Microtubules and Filaments in the Filopodia of the Secondary Mesenchyme Cells of Arbacia Punctulata and Echinarachnius Parma

1969 ◽  
Vol 5 (1) ◽  
pp. 195-210
Author(s):  
L. G. TILNEY ◽  
J. R. GIBBINS
Keyword(s):  
Fine Structure ◽  
Hydrostatic Pressure ◽  
Cell Body ◽  
The Other ◽  
Arbacia Punctulata ◽  
Contraction Process ◽  
Other Hand ◽  
Mesenchyme Cells

In an attempt to understand the mechanism of contraction of the filopodia of the secondary mesenchyme cells and thus secondary invagination of the archenteron, the fine structure of these processes was examined. Whereas microtubules are commonly encountered in the cell body and at the base of the filopodia, very few (one or two) are present near the tip of the filopodia. Instead the slender processes are filled with 50-Å filaments. Colchicine and hydrostatic pressure were applied to the embryos to elucidate the action of these different fibrous elements. Both agents cause cessation of archenteron movement and the disassembly of the microtubules. Hydrostatic pressure causes the disappearance of the filaments as well. Because of the small numbers of microtubules in the slender filopodia and the fact that in no other system is there any evidence for contraction of these elements, it was concluded that they do not function in the contraction process, but are probably involved in the formation of these cell extensions: hence the effect of colchicine on archenteron movement. The 50-Å filaments, on the other hand, are likely candidates for the contraction process.

Translocation of the neuronal cytoskeleton and axonal locomotion

1982 ◽  
Vol 299 (1095) ◽  
pp. 313-327 ◽  
Keyword(s):  
Plasma Membrane ◽  
Axonal Transport ◽  
Cell Body ◽  
Cytoskeletal Proteins ◽  
The Other ◽  
Current Understanding ◽  
Axonal Elongation ◽  
Neuronal Cytoskeleton ◽  
Other Hand ◽  
Neuron Cell Body

Recent studies of axonal transport indicate that cytoskeletal proteins are assembled into polymers in the neuron cell body and that these polymers move from the cell body toward the end of the axon. On the other hand, membranous elements appear to be inserted into the axonal plasma membrane preferentially at the end of the axon. These new observations are explored in relation to our current understanding of axonal elongation.

Morphological and functional aspects of two different types of hair cells in the goldfish sacculus

1989 ◽  
Vol 62 (6) ◽  
pp. 1330-1343 ◽  
Author(s):  
I. Sugihara ◽  
T. Furukawa
Keyword(s):  
Cell Body ◽  
Hair Cells ◽  
The Other ◽  
Resting Potential ◽  
K Channel ◽  
Short Hair ◽  
Current Clamp ◽  
Other Hand ◽  
Inwardly Rectifying ◽  
A Current

1. With the use of whole-cell mode of the patch-clamp method, we examined the electrical responses of hair cells enzymatically isolated from the goldfish sacculus. 2. Hair cells from the rostral saccule had a short cell body and were ovoidal or eggplantlike in shape, whereas hair cells from the caudal saccule had a variable shape. Many had a longer cell body and were cylindrical or gourd-like in shape, but some short hair cells were also present in the caudal saccule. 3. The short hair cells had a resting potential of about -75 mV. In current-clamp experiments, these hair cells elicited damped oscillatory-potential changes of a relatively small amplitude in response to a depolarizing current. A current in the opposite direction produced a slow hyperpolarization, much larger in amplitude. 4. Resonant frequency of the short, or the oscillatory, type of hair cells ranged from 40 to 200 Hz or higher. However, resonance was generally of a poor quality as compared with that noted for hair cells in the turtle cochlea or frog sacculus. 5. The long hair cells had a resting potential of -90 to -100 mV. In current-clamp experiments, these hair cells elicited an all-or-none spike approximately 50 mV in amplitude in response to a depolarizing current. The spike was usually followed by a plateau, which was maintained for the duration of the depolarizing pulse. In some hair cells, damped slow oscillatory waves were evoked at a rate of 5-15 Hz. On the other hand, a hyperpolarizing current produced potential changes much smaller in amplitude. 6. Voltage-clamp experiments showed that Ca2+-activated K+ channel and A-current, especially its high-threshold subclass, were involved in the generation of outward rectification in the oscillatory-type hair cells. On the other hand, Na+, in addition to Ca2+, was involved in the generation of spike in the spike-type hair cells. Spike potentials were elicited even in the presence of tetrodotoxin (TTX), but the rate of rise was slower as compared with the intact spikes. 7. The spike-type hair cells had an inwardly rectifying K+ channel similar to that noted in the tunicate egg and chick vestibular hair cell. However, the oscillatory-type hair cells had an inwardly rectifying channel similar to the hyperpolarization-activated current, Ih, of the rod inner segment, or sinoatrial nodal cell, or lacked the inwardly rectifying channel. Differences in the resting membrane potential between the oscillatory- and spike-type hair cells are probably related to differences in the inwardly rectifying channels. 8. Effects of sound stimulation were simulated by injecting a half-wave rectified sinusoidal current of various frequencies.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals THE CULTIVATION OF TRICHOMONAS OF THE HUMAN MOUTH (TETRATRICHOMONAS HOMINIS)

