scholarly journals ELECTRIC IMPEDANCE OF SUSPENSIONS OF ARBACIA EGGS

1928 ◽  
Vol 12 (1) ◽  
pp. 37-54 ◽  
Author(s):  
Kenneth S. Cole
Keyword(s):  
Cell Division ◽  
Surface Impedance ◽  
Sea Water ◽  
Specific Resistance ◽  
Electric Impedance ◽  
Membrane Formation ◽  
Specific Change ◽  
Polarization Capacity

Apparatus has been designed and constructed for the measurement of the electric impedance of suspensions of Arbacia eggs in sea water to alternating currents of frequencies from one thousand to fifteen million cycles per second. This apparatus is simple, rugged, compact, accurate, and rapid. The data lead to the conclusions that the specific resistance of the interior of the egg is about 90 ohm cm. or 3.6 times that of sea water, and that the impedance of the surface of the egg is probably similar to that of a "polarization capacity". The characteristics of this surface impedance can best be determined by measurements of the capacity and resistance of suspensions of eggs. No specific change has been found in the interior resistance or the surface impedance which can be related either to membrane formation or to cell division.

scholarly journals ELECTRIC IMPEDANCE OF ASTERIAS EGGS

1936 ◽  
Vol 19 (4) ◽  
pp. 609-623 ◽  
Author(s):  
Kenneth S. Cole ◽  
Robert H. Cole
Keyword(s):  
Plasma Membrane ◽  
Sea Water ◽  
Specific Resistance ◽  
Surface Conductance ◽  
Electric Impedance ◽  
High Concentration ◽  
Low Frequencies ◽  
Definite Evidence ◽  
Asterias Forbesi ◽  
Current Resistance

The alternating current resistance and capacity of suspensions of unfertilized eggs of Asterias forbesi have been measured at frequencies from one thousand to sixteen million cycles per second. The plasma membrane of the egg has a static capacity of 1.10µf/cm.2 which is practically independent of frequency. The suspensions show a capacity dependent on frequency at low frequencies which may be attributable to surface conductance. The specific resistance of the cytoplasm is between 136 and 225 ohm cm. (4 to 7 times sea water), indicating a relatively high concentration of non-electrolytes. At frequencies above one million cycles there is definite evidence of another element of which the nucleus is presumably a part.

scholarly journals ELECTRIC IMPEDANCE OF SINGLE MARINE EGGS

1938 ◽  
Vol 21 (5) ◽  
pp. 591-599 ◽  
Author(s):  
Kenneth S. Cole ◽  
Howard J. Curtis
Keyword(s):  
Preliminary Data ◽  
Sea Water ◽  
Membrane Conductance ◽  
Glass Tube ◽  
Alternating Current ◽  
Electric Impedance ◽  
Frequency Range ◽  
Impedance Measurements ◽  
Membrane Capacity ◽  
Thin Walled

Alternating current impedance measurements have been made on several single marine eggs over the frequency range from 1 to 2500 kilocycles per second. The eggs were placed in the center of a short capillary made by heating the end of a 2 mm. thin walled glass tube until it nearly closed, and electrodes were placed in the sea water on each side of the egg. When it is assumed that the membrane conductance is negligible, the membrane capacity and internal resistances of unfertilized and fertilized Arbacia eggs agree with the values obtained from suspensions. Preliminary data on centrifugally separated half Arbacia eggs, and whole Cumingia and Chaetopterus eggs are given.

scholarly journals THE ELECTRIC CAPACITY OF SUSPENSIONS WITH SPECIAL REFERENCE TO BLOOD

1925 ◽  
Vol 9 (2) ◽  
pp. 137-152 ◽  
Author(s):  
Hugo Fricke
Keyword(s):  
Specific Resistance ◽  
Suspended Particle ◽  
Specific Capacity ◽  
Major Axis ◽  
Electrolytic Cell ◽  
Substitution Method ◽  
Static Capacity ◽  
Electric Capacity ◽  
Polarization Capacity ◽  
Made In

