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S Inoué

Publications and source records attributed to S Inoué.

At least 19 recordsLinked to original sources
PubMed1991

Cell division in Dictyostelium with special emphasis on actomyosin organization in cytokinesis.

This study focuses on the dynamic reorganization of actin and myosin ("conventional" myosin, or myosin-II) during cytokinesis in D. discoideum. This is the first study identifying the birefringence of the spindle microtubules as well as three sets of microfilamentous structure in Dictyostelium. The change of organization in these fibrillar structures was followed in real-time with video microscopy, using a Universal Polarizing Microscope equipped with polarized-light (POL) and differential interference contrast (DIC) optics combined with digital image processing. High-frequency mitotic cells were obtained by semi-synchronous culture, and high-resolution observations were made by utilizing the agar-overlay method (Yumura et al.: Journal of Cell Biology 99:894-899, 1984). The molecular identity of the birefringent structures was determined by fluorescence microscopy. Through-focus observations were performed with an axial resolution of 0.3 micron depth of field. The actomyosin fibrils show a dramatic reorganization throughout mitosis. The fibrils at the leading lamellipodia disappear, and there is a striking assembly of the cortical actomyosin in pro-metaphase, which is accompanied by a decrease in cell volume. The cortical actomyosin gradually increases through anaphase. After late anaphase, very active polar lamellipodia, with an average life of less than 1 minute, are formed. We confirmed that the polar lamellipodia include actin, but not myosin-II. At the cleavage furrow, the microfilaments form two distinctive structures: circular contractile ring at the equator, and a cortical filament array parallel to the polar axis. Myosin is localized in the contractile ring, but not associated with the axial array of F-actin. Actomyosin in the contractile ring gradually transforms into cortical network at the posterior region of daughter cells. The constriction of the furrow is accompanied by a drastic efflux of water as evidenced by highly active contractile vacuole formation and turbulent motion of minute vesicles connected to the furrow. This study demonstrates the presence of a new microfilament structure, as well as the dynamic property of the contractile ring, and sheds new light on the contractile mechanisms underlying cytokinesis.

Actomyosin↗
PubMed1990

Effects of medial preoptic area lesions on sleep and wakefulness in unrestrained rats.

Bilateral radiofrequency lesions of the medial preoptic area (MPOA) in unrestrained male rats resulted in a significant decrease in slow wave sleep (SWS) in the light period throughout two postoperative weeks, although the night-active pattern of circadian rhythms was little affected. Both diurnal and nocturnal paradoxical sleep (PS) gradually increased after the lesions. Within one week, however, the daily amount of total sleep (SWS + PS) was recovered to the normal level, since the loss of diurnal SWS was compensated by an increase in nocturnal sleep at the expense of wakefulness. The MPOA lesions brought about a transient elevation of brain temperature, which lasted only for the diurnal period of the day of lesioning. It is speculated that the MPOA plays a definite role in the passage of sleep-regulatory information, especially concerning the circadian distribution of sleep.

Animals↗
PubMed1990

Chronic intake of panax ginseng extract stabilizes sleep and wakefulness in food-deprived rats.

The amount of wakefulness and slow wave sleep significantly fluctuated during 48 h food deprivation and subsequent recovery periods in freely behaving male rats. In contrast, such fluctuations were significantly less prominent in age-matched male rats chronically treated with Panax ginseng extract via drinking water. It is speculated that the ginseng extract may exert a stabilizing effect on sleep-waking disturbances which possibly accounts for its outstanding health-improving activities.

Animals↗
PubMed1990

Panax ginseng extract modulates sleep in unrestrained rats.

The amount of wakefulness and slow wave sleep (SWS) during the 12-h light period slightly but significantly decreased and increased, respectively, in freely behaving rats after continued 1-week intake of Panax ginseng extract through drinking water (15 mg/day). Paradoxical sleep was little affected. No sleep parameters were modulated by the treatment during the dark period. The diurnal SWS enhancement disappeared and recovered to the baseline level after 2 weeks of continued treatment. It is speculated that the well known health-improving effect of the ginseng may be, at least in part, related to an enhancement of sleep.

Animals↗
PubMed1990

Contractile proteins in Drosophila development.

