scholarly journals AN INDIRECT METHOD TO ASSAY FOR MITOTIC CENTERS IN SAND DOLLAR (DENDRASTER EXCENTRICUS) EGGS

1966 ◽  
Vol 30 (3) ◽  
pp. 555-562 ◽  
Author(s):  
Hans A. Went
Keyword(s):  
Sea Urchin ◽  
De Novo ◽  
Sea Water ◽  
Early Prophase ◽  
Sand Dollar ◽  
Normal Pattern ◽  
Mitotic Apparatus ◽  
Sea Urchin Eggs ◽  
Dendraster Excentricus ◽  
Normal Controls

It is possible consistently to induce sea urchin and sand dollar eggs to cleave directly from one cell into four cells. This is done by exposing the fertilized eggs to benzimidazole for 20 to 30 min beginning about early metaphase. The mitotic apparatus regresses, the cells do not cleave, and shortly after they are returned to normal sea water an early-prophase-appearing nucleus is present in each cell. Each cell then organizes a tetrapolar tetrahedral mitotic apparatus de novo, instead of transforming a bipolar mitotic apparatus into a tetrapolar figure, and cleaves one-to-four. In another type of experiment, it appears that sand dollar eggs exposed to mercaptoethanol during the first period of mitotic center duplication have only half as many centers by first cleavage metaphase as the normal controls. This is consistent with an earlier report by Mazia et al (1960). Using this same experimental technique, it was demonstrated that benzimidazole, on the contrary, does not interfere with mitotic center duplication in sand dollar eggs. A labeling experiment demonstrated that benzimidazole does not interfere markedly with the normal pattern of incorporation of C14-thymidine into the DNA of sea urchin eggs. The data reported here suggest that judicious treatment of sand dollar eggs (and probably sea urchin eggs, too) with benzimidazole can induce the eggs to cleave into as many cells as there were mitotic centers sometime earlier, for example at early metaphase of the first cleavage division. This provides a very useful tool for studies on the process of mitotic center duplication.

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.

Cytasters induced within unfertilized sea-urchin eggs

1983 ◽  
Vol 61 (1) ◽  
pp. 175-189
Author(s):  
R. Kuriyama ◽  
G.G. Borisy
Keyword(s):  
Electron Microscopy ◽  
Sea Urchin ◽  
Sea Water ◽  
Light And Electron Microscopy ◽  
Sea Urchin Eggs ◽  
Microtubule Organizing Centres ◽  
Treatment Step

Conditions that induce the formation of asters in unfertilized sea-urchin eggs have been investigated. Monasters were formed by treatment of eggs with acidic or basic sea-water, or procaine- or thymol-containing sea-water. A second treatment step, incubation with D2O-containing, ethanol-containing or hypertonic sea-water induced multiple cytasters. The number and size of cytasters varied according to the concentration of agents and duration of the first and second treatments, and also upon the species of eggs and the season in which the eggs were obtained. Generally, a longer second treatment or a higher concentration of the second medium resulted in a higher number of cytasters per egg. Asters were isolated and then examined by light and electron microscopy. Isolated monasters apparently lacked centrioles, whereas cytasters obtained from eggs undergoing the two-step treatment contained one or more centrioles. Up to eight centrioles were seen in a single aster; the centrioles appeared to have been produced during the second incubation. Centrospheres prepared from isolated asters retained the capacity to nucleate the formation of microtubules in vitro as assayed by light and electron microscopy. Many microtubules radiated from the centre of isolated asters, whether they contained centrioles or not. This observation is consistent with many other reports that microtubule-organizing centres need not contain centrioles.

scholarly journals CHANGES IN THE POTASSIUM CONTENT OF SEA URCHIN EGGS ON FERTILIZATION

1951 ◽  
Vol 34 (3) ◽  
pp. 285-293 ◽  
Author(s):  
Anna Monroy Oddo ◽  
Maria Esposito
Keyword(s):  
Sea Urchin ◽  
Sea Water ◽  
Paracentrotus Lividus ◽  
Potassium Content ◽  
Minimum Point ◽  
Sea Urchin Eggs ◽  
Maximum Loss ◽  
Arbacia Lixula

In the eggs of Arbacia lixula and Paracentrotus lividus an uptake of K occurs during the first 10 minutes following fertilization. Between 10 and 40 minutes K is then released. Both in Arbacia and in Paracentrotus the minimum point of the curve coincides with the nuclear streak stage. A maximum loss of 25 per cent in Arbacia and 20 per cent in Paracentrotus with respect to the amount present in the unfertilized eggs has been found. From 40 minutes up to 1 hour K undergoes a further increase and when the first cleavage sets in the same amount of K is present as in the unfertilized eggs. By treating the eggs with K-free artificial sea water it has been established that about 60 per cent of the K content of the eggs is in a non-diffusible condition. Also under such conditions the eggs when fertilized are able to take up even the very small amount of K present in the medium that was released by them prior to fertilization.

