The influence of pyocyanine on the animalization of the sea-urchin egg induced by calcium free sea-water and sulphocyanate

PROTOPLASMA ◽  
1939 ◽  
Vol 33 (1) ◽  
pp. 628-629
Keyword(s):  
Sea Urchin ◽  
Sea Water ◽  
Sea Urchin Egg

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 Microdissection Experiments on Sea-Urchin Eggs at Cleavage

1953 ◽  
Vol 30 (4) ◽  
pp. 515-524
Author(s):  
J. M. MITCHISON
Keyword(s):  
Internal Pressure ◽  
Sea Urchin ◽  
Sea Water ◽  
Sea Urchins ◽  
The Other ◽  
Membrane Tension ◽  
Membrane Theory ◽  
Sea Urchin Egg ◽  
Pass Through ◽  
Irreparable Damage

1. Chambers (1938) described an experiment in which he cut open one blasto-mere of a cleaving sea-urchin egg at the dumb-bell stage in isotonic KCl. The other blastomere contracted like a ‘deflating balloon’, and this has been taken by other workers as evidence of a positive membrane tension in the cleaving egg. This experiment has been repeated with other sea urchins in various media. It is concluded that this effect only takes place in one species of sea urchin, in an abnormal medium, and after it has suffered irreparable damage. It is not, therefore, legitimate to suppose that there is normally a positive membrane tension in a cleaving egg. It is found that eggs will continue to cleave with one blastomere in an irregular shape which indicates that, on the contrary, there is no membrane tension and no internal pressure. These are the conditions demanded by the ‘expanding membrane’ theory of cleavage. 2. It is found that the furrow of a cleaving egg will pass through a needle placed in its path. This result argues against a simple contracting ring in the furrow region being responsible for cleavage. 3. Chambers (1938) found that an egg will continue to cleave when its asters have been destroyed by stirring. This result has been confirmed by a similar experiment on a different species of sea urchin. This is crucial evidence against an astral mechanism of cleavage. 4. The effects of compressing cleaving eggs have been studied. It is found that compressed eggs continue to cleave unless the degree of flattening is considerable; that cleavage is delayed before it is finally stopped; and that eggs in Ca-free sea water are more susceptible to compression than eggs in ordinary sea water. These results are consistent with the ‘expanding membrane’ theory.

scholarly journals The Inorganic Constituents of the Sea-Urchin Egg

1953 ◽  
Vol 30 (4) ◽  
pp. 534-544
Author(s):  
LORD ROTHSCHILD ◽  
H. BARNES
Keyword(s):  
Sea Urchin ◽  
Total Phosphorus ◽  
Phosphorus Content ◽  
Sea Water ◽  
Paracentrotus Lividus ◽  
Dry Weight ◽  
Chemical Methods ◽  
Sea Urchin Egg ◽  
Soluble Phosphorus ◽  
Inorganic Constituents

1. The principal inorganic constituents of the unfertilized egg of Paracentrotus lividus have been analysed by chemical methods. The results of the analyses, in millimoles per kg. of water in the eggs (dry weight of eggs, 24%; density, 1.09), were: The figures in brackets are the concentrations of the same substances in Roscoff sea water, chlorinity 19.37‰ in the same units. 2. The total phosphorus content of the eggs was about 2 mg./ml. eggs, somewhat over half of this being acid-soluble phosphorus.

Evidence that a secretory component of the sea urchin egg is routed to yolk platelets after fertilization

1989 ◽  
Vol 47 ◽  
pp. 838-839
Author(s):  
M. C. Valdizan ◽  
G. L. Decker
Keyword(s):  
Sea Urchin ◽  
Colloidal Gold ◽  
Sea Water ◽  
Strongylocentrotus Purpuratus ◽  
Secretory Component ◽  
Time Points ◽  
Sea Urchin Egg ◽  
Cortical Vesicles ◽  
The Individual ◽  
Lowicryl K4m

During fertilization the sea urchin egg undergoes a global wave of secretion (the cortical reaction) followed by a period of endocytotic activity involved in membrane retrieval. Using a monoclonal antibody (MAb 1223) that recognizes a 130-kDa glycoprotein found in both the egg and embryo of Strongylocentrotus purpuratus, we recently suggested that glycoproteins bearing the 1223 epitope are stored in the cortical vesicles of the egg, secreted during fertilization, and subsequently endocytosed and routed to yolk platelets, a possible site of degradation.In the current study, to determine whether fertilized eggs could internalize an antibody probe directed at the cell surface, we coupled MAb 1223 to colloidal gold and presented it to eggs that had been stripped of fertilization envelopes and hyaline layers. Gold-conjugated mouse IgG (preimmune), bovine serum albumin (BSA), and goat-antimouse IgG served as controls. Colloidal gold (8 and 15 nm) was prepared and conjugated to BSA or antibody as previously described. For localization of the 1223 antigen in unfertilized eggs MAb 1223-gold was diluted 1:20 in buffer and applied to sections of eggs embedded in Lowicryl K4M. To remove the envelopes and hyaline layers, 20-30 seconds after addition of sperm the eggs were suspended in ice-cold artificial sea water containing 25 mM EGTA and passed through a nylon screen (64 μm mesh). Subsequently, 1 ml aliquots of the denuded eggs [10% suspension (vol/vol)] were gravity settled, removed from the Ca2+-chelator and resuspended in complete sea water. After a second wash, 20 μl aliquots of the eggs were transferred to fresh 1.0 ml volumes of sea water equilibrated at 14°C in the presence of the individual gold probes. The final dilution of the gold probes in sea water was 1:100. After gentle mixing of the eggs and gold probes, at time points 5,15,30 and 60 minutes specimens were fixed and embedded in Spurr resin as previously described.

