The Bivalve Egg's Lectin Recognizing Sperm Glycosphingolipid

从淡水双壳类(Hyriopsis Schlegelii)精子中分离得到一种酸性鞘糖脂，其结构为：GlcA4Me 1-4[GalNAc3Me 1-3]GUC 1-4GlcNAc 1-2man 1-3[Xy1 1-2]Man 1-4Glc 1-1 Ceramine。这是一种独特的糖脂，因为4-O-甲基葡萄糖醛酸和内部定位的岩藻糖是以糖残基的形式存在的，也被认为是专门存在于双壳类精子的细胞表面，按分类属于双壳类精子。这些内在事实让我们探索精子-卵子相互作用的可能角色。然后，通过与载脂的辛基琼脂糖亲和库仑层析，我们试图从100,000克的三角帆蚌卵匀浆的上清液中提取识别酸性脂质的某些物质。该提取物能凝集某些双壳类物种的精子，也能凝集含酸性脂类的脂质体。在SDS-聚丙烯酰胺凝胶电泳法上，大部分提取物出现在表观分子质量为100K、80、60K、40K和20 KDa的5个区带。所有的化合物都能直接与~3H标记的酸性脂质结合，这表明在20 KDa的产物中发现了初步的结合活性。将紫贻贝活卵与用提取物预先孵化的精子混合，发现完全抑制受精。

An acidic glycosphingolipid was isolated from spermatozoa of the fresh-water bivalve, Hyriopsis schlegelii, and it was found to have the following structure: GlcA4Me 1-4[GalNAc3Me 1-3] Guc 1-4GlcNAc 1-2Man 1-3[Xy1 1-2]Man 1-4Glc 1-1Ceramide. This is a unique glycolipid, in that a 4-O-mathylglucuronic acid and an internally located fucose are contained as sugar residues and also thought to exist specifically on the cell surface of the bivalve spermatozoa placed taxonomically in the Veneridae, Unionidae and mytilidae. These intrinsic facts let us explore possible roles for sperm-egg interaction. Then, by affinity coulumn chromatography with the octyl-Sepharose carrying lipid, we tried to extract certain substances that recognize the acidic lipid from a 100,000 x g supernatant of the Hyriopsis egg homogenates. The extract was demonstrated to agglutinate spermatozoa from certain bivalve species, and also the acidic lipid-containing liposomes. On SDSpolyacrylamide gel electrophoresis, the majority of the extract was confirmed to the bands within the five regions of apparent molecular mass: 100K, 80, 60K, 40K, and 20KDa. All of them were found to directly bind to ^3H-labelled acidic lipid, and this indicated that the initial binding activity was found in a production of the 20KDa. When living Mytilus edulis eggs were mixed with sperm preincubated with the extract, it was found to completely inhibit the fertilization.