No abstract

External application of 0.2-100 pglml albuside B inhibits gastrulation of the starfish (Asterina pectinifera) embryo.Treated embryos retain the late blastula morphology with the vegetal plate. However, the vegetal plate is unreactive to soybean agglutinin, a probe for observing the progenitor cells of the archenteron (mesendoderm) in a normal embryo. The effective period of the treatment is limited from 4 to 6 h after fertilization, a period immediately before the onset of blastulation. RNA synthesis is unaffected during the period of sensitivity. The selectivity of the inhibition shows that albuside B may be a useful tool for studying the mechanisms of mesendoderm differentiation.

No abstract

We isolated a C-nucleoside from a culture broth conditioned by the actinomycete Streptmyces albus A282 and reported its structure as la.l The substance, being designated pyrrolosine, inhibited the RNA synthesis of starfish (Asterina pectinifera) embryos at blastulation. Recently, we found that the culture broth extract treated with an adenosine deaminase did not prevent the embryonic development at the blastulation stage, which raised a question as to the proposed structure of pyrrolosine in which no amino group exists.The adenosine deaminase treatment of pyrrolosine yielded an unknown product 2, which showed [a]2D -18.8° (c=0.2, H20) and mp 115° C. The molecular formula was determined by SIMS (m/z 269.0774 for MH+, D0.1 mM U). The compound 2 prevented the development of fertilized starfish eggs specifically at the rotating blastula stage at concentrations above 0.8 µg/ ml.A colorless crystal (0.35X0.05X0.01 mm) was obtained from an ethanol solution and used for X-ray analysis. The intensity data were collected with graphite monochromated Cu Ka radiation from a fine-focus rotating anode at 40 kV 80 mA using w/ 1.78 scan in a 26

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