Some Experiments on Sea-urchin Eggs with Desoxynucleic Acids from Sea-urchin Sperms

Development ◽  
1953 ◽  
Vol 1 (3) ◽  
pp. 261-262
Author(s):  
Sven Hörstadius
Keyword(s):  
New York ◽  
Sea Urchin ◽  
Sea Water ◽  
Water Injection ◽  
Dark Field ◽  
The Other ◽  
Columbia University ◽  
Sea Urchin Eggs ◽  
King's College ◽  
Fertilization Membrane

Dr. I. Joan Lorch, of King's College, London, and I have made some experiments on sea-urchin eggs with desoxynucleic acids (DNA) prepared from sperms of several sea-urchin species by Professor Erwin Chargaff, of Columbia University, New York. Unfertilized eggs did not react when put into a solution of DNA in sea-water. Injection of a small amount of DNA dissolved in Callan's solution had the following consequences. If the DNA did not mix with the cytoplasm but remained as a distinct droplet, the egg could be fertilized. The droplet moved slowly towards the surface and ran out of the egg. This sometimes only occurred after several cleavages. Such eggs developed normally. If, on the other hand, the DNA mixed with the cytoplasm the egg became activated. A fertilization membrane was raised. The surface layer in dark field changed in colour from yellow to white as is the case upon fertilization.

Displacement of Valine From Intact Sea-Urchin Eggs by Exogenous Amino Acids

1968 ◽  
Vol 3 (4) ◽  
pp. 515-527
Author(s):  
J. PIATIGORSKY ◽  
A. TYLER
Keyword(s):  
Amino Acids ◽  
Glutamic Acid ◽  
Sea Urchin ◽  
Sea Water ◽  
The Other ◽  
Metabolic Product ◽  
Primary Factor ◽  
Lytechinus Pictus ◽  
Sea Urchin Eggs ◽  
Neutral Amino Acids

Unfertilized and fertilized eggs of the sea urchin Lytechinus pictus were preloaded with [14C]valine and exposed to individual solutions of each of the twenty ‘coded’ [12C]amino acids in artificial sea water. After 1 h incubation the amount of radioactivity in the medium was determined. The radioactivity was effectively displaced by most of the other neutral [12C]amino acids that are known to compete with valine for uptake. A chromatographic test with fertilized eggs showed the displaced radioactivity to be [14C]valine and not some metabolic product. Addition of acidic, basic or some neutral amino acids that are known to be poor inhibitors of valine uptake did not cause significant quantities of label to appear in the medium. For the unfertilized eggs, the concentration of acid-soluble label remained many hundreds of times greater in the egg fluid than in the sea water. Tests indicated that efflux of [14C]valine and subsequent competition for re-entry is a primary factor responsible for the displacement phenomenon. That this may not be the sole factor is suggested by the fact that some amino acids that are known to be powerful inhibitors of valine uptake were found to be only weak displacers of [14C]valine. Neither [14C]arginine nor [14C]glutamic acid were displaced in significant amounts from preloaded unfertilized or fertilized eggs by any of the tested [12C]amino acids. Attempts were made to utilize the displacement of [12C]valine to elevate the incorporation of [14C]valine and of other labelled amino acids into protein by intact eggs. Unfertilized and fertilized eggs were pretreated with related [12C]amino acids and then exposed to [14C]valine or a mixture of [14C]amino acids. The results varied in the different tests, ranging from no significant increase to 2-fold.

scholarly journals IMMUNOCHEMICAL STUDIES OF 22S PROTEIN FROM ISOLATED MITOTIC APPARATUS

1969 ◽  
Vol 41 (2) ◽  
pp. 577-590 ◽  
Author(s):  
Thomas Bibring ◽  
Jane Baxandall
Keyword(s):  
Sea Urchin ◽  
Morphological Features ◽  
Mitotic Apparatus ◽  
Antibody Preparation ◽  
Sea Urchin Eggs ◽  
Microtubule Protein ◽  
Mild Acid

