The Physiology of Contractile Vacuoles

1960 ◽  
Vol 37 (1) ◽  
pp. 73-82
Author(s):  
J. A. KITCHING ◽  
J. E. PADFIELD ◽  
M. H. ROGERS
Keyword(s):  
Body Surface ◽  
Normal Activity ◽  
The Body ◽  
Contractile Vacuole ◽  
Diffusion Constants ◽  
Contractile Vacuoles

1. The suctorian Discophrya collini (Root) has been subjected to D2O-H2O mixtures containing up to 99.7% D2O. 2. In 25% D2O or over there is a rapid but temporary shrinkage of the body. This shrinkage is difficult to estimate owing to the wrinkling of the body surface, but amounts to at least 10% in the undiluted (99.7%)D2O. 3. During the period of temporary shrinkage the contractile vacuole ceases activity. Normal activity is resumed when the normal volume is regained. In concentrations of D2O too low to cause shrinkage there is a temporary fall in the rate of vacuolar output. 4. Return to H2O leads to a brief but often very considerable rise in vacuolar output. 5. It is concluded that D2O penetrates less rapidly than H2O. A difference of at least 10% in the diffusion constants in the membrane would be required to explain our results. We cannot exclude this as unreasonable from our data, although an explanation based on differences in the equilibrium properties of D2O and H2O might also be invoked.

scholarly journals The Physiology of Contractile Vacuoles

1934 ◽  
Vol 11 (4) ◽  
pp. 364-381
Author(s):  
J. A. KITCHING
Keyword(s):  
Fresh Water ◽  
Sea Water ◽  
Tap Water ◽  
Marine Species ◽  
The Body ◽  
Contractile Vacuole ◽  
Body Volume ◽  
Water Value ◽  
Contractile Vacuoles ◽  
Sustained Increase

1. The rate of output of fluid from the contractile vacuole of a fresh-water Peritrich Ciliate was decreased to a new steady value immediately the organism was placed in a mixture of tap water and sea water. The rate of output returned to its original value immediately the organism was replaced in tap water. The contractile vacuole was stopped when the organism was treated with a mixture containing more than 12 per cent, of sea water. 2. Transference of various species of marine Peritricha from 100 per cent, sea water to mixtures of sea water and tap water led to an immediate increase of the body volume to a new and generally steady value. Return of the organism to 100 per cent, sea water led to an immediate decrease of the body volume to its original value or less. 3. Marine Peritricha showed little change in rate of output when treated with concentrations of sea water between 100 and 75 per cent. In more dilute mixtures the rate of output was immediately increased, and then generally fell off slightly to a new steady value which was still considerably above the original (100 per cent. sea water) value. The maximum sustained increase was approximately x 80. Return of the organism to 100 per cent, sea water led to an immediate return of the rate of output to approximately its original value. 4. When individuals of some marine species were placed in very dilute concentrations of sea water, the pellicle was frequently raised up in blisters by the formation of drops of fluid underneath it, and the contractile vacuole stopped. 5. Evidence is brought forward to suggest that in the lower concentrations of sea water marine forms lost salts. 6. The contractile vacuole probably acts as an osmotic controller in fresh-water Protozoa. Its function in those marine Protozoa in which it occurs remains obscure.

scholarly journals The Physiology Of Contractile Vacuoles

1938 ◽  
Vol 15 (1) ◽  
pp. 143-151
Author(s):  
J. A. KITCHING
Keyword(s):  
Body Surface ◽  
Sucrose Solution ◽  
Tap Water ◽  
The Body ◽  
Partial Recovery ◽  
A Value ◽  
Contractile Vacuoles ◽  
Cyanide Solutions ◽  
Initial Check ◽  
Normal Difference

1. The rate of output of fluid from the contractile vacuoles of fresh-water peritrich ciliates was reduced in solutions of sulphide of concentration not less than M/1000. This effect was reversible. 2. Cyanide depressed the rate of vacuolar output in a concentration of M/100,000, but was more effective in higher concentrations (M/1000). In cyanide solutions there was (a) either a severe initial check or a temporary stoppage of the vacuole, and then later (b) a partial recovery of the rate of output to a value which was still much below the normal. During the initial check the body swelled. 3. Return of the organism from cyanide solution to tap water was followed by a sharp increase in the rate of vacuolar output to an abnormally high value. The body then shrank gradually to its normal size, and the rate of output also fell slowly to normal. 4. The swelling of the body which followed treatment of the organism with cyanide could be exactly counteracted by the addition of sucrose to the outside medium in a 0.05 M concentration. 5. It is concluded that the normal difference of osmotic pressure across the body surface is equivalent to that of a 0.05 M sucrose solution, and that this difference is maintained by the contractile vacuole. 6. The permeability of the body surface to water is estimated as 0.125-0.25 cubic micra per square micron per atmosphere per minute.

