On the Vitelline Membrane of the Egg of Psammechinus Miliaris and of Teredo Norvegica

1932 ◽  
Vol 9 (1) ◽  
pp. 93-106
Author(s):  
A. D. HOBSON
Keyword(s):  
Sea Water ◽  
Tap Water ◽  
Elastic Solid ◽  
Vitelline Membrane ◽  
Hypertonic Solution ◽  
Perivitelline Space ◽  
Free Zone ◽  
Hypertonic Solutions ◽  
Psammechinus Miliaris ◽  
Entire Cell

I. Direct microscopic examination of the unfertilised eggs of Psammechinus miliaris and Teredo norvegica merely shows the existence of a thin, granule-free zone covering the surface. Whether this is continuous with the general cytoplasm or not cannot be made out with certainty by direct observation. 2. A cone of clear material can be drawn out from the surface of the unfertilised egg of both species by means of the microdissection needle. A definite membrane cannot be separated in this way. 3. Hypertonic solutions cause the egg of Psammechinus to shrink smoothly at first and later to become wrinkled. This is consistent with the view that the egg is surrounded by an elastic, solid layer which is normally in a state of tension. 4. Cytolysis of the egg of Psammechinus in tap water is not accompanied by bursting. The egg swells and is perfectly smooth and spherical when cytolysis is completed. This points to the existence of an elastic, solid surface layer. 5. Plasmolysis of the egg of Teredo is of the type here called "polyhedral."The irregular shape of the egg in the hypertonic solution is only temporary, as a clear membrane separates from the concave surfaces and the egg then becomes more or less spherical. 6. The protoplasm of the plasmolysed egg of Teredo behaves as a viscous fluid. 7. Cytolysis of the egg of Teredo in tap water is accompanied by bursting and dispersion of the entire cell contents. A crumpled membrane alone remains. 8. It is concluded that the unfertilised egg of both Teredo norvegica and Psammechinus miliaris is surrounded by an elastic vitelline membrane which is much a Vitelline Membrane of the Egg of P. miliaris and of T. norvegica 105 thicker in the former than in the latter. The vitelline membrane in both cases is tightly attached to the egg surface. 9 . In calcium-free sea water the fertilisation membrane is elevated normally in Psammechinus miliaris. It does not harden, however, and gradually sinks back on to the surface of the egg owing, apparently, to the loss by diffusion of the osmotically active substance in the perivitelline space. It can be elevated a second time by puncturing the surface of the egg and allowing some of the cell contents to penetrate into the perivitelline space. 10. It is suggested that one action of hypertonic solutions in inducing artificial parthenogenesis may be to cause a loosening of the attachment of the vitelline membrane to the egg surface.

The Effect of Fertilisation on the Permeability to Water and on Certain Other Properties of the Surface of the Egg of Psammechinus Miliaris

1932 ◽  
Vol 9 (1) ◽  
pp. 69-92
Author(s):  
A. D. HOBSON
Keyword(s):  
Sea Water ◽  
Tap Water ◽  
Surrounding Medium ◽  
Volume Changes ◽  
Single Experiment ◽  
Stage Of Development ◽  
Maximum Value ◽  
Hypertonic Solutions ◽  
Psammechinus Miliaris

1. A photographic method is described for recording volume changes in seaurchin eggs. 2. The behaviour of the eggs of Psammechinus miliaris, both before and at various intervals after fertilisation, in relation to osmotic changes in the surrounding medium have been investigated. 3. The rate of entrance of water from hypotonic sea water into the egg increases immediately after fertilisation takes place, rises to a first maximum at about 3 min. after fertilisation. It then falls to a comparatively low value at about 5 min. after fertilisation. After this the rate increases steadily to a maximum value which is reached about 35 min. after fertilisation. It remains steady until just before cleavage when, in the single experiment continued until this stage of development, it decreased very markedly. 4. The action of hypertonic solutions on the egg has been examined. Several types of plasmolysis occur and are characteristic of different stages in the development of the egg after fertilisation. The type of plasmolysis is determined principally by the physical properties of the egg surface. The plasmolysis method is of little use in this material for the determination of relative permeability to dissolved substances at different stages of development. 5. The rate of cytolysis in tap water has been investigated and its relation to permeability of the egg surface to water is considered. There is a susceptible period followed by one of resistance during the first 5-10 min. after fertilisation. The rate of cytolysis is conditioned, not only by the rate of entrance of water but also by the degree to which the cell surface will withstand stretching. The latter may be a significant factor. 6. The rate of Zytolysis in extremely hypertonic solutions of sea water + NaCl has been examined. It increases to a maximum at about 5-10 min. after fertilisation. Thereafter it decreases. Cytolysis in the unfertilised egg and just after fertilisation is a sudden process. Later it becomes more and more gradual and progresses slowly from the surface to the interior of the egg. The relation between the rate of cytolysis and permeability is uncertain.

