scholarly journals SOME PROPERTIES OF PROTOPLASMIC GELS

1946 ◽  
Vol 29 (3) ◽  
pp. 181-192 ◽  
Author(s):  
W. J. V. Osterhout
Keyword(s):  
Living Cell ◽  
Lead Acetate ◽  
Lead Nitrate ◽  
Living Cells ◽  
Organic Substances ◽  
Animal Cells ◽  
Natural Conditions ◽  
Know How ◽  
Partial Contraction ◽  
Straight Rod

The chloroplast of Spirogyra is a long, spirally coiled ribbon which may contract to form a short, nearly straight rod. This happens under natural conditions and it can also be produced by a variety of inorganic salts and by some organic substances. It also occurs when the chloroplast is freed by centrifugal force from the clear peripheral protoplasm which is in contact with the cellulose wall. It would therefore seem that the chloroplast may be passively stretched by the action of the clear protoplasm and hence it contracts as soon as it is set free. This contraction happens in dead as well as in living cells. It would be of much interest to know how the protoplasm brings about the coiling of the chloroplast and how the chloroplast is set free by various reagents. Presumably they must penetrate the living protoplasm to produce the effects described. In one species partial contraction without detachment from the peripheral protoplasm can be brought about by lead acetate. This is reversible. Lead nitrate does not produce this result. The attack upon the problem is greatly facilitated by the study of dead cells. Thereby we reduce the number of variables but the chloroplast continues to react to certain chemical and physical agents in much the same manner as in the living cell and the solution surrounding it can be controlled as is not possible in the living cell. We must await further investigation to learn what plant and animal cells contain gels under tension and what functions they perform.

scholarly journals WATER RELATIONS IN THE CELL

1945 ◽  
Vol 29 (2) ◽  
pp. 73-78 ◽  
Author(s):  
W. J. V. Osterhout
Keyword(s):  
Water Relations ◽  
Ferric Chloride ◽  
Lead Acetate ◽  
Lead Nitrate ◽  
Inorganic Salts ◽  
Natural Conditions ◽  
Ellipsoid Bodies ◽  
Straight Rod

Chloroplasts may contract under natural conditions and give up water to the rest of the cell, thus indicating changes in metabolism or constitution. Such contractions may be produced experimentally. In Nitella the chloroplasts are ellipsoid bodies which, under natural conditions, may contract to spheres with a loss of volume. This may be brought about by lead acetate, ferric chloride, and digitonin: the contraction may occur while the cell is alive. The contraction in lead acetate is reversible (in lead nitrate little or no contraction occurs). In Spirogyra the chloroplast is a long, spirally coiled ribbon which may contract under natural conditions to a short nearly straight rod with a loss of volume. This can be brought about by inorganic salts and in other ways while the cell is still alive.

scholarly journals Nanoarchitectonics on living cells

RSC Advances ◽  
2021 ◽  
Vol 11 (31) ◽  
pp. 18898-18914
Author(s):  
Katsuhiko Ariga ◽  
Rawil Fakhrullin
Keyword(s):  
Living Cell ◽  
Living Cells ◽  
Material Surfaces ◽  
As If

We can introduce functional structures with various components on a living cell as if architectures were constructed on material surfaces.

Graphene-Semiconductor Tubular Needles for Operations of Living Cells

2010 ◽  
Vol 5 (1) ◽  
pp. 90-96
Author(s):  
Aleksandr V. Kopylov ◽  
Viktor Ya. Prinz
Keyword(s):  
High Precision ◽  
Biological Material ◽  
Living Cell ◽  
Cylindrical Shells ◽  
Living Cells ◽  
The Novel ◽  
Graphene Structures

The possibility of application of the novel class of tubular needles for piercing cells and injecting biological material inside the cell is considered. Stability calculations of tubular (multiwall) needles were made. Calculations were made for the needles with walls formed from hybrid graphene-semiconductor or graphene structures and spires shaped as trapeziform open cylindrical shells. The possibility of mass fabrication of such needles and chips for AFM significantly broadens the range of available operations on the surface and inside the living cell and opens prospects of effective high-precision manipulations with individual cells.

