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S Inoué

Publications and source records attributed to S Inoué.

At least 109 records · Page 6Linked to original sources
PubMed1984

Differential sleep-promoting effects of five sleep substances nocturnally infused in unrestrained rats.

Sleep-inducing and sleep-maintaining effects of five different putative sleep substances were compared by the same nocturnal 10-hr intracerebroventricular infusion technique in otherwise saline-infused, freely moving male rats. Delta-sleep-inducing peptide (2.5 nmol), which induces electroencephalogram delta (slow)-wave patterns, was rapidly effective in increasing both slow-wave sleep and paradoxical sleep but the effects were not long-lasting. Muramyl dipeptide (2 nmol) induced excessive slow-wave sleep in the middle of the infusion period, accompanying a simultaneous elevation of brain temperature. However, paradoxical sleep was not affected. Component B of sleep-promoting substance (2 brainstem equivalents), a partially purified extract from rats deprived of sleep for 24-hr, was markedly effective in inducing and maintaining both kinds of sleep. Prostaglandin D2 (0.36 nmol) was more effective in enhancing sleep at the later period of the infusion period. Uridine (10 pmol) caused a mild but long-lasting increase in sleep, especially in paradoxical sleep. Thus, each substance exhibited compound-specific sleep-modulating properties.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1983

Prostaglandin D2, a cerebral sleep-inducing substance in rats.

We continuously monitored the circadian sleep patterns of unrestrained rats for more than 96 hr and infused various prostaglandins into their third ventricles for 10 hr to study the effects on inducing sleep. Prostaglandin D2 at 6 fmol/min had no effect on either slow wave sleep or paradoxical sleep. However, prostaglandin D2 at as little as 60 fmol/min caused a significant amount of excess slow wave sleep as compared with the control level during saline infusion. Paradoxical sleep was induced by prostaglandin D2 at doses greater than 600 fmol/min. Prostaglandin D2 (600 fmol/min) increased slow wave sleep by 33% and paradoxical sleep by 56%. Although prostaglandin F2 alpha (600 fmol/min) increased the amount of slow wave sleep, its activity was less than that of the same amount of prostaglandin D2. Prostaglandin E2 (600 fmol/min) had no effect on increasing the amounts of both slow wave sleep and paradoxical sleep. During the infusion of prostaglandin D2, rats were easily aroused by clap sound stimulation and their sleeping and waking postures remained normal. Further, their sleep was episodic, as observed in the physiological sleep of rats.

Animals↗
PubMed1983

Ultrastructure of Reichert's membrane, a multilayered basement membrane in the parietal wall of the rat yolk sac.

The ultrastructure of Reichert's membrane, a thick basement membrane in the parietal wall of the yolk sac, has been examined in 13-14-d pregnant rats. This membrane is composed of more or less distinct parallel layers, each one of which resembles a common basement membrane. After routine fixation in glutaraldehyde followed by osmium tetroxide, the layers appear to be mainly composed of 3-8-nm thick cords arranged in a three-dimensional network. Loosely scattered among the cords are unbranched, straight tubular structures with a diameter of 7-10 nm, which mainly run parallel to the surface and to one another; they are referred to as basotubules. Permanganate fixation emphasizes the presence of a thick feltwork of irregular material around basotubules. Finally, minute dot-like structures measuring 3.5 nm and referred to as double pegs are present within the meshes of the cord network. Reichert's membranes have been treated for 2-48 h at 25 degrees C with plasmin, a proteolytic enzyme known to rapidly digest laminin and fibronectin. After a 2-h treatment, most of the substance of the cords is digested away leaving a three-dimensional network of 1.5-2.0-nm thick filaments. The interpretation is that the cords are formed of a plasmin-resistant core filament and a plasmin-extractable sheath. When plasmin treatment is prolonged for 15 h or longer, the filaments are dissociated and disappear, while basotubules are maintained. Plasmin digestion also reveals that basotubules are composed of two parts: a ribbon-like helical wrapping and tubule proper. Further changes in the tubule under plasmin influence are interpreted as a dissociation into pentagonal units suggestive of the presence of the amyloid P component. After 48 h of plasmin treatment, basotubules are further disaggregated and dispersed, leaving only linearly arranged double pegs. Reichert's membranes with or without a 2-hr plasmin treatment have been immunostained by exposure to antibodies against either laminin or type IV collagen with the help of peroxidase markers. The results indicate that the sheath of the cords contains laminin antigenicity, while the core filament contains type IV collagen antigenicity. It is proposed that Reichert's membrane consists mainly of a three-dimensional network of cords composed of a type IV collagen filament enclosed within a laminin-containing sheath. Also present are basotubules--which may contain the amyloid P component--and double pegs whose nature is unknown.