1917 ◽  
Vol 25 (2) ◽  
pp. 341-347 ◽  
Author(s):  
Tokuzo Ohira ◽  
Hideyo Noguchi
Keyword(s):  
Cultural Studies ◽  
Cell Body ◽  
Trichomonas Vaginalis ◽  
The Body ◽  
The Other ◽  
Other Hand ◽  
Deep Groove ◽  
Different Types ◽  
The Difference

Trichomonades from the mouth were studied by Steinberg who proposed to group them into three distinct types; namely, Trichomonas elongata, Trichomonas caudata, and Trichomonas flagellata. Doflein (3) regards them as probably identical with Trichomonas hominis. Opinions differ as to whether or not Trichomonas vaginalis Donné and Trichomonas hominis Grassi are the same species. Lynch, for instance, believes that they are the same species, while von Prowazek (4), Bensen (5), and others (6, 7) insist that they are different types. Bensen's view seems to be well supported by the difference alleged to be found between the mode of encystment in the two trichomonades, were it not for the fact that our knowledge about the so called cyst of trichomonades is still obscure. According to Alexeieff (8) many of the so called cysts were evidently blastomyces contained in the cell body of the trichomonas. An autogamy alleged to take place in cysts as described by Bohne and von Prowazek (9) has not been confirmed by Dobell (10). And Wenyon (11) contends that it has never been found possible to produce any development of these cysts outside the body on the warm stage as can be done with the cysts of Entamœba coli. Therefore, it is still premature to take the process of encystment into consideration as far as the classification of trichomonas is concerned. On the other hand, Rodenwaldt (12) seems to think that there are many species of trichomonas in the human intestines, and Wenyon has described a new trichomonas from the human intestines (Macrostoma mesnili Wenyon). Further cultural studies in the morphology and biology of these organisms must be carried out in order to solve these problems. In the light of modern investigations there are five subgenera to be included under the genus Trichomonas Donné. They are as follows: (1) Protrichomonas Alexeieff, with three anterior flagella, without an undulating membrane. (2) Trichomastix Biitschli) with three anterior flagella and a trailing flagellum (Schleppgeissel) without an undulating membrane. (3) Trichomonas Donné, with three anterior flagella and an undulating membrane. (4) Macrostoma Alexeieff, Amend, Wenyon (11), with three anterior flagella and an undulating membrane wedged in a deep groove (peristome). (5) Tetratrichomonas Parisi (13), with four anterior flagella and an undulating membrane. As far as our culture trichomonas from the human mouth is concerned, it has been shown that it is not strictly a trichomonas and that it should be classed under the subgenus Tetratrichomonas.

scholarly journals On the vapour-pressure and osmotic pressure of a volatile solute

1908 ◽  
Vol 81 (548) ◽  
pp. 336-336 ◽  
Keyword(s):  
Liquid Phase ◽  
Hydrostatic Pressure ◽  
Osmotic Pressure ◽  
Vapour Pressure ◽  
Specific Volume ◽  
Vapour Phase ◽  
The Other ◽  
Other Hand ◽  
Specific Volumes

