皮层反应是脊椎动物卵细胞在受精过程中的重要步骤，主要功能是阻止多精受精和保障受精卵发育。目前已知胞质内钙振荡对皮层反应是必需的，但Ca2+的调控机制却并不清楚。本实验室通过TALEN介导的基因组定点突变技术得到了一批斑马鱼突变系，其中npdc1a纯合突变雌鱼所产胚胎呈现卵膜不能鼓起的表型。npdc1a突变雌鱼卵巢结构正常，但生成的卵细胞皮层反应出现异常，皮质颗粒无法进行胞吐作用，因而导致卵膜无法正常鼓起。本项目拟在此基础上深入研究npdc1a的功能，特别是在皮层反应中与肌动蛋白—微丝动态变化以及与钙离子信号通路潜在的相互作用，为揭示皮层反应的分子机制提供突破口。此外，npdc1a突变雌鱼的卵母细胞中卵黄小体的成熟出现缺陷，卵黄小体与皮质颗粒的相对位置分布也出现了异常。本项目将同时研究npdc1a在卵黄小体成熟过程中的作用，以及卵黄小体与皮质颗粒分布的关系与相互作用，推进我们对皮层反应和斑马

Cortical reaction is an important process during vertebrate fertilization, which will prevent polyspermy and provide an essential environment for zygote development. Previous studies showed that cytoplasmic Ca2+ wave is necessary for the induction of cortical reaction, while the mechanism is poorly understood. Utilizing TALEN-mediated gene knockout, our lab generated many zebrafish mutant lines. One of the mutants, npdc1a, showed defective chorion elevation in F3 embryos. The mutant females had normal ovary structures, while in their oocytes, cortical granules were not exocytosed during cortical reaction, leading to the chorion elevation defect phenotype. In this project, we will explore the function of npdc1a during cortical granule exocytosis, and illuminate the molecular mechanism of cortical reaction, especially evaluate its potential interaction with Ca2+ signalling and the dynamics of actin filament network. In addition to the cortical reaction defect, npdc1a mutant oocytes also showed defects in yolk body maturation and the distribution of yolk bodies and cortical granules. We will further investigate the regulatory pathway behind yolk body maturation, and investigate the potential relationship between yolk body and cortical granule distribution. The findings of this prject will help us to further understand the mechanism of cortical reaction and zebrafish oogenesis.