scholarly journals Osmoregulation in Salmon and Sea Trout Alevins

1982 ◽  
Vol 101 (1) ◽  
pp. 61-70
Author(s):  
C. TALBOT ◽  
F. B. EDDY ◽  
J. JOHNSTON
Keyword(s):  
Osmotic Stress ◽  
Salmo Trutta ◽  
Developmental Stages ◽  
Electrolyte Concentration ◽  
Sea Water ◽  
Vitelline Membrane ◽  
Turnover Rates ◽  
Progressive Change ◽  
Sea Trout ◽  
Species Survival

Changes in survival, body-water content, body electrolyte concentration and Na+ turnover rates were studied in alevins of Atlantic salmon (Salmosalar L.) and sea trout (Salmo trutta L.) at different developmental stages following exposure to various dilutions of sea water. In 100% sea water, salmon alevins at 9 days post-hatch survived approximately 6 h, and seatrout alevins 13 days post-hatch survived approximately 4 h. In both species, survival in hyperosmotic media decreased and rates of dehydration and Na+ turnover increased with age and development. The progressive change inresistance to osmotic stress is associated with a decrease in body surface area occupied by the relatively impermeable vitelline membrane and to the development of functional gills, leading to an increase in permeability to water and salt.

Cold and hyperosmolar fluids in canine trachea: vascular and smooth muscle tone and albumin flux

1989 ◽  
Vol 66 (3) ◽  
pp. 1309-1315 ◽  
Author(s):  
M. E. Deffebach ◽  
R. O. Salonen ◽  
S. E. Webber ◽  
J. G. Widdicombe
Keyword(s):  
Smooth Muscle ◽  
Muscle Tone ◽  
Control Period ◽  
Smooth Muscle Contraction ◽  
Hypertonic Solution ◽  
Tracheal Lumen ◽  
Smooth Muscle Tone ◽  
Hypertonic Glucose ◽  
Hypertonic Solutions ◽  
Cervical Trachea

We have studied the effects of liquids of various osmolalities and temperatures on the tracheal vasculature, smooth muscle tone, and transepithelial albumin flux. In 10 anesthetized dogs a 10- to 13-cm length of cervical trachea was cannulated to allow instillation of fluids into its lumen. The cranial tracheal arteries were perfused at constant flow, with monitoring of the perfusion pressures (Ptr) and the external tracheal diameter (Dtr). Control fluid was Krebs-Henseleit solution (KH) with NaCl added to result in a 325-mosM solution (isotonic). Hypertonic solutions were KH with NaCl (warm hypertonic) or glucose (hypertonic glucose) added to result in a 800-mosM solution. All solutions were at 38 degrees C, with isotonic and the hypertonic NaCl solutions also given at 18 degrees C (cold isotonic and cold hypertonic). Fluorescent labeled albumin was given intravenously, and the change in fluorescence in the fluid was measured during each 15-min period. Changing from warm isotonic to cold isotonic decreased Dtr and Ptr. Changing from warm isotonic to warm hypertonic or hypertonic glucose decreased Ptr with no change in Dtr. The cold hypertonic responses were not different from cold isotonic responses. Warm hypertonic solution increased albumin flux into the tracheal lumen over a 15-min period to three times that of the control period, persisting for 15 min after replacement with warm isotonic solution. Cooling induces a vasodilation and smooth muscle contraction of the trachea, whereas hypertonic solutions result in vasodilation and, if osmolality is increased with NaCl, an increase in albumin flux into the tracheal lumen.

scholarly journals On the Inhibition of Muscle Contraction Caused by Exposure to Hypertonic Solutions

