Brawley S H
Department of General Biology, Vanderbilt University, Nashville, Tennessee 37235.
Dev Biol. 1987 Dec;124(2):390-7. doi: 10.1016/0012-1606(87)90491-x.
More than 70% of Pelvetia fastigiata eggs and about 15% of Fucus distichus eggs become polyspermic when fertilized at natural sperm concentrations in a low-sodium (2.5 mM Na+, 450 mM N-methyl glucamine) artificial seawater. Natural levels of polyspermy are 1-3% for both species. Polyspermic eggs germinate and respond to photopolarization, but do not develop beyond an abnormal, "stumpy," four-cell stage. They die within 1-1.5 weeks. The sodium-dependent block is a fast block, and it is replaced by a second block (probably cell wall formation) no later than 9 min (Pelvetia) after eggs are shed. The sodium-dependent block in Pelvetia is very efficient; when external sodium is raised to only 47.5 mM, the level of polyspermy drops to about 25%. These results are compared with data on marine invertebrates in the context of factors such as the sperm/egg concentration at fertilization and natural, osmotic (salinity) stress.
在低钠（2.5 mM Na⁺，450 mM N - 甲基葡糖胺）人工海水中，以自然精子浓度受精时，超过70%的鹿角菜卵子和约15%的叉枝藻卵子会发生多精受精。这两个物种的自然多精受精水平均为1 - 3%。多精受精的卵子能够萌发并对光偏振做出反应，但发育不会超过异常的“短粗”四细胞阶段。它们会在1 - 1.5周内死亡。钠依赖性阻断是一种快速阻断，并且在卵子排出后不迟于9分钟（鹿角菜）被第二种阻断（可能是细胞壁形成）所取代。鹿角菜中的钠依赖性阻断非常有效；当外部钠浓度仅升高到47.5 mM时，多精受精水平降至约25%。在受精时的精子/卵子浓度和自然渗透（盐度）应激等因素的背景下，将这些结果与海洋无脊椎动物的数据进行了比较。