Animals↗
PubMed1982

Acrosomal reaction of thyone sperm. I. Changes in the sperm head visualized by high resolution video microscopy.

Structural changes inside the head of Thyone sperm undergoing the acrosomal reaction were followed with a high-resolution, differential interference contrast (DIC) video microscope. The beating sperm, adhering by their midpiece to the cover slip of a wedge perfusion chamber, were activated by a calcium ionophore (20 microM A23187) suspended in sea water containing 50 mM excess CaCl2. Before activation of the sperm, the acrosomal region appears as a 1.1-microM diameter sphere, slightly less dense than the rest of the sperm head. Upon activation, the acrosome pops; the acrosomal region suddenly swells and its refractive index drops. After approximately 1 s, a crescent-shaped periacrosomal cup appears behind the acrosomal vacuole. In the next several seconds, the cup loses more refractive index and expands forward as the acrosomal process extends. The acrosomal vacuole becomes smaller, but without appreciable drop in refractive index. These observations, coupled with the behavior of the extending acrosomal process reported in the companion paper, and in electron microscopy (EM) and early physiological studies, suggest that the acrosomal process is extended by a combination of the explosive polymerization of actin and the osmotic swelling of the periacrosomal cup material. In this paper, we also consider the meaning of the enhanced DIC image seen in the high-resolution video microscope, and discuss the reliability of measurements on small linear dimensions made with the DIC microscope.

Acrosome↗
PubMed1982

Acrosomal reaction of Thyone sperm. II. The kinetics and possible mechanism of acrosomal process elongation.

Thyone sperm were induced to undergo the acrosomal reaction with a calcium ionophore A23187 in sea water containing 50 mM excess CaCl2, and the extension of the acrosomal process was recorded with high-resolution, differential interference contrast video microscopy at 60 fields/sec. The length of the acrosomal process was measured at 0.25-s intervals on nine sperm. When the data were plotted as (length)2 vs. time, the points fell exactly on a straight line except for the initial and very final stages of elongation. Cytochalasin B alters the rate of elongation of the acrosomal process in a dose-dependent way, inhibiting the elongation completely at high concentrations (20 micrograms/ml). However, no inhibition was observed unless excess Ca++ was added to sea water. The concentration of actin in the periacrosomal cup of the unreacted sperm is as high as 160 mg/ml; we calculate this concentration from the number and lengths of the actin filaments in a fully reacted sperm, and the volume of the periacrosomal cup in the unreacted sperm. These results are consistent with the hypothesis proposed earlier that monomers add to the ends of the actin filaments situated at the tip of the growing acrosomal process (the preferred end for monomer addition), and that the rate of elongation of the process is limited by diffusion of monomers from the sperm head (periacrosomal cup) to the tip of the elongating process. During the extension of the acrosomal process, a few blebs distributed along its lengths move out with the process. These blebs maintain a constant distance from the tip of the growing process. At maximum length, the straight acrosomal process slackens into a bow, and numerous new blebs appear. A few seconds later, the process suddenly straightens out again and sometimes actually contracts. The behavior of the blebs indicates that membrane is inserted at the base of the growing acrosomal process, and that membrane assembly and water uptake must be coupled to actin assembly during elongation. We discuss how the dynamic balance of forces seems to determine the shape of the growing acrosomal process, and how actin assembly may be controlled during the acrosomal reaction.

Acrosome↗
PubMed1982

Evidence that myosin does not contribute to force production in chromosome movement.

