Identification and analysis of localizedmaternal determinants in ascidian egg cytoplasm

卵细胞质中的母体信息在动物胚胎发生中起着至关重要的作用。在海鞘动物中，后植物卵细胞质参与了重要事件，如前后轴的指定、肌肉和间充质细胞命运的决定、生殖细胞的形成、不平等分裂、特定母体mRNAs的定位和细胞周期控制。到目前为止，我们分离了9个本地化的母体mRNAs并对它们进行了测序。然后，我们对7个RNA(HrPEM、HrPOPK-1、HrWNT-S、HrGLUT、HrPEM-3、HrPEM-1、HrPEM-2)进行了功能分析。结果表明，这些定位的母体mRNAs在胚胎发育过程中发挥着不同的作用。尤其是HrPEM(没有相似性)参与了胚胎后极连续的不平等卵裂。另一种定位的mRNA，HrPOPK-1(激酶)，是某些mRNAs浓缩和重新定位到中心体吸引小体所必需的。这些发现很有趣，值得进一步深入分析。

Maternal information within eggcytoplasm plays crucial roles in animal embryogenesis. In ascidians, the posterior-vegetal egg cytoplasm is involved in important events such as the antero-posterior axis specification, muscle and mesenchyme cell fate determination, germ cell formation, unequal cleavage, localization of specific maternal mRNAs, and cell cycle control. So far, we isolated nine localized maternal mRNAs and sequenced them. Then we carried out functional analysis of seven RNAs (HrPEM, HrPOPK-1, HrWnt-S, HrGLUT, HrPEM-3, HrPEN-1, HrPEM-2) by inhibition of translation with morpholino antisense oligonucleotides. The results demonstrated that these localized maternal mRNAs play various roles in embryogenesis. Especially, HrPEM (with no similarity) is involved in successive unequal cleavage in the posterior pole of embryos. Another localized mRNA, HrPOPK-1 (kinase), is required for concentration and relocalization of certain mRNAs to the centrosome-attracting body. These findings are interesting and worth for further extensive analysis.