Electrical Recording from the Contractile Ciliate Zoothamnium Geniculatum Ayrton

1979 ◽  
Vol 83 (1) ◽  
pp. 159-167
Author(s):  
R. B. MORETON ◽  
W. B. AMOS
Keyword(s):  
Body Surface ◽  
Complex Form ◽  
Spherical Body ◽  
Mechanical Stimulus ◽  
The Body ◽  
Negative Potential ◽  
Contractile Vacuole ◽  
Ciliate Protozoan ◽  
Electrical Recording

1. The spherical body (200 μm in diameter) of this ciliate protozoan was easily immobilized on a suction pipette and penetrated with glass micro electrodes. 2. No recordings could be made from the contractile stalk, but in the body a negative potential of 30.3 ± 125 mV was observed. 3. Approximately 9 ms after the onset of a mechanical stimulus, a rapid depolarization was observed. This was apparently simultaneous throughout the body surface. The amplitude was 38.9 ± 13.7 mV. Recordings with aphotomultiplier showed that contraction of the stalk began 10 ms later. 4. A slower depolarization of complex form was observed during systole of the contractile vacuole.

scholarly journals The Physiology of Contractile Vacuoles

1939 ◽  
Vol 16 (1) ◽  
pp. 34-37
Author(s):  
J. A. KITCHING
Keyword(s):  
Fresh Water ◽  
Body Surface ◽  
Contractile Vacuole ◽  
Main Function ◽  
General Body ◽  
Marine Ciliates ◽  
Food Vacuoles ◽  
Contractile Vacuoles

1. In peritrich ciliates many food vacuoles without visible solid contents may be formed. The water in these vacuoles passes into the general cytoplasm. 2. In fresh-water Peritricha the rate of uptake of fluid in food vacuoles generally amounts to between 8 and 20% of the rate of output of fluid by the contractile vacuole. The greater part of the water evacuated is presumed to enter the animal by osmosis through the general body surface. 3. In marine Peritricha the rate of uptake of fluid by food vacuoles approximately balances the rate of output by the contractile vacuole. The elimination of the water taken in by food vacuoles is believed to be the main function of the contractile vacuole in marine ciliates.

scholarly journals The Physiology Of Contractile Vacuoles

1936 ◽  
Vol 13 (1) ◽  
pp. 11-27
Author(s):  
J. A. KITCHING
Keyword(s):  
Cell Membrane ◽  
Body Surface ◽  
Salt Concentration ◽  
Sea Water ◽  
Cane Sugar ◽  
The Body ◽  
Contractile Vacuole ◽  
Body Volume ◽  
Oxidative Process ◽  
Low Concentrations

1. There was no change in the body volume of marine Peritricha subjected to reductions in the salt concentration of the medium, so long as the osmotic pressure of the medium was kept constant by the addition of urea, glycerol, or cane-sugar. In mixtures of isotonic non-electrolytes with sea water the rate of vacuolar output was decreased--more so in the case of urea than of glycerol. It is concluded that the cell membrane is relatively impermeable to urea, glycerol, and cane-sugar, and also to neutral salts. 2. Excretory substances could not be produced in sufficient quantity to attract water into the contractile vacuole by osmosis at the rate observed. The process of diastole therefore involves "secretion" of water by the vacuolar walls. 3. Cyanide and sulphide in very low concentrations rapidly caused a great reduction in the rate of output of the contractile vacuole of marine Peritricha. In the case of cyanide this effect was rapidly reversible. Alcohols and urethane only decreased the rate of vacuolar output when present in much higher concentrations. It is suggested that possibly vacuolar activity depends directly on an oxidative process. 4. When marine Peritricha were transferred from dilute sea water to dilute sea water of the same concentration+cyanide M/200 or M/500 (the pH being carefully controlled), the contractile vacuole was completely or almost completely stopped, and the body increased in volume. When the organism was transferred back to dilute sea water of the same concentration without cyanide, the contractile vacuole became active again and the body decreased in volume until a new steady value was attained which was rather below the value in dilute sea water before cyanide treatment. 5. The increase in body volume consequent on treatment with cyanide was greater the more dilute was the sea water. For sea water of concentrations of 100-75 per cent, no swelling was detectable when the organism was treated with cyanide. 6. The rate of output of the contractile vacuole is sufficiently great to account for the decrease in body volume during recovery from cyanide. 7. The permeability of the body surface to water is estimated as 0.05-0.10 cubic micra per square micron per atmosphere per minute.

