Binding of Lens culinaris lectin to sea urchin embryo chromatin.

Lentin binds specifically to sea urchin embryo chromatin. This binding is saturable and inhibited by alpha-methyl-mannose. Scatchard plot analysis of the binding reaction suggests a single binding site.     

Teratogenic effect of tolbutamide on the development of the sea urchin embryo (Paracentrotus lividus lamarck)

Summary The hypoglycemic agent tolbutamide was tested for its action on the cleavage and differentiation of the sea urchin embryo. Tolbutamide effects a strong selective action on the endoderm which becomes suppressed.     

Phosphoproteinphosphatase activity in sea urchin embryos

Riassunto Si è studiata l'attività fosfoproteinfosfatasica in omogenati totali di uova ed embrioni diParacentrotus lividus e diArbacia lixula. La reazione ha un optimum a pH acido, è stimolata da K⁺ e Na⁺ ed è inibita da Ca⁺⁺ e Mg⁺⁺. L'attività enzimatica aumenta tra la fecondazione e lo stadio a 64 blastomeri; in seguito rimane costante fino a blastula con mesenchima; quindi generalmente decresce.

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This work has been supported by a grant from the Consiglio Nazionale delle Ricerche to the Laboratory of Comparative Anatomy (Research Group of Embryology).     

Microincineration of sea urchin eggs during cleavage

Zusammenfassung Im Zytoplasma der unbefruchteten Seeigeleier sind die Aschen gleichmäßig verteilt; gegen die Kortikalschicht sind sie hingegen etwas angehäuft. Nach der Befruchtung, im Spermaster-Stadium, ordnen sich die Aschen radiär um den zentral gelegenen Kern. Eine starke Aschenansammlung findet sich an der Stelle der Spindel.     

Inhibition of sea urchin egg cleavage by ribonuclease

Résumé La ribonucléase exerce une action inhibitrice sur le clivage des ufs d'oursins. La source commerciale de l'enzyme, la concentration utilisée et l'état des ufs déterminent les effets obtenus. Ceux-ci varient entre une inhibition totale immédiate et un ralentissement des divisions cellulaires, suivi d'un développement anormal éventuellement abortif.En outre, la ribonucléase a une action complexe sur la membrane de fertilisation, la couche hyaline et la membrane cellulaire. Cette dernière action pourrait être liée aux effets antimitotiques observés.

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Contribution No.126 from the Oceanographic Institute, Florida State University, Tallahassee (Florida). Aided by a grant from the National Science Foundation.     

The distribution of mitochondria in sea urchin embryos

Zusammenfassung Zytologische Untersuchungen an Embryonen von zwei Seeigelarten haben in bezug auf die Lokalisation der Mitochondrien keinen Unterschied zwischen animaler und vegetativer Hemisphäre ergeben. Vorläufige Versuche, mit Hilfe einer quantitativen Methode die Mitochondrien in Homogenaten zu zählen, ergaben eine starke Zunahme auf dem Stadium der Blastula und eine anschliessende Abnahme der Mitochondrienzahl pro Embryo.

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Research supported by the National Cancer Institute, National Institutes of Health, United States Public Health Service.     

Zinc increases the longevity of unfertilized sea urchin eggs

Summary We have found that Zn²⁺ prevented lysis of unfertilized sea urchin eggs, and the eggs retained the ability to form fertilization membranes and to divide. SDS polyacrylamide gel electrophoresis showed that proteolysis of several proteins accompanied egg lysis, but Zn²⁺ inhibited this proteolysis. Therefore, Zn²⁺ blocks protease activity directly or indirectly and thereby prolongs the longevity of unfertilized sea urchin eggs.     

Free choline in sea urchin embryos (Paracentrotus lividus)

Summary A sensitive radio-enzymatic assay for choline, applied to extracts of developing sea urchin embryos, revealed that free choline in eggs declines during cleavage and rises abruptly previous to gastrulation, indicating an important shift in choline metabolism between these two stages.     

Involvement of a sperm aminopeptidase in fertilization of the sea urchin

Summary Inhibitory efficiencies of bestatin methyl ester and its nine analogs for sea urchin sperm aminopeptidase activity were similar to the efficiency of the same compounds as inhibitors either of sperm respiration or of fertilization. This suggests that a sperm aminopeptidase plays a role in fertilization in the sea urchin, possibly through its involvement in sperm respiration.Acknowledgment. We are grateful to Dr Wataru Tanaka of Nippon kayaku co. for his gifts of bestatin and its analogs. We are also indebted to Mrs Akiko Tsuchida-Watanabe for her technical assitance, and to the staff of Asamushi Marine Biological Station, Tohoku University, where part of this work was carried out. This work was supported in part by a Grant-in-Aid for Scientific Research from the Ministry of Education, Science and Culture of Japan.