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首页> 外文期刊>Fish Physiology and Biochemistry >Acquisition of the potential for sperm motility in steelhead (Oncorhynchus mykiss): effect of pH on dynein ATPase
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Acquisition of the potential for sperm motility in steelhead (Oncorhynchus mykiss): effect of pH on dynein ATPase

机译：获得钢头（Oncorhynchus mykiss）精子活力的潜力：pH对动力蛋白ATP酶的影响

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摘要

Salmonid sperm pre-incubated at extracellular pH (pH(e)) values less than about 7.4 do not become motile upon water activation whereas sperm maintained above about pH 8.0 demonstrate maximal motility upon activation. The basis for this permissive effect of elevated pH(e) on sperm motility is not known. Since it is conceivable that the pH sensitivity of dynein ATPase ( the molecular motor that drives flagellar movement) could be the basis of, or contribute to this pH dependency, the pH sensitivity of this enzymatic activity was evaluated in membrane-permeabilized axonemes ( isolated flagella) of steelhead sperm. Dynein ATPase activity was found to be sensitive to pH. This activity in permeabilized axonemes was about 3.5-fold higher at pH 7.6 compared to 7.0. To determine whether the pH sensitivity of ATP regeneration might affect the interpretation of the effect of pH on dynein ATPase activity, the pH sensitivities of creatine kinase and adenylate kinase were established. The rates of ATP generation by these enzymes were insensitive to pH between 6.5 and 8.0. The results of these studies are consistent with the hypothesis that prior maintenance at pH(e), in part, controls the potential for sperm motility upon water activation via an influence on dynein ATPase activity. However, the potential for motility of steelhead sperm is particularly sensitive to prior maintenance at pH(e) values between about 7.4 and 8.0 whereas the dynein ATPase activity of permeabilized axonemes was particularly sensitive to pH values between 7.0 and 7.6. Phosphorus NMR spectroscopy was used to determine that sperm intracellular pH (pH(i)) increased with increasing pHe between 7.0 and 8.5 and pH(i) was, on average 0.4 - 0.5 pH units lower than pH(e). Therefore the pH(e) sensitivity of the potential for motility appears to correspond to the pH(i) sensitivity of dynein ATPase activity. The data indicate that pH(i) is directly related to pH(e) and that prior incubation at pH(e) may, in part, control the sperm's potential for motility upon water activation via an influence on dynein ATPase activity.
机译：在细胞外pH（pH（e））值小于约7.4的条件下预温育的鲑鱼精子在水活化后不活动，而在pH 8.0以上维持的精子在活化后表现出最大运动性。 pH（e）升高对精子运动的这种允许作用的基础尚不清楚。由于可以认为动力蛋白ATP酶（驱动鞭毛运动的分子马达）的pH敏感性可能是该pH依赖性的基础或对此有依赖性，因此在膜透化的轴蛋白（分离的鞭毛）中评估了这种酶活性的pH敏感性）的顽固精子。发现Dynein ATPase活性对pH敏感。与7.0相比，在pH 7.6时透化的轴突中的这种活性高约3.5倍。为了确定ATP再生的pH敏感性是否会影响pH对动力蛋白ATPase活性的解释，建立了肌酸激酶和腺苷酸激酶的pH敏感性。这些酶的ATP生成速率对6.5和8.0之间的pH不敏感。这些研究的结果与以下假设相一致：在pH（e）之前维持在一定程度上通过影响动力蛋白ATPase活性来控制水活化后精子活力的潜力。然而，杆头精子的运动潜力对先前维持在约7.4至8.0的pH（e）值特别敏感，而透化的轴突的动力蛋白ATP酶活性对7.0至7.6的pH值特别敏感。磷核磁共振光谱法用于确定精子细胞内pH（pH（i））在7.0和8.5之间随pHe的增加而增加，而pH（i）的平均pH值比pH（e）低0.4-0.5。因此，运动潜能的pH（e）敏感性似乎对应于动力蛋白ATPase活性的pH（i）敏感性。数据表明pH（i）与pH（e）直接相关，并且事先在pH（e）孵育可能会通过影响动力蛋白ATPase的活性而部分控制水激活后精子的活力。

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