Shigeyoshi Miyashiro

Structure of a novel steroidal saponin, pachastrelloside A, obtained from a marine sponge of the genus pachastrella

Abstract A novel steroidal glycoside, pachastrelloside A, has been isolated from a marine sponge and its structure was elucidated as 2α,3β-dihydroxy-4β- O -(β-D-galactopyranosyl)-7α- O -(4- O -acetyl-β-Dxylopyranosyl)ergosta-5,24(28)-diene. This glycoside inhibits cell division of fertilized starfish eggs but does not affect nuclear divisions to form multinucleated, unicellular embryos.

Effect of Glycine and L-Isoleucine on Protein Production by Bacillus brevis No. 47

Among factors affecting the protein production by Bacillus brevis No. 47, glycine and l-isoleucine were found to be prominent in stimulating protein production. The simultaneous addition of appropriate amount of these amino acids resulted in the largest accumulation of proteins; namely, 12 g/liter.The mode of action of glycine and isoleucine appeared different. Isoleucine stimulated the synthesis of both extracellular and intracellular proteins, while glycine caused a considerable increase of extracellular protein accumulation with a concomitant decrease in the amount of intracellular protein. Therefore, glycine may have a function in stimulating protein excretion. Glycine made cells more sensitive to lysozyme and caused a large decrease in alanine content of the cell wall fraction. These findings supported the possibility that glycine alters cell wall structure in such a way so as to facilitate protein excretion.The proteins produced in the presence of glycine as a whole were smaller in molecular weight ...

Modes of Flocculation of Yeast Cells with Flocculant Produced by Aspergillus sojae AJ7002

The conditions and modes of flocculation of yeast cells with flocculant produced by Asp. sojae AJ7002 were investigated. Optimum pH for flocculation was lower than 4.0. Optimum temperature for flocculation was in the range from 30 to 80°C. The addition of saccharides, amino acids, organic acids or EDTA to the reaction mixture had no effect on the aggregation of cells. The addition of salts to the reaction mixture reduced the rate of flocculation. The rate of flocculation was affected by pretreatment of cells with some chemicals and enzymes, such as uranyl nitrate, CTAB, Concanavalin A, pronase and acid phosphatase. Optimum concentration of flocculant for flocculating rate was within the range of 10–200 ppm. Age of cells and the addition of cycloheximide and sodium fluoride to the culture media affected the rate of flocculation. These results suggest that the mechanism of yeast flocculation with flocculant is explained in terms of the bridging phenomena between discrete cells and extended polymer chains, f...

Selective inhibition of membrane fusion events in echinoderm gametes and embryos by halenaquinol sulfate

Halenaquinol sulfate, a hydroquinone sulfate obtained from the sponge Xestospongia sapra, prevented cell membrane fusion events of echinaderm gametes but did not affect early embryonic development of fertilized eggs up to the gastrula stage. However, halenaquinol sulfate inhibited secretion of hatching enzyme, resulting in the formation of gastrulae that were surrounded by the fertilization envelope. Therefore, the use of halenaquinol sulfate offers a unique opportunity to analyze the role of secretory events in complex populations of cells without affecting other cellular functions.

Isolation and identification of a specific and reversible inhibitor of starfish development

An inhibitor of development of the starfish Asterina pectinifera was purified to homogeneity from a culture of the bacterium Bacillus subtilis, and was identified as adenosine. Adenosine at 6 μg/ml was shown to halt embryonic development specifically at the 256‐cell stage when all the embryonic cells differentiate into epithelial cells. By returning treated embryos to normal seawater, they developed normally to the bipinnaria stage.

Development of Fertilized Starfish Eggs in Which Cytokinesis is Prevented by Iturin A–2

Iturin A–2, a cyclic peptide obtained from cultures of Bacillus subtilis inhibited cell division but not nuclear divisions of fertilized eggs of the starfish Asterina pectinifera, resulting in the formation of non‐cleaving eggs containing all the embryonic nuclei in a common cytoplasm. Fertilized eggs in which cleavage was prevented by iturin A–2 (50μg/ml) synthesized DNA, RNA and protein at comparable rates to those of normal embryos up to the onset of blastulation. In single‐cell embryos, however, elevation of the level of transcription, which is a characteristic marker of blastulation, did not take place and the chromatin masses eventually dispersed in the cytoplasm.

Stimulatory Effect of Inhibitors of Cell Wall Synthesis on Protein Production by Bacillus brevis

Mutants of Bacillus brevis No. 47 that grew in synthetic media containing a high concentration of ammonium sulfate were stable and had high protein production. Among various antibiotics tested, inhibitors of cell wall synthesis, such as bacitracin or β-lactam antibiotics, were effective in greatly increasing the accumulation of exoproteins.When 60 µg/ml of bacitracin was added to the culture at the early logarithmic growth phase, about 9 mg/ml of proteins was produced. Such a protein yield was estimated to be nearly maximum from a given amount of glucose. Alterations in cell wall components were found in cells grown in the presence of bacitracin. Possible relationships between cell wall structure and protein production were discussed.

Significance of an Increase of Intracellular Adenosine Concentration for Dormancy in Starfish Blastulae

Adenosine at concentrations greater than 6 μg/ml halted embryonic development of the starfish Asterina pectinifera specifically at the 256‐cell stage which corresponds to the onset of blastulation. When a fertilized egg was cultured continuously in sea water containing adenosine from fertilization, a gradual increase in intracellular concentrations of free adenosine was observed before a cessation of development took place. On the other hand, intracellular concentrations of ATP, ADP and AMP in the embryo cultured in sea water containing adenosine were nearly the same as those of an embryo cultured in sea water without adenosine. By returning the development‐arrested embryo to normal sea water the embyro developed normally to the bipinnaria stage accompanied by a gradual decrease in the intracellular cencentration of adenosine.

Isolation of iturin A-2 as an inhibitor of cytokinesis of starfish embryos

Abstract 1. 1. We have purified substances from the bacterium Bacillus subtilis that inhibit the cell division of embryos of the starfish, Asterina pectinifera , and which are identified as iturin A-2 and closely related cyclic peptides. 2. 2. Iturin A-2 at a concentration of 12.5 μg/ml or greater inhibited cell division of the fertilized starfish egg but not nuclear division, resulting in formation of a multinueleated unicellular embryo. 3. 3. Iturin A-2 microinjected into a fertilized egg was ineffective in halting cell division. 4. 4. From the results of these experiments, we conclude that the arrest of cleavage produced by iturin A-2 is due to the inability of the cell membrane to make a furrow at cytokinesis.