Stith B J, Espinoza R, Roberts D, Smart T
Biology Department, University of Colorado at Denver 80217-3364.
Dev Biol. 1994 Sep;165(1):206-15. doi: 10.1006/dbio.1994.1247.
Although it is known that all fertilization events are due to elevated intracellular calcium ([Ca2+]i), it is not known how sperm induce an increase in zygote [Ca2+]i. We report that sperm can increase inositol 1,4,5-trisphosphate in Xenopus laevis eggs that have been preinjected with calcium buffers to prevent the increase in [Ca2+]i (both the initial increase and the subsequent wave) after fertilization. After buffering [Ca2+]i to levels well below basal, IP3 production was not blocked, whereas IP3 metabolism may be inhibited. Also, heparin (an inhibitor of inositol 1,4,5-trisphosphate action and the fertilization response) does not prevent a normal increase in IP3 after fertilization. Conditions that produce various levels of polyspermy are associated with IP3 increases similar to those noted after monospermic fertilization. These data suggest a specific order of fertilization events: sperm utilize an initial production of inositol 1,4,5-trisphosphate to produce the [Ca2+]i increase at fertilization.
尽管已知所有受精事件都归因于细胞内钙升高（[Ca2+]i），但精子如何诱导合子[Ca2+]i增加尚不清楚。我们报告，在预先注射了钙缓冲剂以防止受精后[Ca2+]i增加（初始增加和随后的波动）的非洲爪蟾卵中，精子可增加肌醇1,4,5-三磷酸。在将[Ca2+]i缓冲至远低于基础水平后，IP3的产生并未受阻，而IP3的代谢可能受到抑制。此外，肝素（肌醇1,4,5-三磷酸作用和受精反应的抑制剂）并不能阻止受精后IP3的正常增加。产生不同程度多精受精的条件与单精受精后观察到的IP3增加相似。这些数据表明了受精事件的特定顺序：精子利用肌醇1,4,5-三磷酸的初始产生来在受精时产生[Ca2+]i增加。