In summary, we have used a multidisciplinary approach to the analysis of actomyosin-based motility during Drosophila embryogenesis. We have documented the movements of early embryogenesis with modern, video methods. We have characterized the cytoplasmic myosin polypeptide, made specific polyclonal antisera to the molecule, studied its distribution during early embryogenesis, cloned and partially characterized the gene that encodes it, and have recently completed the nucleotide sequence of a nearly full length cDNA that encodes the entire protein-coding region. We have initiated studies on myosin function in living embryos both by direct microinjection of antibodies and through classical genetics. To better understand how myosin function is regulated, we have begun analysis of its light chains. Finally, to investigate the molecular mechanism by which its function is integrated into a labile cytoskeleton, whose architecture is constantly changing, we have also investigated Drosophila spectrins. Together, these studies are designed to shed light on the dynamics of biologic form at the cellular level, with current focus on such complex processes as cytokinesis and morphogenesis.

Actins↗
PubMed1990

Co-circulating sleep substances interactingly modulate sleep and wakefulness in rats.

Putative sleep substances were infused either singly or in combination into the third ventricle of freely behaving male rats for 10 h nocturnal period. The nocturnal amount of slow wave sleep (SWS) and paradoxical sleep (PS), and the number and duration of their episodes were compared to those of the previous night under saline infusion. The single administration revealed that each substance elicited partially differential and partially common sleep-modulatory activity. SWS was enhanced by the d-type of di-1-methylheptyl-2,5-dioxocyclohexane-1,4-dicarboxylate (d-DOC, 2.3 nmol), delta-sleep-inducing peptide (DSIP 2.5 nmol), deoxyuridine (0.1 nmol), muramyl dipeptide (MDP, 2.0 nmol), and prostaglandin D2 (PGD2, 0.36 nmol). Cytidine (10 pmol) increased the number of SWS episodes and reduced their duration, whereas deoxyguanosine (10 pmol) prolonged the duration. Deoxycytidine (10 pmol) and the 1-type of DOC (0.25 nmol) enhanced PS. Uridine (10 pmol) enhanced both SWS and PS. The simultaneous or sequential administration of DSIP, MDP and uridine resulted in a combination-dependent or sequence-dependent change in sleep-waking dynamics, which was quite different from the time-course sleep-modulation induced by the single administration of each substance. The results suggest that co-circulating sleep substances might interact at least in part, either synergistically or antagonistically, on the sleep-regulatory mechanism.

Animals↗
PubMed1989

Awaking effect of prostaglandin E2 in freely moving rats.

The awaking effect of prostaglandin (PG) E2 was further examined in a long-term bioassay system. PGE2 in saline solution was infused between 11.00 and 17.00 h at 0.1, 1, 10, and 100 pmol/min (infusion volume 10 microliters/h) into the third cerebral ventricle of freely moving rats. These rats were otherwise infused with saline continuously and exhibited a circadian cycle, spending 70% of the daytime and 37% of the night in sleep. In the rats that received PGE2 infusion at 1, 10, and 100 pmol/min, slow wave sleep (SWS) decreased to 84%, 69% and 71% and paradoxical sleep (PS) to 85%, 37% and 40% of the paired controls. Thus, the effect of PGE2 was not specific to either SWS or PS. No effects were observed in the rats that received PGE2 at 0.1 pmol/min. After PGE2 infusion at 10 and 100 pmol/min, marked rebounds of both SWS and PS occurred during the night. SWS reduction by PGE2 was due to the shortened duration of SWS episodes, while SWS increase in the rebound phase was due to the increased number of episodes. PS reduction was due to both the shortened duration and decreased number of PS episodes and PS rebound was due to both the prolonged duration and increased number of episodes. The circadian sleep-wake cycle returned to the baseline on the first or second recovery day after PGE2 infusion. Sleep reduction by PGE2 was accompanied by elevation of the brain temperature and rebound increase of sleep occurred with the fall of the brain temperature.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

The phosphorylated analogue of DSIP enhances slow wave sleep and paradoxical sleep in unrestrained rats.

Continued 10-h nocturnal intracerebroventricular infusion of 0.5 nmol P-DSIP, the phosphorylated analogue of delta-sleep-inducing peptide (DSIP), significantly increased slow wave sleep (22%) and paradoxical sleep (81%) in unrestrained rats. The increase in the amount of sleep was largely due to an increase in the number of sleep episodes. Larger and smaller doses were ineffective in doses ranging from 0.025 to 25 nmol. The sleep-promoting potency of P-DSIP was 5 times greater than that of DSIP compared by the same assay.