1. The specific capacity of a suspension is that capacity which) combined in parallel with a certain resistance, electrically balances 1 cm. cube of the suspension. 2. The following formula holds for the specific capacity of a suspension of spheroids, each of which is composed of a well conducting interior surrounded by a thin membrane of a comparatively high resistance: See PDF for Equation C, specific capacity of suspension; Co, static capacity of one sq. cm. of membrane; r, r1 specific resistances respectively of suspension and of suspending liquid; 2 q major axis of spheroid, α constant tabulated in Table I. 3. The following formula holds practically for any suspension whatever the form of the suspended particle. See PDF for Equation C = C100 being the specific capacity of a suspension with a concentration of 100 per cent. Formulæ (1a) and (1b) hold only for the case, when the frequency is so low, that the impedance of the static capacity of the membrane around a single particle is high as compared with the resistance of the interior of the particle. The formulae hold also for a suspension of homogeneous particles, when polarization takes place at the surface of each particle, provided the polarization resistance is low as compared with the impedance of the polarization capacity. 4. A description is given of a method for measuring the capacity of a suspension at frequencies between 800 and 4½ million cycles. By means of a specially designed bridge, a substitution method is employed, by which in the last analysis the suspension is compared with the suspending liquid which is so diluted as to have the same specific resistance as the suspension, consecutive measurements being made in the same electrolytic cell. 5. Formula (1b) is verified by measurements of the capacity of suspensions of varying volume concentrations of the red corpuscles of a dog. 6. By means of the above measurements, the value of Co is calculated by equation (1a). 7. It is found that Co is independent of the frequency up to 4½ million cycles and that it is also independent of the suspending liquid. These results furnish considerable evidence of the validity of the theory, that Co represents the static capacity of a corpuscle membrane. 8. On this assumption and using a probable value for the dielectric constant of the membrane, the thickness of the membrane is calculated to be 3.3·10–7 cm.

Electrometric method to determine the surface impedance of an ice–sea water bilayer system

2016 ◽  
Vol 61 (2) ◽  
pp. 310-312 ◽  
Author(s):  
Yu. B. Bashkuev ◽  
I. B. Naguslaeva ◽  
V. B. Khaptanov ◽  
M. G. Dembelov
Keyword(s):  
Surface Impedance ◽  
Sea Water ◽  
Electrometric Method ◽  
Bilayer System

Cell movements, cell division and growth in the hydroid Clytia johnstoni

Development ◽  
1964 ◽  
Vol 12 (3) ◽  
pp. 517-538
Author(s):  
L. J. Hale
Keyword(s):  
Cell Division ◽  
Sea Water ◽  
Normal Growth ◽  
Cell Movements ◽  
Extensive Cell ◽  
Glass Plates ◽  
Living Material

Although there have been a great many studies on the morphogenesis of hydroids, the emphasis has been largely with regeneration and with grafting experiments, and mostly using the hydras, Cordylophora and Tubularia as material. Some of these investigations have made reference to cell movements and cell division, but none have considered both these fundamental morphogenetic processes and their interrelationships in a single hydroid. In this paper the occurrence of cell movements and cell division in normal growth and in the regeneration of Clytia johnstoni is considered. The investigation has revealed extensive cell movements, not only in the coenosarc but also passively by the hydroplasm. Cell division is almost exclusively confined to the ectoderm and rarely occurs in the endoderm. Material and Methods The animal was cultured in the laboratory on glass plates in running sea-water (Hale, 1957, 1960). All the observations (except those on cell division) were made on the living material kept at 18°C. (± 1).

scholarly journals FURTHER STUDIES ON CELL DIVISION WITHOUT MITOTIC APPARATUS IN SEA URCHIN EGGS

1965 ◽  
Vol 25 (1) ◽  
pp. 161-167 ◽  
Author(s):  
Y. Hiramoto
Keyword(s):  
Cell Division ◽  
Sea Urchin ◽  
Sea Water ◽  
Sucrose Solution ◽  
Mitotic Apparatus ◽  
Sea Urchin Eggs ◽  
Paraffin Oil

A large quantity of paraffin oil, sucrose solution, or sea water was injected into the eggs of the heart urchin Clypeaster japonicus shortly before the onset of the first cleavage. The injected oil became spherical, pushing the mitotic apparatus aside. The sucrose solution mixed with the protoplasm and caused disintegration of the mitotic apparatus, and the sea water formed a vacuole at the center of the cell. In all these cases, cleavage may take place almost normally in spite of the absence of the mitotic apparatus or its displacement within the cell. In some eggs, furrowing may take place when more than fifty per cent of the endoplasm has been replaced with sea water before onset of cleavage.

