Molecular mechanism of inductive and inhibitory regulation in the spawning of marine bivalves : Analysis of a novel inhibitor from the central nervous system

5-羟色胺(5-羟色胺)诱导的卵子释放被来自大脑和脚神经节的一种新的因子和前列腺素F2α(PG F2α)强烈抑制。PgF2α强烈抑制5-羟色胺诱导的卵子释放，但不抑制卵母细胞成熟，提示PgF2α可能抑制5-羟色胺诱导的生殖道纤毛运动。我们从扇贝的CPG中发现了一种新的因子，可以抑制5-羟色胺诱导的卵母细胞成熟，从而导致卵子释放的抑制。我们将这种新型抑制因子命名为卵母细胞成熟抑制因子(OMAF)。2)OMAMAF的信号通路通过血液转运到卵表面，抑制5-羟色胺诱导的卵母细胞成熟，这种信号通路是通过5-羟色胺受体…介导的更多的是在卵母细胞膜上，通过其自身的接受机制。5-羟色胺在细胞外钙离子存在下，通过生殖道诱导卵母细胞成熟和随后的卵子释放。OMAF降低了5-羟色胺引起的细胞内钙离子浓度的升高，表明OMAF通过钙离子通道抑制细胞外钙离子流入卵母细胞。c)Scallop 5-HTcDNA5-Htpy的克隆、结构和预测功能用从3、6和7个跨膜区保守区设计的简并引物进行RT-PCR和随后的巢式PCR。获得了编码454个氨基酸残基的全长约2.0kbp的5-HTpy基因。5-羟色胺被聚为5-羟色胺1亚型受体亚群，其中5-羟色胺通过5-羟色胺与胃肠道的偶联在细胞内的转导抑制cAMP的产生，并诱导细胞外钙离子流入卵母细胞。由5-羟色胺触发的双壳类动物的产卵分别受生殖管和卵母细胞的α和OMAF的调控，成熟卵母细胞停滞在减数分裂前期的特定阶段直到产卵。较少

a)Molecules related to the regulation of oocyte maturation and spawning in marine bivalvesThe serotonin (5-HT)-induced egg release has been strongly inhibited by a novel factor from the cerebral and pedal ganglion (CPG) and prostaglandin F2α (PG F2α). PG F2α strongly inhibited 5-HT-induced egg release, but not oocyte maturation, thus suggesting that PGF2α may suppress 5-HT-induced ciliary movement in the gonoduct. We found a novel factor from CPG of the scallop to inhibit 5-HT-induced oocyte maturation and thereby result in the suppression of egg release. We named the novel inhibitor Oocyte Maturation Arresting Factor (OMAF). It was demonstrated that the proteinaceous OMAF is received by a receptive mechanism of oocyte and OMAF appears to be a universal substance to inhibit 5-HT-induced oocyte maturation in bivalve species.b)Signaling pathway of OMAFOMAF is transported to egg surface through blood flow and inhibits oocyte maturation induced by 5-HT, which is mediated through 5-HT recep … More tor in the oocyte membrane, via a receptive mechanism of its own. 5-HT induced oocyte maturation and subsequent egg release through the gonoduct in the presence of extracellular Ca^<2+>. OMAF reduced an increase in intracellular Ca^<2+> induced by 5-HT, suggesting that the OMAF inhibits an extracellular Ca^<2+> influx into oocyte via Ca^<2+> channels.c)Scallop 5-HT cDNA (5-Htpy) cloning and the structure and predicted functionRT-PCR and subsequent Nested PCR were carried out using degenerate primers designed from the conservative region of 3rd, 6th and 7th transmembrane domains and 3', 5' RACE was followed. We obtained 5-HTpy cDNA of ca 2.0 kbp containing ORF encoding 454 amino acid residues. The 5-HTpy was clustered into 5-HT1 subtype receptor group coupled with Gi, in which the intracellular transduction of 5-HT via 5-HTpy coupled with Gi inhibits cAMP production and induces extracellular Ca^<2+> influx into oocyte.The spawning of bivalves triggered by 5-HT is regulated by PGF2α and OMAF at the gonoduct and oocyte, respectively, and full-grown oocyte is arrested at the dictyate stage of meiotic prophase until spawning. Less