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A new method to induce oocyte maturation in holothuroids (Echinodermata)

Summary Oocyte maturation in sea cucumbers is stopped during the meiosis at prophase I. Maturation naturally concludes just before spawning leading to a mature oocyte ready to be fertilized. Although thermal shocks applied on mature individuals can induce spawning, it is currently not possible to perform reliably in vitro fertilization of sea cucumber oocytes. The present paper reports the discovery of a new and highly effective oocyte maturation inducer (OMI), called MIF (for maturation inducing fractions). MIF's effects on oocytes of the marketable species Holothuria scabra were analysed and compared to that of the few OMIs described in literature. MIF induces the maturation and fertilization of more than 90% of oocytes while other OMIs [1-methyladenine, dithiothreitol (DTT), dimercapto-propanol (BAL) and L-cysteine] induces 28–90% of oocytes to mature depending on the tested inducer. Moreover the use of the other OMIs result in fertilization rates that never exceed 40%, and the obtained larvae often resent developmental abnormalities. MIF's action on H. scabra oocytes is efficient yearlong even outside the spawning period of H. scabra. MIF is effective on the oocytes of all aspidochirote species tested so far but only when it is prepared from spawns of regular female sea urchin.