1972 ◽  
Vol 59 (6) ◽  
pp. 689-700 ◽  
Author(s):  
M. Miyamoto ◽  
J. I. Hubbard
Keyword(s):  
Plasma Membrane ◽  
Muscle Contraction ◽  
Ringer Solution ◽  
Hypertonic Solution ◽  
Single Fibers ◽  
Hypertonic Solutions ◽  
Alternative Hypotheses ◽  
Original Report ◽  
A Site ◽  
Normal Ringer

The evidence supporting a site of inhibition of excitation contraction (E-C) coupling near the plasma membrane (the "glycerol effect," the K+-potentiating effect) for muscle in hypertonic solution was reinvestigated. It was found, using whole frog sartorii, that there was a rehydration of muscle soaked in glycerol Ringer after 30 min and a large swelling (to 140% after 1 hr soaking) upon return of the muscle to normal Ringer, suggesting that significant amounts of glycerol enter the fibers during this time. While contrary to the original report of the glycerol effect, this finding was consistent with other studies involving the use of single fibers. Also reexamined was the potentiating effect of K+ on the hypertonic inhibition of muscle contraction. It was found that muscles exposed to this KCl pretreatment swell so that they are less dehydrated in hypertonic solutions, thus accounting for the observed potentiation. After being treated instead with a K2-tartrate Ringer solution, muscles did not swell and, as determined with twitch recordings, did not display any potentiation in hypertonic solutions—even though the [K+] was higher than an osmotically equivalent KCl solution. The evidence was thus consistent with alternative hypotheses in which inhibition of contraction occurs at a later stage in E-C coupling or involves the contractile process itself.

Oogenesis and egg-shell formation in Aspiculuris tetraptera Schulz (Nematoda: Oxyuroidea)

Parasitology ◽  
1979 ◽  
Vol 78 (2) ◽  
pp. 131-143 ◽  
Author(s):  
D. A. Wharton
Keyword(s):  
Vitelline Membrane ◽  
Shell Formation ◽  
Perivitelline Space ◽  
Lipid Layer ◽  
Cytoplasmic Inclusions ◽  
Inner Surface ◽  
Egg Shell ◽  
Aspiculuris Tetraptera ◽  
Lipid Layers

SUMMARYThe ovary of Aspiculuris tetraptera has a prominent terminal cap cell. This is considered to be part of the ovarian epithelium. Oogonia detach from the short rachis and increase in size from 6 to 60 μm; accumulating hyaline granules, shell granules and glycogen. The hyaline granules persist in the egg cytoplasm after shell formation has been completed and are considered to be lipoprotein yolk. The shell granules contribute to the non-chitin fraction of the chitinous layer. A classification of the cytoplasmic inclusions of the nematode oocyte is proposed. Upon fertilization a vitelline membrane is formed which constitutes the vitelline layer of the egg-shell. The chitinous layer is secreted in the perivitelline space, between the vitelline layer and the egg oolemma. Upon completion of chitinous layer synthesis, the egg cytoplasm contracts away from its inner surface. The material of the lipid layer is secreted at the surface of the egg cytoplasm and adheres to the inner surface of the chitinous layer. During secretion of the chitinous and lipid layers by the egg cytoplasm, the uterine cells secrete the unit membrane-like external uterine layer and the crystalline internal uterine layer. A complex system of interconnecting spaces develops in the internal uterine layer. This system is open to the exterior via breaks in the external uterine layer. There is no direct involvement of the uterine cells in the formation of this structure.

An experimental study of the scattering of light by natural waters

1952 ◽  
Vol 140 (900) ◽  
pp. 321-338 ◽  
Keyword(s):  
Surface Water ◽  
Natural Waters ◽  
Cold Water ◽  
Sea Water ◽  
Tap Water ◽  
Wave Length ◽  
Average Pore ◽  
Forward Scatter ◽  
Back Scattering ◽  
Similar Sample