Animals↗
PubMed1989

Biological activities caused by far-infrared radiation.

Contrary to previous presumption, accumulated evidence indicates that far-infrared rays are biologically active. A small ceramic disk that emits far-infrared rays (4-16 microns) has commonly been applied to a local spot or a whole part of the body for exposure. Pioneering attempts to experimentally analyze an effect of acute and chronic radiation of far-infrared rays on living organisms have detected a growth-promoting effect in growing rats, a sleep-modulatory effect in freely behaving rats and an insomiac patient, and a blood circulation-enhancing effect in human skin. Questionnaires to 542 users of far-infrared radiator disks embedded in bedclothes revealed that the majority of the users subjectively evaluated an improvement of their health. These effects on living organisms appear to be non-specifically triggered by an exposure to far-infrared rays, which eventually induce an increase in temperature of the body tissues or, more basically, an elevated motility of body fluids due to decrease in size of water clusters.

Animals↗
PubMed1989

Evidence that brain prostaglandin E2 is involved in physiological sleep-wake regulation in rats.

We reported in previous studies that prostaglandin E2 (PGE2) has central effects of augmenting wakefulness and suppressing slow-wave sleep (SWS) and paradoxical sleep (PS) in rats. In the present study, we tested the effect of AH 6809, an antagonist of PGE2 receptors, on sleep-wake activities. AH 6809 in saline was infused continuously into the third ventricle of freely moving rats at a rate of 2.1, 6.3, and 21 pmol/min from 2300 to 0500 hr. During the infusion at 21 pmol/min, wakefulness decreased to 82%, and SWS and PS increased to 122% and 161%, of the respective baseline values. These changes can be explained by AH 6809 antagonizing the endogenous PGE2 that acts to augment wakefulness in the brain. This explanation is supported by the fact that the infusion of AH 6809 at 21 pmol/min inhibited the wakefulness-promoting effect of PGE2 infused at 10 pmol/min. Moreover, the PGE2-related mechanisms for regulating sleep-wake activities may be different from those producing hyperthermia, because AH 6809 at 21 pmol/min had no primary effect on brain temperature and did not antagonize the hyperthermia produced by the PGE2 infusion. A diurnal infusion (1200 to 1800 hr) of AH 6809 at 21 pmol/min produced similar effects on sleep-wake activities compared with the nocturnal infusion (2300 to 0500 hr), although the PS increase was not significant, suggesting that the PGE2-related mechanisms are acting all day long with or without a circadian rhythm. These findings strongly suggest that endogenous PGE2 in the brain is involved in the physiological mechanisms for regulating sleep-wake activities.

Animals↗
PubMed1989

Asymmetric behavior of severed microtubule ends after ultraviolet-microbeam irradiation of individual microtubules in vitro.

The molecular basis of microtubule dynamic instability is controversial, but is thought to be related to a "GTP cap." A key prediction of the GTP cap model is that the proposed labile GDP-tubulin core will rapidly dissociate if the GTP-tubulin cap is lost. We have tested this prediction by using a UV microbeam to cut the ends from elongating microtubules. Phosphocellulose-purified tubulin was assembled onto the plus and minus ends of sea urchin flagellar axoneme fragments at 21-22 degrees C. The assembly dynamics of individual microtubules were recorded in real time using video microscopy. When the tip of an elongating plus end microtubule was cut off, the severed plus end microtubule always rapidly shortened back to the axoneme at the normal plus end rate. However, when the distal tip of an elongating minus end microtubule was cut off, no rapid shortening occurred. Instead, the severed minus end resumed elongation at the normal minus end rate. Our results show that some form of "stabilizing cap," possibly a GTP cap, governs the transition (catastrophe) from elongation to rapid shortening at the plus end. At the minus end, a simple GTP cap is not sufficient to explain the observed behavior unless UV induces immediate recapping of minus, but not plus, ends. Another possibility is that a second step, perhaps a structural transformation, is required in addition to GTP cap loss for rapid shortening to occur. This transformation would be favored at plus, but not minus ends, to account for the asymmetric behavior of the ends.

Guanosine Diphosphate↗
PubMed1988

Suppression of sleep by prostaglandin synthesis inhibitors in unrestrained rats.