Antibody against cytoplasmic myosin, when microinjected into actively dividing cells, provides a physiological test for the role of actin and myosin in chromosome movement. Anti-Asterias egg myosin, characterized by Mabuchi and Okuno (1977, J. Cell Biol., 74:251), completely and specifically inhibits the actin activated Mg++ -ATPase of myosin in vitro and, when microinjected, inhibits cytokinesis in vivo. Here, we demonstrate that microinjected antibody has no observable effect on the rate or extent of anaphase chromosome movements. Neither central spindle elongation nor chromosomal fiber shortening is affected by doses up to eightfold higher than those require to uniformly inhibit cytokinesis in all injected cells. We calculate that such doses are sufficient to completely inhibit myosin ATPase activity in these cells. Cells injected with buffer alone, with myosin-absorbed antibody, or with nonimmune gamma-globulin, proceed normally through both mitosis and cytokinesis. Control gamma-globulin, labeled with fluorescein, diffuses to homogeneity throughout the cytoplasm in 2-4 min and remains uniformly distributed. Antibody is not excluded from the spindle region. Prometaphase chromosome movements, fertilization, pronuclear migration, and pronuclear fusion are also unaffected by microinjected antimyosin. These experiments demonstrate that antimyosin blocks the actomyosin interaction thought to be responsible for force production in cytokinesis but has no effect on mitotic or meiotic chromosome motion. They provide direct physiological evidence that myosin is not involved in force production for chromosome movement.

Actins↗
PubMed1981

Video image processing greatly enhances contrast, quality, and speed in polarization-based microscopy.

Video cameras with contrast and black level controls can yield polarized light and differential interference contrast microscope images with unprecedented image quality, resolution, and recording speed. The theoretical basis and practical aspects of video polarization and differential interference contrast microscopy are discussed and several applications in cell biology are illustrated. These include: birefringence of cortical structures and beating cilia in Stentor, birefringence of rotating flagella on a single bacterium, growth and morphogenesis of echinoderm skeletal spicules in culture, ciliary and electrical activity in a balancing organ of a nudibranch snail, and acrosomal reaction in activated sperm.

Acrosome↗
PubMed1981

Experimental simulation of neuroendocrine dynamics at periparturient periods--a synthetic approach to pregnancy maintenance, parturition and lactation by programmed infusion of sex steroids in ovariectomized rats.

The blood levels of progesterone (P) and estradiol (E2) were artificially controlled in rats ovariectomized on days 19-20 of pregnancy (day 1: sperm in vaginal smears) by 48-168 h intravenous infusions according to 15 different temporally variable programs. The predominance of P infused in various curves for longer than 72 h, caused postmature deliveries on days 24-26 accompanying difficulties in labor and the lack of lactation, although changes in E2 levels antagonistically accelerated the timing of delivery. The most successful delivery and subsequent lactation were induced by an infusion of total amount of 1.5 mg P for 48 h (days 19-21) at a linearly decreasing rate in combination with an infusion of a total amount of 875 ng E2 for 72 h (days 19-22) at a slowly increasing rate, reaching a plateau in the morning of day 21 and rapidly decreasing to nil after that. Spontaneous delivery occurred on day 22 with a normal range of labor duration and no incidence of stillbirth. No further supply of sex steroids was required for the maintenance of lactation. Blood levels of prolactin shortly after delivery were much higher in these lactating ovariectomized rats than in non-lactating animals. The neuroendocrine dynamics at periparturient periods, which triggers the termination of pregnancy and then the induction of parturition and lactation, is discussed in relation to the results of these simulation experiments.

Animals↗
PubMed1979

Motility of the microtubular axostyle in Pyrsonympha.