The Physiology of Contractile Vacuoles

1954 ◽  
Vol 31 (1) ◽  
pp. 68-75
Author(s):  
J. A. KITCHING
Keyword(s):  
The Body ◽  
Contractile Vacuole ◽  
Body Volume ◽  
Sudden Increase ◽  
Small Decrease ◽  
Partial Restoration ◽  
Contractile Vacuoles

1. A study has been made of the effects of sudden changes of temperature on the contractile vacuole of the suctorian Discophrya piriformis Guilcher. 2. A sudden increase of temperature from below 15° C. by 5° or more causes a temporary fall in the rate of output, followed by a rise to a new level higher than the original. During the depression in activity the body swells slightly. 3. The vacuolar frequency increases immediately but briefly when the temperature is raised, falls steeply when the depression sets in, and when secretion is re-established rises again to a level above the original. 4. A sudden fall in temperature causes an immediate decrease in vacuolar frequency, followed by a partial restoration. The rate of output falls rather more slowly and remains low. In several cases a small decrease in body volume was observed. 5. It is suggested that the contractile vacuole is really contractile. 6. The observations on vacuolar frequency described in this paper are interpreted in terms of an inherent vacuolar rhythm which is modified by temperature and which is partially linked with rate of secretion.

The Role of Computer Modeling in Electrocardiography

1990 ◽  
Vol 29 (04) ◽  
pp. 282-288 ◽  
Author(s):  
A. van Oosterom
Keyword(s):  
Electrical Activity ◽  
Computer Modeling ◽  
Body Surface ◽  
Electrical Current ◽  
The Body ◽  
Volume Conductor ◽  
Current Generator ◽  
Cardiac Electrical Activity ◽  
Source Models

AbstractThis paper introduces some levels at which the computer has been incorporated in the research into the basis of electrocardiography. The emphasis lies on the modeling of the heart as an electrical current generator and of the properties of the body as a volume conductor, both playing a major role in the shaping of the electrocardiographic waveforms recorded at the body surface. It is claimed that the Forward-Problem of electrocardiography is no longer a problem. Several source models of cardiac electrical activity are considered, one of which can be directly interpreted in terms of the underlying electrophysiology (the depolarization sequence of the ventricles). The importance of using tailored rather than textbook geometry in inverse procedures is stressed.

The use of Body Surface Index as a Better Clinical Health indicators Compare to Body Mass Index and Body Surface Area for Clinical Application

2018 ◽  
pp. 131-136
Author(s):  
Shirazu I. ◽  
Theophilus. A. Sackey ◽  
Elvis K. Tiburu ◽  
Mensah Y. B. ◽  
Forson A.
Keyword(s):  
Surface Area ◽  
Body Surface Area ◽  
Clinical Application ◽  
Body Surface ◽  
Body Height ◽  
Health Indicators ◽  
The Body ◽  
Body Parameters ◽  
The Relationship ◽  
Individual Body

The relationship between body height and body weight has been described by using various terms. Notable among them is the body mass index, body surface area, body shape index and body surface index. In clinical setting the first descriptive parameter is the BMI scale, which provides information about whether an individual body weight is proportionate to the body height. Since the development of BMI, two other body parameters have been developed in an attempt to determine the relationship between body height and weight. These are the body surface area (BSA) and body surface index (BSI). Generally, these body parameters are described as clinical health indicators that described how healthy an individual body response to the other internal organs. The aim of the study is to discuss the use of BSI as a better clinical health indicator for preclinical assessment of body-organ/tissue relationship. Hence organ health condition as against other body composition. In addition the study is `also to determine the best body parameter the best predict other parameters for clinical application. The model parameters are presented as; modeled height and weight; modelled BSI and BSA, BSI and BMI and modeled BSA and BMI. The models are presented as clinical application software for comfortable working process and designed as GUI and CAD for use in clinical application.

Mannose-binding C-type lectins as defense molecules on the body surface of the sea urchin Pseudocentrotus depressus

2021 ◽  
Vol 116 ◽  
pp. 103915
Author(s):  
Chihiro Iiyama ◽  
Fuyu Yoneda ◽  
Masaya Tsutsumi ◽  
Shigeyuki Tsutsui ◽  
Osamu Nakamura
Keyword(s):  
Sea Urchin ◽  
Body Surface ◽  
The Body ◽  
Mannose Binding ◽  
Defense Molecules
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