FN Archimer Export Format PT J TI Effects of cytochalasin B on fertilization and ploidy in the Pacific oyster Crassostrea gigas BT AF LEDU, Christophe MCCOMBIE, Helen AS 1:;2:; FF 1:PDG-DRV-RA-DCOP-AT;2:PDG-DRV-RA-LGP; C1 Inst Francais Rech Exploitat Mer, IFREMER, Lab Genet & Pathol, F-17390 La Tremblade, France. C2 IFREMER, FRANCE SI TAHITI LA TREMBLADE SE PDG-DRV-RA-DCOP-AT PDG-DRV-RA-LGP IN WOS Ifremer jusqu'en 2018 IF 0.32 TC 5 UR https://archimer.ifremer.fr/doc/2003/publication-2845.pdf LA English DT Article DE ;Crassostrea gigas;Fertilization;Cytochalasin B;Polar body;Polyploidy AB The effects of cytochalasin B on fertilization and ploidy in Crassostrea gigas were examined in a controlled experiment. This enabled us to better understand why variable ploidy results have been found with the retention of polar bodies in previous studies on bivalve mollusks, and what the interaction with fertilization may be. By looking at the early development of Crassostrea gigas embryos with sequential samples stained using Hoechst 33258, a fluorescent DNA-specific dye, we compared normal evolution of fertilized eggs with that obtained with cytochalasin B treatment. In treated eggs, embryos with both three and four pronuclei were found after the second meiotic division. When embryos had three pronuclei, these were identified as the female pronucleus plus two chromatin groups arising from the retention of the two polar bodies. The fourth pronucleus present in some embryos was the male pronucleus. The absence of the male pronucleus in the embryos with only three pronuclei was interpreted as gynogenetic development due to the inhibitory effects of cytochalasin B on penetration of the sperm into the eggs. This result explains the findings of several previous studies where different ploidies resulted from double polar body inhibition in bivalve species. Implications of such treatments for post-embryogenic development are discussed. PY 2003 PD SEP SO Invertebrate reproduction and development SN 0168-8170 PU Balaban Publishers VL 44 IS 2-3 UT 000187231700006 BP 131 EP 137 ID 2845 ER EF