The rhythmic movement of the microtubular axostyle in the termite flagellate, Pyrsonympha vertens, was analyzed with polarization and electron microscopy. The protozoan axostyle is birefringent as a result of the semi-crystalline alignment of approximately 2,000 microtubules. The birefringence of the organelle permits analysis of the beat pattern in vivo. Modifications of the beat pattern were achieved with visible and UV microbeam irradiation. The beating axostyle is helically twisted and has two principal movements, one resembling ciliary and the other flagellar beating. The anterior portion of the beating axostyle has effective and recovery phases with each beat thereby simulating the flexural motion of a beating cilium. Undulations develop from the flexural flipping motion of the anterior segment and travel along the axostyle like flagellar waves. The shape of the waves differs from that of flagellar waves, however, and are described as sawtooth waves. The propagating sawtooth waves contain a sharp bend, approximately 3 micron in length, made up of two opposing flexures followed by a straight helical segment approximately 23 micron long. The average wavelength is approximately 25 micron, and three to four sawtooth waves travel along the axostyle at one time. The bends are nearly planar and can travel in either direction along the axostyle with equal velocity. At temperatures between 5 degrees and 30 degrees C, one sees a proportionate increase or decrease in wave propagation velocity as the temperature is raised or lowered. Beating stops below 5 degrees C but will resume if the preparation is warmed. A microbeam of visible light shone on a small segment of the axostyle causes the typical sawtooth waves to transform into short sine-like waves that accumulate in the area irradiated. Waves entering the affected region appear to stimulate waves already accumulated there to move, and waves that emerge take on the normal sawtooth wave pattern. The effective wavelengths of visible light capable of modifying the wave pattern is in the blue region of the spectrum. The axostyle is severed when irradiated with an intense microbeam of UV light. Short segments of axostyle produced by severing it at two places with a UV microbeam can curl upon themselves into shapes resembling lockwashers. We propose that the sawtooth waves in the axostyle of P. vertens are generated by interrow cross-bridges which are active in the straight regions.

Animals↗
PubMed1978

Mitosis in Barbulanympha. I. Spindle structure, formation, and kinetochore engagement.

Successful culture of the obligatorily anaerobic symbionts residing in the hindgut of the wood-eating cockroach Cryptocercus punctulatus now permits continuous observation of mitosis in individual Barbulanympha cells. In Part I of this two-part paper, we report methods for culture of the protozoa, preparation of microscope slide cultures in which Barbulanympha survived and divided for up to 3 days, and an optical arrangement which permits observation and through-focus photographic recording of dividing cells, sequentially in differential interference contrast and rectified polarized light microscopy. We describe the following prophase events and structures: development of the astral rays and large extranuclear central spindle from the tips of the elongate-centrioles; the fine structure of spindle fibers and astral rays which were deduced in vivo from polarized light microscopy and seen as a particular array of microtubules in thin-section electron micrographs; formation of chromosomal spindle fibers by dynamic engagement of astral rays to the kinetochores embedded in the persistent nuclear envelope; and repetitive shortening of chromosomal spindle fibers which appear to hoist the nucleus to the spindle surface, cyclically jostle the kinetochores within the nuclear envelope, and churn the prophase chromosomes. The observations described here and in Part II have implications both for the evolution of mitosis and for understanding the mitotic process generally.

Anaerobiosis↗
PubMed1978

Mitosis in Barbulanympha. II. Dynamics of a two-stage anaphase, nuclear morphogenesis, and cytokinesis.

Anaphase in Barbulanympha proceeds in two discrete steps. In anaphase-A, chromosomal spindle fibers shorten and chromosomes move to the stationary centrosomes. In anaphase-B, the central spindle elongates and ("telophasic") bouquets of chromosomes, with kinetochores still connected by the shortened chromosomal fibers to the centrosomes, are moved far apart. The length, width, and birefringence of the central spindle remain unchanged throughout anaphase-A. In anaphase-B, the central spindle elongates up to fivefold. During elongation, the peripheral fibers of the central spindle splay, first anteriorly and then laterally. The remaining central spindle progressively becomes thinner and the retardation decreases; however, the coefficient of birefringence stays approximately constant. The nuclear envelope persists throughout mitosis in Barbulanympha and the nucleus undergoes an intricate morphological change. In prophase, the nucleus engulfs the spindle; in early anaphase-A, the nuclear envelope forms a seam anterior to the spindle, the nucleus thus transforms into a complete sleeve surrounding the central spindle. In late anaphase-A, the middle of the seam opens up in a cleft as the lips part; in anaphase-B, the cleft expands posteriorly, progressively exposing the central spindle. Finally, the cleft partitions the nucleus into two. The nuclear envelope shows an apparent elasticity and two-dimensional fluidity. Localized, transient deformations of the nuclear envelope indicate poleward and counter-poleward forces acting on the kinetochores embedded in the envelope. These forces appear responsible for nuclear morphogenesis as well as anaphase chromosome movement. At the end of anaphase-B, the two rostrate Barbulanympha may swim apart of be poked apart into two daughter cells by another organism cohabiting the host's hindgut.

Anaerobiosis↗
PubMed1977

Biocrystals.

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Animals↗