Faculty of Agriculture, Department of Applied Biological Science, Kagawa University, 2393 Ikenobe, Miki, Kagawa 761-0795, Japan.
Department of Applied Bioresource Science, The United Graduate School of Agricultural Sciences, Ehime University, 3-5-7 Tarumi, Matsuyama, Ehime 790-8566 Japan.
Poult Sci. 2019 Oct 1;98(10):5100-5108. doi: 10.3382/ps/pez335.
Ovalbumin-related protein X (OVAX) is a 50 kDa egg-white protein which has heparin-binding affinity. In this study, migration of OVAX and its heparin-binding performance during embryogenesis of fertilized egg were investigated to explore a possible involvement in chick embryo development. Western blotting of egg yolks at different stages using an anti-OVAX antibody showed that OVAX accumulates in yolk during incubation of fertilized egg. Immunohistochemical analysis of embryo resided in 10-day-incubated eggs showed that OVAX existed in almost all tissues of the embryo. These suggest that OVAX is incorporated from egg white into the embryo through yolk sac. Heparin-sepharose chromatography, isothermal titrating calorimetry using fondaparinux as a ligand, and zeta potential measurement indicated that OVAX retained the heparin-binding affinity (Kd = 0.185 ± 0.037) even after 10 D incubation of fertilized egg, although the affinity was slightly decreased during egg incubation because of acidification of molecular surface charge. In conclusion, although heparin-binding ability of egg-white OVAX slightly decreases during embryogenesis, OVAX incorporated into embryo can retain heparin-binding affinity. Our findings provide a new insight that OVAX participates in the functions of heparin during embryogenesis.
卵清白蛋白相关蛋白 X（OVAX）是一种 50kDa 的蛋清蛋白，具有肝素结合亲和力。在这项研究中，研究了受精鸡蛋胚胎发生过程中 OVAX 的迁移及其肝素结合性能，以探索其在鸡胚胎发育中的可能作用。使用抗 OVAX 抗体对不同阶段的蛋黄进行 Western blot 分析表明，OVAX 在受精鸡蛋孵化过程中积累在蛋黄中。对 10 天孵化的鸡蛋中胚胎的免疫组织化学分析表明，OVAX 存在于胚胎的几乎所有组织中。这表明 OVAX 通过卵黄囊从蛋清中被掺入胚胎中。肝素琼脂糖层析、使用磺达肝素作为配体的等温滴定量热法和 ζ 电位测量表明，即使在受精鸡蛋孵育 10 天后，OVAX 仍保留肝素结合亲和力（Kd = 0.185 ± 0.037），尽管由于分子表面电荷的酸化，亲和力在鸡蛋孵化过程中略有下降。总之，尽管蛋清 OVAX 的肝素结合能力在胚胎发生过程中略有下降，但掺入胚胎的 OVAX 仍能保留肝素结合亲和力。我们的研究结果提供了一个新的见解，即 OVAX 参与了肝素在胚胎发生过程中的功能。