scholarly journals ELECTRIC IMPEDANCE OF FERTILIZED ARBACIA EGG SUSPENSIONS

1938 ◽  
Vol 21 (5) ◽  
pp. 583-590 ◽  
Author(s):  
Kenneth S. Cole ◽  
Joseph M. Spencer
Keyword(s):  
Plasma Membrane ◽  
High Resistance ◽  
Sea Water ◽  
High Capacity ◽  
Low Frequency ◽  
Alternating Current ◽  
Electric Impedance ◽  
Perivitelline Space ◽  
Membrane Capacity ◽  
Fertilization Membrane

From the low frequency alternating current impedance and the volume concentrations of suspensions of Arbacia eggs, it is shown that the high resistance membrane is either at or very near the plasma membrane for both unfertilized and fertilized eggs, and that the specific resistances of the perivitelline space and fertilization membrane are not greatly different from that of sea water. The effect of the capacity element which appears after fertilization at intermediate frequencies is considerably less than in the earlier experiments on Arbacia and Hipponoë eggs. These findings indicate that the fertilization membrane does not have the high capacity previously attributed to it and that the increase in membrane capacity takes place at or near the plasma membrane.

scholarly journals ELECTRIC IMPEDANCE OF HIPPONOË EGGS

1935 ◽  
Vol 18 (6) ◽  
pp. 877-887 ◽  
Author(s):  
Kenneth S. Cole
Keyword(s):  
Volume Concentration ◽  
Marked Effect ◽  
Sea Water ◽  
Unit Area ◽  
Specific Resistance ◽  
Internal Resistance ◽  
Simple Method ◽  
Low Frequencies ◽  
Static Capacity ◽  
Current Resistance

Alternating current resistance and capacity measurements have been made from 1.08 103 to 2.32 106 cycles per second on suspensions of unfertilized, fertilized, and swollen unfertilized eggs of the echinoderm Hipponoë esculenta. A simple method has been developed for measuring the volume concentration of eggs in a suspension. The membrane of the unfertilized egg is practically non-conducting at low frequencies and shows a static capacity of 0.87 µf/cm.2 except perhaps at the highest frequencies. The equivalent specific resistance of the egg interior is 11 times that of sea water. The membrane of the fertilized egg is practically non-conducting at low frequencies and shows a static capacity 2.5 times that of the unfertilized egg except at the higher frequencies where another reactive element produces a marked effect. The internal resistance is apparently higher than that of the unfertilized egg. The static capacity per unit area of the membrane decreases as a linear function of the surface area when the eggs are swollen in dilute sea water. In 40 per cent sea water, the capacity falls to about 75 per cent of normal.

Analysis of embryonic cell division patterns using laser scanning confocal microscopy

1989 ◽  
Vol 47 ◽  
pp. 140-141
Author(s):  
Robert G. Summers ◽  
Ping-chin Cheng
Keyword(s):  
Cell Division ◽  
Confocal Microscopy ◽  
Laser Scanning ◽  
Sea Water ◽  
Sea Urchins ◽  
Laser Scanning Confocal Microscopy ◽  
Cell Number ◽  
Embryonic Cell ◽  
Mitotic Apparatus ◽  
Scanning Confocal Microscopy

As embryogenesis in the sea urchin proceeds, cell number increases and overall synchrony of cell division decreases. Beyond 16 cells, it becomes increasingly more difficult to observe individual cells or populations of cells in whole-mounted embryos because of their thickness (up to 150 μm) and superimposition of nuclei. As a consequence, the patterns of cell division (eg. its timing and synchrony within subpopulations of cells, orientation of the mitotic apparatus relative to axes of embryonic symmetry etc.) in sea urchins and other developing systems remain unclear. Confocal microscopy affords the opportunity to analyze intact embryos and to gain an understanding of the role which cell division plays in morphogenesis of the embryo.Sea urchins (Strongylocentrotus purpuratus) were obtained from Northern California and maintained in artificial sea water. Gametes were obtained and cultures of embryos were prepared in the usual fashion and synchronous cultures of embryos were reared at 15°C. Fixation and Feulgen staining were performed per Nislow and Morill.

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