scholarly journals Electron Microscopy of the Centrifuged Sea Urchin Egg, with a Note on the Structure of the Ground Cytoplasm

1960 ◽  
Vol 7 (1) ◽  
pp. 135-142 ◽  
Author(s):  
Paul R. Gross ◽  
Delbert E. Philpott ◽  
Sylvan Nass
Keyword(s):  
Sea Urchin ◽  
Composite Structures ◽  
Annulate Lamellae ◽  
Cortical Granules ◽  
Clear Zone ◽  
Arbacia Punctulata ◽  
Large Numbers ◽  
Sea Urchin Egg ◽  
Size Number

Centrifuged, unfertilized eggs of the sea urchin, Arbacia punctulata, have been studied with the electron microscope. Subcellular particles were stratified by centrifuging living cells, known to be normally fertilizable, for five minutes at 3,000 g. The layered subcellular particles, including cortical granules, 16 mµ RNP particles, pigment, yolk, mitochondria, and oil droplets, possess characteristic ultrastructural features by which they may be identified in situ. The clear zone contains 16 mµ particles, most of them freely dispersed, scattered mitochondria, and a few composite structures made up of annulate lamellae in parallel layers or in association with dense, spherical aggregates of the RNP particles. Free 16 mµ particles are found, in addition, throughout the cell, in the interstices between the stratified larger particles. They show a tendency to form ramifying aggregates resulting from certain types of injury to the cell. A few vesicular structures, found mainly in the clear zone, have attached RNP particles, and appear to be related to the ER of tissue cells. Other vesicles, bounded by smooth membranes, are found throughout the cell. These are extremely variable in size, number, and distribution; their total number appears to depend upon conditions of fixation. It is suggested that limited formation of such structures is a normal property of the ground cytoplasm in this cell, but that fixed cells with very large numbers of smooth surfaced vesicles have produced the latter as a response to chemical injury. A model of the ground cytoplasm is proposed whose aim is to reconcile the rheological behavior of the living cell with the ultrastructural features observed.

scholarly journals pH regulates the polymerization of actin in the sea urchin egg cortex.

1979 ◽  
Vol 83 (1) ◽  
pp. 241-248 ◽  
Author(s):  
D A Begg ◽  
L I Rebhun
Keyword(s):  
Sea Urchin ◽  
Actin Filaments ◽  
Actin Polymerization ◽  
Filamentous Actin ◽  
Cortical Granules ◽  
Isolation Medium ◽  
Large Numbers ◽  
Sea Urchin Egg ◽  
Isolated Cortex ◽  
Egg Cortex

The state of actin in the isolated cortex of the unfertilized sea urchin egg can be controlled by experimentally manipulating the pH of the isolation medium. Cortices isolated at the pH of the unfertilized egg (6.5--6.7) do not contain filamentous actin, while those isolated at the pH of the fertilized egg (7.3--7.5) develop large numbers of microvilli which contain bundles of actin filaments. Cortices that are isolated at pH 6.5 and then transferred to isolation medium buffered at pH 7.5 also develop actin filaments. However, the filaments are not arranged in bundles and microvilli do not form. Although the cortical granules in cortices isolated at pH 6.5 discharge at a free Ca++ concentration of approximately 10 micrometer, actin polymerization is not induced by increasing the Ca++ concentration of the isolation medium. These results suggest that the increase in cytoplasmic pH which occurs following fertilization induces the polymerization of actin in the egg cortex.

scholarly journals A CYTOLOGICAL STUDY OF THE CENTRIFUGED WHOLE, HALF, AND QUARTER EGGS OF THE SEA URCHIN ARBACIA PUNCTULATA

1970 ◽  
Vol 47 (3) ◽  
pp. 711-733 ◽  
Author(s):  
Everett Anderson
Keyword(s):  
Lipid Droplets ◽  
Sea Water ◽  
Cytological Study ◽  
Germinal Vesicle ◽  
The Other ◽  
Annulate Lamellae ◽  
Cortical Granules ◽  
Clear Zone ◽  
Arbacia Punctulata ◽  
Peripheral Position

