Unfertilized sea urchin eggs

The inhibition of amino-acid transport has been regarded as the main toxic effect of mercury compounds [82], The biochemical mechanism underlying the inhibition is unclear. In unfertilized sea-urchin eggs an interaction with the amino-acid carrier was found, whereas in fertilized eggs inhibition of amino-acid transport was indirect and might result from an elevation of the Na + content of the egg caused by the inhibition of the Na+ pump [83]. The action on the diffusional process could be mediated by an effect on membrane phospholipids or on membrane proteins, or by interaction with Ca2+ which stabilizes membrane structure. Mercuric chloride in skate liver cells inhibited amino acid transport, decreased Na + /K + -ATPase (adenosinetriphosphatase) activity, impaired volume regulatory mechanisms and increased the permeability of the plasma membrane to potassium [84]. It has been suggested that... 

Salik, J., Herlands, L., Hoffmatm, H.P., and Poccia, D. (1981) Electrophoretic analysis of the stored histone pool in unfertilized sea urchin eggs quantification and identification by antibody binding. J. Cell Biol. 90, 385-395. 

In 1982 Palumbo et al. (28) reported the isolation of a relatively large amount of 5-mercapto- 1-methyl-L-histidine (4) from unfertilized sea urchin eggs (Paracentrotus lividus), in addition to glutathione. In preliminary experiments, both 4 and the corresponding disulfide 5 were found in aqueous extracts. Therefore, an isolation procedure was developed that involved, in an early stage, the conversion of the thiol to the more stable... 

Tosuji H, Fusetani N, Seki Y. 2003. Calyculin A causes the activation of histone HI kinase and condensation of chromosomes in unfertilized sea urchin eggs independently of the maturation-pjromoting factor. Comp Biochem Physiol C Toxicol Pharmacol 135(4) 415 24. 

Asano Y, Mabuchi I. 2001. Calyculin-A, an inhibitor for protein phosphatases, induces cortical contraction in unfertilized sea urchin eggs. Cell Motil Cytoskeleton 48(4) 245-261. 

Some proteins, such as the poly(A)-binding protein (p78), are present in most if not all mRNPs, whereas others appear to be cell specific and mRNA selective. In unfertilized sea urchin eggs and Xenopus oocytes, for example, untranslated messenger is sequestered by association with proteins that prevent translation until later stages of development. Duck reticulocytes contain globin mRNP, which cannot be translated in vitro, whereas the mRNA obtained by deproteinizing the complex can be translated, showing that in this case translation is prevented by the mRNP proteins. 

Fig. 12. Two-dimensional correlated spectrum of extracted, unfertilized sea urchin eggs. The pH of the mixture was 7.9S. The labeling is the same as in Fig. 10 with the following exceptions cross-peak f indicates that the doublets at — 9.2S and —10.0 ppm are due to the diphosphate NAD and peak e consists of two overlapping cross-peaks, indicating the weak doublets centered at —10.6 and —10.8 ppm are coupled to two doublets under the laige doublet at —9.25 ppm. This spectrum was obtained in collaboration with Dr. D. K. Jemiolo and Professor R. B. Martin.

From these two kinds of experiments the conclusion was drawn that the mRNA s for the increased protein synthesis occurring after fertilization were already present in the unfertilized egg but in inactive form. Fertilization then activated the mmRNA. Additional support for this view appeared in experiments by Maggio, Vittorelli, Rinaldi, and Monroy (1964) and by Slater and Spiegelman (1966a,b) showing template activity in RNA extracts from unfertilized sea urchin eggs. The occurrence of template RNA in the unfertilized sea urchin egg is also demonstrated in the DNA-hybridization experiments by Whiteley,... 

There is, then, convincing evidence from several sources that mature unfertilized sea urchin eggs synthesize protein. Since the mature egg can remain in a fertilizable condition without visible change in appearance, and with essentially normal developmental capacity for a considerable period after. shedding from the ovary, it is evident that this... 

In electron microscopic studies Verhey, Moyer, and Iverson (1965) have demonstrated that microsomes of unfertilized sea urchin eggs differ from those of fertilized eggs in being associated with RNase-resistant, trypsin-labile material. 

Mackintosh, F. R., and Bell, E. (1967). Stimulation of protein synthesis in unfertilized sea urchin eggs by prior metabolic inhibition. Biochem. Biophys. Res. Commun. 27, 425-430. 

Maggio, R., Vittorelli, M. L., Rinaldi, A. M., and Monroy, A. (1964). In vitro incorporation of amino acids into proteins stimulated by RNA from unfertilized sea urchin eggs. Biochem. Biophys. Res. Commun. 15, 436-441. 

PiKO, L., and Tyler, A. (1965). Deoxyribonucleic acid content of unfertilized sea urchin eggs. Am. Zoologist 5, 636. 

ScAR.YNo, E., and Maggio, R. (1957). An exchange between P labelled pyrophosphate and ATP catalyzed by amino acids in unfertilized sea urchin eggs. Exptl. Cell Res. 12, 403-405. 

Jeanmart J, Uytdenhoef P, De Sutter G, Legros F. 1976. Insulin receptor sites as membrane markers during embryonic development. I. Data obtained with unfertilized and fertilized sea urchin eggs. Differentiation 7(l) 23-30. 

Studies of the incorporation of amino acids and into proteins of sea urchin eggs have established that fertilization is immediately followed by increased protein synthesis. In contrast, the unfertilized egg synthesizes little or no protein. The inhibition of protein synthesis blocks cellular proliferation. Detailed study of the machinery involved in protein synthesis has... 

Hsiao, S. C., and H. Boroughs. 1958. The uptake of radioactive calcium by sea urchin eggs. I. Entrance of Ca into unfertilized egg cytoplasm. Biol. Bull. 114(2) 196-204. 

Bracket, J., Decroly, M., Ficq, A., and Quertier, J. (1963). Bibonucleic acid metabolism in unfertilized and fertilized sea-urchin eggs. Biochim. Biophys. Acta 72, 660-662. 

Tyler, A., Piatigorsky, J., and Ozaki, H. (1966). Influence of individual amino acids on uptake and incorporation of valine, glutamic acid and arginine by unfertilized and fertilized sea urchin eggs. Biol, Bull, 131, 204. 

Verhey, C. a., Moyer, F. H., and Iverson, R. M. (1965). Differences in the microsome complexes of unfertilized and fertihzed sea urchin eggs revealed by chemical dissection followed by microscopy. Am. Zoologist 5, 637. 

---