Sleep-suppressive activity of prostaglandin synthesis inhibitors, diclofenac sodium (DF) and indomethacin (IM), was examined in unrestrained male rats. An intraperitoneal injection of 5 mg/kg IM, or an oral administration of 5 mg/kg DF and 10 mg/kg IM at an early phase of the light period transiently decreased slow wave sleep (SWS) and paradoxical sleep (PS) to 30-62% and 0-38%, respectively, of the control level in the first hour. An intravenous infusion of 0.4 mg DF or 0.4 mg IM or an intracerebroventricular infusion of 0.04 mg DF continuously during a 10-h diurnal period resulted in a significant decrease in SWS and PS by 9-17% and 17-21%, respectively, from the baseline value in the 12-h light period. The DF infusion was accompanied by a rebound rise in the nocturnal SWS and PS and the subsequent diurnal PS. The results indicate that the depletion of prostaglandin(s) in the brain is responsible for the DF- and IM-induced suppression of sleep.

Administration, Oral↗
PubMed1988

Progress in video microscopy.

The progress in video microscopy is reviewed from its early inception, especially with respect to improvements of the microscope image quality. Very recent advances that provide serial optical sections and depth of field as thin as 0.1 micron and that make possible the recording of birefringent images of individual microtubules (25 nm in diameter) directly in live, dividing cells are also documented.

Animals↗
PubMed1988

Microtubule dynamics in the chromosomal spindle fiber: analysis by fluorescence and high-resolution polarization microscopy.

We describe preliminary results from two studies exploring the dynamics of microtubule assembly and organization within chromosomal spindle fibers. In the first study, we microinjected fluorescently labeled tubulin into mitotic PtK1 cells and measured fluorescence redistribution after photobleaching (FRAP) to determine the assembly dynamics of the microtubules within the chromosomal fibers in metaphase cells depleted of nonkinetochore microtubules by cooling to 23-24 degrees C. FRAP measurements showed that the tubulin throughout at least 72% of the microtubules within the chromosomal fibers exchanges with the cellular tubulin pool with a half-time of 77 sec. There was no observable poleward flux of subunits. If the assembly of the kinetochore microtubules is governed by dynamic instability, our results indicate that the half-life of microtubule attachment to the kinetochore is less than several min at 23-24 degrees C. In the second study, we used high-resolution polarization microscopy to observe microtubule dynamics during mitosis in newt lung epithelial cells. We obtained evidence from 150-nm-thick optical sections that microtubules throughout the spindle laterally associate for several sec into "rods" composed of a few microtubules. These transient lateral associations between microtubules appeared to produce the clustering of nonkinetochore and kinetochore microtubules into the chromosomal fibers. Our results indicate that the chromosomal fiber is a dynamic structure, because microtubule assembly is transient, lateral interactions between microtubules are transient, and the attachment of the kinetochores to microtubules may also be transient.

Animals↗
PubMed1988

Three-dimensional localization and redistribution of F-actin in higher plant mitosis and cell plate formation.

The distribution of F-actin cables in dividing endosperm cells of a higher plant, Haemanthus, was visualized with the immunogold-silver-enhanced method and compared with the arrangement of immunogold-stained microtubules in the same cells. The three-dimensional distribution of F-actin cables and microtubules during mitosis and cell plate formation was analyzed using ultrathin optical sectioning of whole mounts in polarized light video microscopy. F-actin cables form a loose irregular network in the interphase cytoplasm. Much of this network remains outside of the spindle during mitosis. A few F-actin cables were detected within the spindle. Their pronounced rearrangement during mitosis appears to be related to the presence and growth of microtubule arrays. During prometaphase, actin cables located on the spindle surface and those present within the spindle tend to arrange parallel to the long axis of the spindle. Cables outside the spindle do not reorient, except those at the polar region, where they appear to be compressed by the elongating spindle. Beginning with mid-anaphase, shorter actin cables oriented in various directions accumulate at the equator. Some of them are incorporated into the phragmoplast and cell plate and are gradually fragmented as the cell plate is formed and ages. Actin cables adjacent to microtubule arrays often show a regular punctate staining pattern. Such a pattern is seldom observed in the peripheral cytoplasm, which contains few microtubules. The rearrangement of F-actin cables mimicks the behavior of spindle inclusions, such as starch grains, mitochondria, etc., implying that F-actin is redistributed passively by microtubule growth or microtubule-related transport. Thus F-actin or actomyosin-based motility does not appear to be directly involved in mitosis and cytokinesis in higher plants.

Actins↗