While the ooplasmic components of centrifuged eggs of Arbacia punctulata do not stratify in homogeneous layers, we have obtained the following strata beginning with the centripetal end: lipid droplets, pronucleus, clear zone, mitochondria, yolk, and pigment. Whereas mitochondria may be found mingled with yolk bodies, we have never observed lipid droplets nor pigment bodies among any of the other inclusions. The so-called clear zone contains a heterogeneous population of inclusions: annulate lamellae, heavy bodies, Golgi complexes, and rod-containing vacuoles. The peripheral cortical granules of immature (germinal vesicle stage) and of mature eggs are not dislodged from the cortical ooplasm with the centrifugal force utilized. When the eggs are treated with urethane, prior to centrifugation, the cortical granules of mature eggs abandon their peripheral position. Further centrifugation of the initially stratified eggs produces nucleated and nonnucleated halves and the centrifugation of the halves results in quarters. The cytology of the halves and quarters is discussed. The halves and quarters have been activated with either sperm or hypertonic sea water. With the exception of the nucleated halves, we were unable to obtain plutei larvae from the other fractions (red halves and quarters). We believe that the lack of development of the various fragments is a function of the balance of particular inclusions necessary for differentiation.

scholarly journals A CYTOLOGICAL STUDY OF ARTIFICIAL PARTHENOGENESIS IN THE SEA URCHIN ARBACIA PUNCTULATA

1970 ◽  
Vol 47 (1) ◽  
pp. 140-158 ◽  
Author(s):  
Martin I. Sachs ◽  
Everett Anderson
Keyword(s):  
Endoplasmic Reticulum ◽  
Sea Urchin ◽  
Nuclear Division ◽  
Annulate Lamellae ◽  
Cortical Granules ◽  
Smooth Variety ◽  
Mitotic Apparatus ◽  
Arbacia Punctulata ◽  
The Matrix ◽  
Cell Embryo

Eggs of the sea urchin Arbacia punctulata were artificially activated with hypertonic seawater. The artificially activated eggs undergo the cortical reaction which is not distinguished by a wavelike progression as in the case of inseminated eggs. The cortical granules are released at random loci at the surface of the egg and result in spaces separated by large cytoplasmic projections. Unreacted cortical granules and ribosomes are found within the matrix comprising the large cytoplasmic projections. No "fertilization cone" is formed. The subsequent release of additional cortical granules results in the formation of a continuous perivitelline space, 15 min following activation. 85 min postactivation, an organization of annulate lamellae, endoplasmic reticulum of the smooth variety, and microtubules around a centriole is observed prior to nuclear division. Before the breakdown of the nuclear envelope a streak stage is formed. The streak is composed of a central core of annulate lamellae and is encompassed by endoplasmic reticulum and vesicular components. Condensation of chromatin is followed by the establishment of the mitotic apparatus. Centrioles were not found in the mature egg; however, they are present after activation prior to the first nuclear division, in the four-cell embryo, multicellular embryo, and at blastula. Artificially activated eggs have been observed to develop to the pluteus stage in more than 50% of the eggs treated.

scholarly journals OOCYTE DIFFERENTIATION IN THE SEA URCHIN, ARBACIA PUNCTULATA, WITH PARTICULAR REFERENCE TO THE ORIGIN OF CORTICAL GRANULES AND THEIR PARTICIPATION IN THE CORTICAL REACTION

1968 ◽  
Vol 37 (2) ◽  
pp. 514-539 ◽  
Author(s):  
Everett Anderson
Keyword(s):  
Sea Urchin ◽  
Golgi Complex ◽  
Morphological Evidence ◽  
Cortical Granule ◽  
Perivitelline Space ◽  
Unit Membrane ◽  
Cortical Granules ◽  
Arbacia Punctulata ◽  
Cortical Reaction ◽  
Oocyte Differentiation