Evidence is presented that the "22S protein" of mitotic apparatus isolated from sea urchin eggs is not microtubule protein. An antibody preparation active against 22S protein is described, and immunochemical studies of the distribution of 22S protein in various cellular fractions and among morphological features of mitotic apparatus are reported. The protein is ubiquitous in the metaphase egg fractions that were tested but is not found in sperm flagella. It is immunologically distinct from proposed microtubule protein isolated from mitotic apparatus by the method of Sakai, and from proposed microtubule protein obtained after extraction with mild acid. It exists in nontubule material of isolated mitotic apparatus but is not detectable in microtubules.

Cortical Granule Exocytosis and Fertilization Coat Elevation is Reduced in Aging Sea Urchin Eggs

2000 ◽  
Vol 6 (S2) ◽  
pp. 966-967
Author(s):  
Amitabha Chakrabarti ◽  
Heide Schatten
Keyword(s):  
Plasma Membrane ◽  
Sea Urchin ◽  
Sea Water ◽  
Secretory Granules ◽  
Cortical Granule ◽  
Cortical Granules ◽  
Lytechinus Pictus ◽  
Sea Urchin Eggs ◽  
Cortical Granule Exocytosis ◽  
Granule Secretion

Cortical granules are specialized Golgi-derived membrane-bound secretory granules that are located beneath the plasma membrane in unfertilized sea urchin eggs. Upon fertilization cortical granules discharge in a reaction induced by calcium and release their contents between the plasma membrane and a thin vitelline layer that lines the plasma membrane. Microvilli at the plasma membrane elongate incorporting cortical granule membranes during elongation. The vitelline layer elevates and becomes the egg's fertilization coat that hardens and serves as physical block to polyspermy. While we do not understand the precise mechanisms that participate in cortical granule discharge it is believed that actin plays a role in this process. Because actin and calcium metabolism is affected in aging cells we investigated if cortical granule secretion is affected in aging sea urchin eggs.Lytechinus pictus eggs were obtained by intracoelomic injection of 0.5M KCI to release the eggs into sea water at 23°C.

Fertilization envelope assembly in sea urchin eggs inseminated in chloride-deficient sea water: II. Biochemical effects

1990 ◽  
Vol 25 (2) ◽  
pp. 177-185 ◽  
Author(s):  
Jeffrey D. Green ◽  
Patricia S. Glas ◽  
Sou-De Cheng ◽  
John W. Lynn
Keyword(s):  
Sea Urchin ◽  
Sea Water ◽  
Sea Urchin Eggs ◽  
Biochemical Effects

Non-plasmalemmal localisation of the major ganglioside in sea urchin eggs

Zygote ◽  
1993 ◽  
Vol 1 (3) ◽  
pp. 215-223 ◽  
Author(s):  
Hidehiko Shogomori ◽  
Kazuyoshi Chiba ◽  
Hideo Kubo ◽  
Motonori Hoshi
Keyword(s):  
Endoplasmic Reticulum ◽  
Sea Urchin ◽  
Indirect Immunofluorescence ◽  
Immunofluorescence Microscopy ◽  
Mitotic Apparatus ◽  
Sea Urchin Eggs ◽  
Indirect Immunofluorescence Microscopy ◽  
The One ◽  
Major Ganglioside ◽  
Hemicentrotus Pulcherrimus

SummaryM5 ganglioside (NeuGcα2–6Glcβl-' Cer) is the predominant glycosphingolipid in sea urchin eggs. Distribution of M5 ganglioside was studied in unfertilised and fertilised eggs of the sea urchin Hemicentrotus pulcherrimus by indirect immunofluorescence microscopy. In the cortices of unfertilised eggs, anti-M5 antibody strongly stained the submembranous, polygonal and tubular network of endoplasmic reticulum that was revealed by a membrane-staining dye, DiIC18(3). In addition to the cortical network of endoplasmic reticulum, at least two morphologically distinct vesicles were positive to the antibody. In the cortices isolated from fertilised eggs 30 min after insemination, the antibody stained only a similar network of endoplasmic reticulum, presumably the one reconstructed 5–10 min after fertilisation. During mitosis the endoplasmic reticulum is known to aggregate within the asters of the mitotic apparatus. Indeed, the antibody stained the asters and (more strongly) the vesicular components attaching to the periphery of the mitotic apparatus.

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