Absence of Species Specificity of Germinal Vesicle Factor Required for the Cytoplamic Cycle During Meiotic Division

Germinal vesicles (GV) of starfish oocytes are known to contain some factor(s) indispensable for inducing cyclic cytoplasmic activity, which may be involved in driving meiotic cell cycle. We have examined species specificity of the factor by injecting enucleated oocytes of the starfish, Asterina pectinifera, with GV contents of either different starfish (Asterias amurensis, Astropecten scoparius) or sea cucumber (Holothuria moebi). The injected oocytes showed cyclic changes in cortical tension after treatment with 1-methyladenine. Thus the nature of the factor appears similar among echinoderms. Growing oocytes of A. pectinifera much smaller (75% in diameter) than fully-grown oocytes did contain the factor to rescue the enucleated oocytes, even though such small oocytes themselves did not respond to 1-methyladenine. This result suggests that the factor begins to accumulate at the earlier stage of oogenesis.