Florman H M, First N L
Department of Meat and Animal Science, University of Wisconsin, Madison 53706.
Dev Biol. 1988 Aug;128(2):464-73. doi: 10.1016/0012-1606(88)90308-9.
The effects of accessory sex gland secretions on the zona pellucida-induced acrosome reaction of bovine spermatozoa were investigated. Soluble extracts of zonae pellucidae initiated exocytosis in ejaculated spermatozoa. This process had an ED50 of 20 ng/microliter zona pellucida protein and saturated at 50 ng/microliter (Florman and First, 1988. Dev. Biol. 128, 453-463). In epididymal sperm this dose-response relationship was shifted toward greater agonist concentrations by at least a factor of 10(3). Reconstitution of high potency agonist response was achieved in vitro by incubation of epididymal sperm with bovine seminal plasma. Reconstitution was dependent on the seminal plasma protein concentration. The ED50 of this process was 62 micrograms protein/10(8) sperm and saturation was observed with 124 micrograms protein/10(8) sperm. Agonist responses in reconstituted epididymal sperm and in ejaculated sperm were indistinguishable with regard to dependence on the zona pellucida protein concentration and the kinetics of induced acrosome reactions. Kinetic studies suggest that reconstitution is due to adsorption of regulatory factors from seminal plasma. In addition to the positive regulatory elements responsible for reconstituting activity, seminal plasma also contains negative regulatory elements which inhibit agonist response. These negative factors are inactivated during sperm capacitation, permitting the expression of positive regulators. Acting together, these regulatory elements could coordinate high affinity agonist response with the availability of eggs in vivo.
研究了附属性腺分泌物对牛精子透明带诱导的顶体反应的影响。透明带的可溶性提取物可引发射出精子的胞吐作用。该过程的半数有效剂量（ED50）为每微升20纳克透明带蛋白，在每微升50纳克时达到饱和（弗洛曼和弗斯特，1988年。《发育生物学》128卷，453 - 463页）。对于附睾精子，这种剂量反应关系向更高的激动剂浓度偏移了至少10³倍。通过将附睾精子与牛精浆孵育，可在体外实现高效激动剂反应的重建。重建依赖于精浆蛋白浓度。此过程的ED50为每10⁸个精子62微克蛋白，在每10⁸个精子124微克蛋白时观察到饱和。重建后的附睾精子和射出精子中的激动剂反应在对透明带蛋白浓度的依赖性以及诱导顶体反应的动力学方面没有区别。动力学研究表明，重建是由于从精浆中吸附调节因子所致。除了负责重建活性的正调节元件外，精浆还含有抑制激动剂反应的负调节元件。这些负因子在精子获能过程中失活，从而使正调节因子得以表达。这些调节元件共同作用，可在体内将高亲和力激动剂反应与卵子的可利用性相协调。