It follows by a method given in a recent paper by the author that if the osmotic membrane be assumed to be impermeable to the solute, the formula for the change of vapour-pressure of a volatile solute with hydrostatic pressure, and also the formula for the osmotic pressure which is deduced from it, must be the same as the formula for a non-volatile solute, and should not contain any terms depending on the vapour-pressure of the solute, except in so far as it may affect the hydrostatic pressure of the solution. If, on the other hand, an osmotic membrane is regarded as a vapour-sieve permeable to the vapour of the solution but not to the liquid phase, the equation takes a different form, depending on the concentration of the constituents in the vapour-phase. If c 1 , c 2 , etc., be the concentrations of the constituents in grammes per gramme of the vapour, and if U 1 , U 2 , etc., be the specific volumes of the constituents in the solution, the change of total vapour-pressure dp of the solution for a change of hydrostatic pressure d P is given by the relation, ∑ c U d P = v dp , where v is the specific volume of the whole vapour-phase. If only on constituent is volatile, this relation reduces to the form U d P = v dp for that constituent.

scholarly journals MICROTUBULES IN THE FORMATION AND DEVELOPMENT OF THE PRIMARY MESENCHYME IN ARBACIA PUNCTULATA

1969 ◽  
Vol 41 (1) ◽  
pp. 227-250 ◽  
Author(s):  
Lewis G. Tilney ◽  
John R. Gibbins
Keyword(s):  
Hydrostatic Pressure ◽  
Sea Urchin ◽  
Cell Shape ◽  
Preceding Paper ◽  
Careful Analysis ◽  
The Other ◽  
Arbacia Punctulata ◽  
Cell Form ◽  
Cytoplasmic Microtubules ◽  
Made In

To experimentally test the suggestion made in the preceding paper that the microtubules are involved in cell shape development during the formation and differentiation of the primary mesenchyme, we applied to the embryos two types of agents which affect cytoplasmic microtubules: (a) colchicine and hydrostatic pressure, which cause the microtubules to disassemble, and (b) D2O, which tends to stabilize them. When the first type of agent is applied to sea urchin gastrulae, the development of the primary mesenchyme ceases, the microtubules disappear, and the cells tend to spherulate. With D2O development also ceases, but the tubules appear "frozen," and the cell asymmetries persist unaltered. These agents appear to block development by primarily interfering with the sequential disassembly and/or reassembly of microtubules into new patterns. The microtubules, therefore, appear to be influential in the development of cell form. On the other hand through a careful analysis of the action of these agents and others on both intra- and extracellular factors, we concluded that the microtubules do rather little for the maintenance of cell shape in differentiated tissues.

Structural Differences of Tyloses in Fraxinus Mandshurica Var. Japonica and Kalopanax Pictus

IAWA Journal ◽  
1991 ◽  
Vol 12 (3) ◽  
pp. 241-249
Author(s):  
Yuzou Sano ◽  
Kazumi Fukazawa
Keyword(s):  
Cell Wall ◽  
Fine Structure ◽  
The Other ◽  
Fraxinus Mandshurica ◽  
Kalopanax Pictus ◽  
Other Hand ◽  
Parallel Arrangement ◽  
Structural Differences

This study reports on the occurrence and structure of tyloses in Fraxinus mandshurica Rupr. var. japonica Maxim. and Kalopanax pictus Nakai. Tyloses occurred in the outer sapwood of both species, but they showed great structural differences. Tyloses of F. mandshurica var. japonica were unique in their morphology and fine structure: thinwalled, highly lignified, multi-Iamellate, lacking parallel arrangement of microfibrils and intercellular layers; they are destroyed simultaneously with the transition from sapwood to heartwood. On the other hand, in K. pictus the cell wall organisation of tyloses was similar to those of anormal cell wall; both primary and secondary walllayers, and intercellular layers were found, and the tyloses tightly occluded vessels in both the sapwood and heartwood.

scholarly journals Fine structure of kinetin-treated protonema and kinetin-induced gametophore buds in Funaria hygrometrica

2015 ◽  
Vol 40 (4) ◽  
pp. 549-555 ◽  
Author(s):  
F. Młodzianowski ◽  
A. Szweykowska
Keyword(s):  
Fine Structure ◽  
Metabolic Activity ◽  
The Other ◽  
Funaria Hygrometrica ◽  
Other Hand ◽  
Bud Induction ◽  
Development And Differentiation ◽  
High Metabolic Activity

Besides occasional hypertrophy of grana and disintegration of stroma thylakoids occurring in some chloroplasts, no significant changes were found in ultrastructure of typical protonema cells treated for six days with kinetin. On the other hand, the fine structure of cells in kinetin--induced gametophore buds differed much from that of the protonema cells and showed characteristics of cells of with high metabolic activity and high division rates. The results indicate that cytokinins enhance development and differentiation in the protonema by activating only some of its cells, whereas the others remain unchanged or show symptoms of destruction and ageing. This is supported by the fact that in the presence of chloramphenicol, which prevents bud induction, kinetin acts synergistically with the inhibitor in producing degeneration and destruction of chloroplasts.