This paper presents morphological evidence on the origin of cortical granules in the oocytes of Arbacia punctulata and other echinoderms. During oocyte differentiation, those Golgi complexes associated with the production of cortical granules are composed of numerous saccules with companion vesicles. Each element of the Golgi complex contains a rather dense homogeneous substance. The vesicular component of the Golgi complex is thought to be derived from the saccular member by a pinching-off process. The pinched-off vesicles are viewed as containers of the precursor(s) of the cortical granules. In time, they coalesce and form a mature cortical granule whose content is bounded by a unit membrane. Thus, it is asserted that the Golgi complex is involved in both the synthesis and concentration of precursors utilized in the construction of the cortical granule. Immediately after the egg is activated by the sperm the primary envelope becomes detached from the oolemma, thereby forming what we have called the activation calyx (see Discussion). Subsequent to the elaboration of the activation calyx, the contents of cortical granules are released (cortical reaction) into the perivitelline space. The discharge of the constituents of a cortical granule is accomplished by the union of its encompassing unit membrane, in several places, with the oolemma.

scholarly journals Poisson-distributed active fusion complexes underlie the control of the rate and extent of exocytosis by calcium.

1996 ◽  
Vol 134 (2) ◽  
pp. 329-338 ◽  
Author(s):  
S S Vogel ◽  
P S Blank ◽  
J Zimmerberg
Keyword(s):  
Poisson Process ◽  
Sea Urchin ◽  
Physiological Responses ◽  
Cortical Granule ◽  
Cortical Granules ◽  
Granule Exocytosis ◽  
Calcium Dependence ◽  
Sea Urchin Egg ◽  
High Calcium ◽  
Cortical Granule Exocytosis

We have investigated the consequences of having multiple fusion complexes on exocytotic granules, and have identified a new principle for interpreting the calcium dependence of calcium-triggered exocytosis. Strikingly different physiological responses to calcium are expected when active fusion complexes are distributed between granules in a deterministic or probabilistic manner. We have modeled these differences, and compared them with the calcium dependence of sea urchin egg cortical granule exocytosis. From the calcium dependence of cortical granule exocytosis, and from the exposure time and concentration dependence of N-ethylmaleimide inhibition, we determined that cortical granules do have spare active fusion complexes that are randomly distributed as a Poisson process among the population of granules. At high calcium concentrations, docking sites have on average nine active fusion complexes.

Purification of cortical granules from unfertilized sea urchin egg homogenates by zonal centrifugation

1972 ◽  
Vol 29 (3) ◽  
pp. 307-320 ◽  
Author(s):  
H. Schuel ◽  
W.L. Wilson ◽  
R.S. Bressler ◽  
J.W. Kelly ◽  
J.R. Wilson
Keyword(s):  
Sea Urchin ◽  
Cortical Granules ◽  
Sea Urchin Egg

scholarly journals DIRECT ISOLATION OF THE HYALINE LAYER PROTEIN RELEASED FROM THE CORTICAL GRANULES OF THE SEA URCHIN EGG AT FERTILIZATION

1970 ◽  
Vol 45 (3) ◽  
pp. 615-622 ◽  
Author(s):  
R. E. Kane
Keyword(s):  
Protein Content ◽  
Sea Urchin ◽  
Insoluble Fraction ◽  
Glycerol Solution ◽  
Cortical Granules ◽  
Simple Method ◽  
Quantitative Measurements ◽  
Hawaiian Species ◽  
Sea Urchin Egg

Treatment of the eggs of the sea urchin with a 1 M solution of glycerol at fertilization allows the recovery from this solution of the protein released from the cortical granules, including that which would normally give rise to the hyaline layer. The calcium-gelable protein previously extracted from whole eggs and from isolated cortical material was found to be present in the glycerol solution, confirming its localization in the cortical granules and its role in the hyaline layer. Quantitative measurements on the eggs of two Hawaiian species, Colobocentrotus atratus and Pseudoboletia indiana, which have the widest variation in the gel protein content, demonstrated that a proportionate amount of this material was released at fertilization in these species, which correlates with the thickness of the hyaline layer in the two cases. In addition, the calcium-insoluble fraction of Sakai can be extracted from these eggs after removal of the hyaline protein by glycerol, showing that this is a different material. A simple method for the separation of the hyaline protein from the calcium-insoluble fraction in solution is provided.

