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Objective To investigate whether PLA2 is involved in ZP-stimulated acrosomal exocytosis,if Ca^2 is required for activation of PLA2,and sigal transduction pathways modulating PLA2. Methods Guinea-pig spermatozoa were capacitated and labeled in low Ca^2 medium with [^14C]choline chloride or [^14C] arachidonic acid,and were then exposed to millimolar Ca^2 and various reagents and stimulated with ZP. Results Precapacitated spermatozoa exposed to millimolar Ca^2 and stimulated with ZP experienced increases in arachidonic acid(AA)and lysophosphatidylcholine (lysoPC) and a parallel decrease in phosphatidylcholine (PC);these chages are indicative of PLA2 activation.Simulation with ZP also led to acrosomal exocytosis in a high proportion of spermatozoa. Lipid changes and exocytosis were prevented if spermatozoa were exposed to aristolochic acid,a PLA2 inhibitor, before treatment with ZP.Stimulation with ZP in medium without added Ca^2 ,or in medium with millimolar Ca^2 and EGTA or La^3 resulted in no lipid changes or exocytosis. Pretreatment with pertussis toxin,a G1 protein inhibitor, before stimulation with ZP,blocked the release of AA and lysoPC and acrosomal exocytosis.Exposure of spermatozoa to the DAG kinase inhibitor R59022 before ZP stimulation led to a significant increase in the generation of lysoPC and exocytosis.Conclusion These results indicate very strongly that PLA2 plays an essential role in ZP-induced exocytosis in spermatozoa, that PLA2 activation requires Ca^2 internalization,and that it is regulated by signal transduction pathways involving G proteins and DAG. 相似文献
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目的 为了探讨HA是否参与ZP诱发的AR,它的激活是否依赖于Ca^2 的存在以及HA在豚鼠精子AR过程中的信号转导通路。方法 将豚鼠精子悬浮在最小获能培养基(MCM-LCa^2 ,23μM/LCa^2 )中预培养1h后,用[^11C]氯化胆碱或[^11C]花生四烯酸(AA)标记精子,并持续获能培养5h。经间断percoll密度梯度(30%~55%~85%)离心、洗涤。并将精子重新悬浮于MCM—LCa^2 培养其中。然后暴露于1mM/LCa^2 和/或ZP、百日咳毒素(PIX)、PLA2抑制剂、EGTA和甘油二脂激酶抑制剂(DAGKI),15分钟。精子膜脂类的提取、分离和鉴定采用Roldan和Varquer(1996)所报道方法。同时部分精子用相差显微镜检测AR百分率。结果获能精子Ca^2 /ZP合并应用后,可进一步加速AA释放和溶血磷脂酰胆碱(LysoPC)产生。同时伴有磷脂酰胆碱减少(这些变化是PLA2活性的指征)。Ca^2 /ZP的刺激亦导致精子AR率的增高;上述效应可被PLA2抑制剂马兜铃酸所阻断;采用PIX(G蛋白抑制剂)作用于已获能精子。结果发现由ZP引起AA和LysoPC含量升高以及AR率增加的效应均可被PIX抑制;23μMCa^2 存在下。精子虽不发生AR,但AA释放和LySoPC生成仍维持于较低的水平,而加入2mMEGTA(Ca^2 螫合剂)或250μMCa^2 (Ca^2 通道阻滞剂)可抑制HA的激活,导致AA和LySoPC的生成降低。DAG激酶抑制剂及K59022可加速AA及LySoPC产生,并促进口激发的AR。结论 上述结果表明,PLA2在四诱发豚鼠精子AR过程中起着关键作用,其激活仅需要低钙参与,同时PLA2活性受DAG和G蛋白介导信号转导通路的调控。 相似文献
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老年性白内障手术治疗是目前国际公认的最有效的治疗方法。我院自2007年1月1日至2008年12月31日成功的为110例白内障病人实施了超声乳化+人工晶体植入术。现将在配合手术过程中的一些护理体会总结如下。 相似文献
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甲基狄戈辛是狄戈辛的衍生物,具有与狄戈辛相同的生理活性。通过5名志愿者分别交叉单次口服上述两种药物制剂后,采用放射免疫法测定不同时间的血药与尿药浓度。从血药浓度测得的数据,求得的生物利用度,都显示甲基狄戈辛片比狄戈辛片对肠胃道吸收具有迅速、完全等特点。当达到生物等效与相同临床效果时,前者剂量仅为后者的3/5。 相似文献
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During interaction with the oocyte, sperrnatozoa are stimulated to undergo exocytosis of the aerosome, a process essential for fertihzation. Two main agonists of exoeytosis have been identified in the oocyte vestments : progesterone (P4), which is trapped in the matrix of the cumulus oophorus 相似文献
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DNA切除修复试验可用作检测化学物质的致突变性。用人类外周血淋巴细胞DNA切除修复试验检测化合物(甲基对硫磷、杀螟松、P_(204)、抗矽—14)致突变性。结果表明:甲基对硫磷、P_(204)能诱导程序外DNA合成大量增加,切除修复试验阳性。杀螟松、抗矽—14阴性。 相似文献
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