A blue-sensitive multiplier phototube was used to measure light scattered from a parallel beam in distilled, tap and sea water, the first named serving as a check upon errors from extraneous sources of light. Forward and back scatter are closely the same for distilled water, but with natural waters by far the greater part of the effect occurs through angles less than 25°. A minimum is found for a deviation of about 110°, back scattering increasing somewhat for greater angles. The relative importance of forward scatter increases with turbidity, and in sea water about three-quarters of the effect is due to matter removable by filtration through a collodion filter of average pore diameter 1 μ or by sedimentation; further passage through 0·6 and 0·2 μ filters produces little change. Scattering is greater in blue light. Plymouth tap water scatters more than surface coastal water and the latter more than surface water 20 miles out, station E 1. Surface water scatters more than deeper—the water column being remarkably homogeneous even when a well-marked thermocline had existed for weeks, but a small increase was detectable at the top of the cold water. E 1 surface water increased in scattering between August and January, and decreased till May. Deep water showed little change. Extinction due to scattering between 20 and 155° amounted to less than one-sixth of that found for a similar sample with a Pulfrich photometer, so probably much scattering occurs below 20°. This explains why Pulfrich extinctions are so much greater than vertical extinction coefficients found in the sea. The preponderance of forward scattering within the range 20 to 155° and the effects of filtration suggest that such scattering is due chiefly to refraction through transparent mineral particles, large compared with the wave-length of light. The refractive index of organic matter is too near that of water to produce refraction through angles as large as 20°. Such matter may, however, be responsible for some of the scattering through smaller angles which apparently accounts for most of the turbidity found with the Pulfrich photometer.

scholarly journals Efflux of Red Cell Water into Buffered Hypertonic Solutions

1960 ◽  
Vol 43 (4) ◽  
pp. 707-712 ◽  
Author(s):  
Edwin G. Olmstead
Keyword(s):  
Freezing Point ◽  
Maximum Amount ◽  
Red Cells ◽  
Rabbit Serum ◽  
Hypertonic Solution ◽  
Red Cell ◽  
Supernatant Fluid ◽  
Freezing Point Depression ◽  
Cell Water ◽  
Hypertonic Solutions

Buffered NaCl solutions hypertonic to rabbit serum were prepared and freezing point depressions of each determined after dilution with measured amounts of water. Freezing point depression of these dilutions was a linear function of the amount of water added. One ml. of rabbit red cells was added to each 4 ml. of the hypertonic solutions and after incubation at 38°C. for 30 minutes the mixture was centrifuged and a freezing point depression determined on the supernatant fluid. The amount of water added to the hypertonic solutions by the red cells was calcuated from this freezing point depression. For each decrease in the freezing point of -0.093°C. of the surrounding solution red cells gave up approximately 5 ml. of water per 100 ml. of red cells in the range of -0.560 to -0.930°C. Beyond -0.930°C. the amount of water given up by 100 ml. of red cells fits best a parabolic equation. The maximum of this equation occurred at a freezing point of the hypertonic solution of -2.001°C. at which time the maximum amount of water leaving the red cells would be 39.9 ml. per 100 ml. of red cells. The data suggest that only about 43 per cent of the red cell water is available for exchange into solutions of increasing tonicity.

scholarly journals The effect of hypertonic solutions on the rate of relaxation of contracture tension in Mytilus smooth muscle

1978 ◽  
Vol 74 (1) ◽  
pp. 197-210
Author(s):  
T. Tameyasu
Keyword(s):  
Mechanical Properties ◽  
Smooth Muscle ◽  
Retractor Muscle ◽  
Bathing Solution ◽  
Hypertonic Solution ◽  
Active Tension ◽  
Thin Filaments ◽  
Hypertonic Solutions ◽  
Wet Weight ◽  
Anterior Byssal Retractor Muscle

1. The effect of the bathing solution tonicity on the mechanical properties of the anterior byssal retractor muscle (ABRM) of Mytilus edulis was examined. 2. The rate of relaxation of contracture tension produced by acetylcholine (ACh) was greatly reduced when the bathing solution tonicity was increased by adding NaCl, KCl or LiCl after the removal of ACh, whereas a decreased tonicity increased the rate of relaxation. 3. The contracted ABRM in hypertonic solutions showed no active shortening after an isotonic release and barely redeveloped active tension after a quick release. 4. The resistance to stretch increased with increasing tonicity of the bathing solution. 5. The wet weight of the ABRM decreased much more markedly in sucrose-hypertonic solution than in Na-, K- or Li-hypertonic solutions, but the decrease in the rate of relaxation was less marked in the former, indicating that there may be little relation between the rate of relaxation and the degree of osmotic deformation of the ABRM fibres. 6. It is suggested that the elevated ionic strength in the myoplasm may be related to a reduction in the rate of detachment of the cross-linkages between the thick and thin filaments.

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