scholarly journals A COMPARATIVE STUDY OF THE ISOLATION OF THE CORTEX AND THE ROLE OF THE CALCIUM-INSOLUBLE PROTEIN IN SEVERAL SPECIES OF SEA URCHIN EGG

1969 ◽  
Vol 41 (1) ◽  
pp. 133-144 ◽  
Author(s):  
R. E. Kane ◽  
R. E. Stephens
Keyword(s):  
Comparative Study ◽  
Sea Urchin ◽  
Protein Composition ◽  
Cortical Region ◽  
Cortical Granules ◽  
Divalent Ions ◽  
Sea Urchin Egg ◽  
Protein Gelation ◽  
Isolated Cortex

A comparative study was made of the isolation of the cortex in the eggs of several sea urchin species. Since the isolation method developed by Sakai depends on the presence of magnesium in the medium, the protein composition of the cortex was investigated to determine whether the protein component of the egg described by Kane and Hersh which is gelled by divalent ions, is present in these cortices. Isolation of the cortex was found to require the same divalent ions at the same concentrations as protein gelation, and in the eggs of some species much of the gel protein of the cell was found in the isolated cortical material. In the eggs of other species a smaller fraction of this protein was found in the isolated cortex, although it was more concentrated there than in the endoplasm, and in one species this protein appeared to be uniformly distributed throughout the cell. These results indicate that this protein is localized in the cortical region of the eggs of some species of sea urchin, possibly in the cortical granules, but also point up the fact that results from one species cannot be uncritically extrapolated to others.

scholarly journals THE MEMBRANE CAPACITANCE OF THE SEA URCHIN EGG

1957 ◽  
Vol 3 (1) ◽  
pp. 103-110 ◽  
Author(s):  
Lord Rothschild
Keyword(s):  
Plasma Membrane ◽  
Sea Urchin ◽  
Sea Water ◽  
Unit Area ◽  
Membrane Capacitance ◽  
Percentage Reduction ◽  
Cortical Granules ◽  
Sea Urchin Egg

1. The surface of the unfertilized sea urchin egg is folded and the folds are reversibly eliminated by exposing the egg to hypotonic sea water. If the plasma membrane is outside the layer of cortical granules, unfolding may explain why the membrane capacitance per unit area decreases (and does not increase) when a sea urchin egg is put into hypotonic sea water. 2. The degree of surface folding markedly increases after fertilization, which provides an explanation for the increase in membrane capacitance per unit area observed after fertilization. 3. The percentage reduction in membrane folding in fertilized eggs after immersion in hypotonic sea water is probably sufficient to explain the decrease in membrane capacitance per unit area observed in these conditions.

scholarly journals THE EFFECT OF PENICILLIN ON EGGS OF THE SEA URCHIN, ARBACIA PUNCTULATA

1945 ◽  
Vol 28 (5) ◽  
pp. 405-413 ◽  
Author(s):  
Richard J. Henry ◽  
Maryon D. Henry
Keyword(s):  
Oxygen Consumption ◽  
Cell Division ◽  
Sea Urchin ◽  
Inhibitory Action ◽  
Initial Concentration ◽  
Arbacia Punctulata ◽  
Sea Urchin Egg

1. Penicillin in the range of concentration from 250 U/ml. to approximately 2650 U/ml. inhibits the rate of cell division of the fertilized sea urchin egg from 0 to 100 per cent. 2. Penicillin in the same range of concentrations has no effect on the oxygen consumption of the unfertilized or the fertilized eggs. 3. Penicillin is bound by some component of the sea urchin egg in amounts sufficiently large to lower the initial concentration, this binding apparently not being related to the inhibitory action.

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