompanied with the action potential was never observed in tonoplast-free cells although this is generally observed in normal cells. These phenomena on tonoplast-free cells occurred only when the concentration of free Ca²⁺ in the perfusion medium was less than 10^-6 M. The calcium concentration in the protoplasm was analyzed to estimate the free Ca²⁺ concentration in the cell after disintegration of the tonoplast and dispersion of the cytoplasm-bound Ca into the entire cell space.

View full abstract

Download PDF (1164K)
Synchrony of Burkitt Lymphoma Cells Induced by Hydroxyurea

Tadaaki Miyamoto, Michinori Watanabe, Yosinobu Takabe, Toyozo Terasima

1976 Volume 1 Issue 2 Pages 177-185
Published: 1976
Released on J-STAGE: April 18, 2008

DOIhttps://doi.org/10.1247/csf.1.177

JOURNAL FREE ACCESS

Show abstractHide abstract

Synchronization of Burkitt lymphoma cells grown in suspen-sion was attempted taking advantage of the dual action of hydroxyurea (HU) of blocking the entry G1 cells into S phase and the selective inactivation of S phase cells. The drug at 0.85 mM concentration prevented the incorporation of 3H-thymidine into DNA by more than 95 % and killed a certain fraction of cells which was comparable to a fraction of S phase cells except for the late S phase cells. This drug, however, allowed cells in other phases to progress through the cycle. The exposure time needed to synchronize the cell population was 15 h which was about 6 h longer than G1+ G2 + M periods. The extra-time of 6 h was due to the delayed progression of late S and G2 cells through the cell cycle. The synchronized growth curve determined by either soft agar colony assay or electronic counting was composed of two fractions showing different rates of division. It seemed that rapidly and slowly dividing fractions were derived from fractions of ce ls at G1 phase and at G2 + late S phase, respectively, when HU was introduced. The delaying effect of HU on the progression of G2 and late S cells appeared to be a limiting factor of the induced synchrony. Miyamoto, Tadaaki;Watanabe, Michinori;Takabe, Yosinobu;Terasima, Toyozo

View full abstract

Download PDF (835K)
Colcemid Effects on Mitotic Synchrony and Synchronized Cells

Hiroshi Ohara, Toyozo Terasima

1976 Volume 1 Issue 2 Pages 187-195
Published: 1976
Released on J-STAGE: April 18, 2008

DOIhttps://doi.org/10.1247/csf.1.187

JOURNAL FREE ACCESS

Show abstractHide abstract

The division and growth of mitotic cells were examined after pretreatment with colcemid. Colcemid acted on interphase cells near the mitotic period and blocked the entry of cells into metaphase. Colcemid treat-ment at 0.02 to 0.04 μg/ml for 2 hours was adequate for obtaining undeterio-rated synchronous cell growth. During this treatment mitotic collections in-creased approximately 40% compared to the untreated control culture. The purity of the harvested cells was more than 85 %. The median generation time did not differ significantly between reversed cells and untreated cells. How-ever, colcemid-treatment resulted in delaying the increase of DNA by about 2 hours during synchronous growth. A similar delay was found in the cyclic change of X-ray survival during the DNA synthetic period.

View full abstract

Download PDF (864K)
Method for Intracellular Injection by Cell Fusion using Erythrocyte Ghosts

Toshikazu Nishimura, Mitsuru Furusawa, Masaru Yamaizumi, Yoshio Okada

1976 Volume 1 Issue 2 Pages 197-200
Published: 1976
Released on J-STAGE: April 18, 2008

DOIhttps://doi.org/10.1247/csf.1.197

JOURNAL FREE ACCESS

Show abstractHide abstract

A new technique for intracellular microinjection was developed with mammalian erythrocyte ghosts as "syringes" making use of the cell fusion of Sendai virus (HVJ). By "gradual" hemolysis hemoglobin was replaced by foreign substances without diminishing the fusion capacity of the erythrocyte membrane. HVJ-mediated cell fusion between the erythrocyte ghosts containing foreign substances and the target cells resulted in injections of substances into the cytoplasm of the target cells. With this relatively simple technique, definite amounts of substances were injected into single cells at high frequency.

View full abstract

Download PDF (409K)
The Possible Existence of a Vitamin A-storing Cell System

Eichi Yamada, Kazushige Hirosawa

1976 Volume 1 Issue 2 Pages 201-204
Published: 1976
Released on J-STAGE: April 18, 2008

DOIhttps://doi.org/10.1247/csf.1.201

JOURNAL FREE ACCESS

Download PDF (8000K)

Register with J-STAGE for free!