FONDAP Center for Genome Regulation, Faculty of Sciences, University of Chile, RM 7800003 Santiago, Chile.
Laboratory of Systems Microbiology, Faculty of Sciences, University of Chile, RM 7800003 Santiago, Chile.
Biomolecules. 2020 Sep 3;10(9):1274. doi: 10.3390/biom10091274.
In the teleost egg, the embryo is immersed in an extraembryonic fluid that fills the space between the embryo and the chorion and partially isolates it from the external environment, called the perivitelline fluid (PVF). The exact composition of the PVF remains unknown in vertebrate animals. The PVF allows the embryo to avoid dehydration, to maintain a safe osmotic balance and provides mechanical protection; however, its potential defensive properties against bacterial pathogens has not been reported. In this work, we determined the global proteomic profile of PVF in zebrafish eggs and embryos, and the maternal or zygotic origin of the identified proteins was studied. In silico analysis of PVF protein composition revealed an enrichment of protein classes associated with non-specific humoral innate immunity. We found lectins, protease inhibitors, transferrin, and glucosidases present from early embryogenesis until hatching. Finally, in vitro and in vivo experiments done with this fluid demonstrated that the PVF possessed a strong agglutinating capacity on bacterial cells and protected the embryos when challenged with the pathogenic bacteria Our results suggest that the PVF is a primitive inherited immune extraembryonic system that protects the embryos from external biological threats prior to hatching.
在硬骨鱼的卵中，胚胎被浸泡在一种充满胚胎和卵黄囊之间空间的胚外液中，这种液体会部分地将胚胎与外部环境隔离开来，这种液被称为卵周隙液（PVF）。在脊椎动物中，PVF 的确切组成仍然未知。PVF 允许胚胎避免脱水，维持安全的渗透平衡，并提供机械保护；然而，它对细菌病原体的潜在防御特性尚未被报道。在这项工作中，我们确定了斑马鱼卵和胚胎中 PVF 的全局蛋白质组学特征，并研究了鉴定出的蛋白质的母源或合子来源。对 PVF 蛋白组成的计算机分析显示，与非特异性体液固有免疫相关的蛋白类富集。我们发现了从早期胚胎发生到孵化都存在的凝集素、蛋白酶抑制剂、转铁蛋白和糖苷酶。最后，我们通过体外和体内实验表明，该 PVF 对细菌细胞具有很强的凝集能力，并在胚胎受到致病性细菌的攻击时为其提供保护。
我们的研究结果表明，PVF 是一种原始的遗传免疫胚外系统，它在孵化前保护胚胎免受外部生物威胁。