IR Studies on the Interaction between Thermal and Radiation Defects in Silicon

2007 ◽  
Vol 131-133 ◽  
pp. 351-356 ◽  
Author(s):  
Charalamos A. Londos ◽  
G.D. Antonaras ◽  
M.S. Potsidi ◽  
Efstratia N. Sgourou ◽  
I.V. Antonova ◽  
...  
Keyword(s):  
Hydrostatic Pressure ◽  
Ir Spectroscopy ◽  
Oxygen Vacancy ◽  
Fast Neutron ◽  
High Hydrostatic Pressure ◽  
The Other ◽  
Radiation Defects ◽  
Vacancy Defects ◽  
Ir Studies ◽  
Other Hand

Fast neutron irradiations on pre-treated Cz-grown silicon were carried out. The pretreatments involved thermal anneals at 450 oC and 650 oC under high hydrostatic pressure. We mainly examined, by means of IR spectroscopy, the effect of pre-treatments on the production of the oxygen-vacancy (VO) pair. The amplitude of the VO band was found independent on the 450 oC treatment although the amplitudes of the TDs bands were reduced. On the other hand, the amplitude of the VO band was found lower in the samples treated at 650 oC, indicating an influence on the production of the oxygen-vacancy defects. The results are discussed and explanations are suggested concerning possible interactions between thermal and radiation defects.

A study of cometary eruptions through OH radio-lines

1999 ◽  
Vol 173 ◽  
pp. 249-254
Author(s):  
A.M. Silva ◽  
R.D. Miró
Keyword(s):  
Short Duration ◽  
Growth Curves ◽  
The Other ◽  
Initial Mass ◽  
Radio Lines ◽  
Other Hand ◽  
Sudden Rise

AbstractWe have developed a model for theH2OandOHevolution in a comet outburst, assuming that together with the gas, a distribution of icy grains is ejected. With an initial mass of icy grains of 108kg released, theH2OandOHproductions are increased up to a factor two, and the growth curves change drastically in the first two days. The model is applied to eruptions detected in theOHradio monitorings and fits well with the slow variations in the flux. On the other hand, several events of short duration appear, consisting of a sudden rise ofOHflux, followed by a sudden decay on the second day. These apparent short bursts are frequently found as precursors of a more durable eruption. We suggest that both of them are part of a unique eruption, and that the sudden decay is due to collisions that de-excite theOHmaser, when it reaches the Cometopause region located at 1.35 × 105kmfrom the nucleus.

Ultrastructure and Staining of Developing Elastic Tissue

1971 ◽  
Vol 29 ◽  
pp. 244-245
Author(s):  
E. N. Albert
Keyword(s):  
Fine Structure ◽  
Phosphotungstic Acid ◽  
Staining Method ◽  
Rat Aorta ◽  
Uranyl Acetate ◽  
The Other ◽  
Elastic Fibers ◽  
Elastic Tissue ◽  
Lead Citrate ◽  
New Born

Silver tetraphenylporphine sulfonate (Ag-TPPS) was synthesized in this laboratory and used as an electron dense stain for elastic tissue (Fig 1). The procedures for the synthesis of tetraphenylporphine sulfonate and the staining method for mature elastic tissue have been described previously.The fine structure of developing elastic tissue was observed in fetal and new born rat aorta using tetraphenylporphine sulfonate, phosphotungstic acid, uranyl acetate and lead citrate. The newly forming elastica consisted of two morphologically distinct components. These were a central amorphous and a peripheral fibrous. The ratio of the central amorphous and the peripheral fibrillar portion changed in favor of the former with increasing age.It was also observed that the staining properties of the two components were entirely different. The peripheral fibrous component stained with uranyl acetate and/or lead citrate while the central amorphous portion demonstrated no affinity for these stains. On the other hand, the central amorphous portion of developing elastic fibers stained vigorously with silver tetraphenylporphine sulfonate, while the fibrillar part did not (compare figs 2, 3, 4). Based upon the above observations it is proposed that developing elastica consists of two components that are morphologically and chemically different.

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