Computational Foundations of the Anticipatory Artificial Autopoietic Cellular Automata

2021 ◽  
pp. 289-307
Author(s):  
Daniel M. Dubois ◽  
Stig C. Holmberg
Keyword(s):  
Artificial Intelligence ◽  
Cellular Automata ◽  
Living Cell ◽  
Artificial Life ◽  
Initial Conditions ◽  
Living Cells ◽  
Asymmetric Membrane

A survey of the Varela automata of autopoiesis is presented. The computation of the Varela program, with initial conditions given by a living cell, is not able to self-maintain the membrane of the living cell. In this chapter, the concept of anticipatory artificial autopoiesis (AAA) is introduced. In this chapter, the authors present a new algorithm of the anticipatory artificial autopoiesis, which extend the Varela automata. The main enhancement consists in defining an asymmetric membrane of the artificial lining cell. The simulations show the anticipatory generation of artificial living cells starting with any initial conditions. The new concept of anticipatory artificial autopoiesis is related to artificial life (Alife) and artificial intelligence (AI). This is a breakthrough in the computational foundation of autopoiesis.

scholarly journals Nanorheology of living cells measured by AFM-based force–distance curves

Nanoscale ◽  
2020 ◽  
Vol 12 (16) ◽  
pp. 9133-9143 ◽  
Author(s):  
Pablo D. Garcia ◽  
Carlos R. Guerrero ◽  
Ricardo Garcia
Keyword(s):  
Living Cell ◽  
Viscoelastic Properties ◽  
Living Cells

Method to measure the viscoelastic properties of a living cell by AFM-based force–distance curves.

scholarly journals THE SELECTIVE ABSORPTION OF POTASSIUM BY ANIMAL CELLS

1921 ◽  
Vol 4 (2) ◽  
pp. 141-148 ◽  
Author(s):  
Philip H. Mitchell ◽  
J. Walter Wilson ◽  
Ralph E. Stanton
Keyword(s):  
Electronic Structure ◽  
Cesium Chloride ◽  
Ringer Solution ◽  
Living Cells ◽  
Selective Absorption ◽  
Physiological Effects ◽  
Equivalent Amount ◽  
Animal Cells ◽  
Relationship Of ◽  
Resting Muscle

1. Frog muscles perfused with Ringer solution in which potassium chloride has been replaced by an equivalent amount of rubidium or cesium chloride take up rubidium or cesium and incorporate them into the tissue substance in such form as to be retained during a subsequent perfusion with potassium-free Ringer solution, provided the muscles contract during the first perfusion. Retention of rubidium or cesium by a resting muscle does not occur. 2. Rats on synthetic diets, adequate in all respects except that potassium was replaced by an equivalent amount of rubidium or cesium, died after a period varying from 10 to 17 days with characteristic symptoms including tetanic spasms. Muscle, heart, liver, kidney, spleen, and lung tissues were then found to contain significant amounts of rubidium or cesium. The concentration of these metals in the muscle amounted, in some cases, as shown by a spectroscopic estimation, to about half the concentration of potassium normally found in mammallian muscle. 3. The results are regarded as tending to confirm the theory that the peculiarities in the physiological effects of potassium, including the facility with which it is "selected" by living cells in preference to sodium, are related to the electronic structure of the potassium ion as compared with that of similar ions. The possible relationship of the comparative migration velocity, a function of the electronic structure, to physiological effects is suggested.

scholarly journals Microtubule dynamics and chromosome motion visualized in living anaphase cells.

1988 ◽  
Vol 106 (4) ◽  
pp. 1185-1192 ◽  
Author(s):  
G J Gorbsky ◽  
P J Sammak ◽  
G G Borisy
Keyword(s):  
Chromosome Segregation ◽  
Digital Imaging ◽  
Living Cells ◽  
Microtubule Dynamics ◽  
Chromosome Movement ◽  
Animal Cells ◽  
Digital Imaging Microscopy ◽  
Opposite Pole ◽  
Anaphase B ◽  
Chromosome Motion

Chromosome segregation in most animal cells is brought about through two events: the movement of the chromosomes to the poles (anaphase A) and the movement of the poles away from each other (anaphase B). Essential to an understanding of the mechanism of mitosis is information on the relative movements of components of the spindle and identification of sites of subunit loss from shortening microtubules. Through use of tubulin derivatized with X-rhodamine, photobleaching, and digital imaging microscopy of living cells, we directly determined the relative movements of poles, chromosomes, and a marked domain on kinetochore fibers during anaphase. During chromosome movement and pole-pole separation, the marked domain did not move significantly with respect to the near pole. Therefore, the kinetochore microtubules were shortened by the loss of subunits at the kinetochore, although a small amount of subunit loss elsewhere was not excluded. In anaphase A, chromosomes moved on kinetochore microtubules that remained stationary with respect to the near pole. In anaphase B, the kinetochore fiber microtubules accompanied the near pole in its movement away from the opposite pole. These results eliminate models of anaphase in which microtubules are thought to be traction elements that are drawn to and depolymerized at the pole. Our results are compatible with models of anaphase in which the kinetochore fiber microtubules remain anchored at the pole and in which microtubule dynamics are centered at the kinetochore.

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