SPERM MOTILITY IN THE HORSESHOE-CRAB .4. EXTRACELLULAR IONS AND INTRACELLULAR PH ARE NOT MEDIATORS OF MOTILITY INITIATION
SPERM MOTILITY IN THE HORSESHOE-CRAB .4. EXTRACELLULAR IONS AND INTRACELLULAR PH ARE NOT MEDIATORS OF MOTILITY INITIATION
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DOI：
10.1002/mrd.1120060405
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发表时间：
1982-01-01
期刊：
影响因子：
--
通讯作者：
EPEL, D
中科院分区：
文献类型：
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作者：
CLAPPER, DL;EPEL, D
当稀释到海水中时，鲎精子经历短暂的运动（持续时间< 60 s），之后它们是不运动的，直到遇到来自卵的精子运动起始肽（SMI）。利用高度纯化的SMI提取物和简化的海水配方（从其中删除个别离子），没有特定的细胞外离子是稀释启动或SMI启动的运动所需的。删除1个离子（Na+）产生的稀释启动的运动的持续时间很长（几个小时）。当由SMI（在正常海水中）启动运动时，细胞内pH（pHi）增加，如荧光探针9-氨基吖啶所示;这种pHi变化不是运动的触发因素。作为检测离子运动的更通用方法，使用荧光探针diS-C3-（5）定性测量精子膜电位的变化。虽然粗SMI提取物引起膜去极化，进一步纯化导致几乎完全分离的SMI，这表明SMI激活显然是一个电中性事件。(The膜去极化因子的分子量> 30，000，不引发顶体反应。）利用离子载体A23187 [卡西霉素]和Ca+2-阻断剂（维拉帕米和TMB-8 [8-（N，N-二乙基氨基）辛基-3，4，5-三甲氧基苯甲酸酯]）的实验提供了初步证据，表明运动启动可能需要细胞内Ca+2的动员。无论是在pHi的变化，也不流入特定的细胞外离子SMI启动的运动的直接介质，药理学试剂的实验表明细胞内Ca+2的可能作用。
Upon dilution into sea water, Limulus spermatozoa undergo a brief flurry of motility (duration < 60 s), after which they are nonmotile until encountering a sperm motility initiating peptide (SMI) that emanates from eggs. Utilizing highly purified SMI extracts and simplified seawater formulations (from which individual ions were deleted), no specific extracellular ion is required for either dilution-initiated or SMI-initiated motility. Deletion of 1 ion (Na+) produced dilution-initiated motility of very long duration (several hours). When motility is initiated by SMI (in normal seawater) there is an increase in intracellular pH (pHi), as indicated by the fluorescent probe, 9-amino acridine; this pHi change is not a trigger for motility. As a more general method examining ion movements, the fluorescent probe diS-C3-(5) was used to qualitatively measure changes in the membrane potential of spermatozoa. Although crude SMI extracts caused membrane depolarization, further purification resulted in an almost complete separation of this activity from SMI, showing that SMI activation is apparently an electroneutral event. (The membrane-depolarizing factor has a MW > 30,000 and does not initiate acrosome reactions.) Experiments utilizing the ionophore A23187 [calcimycin] and Ca+2-blocking agents (verapamil and TMB-8 [8-(N,N-diethylamino)octyl-3,4,5-trimethoxybenzoate]) provided tentative evidence that mobilization of intracellular Ca+2 may be required for motility initiation. Neither changes in pHi nor the influx of specific extracellular ions are direct mediators of SMI-initiated motility; experiments with pharmacologic agents indicate a possible role for intracellular Ca+2.