Sea-urchin Development in the Light of Enzymic and Mitochondrial Studies

Development ◽  
1953 ◽  
Vol 1 (3) ◽  
pp. 251-255
Author(s):  
Tryggve Gustafson
Keyword(s):  
Amino Acids ◽  
Sea Urchin ◽  
Opposite Effect ◽  
Sea Water ◽  
Lithium Ions ◽  
Chemical Agents ◽  
Sea Urchin Egg ◽  
Biochemical Studies ◽  
Iodosobenzoic Acid ◽  
Very High

The sea-urchin egg is characterized by a very high morphogenetic plasticity. Its trend in differentiation can in fact be controlled by means of various chemical agents. The development of the entoderm is thus favoured at the expense of that of the ectoderm by adding lithium ions to the sea-water (Herbst, 1892; Lindahl, 1936). Iodosobenzoic acid (Runnström & Kriszat, 1952) and thiocyanate (Herbst, 1892; Lindahl, 1936) have an opposite effect, i.e. they favour ectodermal development. The mechanism of segregation of the egg into the primary germ-layers might be elucidated if we knew more about the biochemical mode of action of these agents. A series of biochemical studies on lithium-treated and normal eggs and larva was therefore undertaken. The studies began on the level of amino acids and peptides and continued on the levels of enzymes and intracellular inclusions. The total changes in the amino-acid composition of the egg were found to be rather small (Gustafson & Hjelte, 1951).

scholarly journals Vegetalization of the Sea-Urchin Egg by Dinitrophenol and Animalization by Trypsin and Ficin

Development ◽  
1953 ◽  
Vol 1 (4) ◽  
pp. 327-348
Author(s):  
Sven Hörstadius
Keyword(s):  
Sea Urchin ◽  
Sea Water ◽  
Lithium Ions ◽  
Apical Tuft ◽  
Sea Urchin Egg ◽  
Different Types ◽  
Other Substances

Herbst (1892) made the remarkable discovery that the differentiation of the sea-urchin egg was shifted in a vegetal direction when lithium ions were present in the sea-water. The vegetalization implies a failure of the apical tuft to appear, a displacement of the skeleton-forming cells in the animal direction, a reduction of the ectodermal region, and a corresponding enlargement of the endoderm, which often leads to exogastrulation. Strong lithium action may lead to complete endodermization of the egg. Many other substances have later been found to cause a change of differentiation, either in a vegetal or animal direction, e.g. a partial or complete animalization by treatment of unfertilized eggs with SCN- or 1-ions (also SO4, Br, and tartrate, Lindahl, 1936). The animal and vegetal principles are considered as two opposite, antagonistic gradients (Runnström, 1928 a, b) representing different types of metabolism (Lindahl, 1936).

scholarly journals The Fertilization Reaction in the Sea-Urchin Egg. The Effect of Nicotine

1950 ◽  
Vol 27 (3) ◽  
pp. 400-406
Author(s):  
LORD ROTHSCHILD ◽  
M. M. SWANN
Keyword(s):  
Sea Urchin ◽  
High Speed ◽  
High Probability ◽  
Sea Water ◽  
Low Speed ◽  
Cortical Structure ◽  
Psammechinus Miliaris ◽  
Sea Urchin Egg ◽  
Low Probability

1. Unfertilized eggs of Psammechinus miliaris which have been allowed to stand in sea water containing nicotine and are then inseminated in normal sea water are polyspermic. 2. Polyspermy is not due to an increase in the speeds at which spermatozoa swim in these circumstances; nor to a decrease in the rate at which the change in cortical structure of the egg, the first sign of fertilization, is propagated over the egg surface. 3. Experiments to test alternative explanations of the effect of nicotine have been carried out. 4. The experiments do not enable a firm decision to be made between (a) a high-speed block to polyspermy (which has not been observed) with a high probability of a successful collision, and (b) a low-speed (20 sec.) block to polyspermy with a low probability of a successful collision.

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