Identification and biosynthesis of sperm receptor in quail oocyte

鸟类的卵母细胞被一层半透明的膜包围着，叫做卵黄膜。卵黄膜由内层、外层和连续膜三层组成。排卵时卵母细胞仅被卵黄膜的内层包裹。我们发现，鹌鹑卵泡颗粒细胞含有33 kDa糖蛋白（ZPC），这是鹌鹑蛋内层的主要成分之一。虽然ZPC作为鹌鹑“精子受体”的候选体在受精过程中具有重要的生理意义，但在排卵周期中，颗粒细胞中ZPC产生的调控细节尚不清楚。为了探讨ZPC产生的调控机制，我们采用Western blot和Northern blot方法研究了ZPC在排卵周期中的表达。此外，我们还对颗粒细胞进行了添加或不添加各种激素和生长因子的培养，以研究内分泌和旁分泌对ZPC产生的控制。体内Western blot和Northern blot分析发现，在卵泡成熟过程中，生长卵泡颗粒细胞中ZPC的表达增加，在最大的卵泡中活性最高。为了研究各种激素和生长因子对ZPC生成的影响，从三个最大的卵泡中获得颗粒细胞，用FSH、LH、EGF、IGF- I、IGF- II、TGF- α、TGF- β、孕酮、雌二醇或睾酮培养72小时。从第三大卵泡中分离的颗粒细胞中观察到对ZPC产生刺激的最显著影响。其他激素或生长因子没有引起明显的增加。这些数据表明，鹌鹑颗粒细胞在FSH的作用下产生ZPC。

The avian oocyte is bounded by the thin translucent membrane called vitelline membrane. The vitelline membrane consists of three layers, the inner and outer layers and the continuous membrane. Only the inner layer of vitelline membrane surrounds the oocyte at the time of ovulation. We have found that the granulosa cells of the preovulatory follicles contain 33 kDa glycoprotein (ZPC) one of the major components of the inner layer in quail egg. Though the physiological importance of ZPC for fertilization was pointed out as the candidate of "sperm receptor" in quail, the details in the regulation of ZPC production in granulosa cells during ovulation cycle remains obscure. To investigate the regulatory mechanism of ZPC production we have studied the expression of ZPC during the ovulation cycle by Western blot and Northern blot analyses. Moreover, we cultured the granulosa cells with or without various hormones and growth factors to study the endocrine and paracrine control of ZPC production. From the Western blot and Northern blot analyses in in-vivo study, the expression of ZPC in the granulosa cells of growing follicles increased during follicular maturation with the highest activity in the largest follicle. To investigate the effects of various hormones and growth factors on the ZPC production, the granulosa cells obtained from the three largest follicles were cultured for 72 hr with FSH, LH, EGF, IGF- I, IGF- II, TGF- alpha, TGF- beta, progesterone, estradiol, or testosterone. The most prominent effects on stimulation of ZPC production was observed in the granulosa cells isolated from the third largest follicle cultured by the addition of FSH.Other hormones or growth factors caused no significant increase. These data illustrate that quail granulosa cells produce ZPC in response to FSH.